Chemical assessment of the electric arc furnace slag as construction material: Expansive compounds

To carry out a correct management of electric arc furnace slags (EAS) requires a detailed knowledge of their properties. From a chemical point of view, the EAS are surrounded by some chemical problems related to its volume instability when they are used as construction materials, due to the presence of potentially expansive compounds such as free lime and mainly free MgO. The current work focuses on the chemical assessment of the black slags coming from an electric arc furnace in order to know the possible chemical disadvantages as construction materials. A complete study of chemical and mineralogical compositions, pozzolanic activity and the quantification of main expansive compounds in EAS were realised. The results show that the nature of these slags has a very high crystallinity; total absence of pozzolanic activity and the presence of expansive compounds in slags (Cl⁻, SO₃, free CaO and free MgO) were very low, if not null concentrations.     

Slag resistance of refractories in the lining of an arc steel melting furnace

The interaction of refractories of various grades with liquid slags whose samples were taken in different stages of melting from an electric furnace are investigated by wetting for temperatures ranging from 20 to 1550°C. The compositions of the slags differed in the CaO/SiO₂ proportion and the content of chromium oxide. It has been established that the olivinite refractory has advantages under the conditions of electric melting, which seems to be explainable by its chemical composition and specific pore structure. The results of the investigation were used to develop compositions of gunite powders for torch guniting of linings of the slag belt of an arc steel melting furnace. Translated from Ogneupory, No. 9, pp. 18 – 20, September, 1995.     

Characterization of granulated and pelletized blast furnace slag

The objective of this study is the characterization of slags from different sources by their chemical composition, glass content, rate and total heat of hydration and compressive strength development with a view to establish a relationship between some of their properties and compressive strength. Binders incorporating 50 per cent slag present the same classification derived from total heat evolved as from slag activity indexes.     

Study on steel furnace slags with high MgO as additive in Portland cement

In this study, usability of Basic Oxygen Process (BOP) slags of Kardemir Iron and Steel Plant, Karabük, Turkey as an additive into cement was investigated. Slags were ground to 4000 and 4700 cm²/g levels, and added in ratios 15, 30 and 45 wt.%. Volume expansion, setting time, compressive strength and bending strength tests were measured according to Turkish standards. Due to impurities of the slags, the 2- and 7-day compression strengths decrease with increase in amount of Mn, but this decrease is lower in the 28-day compression strength, 30 wt.%. It is observed that the physical and mechanical properties of the resulting concrete were acceptable in the Turkish Standards Institute (TSE).     

Resistance of blast furnace refractories to the action of aggressive reactants under conditions of an oxidizing gaseous atmosphere

Conclusions Investigations have been made of the resistance of ShPD-41, ShPD-39, and ShUD-37 chamotte refractories to the action of K₂CO₃, Fe₂O₃, blast furnace dust, and initial and final blast furnace slags under conditions of an oxidizing atmosphere. The investigation results showed that iron oxides and slag break down these refractories at 1400–1500°C. Dense ShPD-41 refractory is more resistant to the action of the reactants.The most resistant to the action of slags and iron oxides at 1400–1500°C are silicon carbide refractories with binders of silicon nitride and oxynitride.Translated from Ogneupory, No. 7/8, pp. 24–27, July–August, 1992.     

Production of high-alumina cement clinker by fusion in an electric furnace

Conclusions The possibility of obtaining clinker from high-alumina cement by melting a mixture of lime and technical alumina in an electric-arc furnace at the Klyuchevsk Ferroalloy Plant has been shown.The high-alumina cement obtained from fused clinker is significantly better in its physicochemical properties than the cement produced on the basis of the lime-alumina slags from the ferroalloy industry.Translated from Ogneupory, No. 5, pp. 25–27, May, 1984.     

Service of refractories in a blast furnace shaft

Conclusions The destruction of the refractory structure of a blast furnace depends on the properties of the refractory, the system of cooling the lining, the furnace operating cycle, the action of alkalis, primary slags, zincite, and sooty carbon, the running of the furnace, the thermal stresses in the structure, abrasion of the batch, and other factors.To increase the life of the shaft lining in a blast furnace it is necessary to use dense, high-fired brick for the structure, prepared on the basis of high-grade kaolin raw materials with the minimum content of fluxing oxides; to use the best system of cooling the shaft; and to stabilize the blast furnace working cycle, especially during the first period of operation after the blow right up to complete drying-out of the refractory structure.Translated from Ogneupory, No. 7, pp. 28–37, July, 1968.     

浅谈电石乙炔废弃物制水泥工艺路线的选择

通过对电石乙炔废弃物(电石渣)与石灰石的性质对比,以及目前常见的传统湿法窑、带压滤的湿法窑、湿磨干烧、新干法等电石渣制水泥生产工艺在消耗以及环境影响等方面的对比,阐述了电石渣制水泥工艺的特点及实际应用情况,并对电石渣制水泥工艺路线的选择提出了建议。     

Effect of viscosity and phase composition of converter slags on the destruction of refractories

Conclusions Converter slags formed in the first 10–12 min of the blowing of the iron, after cooling consist mainly of manganese-iron monticellite, glassy, and cryptocrystalline substances, free calcium oxide, and metallic iron. The primary slags are characterized by a low basicity, refractoriness, and viscosity, and rapidly react with the refractory during the period of their formation in the converter at 1150–1360°C. The primary slags are changed into the truly liquid state at 1256–1312°C.In the middle of the iron blow the slags show a substantial increase in their quantities of calcium silicates, which increase their refractoriness and viscosity. The slags are formed, change into the truly liquid state, and begin to react with the refractory at higher temperatures with the formation of smaller quantities of melt, compared with what is observed during the reaction of the primary slags and the refractory.At the end of the blow the slags show substantial increases in the concentrations of iron oxides, on account of which ferrites and aluminoferrites of calcium are formed, reducing the refractoriness and the viscosity of the slags.The presence of ferrites and aluminoferrites of calcium increases the corrosiveness of the final slag with respect to periclase-spinel refractories, compared with the corrosiveness of slags formed in the middle of the blowing of the iron.Translated from Ogneupory, No. 3, pp. 40–45, March, 1972.     

Use of metallurgical slags in the technology of dolomite refractories

The elemental and mineral compositions of slags of blast-furnace, open-hearth, and electrosmelting production at some enterprises are analyzed. Laboratory development of a technology of stabilized dolomite refractories using 40 – 45% metallurgical slags is carried out. A high-quality product is attained by using open-hearth slags and slags from electrosmelting of alloyed steels. The quality parameters of the stabilized dolomite articles make them an alternative to chromite-periclase articles.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 12, pp. 16 – 20, December, 1996.     

Effect of TiO2 substituting SiO2 on the rheological and crystallization behavior of mold slags for casting Ti-containing steel

In the current study, the influence of TiO₂ substituting SiO₂ on the rheological and crystallization behavior of mold slags for casting Ti-containing steel was investigated through the measurement of the viscosity-temperature relationship, crystallization process and initial crystallization temperature. The structure of molten slags from the Raman spectrum and other parameters (NBO/T and Optical basicity) was compared to explain the difference of slag properties. With the substituting of SiO₂ by TiO₂ in slags from 5% to 20%, the viscosity of these slags at 1573 K decreased from 0.36 Pa s to 0.10 Pa s, and the viscous flow activation energy below the break temperature had the tendency to decrease. With the increase of the TiO₂/SiO₂ ratio from 0.25 to 4.00, the initial crystallization temperature of slags increased and the crystallization of slags were enhanced, which was related to the difference of the crystallization mode and the precipitation of dispersed crystals as nuclei. With the substituting of SiO₂ by TiO₂, the parameter NBO/T and optical basicity of molten slags increased, the complex network structure by the Raman spectra depolymerized gradually and the degree of polymerization decreased, which was related to the destruction of silicate/aluminate structure by the addition of TiO₂ in slags. Hence, the substitution of SiO₂ by TiO₂ in slags simplified the network structure of mold slags, then lowered the viscosity and promoted the crystallization of slags.     

Surface crystallization of glass based on blast furnace slags

Using differential thermal analysis, X-ray phase analysis, electron microscopy, and optical microscopy, surface nucleation of crystals in glass, obtained from metallurgical slags with the addition of SiO₂, is studied. It is shown that the main phases, crystallized from the surface of the samples are melilite (solid solution of gehlenite 2СаО · Al₂O₃ · SiO₂ in akermanite 2СаО · МgO · 2SiO₂) and diopside (CaO · МgO · 2SiO₂). The kinetics of the crystallization of glass is studied and the rates of the surface crystal growth are determined in the glass of nine compositions. The influence of the degree of dispersion of the particles of the original glass on the deposition order of the crystalline phases and the degree of crystallinity of the glass is studied.     

漆渣的特点与处置技术

探讨了漆渣的主要成分与危害,针对几种典型漆渣进行了取样、分析其特征和成分。同时对比了几种典型的漆渣处理、处置方法,并对当前漆渣的处理方式提出了建议。     

转炉渣熔融改性的实验研究

高碱度转炉渣中游离氧化钙(f-CaO)的存在是造成其膨胀的主要因素,限制了其作为建筑材料的应用。采用压蒸法测定了转炉渣的膨胀性,考察了粒度和陈化时间对转炉渣膨胀性的影响,在熔融态转炉渣中加入高炉渣,分析了熔融反应后产物的结构,并用压蒸法测定分析了熔融反应后转炉渣体积膨胀率的变化,实验结果表明熔融态转炉渣中加入高炉渣可以显著降低其体积膨胀率,为转炉渣应用于建筑材料提供依据。     

Erosion mechanism of tabular alumina of various microstructures under different basicity of blast furnace slag

In this study, three types of commercial tabular alumina aggregates with different microstructural characteristics were selected for corrosion tests on blast furnace slags with varying basicities. A corrosion mechanism with different microstructural characteristics is proposed, and the dominant microstructures in high- and low-basicity environments are evaluated. The pore structure was found to have a crucial influence on the dissolution of tabular alumina aggregates in the blast furnace slag. Under low-basicity (0.5–0.7) conditions, a small amount of clustered pore structure was beneficial for obtaining the maximum thickness (40–60 μm) of the isolation layer between the tabular alumina aggregate and slag. Under high-basicity (0.9–1.1) conditions, the circular pore structure tended to form a uniform and stable double-layer isolation structure of calcium hexaaluminate and MgAl₂O₄ spinel.     

用冶金渣制备聚硅硫酸铁的研究

用钢渣和水渣制备出聚硅硫酸铁,分析了影响因素,制备的聚硅硫酸铁净水用量少、无毒、混凝效果好。     

The fate of iron during the alkali‐activation of synthetic (CaO‐)FeOx‐SiO2 slags: An Fe K‐edge XANES study

Slags from the nonferrous metals industry have great potential to be used as feedstocks for the production of alkali‐activated materials. Until now, however, only very limited information has been available about the structural characteristics of these materials. In the work presented herein, synthetic slags in the CaO–FeO_x–SiO₂ system, representing typical compositions of Fe‐rich slags, and inorganic polymers (IPs) produced from the synthetic slags by activation with alkali silicate solutions have been studied by means of X‐ray absorption near‐edge structure (XANES) spectroscopy at the Fe K‐edge. The iron in the slags was largely Fe²⁺, with an average coordination number of approximately 5 for the iron in the amorphous fraction. The increase in average oxidation number after alkali‐activation was conceptualized as the consequence of slag dissolution and IP precipitation, and employed to calculate the degrees of reaction of the slags. The degree of reaction of the slags increased with increasing amorphous fraction. The iron in the IPs had an average coordination number of approximately 5; thus, IPs produced from the Fe‐rich slags studied here are not Fe‐analogs of aluminosilicate geopolymers, but differ significantly in terms of structure from the latter.     

高岭土尾砂玻璃马赛克的研制

根据高岭土尾砂的矿物工艺特性，采用科学配方和相应的生产工艺技术，以高岭土尾砂为主要原料，成功地研制出尾砂玻璃马赛克，为高岭土的综合利用开辟了新领域。，     

富铁矿渣玻璃的熔制溢液现象及解决

本文介绍了有色金属和黑色金属选矿尾砂、冶金钢渣等富铁矿渣的特点，富铁矿渣玻璃的熔制溢液现象，分析了产生溢液的原因并提出了解决溢液现象的方法。     

电石渣作为石灰质原料的有害成分分析与控制

指出了利用电石渣作为石灰质原料生产水泥时电石渣中有害成分的危害和影响。分析了电石渣中的有害成分,并提出相应的控制措施。