Environmental and Socioeconomic Impact of Copper Slag—A Review

Gabasiane, Tlotlo Solomon; Danha, Gwiranai; Mamvura, Tirivaviri A.; Mashifana, Tebogo; Dzinomwa, Godfrey

doi:10.3390/cryst11121504

Cited by 34 publications

(12 citation statements)

References 81 publications

(104 reference statements)

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“…Approximately 2 tons of slag per tonne of copper produced is generated in a typical pyrometallurgical process [ 6 , 7 , 18 ]. Environmental and socio-economic impacts of such slags are some compelling considerations in favour of further recovery of valuable metals [ 19 , 20 ]. The composition of the slag is dependent on the mineralogy of the ore, but it typically contains oxides of gangue elements such as iron, silicon, magnesium, calcium, phosphorus, and copper [ 21 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Mineralogical Characterization of Historic Copper Slag to Guide the Recovery of Valuable Metals: A Namibian Case Study

Dzinomwa,

Mapani,

Nghipulile

et al. 2023

Materials

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The depletion of the ore reserves in the world necessitates the search for secondary sources such as waste products (tailings and slag). The treatment and cleaning up of such secondary sources also has a positive impact on the environment. A smelter in Namibia we examined had historic slag which accumulated over decades of its operating life, thus posing the challenge of how best to collect representative samples to evaluate and propose viable methods of recovering contained metals. In this study, analytical and mineralogical characterization of the slag was performed using X-ray fluorescence (XRF) analysis, atomic absorption spectrometer (AAS), ICP-OES, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, and optical microscopy analysis. The chemical analyses showed that the metal values contained in the slag were mainly copper, lead, and zinc whose average contents were approximately 0.35% Cu, 3% Pb, and 5.5% Zn. About 10.5% Fe was also contained in the slag. Germanium was detected by scanning electron microscopy, but was however below detection limits of the chemical analysis equipment used. Based on the results, approximate conditions under which the different slag phases were formed were estimated and the recovery routes for the various metals were proposed. Analysis by both optical and scanning electron microscopy revealed that Zn and Fe occurred mainly in association with O as oxides, while Cu and Pb were mainly associated with S as sulphides. The slag consisted of three different phases, namely the silicate phase (slag), metallic phase and the sulphide phases. The phases in the slag were mainly silicate phases as well as metallic and sulphide phases. It was observed that the metallic and sulphide phases were dominant in the finer size fractions (−75 µm) whereas the sulphide phase was also present in the coarser size fractions (+300 µm). An important finding from the microscopy examination was that the sulphide phases were interstitial and could be liberated from the slag. This finding meant that liberation and subsequent concentration of the sulphide phases was feasible using conventional processing techniques.

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Section: Introductionmentioning

confidence: 99%

Mineralogical Characterization of Historic Copper Slag to Guide the Recovery of Valuable Metals: A Namibian Case Study

Dzinomwa,

Mapani,

Nghipulile

et al. 2023

Materials

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“…With the economy’s rapid development, people’s desire for copper resources has become unprecedented [ 2 ]. However, the massive buildup of copper slag caused by the low grade of copper ore has presented significant environmental and solid waste management difficulties [ 3 , 4 ]. The rational resource utilization of copper slag, thus achieving environmental protection and clean production of copper is imminent [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of CaO on Physical and Environmental Properties of Granulated Copper Slag: Melting Behavior, Grindability and Leaching Behavior

Sun

Feng

Wang

et al. 2022

IJERPH

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Due to its potential pozzolanic activity, granulated copper slag (GCS) has been proven to act as a supplementary cementitious material (SCM) after thermochemical modification with CaO. This modification method reduces cement consumption and CO2 emissions; however, the additional energy consumption and environmental properties are also not negligible. This paper aims to evaluate the economics and environmental properties of thermochemically modified GCS with CaO through the melting temperature, grindability, and heavy metal leaching characteristics. The X-ray fluorescence spectroscopy (XRF) results indicated that the composition of the modified GCS shifted to the field close to that of class C fly ash (FA-C) in the CaO-SiO2-Al2O3 ternary phase diagram, demonstrating higher pozzolanic activity. The test results on melting behavior and grindability revealed that adding CaO in amounts ranging from 5 wt% to 20 wt% decreased the melting temperature while increasing the BET surface area, thus significantly improving the thermochemical modification’s economics. The unconfined compressive strength (UCS) of the cement paste blended with 20 wt% CaO added to the modified GCS after curing reached 17.3, 33.6, and 42.9 MPa after curing for 7, 28, and 90 d, respectively. It even exceeded that of Portland cement paste at 28 d and 90 d curings. The leaching results of blended cement proved that the heavy metal elements showed different trends with increased CaO content in modified GCS, but none exceeded the limit values. This paper provides a valuable reference for evaluating thermochemically modified GCS’s economics and environmental properties for use as SCM.

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“…It has been estimated that for every ton of copper produced, approximately 2.2–2.5 tons of slag is generated as a result of the relatively low grades of copper concentrates now available . There are several copper smelting plants throughout the world, and this has resulted in the production of approximately 40 million tons per year of slag, which is regarded as waste. − This slag is generally disposed of near smelter sites. , Although the properties of copper slag in flash smelting, reverberatory furnace smelting, and other processes are generally similar, these slags can have different characteristics depending on how they are cooled from the smelter . When copper slag is crystalline, the major phases are usually fayalite (Fe 2 SiO 4 ), along with other silicates.…”

Section: Introductionmentioning

confidence: 99%

“… 6 , 7 Although the properties of copper slag in flash smelting, reverberatory furnace smelting, and other processes are generally similar, these slags can have different characteristics depending on how they are cooled from the smelter. 8 When copper slag is crystalline, the major phases are usually fayalite (Fe 2 SiO 4 ), along with other silicates. However, copper-containing phases in slag can differ, and they may be in the form of oxides, sulfides, 6 or a mixture of both.…”

Section: Introductionmentioning

confidence: 99%

Pressure Leaching of Copper Slag Flotation Tailings in Oxygenated Sulfuric Acid Media

Seyrankaya

2022

ACS Omega

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In this study, a hydrometallurgical method for the recovery of copper, cobalt, and zinc from copper slag flotation tailings (SFT) was investigated. SFT contains large amounts of valuable metallic compounds, such as copper, cobalt, and zinc. A representative SFT sample containing 0.50% Cu, 0.148% Co, 3.93% Zn, and 39.50% Fe was used in experimental studies. High-pressure oxidative acid leaching of SFT was carried out to assess the effects of sulfuric acid concentration, oxygen partial pressure, reaction time, solid/liquid ratio, and temperature on the extraction of copper, cobalt, zinc, and iron. The dissolution of metals from the SFT sample increased with temperature and sulfuric acid concentration. However, high acid concentrations and high solid/liquid (S/L) ratios led to gel formation that caused filtration problems and inhibited metal dissolution. The optimum leaching conditions were found to be a leaching time of 90 min, an acid concentration of 250 kg/t, a temperature of 220 °C, an S/L ratio of 1:5, and an oxygen partial pressure of 0.7 MPa. Under these conditions, 93.1 ± 1.1% Cu, 96.3 ± 1.8% Co, and 92.3 ± 1.7% Zn were extracted. Iron dissolution was only 0.5 ± 0.1%. This hydrometallurgical process almost completely recovers valuable metals. In particular, cobalt, which is of great importance in the production of lithium-ion batteries, has been declared a critical metal by the United States, Canada, and the EU and was taken into solution with very high extraction efficiency (>95%). Additionally, oxygen partial pressure enhanced copper, cobalt, and zinc dissolution. When O2 was not introduced into the leaching system, the extraction efficiencies of Co, Cu, and Zn were approximately 24.5, 5.3, and 26.3%, respectively, after 2 h of leaching treatment.

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Environmental and Socioeconomic Impact of Copper Slag—A Review

Cited by 34 publications

References 81 publications

Mineralogical Characterization of Historic Copper Slag to Guide the Recovery of Valuable Metals: A Namibian Case Study

Mineralogical Characterization of Historic Copper Slag to Guide the Recovery of Valuable Metals: A Namibian Case Study

Influence of CaO on Physical and Environmental Properties of Granulated Copper Slag: Melting Behavior, Grindability and Leaching Behavior

Pressure Leaching of Copper Slag Flotation Tailings in Oxygenated Sulfuric Acid Media

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