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Date submitted2023-12-15
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Date accepted2024-06-13
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Date published2025-02-25
Development of equipment and improvement of technology for inertial thickening of backfill hydraulic mixtures at the final stages of transportation
The results of the study of the functioning of the developed thickening equipment as part of the stowing complex for the formation of a flow of high-concentration hydromixture are presented. To explain the operation of the hydrotransport system of the stowing complex, equipped with a thickener of the developed design, its basic diagram is presented. A mathematical model has been created that describes the mechanism of inertial sedimentation of a solid component of a hydraulic mixture in a working chamber equipped with hydrodynamic profiles. Interaction with the profile leads to flow stratification due to a change in the trajectory of movement and a decrease in speed. The interval of rational velocity of primary pulp entering the input of the working chamber of the inertial thickener is substantiated. The synthesis of solutions of the thickening process model is performed in the COMSOL Multiphysics and Ansys Fluent programs. This made it possible to eliminate physical contradictions in the operation of the equipment and justify the overall dimensions of its main elements, ensuring the implementation of the mechanism of inertial sedimentation of the slurry. It was found that the concentration of the thickened flow at the outlet branch pipe of the thickener working chamber is determined by the level of the primary hydraulic fluid velocity, the characteristic length of the section of interaction with the deflecting profile, and the ratio of the flow and attack angles. A nomogram of the dynamics of the change in the hydraulic fluid concentration in the section of the outlet branch pipe depending on the ratios of the overall dimensions of the deflecting profile of the working chamber was compiled. The results of the study allowed formulating recommendations for selecting the dimensions of the thickener's deflecting hydrodynamic profile to form a flow of hydraulic mixture with a concentration of about 50 % by weight. The developed equipment can be used in a stowage complex and will increase the range of supply of the stowage mixture. This is due to the fact that a flow of primary slurry with a low concentration, due to lower pressure losses, can be moved in a pipeline system over a greater distance than a flow with a high filler content. The use of a thickener at the final stage of transportation is intended to increase the concentration of the hydraulic mixture immediately before production.
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Date submitted2022-05-20
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Date accepted2023-04-03
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Date published2024-02-29
Impact of carbon dioxide on the main geotechnical quality criteria and preparation cost of cemented paste backfill
There is a global upsurge in the use of cemented paste backfill (CPB) for various mining functions. However, the cost of the Portland cement binder is prohibitive, thus warranting strategies to reduce cement usage without overly diminishing the CPB quality. Since carbon dioxide is used for patented sand moulding processes, this study is premised on that physicochemical ability of CO2 to enhance the curing of consolidated inorganic materials. It evaluated the impact of carbon dioxide on the uniaxial compressive strength UCS and preparation cost of CPB standard samples (ASTM C109). The preparation cost was delimited to the purchase cost of the Portland cement. The backfill material was silica sand tailings with 4.5 wt.% Portland cement binder and a water-cement ratio of 7.6. Distilled water of pH 5.4 was used for the control samples while variable amounts of carbon dioxide were dissolved in distilled water to generate carbonated mixing water with pH values of 3.8; 4 and 4.2. The lower the carbonated water pH, the higher is the CO2 concentration. UCS tests were conducted on the samples after curing for 3, 7, 28, and 90 days. There was an observable increase in the UCSs and reduction in curing time with increasing carbon dioxide. Samples prepared with carbonated water of pH 3.8 had almost double the strength of those prepared with pure distilled water of pH 5.4, implying that more dissolved CO2 corresponds to higher CPB strength. This is supported by the trendline equations for the graphical simulation of strength on curing time. Thus, CPB with much less binder can be expected to attain the requisite UCS if carbon dioxide is incorporated. The average reduction in Portland cement consumption was 0.61 %, which translates to a cost saving of the same percentage points. If calculated over the operational life of a mine, this is a massive saving of millions of dollars.
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Date submitted2022-05-03
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Date accepted2022-07-21
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Date published2022-11-03
Determination of rational steam consumption in steam-air mixture flotation of apatite-nepheline ores
Relevance of the study is determined by the decisions taken to increase the production volume of certain commercial products from mineral raw materials. The scale, impact and consequences of the projects on developing the resource-saving technologies for beneficiation of mineral raw materials are socially significant, and the economic growth of mining production complies with the sustainable development goals. The aim of the study is to develop the flotation circuit and mode that improve the technological performance of beneficiation of apatite-nepheline ores of the Khibiny Massif in the Kola Peninsula. The scientific idea of the work is to develop the flotation circuit, the movement of beneficiation products in which ensures a major increase in the content of the recovered component in the rougher flotation procedure with a simultaneous increase in dressability of the material. The above condition is met when mixing the feedstock with rough concentrate. Recovery of the valuable component from the resulting mixture is accomplished in a mode differing from the known ones in that the heat of steam condensation is used to increase water temperature in the interphase film between the particle and the bubble. For pulp aeration during flotation, a mixture of air and hot steam is used as the gas phase. A high recovery of the valuable component in ore flotation according to the developed circuit and mode is facilitated by increasing water temperature in wetting films due to the steam condensation heat. A high selectivity of flotation with a steam-air mixture can be explained using the concepts of a phonon component of disjoining pressure, the value and sign of which are associated with a difference in the dynamic structure of liquid in the wetting film and bulk liquid.
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Date submitted2021-10-14
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Date accepted2022-04-07
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Date published2022-04-29
The influence of the shape and size of dust fractions on their distribution and accumulation in mine workings when changing the structure of air flow
The results of the analysis of statistical data on accidents at Russian mines caused by explosions in the workings space have shown that explosions of methane-dust-air mixtures at underground coal mines are the most severe accidents in terms of consequences. A detailed analysis of literature sources showed that in the total number of explosions prevails total share of hybrid mixtures, i.e. with the simultaneous participation of gas (methane) and coal dust, as well as explosions with the possible or partial involvement of coal dust. The main causes contributing to the occurrence and development of dust-air mixture explosions, including irregular monitoring of by mine engineers and technicians of the schedule of dust explosion protective measures; unreliable assessment of the dust situation, etc., are given. The main problem in this case was the difficulty of determining the location and volume of dust deposition zones in not extinguished and difficult to access for instrumental control workings. Determination of the class-shape of coal dust particles is a necessary condition for constructing a model of the dust situation reflecting the aerosol distribution in the workings space. The morphological composition of coal mine dust fractions with dispersion less than 0.1 has been studied. Particle studies conducted using an LEICA DM 4000 optical microscope and IMAGE SCOPE M software made it possible to establish the different class-shapes of dust particles found in operating mines. It was found that the coal dust particles presented in the samples correspond to the parallelepiped shape to the greatest extent. The mathematical model based on the specialized ANSYS FLUENT complex, in which this class-form is incorporated, is used for predicting the distribution of explosive and combustible coal dust in the workings space. The use of the obtained model in production conditions will allow to determine the possible places of dust deposition and to develop measures to prevent the transition of coal dust from the aerogel state to the aerosol state and thereby prevent the formation of an explosive dust-air mixture.
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Date submitted2020-06-12
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Date accepted2020-06-12
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Date published2020-06-30
Management of hardening mixtures properties when stowing mining sites of ore deposits
Underground mining is characterized by the weakening of the bearing rock mass strata competence and the accumulation of mineral waste. The full use of subsurface resources is ensured by the use of technologies with filling voids by hardening mixtures, which requires high-quality raw materials to obtain the required strength. The deficit of the binding component can be filled with the use of granulated slags of blast-furnace process, mill tailings, ash-slags and other wastes. Most often, voids are laid by mixtures with a combination of cement and a binding component. Mixtures with ash-slag additives to cement in an equivalent amount are not inferior to the strength of the mixture only with cement, especially when grinding ash-slag. The properties of stowing rock masses when using composite binding components and inert fillers are controlled by mechanical, chemical, physical and energy effects at the stages of preparation and transportation of hardening mixtures. To obtain the active fraction of cement substitutes, disintegrators are used that apply the inertia forces of materials at a high speed of rotation with an increase in high activity indicators and lower energy costs. The components of hardening mixtures can be the majority of waste from mining and related industries, which is determined experimentally in specific conditions.
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Date submitted2017-09-10
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Date accepted2017-11-10
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Date published2018-02-22
Research of heat generation indicators of gas engines
- Authors:
- O. N. Didmanidze
- A. S. Afanasev
- R. T. Khakimov
A comprehensive strategy for reviving the production of mining industry equipment and ensuring its competitiveness includes the wide use of gas engines for various purposes. Experimental studies of the working cycle of a gas engine are one of the main tasks in determining the heat generation characteristics. To this end, indicator charts were recorded in various modes, which were subjected to analysis in order to determine the key parameters characterizing intra-cylinder processes. According to the experimental program, the maximum cycle pressure, the rate of pressure build-up, the heat generation characteristic, the first heat generation phase, the duration of the second combustion phase, and the effect of the ignition advance angle for the ignition period were determined. The results of an experimental study of the influence of gas engine working process with allowance for the change in the ignition advance angle for the ignition period are described and the parameters of the maximum cycle pressure, the rate of pressure build-up, and the heat generation characteristics are determined. In the processing of data, integral charts are constructed, the working cycle parameters are calculated, and the dynamics of the engine heat generation is determined.
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Date submitted2016-11-17
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Date accepted2017-01-12
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Date published2017-04-14
Research on regimes of limonite ore hyrdotransport for the conditions of Perdo Soto Alba plant
- Authors:
- Raul' Isk'erdo Pupo
- Al'berto Turro Breff
The paper examines regular flow patterns of high-concentrated limonite pulp with significant content of finest grains. Engineering procedures have been developed to calculate basic parameters of limonite ore hydrotransport in turbulent and structured regimes. Trustworthiness of scientific statements, conclusions and recommendations is justified by theoretical research, establishment of analytical dependences, results of laboratory and industrial experiments. Practical regularities of behavior have been identified for the coefficient of hydraulic resistance, depending on pulp density in the range 35-45 % in case of pulp flow in structured regime, as well as regularity of pressure losses in case of pulp flow in horizontal and inclined pipelines in turbulent regime.
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Date submitted2013-07-16
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Date accepted2013-09-16
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Date published2014-03-17
Stopes walls stabilization at the rich iron ore mining by the flat-back cut-and-fill method
- Authors:
- V. P. Zubov
- M. D. Morozov
- A. S. Malyutin
The most influencing the stopes walls stability factors have been determined. Physical-and-mechanical ore mass properties impact to the stopes height has been researched. Advanced ways to improve stopes walls stability have been considered.
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Date submitted2010-07-13
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Date accepted2010-09-13
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Date published2011-03-21
Actual ways of increasing the effectiveness of facilities for hydrotransport mountain companies
- Authors:
- A. A. Velnikovskiy
Shown the necessity of improving hydrotransport installations. Built a functional model of the hydrotransport system. As a result of its analysis identified the most relevant ways to improve efficiency of hydrotransport on mining enterprises.
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Date submitted2010-07-01
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Date accepted2010-09-23
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Date published2011-03-21
Improving the efficiency of system of deleting waste on Udachny GOK
- Authors:
- V. P. Dokukin
- A. A. Velnikovskiy
Examined ways to improve the efficiency of hydrotransport systems. A method for determining the most advantageous modes of GTP. The calculation of basic characteristics of the flow of pulp when the grain size, density and quantity released to the enrichment of solid material to installation hydrotransport concentrator.
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Date submitted2009-08-22
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Date accepted2009-10-19
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Date published2010-02-01
The substantiation of reinforcing support of preparation mines in the ore massive of the Yakovlevskiy deposit
- Authors:
- Yu. N. Antonov
- V. Yu. Sinegubov
The paper justifies a design of reinforcing mine support of the protective roof at the priority high-grade ore mining site of the Yakovlevskiy deposit. Experience of mine roadway support with the KMP-A3 standing support has been analyzed. A reinforcing support is offered consisting of rock bolts back bracing the ore exposure, which best fits with continuous miner roadheading and consolidating stowing (concrete).