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CN-117228868-B - Method for jointly removing COD, oil content and heavy metals in cobalt-nickel raffinate

CN117228868BCN 117228868 BCN117228868 BCN 117228868BCN-117228868-B

Abstract

The invention belongs to the technical field of nickel-cobalt raffinate sewage treatment, and particularly relates to a method for jointly removing COD (chemical oxygen demand), oil content and heavy metal in cobalt-nickel raffinate. The method for jointly removing COD, oil and heavy metals in the cobalt-nickel raffinate comprises the steps of deoiling adsorption, deoiling resin recovery, alkali precipitation, deoiling adsorption, deoiling resin recovery and the like, and integrates a plurality of adsorption processes in one process. Experiments prove that after the treatment by adopting the method disclosed by the invention, the COD of the effluent can be reduced from 1370mg/L to below 500mg/L, the oil content of the effluent can be reduced from 391.4mg/L to below 10mg/L, and the cobalt and nickel content of the effluent can be stably kept below 0.3 mg/L.

Inventors

  • TANG PING
  • XU KAIHUA
  • LIU TAO
  • XU XIN
  • Rao Youqing
  • MA XIPING

Assignees

  • 荆门市格林美新材料有限公司

Dates

Publication Date
20260512
Application Date
20230831

Claims (6)

  1. 1. The method for jointly removing COD, oil content and heavy metals in cobalt-nickel raffinate is characterized by comprising the following steps of: (1) Deoiling and adsorbing, namely enabling cobalt-nickel raffinate to flow through deoiling resin at the speed of 3-8BV/h, and carrying out deoiling and adsorbing to obtain deoiling resin adsorbing oil and deoiling liquid; (2) Recovering the oil removing resin, namely cleaning the oil removing resin adsorbed with 0.5-2% of H 2 O 2 by mass concentration to obtain washed oil removing resin and high-oil content waste liquid, and blowing off the washed oil removing resin by steam to complete desorption and regeneration to obtain regenerated oil removing resin; (3) Adding 30-50g/L sodium hydroxide solution into the deoiled liquid, regulating the pH value to 8-9, carrying out precipitation reaction, and then carrying out solid-liquid separation to obtain the liquid after alkali precipitation and a solid containing nickel hydroxide/cobalt; (4) Removing heavy adsorption, namely enabling the alkaline precipitation liquid to flow through heavy removing resin at the speed of 3-8BV/h, and performing heavy removing adsorption to obtain cobalt-nickel adsorbing resin and adsorption liquid; (5) And (3) recycling the heavy removal resin, namely sequentially desorbing and regenerating the resin adsorbed with cobalt and nickel by using an acidic solution and an alkaline solution to obtain regenerated heavy removal resin and a high-concentration cobalt and nickel solution, and returning the regenerated heavy removal resin to the step (4) for repeated use.
  2. 2. The method for combined removal of COD, oil and heavy metals from cobalt nickel raffinate according to claim 1, wherein the degreasing resin in step (1) is HPX30 type resin.
  3. 3. The method for combined removal of COD, oil and heavy metals from cobalt nickel raffinate according to claim 1, wherein in step (2), the cleaning time of H 2 O 2 is 100-150min, and the steam stripping time is 100-150min.
  4. 4. The method for combined removal of COD, oil and heavy metals from cobalt nickel raffinate according to claim 1, wherein the weight removal resin in step (4) is D402 type resin.
  5. 5. The method for combined removal of COD, oil and heavy metals in cobalt and nickel raffinate according to claim 1, wherein the specific method in the step (5) is that firstly, the resin for adsorbing cobalt and nickel is eluted by using sulfuric acid solution with the concentration of 300-360g/L for 60-100min, and then the eluted resin is regenerated by using sodium hydroxide solution with the concentration of 50-120g/L for 60-100min.
  6. 6. The method for combined removal of COD, oil and heavy metals from a cobalt nickel raffinate according to any of claims 1-5, wherein the post-adsorption liquid phase of step (4) is comparable to the cobalt nickel raffinate of step (1): the COD content is reduced by more than 65%, the oil content is reduced by more than 98%, the Ni content is reduced by more than 99.7%, and the Co content is reduced by more than 99.9%.

Description

Method for jointly removing COD, oil content and heavy metals in cobalt-nickel raffinate Technical Field The invention belongs to the technical field of nickel-cobalt raffinate sewage treatment, and particularly relates to a method for jointly removing COD (chemical oxygen demand), oil content and heavy metal in cobalt-nickel raffinate. Background In the traditional hydrometallurgical process of cobalt and nickel, a large amount of extractant (mainly referred to as P204 and P507) and sulfonated kerosene (serving as a diluent) are used in an extraction process section to extract cobalt and nickel metal, and raffinate containing high-concentration organic matters is generated after the extraction is finished. Meanwhile, cobalt-nickel metal with certain concentration exists in the extracted raffinate, so that the economic value is extremely high, and the cobalt-nickel metal ions are required to be recovered. In the prior art, the common practice comprises (1) an alkaline method, namely adding liquid alkali or lime milk, converting cobalt and nickel ions into precipitate, and filtering to remove the cobalt and nickel ions. The method is simple and easy to implement, however, the treated wastewater still contains 1.0-5.0 mg/L of nickel and cobalt, and is difficult to thoroughly precipitate and recycle, and (2) the oxidation precipitation method is to add liquid alkali and oxidant simultaneously to oxidize divalent nickel ions into trivalent nickel ions which are easier to precipitate, but because the pH requirement is higher, a large amount of magnesium ions are precipitated while cobalt and nickel are precipitated, and the method cannot reduce Ni to a lower level. It is noted that the presence of organics (mainly COD and oil) in the raffinate can seriously affect the chemical precipitation of cobalt nickel metal, resulting in poor precipitation treatment. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides a method for jointly removing COD, oil content and heavy metal in cobalt-nickel raffinate, which can not only reduce the content of organic matters in the raffinate, but also deeply remove the heavy metal, finally reduce the environmental risk and realize the creation of economic value and environmental-friendly dual benefits. The invention specifically comprises the following contents: a method for jointly removing COD, oil content and heavy metals in cobalt-nickel raffinate comprises the following steps: (1) Deoiling and adsorbing, namely enabling cobalt-nickel raffinate to flow through deoiling resin at the speed of 3-8BV/h, and carrying out deoiling and adsorbing to obtain deoiling resin adsorbing oil and deoiling liquid; (2) Recovering the oil removing resin, namely cleaning the oil removing resin adsorbed with the oil content by using H 2O2 to obtain washed oil removing resin and high-oil content waste liquid, and blowing off the washed oil removing resin by using steam to finish desorption and regeneration to obtain regenerated oil removing resin; (3) Adding alkaline solution into the deoiled liquid, regulating the pH value to 8-9, carrying out precipitation reaction, and then carrying out solid-liquid separation to obtain alkaline precipitated liquid and nickel hydroxide/cobalt-containing solid; (4) Removing heavy adsorption, namely enabling the alkaline precipitation liquid to flow through heavy removing resin at the speed of 3-8BV/h, removing heavy adsorption to obtain cobalt-nickel adsorption resin and adsorption liquid, feeding the adsorption liquid into a pH callback tank, adjusting pH to be neutral, and discharging until the total discharge port of the wastewater reaches the standard. (5) And (3) recycling the heavy resin, namely sequentially desorbing and regenerating the resin adsorbed with cobalt and nickel by using an acidic solution and an alkaline solution to obtain regenerated heavy resin and high-concentration cobalt and nickel solution, and returning the regenerated heavy resin to the step (4) for repeated use, wherein the high-concentration cobalt and nickel solution is returned to the front end for reuse. Preferably, the degreasing resin in the step (1) is HPX30 type resin (sea water HPX30 type degreasing adsorption resin). Preferably, in the step (2), the mass concentration of the H2O2 is 0.5-2%, the cleaning time of the H2O2 is 100-150min, and the steam stripping time is 100-150min. Preferably, the alkaline solution in the step (3) is sodium hydroxide solution with the concentration of 30-50 g/L. Preferably, the heavy resin removed in the step (4) is a D402 type resin (senat D402 type macroporous chelate ion exchange resin). Preferably, the specific method in the step (5) comprises the steps of eluting the resin for adsorbing cobalt and nickel by using a sulfuric acid solution with the concentration of 300-360g/L for 60-100min, and regenerating the eluted resin by using a sodium hydroxide solution with the concentration of 50-120g/L for 6