电解铝炭渣高温焙烧熔融试验与物相分析研究

Research on High Temperature Melting Test and Phase Analysis of Electrolytic Aluminum Carbon Residue

炭渣是电解铝生产过程中产生的一种危险固体废弃物,含有较多电解质。某公司通过高温焙烧法处理炭渣并回收其中的电解质。本文研究了工业化高温焙烧处理电解铝炭渣的工艺条件,并采用X射线衍射分析法研究高温焙烧处理电解铝炭渣过程中各环节主要产物的物相组成。结果表明,采用高温焙烧法,炉内整体温度达到1200℃以上时,炭渣中的电解质完全熔融且流动性良好,无固化状态,炭渣中的电解质和碳质组分得到有效分离,高温焙烧后形成新的物相。其中电解质主要由Na3AlF_(6)、CaF_(2)、Al_(2)O_(3)、K_(2)NaAlF_(6)、LiNa_(2)AlF_(6)、Li_(3)N、LiF、Mg_(3)Al_(2)(SiO_(4))_(3)和NaAl_(11)O_(17)等组成;尾渣主要由Na_(3)AlF_(6)、CaF_(2)、Al_(2)O_(3)、K_(2)NaAlF_(6)、LiNa_(2)AlF_(6)、Li_(3)N和C等组成;收尘灰主要由Na_(5)Al_(3)F_(14)、Na_(3)AlF_(6)、LiNa_(2)AlF_(6)、AlF_(3)、NaAlF_(4)和KAl_(11)O_(17)等物相组成;炭渣中的钙盐始终以游离的CaF_(2)形式存在,一部分夹杂在回收的电解质中,另一部分存在于尾渣中。

Carbon slag is a kind of dangerous solid waste produced in the process of electrolytic aluminum production,which contains high content of electrolyte.A company treated carbon residue by high temperature roasting and recovered the electrolyte.In this paper,the process conditions of industrial high temperature roasting treatment of electrolytic aluminum carbon slag were studied,and the phase composition of the main products in the process of high temperature roasting treatment of electrolytic aluminum carbon slag was studied by X-ray diffraction analysis.The results show that when the overall temperature in the furnace reaches more than 1200℃,the electrolyte in the carbon slag is completely melted and has good fluidity and no curing state,the electrolyte and carbonaceous components in the carbon slag were effectively separated.After high temperature roasting,a new phase will be formed.The electrolyte is mainly composed of Na_(3)AlF_(6),CaF_(2),Al_(2)O_(3),K_(2)NaAlF_(6),K_(2)NaAlF_(6),Li_(3)N,LiF,Mg 3Al_(2)(SiO_(4))_(3) and NaAl_(11)O_(17).Tailings are mainly composed of Na_(3)AlF_(6),CaF_(2),Al_(2)O_(3),K_(2)NaAlF_(6),K_(2)NaAlF_(6),Li_(3)N and C;the dust is mainly composed of Na 5Al 3F 14,Na_(3)AlF_(6),K_(2)NaAlF_(6),AlF 3,NaAlF 4 and KAl_(11)O_(17).The calcium salts in the carbon residue in aluminum electrolysis always exit in the form of dissociative CaF_(2),part of which is included in the recovered electrolyte,and the other part exits in the tail residue.