钛精矿酸解尾气中升华硫产生的机理分析

Mechanism analysis of the production of sublimated sulfur in the tail gas of acidolysis of titanium concentrate

针对硫酸法钛白酸解过程中升华硫堵塞管道从而影响钛白粉连续生产的问题,从钛精矿的结构组成分析出发,结合其在酸解过程可能存在的主要化学反应和实际生产中具体的酸解工艺条件,通过计算相关反应的吉布斯自由能变化,绘制酸解反应条件下体系的电位-pH图,探究了酸解尾气中升华硫产生的机理。结果表明,酸解尾气中单质硫应该主要来源于钛精矿中的磁黄铁矿(FeS),磁黄铁矿在酸解的高温(180~220℃)、高酸度(pH:-1.51~-1.47)复杂环境下被氧化生成单质硫,待反应结束后冷却凝固形成升华硫。因此在生产中可以从具体工艺入手,在不降低酸解率的情况下改变酸解环境(改变化学电位、降低环境pH值),以此规避或减小升华硫的产生,降低升华硫对硫酸法钛白的影响。

In order to prevent the continuous production of titanium dioxide from being blocked by sublimated sulfur in the process of titanium dioxide acidolysis by sulflate process,this paper starts from the structural composition analysis of titanium concentrate,combined with the main chemical reactions that may exist in the acidolysis process and the specific acidolysis process conditions in actual production by calculating the change of Gibbs free energy of related reactions.The potentio-pH diagram of the system under the condition of acid hydrolysis was drawn,and the mechanism of the occurrence of sublimated sulfur in the tail gas of acid hydrolysis was explored.The results show that the elemental sulfur in the tail gas of acidolysis mainly come from the pyrrhotite(FeS) in titanium concentrate.The pyrrhotite is oxidized in the complex environment of acid hydrolysis at high temperature(180~220 ℃) and high acidity(pH:-1.51~-1.47) to produce elemental sulfur,which is cooled and solidified to form sublimated sulfur after the reaction.Therefore we can start from the specific process,change the acid hydrolysis environment(change the chemical potential,reduce the environmental pH value) without reducing the acid hydrolysis rate in order to avoid or reduce the occurrence of sublimation sulfur in production,reduce the effect of sublimation sulfur on the sulfate process titanium white.