Congo (Kinshasa) is the country with the largest reserves of cobalt resources in the world, and its production capacity accounts for more than half of the world’s total production. Cobalt resources in Congo (DRC) mainly exist in the form of copper-cobalt symbiotic ores, and a few are independent cobalt ores. The hydrometallurgy of copper-cobalt ore generally adopts the leaching-extraction-electrodeposition process to produce cathode copper, and the cobalt-containing raffinate after copper extraction generally adopts the impurity removal-cobalt precipitation process to produce cobalt salts or cobalt compounds. The impurity removal process generally uses the neutralization and hydrolysis method to remove impurities such as iron ions and iron ions in the solution. The neutralizer generally uses lime or slaked lime, and the oxidation removal (iron, manganese, etc.) method usually includes sulfur dioxide Mixed gas oxidation with air, strong oxidant (sodium chlorate etc.) Contaminant sodium ions are introduced into the system. The sulfur dioxide and air mixed gas oxidation method has the advantages of relatively low potential to avoid cobalt loss and not introduce impurity ions.
The cobalt precipitation process generally uses a precipitant to separate cobalt ions from the solution by forming insoluble cobalt salts or cobalt compounds. Precipitating agents used in the cobalt precipitation process usually include HS, sodium salt, etc. HS is toxic, harmful to human health and easy to cause environmental pollution. Sodium salts such as Na, CO, NaOH, etc. have strong alkalinity, and it is easy to form a solution that partially enters an environment with an excessively high pH, causing other impurity ions in the solution to precipitate together with cobalt ions, resulting in lower cobalt grades in cobalt products and higher impurities. Moreover, the use of sodium salts will introduce sodium ions into the system and be difficult to handle. When the concentration of sodium ions is high, production will be adversely affected. Activated magnesia has weak alkalinity and is relatively safe to use, and the wastewater after cobalt precipitation is easier to treat.
This paper provides a new process of removing impurities from cobalt-containing raffinate, cobalt precipitation in the first stage, cobalt precipitation in the second stage of slaked lime, and...
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