铜冶炼废渣脱硅工艺研究

Study on desiliconization process of copper smelting slag

以铜冶炼废渣[简称铜渣,主要成分为铁橄榄石(Fe_(2)SiO_(4))]为原料,采用钠化焙烧的方法脱除废渣中的硅,研究了以氢氧化钠为钠化剂对铜渣脱硅的影响。首先采用正交实验探究了焙烧温度、矿碱质量比、焙烧时间等因素对铜渣脱硅的影响顺序,在此基础上采用单因素实验研究了铜渣脱硅的适宜工艺条件。结果表明:铜渣脱硅影响因素由大到小的顺序为焙烧温度、矿碱质量比、焙烧时间。铜渣脱硅的适宜工艺条件:焙烧温度为650℃,矿碱质量比为1∶1.75(氢氧化钠理论量的4.17倍),焙烧时间为180 min。在此条件下铜渣钠化焙烧所得产物的水浸渣中二氧化硅的质量分数降至1.74%,脱硅率达到94.5%。焙烧产物及其水浸渣的X射线衍射分析表明,铜渣钠化焙烧脱硅的机理是铁橄榄石转化为铁酸钠和硅酸钠,铜渣中的铁最终以四氧化三铁的形式存在,硅以硅酸钠的形式脱除。

A sodium-roasting process was employed for removing silicon from a kind of copper smelting slag(here in after re-ferred to as copper slag)which mainly consists of ferric silicate.The effect of NaOH as sodiumizing agent on desiliconization process of copper slag was investigated.First,the orthogonal experiment method was used to explore the sequence of the influ-ence of the mass ratio of ore to alkali,roasting temperature and roasting time on desiliconization of copper slag.On this basis,the suitable process conditions for desiliconization of copper slag was investigated by the single factor variable method.The results indicated that the order of factors affecting silicon removal in the orthogonal experiment was roasting temperature>mass ratio of ore to alkali>roasting time,the optimal processing parameters were roasting temperature of 650℃,mass ratio of ore to alkali 1∶1.75(4.17 times of the oretical amount of NaOH),and roasting time of 180 min,the content of SiO2 in the water leaching product of copper slag by sodium-roasting was 1.74%,and the desiliconization rate was 94.5%under these conditions.X-ray diffraction analysis of calcined products and their water leaching residues showed that the desiliconization mechanism of copper slag by sodium-roasting process could be described that ferric silicate was transformed NaFeO_(2),NaFe_(2)O_(3) and Na_(2)O·nSiO_(2),the iron in the copper slag eventually existed in the form of Fe3O4,silicon was finally removed in the form of Na_(2)O·nSiO_(2).