Wetting behaviour of Cu based alloys on spinel substrates in pyrometallurgical context

Abstract

Metal droplet losses in slags are an important issue in copper industry. One significant aspect that promotes the entrainment of metal droplets in the slag is their attachment to spinel solids. In the present study, the wetting behaviour of copper alloys on spinel substrates has been investigated in the presence and absence of a slag phase. At first, the attachment was investigated using a synthetic slag containing spinel particles. Microstructural analysis of quenched slag reveals the presence of microdroplets sticking onto a surface of the spinel particles. Second, the metal–spinel interaction was investigated using the sessile drop technique. Wetting angle measurements were performed between Cu–Ag alloys and MgAl2O4 substrates. A non-wetting behaviour between the alloys and substrates was observed. The results suggest that the oxygen partial pressure and the amount of Ag in the alloy both influence the wetting behaviour.

Investigation of High-Temperature Slag/Copper/Spinel Interactions

“…[12] There exists, however, an important additional source of mechanically entrained droplets which have been omitted in most studies: the attachment of droplets to solids in slags, hampering the sedimentation. This observation was reported by Ip and Toguri [9] and Andrews, [11] and demonstrated for a synthetic slag system by De Wilde et al [13] These solids are often found to have a spinel structure. Even though the copper attachment to solid spinels was clearly observed, [13] limited experimental or industrial data and fundamental insights concerning the active mechanisms are available.…”

“…This observation was reported by Ip and Toguri [9] and Andrews, [11] and demonstrated for a synthetic slag system by De Wilde et al [13] These solids are often found to have a spinel structure. Even though the copper attachment to solid spinels was clearly observed, [13] limited experimental or industrial data and fundamental insights concerning the active mechanisms are available.…”

“…For the Cu-Ag alloys, a less explicit effect of the oxygen partial pressure was observed, indicating a combined effect of oxygen partial pressure and the alloy composition. [13] This could also explain the difference in observed trend as compared to the results of Pebo et al [27,28] They observed a lower surface tension (i.e., a smaller contact angle) when the Cu-Ag alloys contained more Ag. One should note, however, that they used oxygen potentials consistently smaller than 10 À15 atm, which could thus explain the difference in observed trend.…”

“…For the specific wettability of metals on spinel substrates, Kozlova et al [25] and Fukami et al [26] performed experimental studies on the wettability of iron on MgAl 2 O 4 spinel substrates. As described in our previous work, [13] the wetting behavior between Cu and Cu-Ag alloys on MgAl 2 O 4 was examined in an oxygen partial pressure range between 10 À13 and 10 À8 atm using a sessile drop technique. A non-wetting behavior was observed for all alloys, with a maximal contact angle between 140 and 150 deg for the Cu-12.5 wt pct Ag alloy.…”

Phase field modelling of the attachment of metallic droplets to solid particles in liquid slags: Influence of interfacial energies and slag supersaturation

“…However, a perfect phase separation is virtually impossible in practice and valuable metals are lost or reprocessing is required. Insufficient phase separation can originate from mechanical entrainment of metallic droplets, of which the attachment to solid particles in slags is one of the possible reasons, as illustrated in Figure 1 [1]. This attachment creates production losses in industrial Cu smelters [2,3], Pb reduction melting furnaces [4] but also in other industries [5].…”