Alloy Leaching and Copper Sulfurization for Ni-Co Recovery
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Solution Overview
Problem
Current methods for recovering nickel and cobalt from alloys in discarded lithium ion batteries face challenges such as energy consumption, environmental concerns, and inefficiencies in separating copper, nickel, and cobalt due to the distribution of cobalt into slags during pyrometallurgical processes, and the difficulty in handling toxic substances in hydrometallurgical processes.
Innovation Solution
A method involving a leaching step with an acid and sulfurizing agent, followed by a cementation step with a reducing agent to remove copper, where the copper-removed residue is fed back into the leaching process to enhance nickel and cobalt recovery, optimizing the pH and timing of the slurry formation to prevent sulfide formation and improve leaching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pyrometallurgical process is used to recover valuable metals from discarded lithium ion batteries, then a variety of impurities can be separated at a time and the process is energy-efficient, but cobalt is almost entirely distributed into the slag causing loss in cobalt recovery
Solution Approach 1:
The invention divides the recovery process into two distinct stages: (1) pyrometallurgical processing to separate impurities and obtain copper-based alloy containing nickel and cobalt, and (2) selective leaching to extract nickel and cobalt from the alloy. This segmentation allows each process to optimize for its specific function, preventing cobalt loss while maintaining impurity separation efficiency
Solution Approach 2:
The copper-based alloy serves as an intermediary carrier that temporarily holds both nickel and cobalt after pyrometallurgical processing. This intermediary form allows selective chemical treatment in the leaching stage to recover cobalt without the direct contact that would cause its distribution into slag during the pyrometallurgical process
2Quantity of substance
If gradual cooling is used to separate copper and nickel from the alloy, then some separation can be achieved, but copper and nickel uniformly melt together in all composition ranges and only form a mixed layered solid
Solution Approach 1:
The invention replaces the mechanical/physical separation method (gradual cooling) with a chemical separation method (selective leaching). By using sulfuric acid solution, nickel and cobalt are selectively dissolved from the copper-based alloy, achieving precise separation that physical cooling cannot accomplish
Solution Approach 2:
The invention changes the separation mechanism from physical parameter (temperature gradient during cooling) to chemical parameter (acid concentration and composition). By controlling the leaching conditions with sulfuric acid, selective dissolution of nickel and cobalt is achieved while copper remains in the solid phase
3Manufacturing precision
If nickel undergoes disproportionation reaction with carbon monoxide to volatilize and separate from copper and cobalt, then separation can be achieved, but the use of toxic CO gas makes it difficult to ensure safety
Solution Approach 1:
The invention changes the chemical reagent from toxic carbon monoxide to non-toxic sulfuric acid solution. This parameter change maintains the separation capability while eliminating the safety hazard, as sulfuric acid does not pose the same inhalation risks as CO gas
Solution Approach 2:
The invention converts the potential harm of using strong acids (corrosiveness) into a benefit by selecting sulfuric acid, which while corrosive, is non-toxic and does not require the extensive safety measures needed for CO gas handling. The acid's corrosiveness is controlled and contained, while its non-toxic nature eliminates respiratory hazards
4Manufacturing precision
If electrolytic refining is used to obtain high purity nickel and copper, then high purity can be achieved, but the process is expensive and complex
Solution Approach 1:
The invention replaces the complex electrolytic refining process with a simpler chemical leaching process. By using sulfuric acid to selectively dissolve nickel and cobalt, high purity solutions are obtained without the need for expensive electrolytic cells, power consumption, and complex control systems required by electrolytic refining
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively obtains a solution with high concentrations of nickel and cobalt by suppressing recovery loss and maintaining efficient leaching, reducing the formation of sparingly soluble sulfides, and enhancing the separation of nickel and cobalt from copper.
Implementation Method 1
a leaching step of performing a leaching treatment by adding an acid solution to the alloy in the presence of a sulfurizing agent to obtain a leachate and a leaching residue
Implementation Method 2
a cementation step of performing a copper-removal treatment by adding a reducing agent and a sulfurizing agent to the leachate obtained in the leaching step to sulfurize copper contained at least in the leachate to obtain a post-copper-removal solution and a copper-removed residue
Implementation Method 3
a cementation step of performing a copper-removal treatment by adding a reducing agent and a sulfurizing agent to the leachate obtained in the leaching step to sulfurize copper
Data Source
AI summary
The present invention pertains to an alloy treatment method for obtaining a solution containing nickel and/or cobalt from alloys containing nickel and/or cobalt and copper, such as waste lithium-ion batteries, the method comprising: a leaching step S1 in which an acid solution is added to the alloys in the presence of a sulfurizing agent to perform a leaching treatment and obtain a leachate and a leaching residue; and a cementation step S2 in which a reducing agent and a sulfurizing agent are added to the resulting leachate to perform a copper-removal treatment for sulfurizing at least copper contained in the leachate and obtain a post-copper removal solution and a copper-removed residue, wherein the copper-removed residue obtained through the copper-removal treatment in the cementation step S2 is repeatedly subjected to the leaching step S1 and subjected to a leaching treatment together with the alloys.