Higher Copper Recovery Research Articles

Adsorption of Heavy Metal from Wastewater by Bioabsorbent Modified Azolla microphylla and Lemna minor

Environmental toxicity from rapid industrialization raises concerns about water pollution caused by industrial waste and urban sewage. Aquatic macrophytes, such as the Azolla species, have shown promise in absorbing heavy metals and nutrients from water. This study introduces a novel approach by evaluating Azolla Microphylla and lemna minor as an economical adsorbent for copper removal from rivers. Moreover, this study stands out by conducting thorough characterization analyses. The adsorbent material underwent XRD, SEM, BET, and FTIR analyses after being crushed and sieved to 1-2 mm. Copper was extracted from river water using UV-Vis detection at 285 nm. Optimal conditions for adsorption were determined at pH 4, 30 minutes of contact time, and 0.4 g of adsorbent. Copper concentrations in the Sungai Petani, Sungai Selangor, and Sungai Langat ranged from 2 mgL-1 to 5 mgL-1. Azolla proves effective as a copper adsorbent due to its simplicity in sample preparation, time-saving benefits, cost-effectiveness compared to conventional systems, and high copper recovery rate. By successfully removing copper, a prevalent heavy metal contaminant in industrial waste and urban sewage, this research contributes to achieving Sustainable Development Goal 6 for clean and safe water supplies.

Copper recovery from low-grade copper sulfides using bioleaching and its community structure succession in the presence of Sargassum

Bioleaching characteristics and bacterial community structure were studied during low-grade copper sulfide ores bioleaching in the presence of pretreated Sargassum (PSM). Results indicated that proportion of attached bacteria and copper recovery were improved by using appropriate-dosage PSM. High copper recovery (82.99%) and low Fe3+ concentration were obtained when 150 mg L−1 PSM was used. Precipitation, such as KFe3(SO4)2(OH)6 and (H3O)Fe3(SO4)2(OH)6, was not found in samples used PSM according to XRD, FTIR and TG analyses, which may result from less passivation layer formed by Fe3+ hydrolysis. I− contained in PSM can act as the reductant to convert Fe3+ into Fe2+, which can reduce Fe3+ hydrolysis and adjust Eh value. Bacterial community structure was influenced significantly by PSM according to the 16 S rDNA analysis. Acidithiobacillus ferrooxidans dominated proportion of bacterial community throughout bioleaching process, whose proportion reached 89.1091% after 14 days in sample added 150 mg L−1 PSM.

A novel trithiocarbonate collector featuring high-temperature resistance for copper slag flotation

The nature of copper slag flotation is unique due to the high temperature in the flotation pulp and high metallic copper content in the feed. Despite its great potential for valorizing slag, copper slag flotation remains challenging due to the deactivation of traditional dithiocarbonate (DTC) collectors (e.g., butyl xanthate) under high temperatures. DTC collectors also respond poorly to the metallic copper due to the difficulty in forming stable chemical adsorption. In this work, possible deactivation mechanisms of DTC collectors are proposed, i.e., decomposition, oxidation and thermal desorption. A novel furfuryl trithiocarbonate (FTTC) collector was designed and synthesized. Spectral characterization using FT-IR, H-NMR and ion trap MS confirmed the molecular structure of the synthesized collector and its decomposition, oxidation and polymerization products at 55 °C. The novel collector features high-temperature resistance and high metallic copper recovery, as revealed by the single mineral flotation experiments of chalcopyrite, pyrite and metallic copper at both 25 °C and 55 °C. The high collecting ability and selectivity of our collector were explained by EHOMO and ELUMO values using first-principles calculations. Our work provides guidance for the design of collectors exhibiting high-temperature resistance for copper slag flotation, aims at constituting a meaningful contribution for unlocking potential copper resources in copper slag.

High efficiency copper recovery from anode slime with 1-butyl-3-methyl imidazolium chloride by hybrid Taguchi/Box–Behnken optimization method

Anode slime which is produced by electrolytic refining of copper, is a significant source of copper production. However, conventional recovery methods for copper are characterized by complex process, huge amount of strong acid consumption and hazardous acid waste. Therefore, novel, green, and high-performance process for copper separation was developed. In this paper, a hydrometallurgical process for copper recovery from copper anode slime was proposed with ionic liquid leaching – precipitation – calcination routes. 1-butly-3-methyl imidazolium chloride (BmimCl) was used as a leaching agent. According to the hybrid Taguchi/Box-Behnken optimization, the optimum leaching conditions for copper leaching were determined as 80 % of ionic liquid concentration, 95 °C of temperature, 4.5 h of time, and 0.07 of solid/liquid ratio. Validation tests performed under optimum leach conditions confirmed the feasibility of the model and 95 % of copper leaching efficiency was obtained. Precipitation with ammonium hydroxide solution at room temperature and calcination at 600 °C processes resulted in a highly pure copper recovery as CuO. Also, under optimum conditions, highly soluble lead was easily separated after filtration by cooling in the form of PbSO4.This hydrometallurgical process is found to be simple, environmentally friendly, and adequate for the recovery of copper from copper anode slime.

Separation of Chromium (VI), Copper and Zinc: Chemistry of Transport of Metal Ions across Supported Liquid Membrane.

Prior to applying supported liquid membranes (SLM) with strip dispersion for separation of chromium (VI), copper and zinc, suitable chemical settings were determined through solvent extraction and stripping studies. More than 90% of copper and zinc could be simultaneously extracted with at least 3% (v/v) di-(2-ethylhexyl)phosphoric acid (D2EHPA) at a feed equilibrium pH in the range of 3.5–5.0. For stripping, theoretical model equations derived and experimental results revealed that suitable concentrations of lower acid strength reagents can strip metals that have weaker metal-extractant bond without significantly stripping metals that have a stronger metal-extractant bond. Therefore, in a setup comprising three compartments separated by two SLM, we propose to fill the three compartments in the following order: feed—strip dispersion containing low acid strength reagent—strong acid. An organic phase with 4% (v/v) D2EHPA was used. From stripping experiments, 0.2 mol/L pH 3 citrate buffer, which resulted in the highest copper recovery (88.8%) and solution purity (99.0%), was employed as the low acid strength reagent while the strong acid consisted of 1 mol/L sulfuric acid. In 26 h, 99.1% copper was recovered by citrate buffer with 99.8% purity and 95.1% zinc was recovered by sulfuric acid with 98.4% purity. Chromium (VI), copper and zinc could be separated effectively using this separation strategy.

Continuous Bioleaching of Arsenic-Containing Copper-Zinc Concentrate and Shift of Microbial Population under Various Conditions

The goal of this work was to study the bioleaching of arsenic-containing polymetallic concentrate that contained 6.2% Cu, 7.3% Zn and 1.7% As, depending on different temperatures and in the presence of CO2 and molasses in the medium, as well as the difference in the composition of microbial population formed under various conditions. A mixed population of moderately thermophilic and thermotolerant acidophilic microorganisms formed during the continuous bioleaching of copper concentrate was used as an inoculum. The experiments were carried out in a continuous mode in laboratory scale reactors, with a temperature range of 40 °C to 60 °C. To assess the effect of CO2 and molasses on metal leaching and microbial population composition, the experiments were carried out in three reactors: CO2 (~0.01 L/min) was supplied into the first reactor; 0.02% molasses were added to the pulp of the second reactor; and no additional carbon sources were supplied into the control reactor. The highest copper recovery (27%) was achieved at 50°C in the experiment with molasses, while the highest zinc recovery (82.1%) was reached at 45°C in the control experiment. Additional carbon sources affected the extraction of non-ferrous metals only at 60 °C and increased the extraction of copper and zinc by 12.6% and 24.2%, respectively. Both the temperature and carbon source used affected the microbial population composition. The main microbial genera revealed in the populations by next generation sequencing (NGS) were bacteria of the genera Sulfobacillus and Acidithiobacillus, as well as archaea of the genera Ferroplasma, Acidiplasma, and Cuniculiplasma. At low temperatures (40 and 45 °C), Acidithiobacillus, Sulfobacillus, and Ferroplasma predominated, while at temperatures 50–55 °C, the decrease in relative abundance of these genera occurred, and the predominance of Acidiplasma archaea was observed. The usage of both CO2 and molasses led to the increase in Sulfobacillus and Acidiplasma in relative abundance.

Digital technology for optimizing the sodium sulphide dosage during copper ore flotation

The article analyzes an advanced methodological approach to optimizing reagent flotation regimes during dressability studies for mineral raw materials. This paper studies the electrochemical processes occurring directly in the flotation slurry. In the course of laboratory experiments, the multifunctional effect of sodium sulfide during the flotation of off-balance ore of the Zhezkazgan ore field was studied. The use of the initial multifactorial matrices enabled the subsequent application of digital technologies, which, in turn, made it possible to improve the process indicators for the raw materials studied. It has been shown that the information space required for the implementation of digital technologies may be formed through the application of advanced ionometry methods. With the use of neural network modeling to monitor the electrochemical parameters of the slurry during flotation of copper ore of the Zhezkazgan ore field, it has been found that optimized sodium sulfide supply plays a decisive role in achieving high copper recovery, provided that the potential of the argentite electrode has been stabilized at the level of –450 mV when preparing the slurry before the flotation. The high reliability of the neural network model confirms the effectiveness of the original multifactorial matrices for use in laboratory tests. Due to the high accuracy of the resulting model, the optimal operating process parameters may be found.

Electrochemical investigation of microbially and galvanically leached chalcopyrite

The effect of the galvanic interaction between anodic chalcopyrite and cathodic pyrite was investigated by long-term electrochemical measurements of the galvanic coupling current and verified by chemical leaching and bioleaching. For the first time galvanic corrosion measurements (in the absence and in the presence of microorganisms) over days are reported. Combined microbial and galvanic leaching of chalcopyrite showed increased Cu recovery in the presence of pyrite. Corrosion resulted in mineral dissolution depending on multiple parameters (like metal corrosion). However, maximal chalcopyrite dissolution via bioleaching occurred in the presence of a large cathodic pyrite surface. Highest copper recovery was observed in case of high rest potential differences between galvanically coupled minerals (pyrite coupled with copper concentrate). A comparison of electrochemical data of this study with scientific literature revealed a wide range of rest potential data for a single metal sulfide. Fundamental research on galvanic interaction of mixed mineral systems need to focus on unified experimental parameters to allow a comparison.

Selective and ultrafast agglomeration of chalcopyrite by a water in oil emulsion binder

A high internal phase water in oil emulsion has been used as the binder in a novel agglomeration process for achieving selective and ultrafast recovery of hydrophobic particles. For the first time, the novel agglomeration was applied to the selective recovery of chalcopyrite particles from a model feed formed from equal portions of high grade chalcopyrite (27.5 wt% Cu grade) and pure silica, with Sauter mean diameter of the chalcopyrite of 11.0 µm. While very high copper recovery was achievable when sufficient binder was added, the selectivity was found to depend on the solution chemistry. The separation performance achieved in a period of 7 s of agglomeration was found to be very strong for a pH of 8.5, 9.0, and 9.5, but very poor at a pH of 10.5. Interestingly, this pH dependence was not observed in froth flotation experiments. Further, the aging of the model feed had an impact on the agglomeration but not on the flotation. These effects were attributed to the emulsifier, SMO, being released from the binder used in the agglomeration experiments.

Microwave improving copper extraction from chalcopyrite through modifying the surface structure

Microwave-assisted leaching as a green and efficient method for leaching chalcopyrite has attracted increasing attention. Researchers have actively explored the reasons why microwaves have a positive impact on copper extraction. In this work, X-ray diffraction (XRD), an optical microscope, electron probe micro-analyzer (EPMA) and field emission scanning electron microscope with energy dispersive spectrometer (SEM-EDS) were employed to investigate the surface structure modification of chalcopyrite by microwave during leaching. The modified chalcopyrite had a positive effect on better mineral leachability, higher effective surface for leaching, and the fewer passivation layer. The superior mineral leachability was related to the surplus intermediate products of covellite, while microwave promoted the conversion of chalcopyrite to covellite. In addition, microwave is capable of increasing active sites upon the removal of the passivation layer and the enlargement of the effective reaction surface. This work summarized the relationship between the high copper recovery and the surface structure modification of chalcopyrite systematically.

The effect of degree of liberation on copper recovery from copper-pyrite ore by flotation

ABSTRACT Flotation of grinding products with 55, 60, 65, 70, and 75% of grain size <74 μm, was conducted at the pulp’s pH values of 10 and 12. Higher copper recovery was obtained in concentrates at pH 10, but with lower copper grades, approximately 2%. Copper recovery in concentrates at pH 12 was slightly less, but copper grades were much higher. The effect of grinding was higher at pH 12, especially in terms of copper grades in concentrates, which declined with the increase of grinding time. Ore microscopy tests were done on the concentrates with 55 and 75% of grain size <74 μm at pH 10 and 12. All particles of copper minerals were divided by grain size fractions and by the degree of liberation. Analysis have shown that degree of liberation was higher in finer grinding products.

Effect of Surface Modification with Different Acids on the Functional Groups of AF 5 Catalyst and Its Catalytic Effect on the Atmospheric Leaching of Enargite

Carbon-based catalysts can assist the oxidative leaching of sulfide minerals. Recently, we presented that AF 5 Lewatit® is among the catalysts with superior enargite oxidation capacity and capability to collect elemental sulfur on its surface. Herein, the effect of acid pre-treatment of the AF 5 catalyst was studied on the AF 5 surface, to further enhance the catalytic properties of AF 5. The AF 5 catalyst was pretreated by hydrochloric acid, nitric acid and sulfuric acid. The results showed that the acid treatment drastically changes the surface properties of AF 5. For instance, the concentration of quinone-like functional groups, which are ascribed to the catalytic properties of AF 5, is 45.4% in the sulfuric acid pre-treatment AF 5 and only 29.8% in the hydrochloric acid-treated AF 5. Based on the C 1s X-ray photoelectron spectroscopy (XPS) results the oxygenated carbon is 30.6% in the sulfuric acid-treated AF 5, 29.2% in the nitric acid-treated AF 5 and 28.3% in the hydrochloric acid-treated AF 5. The nitric acid pre-treated AF 5 resulted in the highest copper recovery during the oxidative enargite leaching process, recovering 98.8% of the copper. The sulfuric acid-treated AF 5 recovered 97.1% of the enargite copper into the leach solution. Among different leaching media and pre-treatment the lowest copper recovery was achieved with the HCl pre-treated AF 5 which was 88.6%. The pre-treatment of AF 5 with acids also had modified its elemental sulfur adsorption capacity, where the sulfur adsorption on AF 5 was increased from 30.9% for the HCl treated AF 5 to 51.1% for the sulfuric acid-treated AF 5.

Investigation of Copper Recovery from a New Copper Ore Deposit (Nussir) in Northern Norway: Dithiophosphates and Xanthate-Dithiophosphate Blend as Collectors

The Norwegian mining industry is currently showing increasing interest in the production of metals. Recent research has demonstrated promising results identifying the high potential of the Nussir deposit for the production of copper and other valuable minerals. Mineralogical characterization for Nussir ore samples and their flotation concentrates was performed with optical microscopy and Zeiss automated mineralogy (Mineralogic) where the fine copper sulphide middlings were not completely recovered with a traditional sodium isobutyl xanthate (SIBX) collector. In the current study, dithiophosphate and a mixture of xanthate and dithiophosphate collectors’ interaction on copper and other gangue mineral components of the ore sample were investigated with zeta potential, quantitative adsorption, FTIR studies and Hallimond tube flotation. All the results for single mineral experiments confirmed the feasibility of selective copper sulphide flotation by disecondary butyl dithiophosphate (DBD) as collector. The blend of xanthate and dithiophosphate was chemically adsorbed as individual entities on the surface of the copper minerals via competitive adsorption. A systematic study with DBD and a mixed collector (SIBX and DBD) system was conducted on the coarse grind (−105 µm) of the Nussir ore sample, and the results showed a synergistic interaction between the two reagents. The beneficiated copper concentrate using this mixture of collectors is indeed of improved copper grade and recovery. The highest copper recovery in bench scale flotation was 95.3% with a concentrate grade of 19.4% Cu for DBD collector, whereas mixtures of dithiophosphate and xanthate collectors in the ratio of 3:1 resulted in the highest copper grade (24.7%) and recovery (96.3%).

Investigating the Impact of Pretreating a Waste Copper Smelter Dust for Likely Higher Recovery of Copper

The presence of contaminants and poor porosity structure, pose a challenge to efficient copper recovery from a waste copper smelter dust (CSD), a bye product of copper pyrometallurgy. This report presents the impact of two pretreatment methods (oxidative roasting and centrifugal classification) on possible higher copper recovery from the waste CSD produced during copper smelting in South Africa. The primary waste CSD (AS), its roast products (RP) and concentrates (CT) were characterized with the XRF, BET and SEM for changes in the level of contaminants and porosity structures. The SEM images, showed, pictorially that the reduction in BET surface area from 4.1730m2/g (AS) to 0.4634m2/g (RP) was because of agglomeration of smaller particles to form larger once, while 4.1730 m2/g (AS) to 0.3321 m2/g (CT) was shown to be because of the reduction/removal of smaller particles after density separation, leaving behind large particles. Consequently, resulting in significant increase in the average pore diameter from 82.9530Å (AS) to 233.5759Ả (RP) and 410.8530Å (CT). It was therefore concluded that the goal of %reduction in contaminants (mullite-62.70% and quartz-67.23%), together with improved external porosity structure (pore diameter = +400% CT) and internal porosity structures (cracks and peels), were achieved after centrifugal classification (i.e. Knelson gravity concentrator) of AS; which should allow for an enhanced contact time between the acid and copper value in the following leaching step, therefore a likely higher copper recovery from the AS.

Matte converting in copper smelting

ABSTRACTCopper matte converting is the key step to ensure high primary copper recovery in the smelting chain. Its development and the fundamental research carried out over the past decades will be reviewed. The operational challenges and environmental concern of batch-wise Peirce-Smith Converting vessel have induced more than 50 years ago attempts to continuous converting process which have materialised in the last two decades in the flash converting technology, utilised currently in one smelter in USA and three smelters in China. Their annual copper production is in excess of 1.5 Mt, and selected fundamental studies behind this major technological invention will be examined.

The wide distribution of an extremely thermoacidophilic microorganism in the copper mine at ambient temperature and under acidic condition and its significance in bioleaching of a chalcopyrite concentrate

Thermoacidophiles can exist in a state of dormancy both in moderate temperatures and even in cold conditions in heap leaching. Sulphide mineral ores such as chalcopyrite produce sulfuric acid when exposed to the air and water. The produced sulfuric acid leads to the decrease of pH and exothermic reactions in heap leaching causing the temperature to increase up to 55°C and the activation of thermoacidophilic microorganisms. The aim of the present study was to isolate indigenous extreme thermoacidophilic microorganisms at ambient temperature from Sarcheshmeh Copper Complex, to adapt them to the high pulp density of a chalcopyrite concentrate, and to determine their efficiency in chalcopyrite bioleaching in order to recover copper. In this study samples were collected at ambient temperature from Sarcheshmeh Copper Complex in Iran. Mixed samples were inoculated into the culture medium for enrichment of the microorganisms. Pure cultures from these enrichments were obtained by subculture of liquid culture to solid media. Morphological observation was performed under the scanning electron microscope. Isolates were adapted to 30% (w/v) pulp density. For the bioleaching test, the experiments were designed with DX7 software. Bioleaching experiments were carried out in Erlenmeyer flasks and a stirred tank reactor. The highest copper recovery in Erlenmeyer flasks was 39.46% with pulp 15%, inoculums 20%, size particle 90μm and 160rpm. The lowest recovery was 3.81% with pulp 20%, inoculums 20%, size particle 40μm and 140rpm after 28 days. In the reactor, copper recovery was 32.38%. Bioleaching residues were analyzed by the X-ray diffraction (XRD) method. The results showed no jarosite (KFe3(SO4)2(OH)6) had formed in the bioleaching experiments. It seems that the antagonistic reactions among various species and a great number of planktonic cells in Erlenmeyer flasks and the stirred tank reactor are the reasons for the low recovery of copper in our study.

Investigation of an alternative chemical agent to recover valuable metals from anode slime

Anode slime (AS) including high content of precious metals is a by-product obtained after the electro-refining stage in copper production. In this study, it is aimed to recover Cu, Au, and Ag from the AS by using 1-butyl-3-methyl-imidazolium hydrogen sulphate ([Bmim]HSO4) ionic liquid (IL) as a green solvent. The effects of IL concentration, temperature, reaction time and pulp density on recovery of valuable metals were statistically investigated. A high copper recovery of 87.52% was obtained under optimum condition as in 60% (v/v) [Bmim]HSO4 at 50 °C after 2 h, pulp density at 40 g/L (1/25 solid/liquid ratio). Also, a remarkable gold recovery as 97.32% has been achieved in 80% (v/v) [Bmim]HSO4 at 95 °C after 4 h, pulp density at 40 g/L. Temperature and IL concentration were detected as the most effective parameters for copper and gold recovery from AS, respectively. Silver could not be recovered from the AS due to the lower solubility in [Bmim]HSO4 IL media. According to experimental results, [Bmim]HSO4 could be offered as an alternative leaching agent, instead of conventional solvents, to recover valuable metals from copper anode slime.

High copper recovery from scrap printed circuit boards using poly(ethylene glycol)/sodium hydroxide treatment

Recycling scrap printed circuit boards for recovery of valuable metal resources is a major environmental issue. Most available disposal technologies are not environmentally safe. Here, printed circuit board particles were subjected to solvothermal treatment using poly(ethylene glycol)/sodium hydroxide. Results show that residual ratio of bromine varied with temperature, treating time and sodium hydroxide addition. The optimal temperature, treating time and sodium hydroxide addition were 180 °C, 10 h and 0.4 g, with the lowest residual bromine ratio of 1.7%. After treatment, the separation of residue was done by gravity separation and the purity of copper in the recovered metallic components was 97.8%. The recyclability of scrap printed circuit boards before crushing was also compared, the residue of which yielded a complete separation of copper foils and glass fibers. The purity of copper in the foil was achieved at 96.6%. We conclude that this novel process represents an applicable way to recycle high value resources from scrap printed circuit boards.

Optimization of parameters affecting recovery of copper from Sarcheshmeh low-grade sulfide ore using Bioleaching

In this work, the parameters affecting the recovery of copper from the low-grade sulfide minerals of Sarcheshmeh Copper Mine were studied. A low-grade sulfide ore was used with a copper grade of 0.25%, which was about 28% of the mineral oxide, and the sulfide minerals made up the rest. Much more sulfide minerals were found to be pyrite and most of the gangue minerals were quartz, anorthite, biotite, and muscovite. In order to investigate, simultaneously, the solids (10 to 20%) and acidity (1.5 to 2.5) and shaking (110 to 150 rpm), the separation of bacteria from Sarcheshmeh Copper Mine was carried out. After adjustment of the sample, bio-leaching tests were performed in accordance with the pattern defined by the software DX7 in shaking flasks, and the Cu recovery was modeled and optimized using the response surface methodology. The influential parameters were comprehensively studied. The central composite design methodology was used as the design matrix to predict the optimal level of these parameters. Then the model equation was optimized. The results obtained showed that increasing solids (from 10 to 20%) was bad for bacteria. The highest copper recovery was equivalent to 69.91%, obtained after 21 days at 35 degrees using the Acidi Thiobacillus Ferrooxidans bacteria and a K9 medium with a pulp density of 10% and pH 1.5.

Mineralogical Dynamics of Primary Copper Sulfides Mediated by Acidophilic Biofilm Formation

Bioleaching of copper sulfides is catalyzed by iron-and sulfur-oxidizing acidophilic microorganisms attached to the mineral surface forming a biofilm. However, the link between copper sulfides bioleaching and biofilm formation is not yet fully understood. Understanding the factors that are limiting the bioleaching kinetics for different copper sulfide minerals through exhaustive mineralogical analysis of the mineral surface with concomitant biofilm formation during the leaching process will deliver new process conditions with enhanced kinetics and higher copper recovery. In this work we have developed and standardized a reproducible flow cell method able to mimic heap/dump bioleaching laminar flow conditions to study the mineralogical dynamics by advanced mineralogical analysis including QEMSCAN and SEM-EDS coupled to biofilm formation analysis. Based on this method, the bioleaching mineralogical dynamics of primary copper sulfides (enargite (Cu3AsS4), chalcopyrite (CuFeS2) and bornite (Cu5FeS4)) have been determined in the presence of biofilm formation. Supported by the observed mineralogical dynamics, different mechanisms of dissolution for bioleaching were observed as well as selective biofilm formation over the mineral surface, showing enhanced conditions for copper recovery.