LIX 984N Research Articles

Extraction of Copper from Pregnant Leach Solution (PLS) and Reduction of Crud Formation

ABSTRACT Presented universal recommendations for the reduction of crud formation, reviewing various aspects affecting the loss of diluent and extractant due to the formation of a third phase (crud), encountered in many hydrometallurgical plants using copper solvent extraction. In this paper introduce the reasons of the crud formation , description of the stable emulsions containing solid particles and choice of technological scheme. An analysis of operations to be considered in the operation of copper solvent extraction plants is presented, due to the deterioration of copper grade below 0.5% in ore and the increase in aluminum content up to 20–25%. Results of use of extraction properties of modified extractants of ACCORGA series and unmodified extractant Lix984N on pregnant leached solution of the most important deposits (Almaly and Aktogay) are given. It is established that for solutions of Almaly deposit, ACCORGA5640 and unmodified Lix984 extractants have high selectivity to copper. Distribution of iron, silica, and copper ions during extraction was studied, and it was found that high selectivity to copper/iron and copper/silica is possessed by extractant Lix 984N, ACCORGA5640. It was found that for solutions of the Aktogay deposit, the ratio of interphase suspension in both extractants is the same, and phase separation in experiments with the use of extractant Lix 984N was 10 s shorter with the use of extractant ACCORGA5640. It was found that the addition of ACCORGACR60 reagent in the amount of 5-10 ppm also leads to a decrease in the volume of crud by 13%, for a stronger suppression of crud.

Establishment of a Hydrometallurgical Scheme for the Recovery of Copper, Nickel, and Cobalt from Smelter Slag and Its Economic Evaluation

In pursuit of carbon neutrality, the demand for metals that are necessary for the development of clean energy technologies is rapidly increasing. Metallurgical waste, such as slag, presents a promising secondary source of these key metals. This research aims to develop an eco-friendly hydrometallurgical process to recover Cu, Ni, and Co from discarded copper/nickel slag. High-pressure acid leaching (HPAL) was used to selectively leach Ni, Cu, and Co from the fayalite slag, yielding high leaching efficiencies of 99.9%, 89.4%, and 99.9%, respectively, with low Fe and Si tenors to the pregnant leach solution (PLS). The solvent extraction (SX) technique utilizing LIX 984N was used to selectively extract and enrich copper from the dilute PLS to about 23 g/L Cu with a very low Fe concentration of 0.05 g/L. Potassium amyl xanthate (PAX) solution was used to form Ni and Co xanthate complexes from the raffinate solution. Nickel was selectively recovered using ammonia solution, while the cobalt xanthate complex was thermally decomposed and recovered as cobalt oxide solids of about 25 wt.% Co. A comprehensive process flowsheet is presented. Furthermore, to realize the real application of the developed slag cleaning process, a preliminary economic evaluation was performed.

Study of the Extraction Process of the Main Components of the Productive Solution (Copper, Iron and Silica) of the Almaly Deposit

The purpose of the research was to study the extraction of the main components of the productive solution of the Almaly deposit with oxyoxime extractants. As the practice of existing plants shows, one of the main drawbacks of the process when implementing the liquid extraction process at various fields is the formation and accumulation of a large volume of the third phase (crud), which leads to a slowdown, in some cases to a stop in the solvent extraction process, thereby reducing the efficiency of the entire production copper by SX-EW technology. One of the main factors leading to the formation of such a phase are harmful metal impurities, solid suspensions in the solution supplied for extraction, improper selection of extractants and the operation mode of the extraction cycle. To prevent such a process, it is important to study the extraction of the main components of productive solutions with different extractants. Studies on the extraction of metals from the productive solution of the Almaly deposit of composition, g/dm3 : Cu 0.235-0.262, Fe 17.97-21.55, SiO2 0.34-0.36 were carried out using reagents Acorga 5640 (10%), Acorga 5640 (5%) with CR60 additive and Lix 984N (10%). It was found that when using the first two, they led to the accumulation of iron and silica ions in the organic phase, and at Lix 984N (10%), the maximum transition of silica ions into the electrolyte, and iron into the raffinate. The accumulation of iron and silica ions in the organic phase is undesirable and may be the cause of crud formation.

The effect of the chloride ion on chemical degradation of LIX 984N extractant

Water supply is becoming an increasingly important aspect of hydrometallurgical operations due to water deficiency. This problem may significantly lessen if the extraction processes can incorporate the usage of saltwater throughout the whole hydrometallurgical operation. In this research, the effect of chloride ion on the chemical degradation of LIX 984N was investigated. It was shown that chloride does not directly degrade LIX 984N. However, it has a catalytic effect on the hydrolysis and nitration of the extractant. The synergic effect of chloride on the extractant degradation through hydrolysis and nitration mechanism was assessed at different acidities and mixing times for up to three months. The presence of chloride ion accelerated the degradation of LIX 984N through both hydrolysis and nitration processes. Additionally, the impact of degradation processes on copper maximum loading, extractant viscosity, copper extraction, impurity entrainment, extraction selectivity, and copper stripping were assessed. The structure of the degraded extractant and its compositional changes was studied using Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC–MS) analysis. Degradation of the extractant resulted in a decrease in maximum copper loading, increasing entrainment of impurities, increasing extractant viscosity, lower copper extraction, and less efficient stripping of copper. Samples degraded in the presence of chloride functioned less efficiently in comparison to samples degraded in the absence of chloride. Moreover, structural changes were more noticeable in samples mixed with an aqueous solution containing chloride.

Effect of the chloride content of seawater on the copper solvent extraction using Acorga M5774 and LIX 984N extractants

In recent years, the application of non-conventional water sources, such as seawater in metal extraction industries located in arid and semi-arid areas have been increased. In this study, the integration of seawater in the solvent extraction of copper hydrometallurgical operation was investigated. Accordingly, two commercial copper extractants, Acorga M5774 and LIX 984N were used in extraction of copper from a sulfate–chloride solution containing seawater. The results showed a higher concentration of copper in the pregnant leach solution (PLS) as a result of using seawater; however, the concentration of Fe and the impurities that are associated with seawater, i.e., Cl, Na, Mg, Ca, K were also increased. The presence of the chloride ion resulted in a higher copper extraction at pH values below 1.5. Synergistic system of LIX 984 N and Acorga M5774 (1:1 vol mixture 15% v/v) was found more efficient in extraction of copper at pH values below 1.5 in comparison to sole LIX 984 N and Acorga M5774. Similarly, the extraction of impurities (Na, Mg, K, and Cl) were observed less when a mixture of extractants were used. The results showed that increasing the chloride concentration had a negative effect on copper extraction as the organic to aqueous ratio was decreased. The copper extraction mechanism was also studied using single LIX 984N, Acorga M5774, and a 1:1 vol mixture of these two extractants at chloride concentrations of 0 and 40 g/L. Increasing the chloride concentration resulted in the involvement of more organic molecules.

The effect of chloride ions on copper solvent extraction from sulfate-chloride medium using LIX 984N

The supply of fresh water is becoming an increasingly important issue in hydrometallurgical treatment of mineral ores. The problem may significantly reduce if the extraction process can incorporate the usage of saltwater throughout the whole hydrometallurgical operation. Seawater as the main source of saltwater is a potential alternative to freshwater. In this research, the effect of the chloride ions, in a range of 0 to 40 g/L, on the solvent extraction of copper with LIX 984N was studied. LIX 984N has been commercially used in copper solvent extraction around the world. Increasing the concentration of Cl− was shown to increase the H+ activity and formation of CuCl+ and CuCl2 species. The solution acidity did not have a negative effect on the extent of copper extraction and extraction rate, in the presence and absence of chloride ion, in contrast to recent studies. The chloride addition was even showed to have a positive impact on copper extraction at pHs below 2 and at shorter mixing times. Through thermodynamic studies, it was shown that increasing chloride concentration results in both higher H+ activity and an increase in the activity of copper chloride complexes, of which the latter factor counteracts the former and overall improves the extent of copper extraction. Increasing the chloride concentration was found to negatively affect the copper extraction isotherms. The impact became more significant at lower concentrations of the extractant. It is therefore suggested that cupric chloride complex ion inhibits copper extraction by lowering the extraction driving forces. Also, it was shown that increasing aqueous chloride concentration promotes involvement of more extractant molecules per Cu2+ species in the extraction reaction in contrast to the reaction without chloride ions. The negative effect of chloride ions on copper solvent extraction then is due to the change in the reaction stoichiometry and decrease in the extraction driving force rather than the types of aqueous Cu2+ speciation. The effect of wash stages on the removal of the chloride ion from loaded organic solution was then investigated and the optimum conditions for the wash stage were found at wash solution to loaded organic ratio of 1 to 7 and sulfuric acid concentration of 10 g/L.

Experimental study of phase entrainment in copper solvent extraction

The entrainment of the organic phase in the aqueous applied to typical solutions in a solvent extraction of copper process was studied. The organic phase used is composed of the commercial extractant LIX 984-N diluted in Shellsol 2046 AR. The aqueous phase contains 6 g/L of Cu2+, at pH 2 and 20 ºC. The variables studied were: mixing speed of 400 to 1000 rpm; mixing time of 3 to 30 minutes; initial pH of the electrolyte 2, 3, and 4; percentage of extractant in the organic phase 10 to 30% v/v; and copper concentration in the aqueous phase 1 to 6 g/L. It was determined that the entrainment of the organic phase in the aqueous is determined by the physical properties of the phases in equilibrium and by the system’s hydrodynamics, and it is a phenomenon that involves the advancing speed of the interphase (or dispersion band) and the displacement speed of the organic drops.

Solvent extraction of copper from sulfate-chloride solutions using mixed and modified hydroxyoxime extractants

The solvent extraction of copper from a sulfate-chloride solution containing seawater and/or sodium chloride was studied using the commercial extractants LIX 984N and Acorga M5910. The effect of chloride on the copper extraction equilibria, the copper-iron selectivity, and the extraction of chloride by the organic phases was evaluated. The results indicated that chloride ions in the aqueous solution affect negatively the extraction equilibria for both extractants and this effect becomes very significant for high chloride concentrations. For both extractants, an increase in the temperature from 25 to 35 °C improves slightly the copper extraction but hinders the stripping of the organic. Based on McCabe-Thiele diagrams for extraction and stripping, it was concluded that Acorga M5910 outperforms the LIX 984N when using solutions containing 110 g/l of chloride ions.

Simulation of precious metals recovery from nickel smelter slag under high-pressure oxidative acid leaching (HPOXAL)

The nickel smelter slag as a solid waste of pyrometallurgical operations can be harmful to the environment especially against the ground that will be contaminated by hazardous components contained the smelter slag. Nickel smelter slag has the content of valuable metals as the following: Nickel (Ni), Cobalt (Co), Copper (Cu), Iron (Fe) and Zinc (Zn). Those valuable metals were carried out by high-pressure oxidative acid leaching to recover all the valuable metals suitable with the high measures of recovery. High-pressure oxidative acid leaching (HPOXAL) is a suitable process for the nickel smelter slag with the parameters of the leaching process as the following: the particle size about – 150 + 74 μm, sulfuric acid solution with the concentration of 0.3 mol in 1 liter solution, Ratio of Liquid to Solid (L/S) with 7 ml of liquid to 1 gram of solid components, oxygen overpressure at 600 kPa, operating temperature about 180 - 200 °C and the retention time of 80 minutes. The measures recovery of this leaching process for each valuable metal in percent of initial weight such as nickel and cobalt about 97%, copper about 95%, 94% of zinc and all iron can be separated, respectively. At the separation section, LIX 984N as extractant extracts copper from the product (leaching solution) of the reactor, limestone was used to capture iron in the leaching solution, versatic 10 and decyl-4PC were conducted to remove undesirable mineral that was generated from the leaching process, and cyanex 272 extractants to extract such as nickel, cobalt, and zinc, respectively. This simulation used the feed flowrate with 150 tons per day. The results of the precious metals product were generated each the mass rate such as copper, nickel, cobalt, zinc, and iron with 927 kg/day, 2147 kg/day, 875 kg/day, 199 kg/day and 71,000 kg/day, respectively.

Percolation bacterial leaching of low-grade copper ore

The article describes results of research on copper recovery from low-grade copper ore by heap bioleaching method. The objects of investigation are ores of the Benkala deposit. Results of chemical analysis by atomic-emission spectrometric method and chemical phase analysis present ores element composition and identify copper and iron forms existing in the ores. Ores were subjected to bioleaching by chemolithotrophic bacteria, which oxidizes sulfur and iron compounds. Acidithiobacillus ferrooxidans FT-24 and BF, Acidithiobacillus thiooxidans BS, Acidithiobacillus ferrivorans SU-8 and Sulfobacillus thermosulfidooxidans ST-12 strains were used in the research. It was modeling the process of bacterial heap leaching of low-grade ore in percolation columns. Comparison of efficiency of sulfuric acid and bacterial leaching in percolation columns shows advantage of bioleaching. The copper yield was 47 % at using conventional sulfuric acid leaching, while utilizing bacterial leaching increased the copper recovery up to 86 % during 90 days of the experiment. The values of oxidation-reduction potential (ORP) at sulfuric acid and bacterial leaching of copper ore presented are in accordance with yield of copper. The values of ORP at standard sulfuric acid leaching are between 330-360 mV, at bacterial leaching more high and are 480-550 mV due to high content of ferric iron. During the extraction of copper, the effect of the organic reagent LIX 984N in concentrations 50 and 250 mg/L on the activity of microorganisms was studied. As a result, the extraction reagent has a little effect on the growth of microorganisms and the extraction of copper. Without adding the extraction reagent, the total copper recovery was about 83 %, while the addition of the extraction reagent with concentration 250 mg/L decreased it to 81 %. So using bioleaching technology allows deep processing of copper ore due to oxidation of copper sulfide minerals.

Clarification and solvent extraction studies of a high talc containing copper aqueous solution

Effects of different flocculants on the clarification of a copper aqueous solution destined for solvent extraction were investigated. The test work was conducted on the pregnant leaching solution (PLS) of a high talc containing copper ore that had a high propensity of bearing a large amount of suspended solids. The clarification test work was conducted using three commercial high molecular anionic polyacrylamide polymer flocculants: rheomax® DR 1050, brontë 103, and senfloc® 2660. Solvent extraction tests were done using 30% (v/v) LIX 984N at pH 1.8. The parameters of clarification and solvent extraction were the flocculant dosage (0, 58.14, 116.28, 232.56 and 348.84g/t) and the ratio O/A (1/5, 1/2, 2/3, 1/1, 3/2, 2/1, and 5/1), respectively. The analysis results of the PLS showed it contained 2000ppm of solids in suspension. The optimal conditions for clarification and solvent extraction were a dosage of 116.28g/t and an O/A of 1.5, respectively. Under optimal conditions, the residual total suspended solids (TSS) in the clarified solutions were 1196ppm, 954ppm, and 928ppm; the phases disengagement time (PDT) for organic continuous dispersion were 70s, 80s and 60s; the percent TSS entrained in the organic phase were 26.76%, 28.93% and 25.32%; copper recoveries were 97.63%, 98.98% and 95.13%, with rheomax® DR 1050, brontë 103 and senfloc® 2660, respectively.

Recovery of high value copper and zinc oxide powder from waste brass pickle liquor by solvent extraction

Solvent extraction of Cu and Zn from spent brass pickle liquor has been carried out using LIX 984N as an extractant. Very high difference in ΔpH1/2 value for the two metals during the extraction indicates the ease of separating them under the appropriate conditions. Based on the bench scale results, metals were separated in a continuous mode using a laboratory scale mixer settler unit from the spent brass pickling solution containing 35kg/m3 Cu, 30kg/m3 Zn, 1.5kg/m3 Fe, 0.75kg/m3 Cr, 0.03kg/m3 Ni and 70kg/m3 H2SO4 with 30% LIX 984N in kerosene. High copper extraction (99.9%) at the phase ratio (O/A) of 2/1 was obtained at the equilibrium pH of 2.5 in a two-stage counter-current extraction process, leaving behind Zn, Cr and Ni in the raffinate. Zinc from the chromium free solution was then quantitatively extracted in three counter-current extraction stages at pH5.5 and O/A=2/1 with negligible co-extraction of nickel. From the respective loaded organic phases, copper and zinc were completely stripped off using 150kg/m3 H2SO4. The stripped solutions of Cu and Zn were utilized for the synthesis of high pure Cu metal powder and ZnO particles by the hydrothermal reduction/precipitation processes. Copper powder was synthesised in an autoclave at 20bar H2 pressure and 423K in 2h. On the other hand ZnO powder (4bar) was prepared from zinc striped solution at pH12 in an autoclave under autogenous pressure at 423K in 2h. The purity and morphology of the as-prepared powders were determined by chemical analysis, XRD and SEM-EDS studies.

Copper ion removal from dilute solutions using colloidal liquid aphrons

The extraction of copper (II) from dilute aqueous solution by predispersed solvent extraction (PDSE) using colloidal liquid aphrons (CLAs) is described. The CLAs were made of LIX 984N as an extractant and an anionic, cationic, and nonionic surfactant. It was observed that the CLAs were in the micrometer size range, and that their size was controlled by the phase volume ratio. The phase volume ratio and extractant concentration in CLAs structure are the most effective parameters in this extraction process. CLAs were able to remove copper ions in less than one minute, and they remained stable for more than two months. The effect of surfactant type and concentration was also investigated, with the anionic surfactant found to produce the best results.

Modeling of Synergetic Effect of LIX 984N and D2EHPA on Separation of Iron and Zinc Using Artificial Neural Network

Artificial neural network was used to predict the synergetic effect of LIX 984N and D2EHPA on separation of iron from zinc solution. The aim was to predict iron and zinc extraction as a function of pH, temperature, and various organic compositions. Optimum number of hidden layers and nodes in each layer were determined. A multilayer network, with two hidden layers (4:9:5:1) was applied to predict zinc and iron extraction. Effect of pH, temperature, extractant composition, and interaction of them on extraction percent was also investigated using 3D plots. The modeling results showed that there is an excellent agreement between the experimental data and the predicted values.

Solvent extraction of copper(ii) from concentrated leach liquors

Hydrometallurgical treatment of complex copper sulfidic ores, by-products and concentrates requires aggressive, oxidative leaching methods and application of Fe(III) ions and oxygen or bacteria assisted environment. Leach liquors generated in the process are usually copper and iron-rich solutions of high acidity. Such conditions require the application of suitably strong and selective reagent to extract copper in SX operations. This paper discusses the copper extraction behavior of commercial copper rea- gents: LIX 984N, LIX 612N-LV and Acorga M5640. Aqueous feed solutions used in SX studies were PLS' generated in atmospheric leaching of commercial flotation concentrate, produced at Lubin Concen- trator (KGHM). McCabe-Thiele diagrams were generated and copper net transfer values were compared and discussed. It was shown that stronger modified aldoxime reagents (Acorga, LIX 612) are superior over non-modified salicylaldoxime/ketoxime mixture (LIX 984N). Particularly, the ester modified Acor- ga M5640 showed advantages in recovery and copper net transfer values.

Contaminants of post-leaching copper solutions and their behavior during extraction with industrial extractants

Several copper extractants have been examined in laboratory glassware with a special attention paid to their behavior towards cations others than copper(II). In the studies 25 vol. percent of hydrocarbon (Exxsol D80 AZ) solutions of six industrial copper extractants have been used. They were mainly rea- gents of hydrooxime type (LIX 860N-IC, LIX 984, LIX 984N, LIX 84-I, Acorga M5640) and diketone type LIX 54-100. Individual isotherms of independent extraction of copper(II) and selected cations (Fe 3+ , Fe 2+ , Co 2+ , Ni 2+ , Zn 2+ , Mn 2+ , Cd 2+ , Mg 2+ ) versus equilibrium pH have been compared. Investigations have been conducted with synthetic 0.1 mol/L solutions of their sulfates. The values of pH50% − parameter defined as an equilibrium pH at the moment of half-and-half extraction of the investigated cationic spe- cies have been presented. Also ΔpH50%, that is differences between values of pH50% for specific cation Me(II) and copper(II): ΔpH50% = pH50%(Me) − pH50%(Cu), have been given. In addition to that 25% LIX 984 has been used in counter-current pilot trials for copper(II) extraction from naturally contaminated solutions produced by bioleaching of industrial sulfide copper concentrate to observe behavior of investi- gated contaminants such as correlations between their real co-extraction with copper(II) and the position of their extraction on the pH scale. Copper electrolyte/strip solution, working alternately within close loop of coupled stripping - electrowinning system, has been analyzed during consecutive cycles to observe building up of the contaminants concentrations in the course of test.

Synthesis and characterization of tenorite (CuO) nanoparticles from smelting furnace dust(SFD)

Tenorite (CuO) nanoparticles were prepared from a dilute CuSO4 solution. The solution was obtained by leaching (pH=1.5) of smelting furnace dust of Sarcheshmeh Copper Complex, Iran. The recovery of copper from the acidic sulphate solution was carried out by solvent extraction using Lix 984-N. Tenorite nanoparticles were synthesized by direct thermal decomposition of Langite [Cu4(OH)6SO4(H2O)2] as a precursor which was calcinated in air for 2 h at 750?C. The Samples were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The average diameter of the spherical pure CuO nanoparticles and their crystallite size were estimated to be 92 nm and 40nm, respectively. The simplicity of the present method suggests its potential application at industrial scale as a cheap and convenient way to produce pure CuO nanoparticles from dilute CuSO4 solutions obtained from leaching of smelting furnace dust.

Isolation and identification of microorganisms causing microbial degradation of organic phase of the solvent extraction unit in the copper industries

Solvent Extraction–Electrowinning (SX–EW) is a hydrometallurgical process involving the dissolution and reprecipitation of copper from solution. The organic phases which are widely used in the SX process are very important economically. On the other hand, there are many poisonous components such as phenol in its chemical construction, so its degradation can be critical at economical and environmental point of view. The organic solutions which are used in the Sarcheshmeh Copper Mine consist of LIX 984N as a main extractant and REYSOL 8411, 8401 and kerosene as diluents. The loss of the organic phase from solvent extraction circuits is a major cost factor for SX/EW operations. Recognized sources of loss include evaporation, entrainment, and biological degradation. The mechanisms for both entrainment and evaporative losses are well recognized. Biological degradation of the organic component has not been as extensively evaluated as the other mechanisms but may be a major source of loss. This paper discusses the impact of biological degradation on an operating plant, potential mechanisms for degradation, conditions under which biodegradation of plant organic can occur and plant conditions that may assist in promoting biodegradation. In this research, isolation and identification of microorganisms which are involved in the degradation of the organic phase of the SX unit in the Sarcheshmeh copper mine were investigated. Samples of soil and activated sludge and a sample from an extraction unit were inoculated into microbial culture media containing organic solution as the only carbon source. After growth and isolation of microorganisms, three genera of bacteria, Acinetobacter, Sphingomonas and Moraxella, and two genera of fungi, Aspergillus and Phialophora, were identified.

Extraction of copper, nickel and cobalt from the leach liquor of manganese-bearing sea nodules using LIX 984N and ACORGA M5640

This paper describes a method, using sulfuric acid and activated charcoal for leaching Polymetallic sea nodules. Resulting leach solutions were examined for the extraction of copper, nickel and cobalt using LIX 984N and ACORGA M5640 in kerosene. After the removal of manganese and iron impurities from the leach liquor, copper and nickel were co-extracted leaving cobalt in the raffinate. The selective stripping of nickel and copper produces solutions rich in these metals, while regenerating the solvent for reuse.

Recovery of Copper, Nickel and Zinc from Sulfate Solutions by Solvent Extraction Using LIX 984N

Recovery of valuable metals such as copper, nickel and zinc from synthetic sulfate solutions using LIX 984N as the extractant dissolved in kerosene was investigated. The metals get extracted at different equilibrium pH of the aqueous phase and thus the pH of the aqueous solutions forms the basis of their separation. Copper was extracted at an equilibrium pH of 3.5, while nickel and zinc get extracted at an equilibrium pH of 7.3 and 8.8 respectively. The extraction isotherms of copper, nickel and zinc were obtained by contacting the respective metal solutions and 0.05 M LIX 984N at different A:O phase ratio at their respective equilibrium pH of maximum extraction. A two‐stage counter‐ current extraction simulation was done to achieve quantitative extraction of the metals. Furthermore, a two‐stage counter‐ current stripping simulation yielded quantitative recovery of the individual metals, from their loaded organic phases. On the basis of the results, a flow sheet of the process has been developed.