US 8,986,632 B2 · Process for recovery of cobalt, ruthenium, and aluminum from spent catalyst

Abstract

A method for recovering cobalt, ruthenium, and aluminum from spent Co—Ru/Al2O3 catalyst. First, Co—Ru/Al2O3 spent catalyst is subjected to hydrocarbon removal, reaction with hydrogen, and alkali fusion to obtain a slag. The slag is subjected to acid leaching, precipitation of cobalt with oxalic acid or ammonium oxalate, reduction of cobalt oxalate, and dissolution of cobalt metal with nitric acid to obtain Co(NO3)2.6 H2O. The effluent of acid leaching is subjected to reaction with ethanol, filtration to obtain a filtrate and residue, dissolution of the residue with concentrated hydrochloric acid, and vacuum distillation to obtain β-RuCl3.x H2O. Aluminum hydroxide is prepared from the filtrate through carbonation and calcination. The cobalt yield is ≧97%; the ruthenium yield is ≧95%, and the aluminum yield is ≧92%.

A method for recovering metal cobalt, ruthenium, and aluminum from a spent Co—Ru/Al2O3 catalyst, the method comprising:

1) transferring loose particles of a spent Co—Ru/Al2O3 catalyst to a muffle furnace;
then introducing air into the muffle furnace and calcining the loose particles at 350-500° C. for 3-6 hours to remove heavy hydrocarbons from surfaces of the loose particles;
and then cooling the loose particles down to room temperature to obtain cooled particles;
2) grinding the cooled particles of 1) into powders;
then transferring the powders to a fluidized bed reactor;
then purging the fluidized bed reactor with nitrogen for 0.5 hour;
and then heating the powders in a mixed atmosphere containing H2 and N2 at a H2-to-N2 volume ratio of 1:1-4:1, a space velocity of 1000-4000 h−1, a pressure of 0.1-1 MPa, and a temperature of 350-800° C. for 8-12 hours to obtain heated powders;
3) disposing the heated powders of 2) and alkali fusing agents into layers in a crucible;
then transferring the crucible to a muffle furnace;
then heating the muffle furnace at 200° C. for 1 hour;
then increasing a temperature of the muffle furnace by 3° C./min to a temperature falling within the range of 900-1000° C. using a temperature program;
then maintaining the muffle furnace at the temperature falling within the range of 900-1000° C. to conduct an alkali fusion reaction for 2-4 hours;
and then cooling the muffle furnace to room temperature to obtain an alkali fusion product;
4) leaching the alkali fusion product of 3) in deionized water at a temperature of 90-100° C. and a solid-to-liquid weight ratio of 1:2-1:4 for 0.5-1 hour to dissolve water-soluble K2RuO4 and KAlO2, or Na2RuO4 and NaAlO2, in the alkali fusion product;
and then filtering to obtain a residue and a first filtrate;
5) washing the residue of 4) until a first effluent reaches a neutral pH and collecting the first effluent;
and then adding excess dilute nitric acid to the residue to dissolve cobalt metal and cobalt oxide in the residue to obtain a cobalt nitrate solution;
6) adjusting the cobalt nitrate solution of 5) to a Co2+ concentration of 20 g/L, a pH of 1.5, and a temperature of 70° C.;
then adding oxalic acid solution or ammonium oxalate solution at a pH of 1.5 and a temperature of 70° C. to the cobalt nitrate solution to precipitate cobalt ion as cobalt oxalate, wherein a molar amount of oxalic acid in the oxalic acid solution or a molar amount of ammonium oxalate in the ammonium oxalate solution is 3-4 times a molar amount of the cobalt ion;
then hot-filtering to obtain a cobalt oxalate residue;
then washing the cobalt oxalate residue with deionized water at a temperature of 65-80° C.;
and then dehydrating the cobalt oxalate residue with absolute ethanol to obtain pink cobalt oxalate precipitate;
wherein the pink cobalt oxalate precipitate is produced according to the following chemical reactions:
Co(NO3)2+H2C2O4+2 H2O→CoC2O4.2 H2O ↓+2 HNO3;
or
Co(NO3)2+(NH4)2C2O4+2 H2O→CoC2O4.2 H2O ↓+2 NH4NO3;
7) drying the pink cobalt oxalate precipitate of 6) in a dryer at 80-110° C.;
then transferring the pink cobalt oxalate precipitate to a fluidized bed reactor;
then purging the fluidized bed reactor with nitrogen for 0.5 hour;
and then reducing the pink cobalt oxalate in a mixed atmosphere containing H2 and N2 at a H2-to-N2 volume ratio of 1:1-4:1, a temperature of 400-560° C., a pressure of 0.1-1 MPa, and a space velocity of 1000-4000 h−1 for 2-4 hours to obtain cobalt metal;
wherein the cobalt metal is produced according to the following chemical reaction:
CoC2O4.2 H2O→Co+2 CO2+2 H2O;
8) adding dilute nitric acid to the cobalt metal of 7) until the cobalt metal completely dissolves;
and then evaporating to obtain Co(NO3)2.6 H2O;
9) mixing the first filtrate of 4) and the first effluent of 5) to obtain a mixture;
then dropwise adding absolute ethanol to the mixture and stirring to produce black ruthenium hydroxide precipitate;
then filtering to separate a second filtrate from the black ruthenium hydroxide precipitate;
then washing the black ruthenium hydroxide precipitate with deionized water at a temperature of 65-80° C. until a second effluent reached a neutral pH or does not contain potassium or sodium ions and collecting the second effluent;
and then washing the black ruthenium hydroxide precipitate with absolute ethanol for three times to obtain ruthenium hydroxide;
wherein the black ruthenium hydroxide precipitate is produced according to the following chemical reactions:
10) transferring the ruthenium hydroxide of 9) to a three-necked flask equipped with stirring and refluxing devices;
then adding concentrated hydrochloric acid to the three-necked flask and stirring at 91-95° C. for 1-2 hours;
then adding hydroxylammonium chloride to completely dissolve the ruthenium hydroxide to obtain a solution;
then allowing the solution to stand;
then transferring the solution to a distilling flask and vacuum-distilling at 40±1 kPa until the solution is converted into a paste;
and then stopping vacuum distillation to allow a liquid in the paste to evaporate spontaneously to obtain β-RuCl3.x H2O;
wherein the β-RuCl3.x H2O is produced according to the following chemical reactions:
Ru(OH)4+4 HCl→RuCl4+4 H2O;
and
2 RuCl4+2 NH2OH HCl→2 RuCl3+N2↑+4 HCl+2 H2O;
11) mixing the second filtrate and the second effluent of 9) to obtain a mixed liquid;
then introducing CO2 having a purity higher than 99.0% into the mixed liquid and stirring at a temperature of 25-95° C. to produce white aluminum hydroxide precipitate;
then stopping reaction when a pH of the mixed liquid reaches 10.0;
then filtering and washing the white aluminum hydroxide precipitate with deionized water at a temperature of 65-80° C. until a third effluent reaches a neutral pH or does not contain potassium or sodium ions;
and then washing the white aluminum hydroxide precipitate with absolute ethanol for three times to obtain aluminum hydroxide;
wherein the white aluminum hydroxide precipitate is produced according to the following chemical reactions:
2 KAlO2+CO2+3 H2O→K2CO3+2 Al(OH)3 ↓;
or
2 NaAlO2+CO2+3 H2O→Na2CO3+2 Al(OH)3 ↓;
and
12) drying the aluminum hydroxide of 11) at 80-130° C.;
and then calcining at 500-750° C. to obtain aluminum oxide;
wherein the aluminum oxide is produced according to the following chemical reaction:
2 Al(OH)3→Al2O3+3 H2O.

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Process for recovery of cobalt, ruthenium, and aluminum from spent catalyst

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Process for recovery of cobalt, ruthenium, and aluminum from spent catalyst

Life of this patent

Abstract

Claims18