Laterite Ore Research Articles

Quantitative mineralogical evaluation of Ni-Co laterite ores through XRPD-QPA- and automated SEM-based approaches: The Wingellina (Western Australia) case study

The evaluation of the mineral abundances and metal deportments in Ni-Co laterite ores by means of routine analytical techniques, such as X-Ray Powder Diffraction-based Quantitative Phase Analysis (XRPD-QPA), could be quite challenging or also ineffective, due to occurrence of ore minerals characterized either by complex crystal structures (e.g. smectite and certain Mn-oxy-hydroxides) or by poor structural order (Fe-oxy-hydroxides). In this context, automated Scanning Electron Microscopy (automated SEM)-based methods, which are based on the chemistry and density of various mineral species, could offer breakthroughs in defining the mineralogy and the metal deportments, bypassing the issues related to the presence of phases not evaluable by using solely XRPD-based approaches. For this study we conducted the mineralogical and chemical evaluation of oxide- and clay-dominated mineralised facies occurring in the Wingellina deposit through XRPD-QPA and automated SEM. The results show that the main benefit of using automated SEM is the possibility to directly detect and identify Ni-Co-bearing Mn-oxy-hydroxides (lithiophorite, lithiophorite-asbolane and asbolane) and Ni-bearing clays, which are hardly distinguished at the XRPD-QPA because of their poorly-crystalline structure. Moreover, the use of automated SEM for the analysis of Mn-oxy-hydroxide-dominated samples also allowed determining the Co deportment, which is essential to predict the optimum achievable metals recoveries. The main limitation encountered during the application of the automated SEM in this study was the fine-grained nature of the ore samples, leading to the detection of mixed mineral classes not corresponding to mineral phases sensu stricto.

Evaluation of Dry Processing Technologies for Treating Low Grade Lateritic Iron Ore Fines

ABSTRACT Dry processing options, involving the use of a circulating air classifier and thermal roasting (advanced microwave-assisted magnetizing roasting), followed by magnetic separation using an Induced Roll Magnetic Separator (IRMS), were evaluated for upgrading low-grade hematite-goethite iron ore fines. The novel magnetizing roast was conducted under reducing conditions using CO/CO2 gas mixtures which converted the initial goethite-rich ore into a magnetite-rich ore. From a feed sample containing 54.5% Fe, 2.10% SiO2, 7.97% Al2O3, 0.97% TiO2 and 0.13% P with a density of 3.87 g/cm3 and 80 wt% passing 675 µm, a high-grade IRMS magnetic product of 62.0 wt% Fe was obtained with a yield of 71.6 wt% and around 82 wt% recovery of iron units.

Corrosion Behavior of a Predeformed Fe-Ni Lateritic Steel with Bainite Structure

In a railway track for intermodal usage between a train station to a port, an observation on corrosion behavior of the track alloy in the coastal environment needs to be considered. In this study, Fe-Ni lateritic steel with bainite structure is observed. This alloy is developed from lateritic ores in Indonesia as an alternative to the conventionally made Fe-Ni steels. This study aims to determine the effect of cold rolling and austempering processes on the corrosion properties of the alloy. The cold-rolling reductions used are 30% and 70%, followed by an austempering process at 400°C for 30 mins with air cooling. The corrosion test was performed on four different samples-- First, a before deformation sample. Second, 30% and 70% cold-rolled samples. Third, austempered without deformation samples. Besides, fourth, deformed austempered samples. The corrosion test method implemented was the CASS Method for 2, 4, and 6 days. The highest corrosion rate obtained by 30% cold rolling, and the corrosion rate is increased as the austempering addition. The microstructures of rust are approximately porous few compact, near to voluminous coarse-grain corrosion products, and tend to crack.

Direct Reduction of Limonitic Laterite Nickel Ore with Variation Type of Reducing Agents to Fe, Ni Content and Recovery by Using Coal-Dolomit Bed Method

The increasing demand for stainless steel and the scarcity of sulfide nickel ore affect the increase of laterite nickel ore processing. One of the processes that has been proven can be applied to process laterite nickel ore is direct reduction. In the direct reduction, the reduction atmosphere was adjusted by controlling the volume of CO and CO2 from carbon source materials, such as coal, charcoal, and green cokes. This research aims to analyze the effect of reducing agents type on nickel limonitic nickel briquettes on Ni and Fe content and recovery of Ni and Fe. The direct reduction process was conducted at 1400°C for six hours. The EDX test was conducted to analyze the elemental composition of the product, especially for Ni and Fe content. On the other hand, the XRD can be applied to analyze the compound formed in the product Greencoke will produce the highest Ni content (15.23%). The highest Ni recovery (96%) was obtained by the addition of green coke reducing agent. On the other hand, the highest Fe recovery (18.8%) was obtained by the addition of coal reducing agent.

Kinetics of Atmospheric Leaching from a Brazilian Nickel Laterite Ore Allied to Redox Potential Control

The kinetics of atmospheric sulfuric acid leaching from a Brazilian nickel laterite ore was assessed using distinct reducing agents and ore mineralogy. This transitional ore contains 1.63% Ni distributed as 1.27% in coarse size (− 500 + 150 μm), mainly as silicates (lizardite and chlorite — 28.6%), and 2.06% in the fines fraction (− 75 μm), mainly as iron oxy-hydroxides (goethite and hematite — 49%). The effects of temperature, acid concentration, reducing reagent type, and concentration were evaluated. The − 75 μm fraction limited the leaching efficiency and the use of reducing media with thiosulfate improved leaching and Ni-Fe selectivity. However, at constant Eh of 626–743 mV and a pH range between 0.2 and 1.1, no substantial rise in metals extraction, except for Co and Mn, has been observed. In order to determine the process control at 95 °C, two regions in the extraction curves were used in combination with the shrinking core model. Control by porous diffusion was observed and the kinetic constant was found to be in the order kFe<kNi<kMn<kCo<kMg for atmospheric leaching without Eh control. In reducing media for the first 15 min of leaching, the kinetic constant was found to be kFe<kNi<kMg≅kCo<kMn as derived from Ni disseminated into iron oxides structures.

Development of a nickel extraction-mineral carbonation process: Analysis of leaching mechanisms using regenerated acid

A closed-loop, Ni extraction and mineral carbonation process is being developed for producing Ni from laterite ores, where the only inputs are heat that can come from regenerable resources, and the ore. This closed-loop relies on efficient regeneration of acid and base, which are required for leaching and neutralisation respectively. This contribution investigates the leaching efficacy of regenerated acid, and proposes a novel combined leaching and acid regeneration (CLR) process where the ore is present during the acid regeneration. It is hypothesised that this will favour the recovery of acid and base, and improve leaching kinetics.Results showed that the CLR process effectively shifted the equilibria to favour the production of acid. The feed solution of triethylammonium sulphate was formed by mixing 120 mmol H+ in the form of sulphuric acid (H2SO4) and 140 mmol triethylamine (Et3N). After 30 h 38 mmol of protons were regenerated in the CLR process compared to 30 mmol of protons being produced in the same timeframe during acid regeneration alone. The CLR was approximately twice as selective towards Mg and Ni over Al and Fe than leaching with the regenerated acid. However, the CLR process was not effective at increasing the recovery of base, with 60 mmol of Et3N recovered in both cases. The results show that the CLR process has the potential to reduce the acid requirements for leaching nickel laterites, which could improve the sustainability of metallurgical operations.

Nickel and cobalt losses from laterite ore after the sulfation-roasting-leaching processing

The sulfation-roasting-leaching process has successfully been used to extract nickel and cobalt from laterites due to its flexibility for application to ores with different chemical and mineralogical characteristics. One of the main characteristics of this process is to leave elements such as iron, aluminum, and chromium in the residues as insoluble oxides. In this work, a sample of nickel laterite ore from the northern region of Brazil was processed by the sulfation-roasting-leaching route. The samples after each step of the process were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis by atomic absorption spectrometry. The phases quantification was carried out by the Rietveld method. Under favorable conditions, nickel and cobalt recoveries were higher than 80 (wt.%) while the iron recovery was only 5.5 (wt.%). Despite the higher nickel and cobalt extraction, it was verified after calculation of the metals distribution throughout the main mineral phases present in the solid leaching residue that hematite was responsible for 29.5 (wt.%) and 60.8 (wt.%) of nickel and cobalt losses in the solid leaching residue, respectively. The sulfation-roasting-leaching process efficiency is influenced by many variables, then, depending on the ore characteristics, furnace choice, and processing conditions. The possibility of reprocessing the hematite in the solid leaching residue to increase the recovery of valuable metals can be a key factor for the route viability.

Separation and recovery of iron and nickel from low-grade laterite nickel ore by microwave carbothermic reduction roasting

An effective strategy to achieve separation and recovery of iron and nickel from low-grade laterite ore via microwave carbothermic reduction roasting is reported. In this work, we determined the underlying reason for the poor separation of iron and nickel during the magnetic separation process. The effect of operating variables on the recovery and separation of nickel and iron from low-grade laterite ore was initially investigated during microwave carbothermic reduction roasting to reveal the underlying reason for their poor separation. Then, the phase transformation and interfacial reduction of fayalite Fe2SiO4 and hortonolite Fe2−xMgxSiO4 in the mineral composition of laterite were systemically investigated via SEM/EDS and XRD analysis to determine the influence of CaO and MgO on the stepwise reduction behavior of Fe2SiO4. Phase transformation during the microwave carbothermic reduction roasting process by microwave irradiation heating occurred according to the following steps: (Fe,Ni)2SiO4 (x=0) and Mgx(Fe,Ni)2−xSiO4 (0≤x≤2)→MgxCay(Fe,Ni)2−x−ySiO4 (0≤x+y≤2)→MgxCa2−xSiO4. Finally, the substituted iron and nickel ions were found to reduce to ferronickel alloy under a reductive atmosphere. The ferronickel alloy with a nickel grade of 7.05wt.% and an iron grade of 71.70wt.% was produced successfully from low-grade laterite ores in which the recovery ratios of nickel and iron were 92.44% and 91.17%, respectively. Furthermore, these methods could be extended to the reduction behavior and interfacial reaction of silicates in other ores.

Chromium occurrence in a nickel laterite profile and its implications to surrounding surface waters

Ultramafic rocks are considered as the most important geogenic sources of Cr whose hexavalent species is of environmental concern. In tropical to subtropical areas (e.g. New Caledonia, Brazil, Philippines), prolonged and pervasive weathering of ultramafic rocks produces Ni laterite ores which are further enriched in Cr. While elevated levels of Cr have been identified in Ni laterites, Cr availability and export from these deposits and its contribution to natural waters remain poorly understood. Therefore, this study examined the speciation and flux of Cr in a Ni laterite profile through sequential extraction and leaching experiments coupled with physical, mineralogical, and geochemical characterization. These were correlated to the behavior and export of Cr in surrounding surface waters studied through hydrochemical investigation. This work demonstrates, through the example of the Rio Tuba Ni laterite deposit, that pervasive weathering of ultramafic rocks in tropical areas generate very important reservoirs of Cr(VI). Although Cr is primarily fixed in insoluble fractions (>89%) and least in bioavailable and easily mobilizable phases (<1%), due to the inherent elevated Cr content (up to 2.9 wt%) of the Ni laterites, the latter still provided water-extractable Cr(VI) contents surpassing drinking water and freshwater standards. By comparison with the silicate-rich saprolite unit, the overlying Fe-(oxyhydr)oxide dominated laterite layer yielded lower Cr(VI) contents due to its acidic nature and higher amounts of organic matter and Fe-(oxyhydr)oxides which promote reduction and readsorption of Cr(VI). During water infiltration, Cr(VI) migrates downward along the profile at a rate of 62 to 3446 t/km2/yr. While the alkaline and oxidizing conditions of the surrounding surface waters favor Cr(VI) mobilization, only a fraction of Cr(VI) from the Ni laterites reaches these water bodies. Cr(VI) concentrations (≤213 μg/L) and fluxes (mostly ≤50 kg/km2/yr) in the surface waters being significantly lower than that of the Ni laterites reflect the action of processes (e.g. dilution, reduction, adsorption) that attenuate the release of this species along water flow paths.

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.

Mineralogical Characterization of Limonitic Laterite from Africa and Its Proposed Processing Route

The mineralogical characterization and occurrence of target elements in limonitic laterite from Africa was comprehensively studied by X-ray diffraction (XRD), scanning electron microscopy energy spectrum (SEM–EDS), and optical microscope (OM) measurements. The results suggest that laterite ore has a complex internal structure. In the limonitic laterite, the contents of Ni, Co, and Fe are 1.14%, 0.16%, and 45.91%, respectively. The limonitic laterite mainly contains 72.2% iron oxide/oxyhydroxide, 9.37% silicate, 6.22% chlorite. Limonite, chlorite, and manganese oxide are the main nickel carrier with distribution rates of 60.98%, 22.65%, and 13.94%, respectively. Cobalt is hosted in manganese oxides and iron oxides, respectively. Additionally, Au, Pt, Pd, and Ag are also detected in the limonitic laterite. Gold, platinum, and silver are mainly found in their native metals. Palladium is mainly dispersed in the iron minerals. Furthermore, the route of rotary kiln-electric furnace (RKEF) was selected to this limonitic laterite; the results demonstrate that comprehensive recovery efficiency of Ni, Co, Fe is high with recovery rate of 98.72%, 98.38%, 54.89%, respectively. Notably, the majority of noble metals such as Au, Pt, Pd are enriched in crude ferronickel.

Mineralogical characterization of copper lateritic ore from the Furnas deposit - Carajás, Brazil

Mineralogical characterization of copper lateritic ore from the Furnas deposit - Carajás, Brazil

Leaching Kinetics and Mechanism of Laterite with NH4Cl-HCl Solution

Following the growing demand for Ni and Co and the dwindling supplies of sulfide nickel ore, attention has turned toward the more efficient exploitation and utilization of laterite ore. Using ammonium chloride acid solution to leach is an effective method. Our research concerned investigations on the leaching mechanism and leaching kinetics of laterite. XRD was used to demonstrate the leaching mechanism through analysis of the pattern of the leaching residue and raw ore, showing that acid concentration affects the leaching process more significantly than other factors, and that valuable metals are mainly released from goethite and serpentine. The leaching order of these materials are as follows: Goethite &gt; serpentine &gt; magnetite and hematite. The leaching kinetics were analyzed and this leaching process followed a shrinking core model controlled by a combination of interfacial transfer and diffusion across the solid film. Leaching data fitted to the kinetic equation perfectly, and the apparent activation energies for the leaching of nickel, cobalt, and iron were calculated to be 4.01 kJ/mol, 3.43 kJ/mol, and 1.87 kJ/mol, respectively. The Arrhenius constants for Ni, Co, and Fe were 204.38, 16.65, and 7.12 × 10−3, respectively, with reaction orders of Ni (a 1.32, b 0.85, c 1.53), Co (a 1.74, b 1.12, c 1.22), and Fe (a 2.52, b −0.11, c 0.94).

Effects of direct reduction process on the microstructure and reduction characteristics of carbon-bearing nickel laterite ore pellets

A coal-based direct reduction process was used to recover the ferronickel from low-grade nickel laterite ore. The effects of basicity on the compressive strength, metallization rate, microstructure, and reduction characteristics of carbon-bearing nickel laterite ore pellets were investigated. The results show that the metallization rate of iron and the compressive strength of metallized pellets follow a parabolic function with increasing basicity. The optimal reduction temperature of the rotary kiln should be controlled at 1150 °C to 1250 °C with pellet basicity of 0.56 to prevent the ring-forming phenomenon. Under optimum process conditions, the metallized pellets mainly consist of ferronickel ([Fe,Ni]), forsterite ferroan (Mg1.38Fe0.61Ca0.01SiO4), and pigeonite ((Ca0.06Mg0.68Fe0.26)SiO3). The particle size of ferronickel can reach to 30 μm with a high nickel‑chromium concentrations. The compressive strength of metallized pellets is 5220 to 7223 N·Pellet−1, and the metallization rates of iron and nickel are 95.28% to 98.45%, 94.75 to 96.33%, respectively.

Pengaruh Variasi Persentase Reduksi pada Proses Pengerolan Panas terhadap Sifat Mekanik dan Struktur Mikro Baja Laterit

Lateritic ore is one of the raw materials for the steel industry. Lateritic ore processed into laterite steel has more advantages than steel in the market. It has better tensile strength, hardness, corrosion resistance, and welding properties. Lateritic steel is made by performing a casting process. This research aims to investigate the effect of reduction percentage on mechanical properties and microstructure of the lateritic steel after the hot rolling process. The specimens were heated to austenitization temperature at 1000 0 C for 1 hour before the rolling process. The reduction percentage varies by 10%, 15%, and 20%. Hardness and impact test was conducted using a Rockwell Hardness and Charpy method. The microstructure was observed using an optical microscope. The results showed the optimum hardness of 58 HRC in a hot rolling sample with 20% reduction. The highest impact strength of 46 Joule and ductile fracture took place in this sample. The microstructure of this sample showed a bainitic phase causing lower hardness.

The Effect of Alkali Roasting Pretreatment on Nickel Extraction from Limonite Ore by Using Dissolved SO2-Air

Extraction of limonite ore using dissolved SO2–air is an alternative hydrometallurgical method for nickel recovery. This process is carried out at atmospheric pressure and is shown to have good selectivity of nickel over iron, but with a low recovery yield. The literature refers to the application of alkali roasting as pretreatment in laterite ore leaching to increase nickel recovery. Thus, this study aims to apply the combination method of alkali roasting and leaching to extract nickel from limonite ore (1.33% Ni, 46.61% Fe) from the Southeast Sulawesi region. Three alkali compounds were included in the study (NaOH, Na2CO3 and Na2SO4). The batch-leaching process was carried out at pH 1 and 3 and temperatures of 55 and 80 °C for 180 min. The leach liquors were sampled at 15, 60, 90 and 120 min, and concentrations of the extracted metals were measured by Atomic Absorption Spectrometry (AAS). A mineralogy characterization of the raw ore and its residue after leaching was undertaken by using X-Ray Diffraction (XRD), while the thermal decomposition behavior of the ore was characterized by Thermogravimetry Analyzer (TGA)/Differential Scanning Calorimetry (DSC). The addition of Na2CO3, Na2SO4 and NaOH in the ore pretreatment increases nickel recovery from 14.80% without alkali roasting to 23.99%, 28.15% and 39.22%, respectively. The optimum extraction condition for nickel recovery is at pH 1 and a temperature of 80 °C. However, the highest Ni/Fe selectivity of 24,947 is obtained at pH 3 and a temperature of 80 °C, preceded by roasting in the absence of alkali. Compared to other hydrometallurgical processes, the process studied in this work exhibits lower recovery, but provides an alternative to extract nickel from low-grade limonite ore.

Drying Kinetics of a Philippine Nickel Laterite Ore by Microwave Heating

ABSTRACT The microwave drying of a Philippine nickel laterite ore was proposed as an alternative drying method to reduce the air pollution before further pyrometallurgical processing. The effect of thickness of ore bed and microwave power on the specific energy consumption and effective diffusivity were assessed. The results show that the specific energy consumption decreases with increasing the bed thickness and that the specific energy consumption exhibits a minimum at 1200 W. Besides, the increase of nickel laterite thickness and microwave power promotes the effective diffusivity. Compared with the removal of free water, crystalline water removal is proved to be much more energy-intensive. Furthermore, the specific energy consumption in microwave drying of laboratory scale is substantially higher than commercial rotary kiln drying.

Reinforcement of the two-stage leaching of laterite ores using surfactants

A two-stage leaching process, namely, high-pressure acid leaching-atmospheric acid leaching, was used to treat laterite ores under mild conditions. The leaching ratio of Ni was low because of adsorption and incomplete leaching. In this work, surfactants were used as additives to boost the leaching ratio of Ni. The effect of surfactant type (cationic, anionic, and nonionic surfactants) on the leaching ratio of Ni was investigated. Leaching results showed that stearyl trimethyl ammonium chloride (STAC) apparently increased the leaching ratios of valuable metals. The variation in the physicochemical properties of the lixiviant and the residue improved the leaching ratio of Ni in the presence of STAC. Kinetics analysis indicated that the leaching process was controlled by chemical reaction.

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.

Review of the past, present, and future of the hydrometallurgical production of nickel and cobalt from lateritic ores

Laterite ores are becoming the most important global source of nickel and cobalt. Pyrometallurgical processing of the laterites is still a dominant technology, but the share of nickel and cobalt produced by the application of various hydrometallurgical technologies is increasing. Hydrometallurgy is a less energy-demanding process, resulting in lower operational costs and environmental impacts. This review covers past technologies for hydrometallurgical processing of nickel and cobalt (Caron), current technologies (high-pressure acid leaching, atmospheric leaching, heap leaching), developing technologies (Direct nickel, Neomet) as well as prospective biotechnologies (Ferredox process).