Nickel Laterite Leach Research Articles

Effect of pH neutral on the separation of nickel and cobalt from laterite leaching solution using cyanex 272

Abstract Nickel and cobalt are the most common elements in the earth’s crust that naturally occur in laterite ores. Nickel and cobalt from laterite ores are recovered as products such as mixed hydroxide precipitate (MHP) and mixed sulphide precipitate (MSP). This research focuses on how the nickel laterite leach solution can be processed directly for solvent extraction without going through the precipitation stage. The nitric acid leach solution obtained from the laterite ore is used to extract nickel and cobalt. A cyanex 272 extractant and kerosene mixture will be used as an organic solvent for direct extraction. The raw material used was Indonesian laterite ore from Halmahera Island, which contained Ni (1.72%), Co (0.155%), Fe (26.17%), and other minor elements. The effect of pH in a neutral condition was investigated on the extraction efficiency, distribution coefficient, and separation factor. Nitric acid (1M) was applied as the leaching reagent. The variables include pH variations (6.8; 7.0; 7.2; 7.4; 7.6), 20% cyanex 272, and O/A ratio (1:1/v:v) at 20 minutes with a stirring speed of 500 rpm. Optimum results were obtained at pH 7.4 variation with an extraction efficiency of 69.26% for cobalt and 0% for Ni, respectively. At these optimum conditions, the highest distribution coefficient value is the element cobalt at pH 7.4, and the result is 2.253 with a separation factor (∞). The optimum condition focuses on removing cobalt from the organic phase, not nickel.

Solvent extraction of Ni and Co from Ni-laterite leach solutions using a new synergistic system consisting of Versatic 10 acid, Mextral 6103H and Aliquat 336 with elemental mass balance for leaching, precipitation, solvent extraction, scrubbing and stripping

A new synergistic extraction system containing Versatic 10 acid, Mextral 6103H and Aliquat 336 was investigated for nickel and cobalt recovery from nickel laterite leach solutions. It was found that the addition of 0.3 M Aliquat 336 could significantly improve the nickel stripping kinetics of the Versatic 10 acid and Mextral 6103H mixed system, resulting in 98.9% stripping efficiency within 2 min. The effect of Aliquat 336 on the Versatic 10 acid (V10) and Mextral 6103H mixed system in terms of extraction and stripping performance was investigated. Based on the McCabe-Thiele plots for nickel/cobalt extraction and stripping, semi-continuous tests were conducted using the employed synergistic system. Over 99% nickel and 97% cobalt were extracted via a two-stage semi-continuous extraction with a pH profile of 4.5/5.0 for E1/E2 and an O/A ratio of 2.2, resulting in less than 2.0% manganese and negligible magnesium and calcium in the loaded organic solution. More than 95% co-extracted manganese was readily scrubbed via two stages of semi-continuous scrubbing, resulting in less than 1.0 mg/L Mn left in the scrubbed organic solution. Moreover, 98.8% nickel and 99.1% cobalt could be stripped using a two-stage semi-continuous stripping with 1.5 M H2SO4. Based on the test results, a proposed process flowsheet was developed for nickel and cobalt recovery and purification.

Comparative study of selective copper recovery techniques from nickel laterite leach waste towards a competitive sustainable extractive process

The launch of the 17 SDGs in 2015 cast a light in the challenges on sustainable development impacting directly all industrial process, including extractives. As a result, distinct raw materials, even residues, and industrial routes are being rethought to achieve the objectives. The main challenge of nickel limonite processing is the selective separation of target elements due to high-iron content, which is not well explored in the literature, making this material being considered as a waste Different techniques are explored for selective separation of copper, nickel, and cobalt. So, the motivation of the present work was to compare the ion exchange resin (Dowex XUS43605) and precipitation (sodium dithionite) for copper recovery. Batch experiments were carried in a multi-elementary system. Kinetic and thermodynamic parameters were evaluated focusing on industrial modeling. Results showed that the precipitation using sodium dithionite was more selective than chelating resin. On the other hand, sulfide hydrogen may be released making it dangerous for handling; furthermore, the ion exchange process is normally performed as continuous unlike precipitation, which is more suitable for industrial applications. Copper adsorption fitted better to Langmuir isotherm and pseudo second-order. The present study concludes that chelating resin is recommended to reach the SDGs goals.

Structure investigation for nickel and cobalt complexes formed during solvent extraction with the extractants Cyanex 272, Versatic 10 and their mixtures

This work reports the structure investigation of organometallic complexes formation between nickel and cobalt and the extractants Cyanex 272, Versatic 10 and their mixtures. For a better understanding of nickel and cobalt purification from solvent extraction technique, the experiments were carried out with a synthetic leach solution similar to the nickel laterite leach liquor. The coordination number of the metal complexes was evaluated by the ultraviolet–visible (UV–vis) absorption spectra of the organic phases after extraction. The results indicated that the nickel complexes exhibited an octahedral coordination geometry in all investigated organic phases. The cobalt-Versatic 10 complex showed an octahedral geometry, while for Cyanex 272 and the extractants mixture of 15% (v/v) Cyanex 272 and 5% (v/v) Versatic 10 (C15V5), the cobalt complexes presented a tetrahedral structure. Attenuated total reflectance with Fourier transform infrared spectroscopy (ATR/FTIR) was used to identify the interactions between the functional groups of the extractant and the metal ions. Thermogravimetric analysis (TGA) was used to examine the hydration of the complexes. The continuous variation method (Job’s method) was applied to determine the number of molecules involved in the metal-extractant complexes. The Ni-Versatic 10 complex was formed by three molecules of the extractant. For Ni-C15V5 complex, one molecule of Cyanex 272, one of Versatic 10 and two molecules of water formed the complex. For Co-Cyanex 272 and Co-C15V5, the complex was formed with two molecules of Cyanex 272, indicating that in this experimental condition there was no interaction of the extractant Versatic 10 in the extraction. After the stoichiometry of all the organometallic complexes formed had been defined, a structure was proposed for each metal-extractant complex.

Kinetic and thermodynamic study of magnesium obtaining as sulfate monohydrate from nickel laterite leach waste by crystallization

According to the European Union, magnesium is considered as a critical metal, which can also be found in nickel laterite waste processing, where it is a strategic element with nickel, copper, and cobalt. For this reason, the goal of this work was to study the parameters for crystallization of magnesium sulphate under pressure based on nickel laterite leach solution through a reactor designed with separation system where monohydrate crystals were not decomposed. A magnesium monoelementary solution was used for the present study. After the reaction, the solid phase was separated with the reactor still under pressure to avoid crystals decomposition. Magnesium sulphate solubility was determined to complement the data already published in the literature and to define the solubility product from 30 to 230 °C. Pitzer interaction model made possible the Kps values were obtained at high-temperatures. The crystallization of magnesium sulphate reached the equilibrium in 5 h. At pH 5.7 and 230 °C, 81% of the magnesium crystallized. The particles presented a spherical morphology. The reactor here designed allowed the realization of crystallization at high-temperature, without crystals decomposition. The flowchart here proposed represents the novelty since it could be used for critical metals recovery from mining waste.

Recovery of metals by ion exchange process using chelating resin and sodium dithionite

Chelating ion exchange resins can be used to recover metals from nickel laterite leach solution. The main problem is the high presence of iron. In pH above 2.00, iron precipitates and there is co-precipitation of copper and cobalt, which decreases recovery process efficiency. To solve this problem, a conversion of Fe(III) to Fe(II) can be the solution, where Fe(II) will precipitate just at pH 5.00. This reducing process can also increase metals recovery, where ferrous iron occupies less active sites on the resin than ferric iron. However, studies do not evaluate what happens to the resin under this situation. This work aimed to study the copper, nickel and cobalt recovery using chelating ion exchange resin Lewatit TP 207 and reducing process using sodium dithionite 1 mol.L−1. Sodium dithionite was used to convert Fe(III) to Fe(II). The effect of reducing agent on the resin was studied. Three different solutions where prepared to simulate the real nickel laterite leach solution. Batch experiments were performed to study the effect of pH to recover metals and to compare the results with and without the reducing agent. Results showed that metals adsorption increased when the ferric iron was converted to ferrous iron by reducing process. Chelating resin adsorbed more copper and also was selective for this metal at pH 2.50. Nickel and cobalt adsorption were higher at pH 3.50, but the resin was not selective for these metals under this pH. The order of selectivity of chelating resin changed when pH increased.

Effect of iron oxidation state for copper recovery from nickel laterite leach solution using chelating resin

ABSTRACTThe goal of this work was to study the effect of iron oxidation state for Cu(II) recovery. Two different solutions of nickel laterite leach were prepared with Fe(III) and with Fe(II) for the experiments. FTIR of the chelating resin were analyzed before and after metals adsorption. Kinetics and thermodynamics of metals adsorption were studied in batch. Column experiments were performed to study the effect of iron oxidation state on Cu(II) adsorption. Results indicated that Cu(II) recovery was strongly related to iron oxidation state. Cu(II) adsorption was higher in solution with Fe(II) than with Fe(III). Temperature decreased Cu(II) adsorption. Column experiments showed that Fe(II) reached rapidly the equilibrium during the feeding step, and it was lower adsorbed than Fe(III).

Recovery of nickel and cobalt from nickel laterite leach solution using chelating resins and pre‐reducing process

AbstractThe aim of this work was to recover nickel and cobalt from a nickel laterite leach solution using chelating resins combined with a pre‐reducing process. Sodium sulphite was used as a reducing agent to convert Fe(II) from Fe(III) and increase adsorption efficiency. Batch experiments were performed using synthetic solutions to study the effect of pH in recovering these metals using chelating resins Lewatit TP 207 and Lewatit TP 220. Column experiments were performed to simulate the fixed‐bed column process in the following two steps: first, removing copper; and second, recovering nickel and cobalt. Two acids were tested as eluent, namely, sulphuric and hydrochloric acid 1M and 2M. Batch experiments showed that increasing the recovery of the metals accompanied an increase in pH. Copper recovery was maximal at pH 2.00, and the resin selectivity changed in pH above 2, decreasing copper adsorption. However, batch experiments showed that nickel and cobalt recovery was higher at pH 3.50, and resin adsorbed a high concentration of contaminants such as iron, zinc, and chromium. For this reason, nickel and cobalt recovery at pH 2.00 was better in column experiments, with less of the contamination in the metals being adsorbed by the resin and a high selectivity for nickel and cobalt. Hydrochloric acid 2M showed to be more efficient as eluent than sulphuric acid. A precipitation process using NaOH was used to remove contaminants present in the eluent solution, and Cyanex 272 was used to separate cobalt and nickel through the solvent extraction process.

Recovery of Cu(II) from nickel laterite leach using prereduction and chelating resin extraction: Batch and continuous experiments

AbstractThe processing of laterite ores for nickel and cobalt production is increasing to meet the global demand for these metals. Sulphuric acid is used as a leaching agent, and metals present in the solution may be recovered by many different processes, such as ion exchange. The main problem with nickel limonite layer leach solution is the high concentration of iron, which decreases the efficiency of resin adsorption of nickel and cobalt. The removal of iron by oxidation and precipitation results in nickel, copper, and cobalt losses (co‐precipitation). The aim of this work was to investigate the chelating resin extraction to recover copper from a leachate combined with a pre‐reduction process, in order to increase the resin's efficiency and to increase its pH above 2.00. The following three synthetic solutions were studied: first, a solution prepared with Fe(III); the second solution was prepared with Fe(II); and the last solution was prepared with Fe(III) using a reducing process. Batch experiments were performed to study the influence of pH and temperature, and column experiments with three solutions were compared in order to verify suitable conditions to recover Cu(II) in a fixed‐bed column process.

Iron, aluminium and chromium co-removal from atmospheric nickel laterite leach solutions

Atmospheric leaching (AL) of low-grade nickel laterite ores often produces leach liquor containing significant amounts of trivalent iron, aluminium and chromium ions. These impurities are normally removed by increasing the leach liquor pH to precipitate these metals before the recovery of nickel, cobalt and other metal values. This paper documents an investigation of the removal of iron, aluminium and chromium from both synthetic and real nickel laterite AL leach solutions using single- and multi-stage precipitation methods. Single-stage precipitation experiments performed using synthetic leach solutions containing Fe(III) + Ni(II) + Al(III), Fe(III) + Ni(II) + Cr(III), and Fe(III) + Ni(II) + Al(III) + Cr(III) showed that greater losses of nickel to solids occurred in the presence of aluminium and chromium. Increasing the pH value of the solution and the precipitation temperature favoured the removal of iron, aluminium and chromium, but at a cost of greater nickel losses. However, by carefully controlling pH and temperature using a multi-stage precipitation process, the iron, aluminium and chromium can be rejected effectively by precipitation with minimal nickel loss and desirable sludge properties. The optimum conditions for a multi-stage precipitation process were found to be pH 3.0 and 55 °C in the first stage and pH 3.0 and 85 °C in the second stage. Using this approach, as much as 95% iron and chromium together with more than 80% aluminium can be removed; the level of nickel loss to the solid can be reduced to below 1%. The sludge showed a fast settling rate of 5.05 m/h following the addition of a cationic flocculant. Similar satisfactory results were also obtained when performing this multi-stage precipitation procedure with real leach solutions.

Recovery of cobalt and manganese from nickel laterite leach solutions containing chloride by solvent extraction using Cyphos IL 101

An ionic liquid reagent Cyphos IL 101 (trihexyltetradecylphosphonium chloride) was studied for the recovery of cobalt and manganese from the synthetic nickel laterite leach solution containing chloride. It is shown that cobalt and manganese were effectively extracted from the solution containing 100g/L Cl with 0.5M Cyphos IL 101 in the pH range of 1.2–4.5, while no significant nickel, magnesium and calcium were extracted. This could lead to a simple and economical recovery of cobalt and manganese from nickel literate leach solutions. For comparison, tests with other reagents including Aliquat 336 (trioctylmethylammonium chloride) and Alamine 336 (tri-octyl (decyl) amine) which have similar molecular structures were also carried out and it was indicated that Cyphos IL 101 was advantageous for its higher extraction of cobalt and manganese. The effect of pH, chloride concentration, organic concentration and A/O ratio on the metal extraction was studied. Metal stripping tests showed that cobalt and manganese were readily stripped using water. Zinc stripping was very difficult with water and it was only achieved from a low Cyphos IL 101 concentration or using ammonia as the strip reagent. A process for the recovery of cobalt and manganese from laterite leach solutions containing chloride using Cyphos IL 101 has been proposed.

Solvent extraction of zinc, manganese, cobalt and nickel from nickel laterite bacterial leach liquor using sodium salts of TOPS-99 and Cyanex 272

The extraction and separation of zinc, manganese, cobalt and nickel from nickel laterite bacteria leach liquor were carried out using sodium salts of TOPS-99 and Cyanex 272 in kerosene. The unwanted metal ions were removed by precipitation method and solvent extraction was used to extract/separate Zn, Mn, Co and Ni. The nickel laterite leach liquor which was obtained from bioleaching of chromite overburden samples contained 3.72 g/L Fe, 2.08 g/L Al, 0.44 g/L Ni, 0.02 g/L Co, 0.13 g/L Mn, 0.14 g/L Zn and 0.22 g/L Cr. From this leach liquor, 100% Fe, 96.98% Al and 70.42% Cr were removed by precipitation with CaCO3 at pH 4.4 followed by precipitation of remaining Al and Cr with 50% ammonia at pH 5.4. After precipitation, the extraction of Zn from the Fe, Al and Cr free leach liquor was carried out with 0.1 mol/L TOPS-99 followed by Mn extraction with 0.04 mol/L NaTOPS-99. The yields of Zn and Mn were 97.77% and 95.63%, respectively. After Mn extraction, cobalt was removed from the leach liquor using 0.0125 mol/L NaCyanex 272 and finally nickel extraction was carried out using 0.12 mol/L NaTOPS-99 with 99.84% yield. The stripping of loaded organic (LO) phases were achieved with dilute H2SO4.

Reagent selection for recovery of nickel and cobalt from nitric acid nickel laterite leach solutions by solvent extraction

There is currently no commercial process for recovery of nickel and cobalt from a nitrate-based laterite leach liquor via solvent extraction. Such a process is becoming of interest as nitric acid leaching of nickel laterite ores is progressed by Direct Nickel. Although commercially proven solvent extraction processes do exist for nickel and cobalt extraction from sulphate-based laterite leach liquors, little is known regarding their application to nitrate-based liquors. In the present paper three different solvent extraction systems are compared from a commercialisation standpoint in order to inform future process development. These systems were: neodecanoic acid (Versatic™10)/tributylphosphate (TBP), Versatic 10/pyridine carboxylate (PC), and an aliphatic hydroxyoxime based extractant (LIX®63)/Versatic 10/PC. On the basis of acceptable separation of nickel and cobalt from manganese and magnesium, and ease of metal stripping, the synergistic combination of Versatic 10 and a pyridine carboxylate (in this case nonyl-4-PC) was identified as the most promising system for application to a nitrate-based laterite leach liquor.

Characterisation of iron-rich precipitates from synthetic atmospheric nickel laterite leach solutions

Iron-rich precipitates from atmospheric nickel laterite leach solutions normally contain large amounts of poorly defined phases such as schwertmannite and ferrihydrite. This complicates mineralogical identification using routine X-ray Diffraction (XRD) technique. In the present study, the iron-rich precipitates from synthetic nickel laterite leach solutions were characterised by a combination of several techniques that include selective Acidified Ammonium Oxalate (AAO) dissolution, Differential X-ray Diffraction (DXRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infra-Red (FTIR) spectroscopy. These techniques in combination allowed reliable mineralogical identification for samples containing high proportions of schwertmannite and ferrihydrite. The effects of foreign metallic cations on the crystallization, dissolution behaviour and surface sulphate coordination were investigated. The results suggest that selective AAO dissolution is a good method to distinguish between poorly and highly structurally-ordered phases in a mixed assemblage. The presence of goethite in the iron-rich precipitates was only determined after removing the schwertmannite and/or ferrihydrite. Nickel, aluminium and chromium retarded the transformations of schwertmannite and/or ferrihydrite to goethite, but aluminium and chromium supressed the formation of 6-line ferrihydrite. Also, aluminium and chromium influenced the absorbed sulphate symmetry of iron-rich precipitates. The structural order of the phases became less pronounced with the presence of foreign metallic cations, particularly aluminium and chromium. Aluminium and chromium can strongly stabilize iron-rich precipitates making these resistant to leaching by AAO solution. FTIR analysis confirmed the presence of goethite in the bi-metallic precipitates and suggested that the sulphate is present to a greater extent in lower symmetry environments.

The effect of iron precipitation upon nickel losses from synthetic atmospheric nickel laterite leach solutions: Statistical analysis and modelling

Atmospheric acid leaching (AL) of low-grade nickel laterite ores can produce a pregnant leach solution (PLS) containing large amounts of soluble iron. Purification of the leach solution by iron precipitation with an alkaline reagent often causes an associated loss of valuable nickel. In this study, the effects of the factors governing the iron precipitation process upon nickel loss were investigated in synthetic nickel laterite AL liquors containing just nickel and iron by statistical analysis and modelling. The factors examined in this study were pH, temperature, neutralizing agent, initial Fe/Ni ratio in the PLS and stirring speed. The significance of each factor and their interactive effects were evaluated using statistically-designed experiments, where iron removal efficiency (%) and nickel loss (%) were the measured responses. A one quarter fractional factorial design was performed to screen for factors that have more important effects on the responses, and then the principal factors were further optimized in a Box–Behnken Design (BBD) experiment. The BBD which is an effective response surface methodology was applied to fit quadratic models to describe the relationships between the responses and factors. Quadratic response functions were derived for iron removal efficiency (%) and nickel loss (%) by applying a least squares method. The three-dimensional response surface and corresponding contour plots clearly showed the relationships between the responses and interactive factors.

Oxidation of Fe(II) in a synthetic nickel laterite leach liquor with SO 2/air

Under specific controlled conditions, the addition of SO 2 to oxygen or air produces the peroxy-monosulphate free radical in solution, which is a stronger oxidant than oxygen alone. In this study, the practical strategies required to optimise the oxidation of Fe(II) with SO 2/air was investigated at 75 °C as part of a process to remove iron as Fe(III) oxides from a synthetic nickel laterite high pressure acid leach solution containing 5 g/L Fe(II), 1 g/L Fe(III), 8 g/L Ni, 30 g/L Mg in sea water at pH about 2. The rate of Fe(II) oxidation was optimised in the pH range of 1.2–2.0 with respect to SO 2/air ratio and gas flow rates for minimum production of H 2SO 4 and maximum utilisation of SO 2. In order to minimise the air flow rates into the reactor vessel, the maximum rate of SO 2 addition that could be employed with air was established whilst maintaining oxidising conditions. The results provide strategies for commercial applications of the SO 2/air oxidising system and indicate important factors for reactor design.

Removal of magnesium from nickel laterite leach liquors by chemical precipitation using calcium hydroxide and the potential use of the precipitate as a filler material

The chemical precipitation of magnesium from sulphate solution, resulting from heap leaching of nickeliferous laterites with sulphuric acid, was studied. Magnesium was removed as hydroxide using calcium hydroxide (Ca(OH) 2) and the precipitate produced was a mixture of magnesium hydroxide (Mg(OH) 2) and gypsum (CaSO 4·2H 2O). The variables studied were the temperature and the stoichiometric quantity of Ca(OH) 2. The responses measured were magnesium removal and the specific surface of the precipitate. Design of the experiments and statistical analysis of the data were used in order to determine the main effects and interactions of the factors. Scanning electron microscopy (SEM) was also used to investigate the effect of precipitation conditions on the morphological characteristics of the Mg(OH) 2–CaSO 4·2H 2O mixture. Kinetic analysis with the aid of Nielsen theory allowed the determination of the Mg(OH) 2 formation mechanism. The use of a magnesium hydroxide–gypsum mixture as a filler material was also examined. The suitability of the precipitate was evaluated by measuring a set of properties that can characterize a material as a filler and by measuring mechanical properties of polymers filled with the precipitate at various addition levels. The magnesium hydroxide–gypsum precipitate proved to be promising for this application, as it was found to have similar properties with other commercial products.