BIOLEACHING OF BOGOR ZINC SULPHIDE CONCENTRATES USING BACTERIUM Citrobacter youngae SKC-5

• Main Author: KARINDA RAMADHANI, SARAH
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/24216
• Institution: Institut Teknologi Bandung

Zinc is one type of metals that is classified as base metal. Zinc is ranked in the top four of the world as the most commonly used metal after iron, aluminum and copper. One of the most prominent chemical characteristics of zinc is the ease of zinc to oxidize to form a protective oxide layer so that it is often used as metal corrosion preventive material, especially on iron and steel. Corrosion preventing process by zinc is called as galvanizing. Zinc is mostly produced from a primary mineral source that is zinc sulphide minerals (sphalerite). To date, sphalerite processing is dominated by hydrometallurgical process, especially RLE process (Roasting-Leaching-Electrowinning). The big challenge in applying RLE process is the emission of a harmful pollutant gas, sulfur dioxide gas (SO2). As an alternative to RLE process, nowadays bioleaching method is being used where it is more environmentally friendly and requires lower cost and energy. The present study investigated Zn bioleaching process from sphalerite concentrate, which was kindly provided by PT. BCMG Tani Berkah, Bogor, using the bacterium Citrobacter youngae SKC-5. <br /> <br /> <br /> <br /> The experiments was started with concentrate sample preparation, including water content removal, grinding, sieving to obtain a sample size of -200 mesh (-75&#956;m), and sampling by using riffle-splitter method. Prepared samples were then brought to the next process of bioleaching experiments which began with the culture of the bacterium Citrobacter youngae SKC-5 for 3.5 days on modified-Fe-broth medium. Leaching experiments using Citrobacter youngae SKC-5 was performed on several experimental variables such as FeSO4.7H2O concentration, medium initial pH, pulp density, substrate source and bacterial inoculum to study their effect on zinc extraction, bioleaching selectivity to dissolved iron and changes in Eh-pH during leaching process. Bioleaching took place at room temperature using an orbital shaker at 180 rpm. <br /> <br /> <br /> <br /> Experimental results showed that the highest extraction of zinc was 99.98%, which was obtained from leaching time of 3 days at 1% w/v pulp density, 15 g/l FeSO4.7H2O, 20% v/v bacterial inoculum without pH adjustment. At the highest extraction percentage of zinc, a high selectivity index for iron was found to be 0.986. <br />