Study on Optimization of Tungsten Ore Flotation Wastewater Treatment by Response Surface Method (RSM)

Liping Zhang,Ruihan Yao,Xuejing Song,Xiaofei Jiao,Shengnian Wu

doi:10.3390/min11020184

Abstract

A large amount of collectors, inhibitors and modifiers such as oleic acid, water glass and sodium carbonate are added to the flotation processing of tungsten ore, resulting in the difficulty of the suspended solids (SS) with the residual water glass settling down in the flotation wastewater. The removal efficiency of the suspended solids is low with commonly used reagents like polyaluminium chloride (PAC) and polyacrylamide (PAM). This paper innovatively applied calcium chloride (CaCl2) to treat flotation wastewater and optimized the dosage of CaCl2, PAM and the pH value. The experimental results showed that when the dosage of 595 mg/L CaCl2 was combined with 21 mg/L PAM at pH 12, the turbidity removal ratio could reach 99.98%, and the residual turbidity of the supernatant was 0.23 NTU. The effluent could fully meet the requirements for reuse in industrial, urban miscellaneous and scenic environment water consumption (turbidity < 5 NTU). The quadratic equation model fitted with Design-Expert 8.0.6 software was constructed as Y = 91.52 + 8.68A + 1.11B − 1.02C − 1.7AB + 0.86AC + 0.06BC − 1.56A2 + 2.09B2 − 1.89C2, which had a good accuracy of the predicted responses versus the experimental data.

Highlights

Due to the low utilization efficiency of reagents in the flotation process, large amounts of residual reagents remained in the flotation wastewater which were certainly toxic to the ecological environment
This paper studied a novel coagulate agent and used the Response Surface Method (RSM) to optimize the dosage to achieve the highest removal ratio of the SS in flotation wastewater, reducing the cost, improving the treatment efficiency of tungsten flotation wastewater and realizing the comprehensive utilization of water resources
According to the basic rules of RSM and the central composite design (CCD) method, the main factors affecting coagulation effect were chosen as the main independent variables in the RSM designing, and the supernatant turbidity removal ratio of flotation wastewater was selected as the response parameter

Summary

Introduction

According to the statistical data from the second national census of pollution sources, an average of 4.4 tons of flotation wastewater would be produced for 1 ton of raw tungsten ore in the flotation process. Due to the low utilization efficiency of reagents in the flotation process, large amounts of residual reagents remained in the flotation wastewater which were certainly toxic to the ecological environment. The main pollutants of flotation wastewater include suspended solids (SS), heavy metal ions and residual flotation reagents [2,3]. The discharge of flotation wastewater containing residual flotation reagents could result in serious water pollution and ecological environment damage. China’s ecological environment requirements, efficient treatment and reuse of mineral flotation wastewater is an urgent problem for the mining industry [1]. High-efficient removal of SS from the flotation wastewater is the key to improving the wastewater/reuse ratio. The SS in tungsten ore flotation wastewater are Academic Editor: Raj Mukhopadhyay

Methods

Results

Conclusion