Furnace Carbon Research Articles

The effect of decarburisation on creep deformation: application to magnesium reduction steel retort tubes

ABSTRACT This paper studies high-temperature creep deformation of Mg retort tubes considering the decarburisation of steel. A material model was developed for finite element modelling that relates the activation energy of steel in the steady-state creep rate equation (Q) to its carbon content. Carbon content was described as a function of radial position along the retort thickness (r) and service time (t). The time-dependent activation energy, Q(C(r,t)), was incorporated in the steady-state creep equation. The FEM results of the decarburising model were compared to those of the non-decarburising model and an actually failed retort for verification. The newly developed model presents more accurate results compared to the constant material model (non-decarburising). The FE model was used to predict the effects of various process parameters (temperature, internal pressure, and furnace carbon activity) and geometric parameters (retort diameter and thickness) on the creep deformation of retorts.

Basic Properties of Pyrolysis carbon black of Waste Tyres and Application of Pyrolysis carbon black in Transition Layer Rubber of All Steel Radial Tire

The main chemical composition of pyrolysis carbon black of waste tires is C, O, Cu, Zn and so on. The content of ash and fine powder in pyrolysis carbon black is high, and the 300% elongation stress is high. The difference between pyrolysis carbon black and furnace black N326, which is commonly used in rubber, is obvious compared with chemical property. The pyrolysis carbon black was used to replace furnace black N326 in the transition layer of all steel load Radial tire rubber through experimental study. It was found that the compression heat generation and dynamic loss (Tanδ) of the blend rubber before and after aging were obviously reduced, the elongation at break and resilience increased, while the tensile stress and tear strength decreased by 100% and 300% , but the hardness and tensile strength changed little before and after aging. According to the latest raw material price calculation, 15 used tire pyrolysis carbon black instead of furnace carbon black N326 used in all steel Radial tire transition layer rubber application, excluding labor costs, electricity and equipment depreciation, a ton of blended rubber saves about $22.86 in production costs.

Thermodynamic Model of Silicon Smelting in Ore-Smelting Furnaces

Silicon production by silica-containing raw material reduction by carbon in ore-smelting furnaces (OSF) is a complex pyro-metallurgic process. Silicon is produced in a system consisting of charge, furnace electrodes, air, melt, slag, and gases at temperatures above 2000°C, which generates silicon monoxide and carbide unavoidably. The finished product contains impurities (Fe, Ca, Al, Ti, etc.) in small amounts; however, it is still unknown for sure how impurities, contained in raw materials, behave and interact with each other and with silicon. To analyze the distribution of charge components during smelting, the research team used thermodynamic (mathematical) modeling in Selector software. The constructed four-tank silicon production model describes adequately the process. The assumed tank temperatures correspond to the OSF reaction zones (400°C, 1530°C, 2200°C, and 2000°C). Modeling involves 15 charge-carried elements: quartzite from the Cheremshanskoye deposit, charcoal and black coal, petroleum coke, wood chips, and OSF coal electrodes. According to the model, silicon recovery (with a 97.15 wt% silicon content in the melt) is 75%, which is consistent with literature and production data (AO Kremniy, Shelekhov, Irkutsk Oblast).

Removal of pharmaceutical compounds from aqueous solution by novel activated carbon synthesized from lovegrass (Poaceae).

In this work, lovegrass (Cpa), an abundant grass of the Poaceae family, was employed as feedstock for the production of activated carbon in a conventional furnace using ZnCl2 as a chemical activator. The prepared material (Cpa-AC) was characterized by pH of the point of zero charges (pHpzc), Boehm's titration method, CHN/O elemental analysis, ATR-FTIR, N2 adsorption/desorption curves, and SEM. This carbon material was used for adsorption of acetylsalicylic acid (ASA) and sodium diclofenac (DFC). FTIR analysis identified the presence of O-H, N-H, O-C=O), C-O, and aromatic ring bulk and surface of (Cpa-AC) adsorbent. The quantification of the surface functional groups showed the presence of a large amount of acidic functional groups on the surface of the carbon material. The isotherms of adsorption and desorption of N2 confirm that the Cpa-AC adsorbent is mesopore material with a large surface area of 1040 m2g-1. SEM results showed that the surface of Cpa-AC is rugous. The kinetic study indicates that the system followed the pseudo-second-order model (pH 4.0). The equilibrium time was achieved at 45 (ASA) and 60min (DCF). The Liu isotherm model best fitted the experimental data. The maxima sorption capacities (Qmax) for ASA and DFC at 25°C were 221.7mgg-1 and 312.4mgg-1, respectively. The primary mechanism of ASA and DFC adsorption was justified considering electrostatic interactions and π-π interactions between the Cpa-AC and the adsorbate from the solution.

Получение керамики на основе карбида кремния из золошлаковых отходов

The paper shows the possibility of obtaining bulk samples of solid ceramics based on silicon carbide obtained from ash waste. The process is implemented in three stages: the initial ash waste was treated with a carbon plasma of a direct current arc discharge under ambient air conditions using a vacuumless method, then the obtained powder material was purified from unbounded carbon in an atmospheric furnace, and at the final stage the powder product was sintered by the plasma spark sintering method. According to analytical methods, the result is a ceramic based on silicon carbide with a density of 3.05 g/cm3 and a hardness of up to 19.9 GPa.

Synthesis of 2-Alkylbenzimidazole moiety as a novel antioxidant and its effect on physico-mechanical and electrical properties of acrylonitrile butadiene rubber

In the present work, 2-propyl-, and 2-heptyl-, 1H-benzo[d]imidazole were prepared by condensation reaction of o-phenylenediamine with n-butanoic acid and n-octanoic acid, respectively. The prepared products were characterized by FT-IR, 1H-NMR spectroscopy and melting point. These products were incorporated into acrylonitrile butadiene rubber (NBR) composites with two different fillers (Silica and High Abrasion Furnace carbon black HAF) as an antioxidant additive with different concentrations from 1up to 2 phr as a comparison with 2,2,4-trimethyl-1,2-dihydroquino-line (TMQ) as a traditional antioxidant. Their effects on the rheometric, physico-mechanical and electrical properties of NBR composites were evaluated. Thermo-oxidative aging was carried out for NBR composites and distribution of the prepared products observed by Scanning Electron Microscope (SEM).The results showed that the prepared products can act as highly efficient antioxidants in acrylonitrile butadiene rubber vulcanizates comparing with commercial antioxidant TMQ and revealed that there was enhancement in mechanical properties of NBR composites that containing the prepared products, as well. The results also illustrated that the optimum ratio from 2-alkylbenzimidazole incorporated into acrylonitrile butadiene rubber vulcanizates is 1.5 phr if compared with the same ratio from traditional antioxidant (TMQ).

The Influence of Slag Tapping Method on the Efficiency of Stabilization Treatment of Electric Arc Furnace Carbon Steel Slag (EAF-C)

Studies conducted over the past 10 years have demonstrated the technical suitability of the electric arc furnace slag as an alternative to natural stone in several applications. Steel slag can be profitably used as a road surface layer, for foundations and embankments, or for concrete aggregates. However, a strong limitation to their use is due to the presence of toxic metals (Ba, Cr, V, Mo, etc.) that can be released into the environment in particular conditions, especially for unbound products in which the slag can come into contact with water. Recent studies have investigated the role of chemical composition and microstructure of slag on toxic metal leaching, allowing for the design of suitable stabilization treatments for hindering such leaching. In this work, four batches of electric arc furnace carbon steel slag underwent a stabilization treatment and the obtained results were compared. In two batches, the stabilizer was added directly in the slag pot and the slag was cooled down in the same pot. The other two batches were stabilized during the downfall from slag door to slag pit. Several slag samples were collected before and after the stabilization treatment and were characterized by means of ED-XRF, XRD, and SEM analysis. Leaching tests were carried out in agreement with EN 12457-2 standard on 4 mm granulated slag, and the leachate concentration was compared with the current Italian limits listed in D.M. 3 August 2005 N. 201 and D.M. 5 April 2006 N. 186. The results clearly indicated that the cooling in the slag pot improved the efficiency of the stabilization treatment, leading to a complete transformation of the microstructure by a full development of homogeneous gehlenite matrix and a coarsening of Cr-spinels, assuring better toxic metal retention behavior. On the contrary, stabilization in the slag-pit was rapid and reduced the interaction between slag and stabilizer, leading only to partial transformation of larnite into gehlenite, and also reducing the coarsening of Cr-spinel. In addition, a layering effect was observed, resulting in an inhomogeneous product from top to bottom in terms of chemical composition, microstructure, and leaching behavior.

An Experimental Study on the Reduction Behavior of Dust Generated from Electric Arc Furnace

To improve the utilization value of electric arc furnace dust (EAFD) containing zinc, the reduction behavior of non-agglomerate dust was investigated with carbon and ferrosilicon in an induction furnace. The experimental results show that when the temperature increases, the zinc evaporation rate increases. When the reducing agent is carbon, zinc evaporation mainly occurs in the range of 900–1100 °C. When the reducing agent is ferrosilicon, zinc begins to evaporate at 800 °C, but the zinc evaporation rate is 90.47% at 1200 °C and lower than 99.80% with carbon used as a reducing agent at 1200 °C. For the carbon reduction, the iron metallization rate increases with a rise in the temperature. When the reducing agent is ferrosilicon, with an increase in temperature, the metallization rate first increases, then decreases, and finally, increases, which is mainly due to the reaction between the metallic iron and ZnO. In addition, the residual zinc in the EAFD is mainly dispersed in the form of a spinel solution near the metallic phase.

Modern blast furnace ironmaking technology: potentials to meet the demand of high hot metal production and lower energy consumption

Iron and steel making is one of the most intense energy consuming in the industrial sectors. The intensive utilization of fossil carbon in the ironmaking blast furnace (BF) is related directly to CO2 emission and global warming. Lowering the energy consumption and CO2 emission from BF comes on the top priorities from both economic and environmental aspects. The BF has undergone tremendous modifications and development to increase production and improve the overall efficiency. Both technological development and scientific research drive one another to reach optimum operation conditions, which are very close to the ideal conditions; however, further development is still required to meet the stringent environmental regulations. The present article provides a comprehensive review of recent research and development which were carried out in modern blast furnace to increase the productivity meanwhile reduce the energy consumption and CO2 emission to meet the demand of steel market and the environmental protection. The recent technological and metallurgical improvements in the BF are intensively discussed including: (i) modifications of BF design, top charging and measuring system, (ii) upgrading of conventional top charging burden and alternative agglomerates, (iii) developing of tuyeres injection system and injected materials, and (iv) potentials of waste heat recovery and usage. These topics are reviewed and discussed in some details to elucidate the potential of recent progress in BF technology in saving the energy consumption and lowering CO2 emission. In this paper, the major research and development which have been carried out in ironmaking BF technology are reviewed with an overview of the future prospects.

Carbonaceous Material Properties and Their Interactions with Slag During Electric Arc Furnace Steelmaking

The state of the interface between slag and carbon determines the slag foaming behavior and thus the effectiveness of carbon in electric arc furnace (EAF) steelmaking. This paper explores the interaction between synthetic slag and carbonaceous materials derived from various sources, including bio-char produced by two different technologies, graphite, coke, and char from tire pyrolysis. Different interfacial phenomena were found between slag and the carbonaceous materials examined. The interactions between bio-char and slag are found to be poor in comparison with other carbonaceous materials. Carbonaceous materials were characterized in terms of their chemical composition and the results obtained suggested that interfacial phenomena were not dominated by ash in the carbonaceous material. The effects of carbon crystalline structure on interaction with slag were evaluated by Raman spectroscopy and X-ray diffraction. Surface properties of the samples were evaluated using scanning electron microscopy, and surface morphology was identified as the principal factor affecting the interaction of slag on carbonaceous particles. The smooth surface of bio-char results in reduced slag foaming. This finding forms the basis for future research on the production of bio-char to be used as a slag foaming agent in EAF steelmaking.

USE OF CARBON MATERIAL WITH DEVELOPED SURFACE FOR SYNTHESIS OF HIGHER CHROMIUM CARBIDE

The paper presents experimental data on synthesis of finely dispersed powder of chromium carbide Cr3C2 . Chromium carbide was prepared by reduction of chromium oxide Cr2O3with nanofibrous carbon (NFC) in induction furnace in argon atmosphere. NFC is a product of catalytic decomposition of light hydrocarbons. The main characteristic of NFC is high specific surface area (~150,000 m2/kg), which is significantly higher than that of carbon black (~50,000 m2/kg). Content of impurities in NFC is at the level of 1 wt %. Based on analysis of state diagram of Cr – C system, composition of charge and the upper temperature limit of carbide formation reaction for obtaining chromium carbide in powder state are determined. Based on thermodynamic analysis, temperature of the onset of carbothermic reduction reaction of chromium oxide Cr2O3was determined at various CO pressures. Characteristics of chromium carbide were studied using X-ray diffraction analysis, pycnometric analysis, scanning electron microscopy using local energy dispersive X-ray microanalysis (EDX), lowtemperature nitrogen adsorption followed by determination of specific surface area by means of BET method, sedimentation analysis, synchronous thermogravimetry and differential scanning calorimetry (TG/DSC). The material obtained at optimal parameters is represented by a single phase – chromium carbide Cr3C2 . Powder particles were predominantly aggregated. Average size of particles and aggregates equaled 6.5 μm within a wide range of size distribution. Specific surface value of the obtained samples was 2200 m2/kg. Oxidation of chromium carbide began at temperature of ~640 °C and practically ends at ~1000 °C. Optimum parameters of synthesis are provided by ratio of reagents according to carbide of Cr3C2composition stoichiometry at temperature of 1300 °С and holding time of 20 minutes. It is shown that for this process nanofibrous carbon is an effective reducing agent and that chromium oxide Cr2O3is almost completely reduced to carbide Cr3C2 .

Recovery of sulphur and calcium carbonate from waste gypsum

Gypsum is produced as a waste product by various industries, e.g. the fertiliser industry, the mining industry and power stations. Gypsum waste disposal sites are responsible for the leaching of saline water into surface and underground water. The aim of this investigation was to evaluate a process for converting waste gypsum into sulphur and calcium carbonate. The process evaluated consisted of the following stages: reduction of gypsum to calcium sulphide; H2S-stripping and sulphur production. Thermal reduction showed that gypsum could be reduced to CaS with activated carbon in a tube furnace operating at 1 100 oC. The CaS yield was 96%. The CaS formed was suspended in water to form a CaS slurry. The reaction of gaseous CO2 with the CaS slurry leads to the stripping off of H2S gas and the precipitation of CaCO3. During batch studies sulphide was stripped from 44 000 mg/l to less than 60 mg/l (as S). The H2S generated in the previous step was then reacted in the PIPco process to form elemental sulphur.

The influence of oxidized technical carbon N121 on the properties of butyl-based rubbers

The subject of the study were samples of channel technical carbon K354, furnace technical carbon N121 and experimental – based on TUN121, oxidized with active forms of oxygen. Samples of carbon black were studied in the composition of a rubber mixture based on BK 1675N butyl rubber. The purpose of this study was to determine the possibility of using oxidized technical carbon N121 in fillers of rubber based on butyl rubber, instead of carbon black K354. The physicochemical properties of the samples of technical carbon under study, the results of physical and mechanical tests, and the gas permeability tests of rubber mixtures filled with the samples under study are presented. A conclusion is made about the possibility of replacing channel technical carbon K354 with furnace black carbon N121 oxidized with 30% hydrogen peroxide.

Mechanical Properties of Silicon Carbon Black Filled Natural Rubber Elastomer

A pyrolyzed ash containing about 50% carbon, named silicon carbon black(SiCB), was prepared by the anoxic pyrolysis of rice husk. Fourier transform infrared spectroscopy(FTIR), thermogravimetric analysis(TGA), Brunauer-Emmett-Teller(BET), transmission electron microscopy(TEM) and universal material testing machine were used to analyze the stress-strain relationship, Mullins effect and static viscoelastic properties of SiCB-filled vulcanized natural rubber(NR), and SiCB was compared with a commercially available semi-reinforcing furnace(SRF) carbon black. The results show that the vulcanized natural rubber filled with SiCB had similar reinforcing properties to those of that filled with traditional SRF, but obvious differences between them exist in stress -strain properties and stress softening resistance. We tried to discuss the related phenomena with the aid of the modified two-layer theory. And it is successfully predicted and verified that SiCB has good compression resistance and obvious stress relaxation advantages in compression stress relaxation.

Study on the characteristics of grout material using ground granulated blast furnace slag and carbon fiber

This study aims to evaluate the applicability of a grout material that is mixed with carbon fiber, biogrout, ground granulated blast furnace slag (GGBS) powder and cement. Uniaxial compressive strength tests were performed on homo-gel samples at days of 1, 3, 7, 14 and 28. In addition, the variation of permeability with the mixing ratios was measured. Based on the uniaxial compressive strength test, it was confirmed that the uniaxial compressive strength increased by 1.2times when carbon fiber increased by 1%. In addition, as a result of the permeability test, it was found that when the GGBS increased by 20%, the permeability coefficient decreased by about 1.5times. Therefore, the developed grout material can be used as a cutoff grouting material in the field due to its strength and cut-off effect.

Effects of Basicity and Mesh on Cr Leaching of EAF Carbon Steel Slag

The slag’s chromium leaching is one of the most pressing concerns in Electric Arc Furnace (EAF) carbon and stainless steels production. In recent years, many studies have aimed at understanding which properties (basicity, cooling speed) and phases (spinels, wustite, silicates) determine the Cr leaching, defining different indices (sp-factor, cs-factor) in order to forecast the slag’s behavior compared to the leaching of this toxic metal. The literature suggests that spinel formation is usually a good way to fix Cr and prevent its leaching. However, in some conditions (high basicity, low amount of spinel-forming species) soluble Cr-bearing phases can be formed, i.e., Ca-chromite or unstable spinel. In these conditions, Cr can be leached easily, even if it is bound in a spinel structure. In this paper, the effects of basicity and impurities (Ca, Si) on the instability of Cr-spinel was investigated, with respect to slag mesh. The influence of basicity was also studied on Mg-wustite stability, which might contribute to the leaching of Cr. Different samples of carbon steel slag, suspected of forming unstable spinels, belonging to different steel grade production, were also investigated. Both granulated (4 mm) and milled (<100 μm) slag were analyzed. Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) analyses were carried out to measure the local chemical composition of Cr-bearing phases. This data was correlated with slag basicity (by X-Ray Fluorescence: XRF), spinel fraction (by X-Ray Diffraction: XRD), and Cr leaching (by Inductively Coupled Plasma Mass Spectrometry: ICP-MS). The main results indicate that the increase of the slag basicity implies an increase of the impurity content (Ca, Si) in the spinel, also over-saturated by Cr. This aspect, coupled with spinel geometrical features, seems to justify the unexpected Cr leaching of some slag samples. Basicity does not influence the chemistry of wustite, thus excluding it as an additional Cr leaching source.

Removal of heavy metal ions using polystyrene nanocomposite thin films

Polymer nanocomposite thin films consisting of polystyrene and furnace carbon black were prepared in this study as adsorbent materials for the removal of heavy metals from industrial wastewater. The film properties were characterized, and the effect of carbon content in the nanocomposite, initial concentration, separation time, and pH on the removal efficiency were investigated. The optimal operating conditions were 120 min of separation time at pH 6 with a carbon content of 15 wt%. The adsorption equilibrium data and adsorption kinetics are also described herein. The Freundlich model best fit the equilibrium data, and the adsorption rate followed pseudo second-order kinetics.

Optical characteristics of butyl rubber loaded with general purpose furnace (GPF) carbon black

Optical characteristics of butyl rubber/GPF carbon black (BR/GPFCB) composites with carbon black (CB) concentrations 40, 60, 80 and 100 phr (part per hundred part of rubber) were investigated. The structure of the BR/GPFCB composites was analyzed by x-ray diffraction (XRD). All samples with various CB showed diffraction peaks around 2θ = 14°, 25° and 44° which correspond to interlayer spacing of 6.23 Å, 3.62 Å and 2.10 Å respectively. The peaks were shifted toward larger 2θ angles with increasing CB concentration, indicating a decrease in layer spacing. Ultraviolet and visible (UV–vis) absorbance spectra in the range from 200 nm to 800 nm of the BR/GPFCB composites were studied. In the UV range of the spectra, an absorption edge was recorded. Direct and indirect optical band gaps for the composites were evaluated. The direct band gap values were found-as shown to be slightly greater than that of the indirect ones. The reflectance spectra in the UV optical range were demonstrated. Most of the incident UV light was absorbed inside the composites while a very small fraction was reflected and transmitted. This was attributed to the high UV absorption property of the CB filler. The refractive index of the composite was calculated from the reflectance data. The dependence of the real and imaginary parts of the complex dielectric constant on the incident light energy was characterized. The dielectric loss factor was found to decrease with increasing incident photon energy until approximately 5.5 eV (around the absorption edge) and then it increased rapidly.

Optical and dielectric dispersion parameters of general purpose furnace (GPF) carbon black reinforced butyl rubber

Optical and dielectric dispersion parameters for butyl rubber–general purpose furnace carbon black (IIR-GPF CB) composites with various carbon black (CB) concentrations were determined using ultraviolet transmittance spectra. X-ray diffraction (XRD) for the composite samples was measured in the 2θ range from 5° to 50°. There was a slight increase in the XRD peak intensity by increasing CB content indicating some significant changes in the composite structure. Some structural parameters were calculated for the XRD fundamental peak. The crystallite size increased significantly with the increase in carbon black concentration. This suggested a tendency of the polymer toward a more crystal state. Analysis of refractive index dispersion was carried out using Wemple–DiDomenico single effective oscillator model. The energy of effective single oscillator ( $$E_{\text{o}}$$ ) and the dispersion energy ( $$E_{\text{d}}$$ ) were estimated for the composites of different CB loadings. Accordingly, the moments of optical spectra, static and high-frequency dielectric constants were calculated. The variation of the real part $$\varepsilon_{1}$$ and imaginary part $$\varepsilon_{2}$$ of the complex dielectric function with the incident photon wavelength was investigated. The recorded values of $$\varepsilon_{1}$$ were greater than the values of $$\varepsilon_{2}$$ . The dielectric energy loss was specified by means of three important parameters: volume energy loss function, surface energy loss function and dielectric loss factor ( $$\tan \delta$$ ). The dielectric relaxation time $$\tau$$ and plasma frequency were studied as a function of incident photon wavelength for different composite samples. There was a great dependence of $$\tau$$ on the wavelength and amount of the carbon black in the composite.

SYNTHESIS OF FINELY DISPERSED VANADIUM CARBIDE (VC<sub>0.88</sub>) USING NANOFIBROUS CARBON

The paper presents the experimental data on the synthesis of finely dispersed powder of vanadium carbide (VC 0.88 ). Vanadium carbide was prepared by the reduction of vanadium oxide (III) with nanofibrous carbon (NFC) in the induction furnace under an argon atmosphere. NFC is a product of catalytic decomposition of light hydrocarbons. The main characteristic of a NFC is a high specific surface area (~150 000 m 2 /kg), which is significantly higher than that of soot (~50 000 m 2 /kg). The content of impurities in the NFC is at the level of 1 % wt. Based on the analysis of the state diagram of the V – C system, the composition of the charge and the upper temperature limit of the carbide formation reaction for obtaining vanadium carbide in the powder state are determined. Based on the thermodynamic analysis, the temperature of the onset of the carbothermic reduction reaction of vanadium oxide (III) at various CO pressures was determined. The characteristics of vanadium carbide were studied using X-ray and elemental analyzes, pycnometric analysis, scanning electron microscopy using local energy dispersive X-ray microanalysis (EDX), low-temperature adsorption of nitrogen, followed by determination of the BET specific surface area, sedimentation analysis, synchronous thermogravimetry and differential scanning calorimetry (TG/DSC). The material obtained at optimal parameters is represented by a single phase – vanadium carbide VC 0.88 . The powder particles were predominantly aggregated. The average size of the particles and the aggregates equaled 9.2 – 9.4 μm within a wide range of size distribution. The specific surface value of the obtained samples was 1800 – 2400 m 2 /g. Oxidation of vanadium carbide began from the temperature of ~430 °C and practically ends at ~830 °C. Optimum parameters of synthesis are the ratio of reagents according to stoichiometry to obtain carbide of composition VC 0.88 at a temperature of 1500 – 1600 °С and a holding time of 20 minutes. It is shown that for this process nanofibrous carbon is an effective reducing agent and that vanadium oxide (III) is almost completely reduced to carbide VC 0.88