Metallurgical Coke Research Articles

Preheating upto Tarrification Point and Compaction: A Promising Way for Coke Quality Enhancement

ABSTRACT Coke producers are facing a tough challenge to produce good quality metallurgical coke at reasonable price due to decreasing availability and increasing cost of good quality hard coking coal.The use of alternative carbon source like non-coking bituminous coal, heat altered coking coal (Jhama), petcoke can be a way to address the problem. In this article, the effect of preheating and stamp charging of coal on coke quality parameters were studied and compared with the properties of coke produced in top charging and stamp-charging process. The effect of coal preheating before compaction on the properties of resulting cokes has been studied using five different types of coals. Five coal samples with different coking properties have been selected for the study. The Coal samples have been preheated to their tarification level and then stamped for compaction to higher bulk density before carrying out high-temperature carbonization. The most significant differences between cokes from preheating then compaction were observed in terms of CRI and CSR value. Significant differences of properties have been observed between coke samples produced in preheating followed by stamp-charging and the coke samples produced in top charging and normal stamp-charging technique.

Coking coal in the Alberta Plains Region, Canada

ABSTRACT In 2010, the author participated in an assessment of the coal deposits on Encana Corporation’s freehold lands in Alberta, Canada. He suggested that coal samples collected from a well in the Alberta Plains region that had penetrated the deep, Lower Cretaceous Mannville Group coal seams should be laboratory tested to determine whether this coal had metallurgical coking properties. Exploration and testing of coalbed methane in these coal seams prior to 2010 had indicated that the rank of this coal, determined using petrographic methods, was understated; however, a higher coal rank, determined using ASTM methods, suggested that these coal seams might have coking properties. Samples of coal cuttings from an approximately 4 m thick seam of Mannville Group coal that intersected in a well located a short distance southwest of Edmonton, Alberta, were sent to a coal laboratory for testing. Proximate and petrographic analyses show that coal from this Mannville Group seam has a rank of high volatile A to B bituminous. A coal marketing consultant reviewed the laboratory results and classified the sample as semi-soft coking coal.

Cupola Furnace Design and Fabrication for Industrial Development

The Cupola Furnace Capacity of 450 kilograms per hour was designed and fabricated using locally sourced raw materials which include pig irons, crop ends and foundry shop returns, and ferroalloys for the production of quality cast iron which depends on the customer’s demand. Metallurgical coke is the main fuel source employed for the production processes. The design parameters were analyzed and the metallic shells were then fabricated into four sections to allow proper lining. A mild 5 mm thick steel sheet was collected, marked out according to the required specification. slit and formed into cylindrical shapes. The sections were coupled and joined together through a welding process. Sodium silicate was used as a binder to make them bondable to the interior sections, the internal configurations were first lined with asbestos sheets measured 5 mm thick. with a less dense insulating refractory material. Fireclay refractory bricks were used for furnishing as they directly interfaced with the molten metal, while the flame blower was connected, assembled, and erected in the different segments. Financial analysis was performed to give a general overview of the cost of manufacturing and building a cupola furnace produced locally at N1,467,266.00, which is relatively cheap compared to the imported ones. The technical details were given for the production processes. The raw materials used were sourced locally as they are readily available in quantum and are essential to the government policies on adding values to the production processes by using these materials to promote the addition of these materials for the creation of local content.

Identification of preferential pathways in the pore microstructure of metallurgical coke and links to anisotropic strength properties

This paper has examined whether there are preferred pathways in the pore microstructure of coke. By modelling permeability and tortuosity in the digitised 3D structure obtained from 3D X-ray micro CT analysis of coke samples, preferred pathways were found to be perpendicular to the direction of applied force, i.e. parallel to the oven walls. The tortuosity was approximately doubled when moving from a direction of parallel to perpendicular with the oven wall and the permeability halved. It is hypothesised that applied force could squeeze the pore structure cutting off the openings in the direction toward the wall.Furthermore, by modelling mechanical properties of the digitised 3D structure it was also found that the Young’s modulus decreased by almost 25% going from the parallel to perpendicular direction (with respect to the oven wall). This result indicates that anisotropy in coke’s mechanical properties can occur. This anisotropy could have implications for coke strength. The coke might be more prone to breaking/shearing along particular planes when in the blast furnace. Furthermore, anisotropic permeability suggests that reactivity toward CO2 may also be anisotropic, and this could also have implications for strength deterioration behaviour in the blast furnace.The findings here are at a preliminary stage and it is recommended that the approaches developed here be applied to more coke samples to examine whether the findings here occur universally, and also the extent that anisotropic permeability and stiffness have implications for strength anisotropy during utilisation.

Cupola Furnace Design and Fabrication

The Cupola Furnace Capacity of 450 kilograms per hour was designed and fabricated using locally sourced raw materials which include pig irons, crop ends and foundry shop returns, and ferroalloys for the production of quality cast iron which depends on the customer's demand. Metallurgical coke is the main fuel source employed for the production processes. The design parameters were analyzed and the metallic shells were then fabricated into four sections to allow proper lining. A mild 5 mm thick steel sheet was collected, marked out according to the required specification. slit and formed into cylindrical shapes. The sections were coupled and joined together through a welding process. Sodium silicate was used as a binder to make them bondable to the interior sections; the internal configurations were first lined with asbestos sheets measured 5 mm thick. With a less dense insulating refractory material. Fireclay refractory bricks were used for furnishing as they directly interfaced with the molten metal, while the flame blower was connected, assembled, and erected in the different segments. Financial analysis was performed to give a general overview of the cost of manufacturing and building a cupola furnace produced locally at N1, 467,266.00, which is relatively cheap compared to the imported ones. The technical details were given for the production processes. The raw materials used were sourced locally as they are readily available in quantum and are essential to the government policies on adding values to the production processes by using these materials to promote the addition of these materials for the creation of local content.

Negatively Catalyzed Gasification Characteristics of Metallurgical Coke and its Implication for Ironmaking Process

Negatively Catalyzed Gasification Characteristics of Metallurgical Coke and its Implication for Ironmaking Process

Low-carbon production of iron and steel: Technology options, economic assessment, and policy

Summary Given increased urgency to transition the global economy to net-zero CO2 emission, governments and industry have increased focus on decarbonizing hard-to-abate sectors, including steel making, which contributes roughly 6% of global CO2 emission and 8% of energy-related emission (including power consumption emission). This paper reviews current global iron and steel production and assesses available decarbonization technologies, including hydrogen injection, solid biomass substitution, zero-C electricity substitution, carbon capture and storage (CCS) retrofit, and combinations of these decarbonization approaches. Blast furnace-basic oxygen furnace (BF-BOF) dominates production (71%) and is particularly stubborn to any decarbonization technology. Direct reduced iron to electric arc furnace (DRI-EAF) production is 5% and growing, it appears to have better decarbonization potential to move toward net-zero. Secondary steel production using mainly steel scrap in electric arc furnace (EAF-scrap) is 24% of global production and has both the lowest energy consumption and is technically simplest to decarbonize through electrification but is limited in market share to recycled steel capacity. Of the options assessed, blue hydrogen, carbon neutral biomass, and CCS appear to have the lowest cost and highest technical maturity. However, no single approach today can deliver deep decarbonization to the iron and steel industry and all approaches lead to substantial production cost increase. No uniform ideal solution exists, and different geographies, infrastructure, and economies will determine the local optimum solution with viability and cost. Policy measures will be required to provide financial incentives for decarbonization and to avoid unwelcome outcomes such as emissions leakage or job loss.

Study of possibilities to use coal of K<sub>18</sub> bed of “Abayskaya” mine of Karaganda coal field for the production of coke

I view of furnace equipment at coke-making plants getting old and deterioration of coal base, preliminary study of quality of coals, involved into production of metallurgical coke becomes more and more actual. Such a parameter of a coal, like spreading pressure during its coking if an item of particular interest. Results of a study of composition and properties of bed K 18 coal of “Abayskaya” mine of Karaganda coal field presented, as well as results of technical and chemical analysis of the coke. Study of spreading pressure during coking of bed K 18 coal concentrate and various charge mixtures with it was accomplished in a laboratory coking furnace, representing a steel container of rectangular form with dimensions 1000×200×600 mm. It was established that the studied coal had a high spreading pressure, reaching 31 KPa and was not inclined to shrinkage after sintering. Chronograms of temperature variation by coking zones presented as well as variation of spreading pressure during coking of K 18 coal. It was shown, that the coke obtained at K 18 bed coal coking had high indices of hot strength and reaction ability (56,8 % CSR, 22,9 % CRI). A method was elaborated to decrease the spreading pressure of bed K 18 coal and to reach maximum shrinkage of coke cake during coking by assortment of charge composition by mixing coal fines and concentrates from several coal mines. As a result of coal charges coking in an enlarged laboratory coking furnace, a charge composition was determined which enabled to use concentrate of K 18 bed coal of “Abayaskay” mine in a volume of 10% of the charge mass without exceeding acceptable spreading pressure of <7 KPa.

Effects of Briquetting and High Pyrolysis Temperature on Hydrolysis Lignin Char Properties and Reactivity in CO-CO2-N2 Conditions

Carbonaceous reductants for pyrometallurgical applications are usually obtained from fossil-based sources. The most important properties of the reductants greatly depend on the application and the feeding of the reductant into the process. However, the mechanical strength, calorific value, fixed carbon content, and reactivity of the reductant are the properties that usually define the applicability of the reductant for different processes. The reactivity of the biochars is usually high in comparison to metallurgical coke, which may restrict the applicability of the biochar in reduction processes. One cause of the higher reactivity is the higher surface area of the biochars, which can be suppressed with agglomeration treatment, e.g., briquetting. In this work, hydrolysis lignin was used for slow pyrolysis experiments to produce biochars. The biochars were pyrolyzed in briquetted form and in as-received form at various temperatures. The reactivity values of the biochars were tested in dynamic reactivity tests in a CO-CO2-N2 gas atmosphere at temperatures of up to 1350 °C. It was found that the yield of the hydrolysis lignin char only decreased by 3.36 wt% when the pyrolysis temperature was elevated from 600 to 1200 °C, while a decrease in yield of 4.88 wt% occurred when the pyrolysis temperature was elevated from 450 to 600 °C. The mass loss of hydrolysis lignin biochar in the reactivity experiment in CO-CO2-N2 atmosphere was significantly decreased from 79.41 wt% to 56.80 wt% when the hydrolysis lignin was briquetted before the slow pyrolysis process and the temperature of the pyrolysis process was elevated from 600 to 1200 °C. This means that the mass loss of the material was suppressed by 22.61 wt% due to the higher pyrolysis temperature and briquetting process.

Experimental research with the help of thermal derivatographic analysis on coal powder that can be blowed in the furnace

In an integrated steel flow, the costs related to the consumption of metallurgical coke represent approx. 25% of the production cost of the shards obtained by continuous casting. As the price of coal returns to about 50% of that of coke, the technology of insufflating coal dust at the blast furnaces mouths, which transfers the coking process to the blast furnace, can reduce the cost of slag by 4-5%. It cannot be used to blow into the furnace any type of coal. The coal used must meet certain requirements, based on its physical and chemical properties. By thermo-derivatographic analysis, important properties of coals can be established. The authors present in this paper the results of thermal derivatographic analyzes performed on certain types of coal.

Densification of Biocarbon and Its Effect on CO2 Reactivity

Charcoal is an interesting reducing agent because it is produced from biomass which is renewable and does not contribute to global warming, provided that there is a balance between the felling of timber and growth of trees. Biocarbon is a promising alternative to fossil reductants for reducing greenhouse gas emissions and increasing sustainability of the metallurgical industry. In comparison to conventional reductants (i.e., petroleum coke, coal and metallurgical coke), charcoal has a low density, low mechanical properties and high CO2 reactivity, which are undesirable in ferroalloy production. Densification is an efficient way to upgrade biocarbon and improve its undesirable properties. In this study, the deposition of carbon from methane on three types of charcoal has been investigated at 1100 °C. CO2 reactivity, porosity and density of untreated and densified charcoal were measured, and results were compared to metallurgical coke. Surface morphology of the charcoal samples was investigated by using scanning electron microscopy (SEM). SEM confirmed the presence of a deposited carbon layer on the charcoal. It was found that the CO2 reactivity and porosity of charcoals decreased during the densification process, approaching that of fossil fuel reductants. However, the CO2 reactivity kept higher than that of metallurgical coke.

To decarbonize industry, we must decarbonize heat

Summary Industry is often termed “hard to decarbonize” because a vast, inhomogeneous array of processes comprise the sector. But developing new, decarbonized process heating technologies represents a single, broadly applicable pathway to eliminating a large portion of sectoral emissions—and approximately one-fifth of global CO2 emissions, overall. We begin this perspective with a brief review of the demand for and cost of industrial heat. Then, we highlight key challenges and R&D needs in developing zero-carbon industrial heating technologies. Technologies in four pathways are discussed: (1) zero-carbon fuels, (2) zero-carbon heat sources, (3) electrification of heat, and (4) better heat management. Finally, we identify cross-cutting challenges to the development and adoption of zero-carbon industrial heat technologies, the solution to any of which would constitute a significant breakthrough on the path to industrial decarbonization.

The Properties of Carbon Blends in Submerged arc Furnaces

Charcoal was investigated as a renewable reducing agent to replace fossil fuel reductants in the metallurgical industry. Since a stepwise transition from fossil fuel-based reductants to renewable charcoal is expected, three charcoal blending ratios (20, 40 and 60%) were analysed. A procedure to determine the mechanical, chemical and electrical properties of carbon blends for submerged arc furnaces (SAF) was developed and evaluated by the stated three blending ratios of charcoal and metallurgical coke. The samples were investigated after heat treatment under pyrolysis and CO2 gasification conditions. The higher reactive carbon material (charcoal) was consumed by the Boudouard reaction, reducing its mechanical stability and affecting the generation of fines in consecutive analyses, e.g. the mechanical strength to withstand abrasion decreased. Chemical analysis showed only minor interaction between the carbon materials under pyrolysis conditions. The electrical resistivity of the carbon bed was mainly affected by the heat-treatment temperature and volume fraction of the carbon materials, in which a linear interpolation resulted in an acceptable accuracy. A volume fraction of at least 40% conductive material (coke) was required to enable an electrical conduction through the packed bed.

The Effect of Densification on Compressive Strength of Charcoal

Biocarbon is a promising alternative to fossil reductants for reducing greenhouse gas emissions and increasing sustainability of the metallurgical industry. In comparison to conventional reductants (i.e., petroleum coke, coal and metallurgical coke), biocarbon has low density and poor mechanical strength. Densification is an efficient way to upgrade biocarbon and improve its undesirable properties. In this paper, the deposition of carbon from natural gas on three different types of charcoal has been investigated. Charcoals have been heated in argon atmosphere in an induction furnace up to 1100℃. Then, the temperature was kept constant for 90 minutes while methane was purging with flow rate of 3 Lit/min. Density and compression strength were analyzed before and after heat treatment. The Scanning Electron Microscopy (SEM) was carried out on the samples to investigate the deposition. The compression strength improved considerably in all three types of charcoal and density increased. Carbon deposition is easily visible in SEM pictures for charcoals heat treated.

Attempts to replace nut coke with semi-coke for blast furnace ironmaking

Low coke rate for blast furnace operation has been required in response to the rising cost of coking coals. To extend the utilisation of coal resources, semi-coke has been introduced to blast furnace ironmaking process in recent years, however, there are still many issues unclear about the effect of semi-coke on ironmaking process. In this study, the possibilities of using semi-coke as alternative fuel for nut coke were studied. The characteristics of semi-coke including mechanical strength, high-temperature strength/reactivity, carbon gasification as well as direct reduction were studied and compared with small size metallurgical cokes (nut cokes). The results showed that semi-coke has higher CRI values, especially at higher temperatures and in a mix-charging pattern. Semi-coke was found to have a higher gasification reaction rate and depleted at lower temperatures. The reduction results showed that with participating of semi-coke the reaction starts at lower temperatures. In addition, the study suggested that semi-coke exhibits the advantages of low ash and sulphur contents, although it has lower mechanical strength, it would protect the lump coke by shifting the carbon gasification to itself, therefore, mixing semi-coke would benefit the blast furnace operation and lower the coke rate.

Synthesis of an industrial by-product-based polymeric additive for use with non-coking coal in metallurgical coke making and a combined density functional theory assessment of its molecular mechanism in fluidity development

Recently, the utilization of inferior grade coal for the production of fuel-based materials, i.e., metallurgical coke, is an exciting research area in the industrial sector because of the limited reserves of prime coking coal worldwide. In the steel industry, coal tar is the most abundant and sustainable cost-effective by-product, which is a source of an adequate amount of aromatic components such as phenol or its derivative with polycyclic aromatic hydrocarbons. Therefore, for the first time, we developed a novel organic polymeric additive through a cross-linking polymerization technique using a coal-tar precursor and paraformaldehyde monomer with a glycol-tetraline-based plasticizing agent and explored its application for use as inferior coal in metallurgical coke production. Our synthesized polymer was a homogeneous flowable liquid material; the synthesis process was simple, easily scalable with a high production yield (∼90%), and economical. The interaction of the polymeric additive with the coal matrix was investigated via TGA and H2 evolution study to understand the role of the polymer in coal carbonization. The polymeric additive has significantly improved the crucible swelling number (CSN), fluidity, and plastic layer thickness property of coal. In this connection, we also performed a computational study to rationalize the mechanism of action of the polymeric additive. Exploration of the reaction features through density functional theory calculations offered significant insight into the role of the polymer in assisting coal fluidity development. Addition of the polymer prominently enhanced the coke strength after reaction (CSR) of a non-coking coal enriched blend during carbonization. This study discloses new prospects in the steel industry for the sustainable and bulk scale synthesis of a coal tar-based polymeric additive for the profitable production of metallurgical coke.

Foamy slag practice to enhance the energy efficiency of electric arc furnace: An industrial scale validation

The aim of the present work is to demonstrate the importance of foamy slag practice during steelmaking in electric arc furnaces (EAF). Steel making practices with foamy slag in the EAF not only reduces the energy consumption but it also protects the refractory materials of furnace linings from the high energy intensity generated by electrodes. It also decreases the noise pollution in conjunction with reduced melting time during the process. Foamy slag practices in electric arc furnace operations persists since long in steel making industries but here authors tried to modify the aforesaid practice at the concern plant in most economical way without impairing the steel quality.In the present study a process-controlled feeding of fine metallurgical coke for optimized foaming has been developed and simultaneous increment in energy efficiency has been noticed by collecting and analyzing the process related data. To carry out the present study more than 140 heats have been taken into consideration, with and without foamy slag generation in electric arc furnace. Considerable reduction in the electrical energy consumption (i.e. from ∼510 kwh per tone to ∼450 to 460 kwh per tone) has been noticed along with the reduction in total melting time from ∼87 min to ∼76 min. Present work also confirms that optimized met coke injection in the range of 15–18 kg/tone certainly helps in increasing the foaminess of the slag. FeO content of the slag was also assessed and found in the range of 17–21 wt% having the basicity of 1.8–2.2, which is a good agreement in prospects of yield as well as quality of the steel.

Adsorption method for determining the texture characteristics of Kuzbass fossil coals of the metamorphism series

The presented work is devoted to the study and development of a technique for measuring the parameters of the porous structure of fossil coals in Kuzbass by the adsorption method on an ASAP 2020 analyzer “Micromeritics”. The conditions for sample preparation of samples were selected, which make it possible to record reproducible isotherms of low-temperature adsorption-desorption of nitrogen (77K) by the studied samples of fossil coal of various grades. The obtained isotherms of low-temperature adsorption-desorption of nitrogen were used to determine the textural characteristics of Kuzbass fossil coals by various methods (the specific pore surface area was calculated using the Brunauer-Emmett-Taylor (BET) method; the volume of micropores was determined using the comparative t-Plot method; the mesopore volume was determined using the method of Barrett-Joiner-Halenda (BJH). The obtained values of the textural characteristics of Kuzbass coals of the metamorphism series make it possible to reveal their macro-and microstructural features, to obtain information on the adsorption properties of coal, and can also be used to optimize coal use processes, such as the extraction of methane from coal seams, gasification, combustion, liquefaction, beneficiation, production of metallurgical coke.

Catalysis mechanism of solution loss reaction of metallurgical coke in blast furnace: Experimental and modeling study

Carbon solution loss (SL) reaction significantly affects the performance of metallurgical coke in blast furnace. Unfortunately, the mechanism of SL of coke remains unclear to date. This work investigated the catalytic mechanism of coke SL with both molecular dynamic modeling and experiments using cokes loaded Na2CO3, CaCl2, FeCl3 and H3BO3. The positive catalysis of Na2CO3, CaCl2 and FeCl3 while the counter catalysis of H3BO3 were observed with experiments. Kinetic analysis revealed that the positive catalysts notably reduced while the counter catalyst improved the activation energy of SL reaction of coke. The catalytic mechanisms were further elucidated with the molecular dynamics simulation. The planar nucleophilic semi-quinone structures formed between coke molecule and Na or Fe atoms promoted SL reaction thus showing positive catalysis. On the contrary, the electrophilic B2O3 resulted from the combination of B atoms and CO2 inhibited the SL reaction hence manifesting counter catalysis.

Optimizing the coke oven process by adjusting the temperature of the combustion chambers

Metallurgical coke is obtained from coal and is a fuel and raw material for the iron and steel industries. However, only 15% of the world’s coal reserves have the required properties for metallurgical coke, which makes the useful coal expensive. Transforming coal into metallurgical coke is an energy-intensive endeavor, and global competition requires worldwide steelmakers to be more efficient in terms of energy consumption, therefore the optimization of the coke production process has become increasingly decisive. The objective of this study was to develop a rigorous model of the coke oven process by separately considering the coke oven, combustion chamber, and regenerative bed. In this study, the coke oven was divided into zones according to the number of available temperature measurements in each combustion chamber. The developed model using Aspen Plus™ was used primarily to obtain a more uniform combustion chamber temperature profile and to investigate the effect of the combustion chamber temperature profile on the fuel consumption. The results were validated from the plant data for temperature, flowrate, and composition. A new set of operating conditions was implemented, and the consumption of coke oven gas was reduced by approximately 12%.