One-stage leaching of osmium-rhenium containing lead cake using various oxidizing agents

Abstract

The subject of this study is osmium–rhenium-containing lead cake, which, along with dust, sulfuric acid wash, and sludge, is a byproduct of the pyrometallurgical processing of copper concentrate. The study examined the leaching of osmium–rhenium-containing lead cake using aqueous solutions of hydrogen peroxide, sulfuric and nitric acids, sodium hypochlorite-containing "Belizna," and potassium dichromate. The objective was to select an effective oxidizer for cake leaching. Rhenium is concentrated in an acidic solution as rhenium acid, and rhenium extraction from the solution has been well studied. Osmium is sublimated into the gas phase, then dissolved in an alkali solution containing sodium sulfide, forming commercial osmium sulfide. Novelty and Results: A leaching plant with continuous cake and solution feed and continuous leaching slurry discharge was created. The plant enables the production of rhenium acid solution for ammonium perrhenate and commercial osmium sulfide in a single stage. The sum of the plant’s parameters (operation continuity, specific productivity, and osmium and rhenium extraction degrees) exceeds those of existing methods. The dependence of osmium and rhenium extraction on the consumption of water, hydrogen peroxide, sulfuric and nitric acids, bleach preparation, potassium dichromate, and the leaching temperature and duration was studied. Close to optimal conditions for leaching 100 grams of cake are as follows: distilled water consumption of 60 milliliters; concentrated sulfuric acid consumption of 70 milliliters; bleach preparation consumption of 400 milliliters; liquid-to-solid ratio (L/S) of 5.3; a temperature of 60 ℃; and a specific productivity rate of 100 grams of cake per hour. In this case, the rhenium extraction percentage is 99.1%, and the osmium extraction percentage is 96.8%.