Types Of Slag Research Articles

Research into the properties of poured asphalt from electric furnace slag aggregate

Purpose. This study case shows the influence of the use of electric furnace slag as an aggregate with a high positive impact on the properties of poured asphalt (AC). Research results regarding the skid resistance, depth of surface texture, resistance to erosion, water absorption, pressure solidity, and pellets of clay have argued the fact that adding this slag to mixing eruptive aggregate indicates improvements of mechanical characteristics of poured asphalt and its surface layer. Methodology. Preliminary preparation of the poured asphalt blend preliminary mixture, sampling and examination of the properties are developed in accordance with standard methods: EN 12697-27:2000, SK EN 12697-36:2003, EN 12697-2:2002+A1:2007, EN 12697-8:2003, EN 12697-34:2004+A1:2007, (Marshall Test), EN 12697-6:2004, and SIST EN 12697-2:2004. Findings.The metallurgical industries for years have been using all their by-products, including slag, as valuable resources for the industry and especially in the construction materials industry. The use of this process by-product in the construction industry, mostly in road construction, is among the key factors in saving natural resources and preventing environmental pollution. Originality. For the preparation of the preliminary recipe for three types of poured asphalt (AC 0/11, 0/8 and 0/5 mm), electric furnace slag and the eruptive sand with grain size from 0 to 11 mm, 0 to 8 mm and 0 to 4 mm were used. Practical value. The use of this type of slag as an aggregate of this bituminous mixture will not only show improvement of the physical-mechanical properties of AC, but will also show high economic and environmental effects.

The effect of Basic Oxygen Furnace, Blast Furnace, and Kanbara Reactor Slag as Reinforcement to Cement Based Mortar

Slag is a waste from steelmaking industries that was released into the environment. Slag was used as reinforced material in mortar. Different types of slag, including Air Cooled Slag (ACS), Granulated Blast Furnace Slag (GBFS), Basic Oxygen Furnace Slag (BOFS), and Kanbara Reactor Slag (KRS), were used as a reinforcing material in this study. The composition of slag in the mixture on mortar was 10%, 20%, 30%, 40%, and 50%. The sample was made with a water-cement ratio (w/c) of 0.35, with the ratio of sand and cement being 1:1.5, respectively. Treatment of mortar sample at ambient temperature was applied. The mortar samples were left to cure until 3, 7, and 28 days, which performed a compression test. The results show that adding slag to the mortar enhanced the compressive strength of the pristine mortar. The highest strength was obtained by adding 10% slag at 28 days. The compressive strength of GBFS, BOFS, KRS, and ACS was 23.76 MPa, 23.28 MPa, 19.68 MPa and 17.48 MPa, respectively. Based on the XRD result, it was discovered that the mixture has more Calcium Silicate Hydrate Peak than Pristine mortar.

Effect of Phase Composition on Leaching Behavior and Mechanical Properties of Ceramics from Ferrochrome Slag and Tundish Slag.

Ferrochrome slag (FS) and tundish slag (TS) are two typical slags containing high contents of Cr2O3 (3.88 wt.%) and MnO (18.69 wt.%), respectively. In this study, batches of ceramics were prepared from FS and TS, and their Cr/Mn leaching behaviors, mechanical properties and microstructures were investigated. Results showed that ceramics with 80 wt.% FS or 85 wt.% TS had acceptable properties. By controlling its composition and sintering temperature, pyroxene or spinel phases could become the main crystalline phases of the fired ceramics containing either of the two slags. For both slag series, pyroxene phases contributed to higher bending strengths, whereas spinel phases led to lower Cr/Mn leaching rates. Both ceramic containing 20 wt.% FS and ceramic containing 85 wt.% TS had the main crystals of pyroxene phases and possessed the highest bending strengths (FS20: 114.52 MPa and TS85: 124.61 MPa). However, both ceramic containing 80 wt.% FS and ceramic containing 25 wt.% TS with main crystals from the spinel phases had the lowest Cr/Mn leaching rates (FS80: Cr 0.05% and TS25: Mn 0.43%). Therefore, optimum designs for the compositions of ceramics from different slags were achieved by changing the proportions of pyroxene and spinel phases to obtain a balance between the high strengths of materials and the stable retention of heavy metal ions. This study provides an important basis for long-term research on the large-scale reuse of heavy metal-containing slags in the ceramic industry.

Reaction between molten steel and CaO–SiO2–MgO–Al2O3-FetO slag under varying amounts of converter carryover slag

Converter carryover slag during tapping has been a trouble for improvement of steel quality. In order to give an insight into the action mechanism of carryover slag on steel during tapping, a serious of molten steel-slag reaction experiments was conducted to elucidate the reaction mechanism between 3% Al steel and CaO–SiO2–MgO–Al2O3-FetO type slag at 1600 °C as well as its resulting effect on cleanliness under varying amount of converter carryover slag was investigated in laboratory. Composition evolutions in molten steel and slag during the reaction and microstructure on the steel-slag interface were investigated by employing different experimental techniques. 2[Al] + (Fe2O3) = 2[Fe] + (Al2O3) and 4[Al] + 3(SiO2) = 3[Si] + 2(Al2O3) were confirmed as a major reaction in the system. The initial (Fe2O3) content in experiments increased from 3% to 15%. The results indicated the metal-slag reaction tended to stable after about 10 min, the mass transfer of [Al] in molten steel was the rate-controlling step [Als] was more prone to react with (SiO2) for slags with initial (Fe2O3) less than 4.07%, but it reacted with both (Fe2O3) and (SiO2) when (Fe2O3) content was more. It was therefore suitable addition of Al alloy should take (SiO2) into consideration in addition to (Fe2O3) and dissolved [O]. Increase of carryover slag amount represented by increase of initial (Fe2O3) decreased the sulfur distribution but promoted the formation of MgO·Al2O3 inclusion. The sulfur distribution ratio decreased from roughly 5000 to 2000 but the number density of inclusion increased from 22.125/mm2 to 45.875/mm2 with increase of initial (Fe2O3) from 3% to 15%.

Oxidation behavior of boron in 9CrMoCoB steel by CaF2–CaO–Al2O3–SiO2–B2O3 electroslag remelting (ESR) type slag

The laboratory-scale experiments between the CaF2–CaO–Al2O3–SiO2–B2O3 slag and 9CrMoCoB steel were carried out in alumina and magnesia crucibles at 1823 K to investigate the oxidation behavior of boron (B) during the electroslag remelting (ESR) process. The activities of SiO2 and B2O3 in the slag and the activities of Si and B in the molten steel were calculated by the ion and molecule coexistence theory (IMCT) and the Wagner formalism, respectively. The results showed that both SiO2 and B2O3 have a significant influence on the equilibrium B content. The calculated content of B was in good agreement with the experimental value when the SiO2+B2O3 content in the slag is more than 3.3 wt%. The temperature had little influence on the equilibrium B content when the SiO2, B2O3 and CaO content were in the ranges of 3–5 wt%, 0–1 wt%, and 20–30 wt%, respectively. However, the Si is more prone to oxidation than is B as the temperature increases, indicating that more SiO2 should be added in the slag to reduce the oxidation of Si. From the 80 tonnes industrial tests, the distribution of B and Si content along with the radial direction of the remelted ingot was almost uniform, which is in line with the calculated B content (approx. 30 ppm) under conditions of the Si content in the liquid steel and the (%B2O3)/(%SiO2) ratio are 0.07% and 0.05, respectively, at 1973 K.

New finds of copper metallurgy during the bronze age in the Timok region (north-east Serbia)

Over the last 7 years a series of discoveries were made at Banjsko Polje near the city of Bor, the largest copper exploitation center in south-eastern Serbia, which prove that in the Bronze Age copper metallurgy intensified on this territory. Besides the remains of two metallurgical kilns, a large quantity of ceramics and slag was discovered from the same context. The types of slag indicate a complex process of extracting copper from sulfide ore of the Timok eruptive basin, where the first absolute date established for the Bronze Age on this territory contributed to a change in the archeological framework and genesis of prehistoric culture in the Timok Region.

Review on usage of steel slag for roads

India is the 3rd largest producer of steel with a capacity of 101 Metric Ton (MT), and this capacity is expected to grow up to 125-150 MT by 2025. The iron and steel industries generate millions of tons of various types of slag. These slags are generated during iron making and steel making processes, and are residue from these processes made of minerals like silica, alumina, and titanium from iron sand, as well as combinations of calcium and magnesium oxides. 2-4 tons of waste are generated for each ton of steel produced in different forms such as solids, liquids, and gas. The disposal of such slags is a major challenge for the steelmaking industry. With a growing availability of huge quantities of such slag materials, there is currently great focus on research to develop slag processing technologies that enable re-use of such slags in various infrastructure construction projects. The properties of the slags are very similar to the properties of natural aggregates in terms of both physical and chemical composition, and they have immense potential for extensive use in road construction and infrastructure projects as an alternative to natural aggregates. Rapid infrastructure development has led to a scarcity of natural aggregates as the demand is too high for them. These slags from the iron and steel industry are processed to make them suitable for use as natural aggregates replacements, contributing to sustainability in the construction industry. These slags can be used as an alternative to natural aggregates in sub-base, base and asphalt layers, and in concrete aggregates instead of being dumped as industrial waste near the plants. Standards, codal requirements, and suitable specifications need to be established for the large-scale use of slag continuously in construction, as well as for the implementation of large-scale recycling and re-use of slag from these industries, which can solve environmental issues in handling such industrial wastes.

Leaching and Geochemical Modelling of an Electric Arc Furnace (EAF) and Ladle Slag Heap

Old metallurgical dumps across Europe represent a loss of valuable land and a potential threat to the environment, especially to groundwater (GW). The Javornik electric arc furnace (EAF) and ladle slag heap, situated in Slovenia, was investigated in this study. The environmental impact of the slag heap was evaluated by combining leaching characterization tests of landfill samples and geochemical modelling. It was shown that throughout the landfill the same minerals and sorptive phases control the leaching of elements of potential concern, despite variations in chemical composition. Although carbonation of the disposed steel slags occurred (molar ratio CO3/(Ca+Mg) = 0.53) relative to fresh slag, it had a limited effect on the leaching behaviour of elements of potential concern. The leaching from the slag heaps had also a limited effect on the quality of the GW. A site-specific case, however, was that leachates from the slag heap were strongly diluted, since a rapid flow of GW fed from the nearby Sava River was observed in the landfill area. The sampling and testing approach applied provides a basis for assessing the long-term impact of release and is a good starting point for evaluating future management options, including beneficial uses for this type of slag.

Deciphering the bacterial microbiome in response to long-term mercury contaminated soil

Hg contaminated soils are of concern due to the toxic effects on soil microbes. Currently, the adaptation of bacterial community to long-term Hg contamination remains largely unknown. Here, we assessed the effects of Hg contaminated soils on the bacterial communities under controlled conditions using 16S rRNA gene amplicon sequencing. The results showed that the bacterial α-diversity and richness were significant positively correlated with total Hg (p < 0.05). Land-use type, pH, EC, TK, and nitrate-N played important roles in shaping the bacterial communities. Long-term Hg-contaminated soils can be divided into three types based on land use types: slag type, farmland type, and mining area type. The dominant phyla include Proteobacteria, Actinobacteriota, Acidobacteriota, Chloroflexi, and Firmicutes. The dominant genera identified were Pseudomonas, Gaiella, Sphingomonas, Bacillus, Arthrobacter, Nocardioides. Network analysis showed that dominant taxa had non-random co-occurrence patterns and module 1 had an important role in responding Hg stress. Keystone genera identified were Bauldia, Phycicoccus, Sphingomonas, Gaiella, Nitrospira. The above results further our understanding of the adaptation of the bacterial community in long-term Hg-contaminated soil. This study has important guiding significance for the use of bacterial consortia to remediate Hg-contaminated soil.

Corrosion of magnesia-chromite refractory by PbO-rich copper slags

The work presents corrosion of direct-bonded MgOCr refractory by three types of PbO-rich copper slags. Pellet test, contact corrosion test and hot stage microscopy test enabled to study corrosion phenomena at 1300 °C and 1450 °C, respectively. The structure and microstructure of the after-corrosion samples were deeply analyzed, with the former one aided by development of image detection algorithms. Slags infiltrated the refractory through open pores and cracks. Slag components diffused into refractory and changed its original composition. Forsterite solid solution, Mg2SiO4 s.s., which formed as the only corrosion product caused swelling of microstructure and disintegration of magnesia-chromite direct bonds, critical for the performance of refractory.

Study on the fluidity of ash slag of liquefaction solid product and lignite co‐gasification

AbstractThe utilization of liquefaction solid product (LSP) obtained from fluidization reaction pyrolysis has become a pressing obstacle limiting the industrialization of coal liquefaction technology. In this work, gasification of LSP and Hami lignite coal (LC) and their blend at different ratios was investigated. In addition, the melt flow, mineral transformation, and crystallization behavior in the fusion process and cooling process were investigated. The results show that both LSP and LC are typical crystalline slags and cannot be applied to entrained flow gasification alone. The co‐gasification of LC and LSP is a feasible method to improve their fluidity. At the ratio of 2:1 (LC to LSP), the blend has the lowest AFT. For molten slag, viscosity of the sample corresponded well to the structure of the slag. LC1:2LSP with higher Q2 and Q3 content showed a high viscosity, while LC1:2LSP with higher Q0 and Q1 content showed a lower viscosity. Besides, the size of the crystals generated during cooling is inversely proportional to the high‐temperature viscosity of the sample, the migration of ions became difficult, and the growth of crystal size was inhibited at high viscosity. Meanwhile, the slag type of samples was influenced by the precipitated crystals. Tcv can be effectively reduced by blending LC with LSP in a certain proportion. The results provide a theoretical basis for the utilization of LSP for the operation of entrained flow gasification.

Effects of accelerated carbonation and high temperatures exposure on the properties of EAFS and BOFS pressed blocks

The accelerated carbonation of steel slag can improve its subsequent application as construction materials and can also store CO2 as stable minerals. Due to the differences in the production process, electric arc furnace slag (EAFS) and basic oxygen furnace slag (BOFS) acquire diverse physical and chemical properties, which expected to perform differently upon accelerated carbonation. Especially considering the potential use as green building material, thereby may be subject to fire risk. This research aims at comparing the influence of carbonation temperature, CO2 pressure, and carbonation time on mechanical properties and carbonation efficiencies of EAFS and BOFS pressed blocks, and emphasizing on their performances under elevated high temperatures. Results show that BOFS block has a much better performance than EAFS block, with about twice the compressive strength and CO2 uptake, owing to the higher calcium content and more reactive calcium mineral (portlandite) existed. The strengths of both two types of steel slag pressed blocks were found to increase with the increase of high temperature exposure up to 400 °C due to subsequent hydration reaction induced by elevated temperature. Although a slight decrease of compressive strength can be found after further heating at 600 °C, the residual strength was still comparably higher than that at 20 °C. However, with further increase of heating temperature up to 800 °C, a significant reduction in strength was noticed for both EAFS and BOFS blocks, associated to the decomposition of carbonates phases as the main contributor of bearing-strength within the blocks.

Iron production in Ptolemaic Egypt: From the Abu Gerida specular hematite mines to the Hamama smelting workshop

AbstractAlthough ancient Egypt has a firmly established record of mining and metallurgy of gold and copper, iron production in ancient Egypt is less well documented. Evidence of ancient iron manufacture in Egypt is to be found in the burnt plant remains, slag fragments, and a furnace‐like structure discovered in the Hamama workshop in the Eastern Desert of Egypt. The iron ore required for iron production was delivered from the nearby specular hematite mines of the Abu Gerida area. This Egyptian specularite is geochemically distinguished from other Mediterranean varieties of specularite such as those in Elba, Tuscany, and Seriphos Island. The bloomery iron smelting process in the Hamama workshop produced two types of slags: furnace slags and tapping slags. These two types show different petrographic features and geochemical signatures. Some of the geochemical signatures of the slags, such as their high calcium contents, were derived from charcoal, while others were related to the ore used during the smelting process. Radiocarbon dating of the charred plant remains from the Hamama workshop suggests that the iron smelting activities took place in the early Ptolemaic era. Iron production was seasonal and was conducted by locals who most likely had dynamic socioeconomic ties with the urban centers of the Nile valley.

Influence of aluminum sulfate on strength of CaO-activated slag system

To solve the problem of low early strength of the CaO-activated slag system, the influence of adding Al2(SO4)3 as an auxiliary activator on the compressive strength development, hydration products and microstructure of CaO-activated blast furnace slag (BFS) system was investigated in this study. The results showed that adding Al2(SO4)3 enhanced the strength of binders prepared from two slag types (S1 and S2) when the addition of Al2(SO4)3 was no more than 3 wt%, including 3-d strength and 28-d strength; with an increase in Al2(SO4)3 content, the strength enhancement gradually weakened. The strength enhancement of Al2(SO4)3 was attributed to its ability to accelerate the hydration reaction and induce more dissolution of BFS as well as the formation of more ettringite and calcium silicate hydrate gels, which was confirmed by the setting time, hydration heat, X-ray powder diffraction, thermogravimetric analysis and mercury intrusion porosimeter. This study proved that the compressive strength enhancement effect of Al2(SO4)3 on group 1 was weaker than on group 2 due to the difference in chemical oxide composition and the reactivity of the two slag types. Further, the addition of Al2(SO4)3 significantly influenced the pore size distribution of the binders.

The effect of coal viscosity-temperature characteristics on the dynamic response of slag discharge behavior in Shell gasifier

How to efficiently and quickly detect the slag blocking behavior of entrained flow gasifiers was an urgent engineering problem. At present, the syngas composition of the gasifier was usually detected to judge whether slag plugging occurred, which had significant hysteresis. In this study, based on the slag dynamic flow model, the influences of operating conditions and slag viscosity-temperature characteristics on the slag discharge behavior of shell gasifiers were investigated. The results showed that the viscosity-temperature characteristics of slag had a great influence on the slag flow response process. The slag steady time and the corresponding steady thickness increased gradually with the transformation of slag type from glassy slag to crystalline slag. When the critical viscosity increased from 9.66 Pa·s to 43.5 Pa·s, the total slag thickness of glassy slag B and crystalline slag D increased by 6.4 and 10.5 cm, respectively. Besides, the slag steady time increased exponentially with the decrease of operating temperature. When the operating temperature dropped by 90 K, the steady-state time of the crystalline slag D reached 210 h.

Effective and economical treatment of low-grade nickel laterite by a duplex process of direct reduction-magnetic separation & rotary kiln-electric furnace and its industrial application

An innovative technical route has been proposed to improve recycling efficiency of Ni and Fe from low-grade nickel laterite via the duplex process between direct reduction-magnetic separation and rotary kiln-electric furnace. The results indicated that the high‑nickel concentrates produced from direct reduction-magnetic separation process, which were combined with optimization of slag types can not only increase the grade of furnace burdens and decrease quantity of slag, but also improve the fluidity of slag and smelting efficiency as well as reduce the power consumption of smelting. For the industrial application of duplex process, a preferable stainless-steel master alloy with 10.02% Ni was obtained at a lower cost of 8420 RMB/t than that of 8731 RMB/t for a stainless-steel master alloy containing 8.14% Ni in conventional rotary kiln-electric furnace process, and the recovery of nickel also increased from 91.27% to 95.51%, which shows an obvious superiority for treating the low-grade nickel laterite.

Sulfuric acid effect and application of freezing-thawing curing on long fiber reinforced metabentonite and slag-based geopolymer composites

In this study, different types of metabentonite (MB) and slag (S)-based geopolymer were produced based on origin, polyvinyl alcohol (PVA) and basalt (B) fiber at different percentages of 0.2%, 0.4%, and 0.6%. A total of 7 series were produced. Two steps of curing method were applied for the samples, the first step was at room temperature from day 1-7, and the second step freezing-thawing from 8-28 days. Thus, the applicability of a curing method that used less energy instead of heat curing was investigated. Due to the freezing-thawing curing, the continuation of geopolymerization reactions was ensured and a compact structure was created. The produced samples were subjected to 10% sulfuric acid effect for 3 months after the 28th day. Compressive strength, flexural strength, ultrasonic pulse velocity (UPV), and weight losses due to acid effects were found. Despite the decrease in mechanical properties after the acid effect, the geopolymer products didn't experience easy dispersal because they had strong aluminosilicate bonds, crystalline phase formation, morphology, and lower calcium content that provided high stability. Also, SEM, XRD, FT-IR, and TGA-DTA analyzes and visual inspection resulting from the acid effect were examined.

Treatment of copper converter slag with deep eutectic solvent as green chemical.

Industrial copper slag is among the most important wastes to be evaluated in terms of containing valuable metals and the amount of waste approaching 30 million tons per year. Therefore, in this study, it was aimed to propose a feasible route for copper and zinc recovery from copper converter slag (CCS) by using choline chloride (ChCl) based deep eutectic solvent which is applied on this type of slag for the first time. During the leaching experiments with the pure ChCl-2urea mixture, temperature (25-95°C), leaching duration (2-72h), and pulp density (1/10-1/40g/mL) were selected as the parameters to be investigated for Cu and Zn extraction. After the experimental results, the optimized conditions for the ChCl-2urea leaching process, which gave 89.9% Cu and 65.3% Zn extraction was found at 48h, 95°C, 1/20g/mL pulp density with 600rpm stirring speed. It is noted that the iron dissolution ratio is very low (max. 4.7%) under the selected conditions. At the end of the iron cementation stage, the total recovery efficiency as a pure metallic copper was 63%. The calculated activation energy for the dissolution of the copper and zinc from CCS is 8.86kJmol-1 and 14.48kJmol-1, respectively.

The use of blast furnace slag as a supplementary cementitious material

Waste material recycling in mortar production not only provides a promising resource for producing high-quality mortar, but it also aids in properly addressing the waste disposal issue. This study investigates the potential of utilizing blast furnace slag wastes as a supplementary cementitious material in blended cement-based mortars.The experimental program includes investigation of compressive strength of cement-based mortar composites contained different types and percentages of slag wastes. The mortar specimens were prepared and cured following related international standards. After curing, the compressive strengths of the tested specimens were assessed and compared with control specimens. The influence of the chemical composition of the investigated slag types on the resulted strength of the blended cement mortar was also discussed. Results of this study revealed that the chemical compositions of the raw slag wastes have significant effects on the pozzolanic activity of the produced slag. Slag samples contained higher percentages of calcium oxides present the most promising results regarding the production of supplementary cementitious material.

Removal Mechanisms of Slag against Potentially Toxic Elements in Soil and Plants for Sustainable Agriculture Development: A Critical Review

Potentially toxic element (PTE) pollution is a major abiotic stress, which reduces plant growth and affects food quality by entering the food chain, and ultimately poses hazards to human health. Currently, the use of slag in PTE-contaminated soils has been reported to reduce PTEs and toxicity in plants. This review highlights the role of slag used as a fertilizer for better crop production and sustainable agricultural development. The application of slag increased the growth, yield, and quality of crops under PTE toxicity. The mechanisms followed by slag are the immobilization of PTEs in the soil, enhancement of soil pH, changes in the redox state of PTEs, and positive changes in soil physicochemical and biological properties under PTE toxicity. Nevertheless, these processes are influenced by the plant species, growth conditions, imposition length of stress, and type of slag used. The current review provides an insight into improving plant tolerance to PTE toxicity by slag-based fertilizer application and highlights the theoretical basis for applying slag in PTE-contaminated environments worldwide.