Method for preparing crude sodium tungstate solution by decomposing black tungsten concentrate under high temperature and high pressure with low alkali

Abstract

The invention discloses a method for preparing a rough sodium tungstate solution by decomposing wolframite concentrate at a high temperature and high pressure through low alkaline. The method comprises the following steps that wolframite concentrate powder and water are mixed to form wolframite pulp, sodium hydroxide, trisodium phosphate and sodium nitrate are sequentially added into the wolframite pulp to mix the pulp, mixed wolframite pulp is formed and decomposed, the decomposing temperature is 192 DEG C-210 DEG C, pressure is 0.8 MPa-1.0 MPa, after decomposing, diluting, filter pressing and washing are carried out, a filtrate is taken, and the rough sodium tungstate solution is obtained, wherein the adding amount of the sodium hydroxide is 1.4-1.6 times the theoretical amount of the weight of tungsten trioxide in the wolframite concentrate powder. The method has the beneficial effects that the amount of the alkaline is reduced, and the tungsten decomposing rate of the wolframite concentrate is increased.

Description

technical field [0001] The invention relates to the field of tungsten smelting. More specifically, the present invention relates to a method for preparing crude sodium tungstate solution by decomposing black tungsten concentrate at high temperature and high pressure with low alkali. Background technique [0002] my country's black tungsten concentrate smelting process has gone through three stages of development: the first stage, soda sintering (later decomposed by sodium hydroxide) introduced from the Soviet Union in 1958 → purification and removal of impurities → precipitation of scheelite → acid decomposition → ammonia dissolution → evaporation The classic process of producing ammonium paratungstate (APT) by crystallization, due to long process, low metal recovery rate, serious corrosion, poor product quality and other process defects, the classic process was basically withdrawn from the production field in early 1990; the second stage, 1981, black tungsten pressure cookin...

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Problems solved by technology

[0003] The current tungsten smelting process mainly uses sodium hydroxide to decompose tungsten ore to obtain crude sodium tungstate solution. Although the whole process is a mature process, some manufacturers consume too much sodium hydroxide as an auxiliary material, and the amount of sodium hydroxide reaches the theoretical decomposition level. 2.5 to 3.0 times the amount of sodium hydroxide, resulting in too much residual sodium hydroxide. Therefore, before the subsequent ion exchange of the crude sodium tungstate solution, it is necessary to consume a large amount of water to dilute the crude sodium tungstate solution to make the concentration of sodium hydroxide less than 8g / L, resulting in waste water Increased processing workload and increased production costs