Grade Nickel Research Articles

Selective Reduction of High Alumina-Lateritic Nickel Ore (0.5 Ni-44Fe-16Al2O3)

In this present study, the effect of reductant dosage, temperature and holding time on selective reduction process of high alumina-lateritic nickel ore have been investigated clearly. The lateritic nickel ore was reduced with 5 until 15 wt. % anthracite and 10 wt. % sodium sulfate at reduction temperature of 950ºC, 1050ºC and 1150°C for 60, 90, and 120 minutes. Magnetic separation process was then conducted to separate the concentrate and tailing. The analysis of reduced nickel ore is performed by the Atomic Absorption Spectroscopy, X-Ray Diffraction, and Secondary Electron Microscopy. The optimal process resulted from the reduction of nickel ore with 10 wt. % anthracite at the temperature of 1050°C for 120 minutes which resulted in 0.84% nickel in concentrate. The troilite was not found in reduced ore. The iron grade increased along the increased of reduction temperature. The longer of holding time in selective reduction process increased the nickel grade but it decreased the iron grade.

Study of Temperature and Holding Time of Second Stage in Two-stages Thermal Upgrading of Lateritic Nickel Ore

A two-stage thermal upgrading process with the addition of 10 wt.% sodium sulfate and sodium chloride followed by magnetic separation was conducted for treatment low-grade nickeliferous laterite ore to produce a ferronickel product. The aim of this experiment was to investigate the effect of reduction temperature and holding time in two-stage thermal upgrading process, which was carried out from 950°C to 1150°C for 30 to 90 minutes, into the grade and recovery of nickel also the morphology of ferronickel particle. A wet magnetic separation with 500 gauss magnet was conducted to produce ferronickel in concentrate. Increasing the reduction temperature of nickel laterite increased the nickel grade and recovery. The nickel grade and recovery also increased along with the longer holding time in the reduction process. Nevertheless, it decreased the iron recovery.

Sulfides Formation in Carbothermic Reduction of Saprolitic Nickel Laterite Ore Using Low-Rank Coals and Additives: A Thermodynamic Simulation Analysis

In this paper, a systematic thermodynamic analysis of carbothermic reduction of saprolitic nickel laterite ore was carried out. Different carbon sources—such as pure C, sub-bituminous, and lignite—were used for the carbothermic reduction at 1000 °C (1273 K). The effect of the different additives—such as S, FeS, Na2S, Na2SO4, and CaSO4—was also systematically evaluated. The thermodynamic calculations suggested that the use of low rank coals (sub-bituminous and lignite) do not significantly affect the nickel grade and nickel recovery, but affect the total metals recovery. The presence of S in these C-sources promoted the formation of sulfides. At 1000 °C (1273 K), only a small amount of C-sources (C, sub-bituminous, lignite) are needed to significantly metallize the nickel in the laterite, i.e., between 4–6 wt %. The additives S, FeS, Na2S, Na2SO4, and CaSO4 were predicted to promote the formation of liquid sulfides, and at the same time reduce the formation of the (Fe,Ni) alloy, thus reducing the nickel and total metals recovery. Therefore, consideration is needed to balance the two aspects. The calculations predicted that S, Na2SO4, and CaSO4 additions provided an increase in the nickel grade; while FeS and Na2S reduced the nickel grade.

Pre-concentration of nickel in laterite ores using physical separation methods

Nickel is an important metal globally with a consumption of about 2 million tons per year. This is supplied from both sulfide and laterite ores, but currently laterites are becoming more attractive for nickel production due to the depletion of high grade nickel sulfide ores. Laterites are generally processed through hydro or pyro-metallurgy and therefore, pre-concentration of nickel before such processes is very important.This paper examines the effects of different physical methods on pre-concentration of nickel in laterite ores. The effect of ore mineralogy on choosing the best strategy to upgrade nickel will be discussed. The findings of this project will help to unlock a substantial volume of nickel with significant value from laterite ores.

The effect of temperature and mesh size on the dielectric properties of low grade nickel ore at 915 MHz and 2450 MHz

The present study aims to provide a preliminary guide for microwave processing of low grade nickel ores in wrapped form by investigating the dielectric characteristics based on the permittivity determination from 25 to 1300 °C at different apparent densities, mesh sizes, and two industrial microwave frequencies (915 and 2450 MHz). Dielectric constant () variation with the increase of temperature has three distinct stages: decreasing stage in the range 25–200 °C, fluctuating stage in the range 200–1000 °C, and increasing stage in the range 1000–1300 °C. Also, dielectric loss () of the nickel ore varies in the similar way. Both and increase with decreasing mesh size in the investigated 3 stages. Microwave penetration depth () of the nickel ore increases initially due to dewatering and then decreases due to thermal enhanced microwave absorption ability, with increasing temperature. Reflection loss (RL) exhibits dependence on the imaginary thickness. Microwave heating behavior established the critical temperature effect and mesh size dependence on the microwave absorption ability.

X-Ray mapping and the mineralogy pattern of nickel laterite ore: Bavanat, Fars, Iran

According to the classification of the nickel laterite, this paper describes mineralogy test is to reveal where valuable elements are located in the ore, in which mineralogical form. The purpose of the sieving test was to study if some specific particle size contains most of the valuable metals. Based on its chemical composition nickel laterite is classified as a limonite type and the nickel and cobalt content was 0.7 and 0.04%, respectively. Nickel is predominantly associated with hematite and goethite. Based on the mineralogical analysis of the ore, it is observed that remarkable part of nickel is located in hematite. Therefore, nickel cannot be released from hematite lattice. The nickel content in the laterite was 0.7% and the cobalt content 0.04%. The chemical composition of laterite equals with the occurrence of 38.9% iron oxides, 26.9% carbonates, 26.9% quartz, 4.8% chromite, 2.7% magnetite and 1.9% other minerals. EDS line profile analyses were completed on hematite/goethite ooids and there was a slight correlation in the quantities between iron and nickel in each individual ooid. However, iron and nickel do not always show a positive correlation. Nickel grade could be enriched from 0.7 wt.-percent to 0.91 wt.-percent; however nickel recovery was only 45%.

Nanocrystallisation of Nickel Free High Nitrogen Austenitic Stainless Steel through Ultrasonic Shot Peening

Ultrasonic Shot Peening (USP) - a novel route of surface modification was employed on biomedical grade Nickel free high nitrogen stainless steel (18Cr-21Mn-0.65N-balance Fe) to obtain a surface nanostructure without changing its chemical composition and microstructural phase transformation. Hardened steel shots of diameter 2 mm and 3mm were repeatedly impacted on the specimen surface at a constant frequency of 20KHz for 2 and 8 minutes duration. Coarse surface grains of size 36±6µm transformed into nanocrystalline grains of size 13-18 nm. The deformed layer resulted by USP treatment increased with increase in shot diameter and duration of USP. The microstructure was characterized by using optical microscope, SEM, XRD and TEM technique. The hardness and roughness of the treated surface was also found to be strongly dependent on the USP process parameters.

Effect of reduction temperature and sodium-based additives on nickel upgrading process of laterites ores

In this present work, the selective reduction of nickel laterite was conducted by using 10 wt. % of sodium carbonate, sodium chloride and sodium sulphate as additives. The 5 wt. % of palm shell charcoal was used as the reductant. The selective reduction process for nickel laterite was carried out from 950ºC to 1150ºC for 60 minutes followed by wet magnetic separation using 500 Gausses permanent magnet. The characterization of reduced ore was performed by X-Ray Diffraction, optical microscope and Scanning Electron Microscope with Energy Dispersive X-Ray Spectroscopy, while the chemical composition of concentrate or ferronickel was identified by X-Ray Fluorescence. The results showed that the nickel grade was increased with the increasing of reduction temperature for nickel ore with sodium sulfate additive. Nevertheless, it was relatively constant for sodium carbonate and sodium chloride additive. Nickel recoveries found increased with the increasing of reduction temperatures of nickel ore with sodium-based additives. The ferronickel particle was agglomerated and growth with the increasing of reduction temperature, thus it provided favourable conditions for the separation of ferronickel from impurities in the magnetic separation process.

Optimal conditions for selective reduction process of Nickel Laterite Ore

A low-grade nickel laterite ore from Indonesia was selected to investigate the effect of temperature and time of reduction upon the extraction of nickel through the selective reduction-magnetic separation process to produce the ferronickel. The nickel ore was mixed with5 wt.% of anthracite coal and 10 wt.% of sodium sulfate additive. The mixed ore was pelletized into 10-15 mm of diameter. A series of selective reduction processes were carried out into the pellet ores at various temperatures of 950-1150 °C for 60-120 minutes. The optimal selective reduction parameters of nickel laterite ore were observed clearly. The experimental results indicated that the reduction reactions proceed more completely at a higher temperature and longer reduction time. The optimum of nickel grade and recovery in the ferronickel concentrate was obtained at the reduction temperature of 1150 °C for 120 minutes, which was 8.45% and 72.1%, respectively. The increasing of temperatures and times of reduction process resulted in higher of troilite phase formation which suppressed the iron metallization and also increased the ferronickel particle size.

Effect of sodium sulfate and sodium chloride in two-stage thermal upgrading of low-grade Nickel Lateritic Ore

Selective reduction process and magnetic separation of nickel lateritic ore were conducted through the two-stage thermal mechanism with the addition of sodium sulfate and sodium chloride as the additives agent. The first thermal process was pre-heating at the temperature of 500°C and holding for 90 minutes. Afterward, the reduction continued at the temperature of 1150°C for the same holding time. The mineralogical composition of the reduced samples was determined by XRD. The microstructure of reduced nickel laterite ore was also examined using SEM-EDS. The optimum composition of the additive was the combination of 10% Na2SO4 + 10% NaCl, which produced a concentrate with 5.52% and 85.89% for nickel grade and nickel recovery, respectively.

Effect of the first thermal stage temperature and retention time in two-stage thermal upgrading of low-grade nickel lateritic ore

Selective reduction process and magnetic separation of nickel lateritic ore wereconducted through the two-stage thermal upgrading processwith the addition of sodium sulphate and sodium chloride as the additives agent. Effect of the first thermal stage temperature has been investigated at various of temperature of 500, 600 and 700°C for 60 minutes and continued with the reduction process at temperature of 1050°C for 30 minutes. The mineralogical composition of the reduced samples was performed by XRD analysis. The optimum temperature was 500°C, which produced a concentrate withnickel grade of 2.98% and iron recovery of 40.17%. Effect of the first thermal stageretention time also has been investigated at temperature of 500°C for 30, 60, and 90 minutes, and continued with the reduction process at temperature of 1150°C for 60 minutes. The optimum temperature was 90 minutes, which produced a concentrate with 3.69% nickel grade, and 90.61% nickel recovery.

The kinetic study of limonitic low grade nickel ore leaching using hydrochloric acid

The leaching kinetic ore from Pomalaa (Southeast Sulawesi, Indonesia) using hydrochloric acid solution was investigated in a batch reactor. Variables studied were temperature, pH and particle size. To evaluate the kinetic parameters, the experimental data were fitted with a shrinking core model of a constant particle size. The experimental data fit very well with the proposed model and the overall rate is controlled by dissolution rate of nickel through product layer. The activation energy (EDe) for the dissolution of nickel is 22.5 kJ/mol. The maximum nickel recovery is 41.5% at pH 1, reaction temperature of 90°C, particle size of -200 mesh, solid to liquid ratio at 0.2 (w/w) and stirring speed of 400 rpm for 240 minutes.

The role of sodium-based additives on reduction process of nickel lateritic ore

In this present work, the selective reduction of nickel laterite was conducted by using 5 to 15 wt. % of sodium carbonate, sodium chloride and sodium sulfate as additives. The 5% wt. of palm shell charcoal was used as the reductant. The selective reduction process for nickel laterite was carried out at 1150°C for 60 minutes followed by wet magnetic separation using 500 Gausses permanent magnet. The characterization of reduced ore was performed by using X-ray Diffraction, optical microscope and Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy, while the chemical composition of concentrate or ferronickel was identified by X-ray Fluorescence. The results showed that the increase of nickel grade and recovery of nickel laterite was significantly more affected by the addition of sodium sulfate rather than sodium carbonate and sodium chloride. The ferronickel particle was agglomerated and growth with the increasing of reduction temperature and dosses of additives, thus it provided favorable conditions for the separation of ferronickel from impurities in the magnetic separation process.

Dependence of the Cross Section of the Cut Layer on the Specific Cutting Resistance

This article deals with the study of the effect of cross section of the cut layer of material and its influence on the specific cutting resistance. Measurement and evaluation were carried out using two machined materials, according to the designation W.Nr. carbon steel 1.1191, which is a reference material for the steel grade and refractory nickel alloy 2.4856. For the purpose of the experiment, longitudinal turning technology with two interchangeable CNMG 120408 SM and CNMX 1204A2 – SM cutting inserts was chosen. According to the recommended index insert values, two different types of cutting conditions were chosen for each material so that the cross section of the chip remained the same during machining. For each material, the cutting speed was constant and the feed rate and cutting depth were changed. The main goal of the experimental work was comparison of the specific cutting resistance in dependence on different cross section of the removed layer of material. On the basis of measuring of cutting forces by dynamometer Kistler the resulting cutting force was determined and the size of the specific cutting resistance was calculated.

Characterization of Weda Bay nickel laterite ore from Indonesia

The association of fine grained MgNi silicates with oxy-hydroxides in laterites and saprolites represents challenges for ore processing, in particular, in nickel enrichment. The Weda Bay nickel deposit in Indonesia is a typical example of these complex ores, where clays such as nontronites develop on polyphase serpentinite as protolith. Thus, ores at Weda Bay have a very fine textured and complex mineralogy, which requires a comprehensive mineralogical identification through the use of a series of different types of analytical approaches (i.e. macroscopic and microscopic methods including SEM equipped with energy dispersive X-ray spectrometry (EDS), Raman spectroscopy, Infrared and X-ray fluorescence spectroscopy, and QEMSCAN® mapping). Nickel rich saprolites were found to be principally composed of several types of MgNi serpentines, quartz, clays (nontronite in particular) and little amounts of iron hydroxides. Besides, some parts of the deposit were characterized by the development of nontronites at the interface between the saprolite and the limonite zone. Above this zone, the limonite zone is dominated by iron hydroxides as expected, which replace all earlier silicates including serpentine, and contains a significant amount of nickel. The representative composite ore sample contains several nickel bearers with variable nickel grade of 2 to 3%. Exceptionally richer phases such as polygonal Fe (Ni)-rich serpentine were also found with nickel grade of 5 to 10%. Serpentine types as well as other newly formed silicates such as Fe-Mg-(Ni) smectites, are intimately mixed, preventing any mineral separation. Therefore, the only phases which can be separated are quartz and magnetite. This complicates the upgrading of nickel in Weda Bay laterite ore.

A Thermodynamic Study of the Reduction of a Limonitic Laterite Ore by Methane

AbstractThe recovery of nickel from the oxidic nickeliferous laterite ores is receiving increasing attention due to the difficulty of recovering this metal from the sulphide ore deposits. One possible solution is to selectively reduce the nickel oxide in the ore, which could then be upgraded by, for example, magnetic concentration. In this article, a thermodynamic study was performed on the reduction of a limonitic laterite ore by methane. Methane was selected as the reducing agent as it has a lower environmental impact than carbon due to the reduced carbon dioxide emissions. The effects of temperatures and methane additions on the nickel recovery and nickel grade were investigated. High recoveries of over 95 % were predicted, but the grades were limited to about 2.5 % due to the formation of magnetite. The thermodynamic simulations for reduction by methane were in agreement with the experimental results in the literature for other reducing agents, reflecting the fact that the nickel oxide in the limonitic ore is relatively unstable. Thus, high recoveries could be achieved irrespective of the reducing agent involved.

Selective flotation of fine-grained pentlandite from low grade polymetallic ore

The main aim of this study is to test a new type of an impeller in selective flotation of a low grade polymetallic Ni-Cu-PGE ore. The effect of impeller type and speed on bubble size and nickel grade and recovery was investigated. It was noticed that bubble size was independent of impeller type and speeds. However, the highest volume of small bubbles was measured using a new type of impeller. The results showed that a pitched blade turbine impeller has a positive effect on nickel grade and recovery at higher impeller speed.

Factors affecting nickel upgrade during selective grinding of low-grade limonitic laterites

ABSTRACT In this study wet grinding batch experiments were performed in a laboratory ball mill using laterites from Evia island, Greece, in order to determine the optimal grinding conditions for potential nickel upgrade. Selective grinding which exploits the different grindability between soft and hard minerals was considered. Kinetic models were determined based on population balance considerations for different feed and ball sizes. The efficiency of selective grinding was evaluated by taking into account breakage kinetics as well as the grade and recovery of nickel in the products. The results showed that, in general, nickel tends to concentrate in the finer fraction of −0.075 mm. In this fraction nickel recovery is increased significantly with increasing grinding times, while only a slight decrease in its grade is noticed. The results of breakage rate analysis indicate that nickel bearing phases are ground with a higher rate when shorter grinding times are used.

Beneficiation of Low-Grade Laterite Nickel by Calcination-Magnetic Separation Method

In this research, Effect of thermal treatment on beneficiation of low-grade laterite nickel by calcination-magnetic separation method was studied. In order to determine the components and elements of the sample, to recognize the main and minor minerals and their bond, and phase transformation caused by thermal treatment, Chemical analysis (XRF and ICP), microscopic studies and XRD analysis were done, respectively. SEM analysis was done to study the content of nickel and other minerals. In order to determine the phase transformation of the sample because of calcination treatment, thermal analysis of DTA/TG and XRD analysis, before and after of calcination were done. Wet magnetic separation tests with two methods of calcination-magnetic separation and only magnetic separation were done on the sample and the results in grade and recovery of nickel concentrate were compared. According to results, nickel content in the sample was0.94%. Main minerals of laterite sample were Hematite, Goethite, Quartz, and dolomite and minor minerals were Magnetite and minerals of serpentine group. Furthermore, there is no independent nickel mineral in the sample. SEM studies declared that nickel was substituted in iron-containing minerals (Hematite and Goethite). XRD and thermal analysis (DTA/TG) showed that at 350 °C, Goethite transformed to Hematite and at 750 °C, Hematite transformed widely to Magnetite. Calcination of feed at 750°C followed by wet magnetic separation with the magnetic field of 6000 Gauss in comparison with alone magnetic separation caused an increase in recovery and grade of magnetic concentrate to 12.7% and 0.41%, respectively. Results showed that an increase in temperature of more than 750 °C, caused a decrease in recovery and grade of nickel in magnetic concentrate.

Feasibility of co-reduction roasting of a saprolitic laterite ore and waste red mud

Large scale utilization is still an urgent problem for waste red mud with a high content of alkaline metal component in the future. Laterite ores especially the saprolitic laterite ore are one refractory nickel resource, the nickel and iron of which can be effectively recovered by direct reduction and magnetic separation. Alkaline metal salts were usually added to enhance reduction of laterite ores. The feasibility of co-reduction roasting of a saprolitic laterite ore and red mud was investigated. Results show that the red mud addition promoted the reduction of the saprolitic laterite ore and the iron ores in the red mud were co-reduced and recovered. By adding 35wt% red mud, the nickel grade and recovery were 4.90wt% and 95.25wt%, and the corresponding iron grade and total recovery were 71.00wt% and 93.77wt%, respectively. The X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive spectroscopy (SEM-EDS) analysis results revealed that red mud addition was helpful to increase the liquid phase and ferronickel grain growth. The chemical compositions “CaO and Na2O” in the red mud replaced FeO to react with SiO2 and MgSiO3 to form augite.