Abstract Seawater is used in copper-molybdenum flotation plants when fresh water resources are limited. To minimize the negative effect of process seawater on molybdenite flotation, diluting process seawater with fresh water is a common practice. This study was designed to identify whether the dilution of process seawater in copper-molybdenum flotation plants benefits molybdenite flotation where NaHS is added to depress chalcopyrite. Seawater was prepared based on the concentrations of salts in the process seawater used in a copper-molybdenum flotation plant, and diluted with different proportions of de-ionized water. The concentrations of NaHS chosen to test in molybdenite flotation were determined by conducting chalcopyrite flotation to depress chalcopyrite. It was found that the concentration of NaHS which maximumly depressed chalcopyrite also depressed molybdenite to some extent in both seawater and diluted seawater. Water chemical equilibrium calculation, Cryo-XPS analysis and SEM measurement indicated that the depression mechanisms of NaHS on molybdenite were different in seawater and diluted seawater. Significant dilution of seawater weakened the buffer effect of seawater on pH and raised the pH in flotation significantly after the addition of NaHS so that Mg(OH)2 and CaCO3 precipitates formed to depress molybdenite. Insignificant dilution of seawater had little effect on flotation pH after the addition of NaHS, but the adsorption of HS− and the formation of SO42− on micro-edges of basal plane surfaces of molybdenite at a high NaHS concentration decreased the hydrophobicity of the basal plane surfaces, leading to reduced molybdenite flotation recovery.

中文翻译：

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硫氢化钠对海水和稀释海水中辉钼矿浮选的影响

摘要 当淡水资源有限时，海水被用于铜钼浮选厂。为了尽量减少工艺海水对辉钼矿浮选的负面影响，用淡水稀释工艺海水是一种常见的做法。本研究旨在确定铜钼浮选厂中工艺海水的稀释是否有利于辉钼矿浮选，其中添加 NaHS 以抑制黄铜矿。海水是根据铜钼浮选厂所用工艺海水中的盐分浓度制备的，并用不同比例的去离子水稀释。选择在辉钼矿浮选中测试的 NaHS 浓度是通过进行黄铜矿浮选以抑制黄铜矿来确定的。研究发现，在海水和稀释海水中，最大程度抑制黄铜矿的 NaHS 浓度也会在一定程度上抑制辉钼矿。水化学平衡计算、Cryo-XPS分析和SEM测量表明，NaHS对辉钼矿的抑制机制在海水和稀释海水中不同。海水的显着稀释削弱了海水对 pH 的缓冲作用，并在加入 NaHS 后显着提高了浮选的 pH，从而形成 Mg(OH)2 和 CaCO3 沉淀以抑制辉钼矿。加入NaHS后，海水稀释不显着，对浮选pH值影响不大，