Method for recovering excess sodium hydroxide in tungsten smelting crude sodium tungstate solution

Abstract

The invention discloses a method for recovering excess sodium hydroxide in a tungsten smelting crude sodium tungstate solution. The method comprises the steps of mixing a tungsten ore raw material and water according to the volume ratio of 10: 3, then adding into a ball mill for ball milling to obtain tungsten ore slurry, adding a sodium hydroxide solution into the tungsten ore slurry to perform alkali autoclaving to obtain alkali autoclaved slurry, and performing pressure filtration on the alkali autoclaved slurry twice so as to obtain a crude sodium tungstate solution; pumping the crude sodium tungstate solution into a feeding and preheating device; enabling sodium tungstate crystal slurry obtained by separation after the well preheated crude sodium tungstate solution sequentially passes through a three-effect evaporation unit, a one-effect evaporation unit and a two-effect evaporation unit for evaporation and crystallization to enter a plate frame for pressure filtration so as to obtain a concentrated odium hydroxide solution and sodium tungstate crystals. The method disclosed by the invention has the advantages of high degree of automation, convenience in operation and capabilities of greatly reducing energy consumption, reducing later-stage wastewater neutralization control burden, reducing labor cost, reducing labor intensity and being easy to implement, and is in line with the national policies of reducing cost, increasing efficiency, saving energy and reducing emission.

Description

technical field [0001] The invention relates to the technical field of tungsten smelting, and mainly relates to a method for recovering excess sodium hydroxide in crude sodium tungstate solution for tungsten smelting. Background technique [0002] With the continuous mining of tungsten ore resources, the reserves of tungsten concentrates, especially high-grade black tungsten concentrates, are becoming less and less. In the prior art, the smelting of scheelite concentrate and medium ore generally adopts high-alkali pressure cooking technology, and the amount of alkali dosing is generally 2.8 to 4 times the theoretical amount. Excess NaOH and WO 3 The mass ratio of sulfuric acid reaches 0.7-1.2, or even higher. If it is not recycled, it will not only have an adverse effect on the subsequent process, but also consume sulfuric acid to neutralize it before it can be discharged. Therefore, it is necessary to recover the excess NaOH in the crude sodium tungstate solution of tungs...

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Problems solved by technology

The disadvantages of this method are: firstly, the three-effect downstream evaporation process adopted consumes more energy than the three-effect counter-current or three-effect mixed-flow process. / L solution to prepare liquid caustic soda with NaOH concentration of 42-50%, the steam consumption per ton of NaOH is 3.5-3.8t if three-effect downstream evaporation is used, and the steam consumption per ton of NaOH is three-effect countercurrent / three-effect mixed-flow evaporation 2.6-2.8t, the energy consumption is significantly lower than that of the three-effect downstream evaporation; the second is that sodium tungstate crystals have been precipitated in the second-effect evaporation crystallization section, although there is a crystal outlet, but with the increase of the concentration of the mixed solution, the viscosity Gradually strengthened, it is still easy to cause fouling on the heating tube side, resulting in tube blockage

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