Zero-Pollution Preparation for Ammonium Paratungstate

The industrial process for preparing ammonium paratungstate must use a large amount of water and produce a large amount of waste water. Is there a way to change the dependence of purification on water? Recently, some scholars have innovated a process for preparing ammonium paratungstate that is different from traditional methods. Its general content is as follows:

1)Tungsten ore raw materials and ingredients are ground and mixed to prepare raw materials.

2)The raw material is roasted to obtain clinker and the clinker is crushed and ground.

3)The clinker was leached with ammonium carbonate system, ammonium carbonate-ammonium bicarbonate system, ammonium carbonate-ammonia water system and ammonium carbonate-ammonium hydrogencarbonate-ammonium tungstate system.

4)The leaching slurry is separated by solid-liquid separation and slag phase washing to obtain a crude ammonium tungstate solution and leaching slag, and part of the leaching residue is used as an ingredient to return to step 1 for raw material configuration, and the remaining part is stored.

5)Crude tungsten tungstate solution purification impurities.

6)After purification, the solution is evaporated and crystallized to precipitate APT and ammonia gas and carbon dioxide gas are obtained at the same time.

7)The crystallized slurry is subjected to liquid-solid separation to obtain a crystallization mother liquor and a solid phase. The solid phase is washed with an aqueous solution, and after drying, the APT product is obtained after washing.

8)The ammonia gas obtained from the crystallization mother liquor is returned to step 3 together with carbon dioxide, and the clinker is circulated and leached after replenishing the lost ammonium carbonate.

The above-mentioned method has a simple process flow, convenient operation, low production cost, no waste water discharge, and minimized environmental pollution, and is a brand-new process for preparing APT. Eliminating the transformation step of the sodium tungstate solution that will generate a large amount of waste water and directly obtaining the ammonium tungstate solution fundamentally eliminate the waste water discharge in the APT production process, and realizes the recycling of auxiliary materials and solutions.

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