China Nonferrous Metallurgy

The rational treatment of spent electroless nickel plating bath is a subject of environmental protection and resource utilization owing to its large emission and complex composition. The recycling of sulphur, sodium, phosphorous and carbon elements in the spent bath is seldom investigated. BaSO4 powders were prepared by a co-precipitation method from the spent bath where nickel ions were removed, using the complexation of citrate anions for barium ions. It was investigated that the effects of the molar ratio of citrate ions and barium ions, pH value, temperature and time on the removal rate of sulfate ions, barium sulfate’s productivity, morphology and particle size distribution. The results show that under the condition of the ions ratio of 1∶3, the pH value of 9, the temperature of 55℃ and the time of 10h, the removal rate of sulfate ions and the productivity of barium sulfate reach 99.7% and 98.9%, respectively. The obtained barium sulfate consists of narrow-distribution uniform-sized high-purity spherical-like particles. This route achieves the high-value resource utilization of sulfate anions in the spent electroless nickel plating bath, which conforms to the concept of green circular economy.