Rotary Kiln-electric Furnace Research Articles

Circular Economy Approach on Decarbonization by Repurposing Used Cooking Oil for Nickel Smelter – A Case Study of PT Megah Surya Pertiwi, Obi Island, North Maluku, Indonesia

Abstract This research was instigated by the world’s endeavours to fight dependency on fossil energy sources. While coal prevails as a beneficial energy source, countries worldwide have strived to reduce coal usage in the future under the Net Zero Emission Pledge. Questions linger on how to minimize coal usage, play down its impact on the environment, and maintain economic advantages. This quantitative study focused on the repurposing of used cooking oil for alternative energy sources at PT Megah Surya Pertiwi (PT MSP), the first downstream company of Harita Nickel that processes nickel saprolite ore to Ferronickel using the Rotary Kiln Electric Furnace (RKEF) technology in Obi Island, North Maluku, Indonesia. As the company’s employment grows, wastes, including used cooking oil (UCO), accumulate. The result showed that repurposing UCO in PT MSP has lowered the consumption of coal by 2,206 tons (7.53%), diverted 2,980 tCO2e indirect GHG emission (Scope 1), and saved the total cost up to IDR 1,408,231,332.

Analysis of Changes In Risk Management Implementation At PT. ABC Based On ISO 31000:2018

The implementation of a company's risk management is important because it can provide input for management to act preventively to prevent risk events that are often detrimental (downside risk). PT ABC as a subsidiary of the nickel mining company as Parent Company has transformed its risk management from partial to integrated based on ISO 31000: 2018. This change must be well prepared to avoid delays in the integration process because PT ABC has a project to develop the Industrial Estate and the RKEF (Rotary Kiln Electric Furnace) Smelter Development with a significant value so that preventing losses by carrying out risk mitigation efforts is important to implement. The purpose of this study is to comprehensively analyze changes in the application of risk management at PT ABC, evaluate the application of risk management adopted by the company, identify challenges faced by the company, and analyze the application of risk management to current business activities. The research method uses primary data through direct observation of existing change preparation practices and uses secondary data from related company data. The basis of the risk method used is the ISO 31000: 2018 guidelines. The results showed a significant impact in the integration of risk management adopted to be more comprehensive than the previous implementation. The risk management ntegration factor of the Parent Company and its subsidiaries has consequences for the sustainability of the program and budgeting in the RKAP, especially for improving the quality of risk management analysis through risk awareness programs. The implementation of PT ABC risk management in the RKEF smelter construction project identified 8 aspects of risk which include investment taxonomy (5 aspects), regulatory changes (1 aspect), and environment (1 aspect). Risk mitigation efforts have been carried out in the risk map from 1 aspect of high risk; 5 aspects of medium risk and to reduce the impact and probability that exists, namely: 3 risk aspects (from medium to high) and 5 risk aspects (from low to medium). This shows that there is a fairly good readiness to anticipate risks that have a negative impacts.

Enhancing Rotary Kiln-Electric Furnace Process of Saprolitic Laterite from the Viewpoint of Slag Optimization to Minimize Energy Consumption

Enhancing Rotary Kiln-Electric Furnace Process of Saprolitic Laterite from the Viewpoint of Slag Optimization to Minimize Energy Consumption

Isothermal reduction kinetics and microstructure evolution of various vanadium titanomagnetite pellets in direct reduction

Vanadium titanomagnetite (VTM) pellets is an important charge for utilizing VTM through the rotary kiln-electric furnace process, and its reduction characteristic is essential to industrial production. This paper investigated the reduction behaviors and mechanism of three types of fired VTM pellets, i.e. PA, PB and PC with 13.02%, 11.70% and 5.25% TiO2, respectively. Under the optimal conditions, which were reduced at 1423 K for 150, 120 and 100 min, respectively, they obtained more than 90% reduction degree. During reduction, PA exhibited excellent resistance to volume swelling and great morphology, while PB and PC displayed abnormal swelling and structural damage. Kinetic and microstructure studies indicated that the reduction of PA, which consisted of titanohematite and pseudobrookite, was controlled by the random nucleation and subsequent growth of metallic iron, whereas that of PB and PC, which mainly contained titanohematite, was controlled by intrinsic chemical reactions. Iron- and titanium-bearing oxides were reduced to metallic iron via two routes: titanohematite → titanomagnetite → wustite → metallic iron and pseudobrookite → metallic iron. These various compositions and grain sizes of iron- and titanium-bearing oxides led to different generation rates and morphologies of metallic iron, directly affecting the reduction characteristics and macroscopic performance of VTM pellets.

Literature Review: Comparison of Caron Process and RKEF On The Processing of Nickel Laterite Ore For Battery

Indonesia has abundant resources, especially in natural resources (SDA), one of which is nickel. Nickel is a metal that is loved by many people because of the rapid development of technology in creating electric transportation, in particular, the application of nickel is one of the batteries. Nickel resources in the world are available in the form of Nickel Oxide as much as 60% and the remaining 40% is available in the form of sulfide reserves. Currently, there are 2 extraction methods, namely hydrometallurgy (Caron Process) and pyrometallurgy (Rotary Kiln Electric Furnace). Hydrometallurgy is a process used for nickel ore that has a grade of < 1.5%, while pyrometallurgy is still used for nickel ore that has a Ni content of < 3%. At present, the most common hydrometallurgical process is applied to limonite nickel ore. While the extraction process in pyrometallurgy uses saprolite nickel ore. Nickel metal processing, currently the best and the cheapest in terms of production costs is the hydrometallurgical process followed by the pyrometallurgical process. Using low-grade nickel is more suitable for manufacturing battery manufacture. The reason is that the Limonite Nickel reserves are more and can increase the selling value of the nickel ore. Thus, it is necessary to pay attention to the development in the processing process to increase the purity of the nickel-metal itself.

From Nickel Ore to Ni Nanoparticles in the Extraction Process: Properties and Application

Laterite nickel ore is a mineral rock, which contains iron–nickel oxide compounds. One processing technology proposed to treat the ore is the Caron process. In general, the Caron process combines pyrometallurgical and hydrometallurgical stages. In the pyrometallurgical step, the ore mixed with reductant is heated up to 1800 °C in a rotary kiln-electric furnace to transform iron–nickel oxide into iron–nickel alloy. In the hydrometallurgical stage, nickel has to be dissolved selectively using ammonia solution (alkaline). The further process is aimed to separate and purify the nickel in ammonia solution using solvent extraction and precipitation. The disadvantages of the pyrometallurgical stage in the Caron process include high-energy consumption, low economic value, and technical problems such as partially melted material, which hinders the further process. While in the hydrometallurgical stage, the extensive use of ammonia causes an environmental impact. Selective reduction is proposed to solve problems in the pyrometallurgical stage. Selective reduction is a process favouring the formation of iron oxide to obtain high nickel content in an intermediate product with less energy consumption. An additive is added to the ore to reduce selectively the nickel and decrease the reaction temperature. To solve the environmental impact of ammonia, a novel and safer chemical is proposed as a substitute — the monosodium glutamate (MSG). Selective reduction combined with alkaline leaching using MSG is proposed as an alternative to the Caron method. Precipitation is employed further to purify the nickel that results in nickel nanoparticles with 90–95 wt.% purity.

A comprehensive kinetic investigation on sulfur deportment during nickel laterite calcination using model-free, model-fitting, and master plot approaches

The rotary kiln-electric furnace process is the most common method for ferronickel production from laterite ore. Since sulfur deteriorates the mechanical properties of ferronickel, it is essential to examine the routes through which sulfur is transferred to the nickel-containing product during the extraction process. Oxidation of fuel (e.g., coal) in the calcination kiln emits SO2, which results in sulfur transfer from the gas to the calcine. In this investigation, coal combustion atmosphere was mimicked by purging N2-CO-CO2-SO2 gas mixture in the tube furnace. A comprehensive kinetic analysis on the sulfurization of nickel laterite ore was conducted to obtain a fundamental understanding of the rate of the sulfurization reactions. The kinetic investigation was performed by three approaches: model-free, model-fitting, and master plot at various processing times, temperatures, and partial pressures of SO2. The XRD and ICP analyses were used to determine the phase composition and sulfur content of the calcine, respectively. Considering the activation energy values obtained by model-free approach, the process is divided into two steps, before and after 60 min of calcination. Contracting sphere and Avrami Erofeev are identified as the most suitable kinetic models for steps 1 and 2, respectively. Considering the small values of activation energy, 1.4–5.3 kJ/mol, the sulfurization reactions are identified as diffusion-controlled mechanism.

Development of laterite ore processing and its applications

Nickel ore is found in two types sulfide and laterite. The sulfide is a nickel ore that has high nickel content and low reserves of natural resources than of the zinc laterite. In contrast, the laterite is a rock mineral that contains the iron-nickel oxide compounds. There are two methods of processing nickel laterite, namely hydrometallurgy and pyrometallurgy. The former is a method that uses leaching by a chemical solution or solid such as acid, as a reducing agent. The alkaline leaching (ammonia) is the most optimal method to obtain a nickel grade with the highest recovery but it needs more modification. Pyrometallurgical method uses high heat up to 1800°C, so it requires a lot of energy and needs improvement to decrease the carbon usage. The rotary kiln-electric furnace method is the optimal method for developing the nickel laterite. These methods generate products that can be applied to various fields. For example, the pyrometallurgy method produces nickel pig iron and ferronickel as raw materials for stainless steel and steel alloys. The hydrometallurgy method produces nickel sulfate and nickel oxide with a purity of 99% by weight as raw materials for magnets, sensors, and batteries. Hence, the hydrometallurgy method still needs improvements for the environmentally friendly reagent. Therefore, bioleaching will be a nickel laterite leaching process in the future by using bacteria as the reducing agent.

Large- and Particle-Scale energy assessment of reduction roasting of nickel laterite ore for Ferronickel production via the rotary Kiln-Electric furnace process

• Mineralogical composition and moisture content govern energy consumption. • Dehydroxylation and drying use around one-third of the energy input. • Energy and exergy efficiencies amount to 66.4% and 32.3%, respectively. • Dehydroxylation, drying, and size define intraparticle temperature gradient. Ferronickel is essential in manufacturing austenitic stainless steels, nickel alloy steels, batteries, electronics, and gas turbines, among other crucial products. The Rotary Kiln-Electric Furnace process is a widely recognized pyrometallurgical route for ferronickel production. This paper focuses on the rotary kiln furnace, an intermediate stage in which partially dried minerals convert into calcine, ready for smelting in an electric arc furnace. This paper uses a unique industrial database that contains operation variables and minerals composition of a 180 t h −1 rotary kiln furnace. As a distinguishing feature, this work incorporates the effects of dehydroxylation reactions and uses intraparticle energy analysis to gain further insights into the reduction roasting process. Goethite and serpentine dehydroxylation reactions consume around 18% of the energy input of the rotary kiln furnace. Flue gases and shell losses represent around 25% and 8% of the energy input, respectively, while the vaporization of free moisture consumes nearly 15% of the energy input. The rotary kiln furnace shows energy and exergy efficiencies of 66.4% and 32.3%, respectively, leaving room for waste heat recovery. Particles with surface-to-center distances lower than 5.0 mm could behave as isothermal, while coarser particles could present significant temperature gradients. These results can assist in optimizing operating conditions and provide insights into the thermal effects of the ore mineralogical composition.

Effect of temperature patterns on iron nugget formation in fluxless processing of titanomagnetite

The technology used to process titanomagnetite is currently limited to the rotary kiln-electric furnace. Other techniques are being developed, including the separation of iron in the form of iron nugget from the reduction of titanomagnetite with coal without any flux addition. The effect of different temperature patterns on the formation of iron nuggets from titanomagnetite was studied. The initial temperature was varied from 700 to 1380 °C, while the final temperature was kept constant at 1380 °C. The experiment results showed that the initial temperature affected the formation of iron nuggets. Initial temperatures of 700–1100 °C produced many iron nuggets up to 3 mm in size and an initial temperature of 1200 °C produced one nugget with a size of about 4 mm. Initial temperatures of 1300 and 1380 °C did not produce any iron nuggets due to the formation of metallic iron crust on the surface of the reduced briquettes. The optimum initial temperature was 1000 °C to achieve high iron recovery in the nuggets.

Transient operation effects on the thermal and mechanical response of a large-scale rotary kiln

Rotary kilns are central equipment in material processing operations such as oxide ore reduction, clinker manufacturing, and hazardous waste incineration. This work focuses on an industrial-scale rotary kiln for Ferronickel production via the Rotary Kiln-Electric Furnace (RKEF) process. Rotary kilns are prone to mechanical failure exacerbated by thermal effects, mainly during transient operation, such as preheating and cooling. However, few studies have tackled the impact of the transient operation on the stress state in the rotary kiln wall. Therefore, we evaluate the thermal and mechanical behavior of the rotary kiln wall during preheating. Actual operation data and a thermal model enable to obtain the temperature distribution along the kiln length. This temperature distribution is the starting point for calculating the stress state of the shell and refractory. The maximal thermal gradient occurs at 10 m from the hot end, with temperatures at the outer and inner surfaces of 200 °C and 820 °C, respectively. The von Mises stress shows a maximum of 121 MPa at the wheel position in the hot region of the refractory and a range of 30–60 MPa in the shell. In addition, the compressive stress is higher than the ultimate compressive strength of the refractory. However, it does not necessarily represent refractory detachment due to the plastic deformation undergone by the refractory under high temperatures. This work paves the way towards developing a tool for accurately predicting rotary kiln mechanical failure, which can help optimize operating conditions and assist in programming maintenance.

Metallurgical Research and Its Contribution to Industrial Development

Metallurgical Research and Its Contribution to Industrial Development

Improving the rotary kiln-electric furnace process for ferronickel production: Data analytics-based assessment of dust insufflation into the rotary kiln flame

Ferronickel contains 60–80 wt% Fe and 40–20 wt% Ni and is a feedstock for manufacturing stainless steel and other ferrous alloys. The primary pyrometallurgical route to produce ferronickel from laterite nickel ores is the Rotary Kiln-Electric Furnace (RKEF) process. In the RKEF process, minerals undergo calcination and partial reduction in a rotary kiln. Large amounts of mineral dust leave the kiln entrained in flue gases. Dust insufflation is a potential solution in which dust particles enter directly into the burner flame. The aim is that the insufflated dust softens, agglomerates, and finally joins the minerals stream that goes into the electric furnace. We applied data analytics techniques to a 1-year operation database to assess the operation before and after dust insufflation in an industrial rotary kiln furnace. Bootstrapping revealed statistically significant differences in the operation with and without dust insufflation. Principal Component Analysis (PCA) and k-means clustering were used as exploratory techniques. PCA showed subsets of variables that significantly influence the dataset variance, and k-means allowed distinguishing operation conditions for dust insufflation with encouraging results for the calcine-to-fresh mineral and the natural gas-to-calcine ratios. These results pave the way towards successfully implementing dust insufflation in the RKEF process.

Effective and economical treatment of low-grade nickel laterite by a duplex process of direct reduction-magnetic separation & rotary kiln-electric furnace and its industrial application

An innovative technical route has been proposed to improve recycling efficiency of Ni and Fe from low-grade nickel laterite via the duplex process between direct reduction-magnetic separation and rotary kiln-electric furnace. The results indicated that the high‑nickel concentrates produced from direct reduction-magnetic separation process, which were combined with optimization of slag types can not only increase the grade of furnace burdens and decrease quantity of slag, but also improve the fluidity of slag and smelting efficiency as well as reduce the power consumption of smelting. For the industrial application of duplex process, a preferable stainless-steel master alloy with 10.02% Ni was obtained at a lower cost of 8420 RMB/t than that of 8731 RMB/t for a stainless-steel master alloy containing 8.14% Ni in conventional rotary kiln-electric furnace process, and the recovery of nickel also increased from 91.27% to 95.51%, which shows an obvious superiority for treating the low-grade nickel laterite.

Investigating the Effect of Temperature on Sulfur Deportment in Nickel Laterite Calcination

The majority of the ferronickel production from nickel laterite ores is through the Rotary kiln- electric furnace (RK-EF) process. Calcination and partial reduction of the laterite ore is typically carried out in a rotary fuel fired furnace. Sulfur is one of the most deleterious impurities in nickel alloys and degrades the mechanical properties of the product. Considering the insubstantial concentration of sulfur in laterites, it is assumed that sulfur partially originates from added fuel and reductant in the calcination stage. Investigating the effects of the temperature in the calcination stage on the sulfur distribution can provide valuable information on controlling the level of sulfur in the calcine. In this study, the atmosphere resulted from coal combustion is simulated by purging a gas mixture of N2, CO, CO2, and SO2 to the electrical horizontal tube furnace. The effect of temperature (600, 700, 800, and 900 ⁰C) on the sulfur deportment was studied. Inductively coupled plasma optical emission spectrometry (ICP-OES), and X-ray diffraction tests were used to measure the sulfur content and identify the phase composition of the products. The dominant compound of the calcine that contains sulfur is identified as pyrrhotite. Raising temperature from 600 to 700 ⁰C, increases %S in the calcine from 0.29 to 0.34%; however, promoting the temperature above 700 ⁰C diminishes the sulfur deportation percentage because of decreasing the surface area of solids by recrystallization of magnesia silicate compounds and sintering of oxides.

Control of slag formation in the electric furnace smelting of ferronickel for an energy-saving production

Two-thirds of the global nickel output can be attributed to the rotary kiln-electric furnace process. Due to the high contents of MgO and SiO2 in laterite, a high temperature (∼1600 °C) and corresponding energy (approximately 14 GJ/t-ferronickel) are required during the electric furnace smelting. This work verifies the feasibility of decreasing the smelting temperature by controlling the slag formation for an energy-saving production. The slag regulation method was upgraded through the coordination of the quaternary basicity [ = R4 = m(CaO + MgO)/m(SiO2+Al2O3)] and FeO content. The melting temperature was decreased, and the melting rate of the feed was increased after slag control, owing to the generation of diopside and olivine eutectics instead of olivine and pyroxene. The viscosity of the slag was decreased, thus lowering the required smelting temperature. After regulating the quaternary basicity from 0.58 to 0.61 and the FeO content from 5.0 to 12.5 wt% in the final slag, the smelting temperature decreased by 86 °C. The energy consumption decreased from 13.75 to a minimum of 11.16 GJ/t-ferronickel. Furthermore, a long-term industrial practice (annual output: 0.24 million tons of ferronickel) demonstrated that the total energy consumption could be decreased by 0.16 million GJ a year, which is equivalent to reducing carbon dioxide emissions by 45 kilotons a year.

Energy and exergy analyses of pellet smelting systems of cleaner ferrochrome alloy with multi-energy supply

Comprehensive energy and exergy analyses were performed to evaluate the thermodynamic performance of two ferroalloy pellet smelting systems named sintering-preheating-submerge arc furnace (SPSF) and rotary kiln-electric furnace (RKEF). The analyses considered the multi-energy supply and exergy destruction of the systems and identified the avoidable irreversibility of the processes. The energy efficiency of the SPSF and RKEF systems was 54.07% and 42.93%, respectively. The exergy efficiency of the two systems was found to be 28.37% and 30.71%, respectively. The largest exergy destruction of both systems was caused by the alternating current circuit which could be replaced by direct current circuit for better performance. The heat transfer between equipment was the major avoidable exergy destruction in systems. The integration of smelting equipment is a suitable method to reduce the avoidable exergy destruction. The environmental impact of the systems is also evaluated on the basis of resource utilization efficiency, system carbon dioxide emission rate and sustainability index. The SPSF is more environmental-friendly than the RKEF. The effective recycling of the exhaust gas in the preheating shaft kiln could pose significant energy saving. The present work could be employed for decision making on improving the existing smelting systems.

Value added utilization of ferronickel slags as raw materials of 4A zeolite for CO2 reduction

The scale of smelting ferronickel by RKEF (Rotary kiln—electric furnace) process is increasing these years, these untreated ferronickel slags will occupy a large area as accumulation and cause ecological damage. On the other hand, the CO2 emission and global warming are urgent problems to be solved as they have resulted in severe climate change. Carbon Capture and Storage (CCS) technology is considered as a feasible solution to the problem of excessive CO2 emissions, and the key of the CCS is the exploration for adsorbents which are low-cost, efficient and energy saving. We found that it is viable to use ferronickel slag as raw material to synthesize 4A zeolite. Further improvement for the purities of 4A zeolite was also accomplished by optimizing the synthesis conditions via single factor experiments. The as-synthesized sample was characterized in terms of structural morphology, chemical composition and surface properties. The adsorption and adsorption kinetics properties were investigated by thermal gravimetric analyzer and four models, respectively. The results indicated that 4A zeolite has a great performance in the adsorption and separation of CO2/N2 with the high value-added utilization of ferronickel slags which conducts.

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.

The effect of sulfur in rotary kiln fuels on nickel laterite calcination

Rotary Kiln - Electric Furnace (RKEF) process is the most commonly used pyrometallurgical technique for processing nickel laterite ores and is mainly suited for saprolite deposits. Sulfur is one of the harmful elements in crude ferronickel obtained via the RKEF process. Typically, laterite ores contain insubstantial sulfur content; hence, it is hypothesized that most of the sulfur in crude ferronickel originates from the coal added as the fuel and the reductant during calcination in the rotary kiln. This study investigates the role of sulfur content of rotary kiln fuels on the composition of the calcine. The calcination-partial reduction experiments were conducted at 900 °C for a 2-h residence time. Various reducing gas mixtures representing combustion products of rotary kiln fuels (e.g., coal) were contacted with the ore. At constant PCO, the sulfur content of the calcine increases linearly with an increase in PSO2 in the input gas mixture. Similarly, at fixed PSO2, the percentage of sulfur in the calcine and the percentage of sulfur deportation increase with PCO. However, an exceptional case is observed at PSO2 = 0 atm in the input gas mixture; the sulfur content and sulfur deportation slightly decrease by increasing PCO in the input gas. The sulfur content and the percentage of sulfur deportation drop at a lower input flow rate of the reducing gas mixtures.