Use of Sodium Hexametaphosphate and Citric Acid Mixture as Depressant in the Flotation Separation of Scheelite from Calcite

Zhu Zhu,Dong Dong,Wei Wei,Qin Qin,Jiao Jiao

doi:10.3390/min9090560

Abstract

The floatability of scheelite and calcite in the presence of single depressant (SHMP or H3Cit) and mixed depressant (SHMP/H3Cit) was studied by microflotation experiments and artificial mixed mineral experiments. Solution chemical calculation, zeta potential tests, thermodynamic analysis and XPS analysis were used to explain the relevant depressive mechanism. Mixed depressant (SHMP/H3Cit) exhibited excellent selective depressive effect on calcite. The optimal molar ratio of SHMP to H3Cit was 1:4. The depressant SHMP and H3Cit can be chemically bonded with Ca2+ to form CaHPO4 and Ca3(Cit)2 at pH 8. The CaHPO4 was more easily formed than Ca3(Cit)2 on the mineral surface, which indicated that the depressive effect of SHMP was stronger than H3Cit. The SHMP and H3Cit of the mixed depressant were co-adsorbed on the calcite surface, while the H3Cit of the mixed depressant was weakly adsorbed on the scheelite surface. The mixed depressant can significantly improve the separation efficiency of scheelite from calcite.

Highlights

Scheelite and wolframite are the two most important tungsten resources in nature
When the concentration of Sodium hexametaphosphate (SHMP) reached 2 × 10−3 mol/L, SHMP greatly depressed the flotation of calcite, it greatly depressed the floatability of scheelite, and the recovery was greatly reduced from
Artificial mixed mineral experiment indicated that the mixed depressant can significantly improve the separation efficiency of scheelite and calcite

Summary

Introduction

Scheelite and wolframite are the two most important tungsten resources in nature. Since the wolframite ((Fe, Mn)WO4 ) is more enriched by gravity methods and is easier to exploit and utilize, the wolframite resources have been exhausted [1,2,3]. The exploitation and high standards utilization of scheelite (CaWO4 ) are receiving more and more attention [4,5]. The extraction of scheelite from corresponding gangue minerals has been a problem due to its unique embedding characteristics and symbiotic relationship [6]. Foam flotation is an efficient method to recover minerals with low grade and fine grain size [7,8,9]. The chemical properties of the mineral surface (such as wettability and surface electrical properties) are changed by adding flotation reagents [10,11,12,13]

Methods

Results

Conclusion