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首页> 外文会议>Sixth International Conference on Environmental Issues and Management of Waste in Energy and Mineral Production Swemp 2000, May 30-Jun 2, 2000, Calgary, Alberta >An integrated process for utilization of gypsum and pyrite wastes
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An integrated process for utilization of gypsum and pyrite wastes

机译：石膏和黄铁矿废物综合利用工艺

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摘要

Pre-combustion coal cleaning and post-combustion flue gas desulfurization (FGD) using lime or limestone are the primary methods employed to reduce sulfur dioxide (SO_2) emission from coal combustion. These processes generate voluminous pyrite and gypsum solid wastes that are usually landfilled, occupying thousands of acres of land and creating serious land and water pollution problems due to the release of acids and toxic substances. An integrated process has been developed for the combined utilization of gypsum and pyrite wastes by converting them into useful products including lime, sulfur, and direct reduced iron (DRI). The process includes four major steps. The first step is to concentrate pyrite from coal tailings using flotation or gravity separation. The second is the thermal decomposition of pyrite to pyrrhotite and sulfur. This is followed by the reduction of pyrrhotite with carbon in the presence of lime to produce iron and calcium sulfide. The fourth step involves the reaction of calcium sulfide with gypsum to regenerate lime. The chemical reactions involved in the process were studied using thermogravimetric analysis (TGA) and X-ray diffraction (XRD) techniques. Process variables studied included reaction temperature, time, reactant composition, and purity of reactants.
机译：使用石灰或石灰石的燃烧前煤炭清洁和燃烧后烟气脱硫（FGD）是减少煤炭燃烧中二氧化硫（SO_2）排放的主要方法。这些过程产生大量的黄铁矿和石膏固体废物，这些废物通常被掩埋，占据了数千英亩的土地，并且由于释放酸和有毒物质而造成严重的土地和水污染问题。通过将石膏和黄铁矿废料转化为有用的产品，包括石灰，硫和直接还原铁（DRI），已开发出一种综合方法，用于石膏和黄铁矿废料的综合利用。该过程包括四个主要步骤。第一步是使用浮选或重力分离从煤尾矿中浓缩黄铁矿。第二个是黄铁矿热分解为黄铁矿和硫。然后在石灰的存在下用碳还原黄铁矿，生成铁和硫化钙。第四步涉及硫化钙与石膏的反应，以再生石灰。使用热重分析（TGA）和X射线衍射（XRD）技术研究了该过程中涉及的化学反应。研究的过程变量包括反应温度，时间，反应物组成和反应物纯度。

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