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The paper shows the results of a study of the influence of the cut-off method of the slag by using destructible plugs on the quantitative indicators of the redistribution of slag and metal in the steel ladle during the metal tapping operation from the converter. The laboratory setup simulates a real 160-ton industrial top-blown oxygen converter, and a steel ladle at a scale of 1:18 has been used to fulfill the study. Water was chosen as a liquid steel imitator, and machine oil was chosen for slag with parameters that ensure the similarity of physical parameters in the metal-slag system. The physical modelling of the tapping process of a two-phase converter bath in the case of a destructible plug in the tap hole compared to the tapping option without it showed a significant positive effect of the presence of the plug in the initial period from the moment the converter is tilted.

The influence of different carbon sources, including anthracite, calcined petroleum coke, three samples of high-temperature coke, biochar, and a mixture of 50 wt.% biochar and 50 wt.% coke, on slag foaming behavior was studied. The slag’s composition was set to FeO-CaO-Al2O3-MgO-SiO2, and the temperature for slag foaming was 1600 °C. The effect of the carbon sources was evaluated using foaming characteristics (foam height, foam volume, relative foaming height, and gas fraction), X-ray diffraction (XRD), chemical analysis of the slag foams, Mossbauer spectroscopy, observation by scanning electron microscope (SEM), and energy-dispersive spectroscopy (EDS) mapping. Different foaming phenomena were found among conventional sources, biochar as a single source, and the mixture of coke and biochar. Biochar showed the most inferior foaming characteristics compared to the other studied carbon sources. Nevertheless, the slag foaming process was improved and showed slag foaming characteristics similar to results obtained using conventional carbon sources when the mixture of 50 wt.% coke and 50 wt.% biochar was used. The XRD analysis revealed a difference between the top and bottom of the slag foams. In almost all cases, a maghemite crystalline phase was detected at the top of the slag foams, indicating oxidation; metallic iron was found at the bottom. Furthermore, a difference in the slag foam (mixture of coke and biochar) was found in the presence of such crystalline phases as magnesium iron oxide (Fe2MgO4) and magnetite (Mg0.4Fe2.96O4). Notwithstanding the carbon source applied, a layer between the foam slag and the crucible wall was found in many samples. Based on the SEM/EDS and XRD results, it was assumed this layer consists of gehlenite (Ca2(Al(AlSi)O7) and two spinels: magnesium aluminate (MgAl2O4) and magnesium iron oxide (Fe2MgO4).

Purpose. The research purpose is to substantiate the use of biocoke as a fuel in the iron ore sintering, as well as its influence on the performance and properties of the resulting sinter. To completely replace conventional coke breeze, biocoke is produced using 5 wt.% biomass wood pellets at different carbonization temperatures of 950 or 1100°C. Further, the influence of biocoke on the sintering process and the sinter quality is studied at a high proportion of biomass pellets of 10, 15, 30, 45 wt.% and a carbonization temperature of 950°C. Methods. Carbonization is performed in shaft-type electric furnaces to produce laboratory coke or biocoke. Afterward, the sintering of iron ores is conducted on a sinter plant. To assess the sintering process and the quality of the resulting sinter, the filtration rate is determined on a laboratory sinter plant using a vane anemometer designed to measure the directional flow average velocity under industrial conditions. The sinter reducibility is studied using a vertical heating furnace to assess the effect of coke and biocoke on the sinter’s physical-chemical properties. Findings. It has been determined that biocoke, carbonized at a temperature of 950°C, has good prospects and potential for a shift to a sustainable process of iron ore sintering. Originality. It has been proven that biocoke with a biomass pellet ratio of up to 15 wt.%, obtained at a temperature of 950°C, does not affect the parameters characterizing the sintering process. The sinter strength indicators correspond to the use of 100 wt.% conventional coke breeze. Biocoke used with a high proportion of biomass pellets of 30 and 45 wt.% causes a deterioration in the sinter quality. Practical implications. The results of using biocoke with the addition of 5-15 wt.% biomass pellets and at a temperature of 950°C are within the standard deviation, which makes it possible to use biocoke with 15 wt.% biomass pellets instead of industrial coke breeze.

Steel production is the most dynamic industry and one of the key sectors for the development of the global economy. The growing production of iron ore increases the need for its beneficiation and granulating for subsequent use in the production of iron and steel. As a result, the number of CO2 emissions and harmful substances increases, which negatively affects both society and the environment. It is important to study the use of biomass for the production of iron ore pellets. Lignocellulosic biomass is a renewable and sustainable source of heat and energy that can mitigate climate change. The efficiency of using sunflower husks on the combined machine “straight grate - rotary kiln - annular cooler” to partially replace natural gas in the production of iron ore pellets has been studied. The influences of alternative fuel use on technological indicators of the process and quality of iron ore pellets have been analyzed. It was found that the combustion of sunflower husks generates enough heat to obtain iron ore pellets with good strength. The main indicators of the quality of iron ore pellets remain at the same level as the iron ore pellet quality when using natural gas.

The use of biomass as fuel might solve several technological and environmental issues and overcome certain challenges of sinter production. In particular, as revealed by comprehensive analyses, biomass can be used as fuel for iron ore sintering. In this study, we investigate the use of some raw and pyrolysis-processed biomass pellet types, namely wood, sunflower husks (SFH), and straw, for iron ore sintering. In the experiments, the pyrolysis temperature was set to 673, 873, 1073, and 1273 K, and the proportion of biomass in the fuel composition was set to 25%. It was established that the addition of biofuels to the sintering blend leads to an increase in the gas permeability of the sintered layer. The analysis of the complex characteristics of the sintering process and the sinter strength showed the high potential of wood and sunflower husk pellets pyrolyzed at 1073 and 873 K, respectively, for iron ore sintering. The analysis of the macrostructure of the sinter samples obtained using biomaterials revealed that with higher pyrolysis temperatures; the materials tend to have greater sizes and higher amounts of pores and cracks. The composition analyses of the resultant sinters revealed that with higher temperature, the FeO content of the sinters tends to increase.

Iron ore sintering is a predominant process for fine iron ore and its concentrate to be applied in the blast furnace process. However, sintering produces a negative impact on the environment. One of the effective ways to reduce greenhouse gas emissions from iron ore sintering is to use CO2-neutral biomaterials for the fuel needs of this technology. Walnut shells (WNS) are a promising raw material for such fuel substitute. Herein, the effect of the raw and the pyrolyzed WNS with a constant fineness of 3-0 mm on the sintering process and the sinter properties were studied. The proportion of WNS in the fuel composition was set to 25 wt.%. It has been established that the use of WNS pyrolyzed up to 873 K is optimal. Additionally, the difference in the reactivity of WNS and coke breeze has provoked the studies on the influence of the pyrolyzed WNS size on the sintering process. WNS size was set to 1-0, 3-0, 5-0, and 7-0 mm. It has been found that the most optimal both for the iron ore sintering process and the sinter quality is the use of WNS with a particle size of 3-0 mm, subjected to preliminary pyrolysis up to 873 K.

Dominating globally and within Ukraine, the blast-furnace practice for iron production requires iron ore sintering preparation wherein the significant amount of fossil fuel is consumed, accompanied by harmful emissions into the environment. Pursuing the purpose to mitigate this negative impact, we address the promising direction of biomass utilisation for a partial replacement of fossil fuels in iron ore sintering. This paper considers the benefits of fossil fuels substitution with biomass, the world practice of biomass utilisation in iron ore sintering and the scope of the biomass energy potential in Ukraine. The study for obtaining sinters with the use of raw biomass fuels (sunflower husk, walnut shell) and charcoal has been carried out via lab-scale sintering pot. The influence of various biomaterials types on the process of iron ore sintering have been investigated and the obtained sinter quality in comparison with the conventional types of the fuels allows establishing the feasibility of replacing 25 % of coke breeze by charcoal or by walnut shell. The sunflower husk application is possible if preliminary preparation of the material for increasing bulk density is assumed to be carried out, for instance, by pressing.

An increase in steel production causes an increase in the use of carbon fuels and reducing agents, which in turn leads to greenhouse gas emissions. It is possible to reduce the environmental impact...

A large amount of finely dispersed manganese ore left after benefication operations or blown out from the furnaces is unsuitable for direct use in electric furnaces and blast furnaces, therefore it is necessary to granulate it in order to have the efficient use of its fine ore particles in metallurgy. To make our research more of practical use, we found it is reasonable not only work over manganese fines sintering but also to attempt mitigating the negative effect on the environment produced by the further sintering and apply the biofuel within the total fuel mass. Under laboratory conditions, the studies have been carried out with the objective to obtain manganese sinter, in which wood biomass is applied, namely initial and pre-pyrolyzed, at temperatures of 673, 873, 1073 and 1273 K. The amount of biofuel in the sinter blend was 25 wt.%. It has been established that the biomass use causes the decrease in the specific capacity of the sintering plant. However, for the efficient manganese ores sintering process, the biofuel of high pyrolysis temperature of 1273 K is required. To achieve the specific capacity and the yield to be as high as those when coke breeze is only used, the amount of the biofuel for manganese ore sintering should be less than 25 wt.% of the solid fuel. Additionally, it has been revealed that the further increase in the biofuel ratio in the total fuel amount is possible on condition that its reactivity is decreased, or larger particles of the biofuel are used.

The paper presents a method for obtaining electrochemically active ultrafine composites of iron oxides, superparamagnetic ‘core/shell’ γ-Fe2O3/defective α-Fe2O3, which involved modifying sol-gel citrate synthesis, hydrothermal treatment of the formed sol, and subsequent annealing of materials in the air. The synthesized materials’ phase composition, magnetic microstructure, and structural, morphological characteristics have been determined via X-ray analysis, Mossbauer spectroscopy, scanning electron microscopy (SEM), and adsorption porometry. The mechanisms of phase stability were analyzed, and the model was suggested as FeOOH → γ-Fe2O3 → α-Fe2O3. It was found that the presence of chelating agents in hydrothermal synthesis encapsulated the nucleus of the new phase in the reactor and interfered with the direct processes of recrystallization of the structure with the subsequent formation of the α-Fe2O3 crystalline phase. Additionally, the conductive properties of the synthesized materials were determined by impedance spectroscopy. The electrochemical activity of the synthesized materials was evaluated by the method of cyclic voltammetry using a three-electrode cell in a 3.5 M aqueous solution of KOH. For the ultrafine superparamagnetic ‘core/shell’ γ-Fe2O3/defective α-Fe2O composite with defective hematite structure and the presence of ultra-dispersed maghemite with particles in the superparamagnetic state was fixed increased electrochemical activity, and specific discharge capacity of the material is 177 F/g with a Coulomb efficiency of 85%. The prototypes of hybrid supercapacitor with work electrodes based on ultrafine composites superparamagnetic ‘core/shell’ γ-Fe2O3/defective α-Fe2O3 have a specific discharge capacity of 124 F/g with a Coulomb efficiency of 93% for current 10 mA.

Adding 5 mass% wood pellets in a coal blend affects the reactivity with CO2 and microstructural properties of the coke at different final coking temperatures of 950 and 1100 °C. A correlation between coke reactivity index (CRI) and BET specific surface area was found. The reactivity of coke and biocoke decreases with a decrease in the specific surface area, as well as with an increase in the carbonization temperature. Raman spectroscopy results indicate that the higher carbonization temperature of biocoke mitigates the effect of 5 mass% of biomass addition. The X-ray diffraction-based interlayer spacing of carbon crystallite (d002) decreases slightly with increasing carbonization temperature, and crystallite height (Lc) increases with rising coking temperature for both coke and biocoke. Additionally, the lower the d002 value, the lower the CRI of the cokes and biocokes. A good correlation between CRI and d002 is observed. Carbon crystallite width (La) values increased with a rising carbonization temperature, indicating the intensive growth of carbon crystallites in all directions. However, these values for biocokes are lower due to the presence of charcoal particles.

A promising direction of technical hydrolysis lignin utilization is metallurgical production, primarily iron ore preparation and blast furnace process. A significant potential is concentrated in the sintering process. In order to improve properties of lignin in the role of a fuel, and to remove, with the possibility of trapping, toxic substances, it is necessary to carry out preliminary pyrolysis. The effect of technical hydrolysis lignin of different pyrolization degrees on the iron ore sintering process and properties of the obtained sinter is experimentally studied. Initial lignin was subjected to preliminary heat treatment to the final temperature of 400, 600, 800 and 1000 ºС without air access. Sintering with the participation of pyrolyzed lignin has been carried out via lab-scale sinter pot. After sintering, the sinter strength and the macrostructure have been determined. The chemical composition of the sinter samples has been revealed by X-ray fluorescence analysis. As a result of the experiments, the possibility of replacing 25 % of coke breeze with lignin prepyrolyzed at 800 ºС has been determined. Under these conditions, the main indicators of the sintering process, such as vertical sintering rate, product yield and specific capacity of the lab-scale sinter pot, remain virtually unchanged. There is a slight decrease in the impact strengths and the abrasion strengths of the sinter. However, these figures remain at a technologically acceptable level. It should be noted that when using lignin as a sintering fuel, there is a tendency for some decrease in the iron content of the sinter produced with it. The study of the sinter macrostructure has shown an increase in the pore diameter when the partial replacement of coke breeze with lignin while with the increasing lignin pyrolysis temperature the pore volume increases. The studies has evidence the possibility of solving the urgent environmental issues of technical hydrolysis lignin utilization by applying it in the sintering process with preliminary pyrolization. A promising direction for further research is the development of methods for the preparation of technical hydrolysis lignin for the use in iron ore sintering

Plasma method is used to synthesize manganese ferrite. The basic properties of ferrite are determined by IR spectroscopy, UV spectroscopy, X-ray phase analysis, vibration magnetometry. The paper shows that the use of magnetically controlled sorbent allows to purify waste waters from chromium (III). The process of adsorption of chromium cations (III) is investigated. The kinetics of the process is studied. To describe the equilibrium isotherms, the experimental data are analysed by the models of Langmuir, Freundlich isotherms. Pseudo-first order, pseudo-second-order, and Weber-Morris are used to elucidate the kinetic parameters and mechanism of the adsorption process. It has been established that the removal of Cr (III) cations is described by the pseudo-second order of the Langmuir reaction and mechanism.

The publication considers the possibility to use the original corn stalks and corn stalks after pyrolysis as raw materials for carbon nanomaterials manufacture. The changes in the properties of corn stalks during pyrolysis have been studied at different temperatures and their influence on the corn stalks properties have been revealed with the use of the ultimate and the X-ray fluorescence analyses. The results of the research are obtained in the form of carbon nanoparticles produced from the above-mentioned stock and pyrolysed corn stalks.