Аннотация
Purpose. To evaluate the effect of pretreating copper-bearing ore with a microbial consortium comprising iron- and sulfur-oxidizing bacteria and filamentous fungi on the efficiency of subsequent sulfuric acid percolation leaching of copper. Methods. The initial ore was characterized using chemical, X-ray fluorescence, X-ray diffraction, and mineralogical ana-lyses. The thermodynamic stability of copper-bearing compounds was evaluated using an Eh – pH diagram for the Cu – Fe – S system constructed in HSC Chemistry 8. Iron- and sulfur-oxidizing microorganisms and filamentous fungi were isolated and cultivated on selective culture media. Percolation leaching was performed using H2SO4 solutions with concentrations of 5, 10, and 15 g/dm3. In 145-day column experiments, conventional sulfuric acid leaching was compared with leaching preceded by biological pretreatment of ore with particle sizes of less than 10 and less than 200 mm. Findings. The initial ore contained 0.71 wt.% total copper, 0.57-0.58 wt.% oxidized copper, 6.9 wt.% iron, and 2.57 wt.% sulfate ions. Copper was found to occur in both oxide and sulfide forms, including chalcopyrite. The microbial consortium contained iron- and sulfur-oxidizing bacteria, heterotrophic microorganisms, and filamentous fungi. Increasing the H2SO4 concentration from 5 to 15 g/dm3 increased copper recovery from 42.42 to 46.69%, while a concentration of 10 g/dm3 was selected for further experiments. Biological pretreatment increased copper recovery from ore with a particle size of less than 10 mm from 56.75 to 72.0% and from ore with a particle size of less than 200 mm from 54.45 to 66.3%. Originality. The effect of ore pretreatment with a consortium of iron- and sulfur-oxidizing bacteria and filamentous fungi on the subsequent sulfuric acid leaching of copper from ore with different particle sizes was experimentally established. The combined action of bacterial oxidation of iron- and sulfur-bearing compounds and metabolites produced by filamentous fungi was shown to increase the accessibility of copper-bearing mineral phases to acid dissolution. Practical implications. The results can be used to substantiate the parameters of combined biological pretreatment and sulfuric acid leaching of low-grade and mineralogically complex copper ores, as well as to develop heap-leaching flowsheets for copper-bearing mineral resources.