Changes in physical and chemical properties of ore slurry under ultrasonic treatment

When ore is ground in preparation for bacterial-chemical leaching, oxide films are inevitably formed on the surface of sulfides, which generally inhibits the leaching process. Ultrasonic treatment of the ore slurry may be used to speed the process up. An analysis of existing studies has shown that this treatment changes the physical and chemical properties of the slurry, while bacterial-chemical leaching requires that the specified physical and chemical parameters of the inoculum and ore slurry mix are maintained. Ultrasonic treatment studies of the ore slurry of the Shanuch deposit (Kamchatka) therefore included mandatory monitoring of all changes in the properties. The experiment was carried out using a laboratory unit configured for the two options: with and without slurry circulation through the chamber. With the slurry circulating through the processing chamber, the values of pH, Eh, and T were recorded after every 30 seconds. For the process without circulation, these values were recorded with an interval of 180 seconds. The studies have shown an increase in the pH values by 0.92, 2.2, and 3.16 % when exposed to ultrasonic treatment intensities of 11, 21, and 28 W/cm2, respectively, for 15 minutes with slurry circulation in the chamber. The Eh values for the slurry with the same process parameters dropped by 8, 11 and 15 mV, and the slurry temperature increased by 0.7, 1.3, and 1.7 °C, respectively. When ultrasonic treatment was performed without slurry circulation in the chamber of the laboratory unit, the pH values increased by 2.55, 3.2, and 3.7 % and the Eh values decreased by 12.2 to 20.9 mV, with a temperature rise within 1.4 to 2.3 °C.