Within the framework of a review of the fundamental processes applied for the manufacture of ammonium paratungstate (APT) the main byproducts and wastes generated in these processes and their environmental impact are summarized. A subsidiary process based on the electrodialytic recovery of NaOH for the elimination of the salt byproduct, which is generated in the largest quantities, is outlined together with the main aspects to be taken into account for large-scale industrial implementation. The present stage of development and implementation of an APT production line for the processing of typical scrap material from the light filament industry is shown, as well as the oxidizing and dissolving process of compact and lumpy tungsten alloy scrap (Cu-W, Fe-Ni-W) and hard metal scrap (Co-WC, Co-WC-Ta(Nb)C-TiC). Several as yet unexploited potentials are sketched which could, from scientific and engineering standpoints, be interesting for the development of more efficient intermediate manufacturing processes for APT and tungsten or process operation for a wide variety of raw materials.
展开▼
