The Physical Chemistry of Copper Smelting Slags—A Review

Abstract

A review is presented of the more important studies on copper smelting slags carried out since about the mid-1960s. This includes work on physical properties, constitution of slags, slag chemistry, control of metal losses, distribution of minor elements including Pb, Zn, Cd, Sn, Bi, As, Sb, Ni, Co, Se, Te, In, Pd, Pt, Au and Ag in reverberatory, continuous smelting, converting and refining slags. Some comments are made concerning the rate of fluxing and the need for good slag making in copper smelter operations.Copper losses and the solubility of various metals in slags are examined. Laboratory and operating data for the distribution of elements between matte, metal and slag for all the important smelting processes today are presented and the application of a recent physico-chemical model is described. The behaviour of metals which are slagged in the smelter is discussed and the pathway of metals such as cobalt, nickel and lead in smelting circuits is examined. A new thermodynamic model for slag cleaning by reduction is briefly described.Reswne-L'article presente un compte-rendu des plus importantes etudes ayant ete effectuees sur les scories de fusion du cuivre depuis Ie milieu des annees soixante. Ceci comprend les proprietes physiques, la composition des scories, la chimie des scories, Ie controle des pertes en metal, la distribution des elements secondaires y compris Pb, Zn, Cd, Sn, Bi, As, Sb, Ni, Co, Se, Te, In, Pd, Pt, Au et Ag das les scories de reverbere, de la fusion continue, du convertissage et du raffinage. L'auteur ajoute quelques commentaires sur Ie taux de fluxage et sur la necessite de contr61er la composition des scories en ce qui concerne la fusion pour matte.Les pertes en cuivre et Ia solubilite de divers metaux dans les scories sont egalement examinees. Les donnees experiment ales et operationnelles pour la distribution des elements entre la matte, Ie metal et les scories sont presentees pour to us les procedes de fusion importants ayant cours aujourd'hui. L'auteur decrit egalement l'application d'un modele physico-chimique recent. Le comportement des metaux faisant partie des scories de fusion dans Ie four est discute et Ie parcours de metaux tels que Ie cobalt, Ie nickel et Ie plomb est etudie dans les circuits de fusion. L'auteur decrit brievement un nouveau modele thermodynamique pour Ie nettoyage des scories par reduction.* The "standard" slag used by Higgins and Jones [62J analysed 41.5 % Si02, 26.6 % FeO, 9.6 % A1203, 22.3 % CaO.

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

“…The increased copper content of slag could be due to the elevated content of dissolved copper, which did not settle. This hypothesis was supported by the review by Mackey [13] and the results from Shishin et al [15], where the dissolved slag copper content increased with increasing temperatures.…”

“…The copper recovery to the copper phases increases with decreasing temperatures, from 17.5 % in T1 to 51.2 % in T4. The literature revealed that copper solubility in slag increases with increasing temperatures [13,15]. Copper in the form of, e.g., copper oxide, cannot settle, as the copper phase is dissolved in the slag matrix.…”

“…Chemically dissolved copper associates with oxide (O 2− ) or sulfide (S 2− ) and is distributed within the slag matrix [13]. According to Zhao et al, copper cations can dissolve in fayalite [14], which is often the major phase of copper slag.…”

“…Currently, the correlation between copper solubility and temperature is under debate. Mackey has stated that oxidic copper solubility in general increases with an increase in the partial pressure of oxygen, and temperature [13]. In a thermodynamic assessment by Shishin et al, it was shown that the copper content in slag (Cu-Fe-O-S-Si system) is at its maximum at intermediate matte grades, then falls slightly and rises again when approaching 80 wt% copper in the matte.…”

Enhancing the flotation recovery of copper minerals in smelter slags from Namibia prior to disposal

“…% (Voijtech et al, 2009;Imris et al, 2000). According to Zander et al (2011), Jackman andHayward (1933), Mackey (1982) and Mihailova and Mehandjiev (2010), fayalitic slag generally contains up to 1 wt. % of copper as well as other valuable metals like nickel, cobalt and molybdenum.…”