Abstract

The results of the use of seawater in the bioleaching process of copper sulphide minerals are provided. The microorganisms used were isolated from an abandoned mining deposit located in the Quebrada del Arrayan, Coquimbo region, Chile, were identified by molecular methods (PCR and sequencing). The microorganisms were cultivated in Silverman and Lundgren 9K medium, pH 1.7, at room temperature and low light. They were monitored every 24 hours to see bacterial growth and pH variation. Subsequently, the microorganisms adapted to different percentages of seawater 15%, 30%, 45% and 60%, finding that native species are tolerant to different percentages of seawater. Bioleaching tests were carried out in reverse micro columns, in the microbiology laboratory, manufactured by a polyethylene tube, with a height of 52 cm and a diameter of 4 cm. Fluid transport was generated by gravity and flood Two tests were implemented: 60% sea water and 100% fresh water, the columns were filled with the same sulphided mineral with a percentage of total copper of 1.39 and soluble copper of 0.19%, with a ½ inch grain size. Each column was mounted with 5 liters of acidic solution at pH 1.7 and a flow rate of 2.9 cm3 / min was set. It was found that the inverse column with 100% fresh water extracted a total of 7.16% of the copper and the column with 60% with sea water, extracted 3.41% in the same period of time. It is important to mention that the efficiency in the first 100 hours of bioleaching was higher in the column with 60% of seawater. These results open up the possibility of using sea water in the metallurgical mining processes, in areas where there is a water shortage.