Norlia Baharun

A novel rapid mist spray technique for synthesis of single phase precipitated calcium carbonate using solid-liquid-gas process

Various techniques and approaches have been designed to synthesize precipitated calcium carbonate. We used a continuous sprayed-mist technique that induced spontaneous precipitation reaction of the droplets with the higher surface area when in contact with the gas. The effects of optimum reactant concentration, gas flow rate, and reactant feeding rate including reaction conditions were investigated. The effectiveness of the techniques was scrutinized by analyzing the resultant PCC characteristics, especially the particle phase morphology and size distribution using XRD, FTIR, and SEM. The variation of initial concentration of milk of lime with different gas flow rate was studied. Experimental results, as well as XRD and FTIR, indicated that all the products produced were favorable for the formation of calcite. SEM revealed that the morphologies of PCC were all rhombohedral and tended to adhere to each other (twinning). It was found that production of PCC by using spray-mist method is suitable for lower initial concentration of Ca(OH)2 and higher gas flow rate only.

Microstructural Study of Reduced Malaysian Ilmenite by Carbothermal Reduction and Nitridation in Nitrogen Atmosphere

The reduction of Malaysia Ilmenite (FeTiO3) with coal by carbothermal reduction under N2 atmosphere was studied. Characterization of raw materials was done by XRD, XRF, Optical Microscopy (OM) and SEM analysis. Isothermal experiments were carried out using the pellets in a horizontal tube reactor with continuously flowing gas. From the experiments, 0-10 wt. % of FeCl3 was added in the ilmenite-coal mixtures before reduction. The mixture was reduced at 1100°C for 60, 120 and 180 minutes. The addition of FeCl3 acted as a catalyst and increased the rate of reduction. The microstructures of the reduced sample were porous with the addition of FeCl3. Furthermore, defects were observed due to increase release of Cl2 and CO during reduction. FeCl3 acted as catalyst in the gasification of coal by the Boudouard reaction. SEM analysis indicates that the microstructure of the particles was coarsened due to the addition of catalyst. Besides that, there was less agglomeration of metallic iron particles at higher addition of FeCl3. The effect of FeCl3 on the morphology iron was the nucleation of microscopic iron rich zones in the reduced sample. Keywords: Carbothermal Reduction, Iron Chloride, Malaysian Ilmenite, Nitridation, Titanium Oxycarbonitride.

Removal of Iron and Total Chromium Contaminations in Landfill Leachate by Using Electrocoagulation Process

This research work involves the study removal of Iron and Total Chromium by electrocoagulation process. This project focused on leachate landfill from Pulau Burung, Nibong Tebal, Penang as an electrolyte solution. These heavy metals are the main factor contributing to pollution in leachate landfill. Types of electrodes used in this study were Aluminium (grade 5052) and Stainless Steel (grade 316). The ranges of initial pH applied were pH (3, 4, 5, 6 and 7) and voltages applied were 1.5V, 2.0V and 2.5V. These three parameters were evaluated and the operation time was 60 minutes. At the end of electrocoagulation process, the solutions were stored and analysed using AAS to determine the final concentration of electrolyte solution.

Evaluation of the Leaching Behavior of Hexavalent Chromium from Malaysian Electric Arc Furnace Steel Slag

This study investigates the leaching behavior of hexavalent chromium (Cr (VI)) from both industrial electric arc furnace steel slag and steel slag modified with up to 2% wt Cr2O3. The study was performed with European standard batch leaching test for 15 days and the lixiviant used were alkaline, de-ionized and rain water. The experimental work was also complimented with slag characterization using XRF, XRD and SEM/EDX analysis. After 15 days, Cr (VI) was found to be highest in rain water (0.016 mg/L) and lowest in de-ionized water (0.002 mg/L). With more Cr2O3 in EAF slag, more Cr will leach out based on the 2% wt Cr2O3 addition. Besides the lixiviant used, slag stirring speed and liquid to solid ratio also affect the dissolution of Cr (VI). With up to 2 wt % Cr2O3 in EAF slag, Cr (VI) dissolution was still lower than the threshold of 0.1 mg/L set by USEPA for public water systems. The analysis also indicated that the relative amounts of soluble basic and acidic oxides in the slag will affect the dissolution of Cr (VI).

Microstructural Study of Leached Nitrided Malaysian Ilmenite with Coal-Polystyrene Reductant

Titanium oxycarbonitride (TiOxCyNz) produced from Malaysian ilmenite consists of impurities such as iron that adversely affect the efficiency of chlorination process. In this paper, the dissolution of iron present in TiOxCyNz was performed using ammonium chloride (NH4Cl) solution at 70 °C from 4-6 hrs. Effects of acid concentration, catalyst amount and leaching time on the rate of iron dissolution were also investigated. Microstructural and/or morphological studies of the raw materials, and products were carried out by X-ray diffraction (XRD), X-ray Fluorescence (XRF), scanning electron microscopy (SEM), and Energy Dispersive X-ray analysis. The results obtained from SEM/EDX analysis for the reduced samples HR15 (15% Polystyrene (PS) + 85% coal (C)), HR25 (25% PS + 75% C) and HR35 (35% PS + 65% C) showed that most of the Titanium oxycarbonitrides were found in the circular shape with increase grain coarsening. Iron dissolution was accelerated with acid concentrations and it increased with increasing leaching time from 4 to 6 hrs. The results also showed that the percentage of Fe removed from titanium oxycarbonitride was ~ 76.85% at 70 °C for 6 hrs with the PS/C ratio of 0.18 and 1 wt. % of glucose as catalyst.

An Assessment of the Carbothermal Reduction of Malaysian Ilmenite by Statistical Design

Statistical design analysis (factorial design) was utilized to verify the significance and the interaction between the studied factors include temperature, reduction time and catalyst amount. Carbothermal reduction of iron ore sample was carried out at temperature between 1000°C to 1200°C. The effects of operating parameters studied were extent of reduction (X), carbon consumed (Cconsumed ) and nitridation (XN). Temperature was the most influential parameter that showed strong interaction with the operating parameters, meanwhile, reduction time and catalyst have showed the contrary results and had a very low percentage of contribution. The results of the experimental design showed that the extent of reduction reached up to 93% at 1200°C using 10 wt. % catalysts after 180 minutes reduction. The use of 0-10 wt % catalyst at 1200°C for 180 min reduction significantly affect the X but did not for Cconsumed and XN.Keywords: Carbothermal Reduction, Factorial Design, Malaysian Ilmenite, Nitridation.

Characterization and Gold Assaying Methods in the Assessment of Low Grade Gold Ore from Malaysia

The low grade gold ore obtained from a local gold mine in Malaysia was characterized using X-ray fluorescence analysis and scanning electron microscope/ energy dispersive X-ray analysis for the deportment of gold. Acid digestion was carried out to determine iron, aluminium, sulphur and arsenic using ICP-OES. Chemical assaying methods viz aqua regia leaching and lead fire assay followed by acid digestion were conducted to determine the head grade of the gold ore. Assessment of gold using fire assay was found reliable to reduce the interferences from the gangue minerals. Despite the lower limit of detection of ICP-OES, there was no appreciable amount of gold detected in the samples leached using aqua regia because of the interference from the gangue minerals and also due to the interlocking of gold with aluminosilicates phase which require high pressure and temperature leaching using hydrofluoric acid to liberate the gold. ICP-OES analysis is reliable depending on the degree of liberation of gold during acid digestion. The head grade for this type of low grade gold ore was found to be in the range of 0.31 g/t to 0.55 g/t where the gold was highly associated with aluminosilicate minerals.

The Effects of Experimental Variables on Iron Removal from Nitrided Malaysian Ilmenite by Becher Process

Iron-free titanium oxycarbonitride (TiOxCyNz) is a promising feedstock for production of titanium tetrachloride (TiCl4) at low temperatures. In this study, the effects of leaching variables such as temperature, time, particle size of staring material and concentration of the leaching solutions were evaluated on iron removal from nitrided Malaysian ilmenite by Becher process. The nitrided ilmenite was prepared by isothermal reduction with graphite at 1200 °C for 3 h in H2-N2 atmosphere. The aerated leaching experiments were conducted at 50–90 °C with addition of 0.3–2.0 wt% of NH4Cl catalyst. The highest extent of iron removal (XFe) was obtained at about 96.2% for the sample leached at 90 °C for 7 h with 2.0 wt% NH4Cl. The iron concentrate and titanium oxycarbonitride product were characterized by ICP-OES, XRD, XRF and SEM-EDX analyses. The results indicated that the aeration leaching process was a successful route to prepare low-iron titanium oxycarbonitride.

Effect of Carbon Reductant on the Formation of Copper Doped Titanium Oxycarbonitride by Carbothermal Reduction and Nitridation

In this paper, the effect of carbon reductant on carbothermal reduction and nitridation of copper-doped titanium oxide (Cu–TiO2) was investigated. Reduction was performed under H2–N2 (50 vol.% N2) gas mixtures with a temperature range of 1100–1300 °C for 1–3 h respectively. Three different carbon sources were investigated in the reaction which were graphite, activated carbon (AC) and carbon nanotube (CNT). The highest extent of reduction of 99.9% was obtained at 1300 °C for 180 min using 1:4 carbon to oxide molar ratio with CNT. Extent of nitridation was 71.7% while extent of carburization was 28.2% for this sample. Elemental analysis indicated an oxycarbonitride phase with a composition of Cu–TiO0.002C0.28N0.717. With CNT and AC as a reductant, the formation of Cu–TiOxCyNz occurred at 1100 °C after 180 min. Increasing the reduction temperature, time and molar ratio, the TiN and TiC contents in the synthesized Cu–TiOxCyNz are increased.

Removal of Cadmium and Zinc Contaminations in Landfill Leachate by Using Electrocoagulation Process

The research works involve the study of removal of cadmium and zinc contaminations in landfill leachate by electrocoagulation process. This project focused on leachate landfill from Pulau Burung, Nibong Tebal, Penang as an electrolyte solution. Heavy metals are the main factor contributing to pollution in leachate landfill. Types of electrodes used in this study were aluminium (grade 5052) and Stainless Steel (grade 316). The ranges of initial pH applied were pH (3, 4, 5, 6 and 7) and voltages applied were 1.5V, 2.0V and 2.5V. At the end of electrocoagulation process, the solutions were stored and analysed usingatomic absorption spectroscopy (AAS) to determine the final concentration of electrolyte solution. It was found difference electrodes have difference effectiveness in removing heavy metals, relies on the types of electrodes (aluminium or stainless steel) and also types of heavy metals that were being treated. The initial pH also gives the significant effect to removal of heavy metal and the maximum voltages give higher removal of heavy metal. Removal of cadmium and zinc by stainless steel electrode was more effective than aluminium electrodes at voltage of 2.5V. The removal using stainless steel was 22.45% and 97.54% respectively. For removal using aluminium electrodes 18.37% and 92.12% respectively. It was found that the maximum voltages give higher removal of heavy metal for all removal of cadmium and zinc. The removal maximum when the applied voltage was 2.5V and minimum at 1.5V.