Integrated study on obtaining oxide pellets from brown iron ore

Introduction. Currently, the main raw materials for the production of cast iron and steel at metallurgical plants are iron concentrates obtained from magnetite (ferrous) quartzites, titanium-magnetite, and skarn ores. The existing technologies for processing these types of ores, which mainly include separation processes based on magnetic properties, size, separating of equally falling grains, and surface wettability allow us to produce both ordinary iron concentrates and high quality ones. The use of such schemes in the processing of brown iron ore does not allow obtaining high rates of mineral concentration. One of the methods for processing this type of ore is a roasting-magnetic scheme, which allows converting weakly magnetic (non-magnetic) forms of iron into strongly magnetic ones. Research objective is to develop the mode of magnetizing roasting of brown iron ore, technology of concentrating of the burn-out product in order to obtain iron concentrate and oxide pellets. Methods of research. The duration of heat treatment of the charge consisting of iron ore from the Abail deposit and coal from the Ekibastuz deposit and the required mass fraction of solid carbon contained in the coal are determined. Technological studies of the roasted product were carried out in order to obtain a concentrate with a mass fraction of iron at least 67%. According to the developed technology, a batch of iron concentrate was developed in order to obtain and study raw and oxide pellets. Results. The modes of magnetizing roasting of brown iron ore from the Abail deposit and cooling of the roasted material have been developed. A scheme for mineral processing of the roasted material has been developed in order to obtain a concentrate with at least 67% of iron mass fraction. The process of obtaining strong raw and roasted pellets from iron concentrate is studied. Conclusions. The developed mode of magnetizing roasting of the charge consisting of coal and ore from the Abail deposit makes it possible to obtain a roasted product with a degree of magnetization of 93%. The using of desliming of the roasted product makes it possible to remove magnetic floccules from the processing that reduce the concentrate quality, and to obtain a concentrate with a mass fraction of iron of at least 67% in the last stage of magnetic separation. From the iron concentrate, it is possible to obtain oxidized pellets with a strength of at least 200 kg/pellet at temperature of pellets firing of 1325 °C.

Study of iron content in iron ore concentrate increasing effect on sintering process indices and on metallurgical properties of sinter

Effectiveness of blast furnaces operation in many respects depends on metallurgical properties of agglomerate, in particular, iron content in the sinter and its basicity. At the same time, it is accepted that usage of iron ore concentrates with iron content more than 66–67% for sinter production results in decreasing of its strength. As a result of the planned modernization of the technological sections of the concentration plant JSC “Stoilensky GOK”, iron content in the concentrate will be increased to 68–70%. It makes it actual to accomplish comprehensive studies of metallurgical properties of the sinter while increasing iron content in the raw material. Results of the study of sinter properties presented, the sinter being obtained with utilization of iron concentrate with iron content 66.6 % (base), 68.0 and 69.2 % (exp. 1 and exp. 2 correspondently). The iron ore mixture for all the stages was the same and consisted of iron ore concentrate – 78.3%, sintering ore – 8.0%, lime – 5.5% and sintering additives (sludge, dust, scale) – 8.2%. The sintering mixtures composition for all the study stages differed only by fluxes and iron ore mixture consumption. 18 test sintering operations at three values of basicity 1.6, 1.8 and 2.0 units were accomplished. It was established that increase of iron content in the concentrate and basicity of the sinter results in improving of the sintering process indices, increase of the vertical sintering rate, sintering machines productivity, recovery and the sinter cold strength. Increase of the sinter basicity and its production with increased content of iron results in improving RDI indices at low temperature reducing. Results of the study of porosity indices and metallurgical properties of the sinter presented, in particular the collapsibility during reducing and temperature interval softening-melting presented. The advisability of concentrate with increased iron content utilization in the iron ore mixture shown.

Investigation of the process of metallized materials production from iron concentrate of hydrometallurgical enrichment of ferromanganese ores of Kuzbass

Study of the processes of solid-phase reduction of iron from oxides using coals as reducing agents and the development of energy-efficient technologies for the production and use of metallized materials from concentrates obtained as a result of hydrometallurgical enrichment is an actual scientific direction in ferrous metallurgy. Theoretical studies of the processes of solidphase reduction of iron from iron-containing concentrate obtained as a result of hydrometallurgical enrichment of ferromanganese and polymetallic manganese-containing ores, by coals grades D (long-flame) and 2B (brown) were carried out by the method of thermodynamic simulation using the “Terra” software complex. The experimental study of the process of solid-phase reduction of iron from experimental mixtures was carried out in a muffle furnace SNOL 4/900 and in a resistance furnace with a graphite tubular heater (Tamman furnace). The influence of the composition and volume of gas phase, formed as a result of volatile components emission in the process of coals of two grades heating at 373–1873 K obtained, optimal temperature and consumption of coals defined, which ensure complete reducing of iron from iron-containing concentrate, compositions as well as volumes of gas phase. The influence of temperature of the isothermal exposure on the rate and degree of solid-phase reduction of iron from iron ore oxides was experimentally determined when using coals of different process grades and coke fines as reducing agents. Empirical equations of reduction degree versus time of isothermal exposure for different metallization temperatures were obtained. It is shown that the change in the degree of recovery on temperature with high accuracy was described by a linear dependence, and the change in the recovery rate on the temperature – by a power dependence. Conditions of effective metallization were determined when using iron concentrate and coals of different process grades for production of spongy metallized materials with content of Femet more than 80%, and 1.5–2.5 % C, 0.1 % S, 0.02 % P. As a result of thermodynamic simulation and experimental study of the process of iron reduction from iron concentrate, optimal consumption of coal of grades D and 2Б at temperature 1473K was determined. It was established that the best reducing agent with a minimum specific consumption is long-flame coal grade D. It was found that with an excess of reducing agent, it is possible to achieve almost complete extraction of iron from the concentrate, at the level of 98–99%.

Leaching Titaniferous Magnetite Concentrate by Alkaline Aqueous Solution

Leaching titaniferous magnetite concentrate with alkali solution of high concentration under high temperature and high pressure was utilized to improve the grade of iron in iron concentrate and the grade of TiO2 in titanium tailings. The titaniferous magnetite concentrate in use contained 12.67% TiO2 and 54.01% Fe. The thermodynamics of the possible reactions and the kinetics of leaching process were analyzed. It was found that decomposing FeTiO3 with NaOH aqueous solution could be carried out spontaneously and the reaction rate was mainly controlled by internal diffusion. The effects of water usage, alkali concentration, reaction time, and temperature on the leaching procedure were inspected, and the products were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy, respectively. After NaOH leaching and magnetic separation, the concentrate, with Fe purity of 65.98% and Fe recovery of 82.46%, and the tailings, with TiO2 purity of 32.09% and TiO2 recovery of 80.79%, were obtained, respectively.

Elaboration and implementation technology of concentration of Magnitogorsk steel-works slime tailings

The problems of processing iron ore tailings of wet concentration plants and wastes with high content of iron, contaminated by oil products are actual from both points of view of ecology and economy. One of the reasons restraining solving the problem is absence of technologies ensuring to involve such wastes into industrial turnover. In the process` of the research, composition and opening degree of ore and non-metallic minerals of concentration slime tailing of Magnitogorsk steel-works (MMK) were studied and technology of their concentration was elaborated. Taking into consideration the contamination of initial slime tailings of MMK, it was proposed to accomplish their preliminary de-sliming to remove vegetable remains and clay slimes by disintegration in a screw-toothed crusher and washing in a spiral classifier. Results of wet magnetic separation (WMS) of the initial slime tailings of MMK, made at JSC “Uralmekhanobr” presented, the slimes having natural coarseness of –2.0+0.0 mm. It was established that WMS at the magnetic field intensity of 1500 Oe ensures effective removal of magnetite, aggregates magnetite-hematite-goetite into magnetic product. Iron content in the magnetite concentrate was varying from 61.5 to 62.6%. For processing of slime tailings of MMK, magnetic separation was proposed by high-gradient magnetic separator with permanent magnets, created specially for these purposes by “ERGA” company. To increase iron extraction degree, it was proposed to apply gravitation methods of concentration of nonmagnetic product, obtained at high-gradient WMS. It enabled to increase iron content in the final magnetite-hematite concentrate up to 59%. A technological diagram of oiled slimes processing presented. Tests with oiled slimes of bottom deposits of metallurgical production under pilot-industrial conditions of MMK exhibited a possibility to obtain additional iron concentrate with total iron content of 62.47% while oil content in it was less 0.3%.

Possibilities of Siderite and Barite Concentrates Preparation from Tailings of Settling Pit Nearby Markušovce Village (Eastern Slovakia)

The contribution deals with recovery of useful minerals such as siderite and barite from tailings collected in settling pit nearbyMarkušovce village (East Slovakia). The material form the pit was subjected to gravity pre-concentration and magnetic separationunder laboratory conditions with the aim to verify a possibility of siderite and barite concentrates preparation. A fraction of +0.2–1mm forming a 40.56 wt% of total grain size scale of the material from the pit and containing 35.71% SiO2, 22.55% Fe2O3, 7,12%Al2O3, 5.48% Ba, and 3.89% SO42– was tested in upgrading process. Thus, 78.18% of SiO2, and 60.41% of Al2O3 at loss 21.70%Fe2O3 and 2.09% of Ba were removed in gravity pre-concentration. The iron concentrate with the content of 44.33% Fe2O3 at Ferecovery of 77.29% in magnetic product was obtained. Barite pre-concentrate with the Ba content of 46.21% at Ba recovery of91.95% in non-magnetic product was won.

Extraction of Manganese and Iron from a Refractory Coarse Manganese Concentrate

In this research, the coarse manganese concentrate was collected from a manganese ore concentrator in Tongren of China, and the contents of manganese and iron in coarse manganese concentrate were 28.63% and 18.65%, respectively. The majority of the minerals in coarse manganese concentrate occur in rhodochrosite, limonite, quartz, olivine, etc. Calcium chloride, calcium hypochlorite, coke, and coarse manganese concentrate were placed in a roasting furnace to conduct segregation roasting, which resulted in a partial chlorination reaction of iron to produce FeCl3, ferric chloride reduced to metallic iron and adsorbed onto the coke, and rhodochrosite broken down into manganese oxide. Iron was extracted from the roasted ore using low-intensity magnetic separation, and manganese was further extracted from the low-intensity magnetic separation tailings by high-intensity magnetic separation. The test results showed that iron concentrate with an iron grade of 78.63% and iron recovery of 83.60%, and manganese concentrate with a manganese grade of 54.04% and manganese recovery of 94.82% were obtained under the following optimal conditions: roasting temperature of 1273 K, roasting time of 60 min, calcium chloride dosage of 10%, calcium hypochlorite dosage of 5%, coke dosage of 10%, coke size of −1 mm, grinding fineness of −0.06 mm occupying 90%, low-intensity magnetic field intensity of 0.14 T, and high-intensity magnetic field intensity of 0.65 T. Most minerals in the iron concentrate were Fe, Fe3O4, and a small amount of SiO2 and CaSiO3; the main minerals in the manganese were MnO, and a small amount of Fe3O4, SiO2, and CaSiO3. The thermodynamic calculation results are in good agreement with the test results.

Technological research on converting iron ore tailings into a marketable product

SYNOPSIS We present three technological scenarios for the recovery of valuable components from gangue, stored in the tailings dam at Kremikovtzi metallurgical plant in Bulgaria, into marketable iron-containing pellets. In the first approach the iron concentrate was recovered through a two-stage flotation process, desliming, and magnetic separation. In the second proposed process, the iron concentrate was subjected to four sequential stages of magnetic separation coupled with selective magnetic flocculation. The third route entails the not very common practice of magnetizing roasting, followed by selective magnetic flocculation, desliming, and magnetic separation. The iron concentrate was pelletized in a laboratory-scale pelletizer. Each technology has been assessed with regard to the mass yield of iron concentrate, the iron recovery. and the iron, lead, and zinc content in order to identify the most effective route. Keywords: tailings reprocessing, magnetizing roasting, pelletization.