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Date submitted2023-01-16
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Date accepted2023-06-20
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Date published2024-04-25
Study on the thin layer drying and diffusion mechanism of low rank coal in Inner Mongolia and Yunnan
Coal is one of the world's most important energy substances. China is rich in coal resources, accounting for more than 90 % of all ascertained fossil energy reserves. The consumption share of coal energy reaches 56.5 % in 2021. Due to the high moisture content of low-rank coal, it is easy to cause equipment blockage in the dry sorting process. This paper considers low-rank coal coming from Inner Mongolia (NM samples) and Yunnan (YN samples). The weight loss performance of the samples was analyzed using thermogravimetric experiments to determine the appropriate temperature for drying experiments. Thin-layer drying experiments were carried out at different temperature conditions. The drying characteristics of low-rank coal were that the higher the drying temperature, the shorter the drying completion time; the smaller the particle size, the shorter the drying completion time. The effective moisture diffusion coefficient was fitted using the Arrhenius equation. The effective water diffusion coefficient of NM samples was 5.07·10–11 - 9.58·10–11 m2/s. The effective water diffusion coefficients of the three different particle sizes of YN samples were 1.89·10–11 - 4.92·10–11 (–1 mm), 1.38·10–10 - 4.13·10–10 (1-3 mm), 5.26·10–10 - 1.49·10–9 (3-6 mm). The activation energy of Inner Mongolia lignite was 10.97 kJ/mol (–1 mm). The activation energies of Yunnan lignite with different particle sizes were 17.97 kJ/mol (–1 mm), 33.52 kJ/mol (1-3 mm), and 38.64 kJ/mol (3-6 mm). The drying process was simulated using empirical and semi-empirical formulas. The optimal model for Inner Mongolia samples was the Two-term diffusion model, and Yunnan samples were the Hii equation was used.
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Date submitted2022-04-20
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Date accepted2022-07-21
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Date published2022-11-03
Iron ore beneficiation technologies in Russia and ways to improve their efficiency
- Authors:
- Aleksei E. Pelevin
Increasing the efficiency of crushing circuits is associated with a decrease in the particle size of finely crushed ore and the use of dry magnetic separation of crushed ore. Reducing grinding costs is achieved by using drum mills jointly with mills of other designs. The use of automation systems, slurry demagnetization, technologies with staged concentrate separation, and beneficiation and fine screening in a closed grinding cycle lead to a reduction in grinding costs. The main industrial technology for improving the quality of concentrate is its additional beneficiation using regrinding, fine screening, flotation, and magnetic-gravity separators. Increasing the integrated use of iron ore raw materials is associated with an increase in the yield of iron concentrate and the production of hematite concentrate during the beneficiation of hematite-magnetite ores and ilmenite concentrate during the beneficiation of titanomagnetite ores. Incremented concentrate yield is possible by using magnetic separators with an increased magnetic induction up to 0.25-0.5 T in the first stages of beneficiation. To obtain hematite and ilmenite concentrates, combined technologies can be used, including fine screening, high-gradient magnetic, gravity, flotation, and electrical separation.
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Date submitted2022-05-17
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Date accepted2022-09-06
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Date published2022-11-03
Methodological substantiation of the choice for optimal modes of equipment operation during the stage-wise concentrate removal in iron ores beneficiation
- Authors:
- Alexandr S. Opalev
- Svetlana A. Alekseeva
The urgent task of improving the quality of iron ore concentrates was studied. We propose to use the stage-wise removal of the concentrate by combining fine screening, regrinding, and magnetic-gravity separation. Exemplified by magnetite ore from the Stoilensky GOK, a scientific and methodological approach to the search for optimal separation parameters and modes was substantiated. It includes several stages: studying the particle size distribution and release of useful components in the feed product to select classification parameters; a series of experiments on grinding oversize products to diverse sizes; beneficiation of the obtained products by MG separation. To select the optimal parameters of ore preparation, an analysis of the beneficiation efficiency was used, which is calculated according to the Hancock – Luyken criterion. The results of the research are experimental dependences that connect the process parameters of beneficiation with those of fine vibratory screening. For the studied ferruginous quartzite ore processed at the Stoilensky GOK, the obtained dependences can be described by a second-order polynomial with a high accuracy of approximation. The best performance is achieved with a particle size of 0.1 mm: Fe tot content in the concentrate is 69.7 %, recovery is 85 %, classification efficiency is 80.4 %. The top size of the product in this case is 0.076 mm, which corresponds to 70-73 % grinding size of –0.045 class.
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Date submitted2022-05-17
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Date accepted2022-09-06
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Date published2022-11-03
On the need to classify rock mass fed to dry magnetic separation
The hypothesis of a possible use of dry magnetic separation is substantiated on the example of ores from ferruginous quartzite deposits operated by plants of PAO “Severstal” Holding. Size class of ore after medium crushing is –80+0 mm when the vibrating feeder is used for feeding ore mass to the separation zone. The rationale is based on the analysis of video recording of physical simulation on a laboratory drum magnetic separator of SMBS-L series, in the VSDC Video Editor, and simulation modelling of dry magnetic separation on its virtual prototype in Rocky DEM software package. It has been proved that the use of a vibrating feeder for feeding the material to the working area of a magnetic separator makes it possible to: form a monolayer on the surface of the vibrating feeder chute with a thickness close to the maximum size of a lump of separated ore; implement batch feed of material to the separation zone; increase the spacing between lumps in the separation zone when passing through the free fall area, thereby allowing dry magnetic separation of ferruginous quartzites of size class –80+0 mm without pre-preparation.
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Date submitted2022-06-17
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Date accepted2022-10-18
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Date published2022-11-03
Scientific experimental bases for dry beneficiation of mineral ores
The article presents the results of research on the development of processes and equipment for ore preparation and pneumatic dry beneficiation of mineral ores. The methods of crushing and grinding before enrichment of minerals have been considered, dry enrichment of geomaterials is investigated. Highly efficient prototypes of beneficiation equipment are developed and tested: crushers of multiple dynamic impact RD-MDV-900, DKD-300, centrifugal grinders CMVU-800 and VCI-12, pneumatic separator POS-2000. Fundamental designs are created, and a number of new ore preparation and pneumatic beneficiation instruments are being designed. The efficiency of approbation of an autonomous dry beneficiation complex with new safe environmental standards for the processing of gold-bearing ores, which makes it possible to fully release and extract free gold with a particle size from 10,000 to 100 µm, is shown. The introduction of the dry beneficiation method is very promising for the mining industry. It will allow to reduce capital costs for the construction of stationary beneficiation plants, completely or partially withdraw from the use of process water, the construction of a water supply system, a traditional tailing dam, etc.
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Date submitted2022-06-27
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Date accepted2022-09-09
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Date published2022-11-03
Study of the composition and properties of the beneficiation tailings of currently produced loparite ores
The increase in demand for rare earth metals and the depletion of natural resources inevitably causes the need to search for alternative unconventional sources of rare metal raw materials. The article presents the results of a study of the composition and properties of the beneficiation tailings of currently produced loparite ores. Sieve, mineralogical, chemical, and radionuclide analyses were carried out. The average content of loparite in tailings was determined. Using scanning electron microscopy, minerals-concentrators of rare earth elements in the loparite ore beneficiation tailings were diagnosed. The distribution of valuable components and thorium in the tailings was determined depending on the particle size class. The radium-thorium nature of radioactivity was established, the values of the effective specific activity of the samples were calculated. We concluded that it is necessary to develop an integrated technology for processing the beneficiation tailings of loparite ore, due to the complex and heterogeneous mineral and chemical composition of the tailings material.
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Date submitted2021-02-20
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Date accepted2021-05-21
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Date published2021-09-20
Analysis of the screw press mouthpiece parameters for 3D extrusion of peat pieces of tubular type
The results of theoretical and experimental studies on the creation of a screw press composite mouthpiece screw press for 3D-forming of peat pieces of a tubular type in the field for intensifying the process of field drying of material in a complex mechanized pit are presented. The main purpose of the study was to substantiate the geometric and design parameters of the screw press composite mouthpiece of the spread machine for the production of peat-agglomerated products of the tubular type. The parameters of the mouthpiece are selected based on the geometric characteristics of the peat pieces. An increase in moisture loss during drying of peat-agglomerated products is provided by forming a peat piece in the form of a thick-walled pipe made of a peat raw materials composed of low and high decomposition degrees in a ratio of 1:3. Additive production of polymer-fiber peat composites by extrusion allows to produce products with improved mechanical properties in comparison with non-reinforced raw materials. The vertical arrangement of the peat tubular piece on the drying field allows to increase the loading of the field area by 10 %, increase the convective heat supply to the piece and reduce the contact coefficient of the piece with the field by three times in comparison with the peat spreading of the pieces in the form of a horizontal tape. Based on the analysis of the shape and size of the agglomerated products, the design of a screw press composite mouthpiece consisting of two conditional molding zones of various configurations has been developed. The article presents a parametric analysis of the volumetric productivity of a screw press with a composite mouthpiece of a tubular type, the energy intensity of mechanical processing is determined, the degree of mechanical processing of peat raw materials is estimated with the optimization of the screw parameters for the production of agglomerated products of a tubular type.
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Date submitted2017-12-28
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Date accepted2018-03-03
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Date published2018-06-22
Special features of a structure of technical operations for peat excavation with stage dewatering
- Authors:
- E. A. Kremcheev
A method of development of a technology of peat extraction for intensifying of dewatering which involves drying of peat raw materials in thick layers with a layer-by-layer harvesting into large-sized roll with further delivery to the field storage unit of the enlarged sizes is presented in the paper. Throughout the year storage raw materials may be transported to the customer or to the shopfloor for further processing. Considering dimension and mass characteristics, a crumbed peat of various moisture capacity is a major type of products to be of high demand. On the basis of the results of scientific studies regarding gravity dewatering of peat and its drying in field environment, the ways of intensifying of field dewatering of peat for extraction at shallow-peat lands and fine-limit fields are proposed. The presented results of the experimental performance of a technology of peat drying in thick layers with a layer-by-layer harvesting indicate an increase of seasonal harvesting and a decrease of the influence of unfavorable meteorological factors on the stability of the extraction process. Performed investigations allowed to develop a structure of technical operations for peat excavation with the stage dewatering in spreading and intermediate storage units providing rational state of the extraction process regarding a complex of technical factors. A suggested scheme of a process area for a primary and secondary period of deposit exploitation by a technology of peat excavation is considered.
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Date submitted2015-10-19
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Date accepted2015-12-27
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Date published2016-08-22
Key directions in processing carbonaceous rocks
- Authors:
- T. N. Aleksandrova
Mathematical statistics techniques and the data from laboratory mineral and technological studies of samples were used to identify the most common natural and technological associations of microelements in carbonaceous rocks which could be of industrial value if extracted in the form of commercial products. The discovered structures of spheroidal and ring ferrocarbonaceous clusters are respective formations of the class of metal fullerens with expressed magnetic properties. Such clusters may serve as construction blocks for new magnetic structures since each of them is a separate magnetic domain. Extracting such structures and their practical use opens the way to future technologies. It is expected to employ such results in the future in the course of designing new techniques and technologies for benefication of carbonaceous raw materials while developing comprehensively solid mineral resources in the mining industry regions of Russia.