Comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore
A comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore, comprising the following steps: S1. placing an iron-aluminum slag produced by laterite nickel ore hydrometallurgy in a tube furnace, and introducing an HCl gas stream for a one-stage distillation at 185-290° C. to obtain a one-stage distillation tail gas and a one-stage distillation residue; and condensing the one-stage distillation tail gas to obtain anhydrous AlCl 3 ; S2. introducing an HCl gas stream to the one-stage distillation residue for a two-stage distillation at 320-500° C. to obtain a two-stage distillation tail gas and a two-stage distillation residue; and condensing the two-stage distillation tail gas to obtain anhydrous FeCl 3 ; S3. subjecting the two-stage distillation residue to a leaching treatment by using a leaching solution to obtain a leaching residue and a leaching solution; subjecting the leaching solution to a scandium precipitation treatment to obtain a scandium precipitate and a de-scandiumed liquid; S4. adjusting the pH value of the de-scandiumed liquid to obtain an MHP. The obtained aluminum, iron, and scandium products have high purity and high recovery.
1 . A comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore, characterized by comprising the following steps:
S1, placing an iron-aluminum slag produced by laterite nickel ore hydrometallurgy in a tube furnace, and introducing an HCl gas stream for a one-stage distillation at 185-290° C. to obtain a one-stage distillation tail gas and a one-stage distillation residue; and condensing the one-stage distillation tail gas to obtain anhydrous AlCl 3 ;
S2, introducing an HCl gas stream to the one-stage distillation residue for a two-stage distillation at 320-500° C. to obtain a two-stage distillation tail gas and a two-stage distillation residue; and condensing the two-stage distillation tail gas to obtain anhydrous FeCl 3 ;
S3, subjecting the two-stage distillation residue to a leaching treatment by using an extracting solution to obtain a leaching residue and a leaching solution; subjecting the leaching solution to a scandium precipitation treatment to obtain a scandium precipitate and a de-scandiumed liquid; and
S4, adjusting the pH value of the de-scandiumed liquid for a precipitation treatment to obtain a mixed hydroxide precipitate (MHP).
2 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein step S1 further comprises absorbing the HCl gas stream after the one-stage distillation by using lye, and step S2 further comprises absorbing the HCl gas stream after the two-stage distillation by using lye.
3 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 2 , wherein the flow rate of HCl gas streams used in the one-stage distillation and the two-stage distillation is kept constant, and the concentration of the lye in step S1 and step S2 is kept constant.
4 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein the extracting solution in step S3 is water or acid; the solid-liquid ratio of the two-stage distillation residue to the leaching solution is 50-200 g/L; the leaching temperature is 20-25° C.; and the leaching time is 0.5-2 h.
5 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 3 , wherein the acid is one or more of inorganic acid or organic acid, and the concentration of the acid is 0.001-0.1 mol/L.
6 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein in step S3, the scandium precipitation treatment comprises the following steps: adjusting the pH of the leaching solution to 4-6 and filtering to obtain the scandium precipitate and the de-scandiumed liquid, wherein the scandium precipitate is one or more of scandium hydroxide and scandium oxalate.
7 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein step S3 further comprises calcining the scandium precipitate at 500-1000° C. for 0.5-5 h to obtain scandium oxide.
8 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein the leaching residue comprises a mixture of SiO 2 and CaSO 4 , the leaching residue being used for the manufacture of environmentally friendly permeable brick or ceramsite.
9 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein in step S4, the pH is 9-10.
10 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein the flow rate of the HCl gas streams for the one-stage distillation and the two-stage distillation is 10-300 ml/min, and the introduction time is 0.5-3 h.
11 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein in the process of introducing the HCl gas stream, the following reactions gradually occur by controlling the distillation temperature:
the hydroxides of iron, aluminum, and scandium are respectively converted into the corresponding solid salts by introducing HCl;
AlCl 3 is sublimated from a solid state(s) to a gas state (g) by controlling T (185-290° C.) under introducing HCl; and
FeCl 3 is sublimated from a solid state(s) to a gas state (g) by controlling T (320-500° C.) under introducing HCl.
12 . The comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore according to claim 1 , wherein the lye comprises one or more of ammonia and sodium hydroxide, and the concentration of the lye is 1-3 mol/L.