Enhanced Recovery Of Microfine Grained Scheelite By Lead And Aluminum Ions In A Fatty Acid-water Glass Reagent System

Flotation is an essential operation of recovering microfine grained scheelite from tungsten tailings.The conventional flotation method requires additional flotation collectors and depressants,and the residual agents such as fatty acid ZL（long hydrocarbon chain saponified carboxylic acid）and water glass（SS）in the scheelite tailings are not utilized.In this paper,we propose to add Pb/Al ions to the fatty acid ZL-water glass system to enhance the recovery of microfine grained scheelite and achieve efficient separation of microfine grained scheelite from the tailings.The results of single mineral and binary mixed mineral flotation tests show that microfine grained scheelite and calcite could not be separated in the fatty acid ZL-water glass system.The addition of Pb/Al ions has a strong depressive effect on the fine-grained calcite and improves the grade of the scheelite concentrate.The experimental results of recovering fine-grained scheelite from tungsten tailings（WO₃ 0.2%）show that adding 100 g/t lead nitrate and 40 g/t aluminum sulfate,the closed-circuit test can obtain scheelite concentrate with a WO₃ recovery of 61.76%and a grade of 1.17%.Zeta potential measurements,Fourier transform infrared spectroscopy,scanning electron microscopy with energy dispersive spectrometer and UV-vis spectrophotometer determination showed that strong chemisorption of fatty acid ZL occurred on the surface of both microfine grained scheelite and calcite,but no significant water glass adsorption was observed,resulting in the inability to selectively separate the two minerals.Pb/Al ions combine with silicon-oxygen tetrahedral groups in water glass in two-coordinate(Pb²⁺/Pb（OH）₂)and four-coordinate（Al（OH）₄^-）forms,respectively,to increase the degree of polymerization of water glass.The water glass adsorbed on the surface of the fine-grained calcite has a higher degree of polymerization,and the Q³and Q⁴ structures account for 74.24%and 25.76%,respectively.The structure is denser and the coverage is wider,which resulted in a stronger depressive ability and exerted a desorption effect on the fatty acid ZL already adsorbed on the calcite surface.The degree of polymerization of water glass adsorbed on the surface of microfine grained scheelite is low,and the Q² structure with low polymerization degree accounts for 39.52%with a fragmented distribution.In addition,Pb/Al ions adsorbed on the surface of microfine grained scheelite increased the adsorption sites of fatty acid ZL.