The leaching of szaibelyite ore in NaOH solution to prepare sodium metaborate dihydrate was investigated in a batch reactor. The effects of the reaction temperature, NaOH concentration and liquid to solid ratio on the leaching rate have been evaluated and the conversion of boron could reach 95% in 2 h under the optimum reaction conditions. There were two distinct stages in the leaching process and kinetics of both stages followed shrinking core model. The activation energy of stage one (initial 30 min) and stage two (30-120 min) was estimated to be 41.57 kJ/mol and 40.41 kJ/mol, respectively. The kinetics analysis showed that the leaching process was controlled by chemical reaction. (C) 2015 Elsevier B.V. All rights reserved.
In this study, strontium nitrate extraction from celestite in nitric acid solutions was investigated using the leaching method. The influences of acid concentration, solid-to-liquid ratio, stirring speed, and reaction temperature on the leaching of strontium from celestite concentrate were studied. The results showed that the leaching rate increased with increasing acid concentration, stirring speed, and temperature and decreased with increasing solid-to-liquid ratio. The particle size was fixed in all of the dissolution experiments. The results showed that the stirring speed and the temperature were the most influential parameters with respect to the leaching process. The kinetic model best fit control by diffusion through the product layer. The activation energy of the dissolution celestite in nitric acid solutions was calculated to be 42.22 kJ/mol.
The resources of refractory gold ores are abundant, and their effective treatment can bring good economic benefits. This paper investigated the kinetics of leaching gold from refractory gold ores by ultrasonic-assisted electro-chlorination. The effects of ultrasound time ratio, initial hydrochloric acid concentration and leaching temperature on the kinetic parameters were discussed. It is found that the leaching ratio goes up with all the factors increasing. The reaction kinetics is controlled by diffusion. When ultrasound improves the diffusion by reducing the diffusion resistance, the activation energy increases to 37.1 kJ/mol.