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EP-4735653-A1 - SEMI-BATCH PROCESS FOR OXIDATIVE LEACHING OF NICKEL AND COBALT

EP4735653A1EP 4735653 A1EP4735653 A1EP 4735653A1EP-4735653-A1

Abstract

The present invention provides a semi-batch process for the preparation of a nickel or cobalt sulphate solution, whereby sulphuric acid and hydrogen peroxide are peri- odically fed via a feed section to a reaction zone and whereby an acidic aqueous medium is circulated through the reactor until a predetermined concentration of nickel or cobalt, respectively, in said nickel or cobalt sulphate solution is achieved.

Inventors

  • NEVEN, Margot
  • KLAASEN, Bart
  • VERDICKT, Werner

Assignees

  • Umicore

Dates

Publication Date
20260506
Application Date
20240628

Claims (15)

  1. 1. A semi-batch process for the preparation of a nickel or cobalt sulphate solution in a column reactor (100) comprising a reaction zone (10), said process comprising the steps of: i. feeding metal particles containing nickel or cobalt, respectively, to a reaction zone (10) of said column reactor (100); ii. feeding an aqueous medium to said reaction zone (10); iii. feeding sulphuric acid and hydrogen peroxide via a feed section to the reaction zone (10), thereby contacting hydrogen peroxide with said metal particles containing nickel or cobalt in an acidic aqueous medium; iv. simultaneously with step iii., circulating said acidic aqueous medium by evacuating a fraction of said acidic aqueous medium from said reactor (100) and by recirculating the evacuated fraction to said reactor (100) until a concentration of nickel or cobalt of at least 80 g/L, respectively, and a residual acid concentration below 20 g/L in said nickel or cobalt sulphate solution is achieved; and v. after step iv. evacuating said nickel or cobalt sulphate solution from said column reactor (100).
  2. 2. Process according to claim 1, whereby feeding of sulphuric acid and hydrogen peroxide in step iii. comprises the subsequent steps of: a. feeding sulphuric acid and hydrogen peroxide in a molar ratio of sulphuric acid to hydrogen peroxide of 0.9: 1.0 to 1.1 : 1.0; b. feeding hydrogen peroxide to further reduce the residual acid concentration of said nickel or cobalt sulphate solution.
  3. 3. Process according to claim 2, whereby the sulphuric acid content of the acidic aqueous medium in step iii. a. entering the bottom of the reaction zone (10) is between 15 and 60 g/L.
  4. 4. Process according to any of claims 1 to 3, whereby the residual amount of sulphuric acid of said nickel or cobalt sulphate solution evacuated in step v. is between 2 g/L and 15 g/L.
  5. 5. Process according to any of claims 1 to 4, whereby the concentration of nickel or cobalt in said nickel or cobalt sulphate solution, respectively, evacuated in step v. is between 80 g/L and 200 g/L.
  6. 6. Process according to any of claims 1 to 5, whereby circulating in step iv. is continued after step iii. is ended, until hydrogen peroxide in the nickel or cobalt sulphate solution is substantially exhausted.
  7. 7. Process according to any of claims 1 to 6, whereby the molar ratio of the total amount of hydrogen peroxide fed in step iii. to the total amount of sulphuric acid fed in step ii. and iii. is more than 0.9 and less than 1.1.
  8. 8. Process according to any of claims 1 to 7, whereby at least 80 wt.% of the initial amount of particles containing nickel or cobalt introduced in the column reactor have not reacted with the sulphuric acid and hydrogen peroxide when the process is interrupted and the nickel or cobalt sulphate solution is evacuated.
  9. 9. Process according to any of claims 1 to 8, whereby said aqueous medium fed in step ii. comprises sulphuric acid in a concentration of 5 to 30 g/L.
  10. 10. Process according to any of claims 1 to 9, whereby the aqueous medium entering the reaction zone (10) in steps ii., iii. and iv. has a temperature from 50 °C to 80 °C, preferably from 70 °C to 80 °C, even more preferably from 75 °C to 80 °C.
  11. 11. Process according to any of claims 1 to 10, whereby the reaction temperature at the top of the reaction zone (10) is between 80 °C and the boiling point of the leaching solution, preferably from 85 °C to 99 °C.
  12. 12. Process according to any of claims 1 to 11, whereby the metal particles containing nickel or cobalt are electrolytically obtained.
  13. 13. Process according to any of claims 1 to 12, whereby said metal particles containing nickel or cobalt comprise nickel or cobalt, respectively, in an amount of at least 96 wt.% relative to the total weight of said metal particles.
  14. 14. Process according to any of claims 1 to 13, whereby the column reactor (100) comprises an insulation jacket (50).
  15. 15. Process according to any of claims 1 to 14, whereby the pressure in the headspace above the reaction zone (10) is atmospheric pressure or an under-pressure of less than 0.2 atm.

Description

SEMI-BATCH PROCESS FOR OXIDATIVE LEACHING OF NICKEL AND COBALT TECHNICAL FIELD The present invention relates to a process for manufacturing nickel sulphate and for cobalt sulphate. INTRODUCTION Secondary lithium-ion batteries (LIBs) have found wide-spread applications in portable devices and electric vehicles, as well as in specialized aerospace applications. Important characteristics of reusable batteries include charge/discharge efficiency, cycle durability, energy density and safety. Many developments have focused on improving the performance of the cathode of LIBs. Next to lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate, lithium nickel manganese cobalt oxide ("NMC", LiNixMnyCozO2) and lithium nickel cobalt aluminium oxide ("NCA", LiNixCoyALOz) have received a lot of attention due to their superior performance. They can be easily obtained from mixing a suitable mixed metal precursor with a suitable lithium compound, and subsequent heat treatment of the mixture. Further processing steps are widely reported, e.g., for doping with further elements, providing a surface coating, improving crystallite size, etc. The rising demand for electric vehicles (EVs) has led to an increased demand for high purity nickel and cobalt, especially for high purity nickel sulphate and high purity cobalt sulphate. Effectively, nickel refineries for preparing high purity nickel are considered of paramount importance for the supply of battery materials in the next decade. Such nickel refineries will need to allow for high capacities and high efficiency of the processes to yield the desired nickel sulphate in a desired quantity and high purity. Therefore, novel processes need to be developed and optimized. Amongst other processes, the oxidative leaching of nickel (Ni) from a high purity nickel metal is considered one of the more promising routes. Processes for the leaching of Ni metal in sulphuric acid in the presence of hydrogen peroxide proceed according to the reaction: Ni + H2O2 + H2SO4 -> NiSO4 + 2 H2O This process is also known as oxidative leaching of Ni metal, a process which is highly exothermic (-423 kJ/mol). Similarly, processes for the leaching of Co metal in sulphuric acid in the presence of hydrogen peroxide proceed according to the reaction: Co + H2O2 + H2SO4 -> CoSO4 + 2 H2O and are likewise highly exothermic. WO 2021/105 365 describes a process for manufacturing nickel sulphate by leaching metal particles comprising nickel in an aqueous sulphuric acid solution, said process comprising the steps of introducing the metal particles in the aqueous sulphuric acid solution and introducing an aqueous hydrogen peroxide solution in the aqueous sulphuric acid solution containing the metal particles wherein the aqueous hydrogen peroxide solution is introduced progressively into the aqueous sulphuric acid solution containing the metal particles. Yet, novel processes are in demand for ease of operation, high throughput, and optimized use of reactants as well as reduced consumption of hydrogen peroxide and reduced formation of H2. JP 2011/126 757 describes a method for producing a nickel sulphate aqueous solution with a low content of free sulfuric acid. The method includes filling metal nickel masses in a metal dissolution column, feeding heated sulfuric acid from the upper part of the metal dissolution column and at the same time feeding air or oxygen from the lower part of the metal dissolution column. Such batch processes may, however, suffer from entrainment of non-reacted metal fines in the resulting process output and the equipment must withstand harsh chemical reaction conditions, as high initial H2SO4 acid concentrations are required WO 2022/053448 describes a process for preparing battery grade metal sulphate solutions. Battery grade metal sulphate solutions are prepared directly from electro- lytically produced metal objects, such as cathode plates, that are subjected to an aqueous leaching solution comprising at least one acid leaching agent and a liquid oxidizing agent in a continuous process at elevated temperature in a column with vigorous mixing. Such a continuous process is, however, operated at low acid contents, because typically only a low residual acid content is tolerated in the product stream. This limits the leaching rate and the overall production capacity. Further such continuous processes are not flexible toward changes of reactivity or composition of the reagents, and there is a risk of H2 formation when loading the metal feed into the column during operation. SUMMARY It is therefore an object of the present invention to provide novel, non-continuous processes for preparing metal sulphate solutions under safe conditions with high productivity. The current invention provides a solution for at least one of the above- mentioned problems by providing a process for the oxidative leaching of nickel or cobalt, respectively, in the presence of an acid and an oxidizing agent accor