ENJINIERBuletin Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral

Bulletin for the School of Materials and Mineral Resources Engineering Universiti Sains Malaysia

JIL. 05 BIL. 02 No. ISSN: 1511-5275 http://www.usm.my Disember 2002

JANGAN MENJAUHKANDIRI DARIPADAPERSATUAN

Nibong Tebal - 17hbJulai 2002. Prof. MadyaDr Ahmad Fauzi MohdNoor menasihatkan pela-jar-pelajar supaya tidakmenjauhkan diri daripa-da persatuan.

Nasihat ini dibuatoleh Dr Fauzi semasa memberi ucapan diMesyuarat Agung tahunan PersatuanKejuruteraan Bahan dan Sumber Mineral(MIMATES).

Dr Fauzi menambah lagi tujuan per-satuan ialah membantu pelajar dengansecara tidak langsung, terutamanya bagipelajar-pelajar yang bermasalah.

Beliau menambah lagi bahawa semuapelajar di pusat pengajian digalakkanmemainkan peranan yang aktif dalamMIMATES. Ini termasuklah pelajar-pelajaryang mengikuti program KejuruteraanPolimer, yang merupakan ahli baru PusatPengajian Kejuruteraan Bahan danSumber Mineral.

Dr Fauzi berharap pelajar-pelajar dari-pada kejuruteraan polimer tidak merasatersisih hanya disebabkan nama pusatpengajian seolah-olah melambangkanhanya dua rancangan pengajian sahaja.Nama pusat pengajian tidak ditukarkerana polimer boleh didefinasikan seba-gai sebahagian daripada kejuruteraanbahan.

Tambah beliau lagi, “diharapkan pela-jar cuba sebaik mungkin untuk memper-olehi keputusan peperiksaan yang baikkerana ada syarikat yang hanya mengam-bil pekerja lepasan universiti yang mem-perolehi CGPA 3.0 ke atas”.

GE Fund scholarship

Kuala Lumpur - 19 November. A firstyear student of the Mineral ResourcesEngineering programme was one of the

eight students fromvarious universitiesin Malaysia that wereawarded the GE(General Electric)Fund Scholarship.

The student wasNurul Izza Ismail andthe award was held ina simple ceremony

organised by the Malaysian AmericanCommission for Educational Exchange(MACEE) held at the Renaissance Hotel.

The scholarship was awarded by theGeneral Electric, an Americal InternationalCompany. Dr Polard said that the awardwere given of to high performance stu-dents.

Dr Polard who is a repsentative ofGeneral Electric added that Kofi Annan,the UN Secretary General was one of theStudents Exchange Programme atMacalister College in United States and hehope that may be one day one of thesestudents may follow the steps of KofiAnnan or may become a great inventor.

The photograph above shows a new equipment in the Mineral Processing Laboratory.It is a Grinding and Classifying System equipment that can be operated as aclassifying system or as jet mill system or as a classifier mill. As a jet mill materialscan be grounded as fine as 3 mm.

RAMM 20033rd INTERNATIONAL

CONFERENCE ON RECENT ADVANCESIN MATERIALS, MINERALS AND

ENVIRONMENT

5 - 7 May 2003

Organised by:School of Materials & Mineral Resources

Engineering,Engineering Campus USM,

14300 Nibong Tebal, Penang, Malaysia.

Location:The Bayview Beach Resort,

Batu Ferringhi Beach, Penang.

Further information can be obtained fromthe school’s web page through the USM’sweb page at http://www.usm.my . Enquiries can also be made through e-mailat ramm2003@ eng.usm.my .

Nurul Izza Ismail

Bengkel PerancanganStrategik RancanganMalaysia ke 8oleh: En. Mokhtar Alfakari Anurbek

Pulau Pinang, 23hb Ogos - SatuBengkel Perancangan Strategik telahdiadakan oleh Pusat PengajianKejuruteraan Bahan dan Sumber Mineral(PPKBSM) di Copthorne Orchid Hotel,Pulau Pinang selama tiga hari daripada23hb Ogos hingga 25hb Ogos.

Bengkel ini bertujuan untuk membin-cang dan menilai semula perancanganstrategik yang telah digubal pada bengkelyang sebelum ini telah diadakan di LumutPerak pada 10 hingga 11hb Mac 2001.

Bengkel ini dihadiri oleh semuaperingkat kakitangan di PPKBSMtermasuk semua staf KejuruteraanPolimer yang sejak bulan April yang lalutelah menjadi sebahagian daripada ahlikeluarga PPKBSM.

Beberapa kertas kerja telahdibentangkan oleh Prof. Madya DrKhairun Azizi Mohd Azizli, Dekan PPKBSM,Prof Madya Dr Zainal Arifin Ahmad,Pengerusi Rancangan KejuruteraanBahan, dan Profesor Dr Zainal AriffinMohd Ishak, Pensyarah KejuruteraanPolimer. Antara topik yang dibentangkanadalah berkaitan dengan AgendaPengantarabangsaan Universiti danJaminan Kualiti.

Semua staf dipecahkan kepada beber-apa bahagian untuk membincangkanperkara-perkara dan masalah yang sediaada yang perlu diselesaikan dalam hubun-gan untuk mencapai agenda-agenda yangtelah dibincangkan oleh pembentang ker-tas kerja.

Setiap kumpulan diberi peluang mem-buat persembahan atas semua masalahyang timbul termasuk perkara yang bolehdikatakan sensitif kepada sesuatu pihak.Namun demikian semua perbincangandibuat dengan semangat muhibah danbertujuan untuk menyelesaikan masalahbukanlah untuk menuding jari siapakahyang bersalah atu siapakah yang bertang-gung jawab.

Menurut Dr Khairun di dalam ucapanpenutupan bengkel, semua saranan dankritikan hasil daripada bengkel tersebutakan diambilkira dan dinilai satu persatutanpa ada sebarang pengecualian olehJawatankuasa Pemantauan yang akandibentuk dalam masa terdekat ini, sebaiksahaja semua peserta kembali bertugas.Laporan daripada jawatankuasa tersebut

akan disampaikan kepada Naib Canselor.

Khemah KerjaKecemerlanganKepimpinan untuk pelajar tahun pertamaoleh: Mohd Nazri Idris

Pulau Pinang, 4 Ogos – Seramai 210orang pelajar tahun pertama sesi2002/2003 telah menghadiri KhemahKerja Kecemerlangan Kepimpinan yangtelah diadakan oleh pusat pengajian ini diKem Biro Tata Negara, Pasir Panjang,Balik Pulau, Pulau Pinang.

Aktiviti ini telah diadakan pada 2hingga 4 Ogos yang lalu dengankerjasama sekumpulan kakitangan PusatPengajian Kejuruteraan Bahan danSumber Mineral, pelajar-pelajar Ijazahtinggi, Persatuan Kejuruteraan Bahan DanSumber Mineral serta pelatih-pelatih dari-pada Biro Tata Negara Kem BTN BalikPulau.

Aktiviti ini merupakan tradisi pusatpengajian yang dijalankan pada setiaptahun. Khemah kerja ini bertujuan untukmerapatkan hubungan pelajar denganpusat pengajian dan memberi semangatkepada pelajar supaya mempunyai dayasaing untuk cemerlang, berhemah tinggidan mempunyai daya tahan yang kental.

Untuk mencapai tujuan itu banyakaktiviti-aktiviti ceramah dan motivasidilaksanakan dengan pendedahan kepadapelajar-pelajar terhadap kaedahpembelajaran yang tersusun dan mantapsebagai persiapan mereka untukmenghadapi sistem pengajian diuniversiti yang tentunya berbeza dengansistem persekolahan biasa.

Aktiviti-aktiviti yang menarik adalahgerak kerja berkumpulan yang melibatkanantara pelajar-pelajar dan kakitanganpusat pengajian. Aktiviti ini berjayamenarik minat dan mencungkil kebole-han pelajar-pelajar untuk berkomunikasidan berenteraksi dengan pelbagai lapisansekaligus memberikan paduan integrasikaum yang harmoni.

Seiring dengan hasrat melahirkangraduan yang cerdas dan cergas, pelajar-pelajar juga didedahkan dengan aktiviti‘abseiling’ dan merempuh halangan.

Tidak ketinggalan aktiviti-aktiviti kero-hanian dan moral juga diadakan untukmelahirkan insan yang sempurna,cemerlang dan berpekerti tinggi.Kemuncak kepada segala program iniadalah aktiviti ‘Jungle tracking’ yangdiadakan pada hari ketiga khemah kerja.

Khemah kerja ini berakhir denganucapan penutup oleh Yang BerbahagiaDato’ Profesor Madya Jamaludin Mohaidiniaitu Timbalan Naib Canselor Hal EhwalPelajar Universiti Sains Malaysia.

Sidang Pengarang

Sidang Pengarang Enjinier men-jemput semua staf, pelajar-pelajardan graduan PPKBSM memberi sum-bangan rencana dan pandanganmereka kepada:

Sidang Pengarang Enjinier,Pusat Pengajian Kejuruteraan Bahandan Sumber Mineral,Kampus Kejuruteraan,Universiti Sains Malaysia,14300 Nibong Tebal.

The Enjinier Editorial Board invites allstaff, students and graduates of theSchool of Materials and MineralResources Engineering to contributearticles and views to:

Enjinier Editorial Board,School of Materials and MineralResources Engineering, EngineeringCampus, Universiti Sains Malaysia, 14300 Nibong Tebal.

Ir Mior Termizi Mohd Yusof(Ketua Pengarang)

Prof. Madya Dr Zainal Arifin Ahmad

Encik Samayamutthirian Palaniandy

Encik Mohd Nazri Idris

BANJIR KILAT -PERKARA BIASA

Kampus Kejuruteraan - 14hb November. Banjir kilat seperti inimerupakan perkara biasa di Pusat Pengajian KejuruteraanBahan dan Sumber Mineral pada musim hujan. Banjir iniberlaku setelah hujan lebat selama satu jam pada waktu ten-gahari.

Hujan renyai-renyai turun lagi pada pukul lebih kurang5.00 petang. Pada keesokan hari air telah surut dan air hanyaterdapat di dalam longkang sahaja.

Motosikal danKeselamatanoleh: Ir Mior Termizi Mohd Yusof

29hb November. Sidang makmalbermula pada 8.30 pagi. Tajuk makmalpada hari itu ialah rekabentuk peletupan.Sidang makmal ini tidak boleh dibuatseperti kelas makmal yang lain keranabahan letupan yang sebenar tidak bolehdigunakan di dalam kelas dan jugaundang-undang Malaysia tidak membe-narkan praktikal penggunaaan bahanletupan dibuat di universiti kerana tiadatempat yang sesuai.

Berbeza di luar negara sepertiCamborne School of Mines, England,praktikal penggunaan bahan letupandibuat dengan menggunakan bahanletupan yang sebenar. Namun demikiantahap berjaga-jaga dan keselamatan diUK boleh dikatakan baik kerana penyeliayang mengendalikan bahan letupanhendaklah mempunyai pengalaman danlesen daripada kerajaan British.

Maka di USM makmal ini dibuatseperti kelas biasa dan latihan mengenairekabentuk peletupan dibuat dan

dihantar pada hari itu juga. Denganbilangan pelajar yang sedikit bagai sesimakmal ini, diharapkan pelajar bolehmempelajari sedikit sebanyak mengenaiasas rekabentuk peletupan untuk kegu-naan perlombongan dan pengkuarian.

Sebelum kelas bermula seorangpelajar belum datang lagi. Lebih kurangsetengah jam kemudian pelajarberkenaan muncul dan memberitahubeliau lambat kerana mengalamikemalangan motosikal semasa di per-jalanan. Pelajar ini sebagai pemboncengtidak mengalami apa-apa kecederaantetapi kawannya yang membawa moto-sikal mengalami sedikit kecederaan.Kemalangan ini berlaku di pekan ParitBuntar. Penulis tidak menyiasat lebih lan-jut sama ada benarkah kemalangan iniberlaku. Namun demikian penulis ter-panggil untuk menulis sedikit sebanyakmengenai keselamatan menunggangmotosikal.

Apabila berlaku kemalangan inipenulis teringat tentang beberapakemalangan yang melibatkan pelajar USMsemasa menunggang motosikal dan adayang maut.

Dengan ini penulis ingin memberisedikit nasihat kepada pelajar yang

menunggang motosikal dan begitu jugamemberi peringatan kepada diri penulissendiri yang telah dan masihmenunggang motosikal sejak tahun 1979lagi. Penulis bersyukur kepada tuhankerana sehingga kini penulis tidak pernahlagi terlibat dengan kemalangan yangmengakibatkan kecederaan.

Berjaga-jagaPerkataan berjaga-jaga memang

senang disebut tetapi di Malaysia khusus-nya pengguna jalan raya kurang berjaga-jaga sama ada penunggang motosikaldan juga pemandu kenderaan lain.

Sekiranya di England, pemandukenderaan akan memberhentikan keretasekiranya dia nampak pejalan kaki hen-dak melintas. Tetapi di Malaysia seki-ranya kita sebagai pemandu kereta mem-berhentikan kereta untuk melepaskanpejalan kaki melintas, sudah pastikenderaan di belakang kita membunyikanhonnya. Ini bermakna memanduberhemah di Malaysia masih lagi padatahap yang mendukacitakan

Apabila menunggang motosikal pula,anda mestilah sepuluh kali gandaberjaga-jaga jika dibandingkan dengan

(bersambung di mukasurat 4)

memandu kereta. Ini adalah kerana seorang penung-

gang motosikal yang sedang memandulaju, keadaannya umpama telur dihujungtanduk. Sama ada ia melanggar atau pundilanggar atau tergelincir atau terbabassudah pasti penunggang motosikal akanmengalami kecederaan.

Dalam kempen keselamatan jalanraya di televisyen ada menyebut “2/3kemalangan motosikal bukan disebabkanoleh kecuaian penunggang”. Maka 1/3lagi disebabkan oleh kecuaian penung-gang. Jadi bagaimanakah kita hendakmengelakkan diri daripada terbabit den-gan kemalangan yang disebabkan olehkecuaian pemandu-pemandu kenderaanyang lebih besar daripada motosikal?

Jawapan yang sudah pasti kepadapersoalan ini dan yang paling selamatsekali ialah jangan menunggang moto-sikal. Tetapi bagi mereka yang kurangmampu seperti pelajar universiti danmereka yang berpendapatan rendah,motosikal adalah satu mod pengangkutanyang mudah dan murah dan juga bolehsampai ke destinasi sepertimana yangdirancangkan kerana motosikal bolehmengatasi masalah kesesakan lalulintas.

Defensive RidingPenulis masih ingat semasa membuat

latihan memandu kereta di England untukmendapatkan lesen memandu keretapada tahun 1981. Pada masa itu penulistelah pun mempunyai lesen motosikalsemasa di Malaysia lagi.

Instruktor yang mengajar penulismemberi nasihat supaya pandang jauh kehadapan dan cuba mengambil tindakankepada apa yang berlaku di hadapansebelum terlambat.

Nasihat ini penulis ingat sehingga kinikerana nasihat ini telah menyelamatkanbeliau, semasa menunggang motorsikal,daripada dilanggar oleh seorang peman-du mabuk di Selayang, Kuala Lumpur.

Semasa menunggang motosikal, kela-juan hendaklah mengikut keadaan jalan-raya dan sudah tentulah menurutundang-undang yang sudah ditetapkan.

Sekiranya menunggang dalamkeadaan jalanraya yang basah dan jalanyang berpasir, jangan memandu terlalurapat dengan kenderaan di hadapan.Motosikal hanya mempunyai dua rodadan memerlukan jarak yang lebih jauhjika dibandingkan dengan kereta untukmembuat pemberhentian kecemasan.

Semasa menunggang motrosikal hen-daklah sentiasa memikirkan ruang untukmengelak daripada apa-apa keadaanbahaya yang disebabkan oleh kecuaiankenderaan lain dan sentiasa elakkan diridaripada kedudukan yang tidak bolehdilihat (blind spot) oleh pemandukenderaan hadapan.

Dalam keadaan jalan yang sesak tidakboleh dielakkan kedudukan yang rapatdengan kenderaan di hadapan, makadalam keadaan ini jangan ikut betul-betuldi belakang kenderaan, tetapi ke tepisedikit, sekiranya kenderaan di hadapanberhenti dengan serta-merta, sekurang-kurangnya penunggang tidak menghen-tam belakang kenderaan.

Sekiranya ada kenderaan yang inginmemotong, benarkan ia memotong.Tiada faedahnya kita berlumba dengan-nya. Walaupun kebanyakan motosikalyang mempunyai injin 130 cc ke atasboleh mencapai kelajuan yang bolehmengalahkan kebanyakan kenderaan dijalanraya.

Penyengaraan motosikalPengetahuan tentang injin merupakan

suatu kelebihan tetapi tidak semestinyasatu keperluan. Sekurang-kurangpengetahuan asas mengenai keperluaninjin dan bahagian lain seperti tayar,rantai dan brek sudah memadai.

Motosikal hendaklah sentiasa dipasti-kan dalam keadaan selamat. Ini bolehdibuat dengan menghantar motosikaluntuk diservis pada waktu-waktu tertentuatau selepas beberapa ribu kilometer.Cuba ambilkira semua pengesyoranmekanik yang menyenggara motosikalanda.

Rantai motosikal jangan dibiarkan ter-lalu kendur. Sproket motosikal jangandibiarkan sudah haus sehingga giginyatinggal sedikit sahaja. Dalam keadaan inijangan kedekut, tukar kedua-dua sproketdan rantai sekali. Baru-baru ini adaseorang penunggang motosikal terjatuhdan cedera teruk kerana rantai jatuh dantersangkut dicelah roda membuatkanroda belakang berhenti berputar seolah-olah brek kecemasan dibuat. Ini adalahkerana gigi sproket sudah haus.

Tayar motosikal pula jangan dibiarkanjadi licin baru hendak ditukar. Tidakmemadai wang yang cuba dijimatkankerana bayaran yang “tinggi” terpaksaditanggung sekiranya tayar pecah diperjalanan. Pastikan brek, lampu signal,lampu hadapan dan cermin di kiri dankanan berfungsi dengan baik.

Nasihat di atas jika diikuti bolehdikatakan memerlukan sedikit perbelan-jaan, terutamanya motosikal yang ber-kuasa tinggi. Jika ini merupakan masalahbesar sebagai pelajar universiti, makaberhenti daripada menaiki motosikal dangunakan basikal untuk ke kuliah. Penulismenghadapi masalah ini semasa sebagaipelajar universiti dan pernah membeliempat buah basikal semasa belajar diUTM dan juga di England. Harga empatbuah basikal ini tidaklah semahal sebuahmotosikal.

SIJIL DEKAN SEMESTER 1

SIDANG 2002/2003

KEJURUTERAAN BAHAN

Tahun 1Lim Ling ChingLim Soo WahLum Sek Yew

Tahun 2Cho Cheong ChangChua Boon KweanEng Koo MooiFoong Yuan WeiIliana IsmailKoay Yi EeLarry Tan Chun HaiLu Lian SoonMok Boon YongNorazean ShaariTan Sek SeanTay Poh LeongTee Dee InVegneswary a/p RamalingamVemal a/l Raja ManikamWong Yoke PeiLee Jian HueiPuan Lee Ban

Tahun 3Chum Pak KuanLaw Choon LinLim Su HongLooi Ming HooiNg Mui PingNoraiham MohamadOoi Lee ChuanSeow Eng HengZaileen Suhaili Saari

KEJURUTERAAN SUMBER MINERAL

Tahun 1Tiada

Tahun 2Ee Xun Hong

Tahun 3Chen Chee SiungDewi Suriyani Che HalinGan Szu MinIntan Sharhida OthmanLai Lee ChiouWong Hon Cheng

KEJURUTERAAN POLIMER

Tahun 1Liew Chee Foo

(daripada mukasurat 3)

Bengkel Microscopy 17 - 18hb Oktober 2002diadakan Pusat Pengajian KejuruteraanBahan dan Sumber Mineral

Mendengar taklimat dengan penuh minat. Dr Shamsul Baharin sedang menerangkan peralatanyang digunakan.

Encik Hassan Zuhudi juga tidak melepaskan peluangmemberi sumbangan dalam bengkel ini.

Scanning-Electron Microscopy (SEM)

Prof. Madya Dr Ahmad Fauzi memberi penerangan tentangseramik.

Menjamu selera setelah penat berbengkel.

The Kinetics ofIlmenite Chlorinationwith CarbonTetrachloride AtLower Temperatures

Abdullah, N.S.*, Azizan, A.* and Kamarudin, H.**

*School of Materials and Mineral ResourcesEngineering, Engineering Campus, USM**Northern College University of Engineering Malaysia, 09000, Arau, Perlis.

AbstractA study was done on the kinetics of

ilmenite chlorination using carbon tetrachlo-ride at different sizes (-45+38ìm, -53+45ìmand –75+53ìm) and temperatures (673K,723K and 773K). By obtaining the weight lossof ilmenite briquettes during the process atcertain times, the fraction reacted wasattained. The data was then fitted into kineticmodels with the aid of a curve fittingsoftware, CurveExpert v1.3.

At all temperatures and sizes, it was wellobserved that the reaction fits very well withthe core shrinking model, 1-(1-x)1/3 = kt,where x is the fraction of ilmenite reacted intime, t, with k being the rate constant, withlinear correlations of more than 0.97 in allcases.

The activation energy of the process wasfound between the ranges of 49 to 53 kJmol-1,strongly suggesting the overall reaction wouldbe a chemically controlled one, complement-ing the core shrinking model, which is actual-ly a topochemical reaction scheme.

IntroductionWith special properties, such as high

strength-to-weight ratio and highcorrosion and erosion resistances,titanium metal and alloys are presentlyattracting much attention (Sohn andZhou, 1999).

Sources of titanium included naturalrutile and ilmenite, with the latter beingabundant locally, found as a component intin mining waste. However, most methodsof direct smelting and treatment using thealkaline and acid routes to recovertitanium were found unsuccessful.

Chlorination, which happens to showgreat success in treating complex ores,offers an interesting alternate route forilmenite treatment, producing intermedi-ate compounds in the form of metalchlorides, which would be useful for latterprocesses (Augusto and Oliviera, 2001).

Separation of these metal chlorideswould result in metal segregation, andthis could simply be achieved byfractional distillation, knowing the factthat each metal chloride has its owncondensation limit (Ozaki, 1999).

In this study, the chlorination process,

with carbon tetrachloride as the chlorinat-ing agent, is used to obtain continousreaction of ilmenite chlorination, as analternative to the conventional directsmelting methods.

In studying the extent of the chlorina-tion process, the reaction kinetics of theprocess is scrutinized, and the reactionpattern was fitted to a kinetic model. Thekinetic models, which actually are anobservation of the rate process atdifferent conditions, condensed into anequation of multiple variables, gave afantastic overview of how a reaction actu-ally progresses.

Various models namely the coreshrinking, the nucleation and growth, theJander’s and the pore blocking respective-ly were few of many equated to fit therate process of reactions, thus possiblysupplying a concrete route to predict theoutcome of certain reaction under multi-ple conditions.

Present WorkIn this experiment, the ilmenite raw

samples, obtained from a local amangprocessing plant were grounded in aceramic ball mill, then sieved intodifferent size fractions after cone andquartering.

The samples were then made intobriquettes, pressed at 1400 kg/cm2, usinga Carver closed 13.0 mm die. Eachbriquette was prepared without the aid ofbinders, weighing approximately 2.1-2.3grams, and were all nearly uniform inshape, with an estimated diameter andheight of 13.0mm and 4.0mm respective-ly. These briquettes were then dried in at1100C and were then stored in adessicator before chlorination.

Chlorination was done by placing abriquette in a marlite boat, then placed inthe center of a borosilicate glass tube,positioned horizontally in a resistanceheated Carbolite electric furnace. Thefurnace was then heated to a desiredtemperature with air removed by flushingoxygen free nitrogen into the tube, at aconstant flow of 160 ml/min, observed bya Cole Palmer flowmeter. Trial runs withempty boats gave no loss of weight,showing no reaction between the boatand the gaseous carbon tetrachloride.

Carbon tetrachloride was introducedinto the system by heating a flask con-taining 300 ml of the substance at 840C(±10C) in a waterbath. The flask was thenattached to the borosilicate tube and thecarbon tetrachloride vapour, carried byoxygen free nitrogen at a steady flow of160 ml/min, was passed through the

tube-containing sample in the furnace.The exhaust gas flowing out of the tubewas scrubbed using 0.1M potassiumhydroxide.

At desired time, the flow of carbontetrachloride was stopped and thereacted sample was then cooled under asteady flow of oxygen free nitrogen toroom temperature. The sample is thenweighed and the weight loss is recorded.

ResultsFrom the weight loss data, it would

be possible to obtain a kinetic model thatwell represents the ilmenite-carbontetrachloride reaction, at differenttemperatures, particle sizes and times.

It could be seen that in figures 1through 4 that linear plots could be seenfor the core shrinking model against timegraphs, giving an exceptional fit, withlinear corellations being better than 0.97in all cases. The weight loss data was alsofitted to various other models, withoutsuccess.

Fig. 1-The fraction weight loss for vari-ous sizes against time at 673K

Plots of ln k against 1/T were alsomade, with the slopes bearing theactivation energy. The Ea values werefound to be in the region of 49-53kJmol-1,with coarser particles giving higher activa-tion energy.

Fig. 2- Core shrinking model againsttime for –75 +53m particles

Fig. 3- Core shrinking model againsttime for -53 +45m particles

Fraction Weight Loss Against Time at 673K

0.00

0.25

0.50

0 15 30 45Time (minutes)

Fra

ctio

n

Wei

gh

t L

oss

45 mic 53 mic 75 mic

Chlorination offers an interesting alternate route forilmenite treatment

Core Shrinking Model Against Time

y = 0.003xR2

0

0.1

0.2

0 20 40 Time(minutes)

Cor

e S

hrin

king

M

odel

Core Shrinking Model Against Time

00.050.1

0.150.2

0 20 40Masa (minit)

Cor

e S

hrin

king

M

odel

1-(1-x)^(1/3) Linear (1-(1-x)^(1/3))

Fig. 4-Core shrinking model against timefor -45 +38m particles

Conclusion and Future Work The possibility of low temperature

chlorination of ilmenite could be realizedusing carbon tetrachloride as thechlorinating agent. Individual oxide datais currently obtained, and will be analyzedwith strong belief of preferentialchlorination taking place.

References1. Habashi F., 1997, Handbook of ExtractiveMetallurgy Vol. II, Wiley-VCH, 1129-1176.2 Azizan, A., 1995, Studies on the Chlorination ofStruverite and Related Minerals, PhD Thesis, UniversitiSains Malaysia, 61-823. Augusto, E. B. and Oliveira, H. P., 2001, Kinetics ofChlorination and Microstructural Changes of Xenotimeby Carbon Tetrachloride, Metallurgical and MaterialsTransactions B, 28B, 371-387 5. Sohn, H. Y. and Wadsworth, M. E., 1979, RateProcesses of Extractive Metallurgy, Plenum Press, 1-49.6. Kunago, S. B. and Mishra, S. K., 1997, Kinetics ofChloridization of Nickel Oxide with Gaseous HydrogenChloride, Metallurgical and Materials Transactions B,28B, 371-3877. Altekar, V. A. and Athavale A. A., 1969, ChemicalBeneficiation of Chromite by Selective Chlorination ina Fluidized Bed, Transactions of Indian Institute ofMetals, 22, 29-37.8. Sankaran, C., Misra, R. N. and Bhatnagar, P. P.,1968, Selective Chlorination of Iron From Ilmenitewith Hydrochloric Acid Gas, Advances in ExtractiveMetallurgy, Institution of Mining and Metallurgy,London, 480-500.9. Rhee, R. I. and Sohn H. Y., 1990, The SelectiveChlorination of Iron from Titaniferous Magnetite Orein a Fluidized Bed, Metallurgical Transactions B, 21B,341-347.

THE IMPORTANCEOF GRINDING IN

CEMENT MANUFACTURING

75% of electric energy consumption is consumed ingrinding processes

Fiesal Musa and Assoc. Prof. Dr. Khairun Azizi

Cement is considered as one of themost important building materials aroundthe world. Cement consumption andproduction is closely related to construc-tion activity, and therefore to the generaleconomy activity.

Due to the importance of cement as aconstruction material, and the geographic

abundance of the main raw material, i.e.limestone, cement is produced virtually allcountries.

Portland cement is made primarilyfrom a combination of calcium carbonatefound in calcareous rock such as lime-stone, silica, alumina and iron oxide foundin argillaceous rock such as clay or shale.It consists of approximately 80%limestone, 15-20% clay or shale andabout 2-5% of sand or iron ore additives.

Portland cement is manufactured bygrinding a mixture of these raw materials,burning them at a clinkering temperatureand in the end, fine grinding the resultingclinker.

Grinding of raw materials and clinkerto a great extend determines the econo-my of the cement production. And since75% of electric energy consumption isconsumed in grinding processes, it isimportant to pay particular attention tothis major cost item.

The grinding process in cementmanufacturing starts at grinding the rawmaterials to produce what is called theraw mix.

The grinding system either by ballmills or vertical roller mills must bedesigned to grind the raw materials topowder form, fine enough for burningin the kiln. This is because, in cementmaking, uniformity of composition andfineness must be obtained in order toproduce a proper blended material forheat treatment.

The raw mix must be intimately mixand of sufficient fineness to ensure thatproper combination can take place in thekiln. In achieving this, grinding must be atits best.

Insufficient grinding of the rawmaterials can lead to so many problems.For example, coarser raw mixes requirehigher burning temperature in the kiln.This is because, sintering rate is roughlyproportional to the inverse of particle size.

It has been observed that burning isrelatively easy if the particle size is small.The fineness of raw mixes should be inthe range of 100-200µm for theproduction of general-purpose Portlandcement, and 50-60µm for the productionof high-strength cement.

The combinability between lime com-ponent (CaO) and silica (SiO2) during theclinkerization process is difficult toachieve if the size of the raw mixes islarge.

The critical size for minerals such ascalcite and quartz in the raw mix lie in the

range of approximately 50-100µm. Rawmix that has not been ground efficientlywould therefore give problem to the com-bination process which would results inhigher free lime clinker.

A large amount of free lime in theresulting clinker would mean that the rawmix is not completely burned in the kiln. Aclinker with free lime content above 2%can affect the quality of cement byreacting with water to produce limeexpansion [CaO + H2O Ca(OH2)] inthe mortar and concrete during thehydration of cement. This eventuallyaffects the strength of cement/concrete.

The formation of clinker microstruc-tures (alite and belite) is also affected bythe fineness of the raw mix, in otherwords, the efficiency of the grinding andmilling of the raw materials.

It has been experimentally observedthat raw mixes containing larger mineralsproduced larger alite and belite crystals(see Plate 1). A clinker with larger aliteand belite crystals can slower down thehydration process and thus, lowering theinitial and final strength of the cement.

Plate 1: Large alite and belite crystalsformed from insufficient grinding of rawmixes.

The importance of grinding continuesto the end of the processes in cementmaking. At this stage, the clinker pro-duced must be grounded with theaddition of 5% gypsum to a certain fine-ness (surface area above 300m2/kg) togive cement product.

The fineness of cement productdetermines the strength and also thesetting time. Cement product with thecorrect fineness was observed to producehigher early strength and requiredshorter setting time.

It is therefore impossible to deny theimportance of grinding in the manufactur-ing of cement. Since grinding is an impor-tant and influential unit, not only incement manufacturing, but also in everyindustry that requires size reduction,much attention has to be paid to this unit.

References:1. Duda, W. H. (1979). Cement Data Book. 2ndEdition. Germany. Bauverlag. GmbH2. Fundal, E. (1979). Burnability of Cement RawMixes. World Cement Technology.

Alite Belite

Core Shrinking Model Against Time

y = 0.0021xR20

0.1

0.2

0 20 40 60Masa (minit)

Cor

e S

hrin

king

M

odel

1-(1-x)^(1/3) Linear (1-(1-x)^(1/3))

Cement product with correctfineness produces higherearly strength and requiresshorter setting time

THE ROLE OF MINERAL INDUSTRY

TOWARDSTHE NATION

DEVELOPMENTSThe demand for minerals is directlyrelated to the economic activity of thecountry

by:Samayamutthirian Palaniandy and Khairun

Azizi Mohd Azizli

samaya@ eng.usm.my and khairun@eng.usm.my

The Malaysian minerals industrycontinues to play a significant role in theeconomic development of the country byproviding the necessary inputs to theother sectors of the economy especiallythe construction, infrastructure and man-ufacturing sectors. The robust growth ofthe Malaysian economy over the pastdecade had increased the demand forminerals resources1.

The demand for minerals is directlyrelated to the economic activities of thecountry. For the period 1993 to mid-1997,strong growth in construction and manu-facturing sectors had increased mineralconsumption by 5% to 13%, dependingon the types of minerals. Table 1 showsthe comparison of the growth rate of theconstruction industry and the quarryingindustry before, during and after theeconomic crisis. Fluctuation of growthrate of these two industries shows a verystrong contribution of the mineralindustry towards the development of theconstruction industry. Continued strongdemand for locally sourced minerals,particularly industrial minerals as well asimported minerals to support Malaysia’sindustrialisation programme, had

increased the overall domestic mineralconsumption2.

Although the construction industryshows a negative growth rate, the quar-rying industry still surviving with 0.8%growth rate in 1998 due the demands of

rocks for the completion of various megaprojects such as the Kuala Lumpur CityCentre, KLIA, major expressways andother infrastructure projects contributedfor the demand. Figure 1 shows the valueof the overall mineral production inMalaysia. Figure 1 also supports thatthere is a strong correlation between GDPand the mineral production values. In1998 the GDP was -7.8% and the mineralproduction was reduced by 11.9%. In1999 a massive recov-ery of the GDP wasobserved where it was6.1% and increase byanother 2.2% in 2000.Indication of a steadyfair growth of the con-struction industry hasa direct impact on themining and quarryingindustry.

The mineralsindustry basically canbe divided into threemain groups, namelymetallic, non-metallicand energy min-erals4. The industrycovers the wholerange of activitiesfrom exploration andmining to the manu-facturing of mineral-based products.Currently the mineralbase industry inMalaysia is morefocusing on the nonmetallic minerals ascan be observed in

Figure 2. Non-metallic miner-als presently beingproduced inMalaysia includeaggregates, clay,kaolin, limestone,silica, feldspar aswell as sand and

gravel. The non metallic minerals con-tribute more than 80% of the total miner-als production in Malaysia. During the cri-sis period, the non-metallic mineralsproduction was declining but it starts

picking up after 2000. An interestingfactor during the crisis period is the boostof the metallic minerals production. Theincremental of the metallic minerals dur-ing the crisis period by 3% - 4% may dueto the boosting of the US$ currency. Theenergy mineral also plays an importantrole as Malaysia’s consumption on energyminerals especially coal was around 3.0million tonnes and the large coalconsumer are the power generation plant

and the cement plant. It is wise to say that mineral industry

is the one of the most important pillarwhich supports the nation developmentby supplying raw materials to otherindustries such as construction,infrastructure and manufacturing sectors.Although Malaysia had passed the gloryyears in the tin mining, the mineralindustry will always contributes towardsnation developments because “Lookaround you, anything you see –either you grow it or YOU MINEIT!!!!!!!”.

Figure 1 : Production figures of minerals and growth ratepercentage from 1996 to 20011.

0

500

1000

1500

2000

2500

3000

1996 1997 1998 1999 2000 2001

YearP

rodu

ctio

n V

alue

, R

M m

illio

n

-10

-8

-6

-4

-2

0

2

4

6

8

10

12

GD

P G

row

th,

%

Minerals Productions GDP

Figure 2: Production value of metallic, non-metallic and energy mineral from 1996 to 2002 3.

0

500

1000

1500

2000

2500

1996 1997 1998 1999 2000 2001Years

Min

era

ls p

roduct

ions

valu

es,

RM

millio

ns

Metallic Non.metallic minerals Energy

Table 1: Growth rate of construction and quarrying industry

No. Sector Pre EconomicCrisis GrowthRate(1996)

Growth RateDuring CrisisPeriod(1998)

Growth Ratein 2001

1. Construction 11.8% -24.5% 3.2%

2. Quarrying andMining

2.7% 0.8% 6.5%

References

1. Samayamutthirian, P. and Khairun Azizi, M. A.,(2001); Heat Generation In Planetary Mill During FineGrinding Process Of Silica(Proceedings of NationalSeminar on Advanced Materials Development inMalaysia- 2001, Johor Bahru, Malaysia)2. Profile Of Malaysia’s Primary Comodities, MinistryOf Primary Industry Malaysia. 8th Issue. (2000), 1433. Ir. Sukeri Osman. (2002). The Scenario InMalaysia’s Mineral Sector. Dialog Mineral 2002. 9-10September 2002. Ipoh Perak.4. Khairun Azizi, M. A. & Azizan A., (2002); ResearchDevelopment in the Mineral Sector through SmartPartnership (Proceedings of national QuarryConference 2002, Kuala Lumpur Malaysia.)

Kemunculan PorselinGigi Tempatan – Harga Patut

PPKBSM sedang membuat usahauntuk menghasilkan porselin gigi

tempatan.

Zainal Arifin Ahmad danWan Mohd Arif W. Ibrahim

Pusat Pengajian Kejuruteraan Bahan &Sumber Mineral

zainal@eng.usm.my

Pengenalan

Pernahkah anda terfikir mengapa satubidang kedoktoran yang khusus diwujud-kan, iaitu Doktor Gigi? Pengkhususan inimenunjukkan tahap keperluan dankepentingannya dalam penjagaankesihatan gigi manusia.

Kita mungkin berpengalaman merasaiseksanya apabila ‘sakit gigi’, ‘gigiberlubang’, ‘rasa ngilu’, ‘cabut gigi’,‘tampal gigi’ dan lain-lain. Kita merasakanserba serbinya tidak selesa hanyalahdisebabkan oleh masalah yang berkaitandengan ‘gigi’ tersebut. Apatah lagi jikasatu atau beberapa batang gigi depantercabut atau terpaksa dicabut – bukansahaja tidak dapat merasai kenikmatanmengunyah makanan, tetapi hendakkeluar rumah pun terasa segan (khusus-nya jika anda masih muda remaja!!). Bila‘angin’ sudah tiada penghadangnya,perkataan yang dituturkan sudahberlainan bunyi sebutannya. Atausenyuman anda tidak semanis dulu.Inilah di antara pengalaman biasa yangterpaksa ditempuhi jika kita menghadapimasalah gigi.

Doktor gigi akan membantu sebolehmungkin agar gigi asal tidak dimus-nahkan (dicabut). Maka beliau akanmenampal gigi tersebut. Tetapi jika tidakboleh diselamatkan terpaksalah ‘gigipalsu’ dipasang. Anda mungkin perlumemasang “crown”, “bridge”, “veneer”

atau “ tanam semula gigi”. Teknologi yang ada pada hari ini

dapat memberikan anda “restorasi gigi”yang nampaknya mempunyai estatikadan kilauan seperti gigi asli. Perbezaanyang ada pada restorasi ini ialah jenisbahan yang digunakan dan harganya.

Bahan restorasi pergigian bolehdihasilkan menggunakan bahan-bahanseperti berikut:

Resin Akrilik Logam seperti emasPorselin danKomposit

Yang terbaik dan menghampirikeadaan semulajadi gigi asli ialahporselin. Sifat-sifat utama gigi asli dapatdiikuti dengan baik oleh gigi porselen ini.Antara sifat-sifat tersebut ialah:

Warna dan kilauan (estatik)Pekali pengembangan terma KekerasanKekuatanTindakan pelarut

Malangnya, porselin gigi TERSANGATMAHAL jika dibandingkan dengan bahanlain. Harga minimum untuk restorasisebatang porselin gigi ialah RM550.00(Malaysian Dental Association) berband-ing dengan RM30.00 untuk akrilik. Antaraalasan yang penting mengenai perbezaanini ialah kerana porselen gigi adalahterdiri daripada 100% produk import.Maka kami telahpun menjalankan penye-lidikan sebagai menyahut cabaran ini.Kami mampu menghasilkan porselin gigipada harga yang jauh lebih murah –mungkin sepertiga dari harga pasaran.

Penggunaan Porselin Gigi

Porselin telah menyumbangkankepada pelbagai aplikasi dalam bidangpergigian sejak diperkenalkan lebih 200tahun dahulu. Pada ketika itu, porselindigunakan dalam pembuatan gigi palsu.Seterusnya hasil daripada penyelidikanporselin, porselin gantian penuh telahdibangunkan untuk tujuan restorasi padabahagian permukaan anterior gigi yangrosak.

Perkembangan pesat dalam bidangteknologi porselin pergigian adalah ketikaera penghasilan porselin ikatan logam(Porcelain Fused Metal - PFM).

Penghasilan PFM ini telah membawasatu dimensi baru dalam bidang pergi-gian dan diguna pakai oleh seluruhmasyarakat hingga sekarang. Restorasisecara PFM ini telah menghasilkan peng-gantian gigi yang mempunyai nilai estatikyang tinggi dan mampu menghasilkanrupa bentuk yang hampir sama dengangigi asal.

Pada permulaan dekad lepas, hasildari perkembangan teknologi yang pesat,porselin gantian penuh telah dihasilkan.

Perkembangan ini secara tidak langsungtelah meningkatkan teknik dan kemajuanbahan porselin. Secara amnya, sifat esta-tik bagi porselin gantian penuh adalahmungkin lebih baik berbanding porselinikatan logam disebabkan keseluruhanketebalan restorasi porselin gantianpenuh adalah terdiri daripada porselin.Namun demikian, porselin gantian penuhini masih tidak mampu untuk menandingikekuatan restorasi PFM.

Pembuatan Gigi Porselin

Asasnya gigi porselin terdiri daripadatiga lapisan. Lapisan dalam koronaporselin biasanya dibuat daripada bahanteras yang legap dan disaluti denganlapisan dentin yang lebih lutcahaya danseterusnya lapisan enamel yang jugalutcahaya, membentuk lapisan palingluar.

Rajah 1: Pembahagian setiap lapisandalam porselin gigi

Penghasilan restorasi porselin inimemerlukan seni dan kerja yang tekunbagi menjamin mutu hasilan yang cantikdan mempunyai nilai estatik yang tinggi.

Rajah 2: Model gigi dibentuk dari serbukporselin menggunakan berus khas,

Rajah 3: Bentuk gigi disediakan untukproses pensinteran.

Rajah 4: Kerja akhir dijalankan ke atasgigi porselin.

Rajah 5: Gigi porselin dibandingkandengan gigi porselin piawai untuk menilaihasil akhir.

Penyelidikan di PPKBSM

Di Pusat Pengajian KejuruteraanBahan dan Sumber Mineral (PPKBSM),USM, usaha sedang dijalankan untukmenghasilkan bahan porselin pergigian.Hasil penyelidikan ini dijangka mampumenyaingi porselin pergigian komersial dipasaran.

Porselin gigi ini yang dihasilkan den-gan felspar sebagai bahan asas dandicampurkan dengan bahan tambahanlain diproses kepada bentuk serbuk seba-gai hasil akhir. Proses pensinteranmemainkan peranan yang sangat pentingdalam menentukan hasil akhir penghasi-lan porselin pergigian ini. Suhu sekitar900°C hingga 1300°C telah digunakandalam proses pensinteran ini.

Hasil yang diperolehi dikaji secarapemerhatian langsung dan juga beberapaanalisis dan ujian seperti ujian mekanikaldan kimia. Perbandingan dengan piawa -ian ISO dijadikan asas untuk membuk-tikan mutu porselin yang dihasilkan.

Kesimpulan

Daripada kajian yang dijalankan kitasebenarnya mampu menghasilkanporselin gigi secara tempatan.Penghasilan ini pastinya akan dapat men-gurangkan kos pembuatan gigi porselinberbanding porselin pergigian komersialimport. Harga patut yang ditawarkanpasti dapat memberi peluang kepadalebih ramai pengguna.

Penghargaan

Penulis menghargai geran penyelidikanJangka Pendek yang telah diberikan olehUniversiti Sains Malaysia.

The low velocityimpact response of

foam-based sandwich structures

by:Md. Akil Hazizan and W.J. Cantwell

IntroductionSandwich structures based on strong,

stiff composite skins bonded to a lowdensity core material are findingincreasing use in aerospace, offshore andmarine industries.

One of the main drawbacks of thesehigh-performance structures is theirrelatively poor resistance to localizedimpact loading [1-4]. A number of workershave investigated the impact response ofsandwich structures and an excellentreview is given in ref. [2]. Horrigan et al.[1]

conducted experimental and theoreticalinvestigations on a Nomex honeycombstructure with glass fibre epoxy skinswhereas Charles and Guedra-Degeorges [5]

showed that the dent depth around theimpact point increases with impactenergy until a maximum value is reached.

The aim of the present work is todevelop and apply an energy-balancemodel similar to that outlined by Abrate [2]

in order to predict the impact response ofa foam-based sandwich structure. Theaccuracy of the model will be investgatedby varying the incident energy of thefalling impactor as well as the propertiesof the foam core.

Experimental procedureEleven sandwich structures were

evaluated during the course of thisresearch programme.

Impact tests were conducted using aninstrumented falling-weight impact toweras shown in Figure 1. A 1.98 kg carriagewith 10 mm diameter hemisphericalindentor was released from heights of upto 1.0 m. Incident impact energies gener-ated was in the range of 0.1 – 1.97 Jwhich was achieved by varying the dropheight.

The rate-sensitivity of the 11 foammaterials and the skins was investigatedby conducting three point bend tests. Theimpact response of the sandwichstructures was modelled using an energy-balance model. Here, it is assumed thatthe target responds quasi-statically duringthe impact event and that the kineticenergy of the target is absorbed inbending, shear and contact effects. The

energy-balance for the sandwichstructure is therefore:

where P is impact force, D is the flexuralrigidity of the skins, A is the geometricalparameter that depends on the thicknessof the core and skins and beam width, Gis the shear modulus and C and n are con-stants which were determined experimen-tally in this study.

ResultsThe variation of the flexural modulus

of the composite skin with crossheaddisplacement rate is shown in Figure 2.Here, it is clear that the flexural modulusof the glass reinforced composite skinsdoes not vary with loading rate with thevalue of Ef averaging approximately 29GPa at all crosshead displacement rates.

The rate sensitivity of four of the foammaterials is shown in Figure 3. Anexamination of the data indicates that allfour systems exhibit a rate-insensitiveresponse with the flexural modulusremaining constant over the threedecades of loading.

Figure 4 shows the variation of themaximum impact force with impact ener-gy for two of the linear PVC foams. The

data for 50 kg/m3 foam show an initialrise in force with increasing impactenergy before reaching a plateau atapproximately 170 N.

The agreement between the modeland the experimental value is goodwithin the elastic limit of the material.Agreement between the model and theexperimental data improves significantlyin higher density system.

ConclusionLow velocity impact tests on the

sandwich structures have shown that thedynamic response of these systemsdepends on the elastic properties of thefoam core material.

For a given impact energy, themaximum impact force, Pmax, tend toincrease with increasing shear modulus,G.

It has also been shown that a simpleenergy-balance model based on thedissipitation of energy during the impactevent can be used to predict the lowvelocity impact response of sandwichstructures in the elastic regime.

AcknowledgementThe authors acknowledge the financial

support of the University Sains Malaysia. Theauthors are also grateful to Dr Lukas Berger forsupplying the foam materials and Mr MarcusErath of Stesalit Ltd, Switzerland for supplyingthe composite materials.

( )( )

1nC/PC

AG4L

D48L

2P

mv21 n/1n

max3

max2

2

++

+=

+

ReferencesHorrigan DPW, Aitken RR, Moltschaniwskyj G.

Modelling of crushing due to impact in honeycombsandwiches. J Sandwich Struct Mater 2000;2:131-51

Abrate S. Localised impact on sandwich struc -tures with laminated facings. Appl Mech Rev1997;50:70-82

Ishai O, Hiel C. Design of highly damage-tolerant

sandwich panels. 37th Int SAMPE Symp Exhibit1992:1228-42.

Nettles AT, Hodge AJ. Impact testing ofglass/phenolic honeycomb panels with

graphite/epoxy face sheets. Proc 35 th Int SAMPESymp Exhibit 1990:1430-40

Charles JP, Guedra-Degeorges D. Impact damage

tolerance of helicopter sandwich structures. Proc 23rd

Int SAMPE Conf 1991:51-61

Figure 1: Schematic of the impact test arrangement

Figure 2: The variation of the flexural modulus of thecomposite skin with crosshead displacement rate

Figure 3: The variation of the flexural modulus of fourfoam systems with crosshead displacement rate.

Figure 4: The variation of the maximum impact forcewith impact energy for two linear PVC foams. Thearrows indicate the damage threshold energy and thesolid lines represent the predictions of the energy-bal -ance model.

Pengurusan danlangkah-langkah

keselamatan makmalOleh

Mohd Nazri IdrisPusat Pengajian Kejuruteraan Bahan Dan

Sumber Mineral

Setiap institusi pendidikan sama adaperingkat rendah mahu pun padaperingkat institusi pengajian tinggi tidakdapat lari daripada menggunakan mak-mal yang merupakan komponen pentingda-lam pembangunan pendidikan.Pengguna-an makmal yang teratur den-gan aspek-aspek keselamatan serta pen-gurusan yang baik merupakan komponenpenting yang perlu dipertimbangkan.

Kesedaran terhadap pengurusan danpenggunaan yang tepat adalah pentinguntuk memberikan suasana kerja yangbaik dan terjamin.

Sehubungan dengan itu setiap peng-guna sama ada pihak kakitangan teknikalmahupun pelajar-pelajar perlu diberibimbingan serta panduan yang sempurnasebelum mereka menjalankan sesuatuujikaji atau ujian.

Matlamat pengurusan serta kesela-matan makmal ini hanya akan tercapaisekiranya semua peraturan dan proseduryang ditetapkan dilaksanakan dan initidak hanya mencukupi dengan pempela-jari secara teori sahaja.

Antara aspek-aspek penting yangperlu diberi perhatian oleh semua peng-guna makmal adalah aspek kebersihanmakmal, penggunaan peralatan makmalserta pengendalian komponen elektrik,penggunaan bahan-bahan ujikaji sertabahan mentah dan keadaaan suasanatempat kerja yang selamat.

Kegagalan dalam pengendalian asas-asas utama ini mungkin boleh menye-babkan kemalangan yang berbahayakepada pengguna itu sendiri atau kepadapengguna-pengguna lainnya.

Perkara pertama yang perlu diberiperhatian oleh setiap pengguna makmaladalah aspek kebersihan persekitaranmakmal. Sehubungan dengan itulangkah-langkah berikut perlu diseleng-garakan dengan sempurna.

Mempastikan kesemua alatan disusundan disimpan pada tempat yang selamatterutama barangan yang berada di lantaidan menghalang kawasan lalulintas.

Semua tumpahan bahan kimia perlusegera dibersihkan untuk mengelakkankemalangan sama ada pada penggunamakmal atau alatan-alatan makmal lain.

Mempastikan setiap makmaldilengkapi alat-alat keselamatan sepertipemadam api, ‘shower’, selimutkebakaran dan peti pertolongan cemasyang lengkap. Pastikan alatan ini dile-takkan pada tempat yang sesuai danmudah diperolehi.

Sisa kimia berlebihan perlu diletakkandi dalam botol khas yang dilebel denganjelas dan terang. Jangan sekali-kalimembuang sisa kimia kedalamsingki.

Setiap pengguna makmal perlu meng-gunakan kot makmal sepanjang mengen-dalikan ujikaji. Untuk keselamatan,elakkan memakai kot makmal semasaberada di bilik rehat atau di tempatmakan.

Jangan sekali-kali memakai seliparsemasa berada di dalam makmal. Iniboleh menyebabkan kemalangan seki-ranya berlaku tumpahan bahan kimiaberacun atau terkena serpihan alatanyang pecah.

Penggunaan kanta sesentuh adalahtidak digalakkan kerana jika berlaku per-cilakan bahan kimia beracun dan mudahmengkakis, larutan tersebut akan mudahmenyerap antara lensa dan mata.Pengguna juga dinasihatkan menggu-nakan cermin mata keselamatan semasamenjalankan kerja.

Bahan-bahan dan pelarut kimia perludilebel dengan jelas. Simpanan pelarutyang mudah terbakar perlu dihadkan den-gan kuantiti yang minimum. Sebahagianbahan perlarut perlu disimpan dalam storkimia.

Anda dilarang makan dan minumdidalam makmal. Merokok didalam mak-mal juga adalah berbahaya kerana iaboleh menyebabkan kebakaran atau letu-pan yang tidak diingini.

Tempat pembuangan sampah didalam makmal perlu diperbuat daripadabahan yang tidak mudah terbakar.Serpihan peralatan kaca yang pecah per-lulah diasingkan dari sampah yang lain.

Peralatan kacaKebanyakkan peralatan makmal

adalah diperbuat daripada barangankaca. Oleh itu peralatan-peralatan iniperlu dikendalikan dengan baik danberhati-hati. Umumnya peralatan kacadalam makmal terdiri daripada kaca sodalime dan kaca borosilikat. Kaca soda limeadalah tahan terhadap kakisan bahankimia tetapi mempunyai ketahanan kimiayang rendah. Manakala kaca borosilikatmempunyai ketahanan hakisan kimia danbahan api yang tinggi. Berikut adalahlangkah-langkah yang betul semasamenggunakan alat-alat radas kaca ini.

Hanya gunakan alat-alat radas kacayang mempunyai ketahanan haba yangtinggi semasa anda menjalankan kerja-kerja seperti pemanasan dan pencampu-ran bahan kimia yang mengeluarkanhaba.

Semasa menjalankan sejatan di dalambekas kaca, anda dinasihatkan janganmeninggalkan sejatan tersebut tanpadiawasi kerana ia akan menjadi keringdan kemungkinan akan meletup.

Jangan memindahkan alatan kaca

yang panas ke atas permukaan yangsejuk kerana ia akan menyebabkan alattersebut pecah.

Sentiasa menggunakan batu didihapabila anda perlu mendidih sesuatucampuran larutan atau air di dalam radaskaca seperti bikar dan kelalang. Ini akanmengurangkan gelembung-gelembungudara yang besar semasa larutan itumendidih.

Kebanyakkan makmal yang digunakantidak dapat lari daripada menggunakankomponen-komponen elektrik. Penge-tahuan asas yang mendalam tentangpengendalian komponen-komponenelektrik ini adalah penting ke arah mewu-judkan pengurusan makmal dan kesela-matan kerja yang baik.berikut adalahbeberapa perkara yang perlu diberi per-hatian semasa mengendalikan pendawa -ian elektrik dalam makmal.

PendawaianPendawaian sementara kepada per-

alatan elektrik adalah tidak digalakkan.Penggunaan ‘multi plug’ mestilah

dikawal untuk menghindarkan ‘overload-ing’ dan kemalangan elektrik.

Soket dan plug elektrik yang rosakperlulah ditukar dengan segera.

Jika eksperimen melibatkan pendawa -ian elektrik dan pengubahsuaian litar, iaperlu disambung dengan seberapa pen-dek yang boleh. Semua pendawaian perludijauhi daripada permukaan panas dankabel yang panjang diikat dengan kemas.

Jika sesuatu alatan menggunakanvoltan yang rendah. Anda perlu menggu-nakan ‘transformer’ yang sesuai.

Anda dinasihatkan jangan mengujiatau menggunakan alatan elektriksemalaman. Jika perkara ini perludilakukan, satu kenyataan atau amaranyang alat ini sedang dilakukan semala-man perlu dipamerkan. Kenyataan terse-but perlulah menyatakan siapa penggu-nanya, nombor telefon, dan bagaimanahendak dihubungi jika berlaku kece-masan. Nyatakan juga langkah-langkahyang perlu diambil sekiranya sesuatukemalangan berlaku semasa alat itu digu-nakan.

Jangan sekali-kali memegang suisatau sambungan elektrik dengan tanganyang basah atau berdiri di dalam air.

Selain daripada perkara-perkara diatas, ada beberapa perkara penting yangperlu diberi perhatian ketika mengenda-likan makmal terutama untuk tujuan-tujuan pengajaran dan penyelidikan.

1. penggunaan alat – jangan cubamenggunakan sesuatu alatan makmalsekiranya anda kurang pasti terhadappenggunaannya. Pastikan anda membacadengan teliti tatacara pengendaliannyadan tatacara ini perlu diikuti satu persatu.

2. Menguji kebocoran gas – cara yang

selamat adalah dengan menggunakanbuih sabun yang disapu kepada paip gasyang bocor itu. Jangan sekali-kali meng-gunakan api untuk menguji kebocorangas.

3. Penggunaan selinder gas termam-pat – selinder gas termampat seperti gasoksigen, nitrogen, helium, hidrogen dansebagainya perlu dekendalikan dalamkeadaan menegak. Jangan baringkanselinder gas di atas lantai. Semua selindergas perlu diikat dengan rantai besi yangkuat dan sesuai di tepi dinding.

4. Pengendalian cecair sejuk – jangansekali-kali membiarkan cecair ini terkenapada kulit atau mata anda kerana iniboleh menyababkan berlakunyakebakaran sejuk di atas kulit dan sukaruntuk dirawati. Cecair ini perlu disimpandi dalam termos khas dan ditutup denganlonggar.

5. Penggunaan asid pekat – asidpekat adalah bahan yang mudahmengkakis. Jika anda perlu untuk menye-diakan asid cair, anda perlu memasukkanasid ke dalam air dan bukan air ke dalamasid. Pastikan anda mengendalikan den-gan tepat dan gunakan cermin matakeselamatan serta kot makmal.

6. Memanaskan cecair yang mudahterbakar – jangan sekali-kali mem-anaskan dan menyejatkan cecair ini diatas penunu bunsen. Ini boleh menye-babkan kebakaran. Jika anda perlu mem-anaskan atau menyulingkannya, cecair iniperlulah dimasukkan ke dalam kelalangyang sesuai dan dipanaskan denganmenggunakan kukusan air panas.

7. Alat-alat yang mempunyai hujungyang tajam perlu digunakan dengan teliti.

8. Pemindahan peralatan dan bahan-bahan kimia – pemindahan peralatanmakmal dari satu tempat ke tempat yanglain perlu dikendalikan dengan betul.Pastikan peralatan diikat atau beradadalam keadaan yang selamat ketika kerja-kerja pemindahan dilakukan. Pemindahanbahan-bahan kimia perlu menggunakanbekas pembawa yang disediakan.

9. Penggunaan kebuk wasap – semuakerja-kerja yang melibatkan gas, wap danhabuk perlu dilakukan dalam kebukwasap. Pastikan kipas dan saluran paippengeluaran udara kebuk wasapberfungsi dengan baik untuk digunakan.

Pengurusan makmal yang baik adalahtanggungjawab setiap pengguna.Perlaksanaan ini tidak akan tercapai seki-ranya tiada kerjasama yang baik antarapelajar-pelajar dan kakitangan yang terli-bat.Jangan sekali-kali mengamalkan sikapmementingkan diri sendiri denganmengabaikan keselamatan orang lain.Setiap pengguna yang berpengalamandan berdidikasi sentiasa mengutamakanprinsip keselamatan, kebersihan danmemupuk sikap kerjasama dan bertang-gungjawab dengan pengguna-penggunalain.

Rujukan:

Panduan pengurusan makmal Oleh: Khairul Nasrin Abas

Gelcasting - CaraMudah Menghasilkan

Seramik TumpatBerbentuk Kompleks

Contoh kegunaan yang dianggappenting ialah untuk menghasilkankomponen enjin daripada seramik.

Mohd Zairol Hafiz Zainal Badri, Mohd Al AminMuhamad Nor, Zainal Arifin Ahmad

zainal@eng.usm.my

PengenalanPenghasilan seramik tumpat boleh

dilakukan melalui kaedah tuangan slip,acuan suntikan, semperitan danpenekanan serbuk.

Walau bagaimanapun, satu kaedahbaru yang lebih murah berbandingkaedah pembentukkan tradisi tersebuttelah dicipta oleh Omatete et. al. (1991).

Kaedah baru ini dikenali sebagai ‘gel-casting’. Melalui kaedah ini, produkseramik boleh dihasilkan dalam keadaanlebih tumpat dan pelbagai bentuk(walaupun bentuk yang sangat rumit).Contoh kegunaan yang dianggap pentingialah untuk menghasilkan komponenenjin daripada seramik.

Kaedah ‘gelcasting’ ini mengabungkankimia polimer dengan kaedah penghasilanseramik tradisi.

Penggunaan monomer organik akanmenyediakan slip seramik dengankelikatan rendah. Slip seramik ini jugaboleh disediakan dengan kandunganpepejal yang tinggi.

Kebaikan slip yang berkelikatan ren-dah ialah mengenai keupayaannyamengisi ruang acuan dan seterusnyamenghasilkan bentuk yang menyamaiacuan tersebut.

Manakala kandungan pepejal yangtinggi di dalam slip pula memudahkanproses pengeringan dilakukan, mengekal-kan bentuk selepas pembakaran, mengu-rangkan kecut bakar dan kecacatan yangminima pada jasad anum serta peratusliang yang rendah.

Monomer organik membolehkan pem-polimeran in-situ berlaku apabila penam-bahan mangkin dan bahan pemuladilakukan. Tindakbalas ini menghasilkanjasad yang tegar serta mempunyai keku-atan yang tinggi dan boleh dimesinselepas pengeringan.

Selain proses yang mesra alam seki-tar, penggunaan air sebagai pelarut jugamemudahkan penyingkiran pelarutsemasa pengeringan.

boleh digunakan untuk pelbagai jeniskomponen seramik dari seramik refraktorisehinggalah seramik berteknologi tinggiseperti silikon karbida dan silikon nitrida.

Bahan-bahan:-

(i) Serbuk alumina (a-Al2O3) bersaizpurata 10µm

(ii) Monomer organik terdiri dariakrilamida

(iii) Agen terpaut silang N,N, metilenabisakrilamida

(iv) Bahan pemula - amoniumperoksodisulfat

(v) Mangkin - N,N,N’,N’ - tetrametilenadiamina

(vii) Agen penyerak – Dispex N40

(viii) Pelarut – air suling

Proses penyediaan sampel:

Penyediaan sampel dilakukan denganberpandukan kaedah gelcasting yangdihasilkan oleh Omatate et. al. (1991)seperti ditunjukkan di dalam rajah 1.

Rajah 1: Carta alir proses penyediaanseramik tumpat melalui kaedah gelcasting

Penyediaan larutan monomer organikdan agen paut silang dilakukan denganmenggunakan air sebagai pelarut dengankepekatan tertentu. Larutan tersebut

akan dicampurkan kepada serbukseramik, kemudiannya dilakukan pencam-puran basah untuk membentuk ampaianseramik.

Ampaian tadi dihampagas untukmenyingkirkan udara yang terperangkap.Mangkin dan bahan pemula ditambah dankemudiannya ampaian tadi dituang kedalam acuan.

Pempolimeran in-situ ampaianseramik akan bermula sebaik sahajabahan pemula ditambahkan dan seterus-nya menghasilkan jasad yang tegar.Proses pempolimeran mungkin mengam-bil masa dalam 1 hingga 30 minit bergan-tung kepada jumlah bahan pemula yangditambah. Sampel dikeringkan sebelumpersinteran dilakukan.

Walapun proses ini nampak mudah,beberapa parameter perlu dititikberatuntuk menghasilkan jasad yang berkualititinggi. Di antaranya ialah pemilihan pera-tus (%) kandungan pepejal, % agenpenyerakan, % dan kepekatan larutanmonomer organik dan juga agen terpautsilang.

Contoh hasil ‘gelcast’.

Rajah 2 menunjukkan gambar beberapacontoh produk alumina yang dihasilkanmelalui kaedah gelcasting. Bermula den-gan bentuk mudah (silinder) hinggalahkepada bentuk yang sukar (banyaksegi/lurah) telah berjaya dihasilkan.Parameter yang dipilih ialah 60% kandun-gan pepejal, manakala kandungan cecairpula terdiri dari 5.26% larutan agen peny-erak dan selebihnya (97.74%) adalahcampuran 7 bahagian larutan 20% akril-amida dan 3 bahagian larutan 2% N,N,metilena bisakrilamida. Mangkin danbahan pemula ditambah dalam jumlahyang sedikit sahaja. Penyediaan bahankimia adalah diambil dari kaedah yangdinyatakan oleh Menchhofer (1995).

Rajah 2: Gambar beberapa contoh pro-duk alumina yang dihasilkan melaluikaedah gelcasting

Kesimpulan.Kaedah gelcasting sangat sesuai

dibangunkan untuk penghasilan seramik

bentuk kompleks yang amat sukardilakukan dengan mengunakan kaedahtradisi seramik. Satu proses pembentukanyang mudah dan murah dengan hasilanyang berkualiti tinggi dihasilkan.

Penyelidikan sedang rancak dijalankanuntuk menghasilkan bentuk lebih sukardengan merekabentuk acuan yang lebihkompleks dengan menggunakan lilin.Kaedah ini juga akan dibangunkan untukmenghasilkan seramik berteknologi tinggiseperti silikon nitrida dan silikon karbidauntuk pelbagai tujuan komersil.

Rujukan:1. Omatete O.O, M.A. Janney, M.A. and Strehlow, R.(1991) Gelcasting - A new ceramic forming process. J.Am. Ceram. Soc. Bull. 70 10. pg 1641–1649. 2. Menchhofer, P (1995).Casting of particle-based hol-low shapes. US Patent No. 5419860

BED FLUIDISATIONOF CHROMIUM SLAGH HUSSIN, A. C. APLING AND C. POOLE

AbstractSeparation of chromium particle in the fraction

(-90 +63) mm from slag are seen to be promising.Beside the density the shape of the chromiumparticle was also affected the separation.

IntroductionAir-solid fluidised systems are well known,

particularly in chemical engineering fields.Through this technique a bed of particulatesolids, supported over a fluid-distributing plate,is made to behave like a liquid by the passageof the fluid (gas, liquid, or gas-liquid) at a flowrate above a certain critical value. In otherwords, it is the phenomenon of imparting theproperties of a fluid to a bed of particulatesolids by passing a fluid through the latter at avelocity which brings the fixed or stationarybed to its loosest possible state just before itstransformation into a fluid like bed (Gupta andSathiyamoorthy, 1999).

In normal fluidisation, the fluidising fluidflow upward, thereby counteracting the gravi-tational force acting on the bed of particulatesolid materials. It can be seen that, high densi-ty particle that rest in the static bed would sinkand low density particle would float. At the endof the fluidisation, for the ideal circumstancestwo layers of different specific gravity mineraland alternated by mixed of those mineralswould be yielded.

Material

The material used in this research wasobtained from London & ScandinavianMetallurgical Co. Limited, Fullerton Road,Rotherham, South Yorkshire, S60 1DL,England. This plant producing chromium metalby the aluminothermic reduction method whichcan be simplified by the equation [1-0]. In thisprocess pure chromium oxide powder isreduced by fine aluminium metal. A type ofbooster was also added to the mixture in orderto make the reduction activity become fasterand more complete. But in reality the reactiondoes not completely change chromium oxide to

SERBUK SERAMIK

MONOMER ORGANIK

AGEN PENYERAK PELARUT

PENCAMPURAN BASAH

AMPAIAN SERAMIK

PENYINGKIRAN ACUAN

PENUANGAN KE DALAM ACUAN

PENGERINGAN, PERSINTERAN

PENYINGKIRAN UDARA

AGEN PEMULA,MANGKIN

PRODUK

chromium metal, therefore a few percent ofCr2O3 remains in the slag. During cooling peri-

ods some fine droplets of chromium metal donot sink fast enough through the slag for themto reach the main mass of chromium metalbefore the slag goes solid. This resulted insome small droplets of chromium metaltrapped in the slag and are usually dumped aswastes at the plant site. It is mainly made upof aluminium oxide (Al2O3) in the form of syn-

thetic corundum. Visually, the colour of theslag is dark red. It is known that a considerableproportion of chromium metal (droplets) is lostin the slag along with some other materialssuch as silica, carbonate, and iron. The gradeof chromium slag are varies from 8.5% to6.8%. Table 1.0 shows the typical analysis ofthe slag. Under microscope observation theparticles can only be fully liberated at 90 mm.Therefore, the sample received was thenground to minus 90 mm before the experimen-tal can be proceeded.

Cr2O3 + 2Al = Al2O3 + 2Cr ......... [1.0]

Table 1.0: Typical Results of Semi-Quantitative Analysis of Slag Samples

Composition Percentage (Wt %)Al 88.0 to 90.0Cr 7.0 to 10.0K 4.6W 2.2Ca 1.7Si 0.38Mg 0.25Fe 0.5 to 1.2Na 0.047S 0.025Zn NDACl NDA

MethodologyA fluidisation cell was constructed and

used in all experiments to examine the possi-bilities of achieving separations on a densitybasis under streamline conditions of fluidisa-tion. In this experiment, the fluidising fluid(air) flows upward, thereby buoyancy and dragforces counteracting the gravitational forceacting on the bed of particulate solid materials.These have two main purposes, stratificationand separation of the stratified layers.

The bed of solids was supported in a verti-cal cylindrical transparent column with a bot-tom distributor mesh covered with a filtercloth. The cylinder was measured as 3.0 cminner diameter and 45.0 cm long. Samplingholes of diameter 0.5 cm were made evenly atevery 1.0 cm from the bottom of the column to15 cm height. To avoid sample escaping fromthe cylinder, the holes were covered with clingfilm during the fluidisation process. A half cutof sharp and strong plastic straw was used asa sampling device. It was pushed horizontal-ly through the hole from one side and out atthe other side. Sample that collected in thestraw was then analysed for chromium.

Each test was performed for 5, 15 and 30minutes. Fluidisation air flowed into the base ofthe column through a flow meter and a valve.A simple manometer that attached to theapparatus was used to measure the pressuredrop of the bed. Before the experiment start-ed, the pressure drop between fixed bed andfluidised bed was determined. The determina-tion of the pressure drop can be made by themeasurement of the pressure difference.

As illustrated in Figures 1.0 (a) and (b),two experiments were conducted, one normalfluidisation and the other was the combinationwith vibration (vibro-fluidisation). In everyexperiment, different size ranges of feed wereexamined. Careful visual observations hadbeen made to the bed throughout the work toidentify changes in bed structure, bed heightand where possible the behaviour of the bedduring fluidisation such as bubbling, chan-nelling and slugging.

In the early stage, a wide size range (-90mm) of sample was tested but it shows thatthe bed was quite dense (low value ofvoidage) and high air flow rate is needed tomake the particles move from static bed tofluid like. This situation is due to the fine par-ticles filling the interstices of the coarse mate-rial and makes the bed very compact. Whenair is supplied to the vessel the pressure dropgradually increases and after some time a sud-den burst of air brings very fine particles to thesurface. In other word it was difficult to esti-mate the Umf (superficial velocity) of the sys-

tem as fluidisation was not homogenous andwhen air is introduced to the canister the fineparticles were blown away. To avoid these sit-uation, the sample was then classified intosmaller size ranges; (-90 +63), (-63 +45) and-45 mm.

Results1. Normal Fluidisation(i). Fraction (–90 +63) mm

As indicated in Figure 1.1(a), the gradeof chromium obtained from the experimentalwork show a similar pattern of segregation.The grade of chromium was slightly higher atthe bottom and at the top of the bed comparedto the grade of feed (8.74 %Cr). The grades ofchromium were between 10.15 to 10.75 %Crat the bottom and 9.6 to 10.19 %Cr at the top.The highest grade of 10.75 %Cr was obtainedat the bottom of the bed when the fluidisationwas run for 15 minutes. Meanwhile, the high-est grade of 10.19 % Cr at the top of the bedwas also obtained when the fluidisation wasrun for 15 minutes. Generally, in all cases thegrade of chromium was gradually reducedfrom the bottom to the middle and increasedinconstantly to the top of the bed.

The result obtained probably influenced bythe history of the sample preparation whichwas ground to minus 90 mm in a Tema mill forthe liberation process. Thus, this activity indi-rectly generated a variety of chromium particleshapes. Two major shapes of chromium parti-cle were mainly generated; flaky and granulat-ed shapes. The production of the flaky shapedparticles were related to the property ofchromium metal which is ductile, and tend toform very thin flakes before being broken tosmall particles. During the bed fluidisationprocess the flaky shaped particles have the

tendency to float at the top of the bed. This isdue to the buoyant and drag forces being moresignificant than the gravitational force. In suchsituation even though the density of chromiumwas comparatively high but the shape of theparticles gave more advantages to the buoyantand drag forces to carry and hold the particlesat the top rather than the gravity force. Thegravitational force is significant for the granu-lated particles and displaces them to settle atthe bottom of the bed. In both conditions wecan say that even though the density ofchromium was approximately double the den-sity of corundum but the gravity force stronglyaffected the granulated particles rather thanflaky shape particles. Therefore, from thegraphs it can be seen that in all cases chromi-um particles were segregated into two differ-ent levels.

(ii). Fraction (-63 +45) mm Generally, the highest grades that can beobtained in these experiments were not satis-factory. As illustrated in Figure 1.1(b) thehighest grade of 9.75 and 9.82 %Cr (thegrade of feed 9.22 %Cr) were obtained whenthe fluidisation was run for 15 and 30 minutesrespectively. Even though the results obtainedwere not acceptable but a trend of normal seg-regation can be seen in this fraction which isthe heavy particles settling at the bottom andlight particles floating at the top. As observedunder a microscope the shape of chromiumparticles in this fraction was mainly granulated(angular and sub-angular) which is a quitesimilar to the shape of corundum. As a result,both buoyant and drag forces were lesssignificant to the chromium particles comparedto gravity force, in this regard the chromiumparticles would be found accumulated at thebottom of the bed and corundum which islighter than chromium accumulated at the topof the layer.

(iii). Fraction (-45) mmThe graphs shown in Figure 1.1(c) indicatethat the grade of chromium at all levels werealmost similar with the grade of feed. Duringthe experimental work, it can be observed thatthe particles were agglomerated and trans-formed to bigger-rounded particles asillustrated in Figure 1.1(d). In the mean timethe manometer indicated that the pressuredrop was not very stable as observed by thefluctuating water level. The pressure dropfinally declined and remained close to zero. Inthis situation it can be seen that channelswere created by the agglomeration activitywhich in turn allowed airflow to escapethrough the bed freely. As a result, thefluidisation failed to segregate the particles.The difficulty of the fluidisation process is dueto the inter-particle cohesion, in which the par-ticles agglomerate to form big particles andprevent the segregation process.

2. Vibro Fluidisation (i). Fraction (-90+63) mm Figure 1.2(a), shows that the grades ofchromium were similar at every level and notmuch different from the grade of feed. In thissituation fluidisation was not able to segregatethe particles. This is due to the vibration whichwas used to overcome the inter-particle forcewas actually makes the bed more compacted.Thus, the flaky shape particles were probablytrapped among the particles or stay vertically

Figure 1.0 The schematic diagram of bed fluidising apparatus: (a) Normal fluidisation and (b) Vibro fluidisation

Sampling Holes

Air Air

Up-down movement

Vibrator

(a) (b)

significant to them.

(ii). Fraction (-63 +45) mm Figure 1.2(b) shows that the grades ofchromium at every level were also not muchdifferent from the grade of feed and do notshow any trend of segregation.

(iii). Fraction (-45) mm As shown in Figure 1.2(c) the separation ofthis fraction by bed fluidisation is far from sat-isfactory. The vibration made the bed of parti-cles more compact and need more upward flowrate to allow the particles to be displaced froma static bed to a fluid like bed. However, whenthe flow rate was increased the particles werenot moving freely but initiated slugs (air cush-ion). It can be seen clearly that, a certainthickness of particles moved above an air sluglike a piston Figure 1.2(d). The slug growslarger finally bursting when the pressure strongenough to break the layer and some of the par-ticles were blown off. Meanwhile, new slugswere generated and the same processes wererepeated. It can also be seen that the problemwith this method is that when the vibration isreduced to a lower frequency, the shock wavesfrom the vibration only travels some centime-tres into the bed before they are attenuated,leaving much of the bed unimproved and whenthe vibration was then increased the bedbecame more compact.

ConclusionsThe chemical analyses of fraction (–90

+63)mm by normal fluidisation shows that thepercentage of chromium at level 0 (bottom ofthe bed) and at level 10 (top of the bed) wereslightly higher than the feed. The presence oftwo different types of particles was probablythe main reason for this. The flaky shape par-ticles are more significant to buoyant and dragforces rather than gravitational force, resultedan accumulation of flaky shaped particles floatat the top. In such situation even though thedensity of chromium is double the density ofcorundum the shape of the particles give more

advantage to the buoyant and dragforces to carry and hold the parti-cles at the top rather than thegravity force. The gravitationalforce is mainly significant to thegranulated chromium particles,therefore displaced them to thebottom of the bed.

In the fraction -45 microns flu-idisation is not possible becausethe particles were agglomeratedand transformed to big-roundedparticles. The grade of chromium isalmost similar with the grade offeed at every level of the bed. Thisis because the formation of chan-nels allows airflow to escape

through the bed freely. As a result, fluidisationfailed to segregate the particles. An attempt toapply vibration to the fluidisation did notimprove the segregation. The vibration actionmade the bed of particles more compacted andthis need more upward flow to bring the parti-cles to be displaced from a static to a fluid likebed. An increasing of the airflow rate did notmove the particles freely but initiate air slugs.

The inter-particle forces and moisture fromthe airflow could be other factors that makethe separation not possible. As reported byLupa and Laskowski (1979) cited by Burt(1984) the moisture in the fluidising air inexcess will cause aggregation of particles,resulting in canalisation of the airflow and abreakdown of fluidisation

ReferencesBurt, R. O. 1984. Gravity Concentration

Technology . Elsevier. Amsterdam, Oxford, New York,Tokyo. pp1-605.

References (ctd.)

Douglas, E. and Walsh, T. 1966. New Type ofDry, Heavy-Medium, Gravity Separator. Trans. Inst.Min. and Metall. 75 Section C. C226-C232

Gupta, C. K., and Sathiyamoorthy, D. 1999. FluidBed Technology in Materials Processing . CRC Press,Boca Raton. London. New York. WashingtonD.C.pp1-498

Fraction - 45 microns

5

5.2

5.4

5.6

5.8

6

6.2

6.4

6.6

6.8

0 1 2 3 4 5 6 7 8 9 10 11Sampling Level (cm)

Gra

de (%

-Cr)

5 minutes

15 minutes

30 minutes

Fraction (-90 +63) microns

6

6.5

7

7.5

8

8.5

9

9.5

10

10.5

11

0 1 2 3 4 5 6 7 8 9 10 11Sampling Point (cm)

Gra

de (%

-Cr)

5 minutes

15 minutes

30 minutes

Figure 1.1 Normal fluidisation of (a) fraction (90+63) µm (b) fraction (–63+45)µm (c) fraction –45µm as a function of fluidisation time.

Fraction (-63 +45) microns

8.2

8.4

8.6

8.8

9

9.2

9.4

9.6

9.8

10

0 1 2 3 4 5 6 7 8 9 10 11Sampling Level (Cm)

Gra

de (%

Cr)

5 minutes

15 minutes

30 minutes

(a) (b)

(c)

Figure 1.1(d) (i) In the fraction (-90 +63) µm and (-63+45) µ m, bubbles are constantly splitting and coalescing and a maximum stable bubble size is achieved. (ii) attempts to fluidise fine fraction producing cracks and channels.

Airflow

(i) (ii)

Air-flow

Figure 1.2 Vibro fluidisation of (a) fraction (-90+63) µm (b) fraction (–63+45) µm (c) of fraction (-45) µm as a function of fluidisation time

Fraction - 45 microns

4

4.5

5

5.5

6

6.5

7

1 2 3 4 5 6 7 8 9 10 11Sampling Level (cm)

Gra

de (%

Cr)

5 minutes

15 minutes

30 minutes

Fraction (-90 +63) microns

8

8.2

8.4

8.6

8.8

9

9.2

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Fraction (-63 +45) microns

7

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(a)

(c)

(c)

(i) (ii)Air-flow Air -flow

vibr

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vibr

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Figure 1.2(d) A schematic diagrams represent; (i) The bed beco me more compact when vibration was applied, (ii) The formation of slugs when airflow was increased during vibro fluidisation.

GERAN PENYELIDIKAN BARU

FRGS (FUNDAMENTAL REASERACH GRANT SCHEME)1. “Study of cross linking process of proteins in natural rubber latex”

Prof. Madya Dr. Baharin Azahari, Dr. Azhar Mat Essa, Prof. Madya Dr. Hanafi Ismail and Prof. Madya Mas Rosemal Hakim Mas Haris. (RM 83,500)

2. “Determination of transport properties in the protective oxide-scale formation of the Ti-Al-X multiphase alloy systems.” Prof. Madya Rizal Astrawinata and Prof. Madya Azizan Aziz (RM77,060).

3. “Structural changes in silica particles during ultra fine grinding process”.Prof. Madya Dr. Khairun Azizi Mohd Azizli and Samayamutthirian Palaniandy (RM34,300)

Ketua Penyelidik Tajuk Geran Jumlah(RM)

Prof. Madya Dr. Zainal ArifinAhmad

Development and performance of ceramics - metalbonding to improve structural materials.

211,600

Dr. Sutapa Roy Ramanan Development of heat mirror and rear view mirrorcoating on glass by sol-gel technique.

120,000

Dr. Shamsul BaharinJamaludin

Synthesis and properties of hard and wearresistance materials for industrial application.

99,000

Prof. Madya Dr. BaharinAzahari

Study of crosslinking process of protein in naturalrubber latex.

248,000

Prof. Madya Dr. HanafiIsmail

A new compatibilizer of coupling agent based onpalm oil fatty acid for plastic and rubber industries(now chemical)

209,500

Prof. Madya Dr. UmaruSemo Ishiaku

Preparation and characterization of highperformance natural rubber/organosilicate andpolypropylene/polyamide/organosilicate.

181,000

Prof. Madya Dr. Khairun AziziMohd Azizli

Production of high quality aggregate forconstruction purposes.

265,420

DE CROSS PRO - A NOVELMECHANO-CHEMICAL PROCESS FOR

RECYCLING RUBBER WASTESinvented by

ASSOC. PROF. DR HANAFI ISMAIL

Introduction

The annual consumption of natural rubberis more than 15 million tons, and the out-put or rubber products is more than 31million tons worldwide. With the develop-ment of rubber industry, a lot of wasterubber is produced in the world everyyear. The main source of waste rubber isdiscarded rubber products, such asdiscarded tyres, rubber pipes, rubberboots, rubber shoes, edge scraps andwaste products which are produced inrubber processes. Presently the amountof discarded tyres reaches 10 milion tonsevery year.

Objective

To recycle alll rubber waste such as tyres,scrap gloves, tubes, shoe sole, rubberhose, etc. and to assist the Malaysiangovernment to solve the environmentalproblems in disposing various wastesthrough the recycling of scrap as well asto find an economical method of recyclingrubber wastes and to produce a newproduct using recycled rubber.

Description

1. With the help of mechanical shearing(rubber processing eqipment such asinternal mixer, roll-mill, etc), all rubberwastes can be recycled usingDeCrossCHEM.2. The recycled rubber called DeCrossCompound can be vulcanised into newproduct either using 100% DeCrossCompound (recycled rubber compound)or blend it with new rubber in thepresence of curative agents.3. A moderate strength of new products(about 5-7 MPa) is obtained using 100%recycled compound and a very goodstrength of new products (about 18-20MPa) is obtained by blending 50% ofrecycled rubber and 50% of new rubber.4. Only 5 grams of DeCrossCHEM isneeded to recycle 100 grams of rubberwastes.5. The manufacturing cost forDeCrossCHEM is only RM15/kg

Japanese proverb:

Vision without action is just a daydream,action without vision is a nightmare.

TINGGAL KENANGAN

SahabatSehingga semalam kau masih temanku

Bersama merenung arusBersama menyusuri sungai

Kita juga bersamaMembina impian

SahabatSehingga semalam, engkaulah kawanku

Sahabat sejati penawar sepiBersama serpihan kenangan semalam

Apalah yang ada pada mimpi kitaSekadar senyuman nan melegari mata dan

hatitinggal....tinggal kenangan itu....

Dalam lipatan diari hatiku

TemanTanpa sedarHatiku dilukaiTanpa Kata

Aku kau biarkan mencari erti persahabatanSampai bilakah dapat aku tentang

Tiap arah yang bersimpangKerna terpaksa jua aku lepaskan

Genggaman erat setia Walau di pertengahan jalan

SahabatCukuplah andai disisip di sanubariTidak perlu dibawa ke alam mimpi

Bahawa di antara kita Ada erti yang sukar dimengertiAda suratan di sebalik siratan

Namun siapalah yang mendambakanSatu kehilangan yang tak mungkin terganti

SahabatTiada lagi madah-madah indahYang disulami serpih kenanganTak usahlah disalahkan takdir

Kerna dengan iaKita saling mengenaliMenjadi sahabat sejati

Hanya sehingga semalam...............

YusliaKernaTerpaksa

ANUGERAH

Berikut adalah anugerah yang telahditerima:

1. Malaysian Toray Science Foundation (S&T Research Grant)Yeoh Fei Yee, Prof. Madya Dr Azizan Aziz dan Prof. Radzali Othman.

“Synthesis and characterization of advance nanostructure pyroelectric smart material” (RM 25,000).

2. Malaysian Toray Science Foundation (S&T Research Grant).

Sim Lim Chong, Dr Ramanan Venkatesh, Dr Sutapa dan Prof. MadyaDr Azizan Aziz.

“Fabrication of new generation thermal interface materials to be usedin electronic industries” (RM 25,000).

3. Anugerah Kecemerlangan Penyelidikan Kejuruteraan (Yayasan Perak) - hadiah saguhati (RM3,000)

Prof. Madya Dr. Hanafi Ismail dan rakan-rakan.

4. Anugerah Kecemerlangan Penyelidikan Kejuruteraan (Yayasan Perak) - hadiah saguhati (RM3,000).

Prof. Madya Dr Khairun Azizi, Prof. Madya Dr Abu Bakar Mat Diah, Samayamutthirian, Sri Rajeshwari, Rashazita dan Badrul.

5. Biasiswa Tabung General Electric (G.E.Fund Scholarship Award) oleh MACEE.

Nurul Izza Ismail (Pelajar tahun satu Kejuruteraan Sumber Mineral).

6. Prof. Madya Dr Hanafi Ismail dan rakan-rakan

‘DecrossPRO - A novel mechano-chemical process for recycling rubberwaste”.

7. Prof. Madya Dr Luay Bakir Hussain danrakan-rakan.

i. Honey comb structures for roofing and panels application.

ii. Low cost metal cutting wheel

Bahagian hadapan Pusat PengajianKejuruterann Bahan dan Sumber Mineral