The growing intensification of the ~echnological processes in metallurgical and other industries is causing greater demands to be placed on refractories with regard to strength, density, deformation properties, and corrosion resistance to various corrosive agents.This article presents the results of the development and mastering at the Belokamensk Firebrick Factory of a technology for making high-quality kaolin refractories based on relatively pure Polozhe kaolin PLK-0 and chamotte ShKN-1 made from Novoselitsk kaolin. The method was developed on the basis of the known technological method of obtaining high-chamotte refractories using a mixture of combined-grind chamotte and binder.Laboratory studies were first made to determine the optimum quality of kaolin and the mixture of combined-grind material in the batch, and also the firing temperature for the products.The chemical compositions of the materials are shown in Table 1. We studied the sintering of Polozhe kaolin to establish the approximate firing temperature. It was found that the greatest densification occurs at 1450-1500~ (Fig. 1).The technological trials to select the optimum parameters were made on laboratory specimens of diameter 36 and height 50 mm. Studies showed that the content of Polozhe kaolin and combined-grind mixture in the body considerably affects the properties of the specimens (Figs. 2, 3). The maximum density is shown by specimens containing 10-12% Polozhe kaolin. The fabrication pressure in this case should be not less than 70 MPa.In accordance with the data for the sintering of Polozhe kaolin, the specimens were fired at 1500~ simultaneously, we tested them by firing at 1450 ~ and 1550~The properties of the fired specimens bore a direct relationship with the firing temperature.With the optimum contents of Polozhe kaolin and combined-grind mixture in the batch and using a pressure of 70 MPa and a firing temperature of 1500~ we obtained specimens with the following properties: content of A1203, 44.8%; open porosity, 15-20%; apparent density, 2.30-2.35 g/cmS; coefficient of gas permeability, 4nPM; compressive strength in the cold state 80-100 MPa, at 800~ 120 MPa, at 1000~ 146 Pa; after-contraction at 1450~ 0.1%, refractoriness 1780~ temperature of initial softening under a load of 0.2 MPa, 1580~ creep when tested for 8 h: at 1300~ and a load of 0.2 MPa 0.7%; at 1200~ and a load of 1 MPa 0.4%; at 1100~ and a load of 1MPa no deformation was noted in the specimens.
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