Using Waste Material Recover Tungsten By Ammonium Leaching

Tungsten-soft scrap is a waste that accrues by the production of hard metal tools. The land filling of this valuable material causes serious ecological and economic problems. Thus, it is required to recover tungsten with appropriate techniques, for instance by leaching.

According to an exemplary embodiment of the invention, a method of recycling tungsten within a waste material is provided. The method comprises (a particularly continuous or uninterrupted, i.e. without any intermediate method step between) roasting the waste material in an oxidizing atmosphere for at least partially converting tungsten compounds of the waste material (such as metallic tungsten and/or tungsten carbide and/or other compounds comprising tungsten) into tungsten oxide, and, directly after the roasting (particularly without any intermediate method step between), leaching the roasted waste material for separating tungsten components from remaining components. The tungsten components are leached (this may or may not be the before mentioned leaching process) in an alkaline ammonia solution so that the tungsten oxide is selectively dissolved. The method further comprises separating remaining solid components of the leached roasted waste material from the dissolved tungsten oxide.

According to an exemplary embodiment of the invention, a process for at least partially recycling tungsten from impurified tungsten scrap is provided. A gist of such a process is the combination of a continuous oxidative roasting procedure directly followed by a selective leaching of the resulting metal oxides to separate different metal components by a solid/liquid separation. Separation of specific tungsten components from other components (such as components comprising other metals and/or other tungsten components) may be performed by producing an ammonia solution. In such an ammonia solution, the tungsten components can be brought in the liquid phase, whereas other components are in a solid phase. By applying only one (or a single-stage) roasting procedure at moderate temperatures it is possible to significantly accelerate the recycling process as compared to conventional approaches which apply complicated multiple-step roasting procedures interrupted by reduction processes.


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