Use of ceramic fiber modified with ferrites for the cleaning of flue gases of graphitization furnaces

Abstract

Gaseous emissions of industrial enterprises as a result of their economic activities adversely affect the ecological situation, and even worsen the sanitary and hygienic working conditions of the personnel. Carrying out chemical reactions in the furnace equipment of metallurgical and electrothermal production, as a rule, lead to the formation of gases containing various toxic impurities, including carbon monoxide, the disposal of which is an important environmental task. As the calculations show, the total amount of annual CO emissions in Ukraine is 704344.218 t/year, which in percentage terms is 31.42% of the total emissions of pollutants and greenhouse gases, except for carbon dioxide - 2242020.75 t/year. The release of significant amounts of poisonous CO into the atmosphere is a serious problem that must be solved at the level of industrial production. One of the effective directions in the field of purification of industrial gas emissions from toxic carbon monoxide is the application of catalytic technologies due to the use of compositions based on transition metals, especially ferrite materials. Recently, systems for neutralizing toxic gases, including glass fiber catalysts, have become widely popular. The study of the CO oxidation process was carried out on a flow-type installation with a stationary weight of the catalyst. Catalytic purification of the gas mixture from CO was studied in the range of 50-450 °C. The concentration of carbon monoxide in the initial gas mixture at the entrance to the reactor was varied in the range of 1-2 vol. %. If necessary, helium was used as an inert gas. Ceramic fiber was used as a fiberglass support for catalytic systems for the oxidation of gaseous emissions containing CO. Ferrite catalysts were applied to ceramic fiber by the method of impregnation from sulfate solutions of iron, copper, and potassium bichromate. From the temperature dependences of the conversion of carbon monoxide with a concentration of 1-2% on ferrite catalysts on a ceramic fiber carrier, it can be seen that 100% conversion of carbon monoxide is not achieved even at a temperature of 450 ºС. In the case of using a mixture of magnetite and copper ferrite, the degree of conversion of CO was 97% at temperatures above 300 ºС and stably ensured the neutralization of CO until the conversion degree of 98% was reached at a temperature of 450 ºС. At a temperature of 450 ºС, the highest degree of conversion of 99% was ensured by using chromium ferrite, but the specified chromium-ferrite catalyst at a temperature of 400 ºС provided a slightly lower oxidation efficiency, that is, the specified catalyst has less advantages for use in fluctuating gas temperatures in industrial conditions. When magnetite and copper ferrite were used separately, the degree of CO conversion was 40% and 75%, respectively. Therefore, the conducted studies showed that the use of ceramic fiber modified with ferrites can be effectively used for the purification of flue gases of electrode graphitization furnaces, in particular, the neutralization of toxic carbon monoxide. Obtaining ceramic fiber modified with ferrite material does not require significant capital investments, as it is based on the use of liquid waste from etching, copper plating, and chrome plating of galvanic production. Laying ceramic fiber on top of the thermal insulation of the graphitization furnaces of electrode production will also reduce the inflow of oxygen into the porous space and reduce the formation of carbon monoxide, which will contribute to the improvement of the ecological situation at the electrode production. The obtained results on the use of ceramic fiber modified with ferrite material as a catalyst for the neutralization of carbon monoxide are a highly effective and affordable measure to reduce the man-made burden of electrode production on the environment.