钛石膏硫酸浸取法提取铁质氧化物及石膏的物相变化

硫酸法生产钛白粉副产大量钛石膏,因其含有较多杂质而无法直接利用,目前可采用硫酸酸浸处理提高钛石膏的品质。本文以硫酸为浸取剂,研究钛石膏中铁质氧化物在不同硫酸浓度、反应温度、固液比、反应时间条件下的溶出规律以及酸浸产物的物相变化;采用XRD、XRF、SEM等分析手段,对钛石膏酸浸前后样品的物相、化学成分、形态等进行分析。结果表明,硫酸酸浸可以有效去除钛石膏中铁质氧化物,最佳工艺条件下去除率可达93.14%,白度由原来的8.1提高至54.4。在酸浸过程中随着硫酸浓度、反应温度、固液比等浸取条件的改变,钛石膏中的二水石膏脱水形成半水石膏和无水石膏。采用硫酸酸浸法处理钛石膏,滤液经处理可获得Fe(OH)₃,废液可循环利用,将为钛石膏的资源化利用提供新途径。

Extraction of iron oxide from titanium gypsum by sulfuric acid leaching and phase transform of gypsum

Titanium gypsum is a by-product in the production of titanium dioxide by sulfuric acid method. The impurities in titanium gypsum limit the usage of it. Sulfuric acid leaching processing can be used to improve the quality of titanium gypsum. Using sulfuric acid as a leaching agent, the dissolution rules of iron oxide in titanium gypsum and the phase change of acid leaching products were investigated under different sulfuric acid concentration, reaction temperature, solid-liquid ratio and reaction time. XRD, XRF, SEM and other analytical methods were used to analyze the phase, chemical composition and morphology of the samples before and after the acid leaching of titanium gypsum. The results show that the sulfuric acid leaching can effectively remove the iron oxide from titanium gypsum, and the removal rate can reach 93.14% under the optimum conditions, and the whitenes increases from 8.1 to 54.4. During the acid leaching process, dehydration of dihydrate gypsum in titanium gypsum forms hemihydrate gypsum and anhydrite as sulfuric acid concentration, reaction temperature, solid-liquid ratio, reaction time changed. Titanium gypsum is treated by sulfuric acid leaching method, Fe(OH)₃ can be obtained from the filtrate after treatment. The waste liquid can be recycled, which will provide a new way for the resource utilization of titanium gypsum.