This article studies the oxidative firing process of lead sludge of copper production for the purpose of extracting rhenium. As an oxidizer, calcium hypochlorite is used, which is simultaneously an oxidizer of low-valent rhenium compounds and a binding reagent of rhenium oxides to calcium perrenate. Optimal conditions for the firing process are found: the firing temperature is 500-600°C, the firing duration is 30-60 minutes, and the oxidizer consumption is 20-40 % of the sludge mass. As a result of thermal studies and experimental work, it was established that the rhenium oxidation process begins at 180-260 °C after the decomposition of calcium hypochlorite and completely ends at 500-600 °C with the formation of calcium perrenate. During water leaching of the stub under the following conditions: T: W=1: 3, temperature of 70 °C, duration of 60 minutes, a solution containing 546 mg/l of rhenium was obtained. The degree of rhenium recovery in the solution was 93-94 %.
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Berdikulova et al. (2020) studied this question.