Simulation of Bioleaching Heat Effects for Enhancement of Copper Recovery from Sarcheshmeh Chalcopyrite
- PDF / 1,656,184 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 104 Downloads / 142 Views
TRODUCTION
AS worldwide reserves of high grade ore are rapidly diminishing because of heavy exploitation, traditional techniques of chemical processing have become less economically attractive. Microorganisms bear, however, a clear advantage over the traditional techniques by offering clean and economically viable alternatives. Microorganisms such as bacteria and fungi convert metal compounds into water-soluble forms. They act, hence, as biocatalyst of the leaching processes. Bioleaching occurs naturally while harnessing metal recovery from low-grade ores.[1] Among the most significant applications of microorganisms to extract precious metals is heap bioleaching. Heap bioleaching is a hydrometallurgical process which can take place over a period of months to years. It involves the application of acid solution and bacteria (either natural or inoculated). To keep the aerobic bacteria alive, air is injected (sparged) into the heap using pipes laid before heap stacking. The solution infiltrates the heap from the top, soaking the ore, and leaching the metals into solution. Finally, the solutions are collected at the base of the heap for subsequent electrowinning of the metal.[2] The need for efficient heap bioleaching operations has led to scientific research and development of mathematical models. A number of heap bioleaching models developed before have been reviewed.[3]
ALI REZA MAHMOUDIAN, Ph.D. Student, and K. SADRNEZHAAD, Professor, are with the Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave., P. O. Box 11155-9466, Tehran, Iran. Contact e-mail: ali_reza_ [email protected] ZAHRA MANAFI, Head Researcher, is with the Hydrometallurgy Research Unit, R&D Center, Sarcheshmeh Copper Complex, Rafsanjan, Iran. Manuscript submitted July 10, 2013. METALLURGICAL AND MATERIALS TRANSACTIONS B
Among the significant processes that occur in a bioheap are the heat generation and conservation. An analysis of heat conservation for copper sulfide heap leaching has been accomplished with the aid of a computer model.[4] Such analysis is carried out for several reasons. First, the bacteria which catalyze the oxidation reactions are sensitive to temperature. Second, many oxidation reactions influencing the copper recovery are strongly temperature dependent.[3,4] Chalcopyrite is the most important source of copper in the world; however, its sources are increasingly declining in grade.[5] It has been observed that chalcopyrite passivation is not observed in thermophile leaching.[6,7] Therefore, the aim of the current study is to find the conditions by simulation under which thermophilic leaching is established within the heap of Sarcheshmeh copper mine.
II.
MATERIALS AND METHODS
Heap bioleaching involves loading of material onto an impervious base, irrigating the top of the heap with a suitable lixiviate, aeration from bottom, and treatment of the pregnant solution draining from the heap for extraction of the dissolved metal values. The leaching solution flows downward under influence of gravity, and a
Data Loading...
