Recycling and environmental issues of metallurgical slags and salt fluxes (original) (raw)
Related papers
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.
Review on Novel Application of Slag Fluxes and Salts in Metallurgical Industry
The cost of processing recycling slag is less than the purchase of new flux from the manufacturer .Many times this can amount to saving 50 percent or greater. In order to continue effective use of slag in the future, we realize the necessity of development for new applications and market reclamation to create the stable demand. Therefore the needs of recycling slag waste cannot be over emphasized for sustainable environmental, economic and industrial growth. The present paper summarizes the current application of slag the ferrous and non-ferrous slag, as well as recycling of salt fluxes in secondary smelting production. Fluxes often are selected to make slag to perform different functions at different stages of a process prior to final melting, hence Slag chemistries are adjusted to provide the proper melting point, viscosity, surface tension, conductivity, specific heat, density, or chemical properties for the particular metallurgical process.
Processing and utilization of metallurgical slag
Production Engineering Archives
Metallurgy and foundry industry create a huge amount of slags that are by-products in production of pig iron, steel and cast iron. Slag is produced in a very large amount in pyrometallurgical processes, and is a huge source of waste if not properly recycled and utilized. With rapid growth of industrialization, land available for land-filling of large quantity of metallurgical slag is being reduced all over the world and disposal cost is becoming increasingly higher. Metallurgical slag from different metallurgical processes treated and utilized in different ways based on different slag characteristics. The most economic and efficient option for reducing metallurgical waste is through recycling, which is a significant contribution to saving natural resources and reducing CO 2 emissions. Characteristic of slags as well as its treatment and utilization are given in the paper. Slag from pig iron and steel production is used most frequently in building industry. From experiments using blast furnace slag and granulated blast furnace slag as gravel, and water glass as binder it can be concluded that that the best resultsthe best values of compression strength and tensile strength were reached by using of 18% of water glass as a solidification activating agent. According to cubic compression strength, mixture from 50% blast furnace gravel, 50% granulated blast furnace slag and 18% water glass falls into C35/45 class of concrete. Such concrete also fulfils strength requirements for road concrete, moreover, it even exceeds them considerably and, therefore, it can find an application in construction of road communications or in production of concrete slabs.
While the usage of blast furnace slag is well established in the area of cement making, recycling of steelmaking slag is still a challenging task. About 150-180 kg steelmaking slag is generated per ton of steel depending upon the quality of hot metal. At present less than 50% of the slag is used in road making, construction and sinter making, and the remainder is dumped. This slag may find application in refining of steel or iron making processes due to its high metal value and lime content provided phosphorus (P 2 O 5 =2-4 %) is removed from the slag. Amongst the different methods tried for phosphorus removal, chemical process has been considered most suitable because it utilizes the energy content of the slag The results have shown 70-75% recovery of metallic values from slag whereas phosphorus removal varied in the range of 65-95%. This paper examines the effect of recycling of resultant slag with different levels of phosphorus on the final content of phosphorus of hot metal and their consequences on the process economics.
Steel Slag and Waste Management
Key Engineering Materials, 2004
Steel slag is a waste material produced during the process of steel making. For many years, a large amount of steel slag was deposited in slag storing yards, occupied farmland, silted rivers and polluted the environment. Many steel plants in the world have already taken up innovative waste recycling technologies with the ultimate objective of 100% recycling. There is much to be improved in using steel slags in Turkey. The comprehensive utilization of steel slag is important for environmental protection and resource reuse in Turkey and abroad. It is clear that steel slag must meet appropriate performance specifications before being adopted for a particular application. The aim of the present research was to characterize steel slag from a Turkish company and compare to the steel slags from various countries. Application possibilities have been sought by comparing properties to the other steel slags.
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.
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.
Review on the innovative uses of steel slag for waste minimization
Journal of Material Cycles and Waste Management, 2018
Piles of steel slag, a solid waste generated from the iron and steel industry, could be seen due to no utility found for the past century. Steel slag has now gained much attention because of its new applications. The properties of slag greatly influence its use and thus had got varied applications. The chemical composition of steel slag varies as the mineral composition of raw material such as iron ore and limestone varies. This paper reviews the characteristics of steel slag and its usage. The paper reviews recent developments in well-known applications to the steel slag such as aggregate in bituminous mixes, cement ingredient, concrete aggregate, antiskid aggregate, and rail road ballast. This paper also reviews novel uses such as mechanomutable asphalt binders, building material, green artificial reefs, thermal insulator, catalyst and ceramic Ingredient. The review is also done on utilization of solid waste for waste management by the novel methods like landfill daily cover material, sand capping, carbon sequestration, water treatment and solid waste management. Review also shows recovery of pure calcium carbonate and heavy metals from slag, providing opportunity for revenue generation. Steel slag once traded as free to use by steel industries is now sold in the market at some price. Its utilization is of great economic significance as it also contributes to the reduction of solid waste.
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