Particle Size Distribution of Cemented Rockfill Effects on Strata Stability in Filling Mining

It is of great significance for engineering safety, economic benefits, environmental protection, and sustainable development to investigate the strata stability in filling mining with cemented rockfill. Consequently, this paper is based on a specific coal mine where we applied the fully-mechanized longwall mining and filling and designed a cemented rockfill material for which the particles satisfied the Talbot gradation. Uniaxial and triaxial compression experiments were carried out on the cemented rockfill specimen, which obtained the relations between the mechanical parameters (Poisson ratio, elastic modulus, compressive strength, cohesive force, internal friction angle, and tensile strength) and the particle size distribution of the aggregate. The excavation and filling processes in the coal seam were simulated based on the numerical software FLAC3D. The characteristics of the displacement and stress fields of the strata when the goaf was filled by cemented rockfill with different granule gradations were discussed. The influences of the particle size distribution and mining distance on the maximum subsidence displacement of the coal seam roof, internal stress of the backfill, and the stress of the rock mass in the coalface were analyzed. The feasibility and effectiveness of the filling mining with cemented rockfill to protect the integrity of the overlying strata were discussed. The results showed that optimizing the particle size distribution of the aggregate in cemented rockfill could increase the loading capacity of the backfill to improve the filling effect, effectively control the strata movement, and decrease the stress of rock mass in the coalface to reduce the potential danger.

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Particle Size Distribution Effects on the Strength Characteristic of Cemented Paste Backfill

Minerals ◽

10.3390/min8080322 ◽

2018 ◽

Vol 8 (8) ◽

pp. 322 ◽

Cited By ~ 21

Author(s):

Jiangyu Wu ◽

Meimei Feng ◽

Zhanqing Chen ◽

Xianbiao Mao ◽

Guansheng Han ◽

...

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Strength Characteristic ◽

Triaxial Compression ◽

Confining Pressure ◽

Peak Strength ◽

Strength Parameter ◽

Cemented Paste Backfill ◽

Paste Backfill

It is of great significance, for economic, environmental and security reasons, to investigate the strength characteristic of underground cemented paste backfill (CPB). Consequently, an ultrasonic test, uniaxial and triaxial compression experiment, and acoustic emission (AE) monitoring were carried out on CPB, for which the particles satisfied Talbot gradation. The homogeneity of CPB specimens was evaluated by ultrasonic pulse velocity (UPV). The stress–strain behavior and AE characteristic of CPB specimens under different Talbot indices and confining pressures were investigated. The effects of the particle size distribution and the confining pressure on the peak strength of CPB were analyzed. The strength parameter model of CPB under the coupled influence of the particle size distribution and the confining pressure was constructed based on the Mohr–Coulomb strength criterion. The results show that the peak strength of CPB is positively linear with confining pressure, however, the relationship between its strength parameters and the Talbot index can be characterized by a quadratic polynomial function. This suggests that there is an optimal gradation of particles reflected in the maximum strength of CPB.

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INFLUENCE OF PARAMETERS OF EXPLOSIVE DESTRUCTION OF MINING BLOCKS OF COMPLEX GEOLOGICAL STRUCTURE ON THE PREPARATION OF THE MINING MASS FOR PROCESSING

Metallurgicheskaya i gornorudnaya promyshlennost ◽

10.33101/s065676567 ◽

2018 ◽

pp. 68-74

Author(s):

К.V. Babii

Keyword(s):

Particle Size ◽

Rock Mass ◽

Particle Size Distribution ◽

Size Distribution ◽

Iron Ore ◽

Geological Structure ◽

Contact Zones ◽

Complex Geological Structure ◽

A Charge ◽

Explosive Destruction

Purpose: to investigate the influence of the parameters of explosive destruction of mining blocks of complex geological structure on the production processes of mining and processing of iron ore. Determine the stability of the escarpment slopes during excavation of rocks in ore mining blocks with barren layers. Results. The analysis of geophysical methods for studying the structure of deposits. It is proposed to use the magnetic susceptibility method for well logging. The structure of mining blocks of a complex geological structure with contact zones "ore - host rocks" was investigated. It has been proven that for the effective use of equipment for the pre-enrichment of ore in a quarry there are conditions: the regulation of the granulometric composition of the rock mass and the reduction of ore splices with overburden rocks. It is proposed to use a charge design of an explosive with inert gaps or a charge section of a cumulative action in the explosive destruction of rocks with contact zones. The influence of parameters of explosive destruction of mining blocks of complex geological structure on the formation of technological complexes of ore beneficiation in quarries is established. The dependence of the factor of stability of slopes of slopes during excavation of rocks, depending on the geological parameters. Scientific novelty. The regularities of changes in the parameters of the ore mass flow (medium piece and oversize) are established depending on the diameter of the drilling-blast wells, which allows you to adjust the particle size distribution. Practical significance. Based on the established patterns and improvement of the design of well charges, their influence on the quality of the blown-up rock mass in the ledges of a complex geological structure has been substantiated, which makes it possible to form the corresponding technological complexes of ore dressing in quarries. The result is a significant increase in the productivity of the technological equipment of the mining enterprise and the profitability of iron ore mining. Key words: quarry, ledge, complex geological structure, downhole charge structures, particle size distribution.

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Characterization and flowability methods for metal powders

Scientific Reports ◽

10.1038/s41598-020-77974-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Jiri Zegzulka ◽

Daniel Gelnar ◽

Lucie Jezerska ◽

Rostislav Prokes ◽

Jiri Rozbroj

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Flow Characteristics ◽

Friction Angle ◽

Angle Of Repose ◽

Flow Index ◽

Distribution Data ◽

Metal Powders

AbstractWith the rise of additive technologies, the characterization of metal powders is increasingly required. There is a need to precisely match the properties of metal powders to a specific machine and to ensure highly consistent production. Therefore, the study aims at a detailed characterization of ten metal powders (Metal powder 316 L, Zn, Sn, Al, Cu, Mn, Fe, Bronze, Ti and Mo powder), for which the particle size distribution, morphology, static and dynamic angle of repose and the effective internal friction angle (AIFE) were determined. The AIFE parameter and flow index were determined from three commonly used rotary shear devices: The computer-controlled Ring Shear Tester RST-01. pc, the Brookfield PFT Powder Flow Tester and the FT4 Powder rheometer. The results showed that the values for the device of one manufacturer did not fully correspond to the values of another one. The flow characteristics of the metal powders were quantified from the particle size distribution data, static angle of repose, and AIFE data. According to the particle size distribution and angle of repose (AOR), 50% of the tested metal powders fell into the free-flowing mode. According to the evaluation of AIFE, 20% of the samples fell into the lower area. Based on the flow indexes calculated from the measurements of the shear devices used, 100% (RST-01.pc), 70% (PFT) and 50% (FT4) of the samples were included in the free-flowing category. When comparing the results, attention should be paid not only to the nature of the material, but also to the methodology and equipment used. A comparison of methodologies revealed similarities in the changing behavior of the different metal powders. A comparison of effective angles of AIFE and static AOR was shown, and a hypothesis of the conversion relation was derived.

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Justification of parameters and technology of drilling and blasting operations to ensure the required lumpiness

Горная промышленность ◽

10.30686/1609-9192-2021-3-110-115 ◽

2021 ◽

pp. 110-115

Author(s):

V.V. Egorov ◽

A.N. Volokitin ◽

N.V. Ugolnikov ◽

A.V. Sokolovsky

Keyword(s):

Particle Size ◽

Rock Mass ◽

Particle Size Distribution ◽

Size Distribution ◽

Design Stage ◽

Production Cycle ◽

Lump Size ◽

Optimal Technology ◽

Average Size ◽

The Cost

The practice of mining and blasting operations both during the development of a mineral deposits, and at the mine design stage, often involves the question of selecting the technology options and operation parameters. Virtually all recommendations for selecting the best production option are based on minimizing the total costs for the entire technological cycle of mining activities. In most cases the optimal technology and parameters of mining and blasting operations depend on the commercial, maximum permissible and average size of the blasted rock mass, which are determined by the type and capacity of the mining haulage equipment. Therefore, the total costs will mainly depend on the commercial or average lump size and the cost of mining transport equipment. The article presents a methodology to select the best technological option for the drilling and blasting operations to obtain the optimal lumpiness (particle-size distribution) of the blasted rock. The optimal range of lumpiness is defined by the total minimum costs for the entire production cycle of mining and processing of minerals. In order to select a rational technology of drilling and blasting and to calculate their parameters it is proposed to take into account the integral criteria of lumpiness in addition to the average lump size. For this purpose, we studied the particle size distribution in the rock mass and in the muck piles.

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Methodological principles of an on-site statistical point estimation of the particle-size distribution of a rock mass

Hydrotechnical Construction ◽

10.1007/bf01425399 ◽

1982 ◽

Vol 16 (7) ◽

pp. 420-426

Author(s):

V. A. Kuznetsov

Keyword(s):

Particle Size ◽

Rock Mass ◽

Particle Size Distribution ◽

Size Distribution ◽

Point Estimation ◽

Statistical Point ◽

Methodological Principles

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Rational crushing of mineral raw materials by well charges as a factor of environmental safety of blasting works in quarries

Collection of Research Papers of the National Mining University ◽

10.33271/crpnmu/64.138 ◽

2021 ◽

Vol 64 ◽

pp. 138-153

Author(s):

V Kolesnik ◽

A Pavlychenko ◽

T Kholodenko ◽

A Kirichenko

Keyword(s):

Particle Size ◽

Rock Mass ◽

Particle Size Distribution ◽

Size Distribution ◽

Construction Materials ◽

Environmental Safety ◽

Shock Adiabats ◽

Rock Destruction ◽

Dust Emissions

Purpose. Improving the environmental safety of blasting operations in quarries for the extraction of non-metallic and construction materials based on their rational explosive crushing, aimed at reducing the effect of overgrinding, accompanied by the formation of fine fractions of materials and significant dust emissions. The research methodology provided a theoretical analysis of the destruction processes of a rock massif by well charges of explosives on the basis of calculations of shock adiabats of an explosive wave in rocks at different speeds of detonation of explosives. Experimental verification of the identified patterns was performed by assessing the quality of blasting by the particle size distribution of the rock in the collapse. Research results. The scientific and practical task of ensuring rational explosive crushing of materials in quarries with the use of elongated borehole charges has been solved. Mechanisms for the destruction of rock massifs and the peculiarities of the distribution of destruction zones by dispersed composition have been established, which contributes to the reduction of dust emissions into the atmosphere to an acceptable level of environmental safety of blasting operations in quarries. Comparative estimates of the shock load during the explosion of the explosive charge for the main rocks at different levels of the rate of detonation of charges are given. The dependence of the volume of overgrinding rock in the zone of its adjacency to the charge on the detonation velocity of explosives has been established. An experimental verification of the identified patterns in the current quarry by assessing the quality of blasting by the particle size distribution of rock mass in its collapse after experimental explosions with different parameters is done. Scientific novelty. The multiphase process of rock destruction by explosion was investigated by the calculated determination of the parameters of the shock adiabats of the blast wave in different rocks and at different detonation velocities of explosives. It is shown that during the destruction of a rock mass by the explosion of an elongated borehole charge of explosives, several specific zones of destruction are formed, the characteristics of which differ in particle size distribution. The area of controlled crushing is highlighted, where the intensity of rock destruction can be changed by adjusting the parameters of the explosive load and the area of little or almost unregulated crushing. The possibility of managing the process of dust formation and, accordingly, the level of environmental safety of blasting works in quarries for the extraction of non-metallic and construction materials is substantiated. Practical meaning. The identified patterns and provisions to reduce the effect of mineral overgrinding were used in the development of measures to improve the environmental safety of blasting in the quarry, which, in particular, provided an increase in well spacing in the range up to 3.0-3.4 m and reduce specific energy consumption from 1.27 g/cm3 to 0.97 g/cm3.

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Assessment of Water Quality and Fish Production in an Intensive Pond Aquaculture System

Transactions of the ASABE ◽

10.13031/trans.12799 ◽

2018 ◽

Vol 61 (4) ◽

pp. 1425-1433 ◽

Cited By ~ 1

Author(s):

Weijun Bao ◽

Songming Zhu ◽

Shuirong Guo ◽

Li Wang ◽

Han Fang ◽

...

Keyword(s):

Water Quality ◽

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Suspended Solids ◽

Economic Benefits ◽

Production Cycle ◽

Cost Ratio ◽

Pond Aquaculture ◽

Aquaculture System

Abstract. Pond aquaculture plays a major role in world aquaculture production, especially in China. To make pond aquaculture more precise, ecologically sound, and efficient, in this study, an intensive pond aquaculture system (IPAS) was designed and built to produce freshwater fish that are commonly reared in China. Aquatic plants and filter-feeding, omnivorous fish were used to rehabilitate the aquaculture water quality, and the particle size distribution (PSD) model of suspended solids in the pond raceways was investigated. The results showed that the water quality in the purification pond was improved compared to that in the sedimentation basins, and it was close to the water quality in the raceways, which were within the acceptable range. The number distribution of suspended solids can be described by the power law model (R2 = 0.901 ± 0.032), which can provide guidance for solids removal using different methods. Moreover, during one production cycle, economic benefits of the IPAS were also evaluated; the return on investment (ROI) of 35.69% and benefit cost ratio (BCR) of 1.36 indicated that this kind of aquaculture mode has achieved a better profit. There are many fish species in China, so developing an IPAS with a wide application range requires further study in the future. Keywords: Airlift push-water aerator, Aquatic plant, Drum filter, Intensive pond aquaculture system, Particle size distribution, Purification pond.

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