Effect study of an amount of active alumina addition on the properties of alumina refractories with a complex additive of chromium oxide and zirconium dioxide

An effect of active alumina amount introduced into a batch (7.5 - 22.0 %) on the properties of alumina samples containing a complex additive of chromium oxide (10 %) and zirconium dioxide (3 %) was studied. The optimal amount of introduced active alumina (12.5 %) was established, which ensures the production of samples fired at a temperature of 1580 ºС, with the lowest open porosity (18.2 %), the highest apparent density (3.25 g/cm3) and the highest cold crushing strength (117 N/mm2), refractoriness under a load of 0.2 N/mm2 > 1700 ºС, thermal shock resistance (in the mode of 1300 ºС — water) not less than 7 thermal cycles.The results of carried out studies were used in the development of production technology of domestic refractory products based on fused corundum, α-form alumina, active alumina, containing the complex addition of chromium oxide and zirconium dioxide, by semi-dry pressing method. These refractory products characterized by high properties and intended for service at a temperature of 1850 ºС in the combustion chamber of carbon black production reactors.The use of these refractories in the lining of above mentioned high-temperature industrial units will allow to increase a duration of their operation due to an increase in the refractory durability in service, as well as to save material and energy resources associated with a relining of the reactors.

Effect of a calcined alumina additive amount on the properties of zirconia ramming mix on а phosphate bond

An effect of alumina additive amount on the main properties of ramming mix samples based on zirconia stabilized with calcium oxide on a phosphate bond was studied, as well as the processes of phase formation in these samples. It was found that, the alumina additive introduction activates the ZrO2 cubic phase destabilization, but does not cause softening of the samples structure. This is due to the fact that, as a result of the interaction of alumina with CaO released from the solid solution with ZrO2, elongated prismatic crystals of calcium hexaaluminate are formed, which reinforce and strengthen the samples structure. It was shown that, the samples composition containing 10 % alumina additive is optimal in terms of porosity, strength, and thermal shock resistance: ZrO2 + НfO2 — 83.52 wt. %; CaO — 3.86 wt. %; open porosity-— 15.9 %, cold crushing strength —62 N/mm2, thermal shock resistance (1300 ºС — water) — 6 thermal cycles, change in linear dimensions — 1 %. The obtained scientific results were used in the technology development of a new type of product — a mixture of powders for zirconia-alumina ramming mix, the manufacture of which was mastered at JSC "URIR named after A. S. Berezhnoy". The developed ramming mix is recommended for use, in particular, for making lining at the border of combustion and mixing zones of carbon black production reactors.

Optimization of Carbon Black Production from Waste Polyethylene Water Sachet

Waste management has been one of the greatest of Nigeria. In this study production of carbon black was carried out by recycling of waste polyethylene water sachet. Optimization of carbon black production was also done by varying factors that affects its production using response surface methodology. Box Behnken design was used to generate a total 17 experimental runs, which were design to study the effects of reactor size, initial fuel volume and mesh size on the carbon black production. A quadratic regression model was obtained for the production of carbon black with highest yield of 0.84g at optimal condition reactor volume of 2500 cm3, mesh area of 0.01 cm2, and initial fuel volume of 0.01 liters. The prediction of the model was verified using optimal condition which was applied to three independent replicates and the average carbon black yield obtained was 0.80 g, which was well within the estimated value of the model equation. The result obtained could be scaled up to pilot production.