Investigation of the process of precipitation of arsenic from copper electrolyte with manganese oxide (IV)

Abstract

The work is aimed at researching the process of depositing arsenic from copper electrolyte with manganese oxide (IV) using the method of stochastic determinated design of experiments on four levels. The chosen factors are: the frequency of dispensing of the precipitant; the ratio of precipitant to arsenic; the temperature of process; concentration of sulfuric acid; duration of experiment. Analysis of the partial dependencies of arsenic deposition showed that the increase in the amount of precipitant and the duration of the experiment had a significant influence on the course of the process. IR spectroscopy of precipitation showed the presence of arsenate ions AsO4 3– in them. The kinetic curve of the differential-thermal analysis of the solid sediment characterizes the process of its destruction as a step-wise process — the removal of crystallizated water (from 250 ºС to 350 ºС), the decomposition of manganese hydroarsenate (from 470 ºС to 630 ºС) and manganese arsenate (from 690 ºС to 900 ºС). It is established that the process of formation of manganese arsenate is a result of parallel reactions of interaction of sulfate ions with manganese ions with the formation of a sulfate complex, interaction of the manganese sulphate complex with arsenate ions with the formation of manganese hydroarsenate, and the transition of hydroarsenate to manganese arsenate.