EVALUATION OF THE POSSIBILITY OF CLEANING OILY SCALE BY THERMAL METHODS

Abstract

This article addresses a pressing issue in modern metallurgy: the effective disposal of oily scale. This material is a valuable man-made resource with a high magnetite content (65–72% Fe). However, the presence of significant amounts of oil and moisture (up to 20%) and its status as Class III hazardous waste hinder its direct use in sintering operations due to environmental risks and equipment safety hazards. The paper examines three main approaches to solving the problem: chemical degreasing, biological remediation, and thermal destruction. The authors focus on the thermal method. Laboratory studies conducted at PAO Severstal in a high-temperature furnace have experimentally established that effective scale degreasing requires heating to a temperature of at least 450–500°C. Under these conditions, the mass fraction of oil products decreases from the initial 10.2% to less than 1%. The practical significance of this work is confirmed by the results of pilot tests. The article describes the design and operating principles of a modular unit based on a lined rotary kiln with a capacity of 1 ton per hour. The process chain is presented: from raw material acceptance by screw conveyors to drum firing at approximately 900°C, where moisture evaporates, organic impurities are burned off, and the scale structure is strengthened. Particular attention is paid to the environmental safety and energy efficiency of the process. A system for exhaust gas afterburning in a special chamber and the use of heat exchangers, which allow for the recovery of thermal energy for heating the plant's premises, are described. The authors conclude that systemic thermal cleaning not only eliminates environmental risks but also significantly improves technical and economic performance by returning high-quality iron to a closed production cycle.