Low Grade Tungsten Molybdenum Ore High Efficiency Utilization

After a long time of mining, the quality of China's tungsten and molybdenum have been exhausted, and the effective separation of high requirements on the treatment process, if the preparation of high value-added utilization of low-grade refractory molybdenum mixed concentrate directly of high purity tungsten and molybdenum alloy products, simplify the process, but also can realize the efficient use of difficult to use tungsten and molybdenum resources.

Tungsten molybdenum alloy has excellent properties of preventing molten zinc corrosion, with high melting point, corrosion resistance and flame erosion resistance of solid particles. It is widely used as some corrosion resistance components of zinc liquid temperature tube, heating electrode casing, zinc liquid pump rotor and zinc smelting furnace. It is also used as a tungsten molybdenum crucible for sapphire growth.

A high purity tungsten molybdenum alloy was prepared by using low grade tungsten molybdenum mixed concentrate. By the method of CO leaching, CO crystallization, CO roasting and co reduction, the tungsten molybdenum alloy was prepared by the mixed concentrate of calcium tungstate and calcium molybdate. The process includes the following steps

(1) The low grade calcium tungstate and calcium molybdate mixed concentrate were roasted for 1~5 hours in the temperature range of 550~700°C, and the roasting ore was obtained.

(2) At room temperature, the pH value of the hydrochloric acid solution to the roasting ore is 0.6~3.0, then filtered, washed and dried.

(3) Soda and silica were added into the products and the sintered material was sintered for 1~4 hours under air atmosphere at 750~900 C, and the addition of soda was 0.7~1.2 times of the quality of the obtained product, and the amount of silica added was 0.12~0.18 times the quality of the obtained product.

(4) The sintering material obtained by 80~95°C water for 1~2 hours, filtering to obtain the leaching liquid and residue, the residue with 80~95°C water washing 1~3 times, get the washing liquid and dregs, mixing the leaching solution and washing solution evenly mixed crude sodium tungstate solution with sodium molybdate; wherein, sinter water immersion when the solid-liquid ratio was 1:5~1:7kg/L.

(5) The mixed crude solution is evaporated to 1.18~1.25g/cm3, boiling and adding dilute hydrochloric acid to regulate pH to 12.5~13.5 under continuous stirring, and after boiling for 20~40 minutes, adding ammonium chloride to adjust pH to 8~9, adding animal glue, and then cooling to filtrate and getting filtrate; among them, the amount of animal glue is added. For sodium tungstate and sodium molybdate total quality 0.1%~1%

(6) Adding ammonia water in the filtrate to adjust pH to 10~12, then adding magnesium chloride to adjust the filtrate pH to 8.5~9.5, then heating to 80~90°C, settling to the clarification, adding ammonium sulphide, and maintaining the 80~90°C for 5~60 minutes, the mixed purification solution of sodium tungstate and sodium molybdate is obtained by filtration, and the addition of ammonium sulphide is the 0.1%~0.3% of total sodium tungstate and sodium molybdate.

(7) After the mixture was heated to 55~65°C, the mixture was stirred with ammonium chloride, and the mixture of ammonium tungstate and ammonium molybdate was obtained by boiling to 1.35~1.40g/cm3, stopping heating and stirring for 25~35 minutes. The mixture of ammonium tungstate and ammonium molybdate was obtained by filtration, washing and drying.

(8) The mixed compounds were obtained by calcination, one hydrogen reduction and twice hydrogen reduction.

(9) The tungsten molybdenum mixed powder was pressed and formed, and then sintered for 4~8 hours at 2100 1800°C in vacuum or hydrogen atmosphere to obtain tungsten molybdenum alloy.

This method uses the refractory low grade tungsten molybdenum ore, low grade calcium tungstate and calcium molybdate mixed concentrate directly to obtain high added value high purity tungsten molybdenum alloy products, so that the tungsten and molybdenum resources have been used efficiently.

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