ABSTRACT

Inorganic acids (sulfuric acid (H₂SO₄) or phosphoric acid (H₃PO₄)) are generally employed as depressants in the reverse flotation of collophanite to separate apatite from dolomite. In this study, the flotation performance of a collophanite ore was studied, employing H₂SO₄, H₃PO₄, and a sulfur–phosphorus mixed acid as the depressants. The flotation tests revealed that the sulfur–phosphorus mixed acid could depress the apatite effectively. A high-quality concentrate with P₂O₅ content of 28.4 wt% and MgO content of 0.95 wt% was obtained, the corresponding P₂O₅ recovery of which was 85.0%. Furthermore, the separation mechanism of apatite and dolomite was clarified by zeta potential measurements, solution chemistry analysis and X-ray photoelectron spectroscopy (XPS). Within the pH range of 4.0–7.0, the zeta potentials of apatite were negative while those of dolomite were positive in the presence of all the three acid-depressants. The addition of sodium oleate made the potentials of both minerals to a more negative position. However, the potential shifts of dolomite were much more significantly negative than apatite when H₂SO₄ or H₃PO₄ was used. It indicated a greater absorption of sodium oleate on the surface of dolomite than apatite, which contributed to a more widen hydrophobicity gap between the surfaces of apatite and dolomite. SO₄ ²⁻ and H₂PO₄ ⁻, not H⁺ or Cl⁻, were founded to be the pivotal ions for depressing. XPS analyses illustrated that the simultaneous additions of H₂SO₄ and H₃PO₄ as depressants were beneficial to the formation of CaHPO₄ and CaSO₄ on the surface of the apatite, which were harmful for the adsorption of sodium oleate, making the depressing effect more remarkable and result in a better separation of dolomite from apatite. It performed much more efficiently in collophane ore flotation when H₃PO₄ and H₂SO₄ were used corporately as a combined depressant than when they were used separately.

摘要

无机酸（硫酸（H ₂ SO ₄）或磷酸（H ₃ PO ₄））通常在白云石反浮选中用作抑制剂，以将磷灰石与白云石分离。在这项研究中，以H ₂ SO ₄，H ₃ PO ₄和硫磷混合酸为抑制剂，研究了白云石矿石的浮选性能。浮选试验表明，硫-磷混合酸可以有效地抑制磷灰石。获得具有28.4 wt％的P ₂ O ₅含量和0.95 wt％的MgO含量的高质量精矿，相应的P ₂O _5的回收率为85.0％。此外，通过ζ电势测量，溶液化学分析和X射线光电子能谱（XPS）阐明了磷灰石和白云石的分离机理。在4.0-7.0的pH范围内，在所有三种降酸剂的存在下，磷灰石的ζ电位均为负，而白云石的ζ电位为正。油酸钠的添加使两种矿物质的电位都处于负值。但是，当H ₂ SO ₄或H ₃ PO ₄时，白云石的电位位移远比磷灰石的负位移大得多。被使用了。这表明白云石表面的油酸钠比磷灰石吸收更大，这导致磷灰石和白云石表面之间的疏水间隙更大。SO ₄ ^2-和H ₂ PO ₄ ^- ，不是H ⁺或Cl ^- ，都成立是用于按压枢转离子。XPS分析表明，同时加入H ₂ SO ₄和H ₃ PO ₄作为抑制剂有助于形成CaHPO ₄和CaSO _4。磷灰石表面的磷灰石对油酸钠的吸附有害，使降压效果更加显着，白云石与磷灰石的分离效果更好。当将H ₃ PO ₄和H ₂ SO ₄一起用作组合抑制剂时，与单独使用相比，在浮选矿石中它的效率更高。