CN103757399A - Leaching method of lithium cobaltate waste battery positive electrode material - Google Patents

Abstract

The method for leaching the anode material of lithium cobalt oxide waste battery introduced in the present invention is to add the anode material and sawdust separated from the waste lithium cobalt oxide battery and obtained through roasting pretreatment into a pressure-resistant, sulfuric acid and nitric acid corrosion-resistant reaction kettle , adding a mixed solution of sulfuric acid and nitric acid, and stirring and leaching under airtight conditions.

Description

Leaching method of lithium cobalt oxide waste battery cathode material

technical field

The invention relates to a method for leaching the positive electrode material of lithium cobalt oxide waste batteries.

Background technique

Lithium cobalt oxide battery is a type of battery widely used, and a large amount of waste batteries will be generated after the battery is scrapped. Because this type of battery contains a large amount of heavy metals, if it is discarded into the environment, it will cause great direct and potential harm to the environment. The positive electrode material of lithium cobalt oxide waste batteries mainly contains cobalt, lithium, copper and aluminum, and the total content of cobalt, lithium and copper is more than 60%, which is very valuable for recycling. At present, the processes for recovering cobalt, lithium and copper from the positive electrode materials of lithium cobalt oxide waste batteries mainly include fire process and wet process. The products obtained by the fire process are alloy materials, and it is difficult to obtain relatively pure cobalt, lithium and copper. The wet process is relatively easy to obtain relatively pure cobalt, lithium and copper. Leaching is an essential process in the wet process. At present, the leaching methods of lithium cobalt oxide waste battery positive electrode materials mainly include hydrochloric acid leaching method, sulfuric acid leaching method, nitric acid leaching method and mixed acid (sulfuric acid plus nitric acid) leaching method. In the hydrochloric acid leaching method, the equipment is corroded, and the acid mist is produced in large quantities, which pollutes the environment. Sulfuric acid leaching consumes more expensive reducing agents (such as hydrogen peroxide, etc.). The consumption of nitric acid in the nitric acid leaching method is large, and a large amount of nitrogen oxides will be produced, which will pollute the environment. All wet processes have the problem of how to economically increase the leaching speed, increase the metal leaching rate, and reduce the consumption of acid and other auxiliary materials. Although the pure oxygen leaching method in the nitric acid processing industry and the pure oxygen leaching method in the mixed acid processing industry have solved the above problems, the leaching equipment is more complicated, and the amount of industrial pure oxygen required for the leaching of waste batteries is not large, and waste battery treatment enterprises produce on-site Industrial pure oxygen is not economical for personal use, and the storage, transportation and use of industrial pure oxygen are troublesome. The development of a leaching method for lithium cobalt oxide waste battery cathode materials with low equipment corrosion, fast leaching speed, high leaching rate, low acid consumption and other auxiliary material consumption, convenient use, and basically no environmental pollution has great practical value.

Contents of the invention

Aiming at the problem of leaching the positive electrode material of the lithium cobalt oxide waste battery at present, the purpose of the present invention is to find a metal leaching rate high, the leaching speed is fast, the leaching rate is high, the consumption of acid and other auxiliary materials is low, the use is convenient, and no expensive reducing agent is used. The method for leaching the anode material of lithium cobaltate waste battery which is basically non-environmentally polluting is characterized in that the positive electrode material separated from the waste lithium cobaltate battery and obtained through roasting pretreatment and sawdust of ≤1.5mm are added to withstand voltage and withstand pressure. Add the mixed solution of sulfuric acid and nitric acid into the reaction kettle corroded by sulfuric acid and nitric acid, and carry out stirring and leaching under airtight conditions. After leaching, liquid-solid separation is carried out to obtain the desired leaching solution. The reaction temperature is 60℃～80℃, the initial concentration of leached sulfuric acid is 1mol/L～4mol/L, the initial concentration of nitric acid is 5g/L～10g/L, the leaching time is 2h～4h, the leaching process is stirred, and the stirring speed is 30r/min～120r/min. The amount of sulfuric acid added is 110% to 140% of the theoretical consumption of sulfuric acid for the leaching of all metals in the positive electrode material added to the reaction vessel. The amount of sawdust added is 90% to 120% of the mass of LiCoO ₂ in the cathode material on a dry basis.

The object of the present invention is achieved like this: under the condition that airtight and have sawdust and nitric acid to exist, sulfuric acid leaches the waste lithium cobaltate battery anode material (cobalt and lithium in the material exist in the form of lithium cobaltate after roasting pretreatment, When copper and aluminum are mainly in the form of metal oxides), the following main chemical reactions occur during the leaching process:

CuO _{+ H2SO4} = _CuSO4 + _H2O

Al ₂ O ₃ + 3H ₂ SO ₄ = 3Al ₂ (SO ₄ ) ₃ + 3H ₂ O

nC ₆ H ₁₀ O ₅ + nH ₂ SO ₄ =n(C ₅ H ₁₁ O ₅ )HSO ₄

n(C ₅ H ₁₁ O ₅ )HSO ₄ + nH ₂ O = nC ₆ H ₁₂ O ₆ + nH ₂ SO ₄

C ₆ H ₁₂ O ₆ + 8HNO ₃ = 8NO + 6CO ₂ + 10H ₂ O

nC ₆ H ₁₀ O ₅ + 8nHNO ₃ = 8nNO + 6nCO ₂ + 9nH ₂ O

6LiCoO ₂ + 9H ₂ SO ₄ + 2NO = 6CoSO ₄ + 3Li ₂ SO ₄ + 2HNO ₃ + 8H ₂ O

The overall reaction of lithium cobaltate is:

24nLiCoO ₂ + nC ₆ H ₁₀ O ₅ + 36nH ₂ SO ₄ = 24nCoSO ₄ + 12nLi ₂ SO ₄ + 6nCO ₂ + 41nH ₂ O

Other organic matter in sawdust also reacts with nitric acid to generate NO, CO ₂ and H ₂ O, and the generated NO reacts with LiCoO ₂ and H ₂ SO ₄ to generate CoSO ₄ , Li ₂ SO ₄ , HNO ₃ and H ₂ O.

Since the reaction speed of nitric acid and wood chips is faster, the reaction of NO produced with LiCoO ₂ is also faster, thereby speeding up the entire leaching process and achieving a more complete leaching of LiCoO ₂ . NO can completely destroy the layered structure of high-valent oxides in positive electrode materials and improve the leaching rate of valuable metals.

Compared with the existing method, the present invention has the outstanding advantages of using sawdust as the reducing agent and nitric acid as the leaching accelerator to leach the positive electrode material of the lithium cobalt oxide waste battery. The reaction speed is fast, the reaction acidity is low, and the consumption of sulfuric acid and reducing agent is small. And the wood chips are cheap; the layered structure of the high-valent oxide in the positive electrode material is completely destroyed, which can increase the metal leaching rate; the subsequent treatment of the leachate does not need to neutralize a large amount of acid, and the cost is low; the amount of waste generated in the subsequent treatment of the leachate is small. The cost of pollution control is reduced, and it has obvious economic and environmental benefits; the process is carried out under airtight conditions, which avoids environmental pollution caused by NO escape.

Specific implementation method

   Example 1: Add 100g of lithium cobalt oxide waste battery cathode material (containing 53.6% cobalt, 5.3% lithium, 8.2% copper, 3.4% aluminum) and 30g of sawdust ≤ 1.5mm into a titanium-lined pressure reactor with a volume of 2L, and add 1180ml of mixed acid solution with a concentration of sulfuric acid of 1.5mol/L and a concentration of nitric acid of 5g/L was leached at 60°C to 70°C with airtight stirring (stirring speed 80r/min) for 4.0h, and liquid-solid separation was carried out after leaching to obtain 1160ml of leaching solution (without leaching slag washing water). The leaching rates of cobalt, lithium, copper and aluminum are 99.0%, 99.3%, 98.5% and 98.8% respectively (calculated based on cobalt, lithium, copper and aluminum entering the leaching solution and leaching slag washing solution).

Example 2: Add 500g of lithium cobalt oxide waste battery positive electrode material (containing 53.6% cobalt, 5.3% lithium, 8.2% copper, 3.4% aluminum)≤1.5mm sawdust 190g into a titanium-lined pressure reactor with a volume of 5L, and add sulfuric acid Concentration of 3.0mol/L, nitric acid concentration of 10g/L mixed acid solution 3500ml, at 70 ℃ ~ 80 ℃ closed stirring (stirring speed 70r/min) leaching 2h, liquid-solid separation after leaching, to obtain 3300ml leaching solution ( does not contain leaching slag washing water), the leaching rates of cobalt, lithium, copper and aluminum are 99.3%, 99.5%, 99.0% and 98.7% respectively (according to the cobalt, lithium, copper and aluminum in the leaching solution and leaching slag washing solution calculate).

Claims (1)

1. A method for leaching the cathode material of a lithium cobaltate waste battery, which is characterized in that the positive electrode material separated from the waste lithium cobaltate battery and obtained through roasting pretreatment and sawdust of ≤1.5mm are added with pressure-resistant and sulfuric acid-resistant Add a mixed solution of sulfuric acid and nitric acid into the reaction kettle corroded with nitric acid, and carry out stirring and leaching under airtight conditions. After the leaching, carry out liquid-solid separation to obtain the required leaching solution. The reaction temperature is 60 ° C ~ 80 ° C, the leaching The initial concentration of sulfuric acid is 1mol/L ~ 4mol/L, the initial concentration of nitric acid is 5g/L ~ 10g/L, the leaching time is 2h ~ 4h, the leaching process is stirred, the stirring speed is 30r/min ~ 120r/min, the amount of sulfuric acid added It is 110%-140% of the theoretical consumption of sulfuric acid for leaching all the metals in the positive electrode material added to the reaction vessel, and the added amount of sawdust is 90%-120% of the mass of _LiCoO2 in the positive electrode material on a dry basis.