As a renewable and carbon-neutral energy source, straw-type biochar shows promise in replacing fossil fuels for green metallurgy. In this paper, an ammonia leaching-biochar reduction roasting-magnetic separation process was developed to achieve whole-component resource recovery of the jarosite residue. The optimum conditions for ammonia leaching included an ammonia mass fraction of 4 %, leaching temperature of 70 °C, leaching time of 45 min, and liquid-solid ratio of 12, under which 96.84 % ammonia jarosite decomposition rate was obtained. The feasibility of the reaction between biochar pyrolysis gas and the iron-bearing components was investigated by thermodynamic and thermogravimetric analyses. The optimum conditions for biochar reduction included a roasting temperature of 1050 °C, corn stover biochar as a reducing agent, a biochar addition ratio of 1.25, and a roasting time of 60 min, under which 75.8 % of the iron was reduced to metallic iron. After magnetic separation, exhibited a remarkable metallic iron content of 93.54 % and an iron recovery rate of 83.20 %. Eventually, the particles were reduced to massive and spherical metallic iron particles. This study presents a novel reference for the implementation of biochar reduction of jarosite residue and demonstrates the potential of biomass for energy saving and emission reduction in resource utilization.

中文翻译：

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秸秆型生物炭还原剂还原烧制黄铁矿渣制备还原铁粉


作为一种可再生和碳中和的能源，秸秆型生物炭有望取代化石燃料用于绿色冶金。本文开发了一种氨浸出-生物炭还原焙烧-磁选工艺，以实现黄铁矿渣的全组分资源回收。氨浸出的最佳条件为氨质量分数 4 %、浸出温度 70 °C、浸出时间 45 min、液固比 12，获得 96.84 % 的黄铁矿氨分解率。通过热力学和热重分析研究了生物炭热解气体与含铁组分之间反应的可行性。生物炭还原的最佳条件包括烘烤温度 1050 °C，玉米秸秆生物炭作为还原剂，生物炭添加比例为 1.25，烘烤时间 60 min，其中 75.8% 的铁被还原为金属铁。磁选后，金属铁含量达到 93.54%，铁回收率达到 83.20%。最终，这些颗粒被还原为块状的球形金属铁颗粒。本研究为生物炭还原黄铁矿渣的实施提供了新的参考，并展示了生物质在资源利用节能减排方面的潜力。