Converter Slag Research Articles

Metallurgical Waste for Sustainable Agriculture: Converter Slag and Blast-Furnace Sludge Increase Oat Yield in Acidic Soils

The study is the first to examine the combined use of blast-furnace sludge as a source of microelements and converter slag as a soil-deoxidizing agent in oat (Avena sativa L.) cultivation in sod-podzolic soils. It has been established that blast-furnace sludge is a highly dispersed waste, which contains about 50% iron, 7% zinc, and a small amount of calcium, silicon, magnesium, aluminum, and sulfur. Hazardous components such as lead, arsenic, etc., are not detected. Converter slag comprises porous granules up to 3 mm in size, consisting mainly of calcium compounds (CaO, Ca(CO)3, CaSiO3, CaFe2O4) and a small amount of Mn, Al, and Mg trace elements. In a laboratory experiment, blast-furnace sludge increased the germination of oats by 5–10%, regardless of the addition of a deoxidizer (slag), but at the same time suppressed the growth of stem length by a maximum of 18% at 1 g∙kg−1. The addition of slag raised substrate pH and increased the index by 8% at a sludge concentration of 0.1 g∙kg−1. Root length in deoxidizer-free variants increased by 50–60% and with the addition of slag by 27–47%. Root dry mass also increased under the addition of sludge by 85–98%; however, the addition of slag reduced the indicator to the control level. In a field experiment with the combined application of waste, an increase in yield by more than 30% was shown. When soil was treated with slag and sludge, the height of plants increased by an average of 18%. It should be noted that the introduction of waste did not affect the quality of the grain. The use of slag increased the lead content in the soil, which is probably due to the sorption properties of calcium compounds in the slag, since lead was not found in the analyzed waste. Presumably, lead is sorbed by slag from the lower soil horizons, concentrating and immobilizing it in the upper layer. This version is supported by the absence of lead accumulation in straw and oat grain. The zinc-containing sludge increased the content of this element by 33% in the soil, as well as by 6% in straw and by 14% in grain. Thus, we found that the studied metallurgical wastes can be used as nutrients for agriculture, both individually and jointly. Overall, the proposed approach will contribute both to reducing the amount of accumulated waste and to improving the efficiency and sustainability of agricultural production and CO2 sequestration. However, the features of the accumulation of heavy metals in soil and plants under the influence of the analyzed types of waste require more in-depth study, including within the framework of long-term field experiments.

Structural Changes in Copper Slags During Slow Cooling

The objects of the study were converter slags from the Balkhash copper plant in their initial state and after heat treatment. Using mineralogical and X-ray phase analysis, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA), it was found that the initial converter slag and its thermally treated samples have identical matrices with almost complete coincidence in mineral and phase compositions. The distinguishing feature is the quantitative ratio of mineral components in the slag mass. Almost all of the iron is oxidized and present in the form of fayalite, magnetite, and magnetite, with other elements (silicon, copper, zinc, and aluminum) incorporated into its lattice. The structure of all slag samples indicates an association of sulfur exclusively with copper. Copper in the slags was identified in both metallic and sulfide forms. Slow cooling of the converter slag after its remelting contributes to the reduction in the sulfide–metal suspension in the volume of the melt and its coarsening. During slow cooling, structural changes occur not only in the main oxide part of the slag but also in the polymetallic globules.

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

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

Promotion of germination, rooting, and seedling emergence of rice (Oryza sativa L.) by soaking seeds in converter slag suspension before sowing

ABSTRACT Seed soaking is an important process in rice cultivation. Allowing seeds to absorb sufficient water before sowing improves their germinability, germination vigor, and seedling emergence. The use of converter slag, which is a fertilizer and soil amendment, can increase crop yields and suppress diseases. However, there are no reports on the effect of the converter slag on initial rice plant growth when applied at the seed soaking stage. In this study, we investigated the effects of soaking rice seeds in two types of converter slag suspensions on the early growth of rice plants from germination to seedling emergence. We conducted laboratory tests with simulated cultivation processes (germination forcing and root-elongation forcing). The seeds soaked in converter slag suspensions showed improved germinability and coleoptile elongation under anaerobic conditions, as well as improved rooting ability and seminal root elongation under aerobic conditions. Seeds soaked in converter slag suspensions and water were sown using five sowing methods (standard seedling raising; Japanese-type direct sowing at surface, shallow, and deep soil depths; and Italian-type direct sowing). Overall, the seedlings that grew from seeds treated with the converter slag suspensions showed faster seedling emergence and better growth. These results show that soaking seeds in Ca2+-rich converter slag suspensions can promote the early growth of rice plants by avoiding low-oxygen disorders and improve subsequent seedling establishment. Thus, converter slag suspensions are suitable for germination but unsuitable for microbial growth due to high alkaline conditions (pH 11–11.5), which may omit both water changes and germination forcing process.

Carryover slag weight prediction under converter tapping process by applying attention-shifting infrared thermal mapping technique

The prediction model of actual slag weight under converter tapping process was constructed by applying attention-shifting infrared thermal mapping technique. Firstly, the linkage between programmable logic controller signal of the converter mechanical structure and the infrared thermal mapping detector image was realized to ensure the real-time monitoring of the whole tapping process. Images should be preprocessed to ensure a good distinction between the flowing liquid and background at the tapping beginning, furthermore to separated slag from liquid steel at the following process. Moreover, the use of attention-shifting block belonging to the infrared thermal detector was effect to obtain more accurate image distinction between the liquid steel and slag. Hence the gray degree threshold value was adjusted to 220–225 in the early stage, and the value was needed to be lowered to 170–176 in the end. After using the model, the slag weight was less than < 8.0kg/t when only slag-stopping awl was adopted in tapping process. The average weight of slag in converter was 7.3kg/t by using slag-stopping awl and sliding plate slag-blocking.

The Application of Converter Sludge and Slag to Produce Ecological Cement Mortars.

The paper presents an analysis of the effective use of a mixture of steel sludge (S1) and slag (S2) from the converter process of steel production for the production of cement mortars. Metallurgical waste used in the research, which is currently deposited in waste landfills and heaps near plants, posing a threat to groundwater (possibility of leaching metal ions present in the waste), was used as a substitute for natural sand in the range of 0-20% by weight of cement (each). The obtained test results and their numerical analysis made it possible to determine the conditions for replacing part of the sand in cement mortars with a mixture of sludge and slag from a basic oxygen furnace (BOF) and to determine the effects of such modification. For the numerical analysis, a full quadratic Response Surface Model (RSM) was utilized for two controlled factors. This model was subsequently optimized through backward stepwise regression, ensuring the inclusion of only statistically significant components and verifying the consistency of residual distribution with the normal distribution (tested via Ryan-Joiner's test, p > 0.1). The designated material models are helpful in designing ecological cement mortars using difficult-to-recycle waste (i.e., sludge and converter slag), which is important for a circular economy. Mortars modified with a mixture of metallurgical waste (up to 20% each) are characterized by a slightly lower consistency, compressive and flexural strength, and water absorption. However, they show a lower decrease in mechanical strength after the freezing-thawing process (frost resistance) compared to control mortars. Mortars modified with metallurgical waste do not have a negative impact on the environment in terms of leaching heavy metal ions. The use of a mixture of sludge and steel slag in the amount of 40% (slag/sludge in a 20/20 ratio) allows you to save 200 kg of sand when producing 1 m3 of cement mortar (cost reduction by approx. EUR 5.1/Mg) and will also reduce the costs of the environmental fee for depositing waste.

Preparation of cementing material and recovery of iron resources using converter slag

This study aims to optimize the modification of blast furnace slag and converter slag using dust removal ash as a reducing agent, with the dual goals of enriching cementitious materials and recovering iron resources. The results show that the pulverization effect of the modified slag is optimized when the dust removal ash addition ratio is 14 wt%, the reduction temperature is 1450 °C, and the reduction time is 30 min. Under these conditions, the pulverization and iron recovery rates reached 65.23 % and 60.85 %, respectively. The composition of the reduction-modified product is influenced by the particle size of the reduction product, which in turn affects its phase composition. The main phases of small particles (particle size < 0.150 mm) identified were magnesium rose pyroxene (Ca3Mg(SiO4)2, C3MS2) and dicalcium silicate (γ-Ca2SiO4, γ-C2S). The main phases of large particles (particle size > 0.150 mm) identified were dicalcium silicate (β-Ca2SiO4, β-C2S) and Ca2Fe2O5. Iron primarily exists in the form of an alloy and cementite, while P is dispersed in the iron beads in the form of Fe3P, Fe2P, and Mn2P in a striped configuration.

Insight into the TiO2 on transport behavior and heat transfer of the CaO–SiO2–FeO–MgO system at different basicities: Molecular dynamics simulation and thermodynamics

In order to promote the resource utilization of Ti-containing converter slag and reduce the loss of metallic Ti, it is necessary to clarify the relationship between the oxygen network structure and thermophysical properties of the slag. The present work uses classical molecular dynamics (CMD) simulation to study the effects of basicity (1.0–3.0) and TiO2 content (0%–10 %) on the local structural properties, viscosity, and thermal conductivity of the CaO–SiO2–FeO–MgO–TiO2 (CSFMT) system at 1873 K. The M − O (M = Ca, Si, Fe, Mg, and Ti) bond length calculated based on CMD is consistent with the experimental results, and the [SiO4] tetrahedron and [TiO6] octahedron are the basic structural units of the CSFMT system. The increase in basicity promotes the break of bridging oxygen (BO) Si–O–Si and the formation of non-bridging oxygen Si–O-M. The increase in TiO2 content promotes the formation of Ti–O–Si in the system. The basicity and TiO2 content affect the thermophysical properties of the CSFMT system by promoting and inhibiting the depolymerization of the oxygen network structure, respectively. The diffusion abilities of different atoms in the CSFMT system are in descending order of Fe > Mg > Ca > O > Si > Ti. The viscosity of the CSFMT system decreases with increasing basicity and increases with increasing TiO2 content. Increasing the proportion of BOs can weaken the anharmonicity in the polyhedral structural units and reduce phonon scattering. With increasing basicity and TiO2 content, the effective phonon mean free path decreases and increases, respectively, resulting in a decrease and an increase in the thermal conductivity of the CSFMT system. The changes in the microstructure properties of the CSFMT system can be reasonably explained by the changes in its thermodynamic properties such as enthalpy. It is worth noting that the basicity has a greater effect on the viscosity, while the TiO2 content has a more significant impact on the thermal conductivity of the CSFMT system.

Comprehensive Utilization and Control Measures of Iron and Steel Slag

With the increase of steel production, the amount of steel slag piled up is on the rise. The article analyzes the current situation of blast furnace slag utilization, elaborates on the current treatment technology of blast furnace slag, and points out that in the future, the utilization of blast furnace slag will develop towards the direction of developing high value-added products, and the sensible heat recovery rate of blast furnace slag is expected to increase. Analyze the current application status and treatment process of converter slag. The comprehensive treatment technology of converter slag is limited by multiple factors, and it is proposed to control converter slag from the production source through "slag recycling".

Mineralogy and environmental stability of metallurgical slags from the Euronickel smelter, Vozarci, North Macedonia

The laterite Ni-smelting operations at Vozarci, Republic North Macedonia have produced large amounts of smelting wastes dumped in the close vicinity of the smelter. We examined phase composition and chemistry of the various types of slags (electric furnace slags, converter slag, magnetic slag) with the special focus on the phases containing potentially toxic elements in terms of their mineralogy, chemical composition, and responses to weathering. Electric furnace slags contain between 35 and 47 wt.% SiO2, 21–40 wt.% Fe2O3, and 13–23 wt.% MgO; converter and magnetic slags are Fe-rich (76–77 wt.% of Fe2O3) with significant amounts of Ca (7.6–8.4 wt.% CaO) and S-portion (2–2.5 wt.% SO3). All slags contain substantial amounts of the potentially toxic elements: Co (20–87 ppm), Cr (9600–17400 ppm), Ni (170–730 ppm), and Zn (150–380 ppm). Further mineralogical analyses showed that the slags consist of silicate glass, synthetic equivalents of olivines, orthopyroxenes, clinopyroxenes, and subordinate spinel-group phases, sulfides, and intermetallic compounds. Some of the slags had been subject to weathering since their dumping in 1982. The weathering results in the release of metals from primary slag phases, particularly from glass, and the partial immobilization of these metals in secondary soluble and insoluble minerals in the slag heaps (hydroxy-iron oxides, gypsum, anhydrite, syngenite, aphthitalite). The majority of slag samples exhibited increased leaching under conditions of lower pH (2.9) compared to higher pH (4.9). The contrast between leaching treatments was particularly evident for nickel (Ni), with leaching at a low pH of 2.9 reaching up to 135 times higher (MS) than at pH 4.9. At lower pH conditions, other contaminants of interest were leached out at a rate 4 to 76 times faster compared to the leaching achieved at pH 4.9, because they are the major source of potentially toxic elements.

OPTIMIZING VANADIUM CONVERTER SLAG UTILIZATION: TARGETED ENRICHMENT AND STABILIZATION OF VANADIUM THROUGH NON-EQUILIBRIUM SOLIDIFICATION

The objective of this research was to optimize the comprehensive utilization of vanadium converter slag through targeted enrichment and stabilization of heavy metal vanadium. Employing the non-equilibrium solidification theory and FactSage software, we investigated the potential of modifying vanadium converter slag. When the original slag failed to generate vanadium-rich spinel with usable V elements, introducing modifying agents Fe and Al proved effective. Fe facilitated the enrichment of Cr within spinel, while Al significantly promoted the V enrichment. Expanding on this, we systematically examined the influence of Fe2O3, Al2O3 and MgO contents on spinel phase precipitation during vanadium slag solidification. The addition of Al resulted in the precipitation of corundum, hematite, spinel, olivine and diopside phases. With an increase in the Fe2O3 content, the precipitation of FeV2O4 and MgV2O4 initially increased, peaking at 9.67 % before subsequently decreasing. Maintaining the Fe2O3 content within a range of 25–30 % proved optimal for enhancing vanadium precipitation and enrichment. In contrast, variations in the Al2O3 content had minor impacts on SP-V phase precipitation, with slight effects on FeV2O4 reaching 10.34 %. Furthermore, the incorporation of MgO facilitated the precipitation of MgV2O4 while concurrently suppressing the FeV2O4 precipitation. By judiciously controlling the MgO content at approximately 20 %, vanadium enrichment in the form of FeV2O4 and MgV2O4 spinel phases reached a remarkable 94.46 %.

Methacrylic acid in situ modified steel converter slag/natural rubber composites: Resourceful utilization of steelmaking solid wastes

As a by-product of the steelmaking industry, the large-volume production and accumulation of steel converter slag cause environmental issues such as land occupation and dust pollution. Since metal salts of unsaturated carboxylic acid can be used to reinforce rubber, this study explores the innovative application of in-situ modified steel slag, mainly comprising metal oxides, with methacrylic acid (MAA) as a rubber filler partially replacing carbon black. By etching the surface of steel slag particles with MAA, their surface roughness was increased, and the chemical bonding of metal methacrylate salt was introduced to enhance their interaction with the molecular chain of natural rubber (NR). The results showed that using the steel slag filler effectively shortened the vulcanization molding cycle of NR composites. The MAA in-situ modification effectively improved the interaction between steel slag and NR molecular chains. Meanwhile, the physical and mechanical properties, fatigue properties, and dynamic mechanical properties of the experimental group with MAA in-situ modified steel slag (MAA-in-situ-m-SS) were significantly enhanced compared with those of NR composites partially filled with unmodified slag. With the dosage of 7.5 phr or 10 phr, the above properties matched or even exceeded those of NR composites purely filled with carbon black. More importantly, partially replacing carbon black with modified steel slag reduced fossil fuel consumption and greenhouse gas emission from carbon black production. This study pioneered an effective path for the resourceful utilization of steel slag and the green development of the steelmaking and rubber industries.

On the issue of neutralizing carbon dioxide at processing coal in boilers of thermal power plants

The aim of the work is to predict 100% decarbonization of power plant's flue gases; to recover carbon from CO2 in in-situ mode; to extract valuable metals from ash; and to process ash and converter slag into stone casting. The novelty of the work is the development of a system for the integrated processing of coal in a smelter reactor by using high-temperature off gases in a boiler; carbon splitting according to the formula CO2 + 2Zn = 2ZnO + C, with the return of “C" to the system; sublimation of Zn from ZnO using a highly efficient counter-impacting jet method. Experiments carried out in a smelter have shown, the degree of reduction of germanium and zinc from slags ∼70%. The specific energy consumption is 2–3 times lower than in an acting analog. In a pessimistic scenario, the net profit of the system will be sufficient to purchase the missing electricity for the distillation unit: for the 60% carbonization of CO2, at the cost of electricity from wind turbines $46.3/MWh; in order to fully decarbonize CO2 - $31.8/MWh. The system's payback period will not exceed 6–8 years, with the expected net profit of $21,660,860/y.

Leaching behavior and microstructure of phosphorus in converter slag

Leaching behavior and microstructure of phosphorus in converter slag

Depletion of converter slags to waste in the Vanyukov furnace during pyrometallurgical copper production at JSC Almalyk MMC

The article shows the possibility of involving man-made formations in the pyrometallurgical production of copper in the form of slag and clinker-zinc production for the purpose of comprehensive extraction of non-ferrous and precious metals from them at Almalyk MMC JSC. Clinker, a technogenic waste from zinc production, contains a significant amount of reducing elements in the form of metallic iron and carbon, as well as gold in the amount of 2.3 g/t and silver 250 g/t. In research, clinker works as a reducer of magnetite contained in the converter slag during its depletion and in the process of depletion (reduction) of the converter slag, noble metals are extracted into matte, and then into blister copper up to 95-98%. Converter slags from copper production of Almalyk MMC JSC contain 2.0-3.5% copper, and they, as a circulating product, are depleted in a reverberatory furnace with copper extraction of 75%. To increase the yield of copper from converter slag in Vanyukov furnaces, it is necessary to first deplete the converter slag in reduction processes and then transfer it for processing. It was found that using clinker, a technogenic waste from zinc production with a particle size of +5 - -10 mm, the recovery of converter slag in a converter from magnetite to wustite using the developed technology in 10-15 minutes exceeded more than 50.0% (the amount of magnetite decreased from 21.9 % to 9.8%). As a result of processing recovered converter slags in the Vanyukov furnace, it was possible to reduce the copper content in converter slags of copper production from 2.2-3.5% to 0.58-0.72% in waste slag. To increase the yield of copper from converter slag in the reverberatory and Vanyukov furnaces, it is necessary to first deplete the converter slag in reduction processes and then transfer it for processing.

Regulating the pore structure of periclase refractories by adding Y2O3 to enhance corrosion resistance for copper slag

AbstractThe penetration of copper‐smelting slag into refractories is a major challenge to the research of chromium‐free refractories for copper‐smelting furnace. In this paper, Y2O3 was added to regulate the pore structure of periclase refractories, which enhanced their various properties, especially corrosion resistance to copper converter slag. The results showed that the periclase refractories doped with 1.0 wt.% Y2O3 (1Y sample) possessed the optimum properties. Compared to the sample without Y2O3, the apparent porosity of 1Y sample was decreased by 7.3%, and its average pore diameter was only 3.7 μm. The addition of Y2O3 filled the pores among MgO grains and promoted the expansion of high melting point silicates, thereby reducing the pore size and causing more complex pore structures. This was beneficial to improving the corrosion resistance of periclase to copper slag, especially to prevent the penetration of Cux+ and Na+. After static slag corrosion, the permeability index was significantly decreased by 41% compared to periclase refractories without Y2O3. Moreover, compared to industrial MgO–Cr2O3 refractories, the 1Y sample possessed better resistance to copper slag erosion based on rotating finger tests, and its permeability index and penetration depth decreased by almost 50%.

Corrosion mechanism of novel MgO–Al3BC3 refractories in contact with converter slag

The corrosion mechanism of novel MgO–Al3BC3 refractories in contact with converter slag was investigated. Results demonstrated that refractories with an optimized Al3BC3–Al composition exhibited significantly reduced corrosion index compared with low–carbon MgO–C refractories. The superior corrosion resistance was primarily attributed to the formation of a dense protective layer composed of MgO–MgAl2O4–Mg3B2O6, which was achieved at 1100 °C by combining Al3BC3–Al. These protective layers with enhanced diffusion barriers effectively impedes the penetration and solid solution of Ca and Fe ions, thereby also optimizing the slag viscosity. The self–healing capability of the novel MgO–Al3BC3 refractories further enhances their corrosion resistance.

Development of resource-saving technology for copper production at “Almalyk MMC” JSC

This article discusses the possibility of introducing man-made waste from the production of nonferrous metals from metallurgical processing into copper production. Industrial tests have shown that with the use of technogenic waste from the production of nonferrous metals when smelting copper in metallurgical furnaces, it was possible to reduce the copper content both in the converter slag and in the slag of the reverberatory furnace with the possibility of additional extraction of noble metals. Based on the research carried out, a technological scheme for energy- and resourcesaving copper production technology was developed.

The influence of gas heating on the calculated supersonic parameters of gas-powder flow at slag blower in the converter. Message 1

The article shows that one of the priority tasks in steel production technology is to increase the durability of the lining of oxygen converters. It is shown that the slag blower is a radical way to increase the durability of the lining of oxygen converters. When blowing the melt with oxygen, the MgO content in the slag is 6-8%. To increase the chemical affinity of the slag and the lining, it is proposed to blow the converter slag with jets of nitrogen or powder gas. To achieve optimal chemical affinity of the lining and slag, it is recommended to modify the latter by increasing the content of magnesium oxide in it to 12-14%. Increased durability of the lining makes it possible to solve the problem of replacing wasteful wastes of coal slag and changing environmental concerns on the excess media. It is shown that an attempt to increase the efficiency of modeling very complex processes of interaction of supersonic jets with converter slag has not yet been solved a. A critical analysis of existing methods for constructing mathematical models based on the use of known gas-dynamic laws of interaction of free turbulent jets with the melt is carried out. It has been established that only supersonic jets with their characteristic shock-wave structure always enter the slag melt. An integral method for calculating the parameters of a gas-powder flow in a supersonic nozzle taking into account the powder concentration is presented. It is determined how heating of the gas suspension affects the required pressure in front of the nozzle block, the speed and flow density in the outlet section of the supersonic nozzle. The gas dynamics system is connected to the heat exchange of the flowing gas-dispersed mixture in the Laval expansion nozzles to establish the heating effect in front of the nozzle block of the two-phase gas suspension to a temperature that will ensure The increase in the fluidity of the gas flow is doubled and its kinetic energy is increased threefold. The method of expanding the parameters of the gas-powder flow between the Laval expansion nozzle involves the infusion of 10 physical effects into 14 parameters of the gas-powder flow. It is shown that numerical expansions allow the tuyere body to be used as a heat exchanger for heating the gas suspension, as well as for increasing the pressure of the gas-powder jet that flows from the nozzles

Application of slags for the production of resource‐efficient paving stones

AbstractIn a recent research project under the lead of the Fraunhofer Institute for Building Physics IBP, gravel and sand within a mixture of paving stones were replaced with LD converter slag and blast furnace slag for 50 wt. % and 100 wt. % to produce resource‐efficient concrete components. For this purpose, first, the dry processing of the slags including metal separation and crushing was carried out. In the next step, the particle size distributions of slags using sieve analysis were determined. Finally, the mix designs were set based on the optimum combination of different size fractions of slags. This combination was determined in a way to lead to an almost identical grading curve as that of the original formulation. Splitting tensile strengths of the obtained samples were measured after 14 days of curing under a humidity of 95%. Several paving stone specimens containing slags showed higher splitting tensile strengths than that of the reference sample. Similar results were observed for industrially produced paving stones which demonstrates the successful transfer of the laboratory mixes to the industrial plant.