Selective Reduction Process Research Articles

CFD-based investigation of NO x removal from industrial waste gas by selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) process using NH3

CFD-based investigation of NO_<i>x</i> removal from industrial waste gas by selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) process using NH₃

Recovery of ferronickel by green selective reduction of nickel laterite

Abstract The conversion of nickel laterite into ferronickel is commonly done through a high-temperature pyrometallurgical process that utilizes fossil fuels, which leads to environmental emissions. In order to deal with this, a biomass-based selective reduction process is proposed that uses palm shell charcoal (PSC) as the reductant. In this study, we investigate how to selectively reduce saprolytic nickel ore in various conditions, including pelletization, reduction at 1150°C for one hour, and wet magnetic separation. The optimal conditions, determined with 0.3 stoichiometric carbon, yielded a nickel content and recovery of 22.778 wt.% and 27.541 wt.%, respectively. Phases identified in the reduced pellet include forsterite, diopside, ferronickel, troilite, and olivine. Adjusting stoichiometry influences nickel concentration, resulting in increased recovery; however, excessive stoichiometry intensifies iron metallization, reducing nickel content. The addition of sodium sulfate affects nickel and iron recovery by promoting FeS phase formation, resulting in reduced iron recovery.

Novel water/oxygen cycle reaction photo fuel cell for solar conversion and pollutant detection: Based on selective 2-electron collaborative catalysis process

New typed photovoltaic devices, represented by water/oxygen cycle based photo fuel cells (PFCs) as a promising strategy to resolve the fossil energy crisis, have attracted extensive attention for the ideal photo energy conversion and utilization efficiency, spontaneous operation, and miniaturized devices. However, they still have limitations such as low oxygen reduction efficiency and poor stability caused by the complex structure of the cathode. In this work, a synergetic and fast 2-electron water/oxygen cycle reaction based dual-photoelectrode fuel cell (DPFC) is constructed with molecularly imprinted (MI)-CdS/ZnO nanorods (NRs) as photoanode and p-type organic semiconductor polythiophene (pTTh) as photocathode for the first time. The larger self-bias and simple structure endow the device higher open circuit potential (EOCV = 1.07 ± 0.08 V) and ideal output power density (Pmax = 60.5 ± 2.1 μW·cm−2). Attributed to the synergistic reaction effects, the 2-electron water/oxygen cycle is realized by the photocathode-generated H2O2 to serve as shuttle molecule, with outstanding cyclic stability (96 %) in 64 h continuous irradiation. Moreover, a portable self-powered sensor for the typical environmental pollutant atrazine is successfully developed based on this DPFC. A very wide concentration range (0.002 to 50 nM) and a super low detection limit (0.19 pM) is achived via a digital multimeter without the assistance of any signal amplifier. The mechanism, pathway, and active site of the selective reduction process are studied by the attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS). This work has proposed a cheap and regulatable new way to convert and utilize solar energy and provided theoretical guidance for achieving economic power generation and the sensing strategy of self-powered sensors.

In Situ Creation of Surface Defects on Pd@NiPd with Core-shell Hierarchical Structure Toward Boosting Electrocatalytic Activity.

A deep insight into surface structural evolution of the catalyst is a challenging issue to reveal the structure-activity relationship. In this contribution, based on a surface alloying strategy, the dual-functional Pd@NiPd catalyst with a unique core-shell hierarchical structure is developed through selective crystal growth, surface cocrystallization, directional self-assembly, and reduction process. The surface defects are created in situ on the outer NiPd alloy layer in the electrochemical redox processes, which endow the Pd@NiPd catalyst with excellent electrocatalytic activity of hydrogen generation reaction (HER) and oxygen generation reaction (OER) in alkaline media. The optimal Pd@NiPd-2 catalyst requires an overpotential of only 18 mV that is far lower than Pt/C benchmark (43 mV) at the current density of 10 mA cm-2 for the HER, and 210 mV that is far lower than RuO2 benchmark (430 mV) at 50 mA cm-2 for the OER. Density functional theory (DFT) calculations reveal that the outstanding electrocatalytic activity is originated from the creation of surface defect structure that induces a significant reduction in the adsorption and dissociation energy barriers of H2O molecules in the HER and a decrease in the conversion energy from O* to OOH* that resulted from the synergy of two adjacent Pd sites by forming O-bridge. This work affords a typical paradigm for exploiting efficient catalysts and investigating the dependence of electrocatalytic activity on the surface structural evolution.

Essential Rule Derived from Thermodynamics and Kinetics Studies of Benzopyran Compounds.

Compounds with benzopyran as the core structure play an important role in the total synthesis of antioxidants, drugs, and natural products. Herein, the thermodynamic data of benzopyran compounds and their intermediates were measured and calculated by combining thermodynamics with kinetics. The mechanism of reactions between four benzopyran compounds and organic hydride acceptors was proven to be a one-step hydride transfer. The thermodynamic properties of these compounds and their corresponding intermediates were elucidated. The rationality and accuracy of the electrochemical measurement method were proved. Furthermore, the essential rule of unique structures being present between the C-H bond and para-substituent constants on the benzene ring, as shown in previous studies, was investigated. A simultaneous correlation between thermodynamics and kinetics was found for the hydride transfer reaction, in which the reaction site is connected with the substituent through the benzene ring, a double bond, or a N atom. The likely reason for the correlation between thermodynamic and kinetic is that the benzene ring, double bond, or N atom have the role of transferring the electronic effect. This finding can be applied to the calculation of the activation energy of hydride self-exchange reactions, the prediction of kinetic isotope effects, and explorations of selective reduction processes of hydride transfer in such organic hydride compounds.

The reaction characteristics and mechanism of polymer non-catalytic reduction (PNCR) for NOx removal

To overcome the defects of the traditional selective non-catalytic reduction (SNCR) process (e.g., low efficiency, narrow temperature range), a new modified SNCR technology based on the solid complex polymer reducing agents, also called polymer non-catalytic reduction (PNCR), was investigated both in the laboratory and pilot scale to reveal its reaction characteristics and mechanism. The PNCR process demonstrates excellent removal efficiency (about 90%) of NO in furnace in the wide temperature range (850–1150 °C), and possesses promising application feasibility with an average NOx emission concentration of 68.72 mg·m−3 even on unstable industrial operating conditions. The NO removal behaviors influenced by O2, temperature, or water steam illuminate the unique O2-independent and H2O-promoted reaction characteristics of PNCR in the wide temperature range. The thermogravimetric infrared spectra/mass spectrometry (TG-IR/MS) results further reveal a pyrolysis-assisted formation mechanism of active NH2/NH free radicals without the requirement of O2 and high temperature, which avoids the overoxidation of active radicals and accounts for the wide denitrification temperature window, low oxygen compliance and high denitrification efficiency of PNCR process. The excellent NO removal performance as well as the unique reaction characteristics/mechanism of PNCR forebode its broad industrial application prospect in the field of flue gas cleaning.

Innovative developments on the use of hydrogen in transport internal combustion engines and power plants

BACKGROUND: Innovative technologies and design solutions aimed at using hydrogen in internal combustion engines and hydrogen power plants are reviewed in the paper. The advantages of hydrogen fuel are shown and the main problems that Western automakers face and which determine the ways to solve problems in road transport are identified. In this regard, the method of using hydrogen energy in internal combustion engines and hydrogen power plants becomes a decisive factor.&#x0D; AIMS: Search for a reasonable and effective method of using hydrogen in transport.&#x0D; METHODS: The technologies of hydrogen production with the electrolysis method and on-board generation of hydrogen using hydrogen-containing components are considered. It is proposed to use ammonia as a hydrogen carrier reagent for operation in dual-fuel diesel internal combustion engines.&#x0D; RESULTS: It is noted that ammonia, with a high level of hydrogen content in the molecule, is relatively safe, has a low cost and a significant volume of production. It is easier to store and transport compared to hydrogen. For internal combustion engines operating on hydrocarbon fuel, the use of ammonia and hydrogen, its derivative product, is attractive due to the need to remove highly toxic nitrogen oxides containing in the exhaust gases of diesel internal combustion engines.&#x0D; One of the main problems of creating an environmentally friendly diesel engine associated with reducing the NOx content to an environmentally safe level is considered. A positive factor of using ammonia is the on-board production of hydrogen in the thermal reactor, as well as the possibility of organizing an effective process of neutralizing nitrogen oxides in a diesel engine.&#x0D; CONCLUSIONS: The use of ammonia to generate hydrogen allows the diesel engine to implement the process of selective reduction of nitrogen oxides when ammonia is injected into the combustion chamber at the exhaust stroke. This method will significantly increase the efficiency of NOx neutralization in a diesel internal combustion engine due to the possibility of temperature regulation of the NOx neutralization reaction directly in the cylinder and in the exhaust system of the internal combustion engine.

Numerical Simulation of Selective Non-Catalytic Reduction Denitrification Process in Precalciner and the Effect of Natural Gas Injection on Denitrification

Cement production is the third largest source of nitrogen oxides (NOx), an air pollutant that poses a serious threat to the natural environment and human health. Reducing NOx emissions from cement production has become an urgent issue. This paper aims to explore and investigate more efficient denitrification processes to be applied in NOx reduction from precalciner. In this study, firstly, the flow field, temperature field, and component fraction in the precalciner are studied and analyzed using numerical simulation methods. Based on this, the influence of the reductant injection height and amount on the SNCR was studied by simulating the selective non-catalytic reduction (SNCR) process in the precalciner. The effect of natural gas on the NOx emissions from the precalciner was also investigated. The simulation results showed that, with the increase in height, the NOx concentration in the precalciner decreased, then increased, then decreased, and then increased again. The final NOx concentration at the exit position was 531.33 ppm. In the SNCR denitrification process, the reductant should be injected in the area where the precalciner height is 26–30 m so that the reductant can fully react with NOx and avoid the increase of ammonia escape. The NSR represents the ratio of reductant to NOx, and the results show that the larger the NSR is, the higher the denitrification rate is. However, as the NSR approaches 2, the denitrification rate slows down and the ammonia escape starts to increase. Therefore, according to the simulation results, the NSR should be kept between 1 and 1.6. The denitrification rate reached the maximum value of 42.62% at the optimal condition of 26 m of reductant injection height and 1.6 of NSR. Co-firing of natural gas with pulverized coal can effectively reduce the NOx generation in the furnace. The denitrification rate reached the maximum value of 32.15% when the natural gas injection amount was 10%. The simulation results of natural gas co-combustion and SNCR combined denitrification showed that combined denitrification was better than natural gas co-combustion or SNCR denitrification. Under the condition of NSR of 1 and natural gas injection of 10%, the denitrification rate increased by 29.83% and 31.64% compared to SNCR-only or co-combustion-only denitrification, reaching 61.98%, respectively. Moreover, less reductant is used in co-denitrification, so the problem of excessive ammonia emissions can be avoided. The results of this study provide useful guidance for denitrification process development and NOx reduction in cement production.

Composition of tailings after selective reduction of laterite

The selective reduction process generates products in the form of concentrates and tailing/by-products. There is high percentage of iron and other elements in the tailings that are not extracted in selective reduction process. Properties of by-products of selective reduction were investigated using X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP–OES), ultraviolet-visible (UV–VIS), and scanning electron microscopy energy dispersion spectroscopy (SEM–EDS). Based on the results of this study, the properties of iron-sulfur, iron-magnesium-aluminium, and silica phases in the tailings can be interpreted experimentally. For future research, it can be the reference for such processes as acid and base leaching. Pure iron extracted from tailings can be used for metal fuel in the future. The tailings composition data will help future researchers to find optimal processes for the tailings.

Advancing insights towards electrocatalytic activity of La/Ba-Sr-Co-Fe-O-based perovskites for oxygen reduction & evolution process in reversible solid oxide cell

Electrocatalytic activity of La/Ba-Sr-Co-Fe-O-based mixed ionic and electronically conducting (MIEC) perovskites has been studied for selective oxygen reduction (ORR) and evolution (OER) processes applicable in Reversible Solid Oxide Cell (R-SOC). XPS study establishes scavenging of oxygen vacancy in LSCF and generation of the same in BSCF. BSCF enables faster oxygen ion transport and is correlated with lower frontier molecular orbital (FMO) energy gap of 1.18 eV derived from density functional theory (DFT). Relatively higher ΔEFMO(Absolute) 1.75 eV in LSCF accounts for higher charge transfer. Amperometric measurements @800℃ in asymmetric cell configuration exhibit lowest time-dependent current loss of 0.019 mA.h-1 & 0.035 mA.h-1 for BSCF & LSCF under applied anodic (+0.8 V) and cathodic potentials (-0.8 V) for 200 h with respective surface resistances (Rs) of 0.19 Ω.cm2 and 0.081 Ω.cm2. H2 flux of 0.4Nl.h-1.cm-2 obtained with BSCF, establishes its effectivity as OER whereas LSCF is found to be more selective in ORR.

Influence and mechanism of the adsorption and reactions of residual NH3, NO, and O2 on coal ash after the selective noncatalytic reduction process

NH3 as reducing agent in selective noncatalytic reduction (SNCR) is widely used for the deNOx of coal-fired boiler flue gas, where fly ash significantly influences the conversion of residual NH3 that does not participate in deNOx. However, few studies have been conducted on the exact nature of this influence. The adsorption and reaction of NH3, NO, and O2 on the fly ash at 50–850 °C were investigated in this study. At 50–350 °C, NH3, NO, and O2 co-adsorbed on the coal ash surface, and the presence of NO and O2 reduced the physical adsorption of NH3 on the ash and promoted its chemical adsorption on the ash. At 450–850 °C, coal ash catalyzed NO reduction by NH3 and NH3 oxidation by O2. In the presence of O2, the oxidation reaction became dominant and the reduction reaction was inhibited. The mechanism of adsorption and reaction of coal ash showed that NH3 was adsorbed on the Brönsted and Lewis sites on coal ash and NH3 at the Lewis site could be dissociated into *NH2 and *NH. The NO ad-species in coal ash were mainly nitrate and nitrite. *NH2 reacted with NO to form NH2NO, which desorbed as N2 at 450–850 °C. The main oxidation intermediates for NH3 ad-species were monodentate nitrate and bridged nitrate, which desorbed as NO at 450–850 °C. The results provide a theoretical basis for adjusting the migration and conversion of residual NH3 and reducing ammonia slip from power plants.

Briquetting Pressure Roles in Selective Reduction Process of Limonitic Nickel Laterite

Direct reduction is one of the methods used in nickel extraction from limonitic nickel laterite. Briquettes become an essential part of the direct reduction. This research examines the appropriate com-paction pressure of briquettes to achieve the optimum concentration, recovery of Ni and Fe, and selectivity factors also analyze the com-pounds formed. The briquettes were made at a pressure of 20 Kgf/cm2, 30 Kgf/cm2, 40 Kgf/cm2, and 50 Kgf/cm2. This study was performed out by mixing the prepared materials and then compact-ing them to form briquettes. Then, it was put into a crucible, and the coal-limestone bed mixture is added and put into the muffle fur-nace. Then, the direct reduction was started by heating at 700°C for 2 hours and continued at 1400°C for 6 hours. Next, it was continued with magnetic separation and weighing of the reduction products. The products were tested with SEM-EDX to determine the content. The products were tested with XRD to determine the compounds formed. The optimal results were obtained at variations of 30 Kgf/cm2 with a Ni content of 5.00% and Recovery of 86.76%.

The Technology of Processing of Bed Combustion Fly Ash for Cement Composite Production

Insufficient offer of high-temperature fly ash meeting the requirements of standard EN 4501 is becoming an increasingly significant problem for concrete technology. This trend is generally caused by relentless effort to green electricity generation and reduce the carbon footprint, leading to the decommissioning of coal-fired power plants and the greening of existing. The most often ways are combustion processes of fluidized-bed and selective non-catalytic nitrogen oxide reduction (SNCR) processes. Thanks to these processes, the demand for this raw material has significantly exceeded its supply in recent years. It is, therefore, more than current to look for ways to use the large amount of ash produced from coal combustion, which is not high-temperature fly ash, but can be classified as a bed combustion fly ash or cinder. The paper aims to show the possible processing and subsequent use of these waste materials for the production of cement composites. The possibilities of grinding these coarse-grained fly ashes and the subsequent impact of their use on the cement composite in comparison with conventional fly ash according to the standard EN 450 from the same sources were verified. The impact of their use on the properties of composites in the fresh and hardened state was analysed, and these impacts were related to, for example, their chemistry, grain morphology, loss on ignition, or fineness.

Trimeric Ruthenium Cluster-Derived Ru Nanoparticles Dispersed in MIL-101(Cr) for Catalytic Transfer Hydrogenation

The synthesis of highly dispersed metal nanoparticles supported on metal–organic frameworks has been widely studied as a means to provide high-performance heterogeneous catalysts. Here, a Ru-nanoparticles-supported MIL-101(Cr) catalyst was prepared via a diamine and oxo-centered trimeric ruthenium cluster ([Ru3(μ3-O)(μ-CH3COO)6(H2O)3]CH3COO), Ru3 cluster sequential grafting, followed by alcohol reduction. Ethylenediamine (ED) acted as the linker, coordinating with unsaturated sites on both MIL-101(Cr) and the Ru3 cluster to produce Ru3-ED-MIL-101(Cr), after which selective alcohol reduction process provided the Ru/ED-MIL-101(Cr) catalyst. The synthesized Ru/ED-MIL-101(Cr) catalyst contained small, finely dispersed Ru nanoparticles, and the structural integrity of ED-MIL-101(Cr) was maintained. The Ru/ED-MIL-101(Cr) catalyst was tested for the transfer hydrogenation of benzene using isopropanol as the hydrogen source, where it was shown to outperform other Ru-based catalysts.

Supported Gold Nanoparticle-Catalyzed Selective Reduction of Multifunctional, Aromatic Nitro Precursors into Amines and Synthesis of 3,4-Dihydroquinoxalin-2-Ones.

The synthesis of 3,4-dihydroquinoxalin-2-ones via the selective reduction of aromatic, multifunctional nitro precursors catalyzed by supported gold nanoparticles is reported. The reaction proceeds through the in situ formation of the corresponding amines under heterogeneous transfer hydrogenation of the initial nitro compounds catalyzed by the commercially available Au/TiO2-Et3SiH catalytic system, followed by an intramolecular C-N transamidation upon treatment with silica acting as a mild acid. Under the present conditions, the Au/TiO2-TMDS system was also found to catalyze efficiently the present selective reduction process. Both transfer hydrogenation processes showed very good functional-group tolerance and were successfully applied to access more structurally demanding products bearing other reducible moieties such as chloro, aldehyde or methyl ketone. An easily scalable (up to 1 mmol), low catalyst loading (0.6 mol%) synthetic protocol was realized, providing access to this important scaffold. Under these mild catalytic conditions, the desired products were isolated in good to high yields and with a TON of 130. A library analysis was also performed to demonstrate the usefulness of our synthetic strategy and the physicochemical profile of the derivatives.

(Invited) CdS/Pd Photocatalytic Bipolar Membrane for Selective Reduction and Oxidation Processes

A bipolar membrane with specific cation exchange and anion exchange properties between the two layers enables design of photocatalytically active membrane which also separate reaction compartments. The key advantage of such a membrane lies in the separation of oxidation and reduction processes while continue to engage in the photodriven reactions. The example of simultaneous oxidation of 4-chlorophenol and the reduction of 4-nitrophenol under visible light irradiation of the BPM-CdS/Pd shows its effectiveness in photocatalytic remediation of chemical contaminants. The CdS-Pd based bipolar membrane to carry out selective reduction and oxidation processes has also allowed us estimate the contribution of sacrificial donor oxidation in H2 production in water photoelectrolysis. The design and photocatalytic properties of this photocatalytic membrane will be discussed.

An experimental and modelling study of the Selective Non-Catalytic Reduction (SNCR) of NOx and NH3 in a cyclone reactor

The Selective Non-Catalytic Reduction process was investigated through experiments and modelling in a bench scale cyclone reactor. Outlet and internal profiles of NO and NH3 concentrations were measured at varying operating conditions. Cyclone inlet temperatures between 866 and 1023 °C were used, while the inlet NO concentration was kept at ~500 ppm. Gaseous ammonia was injected in the cyclone inlet, with nitrogen carrier gas. 60–69% NO reduction was achieved at inlet temperatures of 975–982 °C, and stoichiometric ratio NH3/NO β≈1.6, with no ammonia slip. The main reaction zone was the inlet and upper cyclone chamber. The experiments was modelled using simple and detailed kinetics combined with simple reactor models and a compartment model suggested in this work. The qualitative trends of NO reduction and ammonia slip were predicted by the models. However, the ammonia slip was significantly over-predicted in most cases. The outlet concentrations were insensitive to choice of reactor model, while sensitive to temperature and kinetics. The compartment model quantitatively reproduced the cyclones NO concentration profiles, through its simplified representation of the cyclone flow and temperature gradients, while the NH3 profiles were only qualitatively predicted. The choice of bypass fractions showed a large influence on the ammonia profiles.

Cobalt Oxide Nanowires with Controllable Diameters and Crystal Structures for the Oxygen Evolution Reaction

AbstractHerein, mesoporous cobalt oxides with nanowire morphology were size‐selectively synthesized via nanocasting and used as a model system to reveal the impact of diameter, pore, and crystal structures toward the alkaline water electrolysis. A range of Co3O4nanowires with variable diameters was prepared by replication of SBA‐15 silica with different degree of interconnectivity and pore sizes. These nanowires could be further transformed to CoO rock‐salt structure through a selective reduction process by keeping the initial morphology and textural parameters. The electrocatalytic screening showed that CoO with the smallest nanowire diameter and open pore structure showed superior activity in the electrochemical oxygen evolution reaction (OER) due to the higher amount of available active centers and defect sites. The overpotential to reach 10 mA/cm2drops from 392 to 337 mV after reduction of Co3O4to CoO. Anin situRaman spectroscopy investigation showed that Co3O4retained its bulk crystalline spinel phase while CoO faced an irreversible phase transformation into a distorted spinel structure after OER.

Redox Dynamics of Active VOx Sites Promoted by TiOx during Oxidative Dehydrogenation of Ethanol Detected by Operando Quick XAS

Titania-supported vanadia (VOx/TiO2) catalysts exhibit outstanding catalytic in a number of selective oxidation and reduction processes. In spite of numerous investigations, the nature of redox transformations of vanadium and titanium involved in various catalytic processes remains difficult to detect and correlate to the rate of products formation. In this work, we studied the redox dynamics of active sites in a bilayered 5% V2O5/15% TiO2/SiO2 catalyst (consisting of submonolayer VOx species anchored onto a TiOx monolayer, which in turn is supported on SiO2) during the oxidative dehydrogenation of ethanol. The VOx species in 5% V2O5/15% TiO2/SiO2 show high selectivity to acetaldehyde and an ca. 40 times higher acetaldehyde formation rate in comparison to VOx species supported on SiO2 with a similar density. Operando time-resolved V and Ti K-edge X-ray absorption near-edge spectroscopy, coupled with a transient experimental strategy, quantitatively showed that the formation of acetaldehyde over 5% V2O5/15% TiO2/SiO2 is kinetically coupled to the formation of a V4+ intermediate, while the formation of V3+ is delayed and 10–70 times slower. The low-coordinated nature of various redox states of VOx species (V5+, V4+, and V3+) in the 5% V2O5/15% TiO2/SiO2 catalyst is confirmed using the extensive database of V K-edge XANES spectra of standards and specially synthesized molecular crystals. Much weaker redox activity of the Ti4+/Ti3+ couple was also detected; however, it was found to not be kinetically coupled to the rate-determining step of ethanol oxidation. Thus, the promoter effect of TiOx is rather complex. TiOx species might be involved in a fast electron transport between VOx species and might affect the electronic structure of VOx, thereby promoting their reducibility. This study demonstrates the high potential of element-specific operando X-ray absorption spectroscopy for uncovering complex catalytic mechanisms involving the redox kinetics of various metal oxides.

Effect of modified basicity in selective reduction process of limonitic nickel ore

Basicity is an important parameter in the smelting of nickel laterite to obtain low-temperature melting point and low-liquidus slag viscosity, resulting in less energy consumption and a more effective smelting process ferronickel production. Nevertheless, it is still less studied in selective reduction of nickel laterite. In this work, the effect of binary, ternary, and quaternary basicity limonitic nickel ore had been investigated clearly to reveal the appropriate basicity in the selective reduction process. The basicity was modified with the addition of CaO, MgO, SiO2, and Al2O3 in nickel laterite. The reduction process was conducted in a muffle furnace at 1150 °C for 60 min. It was continued with the magnetic separation process to separate concentrate and tailing. The appropriate basicity type in selective reduction of limonitic ore was 0.3 of ternary basicity (BT1) and 0.2 of quaternary basicity (BQ1), which had a similar nickel grade and recovery, i.e., 6.08% and 88.33%, respectively. At low basicity, the addition of CaO and SiO2 could suppress the metallization of iron through troilite and fayalite formation, respectively. Nevertheless, more CaO addition at high basicity could inhibit the ferronickel agglomeration due to the formation of high melting point structures, i.e., melilite. Modifying basicity with the addition of MgO and Al2O3 resulted in a negative effect in selective reduction due to the formation of a complex structure of forsterite and magnesioferrite (with an aluminum substitute), which was more difficult to reduce than magnetite.