Hebei Messi Biology Co., Ltd. stated that the current cobalt product of the cobalt salt plant is crude cobalt carbonate, which is precipitated with sodium carbonate, and the post-precipitation liquid is directly discharged. The defect of this process is that there is a large amount of sodium sulfate in the discharged waste liquid. The wastewater containing sodium sulfate is not easy to treat. Direct discharge will cause certain environmental pollution and have an adverse effect on water quality. In the dry season, white crystalline sodium sulfate will appear from the wastewater discharge outlet and the downstream riverbed, which is easy to attract attention. At present, the environmental protection policies of the Democratic Republic of the Congo are gradually standardized, and the law enforcement is gradually strict. Some companies have adopted the activated magnesium oxide cobalt precipitation process to produce cobalt hydroxide, changing the past cobalt carbonate product plan to reduce environmental pollution.
Therefore, it is necessary for the cobalt salt plant to improve the process and reduce waste liquid discharge. The cobalt salt enterprise cooperating with Hebei Messi Biology Co., Ltd. has conducted a small test on this. The results show that the amount of activated magnesium oxide cobalt precipitation is about 1/2 of that of sodium carbonate, and the price of suitable activated magnesium oxide is about twice that of sodium carbonate. Therefore, the cost of auxiliary materials consumed in the step of cobalt precipitation is close, but some logistics and warehousing costs can be saved. The cobalt grade in the produced cobalt hydroxide is about 2 percentage points lower than that in cobalt carbonate, which is a more environmentally friendly solution for producing crude cobalt products. At the same time, the magnesium sulfate waste liquid generated by cobalt precipitation is easy to handle.