Extraction of Copper from Copper-Bearing Materials by Sulfation Roasting with SO2-O2 Gas

Abstract

Recycling metals from secondary materials and more complex ores has recently been attracting more attention, creating a need for more precise separation methods of different elements. This study proposed a sulfation-roasting method and designed thermodynamic conditions to selectively facilitate the formation of copper sulfate while separating iron as oxide. The roasting behaviors for chalcopyrite, copper slag, and pure copper compounds were investigated in a 0.5% SO2–0.5% O2–99% Ar atmosphere at 600°C. X-ray fluorescence spectroscopy, x-ray diffractometry, scanning electron microscopy, and energy dispersive x-ray spectrometry were used to characterize the raw materials and roasting products. The proposed methodology was confirmed for a complete separation of Cu from Fe, and, further, the sulfation-roasting mechanism of chalcopyrite was confirmed by thermodynamic calculations and experimental observations. These will provide a theoretical basis for copper recycling from both complex primary and secondary copper-bearing materials.

Copper Sulfation from Enargite Roasting Using Coal and Fayalite Slag Mixture

“…On the one hand, Ozer, M. et al studied the mechanism of the formation of copper and ferric sulfates utilizing a chalcopyrite concentrate and tailings in an oxidative atmosphere, with a temperature range of 773 to 953 K [11]. On the other hand, Wan, X. et al studied the chalcopyrite sulfation roasting behavior at 873 K with a SO 2 -O 2 gas mixture [12]. The reactions are the following.…”

“…One of the main minerals with a high content of arsenic in Chile is enargite (Cu 3 AsS 4 ), which, similar to most sulfides, is unstable in exogenous media and decomposes by roasting at high temperatures [2]. In 2001, Padilla et al [3] carried out the roasting of enargite in a neutral atmosphere utilizing nitrogen to determine the reaction mechanism and proposed that between 848 and 973 K, the decomposition occurs according to the following reactions: 4 Cu 3 AsS 4 (s) = Cu 12 As 4 S 13 (s) + 1.5 S 2 (g) (1) Cu 12 As 4 S 13 (s) = 6 Cu 2 S (s) + As 4 S 4 (g) + 3 S 2 (g) (2) In 2012, Padilla et al [4] again studied the roasting of enargite, but now in oxidative conditions and in a temperature range of 648 to 898 K. They proposed that it should be decomposed in the first step, forming tennantite (Cu 12 As 4 S 13 ) and sulfur dioxide gas (SO 2 ), Minerals 2023, 13, 1489 2 of 10 and it then oxidizes forming arsenic gas (As 4 O 6 ), sulfur dioxide gas and copper oxide (CuO), as represented in the following reactions: 4 Cu 3 AsS 4 (s) + 3 O 2 (g) = Cu 12 As 4 S 13 (s) + 3 SO 2 (g) (3) Cu 12 As 4 S 13 (s) + 10 O 2 (g) = 6 Cu 2 S (s) + As 4 O 6 (g) + 7 SO 2 (g) (4) 6 Cu 2 S (s) + 12 O 2 (g) = 12 CuO (s) + 6 SO 2 (g) (5) Nakazawa et al [5] studied the behavior of arsenic, simulating what would happen during the practical roasting of a copper concentrate, and stated that when hematite (Fe 2 O 3 ) is present, below 973 K, ferric arsenate will be formed (FeAsO 4 ), which could be a stable and nonvolatile compound of arsenic, as represented in Reaction (6).…”

A potential industrial waste–waste co-treatment process of utilizing waste SO2 gas and residue heat to recover Co, Ni, and Cu from copper smelting slag

“…According to the XRD analysis (Figure 1b) and microstructures (Figure 7b) of the untreated copper slag, the valuable metals Co and Ni mainly dissolved in the spinel phase as metal oxides or (Ni, Co, Fe) 3 •O 4 . During the smelting process, the majority of the copper dissolves in the slag by oxidic dissolution and mechanical matte dispersion loss (Genevski and Stefanova, 2008;Wan et al, 2020c). After the sulfation process at the designed atmosphere of this study, the spinel phase structure was destroyed and the valuable metals in the slag were converted to metal sulfates in the following steps (Me represents Cu, Co, Ni, or Fe).…”

Kinetics of solid-state oxidation of iron, copper and zinc sulfide mixture

“…An important aspect of the technology is the intensity of oxidative roasting of the copper ore, which determines the specific productivity of the fluidized bed furnace and temperature and duration of the process; for its evaluation, information on the chemistry, kinetics, and mechanism of roasting is needed. A lot of publications are devoted to these questions in relation to copper-nickel ores [14], copper [15][16][17][18][19][20][21][22][23][24][25][26][27], zinc [17,28,29], nickel [30,31], and copper-cobalt [32] concentrates, as well as individual sulfide minerals which are part of them: pyrite [33][34][35][36][37][38][39][40][41][42][43][44][45][46], marcasite [47], mackinawite [48], pyrrhotite [34,36,39,[49][50][51][52][53][54], chalcopyrite [36,47,…”