The flotation behavior and mechanism of sodium silicate on scheelite, fluorite and calcite were investigated by flotation tests, Zeta potential and XPS. The flotation experiment results show that the recovery of scheelite is higher than 80%, but the recoveries of fluorite and calcite are less than 10%and 26%, respectively, when Na2SiO3 dosage is greater than 2.5 g/L with collector 731 in the pH range of 9.7-10.3. The results of Zeta potential measurement show that Zeta potentials of scheelite shift negatively a little, however, the Zeta potentials of fluorite and calcite shift to more negative values in presence of sodium silicate, which indicates that sodium silicate is more easily adsorbed on the surface of fluorite and calcite. The results of XPS show that the Si 2p peaks are found on the surface of fluorite and calcite in presence of sodium silicate, and Si relative contents are 6.81%and 4.72%, respectively, but the Si relative concentration on the scheelite surface is only 0.35%, and Ca 2p 3/2 binding energy shifts of scheelite, fluorite and calcite are 0.26, 0.41 and 0.55 eV, respectively. According to the results of XPS, it can be concluded that sodium silicate is absorbed on the scheelite surface by physical adsorption, but it is absorbed on the fluorite and calcite surface by chemical adsorption. Therefore, sodium silicate can be used to separate scheelite from fluorite and calcite for selective depression fluorite and calcite.%以白钨矿、萤石和方解石为研究对象，通过单矿物浮选试验、动电位测试及XPS能谱分析，研究硅酸钠对含钙矿物浮选行为的影响及作用机理。浮选实验结果表明：在捕收剂731的作用下，pH值为9.7~10.3、硅酸钠浓度高于2.5 g/L时，白钨矿的回收率大于80%，而萤石和方解石的回收率分别低于10%和26%。Zeta电位检测结果表明：硅酸钠与矿物作用后，萤石和方解石的Zeta电位明显负移，而白钨矿的Zeta电位改变较小，说明硅酸钠更容易在萤石和方解石表面发生吸附。XPS能谱分析显示：硅酸钠与矿物作用后，在萤石和方解石表面出现了Si 2p特征峰，并且其相对含量分别为6.81%和4.72%，而Si在白钨矿表面的的相对浓度仅为0.35%；同时，白钨矿、萤石和方解石表面的Ca 2p 3/2结合能偏移量分别为0.26、0.41和0.55 eV，说明硅酸钠在白钨矿表面可能发生了物理吸附，而在萤石和方解石表面发生了强烈的化学吸附。因此，硅酸钠能选择性抑制萤石和方解石，有效地分离白钨矿与萤石和方解石。
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