Modeling of hydrogen reduction of fine iron oxide

Abstract

During the multi-ton production of steel, a lot of fine by-products are formed as contamination of the environment. Traditionally, they were collected in dumps or sludge tanks. From the point of view of environmental protection, such by-products should be purified and utilized by recycling. One such refined by-product is fine iron oxide powder. It is irrational to return such the by-product for utilization in the main production of steel. As an option, processing of such iron oxide into iron powder is proposed. Reduction of the oxide to fine iron powder with hydrogen is an ecological method of processing. The problem with fine oxides is the lack of flowability of such material. It has a highly developed surface and can be highly flammable after reduction. The industrial production of iron powders today prefers the technology of atomization of overheated steel with high-pressure water, followed by annealing in a controlled atmosphere containing hydrogen. But the raw powder after atomization contains 2-3% of residual oxygen. And the fine iron oxide obtained as the by-product has a content of oxygen up to 29.5%. Therefore, the processes of annealing and reduction are very different. To study the process of hydrogen reduction of the fine iron oxide from sludge waste, experimental studies were conducted and a mathematical model of the process was developed. The mathematical model predicts the degree of reduction depending on three process control factors, namely: powder layer height, furnace temperature, and time within the hot furnace section. The main purpose of obtaining a mathematical model is the further virtual study of the process for the development of a technical task for the design of a pilot project for the production of iron powder by the method of hydrogen reduction of iron oxide. The pilot trials of the technology will be the basis for the commercial technology.