Chloride Titanium Dioxide Production In Boiling Chloride Residue

The boiling chlorination slag produced during the process of titanium pigment production will cause serious environmental pollution, if the chloride is piling up directly. DuPont of US treated the chloride by water filtration, which injected the filtrate directly into the 1600m under the ground. And there is risk of pollution. Ti-Cons of Germany used lime to neutralize water filtrate to treat and recycle calcium chloride. However, because the calcium chloride market in Yunnan Province has reached saturation, this method does not suit the current situation. Therefore, in this article, the boiling chlorination sla was recycled from the filtrate by neutralized with NaOH and further filtration. The process can be completed in three steps:First, the determination of the dissolve condition of boiling chlorination slag solution, the investigation of the process of impurity of boiling chlorination slag filtrate, and the research on the recycle of insoluble product and hydroxide.The optimal conditions to dissolve the boiling chlorination slag are as follows:residue size(-0.074mm accounted for 91.6%); pH=1; solid-liquid ratio 4:1; 30 minute reaction time; reaction at room temperature(25℃). Under these conditions, the solution rate of the main metal chloride is above 90%. The conditions to remove impurity in dissolved boiling chlorination slag are as follows:add NaOH into water, filtrate at pH=5.2, add iron powder into the filtrate, mix and then add NaOH, add quantitative Na2CO3·10H2O when adjusting pH to 7.0-8.0, when reaction completes, add NaOH to adjust pH=12, continue to filtrate, then add HC1 to neutralize the solution at pH=7.0. In this procession, Na2CO3·10H2O and the iron powder help to improve the effect of filtration. The appropriate quantity of Na2CO3·10H2O is 20g in 500mL filtrate. The appropriate quantity of iron powder is 1.5g. In the processing of filtration, hydroxide is produced at pH5.2 and pH12. Hydroxide from pH5.2 can produce Fe2O3 containing 55% iron by roasting and wash. P, S, As and other impurity is not over standard. The Fe2O3 can be used as grade 4 iron ore. Hydroxide from pH12 contains a mass of water-soluble materials. Re-wash and recollect these water-soluble materials. The re-washed filtrate can be used to dissolve boiling chloride residue. The re-washed residue is innoxious and can be stacked. The author treated the boiling chlorination slag with filtration to prevent the hazard to environment. While fitting the technical requirement, the recycle and utility can be realized.