It is estimated that approximately 1.2 tons of bauxite residue (BR) was generated per tonne of alumina produced, and less than 3 % of the annual generation is used. The high alkalinity makes it technically and economically challenging to reuse this material. The study investigated the alkaline neutralization of BR through synergistic pyrolysis with products from Refuse-Derived Fuel (RDF). Two types of RDF, from different producers, were used and BR (pH 12) was generated by an alumina refinery in Brazil. Different mass proportions (0, 10, 20 and 50 % w/w) of RDF were used for synergetic pyrolysis. A pyrolysis was performed at 200, 400, 600, and 800 ºC using muffle furnace and crucibles with a residence time of 20 min. The pH of the mixtures after pyrolysis, decreased as the proportion of RDF increased. The results showed that the neutralization of the BR occurred at temperatures of 200 and 400 ºC. However, as the temperature increases (600 and 800 ºC) the pH neutralization is reduced. The best performance was observed for 50 % RDF at 400 ºC with a final pH 8 (33 % reduction). Synergistic pyrolysis of BR and RDF was effective in promoting reduction in the alkaline content of the bauxite residue.

中文翻译：

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垃圾衍生燃料 (RDF) 的协同热解可以中和铝土矿残渣


据估计，每生产一吨氧化铝，就会产生约 1.2 吨铝土矿渣 (BR)，但仅使用了不到年产量的 3%。高碱度使得这种材料的再利用在技术和经济上都具有挑战性。该研究通过与垃圾衍生燃料 (RDF) 产物的协同热解研究了 BR 的碱中和作用。使用来自不同生产商的两种类型的 RDF，BR（pH 12）由巴西的一家氧化铝精炼厂生产。使用不同质量比例（0、10、20 和 50% w/w）的 RDF 进行协同热解。使用马弗炉和坩埚在 200、400、600 和 800 ℃ 下进行热解，停留时间为 20 分钟。热解后混合物的pH值随着RDF比例的增加而降低。结果表明，BR 的中和发生在 200 和 400 ℃ 的温度下。然而，随着温度升高（600 和 800 ℃），pH 中和作用会减弱。在 400 ℃、最终 pH 值为 8 时观察到 50% RDF 的最佳性能（减少 33%）。 BR和RDF的协同热解可有效促进铝土矿渣碱含量的降低。