Limonitic Laterite Ore Research Articles

Transformation mechanism and selective leaching of nickel and cobalt from limonitic laterite ore using sulfation-roasting-leaching process

The sulfation-roasting-leaching process holds promise as an environmentally friendly method of production but has low recovery efficiency and poor selectivity for Ni and Co in ores containing impurity metals, including Fe, Al, and Cr. In this study, the transformation mechanism and leaching behavior of metals in a limonitic laterite ore during the sulfation-roasting-leaching process were investigated. Results suggest that the transformation of ferrous ion can reduce leaching efficiency for impurity metals in air atmosphere. The leaching efficiencies for Ni, Co, and Al were 91.1%, 91.5%, and 3.3%, respectively, during roasting at 725 °C for 1.5 h. The leaching solution equilibrium pH value was 3, the concentration of the added H2O2 was 0.5 wt%, and Fe and Cr were not detected in the leaching solution. Simulation and characterization results indicated that the conversion of Fe(II) into Fe(III) reduced the amount of FeSO4 in the roasting product and inhibited iron dissolution, demonstrating that the sulfation-roasting-leaching process is a feasible and environmentally friendly method that selectively leaches Ni and Co in ores containing trivalent metals.

Mineralization Behavior and Strengthening Mechanism of Limonitic Laterite Ore Sintering Process Enhanced by Calcined Lime Coating

Mineralization Behavior and Strengthening Mechanism of Limonitic Laterite Ore Sintering Process Enhanced by Calcined Lime Coating

Atmospheric acid leaching of powdery Ni-Co-Fe alloy derived from reductive roasting of limonitic laterite ore and recovery of battery grade iron phosphate

The efficient and inexpensive extraction of Ni and Co from limonitic laterite ore is becoming imperative due to the rapidly growing demand for nickel and cobalt driven by electric vehicles (EVs). In this work, powdery Ni-Co-Fe alloy was prepared from limonitic laterite via reductive roasting followed by magnetic separation, with nickel and cobalt recoveries of 91.9% and 93.3%, respectively. Most of the gangue material was rejected, and the obtained powdery alloy was readily dissolvable in sulfuric acid solution at atmospheric pressure. Under the conditions of 2.5 M H2SO4, 80 °C, 60 min, L/S ratio of 8 mL/g, the extractions of Ni, Co and Fe were 98.5%, 99.9% and 95.6%, respectively, and chemical reaction was the rate-controlling step. The proposed process is promising for the utilization of limonitic laterite ore with high leaching efficiency and less leach residue discharge.

Effective separation and recovery of iron and chromium from laterite residue in the presence of calcium chloride

In nitric acid pressure leaching (NAPL) for the treatment of limonitic laterite ores, the comprehensive utilization of leach residue is significant for resource recovery and environmental protection. In this work, the recovery and separation of iron and chromium from NAPL residue by metallization reduction roasting−magnetic separation with calcium chloride as additive was studied. The following optimum parameters were obtained: 1100 °C roasting temperature, 25 % reductant dosage, 40 min roasting time, 7 % calcium chloride dosage, 200 mT magnetic field intensity, and 40 s rod mill time (D50 = 7.20 µm). Under these optimum conditions, 81 wt% iron content in the concentrate and 7.4 wt% chromium in the tailings were obtained. The corresponding recovery rates of iron and chromium were 95 % and 64 %, respectively. The microstructure and composition of leach residue and process products were investigated by SEM, EDS, and XRD to study the phase transition and polymerization of substances during roasting. The results showed that iron was mainly enriched in the magnetic concentrate, and chromite and silicate minerals dominated the tailings. Analysis of the action of calcium chloride in the reduction roasting revealed that calcium chloride was beneficial for the liberation of Fe from fayalite and the migration and polymerization of iron.

Smelting and Selective Reduction of Limonitic Laterite Ore in Mini Blast Furnace

Smelting and Selective Reduction of Limonitic Laterite Ore in Mini Blast Furnace

Effects of temperature, CO content, and reduction time on the selective reduction of a limonitic laterite ore

The production of nickel and cobalt from laterite ores has gained increasing attention as their demands continue to rise. This study evaluated the effects of temperature (700–1000 °C), CO content (10–70 vol%), and reduction time (10–90 min) on the selective reduction of a limonitic laterite ore and examined the mechanism of the selective reduction. SEM/EDS observation shows that the ore consists of goethite, hematite and small particles of clinochlore cemented by amorphous iron-rich silicate phase. Nickel and cobalt occur with goethite mineral in this ore. It was observed that fine grains of Fe-Ni-Co alloy dispersed within magnetite phase in reduced samples. XRD and XPS analyses show increased Fe2SiO4 generation with increasing reduction temperature, and elements nickel and cobalt were capatured in Fe2SiO4 according to SEM/EDS observation. Reduction at temperature above 850 °C resulted in a sharp increase in Fe2SiO4 generation and decrease in the specific surface area of the ore. The morphological and compositional observations indicate that CO content over 20 vol% promoted Fe formation from the laterite ore but hardly enhanced the formation of Ni and Co. The difference in equilibrium CO partial pressures for the formation of Fe, Ni, Co accounts for selective reduction. The current study suggests that selective reduction can be achieved by controlling reduction temperature and gas composition. Under the optimum condition of 850 °C, 20 vol% CO-80 vol% CO2 and 60 min, the degrees of metallisation of iron, nickel, and cobalt reduction were 17.5%, 87.3%, and 91.5%, respectively.

Production of ferronickel from limonitic laterite ore using hydrogen reduction and cementation

Production of ferronickel from limonitic laterite ore using hydrogen reduction and cementation was studied by relying on a novel hydrometallurgical process consisting of the key steps: calcination, reductive roasting with hydrogen gas, 2-stage atmospheric hydrochloric acid leaching, and cementation with Fe. The introduction of the reusability of H2-reduced limonitic laterite as a cementation agent instead of conventional Fe sources is an important approach of the proposed process in terms of enhancing cost-effectiveness. The effects of the type of Fe source, the amount of cementation agent, and the temperature on Ni cementation were experimentally determined. The kinetic analysis confirms that Ni cementation behavior can be elucidated by applying 1st order reaction kinetic principles, and the temperature is the most effective parameter. Based on the linear relationship of empirical data with the 1st order kinetic model and by the calculations associated with Arrhenius law, the value of the activation energy of Ni cementation onto Fe could be deduced as 7.5 kJ/mol. Greater than 99% of Ni could be recovered under the most suitable conditions, and the final product was obtained as ferronickel cement (Ni 10%), which can be applied in steel smelter as a prominent intermediate.

Sodium Thiosulfate and Natural Sulfur: Novel Potential Additives for Selective Reduction of Limonitic Laterite Ore

The diminution of sulfide ore deposit as the main source of nickel extraction initiates the development of alternative methods to maximize the processing of low-grade nickel ore including limonitic laterites. Aiming to produce ferronickel with high nickel content and recovery, the study used sodium thiosulfate and natural sulfur as novel additives to be employed in selective reduction techniques. The reduction process was conducted at 1400 °C for 6 h in a coal–limestone bed. Ores and the as-reduced products were characterized by Emission Dispersive X-Ray (EDX) and X-Ray Diffraction (XRD) to determine the elemental composition in the product and examine the phase transformation of ores. Results showed that utilization of 10%wt Na2S2O3 resulted in a product with 14.31% Ni content and 93.22% recovery, while the employment of 10%wt natural sulfur yielded a product with 13.62% Ni content and its recovery reaching 97.91%. Phase identification of slag product using XRD pointed out that both Na2S2O3 and natural sulfur additives assisted the transformation of ore mineralogy in which the kamacite and taenite phases of metal products confirm the successful formation of ferronickel (Fe, Ni). Furthermore, slag products showed a large amount of iron compound, confirming the fact of low iron recovery.

Nitric acid pressure leaching of limonitic laterite ores: Regeneration of HNO3 and simultaneous synthesis of fibrous CaSO4·2H2O by-products

An innovative technology, nitric acid pressure leaching of limonitic laterite ores, was proposed by our research team. The HNO3 regeneration is considerable significance for the improvement of the proposed technology and its commercial application, but it has not been systematically investigated. Herein, regenerating HNO3 from Ca(NO3)2 solution with low-cost H2SO4, and simultaneous synthesis of fibrous CaSO4·2H2O by-products were studied. As a theoretical basis, the solubility of CaSO4·2H2O in HNO3 medium is studied. It is concluded that the solubility of CaSO4·2H2O increases with increasing temperature or increasing HNO3 concentration, which has considerable guiding significance for the subsequent experimental research and analysis. Then, the effects of various factors on the residual Ca2+ concentration of filtrate, the regenerated HNO3 concentration and the morphology of synthesized products are investigated using ICP-AES and SEM. And the effect mechanism is also analyzed. The results indicate the regenerated HNO3 concentration reaches 116 g/L with the residual Ca2+ concentration being 9.7 g/L at the optimum conditions. Moreover, fibrous CaSO4·2H2O by-products with high aspect ratios (length, 406.32 µm; diameter, 14.71 µm; aspect ratio, 27.62) can be simultaneously synthesized.

Effect of a thermal pretreatment on dissolution kinetics of a limonitic laterite ore in chloride media

The effect of a thermal pretreatment on the kinetic parameters and rate-controlling step for nickel leaching dissolution in hydrochloric acid‑sodium chloride solutions from a low – grade Colombian nickel laterite (1.15% Ni, 0.12% Co and 41.1% Fe), was evaluated. The mineralogical analysis showed that nickel is associated with iron in the form of hematite (Fe2O3) and goethite (FeOOH) within the calcined and uncalcined ore, respectively. The hydrochloric acid and total chloride ions concentrations, as well as the leaching temperature, were shown to have a direct effect on nickel extraction. The experiments showed that ~92% of nickel can be dissolved after only 25 min in a 3 M HCl and 2 M NaCl solution when the leaching temperature was increased to 60 °C, after the sample had been previously calcined at 430 °C for 1 h. Nickel dissolution can be described by the chemical reaction-controlled shrinking particle model for both the calcined and uncalcined sample with apparent activation energies of 98 kJ/mol and 103 kJ/mol, respectively. This result suggests that a thermal pretreatment stage does not affect the nickel reaction mechanism, although it may liberate the nickel within the laterite structure.

Sulfur-enhanced reductive bioprocessing of cobalt-bearing materials for base metals recovery

The abundance of limonitic laterite ores in tropical and sub-tropical areas represents a large, and mostly unexploited, cobalt resource. Bioprocessing oxidised ores, and also waste materials such as tailings and processing residues, using acidophilic microorganisms to catalyse the reductive dissolution of iron and manganese minerals, is an environmentally benign alternative approach of extracting valuable base metals associated with these deposits. This work describes results from laboratory-scale experiments in which five cobalt-bearing materials, three primary limonitic laterite ores and two processing residues (filter dust and slag), all sourced from mines and a processing plant in Greece, were bioleached under reducing conditions by a consortium of acidophilic bacteria (using elemental sulfur as electron donor) in stirred tank bioreactors at pH 1.5 and 35 °C. Whilst the target metal, cobalt, was successfully bioleached from all five materials (40–50% within 30 days) the extraction of some other metals was more variable (e.g. between 2 and 48% of iron). Concentrations of soluble cobalt were highly correlated, in most cases, with those of manganese, in agreement with the finding that cobalt was primarily deported in manganese (IV) minerals. Acid consumption also differed greatly between mineral samples, ranging between 3 and 67 moles H2SO4 g−1 cobalt extracted. Comprehensive mineralogical analysis of the three limonitic samples before and after bioprocessing revealed significant variations between the ores, and demonstrated that elemental and mineralogical variabilities can greatly impact their amenability for reductive bioleaching.

Extraction of Nickel and Cobalt from Sulawesi Limonite Ore in Nitric Acid Solution at Atmospheric Pressure

Characterization and leaching study of a limonitic laterite ore from Sulawesi has been undertaken in order to find out mineralogical nature and Ni and Co concentration along with dissolution behavior during leaching process in nitric acid. Extraction rates of Ni and Co in different acid concentration and reaction time were also assessed. Mineralogical identification was conducted using optical microscopy and X-ray diffraction (XRD) techniques; whereas Ni and Co content was determined by means of atomic absorption spectrometry (AAS). Results of analyses show that minerals found in lateritic nickel ore studied were dominated by goethite with less quartz, talc, and trace spinel. Goethite was found to be high dissolution rate in nitric acid whereas quartz, talc and spinel were not dissolved during the leaching process. The highest extraction rates of Ni and Co with different acid concentrations at 1 hour leaching time were 13.22% and 24.17% respectively; whereas the maximum Ni and Co extraction rates under 2 molar nitric acid with different leaching times were obtained at 90 minutes with recovery of 24.17% and 56.53% respectively.

Solvent Extraction of Ni and Co from the Phosphoric Acid Leaching Solution of Laterite Ore by P204 and P507

An alternative process of pre-roasting, phosphoric acid leaching followed by solvent extraction of a limonitic laterite ore was described in this work, with emphasis on the solvent extraction of Ni and Co from the phosphoric acid leaching solution by P204 and P507. First, the pH value of the leaching solution was adjusted using ammonia to reduce the content of Al3+ and Fe3+ by precipitation, then the content of Al3+, Fe3+ and Mn2+ were further decreased by extraction using P204. At last, Ni2+ and Co2+ were separated by three-stage extraction using P507. After extraction, the extraction ratio of Co2+ was 96.61%, while that of Ni2+ was 12.32%, and the selective extraction of Ni2+ and Co2+ could be realized.

An investigation into the distinctive sintering performance and consolidation mechanism of limonitic laterite ore

In this study, the distinctive sintering performance of 100% limonitic laterite was investigated through sinter pot tests, industrial data comparison, theoretical analysis and mineralogy determination. The optimum sinter indices including tumble index, productivity and solid fuel rate were attained at 1.4 basicity as follows: 45.87%, 0.97 t·m−2·h−1 and 140.52 kg/t, respectively. The limit of liquid phases at lower basicity and diffusion of low-strength binding phases, deterioration of SFCA structure and weakened consolidation between hercynite and liquid phases at higher basicity were observed, which was deleterious to sinter. However, the optimum sintering performance of limonitic laterite was far poorer than that of ordinary iron ores, attributed to only 8.78% of acicular SFCA, higher sinter porosity of 48.92%, poorer wettability of high viscosity liquid phases on hercynite and extensive formation of high melting liquid phases and solid phases. It is crucial to develop effective technologies to improve sintering performance of this refractory limonitic laterite.

Improved beneficiation of nickel and iron from a low-grade saprolite laterite by addition of limonitic laterite ore and CaCO3

As is well known, the process of direct reduction and magnetic separation is effective route to deal with low-grade saprolite laterite, but generally limited by the reduction of nickel (iron)-bearing minerals and growth of Fe-Ni alloy particles in the reduction process, causing the low recovery of nickel and iron. To improve beneficiation of nickel and iron from low-grade saprolite laterite with 1.29wt.%Ni and 16.31wt.%Fe, co-reduction with limonitic laterite ore and basicity optimization were adopted as strengthening measures in this paper with better economic efficiency than before. The enhancing mechanism was investigated via the thermodynamics analysis and mineralogical study. The phase transformation and growth behaviors of metallic alloy particles during reduction process were revealed as well. The results indicated that co-reduction with limonitic laterite ore is capable of promoting phase transformation from Ni2SiO4 in saprolite laterite to NiFe2O4. CaCO3 can not only destroy the structure of magnesium silicate to release nickel(iron)-bearing phase, but also enhance the reduction of Fe2SiO4 to form efficiently iron-based eutectoid with nickel and liquid phases to accelerate the growth of Fe-Ni fine particles larger than 40μm. A superior crude alloy was obtained with 5.11wt.%Ni and 82.15wt.%Fe with corresponding recovery rates of 91.89% and 85.15% respectively.

Leaching Ni and Co from Saprolitic Laterite Ore by Employing Atmospheric Acid Leaching Solution with High Concentration of FeCl3 at Mild Conditions

Limonitic and saprolitic laterite ores are used to produce Ni by employing different kinds of processes. Acid leaching is an energy-saving process for pure Ni metal production. The high concentration of Fe in atmospheric acid leaching solution caused difficulties in metal-ions separation. In this work, saprolitic laterite ore was leached by atmospheric acid leaching solution of limonitic laterite ore at moderate temperatures. Conditions affecting the leaching of valuable metals and the conversion ratio of Fe were investigated. The results showed that optimal output was obtained after 1.5 h of leaching at 150°C with 1.0 liquid/solid ratio (volume/weight). X-ray diffraction analysis and mineral liberation analysis indicate that some nickel was adsorbed by leached residues, resulting in the loss of nickel. The physiochemical properties of leached residues could be changed due to the presence of Al and Cr. The decrease in zeta potential and the increase in specific surface area resulted in the increase of Ni adsorption.

A Novel Method of Smelting a Mixture of Two Types of Laterite Ore to Prepare Ferronickel

A novel method of smelting a mixture of two types of laterite ore (saprolitic and limonitic) to prepare ferronickel has been investigated. Thermodynamic analysis revealed that the melting temperature of the slag phase dropped below 1400°C with increasing FeO content, which can be regulated by adjusting the ratio of limonite and the carbon content. The experimental results also proved that the melting degree of the reduced pellets increased with increasing limonitic laterite ratio and that the reduction as well as magnetic separation was enhanced when the reduction was carried out in the presence of limonitic laterite ore. A ferronickel product with 8.08 wt.% Ni, 80.09 wt.% Fe, and 3.75 wt.% C was prepared by heating the mixture to 1380°C in the presence of 6 wt.% carbon content and 5 wt.% limonitic laterite ore, followed by magnetic separation. The Ni and Fe recoveries were 89.26% and 81.64 wt.%, respectively.

A novel utilization of Bayer red mud through co-reduction with a limonitic laterite ore to prepare ferronickel

The large-scale utilization problem of red mud remains a challenge. During the reduction of laterite ores to prepare ferronickel product, sodium or calcium salt usually needs to be added, but it would increase the raw material cost. Thus, the feasibility of co-reduction followed by magnetic separation of strong alkaline waste red mud and a limonitic laterite ore to prepare ferronickel was investigated. A ferronickel product containing 1.71 wt% nickel and 86.00 wt% iron was obtained, under the optimized co-reduction conditions of the red mud dosage of 20 wt%, the anthracite dosage of 16 wt%, the co-reduction duration of 70 min. The corresponding nickel and the total iron recoveries were 96.37 wt% and 97.72 wt%, respectively. Results showed that the co-reduction and comprehensive recovery of the iron ore in the red mud were achieved.

Kinetics on roasting reduction of limonitic laterite ore using coconut-charcoal and anthracite reductants

In recent years, the demand for processing nickel laterite ore, which accounts for about 72% of the world nickel resources, increases as the continuous depletion of sulphidic nickel ore. With as many as 60% of nickel, usage goes into stainless steel production combined with the high price of its pure form, nickel pig iron (NPI) has emerged into account from lateritic ores. However, until now, the process requires the use of coking coal which emits a huge amount of carbon dioxide during the reduction stage so that an initial study about using more environmentally-friendly carbon-based reductant to reduce carbon dioxide emission is deemed important.Limonitic laterite ore, coconut charcoal, and anthracite coal were used in the process. All materials were crushed to certain particular size and then mixed to form laterite-reductant pellets. In a muffle furnace, the pellets were roasted at a temperature of 800 °C, 900 °C, and 1000 °C. Initial analysis of laterite ore and reductant (both charcoal and anthracite) was conducted using X-ray fluorescence (XRF) and proximate analysis. X-Ray Diffraction (XRD) of the samples and the mass loss calculation, before and after the reduction process, were assessed to study the phase transformation and kinetic mechanism. To confirm the minerals in the limonitic laterite ore Thermogravimetric-differential thermal analysis (TG-DTA) was conducted. It is found that the dominating mineral in the limonitic laterite ore is goethite and a little portion of serpentine.The results indicated that hematite and magnetite were present in the roasted sample. From the data fitting, diffusion models match the trend properly and thus, indicated that direct reactions occur. Both Jander and Ginstling-Brounshtein model fit the data properly although Jander model gives the smallest error with the average least square fittings of 0.9778 and 0.9108 for laterite-anthracite and laterite-coconut crust charcoal sample, respectively. The related activation energy values obtained were 3.7092e + 04 and 4.4370e + 04 J/mol showing that coconut charcoal performs comparably as anthracite coal in the reduction of limonitic laterite ore.

Utilization of limonitic nickel laterite to produce ferronickel concentrate by the selective reduction-magnetic separation process

Attempts to economically upgrade low nickel content laterite ore face a number of challenges, including limited ability to beneficiate the ore prior to processing due to its complex association and dissemination structure. Limonitic nickel laterite, characterized by its relatively high iron grade and low nickel content, is very difficult to upgrade. The current work explores improving the beneficiation of nickel from limonitic laterite ore through interaction of silica and calcium sulfate in a selective reduction-wet magnetic separation process. The results show that the ferronickel concentrate assaying 5.0% Ni can be obtained at a nickel recovery of 95.9%, when limonitic laterite ore is reduced at 1250 °C for 60 min with the addition of 3 wt% CaSO4, 8 wt% silica and 3 wt% graphite. The mechanism of additives in promoting the selective reduction of nickel laterite ore was also investigated by XRD, VSM, SEM-EDS and EPMA. The silicate reacted with iron oxide to form the liquid, which decreased the iron metallization ratio. S2 from the thermal decomposition of CaSO4 in a strong reducing atmosphere significantly promoted γ Fe–Ni particle growth by formation of an Fe-FeS eutectic with a low melting point.