The development and introduction of compositions of heat-resistant concretes and of a new design and method of preparation of the lining of hot tops

Abstract

One of the most laborious operations in steel melting production is preparation of the mold trains for reception of the heat and, in particular, preparation and repair of the hot top linings.At Makeevka Metallurgical Combine the hot top linings are traditionally prepared from chamotte brick which, as is known, involves large expenditures of manual labor and complexity in development of a lining of the optimum configuration providing effective thermal operation of the top portion of the ingot.A mechanized method of preparation of hot top linings of heat-resistant concrete was introduced earlier at Petrovskii Dnepropetrovsk Metallurgical Plant [1][2][3][4] and Dzerzhinskii Dnepr Metallurgical Combine [5]. The linings are ll0-120-mm-thick single-layer ones.Experience in use of the new method of preparation of hot tops showed its advantages in reducing expenditures of manual labor, increasing service life, and improving the thermal insulating capacity of the lining. In addition, as the result of the significant strength of the heat-resistant concrete such a lining is very difficult to remove from the hot top housing after wear. Removal of the worn lining with the use of the pneumatic impact machine developed for this purpose [4,5] requires large expenditures of time, is accompanied with loud noise, and reduces the life of the housing. The operation of removal of the worn lining has become a bottle-neck in the production operation of preparation of the hot tops. In addition, making the lining a single layer one of dense structure heat resistant concrete, while solving the problem of increasing the service life of the lining, limits the possibilities of further increasing its thermal insulation capacity and reducing loss of metal to the cut-back.In developing a mechanized method of preparation of hot top linings at Makeevka Metallurgical Combine we aimed at developing a hot top with a two-layer lining consisting of permanent and working layers. The surface of contact of the working and permanent layers was made expanding toward the top of the hot top [6]. The design of the hot top with a two-layer lining of heat resistant concrete is shown in Fig. i. Making of the surface of contact of the lining expanding toward the top of the hot top makes it possible to remove the working layer of the lining after wear of it (by shifting it relative to the permanent) relatively simply and without disturbing the permanent layer and makes it possible to use a light and more effective thermal insulation heat-resistant concrete for preparation of the permanent layer.The working surface of the hot top is made pyramidal with rounded angles, which in comparison with a hot top lined with brick made it possible to reduce the volume of metal in the hot top from 149.65 to 140.01 dm 3, the area of the pool of metal from 25.95 to 22.78 dm =, and the heat-transmitting side surface of the lining from 93.07 to 88.74 dm =.Heat-resistant concretes, the compositions of which are shown in Table i, were used for preparation of the two-layer lining. The ...