Reprocessing of copper by flotation via mineralogical characteristics from a copper slag case study

Innovative methodology for comprehensive and harmless utilization of waste copper slag via selective reduction-magnetic separation process

Recovery of valuable metal from copper electric furnace slag (CEFS) is of great interest for saving minerals and reducing pollution. XRF, XRD, mineral liberation analysis (MLA), and batch tests were conducted to investigate the mineralogical and recovery of copper and iron from CEFS. Based on the mineralogical characteristics, a flotation and magnetic combined process was proposed and evaluated for the recovery of copper and iron. The results show that copper in CEFS main distribute in chalcopyrite, copper matte, and bornite, while iron distribute in magnetite, fayalite, and pyroxene. The proposed process involves the recovery of iron via magnetic separation from flotation tailings after recovering copper from CEFS by flotation. 72.79% of copper and 20.41% of iron were recycled from CEFS where the grades of copper and iron concentrate were 19.86% and 50.69%, respectively. This is a significant finding. Engineering application clearly proved that recycling copper and iron from CEFS by this combined process has significant economic, social, and environmental benefit.

This study investigates the effects of sodium sulfate (Na2SO4) dosage, reaction temperature, and processing time on the structural decomposition of complex compounds in copper slag. Experimental results demonstrated that applying 20% Na2SO4 achieves an impressive decomposition rate of 89%, highlighting its effectiveness in liberating valuable metals from the slag matrix. The optimal temperature for maximizing fayalite decomposition is determined to be 900 °C, which significantly enhances reaction kinetics and efficiency. Furthermore, extending the reaction time to 90 min resulted in the highest observed decomposition efficiency. Subsequent leaching experiments in sulfuric acid confirmed that the liberated metal transitioned into the solution phase was very effective, ensuring high metal recovery rates. The treated samples demonstrated metal recovery rates of 97% for copper (Cu), 96% for iron (Fe), and 93% for zinc (Zn). In contrast, the untreated samples exhibited considerably lower recovery rates, with copper at 61%, iron at 59%, and zinc at 65%. Additionally, this approach mitigates filtration challenges by preventing the formation of silica gel. These findings provide key operational parameters for optimizing metal recovery from copper slag and establish a solid foundation for advancing sustainable and efficient resource extraction research.

Expansive soils have large volume changes due to the variation of water content. Therefore, expansive soils are also known as problematic soils due to its expansive nature. The black cotton soil has very low bearing capacity, high plasticity, high compressibility, low permeability and high swelling and shrinkage properties due to the presence of montmorillonite mineral. Due to these properties, black cotton soils are problematic soils. Therefore, it is necessary to improve its properties by using soil stabilization method. This study aims at conducting stabilization of black cotton soil of Bharuch region in Gujarat state by using combination of two soil stabilizing agents: copper slag and groundnut shell powder. In this research, copper slag is added 5% and 10% and groundnut shell powder is added 2% and 4%, respectively. The research gives comparison between the soil properties of non-treated and treated black cotton soil. Various laboratory tests are carried out such as specific gravity, liquid limit, plastic limit, shrinkage limit, free swell index, standard proctor compaction test, unconfined compressive strength test for both the cases by taking IS:2720 as reference. These laboratory tests results can be helpful to engineers to carry out soil stabilization on field during construction.

Thionocarbamates are the group of collectors that are mostly used for flotation of sulphide copper minerals, alone or in combination with xanthates depending on a mineralogical composition of the ore. In this paper, the results of the study of application of thionocarbamates in copper slag flotation are presented. Chemical analysis of smelter slag sample obtained from Flotation plant in Bor, Serbia, showed that it contains 3.56% of copper, of which over 73% is in the sulphide form, as well as 0.58 g/t of gold and 11.30 g/t of silver. XRD analysis identified fayalite and magnetite as main minerals present in the slag and SEM-EDS analysis showed that copper is mainly present in the form of sulphide minerals, thus making it suitable for flotation with thionocarbamates. Two thionocarbamates MX 980 and TC 1000 and one xanthate SIPX, along with their mixtures MX 980 + SIPX and TC 1000 + SIPX, were investigated. The influence of parameters such as collector type and dosage, grinding fineness, pulps’ pH and flotation time, on flotation indicators (recovery, yield and copper grade in concentrate) were determined. Smaller dosages of thionocarbamates (40 g/t) provided concentrates with high copper grades, 22.34% (MX 980) and 18.42% (TC 1000) and lower recovery rates, 83.98% (MX 980) and 87.78% (TC 1000), while the increase of dosages to 200 g/t led to the increase of recovery rates for more than 4% and a significant decrease in copper grades. The increase of grinding fineness from 50% to 70% of grain size < 0.074 mm showed a positive impact on flotation indicators, recovery rate, copper grade and yield, for all investigated collectors and their mixtures, while, with the further increase from 70% to 90%, recovery rates continued to increase while copper grades decreased. The increase of pulps’ pH had a positive influence, especially for MX 980, for which recovery rates increased with the increase of pH from 8 to 10 (12). A flotation kinetics test showed that flotation with TC 1000 was the fastest, i.e., recovery rate after 20 min of flotation was over 91%, while recoveries obtained with other collectors were a few percentage points lower.

Synergetic utilization of copper slag and ferruginous manganese ore via co-reduction followed by magnetic separation process

Copper slag, a by-product of the pyrometallurgical process, used for obtaining copper from the copper ore in Bor, is disposed on the landfills. Despite favorable technical properties, the copper slag aggregates possess such resistance to the crushing (12.76 %) and higher particle density (3.33Mg/m3 ); its use in the construction industry is not sufficiently examined. The experiments included tests on three concrete mixtures with a partial replacement of coarse natural aggregate with the copper slag. Replacement of the RA particle size 8/16 mm and 16/31.5 mm, with the CSA in the amount of 2 0+20% and 20+50%, resulted in an increase in the compressive strength of 10.2% and 12.6%, respectively. Increase of the CSA content in the amount of 20+20% and 20+50%, led to increase in tensile strength by 6.2% and 22.1%, respectively.

Recovery of high-grade copper matte by selective sulfurization of CuO–Fe2O3–SiO2–CaO system

Investigation of converter copper slag reduction using spent cathode carbon as a reductant

The copper smelting process produces plenty of copper slag every year, which is a hazardous solid waste, but a secondary resource. In the present study, the extraction of copper, nickel, and cobalt from copper slag was investigated through the process of sulfation roasting–water leaching and the process of sulfation roasting–sulfate decomposition roasting–water leaching respectively. Compared with the process of sulfation roasting–water leaching, the process of sulfation roasting–sulfate decomposition roasting–water leaching is a better choice, which could not only get almost the same leaching of copper, nickel, and cobalt as the former process, but has a lower leaching of iron and aluminum. For the process of sulfation roasting–sulfate decomposition roasting–water leaching, the leaching of Cu, Ni, and Co reached up to 74.2%, 71.1%, and 69.6% respectively, under the optimal conditions including sulfation roasted with 80 wt% sulfuric acid addition at 200 °C for 60 min and sulfate decomposition roasted at 650 °C for 60 min, followed by water leached at 90 °C for 30 min with a liquid–solid ratio of 2 ml/g. The leaching of Fe and Al was only 4.9% and 17.6%.

Evaluation of thermal and energy consumption behavior of novel foamed copper slag based geopolymer masonry blocks

Based on index properties in laboratory testing, foundry sand, and blast furnace steel slag may be considered as a construction backfill alternative. Naturally available granular materials for various fill applications are fast dwindling and sometimes not readily available near every construction site. In the current scenario, there is a substantial need to use alternative geomaterials. Many industry by-products and waste materials [fly ash, copper slag, bottom ash, construction, and demolition wastes (C&D), etc.] have been extensively studied for their suitability as a geomaterial. Steel slag generation in the world was estimated to be in the range of 170-250 MT in 2015, and considerable amounts of waste foundry sand are also generated. In the present study, waste foundry sand from Ordnance Factory, Medak, India, and blast furnace (BF) steel slag from Tata Steel, Jamshedpur, India, are tested for basic characteristics including gradation, specific gravity, morphology, chemical composition, and compaction. The engineering properties, shear strength, and permeability, are evaluated. In addition, leachate studies are conducted to assess the environmental impact of use of these materials for the proposed applications. Compaction behaviour of both the materials is found to be similar to granular soils. Foundry sand and BF steel slag exhibited an angle of shearing resistance of 31 0 and 37 0 , respectively. A comparative study on the properties of foundry sand and BF steel slag with the conventional fill material is performed, and the two waste products considered in the study are assessed for fill applications.

Co-treatment of spent carbon anode and copper slag for reuse and the solidification of the constituent fluorine and heavy metals

Cement-based biocide coatings for controlling algal growth in water distribution canals

Copper and cobalt are essential metals for the transition to renewable energy and various aspects of modern life. Their extraction from primary sources, such as ores, requires metallurgical separation from unwanted host materials, generating a substantial amount of waste. One type of this waste is copper smelting slag, with 39 million tonnes produced and discarded globally each year. These large quantities of slag occupy significant land space, often near residential areas, and pose a potential hazard by releasing contaminants into the environment. However, they also contain residual amounts of valuable copper and cobalt. To address the challenge of mitigating the negative impacts of this waste and exploring the potential commercial opportunities of the contained critical minerals, this study reviews global smelting slag production over the past 25 years, as well as the composition and technical reprocessing options. It provides a summary of the chemical and mineralogical characteristics of copper slag from various research and an extensive overview of the processing strategies for metal recovery from copper slag, including flotation, pyrometallurgy, and hydrometallurgy. The study demonstrates that a significant amount of smelting slag has been produced with considerable variation and complexity, representing a major potential resource for cobalt and copper metals. The overview of production trends and reprocessing techniques shows that while some effective options exist or are emerging, further research is required to enhance the reprocessing of smelting slag waste to create economic value, improve energy efficiency in metal production, increase the supply of critical metals, and reduce environmental impacts.