The research of the effect of oxidizing agents on the burning process of the carbon-containing component of ceramic masses and their firing properties

Abstract

The efficiency of using different oxidizing agents to intensify the burnout of the organic component of ceramic masses is investigated. The ceramic masses contained coal flotation wastes with a high carbon content as a fuel-mineral additive. Various inorganic salts, which are oxygen donors during the firing of ceramic masses and form oxidizing agents O2, NO2, N2O during their thermal decomposition, are considered. A new calculation method for determining the content of an oxidizing salt in a ceramic mixture is proposed. This method takes as a basis the amount of «effective oxygen» that released during the thermal decomposition of the oxidizing agent, but not its mass, as it was before. The method allows calculating the rational content of an oxidizing agent necessary for efficient combustion of the carbon component of fuel-mineral additives. When calculating, it is necessary to take into the composition of the organic part of the additive, its content in the ceramic mass and the degree of carbon oxidation. Calculation of the rational content of the oxidizing agent according to this method allows avoiding its excessive and economically unreasonable use. The effect of oxidizing agents and their combinations on the burnout of the carbon component and the firing properties of the masses for wall ceramics is studied. The masses contained 15 % of coal flotation waste with a carbon content of 29 %. It was found that the use of oxidizing agents accelerates the burnout of the organic part of the masses, improves the appearance and mechanical properties of ceramic samples. The use of combined oxidizing agents with different decomposition temperatures makes it possible to create an oxidizing medium in a wider temperature range. This positively effects on the mechanical properties of ceramics. The optimal combinations of oxidizing agents NH4NO3+Ca(NO3)2 і NH4NO3+NaNO3, which made it possible to obtain ceramic samples with a compressive strength 10 МПа, were determined. This mechanical strength meets the requirements of the State Standard of Ukraine B M.2.7-61: 2008 in part of ordinary brick of the M100 brand.