A corundum hydraulically hardening compound with addition of titanium slag for steel ladle vacuum degassers

Abstract

In circulating and batch vacuum degassers for steel the outer linings of the intake and return nozzles made of MKN-94 corundum hydraulically hardening compound produced by Borovichi Refractory Compound [i] are subjected to significant wear in service.In [2] a corundum hydraulically hardening compound with addition of baddeleyite making it possible to increase the mechanical strength of the outer lining of the nozzles, to reduce its open porosity, and reduce the rate of wear in service is described.According to [i] the increase in mechanical strength and decrease in open porosity of concrete of corundum hydraulically hardening compound may also be obtained by addition to its composition of titanium dioxide, which promotes sintering of the concrete at the service temperature (1600 ~ but at the same time significant linear shrinkage (1.7%) is observed. The use in preparation of the corundum compound of baddeleyite and titanium dioxide additions leads to an increase in cost of it.Taking this into consideration in this work to improve the physicotechnical characteristics of corundum compound, addition to its composition as the titanium-containing addition of titanium slag, the cost of which does not exceed the cost of fused corundum, in place of a portion of which it is added in preparation of the compound, was tested. The high titanium dioxide content in the titanium slag (more than 80%) provided a basis for expecting that addition of it to the corundum compound will promote an increase in mechanical strength and a reduction in porosity of the concrete in heat treatment, and the presence in the titanium slag of impurities increasing in volume at high temperatures made it possible to expect less shrinkage of the concrete in service than with the addition of pure titanium dioxide.In conducting the investigations fused corundum to TU 14-8-384-81, Talyum high-alumina cement to TU 6-03-339-78 produced in the experimental technology area of All-Union Refractory Institute, and titanium slag to TU 48-10-31-78 were used as the original materials. The chemical analyses of the fused corundum and the high-alumina cement are similar to those described in [2]. The chemical analysis of the titanium slag is* 84.5 TiO=, 4.8 FeO, 5.9 SiO=, 2.1 AI=03, 0.3 MgO, 1.0 Cr=03, and 0.5 MnO and the growth in firing 2.2.For the laboratory investigations specimens were prepared of corundum hydraulically hardening compound (particle size 7-0 ~Lm) with additions of 2 and 5% finely ground titanium slag. For comparison concrete specimens of MKN-94 production compound were also prepared under the same conditions. To prepare the specimens the components of the compounds were mixed, moistened with 10% water, rammed into split metal dies, and held in a humid atmosphere. The concrete specimens had the shapes of cubes with 30-mm edges and of 36-mm-diameter 50-mmhigh cylinders.After hardening for 3 days from the moment of mixing the compressive strengths of the specimens were determined. A portion of the specimens of each composition was fired in a batch...