Use of Lebedinsky Mining and Processing Works Overburden Chalkstone for Iron-Ore Pellet Fluxing

Abstract

Mine rocks generated abundantly in the course of iron-ore deposit development and containing high quality overburden chalkstone are mainly stored in dump pits. This relates to the Lebedinsky Mining and Processing Works as well. This results in certain environmental issues. Therefore the work provides the investigation results in some measure allowing the defined problem solution through complete replacement of limestone used for iron-ore pellet fluxing by the overburden chalkstone. This required a whole set of experiments. Derivatographic investigation was carried out on the overburden chalkstone samples of the Lebedisky Mining and Processing Works and allowed defining of the studied sample temperature and heating time impact on production of chalkstone with varying decarbonization process extent. Activity of the lime produced from the chalkstone was evaluated through determination of the total content of active calcium and magnesium oxides in it. In the course of the experiments the temperature and time impact on the liming process was defined. To justify the potential of the overburden chalkstone use as an additive for iron-ore pellet fluxing and their production with sufficiently high strength properties ensured, as well as of the complete replacement of the limestone used for these purposes, the experiments with the briquettes were carried out. At that the briquette composition complied with that of the fluxed iron-ore pellets. The briquette strength properties with chalkstone additives versus the firing temperature and degree were studies, as well as physicochemical processes occurring in the samples at their heat treatment. As a result of the investigation it was determined that the chalkstone additive use in the pellet fluxing contributes to their significant strength increase. The obtained results are of certain interest for the specialists dealing with iron ore material preparation for metallurgical conversion and allow development of pellet heat treatment conditions ensuring their high metallurgical performance.