熔盐辅助下的选择性氢氯化处理铜钴合金基础研究

As the main Co-bearing resource/byproduct that is imported from overseas, Cu-Co alloy is conventionally treated by acid-leaching-based processes that are limited by their relatively low leaching efficiency, lengthiness of the process, and the generation of large quantities of wastes. Efforts need to be made in order to allow the metal extraction and separation from the Cu-Co alloy in an efficient and clean manner. After drawing inspiration from the high temperature corrosion mechanism of metals/alloys, a clean process was proposed to treat the Cu-Co alloys by hydrochlorination enhanced with molten salt media. Separation of the metallic components from the Cu-Co alloys can be achieved owing to the high selectivity of the hydrochlorination reactions toward specific elemental components. Coupling with selective reduction of metal chlorides with hydrogen (i.e., de-chlorination of chlorides), it could achieve near-complete reuse and recycling of the gaseous HCl within the process, representing an efficient and clean method for the extraction of valuable metals from Cu-Co alloys. In this study, selective hydrochlorination of Cu-Co alloys, and the mechanism for the enhancement with the presence of molten salt will be investigated. The controlling mechanism and the kinetics characteristics of the selective hydrogen reduction of the multi-metal chlorides will also be studied. The processing parameters will be optimized. These will provide theoretical and fundamental basis for the selective hydrochlorination process enhanced with molten salt media for the treatment of Cu-Co alloys. New technical framework will be established, which will provide guidance for the Cu-Co alloy treatment practice in a cleaner and more efficient manner.

铜钴合金作为我国进口的主要钴原料，其传统酸性浸出工艺存在浸出效率低、流程长、废渣废水产生量大等局限性，限制了铜钴合金中有价组分的高效清洁提取。借鉴金属腐蚀机理，本项目创新地提出一种熔盐辅助下氢氯化处理铜钴合金的清洁、短流程处理方法。本方法拟利用氢氯化反应对铜钴合金中特定元素具有高度选择性而达到提取分离目的。结合氢气梯级还原多金属氯化物的“脱氯”过程，实现铜钴合金处理过程中氯化氢气体的循环利用及有价金属的高效清洁分离。本项目主要研究铜钴合金选择性氢氯化行为规律及熔盐强化的协同处理机制；研究多金属氯化物梯级氢气还原调控机制与动力学特征，确定优化工艺条件，建立熔盐强化-选择性氢氯化处理铜钴合金的理论基础，形成新技术原型，为铜钴合金的清洁高效处理提供理论指导。

本项目针对传统湿法处理铜钴合金效率低、流程长、能耗高等问题，提出一种熔盐辅助下的选择性氢氯化处理铜钴合金的新思路。通过系统的理论与实验研究，阐明了选择性氢氯化机理与熔盐辅助机制，明晰了多金属氯化物梯级氢气还原“脱氯”机制，为铜钴合金清洁高效处理提供了理论依据。.a.氢氯化：本项目提出铜钴合金的氢氯化焙烧-水浸的方法。考察了焙烧温度、焙烧时间等因素对分离效率的影响。氢氯化过程中，铜钴合金的致密结构被破坏，合金中的Co、Fe、Cu和Si转化为CoCl2、FeCl2、Cu和SiCl4。浸出时，Co和Fe进入液相，Cu留在渣中。在优化条件下，焙烧产物中Co、Fe、Cu的水浸效率分别为87.76%、93.25%和4.85%。.b.熔盐辅助：氢氯化反应过程中产生的氯盐保护层阻碍了氢氯化反应的进一步发生。本项目对熔盐辅助强化氢氯化的效果进行量化。结果表明：存在一个氯化氢与铜钴合金质量比（m(HCl)/mcopper-cobalt alloy）窗口，可使Si，Fe，Co，Cu四种金属实现高效选择性分离，并分别进入气相、熔盐相和合金相。.c.氢还原：实验探究了还原温度、还原时间等因素对铁钴分离率及产物微观形貌的影响，结果表明：在相同温度下缩短还原时间、相同时间下降低还原温度，均有利于氯盐混合物中铁钴的分离。氢气浓度越高，还原速率越快，总流速对还原速率影响不显著。最优条件下，合金相中的钴铁比为10.71，实现了钴、铁的有效分离。

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