Zero Pollution Leaching Ammonium Tungstate Solution

Ammonium tungstate solution is an important intermediate material in the process of preparing APT from tungsten smelting industry. At present, the methods of preparing ammonium tungstate solution used in industry mainly include soda pressing, soda sintering, acid decomposition, ammonium salt decomposition and tungsten ore roasting ammonia leaching.

In the existing technology, various processes for preparing ammonium tungstate solution have to be discharged in high pollution to pursue low cost, or must be exchanged for zero emission at high cost. If emissions are thoroughly processed, the investment needed will be even more than production profits. Therefore, many enterprises choose low cost for profit, but seriously pollute the environment, destroy the ecology, deteriorate the living state of human beings, and make it difficult to achieve sustainable development.

Researchers have proposed a leaching method of ammonium tungstate solution, which is different from conventional technology, which can achieve zero pollution leaching.

After mixing calcium carbonate and tungsten oxide according to CaO/WO₃ molecule than 3.1:1, Ca₃WO₆ was synthesized at 800 ℃ in muffle furnace at 800 ℃, and 325 mesh sieves (<45 m) were fined after the synthesis of Ca₃WO₆. Then 5.0g Ca₃WO₆ and 50g were used to analyze pure ammonium carbonate, and then added to the microreactor, then 50mL deionized water was added, closed and stirred, and 0.5h was leached at 80. After leaching, the leach slurry was vacuum filtered and washed with deionized water for three times. The leaching rate of tungsten is 92.90%.

In the above method, tungsten is directly into the solution in the form of ammonium tungstate, without the transformation of ion exchange or solvent extraction; of the auxiliary materials used, carbon dioxide and ammonium carbonate are cheap and easy to get, and the utilization rate is high; the leaching process pressure is low and the operation is simple; the concentration of ammonium tungstate solution is high, and the subsequent tungstate acid is high. The preparation process of ammonium has no significant influence, and the ammonium carbonate system is easy to circulate during the process of preparation of APT. The leaching system of ammonium bicarbonate - ammonium hydrogen carbonate - ammonium tungstate, ammonium carbonate - ammonium tungstate, or ammonium carbonate ammonium tungstate - ammonia water solution system is leached, and the material of the leaching system is converted into ammonia and two oxygen after the crystallization process. It can return to the leaching system and realize its recycling, completely detached from the traditional open circuit system or the open circuit semi circulation system, so as to solve the pollution problem caused by the waste water discharge in the current industrial production and realize the clean production.

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