A new thiosalt depuration bioprocess for water- recycling in metallic sulphide mineral processing. (November 2019)

• Record Type: Journal Article
• Authors: Mazuelos, Alfonso; Iglesias-González, Nieves; Montes-Rosúa, Cristina; Lorenzo-Tallafigo, Juan; Romero, Rafael; Carranza, Francisco
• Is Part Of: Minerals engineering. Volume 143(2019)
• Publication Date: 2019-11
• Subjects: Thiosalts -- Thiosulphate -- Sulphite -- Acidithiobacillus -- Bio-oxidation -- Flotation; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2019.106031
• Languages: English
• ISSNs: 0892-6875

Abstract

Graphical abstract: Highlights: A novel process is proposed to remove thiosalts from mineral processing waters. Sulphite and thiosulphate inhibit biooxidation at pH below 2. Acidification up to pH 1.5 before biooxidation allows thiosalts depuration. Abstract: Economic and environmental imperatives force the metallic sulphide processing industry to re-use liquors that normally contain thiosalts; this processing entails difficulties in operation control and losses in metal-extraction performance. Bio-oxidation presents a promising option for thiosalt removal. Hitherto, this method has been tested to treat synthetic liquors containing only one thiosalt, either tetrathionate or thiosulphate, usually at low concentration (<1 g/L). In this article, bio-oxidation is studied of synthetic and real liquors containing mixtures of these thiosalts at concentrations close to 4.5 g/L. Coexistence of thiosulphate and tetrathionate in an acidic medium leads to strong and irreversible inhibition phenomena (performance losses close to 80%). In order to solve this problem, a previous treatment is proposed consisting of the 8-hour aeration of inlet solution after adding up to 20 mg/L and pH 1.5 of Cu 2+ and sulphuric acid, respectively, resulting in the complete removal of thiosulphate and sulphite. Pre-treated real liquors were fed into a 1 L discontinuous stirred tank bioreactor and a 1 L continuous flooded packed-bed bioreactor, which were successfully started up and operated, thereby obtaining bio-oxidation rates close to the highest rates found in the literature with synthetic liquors.