Environment protecting hydrometallurgical processes associated with the manufacture of some tungsten based products. I. The manufacture of ammoniumparatungstate (APT)

Abstract

Reviewing the fundamental processes adopted for ammoniumparatungstate (APT) manufacture the main byproducts, wastes generated in the processes, have been summarized with their environmental impacts. A process based on the electrodialytical recovery of NaOH for the elimination of the salt byproduct generated in the largest quantities was outlined, as were the main aspects to be taken into account at the large-scale industrial implementation. The present stage of the development and implementation of an APT production line for the processing of typical scraps in the lamp filament industry is shown as well as the oxidizing and dissolving process of compact and lumpy tungsten alloy scraps (CuW, FeNiW) and hard metal scraps (CoWC, CoWCTa(Nb)CTiC). Some up-until-now unexploited potentials were sketched, being desirable from scientific and engineering aspects for the development of more efficient and up-to-date ATP and other tungsten-intermediate manufacturing processes or process operations from a wide variety of raw materials.