Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Tesis

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Evaluation And Processing Of Gold At Pulai Mining, Gua Musang, Kelantan
(2014-11)
Eang, Khy Eam
Gold mining is the important activities that create economic growth and development of the country. Effective method in gold processing is the key part in gold mining. At Pulai Mining Sdn Bhd, gold recovery is poor and it is believed that some percentage of gold lost into the tailing. This study involves characterization of samples from the area and suggests the suitable processing method to recover gold and iron with mining impacts to the environment. In this research, tailing and palong samples are studied and the following methodology is applied: laboratory sampling, mineral characterization and alluvial gold processing and then found the recovery of gold after the results of analysis and processing. Result shows that the tailing sample composed of 0.020 % of AU20 in flaky shape presented in fraction size <2.36 mm. No gold was found in palong sample (taken from middle of palong) due to its good design. Based on XRD result, tailing sample consists of hematite (FC203) 44.20 %, quartz low (Si02) 32.90 %, pyrrhotite high (FeO.lJ8SS) 13 %, pyrite (FeS2) 9 % and magnetite (Alo.IFe2.46Mgo.4204Tio.03) 0.90 %, whereas palong sample consists of quartz low (Si02) 74.60 %, hematite (Fe203) 21. 70 %, magnesium aluminum sulfide (AhMgS4) 3.20 % and pyrite (FeS2) 0.60 %.
Fabrication And Characterization Of Poly (L-Lactic Acid) (Plla) Blends And Pllaikenaf Fiber Composites
(2014-12)
Eawwiboonthanakit, Netnapa
Environmental impacts are the main global concem which induce to incremental awareness on the replacement of conventional plastic materials by biodegradable plastic e.g. Poly (L-Iactic acid) (PLLA). Investigations on mechanical and thermal properties of PLLA blends and PLLA/kenaf fiber composites by internal mixing were observed in this study. Properties of PLLA blended with polymer additives; carboxyl-terminated butadiene acrylonitrile (CTBN), acrylonitrile butadiene styrene (ABS) and poly (lactic acid) (PLA) microsphere at various blend ratios (10010, 98/2, 96/4, 94/6 and 92/8 wt%) are observed in the first part. It was found that PLLA/PLA microsphere blend at 92/8 blend ratio presented higher mechanical, thermal and melt now index properties with resulting of fibril formation in the microstructure compared to other blends systems. Effects of fiber surface modification and fiber loading on the mechanical and thermal properties of kenaf fiber (KF) in PLLAIPLA microsphere/KF composites were investigated in second part of study. Addition of 4 wt% of treated KF (T-KF) in the composite illustrated higher flexural strength and easy to process compared to composite with 30 wt% of T -KF content.
Comparative Study On The Sintering Of Calcium Phosphate Ceramic By Conventional And Microwave Sintering
(2014-12)
Mangkonsu, Chuthathip
Sintering of calcium phosphate bioceramic were performed using microwave and conventional furnaces. The calcium phosphate precursor was used as raw material powder. Sintering of biphasic calcium phosphate (B'Cl") was successful using both sintering methods. The precursor powder was characterized by XRO, TG/ ose and particle size analysis. Sintering was done at different temperatures (1200 oe, 1250 oe, 1300 oe, 1350 oe, and 1400 Oe) using conventional and microwave furnaces. For the microwave sintering, the firing process was stopped, when the temperature reached at 1350 oe because the specimens cracked and the surfaces were damaged especially on the edge of specimens. Then the Bep specimens were characterized by XRO and FESEM while physical properties measured include density, porosity and linear shrinkage. The mechanical properties of bulk Bep were determined by using Micro Vickers hardness and diametrai tensile strength (OTS). The comparison on properties was carried out on specimens sintered at the same temperature using both methods. The XRO results showed that the f3-TCf' to (l-TCf' transformation phase occurs above 1250 oe in both sintering furnaces.
Effect Of Secondary Plastic Deformation On The Microstructures And Mechanical Properties Of Cast Ai-7Si-Mg Alloy
(2014-12)
Thuong, Nguyen Van
The purpose ofthis research is to study microstructure and hardness of AI-7SiMg alloy under different cooling slope casting conditions and equal channel angular pressing (ECAP). The effect of cooling slope casting method with varying variables, such as pouring temperature (625°C - 640°C - 660°C - 680°C), cooling slope length (150 mm - 250 mru- 350 mm) and cooling slope temperature (room temperature - 200°C - 400°C) and conventional casting method are investigated. The as-cast alloys and as-ECAPed alloys were analyzed based on Differential Scanning Calorimetry, Xray fluorescence, microstructures, hardness, X-ray Diffraction pattern, wear resistance, Secondary Electron Microscope and Energy Dispersive X-ray. Microstructure of conventional cast alloy cast at pouring temperature of 640°C was coarse and almost dendrite the structure. However, uniform, fine and globular microstructure could be obtained from cooling slope casting with pouring temperature range of 625°C - 660°C, cooling slope length range of 150 mm - 350 mm and slope temperature ranging from room temperature to 200°C_ This is due to copious nucleation occurred on slope surface and these nuclei were then detached due to the force convection during pouring process.
Syedsalim, Sharifah Aishah
(2014-01)
January 2014
In this research, the effect of Zirconium ions (Zr4+) and Calcium ions (Ca2+) dopant on NiO was investigated. The electroceramic of Ni(l_;c)ZrxO, Ni(l_x)CaxO and Nio.9SZrO.o2CaO.OI was prepared by using solid state reaction method. Three main raw materials ofNiO, Zr02 and CaO were mixed for 24 hours, then were calcined at 1000°C. Ni(l_x)Zr.

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