Recycle Sodium Hydroxide from Sodium Tungstate Solution

In the existing technology, high alkali pressure cooking technology is commonly used in the smelting of scheelite concentrate and middle ore, and the amount of alkali is generally 2.8 ~ 4 times of the theoretical amount. The mass ratio of excess NaOH and WO₃ in the crude sodium tungstate solution after the alkali pressing filter is 0.7 ~ 1.2. If it is not recycled, it has a negative effect on the subsequent process.

Therefore, no matter from the lower raw material consumption, or from the view of energy saving and emission reduction is necessary to excess sodium hydroxide recovery of tungsten smelting coarse sodium tungstate. Recovery of excess sodium hydroxide has the following main steps:

(1) Tungsten ore is mixed with water in a ball mill by a volume ratio of 10: 3 to a ball mill to get tungsten pulp, and sodium hydroxide solution is added to the tungsten pulp. The content of sodium hydroxide solution added to sodium hydroxide solution is 1 to 1.4 times the content of tungsten trioxide in tungsten ore, and then the tungsten will be added to the sodium hydroxide solution. The pulp was pumped into a stirred medium pressure reactor to obtain alkaline pressure cooking slurry by alkaline pressure cooking. The alkali pressed slurry was obtained by two pressure filtration to obtain crude sodium tungstate solution.

(2) When the crude sodium tungstate solution is fed into the feed preheating device of the three effect evaporation crystallizer, when the preheating temperature of the sodium tungstate solution reaches the boiling temperature of the three effect evaporation unit heater, the crude sodium tungstate solution is pumped into the evaporation unit of the three effect evaporation unit, and the vapor-liquid separation is carried out by the three effect separation crystallization device after the evaporation and concentration. The residual steam is separated into the condensing device and separated into an evaporation unit of an evaporation unit. After evaporation and concentration, the separation of gas and liquid is carried out by one effect separation crystallization device.

(3) After separation of gas and liquid through one effect separation crystallization device, one concentration of steam is separated into the evaporation unit of two effect evaporation unit as a heating source. The two concentration liquid is separated into the evaporation unit of two effect evaporation unit. After crystallization, the vapor liquid separation is carried out by two effect separation and crystallization.

(4) The two concentration liquid is separated by two effect crystallization device, and the two steam as heating source is separated into the evaporation unit of three effect evaporation unit. The sodium tungstate crystal slurry is separated into the plate frame pressure filter, and the filtrate is concentrated by the concentration of sodium hydroxide solution to the ammonium para tungstate production process. The slag is filtered into tungsten smelting after the dissolution of sodium tungstate crystal. The preparation process of the solution before ion exchange.

This method has high automation and convenient operation. The crystallization of sodium tungstate can be concentrated in the two effect evaporation unit, and the recovery efficiency of sodium tungstate is high. After the recovery of the excess sodium hydroxide in the crude sodium tungstate solution, the cost of liquid treatment can be reduced after the ion exchange of tungsten smelting, and the amount of sulphuric acid that regulates the pH value during the treatment of tungsten smelting wastewater is reduced. The cost and cost of resources are greatly reduced.

• < Prev
• Next >