What are the production processes of nickel sulphate?

Nickel sulfate with the increase in the application of ternary materials, the demand for nickel sulfate is also gradually increasing, copper smelters can prepare nickel sulfate, Kang Jinghui small talk with you about nickel sulfate production process what?

In the process of copper electrolytic refining, nickel is often accumulated in the form of ions and enriched in the electrolyte, nickel is one of the main impurities in the copper anode plate, in the process of copper electrolysis generally requires that the concentration of nickel ions in the electrolyte is not more than 15g/L. Usually, the electrolytic waste solution is de-coppered, and then nickel is removed with the de-coppered post solution.

Nickel Sulfate Production Process

Nickel removal methods mainly include crystallisation method, extraction method, ion exchange method, etc. At present, we mainly use crystallisation method to produce nickel sulphate.

At present, we mainly use the crystallisation method to produce crude nickel sulphate, before the main straight fire concentration method, electrothermal concentration method and freezing crystallisation method, etc., and now take the vacuum evaporation concentration crystallisation method and vacuum evaporation freezing crystallisation method is more common.

1, direct fire concentration method because of simple equipment, simple operation and nickel straight yield advantages, early widely used, but due to the acid volatilization caused by the operating environment, energy consumption, labour intensity and other factors, with the improvement of environmental protection and emphasis on labour safety and hygiene requirements, is no longer belong to the elimination of technology.

2, electrothermal concentration method due to the high degree of automation, environmental protection, nickel removal rate and other advantages of the early part of the factory used, but because of the complexity of the equipment required, large investment and the production of crude nickel sulphate cost, the use of limited.

3, freezing crystallisation method is not widely used due to the need for more equipment, large area, low rate of nickel removal and other factors. Steam indirect heating concentration method (at a certain pressure, the use of steam indirect heating to make the solution evaporation method), because all smelters produce a large amount of surplus steam, the use of low-cost, by small and medium-sized copper smelters generally favoured.

With the gradual maturation of the preparation of nickel sulfate production process, nickel sulfate preparation using vacuum evaporation freeze crystallisation method, in order to improve production efficiency, integrated vacuum evaporation and freeze crystallisation of the two methods.

1, electrothermal concentration method

Electrothermal concentration hair process principle is basically the same as the straight fire concentration method, it is the use of electricity to directly heat the concentration solution, and then water-cooled crystallisation output of crude nickel sulphate.

Electrothermal concentration method with three graphite electrodes inserted into the solution containing the concentration tank, the power supply device output higher current to the electrode, through the solution's own resistance to generate heat so that the solution boils. Water is evaporated at atmospheric pressure to concentrate the solution. The evaporated gas is sent to the sulfuric acid mist absorption tower by the exhaust system for purification and evacuation, and the concentrated solution is cooled by the water-cooled crystallisation tank and filtered by the vacuum suction to get the crude nickel sulfate product.

Electrothermal concentration method due to the consumption of electrical energy, for the electric tension up to the region is not very favourable, the price of electricity is higher, the cost of crude nickel sulfate is higher. The high temperature corrosive gas produced by electrothermal concentration is serious corrosion to the gas purification system, production equipment and plant. At present, only a few manufacturers are using this process.

2,Freeze crystallisation method

Freezing crystallisation is a higher concentration of nickel containing copper final night, first pre-cooling, and then flow through the freezing crystallisation tank continuous freezing crystallisation, generally controlled at -25 ~ -10 ℃. Each crystallisation tank is turned on continuously with low intensity stirring. Crystallised crude nickel sulphate in the crystallisation tank is filtered, the filter cake is crude nickel sulphate, and the filtrate is pre-cooled for the final night of copper removal. Because the nickel in the decopperised liquid is not very high, the efficiency of freezing and crystallisation is not very efficient. Some manufacturers will electrolysis system to a certain concentration, intermittent production of nickel sulfate using cryocrystallisation.

3, vacuum evaporation concentration crystallisation method.

Vacuum evaporation concentration crystallisation method is the use of the solution of sulfuric acid concentration and sulfate solubility at different temperatures there is a certain equilibrium relationship, that is, the solution of sulfate solubility will change with its acidity, temperature changes; at the same time, the solution in different acidity, under different pressures, its boiling point is different, and there is also a certain equilibrium relationship between them.

The use of steam through the titanium plate or heating coil to heat the reaction kettle after decopperisation, and vacuum the reaction kettle to reduce the boiling point of water and accelerate the evaporation speed. Vacuum evaporation production of crude nickel sulfate is mainly the smelter produced by the surplus steam for use, the production cost is low.

4,Vacuum evaporation concentration freeze crystallisation method.

Vacuum evaporation concentration freeze crystallisation method is to remove the copper after the liquid first vacuum evaporation, then pre-cooling, followed by freeze crystallisation, and finally filtered, vacuum evaporation concentration freeze crystallisation efficiency is higher, but because the process is longer, has been concentrated after the removal of copper after the liquid needs to go through some of the pipeline and freeze crystallisation equipment, the equipment corrosion is more serious, increasing the maintenance of the production costs.