Smelting Temperature Research Articles

Preliminary study on smelting micro-carbon ferromanganese alloy by electro silicon thermal one-step process

Abstract In this paper, the related thermodynamic analysis of the one-step electro silicon thermal smelting process of micro-C-ferroalloy was carried out, and the effects of smelting temperature (T), slag alkalinity (R), silicon ratio (KSi) and holding time (t) on the appearance quality of the alloy, the Mn content, the Si content of the alloy and the Mn element recovery rate were studied. It is concluded that under the conditions of a smelting temperature of 1400°C, the basicity of slag R is 1.2, the silicon addition coefficient KSi is 1.0, the holding time is 60 min, the alloy appearance quality is good, Mn content of the alloy is high, Si content is low, and Mn yield is relatively high. Under laboratory conditions, the Mn yield of the alloy obtained by this method is low, and the thermodynamic equilibrium and reaction kinetics of the alloy melt and slag system of this method still need to be further studied to provide a theoretical basis for the expansion test.

Smelting characteristics of nickel‑chromium‑manganese bearing prereduced pellets for the preparation of nickel saving austenite stainless steel master alloys

Nickel saving austenite crude stainless steel master alloys were innovatively produced by smelting of nickel‑chromium‑manganese bearing prereduced pellets in an effective and economical way. The thermodynamics analysis and systematic process mineralogy were also conducted to further reveal the smelting characteristics of prereduced pellets and the related enhanced mechanism. The results showed that the preferable stainless steel master alloys with 66.29% Fe, 4.21% Ni, 17.28% Cr, 6.53% Mn and 4.76% C can be prepared from the nickel‑chromium‑manganese bearing prereduced pellets with a corresponding recovery of valuable metals more than 95%. Furthermore, during the enhanced smelting process, the optimization of slag types can further realize the phases transformation from high-melting-point enstatite and forsterite to low-melting-point diopside and monticellite to obtain a decreased smelting temperature and viscosity of slag. The smelting duration and the alloy grain included in the smelting slag were both obviously decreased, resulting in an improved smelting performance.

A Study on Smelting Temperature through analysis of Slag Excavated from Iron Manufacturing Remains on Site of Jangamjinseong in Seocheon, Korea

This study studied the smelting temperature by the principal components, crystal structure, microstructure, and differential thermal analysis on four slags excavated from iron manufacturing remains on site Jangamjinseong in Seocheon, Korea. As a result of the principal component analysis, the content of the T⋅Fe and Deoxidation agent which was the same as the characteristics of the direct smelting slag. As a result of the crystal structure analysis, Fayalite(Fe<sub>2</sub>SiO<sub>4</sub>) and Wustite(FeO) were detected. and as a result of microstructure analysis, Fayalite and Wustite were present on the Glass Matrix. As a result of differential thermal analysis, Fayalite was melted at an endothermic peak of 1,132.0°C. At 1,370.0°C, Wustite was melted. In No. 2, it was found that Fayalite melted at an endothermic peak of 1,096.0°C, and Wustite melted at 1,311.0°C. As a result of the analysis of the FAS ternary phase diagram and the FCS ternary phase diagram, the smelting temperature range was 1,150.0 to 1,250.0°C. The FeO-SiO<sub>2</sub> binary state is also a range in which Fayalite is melted on Wustite + Fayalite to become a Wustite + Liquid phase. When combined with the results of differential thermal analysis, the range of the smelting temperature is 1,096.0°C to 1,370.0°C. To sum up all the results of the analysis, the steel relics in the site of Jangamjinseong in Seocheon used a direct smelting method, and were carried out in the range of 1,096.0℃ to 1,370.0℃ during the process.

Reduction-Sulfurization Smelting Process of Waste Hydrogenation Catalysts, Automotive Exhaust Purifier Waste Catalysts, and Laterite Nickel Ore.

Reduction-sulfurization smelting is an effective method for treating solid hazardous waste and recovering valuable components from them. In this work, a waste hydrogenation catalyst (WHC), an automotive exhaust purifier waste catalyst (AEPWC), a vulcanizer, and laterite nickel ore were mixed, and the reduction smelting behavior of this solid waste was investigated. XRD (X-ray diffractometry), TG-DSC (thermogravimetric/differential scanning calorimetry), SEM-EDS (scanning electron microscopy-energy dispersive spectroscopy), OM (optical microscopy), and ICP-OES (inductively coupled plasma-optical emission spectrometry) methods were used to examine the chemical composition, thermal stability, structure, and morphology, as well as the metal content of the samples. Under the Al2O3-FeO-SiO2 ternary slag system, at a smelting temperature of 1450 °C, smelting time of 2 h, mass ratio of coke, pyrite, and CaO to waste catalysts of 16, 25, and 0%, respectively, nickel (Ni) and molybdenum (Mo) recovery reached 91.1 and 92.9%, respectively, where average PGMs (platinum group metals, platinum (Pt), palladium (Pd), rhodium (Rh)) recovery reached 96%, although vanadium (V) recovery was only 25.1%. The characterization of the slag shows that Al, Si, and Fe are mainly bound in the form of chemical compounds, while V is intercalated with ferro- or aluminosilicate, which hinders the reduction and sulfurization of V. A series of tests using reduction smelting without sulfurization were also conducted, after which the Ni, Mo, and V recovery reached 96.8, 96.6, and 89.7%, respectively, while PGMs (Pt, Pd, Rh) recovery ranges from 90.2 to 98.0%. The collaborative disposal of primary ore and multisource solid waste has been achieved through two process paths: reducing smelting and reducing sulfurization smelting, which provide reference for the collaborative smelting of multisource secondary resources.

Efficient recycling of silicon cutting waste for producing high-quality Si-Fe alloys.

A tremendous amount of silicon cutting waste (SCW) is being produced during slicing Si ingots, which leads to a great waste of resources and serious environmental pollution. In this study, a novel method that recycling SCW to produce Si-Fe alloys was proposed, which not only provides a process with low energy consumption, low cost, and short flow for producing high-quality Si-Fe alloys but also achieves a more effective recycling of SCW. The optimal experimental condition is investigated to be a smelting temperature of 1800°C and a holding time of 10min. Under this condition, the yield of Si-Fe alloys and the Si recovery ratio of SCW were 88.63% and 87.81%, respectively. Compared with the present industrial recycling method that uses SCW to prepare metallurgy-grade Si ingot by an induction smelting process, this Si-Fe alloying method can achieve a higher Si recovery ratio of SCW at a shorter smelting time. The promoting mechanism of Si recovery by Si-Fe alloying is mainly expressed as follows: (1) facilitating the separation of Si from SiO2-based slag; (2) reducing the oxidization and carbonization loss of Si by accelerating the heating of raw materials and reducing the exposed area of Si.

Direct Evidence for Phase Transition Process of VC Precipitation from (Fe,V)3C in Low-Temperature V-Bearing Molten Iron

V-bearing molten iron was obtained by adding Na2CO3 in the smelting process of vanadium titanomagnetite at low temperature. Two forms of V-rich carbides ((Fe,V)3C, VC) were detected in the V-bearing pig iron products. Once the smelting temperature was above 1300 °C, most of the V in the raw ore was reduced into molten iron. Owning to the high content of V, the unsteady (Fe,V)3C solid solution decomposed along with the precipitation of graphite and VC during the solidification process. The presence of VC cluster and VC precursor in (Fe,V)3C was detected by transmission electron microscopy, which confirmed the possibility of this transition process at the atomic perspective. The transformation dramatically affected the compositions and properties of V-bearing pig iron and had important guiding significance for the actual production process.

Distribution behavior and deportation of arsenic in copper top-blown smelting process

In recent years, the impurity content in copper concentrate increases gradually with the consumption of high-grade copper ore. When the arsenic content in the raw materials increases, large amounts of arsenic enter the sulfuric acid system, resulting in large amounts of waste acid that put great pressure on production and environmental protection. Using the distribution characteristics of arsenic in each phase, the possibility of enriching arsenic in the form of stable arsenates in the slag was investigated to enrich arsenic in the form of stable arsenates in the slag. It is shown that increasing CaO content in slag at relatively low temperatures, controlling the slag type and changing the slag composition effectively improved the ability of the slag to absorb arsenic. Based on a theoretical analysis used to optimize the process parameters and determine a reasonable slag type, an oxygen-enriched top-blown smelting experiment was conducted with mixed copper concentrates. The mechanism of arsenic fixation in smelting slag at a smelting temperature of 1180 °C (1453 K) was investigated, and the results showed that the As content in slag was increased by 20∼50% and decreased by 10∼30% and 10∼20% in the dust and matte, respectively. Thus, arsenic is fixed in silicate in the form of stable arsenate, which can be an effective and safe treatment solution for copper smelting processes.

Thermal Effect and Metallurgical Characteristics of Hydrogen Bottom Blowing in Top–Bottom Combined Blowing Converter

A new technology of hydrogen bottom blowing instead of traditional argon blowing in the current converter steelmaking process is proposed herein, in the aim of overcoming problems such as energy shortages caused by increased scrap charging, the low stirring intensity of bottom blowing, high CO2 emissions, and endpoint carbon content control. The thermal effect and metallurgical characteristics of hydrogen bottom blowing were investigated based on the production data of a steelmaking converter in Pangang Group Xichang Steel & Vanadium Co., Ltd. This study shows that hydrogen bottom blowing at an intensity of 0.1–0.5 m3·min−1·t−1—rather than argon blowing at an intensity of 0.1 m3·min−1·t−1—can increase the smelting temperature by 16–73 K, increase the scrap charging ratio by 0.89–5.19%, and reduce CO2 emissions by 19.79–115.96 kg per ton of steel. Intensive hydrogen blowing could significantly reduce the oxygen content of molten steel in the late stage of steelmaking and be beneficial to controlling oxygen at the endpoint. Hydrogen can also reduce the (FeO) content in slag, and the equilibrium partial pressure ratios of H2O/H2 for the reaction H2 + (FeO) = H2O + Fe in the middle and late periods are 0.41 and 0.11, respectively. Hydrogen can also slightly suppress the decarbonization reaction in the late period of steelmaking, and the equilibrium partial pressure ratio of H2O/H2 for the reaction H2 + (CO) = [C] + H2O in the late period is 9.65 × 10−2, which means that hydrogen is beneficial in preventing the rapid decrease in [C] and, in turn, helps control the endpoint carbon content. By comparing the degree of the reaction (P2O5) + 5H2 = P2(g) + 5H2O and the reaction (P2O5) + 5H2 = 2[P] + 5H2O, it can be seen that intensive bottom-blown hydrogen may have a slight positive effect on slag gasification dephosphorization. The FactSage simulation results further verify the conclusions of the above analysis.

Recovery of Rare Earth Elements from Spent NdFeB-Magnets: Separation of Iron through Reductive Smelting of the Oxidized Material (Second Part)

This paper proposes a pyrometallurgical recycling method for end-of-life NdFeB magnets by oxidizing them in air and subsequently smelting them. The smelting process enabled the recovery of rare earth elements (REEs), producing a new reach concentrate separating the iron as a metallic phase. From the products of smelting, the metallic phase showed a maximum Fe content of 92.3 wt.%, while the slag phase showed a maximum total REE (Nd, Pr, and Dy) content of 47.47 wt.%, both at a smelting temperature of 1500 °C. ICE-OES and XRD analysis were conducted on both phases, and results showed that the metal phase consists mainly of Fe and Fe3C while the slag phase consists of the RE-oxides, leftover Fe2O3, and a mixture of Fe6Nd4. The obtained slag concentrate based on the oxides of rare earth elements is suitable for further pyrometallurgical or hydrometallurgical treatment in order to obtain rare earth elements.

Analysis on Ancient Bloomery Ironmaking Technology: The Earliest Ironmaking Evidence in the Central Plains of China Was Taken as the Research Object

The slag found in Hengdong Jiangxian County, Shanxi Province has been recognized by archaeologists as the earliest evidence of bloomery ironmaking in China. The slag was characterized and analyzed by chemical titration, inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS), and tescan integrated mineral analysis (TIMA). The smelting technology in ancient China was explored, combined with thermodynamic theory. The results of chemical titration shown that the total Fe was as high as 64.18%, which means that it was very difficult to produce iron on a large scale with the ancient bloomery ironmaking technology, consuming a lot of iron ore while producing very little iron. The distribution of FeO was relatively dispersed, while that of Fe2O3 particles was concentrated and large. The source of Fe2O3 in the slag can be roughly identified as the oxidized metallic iron, which could not be separated in the slag in the past. Tescan integrated mineral analysis (TIMA) images show that Fayalite and Wustite are the main phase forms in smelting slag. The existence of fayalite proves that the temperature of a slag system should reach the condition of liquid phase formation during the smelting process. Based on the characterization results, the metallurgical conditions of the slag at that time are inferred by FactSage7.1. The theoretical smelting temperature was between 1150 °C and 1200 °C. The fayalite and aluminosilicate in the slag had obvious displacement and inhomogeneity, which pointed to the forging temperature ranging from 1050 °C to 1100 °C.

Optimal System for Improved Internal Model Control of Argon-Oxygen Decarburization Process Based on the Piecewise Linear Model and Time Constant of Filter Optimization

This paper presents an improved internal model control system to raise the efficiency of refining low-carbon ferrochrome. This control system comprises of a piecewise linearized transfer function and an improved internal model controller based on optimized time constant of the filter. The control system is mainly used to control the oxygen supply rate during the argon-oxygen refining for controlling the smelting temperature. The regulatory performance and servo of two closed-loop control schemes are compared between the improved internal model controller based on the optimized filter time 0000-0002-7606-6546and the internal model controller based on the fixed filter time constant. The simulation analysis shows that the piecewise linearized model and the optimization of the time constant of the filter improves the response time, stability, and anti-interference ability of the controller. Then, the proposed improved internal model controller is used to adjust the gas supply flow in 5 ton AOD furnace to control the smelting temperature. Ten production tests performed the effectiveness of the controlling refining optimal system. The analysis of the experimental data shows that the improved internal model control system can shorten the melting time and improve the melting efficiency. Thus, the application of the improved internal model control system in low-carbon ferrochrome refining is an interesting potential direction for future research.

Corrosion mechanism of magnesia-chrome and alumina-chrome refractories in E-scrap smelting

Pyrometallurgical processes have been widely recognised as the preferred technology for E-scrap recycling, and E-scrap smelting is usually accompanied by the formation of high-Al2O3-content slag. However, this slag can cause problems, such as refractory wear and even accelerated failure. Therefore, the corrosion mechanism of magnesia-chrome and alumina-chrome refractories in contact with FeOx-SiO2-CaO-Al2O3 smelting slag was experimentally studied in the range of 1300–1400 °C, in air (pO2 = 0.21 atm) and at pO2 = 10-7 atm. The results showed that refractory-component dissolution and new phases formation were the major causes of refractory degradation. The dissolution of the refractory components increased along with both increasing temperature and decreasing Al2O3 concentration in the initial slag. When decreasing the pO2, the dissolution of MgO and Al2O3 into the slag slowed down. New phases such as forsterite, anorthite, and spinel were detected at the interface between the slag and the bulk refractory. The formation of forsterite accelerated the refractory wear, whereas the newly formed (MgO,FeO)·(Cr2O3,Fe2O3,Al2O3) spinel phase acted as a protective layer against further corrosion. A lower Al2O3 concentration in the slag and a higher smelting temperature both densified the formed spinel layer. Additionally, a high oxygen partial pressure was beneficial to the formation of spinel in the magnesia-chrome refractory corrosion experiments. However, a low oxygen partial pressure was favourable for the formation of spinel on the surface of the alumina-chrome refractory materials. This study provides useful information for designing refractory materials and optimizing the processing parameters of E-scrap smelting.

Reduction Smelting Experiment of Copper Dross with Low Copper Content

Copper dross with less copper content was used as raw material for reduction smelting experiment, and the effects of the amount of coke fines dosage, the reduction smelting temperature, and the reduction smelting time on the distribution of the main elements in the copper dross between the various layers were investigated by the bath smelting process during the reduction smelting process. The optimum experiment conditions were as follows: the number of coke fines was 0.1% of the mass of copper dross, the smelting temperature was 1250 °C, and the smelting time was 90 min. Under this condition, the medium frequency furnace was used to carry out the pilot experiment of copper dross, and the experiment results were similar to the laboratory results. Copper dross achieved the separation of valuable metals through reduction and smelting, and obtains four kinds of materials such as crude lead, matte, slag, and smoke dust. Metal lead, silver, and arsenic were mainly concentrated in the crude lead, sulfides such as lead sulfide, cuprous sulfide, and ferrous sulfide were mainly concentrated in matte copper, lead oxide, and slag-forming elements were mainly concentrated in slag, and lead oxide was mainly concentrated in smoke dust.

Integrated carbothermic smelting – Acid baking – Water leaching process for extraction of scandium, aluminum, and iron from bauxite residue

A closed-loop valorization process, combining carbothermic smelting and acid baking – water leaching was developed to recover scandium, aluminum, and iron from bauxite residue, a major side product of aluminum production. This process employs carbothermic smelting to recover 99% of the iron in the starting residue as crude metallic iron, which can be separated from slag that contains aluminum and scandium. Composition of slag was found to be primarily dependent on the smelting temperature and amount of smelting flux added. At high smelting temperatures (1600 °C), sodium was found to evaporate from slag, potentially enabling sodium separation and recovery. The slag was treated by acid baking – water leaching, to convert scandium and aluminum to soluble sulfate species, allowing recovery. The single-pass acid baking – water leaching was optimized to achieve 99% scandium and 47% aluminum extraction by employing sulfuric acid at a ratio of 1.25 gH₂SO₄/g, baking at 150 °C for 2 h, and water leaching at ratio of 7.5 mLH₂O/g for 210 min. The production of solid leaching residue was avoided by employing thermal desulfation at 1400 °C to remove 84% of leaching residue sulfur content thereby potentially allowing regeneration of sulfuric acid for acid baking and producing a recycled smelting flux that would reduce reagent consumption and would allow recapturing the scandium and aluminum not recovered during leaching. This closed-loop process enables efficient and sustainable recovery of scandium, iron, and aluminum from bauxite residue, and constitutes first steps in an integrated process for sustainable valorization of bauxite residue, supporting efforts to develop a zero-waste economy.

Effect of phosphorus on interface characterization of steel–copper bimetals in solid–liquid composite casting

Carbon steel and Cu-Pb-Sn bimetallic samples were prepared by the solid–liquid composite method. The preheating temperature of the steel matrix was 1150 ± 30 °C and the Cu-Pb-Sn alloy smelting temperature was 1200 ± 20 °C. The Cu-Pb-Sn alloy was subsequently poured into the preheated steel matrix to form a bimetallic composite interface. The influence of phosphorus (P) on the microstructure and mechanical properties of the interface and the behavior mechanism of P at the bimetallic interface were examined. The results showed that when the P content was 0.1% (all contents reported herein are in wt%), the carbon steel and Cu-Pb-Sn alloy formed an ideal metallurgical bonding interface. It was found that a nanoscale Fe3P phase was precipitated at 750 °C at the grain boundary of the ɑ-Cu interface. The Fe3P interplanar spacing of the phase was 2.1 Å, and the interplanar spacing of ɑ-Cu was 2.07 Å. When the P content reached 0.2%, the Fe3P phase precipitated at 1020 °C and aggregated into micrometer size at the interface, which formed a transition zone with ɑ-Cu. The transition zone widened with an increase in the P content in the alloy liquid. The interface atomic diffusion distance between Fe and Cu was 11.55 µm when the P content was 0.1%, and the sample shear strength reached a maximum value of 157.89 MPa. With increasing P content, the interface became hard and brittle because it emerged in the precipitated transition zone, which decreased the shear strength.

Efficient recycling of silicon cutting waste by Al[sbnd]Si alloying with the assistance of cryolite

Silicon cutting waste (SCW) generated during Si wafers producing process can be recycled by AlSi alloying process. However, the presence of O in SCW has a detrimental impact on recycling process. In this study, cryolite was introduced to eliminate the hindrance of O. The influences of smelting temperature and the amount of cryolite additive on the yield of the blocky AlSi alloys and the Si recovery ratio of the SCW have been investigated and the alloying conditions were optimized to a smelting temperature of 1000 °C and a cryolite/SCW mass ratio of 0.8, achieving a AlSi alloys yield of 95.99% and a Si recovery ratio of 84.77%, which were far greater than those without cryolite additive. The results showed that the addition of cryolite additive can effectively improve the smelting effect and reduce the alloying temperature. Furthermore, the action mechanism of cryolite in Al-SCW system was analyzed, and the results revealed that the molten cryolite can dissolve the generated Al2O3 existing on the surface of AlSi alloy droplets and finally contributes to the aggregation of these droplets. This method has advantages including high Si recovery ratio of SCW, low alloying temperature and simple technological process.

Role of amount of council and diameter of copper on metal smelting temperature

This paper discusses the role of the number of turns and the diameter of copper wire on metal melting temperature. The aim is to determine the effect of the number of turns and wire diameter on the temperature produced in the metal smelter. The method used by testing using the number of turns referred to is 20 turns, 25 turns, 30 turns, and a wire diameter of 1 mm, 1.5 mm and 2 mm. The results of the average value of the number of turns that vary, where the number of turns (30) has the highest average temperature value of 681.11 ° C, while the number of turns (25) produces the lowest average temperature of 648.22 ° C, the number of turns (20) the averagetemperature value is 651.11 ° C. and the larger the coil wire diameter is used, the higher the temperature produced. At 2mm, the coil wire diameter has the highest average temperature value of 691.11 ° C, while the coil wire diameter of 1.5mm has the highest average temperature value of 691.11 ° C. The average temperature value is 667.22 ° C, then the coil wire diameter of 1 mm has the lowest average value of 622.11 ° C

Slag Activation in the Carbothermic Reduction of Phosphorite with Adding Micronutrient-Bearing Cosolvents

High smelting temperature of phosphate ore and low activity of the slag lead to energy-extensive consumption and large solid waste generation in the yellow phosphorus industry. Micronutrient-bearing cosolvents were added to the reduction smelting process of phosphate ore to reduce the smelting temperature and increase the activity of slag in the current work. Thermodynamic analysis demonstrated that B2O3 and K2O as cosolvents can decrease the melting temperature, promote the liquid phase formation and reduce the slag viscosity. In addition, cosolvents had no unfavorable effect on the reduction volatilization of phosphate ore, and the volatilization ratio of phosphorus was > 97 wt.% at 1550°C for 1 h. In this case, the value of slag was enhanced with the addition of cosolvents, and the activation ratios of micronutrients were > 90%. Resultantly, no solid waste was generated since the activated slag can be regarded as a favorable ingredient for the crop fertilizer.

Smelting Reduction Characteristics and Mechanism of Vanadium–Titanium Magnetite Carbon-Bearing Pellet

Vanadium–titanium magnetite is one kind of important strategic resources. However, there exist some common problems in the current smelting process of vanadium–titanium magnetite. In the present paper, we propose the rotary kiln pre-reduction and bath smelting process reasonably for smelting vanadium–titanium magnetite. The smelting reduction test of vanadium–titanium magnetite carbon-bearing pellet in the bath was conducted under laboratory condition, and the effect of end slag basicity, the smelting temperature, the smelting time and the amount of pulverized coal on the separation of slag–iron and the quality of hot metal were mainly investigated. The results showed that the reasonable smelting parameters for vanadium–titanium magnetite smelting of the process introduced in the paper were above 1450 °C of smelting temperature, above 0.8 of basicity of slag, 30–40 min of smelting time and 20–22% of coal addition. Nevertheless, the sulfur content of the iron particle was higher than the demand of steelmaking and it needed further desulfurization. The process is economically feasible for smelting vanadium–titanium magnetite, which can recover the vanadium and titanium resources effectively.

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.