Studies of Layer Growth During the Disintegration of Cemented Carbides with Vaporous Zinc

Abstract

The recycling of cemented carbides (CC) is an indispensable facet of resource conservation, especially for critical raw materials, signifying its profound environmental, economic, and strategic importance. These complex materials, consisting of refractory carbides embedded in a metallic binder, mainly tungsten carbide and cobalt, offer versatile recycling options. Among these methods, the zinc process is emerging as the most promising with significant potential regarding energy consumption and quality of products. In this method, zinc reacts with cobalt binder to form intermetallic phases, resulting in a breakdown of the material's composite structure due to the higher volume of these phases. In the second step, Zn evaporates at high temperatures under vacuum, leaving behind a porous cemented carbide skeleton. By means of crushing, grinding, and sifting, these can be processed into a powder mixture suitable for direct use in the manufacture of new products. While previous research has focused on the formation of Co-Zn phases during the decomposition step, there is a gap in understanding the growth rate of the disintegration layer. Therefore, this study aims to investigate the layer growth and the kinetics of the disintegration stage of the zinc process. By examining these aspects, a deeper understanding of the fundamental mechanisms at play in this method is gained, contributing to further advancements in the recycling of cemented carbides.