In the reverse anionic flotation of phosphate ores using phosphoric acid, it is often suggested that a selective surface passivation of the phosphate minerals by calcium phosphate occurs. Several calcium phosphate species have been proposed in the literature for this surface passivation. In this study, in-situ Raman spectroscopy was used to monitor as a function of time the interaction of phosphoric acid with calcite and fluorapatite at a fixed pH of 4.5 or at fixed phosphoric acid concentrations in order to identify what species have formed in conditions similar to those used in flotation. X-ray photoelectron spectroscopy was also used to confirm and identify more clearly the species formed at the minerals surface. Although a calcium phosphate (1:1) species was observed on both minerals, its presence on calcite was highly dependent on phosphoric acid concentration and pH as the latter controls both calcium dissolution and calcium phosphate precipitation. The results of mineral flotation have confirmed the importance of phosphate concentration in solution, originating from phosphoric acid addition and/or mineral dissolution, in the formation/precipitation of calcium phosphate which can turn on or off the flotation of calcite or fluorapatite, or both.

在使用磷酸的磷酸矿石的反向阴离子浮选中，通常建议发生磷酸钙对磷酸盐矿物的选择性表面钝化。在文献中已经提出了几种磷酸钙来进行这种表面钝化。在这项研究中，使用原位拉曼光谱法来监测在固定pH值为4.5或在固定磷酸浓度下磷酸与方解石和氟磷灰石的相互作用，以鉴定在相似条件下形成了哪些物种浮选中使用的那些。X射线光电子能谱还用于确认和更清楚地识别在矿物表面形成的物质。尽管在两种矿物上均观察到磷酸钙（1：1）物种，它在方解石中的存在高度依赖于磷酸浓度和pH，因为后者控制着钙的溶解和磷酸钙的沉淀。矿物浮选的结果已经证实，溶液中磷酸盐浓度的重要性源自磷酸的添加和/或矿物溶解，在磷酸钙的形成/沉淀中，磷酸钙可以开启或关闭方解石或氟磷灰石的浮选，或两者兼而有之。