Pore Structure Regulation in Refractory Grog with Alumina Content over 45 %

Increased alumina content in refractory grog is a product of the grog’s firing and, at the same time, it is a raw material used for the production of dense or insulating, shaped or monolithic refractories. Grog characteristics determine the properties of the final product. The specific characteristics of the grog are therefore optimized to suit the refractory product as close as possible. The basic characteristics determining the nature of the grog include its mineralogical composition, chemical composition, and apparent porosity. The present study focuses on ways of reducing the porosity of a high-alumina grog and thus obtaining a raw material suitable for the production of dense refractory materials. The experiments have shown that it is possible to regulate porosity by using clay with better sinterability and phosphoric acid in the production of grog from claystone with alumina content over 40 %, a minimal Fe2O3 content, a minimal content of CaO and alkali oxides.

The Effect of Temperature on the Fundamental Characteristics of Self-Compacting No-Cement Refractory Castable

In this research, the impact of firing temperature and MgO addition on mechanical and physical properties of self–compacting no-cement castables were investigated. For this propose up to 3.3 wt % of MgO was added to the corundum castable compositions and the specimens were fired at 600 °C, 800 °C, 1000°C, 1200°C and 1500°C. The mixtures were made so that the consistency of each one was the same. There were only minimal differences in the mixtures water content. The mineral composition of the input raw materials for manufacturing of the refractory castables was determined. The physical and mechanical properties of castable compositions such as self-flow values, bulk density, apparent porosity, cold crushing strength and flexural strength were examined. Also, the X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDX) techniques were used for detection the ceramic phase formation. The corrosion resistance was determined by means of the crucible test according to ČSN P CEN/TS 15418 (726022) Method of test for dense refractory products – Guidelines for testing the corrosion resistance of refractories caused by liquids. The study follows up on research, the results of which were published last year [1], but the study is focused to self-compacting refractory castable.

MgO Influence on the Fundamental Characteristics of Corundum Refractory Castables

The paper focuses on the determination of how periclase content in the raw material influences the final properties of no-cement refractory castables. The motivation for this research was the continued pressure on increasing the utility properties of refractory castables, especially their corrosion resistance. The influence of MgO was observed in vibration-compacted refractory castables; the mixtures were made so that the consistency of each one was the same. There were only minimal differences in the water content of the mixtures. The mineral composition of the raw materials used in the manufacturing of the refractory castables was determined and the influence of the firing temperature on their compressive strength, flexural strength, apparent porosity, mineralogy and pore structure was described. The corrosion resistance was determined by means of the crucible test according to CSN P CEN/TS 15418 (726022) Method of test for dense refractory products – Guidelines for testing the corrosion resistance of refractories caused by liquids.