铊对常规湿法炼锌系统的影响及开路方法

The influence of thallium on the conventional zinc hydrometallurgical system and its open paths

硫化锌精矿普遍伴生有一定量的铊,部分铅锌矿床含铊特别高。在常规湿法炼锌过程中原料中的铊会干扰锌冶炼操作和产品质量,表现为影响正常的检验分析、采用锌粉置换去除困难和影响锌粉净化除钴等。铊在湿法炼锌系统中的分布走向与原料含铊的高低、生产辅料的选择、操作条件等密切相关,可以在一定程度上人为采取措施控制铊的含量,减少对生产的影响。铊在常规湿法炼锌系统中的开路主要有三种方法,在浸出阶段采用氧化沉淀法除铊,净化阶段采用加铅锌粉置换法除铊,在回转窑阶段采用氯化亚铊挥发法把铊富集到高氟氯烟尘中开路。当原料含铊较低,浸出采用锰粉或氧气作为氧化剂时,铊主要在海绵镉或钴渣中开路(具体看所用锌粉是否加铅);当原料含铊比较高,浸出采用双氧水、高锰酸钾或者臭氧作为氧化剂时,铊主要在高氟氯烟尘中开路。

Zinc sulfide concentrate is usually associated with a certain amount of thallium,and in some zinc-lead deposits,the content of Tl can be particularly high.In a conventional hydrometallurgical zinc refining process,the Tl contained in the raw material can affect the operation and product quality.The symptoms include problematic assaying,difficulty in zinc dust precipitation,and cobalt removal.As the stream and distribution of Tl across a hydrometallurgical zinc refining process is closely related to its content in the ore,the selection of auxiliary materials and operating conditions,by manipulating these factors the adverse effect of Tl can be controlled.There are three paths of bleeding Tl from a conventional hydrometallurgical zinc refining process:oxidizing precipitation during leaching,zinc dust precipitation during purification,and concentrating Tl into high F-Cl offgas dust by volatilizing thallium chloride in the rotary kiln.When the Tl grade in the feed is low and when Mg powder or oxygen is used as the oxidant for leaching,Tl can be removed mainly through sponge cadmium or cobalt residue(dependent on the lead content in the zinc dust);when the feed Tl is high and when hydrogen peroxide,or potassium permanganate or ozone is used as oxidant,Tl can be removed through high F-Cl offgas dust.