On Expediency of the Preliminary Heat Treatment for Liquid-Phase Reduction of Waste Steelmaking Slag (original) (raw)
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Innovative approach to recovery of iron from steelmaking slags
Ironmaking & Steelmaking, 2010
The present work is aimed at the development of a new sustainable method for the utilisation of valuable elements from the steelmaking slag. In the framework of the innovative concept earlier proposed by the authors for utilisation of steelmaking slags, oxidation of iron mono-oxide in the liquid slag was studied experimentally in different atmospheres and in the temperature range 1623-1823 K using thermogravimetry technique. Synthetic (binary and ternary slag system) as well as industrial steelmaking slags were used in the experiments. Analysis of the reaction products was carried out using X-ray diffraction method. A possibility to transform the nonmagnetic iron bearing compounds to magnetite in the steelmaking slag by oxidation has been confirmed.
Reduction of steel-making slags for recovery of valuable metals and oxide materials
Scandinavian Journal of Metallurgy, 2003
Extensive researches on slag reduction for recovery of valuable metals and oxide materials from metallurgical slags and other wastes using a DC furnace with a hollow electrode have been conducted in 2 major EU projects with close cooperation between MEFOS, FEhS and CRM. Steel slags and other residues were introduced into the reactor through the hollow electrode to the hot plasma. The materials were melted, reduced and mixed. The final products were a metal product, a slag product with targeted chemical composition and a dust fraction with a high content of ZnO. Different steel-making slags and residues including BOF slag with low and high V-content as well as EAF and AOD slags from stainless steel production, EAF dust, oily millscale, hydroxide sludge, BOF and BF dust have been treated. The slag products include a metallurgical powder for desulfurization of steel, hydraulic binder and slag stones for construction applications. The metals obtained are rich in Fe, Mn, V and Cr depending on the treated slag and residues. The environmental compatibility and mechanical properties of the slags have been improved after slag reduction.
STUDY OF IRON AND STEEL SLAG AS A PRODUCT WITH RESPECT TO PHYSICAL-CHEMICAL PROPERTIES
International Journal of Advanced Engineering Technology, 2017
This paper review the generation of slag from an integrated steel plant; focusing on, slag generated in blast furnace during process of iron making and through EAF / BOF during process of steel making .The slag generated from BF and EAF/BOF are having different characteristic. The different type of slag having different chemical and physical properties, this depends on the chemical properties of input raw material charged in process of iron/steel making and this slag used in different process as raw material. Blast Furnace slag production ranges from about 220 to 370 kilograms per metric ton of pig iron produced; although lower grade ores may yield much higher slag fractions. Steel making process in electric arc furnaces generates up to 15 % of slag, which is, based on its properties, classified as non-hazardous waste. Disposal of such material requires large surfaces and it is rather unfavorable in economic terms.
A physico-chemical separation process for upgrading iron from waste copper slag
International Journal of Mineral Processing, 2013
A large amount of waste copper slag containing about 35-45 wt.% iron is generated every year from pyrometallurgical processes for producing copper from copper concentrate. Recovery of iron from the waste copper slag is of great interest for comprehensive use of mineral resource and reduction of environmental problems. In this study, a method for upgrading iron from the waste copper slag discharged as an industrial waste has been developed. The process first crushes the waste copper slag between 150 and 203 μm, followed by reduction reaction at 1250°C for 1.5 h. And then, the resulting material is again crushed to 75-104 μm, followed by dry magnetic separation. Using the developed process, a magnetic product containing more than 65 wt.% iron was obtained from magnetic separation under a magnetic field strength of 0.03 T for the waste copper slag treated by reduction reaction. At the same conditions, the percentage recovery of iron was over 85%. It was also found that iron in the magnetic product mainly exists in iron metal, iron carbide, and iron oxides.
Journal of Mining and Metallurgy, Section B: Metallurgy, 2013
Sustainable development of steelmaking requires solving a number of environmental problems. Economically feasible and environmentally friendly recycling of slag wastes is of special concern. Research of the team representing National Metallurgical Academy of Ukraine, Royal Institute of Technology, Carnegie Mellon University and URS Corp revealed a possibility of the controlled phase transformations in the liquid silicate melts followed by formation of the magnetically susceptible compounds. This approach enables selective recovery of metal values from slag. In this paper, the results obtained and further research directions are discussed. A possibility to exploit physical properties of the transition metals, typical for the metallurgical slags (such as Fe, Mn, V and others), and corresponding specific properties of their compounds, such as non-stoichiometry, mixed valency, pseudomorphosis, thermodynamic stability etc, in production of value-added materials from slag wastes is discussed. The results of the studies of thermodynamics and kinetics of oxidation in slags followed by phase transformation with binary, ternary and complex oxides under various physicochemical conditions are discussed in the view of their application for production of the materials with predefined physical properties. Peculiarities of precipitation in slags with various basicities are analysed and demonstrate capacity of the proposed approach in the production of the material with a given structure and size -for example, nano-sized crystals with structure of spinel. The approaches towards industrial realization of the developed method are also discussed.
The utilization of metallurgical slags by means of oxidation in the liquid state
2012
In the present contribution, the concept of the slag utilization based on transformation of non-magnetic wüstite (FeO) to magnetic magnetite (Fe3O4) using an oxidizing atmosphere is proposed. In order to verify the feasibility of the proposed way of slag utilization, experiments were performed on the ternary CaO-FeO-SiO2 and quaternary CaO-FeO-SiO2-MnO slag systems, accompanied by thermodynamic and kinetic modelling. The kinetic studies of the oxidation of FeO in liquid synthetic slags were carried out using thermogravimetric technique (TGA) and nucleation / crystal growth of the precipitated phase by confocal scanning laser microscopy (CSLM). Air was used as an oxidizing atmosphere. TGA results indicated that, during the first 10-15 min of oxidation, 80-90% of FeO in the slag was oxidized. CSLM images showed that crystals grew and agglomerated on the liquid slag surface, reaching 50 μm in length in some cases. Different shapes of crystals were observed at different experimental tem...
Application of Physical and Chemical Methods for Processing Slags of Copper Production
International Journal of Advanced Research in Science, Engineering and Technology, 2019
The article deals with the problem of reducing copper losses from waste slags. A comprehensive solution to the problem with the use of physicochemical methods of influence on the melt is proposed. It is shown that the success of the depletion process depends on the sulfiding of oxidized copper compounds, the reduction of magnetite in the slag to wustite, and the creation of conditions for the coalescence of fine drops of matte. Creating these conditions makes it possible to reduce the residual concentration of copper to the level applied. This can be obtained poor matte, which is processed by pouring them into a melting furnace. Depleted slag is waste products and can be implemented in the construction industry. In fact, this makes it possible to abandon the creation of slag heaps.
Overview of Steel Slag Application and Utilization
MATEC Web of Conferences, 2016
Significant quantities of steel slag are generated as waste material or byproduct every day from steel industries. Slag is produced from different types of furnaces with different operating conditions. Slag contains Ferrous Oxide, Calcium Oxide, Silica etc. Physical and chemical properties of slag are affected by different methods of slag solidification such as air cooled, steam, and injection of additives. Several material characterization methods, such as X-ray Diffraction (XRD), Scanned Electron Microscopy (SEM) and Inductive Coupled Plasma (ICP-OES) are used to determine elemental composition in the steel slag. Therefore, slags can become one of the promising materials in various applications such as in transportation industry, construction, cement production, waste water and water treatment. The various applications of steel slag indicate that it can be reused and utilized rather than being disposed to the landfill. This paper presents a review of its applications and utilization
Treatments and Recycling of Metallurgical Slags
Recovery and Utilization of Metallurgical Solid Waste [Working Title], 2018
Steelmaking plants continuously strive to reduce the environmental load in the steelmaking process, resulting in the recycling of energy, water, and other byproducts. In this chapter, techniques for the treatment and recycling of metallurgical slags are described. Metallurgical slags are considered secondary raw materials and are used or added during the process to improve steelmaking practice. Steelmaking slag added into ladle slags makes it possible to minimize slag line wear. BOF-converter slags are also applied in buildup, foaming, or slag splashing practices carried out to prolong the lifespan of refractory lining. Also, EAF slags are commonly used to avoid refractory wear and decrease energy consumption. It is known that cement concrete is one of the most common building materials. Blast furnace crystallized slags are used in cement production, in different percentages. In this sense, understanding the properties of slags is a prerequisite to apply them in different functions. This chapter deals with the measurement and modeling of thermochemical properties of slags, thermophysical properties, and interproperty correlations. Different experimental tests applied in slag characterization are also detailed.