Basic Studies Of The Process Of Scandium Recovery From Red Mud

The object of this paper is red mud.Separation and extraction of valuable elements from red mud have been studied through direct sulfuric acid leaching,titanium white waste acid leaching and sulfation-roasting-leaching process.Among them,the sulfation-roasting-leaching process has high selectivity and operability.The specified studies were as follows:First of all,in sulfuric acid leaching text,through the investigation on effects of s concentrated H₂SO₄,leaching temperature,solid-liquid ratio and leaching time,optimu conditions were determined.Experimental result showed that at H₂SO₄concentration 6mol/L,leaching temperature 60?,solid-liquid ratio 1:3,leaching time 1 h,the leaching rate of Sc?Ti?Fe?Al and Si were 63.56%?69.70%?43.80%?69.32%and 1.72%respectively.Secondly,in titanium white waste acid leaching text,as the reaction temperature increases,the leaching rate of Sc,Ti,Fe and Al increases.The scandium can be effectively leached with leaching temperature 60?.When leaching temperature60?,solid-liquid ratio 1:4 and leaching time 1.5 h,the leaching rate of Sc?Ti?Fe?Al and Si were 68.91%?59.01%?41.37%?67.37%and 72.43%respectively.The high leaching rate of silicon increases difficulty for subsequent separation.Thirdly,Selective recovery of scandium from red mud could be finished through sulfation-roasting-leaching process.Effects of roasting conditions including roasting temperature,concentrated H2SO4 addition and roasting time on the leaching rates of iron,aluminum,silicon,sodium,titanium and scandium were studies and analyzed.During roasting,the decomposition of NaFe?SO₄?₂ should occur before the decomposition of NaAl?SO₄?₂,which should follow the decomposition order of TiOSO4>Fe2?SO4?3>NaFe?SO4?2>NaAl?SO4?2^Al2?SO4?3>Na3Sc?SO4?3>Na2SO4>CaSO4.Around 60%Na,63%Sc,3%Fe,0.2%Ti,28%Al,8%Ca and 1%Si could be leached under the optimized roasting temperature 700?,concentrated H2SO4 addition 0.6g/g and roasting time 2h.The P204,P507 and Cyanex272 were used to extract the Sc from the leaching liquor of sulfation-roasting-leaching red mud.P204?3%v/v?+sulfonated kerosene?95%v/v?+heptanol?2%v/v?exhibts a economically extraction performance for Sc under the condition of A:O of 15:1,extraction temperature of room temperature.Nearly 100%Sc could be extracted out from the red mud leachate.