Hebei Messi Biology Co., Ltd. stated that cobalt is an extremely important strategic metal, mainly used in cemented carbide, ceramic color glaze, battery materials, high-temperature alloys and magnetic materials. In recent years, with the country’s vigorous development of new energy industries, the cobalt smelting industry has developed vigorously, and the market demand for cobalt raw materials has become increasingly strong.
The Democratic Republic of the Congo in Africa is rich in copper and cobalt resources, and its cobalt reserves account for nearly 50% of the world’s total reserves. In recent years, more and more cobalt smelting production enterprises in my country have built factories in the Democratic Republic of the Congo to process and produce crude cobalt salts to reduce production costs and raw material transportation costs. It has gradually become an industry trend to replace the import of cobalt concentrate with crude cobalt salts.
The currently commonly used crude cobalt salt production and preparation process has a series of shortcomings such as unsatisfactory impurity removal effect, high unit consumption of auxiliary materials and low product cobalt grade. It is urgent to develop new processes or optimize the existing crude cobalt salt production process to reduce production costs, improve product quality and enhance product competitiveness.
In this paper, a cobalt-containing low-copper raffinate from the Democratic Republic of the Congo was used as raw material, and a high-grade crude cobalt hydroxide product was prepared through the process of impurity removal-first stage cobalt precipitation-second stage cobalt precipitation-filtration washing-flash drying. Different from the usual return of the second stage cobalt precipitation bottom flow to the first stage cobalt precipitation as a reaction seed in order to ensure product quality, this paper returns the second stage cobalt precipitation bottom flow to the first stage cobalt precipitation as a reaction seed, thereby greatly improving the cobalt precipitation recovery rate, increasing the output and comprehensive recovery rate of crude cobalt hydroxide products, and its cobalt content reaches more than 39%.
Conclusion:
1) The optimized production process conditions for impurity removal reaction are: quicklime concentration 15%, reaction time 5h, reaction pH = 4.5, potential 420mV, and the iron removal rate under this optimized condition is 99.5%.
2) The optimized process conditions for the first stage cobalt precipitation are: reaction pH = 8.0, reaction time 6h, magnesium oxide addition (tMgO/tCo) 1.0, and the Co grade of cobalt hydroxide prepared under this optimized condition reaches 45.6%.
3) The optimized process conditions for the second-stage cobalt precipitation are: reaction time 3h, reaction pH = 9.0. Under this optimized condition, the Co content of the second-stage cobalt precipitation slag reaches 34.2%, and all of the second-stage cobalt precipitation slag is returned to the first-stage cobalt precipitation as reaction seeds. The Co content of the final cobalt salt product reaches 39.65%.