Production of lightweight chamotte refractories

Abstract

Lightweight chamotte refractories are produced by plastic forming and semidry pressing, with use of burning-off additions, sawdust and coke, respectively. More effective is semidry pressing in which strong carbon-containing materials, pitch, petroleum, and metallurgical coke, are most suitable. However, lightweight parts produced with coke are distinguished by low strength, caused by the coarse-grained loose structure of the fragments as the result of burning off of the carbon and the irregular form of the coke grains. In addition coke is an energy-consuming material in short supply. Abroad there are produced similar types of lightweight refractories the strength of which is significantly (by about three times) higher than of domestic ones as the result of use as the burning-off additions of polymer materials with a spherical form.These investigations were devoted to establishment of the possibility of use as the burning-off addition of chemical production wastes for production of lightweight parts not inferior in properties to the requirements for type ShKL-1.3 parts to GOST 5040-78.As the original materials KV-2 Vladimirovka kaolin, ShKV-2 chamotte from this kaolin, wastes of the production of polyethylene wax (TU 6-05-361-16-83) not previously used, and wastes from the production of synthetic rubber -crumb rubber from the wastes of type A BS-P rubber (TU 38.103524-87) -were used.The production wastes of polyethylene wax (subsequently wax) are a solid substance with a melting point of 85-100~ and a flash point of about 300~ The crumb rubber from rubber waste, yellowish brown spherical particles, has a specific odor, a flash point of 315~ a spontaneous combustion temperature of 355~ and an ash content of 13.8%. The characteristics of crumb rubber from rubber waste are given in Table 1.The chemical composition of the ash of the crumb rubber from the production waste is (wt. %) 51.2 SiO 2, 0.32 AI203 , 7.08 Fe203, 0.66 TiO2, 7.8 CaO, 17.1 MgO, 0.17 Na20 , 0.31 K20, 2.77 SO3, and Amealc 2.60.The influence of the maximum particle size of the burning-off addition and of the quantity of it and also of the pressing, drying, and firing parameters on the properties of the lightweight specimens was investigated. Cubes with an edge of 50 mm were pressed and on them were determined the apparent density, compressive strength, and shrinkage. The physicomechanical and thermal insulation properties were determined on standard specimens prepared from a normal size brick.The mixture was prepared by mixing of the burning-off addition moistened with commercial lignosulfonate with the refractory material. It should be noted that certain difficulties related to breakup and sifting of the necessary fraction of wax arose. The mechanical action caused softening of it, as the result of which the wax particles stuck to the screens. Therefore for the purpose of hardening the wax it was treated with liquid nitrogen, as the result of which the wax was prepared normally. Investigation of the maximum particle size of burning-off additions show...

Potentialities of the method of burning-off admixtures in production of heat-insulating refractories

“…Various combustible materials may serve as burning-off admixtures [3]. Hardwood sawdust has become the most popular admixture, though its use entails certain manufacturing difficulties.…”