Na_(2)O/SiO_(2)比对脱铜阳极泥卡尔多炉还原熔炼渣结构和性能的影响

Effect of Na2O/SiO2 ratio on structure and properties of reduction smelting slag for treating decoppering anode slime in Caldo furnace

卡尔多炉熔炼是目前火法处理脱铜阳极泥的重要工艺之一。针对国内某企业脱铜阳极泥卡尔多炉还原熔炼中渣熔化性能差、渣含贵金属损失大等问题,本工作利用热力学分析以及炉渣物性检测,结合XRD、拉曼光谱等结构表征手段,开展了脱铜阳极泥卡尔多炉还原熔炼渣钠硅比调控优化研究。根据PbO-Na_(2)O-SiO_(2)-BaO四元体系液相区图及性能测定结果,在不改变渣率及熔剂添加总量前提下,适当提高Na_(2)O/SiO_(2)比可有效降低炉渣熔点和黏度;随着还原熔炼渣Na_(2)O/SiO_(2)比由0.42提高至0.60,由于Na_(2)O的网络修饰剂作用,更多的桥氧转变为非桥氧,炉渣结构由Si_(2)O_(7)^(6-)硅酸盐二聚体结构为主,向SiO_(4)^(4-)硅酸盐四面体结构过渡,其中的Si_(2)O_(6)^(4-)链状结构与Si_(2)O_(5)^(2-)片状结构也相应减少,含铅硅酸盐聚合度降低,桥氧Qn分析结果与熔渣硅酸盐结构相契合。同时,提高钠硅比后,炉渣熔化温度从1178℃降至950℃,在1100℃冶炼温度下,还原熔炼渣黏度可降低45.2%,流动性得到显著改善,从宏观角度也验证了熔渣结构变化规律。结果表明,对脱铜阳极泥卡尔多炉还原熔炼,通过调控炉渣Na_(2)O/SiO_(2)比来降低桥氧数及复杂阴离子聚合度,从而改善炉渣物化性能的思路是可行的。

Caldor smelting is one of the most important methods for treating decoppering anode slime by pyrometallurgy.This research aims to solve the serious problems of poor melting performance and large precious metals loss of reduction smelting slag for treating decoppering anode slime emerged in a domestic enterprise.Therefore,the process optimization and regulation on the Na_(2)O/SiO_(2) ratio of reduction smelting slag in the Caldor furnace is carried out.The thermodynamic analysis by Factsage software is employed;simultaneously,the physicochemical properties of reduction smelting slag are measured combined with the XRD analysis and Raman spectroscopy characterization.According to the liquid phase diagram and the tested physicochemical properties of the PbO-Na_(2)O-SiO_(2)-BaO system,appropriately increasing Na_(2)O/SiO_(2) ratio can effectively decrease the melting temperature and viscosity of reduced smelting slag,without changing the slag rate and the adding amount of total flux.The structure of reduction smelting slag varies from dimer structure silicate of Si_(2)O_(7)^(6-)to tetrahedron structure silicate of SiO_(4)^(4-)when the Na_(2)O/SiO_(2) ratio of reduction smelting slag changes from 0.42 to 0.60.The increase of network modification of Na_(2)O results in more bridging oxygens converting to non-bridging oxygens in the reduction of smelting slag,and the ratio of Si_(2)O_(6)^(4-)chain structure silicate and Si_(2)O_(5)^(2-)sheet structure silicate decrease also,which lead to the lower of polymerization degree of slag.The analysis results show that the Q_(n) of bridged oxygen is consistent with the silicate structure of the smelting slag.Simultaneously,the hemispherical melting temperature of slag decreases from 1178℃to 950℃,and the viscosity can decrease about 45.2%at a smelting temperature of 1100℃when the Na_(2)O/SiO_(2) ratio of the reduction smelting slag varies from 0.42 to 0.60.As a result,the fluidity of reduction smelting slag is improved obviously,which can verify the above change trend of slag microstructure from the view of macroscopic properties.The results prove that it is feasible to regulate the Na_(2)O/SiO_(2) ratio of reduction smelting slag to lower the bridging oxygen number and polymerization degree of complex anionic,to improve the physicochemical properties.