CN103757315A - Method for leaching positive pole material of waste nickel-metal hydride battery - Google Patents

Abstract

The method for leaching the anode material of nickel-metal hydride waste battery introduced in the present invention is to add the positive electrode material and coconut shell powder which are separated from the waste nickel-hydrogen 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 positive electrode material of nickel-hydrogen waste battery

technical field

The invention relates to a method for leaching the positive electrode material of nickel-metal hydride batteries.

Background technique

Ni-MH batteries are a type of batteries widely used, and a large amount of waste batteries will be produced after the batteries are 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 nickel-metal hydride batteries mainly contains nickel and cobalt, and the total content of the two is as high as 50-70%, which is very valuable for recycling. At present, the processes for recovering nickel and cobalt from the positive electrode materials of nickel-metal hydride 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 nickel and cobalt. Wet process is easier to get purer nickel and cobalt. Leaching is an essential process in the wet process. At present, the leaching methods of the positive electrode materials of nickel-metal hydride batteries 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. The sulfuric acid leaching method consumes more expensive reducing agents (such as hydrogen peroxide, etc.), and the leaching speed is slow and the acid consumption is high. 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. It is of great practical value to develop a leaching method for nickel metal hydride waste battery anode materials with low equipment corrosion, fast leaching speed, high leaching rate, low consumption of acid and other auxiliary materials, convenient use, and basically no environmental pollution.

Contents of the invention

Aiming at the problem of leaching the positive electrode material of nickel-hydrogen waste batteries at present, the purpose of the present invention is to find a metal with high leaching rate, fast leaching speed, high leaching rate, low acid consumption and other auxiliary material consumption, easy to use, no expensive reducing agent, basically A non-environmentally polluting method for leaching the positive electrode material of waste nickel-hydrogen batteries, which is characterized in that the positive electrode material separated from waste nickel-hydrogen batteries and obtained through roasting pretreatment and coconut shell powder ≤ 1.5 mm are added to withstand pressure 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 required leaching solution. The reaction temperature is 50 ℃ ~ 80 ℃, the initial concentration of sulfuric acid leached 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 coconut shell powder added is 60% to 75% of the total mass of nickel and cobalt in the positive electrode material on a dry basis. the

The object of the present invention is achieved like this: under the condition that airtight and have coconut shell powder and nitric acid to exist, sulfuric acid leaches the waste nickel-hydrogen battery anode material (nickel and cobalt in the material are oxide form) after roasting pretreatment , the following main chemical reactions occur during the leaching process:

NiO _{+ H2SO4} = _NiSO4 + _H2O

CoO _{+ H2SO4} = _CoSO4 + _H2O

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

_3Ni2O3 + _{6H2SO4 +} 2NO = _6NiSO4 + _{2HNO3 + 5H2O}

3Co ₂ O ₃ + 6H ₂ SO ₄ + 2NO = 6CoSO ₄ + 2HNO ₃ + 5H ₂ O

The overall _{reaction of Ni2O3} and _Co2O3 is:

12nNi ₂ O ₃ + nC ₆ H ₁₀ O ₅ + 24nH ₂ SO ₄ = 24nNiSO ₄ + 6nCO ₂ + 29nH ₂ O

12nCo ₂ O ₃ + nC ₆ H ₁₀ O ₅ + 24nH ₂ SO ₄ = 24nCoSO ₄ + 6nCO ₂ + 29nH ₂ O

Other organic matter in coconut shell powder also reacts with nitric acid to generate NO, CO ₂ and H ₂ O, and the generated NO reacts with Ni ₂ O ₃ and Co ₂ O ₃ to generate NiSO ₄ , CoSO ₄ , HNO ₃ and H ₂ O .

Because the reaction speed of nitric acid and coconut shell powder is faster, the reaction of produced NO with Ni ₂ O ₃ and Co ₂ O ₃ is also faster, thereby speeding up the whole leaching process and realizing the comparison of Ni ₂ O ₃ and Co ₂ O ₃ Fully leached. 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 outstanding advantage of the present invention is that coconut shell powder is used as the reducing agent, and nitric acid is used as the leaching accelerator to leach the positive electrode material of the nickel metal hydride battery, the reaction speed is fast, the reaction acidity is low, and the consumption of sulfuric acid and reducing agent is small , and coconut shell powder is cheap; the layered structure of high-valent oxides 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 waste generated in the subsequent treatment of the leachate The amount is small, which reduces the cost of pollution control, and 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 waste nickel-metal hydride battery cathode material (containing 56.4% nickel, 5.9% cobalt) and 37.5g of ≤ 1.5mm coconut shell powder into a titanium-lined pressure reactor with a volume of 2L, and add sulfuric acid at a concentration of 1.5mol/ L. 850ml of mixed acid solution with a concentration of nitric acid of 5g/L, leaching for 4.0h under airtight stirring (stirring speed 80r/min) at 50°C to 60°C, and liquid-solid separation after leaching to obtain 820ml of leaching solution (without leaching residue wash water). The leaching rates of nickel and cobalt are 98.7% and 98.4% respectively (calculated based on nickel and cobalt entering the leaching solution and leaching slag washing solution).

Example 2: Add 500g of waste nickel-metal hydride battery positive electrode material (containing 56.4% nickel, 5.9% cobalt) and 230g of ≤1.5mm coconut shell powder into a titanium-lined pressure reactor with a volume of 5L, and add sulfuric acid at a concentration of 3.0mol/L , 2500ml of mixed acid solution with a nitric acid concentration of 10g/L, leaching at 70°C to 80°C with closed stirring (stirring speed 70r/min) for 2.0h, and liquid-solid separation after leaching, to obtain 2300ml of leaching solution (excluding leaching residue washing water). The leaching rates of nickel and cobalt are 99.6% and 99.4% respectively (calculated based on nickel and cobalt entering the leaching solution and leaching slag washing solution).

Claims (1)

1. A method for leaching the positive electrode material of waste nickel-hydrogen batteries, which is characterized in that the positive electrode material separated from waste nickel-hydrogen batteries and obtained through roasting pretreatment and coconut shell powder 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 is completed, carry out liquid-solid separation to obtain the required leaching solution. 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% to 140% of the theoretical consumption of sulfuric acid for leaching all metals in the positive electrode material added to the reaction vessel, and the added amount of coconut shell powder is 60% to 75% of the total mass of nickel and cobalt in the positive electrode material on a dry basis.