有色重金属冶炼废渣硫化法回收过程特征研究

With the increase of nonferrous metal production, the discharge of heavy metal-containing nonferrous smelting slag increases year by year and the annual discharge amount exceeds ten million tons. These slags contain valuable metals,such as copper, lead, zinc and cadmium and the comprehensive utilization rate of these slags is less than 50%, which leads to severe environment pollution problem and resource waste. These slags have diverse sources, wide variety and difference in properties. It is difficult to form common industrialized technology to treat heavy metal-containing slag by the present leaching technology because of the disadvantages in aspect of recovery rate, techno-economics and secondary pollution. Based on formation principle of sulphide ore, a new idea of sulfidation followed by flotation treatment for recovery of metal sulfide concentrates from heavy metal-containing slag is proposed. The crucial problems of this technology lie in the cognition of deep sulfidation of heavy metal in slag and growth of sulfide crystal as well as realization of crystal growth control. Therefore, the present study mainly focuses on: 1) the bonding between heavy metal and sulfur as well as oxygen in solid phase; 2) the mechanism of heavy metal sulfidation reaction and sulfide growth as well as mineralization crystallization kinetics; 3) the interface interaction between sulfide and residue in slag; 4) the process feature of artificial sulfide ore recovery by sulfidation process. The purpose of this study is to enrich the theory system of sulfidation treatment of heavy metal-containing smelting slag and to form new prototypes of artificial sulfide ore recovery from heavy metal-containing smelting slag by sulfidation followed by flotation method.

有色重金属冶炼废渣随着有色金属产量的增加而逐年递增，年排放量已过千万吨，其中含有不少铜、铅、锌、镉等有价金属，综合利用率不到50%，造成环境污染和资源浪费严重。由于废渣来源广泛、种类繁多、性质差异很大，目前浸出技术在回收效率、技术经济性及二次污染等方面存在问题，难以形成产业化共性技术。基于硫化矿形成原理，提出废渣硫化-浮选法回收金属硫化物精矿的新思路，前期初步研究发现突破该技术的关键瓶颈在于认知废渣中重金属深度硫化转化、硫化物晶体生长规律并实现其有效调控。拟研究：1）固体物相中重金属与氧、硫的键合作用关系，2）重金属硫化反应机制、硫化物生长机制及矿化结晶动力学研究，3）废渣中硫化物与残渣的界面作用，4）硫化法回收人造硫化矿的工艺特征。通过本项目研究，旨在丰富重金属冶炼废渣硫化处理方法的理论体系，形成重金属冶炼废渣硫化法回收人造硫化矿的新技术过程特征原型。

有色重金属冶炼废渣含锌、铅、铜等有价金属，不适当的处理易造成严重的环境污染和资源浪费。由于废渣来源广泛、种类繁多、性质差异大，迫切需要研发资源化处理的共性关键技术。基于硫化矿形成原理，提出废渣硫化-浮选法回收金属硫化物精矿的新思路。项目研究结果表明无论在液相中抑或固相中，通过施加外场都能实现重金属的硫化转化。机械力化学硫化为自蔓延反应机制，其发生的必要条件为绝热反应温度>1300K；铅锌氢氧化物的水热硫化涉及重金属化合物的表面水解、水解产物的硫化转化、硫化物的聚集生长等过程，其硫化转化过程符合收缩核反应模型，硫化锌、硫化铅晶体生长为Ostwald成熟过程，晶体生长是小颗粒溶解、大颗粒长大的过程，因此晶体生长较为缓慢，晶粒细小；在一定条件下，废渣中的钙质可促进或不影响重金属化合物的硫化转化，但细小的硫化物极易黏附在生成的钙质矿物表面，造成钙锌分离难题；铁酸锌、硅酸锌等复杂物相可通过硫化焙烧转化为硫化物，其硫化转化为硫蒸气诱导的界面硫氧交换机制；以废水中和渣为代表，开展了其水热硫化回收硫化物研究，基于硫化物与钙脉石界面作用、硫化转化及硫化物回收工艺特征的研究，提出了硫酸钙水化转化促进硫化物分离与回收新工艺；以锌浸渣和异极矿为典型代表，研究了其硫化焙烧工艺特征，通过硫化产物预处理（如球磨等）、三氧化二铁的磁选回收、硫化物的浮选回收，可实现硫化物的富集和回收。项目研究结果极大地丰富了废渣硫化法回收重金属硫化物的基础理论体系，形成了有色重金属冶炼废渣水热硫化、机械硫化、硫化焙烧等技术原型。