Study of the mineral and phase composition of aluminosilicate refractory ShPDM-45 after service in an aluminum electrolyzer of OAO Zaporozh’e aluminum combine

Abstract

Comprehensive studies have established that ShPD M -45 refractory produced by OAO Zaporozhogneupor exhibits good anticorrosion properties towards the action of electrolysis bath corrosive extraneous components. The degree of degradation of ShPD M -45 refractory after two years of service is 10%. The average concentration of entry of Na g and F tot into ShPD M -45 refractory through hearth blocks with 50% graphite is correspondingly 4.08´10 -4 and 3.32´10 -4 g-mole/day. It is established that ShPD M -45 refractory is a more reliable barrier material than unmolded aluminosilicate mixes. The penetration rate of corrosive components of the electrolysis bath into unmolded aluminosilicate materials is greater by a factor of 10 -30 than for ShPD M -45 refractory. It is shown that the protective function of titanium-containing components and glass phase in an electrolyzer lining develops as a result of forming fluoride, subfluoride and oxyfluoride titanium compounds. Industrial approval of ShPD M -45 refractory under OAO Zaporozhe Aluminum Combine conditions has shown that it exhibits good operating properties in electrolyzers with hearth blocks with 50% graphite.The service life of domestic and Russian electrolyzers is significantly less than for the leading overseas enterprises. One of the reasons that affect the service life of an electrolyzer is the quality of refractory materials for lining the electrolyzer socle. Refractories available in the domestic market in service and mechanical properties, operating stability under conditions of a corrosive medium, are surpassed by materials recommended by overseas firms for use in aluminum electrolyzers.Participants of the exhibition Aluminii-2007/ALUMICO, meetings on problems of material quality, repeatedly noted the importance of quality and a requirement for the combined effort of enterprises, producers and users of refractories in further development directed towards improving the quality and competitive capacity of production. An important area is the search for and development of refractory materials corresponding to contemporary requirements for electrolytic production of aluminum.Operating experience indicates that the most popular barrier materials remain aluminosilicate refractories [1]. On the basis of work given in publications [2 -5] and according to the resolution of the Technical Council of the Zaporozhe Aluminum Combine for replacement of refractory ShA-5, that exhibits low operating indices, the refractory lining used was chamotte dense blast-furnace objects grade ShPD M -45 with additions of mullite-corundum chamotte. The characteristics and service properties of objects are provided in articles [6 -9].The technical and economic indices of electrolyzer operation with hearth blocks with 50% graphite used in lining a cathode with ShPD M -45 refractory have improved alongside other factors. Electric energy consumption for one ton of aluminum and the average voltage decreased by 4.91 and 1.81% respectively. The current efficiency increased b 1%. It was of inte...