Prospects of the use of torch guniting in the copper and nickel industry

Abstract

Successful experience accumulated in the steel industry on the introduction and use of torch guniting as a method of hot repair of metallurgical equipment linings and above all else of steel melting converters has created good experience for its use in nonferrous metallurgy.However, the first experience in the use of torch guniting for repair of the tuyere belt of horizontal converters at South Ural Nickel Plant did not provide positive results [i]. This indicates that direct transfer of experience in the steel industry without taking into consideration the specific operating conditions of nonferrous metallurgical equipment is not promising.The basic reason for the low effectiveness of torch guniting of nickel industry converters was the relatively low temperature of the converter process of nickel mattes (< 1500~ and consequently the low lining temperature before application of the coating, which is approximately 400~ lower than the temperature of a steel melting converter after pouring of the metal.By operating conditions and applicability of torch guniting copper and nickel production equipment may be conditionally divided into a number of basic groups.The first group includes the 30-ton vertical converters for processing of ferronickel at Pobyzhskoe and Buruktal'sk Nickel Plants. They are almost completely similar to steel melting converters and consequently guniting methods developed in the steel industry may be applied to them. However, as calculations showed, as the result of the low scale of production and the relatively long life of the lining in these units the use of torch guniting for repair of them is economically undesirable.Another group of equipment is electric arc furnaces for melting of anodic mickel or copper, which are similar to steel melting electric furnaces. For these furnaces local wear of the lining as the result of nonuniform distribution of power between the electrodes is most characteristic. The possibility of repairing local wear of their lining involves the necessity of development of a method of directed torch guniting and the appropriate equipment, Vertical converters for melting of sulfide copper and copper-nickel concentrates are the third group and are similar to vertical steel melting converters in their operating characteristics (batch process) and temperature of the production operation (above 1700~The difference is in the properties of the molten materials processed in them. In particular, molten sulfides at above 1700~ possess a high penetrating capicity and quite easily fill cracks, irregularities, and voids in the refractory lining. The influence of this factor on the effectiveness of guniting and the adhesion strength of the gunited layer with the lining have not been studied and the problem includes evaluation of the effectiveness of preliminary treatment of the surface to be repaired with a high temperature flame for the purpose of melting out of the sulfides, removal of the slag crust from the surface, and heating of the lining before application of the coating.