Coke Rate Research Articles

Consequence of natural gas injection in blast furnace: a critical appraisal using a thermodynamic and evolutionary computation approach

ABSTRACT The data generated from a model-based simulator are used in this study for evolutionary multi-objective Optimisation, correlating input parameters like natural gas and pulverised coal injection with coke rate, carbon rate and fuel cost. Evolutionary optimisers are used to minimise coke input and total fuel cost and corresponding CO2 emissions were analysed. Co-injection of gas with coal in a blast furnace generally lowers furnace CO2 emissions by increasing hydrogen in the input fuel. This study reveals that major emission reduction possibilities at the lowest optimised coke rate and total fuel cost do not exist when coal and gas co-injection is attempted. A tri-objective Optimisation study was also conducted for simultaneous minimisation of coke rate, carbon rate and fuel cost with co-injection of gas and coal and several trends emerged. Although significant reductions of coke rate and fuel costs were predicted, no marked reduction of carbon rate, hence emissions, was foreseen.

Optimization of pulverized coal injection (PCI) rate in an ironmaking blast furnace by an integrated process model

Pulverized coal injection (PCI) is generally used in modern blast furnace (BFs) ironmaking to reduce coke consumption by burning cheaper coal. This paper presents a numerical study on the effects of PCI on the inner states and overall performance of a 5000-m3 industrial BF. This is based on a recently developed integrated BF model that simulates an entire BF, including the raceway and hearth regions. The model is extended to consider the interaction between the raceway and the remaining BF region, the layered burden structure, and the hydrogen related reactions. After validation, it is used to study the effect of PCI rate and its interaction with oxygen enrichment and top burden distribution. The results are analyzed in detail in terms of raceway combustion characteristics, inner flow and thermochemical behavior, and overall performance. A maximum operable PCI rate is identified under given blast and burden conditions, beyond which relatively low coal-coke replacement ratio, high pressure drop and low hot metal (HM) temperature are observed. The maximum PCI rate is further improved with appropriate oxygen-enriched operation combined with suitable burden distribution. Excessive oxygen enrichment increases the coke rate to compensate for the cooling effect of coal injection. The results suggest that this integrated model can be used as a cost-effective tool to understand, quantify and optimize PCI effects on BF performance under different bottom and top operations.

Vacuum-assisted and alkali roasting for desulfurization of petroleum coke

A new vacuum-assisted alkali roasting desulfurization technology for petroleum coke is presented in this article. Deep desulfurization experiments were carried out on high-sulfur petroleum coke under argon and vacuum conditions. The results showed that vacuum was more favorable for the pyrolysis of organic sulfur in petroleum coke at high temperatures (>1400 °C) compared with argon. Vacuum-assisted alkali roasting desulfurization can reduced the sulfur content of petroleum coke to 0.18%, and the desulfurization rate can reached 98.54% at 1600 °C. The mechanism of sulfur removal in petroleum coke was preliminarily explored by Gauss, Multiwfn and VMD software, and the experimental samples were analyzed by Carbon–Sulfur Analyzer, XPS and SEM. The experimental results strongly verify the correctness of the simulation calculation. It is difficult to remove thiophene and sulfone in petroleum coke, but Vacuum-assisted alkali roasting can overcome this point, and greatly improve the desulfurization rate of petroleum coke.

Experimental investigation of n-heptane unsteady-state pyrolysis coking characteristics in microchannel

Coke deposition is considered a challenging problem during hydrocarbon pyrolysis. To get more insights into pyrolysis coking characteristics in the regenerative cooling channels, the unsteady-state experiments of n-heptane were performed in a 2.0 mm (internal diameter) passivated STS304 tube at 873–1073 K and 1.0 MPa with a feeding flow rate of 1.0 mL/min during pyrolysis for 5–60 min. The unsteady-state and spatial coke distributions were obtained. Results showed three distinct stages of coking, namely, catalytic coking, the transition stage, and pyrolytic coking. Coke samples obtained under different temperatures were characterized by element analyzer, scanning electron microscope (SEM), thermogravimeter coupled with a Fourier transform infrared spectroscopy (TG-FTIR), X-ray diffraction (XRD), and Raman spectra apparatus. The coke could be classified into two or three types according to its oxidative activity, and was composed of aromatic carbon and aliphatic hydrocarbons. The morphology of the coke transitions from filamentous to spherical with temperature and pyrolysis time. The C/H ratio of coke increased with the temperature in the catalytic coking stage, but decreased in the pyrolytic coking stage. High H contents and extensive defects of the coke observed at high temperatures could attributed to the generation of large amounts of pyrolytic coke and high coking rate, which resulting a lower degree of dehydrogenation. The presence of metallic substances in the coke verifies the catalytic effect at the beginning of coking and indicates the occurrence of carburization corrosion.

Evaluating the Effect of MgO/Al2O3 Ratio on Thermal Behaviors and Structures of Blast Furnace Slag with Low Carbon Consumption

In order to clarify the effect of the MgO/Al2O3 ratio on the fluidity of a low-alumina blast furnace slag system, the influence law of slag fluidity with different MgO/Al2O3 ratios was studied based on the composition of blast furnace slag through a viscosity experiment and themodynamic software. By studying the effect of the MgO/Al2O3 ratio on the activation energy of viscous flow of slag combined with FT-IR, the effect of the MgO/Al2O3 ratio on the thermal-stability of low-aluminum slag was interpreted from the microstructure level. Results indicated that the viscosity and the melting temperature of slag both showed a gradual downward trend due to the increase of the MgO/Al2O3 ratio. Besides, the temperature stability of the low aluminum slag became more stable due to the depolymerization of the complex structure of slag. Considering the actual operating conditions of blast furnace, the MgO/Al2O3 ratio of slag was suggested to be controlled to 0.60 and the basicity to be no higher than 1.20 under the conditions of this investigation. Industrial test results showed that the coke rate could be saved as 3.49 kg/t when the MgO/Al2O3 ratio decreased from 0.70 to 0.58.

Experimental Study on Co-Pyrolysis Characteristics of Household Refuse and Two Industrial Solid Wastes

The calorific value of household refuse (HR) is greatly improved after classification, which includes the implementation of sufficient pyrolysis conditions. Therefore, a better pyrolysis effect can be achieved by co-pyrolysis with industrial solid waste (ISW) with high calorific value. In this work, HR and ISW were used as raw materials for co-pyrolysis experiments. The influence on the distribution of three-phase products after co-pyrolysis, the concentration of heavy metals and dioxins in the flue gas, and the distribution of PCDD/Fs isomers were studied. The results showed that, at a temperature of 600 °C and H/C = 1.3, of the formed material, the quantity of pyrolysis gas was approximately 27 wt.%, and the quantity of pyrolysis oil was approximately 40.75 wt.%, which mainly contained alkanes, olefins, and aromatic hydrocarbons. When S/C = 0.008, pyrolysis gas accounted for 25.95 wt.% of the formed material, and pyrolysis oil for 41.95 wt.% of the formed material. The ignition loss rate of pyrolysis coke was approximately 20%, and the maximal calorific value was 14,217 KJ/kg. According to the thermogravimetric experiment, the co-pyrolysis of HR and ISW can promote the positive reaction of pyrolysis, and the weight loss reached 62% at 550 °C. The emission of gaseous heavy metals was relatively stable, and the concentration of heavy metals slightly decreased. The main heavy metals in the ash were Cu, Fe, and Zn. The emission of dioxins could be effectively reduced by the pyrolysis of HR with ISW, and the produced dioxins were mainly synthesized from de novo synthesis. After pyrolysis, the toxic equivalent of dioxins in the flue gas was reduced from 0.69 to 0.29 ng I-TEQ/Nm3, and the distribution of dioxin isomers in the flue gas had little influence. The experimental results provide a theoretical basis for the application of co-pyrolysis technology with HR and ISW.

Prospects of steel industry development accounting ecological restrictions

Discussion of many years on consequences of man’s activity effect on environment at present moved to a practical aspect. New ecological and economical limits dictate a necessity to reduce the carbon intensity of metallurgical processes. It was noted that the technological couple “blast furnace – basic oxygen furnace” is a basic method of steel production, based on utilization of coke as a fuel and reducing component. Distribution of metallurgical capacities by types of fuel used shown, which confirms application of carbon-containing fuel-reducing additions in overwhelming majority of technological processes of iron production. Data on projects reducing carbon intensity of metallurgical industry presented, most of which aimed at changing the technology of BF process. Experience of steel industry of Japan on perfection machinery and technology of BF production considered, which enabled to reduce total consumption of reducing agents down to figure less down to 450 kg/t of hot metal, which is the best index among countries of the world. It was shown that increase of a blast furnace volume results in change of BF process technology. Such an increase also results in decrease of carbon consumption – blast furnaces of large volume have lower specific consumption of fuel and reducing agent. The specific coke rate in blast furnaces of large volume is by 71 kg/t of hot metal less comparing with blast furnaces having volume less 1000 m3, and the total fuel consumption in large blast furnaces is by 51 kg/t of hot metal lower. Accounting necessity to decrease the carbon footprint in steel products, basic ways of steel industry technologies development can be enlargement of facilities with shutdown of small and not effective capacities, changing sinter and BF charges structure with increase of more qualitative raw materials and pellets, application of alternative kinds of fuel and reducing additions.

Experimental and Numerical Investigations on Charging Carbon Composite Briquettes in a Blast Furnace

In the present research, charging carbon composite briquettes (CCB) in a blast furnace (BF) was investigated. The CCB used contained 29.70 wt.% Fe3O4, 39.70 wt.%, FeO, 1.57 wt.% iron, 8.73 wt.% gangue, and 20.30 wt.% carbon. Its reaction kinetics in BF was examined by nonisothermal tests and modeled. Thereafter, the influence of replacing 10% ore with CCB on BF performance was studied by numerical simulations. Results showed that the CCB reaction behavior in BF could be modeled using the previously proposed model under ags = 1900 m2·m−3. Numerical simulations on a BF with a production of 6250 t hot metal per day (tHM/day) showed that replacing 10% ore with CCB efficiently improved the BF operation for coke saving. In the CCB charging operation, the CCB reached a full iron-oxide reduction above the cohesive zone (CZ) and a carbon conversion of 85%. By charging CCB, the thermal state in the BF upper part was significantly changed while it was not influenced in the BF lower part; the ore reduction was retarded before the temperature reached 1073 K and was prompted after and the local gas utilization tends to increase above the CZ. By the CCB reduction above the CZ, BF top gas temperature was decreased by 8 K, the BF top gas utilization was increased by 1.3%, the BF productivity was decreased by 17 tHM/day, the coke rate was decreased by 52.2 kg/tHM, and ore rate was decreased by 101 kg/tHM. Considering the energy consumption of sintering and coking, charging the CCB could have a significant energy-saving and CO2-emission-reducing effect for BF iron making.

Transient State modeling of Industry-scale ironmaking blast furnaces

The dynamic multiphase flow in ironmaking blast furnaces (BFs) operation is a transient-state process, but it was widely modeled as steady-state in the past. It is necessary to understand the evolution of in-furnace phenomena after some operational parameters are changed. In this study, for the first time, a transient-state BF (TBF) model is developed to describe the dynamic in-furnace phenomena in terms of flow, thermal, and chemical behaviors, featuring respective chemical reactions in respective burden layers. The TBF model is validated against the measurements from an experimental BF. Then the TBF model is applied to a commercial BF of industry-scale and used to capture the time-evolution of velocity field, cohesive zone profile, thermal field, and gas utilization efficiency from an initial state to a steady state under given conditions. Moreover, the TBF model is used to study a specific BF operation change – hot burden charging, for TBF model capability demonstration, by capturing the time-evolution of the in-furnace phenomena at certain time intervals. It shows that, after charging the hot burden, the change of reacting flow can be more significant in the upper shaft regions compared to other regions, more important at near-wall region compared to the center region, and this largely happens in the first 8–10 h; besides, top gas temperature can rise to ∼ 800 K and coke rate is increased by ∼ 20 kg/tHM to maintain the BF productivity. This TBF model offers a cost-effective tool to understand the evolution of in-furnace behaviors in operation changes; and provide a basis for real-time understanding and control in future ironmaking.

Graphitization and Performance of Deadman Coke in a Large Dissected Blast Furnace.

The graphitization and performance of deadman coke in the blast furnace hearth have an essential influence on the longevity of the blast furnace. In this paper, coke samples were obtained from various heights in a hearth during the overhaul of the blast furnace. The voidage, particle size, graphitization degree, microstructure, and structure evolution of multiple cokes were analyzed through digital image processing, XRD, Raman spectra, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (SEM-EDS). The graphitization results were compared with feed coke, tuyere coke, cohesive zone coke, and deadman coke in reference, and the main findings were analyzed. The following results were obtained. First, the voidage of deadman coke increased and then decreased with the increase of the depth while the particle size continued to decrease. In addition, the consumption rate of coke as a carburizer, reductant, and heart source was 8.47, 30.95, and 60.58%, respectively. Second, the graphitization degree of deadman coke was extremely high and showed a trend of first increasing and then decreasing. Finally, the evolution mechanism of coke graphitization was proposed. Molten iron, alkali metal, temperature, and mineral were the crucial factors that affect the graphitization of coke. The turning point of the graphitization degree was related to the buoyancy of the hearth.

A Comparison of Laboratory Coal Testing with the Blast Furnace Process and Coal Injection

The injection of coal through tuyeres into a blast furnace is widely adopted throughout the industry to reduce the amount of coke used and to improve the efficiency of the iron making process. Coals are selected depending on their availability, cost, and the physical and chemical properties determined by tests, such as the volatile matter content, fixed carbon, and ash content. This paper describes research comparing the laboratory measured properties of injection coals that were used over a two-month production period compared to the process variables and measurements of the blast furnace during that study period. In addition to the standard tests, a drop tube furnace (DTF) was used to compare the burnout of coals and the char properties against the production data using a range of statistical techniques. Linear regression modelling indicated that the coal type was the most important predictor of the coal rate but that the properties measured using laboratory tests of those coals were a minor feature in the model. However, comparisons of the Spearman’s correlations between different variables indicated that the reverse Boudouard reactivity of the chars, prepared in the DTF from the coals, did appear to be related to some extent to the coal and coke rates on production. It appears that the constant process adjustments made by the process control systems on the furnace make it difficult to identify strong correlations with the laboratory data and that the frequency of coal sampling and the coal blend variability are likely to contribute to this difficulty.

Effect of Phosphine on Coke Formation during Steam Cracking of Propane

In conventional steam cracking feedstocks, contaminants such as sulfur, phosphine, and heavy metal components, present in trace levels, are believed to affect coke formation on high temperature alloys. To gain an understanding of the role of phosphine coking rates on 25/35, CrNi and Al-containing reactor materials were determined in a plug flow reactor during cracking of a propane feedstock doped with ppb levels of PH3 in the presence of DMDS. The presence of phosphine decreased the asymptotic coking rates by more than 20%, while it had a smaller influence on the catalytic coking rate. The coking rate was more severely reduced for the 25/35 CrNi alloy in comparison to the Al-containing alloy. The ppm levels of phosphine did not affect the olefin yields nor the production of undesired carbon monoxide. The morphology of the coked alloys were studied using an off-line Scanning Electron Microscope with Energy Dispersive X-ray detector (SEM with EDX) images of coked coupons. Two types of coke morphology are observed, i.e., filamentous coke with DMDS as an additive and globular coke in the presence of phosphine. The effect of phosphine on the material has a positive impact on the oxide scale homogeneity of 25/35 CrNi alloy, whereas the Al-containing alloy remained unchanged.

Numerical investigation of the limit of coke rate reduction in an ironmaking blast furnace (BF)

Blast furnace (BF) ironmaking maintains its role as the predominating process for producing hot metal (HM) from iron ore. The process is highly carbon-consumption and emission intensive. Considering its massive production scale, any improvement of the process in terms of the operational parameters could results in significant social, environmental and economical benefits. The most concerned operational parameters of the BF is the coke rate, with the reduction of the coke rate being long time pursued. However, the limit of coke rate reduction for an operating BF is rarely attempted for safety and stability. Therefore, the limit for coke rate reduction for an operating BF largely remains implicit, with the underlying mechanism being unknown. In this work, a previously developed multifluid BF process model is used to investigate the limit of coke reduction on an experimental scale BF. With the gradual reduction of the coke rate, the BF is analysed in detail in terms of in-furnace multiphase flow, thermochemical behaviors as well as overall performance indicators. The minimum coke rate to maintain a targeted production is identified with the underlying mechanism for the BF operated with a coke rate at its limit explained. Also, possible measures for increasing the limits of coke reduction are proposed. This is done by increasing the hot blast temperature, which proves to be useful based on the simulation results. The results generated from this work should be useful to improve the BF ironmaking process efficiency, hence cutting CO2 emission and guiding green production in the future.

Prediction of product distribution in the delayed coking of Iranian vacuum residue

The delayed Coker process as an upgrading process has main impact on the productivity of the Refinery Complexes. To determine the impact of different operating conditions on the product yield distribution of the delayed coking process, several experiments were designed and conducted in a prefabricated pilot plant. The experiments were conducted on different Iranian vacuum residues at temperatures ranging from 420°C to 480°C and at atmospheric pressure. Reaction times were within the range of 5-120 minutes. A four lumps kinetic model has been developed based on the experimental results. The lumps—which included Volatile products, coke, feed, and an intermediate phase between coke and feed—were defined to precisely monitor the yield distribution of products throughout the reaction time. The feedstocks utilized were three different vacuum residues and their blends. The mixtures were produced by using different mixing ratios of the three vacuum residues. The Statistical analysis shows that this model has R-squared, RMSE, SSE, and MRE equal to 0.99, 0.022, 0.08, and 3.537%, respectively. This shows that the developed model is sufficiently accurate. The experimental and modeling results in this research reveal that by increasing the temperature, the yield of coke and gas is abated. However, the yield of the distillate is escalated. This investigation illustrates that the production of an intermediate reaction has the highest amount of activation energy in comparison with the other reactions. Also, the results indicate that the production reaction rate of coke has the highest amount in comparison with other reactions.

Tuyere-Level Syngas Injection in the Blast Furnace: A Computational Fluid Dynamics Investigation

With the recent push towards high injection rate blast furnace operation for economic and environmental reasons, it has become desirable in North America to better understand the impacts of alternate injected gas fuels in comparison to the well-documented limitations of natural gas. The quenching effects of gas injection on the furnace present a functional limit on the maximum stable injection rate which can be utilized. With this in mind, researchers at Purdue University Northwest’s Center for Innovation through Visualization and Simulation utilized previously developed computational fluid dynamics (CFD) models of the blast furnace to explore the impacts of replacing natural gas with syngas in a blast furnace with a single auxiliary fuel supply. Simulations predicted that the syngas injection can indeed reduce coke consumption in the blast furnace at similar injection rates to natural gas while maintaining stable raceway flame and reducing gas temperatures. The coke rates predicted by modeling using similar injection rates indicated an improvement of 8 to 15 kg/thm compared to baseline conditions when using the syngas of various feedstocks. Additionally, syngas injection scenarios typically produced higher raceway flame temperatures than comparable natural gas injection cases, indicating potential headroom for reducing oxygen enrichment in the hot blast or providing an even higher total injection rate.

Adjustment of a technology of cast iron smelting in the blast furnace of jsc "ural steel" w ith a volume of 1232 см<sup>3</sup> with charge h a v in g 95% share of Mikhailovskii GOK pellets

To use effectively internal raw material base, JSC “Ural Steel” accomplished I category major overhaul of the blast furnace No. 2. The main purpose of the overhaul was to design a rational profile which could ensure an ability to operate with a charge containing 95 % of Mikhailovskii GOK (mining and concentrating plant) pellets having basicity of 0.5 by CaO/SiO2. The blast furnace No. 2 having useful volume of 1232 m3, was constructed by design of Danieli Corus, the Netherlands, and was blown in on December 30, 2020. In the process of guarantee tests, step-by-step increase of Mikhailovskii GOK pellets (Fetotal = 60.5 %, CaO/SiO2 = 0.5) content in the charge iron ore part was being accomplished from 55 to 95.1%. Charging of the blend containing pellets in the amount of 55% of iron ore part, was done by charging system 4OOCC + 1COOCC (Ore - Coke) with filling level 1.5 m. Under conditions of pellets part increase in the blend, the charging system was changed to decrease their content at the periphery, to increase it in the ore ridge zone and make it intermediate between periphery and the ore ridge. At the pellets share in the iron ore raw materials 0.75 the charging system was used as the following: 3OOCC + 1COOC + 1COOCC, while at the content 95.1% the following charging system was used: 2COOC + 2COOC + 1COOCC. It was noted that in the period of guarantee tests the furnace running was smooth. The average silicon content in the hot metal was 0.70% at the standard deviation 0.666. Sulfur content in the hot metal did not exceed 0.024%, the blowing and natural gas consumption figures were 2100 m3/min and 11000 m3/min correspondently, oxygen content in the blowing 26.5%, hot blowing and top smoke pressure figures were 226.5 and 109.8 KPa correspondently. The productivity of the furnace was reached as high as 2358 t/day at the specific coke rate 433 kg/t of hot metal. After guarantee tests completion, the pellets content in the iron ore part was decreased gradually from 95 down to 50%. The decreasing was made by 5% in every 6 hours of operation. Application of the mastered technology of the blast furnace No. 2 with the increased share of pellets will enable to stably supply the blast furnaces No. 1, 3 and 4 by iron ore raw materials in the proportion of 30-35% of pellets and 65-70% of sinter.

Co-hydrogenation behavior of Hami coal with Tahe residue

The hydrogenation and co-hydrogenation behaviors of Hami coal and Tahe residue were investigated in an autoclave, and the feasible technical route for co-hydrogenation was explored. The experimental results showed that Hami coal had good hydroliquefaction performance and the suitable reaction temperature was 445°C. At 445°C and 9 MPa, the coal conversion rate reached 98.74%, and the oil yield reached 68.54%. The hydrogenation tests of Tahe residue showed obvious coking tendency at the lower temperature, and it was difficult to achieve lightening. At 430°C, the conversion rate of Tahe residue was only 66.38%, the light oil yield was only 50.01%, and its coking rate was as high as 9.45%. The coking rate increased with the reaction temperature. When the mixtures of Hami coal and Tahe residue were co-hydrogenated directly, the conversion rate of the raw materials was lower, and the coke phenomenon was obvious. At the coal/oil ratio was 40/60, the conversion rate was 97.79%, and oil yield was 73.36%. Adding hydrogen solvents into the co-hydrogenation system could effectively inhibit coke formation, increase the conversion rate, and lighten co-hydrogenation products. When the amount of coal was 45% and Tahe residue was 20%, the conversion rate of raw materials was 98.38% and the oil yield was 74.82%.

Influence of coke rate on thermal treatment of waste selective catalytic reduction (SCR) catalyst during iron ore sintering

Waste selective catalytic reduction (SCR) catalyst as a hazardous waste has a significant impact on the environment and human health. In present study, a novel technology for thermal treatment of waste SCR catalyst was proposed by adding it to sinter mix for iron ore sintering. The influences of coke rate on the flame front propagation, sinter microstructure, and sinter quality during sintering co-processing the waste SCR catalyst process were studied. In situ tests results indicated the maximum sintering bed temperature increased at higher coke rate, indicating more liquid phase generated and higher airflow resistance. The sintering time was longer and the calculated flame front speed dropped at higher coke rate. Sinter microstructure results found the coalescence and reshaping of bubbles were more fully with increasing coke rate. The porosity dropped from 35.28% to 25.66%, the pore average diameter of large pores decreased from 383.76 μm to 311.43 μm. With increasing coke rate, the sinter indexes of tumbler index, productivity, and yield, increased from 33.2%, 9.2 t·m−2·d−1, 28.9% to 58.0%, 36.0 t·m−2·d−1, 68.9%, respectively. Finally, a comprehensive index was introduced to systematically assess the influence of coke rate on sinter quality, which rose from 100 to 200 when coke rate was increased from 3.5% (mass) to 5.5% (mass).

Influence of process parameters on impurity level in ferrochrome production-An industrial-scale analysis

ABSTRACT Ferrochromium production is a highly energy-intensive process, consuming between 3000 and 4000 kWh for producing one ton of ferrochrome alloy. The alloy produced contains chromium, iron as a principal constituent and silicon and carbon as an impurity. Minor quantity of silicon is desirable to aid in the fluidity of the alloy while smelting chromite ore. Still, at a higher level, it not only deports as the impurity in alloy but also causes a considerable drain of energy. Also, the excess of carbon in alloy causes problem during final carbon adjustment during steelmaking. An exhaustive understanding of different process parameters affecting impurity intake in the alloy can significantly reduce impurity and hence, energy consumption. The gained knowledge can be further utilized to control the process better and achieve the alloy of the desired composition. Several sets of industrial data were obtained and analyzed to understand the process. Different parameters, such as coke rate, power input, input silicon and average moisture on the composition and recovery of ferrochrome, were studied. From the study, it was concluded that a high grade of feed material with input Si <13 Wt.%, a coke rate of 380–390 kg/t of alloy and power input in the range of 3067–3200 kWh/t of alloy can result in an alloy with Si <2 Wt.%. Operating under the given power range is also observed to reduce the Cr2O3 loss to the slag.

Trimetallic Ni-Co-Ru catalyst for the dry reforming of methane: Effect of the Ni/Co ratio and the calcination temperature

This work studies the effect of Ni/Co ratio and calcination temperature on the performance of trimetallic Ni-Co-Ru catalysts supported on MgO-Al2O3. Higher activity was achieved with higher Ni/Co ratios, and the effect of calcination temperature on stability was small except for the bimetallic Co-Ru catalyst which showed different deactivation mechanisms at different calcination temperatures. A higher calcination temperature was generally associated with an increased coking rate due to elevated sintering, while a lower calcination temperature slightly improved the reducibility of the catalysts. Promoting the Ni-Co catalysts with Ru improved their stability and reducibility, but slightly compromised catalyst activity when calcined at high temperature. Coking rate was significantly reduced by Ru addition on the 7.5Ni 7.5Co sample. Excellent stability and the lowest coking rate were achieved at the expense of a slightly lowered activity with the 5Ni 10Co 0.25Ru catalyst calcined at 750 °C.