Research of the treatment of depleted nickel­plating electrolytes by the ferritization method

Abstract

Considerable attention has been paid recently to the development of comprehensive recycling of industrial wastewater, which provides for an appropriate degree of purification for both organization of circulation water supply, and subsequent disposal of waste of water treatment. The improved ferritization process, which allows decreasing original concentration of nickel ions in depleted electrolytes of nickel plating from 50–100 g/dm 3 to <0.2 mg/dm 3 , was presented. The experimental ferrite-reactor with the use of the traditional thermal and electromagnetic pulse method of activation of ferritization process in the range of generating frequencies of up to 0.9 kHz was developed. Economic benefits of the use of the electromagnetic pulse activation compared to the high temperature one were identified. Kinetics of extraction of nickel and iron ions from aqueous solutions was explored. The impact of the basic technological parameters of ferritization at different ways of activation was experimentally determined. The most effective results of treatment of highly concentrated wastewater were achieved using the electromagnetic pulse (T=20 °C) and thermal (T=70 °C) way of activation of the ferritization process at the original ration of concentration Fe 2+ /Ni 2+ within 3/1–4/1, total concentration of ions of heavy metals of 20–25 g/dm 3 , original pH of the reaction mixture of 9.5 and duration of ferritization process of 15 min. Research into phase composition and physical properties of ferritization sediments was performed. Comparative analysis of sediment volumes at different ways of compaction was carried out. Sediments are mainly characterized by the crystalline structure, ferromagnetic properties, and considerable chemical resistance. This provides for actual environmental ways of recycling, which makes it possible to avoid the loss of valuable and, at the same time, toxic metal – nickel. The proposed comprehensive process of recycling liquid industrial waste prevents pollution of the environment, ensures effective and efficient use of water, raw materials, and power in the system of galvanic production.