Under the oxidative roasting process, pyrite, as a major mineral in sulfidic mine tailings, can transform to iron oxides. Generated iron oxides, if exhibiting enough magnetic properties, can be recovered via magnetic separation resulting in partial mine tailings valorization. However, due to the presence of various minerals and sintering possibility, it is advantageous to remove impurities and increase the pyrite content of mine tailings prior to the roasting procedure. In this case, hydrofluoric acid that has no influence on pyrite can be used to leach most inorganic minerals, including aluminosilicates. Therefore, this study investigated and compared the influence of the roasting process with and without hydrofluoric acid leaching pretreatment on mineralogical phase transformation of pyrite and magnetic properties of thermally generated minerals. Several tests and analyses were performed to study mineralogical phase transformation, morphology, elemental composition, surface characterization, and magnetic properties. Results of this study indicated that without acid leaching pretreatment, pyrite was mainly transformed to hematite. However, via acid leaching, fluorine, as a more electronegative element over oxygen, entered the compound and neglected the role of oxygen in thermal oxidation, instead reducing sulfur content of pyrite to only form pyrrhotite.

中文翻译：

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氢氟酸浸出和焙烧对硫矿尾矿中硫铁矿矿物相变的影响

在氧化焙烧过程中，硫铁矿作为硫化矿尾矿中的主要矿物，可以转化为氧化铁。如果产生足够的磁性，可以通过磁选法回收产生的氧化铁，从而导致部分矿山尾矿的增值。然而，由于各种矿物的存在和烧结的可能性，在焙烧步骤之前除去杂质并增加矿渣的黄铁矿含量是有利的。在这种情况下，对黄铁矿没有影响的氢氟酸可用于浸出大多数无机矿物，包括铝硅酸盐。因此，本研究调查并比较了焙烧过程与不进行氢氟酸浸出预处理对黄铁矿的矿物相变和热产生矿物的磁性的影响。进行了一些测试和分析，以研究矿物相变，形态，元素组成，表面表征和磁性能。研究结果表明，未经酸浸预处理，黄铁矿主要转化为赤铁矿。但是，通过酸浸，氟作为氧的负电性更高的元素进入了化合物，并忽略了氧在热氧化中的作用，而是将黄铁矿中的硫含量降低，仅形成黄铁矿。