Rotary Kiln-electric Furnace Process Research Articles

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.

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.

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.

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.

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.

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.

Beta-glucosidase analysis in dried blood collected on filter paper (DBS), report of a new method applied to the population and patients with suspected Gaucher disease (GD)

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.

Respiratory system involvement in Russian patients with mucopolysaccharidosis: Effects of enzyme replacement therapy

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.

（株）日向製錬所におけるフェロニッケル製錬

Hyuga Smelting Co., Ltd. established by Sumitomo Metal Mining Co., Ltd. started production of ferronickel by Sintering-Electric Furnace Process in September; 1956, which is now owned by Sumitomo Metal Mining Co., Ltd.(60%), Nippon Steel Corporation (25%) and Mitsui & Co., Ltd.(15%).In accordance with the rapid increase of the market demands, the company made a steady growth, expanding the production capacity from 30 to 200 tons of nickel per month. Because the further expansion required greater productivity and broader acres, the new plant was built at present site in the coastal industrial quarter adopting Rotary Kiln-Electric Furnace Process in 1968.Since the improvement of the process, the development of new products and the energy curtailment of the whole plant have been achieved, Hyuga Smelter has become one of the most advanced coastal ferro-nickel smelters, boasting of most modern facilities and incompetitive technical knowledge.Production capacity is 1, 500 tons of nickel per month.

Production of FeNi by the rotary kiln-electric furnace process at Hyuga Smelter

Hyuga Smelting Co., established by Sumitomo Metal Mining Co., started the production of ferro-nickel by the sintering-electric furnace process in September 1956. In accordance with the rapid increase in market demands, the company made a steady growth, expanding the production capacity from 30 to 200 tons of nickel per month. Because further expansion required greater productivity and more space, a new plant was built at the present site in the coastal industrial quarter in 1968 adopting the rotary kiln-electric furnace process. Since the improvement to the process, and with the development of new products and the energy curtailment, of the whole plant, Hyuga Smelter has become one of the most advanced coastal ferro-nickel smelters, having the most modern facilities and most advanced technical knowledge. The production capacity is 2,200 tons of nickel per month. This paper briefly reviews the developments in technical knowledge and cost saving: (1) improvement of the ore sizing; (2) substitution of heavy oil and anthracite by bituminous coal; (3) adopting the pelletizing for the treatment of the rotary kiln dust; and (4) energy savings of the electric furnace and its apparatus.

富山昭和電工 (株) におけるフェロニッケル製錬

Toyama Showa Denko Co., Ltd.(TSK) is situated in the industrial area near by the Toyama port. TSK is smelting ferro-alloys such as ferro-nickel, ferro-chromium and ferro-molybdenum, and these products are mainly used for stainless steel making.TSK had been Toyama works of Showa Denko Co., Ltd., but became the subsidiary of Showa Denko Co., Ltd. on January 22, 1979.Since we started ferro-nickel smelting in 1969, we have had much experience about it during more than ten years.At present, we go on smelting ferro-nickel, based on the rotary kiln-electric furnace process. The annual capacity of this process is about 4500 tons of nickel.TSK is dependent for its raw material ores on garnierite obtained from the nickel oxide deposits in areas such as New Caledonia and Indonesia. Garnierite is a rich siliceous ore of which the nickel content varies between 2.3-2.6%. Our process is to calcine these ores in the rotary kiln and to reduce the hot materials in the electric furnace. In this paper, the outline of our smelting process, and improvements of plants are described.