Slag Consumption Research Articles

A mathematical mould model for transient infiltration and lubrication behaviour of slag in a steel continuous casting process

The transient infiltration and lubrication behaviour of slag during continuous casting of steel is important for billet quality. A two-dimensional coupled mathematical mould model was developed to investigate these phenomena. The accuracy of the model was verified by comparing the calculated slag consumption with measurements by the plant. The results show that the liquid slag is consumed from the middle and late period of positive strip time to the next early period of positive strip time, including the entire negative strip time. The maximum downward infiltration velocity and positive pressure in the slag channel is at the middle of the negative strip time. Increasing the positive pressure of the slag channel is conducive to lubrication. The shear stresses acting on the shell surface and at the mould side were determined by the lubrication slag consumption and total slag consumption, respectively, and gradually decreased with increasing slag consumption. The negative strip time was lengthened to increase the slag consumption and prolong the time near the maximum downward shear stress, so as to be conducive to the demould.

Modelling of Meniscus Behavior and Slag Consumption During Initial Casting Stage of Continuous Casting Process

Modelling of Meniscus Behavior and Slag Consumption During Initial Casting Stage of Continuous Casting Process

Accelerated carbonation and stabilization of BOF slag: data fitting relationship between particle size and CO2 sequestration

Carbonation of BOF slag offers a promising solution to reduce f-CaO content and simultaneously capture CO2. This study investigated the influence of particle size on f-CaO consumption and CO2 sequestration of BOF slag while exploring the kinetics of the carbonation process. Under optimum conditions, the finest particle size achieved f-CaO consumption and CO2 sequestration values reaching 99.72% and 5.57%, respectively; whereas the largest particle size exhibited values of 97.89% and 3.4%, respectively. The shrinking core model accurately described the carbonation process with internal diffusion identified as the rate-limiting step for the whole process. The transition point between two rate-limiting steps was determined along with an established equation between particle size, CO2 sequestration and time. The XRD patterns and SEM images illustrated morphological changes in slag before and after carbonation. These findings can provide crucial insights for optimizing the carbonation process and facilitating its utilization as cementitious materials.

Numerical Simulation of Oscillation Mark Formation and Slag Consumption in Meniscus Region During a Mold Oscillation Cycle

Numerical Simulation of Oscillation Mark Formation and Slag Consumption in Meniscus Region During a Mold Oscillation Cycle

Flow and Influencing Factors of Coated Slag in Continuous Casting Mold

In the continuous casting, the protective slag is coated on the surface of the molten steel, which is an important factor affecting the quality of the billet. The liquid slag layer on the surface of molten steel should be kept at an appropriate thickness to ensure a sufficient supply of liquid slag and to prevent slag from becoming entangled in the billet shell. Moreover, the consumption of protective slag should be appropriate to ensure stable liquid slag film thickness and uniform heat transfer between the casting billet and the mold. In this work, a two-dimensional numerical calculation model using volume of fluid method was established for the flow of protective slag, the Navier–Stokes equation was solved for the model, the consumption of protective slag during a vibration cycle was calculated, and the effects of factors such as casting speed, amplitude, and vibration frequency on the consumption of protective slag were explored. The results showed that when the casting speed increased from 1.2 m/min to 1.6 m/min, the consumption of protective slag per unit area decreased by about 4.76%, but the consumption of protective slag per unit length of the casting billet increased by about 26.98% within a vibration cycle. The consumption of protective slag per unit area and per unit billet length within a vibration cycle increased slightly with the increase of amplitude. The variation pattern of the consumption of protective slag with vibration frequency was not obvious. This model can provide theoretical basis and technical guidance for the design of protective slag, thereby improving the quality of steel billets in steel plants.

Flow and Heat Transfer on the Surface of Molten Steel Slag Layer in Continuous Casting Mold

Protective slag is coated on the surface of molten steel during continuous casting, the flow and heat transfer state of the protective slag is a decisive factor affecting the inflow and consumption of liquid slag and is also an important prerequisite for stabilizing and improving the quality of continuous casting billets. Based on the Navier Stokes fluid momentum conservation equation and energy equation, a two-dimensional longitudinal numerical model describing the flow/heat transfer of liquid protective slag on the surface of steel is established. The data comes from the equipment parameters and casting process of an arc shaped slab continuous casting machine in a domestic steel plant. The flow field and temperature field distribution of protective slag are calculated and analyzed, and the effects of factors such as slag layer thickness and shear speed on the flow and heat transfer status of the liquid slag layer are discussed. When the bottom shear velocity increases from 0.005 m/s to 0.2 m/s, the maximum flow velocity of liquid slag from the nozzle to the narrow surface in the center area of the model increases from 0.0012 m/s to 0.0617 m/s, and the average longitudinal flow velocity of liquid slag near the nozzle increases from 0.0012 m/s to 0.0627 m/s. The research results provide reference for investigating the complex metallurgical behavior of protective slag.

Mechanism of arsenic distribution and migration during iron extraction by copper slag-steel slag combined reforming: A potential solution to refractory wastes

In this study, a combined reforming and reduction smelting of copper slag-steel slag was proposed to recover iron (Fe) from solid waste while lowering the environmental risks associated with the management of such waste. In this process, copper slag was mixed with steel tailing to sinter, and made into pellets after magnetic separation. These two products were extracted by a smelting reduction process to obtain Fe, with a recovery rate of 98.63% and a grade of 92.91%. The migration and enrichment behaviors of arsenic (As) in the process were studied, and its mechanism was analyzed by X-ray diffraction, electron probe micro-analyzer, and X-ray photoelectron spectroscopy. The sequential extraction procedure was adopted to analyze the occurrence form of the hazardous As in the copper slag, while leaching tests allowed evaluating the environmental risk of the slag upon reduction smelting. The results proved that such reduction slag represent a stable and low-risk material. However, As was dispersed and released in each procedure of the process, potentially propagating its hazards into subsequent processes and life cycles. This study highlights the potential of an alternative route for the treatment of waste copper slag while recovering Fe from it. The reformed copper slag has strong adaptability, and the smelting reduction method exhibits a high recovery rate of Fe and low-risk reduction slag that can be widely used. It provides a valid reference for the safe management of heavy metal emissions and environmental risk awareness and helps to achieve large-scale consumption of copper slag and steel slag.

Increasing the Metal Heating Efficiency in High-Temperature Units

This research paper delves into the improvement of the thermal modes of metal heating in the heating wells and it evaluates the metal heating modes in high-temperature units that affect the quality of products. Consideration was given to the main factors that affect the production cost, namely, slag consumption and conventional fuel consumption at different heating temperatures and metal holding times. The described calculations can be used in industry to improve the production process and reduce the cost of production. The research topic relating to metal heating modes in heating wells is relevant in the context of increasing the efficiency of the production of metal products and reducing production costs. The main problem is the instability of thermal processes in heating wells under variable technological regimes. The purpose of this study was to improve the thermal modes of metal heating in heating wells in order to increase production efficiency and reduce costs. The effect of the technological process delays on thermal processes in heating wells has been studied. To analyze thermal processes in heating wells, a calculation method was used that enabled the assessment of the effect of the changed technological regimes on metal heating indices. The calculation of the thickness of the burning-out crust can be used to preemptively control the metal heating process and prevent the dissection and oxidation of sub-crustal gas bubbles. It will help avoid the formation of such defects as the torn edge and reduce the amount of melted metal, as well as reduce the consumption of slagged metal. The obtained results can be used in the production of metal articles for further research to improve the technological regimes of metal heating in heating wells, in particular, to take into account the influence of other factors on thermal processes and to study the possibilities of using the latest technologies to increase the efficiency and competitiveness of production.

Effect of rice husk ash on properties of slag based geopolymer pastes

With the increasing commercialization of fly ash and slag, the price of slag is gradually increasing and there is a need to reduce slag consumption and utilize China's large rice husk production to introduce rice husk ash (RHA) as the raw material. In this experiment, the amount of RHA accounted for a high proportion (50%–80%), and the influence of the amount of RHA on compressive strength, flexural strength, water absorption and moisture absorption coefficient was studied. It is proposed that the degree of efflorescence can be judged according to the water evaporation rate, and the efflorescence degree can be quantitatively characterized by Image-Pro Plus® 6.0, mass weighing of efflorescence substance and pH measurement. In addition, microstructural experiments (SEM, XRD and MIP analysis) were also conducted to confirm the macroscopic experimental phenomena. The test results show that considering the compressive strength and flexural strength, 60% RHA and 40% slag (R6S4) are used together as the precursors to obtain the best mechanical properties. Increasing RHA can raises the water absorption performance, which can play the role of internal curing; meanwhile, it reduces the water evaporation rate by changing pore structure, and fewer free water as carriers inside the sample migrates to the outer surface, inhibiting efflorescence.

ANALYSIS OF THE STRUCTURAL-CHEMICAL MILL DUPLEX-SYSTEMS OF SILICATE-SILICIDE OF LUNG-EARTH METALS. Message 3. The mechanism of desulfurization in the smelting of blast-furnace pig iron

The mechanism of cast iron desulfurization through structural and chemical reactions in smelting slags corresponding to the composition of the main mineral phases is presented: monticellite (MT, SiO2MgOCaO) → mervinite (MP, 2SiO2MgO3CaO) → ockermannite (OK, 2SiO2MgO2CaO) →diopside (DP, 2SiO2MgOCaO) → rankinite (pH, 2SiO23CaO) and eutectic slags (E, 3SiO2MgO4CaO). A sequential series of adsorption capacity of slag phases with respect to sulfur (АС, mas. %) and the depth of metal desulfurization – Δ(S), ppm was determined: Е (3.54/36) → MR (4.8/49) → OK (5, 7/59) → DP (7.14/74) → MT (9.8/103) → RN (20/222). In factory conditions, the efficiency of smelting slags of eutectic composition and diopside for ladle processing of cast iron was tested. The expediency of using such blast furnace slags for ladle processing of cast iron has been established, which at a consumption of 5-10 kg/t provide a desulfurization depth of 200-400 ppm. The consumption of slag is significantly reduced with the additional deoxidation of smelting slags with carbon during the release of melt in the ditch of the foundry and in the pig iron ladle.

Soil stabilization by injection of mineral complexes

Soil stabilization and strengthening is a necessary complex of engineering measures and can be carried out by introducing organic or mineral substances into the soil which increases soil viscosity and its mechanical characteristics. Soil modification can also be accompanied by mechanical pressure, as well as temperature influence. Judging by the results of the analysis of the state of the issue, a hypothesis was formulated, according to which an improvement in the operational characteristics of the soil is possible as a result of the use of a stabilizer based on quicklime and an active mineral additive. The object of the study was light sandy loam. The experiment was carried out using mathematical planning methods with subsequent statistical processing of the results. The following are accepted as variable factors: the consumption of quicklime, the consumption of ground slag and the specific surface area of ground slag. The strength of the modified soil at the age 28 of hardening under laboratory conditions and its average density were taken as response functions. It was established that the introduction of quicklime and finely ground slag could significantly improve the operational characteristics of the soil as a result of analytical optimization of the obtained strength and density functions of the modified soil.

Use of ilmenite ore enrichment wastes in the production of Portland cement clinker

We presented the results of the research on the influence of d-elements of ilmenite ore beneficiation wastes of the Vilnohirsk Mining and Metallurgical Plant on the structure and properties of Portland cement clinker minerals, firing properties and their hydraulic activity. It was established that the use of the enrichment wastes as an aluminosilicate component of the raw material mixture for clinker firing contributes to the reduction of the consumption of blast furnace granulated slag, simultaneously increasing the consumption of limestone. The presence of compounds of d-elements contained in the wastes of enrichment of ilmenite ore in the proposed raw material mixture for obtaining Portland cement clinker increases the saturation coefficient up to 99% and improves the processes of decarbonization and sintering during clinker firing. The physical-mechanical characteristics of the developed cements, in particular the compressive strength limit indicators, are not inferior to those produced according to the classical formulation. Cements obtained on the basis of clinkers, according to their properties, correspond to type II cements (state standard DSTU B.V. 2.7-46:2010). Partial replacement of the clay component in the raw material mixture by ilmenite ore enrichment wastes allows significantly expanding the raw material base for the production of Portland cement clinker and effectively influencing the technological process of firing.

Optimization of Self-Compacting Concrete Containing Blast-Furnace Slag Compositions

The paper deals with composition design of self-compacting concrete containing blast furnace granulated slag and polycarboxylate type superplasticizer in a wide range of concrete strength classes. Optimal superplasticizer content, cement, and blast furnace slag consumptions are obtained from the viewpoint of minimum water demand and water-cement ratio, maximum self-compacting concrete mixture workability retention, and concrete strength. A significant effect of joint influence of superplasticizer and blast furnace slag is demonstrated. The possibility of minimizing the cement consumption at optimal superplasticizer content and slag consumption of 100–120 kg/m3 is shown. Dependences for calculating SCC strength at 1, 7, and 28 days vs. the water-cement ratio are obtained. It is found that the nature of correlation dependences for SCC splitting and compression strengths when using the blast furnace slag and the superplasticizer is linear. Optimization of SCC compositions using mathematical programming enables to obtain compositions with a lowest possible cost while providing a set of specified parameters.

Mathematical Modeling on Slag Consumption and Lubrication in a Slab Continuous Casting Mold

In the current study, a two-dimensional mathematical model was applied to investigate the slag lubrication in continuous casting mold of slab through the acquisition of the average slag consumption per oscillation cycle and the shear stress acting on the shell. The thickness and the consumption of the slag in the shell/mold gap and the downward velocity on either side of the liquid slag were monitored at different distances below meniscus and compared with different casting parameters. With the increase of the distance below meniscus from 10 to 300 mm, the thickness of the total slag and the liquid slag decreased, and thickness was within 0.78 to 1.11 and 0.04 to 0.33 mm, respectively. The average slag consumption at four different locations below meniscus was approximate, within 0.0287 to 0.0298 kg/s in three adjacent oscillation cycles. With enough slag consumption, the shear stress was extremely small and was below 80 Pa at 100 and 300 mm below meniscus. With the decrease of the casting speed from 1.6 to 1.2 m/min, the casting superheat from 45 to 25 K and the oscillation frequency from 180 to 100 cpm, and the increase of the oscillation amplitude from 2 to 5 mm, the average slag consumption per ton of steel and the slag consumption (kg/m2) increased, and the consumption was within 0.0245 to 0.0415 kg/s and mainly below 0.40 kg/m2, respectively, which resulted in the improvement of the lubrication in the shell/mold gap.

A 1D Analytical Model for Slag Infiltration during Continuous Casting of Steel under Non-Sinusoidal Mold Oscillation

A 1D analytical model for slag infiltration during continuous casting of steel is developed to investigate the slag behavior in the mold–strand gap. The superposition principle and Fourier expansion are applied to obtain the analytical solution for transient slag flow under arbitrary mold oscillation including non-sinusoidal oscillation mode. The validated model using literature data partially explains several controversies such as slope of slag film channel, mechanism of non-sinusoidal mold oscillation, and timing of slag infiltration. The model shows that a converging slag film into the casting direction is required to open the mold–strand gap if compression is applied in between. Also, model calculations imply that higher slag consumption is achievable from non-sinusoidal mold oscillation by means of the increase of film thickness through longer positive pressure with higher peak pressure. The model demonstrates a time difference between slag flow and pressure near the meniscus and the discrepancy in timing of infiltration between previous works is attributed to the mismatch. The model provides a concise but reliable tool to understand slag infiltration behavior and design mold oscillation settings.

The role of the composite modifier in the stabilization of the soil base

The conducted research assesses the effectiveness of using metallurgical production waste (gas cleaning dust, slags and slurries) as modifiers of the structure of the ground base of the road surface. Laboratory and field tests were conducted to determine the main strength characteristics of the stabilized soils.The tests used fine-ground slags, dust from gas cleaners of metallurgical production and fine-ground sand from local quarries. The slags were modified with both alkaline hardening activators and Portland cement. The results obtained in the studies were compared with the indicators of soils stabilized with Portland cement.Based on the results of the study, the recommended percentage of stabilizer is 23–30% of the soil mass. Experimentally, it was found that the optimal ratio of components in the slag-alkali binder hardening activator is 60% NaOH + 40% Na2SiO3 (1:1), and when using lime and soda, 10% of the slag consumption. The optimal humidity of the slag-ground mixture for producing slag-ground with high physical and mechanical properties is 13–16% for sandy loams and 16–18% for loams. The strength of cinder samples of alkali-stabilized components exceeds the strength of cement-based materials by 37–66 %.

Effect of Interfacial Reaction between CaO–BaO–Al2O3‐Based Mold Fluxes and High‐Mn–High‐Al Steels on Fundamental Properties and Lubrication of Mold Flux

Contact experiments between low‐reactivity CaO–BaO–Al2O3‐based mold fluxes, F1 and F2, and 1.4–2.2 mass% of Al‐containing steels are conducted to investigate the effect of interfacial reaction on mold flux properties and the ultimate limit of reaction duration capacity of the developed mold flux. F1 contains 30.76% CaO, 17.03% Al2O3, 13.40% BaO, and 10.70% SiO2, whereas F2 consists of 27.90% CaO, 23.60% Al2O3, 12.90% BaO, and 9.57% SiO2 of the mass. The pre‐ and post‐experimental wettability of slag samples on steel substrates and the lubrication behavior of slags are discussed. The main results reveal that SiO2, Na2O, and B2O3 in the mold flux react with [Al] in the molten steel at steel–slag interface. The variations in slag properties indicate that both reaction durations between F1 reacting with twinning‐induced plasticity (TWIP) and F2 reacting with 20Mn23AlV steel can last for 40 min, whereas F2 has wider potential applicability for the continuous casting of Al‐containing steels. Interfacial reaction deteriorates the wettability of slag F2 on 20Mn23AlV steel substrate and reduces slag consumption, as equilibrium contact angle increases from approximately 3° to 37°, but slag consumption prediction is 0.22 kg m−2, which is likely to meet the requirement for lubrication.

Evaluation of coppe slag as aggregate addition on properties of cementitious matrix

This work aims the performance of concretes copper slag-added evaluated in fresh state by slump test and in hardened state by compression strength in 7 and 28 days of cement hydration, durability indexes as water absorption and binder efficiency by cement index. In fresh state, the results showed that the samples with copper slag presented lower slump than the reference sample. In hardened state, with 30% of copper slag addition, the compression strength was reduced only by 9% and 8% in comparison with the control series, for 7 and 28 days, receptively. Also, for 28 and 48 days of cement hydration, the water absorption showed lower values in the series with copper slag, indicating a beneficial performance of this waste in the cementitious matrix. Also, the binder efficiency was verified in the work. As the higher the slag in the mixture, lower was the cement consumption and, consequently, higher was the efficiency of the cement, resulting in a low increased in the cement index. The control series, at 28 days of cement hydration, achieved 11 kg·m-3·MPa-1 while the 30% copper slag-added series achieved 12 kg·m-3·MPa-1, which is only 9% higher than series with no consumption of copper slag, indicating a great performance of the copper slag in this cementitious matrix. Keywords: copper slag; cementitious matrix; replacement; concrete.

Study on Energy Consumption Evaluation for Production of High-Titanium Slag

High-titanium slag is not only the substitute for the gradually depleted natural rutile resources but also the important raw material for the clean production of titanium industry. In this paper, a modeling of energy consumption evaluation for production of high-titanium slag using the ilmenite as raw material was proposed, then the energy consumption of high-titanium slag production by direct reduction-melting and separation process (two-stage process) was measured on production site. The energy consumption of high-titanium slag was converted into standard coal energy or electric energy by the energy value method and the energy equivalent method, respectively, on the base of data collected from the plant. The electric energy consumption of high-titanium slag produced by the two-stage process was 1661.6 kWh per ton slag with the energy value method. Due to the energy value conversion method more reflects the value of electricity, which is suitable for applying to the energy consumption evaluation of high-titanium slag production.

Mold Nonsinusoidal Oscillation Mode and Its Effect on Slag Infiltration for Lubrication and Initial Shell Growth during Steel Continuous Casting

The effect of nonsinusoidal oscillation at different modification ratios (α) on slag lubrication was investigated during mold oscillation. A validated and reliable multiphase model was employed, which involved flow and solidification of the molten steel and mold slag. The main results revealed that a large amount of liquid slag at the entrance of the mold–strand channel reflowed into the slag pool at the middle of the negative strip period. The phenomenon was more distinct, with an increase in the modification ratio. The modification ratio had no obvious effect on the average thickness of the liquid film at different depths below the meniscus. A modification ratio of 0.5 caused less fluctuation of the transient liquid film. Quantitative prediction of slag consumption indicated that as the modification ratio increased from 0.2 to 0.5 to 0.8, the average values were 0.278, 0.286, and 0.279 kg/m2, respectively. Shell solidification and growth near the meniscus mainly occurred when the mold was descending, which not only depended on the heat flux, but also on the liquid slag flow, the pressure driven by slag rim, and the mold oscillation. Optimization of the modification ratio of nonsinusoidal oscillation could be an alternative to delay growth of the initial shell towards the molten steel. A modification ratio of 0.5 had the least robust shell tip at the meniscus, thereby reducing entrapment of inclusions and bubbles by the shell tip.