Copper-molybdenum grades of important mining deposits have progressively decayed, which is associated with high levels of clay minerals which affect froth flotation. The depressing effect of clay minerals on copper sulfides was previously reported but there are no systematic studies on the effect on molybdenite flotation in seawater. The objective of this work was to study the effect of kaolinite on molybdenite flotation in seawater and to evaluate the use of sodium hexametaphosphate (SHMP) as dispersant. The results of this work show that kaolinite depresses molybdenite flotation which is more significant in seawater at pH > 9. All the experimental data validate the hypothesis that kaolinite covers molybdenite, reducing its flotation recovery. The depressing effect of kaolinite on molybdenite flotation in seawater is enhanced by the magnesium and calcium hydroxo complexes at pH > 9, which induce heterocoagulation between kaolinite and molybdenite, thus reducing recovery. The attachment of the positively charged hydroxo complexes of magnesium and calcium to the molybdenite and kaolinite surfaces is diminished by SHMP. This reagent increases the repulsive forces between molybdenite and precipitates and as a result, molybdenite becomes more hydrophobic and recovery increases.

中文翻译：

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高岭石对海水中辉钼矿浮选的抑制作用

重要矿床的铜钼品位已逐渐衰减，这与影响泡沫浮选的高含量粘土矿物有关。先前曾报道过粘土矿物对硫化铜的抑制作用，但尚无系统研究对海水中辉钼矿浮选的影响。这项工作的目的是研究高岭石对海水中辉钼矿浮选的影响，并评估六偏磷酸钠（SHMP）作为分散剂的用途。这项工作的结果表明，高岭石抑制了辉钼矿的浮选，这在pH值大于9的海水中更为明显。所有实验数据证实了高岭石覆盖辉钼矿的假设，从而降低了其浮选回收率。pH> 9的镁和钙羟基复合物会增强高岭石对海水中辉钼矿浮选的抑制作用，这会引起高岭石和辉钼矿之间的杂凝，从而降低回收率。SHMP可以减少镁和钙带正电的羟基复合物在辉钼矿和高岭石表面的附着。该试剂增加了辉钼矿与沉淀物之间的排斥力，结果，辉钼矿变得更加疏水，回收率提高了。