Technical solutions to improve operating conditions of Vanukov furnace while processing technogenic raw materials

The global trend of ore quality degradation, which is occurring in parallel with increased production volumes of primary metals, has led to the necessity of comprehensive processing of raw materials. This involves the concentration and recycling of metallurgical technogenic wastes, which were previously considered unprofitable. In particular, this means the introduction of dump tailings and sludges from holding ponds to concentration, as well as the feeding of matured concentrates, dump, and recycled slags, and in-house low-grade reverts to metallurgical processing. The feed and the product of its concentration demonstrate an increased content of the refractory spinel phase, which has a variable composition. A share of the technogenic feed in charge of head smelting units exceeds 20%. The majority of main smelting units employ autogenous processes, such as flash smelting, liquid bath smelting, and oxygen-flash smelting. The processing of technogenic low-heat feed in autogenous smelting units results in thermal imbalance, loss of melt homogeneity, and, consequently, disrupts the discharge of smelting products, potentially leading to complete shutdown of the unit. Such behavior is typical for both types of autogenous units operated in the Nornickel Polar Division, namely the Vanukov furnace and the flash smelting furnace. The issue of melt heterogeneity and the formation of refractory accretion at problem areas of the flash smelting furnace is widely known and sufficiently investigated in foreign literature as well as by the authors of this paper. However, further investigation is required for the Vanukov furnace, with a particular focus on the formation mechanism of the intermediate layer phase in the melt. This investigation should aim to develop effective mitigation strategies to address the adverse impact of this phase formation.