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Chemistry for Sustainable Development

2017 year, number 4

On the Issue of Processing Hydroxide Arsenic Sludges of Copper Refining Production

Ural Federal University named after the first President of Russia Boris Yeltsin, Yekaterinburg, Russia
Keywords: hydroxide sludge, calcium metaarsenite, complexing agent, leaching, EDTA
Pages: 367-371


The paper carried out X-ray phase analysis of arsenic sludge, whereby the following compounds were detected: (CaSO4) • 2H2O, Cu(OH)2, Ni(OH)2, Fe(OH)3, Ca(OH)2, and Zn(OH)2. The presence of arsenic (III) as calcium metaarsenite (Ca(AsO2)2) was also determined. Options for extraction of non-ferrous metals from multicomponent hydroxide raw materials containing significant amounts of arsenic were considered. Solutions of sulphuric acid, ammonium salts, oxyethylidenediphosphonic (OEDP), ethylenediaminotetraacetic acid (EDTA), alkaline metal tartrates were explored as reagent solvents. The values for the logarithms of the stability constants of copper (II), nickel (II), and calcium (II) complexes with appropriate ligands were presented. According to experimental data, the use of substances that ensure the copper and nickel extraction as complexes while maintaining pH > 5 allows for almost complete elimination of arsenic dissolution. It was experimentally proven that ammoniacal leaching and leaching in solutions of EDTA salts did not lead to arsenic contamination of the filtrate ensuring copper and nickel extraction from sludges. The use of EDTA and its salts also simplified technology and equipment selection for further solution processing. The findings led to the conclusion that the use of EDTA solutions at leaching of sludges of neutralising industrial solutions was promising.

DOI: 10.15372/CSD20170405