Analysis of the Effect of Dry Magnetic Separation on the Process of Ferruginous Quartzites Disintegration

The paper considers the results of the application of dry magnetic separation on samples of ferruginous quartzites of the Kostomuksha ore field, represented by refractory ore, free-milling ore, and their mixture. The assessment of the influence of the ore texture on the technological parameters of dry magnetic separation indicates their insignificant changes: the yield of the non-magnetic product varies from 12.4 to 13.5%, and the Fetotal content in the magnetic product increases by 1.11–1.14 times. A decrease of at least 15% in the number of harmful impurities was found: S by 16.2–17.3%, SiO2 by 15.5–21.1%, and Al2O3 by 39.1–48.4%. The authors have performed a comparative assessment of the granularity of the initial ore and the magnetic product with the measurement of energy consumption, as well as an analysis of the magnetite liberation on particle sizes of less than 2 mm. It was found that due to the release of a non-magnetic product in the amount of 12.3–14.5%, represented by non-magnetite or weakly mineralized rock varieties, energy consumption for the crushing process is reduced by at least 5%. The mineral liberation assessment showed that mainly free magnetite is contained in the −0.4 mm fineness class. It was found that in the magnetic separation product of the refractory ore sample, the amount of liberated magnetite in the size class −1 + 0 mm increases by 12.1% compared to the initial ore sample. For the free-milling ore sample, the opposite trend is observed: a decrease in the amount of free magnetite by 30.9% in the magnetic product. Analysis of the magnetite liberation in the mixture indicates deterioration in the results obtained during the separate crushing of refractory and free-milling ore and a decrease in the amount of liberated magnetite in the magnetic product by 60% compared to the initial ore.

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.

Development and implementation of new generation cyclone facilities to improve efficiency of iron ore beneficiation and dust collection during its processing

Average iron content in industrial ores decreases from year to year. To use them in the processes of agglomeration and pelletizing, enrichment is necessary, accompanied by abundant emission of dust. A significant amount of iron is lost in tailings at existing magnetic enrichment technologies. Therefore, the development and implementation of new generation cyclone facilities to increase the efficiency of iron ore beneficiation and dust collection during its processing is an urgent scientific, practical and social task. The results of the of new generation cyclone facilities implementation for enrichment of iron ore and dust collection during its processing at the mining and processing factories of Kryvbas (Ukraine) are presented. It has been established that dry magnetic separation of finely crushed ore makes it possible to isolate a magnetic product with an iron content of 64-65%. The yield is up to 45%, the extraction of iron into the magnetic product is 73-75% in two-stage schemes. The degree of dust collection by the new generation cyclone facility is exponentially dependent on the speed of the cleaned flow, number and size of coaxial shells, as well as the diameter of dust particles) and is 1.23 times higher comparing with the previously used cyclone of the same size and capacity. The mobile magnetic field in the recommended cyclone allows to capture magnetic dust with an efficiency of up to 95%, and at the same time the dust is separated into a magnetic component (with an iron content of up to 65%) and a non-magnetic component (up to 12% of Fe) with an initial total iron content of up to 33%.

Perfection of a technology of processing and utilization of fine fractions of dump slag

Processing of old dumps slag at crushing-sorting facilities results in a large yield of slag fine fractions – screening. Because of high content of metal inclusions and powder-like fraction in the screening, this product often becomes unclaimed and is returned to dump. Magnetic separation can increase the consumer properties of the slag screening, but it is only magnetic product that is returned to the processing while the mineral part is left in the dump. Basic characteristics of 0–10 mm fraction quoted. It was determined by laboratory study, that after extraction of ferromagnetic inclusions, the true screening density decreased by 17.5% and bulk density – by 3.1%. The powder-like inclusions remain in the screening, that does not allow to consider the material as a filler for concrete and macadam-sand mixture for road-building. To recycle the magnetic product, extracted out of the screening, decreasing of slagging is needed, as well as systematic evaluation of sulphury inclusion content in it. It was proposed to divide the slag screening for macadam and sand fractions after maximum possible removal magnetic inclusions and powder-like inclusions. It will allow to return into the utilization a part of iron previously lost with the fraction 0–10 mm and to obtain an iron concentrate for sintering. The remained tails in the form of macadam of 5–10 mm fraction, sand 0–5 mm and meliorant with decreased iron content can be used in construction industry and agriculture. By field tests it was determined, that adding meliorants, which contain a grinded screening with oxides of magnesium, phosphor and microelements, into soil, results in increasing crop capacity of vegetables by 30% at test areas.

Grinding Behavior and Potential Beneficiation Options of Bauxite Ores

This laboratory study investigates selective grinding and beneficiation options for a Greek bauxite ore. First, a series of batch grinding tests were carried out in order to investigate the grinding behavior of the ore and the effect of the material filling volume (fc) on the distribution of aluminium- and iron-containing phases. Then, the ground ore was subjected to magnetic separation either as received or after reduction roasting in order to further explore potential beneficiation options. The results showed that grinding of the ore exhibits non-first order behavior, while the breakage rate varies with grinding time. Additionally, Al2O3 tends to concentrate in the coarser than 0.300 mm product fraction, while fc 10% and 2 min of grinding time are considered optimum conditions for good distribution of Al2O3 and Fe2O3. When different product fractions were subjected to magnetic separation, it was seen that the non-magnetic product obtained from the 0.300–1.18 mm fraction was more rich in Al2O3. In this fraction, the Al2O3 content increased from 58 wt% in the feed to 67.9 wt%, whereas the Fe2O3 content decreased from 22.4 wt% in the feed to 13.5 wt%. When the ore was subjected to a two-step treatment, involving reduction roasting followed by magnetic separation, the Fe2O3 grade decreased from 20.8 to 5.1 wt%, but in this case the recovery was very low.

Separation of Monazite from Placer Deposit by Magnetic Separation

In this study, mineralogical analysis and beneficiation experiments were conducted using a placer deposit of North Korea, on which limited information was available, to confirm the feasibility of development. Rare earth elements (REEs) have vital applications in modern technology and are growing in importance in the fourth industrial revolution. However, the price of REEs is unstable due to the imbalance between supply and demand, and tremendous efforts are being made to produce REEs sustainably. One of them is the evaluation of new rare earth mines and the verification of their feasibility. As a result of a mineralogical analysis, in this placer deposit, monazite and some amount of xenotime were the main REE-bearing minerals. Besides these minerals, ilmenite and zircon were the target minerals to be concentrated. Using a magnetic separation method at various magnetic intensities, paramagnetic minerals, ilmenite (0.8 T magnetic product), and monazite/xenotime (1.0–1.4 T magnetic product) were recovered selectively. Using a magnetic separation result, the beneficiation process was conducted with additional gravity separation for zircon to produce a valuable mineral concentrate. The process resulted in three kinds of mineral concentrates (ilmenite, REE-bearing mineral, and zircon). The content of ilmenite increased from 32.5% to 90.9%, and the total rare earth oxide (TREO) (%) of the REE-bearing mineral concentrates reached 45.0%. The zircon concentrate, a by-product of this process, had a Zr grade of 42.8%. Consequently, it was possible to produce concentrates by combining relatively simple separation processes compared to the conventional process for rare earth placer deposit and confirmed the possibility of mine development.

Insight into the adsorption mechanisms of aqueous hexavalent chromium by EDTA intercalated layered double hydroxides: XRD, FTIR, XPS, and zeta potential studies

To understand the possible mechanisms of Cr(vi) adsorption on the surface of modified LDHs, we synthesized EDTA intercalated MgAl-LDH and its magnetic product, and evaluated their adsorption performance for Cr(vi) by batch experiments.

Beneficiation Of Chromium Waste By Means Of Magnetic And Gravitational Separation

The paper presents the results of investigations of chromium recovery from the Cr waste mud, originating in the production of sodium dichromate. The differentiation of physical properties of particles of different contents of chromium and magnesium compounds is a premise for the use of physical separation methods. The investigations were performed on 2 waste samples, taken by random from the waste dump. The investigations of magnetic and gravity concentration for sample I and II were made, respectively. The results of screen and float and sink analyses of sample II indicate that it is possible to obtain Cr- and Mg-enriched products by means of a combined method of separation, i.e. hydraulic classification and, next, gravitational concentration on the shaking table. The concept of gravity concentration of the tested chromium waste was verified in the technical scale on multiboard shaking tables. The advantage of these fittings in relation to laboratory conditions is the possibility of separation of discussed waste without previous classification. The longer time of separation on the industrial shaking table as well as the respective amount of water directed to the process together with feed enabled an exact separation of initial material. The obtained concentrate in such conditions contains from 25 to 35% Cr2O3, depending on the chromium content in the initial waste material. It results from the fractional magnetic analysis of sample I that by means of the magnetic separation it is possible to obtain the magnetic concentrate of Cr2O3content minimum 20% and, simultaneously, to obtain the non-magnetic product of increased MgO content. The optimum separation conditions regarding the yield and content of Cr2O3were determined. The highest value of criterionKfor the grade of the concentrate containing over 20% of Cr2O3is obtained when the 10 mm diameter balls and the 1150 kA/m magnetic field intensity are applied. The yield of the concentrate equals about 9.5 % and recovery of Cr2O3almost 22%. In the non-magnetic product the content of Cr2O3equals 7.74% and MgO 27.36%.

Improvement of brightness of kaolin by superconducting magnetic separation and characterization of the impurities

In the present study, changes of iron content, brightness, particle size, mineralogy and paramagnetic properties of kaolins before and after superconducting high gradient magnetic separation (SHGMS) were investigated. The Fe2O3 contents of the feed decreased by 56% after 3.5T SHGMS with 1# steel wool, but higher magnetic intensity to 5.5T did not remove additional iron. The ISO brightness of the kaolin sample after SHGMS was improved from 56.9% to 76.7%. The D50 value of the magnetic rejects was 35% larger compared to the feed. Large particles might block the micro-pores in the steel wool matrix. Compared to the feed, the dark or red impurities significantly decreased in the non-magnetic product. Paramagnetic species in the kaolin sample were sensitive to SHGMS. The resonances at g = ~2.0 and g = 4.0 decreased significantly in the concentrate compared to the feed in the ESR spectra. Iron components in the non-magnetic product were more likely to be non-paramagnetic. The results are useful for understanding the SHGMS in kaolin treatment, and might be a guide for optimizing process parameters.

A Study on Magnetic Separation Washability Mathematical Model of Pulverized Coal

To further understand the magnetic separation washability of pulverized coal, washability curve and mathematical model were done based on internal relations of curves. The model included non-magnetic substance accumulated curve, ash characteristic curve and magnetic susceptibility curve mathematical model. The theoretical separation indicators and the non-magnetic product yield among the adjacent sub-selections susceptibility can be found and determined from these. We also can make a quantitative assessment of the magnetic separation washability and predict the actual results. Results showed that simulation results and experiments results can tally well according to choose reasonable parameters. Evaluation criteria of magnetic separation washability of pulverized coal has yet to make a further investigation. These indicate as a powerful tool of studying magnetic separation washability of pulverized coal can not only be qualitative reasonably but also investigate quantitatively. Key words: pulverized coal; magnetic separation; washability; mathematical model