Investigation of Copper Ammonia Leaching from Smelter Slags: Characterization, Leaching and Kinetics

Abstract

EHSAN BIDARI and VALEH AGHAZADEHAlthough ammonia leaching of copper from slags has been reported generally as a part of copper slag utilization methods, but no detailed studies have been reported in the literature. In this research, we tried to investigate the effect of different parameters on ammonia leaching of copper from copper smelting slag by identifying different copper-bearing phases and following them during leaching time. Mineralogical characterization of the smelting slag (1.7 pct Cu) was done using X-ray fluorescence, X-ray diffraction, optical microscopy, diagnostic leaching tests, and scanning electron microscopy. The characterization studies indicated that main copperbearing species are soluble copper oxides and chalcocite along with minor amount of covellite, bornite, blister copper particles, and chalcopyrite. It was also found that only approximately 0.2 pct Cu was present in the insoluble bulk silicate phases. These results suggest that approximately 88 pct of the total copper of slag could be extracted by ammonia sulfide leaching. Leaching tests were carried out and the effects of various parameters, namely pH, ammonia concentration, temperature, presence of oxygen, stirring speed, and pulp density were examined on copper leaching. The temperature and stirring speed had the most pronounced effect on the copper leaching, whereas ammonia affected the leaching yield at low concentrations of ammonia. It was found that 78 pct of Cu could be extracted within 4 hours and under optimum conditions: T = 343 K (70°C), 2M ammonia, pH 10.5, stirring speed = 900 rpm, pulp density = 10 pct (w s /v). The kinetic data were analyzed with the shrinking core models, and it was found that the leaching process is controlled by both the interfacial transfer and diffusion across the product layer and the activation energy is calculated to be 49.4 kJ mol À1 .

Intensifying separation of Pb and Sn from waste Pb-Sn alloy by ultrasound-assisted acid leaching: Selective dissolution and sonochemistry mechanism

“…In the diffusion control model, the stirring method has a remarkable effect on the reaction [36] , [37] . Due to the ultrasound cavitation effect, the ultrasound-assisted stirring has better dynamic conditions than that of the mechanical agitation in conventional leaching [38] . Ultrasound can destroy the reaction layer between solid and liquid, so ultrasound-assisted leaching has a large reaction rate constant.…”

Magnesium recovery from ferrochrome slag: kinetics and possible use in a circular economy

“…The chemical makeup of the chromite ore, feedstock, amount of ash in the coke, and other reducing agents used typically determine this, though ( Dube et al., 2018 ). As a result of its strength, durability, and chemistry, FCS is no longer seen as a waste residue merely to be discarded, but as a potential economic secondary source ( Binici and Aksogan, 2011 ; Bidari and Aghazadeh, 2015 ). Inherently, FCS has drawn interest in the fields of construction, glass ceramics, and recovery of valuable metals.…”

Dissolution of copper from smelting slag by leaching in chloride media

“…Most of the studies on the recovery of copper and other base metals from copper metallurgical slags have been conducted in acidic sulphate media, either in the absence or presence of an oxidant, in both atmospheric and pressure conditions [3][4][5][6][7][8][9]. In contrast, only a few papers have been published on the leaching of copper and other base metals from copper metallurgical slags in ammonia [7,8,10] and acidic chloride solutions [8,11]. However, chloride media are generally known to be more aggressive than sulphate media [12].…”