UDC 669. 054:669.849 Results are provided for thermal and thermogravimetric studies of lead sludge in the presence of and without oxidizing agents in order to determine the thermally active part of the charge composition. It is shown that during oxidation firing of lead sludge the process begins with charge dewatering and organic compound decomposition, and rare metal oxidation commences after complete destruction of organic compounds. Addition of sodium nitrate or calcium hypochlorite oxidizing agents provides complete oxidation of rhenium and osmium in the range of 400-650°C with the subsequent extraction of osmium into sublimate and concentration of rhenium in the form of perrhenate compounds in the ash. In this case decomposition of organic substances proceeds in parallel with oxidation reactions of rare metals without affecting their oxidation.
The article presents the results of oxidative leaching of lead sludge from copper production in order to extract rhenium into solution. The optimum regimes for product leaching man-made product in the presence of sodium peroxocarbonate Na2CO3·1.5H2O2 has been established: Experimental work was carried out under the following conditions: oxidant consumption 5% by weight of the raw material, leaching temperature 70°C, duration 30–60 minutes, stirring speed 200 rpm, and the ratio of liquid to solid S : L = 1 : 3. The degree of extraction of rhenium into the solution is 95–97%, and the content reaches 500–520 mg/L Re.
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