A. Altun

Investigation into Utilization of Bayer- Al(OH) 3 in Production of Calcium Aluminate Cements

Abstract. In this study, samples of Calcium Aluminate (CA) cements produced from reactive alumina and calcite were compared with those samples produced from Bayer - Al(OH)3 and calcite. The raw material mixtures were formed under light pressure into cylinders and sintered at 1350, 1400, 1450 and 1500 0 C. The fired samples were ground to 3300-4400 cm 2 /g Blaine in a laboratory ceramic mill. The physical and mechanical properties of the cement samples were determined. The results of this study suggest that the production of CA - cements containing 71 % Al 2 O 3 was possible using Bayer- Al(OH) 3 and calcite as raw materials. Introduction In recent years, the use of high alumina cements in the refractory concrete mixtures as a binder has gained importance. The main trend in refractory concrete is the production of high density, dimensionally stable and long life refractory materials by decreasing amount of binding cement. Bauxite, the principal raw material of commercial CA cements should have very high alumina and very low iron and silica contents. SiO

Development of Basic Heat-Insulating Bricks by Burn-Out Process

MgO-heat insulating bricks were produced using high quality sinterMgO, 25 % or 35 % combustible materials and 20 % spinel (M-Sp/I) or alumina (M-Sp/II) additives. For sufficient strength MgSO4 was added in amount of 7.5 %. Petroleum coke and saw dust mixture was used as combustible material. The optimal heating profile was determined with the help of thermo gravimetric analyses. Hematite fines were used as sintering aid. The formed samples were sintered at 1500 and 1600 o C. The thermal conductivity curves and micro-structure of the samples were similar to those of the reference sample.

Effect of CaO on Thermomechanical Behavior of SiC Based Self-Flowing Castables

In this study the use of hydratable alumina binder (Alcoa) instead of Calcium Aluminate (CA) cement as binder in the production of SiC based self-flowing castable has been investigated. Spent SiC particles were classified into different fractions following crushing and grinding operations and have been utilized as aggregate. Tabular alumina, calcined monodipersed alumina, and hydratable alumina/CA cement were used as binder matrix. Anorthite (CaO.Al2O3.2SiO2) a gehlenithe (2CaO.Al2O3.2SiO2) phases were formed according to the CaO-Al2O3-SiO2 three phase diagram. Molten phase negatively affects refractoriness of the materials. For that reason, by using hydratable alumina instead of CA cement mullite binder was created. Mullite was studied by SEM. In addition to CA cement supplementary samples, molten phase produced with CaO lessened the value of the hot modulus of rupture (HMOR). Hydratable alumina binder added samples at 1450 o C, however amplified the values of HMOR. It was concluded that the refractories acquired can be used as kiln furniture for porcelain sector.