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Magnesium sulfate waste liquid is an important by-product generated during the production of nickel sulfate, and it contains large amounts of nickel and cobalt elements. If these elements are not effectively recycled, it will not only result in a huge waste of resources but may also cause environmental pollution. The Magnesia Sulfate purification process developed by Kohaisi takes into full account factors such as water quality and volume in actual production, employing a flexible design to address various challenges. Taking a real project as an example, the designed water volume is 1,000 tons per day, with an operation time of 24 hours. In terms of the quality of the water entering the system, the magnesium concentration in the magnesium sulfate solution is around 10 g/L; it also contains high levels of cobalt ions (800 mg/L) and nickel ions (500 mg/L). The required quality standards for the effluent specify that the levels of cobalt and nickel must be below 1.0 mg/L in order to meet the requirements of subsequent processes such as evaporation and crystallization. Considering the characteristics of magnesium sulfate waste liquid, Kehaisi conducted a comparison of various treatment processes, including extraction, precipitation, and ion exchange. Extraction process: Although the extraction method offers advantages such as high efficiency in extraction and separation as well as low reagent consumption, it requires a large amount of reagents in practical applications, results in high experimental costs, and involves complex procedures, which makes it unsuitable for large-scale industrial use. Precipitation process: Although the precipitation method can be used to remove nickel and cobalt by adding precipitants, it is difficult to control the location of precipitation, the reproducibility is poor, and the resulting metal particles are large with low uniformity, making it difficult to meet the requirements of high-precision processing. Ion exchange process: Due to its efficiency, wide applicability, cost-effectiveness, and stable quality of the treated water, the ion exchange method has been chosen as the process for purifying magnesium sulfate and removing nickel and cobalt in Kehaisi’s operations. In terms of the process flow, Kohaisi adopts a core process consisting of \"mother liquor + quartz sand filter + activated carbon filter + ion exchange resin\"; through the synergistic action of various stages, it achieves efficient removal and recovery of nickel and cobalt from magnesium sulfate wastewater. Pre-treatment stage: The raw liquid is first pre-treated using a quartz sand filter and an activated carbon filter to remove impurities such as suspended solids and organic matter, thereby providing favorable water conditions for the subsequent treatment with ion exchange resins. Ion exchange stage: The pretreated wastewater enters the ion exchange resin stage. Corex has specifically selected the Tulsimer® CH-90Na nickel-cobalt removal specialty resin, which possesses an excellent ability to selectively remove divalent metal ions such as Cu2⁺ and Ni2⁺. In magnesium sulfate waste liquid, nickel and cobalt exist mainly in the form of divalent ions; therefore, this resin can remove them efficiently. At the same time, this resin also possesses good regeneration properties; it can be regenerated using hydrochloric acid or sulfuric acid, thereby extending its service life and reducing operating costs. Effluent quality: After treatment with ion exchange resin, the levels of nickel and cobalt in the wastewater were significantly reduced, falling below 1.0 mg/L in both cases, thus meeting the requirements for effluent quality. Process advantages and application prospects, scheme design, resin selection and testing, technical consultations regarding equipment operation: 15271938854. The magnesium sulfate purification process developed by WeiDian KeHaisi for removing nickel and cobalt offers significant advantages: efficient removal – the use of high-performance ion exchange resins enables effective removal of nickel and cobalt from magnesium sulfate wastewater. Resource recycling: The removed nickel and cobalt can be recycled through subsequent processing, reducing production costs and improving resource utilization. Environmental protection and energy savings: Compared with traditional precipitation methods, this process reduces the consumption of alkalis and the generation of waste residues, thereby lowering the risk of environmental pollution. At the same time, this process operates stably and reliably, is easy to maintain, and reduces operating costs. Wide range of applications: This process is not only suitable for treating magnesium sulfate waste liquid generated during the production of battery-grade nickel sulfate, but it can also be applied to the treatment of other wastewater containing nickel and cobalt, offering broad market prospects.