Sains Malaysiana 39(1)(2010): 31–38

 

Sifat-sifat Fizik dan Kandungan Kimia Lempung Kaolin Segamat, Johor, Malaysia

(Physical Properties and Chemical Composition of Segamat Kaolin, Johor, Malaysia)

 

Umar Hamzah*, Khor Kang Learn & Sahibin Rahim

Pusat Pengajian Sains Sekitaran & Sumber Alam

Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E., Malaysia

 

Received: 18 November 2008 / Accepted: 9 May 2009

 

ABSTRAK

Lempung kaolin adalah sejenis sumber mineral sekunder yang dihasilkan oleh proses luluhawa mineral-mineral primer. Komponen utamanya ialah kaolinit bersaiz halus (<2μm) dan ia melimpah dengan sebatian filosilikat serta unsur lain seperti aluminium dan ferum yang membentuk pigmen. Kaolin berwarna putih susu jika mengandungi banyak komponen aluminium serta sifat keplastikannya yang rendah, seringkali digunakan dalam industri seramik, plastik, cat, kertas, pestisid, farmakologi dan kosmetik. Pencirian sifat fizik dan kimia kaolin adalah penting dalam penentuan potensi kegunaannya. Dalam kajian ini, sampel telah diambil secara penggerudian tangan sedalam 1-2 meter dari 25 lokasi di kawasan Buloh Kasap, Segamat, Johor, Malaysia. Analisis kimia telah dijalankan untuk menentukan kandungan oksida dan mineral dengan teknik pembelauan sinar-X dan pendafluoran sinar-X. Sampel kaolin juga diuji secara fizikal untuk menentukan kadar pengecutan, modulus patah dan kadar penyerapan air di samping, had plastik dan cecair serta indeks keplastikan. Kaolin Segamat mempunyai komposisi silikat yang tinggi dan berwarna cerah. Kandungan mineral terbanyak ialah kaolinit di samping kuarza sebagai bendasing. Kadar pengecutan yang rendah menunjukkan sampel kaolin adalah padat dan kurang rongga serta sesuai sebagai bahan seramik di samping tahan kepada haba yang tinggi. Kaolin ini juga mempunyai kadar penjerapan air dan keplastikan yang rendah serta kuat berdasarkan ujian modulus kekuatan patah.

 

Kata kunci: Analisis kimia; kaolin; seramik; sifat fizik; sinar-X

 

ABSTRACT

 

Kaolin is a source of secondary mineral as a product of a weathering process of primary minerals. Its main component is fine grain kaolinite (<2μm) and it also contains other elements such as aluminium and iron phyllosilicate as the pigment. Aluminium rich kaolin is light in colour with high plasticity and is normally used in the ceramic, plastic, paint, paper, pesticide, pharmacology and cosmetic industries. The physical and chemical characteristics of kaolins are important for its potential application. In this study, about 25 kaolin samples were hand-augered from depths of 1-2 m at Buloh Kasap Segamat, Johor, Malaysia. Chemical analysis carried out included determination of oxides and types of minerals by X-ray diffraction and X-ray fluorescence. Shrinkage rate, rupture modulus and water absorption rate tests were carried out in the physical properties analysis. Plastic and liquid limits of the kaolin were also measured for plastic index. The Segamat kaolin was light in colour due to its high silicate composition. The highest mineral content in the kaolin was kaolinite and quartz occured as impurities. The low shrinkage rate showed that the kaolin was dense with little voids, hence very suitable for use in the ceramic industry. This kaolin has low water absorption, plasticity and durable according to the rupture modulus test.

 

Keywords: Ceramic; chemical analysis; kaolin; physical properties; X-ray

 

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*Corresponding author; email: umar@ukm.my