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This study shows that agglomeration and bioleaching can be used to extract copper from fine-grained low-grade sulphide copper ores. Column bioleaching test results for ore from Sarcheshmeh, Iran, which averages 0. 22% Cu with 30% in the 50% of particles finer than 1 mm and with a high clay content, showed that heap bioleaching for 200-250 days was suitable. Lime and sulphuric acid binders achieved the best agglomerate and column tests for 105 days extracted 77.5% of Cu, compared with 57% in a non- biological control column., This study shows that agglomeration and bioleaching can be used to extract copper from fine-grained low-grade sulphide copper ores. Column bioleaching test results for ore from Sarcheshmeh, Iran, which averages 0. 22% Cu with 30% in the 50% of particles finer than 1 mm and with a high clay content, showed that heap bioleaching for 200-250 days was suitable. Lime and sulphuric acid binders achieved the best agglomerate and column tests for 105 days extracted 77.5% of Cu, compared with 57% in a non- biological control column.

The low-grade Iranian ore contains pyrite, which causes some problems in the flotation of chalcopyrite and other sulphide minerals. It was shown in experiments that selective flotation of the copper sulphides is possible when they interact with Acidithiobacillus ferrooxidans grown in the presence of either natural ferrous ion or sulphur. The bacteria did not adhere significantly to the chalcopyrite but could selectively adhere to the surface of pyrite, hindering its flotability and acting as a depressant. Cells strongly adsorbed on the pyrite surface may have hindered adsorption of xanthate, whereas the collector could be adsorbed on the copper sulphide minerals to promote their hydrophobicity. Development of the technology would not only result in reduced emissions of sulphur dioxide but would also solve the problem of pipelines becoming blocked by lime, resulting in considerable cost savings., The low-grade Iranian ore contains pyrite, which causes some problems in the flotation of chalcopyrite and other sulphide minerals. It was shown in experiments that selective flotation of the copper sulphides is possible when they interact with Acidithiobacillus ferrooxidans grown in the presence of either natural ferrous ion or sulphur. The bacteria did not adhere significantly to the chalcopyrite but could selectively adhere to the surface of pyrite, hindering its flotability and acting as a depressant. Cells strongly adsorbed on the pyrite surface may have hindered adsorption of xanthate, whereas the collector could be adsorbed on the copper sulphide minerals to promote their hydrophobicity. Development of the technology would not only result in reduced emissions of sulphur dioxide but would also solve the problem of pipelines becoming blocked by lime, resulting in considerable cost savings.

The catalytic activity of five cultures of acidophilic bacteria for pyrite oxidation were studied for various pyrite pulp densities. These were Thiobacillus ferrooxidans DSM 581 as a mesophile, strain TSB as a moderate thermophile and Acidianus brierleyi DSN 1651, Sulfolobus acidocaldarius ATCC 33909nm, and strain L1 as extreme thermophiles. Optimum growth conditions for these were determined. The wild strain TSB, isolated from Iranian hot acidic springs and not previously used metallurgically, was found to the most effective and likely to be adaptable and to grow under leaching conditions, The catalytic activity of five cultures of acidophilic bacteria for pyrite oxidation were studied for various pyrite pulp densities. These were Thiobacillus ferrooxidans DSM 581 as a mesophile, strain TSB as a moderate thermophile and Acidianus brierleyi DSN 1651, Sulfolobus acidocaldarius ATCC 33909nm, and strain L1 as extreme thermophiles. Optimum growth conditions for these were determined. The wild strain TSB, isolated from Iranian hot acidic springs and not previously used metallurgically, was found to the most effective and likely to be adaptable and to grow under leaching conditions

An investigation was carried out into the use of Thiobacillus ferrooxidans bacteria in the selective flotation of Sarcheshmeh low-grade, pyrite-containing Cu sulphide ore. In the presence of Thiobacillus ferrooxidans and xanthate as collector pyrite was depressed while chalcopyrite and other sulphide minerals were unaffected. The pulp pH remained unchanged. The results showed that the surface chemical properties of pyrite and sulphide ores could be changed in the presence of the bacteria to achieve the desired effects in flotation. Recovery of pyrite in the presence of the bio-depressant was 50% lower. Recovery of chalcopyrite was not affected., An investigation was carried out into the use of Thiobacillus ferrooxidans bacteria in the selective flotation of Sarcheshmeh low-grade, pyrite-containing Cu sulphide ore. In the presence of Thiobacillus ferrooxidans and xanthate as collector pyrite was depressed while chalcopyrite and other sulphide minerals were unaffected. The pulp pH remained unchanged. The results showed that the surface chemical properties of pyrite and sulphide ores could be changed in the presence of the bacteria to achieve the desired effects in flotation. Recovery of pyrite in the presence of the bio-depressant was 50% lower. Recovery of chalcopyrite was not affected.

The bacterial leaching was investigated of Cu dust from the smelting furnaces at the Sarcheshmeh, Iran, Cu mine. Sulphuric acid leaching was performed prior to bacterial leaching and shaking flask experiments carried out using a mixed culture of thiobacilli. Cu recoveries from inoculated and control flasks using 5% pulp density were 87% and 38%, respectively, after 22 days., The bacterial leaching was investigated of Cu dust from the smelting furnaces at the Sarcheshmeh, Iran, Cu mine. Sulphuric acid leaching was performed prior to bacterial leaching and shaking flask experiments carried out using a mixed culture of thiobacilli. Cu recoveries from inoculated and control flasks using 5% pulp density were 87% and 38%, respectively, after 22 days.