Research On The Recovery Of Valuable Metal Elements And Calcium Carbonate From Red Mu

Red mud is the alkaline solid waste discharged during the extraction of alumina.With the rapid development of aluminum industry,the amount of red mud continues to increase,resulting in the accumulation of more and more.At present,due to the lack of innovative key technologies,the comprehensive utilization of red mud cannot be large-scale utilization,and the harm problem of red mud can not be fundamentally solved.On the other hand,the grade of calcium and titanium resources in red mud is relatively high,and with the continuous innovation and development of technology,the demand for calcium and titanium resources is gradually increasing.If the calcium and titanium in red mud can be utilized,the pressure on the demand for calcium and titanium resources can be reduced,and the economic benefits generated by the comprehensive utilization of red mud can be improved.In view of the above problems,a new idea of comprehensive utilization of red mud was put forward.In this paper,red mud was leached with hydrochloric acid to obtain the leaching solution containing Fe,Al,Ca,Mg,Ti,V,Sc,Zr and other valuable metal elements,as well as the red mud residue.The dry silica gel was aged by wet method and then reacted with sodium hydroxide to prepare liquid water glass.The solvent extraction method was used to extract valuable metal elements such as iron and titanium from the leaching solution,and the aluminum hydroxide was recovered by precipitation method.Finally,calcium carbonate products were prepared.The research contents and results were as follows:（1）The red mud extracted by hydrochloric acid was filtered and aged to obtain the leaching solution and silica gel,and the silica gel was dried to produce dry silica gel.Under the conditions of liquid-solid ratio 5:1,reaction temperature 60℃and reaction time 1h,the influence of acid concentration on the leaching rate of various metal elements was studied,and the optimal concentration of hydrochloric acid was12mol/L.Under the conditions of Na OH concentration of 20%,liquid-solid ratio of3:1,system temperature of 80℃and time of 15min,the reaction with dry silica gel was carried out,and the liquid water glass was obtained at the end of the experiment.（2）The solvent extraction method is used to recover the iron in the leach solution.Compared with P204 and P507,the extraction and separation performance of P507 is better than that of P204.The extraction system and process parameters are determined.Under the conditions of aqueous p H=2.5,extraction temperature 40℃and extraction time 15min,compared with V_O/V_A=3/1,the extraction rate of Fe³⁺,Ti⁴⁺,Ca²⁺and Al³⁺can reach 99.62%,15.23%,1.75%and 9.45%respectively.The reverse extraction effect of hydrochloric acid is better than that of sulfuric acid.Under the condition that the concentration of hydrochloric acid is 5mol/L,the stripping temperature is 25℃,and the stripping ratio of V_O/V_A=1/1,the Fe³⁺back extraction rate can reach 93.12%after 10min.（3）Solvent extraction method to recover titanium in ferric acid leaching solution,through the comparison of TBP and N1923,N1923 extraction and separation performance is better than TBP,to determine the best process parameters,when20%N1923+80%sulfonated kerosene as organic phase,Under the conditions of stirring speed 150r/min,extraction temperature 25℃,extraction time 6min,compared with V_O/V_A=1/1,the extraction rate of Ti⁴⁺,Ca²⁺and Al³⁺can reach 96.71%,5.89%and 3.67%.The reverse extraction effect of ammonia water is better than that of H₂SO₄+H₂O₂mixed solution.Under the condition that the concentration of ammonia water is 5mol/L,the stripping temperature is 25℃,and the stripping ratio of V_O/V_A=1/1,the Ti⁴⁺stripping rate can reach 95.14%after 5min.（4）The aluminum in the titanium acid leaching solution is recovered by precipitation method,and the aluminum hydroxide and the titanium acid leaching solution are configured to react and filter to obtain aluminum hydroxide and filtrate,and the purity of aluminum hydroxide is above 95%;After the reaction of the prepared sodium carbonate solution with the filtrate,the purity of the calcium carbonate obtained is above 99%.