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Study of the nature of transformation of weakly magnetic iron oxides/oxyhydroxides into strong magnetic oxides under the action of external influences for the improvement of the technology of processing natural and technogenic mineral raw materials

ABSTRACT

Report on the SRW: 1 book, 55 pages, 31 illustrations, 10 tables, 33 references.

The object of the study is a collection of iron ore samples from the Kryvyi Rih and Kerch iron ore regions, as well as synthetic iron oxides and hydroxides.

Purpose of the work: The purpose of the project is a theoretical and experimental study of the influence of various external factors on the structure, crystal-chemical and physical properties of weakly magnetic iron oxides and oxyhydroxides, which lead to their transformation into strongly magnetic oxides, which are easily enriched and concentrated for industrial purposes.

Research methods and equipment: magnetometry method (magnetometer with a Hall sensor), X-ray diffraction method (DRON-3M), YGR spectroscopy, thermomagnetic studies.

Results and their novelty: Collections of iron ore samples from the Kryvyi Rih iron ore region were created. The phase transformations of hematite and goethite ores at temperatures up to 650°С in the presence of bioregenerative raw materials, as well as under mechanical activation, were studied. It was shown that under such influences weakly magnetic minerals turn into strongly magnetic magnetite. It was shown that isomorphic impurities in the structure of the formed magnetite lower its Curie temperature. The phase transformations of synthetic lepidocrocite during temperature treatment up to 650°С in the presence of a reducing agent were studied and it was shown that lepidocrocite transforms into magnetite during such treatment. The kinetics of the transformation of the structure of iron oxides and hydroxides in an aqueous environment (in the presence of iron salts and alkali) at a temperature of 100 °C and in a dry environment (after reduction with starch) were studied. It was shown that hematite and goethite are transformed into magnetite during such treatments, and the saturation magnetization of the formed samples increases tenfold (up to 70 A∙m2/kg). Mechanisms of transformation of weakly magnetic iron oxides and oxyhydroxides into strongly magnetic oxides are proposed. The novelty of the obtained results is that the procedures of phase transformations are energy-saving and do not require large amounts of reducing agents.

Recommendations for using the results of the work: the obtained results can be used to solve the problems of processing iron ores of Kryvyi Rih and the Kerch region, as well as to solve environmental problems associated with the disposal of dumps and tailings in Kryvyi Rih.

Authors:

Ponomarenko Oleksandr Mykolaiovych

Other authors:

Bryk O.B., Yushyn O.O., Dudchenko N.O.

Keywords:

crystal structure, magnetic properties, phase transformations, iron oxides and hydroxides, magnetite, hematite, goethite, lepidocrocite

Head of the research:

Ponomarenko Oleksandr Mykolaiovych

Registration Card (RC):

0114U002921

Execution period of the research:

2014 - 2015