Comprehensive Treatment of Tungsten-containing Fluorogypsum

About 7% of fluorite is associated with Scheelite in China. The flotation properties of scheelite and fluorite are similar, and scheelite is often found in floatation fluorite concentrate. Tungsten containing fluorite concentrate is obtained from fluorine containing gypsum by dry fluorine process. At present, the slag is mainly sold to cement factories or used to prepare gypsum slabs. Calcium and sulfur in the slag are only treated as low-end gypsum, and no high value-added products are produced. Tungsten is not used at all. White white is losing valuable resources.

In the famous Shizhuyuan of Hunan Province, the CaSO₄ grade of tungsten-containing fluorogypsum is higher than that of the conventional natural gypsum ore, but the impurity content is relatively small, and it contains a certain amount of tungsten. The existing technology has not made good use of this material, resulting in a waste of resources. For this reason, a unique fluorinated gypsum containing treatment technology has been developed by improving the technology. The contents of the process are as follows:

(1)The tungsten-containing fluorogypsum residue (CaSO 497.2%, Fe 0.23%, Al 0.45%, WO 30.17%) was taken for 500 g, then was slurried with 1500 ml tap water, added with 93% sulfuric acid of 10 ml concentration, leached at 50 ℃ for 3h, filtered and washed to obtain refined calcium sulfate and impurity removal waste liquor; the iron and aluminum removal rates of refined calcium sulfate were 87.85%, 95.38% respectively, and the tungsten retention rate was 95.38%. The rate is 84.66%.

(2)Adding 800 ml of 0.1 g polyethylene glycol into the refined calcium sulfate, adding 800 ml of 400 g ammonium carbonate solution to decompose, and stirring at 40 ℃ for 3 h after the addition, the final product of calcium carbonate and the decomposition solution of ammonium tungsten sulfate were obtained.

(3)Take 10L of the above decomposition solution containing ammonium tungstate (WO₃ concentration is 0.36g/L, ammonium sulfate concentration is 296.2g/L) with sulfuric acid to adjust its pH value to 5, using 100 ml D201 resin adsorption for 12 hours, the final Adsorption Tail a, WO₃ concentration is 0.035 g/L, the tungsten adsorption rate is 90.27%, using 300 mL concentration of 5% NaOH + 10% NaCl solution analysis resin. The analytical rate of tungsten is 98.6%, and the analytical solution a is obtained, where WO₃ concentration is 10.68g/L.

(4)2L adsorbed tail liquor a (WO₃ concentration is 0.035g/L, ammonium sulfate concentration is 294.8g/L, PH is 5) evaporated and crystallized to 560ml, then stirred and crystallized at 25 ℃ for 2h. The mother liquor 501ml was filtered, and the ammonium sulfate crystal was 219.5g, and the product N content was 21.1%, which met the requirements of agricultural ammonium sulfate fertilizer. Purified to PH 5.5 ~ 6.8, purified water returned to step (1) acid washing, purified residue for calcium sulfate, iron, aluminum mixture, do cement raw material products.

(5)Taking 2L adsorbed tail liquor a (WO₃ concentration is 0.035g/L, ammonium sulfate concentration is 294.8g/L, PH is 5) to evaporate and crystallize to 560ml, then stirring and crystallizing at 25 ℃ for 2h, the mother liquor 501ml is filtered, the ammonium sulfate crystal is 219.5g, the product N content is 21.1%, which meets the requirements of agricultural ammonium sulfate fertilizer. Adsorption tail liquid B is neutralized by lime and purified to pH 5.5~6.8. Purified water is returned to the acid washing step (1). The purified residue is a mixture of calcium sulfate, iron and aluminum, which is used as raw material for cement production.

The qualified light calcium carbonate, ammonium sulfate and tungsten extract were prepared by making full use of calcium, sulfur and tungsten resources in tungsten fluoride gypsum slag. The process conditions are mild, simple to operate, low in equipment requirements, and conducive to large-scale industrial production.

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