Basic slag was thought by many to be the best grassland fertiliser ever. Weathering of the slag before utilisation can allow some hydration of the free lime to take place so that the potential for expansion is reduced before the slag is used as an aggregate. The basic slag is obtained by the various processes of steel manufacture. In that case, it becomes necessary to know their nature and properties in order to establish whether they are a valuable resource or a liability. Fluxing materials may be added to accelerate the slag formation and the assimilation of additives such as lime. Please choose which format you would like below. Thus the European Standards only specified a test to confirm whether any falling had occurred during cooling. In the basic oxygen and EAF processes, molten metal, and/or scrap, and fluxes (lime (CaO) or dolomitic lime (Cao.MgO)) are placed in the furnace. The metals uptake by the plants is affected by the soil properties. Other terms such as BOS (Basic Oxygen Steelmaking) or BOF (Basic Oxygen Furnace), which have a broader meaning, are also commonly used for this process. These cookies do not store any personal information. Thus any free lime present is normally at a lower level, and less likely to cause any significant expansion of the aggregate. You can also use it to narrow down your search by subject area. (In modern practice there could be around 0.1-0.2% P in the hot metal, which will be reduced to about a tenth of that value, giving a content of about 1% P2O5 in the slag. For the purposes of slag utilisation, the most important point is that several percent of free lime can remain unreacted. DOI: 10.5772/31804. Environmental safeguards are needed with such processes, partly for the dust or slag fibres that may be generated but also because the sulphur in the slag can react to release compounds into the air and water. APPLICATION OF ELECTRIC ARC FURNACE SLAG ... Institute of Civil Engineering, both in Zagreb, have shown that slag can be used for agricultural purposes as inorganic soil enhance, in construction industry as an additive to cement and in civil engineering as an additive for road construction. Strict chemical limits were developed and incorporated into British Standards to guard against this postulated “late falling”. Basic Slag When iron ores contain much phosphorus, its extraction by use of lime gives a by-product in the making of steel that has agricultural value. Among the common historical fluxes are calcium fluoride and certain borates, although a wide range of other materials has been tried at some locations such as red mud from the processing of alumina. Open Hearth slags were used as road aggregate in some countries when that was a major process in the industry. Recycling slags by feeding them back into the process has the attraction of efficiency but there are usually strict limits to the amount that can be recirculated in this way. Heavy rates of application are common. VAT is not charged on printed copies of proceedings. In most commercially traded ores the other elements tend to be present only at much lower levels although there are some sources which can contain significant amounts of other components. The slag can be water- cooled, granulated, or air-cooled. This process, known as “falling”, was common at some plants in the early years of the twentieth century and was found to make the slag unusable as an aggregate. Various other processes such as external desulphurisation of steel may generate significant amounts of slag at some plants but overall they are only a small proportion of the total. However, slags from the earliest processes often have a high FeO content, giving a dense rocky material rich in the minerals wustite and fayalite. Slag with a higher lime/silica ratio is not sufficiently fluid but a lower ratio gives reduced phosphorus removal. €35+ worth of phosphates . 437 1. Since his retirement he has retained an interest in such matters, publishing two papers concerning slag utilisation. Slags from these processes are usually strong and rock-like, with the potential for use as aggregates in a variety of applications. Immediate value of dicalcium phosphate, nitrophosphates, Gafsa rock phosphate basic slag and potassium metaphosphate for barley and ryegrass - Volume 70 Issue 2 - G. E. G. Mattingly, A. Penny This not only caused a loss of confidence in the material but such cases have at times been confused with BOS slag. authors:G G Brown, K F J Thatcherpublished:1967proceedings:96ISBN:978-0-95004-642-6. Basic slag. … Production is usually in an electric arc furnace, and the slag arises from the other components present within the chromite. The IFS is running two webinar programmes – one covering Agronomic topics and the other Technical production. These can reportedly reduce the time required per batch to days or even hours. www.intechopen.com. Phosphorus is normally only present in very small amounts but its profound effect on steel properties means that it receives close scrutiny. DisposalDisposing of this material by dumping would not only be expensive but would also represent a waste of valuable natural resources. As it is, the slag compositions used in modern ironmaking mean that falling slag in the slag pits is now a rare occurrence. In the steelmaking process the impurities in the crude iron are oxidised and together with lime form the slag. Emer Life Sci Res (2019) 5(2): 8-11 9 emergent Life Sciences Research Mamatha et al. (In arid areas, for instance, little weathering will occur unless the slag piles are regularly watered.) This website uses cookies to improve your experience. Slag generated from basic oxygen furnace (BOF) or Linz-Donawitz (LD) converter is one of the recyclable wastes in integrated steel plants. A general discussion . When the British Standards were being replaced by European Standards in the 1990s, he was involved in the drafting of those affecting the utilisation of slags. The calcium contained is in the form of calcium silicate, and reacts with soil acids in a manner similar to ground limestone. Teresa Annunziata Branca and Valentina Colla (March 16th 2012). The ores of the United States usually do not give a slag sufficiently rich in phosphorus to be valuable. For example the Cr and V contents into potatoes … These are sometimes used for specific metallurgical purposes (for instance, to raise the manganese or titanium content of the burden) or for reasons such as local availability and cost. If the crude steel undergoes further secondary steelmaking processes, different … The high total lime content, often over 40%, and the fact that much of this lime content is held by minerals that are reactive under soil conditions, allows some slags to be used as agricultural liming agents. SirRobert Hadfield, Bart., F.R.S. It is mandatory to procure user consent prior to running these cookies on your website. Marl and chalk are soft, impure forms of limestone and are sometimes used as liming materials, as are oyster shells. Application/Distribution/Spreading/Placement, Materials from our webinars on 10 / 11 December are now available to view, Online final event for the 2020 Brian Chambers award is announced, The next IFS webinar is on 10 December, on digital aids, The recordings, slides and written papers from our webinar on aspects of fertilisers from recycled materials are now available, The finalists of the 2020 Brian Chambers Award have been announced, Agri-food workers are the focus of the 2020 Global Fertilizer Day. Basic Slag. 5. and The Chairman Abstract. The basic slag (S1) resulted in the greatest expansion (0.08% at 180 days), while the use of acid slag (S3) significantly reduced the expansion (0.03% at 180 days), neutral slag giving an intermediate value of 0.5% after the same time. 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