Coke Powder Research Articles

Dephosphorisation behaviour of blast oxygen furnace (BOF) slag due to carbothermal reduction

ABSTRACT The thermodynamic analysis of converter slag by carbothermal reduction was carried out. The laboratory tests of converter slag by carbothermal reduction dephosphorisation were carried out in molybdenum disilicide high-temperature resistance furnace and 500 kg top bottom combined blowing multi-functional test furnace respectively. The results show that the reaction temperature and kinetic conditions have a great influence on the dephosphorisation rate. In the top and bottom combined blowing multi-functional test furnace, coke powder is used as both reducing agent and heating agent. The exothermic reaction between coke powder and oxygen can ensure that the dephosphorisation reaction can be carried out at a higher temperature. At the same time, the good stirring of topblowing oxygen on the slag layer is conducive to further improve the dephosphorisation reaction speed.

Application of High‐ and Low‐Reactivity Cokes in Hydrogen‐Rich Blast Furnaces

The effects of two cokes with different reactivity on the lump ore's metallurgical properties and coke's solution loss are investigated under the high‐temperature load reduction. The work used an improved test device for softening‐melting and dropping characteristics of iron ores in both CO2 and CO2H2O atmospheres. The deterioration behavior of highly reactive cokes is expounded under hydrogen‐rich conditions. High‐reactivity cokes under hydrogen‐rich conditions are more favorable for enhancing the breathability of charge and the penetration of the coke layer. However, it increased the thickness of the softening zone. High‐reactivity cokes had obvious internal and external reaction gradients. The solution loss reaction mostly occurred on the surface, with selectivity. The longitudinal stacking height, layer number, and order degree in the carbon structure decreases after the reaction. The carbon‐structure difference weakens between the shell and core. The enhancement of coke's reactivity, however, results in the significant loss of coke powders on its surface. Unreduced FeO and refractory Fe2SiO4 are more likely to appear in the droplets, which is not conducive to the reduction of Fe and the generation of slag crust in the furnace. The difficulty in separating lump ores and cokes is aggravated, and more iron‐containing charge remain in the furnace.

Exergy analysis of a novel ironmaking process combining coal gasification with the smelting reduction of iron ore

The global iron and steel industry is an energy-intensive industry, and energy-saving in this industry is of great significant. A novel ironmaking process combining coal gasification with the smelting reduction of iron ore (CCGSR) is proposed, and an exergy analysis is applied to evaluate its thermodynamic performance. The results show that the exergy efficiency of the entire system is 88.15 % whereas the energy efficiency is 98.64 %. The exhaust gas of pre-reduction furnace is the main exergy output and has great energy-saving potential. The local exergy loss rates in the pyrolysis, pre-reduction, and smelting reduction furnaces are 55.81 %, 7.24 %, and 36.95 %, respectively. The pyrolysis and smelting reduction furnaces exhibit the largest exergy loss, owing to the mixing of high-temperature gas of the smelting reduction furnace and circulating gas, coke powder gasification, and heat transfer. In addition, after the exhaust gas is utilized to form a cogeneration system of iron and electricity, the exergy efficiency increases from 40.18 % to 50.06 % comparable with 600 MW ultra-supercritical coal-fired generating units. The present work also provides some suggestions for reducing exergy destruction.

Resistance characteristics and particle movement behavior of a petroleum coke particle packed bed in a vertical shaft calciner under different burden distribution methods

AbstractBecause of the increasingly deteriorating quality of petroleum coke raw materials, abnormal furnace conditions, such as “firing and blasting”, frequently arise during the calcination of petroleum coke with a high powder/coke ratio in a vertical shaft calciner. This poses an urgent technical challenge that needs to be addressed. In iron and steel metallurgy, the burden distribution system is an important way to regulate blast furnace conditions and improve the permeability of a particle packed bed. In this work, advanced burden distribution concepts were introduced into the calcination process of petroleum coke in a vertical shaft calciner. Experimental devices were established to determine the resistance characteristics of a petroleum coke particle packed bed, along with a cold physical model of a 1/8 scale vertical shaft calciner. The influence of particle size and burden distribution methods on the resistance characteristics and particle motion behavior of the petroleum coke particle packed bed was systematically studied. The research findings indicate that both particle size and burden distribution methods significantly impact the resistance characteristics of petroleum coke particle packed beds. The smaller the particle size, the poorer the permeability of the bed. The layered burden distribution, symmetrical burden distribution, and dual‐particle mixed conventional burden distribution all contribute to improving the permeability of the petroleum coke particle packed bed in the vertical shaft calciner. Furthermore, employing symmetrical burden distribution in Bed‐3, which is packed with petroleum coke particles of diameters −3.2 + 2.5 mm and −1.0 + 0.8 mm, results in the smallest unit pressure drop, at only 1.7% of that of the conventional burden distribution of unscreened raw materials. This is the most effective means of improving the permeability of the bed. During the discharging process, particle size and symmetrical burden distribution have no significant impact on the motion characteristics of petroleum coke particles in the vertical shaft calciner. In general, in the calciner area, particles primarily move in a plug flow pattern and gradually transform into funnel flow in the cooling water jacket area. These research results provide the theoretical basis for addressing the technical challenges associated with powder coke calcination in vertical shaft calciners through reasonable burden distribution methods for fine and coarse particles.

Resource utilization of semi-dry flue gas desulfurization ash by thermal treatment on sintering machine

Semi-dry flue gas desulfurization ash (SFGDA) is an abandoned Ca and S resource that is currently stacked without appropriate disposal methods. A technology with industrialization potential, SFGDA, and iron ore thermal processing is an effective approach to obtaining calcium ferrite and industrial sulfuric acid. This study investigated the thermochemical reaction mechanism of SFGDA during high-efficiency pyrolysis employing Fe2O3 and coke powder for self-heating. The results showed that the addition of coke powder enhanced the thermal efficiency and reduced the decomposition temperature, while the reaction is accelerated by the lightning-fast combination of Fe2O3 with the CaO produced during pyrolysis to generate calcium ferrite products. The optimal conditions were determined to be a coke powder dosage of 10% and Fe2O3 dosage of 50%. In semi-industrial experiments, the SFGDA achieved a desulfurization rate of 99% and a calcium ferrite content of 85%. The calcined product CaO from CaSO4 and CaSO3 in the form of calcium ferrite products, with a minimal amount of CaSO4. In addition, during the high-temperature calcination process performed by the sintering machine, the majority of the sulfur within the raw materials migrates as SO2 and is subsequently emitted into the flue gas. Following, this SO2 is captured and utilized for the production of commercially valuable sulfuric acid. When the yield of enabled to calcined product corresponds to 1 ton, it could potentially dispose of 882 kg of SFGDA, culminating in a high-value, harmless, and large-scale SFGDA treatment in steel industry.

Nitric Acid-Treated Blue Coke-Based Activated Carbon's Structural Characteristics and Its Application in Hexavalent Chromium-Containing Wastewater Treatment.

This study primarily focused on the efficient transformation of low-priced blue coke powder into a high-capacity adsorbent and aimed to address the pollution issue of hexavalent chromium (Cr (VI))-laden wastewater and to facilitate the effective utilization of blue coke powder. A two-step method was utilized to fabricate a blue coke-based nitric acid-modified material (LCN), and the impact of nitric acid modification on the material's structure and its efficacy in treating Cr (VI)-contaminated wastewater was evaluated. Our experimental results illustrated that, under identical conditions, LCN exhibited superior performance for Cr (VI) treatment compared to the method employing only potassium hydroxide (LCK). The specific surface area and pore volume of LCN were 1.39 and 1.36 times greater than those of LCK, respectively. Further chemical composition analysis revealed that the functional group structure on the LCN surface was more conducive to Cr (VI) adsorption. The highest amount of Cr (VI) that LCN could bind was measured at 181.962 mg/g at 318 K. This was mostly due to chemisorption, which is dominated by redox reactions. The Cr (VI) removal process by LCN was identified to be a spontaneous, exothermic, and entropy-increasing process. Several tests on recycling and reuse showed that LCN is a stable and effective chromium-containing wastewater adsorbent, showing that it could be used in many situations.

Study on Direct Reduction in Carbon-Bearing Pellets Using Biochar

As a renewable, carbon-neutral raw material, the application of biomass in steel production is conducive to reducing greenhouse gas emissions and achieving green and sustainable development in the steel industry. The heating and reduction process of a rotary hearth furnace was simulated under laboratory conditions to roast and reduce biochar carbon-bearing pellets with coke powder and anthracite carbon-bearing pellets as a comparison. This was conducted to investigate the impact of biochar as a reducing agent on the direct reduction in carbon-bearing pellets. Under various reduction temperatures, carbon/oxygen ratios, and reduction times, tests were conducted on the compressive strength and metallization rate of carbon-bearing pellets made using typical binder bentonite. Results show that with the increase in reduction temperature, the metallization rate of pellets increases, while the compressive strength initially decreases and then increases, reaching the lowest point at 900 °C and 1000 °C. When the ratio of carbon to oxygen is between 0.7 and 0.9 and the reduction time is between 15 and 25 min, carbon-bearing pellets meet the requirements of both the metallization rate and the strength, with the metallization rate above 80%. However, severe volume swelling and low strength were observed in biochar carbon-bearing pellets at 900 °C and 1000 °C, which negatively impacted multi-layered charging and heat transfer efficiency in the blast furnace. Therefore, a novel laboratory-prepared binder was introduced in the preparation process of biochar carbon-bearing pellets at an appropriate addition ratio of 5–8%. Without producing any swelling concerns, the inclusion of this binder considerably improved the compression strength and metallization rate of the pellets, enabling them to fulfill the standards for raw materials in the blast furnace.

High efficiency separation of fine coke powders by the novel jet-swirl scrubber: Characteristics and mechanisms

The deep removal of fine coke powders is an urgent need and remains a great challenge for the stable operation of the delayed coke system. Herein, a novel jet-swirl scrubber was developed. A combined approach utilizing CFD and DPM was employed to investigate the mechanism of droplet fragmentation. The results indicated that droplets underwent two stages of fragmentation in the convergent and throat sections under the influence of turbulent vortex structures. This leaded to a rapid reduction in droplet size and an effective dispersion. Thorough mixing with the gas phase occurred in the divergent section, facilitating enhanced capture of coke powders. Cold model experiments were conducted to examine the relationship between droplet size, coke powders capture efficiency, and gas-liquid separation efficiency. Under the condition of optimized critical droplet size 0.106 mm by adjusting the flow rate, the removal efficient of coke powders was up to 99.57 %. This work provides valuable technical support for further development and process optimization of the decoking powder unit in delayed coking system.

Distribution characteristics, risk assessment, and relevance with surrounding soil of heavy metals in coking solid wastes from coking plants in Shanxi, China.

Heavy metal concentrations represent important pollution evaluation indices, and it is necessary to assess the potential environmental and health risks from heavy metals associated with coking wastes from coking plants. In this study, coking sludge (CS), tar residue (TR), coke powder (CP), and sulfur paste (SP) from three coking plants (Plant A, Plant B, and Plant C) in central, western, and southern Shanxi Province and from soils surrounding Plant A were selected as the research objects, and the distributions of Cu, Ni, Pb, Zn, Mn, Cd, and Cr were determined. The results showed that Cd in the four solid wastes far exceeded the soil background value by a factor of 16~195, and the contents of Pb in TR (three plants) and CS (Plant C) exceeded the soil background values 19.70-, 23.57-, 14.46-, and 12.56-fold, respectively. Similarly, the concentrations of Cu, Ni, Pb, Zn, and Cd in soils were higher than the background values by factors of 31.18, 8.35, 34.79, 29.48, and 3.43, respectively. In addition, the Cu, Ni, Pb, and Cr in the four solid wastes and soils mainly existed in the residual state. As depth increased, the overall Ni, Pb, Mn, and Cd concentrations in soils increased. The high ecological risks associated with the four solid wastes were mainly due to the enrichment of Cd. Workers in coking plants face certain Cr health risks. This study provides theoretical support for the coking industry with respect to the treatment, disposal, and management of solid wastes.

A novel method of combined desulfurization and heat utilization of low-temperature flue gas from hot blast stove for blast furnace: Laboratory research and industrial application

To address the challenges of low waste heat utilization rates and high desulfurization costs, this study proposes a novel method for combined desulfurization and heat utilization of low-temperature flue gas. By utilizing the low-temperature flue gas from hot blast stoves to dry lump metallurgical coke, the method also achieves flue gas desulfurization during the lump coke drying process. During the drying process, the wet lump coke desulfurizes due to the reaction between water vapor in the lump coke and the SO2 and oxygen in the flue gas, resulting in the formation of sulfuric acid. Additionally, the coke powder generated by friction during the drying process of lump coke has a large specific surface area, enabling it to adsorb additional quantities of SO2 and enhance the desulfurization process. It's important to note that the lump coke itself does not exhibit adsorption properties towards SO2 during the drying process, and the gas is not retained within the lump coke. Industrial applications indicate the outlet flue gas temperature is reduced from 175 °C to 60 °C, and the concentration of SO2 in the outlet flue gas is reduced from 150 mg/m3 to 29 mg/m3.

Biochar and other carbonaceous materials used in steelmaking: Possibilities and synergies for power generation by direct carbon fuel cell

The objective of this study is the preliminary investigation of the feasibility of using a low-temperature molten hydroxide direct carbon fuel cell as an additional energy source for steel production by electric arc furnace. For this purpose, four carbonaceous materials related to the steel industry (electrographite, coke, torrefied biochar and hydrochar) were selected and characterized to predict their electrical behavior before their actual introduction as fuels. Special attention was paid to both the morphological effect (bulk/pellet or powder) and the chemical composition of the fuels on the electrical performance of the cell. Electrical measurements showed the positive influence of powder morphology, with coke powder having the highest peak power density value (49.6 mW/cm2). Electrographite was found to be useable only as a powder (18.7 mW/cm2), as the high chemical stability of the bulk morphology, provided by the smooth surface and the pitch used as a binder, acted as inhibitors of the carbon oxidation reaction. Although biochar appeared superior to hydrochar when inserted as powder (23.5 vs. 18.2 mW/cm2), the latter showed promising results also inserted as pellet. the latter also showed promising results when inserted as a pellet. Specifically, once inserted within the molten hydrochar, the binder used to produce the hydrochar is removed changing the morphology from pellet to sandy/powdery, negating the penalizing effect of the lower surface to volume of bulk morphology (15.8 vs. 18.2 mW/cm2) and offering the advantage of avoiding the milling process and related fine particulate production from an industrial point of view.

Petroleum Coke Embedded in Cigarette Butts: All Waste-Derived Solar Evaporator for Effective Water Evaporation.

Solar-driven interfacial evaporation is an eco-friendly solution for tackling the impending water scarcity the world is facing in our century. In this work, a solar-driven interfacial evaporator was prepared from cigarette butts loaded with petroleum coke powder (Filter-PetCoke), a by-product of the oil refinery processes, for the improvement of the absorption of the incident solar light. A comparison between a flat 2D and a 3D evaporator with a surface composed of orderly patterned protrusions of 2.1 cm was carried out to assess the influence of the evaporator configuration on the evaporation performance. The 3D evaporator (3D Filter-PetCoke) achieved by far the best performance (evaporation rate: 1.97 ± 0.08 kg m-2 h-1 and solar conversion efficiency: 93.2 ± 5.4%) among the prepared samples (3D Filter-PetCoke, 3D Filter, 2D Filter-PetCoke, and 2D Filter). In addition, this configuration seems to be adaptable for real and more massive operation because of the geometry of the evaporator. The high efficiency was ascribed to the good heat generation of the petroleum coke and the excellent heat management of the 3D structure of the evaporator. Moreover, this evaporator was resistant to multiple repeated usages without significant efficiency loss and capable of producing drinking water from seawater and Escherichia coli (E. coli)-contaminated water. The findings in this work indicate that this evaporator is pertinent to real situations to supply safe freshwater very efficiently from chemically/biologically contaminated water.

Surface Modification of Coal-Based Coke Powder with Pitch Powder for Lithium Ion Batteries

Surface Modification of Coal-Based Coke Powder with Pitch Powder for Lithium Ion Batteries

Cold-model numerical study of raceway shape and size effect on gas and fines flow behaviour in packed bed between the raceway and cohesive zone

ABSTRACT Operational stability and productivity of an iron-making blast furnace relies on the permeability of the bed, which is adversely affected by the accumulation of unburnt coal and fine coke powder resulting from Pulverised Coal Injection (PCI) and coke degradation. Stable operation at a high PCI rate necessitates an understanding of gas-fine powder distribution, which is affected by the cohesive zone, and raceway shape and size. A computational study of a laterally injected gas-fine powder flow through a tuyere, into a packed bed is conducted in the presence of raceway and cohesive layers. An experimental correlation is used to predict the static holdup. The effect of operational parameters such as gas flow rate, particle and fine properties, and structural parameters such as cohesive zone configuration, porosity, and tuyere protrusion are analysed. Sensitivity analysis shows raceway shape, size, and interaction with the cohesive blocks affects the distribution and accumulation of fine powder.

Effects of Coupling Action of Load and Temperature on the Lubricity of Coke Powder

By introducing the coke powder into the friction pair, the effects of load and temperature on the lubricity of coke powder at the frictional interface are studied. Before the test, the microcrystalline structures of coke powder at different temperatures are characterized by X-ray diffraction (XRD). After the test, the friction surfaces are observed by electron microscope and energy spectrum, the oxide compositions of friction surface are characterized by XRD, and the lubrication mechanism of coke powder is investigated. The results show that at RT (room temperature), as the load increases, the forming of the powder layer gradually deteriorates. When the load is 5 MPa, at a low temperature, the powder layer is thicker, and the coke powder exhibits better lubricity. In contrast, at a high temperature, affected by the temperature, the lubricity of coke powder declines, and the friction coefficient is higher.

The Amount Prediction and Optimization of the Returned Ore Generated from Sintering Process Based on SHAP Value and Ensemble Learning

Sintering is the first step of ironmaking. The amount of returned ore is related to the quality of the sinter, yield, and cost of ironmaking. Herein, a novel and interpreted method is proposed to intelligently predict and optimize the amount of returned ore, which is not the case with the traditional “black box” model. The optimal combination of input variables is determined based on the SHapley Additive exPlanation (SHAP) value and eXtreme Gradient Boosting (XGBoost) selection. The model is constructed considering an R2 of 0.91 and average error of 2.9%, which verify its feasibility. Found by SHAP value analysis, when annular cooler speed and sintering machine speed are below 1.7 m min−1, sintering machine speed is below 2.1 m min−1, coal and coke powder amount are more than 14 and 8 t h−1, respectively, and the amount of the returned ore is reduced. In the optimization process, the joint optimization method with regard to the speed of the annular cooler and sintering machine can help solve 91% of the problem of high‐amount ore return, thereby reducing the returned ore amount 13.3 t h−1 at average and the returned ore rate by 1.8–2.7%.

Research on the performance of modified blue coke in adsorbing hexavalent chromium

To solve the issue of hexavalent chromium (Cr(VI)) contamination in water bodies, blue coke powder (LC) was chemically changed using potassium hydroxide to create the modified material (GLC), which was then used to treat a Cr(VI)-containing wastewater solution. The differences between the modified and unmodified blue coke’s adsorption characteristics for Cr(VI) were studied, and the impact of pH, starting solution concentration, and adsorption period on the GLC's adsorption performance was investigated. The adsorption behavior of the GLC was analyzed using isothermal adsorption models, kinetic models, and adsorption thermodynamic analysis. The mechanism of Cr(VI) adsorption by the GLC was investigated using characterization techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), and X-Ray Photoelectron Spectroscopy (XPS). With the biggest difference in removal rate at pH = 2, which was 2.42 times that of LC, batch adsorption experiments revealed that, under the same adsorption conditions, the GLC always performed better than LC. With a specific surface area that was three times that of LC and an average pore diameter that was 0.67 times that of LC, GLC had a more porous structure than LC. The alteration significantly increased the number of hydroxyls on the surface of GLC by altering the structural makeup of LC. The ideal pH for removing Cr(VI) was 2, and the ideal GLC adsorbent dosage was 2.0 g/L. Pseudo-second-order kinetic (PSO) model and Redlich-Peterson (RP) model can effectively describe the adsorption behavior of GLC for Cr(VI). Physical and chemical adsorption work together to remove Cr(VI) by GLC in a spontaneous, exothermic, and entropy-increasing process, with oxidation–reduction processes playing a key role. GLC is a potent adsorbent that can be used to remove Cr(VI) from aqueous solutions.

Prediction of Sinter Properties Using a Hyper-Parameter-Tuned Artificial Neural Network.

The present work aims at performing prediction validation for the physical properties of coke layered and nonlayered hybrid pelletized sinter (HPS) using artificial neural networks (ANNs). Physical property analyses were experimentally performed on the two HPS products. The ANN model was then trained to obtain the best prediction results with the grid-search hyper-parameter tuning method. The learning rate, momentum constant, and the number of neurons varied over specified ranges. The binary variable conversion was utilized to assess the two sintering processes. The nonlayered HPS product of 4 mm micropellets at basicity 1.75 and using 8% coke shows a good combination of physical properties, whereas HPS of 4 mm micropellets at 1.5 basicity using 4% coke as fuel and 2% coke as layering gives a radical improvement in physical properties. The yield of the HPS product is 96.07%, with the shatter index (SI), tumbler index (TI), and abrasion index (AI) values being 86.12, 79.60, and 5.74%, respectively. Hence, HPS can be preferred by implementing the layering of coke powder. The prediction analyses showed that the multilayer perceptron model (MLP) network with a 4-29-5 structure showed prediction accuracies of over 99.99% and a mean squared error (MSE) of 2.87 × 10-4. It verifies the accuracy and prediction effectiveness of the hyper-parameter-tuned ANN model.

Gasification Behavior of Phosphorus during Biomass Sintering of High-phosphorus Iron Ore

Developing the innovative technology for efficient utilization of high-phosphate iron ore was the inevitable choice of resource strategy. In this paper, exploring a new method of gasification removal of phosphorus by iron ore sintering technology based on biomass. Combined with theoretical analysis and experimental research, the effects of different conditions (biochar type, addition proportion, basicity) on the reduction and gasification behavior of phosphorus were studied. The results showed that the addition of biochar instead of part of the coke powder could promote the reduction of apatite and increase the dephosphorization rate compared with the full coke breeze. Among different types of biochar fuels (fruit shell charcoal, straw charcoal, bamboo charcoal), bamboo carbon had the greatest effect on the dephosphorization rate. The optimal reduction temperature was 1100°C, substitution proportion of bamboo charcoal was 20% and basicity was 0.5 for the phosphorus gasification and removal, and the corresponding dephosphorization rate was 28.77%. Selective reduction of iron and phosphorus existed in the reduction process, iron oxide took precedence over the reduction of apatite, and part of phosphorus gas entered the metal iron to form iron phosphide, resulting in the decrease of dephosphorization rate.

Experimental Study on the Recovery of Arsenic and Iron from Arsenic–Iron Precipitate by Carbon Thermal Magnetization Reduction

Arsenic–iron precipitate was treated using a carbon thermal magnetization reduction method in order to recover arsenic and iron. Arsenic–iron precipitate mixed with coke powder was roasted at a low temperature; arsenic was recovered in the form of As2O3, and iron was recovered in the form of Fe3O4. The volatilization rate of arsenic was 97.45%, and the content of arsenic in the precipitate was decreased to 0.60%. Iron and arsenic were recovered in the form of Fe3O4 and As2O3 with a purity of 99.91 wt.% under the conditions of a roasting temperature of 650 °C, coke powder addition of 25 wt.%, a roasting time of 180 min, and an argon flow rate of 10 L/min. The volatilization of arsenic was controlled by a chemical controlling step at 20–100 min, and this was switched to a diffusion controlling step at 120–180 min by kinetic experiments. The reaction mechanism of arsenic and iron under carbon thermal magnetization reduction was as follows: in the early stage of the reaction, a large amount of FeAsO4 was decomposed into As2O3 and Fe3O4; in the middle and late stages of the reaction, FeAsO4 was continuously decomposed and reduced, and the content of Fe3O4 was continuously increased until all iron was magnetized to generate Fe3O4, and the decomposed As2O3 volatilized into dust. Arsenic reacted with CaO to generate Ca3(AsO4)2, and this may be the reason why arsenic could not be removed completely.