Wet Production of Battery Grade Cobalt Sulfate Extract/Stripping Solution for Oil and TOC Removal

As low-grade cobalt ore becomes the mainstream raw material in the cobalt industry, many companies use wet smelting to process low-grade cobalt ore and prepare cobalt intermediates (crude cobalt hydroxide, crude cobalt carbonate, etc.) to reduce costs. However, these cobalt intermediates often have high contents such as CuZnFeMnNi, which need to be removed after acid dissolution to prepare battery grade cobalt sulfate.

The process of preparing battery grade cobalt sulfate from crude cobalt hydroxide is divided into the following steps: using dilute sulfuric acid to dissolve impurities, reducing leaching, oxidizing precipitation to remove iron, manganese, and arsenic, ammonium fluoride precipitation to remove calcium and magnesium, P204 extraction for deep purification and impurity removal, P507 extraction for sodium removal and separation of cobalt and nickel, and then the organic phase loaded with cobalt is back extracted with sulfuric acid solution to obtain cobalt sulfate for the preparation of battery grade cobalt sulfate.

Now, due to the large-scale retirement of power batteries, the main sources of cobalt containing battery waste are waste lithium cobalt oxide batteries and waste nickel cobalt manganese batteries. The process of recycling cobalt containing battery waste to prepare battery grade cobalt sulfate mainly consists of two steps. The physical process is the pre-treatment stage of waste lithium batteries, mainly including mechanical treatment, heat treatment, mechanochemical methods to strip and separate the positive electrode material of waste lithium-ion batteries; The chemical process is the recycling stage of waste lithium-ion battery cathode materials, mainly including acid leaching, biological leaching, solvent extraction, electrochemical treatment and other processes.

After treating impurities such as iron, copper, and aluminum in the leachate, various metal ions (manganese, cobalt, nickel) are separated and purified using extractants in different pH ranges. Transition metals exist in the organic phase in the form of organic complexes during extraction, and the impurity content of the cobalt solution after back extraction is lower than the national standard, which can be used to prepare battery grade cobalt sulfate.

However, due to the presence of hydrophilic groups in the organic phase, the extracted residue and back extract often contain oil phase components. If the oil phase is not removed, it will affect the purity and performance of subsequent cobalt products. These oil phases are mainly dispersed oil, dissolved oil, and emulsified oil. The difficulty lies in dissolving and emulsifying oil.

Due to the presence of emulsified oil, dissolved oil, and dispersed oil, the oil content in the residual or reverse extract is greater than 200ppm, which is much higher than the usage requirements.

Haipu HP268 is a polymer based porous adsorption resin specifically used for oil removal from water bodies. It has good mechanical and chemical stability, large adsorption capacity for oil, fast adsorption rate, easy regeneration, simple operation, and long service life.

HP268 is suitable for processing various oil containing extracts or back extracts; The leaching solution is used to remove heterocyclic rings and TOC (residual P204P507 sulfonated kerosene, etc.) from the cobalt sulfate nickel sulfate feed solution. TOC can be reduced to below 20mg/L. In addition, it can be applied to the resource utilization of oily wastewater generated by extraction processes, various feed solutions for oil removal, desorption regeneration, and steam distillation, without introducing new impurities into the feed solution.