CN103757357A - Leaching method of nickel-cadmium waste battery positive electrode material - Google Patents

Abstract

The method for leaching the positive electrode material of nickel-cadmium waste battery introduced by the present invention is to add the positive electrode material and reed powder separated from nickel-cadmium waste battery and obtained through roasting pretreatment into a pressure-resistant, sulfuric acid and nitric acid corrosion-resistant reaction kettle, Add a mixed solution of sulfuric acid and nitric acid, and carry out stirring and leaching under airtight conditions.

Description

Leaching method of positive electrode material of nickel-cadmium waste battery

technical field

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

Background technique

Nickel-cadmium batteries are a type of widely used batteries, 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-cadmium waste batteries mainly contains nickel and cobalt, and the total content of the two is as high as about 60%, which is very valuable for recycling. At present, the processes for recovering nickel and cobalt from the positive electrode materials of nickel-cadmium 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 nickel-cadmium 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. It is of great practical value to develop a leaching method for nickel-cadmium waste battery anode 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.

Contents of the invention

Aiming at the problem of the leaching of the positive electrode material of the nickel-cadmium waste battery 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 The method for leaching the positive electrode material of waste nickel-cadmium battery without environmental pollution is characterized in that the positive electrode material separated from the waste nickel-cadmium battery and obtained through roasting pretreatment and reed powder of ≤1.5mm are added with pressure-resistant, sulfuric acid-resistant and Add the mixed solution of sulfuric acid and nitric acid to the reaction kettle corroded by 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 reed powder added is 60% to 75% of the total mass of nickel and cobalt in the positive electrode material on a dry basis.

The object of the present invention is achieved like this: under the condition that reed powder and nitric acid exist in airtight, when sulfuric acid leaches the spent nickel-cadmium battery cathode material (nickel and cobalt in the material are metal 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 reed 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.

Due to the fast reaction speed of nitric acid and reed powder, the reaction of NO produced with Ni ₂ O ₃ and Co ₂ O ₃ is also fast, thus speeding up the whole leaching process and realizing the completeness of Ni ₂ O ₃ and Co ₂ O ₃ leach. 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 reed powder is used as reducing agent, and nitric acid is used as leaching accelerator to leach the positive electrode material of nickel-cadmium 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 reed powder is cheap; the layered structure of the high-valent oxide in the positive electrode material is completely destroyed, which can increase the metal leaching rate; there is no need to neutralize a large amount of acid in the subsequent treatment of the leachate, and the cost is low; the amount of waste generated in the subsequent treatment of the leachate 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 100 g of the positive electrode material (containing 55.2% nickel, 3.8% cobalt) and 35.5 g reed powder ≤ 1.5 mm into a titanium-lined pressure reactor with a volume of 2 L through roasting pretreatment, and add sulfuric acid concentration 800ml of mixed acid solution with a concentration of 1.5mol/L and a concentration of nitric acid of 5g/L was stirred at 50°C to 60°C (stirring speed 80r/min) for 4 hours, and liquid-solid separation was performed after the leaching was completed to obtain 770ml of leaching solution (without leaching slag washing water). The leaching rates of nickel and cobalt are 99.1% and 99.0% respectively (calculated based on nickel and cobalt entering the leaching solution and leaching slag washing solution).

Example 2: Add 220 g of reed powder ≤ 1.5 mm into a titanium-lined pressure reactor with a volume of 5 L, and add sulfuric acid at a concentration of 3.0 mol/L, nitric acid concentration of 10g/L mixed acid solution 2500 ml, stirred at 70 ℃ ~ 80 ℃ (stirring speed 70r/min) leaching 2h, liquid-solid separation after leaching, to obtain 2300 ml leaching solution (without leaching slag washing water). The leaching rates of nickel and cobalt are 99.4% and 99.1% respectively (calculated based on nickel and cobalt entering the leaching solution and leaching slag washing solution).

Claims (1)

1. the leaching method of a nickel anode material of used nickel cadmium battery, it is characterized in that by positive electrode material isolated from waste nickel-cadmium batteries and that obtain through roasting pretreatment and≤reed powder of 1.5mm adds withstand voltage, in the reactor of resistance to sulfuric acid and nitric acid corrosion, the mixing solutions that adds sulfuric acid and nitric acid, and carry out in confined conditions agitation leach, after finishing, leaching carries out liquid-solid separation, obtain required infusion solution, temperature of reaction is 50 ℃～80 ℃, the sulfuric acid starting point concentration leaching is 1mol/L～4mol/L, the starting point concentration of nitric acid is that 5g/L～10g/L extraction time is 2h～4h, leaching process stirs, stirring velocity is 30r/min～120r/min, sulphuric acid is to add 110%～140% of sulfuric acid theoretical consumption that in the positive electrode material of reaction vessel, all metals leach, the add-on of reed powder is counted nickel in positive electrode material with butt, 60%～75% of cobalt total mass.