Metallurgical Coke Research Articles

A Comprehensive Review on Blast Furnace

The design and control of blast furnace (BF) ironmaking must be optimized in order to be competitive and sustainable, particularly under the more and more demanding and tough economic and environmental conditions. To achieve this, it is necessary to understand the complex multiphase flow, heat and mass transfer, and global performance of a BF. In this paper injection of alternative reducing agents via lances in the tubers of blast furnaces is discussed to reduce the consumption of metallurgical coke. Besides liquid hydrocarbons and pulverized coal the injection of recycled waste plastics is possible, offering the opportunity to chemically reuse waste material and also utilize the energy contained in such remnants.

Intelligent Monitoring Network Construction based on the utilization of the Internet of things (IoT) in the Metallurgical Coking Process

Abstract With the development of the Internet of Things (IoT), a new and important research direction is possible using IoT to solve the problems of information and intelligence in the metallurgical industry. This paper proposes an intelligent monitoring network based on networking technology and uses the coking process as the research object. The construction of a coking process intelligence monitoring network should focus on the formation of a perception layer network and build on a ZigBee mesh clustered network. Moreover, it also puts forward a network routing establishment and data transmission mechanism. This study provides an effective reference for the wide application of the IoT in the intelligent management and monitoring of the metallurgical process.

Relationship of Coke Reactivity and Critical Coke Properties

The gasification reactions of five metallurgical cokes were studied using a thermogravimetric analyzer at 1273 K and 1673 K in CO2-CO-N2 gas mixture. The results show that these cokes showed different reactivities in the gasification reactions. Properties that potentially influence coke reactivity including ash content, catalytic index, surface area, and crystallite size were measured and correlated with reactivity. The results indicate that reactivity had a good correlation with ash content, catalytic index, and crystallite size. The effect of surface area on coke reactivity was marginal. Coke reactivity was positively affected by catalytic index but inversely affected by ash content. Although crystallite size inversely affected reactivity, the reaction rate at the initial stage was more predominantly influenced by the mineral matter. Therefore, the influence of surface area and crystallite size was overshadowed by the impact of ash content and catalytic index at the initial stage of reaction.

Tribological Testing of Metallurgical Coke: Coefficient of Friction and Relation to Coal Properties

Tribological testing and analysis of metallurgical-grade cokes were conducted to elucidate the nature of the surface of each coke and the influence of the surface on coke abrasion resistance. The c...

Effects of Porosity and Electrical Resistance of Metallurgical Coke and Semicoke on Silicon Recovery in an Electric Arc Furnace

The effects of the electrical resistance and porosity of two types of coke used in ferrosilicon electric arc furnaces were investigated to determine the silicon recovery from quartz rock ( $$ {\text{SiO}}_{2} $$ ). To investigate the effect of the electrical resistance and porosity on the quartz recovery rate, semicoke and metallurgical coke were separately tested in ferrosilicon arc furnaces. The product was quantitatively and qualitatively studied. The results showed that the higher electrical resistance and porosity of semicoke, in comparison with metallurgical coke, increased the efficiency of silicon recovery and also reduced the electrical energy consumption. The furnace efficiency when using semicoke and metallurgical coke was 90.8% and 80.5%, respectively.

THE APPLICATION OF RIDGE REGRESSION METHODS WHEN COMBINING FORECASTS

Forecasting of economic indicators with time series using one or another method or another but the only method leads to the situation that all the information contained in other forecasting methods is usually discarded. The information that is ignored may contain information that allows other features of the economic process to be assessed. Combining forecasts makes possible to take into account almost all the information contained in particular forecasts. In the article, we present the analysis of the application of the method of regression analysis, in particular, ridge regression for finding the weighting coefficients of the particular forecasts in the combined forecast. We compared the accuracy of prediction based on the ridge regression with other methods of combining predictions. The purpose of our research work was an analysis of the most common methods of combining forecasts — various modifications of Granger-Ramanathan methods and comparison with a new approach of combining forecasts based on the ridge regression for its use in practice. We used statistical methods of time series forecasting (the method of harmonic weights, adaptive exponential smoothing using a tracking signal, the method of simple exponential smoothing and the Box-Jenkins model), the method of constructing combined forecasts, as well as methods of regression analysis. As a result, we built the combined forecasts based on annual data for the period from 1950 to 2015 on the production in Russia of some products: steel, metallurgical coke, pulp, plywood, cement. We used the methods of Granger-Ramanathan (without restrictions and with restrictions on the sum of coefficients in partial predictions) and also the ∆-coefficients obtained by the ridge regression method. The forecasts constructed using the Granger-Ramanathan methods give the highest accuracy of the combined forecast. The method based on the ridge regression is less accurate, but better than the separate predictions. At the same time, the proposed method of calculating the weight coefficients on the basis of the ridge regression has a well- developed scheme of calculation and eliminates the negative weight coefficients in the combined forecast.

Characterization and reactivity of charcoal from high temperature pyrolysis (800–1600 °C)

This study presents the effect of wood origin and heat treatment temperature on the CO2 reactivity, nanostructure and carbon chemistry of chars prepared at 800, 1200, and 1600 °C in slow pyrolysis reactors. The structure of charcoal was characterized by transmission electron microscopy, Raman spectroscopy, mercury intrusion porosimetry and N2 adsorption. The CO2 reactivity of char was investigated by thermogravimetric analysis. Results showed that spruce and oak chars have similar reactivity at all heat treatment temperatures. The oak char prepared at 1600 °C contained long and flat graphene layers and interplanar distance that is similar to graphite and thus, was more ordered than the spruce char. The TEM analysis showed that charcoal had structural characteristics of non-graphitizing carbon. Thus, increasing heat treatment temperature increases the graphitization of char structure, leading to the reactivity that is nearly similar to that of low reactive metallurgical coke. The wood origin, heat treatment temperature, nanostructure, differences in porosity and pore size of char influenced the CO2 reactivity less than the differences in CO2 concentrations.

Comprehensive evaluation of inherent mineral composition and carbon structure parameters on CO2 reactivity of metallurgical coke

In order to obtain a comprehensive understanding of the influence of both inherent minerals and carbon crystalline structure parameters on coke reactivity index (CRI), 30 industrial metallurgical cokes were selected and their mineral composition were quantitatively determined by X-ray diffractometer (XRD) and TOPAS software, the influence of inherent minerals was further investigated by the TGA. The mineral catalysis index (MCI) and carbon crystalline structure parameters were correlated with the CRI. The results show that: (1) CRI can be expressed as function of MCI with R2 equal to 0.6548: CRI = 7.7037MCI + 6.8564; (2) Main crystalline minerals in cokes include mullite, quartz and cristobalite (the sum is more than 80%), oldhamite, anhydrite and hedenbergite also exist in coke with small amount. The reactivity index improved linearly, from 0.049 increased to 0.059 (increased 20.41%) with addition of 8% CaS, which indicate that CaS has an apparent catalytic effect on coke gasification; (3) Both carbon structure and MCI have a significant influence on coke’s CRI. When MCI < 3, carbon structure is the primary factor affecting the CRI, with Lc, La and fa increasing, CRI decreased; when MCI ≥ 3, CRI increased with Lc, La and fa, the mineral composition is the principal factor affecting the CRI.

The effect of feedstock origin and temperature on the structure and reactivity of char from pyrolysis at 1300–2800 °C

This study reports the effect of feedstock origin, residence time, and heat treatment temperature on CO2 and O2 reactivities, nanostructure and carbon chemistry of chars prepared at 1300, 1600, 2400, and 2800 °C in a slow pyrolysis reactor. The structure of char was characterized by transmission electron microscopy and Raman spectroscopy. The CO2 and O2 reactivity of char was investigated by thermogravimetric analysis. Results showed that the ash composition and residence time influence the char reactivity less than the heat treatment temperature. The heat treatment temperature and co-pyrolysis of pinewood char with biooil decreased the CO2 reactivity, approaching that of metallurgical coke. Importantly from a technological standpoint, the reactivities of char from high temperature pyrolysis (2400–2800 °C) were similar to those of metallurgical coke, emphasizing the importance of graphitizing temperatures on the char behavior. Moreover, graphitization of chars from wood and herbaceous biomass increased with the increasing heat treatment temperature, leading to formation of graphitizing carbon.

Transformation of Coke Carbon Textures and Minerals during Gasification Investigated by SEM/EDS

The carbon textures, minerals, and their interactions of a metallurgical coke during gasification reaction were investigated using scanning electron microscopy/energy dispersive spectroscopy by analyzing exactly the same sites of coke surfaces before and after reaction. The results indicate that most inert maceral-derived component (IMDC) had a greater propensity to react with CO2 than the reactive maceral-derived component (RMDC). A portion of the carbon in mineral-carrying IMDC was removed as a result of the reaction with CO2, leaving minerals, primarily alumino-silicates, more pronounced. However, the reactivity of IMDC was found to be similar to that of RMDC in some cases. The physical features of the alumino-silicates in the coke were barely altered but bound with alkalis during the reaction. The Fe-containing phases were highly active and had strong interactions with the carbon matrix. Voids were formed in the carbon matrix associated with the Fe-containing phases as a result of the catalytic carbon...

Estimating coke fracture toughness using acoustic emissions and changes in coefficient of friction during scratch testing

Acoustic emission profiles generated during scratch testing of a range of metallurgical coke samples were recorded and linked to the concurrent energy release, dispersal or absorption on coke fracture or damage. Three different signatures were identified, which were based on the simultaneous measurement of acoustic and total energy release profiles, and these signatures could be correlated with both the microstructure and microtexture of the coke being traversed at the time. The acoustic emission signature for fracture or damage to the coke reactive maceral derived constituents (RMDC) was correlated to the rank of the parent coal or coal blend, with the signature number generally increasing with increasing rank. Conversely, the signature numbers did not vary with parent coal rank for fracture or damage to the inertinite maceral derived constituents (IMDC), with the majority of IMDC fractures associated with a release of mechanical energy. The incidence of the signature associated with a release of mechanical energy (type 1) became increasingly dominant from RMDC to RMDC-IMDC interfaces to IMDC. Conversely, signature types associated with a dispersal (type 2) or absorption (type 3) of mechanical energy become increasingly dominant from IMDC to RMDC-IMDC interfaces to RMDC. The findings suggest acoustic emissions recorded during scratch testing and their subsequent characterisation can be used to indicate the fracture toughness of a given coke. This study contributes towards a broader program of research to improve understanding of the factors which influence the strength of coke and its microtextural constituents and interfaces, and how this relates to the properties of the parent coals.

Carbon Dissolution Using Waste Biomass—A Sustainable Approach for Iron-Carbon Alloy Production

This paper details the characterisation of char obtained by high-temperature pyrolysis of waste macadamia shell biomass and its application as carbon source in iron-carbon alloy production. The obtained char was characterised by ultimate and proximate analysis, X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray photon spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area via N2 isothermal adsorption and scanning electron microscopy (SEM). The results indicated that obtained char is less porous, low in ash content, and high in carbon content. Investigation of iron-carbon alloy formation through carbon dissolution at 1550 °C was carried out using sessile drop method by using obtained char as a carbon source. Rapid carbon pickup by iron was observed during first two minutes of contact and reached a saturation value of ~5.18 wt % of carbon after 30 min. The carbon dissolution rate using macadamia char as a source of carbon was comparatively higher using than other carbonaceous materials such as metallurgical coke, coal chars, and waste compact discs, due to its high percentage of carbon and low ash content. This research shows that macadamia shell waste, which has a low content of ash, is a valuable supplementary carbon source for iron-carbon alloy industries.

Study on CO2 Gasification Reactivity and Structure Characteristics of Carbonaceous Materials from the Corex Furnace

The gasification reactivities of four pretreated carbonaceous materials from the Corex furnace, including one coal char, two metallurgical cokes, and one recycling dust, were investigated by a thermogravimetric analyzer, in which the recycling dust came mainly from two metallurgical cokes and accounted for a mass fraction of 71.3%. The physicochemical properties of the different samples were tested systematically. The results showed that the recycling dust had a gasification reactivity similar to the coal char, of which the value was higher than those of the two metallurgical cokes. The structure analysis ascertained that the main factor that affected the gasification reactivity was the carbonaceous structure. Moreover, to characterize the reactive behavior of the different samples, three nth-order typical gas–solid reaction models were employed in this study. It has been found that the random pore model was the best model. The activation energies of different chars were in the range of 181.1–202.3 kJ/mol.

Uniaxial compression of metallurgical coke samples with progressive loading

Coke samples, produced from coals having a range of rank and vitrinite content, were subjected to uniaxial loading in a universal tester. Cokes were also imaged at high resolution using micro-CT. The aim was to understand the relationship between the internal microstructure of the coke and coke strength under load. The loading was done in two separate ways, being either compression to failure or progressive loading. The results showed that the coke samples underwent a form of stiffening at low loads, potentially due to closing of fine-scale pores and/or re-alignment of graphitic layers in the RMDC. Measurements of plastic strain indicated that these changes were permanent. At higher loads, small load-bearing components of the microstructure were found to break, leading to a softening of the coke samples. Evidence of the breaking was observed using micro-CT images before and after loading of samples. The work has relevance to the understanding of the fundamentals of coke strength, as well as to issues relating to handling and preparation of coke for standard testing.

Sustainable development of selective iron carbide, silicon carbide and ferrosilicon (low temperature) phases during iron ore reduction using only polymers

Production of selective iron phases of iron carbide (nanoscale<2nm), silicon carbide or ferrosilicon using polymer resins and hematite is presented. Commercial epoxy resin, epiglue and silicones are used. Nonrenewable resources such as coke or high pure quartz are not used. A solid-liquid reaction provides for better intimate contact and reaction efficiency. Viscous epoxy and silicone resins can completely wet the reactants forming interfacial covalent bond between the metal oxide and the desired elements in the resins when cured at room temperature for 24h, while facilitating migration of desired elements into iron matrix during reduction of hematite. Secondary ion mass spectroscopy, X-ray diffraction, Scanning Electron Microscopy and off gas studies confirmed the formation of iron alloy phases. The study opens pathway for feedstock recycling of silicones maximizing resource recovery reducing the landfill/depolymerization of silicones. The valuable resources such as silicon, carbon and hydrogen in waste silicones, can replace metallurgical coke and quartzite as alloying elements in FeSi or SiC. Recyclable bioepoxy resin /bio renewable/recycled epoxy resin, which will otherwise be landfilled or incinerated, make this process sustainable, cleaner and cost-effective. FeSi formation at much lower temperature (~1500°C) as opposed to very high temperatures (>1800°C) spells energy savings and emission reductions. A potential replacement of nonrenewable coke by the composites of the resins and iron oxide as spacer provides for added benefit. The SiC, Fe3C and ferrosilicon find application in the economical production of high pure hydrogen and photovoltaic industry.

Gasification of metallurgical coke in CO2-CO-N2 with and without H2

The reaction kinetics of the gasification of a metallurgical coke was investigated using a thermogravimetric analyzer (TGA) in the temperature range of 1173–1873 K, particle size of 200–2000 μm, and CO2 content of 5–20 vol% in CO2-CO-N2 and CO2-CO-H2-N2 gas mixtures. The gasification rate in the presence of H2 is significantly higher than that without H2 at lower temperatures. The enhancing effect of H2 diminishes with temperature increase. Two temperature zones corresponding to chemical reaction controlled regime and diffusion controlled regime are identified. The reaction transitions from chemical reaction control to diffusion control at 1467 K for gasification without H2 in comparison to 1364 K with H2. It indicates that diffusion becomes the controlling step at a lower temperature in the H2-containing gas mixture due to the generation of H2O through water-gas shift reaction. With increasing gasification rate with temperature, the gasification becomes controlled by the diffusion of CO2, which is further demonstrated by the decreasing reaction rate with increasing particle size and the increasing reaction order as temperature increases.

Occurrence and Behavior of Sulfur‐Bearing Minerals in Metallurgical Coke

The behavior of sulfur‐bearing minerals is characterized from coking coals to the feed coke and the blast furnace (BF) coke using field emission scanning electron microscope and thermodynamic calculations. In coals, they are represented by sulfides (pyrite, sphalerite, galena, chalcopyrite, and arsenopyrite) and sulfates (anhydrite and barite). During coking process, the minerals undergo phase transformations, but sulfur will be retained in the coke in mineral form for most of the minerals until the end of the coking process. Depending on the initial mineral in the coal, sulfur‐bearing minerals will be transformed at the end of coking process into the following phases: pyrrhotite, wurtzite, Cu–Fe–S melt, CaS, and BaS. The amount of sulfur that will be kept in the coke in mineral form increases in the following order: galena → pyrite → sphalerite → arsenopyrite → chalcopyrite → anhydrite → barite. Intensive gas flow under BF conditions facilitates liberation of sulfur from mineral phases in the Fe–S and Zn–S system. CaS and BaS are the most stable sulfur‐bearing phases formed after sulfur‐bearings minerals. The coals with elevated amounts of anhydrite and barite, or with high concentrations of Ca and Ba combined with S should be avoided for coking purposes. Complete elimination of mineral‐related sulfur from coke under BF conditions occurs above 2000 °C.

Effect of basicity and reductant amount in the nickel pig iron (NPI) production from Indonesian limonite ore in submerged electric arc furnace (SAF)

The effect of basicity and reductant amount on the nickel and iron recovery of the nickel pig iron (NPI) production from Indonesian limonite ore was investigated in the experimental study using submerged electric arc furnace (SAF). Indonesian limonite ore used in this study originated from Sulawesi Island with the composition of Ni (1.26%) and Fe (43%). Metallurgical coke was applied as the reductant. This study showed that the the highest nickel and iron recovery as well as metal yield can be resulted from the basicity of 0.8 and reductant amount of 0.23 kg coke/kg limonite ore. Nickel content in the NPI produced was around 3 – 4%. It was concluded that this experiment can produce medium grade NPI.

Enrichment of reactive macerals in coal: its characterization and utilization in coke making

Macerals in coal are of different types: reactive and inert. These macerals are differ in their physical and chemical properties. Column flotation method has been used to separate the reactive macerals in a non-coking coal. The enriched coal is then characterized in order to understand the changes in the coking potential by different techniques. It is then used in making of metallurgical coke by proper blending with other coals. Enriched coal enhance the properties of metallurgical coke. This shows a path of utilization of non-coking coal in metallurgical coke making.

Основные тенденции мирового производства металлургического каменноугольного кокса. еврококс 2018

Основные тенденции мирового производства металлургического каменноугольного кокса. еврококс 2018