Study on Magnetite Ore Crushing Assisted by Microwave Irradiation

High energy consumption in ore crushing brings great challenges to the mining industry. Microwave irradiation provides a promising solution for rock breaking. However, there is currently a lack of detailed understanding of the microwave parameters regarding magnetite ore. The purpose of this study is to fully understand the potential value of microwave irradiation applied in auxiliary crushing of magnetite ore. It is typically found that increasing power reduces the mechanical properties of ore, increasing energy utilization, and crushing degree, more than extending time. Based on wave impedance, this reveals the dependence of energy utilization on thermal damage. Increasing irradiation power, time and cooling rate will cause more transgranular cracks and cleavage tears in the crushed ore. Based on the separate microwave response of several minerals, the microwave-damage mechanism of magnetite ore is further demonstrated.

Technological characteristics of sulfide-magnetite ore washability at the magnetite skarn Peschanskoe deposit

Introduction. In the magnetite lime-skarn Peschanskoe deposit, the Zapadno-Peschanskaya ore deposit is distinguished, which differs from other ore bodies by an increased content of copper and precious metals. Due to the fact that the technology of processing magnetite ores of the Peschanskoe deposit at the enterprise of the subsurface user is configured to receive only iron concentrate, the development of a comprehensive technology for processing sulfide-magnetite ores is an urgent task. Research aim is to study the material composition and sulfide-magnetite ore concentration of the ZapadnoPeschanskaya ore deposit and to develop a comprehensive technology for its processing. The technology should ensure gold-containing, copper and iron concentrates production. Research methods consisted in studying the material composition of sulfide-magnetite ore by means of quantitative chemical analysis using Arcos emission spectrometer with inductively coupled plasma, Solaar atomic absorption spectrometer, CS-800sulfur analyzer, Titration Excellence T-70 automatic titration system, and Specord 250 Plus scanning spectrophotometer; chemical phase analysis for the forms of iron, copper, gold, silver and sulfur compounds; mineralogical analysis using the Axio Imager A1m optical microscope and Mineral C7 automated analyzer. Technological research was carried out by various concentration methods: X-ray radiometric separation on the SRF1-100L separator; dry magnetic separation on the PBS-90/25 magnetic separator; gravity on the KC-MD3 centrifugal concentrator and the SKL-0.2 concentration table; flotation on the FMP-L series flotation machines; wet magnetic separation on the electromagnetic separator EBM-32/20. Scope of results. The present research result can be used at complex sulfide-magnetite ores processing. Conclusions. The results of the material composition research and technological properties of the sulfidemagnetite ore of the Zapadno-Peschanskaya deposit of the Peschanskoe skarnovo-magnetite deposit are presented. It is established that the researched ore can be efficiently processed using a complex gravityflotation-magnetic technology, which allows to obtain: gravity gold-containing concentrate with a mass fraction of gold of 50 g/t at recovery of 27%; copper concentrate with a mass fraction of 23.71%, gold – 18.9 g/t and silver – 60.0 g/t when extracted, respectively, 93.6%, 42.9% and 54.6%; magnetite concentrate with a mass fraction of iron 66.5%, sulfur 0.7% with the recovery of total iron 76.6%.

Increasing of efficiency of dry magnetic enrichment of magnetite ore

A possibility of sintering ore obtaining from regular skarn magnetite ore by dry magnetic separation considered (DMS). A possibility of decreasing iron losses with DMS tails by additional control operation and application of separators of various design as well as application of screening studied. It was shown, that re-cleaning of intermediate product of –15+0 mm size enables to obtain from a regular skarn magnetite ore, a sintering ore having iron mass share more than 45% at the yield of 5.5% (of DMS intermediate product). It can be reached by application of a suspended belt separator with flat magnetic system. By using a drum separator with increased drum rotation speed, a DMS concentrate was obtained having iron mass share of 43.08%. Application of additional control operation of DMS tails enables to decrease the iron mass share in DMS tails from 11.25–11.32 to 9.97–10.67% as well as iron losses with DMS tails by 11.13–26.06% (rel.). To decrease the iron losses with DMS tails it is reasonable to increase magnetic field induction of drum separators of basic operation, but not apply additional control DMS operation. It was established, that the basic iron losses relate to fine class (–3+0 mm), characterized by increased iron mass share (14.43%). Therefore, for reextraction of iron from DMS tails a scheme with screening at 3 mm sieve and DMS of the mesh minus is possible. Such a scheme enables to obtain an intermediate product having iron mass share of 35.05–45.74% from DMS tails.

The features of classification in hydrocyclones in the course of titanium magnetite ore grinding

Research aim is to assess the use of hydrocyclones in the closed circuit of the second stage of grinding for the conditions of EVRAZ KGOK dressing mill. Methodology. Industrial tests were carried out under various solid phase capacities of two hydrocyclones GTs-710. Industrial testing results and their discussion. Increase in the content of solid and –71 µm class in the feed of the hydrocyclone results in discharge output increase. Decrease in the content of solid and increase in the content of –71 µm class result in the increased content of –71 µm class in the discharge. When increasing the content of solid in the feed of the hydrocyclone, the extraction of all size classes into the discharge of the hydrocyclone increases. At the same time the efficiency of classification by –71 µm class reduces. 84 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 1. 2021 ISSN 0536-1028 Iron content values in hydrocyclone discharge and sand. The classifying hydrocyclone partially separates by density resulting in different content values of iron in discharge and sand. Under pulp high density, the content of iron in the discharge is higher than that of iron in sand. Under low density of feed pulp, there is less iron in the discharge, compared to that in sand; that is due to small particles of titanium magnetite entering the sand. Summary. The indicators of separation by size in hydrocyclone are significantly affected by the content of solid and –71 µm class in the feed. The drawback of the hydrocyclone is partial separation by density (in iron) which results in overgrinding of titanium magnetite in the closed circuit of grinding and higher losses in subsequent procedures of wet magnetic separation. The technologies which make it possible to reduce overgrinding of titanium magnetite in the closed circuit of grinding are as follows: automatic control system for classification in the hydrocyclone, the use of hydraulic screens instead of hydrocyclones, and multi-stage dressing.