Process and kinetics of the selective extraction of cobalt from high-silicon low-grade cobalt ores using ammonia leaching

An ammonia-based system was used to selectively leach cobalt (Co) from an African high-silicon low-grade Co ore, and the other elemental impurities were inhibited from leaching in this process. This process was simple and environmentally friendly. The results revealed that the leaching ratio of Co can reach up to 95.61% using (NH4)(2)SO4 as a leaching agent under the following materials and conditions: (NH4)(2)SO4 concentration 300 g/L, reductant dosage 0.7 g, leaching temperature 353 K, reaction time 4 h, and liquid-solid ratio 6 mL/g. The leaching kinetics of Co showed that the apparent activation energy of Co leaching was 76.07 kJ/mol (i.e., in the range of 40-300 kJ/mol). This indicated that the leaching of Co from the Co ore was controlled by an interfacial chemical reaction, and then the developed leaching kinetics model of the Co can be expressed as 1- (1- alpha)(1/3) = 28.01 x 10(3)x r(0)(-1) x C-(NH4)2SO4(1.5) x exp(-76073/8.314T) x t, where alpha is the leaching ratio (%) of Co, r(0) is the average radius (m) of the Co ore particles, T is the temperature (K), and C-(NH4)2SO4 is the initial reactant concentration (kg/m(3)).

Automated summary

An ammonia-based system was utilized to selectively leach cobalt (Co) from an African high-silicon low-grade Co ore, while inhibiting other elemental impurities from leaching. The process was shown to be simple and environmentally friendly, achieving a Co leaching ratio of up to 95.61% using (NH4)(2)SO4 under specific conditions. The leaching kinetics of Co indicated that the process was controlled by an interfacial chemical reaction, and a developed model was established to express the leaching behavior of Co.