硫化锑精矿还原固硫焙烧直接产出金属锑研究

Direct production of antimony by reduction and sulfur-fixing roasting from stibinite concentrate

针对现行鼓风炉挥发（熔炼）-反射炉还原炼锑工艺存在的流程长、能耗高、低浓度SO2烟气污染等问题,提出了一种基于选冶联合过程的锑提取新工艺——硫化锑精矿还原固硫焙烧直产金属锑.分别以ZnO和碳粉作为固硫剂和还原剂实现对硫化锑矿的固硫还原转化,直接产出金属锑,同时生成硫化锌,再分别分离得到金属锑粉和硫化锌精矿.本文采用控制变量法,分别考察了焙烧温度、碳粉粒度、ZnO配入量、焙烧时间对锑生成率和ZnO固硫率的影响.得到最佳条件如下：焙烧温度800℃、碳粉粒度100~150目、ZnO量为固硫所需理论量、焙烧时间2 h,在此条件下,锑生成率为90. 4%,ZnO固硫率为94. 8%,其中温度和ZnO加入量对焙烧效果有较大影响;同时对反应产物的分析和过程热力学计算表明焙烧过程分两步进行,即首先发生Sb2S3与ZnO的交互固硫反应生成Sb_2O_3,其后在高于700℃温度下Sb_2O_3被大量还原成金属锑.在不同品位的锑精矿综合实验中,均获得了90%左右的锑生成率和88%的固硫率,验证了工艺的可行性.新工艺低温低碳、清洁环保,易于开展工业化生产.

Blast furnace volatilizing（ smelting） and reverberatory furnace process is the main reduction method in the current antimony smelting process,and it is associated with problems such as a long production flow,high energy consumption,and SO_2 flue gas pollution. Thus,in this paper,a new process,based on the combination of beneficiation and metallurgy,was proposed for the direct extraction of antimony from stibnite concentrate. Using ZnO and carbon as a sulfur-fixing agent and reductant,respectively,antimony sulfide was transformed to Sb and Zn S metals,and then the mixture was separated by a mineral separation method. The effects of calcination temperature,carbon particle size,ZnO dosage,and calcination time on the conversion rate of Sb and sulfur-fixing rate of ZnO were investigated in detail by controlled variables method. The optimal conditions are as follows： calcination temperature 800 ℃,carbon particle size 100 ~ 150 mesh,ZnO dosage 1. 0 times the theoretical amount,and roasting time 2 h. Under these conditions,the antimony generation rate and sulfur-fixing rate of ZnO are 90. 4% and 94. 8%,respectively. The antimony generation rate and sulfur-fixing rate of ZnO can be improved by increasing the reaction temperature and ZnO dosage. Meanwhile,the phase analysis results of the reaction products and thermodynamic calculations of reactions indicate that the reaction paths of Sb2 S3 and ZnO comprise two steps：First,Sb2 S3 reacts with ZnO to generate Sb_2O_3,and then after 700 ℃,it is reduced to a large amount of antimony. In the comprehen-sive experiments of different grades of antimony,about 90% of antimony generation rate and 88% of sulfur-fixing rate are realized,which demonstrates the feasibility of the new process. The new process is characterized by low temperature and low carbon usage,and it is clean and environment friendly; thus,it is suitable for industrial production.