The key factor for pushing ahead the semidirect recycling route is, that at the moment most of the industrially applied techniques for cemented carbide recycling are based on a modulation of the primary route (indirect recycling) or the zinc-process (direct route). Depending on the scrap quality the latter isn’t appropriate, because of the remaining coating material in the recyclate which reduces its utilizability. Nevertheless a complete processing through the primary route after the mandatory oxidation is neither the ideal method.

Today, not only primary sources, such as ores and concentrates, but also secondary materials (residues and by-products from various industrial processes) are in general feedstocks for production of ferroalloys. A significant increase of their demand during the last decades as well as progressively stricter environmental laws effected intense research activities in that field to improve existing or develop new processes, especially for the utilization of secondary raw materials aiming either to a complete conversion in marketable products or to an inertisation of the non-usable residue. Examples therefore are the feed of lithium ion as well as nickel metal hydride batteries for the recovery of ferronickel at which it is also progressively attempted to extract additional elements such as lithium or rare earth elements.

Nowadays, industrial applications for recycling of hard metals focus on the zinc process and on feeding scrap into the primary, hydrometallurgical route. The latter is only suitable for pure hard scrap of sufficiently small particle size due to the required process time. The zinc process works based on the fact that zinc forms voluminous intermetallic phases with cobalt metal that acts as a binder in most common hard metals. In summary, it effectuates only disintegration without separation of impurities. Also, the matrix used in drill bits for oil and gas exploration consists of a complex alloy made of copper, manganese, nickel, and zinc.

Some elements, such as precious metals, exhibit low concentrations in common ores. In secondary resources, e.g. waste electrical and electronic equipment (WEEE), these metals are more concentrated than in primary raw materials. Furthermore some other special metals, such as rare earth elements (REE), are contained in WEEE. This generally forms a big advantage for the recovery of these metals, but there are further aspects, which must be considered.