Copper Smelting Slag Research Articles

Complex Processing of Copper Smelting Slags with Obtaining of Cast Iron Grinding Media and Proppants


 
 
 The Ural region has a large number of metallurgical companies. The extraction of metals from ore is always accompanied by the accumulation of wastes. Currently, most of the wastes are stored in dumps and storage facilities forming technogenic deposits. One such that occupies huge areas is copper slag from the copper-smelting production. According to current estimations, about 2.2 tons of slag is formed for each ton of copper produced and about 24 million tons are produced annually [1]. In general, a copper slag contains about 35-45% iron and 0.4-0.5 copper, which indicates that this is a valuable secondary resource for recycling and utilization [33]. However, more than 80% of copper slag is not utilized, which makes it possible to consider this waste not only as a valuable material, but also as a potential hazard for the environment; it contaminates the soil and water with heavy elements [8]. Currently, only small amounts of the waste are recycled. In addition, technologies do not allow the complete extraction of valuable elements. This offers potential for the development of new highly efficient technologies for processing copper smelting wastes with extraction of valuable elements such as iron (Fe). Improvement of Fe quality requires a decrease in non-ferrous metal content, especially Cu. In recent years, extensive research was directed at the extraction of valuable materials from copper slags by high-temperature firing of copper conglomerates with subsequent magnetic separation or leaching of non-ferrous metals. However, these studies do not allow the complete processing of copper smelting slags. This work studies the production of iron-containing briquettes from copper-smelting slags, and their subsequent processing to obtain valuable products for metallurgical and oil companies.
 Keywords: briquette, reduction, cast iron, proppants
 
 

Processing of Anthropogenic Waste of Smelters of the Ural Mining and Metallurgical Company


 
 
 The industrial sites of the smelters of the Ural Mining and Metallurgical Company have accumulated a lot of anthropogenic waste, the processing of which is currently economically impractical. These primarily include tailings and beneficiation tailings, as well as waste granulated and copper smelting slag. This article conducts studies on technologies for x-ray-radiometric/magnetic separation enrichment of discard slags of MMSK as well as using jigging machines. Slag and slag enrichment tailings are used for cement production and road construction. For complex processing of fine copper smelting dusts OJSC Chelyabinsk zinc plant developed, tested and implemented a special technology. After implementation of ”Actions to process industrial waste generated by UMMC enterprises at metallurgical enterprises of UMMC-Holding Corp.”, the following were noted: concentrators and special beneficiation facilities process slag; R&D on complete processing of concentrator’s tailings was conducted; smelting dust was not stored but processed in full; the technology of implementing Waelz process for processing of steel smelting dust has been developed and commercially tested; the technology for extraction of copper and precious metals from pyrite dross is to be improved.
 
 
 
 Keywords: anthropogenic waste, dust, tailings, slag, pyrite dross
 
 
 
 
 

Simultaneous NOx and SO2 removal during wet flue gas desulfurization, using copper smelter slag slurry combined with yellow phorphorus

AbstractThe study of copper slag has attracted the attention of scholars from both China and around the world. But few have paid attention to its applications in the simultaneous removal of SO2 and NOx in wet flue gas desulfurization (WFGD), becasue WFGD technique is inappropriate for directly treating NOx owing to the low solubility of NO. This work aims to improve NOx removal efficiency in WFGD technology using copper slag slurry associated with the oxidation of NOx by yellow phosphorus. Different operating conditions, including dispersion of P4, solid‐liquid ratio, initial pH value of copper slag slurry, reaction temperature, oxygen content, and gas flow rate, were compared regarding the efficiency of SO2 and NOx simultaneous removal. The characterizations were carried out on the liquid and solid part of fresh and spent copper slag slurry after filtration. The results indicated that a great amount of metals ions, such as Fe3+ and Zn2+, were leached by reacting with produced acids (H2SO4, HNO3, and H3PO4), which had a liquid‐phase catalytic oxidation on SIV species (SO32−/HSO3−), leading to promotion in absorption for SO2. The copper slag played a significant role in dispersing the yellow phosphorus and promoting ozone generation, thus improving NOx removal efficiency. The reaction pathway can be divided into three parts: (a) ozone generation induced by yellow phosphorus, (b) the oxidation of NO by O3 and then dissolution in aqueous solution, and (c) the dissolution of SO2 and the liquid‐phase oxidation for SO2 through metal ions produced by the reaction between acid and copper slag.

Leachate and contact test with Lepidium sativum L. to assess the phytotoxicity of waste

The study evaluated the use of Lepidium sativum L. to assess the phytotoxicity of three types of waste such as hazardous waste (slags from zinc to copper smelters) and nonhazardous waste (mineral–organic composite). Previous studies evaluated heavy metal leaching and the environmental impact of the tested waste. The purpose of phytotoxicity studies was to increase knowledge about this waste. Two types of tests were used to assess the phytotoxicity of wastes: germination index and accumulation test. Both tests were carried out for leachate (leachate test) and waste (contact test). The results of both tests were compared to assess the phytotoxic effects of tested waste. Phytotoxicity tests have shown that the mineral–organic composite leachate was stimulated plant growth, copper smelter slag leachate was characterized by no phytotoxicity and zinc slag leachate inhibited the growth of plants. In contrast, contact test showed inhibitory effects from all tested waste. Wherefore, the contact test was indicated as more sensitive in the assessment of phytotoxicity. However, this is not a clear assessment, because the germination index values for both tests were a result of differences of root length for both control samples (deionized water and sand). The study confirmed the usefulness of L. sativum for the assessment of phytotoxicity of various types of waste. Additionally, it was found that L. sativum was resistant to high concentrations of heavy metals in the leachate, without causing any negative physiological effects.

Copper Smelting Slag Cleaning in an Electric Furnace by Using Waste Cooking Oil

In view of the non-renewable reductant resources and carbon neutralization in the process of copper slag cleaning in an electric furnace, this study proposed to use waste cooking oil as reductant to replace fossil energy. Combined with the phase equilibrium theory and experimental results, the harm of excessive magnetite in the copper smelting slag to the cleaning process was clarified. The reduction thermodynamics of magnetite by using WCO is analyzed. A series of copper slag cleaning experiments with different WCO dosages along with various temperatures and settling durations was systematically carried out in a laboratory-scale electric furnace. The distribution of matte particles in each slag layer after cleaning was investigated in detail, which indicates that the copper content in the upper slag layer can be reduced to 0.56 wt pct via WCO reduction, realizing the green cleaning of copper slag.

Ferro-silico-manganese production from manganese ore and copper smelting slag

Utilization of smelter by-products, such as metal scrap, slag, flue-dust, and other residues, is necessary if the goal of zero waste in metal production is to be achieved. One of the possible utilizations of the by-products is by using them as raw materials for the production of commercial metals or alloys. Laboratory experiments of the production of ferro-silico-manganese alloy using manganese ore and copper smelting slag as raw materials were carried out in the present study. Manganese ore and different amounts of copper smelting slag were reduced by bituminous coal at final holding temperatures of 1450, 1500 and 1550 °C. The equilibrium compositions and phases were predicted by FactSage thermodynamic software and were used to assist the analysis of the present experimental results. The influences of temperature and the addition of copper smelting slag on the metal product size, total metal recovery, metal composition, and recoveries of elements in the metal product were determined. The final slag obtained from the reduction process were also characterized. The present study demonstrates the possibility of producing ferro-silico-manganese by utilizing manganese ore and copper smelting slag as raw materials.

Reduction of Magnetite from Copper Smelting Slag in the Presence of a Graphite Rod

Through the reduction reaction of Fe3O4 and graphite rod, the viscosity of slag was reduced and the settlement of matte in slag was promoted. The reduction of Fe3O4 in copper slag by a graphite rod was studied and the kinetics of the reduction process analyzed. The results show that the content of Fe3O4 decreased with increase in reduction temperature and reduction time. The slag samples after reduction were examined and found to consist of three layers: a slag foam layer, a fayalite layer, and a matte layer. A substantial number of large-sized matte particles were found in the slag foam layer. Also, a layer of Fe3O4 was attached to the upper surface of the matte layer. The reduction of Fe3O4 was concluded to be a second-order reaction, the apparent activation energy was 610 kJ/mol, and the limiting step was the Boudouard reaction.

Experimental study on the separation of a shrend copper slag

An experimental study on copper separation from a shrend copper slag in Yunnan province was carried out. The test contents included: grinding curve test, grinding process determination test, comparison tests of different flotation processes. The results shown that: the main ingredients of shrend copper slag were iron, silicon and the main valuable metallic elements were Cu, Fe, grade of 0.70%, 40.14%, consistent with the main components of the copper smelting slag. When the grinding time exceeded 35 minutes, the grinding fineness curve tended to flatten, indicating that the grinding effect was not obvious after the time exceeded 35 minutes, and the grinding fineness did not change much, which may be the shrend copper slag crystallized into a dense structure during the cooling process. Finally, the two stages grinding and regrinding process was adopted. Under the fineness of -0.074 mm 70% on the first grinding, the fineness of -0.037 mm 100% on the second grinding, and the fineness of -0.026 mm 85% on the regrinding, the process of regrinding and recleaning for combined cleaning middling of sulfide copper with roughing and scavenging middling of oxidized copper was suitable for the shrend copper slag.

Removal of Arsenic During Iron Extraction from Waste Copper Slag

Substantial quantities of openly dumped slag contribute to the absence of recovery and utilization of valuable metals as well as potential environmental pollution to water and soil. Owing to the excessively high arsenic content present in iron extracted from copper smelting slag, we propose a new arsenic removal process in this paper. The results indicate that arsenic sulfides in copper smelting slag can be significantly removed at 1100 °C in an N2 atmosphere, leading to a 0.15% residual arsenic content. Furthermore, undecomposed arsenate in the slag can be reduced in an N2–CO atmosphere. During a coal-based direct reduction process, under optimal conditions, the removal efficiency of arsenic is relatively low. Subsequently, under optimal conditions, the arsenic content drops significantly from 0.18 to 0.080%. This new removal process engenders lower arsenic content in iron extracted from slag than the standards of pig iron and direct reduced iron in steelmaking.

A novel strategy for harmlessness and reduction of copper smelting slags by alkali disaggregation of fayalite (Fe2SiO4) coupling with acid leaching

Copper smelting slags are difficult to achieve harmlessness and reduction because of the presence of abundant of fayalite (Fe2SiO4). This work proposed a novel strategy for harmlessness and reduction of copper smelting slags by alkali disaggregation of Fe2SiO4 coupling with acid leaching. The disaggregation changed the Fe2SiO4 phase by NaOH and released the embedded harmful and valuable metals. The evaluation of disaggregation effect mainly depends on further acid treatment. Especially the total leaching efficiency of As, Zn, Fe, Cu and Pb was achieved 99.7%, 62.5%, 41.5%, 99.9% and 99.1% under diluted HNO3-H2O2 system, respectively. Compared with the non-disaggregated control, the efficiency was accordingly increased by 73.3%, 71.1%, 18.6%, 72.2% and 22.4%. Meanwhile, the content of As, Cu and Pb in the slags decreased from 1165.5 mg/kg, 30085.9 mg/kg and 5008.8 mg/kg to as low as 5.2 mg/kg, 21.2 mg/kg and 15.6 mg/kg, respectively. Interestingly, the strategy brought out 48.1% of the weight reduction of the copper smelting slags. The favorable effect was mainly attributed to the broken of Fe-O-Si bond thereafter improving the acid leaching activation. Therefore, the proposed strategy could potentially be a new method to realize harmlessness and reduction of copper smelting slags.

Element mobility from the copper smelting slag recycling waste into forest soils of the taiga in Middle Urals.

The article presents the results of assessing the element mobility (chemical elements and compounds) from the copper smelting slag recycling waste into brown forest soils (Haplic Cambisols) of the southern taiga district in Middle Urals, Russia. The copper smelting slag recycling waste was obtained by crushing the cast slag of the Sredneuralskiy Smelter ("technical sand") followed by flotation extraction of copper concentrate. The investigations were carried out in two forest types, distinguished according to the principles of the genetic forest typology, cowberry shrub pine forest and berry pine forest with linden, and the corresponding clear-cuttings. We conducted the experiment in the autumn before the snow cover was established in two variants: (i) we evenly scattered 1 kg of waste on meter sample plots; (ii) we weighed the "technical sand" by 100 g, packed it in non-woven material and buried it in the soil to a depth of 7-10 cm. Two years later, we dug up the bags with waste and weighed them. The analyses were performed by inductively coupled plasma mass spectrometry using Elan-9000 ICP mass spectrometer. As a result of the research, it was found that waste loses 11% mass over 2 years of being in forest soils. The content of Zn, As, Cd, and Se changes most strongly. The difference in the degree of element migration from the "technical sand" to the brown forest soils of the two forest types and clear-cuttings was revealed. The study of the effect of technogenic waste on the dominant and diagnostic species of grassy vegetation in the selected forest ecosystems of the Middle Urals was carried out. There was no negative effect on the qualitative composition of the grassy layer of two forest types and their clear-cuttings after 1 year after a single surface application of mineral waste at a concentration of 1 kg/m2.

Mineralogical and morphological factors affecting the separation of copper and arsenic in flash copper smelting slag flotation beneficiation process

Separating copper and arsenic has always been a major problem in the copper slag flotation process, which influences copper slag utilization and the environmental safety. A comparative study of flash smelting furnace (FSF) slag and its flotation products (concentrate and tailing) reveals the factors affecting the separation of copper and arsenic in the beneficiation process from the perspective of mineralogy and morphology. The elemental fractionation in the process shows a positive correlation of As, Cu and Cd and an obvious correlation between speciation transformation of copper and arsenic was observed. The occurrence of arsenic and copper in FSF slag correlate the key phases of arsenic copper alloys, accounted for 88.91 % of total arsenic-bearing phases and 32.28% of copper-bearing phases. Closely-embeded matte and copper-arsenic alloys incerease the difficulty of the separation suggesting the finer grinding is needed for slag. Arsenic is liberated and oxidized into arsenate compounds while the recombination of As-O and Cu-S happened in the process affecting the selectivity of copper and arsenic. Arsenic fixed in silicate minerals is discharged into tailing which suggested to induce and fix arsenic into silicate minerals can facilitate arsenic removal from concentrate. FSF slag and its flotation concnetrate show risks of some of some of HMs which should be cautiously transported, disposed, and utilized.

Environmental geochemistry of the copper slag old dump in the Middle Urals

Relevance of the work. Wastes from mining and processing industries occupy vast areas and cause serious environmental damage. The research results will contribute to the development of biological reclamation of industrial areas and environmental monitoring. Purpose of the work: study of the geochemical features of soils and plants formed on old slags of the Polevsky copper smelter (Middle Urals). Methods of the study. We laid the plot in the relatively flat section of the base of the steep slope of the dump. Complex samples were taken at equal intervals on the transect and included blocks of technogenic soil along with growing plants. The material of the complex sample was divided into fractions by nature (soil, plants) and by size of fragments of copper smelting slag, dried to air-dry state and weighed. The chemical composition of the samples was determined by inductively coupled plasma mass spectrometry. Results. The man-made soil with a thickness of 10–15 cm has formed on the cast copper smelting slag old dump. More than a third of its mass is fine soil (particles less than 1 mm), which is a sorption geochemical barrier. The most elements concentration in fine soil is 1–2 orders of magnitude higher than their concentration in slag stone. Lead, cadmium, bismuth are especially effectively delayed. In the fine soil, the strongest excesses of the maximum permissible concentrations for all regulated elements have been established. It has been confirmed that under unlimited supply conditions of elements migration from slag, plant has an upper accumulation threshold. For the aboveground plant parts, the highest values of the biological absorption coefficient were found for selenium, potassium, calcium, and phosphorus. Conclusions. An environmental assessment of the Polevsky smelter (Middle Urals) old dump was carried out, the geochemical features of the soil and plants were investigated.

Phosphorus removal from secondary wastewater effluent using copper smelter slag

This study investigated the use of copper smelter slag for the removal of phosphorus from secondary wastewater effluent through batch tests. The media was physically and chemically characterized and showed presence of Fe2O3 (45.22%), SiO2 (14.98%), Al2O3 (3.21%), CaO (1.99%), SO3 (1.77%) and MgO (1.33%). Scanning electron microscopy monographs revealed smooth and flat surface and no heterogeneity on the surface of the slag with visible micro pores before the experiment and less visible after the experiment. The point of zero charge of the media was 5.0. Equilibrium was reached after 4 h at 29.5 ± 0.71% phosphorus removal efficiency and media dosage of 0.4/100 mL. The kinetic data was best described by Pseudo second order equation. More than one mechanisms were involved in the adsorption of phosphorus onto copper smelter slag as suggested by multi-linearity of intra particle diffusion model. Ninety seven percent (97.5 ± 0.0%) removal efficiency was achieved at an equilibrium dosage of 160 gL-1. The equilibrium isotherm was described better by Langmuir equation with observed maximum adsorption capacity of 0.16 mg P g−1 media and the experimental maximum adsorption capacity was 0.26 mg P g−1 media. Regeneration studies showed low performance with maximum efficiency of 11.7% revealed during the first regeneration trial therefore low practical benefits. Copper smelter slag is a poor adsorbent for phosphorus and further studies on the media should be conducted.

A Method of High-quality Silica Preparation from Copper Smelting Slag

High-quality silica was prepared from copper smelting slag through a method of in situ modification. The effects of the addition of an amount of polyethylene glycol-6000 as a modifier, the modification temperature and the modified endpoint pH on the particle size and specific surface area of the silica were systematically studied. It has been shown that the particle size, specific surface area, and the interstices between the particles were greatly affected by the modification temperature and the pH of the modification endpoint. Optimal conditions are: modifier 10% as solute mass, modification temperature 40°C, and pH of modification endpoint 8.5. Under these conditions, the silicon sinking rate was as high as 97.82%, the prepared silica particles had good dispersibility, the average particle size was 20 nm, the particle morphology was spherical, and the specific surface area was as high as 244.67 m2/g, which was superior to A-grade standard of HG/T3061-1999 and ISO 5794-1:2005(E), and could be directly used in the rubber industry.

Технологические возможности металлургической переработки промпродуктов обогащения полиметаллических руд и обеднения шлаков медеплавильного производства в агрегате «Победа»

Технологические возможности металлургической переработки промпродуктов обогащения полиметаллических руд и обеднения шлаков медеплавильного производства в агрегате «Победа»

A Study on Reduction of Copper Smelting Slag by Carbon for Recycling into Metal Values and Cement Raw Material

Copper smelting slag is a solution of molten oxides created during the copper smelting and refining process, and about 1.5 million tons of copper slag are generated annually in Korea. The oxides in copper smelting slag include ferrous (FeO), ferric oxide (Fe2O3), silica (SiO2 from flux), alumina (AI2O3), calcia (CaO) and magnesia (MgO). The main oxides in copper slag, which are iron oxide and silica, exist in the form of fayalite (2FeO·SiO2). Since copper smelting slag contains high content of iron, and copper and zinc, common applications of copper smelting slag can be used in value-added products such as abrasive tools, roofing granules, road-base construction, railroad ballast, fine aggregate in concrete, etc. Some studies have attempted to recover metal values from copper slag. This research was intended to recover ferrous alloy contained Cu, a raw material of zinc, from copper slag, and produce reformed slag such as blast furnace slag for Portland cement. As a result, it was confirmed that with reduction smelting by carbon at temperatures above 1400 °C, it is possible to recover pig iron containing copper from copper smelting slag, and the addition of CaO in reduction smelting helped to reduce iron oxide in the fayalite and change the chemical and mineralogical composition of the slag. The copper oxide in the slag can be easily reduced and dissolved in the molten pig iron, and zinc oxide is also reduced to a volatile zinc, which is removed from the furnace as fumes, by carbon during the reduction process. When CaO addition is above 5%, acid slag is completely transformed into calcium silicate slag and is observed to be like blast furnace slag.

Kinetics of copper extraction from copper smelting slag by pressure oxidative leaching with sulfuric acid

The accumulation of copper smelting slag not only pollutes the environment but also wastes resources, using oxygen pressure acid leaching process to treat copper slag has incomparable advantages over other processes, but there are few researches reported at home and abroad. In this paper, copper slag was treated by this process. Under the premise of fully studying the influence of various factors on copper dissolution, the selective leaching behavior and kinetics of copper oxy-pressure acid system in copper slag were expounded. The experimental results showed that the dissolution kinetics analysis of the experimental data based on the shrinking core model for various conditions indicated that the reaction rate of leaching was mainly controlled by the chemical reaction during its early stages, then switched to be controlled by mixed chemical-reaction and product-layer diffusion which could be ignored because of its short lifetime, and finally was controlled solely by diffusion through a surface product layer in the later stage. The activation energy was calculated to be 47.03 kJ·mol/L in the early surface chemical reaction controlling stage and 11.35 kJ·mol/L in the later diffusion controlling stage, respectively. The leaching rate of copper is mainly determined by the chemical reaction control stage, in which the reaction orders of sulfuric acid concentration, oxygen partial pressure and particle size are 0.83, 0.92 and −1, respectively.

Microstructural and chemical characterization of stabilized spent vanadium pentoxide catalyst in copper smelting slag

The purpose of this research is to perform a microstructural characterization of the stabilized spent vanadium pentoxide (V2O5) catalyst in the copper smelter slag. The spent V2O5 catalyst (SVC) is a discarded material from a sulfuric acid production plant. The used SVC is a catalyst material supported in SiO2. The used copper smelting slag (CSS) was from a copper refining mine. The toxic V2O5 compound present in the SVC was stabilized via pyrometallurgical processing with the CSS in an electric furnace with a CSS/SVC 4:1 ratio at 1250 °C to obtain a fused compound. The microstructural and chemical characterization of the CSS, SVC used materials and the obtained fused compound, were performed by scanning electron microscopy (SEM) coupled and Energy dispersed X-ray analyser (EDS), X-ray powder diffraction (XRD) and Differential Thermal Analyser (DTA-TGA). The fused compound was a complex slag that comprised of Fe2SiO4 and FeVO4 phases.

Decomposition of Methylene Blue by Fenton–like Reaction Catalyzed by Copper Smelter Slag

Decomposition of Methylene Blue by Fenton–like Reaction Catalyzed by Copper Smelter Slag