Investigation of Reactive Origin for Attachment of Cu Droplets to Solid Particles

Abstract

Both primary and secondary copper production encounter a limitation in the process efficiency due to droplet losses in slags. One of the causes for the mechanical entrainment of these droplets is their interaction with solid spinel particles, hindering the sedimentation of the copper droplets. Previous experiments with synthetic slags provided insights into this interaction and yielded two possible mechanisms: separately formed droplets and particles become attached to one another due to fierce agitation of the slag and metal phases; or the spinel particles and metal droplets form as the result of a chemical reaction together with a new droplet or alongside a droplet that was already present in the system. This experimental study aims to investigate the hypothesis of the formation of copper droplets sticking to spinel particles due to a chemical reaction further. A slag that is initially free from Cu droplets was prepared. After creating controlled conditions to induce the chemical reaction, the formation of sticking dropletswas observed. The results from this experiment therefore confirm the previously proposed reactive mechanism.

Metal losses in pyrometallurgical operations - A review

“…Furthermore, it was also observed some copper droplets were completely surrounded by spinel solids present in the slag system. Both observations, together with the fact that the attachment occurs even though the slag exhibits a better wetting than copper on spinel, support the explanation of the reactive origin of the attachment [62,67,68].…”

“…After the insertion of a steel bar in the system, the formation of sticking droplets was observed. [68] A reaction scheme was proposed, including two possible pathways where the spinel solids form together with the copper droplets or form around the copper droplets, depending on the local conditions of the system. In both pathways, redox reactions involving copper (oxides) are essential and within the applied synthetic system, Fe and Fe-oxides play a crucial role.…”

Phase-Field Modelling in Extractive Metallurgy

“…In all these processes, (non-)wetting may play an important role to deteriorate or improve the phase separation between different phases, e.g., the attachment of the metal phase to certain solid particles within the liquid slag which hinders their sedimentation. [133][134][135][136][137][138][139] Wetting is generally subdivided in nonreactive and reactive wetting, which were both already modelled with the phase-field method.…”

Influence of Process Parameters on Copper Content in Reduced Iron Silicate Slag in a Settling Furnace

“…Settling processes can also be hindered by the attachment of copper to solid phases, as suggested in experimental studies by Bellemans et al and De Wilde et al [27][28][29][30]. Copper attached to spinels has a lower density than the underlying copper phase and thus cannot settle completely [29].…”