Abstract

The state of the art for the recovery of metals from steel industry by-products using hydrometallurgical processes is reviewed. The steel by-products are different slags, dusts, and sludges from a blast furnace (BF), basic oxygen furnace (BOF), electric arc furnace (EAF), and sinter plant, as well as oily mill scale and pickling sludge. The review highlights that dusts and sludges are harder to valorize than slags, while the internal recycling of dusts and sludges in steelmaking is inhibited by their high zinc content. Although the objectives of treating BF sludges, BOF sludges, and EAF dust are similar, i.e., the removal of zinc and the generation of an Fe-rich residue to be returned to the steel plant, these three classes of by-products have specific mineralogical compositions and zinc contents. Because wide variations in the mineralogical composition and zinc content occur, it is impossible to develop a one-size-fits-all flow sheet with a fixed set of process conditions. The reason for the interest in EAF dust is its high zinc content, by far the highest of all steel by-products. However, EAF dust is usually studied from the perspective of the zinc industry. There are not only different concentrations of zinc, but also variations in the all-important ZnO/ZnFe₂O₄ (zincite-to-franklinite) ratio. In many chemical processes, only the ZnO dissolves, while the ZnFe₂O₄ is too refractory and reports to the residue. It only dissolves in concentrated acids, or if the dust is pre-treated, e.g., with a reductive roasting step. The dissolution of ZnFe₂O₄ in acidic solutions also brings significant amounts of iron in solution. Finally, due to its high potassium chloride content, sinter-plant dust could be a source of potassium for the fertilizer industry.

Graphical Abstract

中文翻译：

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从钢铁工业副产品中回收金属的湿法冶金工艺：关键评论

摘要

综述了使用湿法冶金法从钢铁工业副产品中回收金属的最新技术。钢铁副产品是来自高炉（BF），碱性氧气炉（BOF），电弧炉（EAF）和烧结厂以及油厂规模和酸洗污泥的不同炉渣，粉尘和污泥。该评论强调，粉尘和污泥比矿渣更难获得有效的价值，而炼钢中粉尘和污泥的内部回收却受其高锌含量的限制。尽管处理高炉污泥，转炉污泥和电弧炉粉尘的目标是相似的，即去除锌和生成富铁残渣以返回钢厂，但这三类副产物具有特定的矿物学组成和锌含量。由于矿物成分和锌含量会发生很大变化，因此不可能开发出一套固定条件的，适用于所有工艺条件的“一刀切”流程。对电弧炉粉尘感兴趣的原因是其高锌含量，是所有钢副产品中最高的。但是，电弧炉粉尘通常是从锌工业的角度进行研究的。不仅锌的浓度不同，而且最重要的ZnO / ZnFe也存在差异₂ O ₄（锌铁矿对富兰克石的比率）。在许多化学过程中，只有ZnO溶解，而ZnFe ₂ O ₄则是难熔的，会向残留物报告。它仅溶于浓酸中，或者如果粉尘经过预处理（例如，采用还原焙烧步骤），则会溶解。ZnFe ₂ O ₄在酸性溶液中的溶解还会在溶液中引入大量的铁。最后，由于其较高的氯化钾含量，烧结厂粉尘可能成为化肥行业钾的来源。

图形概要