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Thermal Simulation of Bioheap

Mahmoudian, Alireza | 2013

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 45679 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Sadrnezhad, Khatiboleslam
  7. Abstract:
  8. Nowadays, because of drastically decrease of copper sulfide ore’s grade, and difficulties in leaching of them, new processes of copper production like bioleaching technique become significant. Finding the optimal conditions for bioleaching, require investing a lot of time and cost. Computer simulation is useful in this case. Temperature, affects the kinetics of dissolution reactions, type and growth rate of bacteria, and finally, rate and amount of recovery of valuable copper metal from ores, so determination of temperature within the bioheap is very important. Thermophiles are better than mesophiles in chalcopyrite bioleaching and in the range of 55 to 65 degree centigrade, thermophiles have the most activity. Computer simulation is used to find the distribution of temperature within the bioheap because of its simplicity and flexibility.
    A heat transfer model was formulated to determine the distribution of temperature within a bioheap of chalcopyrite of Sarcheshmeh copper mine. Numerical solution was done using finite difference method by available software. Practical bioleaching were done by mixed mesophilic and thermophilic microbes for Cu extraction. For this aid, mixed native mesophilic and thermophilic microbes, were adapted in industrial medium. Establishing the optimal conditions for thermophiles growth, was selected as the main goal. The solution irrigation and aeration rates were taken into account as the main operational factors. Three 4m test columns and two 6m cone shape test bioheap pads were prepared and some tests were done in predetermined conditions. The model was validated by comparing the temperature profiles of test columns and bioheaps with the model results. The model was used to find the optimum ratio of irrigation rate to aeration rate. It was seen that when the solution was fed at a flow rate of 5 kg/m2.h and air was blown at a flow rate of 7.5 kg/m2.h, the transition from a mesophilic to thermophilic state inside the heap was occurred. In this situation, the maximum temperature rise inside the heap was 59oC after 60 days.
  9. Keywords:
  10. Thermal Modeling ; Chalcopyrite ; Bioleaching ; Thermophilic Bacteria ; Mesophile Bacteria

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