钛精矿连续酸解过程中物相变化特征探讨

如何进一步提升酸解回收率一直是硫酸法钛白研究的重点,而酸解回收率的高低与含钛物相的变化密切相关。以连续酸解工艺为例,为考察反应过程中含钛物相的变化特征,综合应用矿物分析仪、X射线衍射(XRD)、扫描电镜(SEM)、化学分析等技术手段对反应过程中钛精矿中主要物相的含量、形貌变化特征以及Ti、Si元素的含量、赋存变化特征进行了研究。结果表明,钛精矿主要由钛铁矿和硅酸盐矿物组成;酸解过程中,酸沿钛铁矿颗粒边缘或裂隙向内部渗透将其逐步分解,与此同时,钛铁矿含量由钛精矿中的86.13%(质量分数,下同)逐渐降低至残渣4#中的14.38%;在此过程中,石英、透辉石得到富集,其含量分别由钛精矿中的0.06%及1.58%逐渐增加至残渣4#中的50.85%和14.92%;反应过程中Ti元素含量由钛精矿中的26.74%逐渐减小至残渣4#中的6.46%,Si元素含量则由2.19%逐渐增加至29.14%;反应期间,钛铁矿中Ti元素赋存比由钛精矿中的96.08%逐步降低至残渣4#中的64.88%,且Ti元素主要由钛铁矿向TiOSO₄迁移,部分Ti元素被石英及其混合物包裹而滞留其中,导致Ti元素的损失;Si元素主要赋存物相由钛精矿中的钛铁矿以及辉石等硅酸盐逐渐转变为残渣4#中的石英和透辉石,且石英中Si元素赋存比由钛精矿中的0.79%大幅增加至残渣4#中的73.78%。

Discussion on phase transformation characteristics of titanium concentrate during continuous acidolysis process

How to further improve the acidolysis recovery rate was always focused in sulfate process titanium dioxide, and the level of acidolysis recovery rate was closely related to the transformation of titanium-containing phases. The continuous acidolysis process was selected as an example to investigate the change characteristics of titanium-containing phases during the reaction. The mineral analyzer, X-ray diffractometer (XRD), scanning electron microscope (SEM) and some chemical analysis methods were synthetically applied to determine the variation characteristics on content and morphology of main phases in titanium concentrate during the reaction process, as well as the variation characteristics on content and occurrence of Ti and Si elements. The results showed that the titanium concentrate was mainly composed of ilmenite and silicate minerals. In process of acidolysis, the acid permeated into interior along the edges or cracks of ilmenite particles to finally decompose the mineral. Meanwhile, the content of ilmenite decreased from 86.13% (mass fractrion, the same below) in titanium concentrate to 14.38% in residue 4#. During this process, the quartz and diopside were enriched. Their contents increased gradually from 0.06% and 1.58% in titanium concentrate to 50.85% and 14.92% in residue 4#, respectively. In the reaction process, the content of Ti in titanium concentrate decreased from 26.74% to 6.46% in residue 4#, while the content of Si increased from 2.19% to 29.14%. During the reaction process, the occurrence ratio of Ti gradually decreased from 96.08% in titanium concentrate to 64.88% in residue 4#, and Ti migrated mainly from ilmenite to TiOSO₄. Partial Ti elements were encased by quartz and its mixture, leading to the loss of Ti. The main occurrence phases of Si were gradually converted from ilmenite and silicates such as pyroxene in titanium concentrate to quartz and diopside in residue 4#, and the occurrence ratio of Si in quartz increased significantly from 0.79% in titanium concentrate to 73.78% in residue 4#.