酸性复杂体系中铬钒铁络合深度分离基础研究

Deep separation of chromium/vanadium/iron is the core of the comprehensive utilization of the resources containing chromium/vanadium/iron, such as Vanadium-chromium mud. Based on the original discovery of the difference of complex ability between chromium, vanadium and iron, the applicant first proposed the novel method of chromium/vanadium/iron deep complexation separation, which has been used successfully in the annual 18 000 tons industrial engineering of Vanadium-chromium mud treatment. Due to the wide range of raw material sources and variable composition, complex occurrence state of chromium/vanadium/iron, insufficient chemical stability of the existing complexing agent, and incomplete complexation dissociation, the process control is difficult and the recycling ratio of the complexing agent is not high enough. It is necessary to research the basic theories and control methods of complexation separation to optimize and expand the new process. Using cross-subject method of physical chemistry and complexation chemistry, the project mainly aims at the study of complexing property of the complexing agent to chromium/vanadium/iron, the structure-activity relationship of complex structure/characteristics and separation efficiency, the complexing dynamic directional regulation law and the dissociation law of complex group. Through these studies, the project will reveal the basis and the law of complexation separation, find out the boundary area of chromium/vanadium/iron deep separation, achieve the directional regulation of chromium/vanadium/iron, improve significantly the cycle efficiency of complexing agent. Furthermore, results of the project will provide the theoretical basis for the comprehensive utilization of the Vanadium-chromium mud and other similar resources.

铬钒铁深度分离是钒铬泥等含铬钒铁资源高值综合利用的核心，现有萃取、离子交换等分离方法难以有效实现铬钒铁的全利用。本项目基于铬钒铁在酸性体系下络合能力差异的原创性发现，在国内外首次提出铬钒铁络合深度分离的新方法，并完成了1.8万吨钒铬泥产业化的应用验证，但仍存在原料来源广泛与组成多变、铬钒铁赋存状态复杂、已有络合剂稳定性不够、解络合不彻底等问题，导致工艺调控难度大、络合剂循环利用率不高。新工艺优化与应用拓展亟待在络合分离原理与调控方法等理论基础方面取得突破。本项目将采用物理化学、配位化学等多学科交叉方法，系统开展铬钒铁络合性能、络合分离构效关系与络合剂改性、动力学定向调控规律、络合基团解离机理与方法等研究，揭示铬钒铁配位原理与分离规律，查明铬钒铁深度分离的界区范围，实现铬钒铁深度分离的定向调控，显著提高络合剂循环效率，为钒铬泥及其它类似原料的高值综合利用提供理论依据。

铬钒铁深度分离是钒铬泥等含铬钒铁资源高值综合利用的核心，现有分离方法难以有效实现铬钒铁的全利用。本项目基于铬钒铁在酸性体系下络合能力差异的原创性发现，在国内外首次提出铬钒铁络合深度分离的新方法，并完成了1.8万吨钒铬泥产业化的应用验证，但仍存在原料来源广泛与组成多变、铬钒铁赋存状态复杂、已有络合剂稳定性不够、解络合不彻底等问题，导致工艺调控难度大、络合剂循环利用率不高。新工艺优化与应用拓展亟待在络合分离原理与调控方法等理论基础方面取得突破。经过四年的研究，本项目系统开展了铬钒铁络合性能、络合分离构效关系、动力学定向调控规律、络合基团解离机理与方法等研究，揭示了铬钒铁配位原理与分离规律，查明了铬钒铁深度分离的界区范围，实现了铬钒铁深度分离的定向调控，显著提高了络合剂循环效率。研究结果表明，铬/钒/铁均可与络合剂进行络合反应，其络合的基本原理是络合基团中S原子提供的孤对电子与阳离子基团键合，铬(III)、钒(V)、铁(III)络合物的组成分别为Cr(CS2NR2)3、VO(CS2NR2)3、Fe(CS2NR2)3。铬(III)与络合剂的络合反应主要发生在pH 6~8区间，钒(V)与络合剂的络合反应主要发生在pH 1.0~5.5区间，铁(III)与络合剂的络合反应主要发生在pH 2~6区间。在络合工艺及动力学方面，发现pH值和温度对络合分离效果影响较大，在优化工艺条件下，沉钒率达97%，沉铁率达99%，铬损失率为3%。钒(V)、铁(III)络合物沉淀的成核及晶体长大均满足一级反应模型。在络合剂再生方面，获得了优化的络合剂再生工艺条件，在优化工艺条件下，络合剂再生率达95%以上。项目的顺利完成，为络合分离在多组分深度分离过程的应用奠定了基础。