Production of FeNi and other ferroalloys

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.

However, the consequential shift in feed composition, which is also provoked by an increasing processing of low-grade nickel resources (laterite and saprolite) instead of high quality pentlandite, changes the behavior of the materials during reduction respectively refining as well as the wear of refractories and also affects the product quality. Anyhow, only limited data is available about the impact of abnormal elements or deviant concentrations on the whole ferronickel production process.

Thus, a further topic of the CDL-TM addresses the mutual interactions between material compositions (feed, metal, slag, etc.), process conditions and wear of the refractory for reduction and refining. In doing so, one main focus is on physical and chemical properties of particular slags such as viscosities, melting range and solubilities for refractory constituents. Additionally, the integrated hot stage of the scanning electron microscope should provide supplementary useful results regarding wear mechanisms by measurements at elevated temperatures. The expected results from theoretical and empirical investigations will form a basis to compile a model of the relevant courses of action in both process steps, which allows the simulation of different process variants for ferronickel and later on other ferroalloys.