Effects Of Organics On Gibbsite Precipitation In Sodium Aluminate Solution

Bauxite resources are mainly diasporic bauxite which is low A/S.The consumption of alkali is too high and alumina recovery is too low in the traditional Bayer process.Dressing Bayer is added to flotation technology on the basis of the Bayer process,and makes the low-grade bauxite A/S increase to 10 to 11 to enter the bauxite Bayer process.Dressing Bayer can be economically processed in low-grade bauxite.In the Dressing Bayer,beneficiation reagent,flocculant and crystallization aids can enter into the process,and they have bad effects on the decomposition of sodium aluminate solution and the size of the Al?OH?₃ particales.According to actual production conditions of Alumina Factory in Henan,in this study,we analyze the organics of added pharmacy,sodium aluminate solution in different process and Al?OH?₃ and determine the source,type,content and the effect on decomposition.We study the effect of decomposition conditions?such as temperature,seeds,time?on decomposition and fix the best conditions by decomposition experiment.The conclusions are drawn as follow:Analyazing by gas chromatography,organic carbon analyzer,infrared spectrometer,the results shows that collector,flocculants and crystallization aids in the TOC contents are 5.05%,47.84%,and 45.41%.Collector components may be oleic or linoleic acid,and flocculants is sodium polyacrylate,and crystallization aids is sodium stearate.Analyazing by gas chromatography,organic carbon analyzer,infrared spectrometer,liquid chromatography and gas chromatography,the results shows that semen,vertical disk liquor and recycling mother liquor TOC was 2.45g/L,2.31g/L,2.51g/L,and they substantially have no collector and flocculants,but crystallization aids.The mainly organics includes oxalate,acetate,formate,propionate,dipropyl ketone,succinate and so on.Oxalate is 2.55g/L in semen,and it is higher than vertical plate liquor and recycling mother liquor.Aluminum hydroxide decomposition products TOC content of 0.40 percent,and have crystalline additive not collectors and flocculants.Small organic molecules is mainly oxalate,acetate,formate,propionate,and oxalate content is relatively high.So aluminum hydroxide decomposition products take away some small organics and crystallization aids.Under the same conditions of decomposition,the decomposition rate of organic-free sodium aluminate solution is greater than the industrial sodium aluminate solution,and the organic can reduce the size of the Al?OH?₃ particales which is deeply effected by the temperature system.Reducing the initial temperature and slower speed in previous stage and fast speed in later stage are better which are in favor of the improving the decomposition rate and size of the Al?OH?₃ particales.According to studying the effects of organics on decomposition rate and size of the Al?OH?₃ particales,When formate is 1.5g/L,acetate is 1.5g/L,oxalate is 5g/L,collector is 3g/L,they all can reduce the decomposition rate of sodium aluminate solution and the decomposition products of granularity,and its presence is not conducive to seed sodium aluminate solution decomposition.According to studying the influence of decomposition temperature system,the seed addition and decomposition time to sodium aluminate solution decomposition rate and the particle size,we determine the best conditions:decomposition temperature system of 58??47??45?,the decomposition time for the pre-23h,late as 22h,and seed dosage of 700g/L.