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Refractories for Aluminium: Electrolysis and the Cast Houseкнига
- Автор: Yurkov Andrey
- Год издания: 2015
- Место издания: Springer International Publishing AG Heidelberg New York Dordrecht London
- Объём: 254 страниц (12,2 печатных листов)
- ISBN: 978-3-319-11442-5; 978-3-319-11442-2
- Монография
- DOI: 10.1007/978-3-319-11442-2
- Аннотация: The book includes 4 chapters: 1.The properties of refractory and heat insulation materials 2.Refractories and carbon cathode materials for aluminium reduction cells 3.Refractories and heat insulation materials for the cast house. 4.Refractories for the anode baking furnaces .The processes during service. Interactions The emphasis of the chapter “The properties of refractory and heat insulation materials” is on application of specific refractory, heat insulation and carbon cathode materials in Aluminium industry. The physical and chemical origin of properties are given together with ISO, ASTM and DIN standards to measure these properties of materials. There are the practical examples , proving the importance of the properties of refractory and carbon cathode materials for direct use in reduction cells and melting and holding furnaces for Aluminium. Specific questions, that arise in practical work between the producers of the materials and the metallurgists , using these materials, are underlined. The example is the relativity of the thermal conductivity measurements, depending on the principle of measurement, standard and the equipment. However this relativity may seriously influence the thermal balance of the holding furnace and the consequent performance and the service life time. The chapter describes the elements of the reduction process, organization of reduction shops at smelters, the typical designs and constructions of reduction cells, (with emphasis on the basic heat balance of Hall-Herault reduction process), the pre heating and the start up of the reduction cells. The main types of failures and shut downs of the reduction cells are described together with the principles of the dry autopsies for the investigation of the reasons for shut downs. The main materials for the lining of the reduction cells: - Carbon cathode blocks and carbon ramming pastes; - Carbon and silicon carbide side lining materials and ramming pastes, concretes and mortars for the installation of them; - Refractory barrier layer bricks and dry barrier mixtures; - Heat insulation materials are described in the following sequence: - The purpose of the material and its basic properties, grades of materials; - Raw materials for processing; - Installation in the reduction cell; - Elements of technology and processing, equipment, structure of the materials; - The typical defects of materials; - The behavior in reduction cell during the service in connection with physical changes and chemical interactions. Critical pore sizes for the penetration of electrolyte. - Testing and characterization. The chapter briefly gives idea of organization of the cast house at aluminium smelter and the secondary aluminium plant. The main metallurgical devices requiring refractories are melting and holding furnaces, some words are said about ladles and launders for the transportation of molten Aluminium to the degassing units and filter boxes to the casting machines. Typical compositions of refractories and heat insulation materials are given. The reaction of Aluminium and silicon oxide and silicon oxide containing compounds may take place above the melting point of Aluminium. Magnesium – the most frequent component of Aluminium alloys, reacts with alumina. The mechanism of the degradation of alumina silica refractories in contact with molten aluminium and AL-Mg alloys is in negative volume effect of reactions between the components of alumina silica refractories with molten aluminium and magnesium, that prevents the formation of protective layer and opens way to penetration of the melt inside the lining and increasing of the thermal conductivity, that in its turn shifts the freezing point of the melt more deep inside the lining to the heat insulation layer. The reactions with positive volume effect may cause cracking inside the structure of refractories, forming passes to following penetration of the melt. The volume effect of reactions on the surface of the contact of refractories and the melt and inside the pores differs. Thermodynamically stable substances in contact with molten Aluminium, that might be the components of refractories, are sufficiently costly comparing with modified alumina silica refractories. The anti wetting additives are described in connection with the wetting behavior and critical pore sizes for the penetration of aluminium melt inside the refractory and the transformation of anti wetting additives with following decreasing of contact wetting angles and anti wetting behavior. The main principles of lining constructions and lining performance are discussed together with heating regimes for linings from bricks and castables.
- Добавил в систему: Юрков Андрей Львович