Efficient removal of NaOl from mineral processing wastewater using Al-electrocoagulation

Gaogui Jing; Xiangsong Meng; Renji Zheng; Jing Chen; Wei Sun; Zhiyong Gao

doi:10.1016/j.jenvman.2023.117817

Efficient removal of NaOl from mineral processing wastewater using Al-electrocoagulation

J Environ Manage. 2023 Jul 15:338:117817. doi: 10.1016/j.jenvman.2023.117817. Epub 2023 Mar 30.

Authors

Gaogui Jing¹, Xiangsong Meng¹, Renji Zheng¹, Jing Chen¹, Wei Sun¹, Zhiyong Gao²

Affiliations

¹ School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Hunan International Joint Research Center for Efficient and Clean Utilization of Critical Metal Mineral Resources, Central South University, Changsha, 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha, 410083, China.
² School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China; Hunan International Joint Research Center for Efficient and Clean Utilization of Critical Metal Mineral Resources, Central South University, Changsha, 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha, 410083, China. Electronic address: zhiyong.gao@csu.edu.cn.

PMID: 37003222
DOI: 10.1016/j.jenvman.2023.117817

Abstract

Sodium oleate (NaOl) is widely used as collector for oxidised ore flotation, and residual NaOl in mineral processing wastewater is a serious threat to mine environment. In this work, the feasibility of electrocoagulation (EC) as an alternative for chemical oxygen demand (COD) removal from NaOl-containing wastewater was demonstrated. Major variables were evaluated to optimise EC, and related mechanisms were proposed to interpret the observations in EC experiments. The initial pH of the wastewater greatly affected the COD removal efficiency, which was likely to be related to the variation of predominant species. When the pH was below 8.93 (original pH), liquid HOl_(l) was the predominant specie, which could be rapidly removed by EC thought charge neutralisation and adsorption. At original pH or higher, Ol^- could react with dissolved Al³⁺ to form insoluble Al(Ol)₃, which was subsequently removed through charge neutralisation and adsorption. The presence of fine mineral particles could reduce repulsion force of the suspended solids and promote flocculation, whereas the presence of water glass had an opposite effect. These results demonstrated that EC can be employed as an effective process to purify NaOl-containing wastewater. This study will contribute to deepening our understanding of EC technology for NaOl removal and provide useful information to researchers in mineral processing industry.

Keywords: Electrocoagulation; Flotation reagents; Mineral processing wastewater; Sodium oleate.

MeSH terms

Electrocoagulation / methods
Electrodes
Hydrogen-Ion Concentration
Industrial Waste / analysis
Manufacturing Industry
Minerals
Waste Disposal, Fluid / methods
Wastewater*
Water Pollutants, Chemical*

Substances

Wastewater
Minerals
Industrial Waste
Water Pollutants, Chemical