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Refractories Definition & Classification Tina Stendal Svendsen Product Manager

Refractories Definition & Classification Tina Stendal Svendsen Product Manager. Definition of Refractory. “ non-metallic ceramic material or product whose chemical and physical properties allow it to be used in a high temperature environment”. Application of Refractory

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Refractories Definition & Classification Tina Stendal Svendsen Product Manager

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  1. Refractories Definition & Classification Tina Stendal Svendsen Product Manager

  2. Definition of Refractory “non-metallic ceramic material or product whose chemical and physical properties allow it to be used in a high temperature environment”

  3. Application of Refractory Lining of plants for thermal processing (melting, firing and heat-treatment furnaces) e.g.: • Iron and steel • Cement and lime • Glass and ceramics • Chemical and petrochemical • Heat- and power (waste and biomass) Heat-insulation Functional products: shaped products with an additional function during service

  4. Classification due to product type

  5. Classification due to bondtype and cement content

  6. Classificationaccording to type of chemicalcomposition Focus on Alumina-Silicaterefractory products basedon: • Al2O3 (alumina) • SiO2 (sillica) The variants of alumina-silicacastablesareformulated by: • Differentamounts of Al2O3 and SiO2 in rawmaterials • Differentcrystalstructures of rawmaterials • Different properties of rawmaterials • Grainsize distribution and matrix products

  7. Composition of denserefractorycastables Aggregates(> 45 μm) 65-75% • Croase; build the foundation of the castable • Fine; fill the voidsbetween the croaseaggregates Matrix products (< 45 μm) 25-35% • Fillthe micronsizevoids, affectsworkability and strength • Binders; hold castabletogetheruntilthermalsinteringoccurs • Additives; reduceswater or controlsetting time

  8. Rawmaterialscharacterization • Chamotte (calcinedfireclay): 30-45% Al2O3 Alkali resistance • Andalusite: 50-60% Al2O3 Shockresistance • Bauxite: 80-90% Al2O3Abrasionresistance • Corrundum (alumina): 99% Al2O3 High refractoriness • Synteticmullite (calcinedbauxiticclay): 60-80% Al2O3 Strength • Siliconcarbide: SiCHigh thermalconductivity

  9. High qualityrefractoryrawmaterials: Are subjected to Calcination (minerals fired at 1400-2000°C) • Reduces the amount of impurities • Low porosity • High density • Chemically stable • Increasedrefractoriness Low iron (Fe2O3) content (minimize the risk of CO-attack) Low alkali content(minimize the formation of low-melting-temp. glasses) Be aware of recycledmaterials!

  10. Summary • Refractorymaterialscanbeclassifiedaccording to e.g. type, cement content, application/installation technique and the mainrawmaterial • Wewillfocus on Alumina-Silicatecastables • Densecastablescontainsapprox. 70% aggregates and 30% matrix products • The variants of alumina-silicatecastablesareachieved by a diversity of differentrawmaterials with different properties • Bothnatural minerals and calcined minerals areused • Fractions (and optimal particle distribution) areobtained by crushing, sieving and grinding/milling • High qualityrawmaterials performs better!

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