Current state of steelmaking slag processing

In the present work, the properties and composition of steelmaking slag are assessed by analysing existing processing methods, including desulfurisation and dephosphorisation. The atomic absorption and optical emission methods were used to study the chemical composition of slag samples, and metallographic analysis was used to study their microstructure. Major approaches to processing slags applied in Russia and abroad were studied. It was shown that steelmaking slags are neutralised and treated by various methods and subsequently applied in construction and road industries, while the obtained phosphorus-containing products are used in agriculture instead of superphosphate. In addition, these products reduce lime consumption and improve slag formation in steelmaking. The key factor hampering reusing electric steelmaking and converter slags for metal refining is shown to be the presence of phosphorus. The chemical composition of slag samples from the electric steelmaking production was analysed; the iron content amounted to 33.2 wt%, calcium – 19.15 wt%, phosphorus – 0.33 wt% and silicon – 5.39 wt%. Iron is present in the oxidised form (FeO, Fe2O3 and Fe3O4), silicon and calcium in the form of dicalcium silicate (2CaO ∙ SiO2 ), phosphorus in the form of calcium silicophosphate having complex composition – Ca2(SiO4)6(Ca3(PO4)2. Phosphorus is fed to the melting units with gangue minerals, agglomerate, ore and fluxes. When the slags are reused, phosphorus returns to the metal, thus contaminating the final product. Possible methods for extracting phosphorus from steelmaking slags include magnetic and electrostatic separation, gravity and flotation concentration, as well as hydrometallurgical processing.

On possibility of using silicomanganese slag and ladle electric steelmaking slag in manufacture of welding fluxes

Analysis of the existing trends in development of technologies for production of welding and surfacing fluxes showed that one of the actively developing areas is the production of fluxes using man-made waste (including metallurgical one) as components of the initial charge. This is due to the fact that the slag waste of metallurgical production contains a large amount of manganese and silicon, which in turn are the basis in welding fluxes. Within the framework of this direction development, the article describes principal possibility and efficiency of using materials based on ladle electric steelmaking slag from JSC “EVRAZ United West Siberian Metallurgical Combine” and slag produced by silicomanganese from LLC “West Siberian Electrometallurgical Plant” in the charge for production of fluxes used in the surfacing of rolling rolls. All the laboratory tests were made using the equipment of the scientific and production center “Welding Processes and Technologies”. For surfacing steel samples, the authors used a flux additive obtained by mixing ladle electric steelmaking slag of a fraction less than 0.2 mm with liquid sodium glass in a ratio of 62 and 38 %. The resulting flux additive was mixed with slag from the production of silicomanganese of a fraction of 0.45 - 2.50 mm in various ratios. Studies of the chemical composition (by the spectral method) and metallographic studies of the deposited layer revealed a tendency to an increase in sulfur content and in contamination with non-metallic inclusions in it with an increase in content of the flux additive in the charge of more than 20 %. According to the results of visual quality control of the deposited layer macrostructure, the absence of defects was established with a flux additive content of up to 30 %.

Investigation of the processes of dust processing gas cleaning of steelmaking industries

The article deals with the issues of processing of dust from electric steelmaking production by the method of thermodynamic extraction of iron, zinc and lead in order to reduce the environmental impact and increase the resource base of the industry. The paper presents various methods of zinc extraction from dust and gas purification, thermodynamic calculation of the decomposition and reclaiming of zinc ferrite.

Fuel-melting aggregate “MAGMA-1” for processing wastes of electric steelmaking

Toughening of ecological requirements to metallurgical production and economic factors, stipulated by competitiveness at the metal products market, increased actuality of utilization of slags, sludges and dust, obtained in steelmaking. It was shown, that from the economic point of view, processing of slags obtained at operation of modern ultra-powerful electric arc furnaces (EAF), is the item of highest interest. At present, their processing is restricted often by maximum possible recovery of metallic inclusions. At that the problem of utilization slag remains, dust and sludges remains unsolved. A pyrometallurgical method of electric steelmaking slags processing in EAF was considered. The process involves application of liquid phase reducing of metal oxides and correction of slag composition aimed at obtaining cast slag marketable products and clinker for cement industry. Data of test heats for slags utilization at the 5-ton EAF presented. The proposed technology enables to make industrial scale processing of slags with obtaining cast iron and melted clinker. Taking into consideration that EAF coefficient of efficiency, accounting fuel consumption for electrical energy obtaining is not high and is 23–24%, it was proposed to do slags processing in fuel-melting aggregates, in which the efficiency of primary energy utilization is higher (efficiency coefficient is 25–40%). The firm OJSC NTP “Akont” developed a technical project of a fuel-melting aggregate “MAGMA-1” for processing electric steelmaking slags. Its basic technical data and performance indices presented. It was shown that additional decrease of fuel consumption can be provided at utilization of liquid slag tapped out of EAF in a course of a heat, as well as at charge heating in a tubular rotating heater by waste gases.

Techno-Genic Fillers in the Composition of Modern Polymer Paints

The article shows that techno-genic fillers, based on slag of electrometallurgical production, can be used as fillers for water-dispersion paints, based on polymer composition. For these purposes, it is necessary to modify the slag particles, in order to increase its hydrophobic property. The article examines the effect of the mass of the additive of techno-genic filler, based on the modified slag of the electrometallurgical plant, on the properties of the resulting paint. A water-dispersed acrylic composition, containing stearic acid-modified slag of electric steelmaking production as a filler, has been developed. The composition has high uniformity, is more heat-resistant and water-resistant, a high hiding power and viscosity, and corresponds to modern analogues.

Performance and Durability of Porous Asphalt Mixtures Manufactured Exclusively with Electric Steel Slags

Electric arc furnace slag (EAFS) and ladle furnace slag (LFS) are by-products of the electric steelmaking sector with suitable properties for use in bituminous mixtures as both coarse and fine aggregates, respectively. In this research, the production of a porous asphalt mixture with an aggregate skeleton consisting exclusively of electric steelmaking slags (using neither natural aggregates nor fillers) is explored. The test program examines the asphalt mixtures in terms of their mechanical performance (abrasion loss and indirect tensile strength), durability (cold abrasion loss, aging, and long-term behavior), water sensitivity, skid and rutting resistance, and permeability. The results of the slag-mixes are compared with a standard mix, manufactured with siliceous aggregates and cement as filler. The porous mixes manufactured with the slags provided similar results to the conventional standard mixtures. Some issues were noted in relation to compaction difficulties and the higher void contents of the slag mixtures, which reduced their resistance to raveling. Other features linked to permeability and skid resistance were largely improved, suggesting that these mixtures are especially suitable for permeable pavements in rainy regions. In conclusion, a porous asphalt mixture was produced with 100% slag aggregates that met current standards for long-lasting and environmentally friendly mixtures.