КИНЕТИКА ВЫСОКОТЕМПЕРАТУРНОЙ ДЕГИДРАТАЦИИ ЛИСАКОВСКОГО ЖЕЛЕЗОРУДНОГО КОНЦЕНТРАТА

Abstract

Lisakovsk deposit of brown iron ore (Kostanay region, Ka-zakhstan) is developed by the open method, which provides cheaper ore mining. At the LF LLP “Orken”, the ore is enriched in a gravity-magnetic process to produce a gravitational-magnetic concentrate containing 48 to 49 % of Fe, 10 to 12 % of SiO 2 , 4.5 to 5.5 % of Al 2 O 3 and 0.7–0.9 % of P. The product is supplied to the agglomeration in JSC “Arcelor Mittal Temirtau” (Temirtau, Kazakhstan). Because of the increased content of phosphorus in the gravitational-magnetic concentrate, the demand for it is limited. Lysakovsk concentrate contains a significant amount of hydrated moisture (up to 12 %). Most of the moisture is in the form of iron hydrates and decomposes at a moderate temperature of 320–350 °C. The other part, apparently, is associated with a phosphorus-containing component decomposing at elevated temperature. In this process, oxidative firing results in the formation of free phosphorus oxide. Studies on decompounding a hydrated phosphorous-containing component in Lisakovsk iron ore concentrate were undertaken to determine kinetics of the process. Removal of phosphorus from the iron ore concentrate during preparation for metallurgical processing is possible after high-temperature oxidizing roasting of the material and subsequent sulphuric acid leaching. Phosphorus is not leached from the original concentrate by hydrometallurgical method. Using high temperature, it is necessary to break the chemical bond and transfer phosphorous to a free oxide. Complete decompounding of the hydrated phosphorous-containing component at roasting affects the quality of subsequent sulphuric acid treatment of the roasted product. High-temperature hydrate moisture is exuded from Lisakovsk concentrate step-by-step. The rate of high-temperature dehydration de- creases with the rise of calcination temperature, which is explained by slow water vapour diffusion through the layer of material that becomes packed at the temperature rise. © 2017, National University of Science and Technology MISIS. All rights reserved.