Experimental study on forced ventilation in dead-end mine working with various setbacks of the ventilation pipeline from the working face

The study of airflow patterns at the ends of dead-end mine workings is crucial for optimizing underground mining ventilation systems. Understanding these patterns forms the basis for designing and implementing effective ventilation strategies. Previous studies have shed light on the behavior of the main vortex and the formation of stagnant zones in such environments, but these insights remain fragmented and call for a more systematic exploration to integrate them into a comprehensive theory. This paper presents the results of a thorough field investigation into the forced ventilation behavior in a dead-end mine working with a significant cross-sectional area (29.2 m2). We evaluated the impact of varying the setback distance of the ventilation duct’s end from the working face at intervals of 10, 15, 17, 19, and 21 m. The experimental design included precise measurements of turbulent airflow velocities at 25 carefully chosen points (in a 5x5 grid) for each setback distance, covering the area from the working face to beyond the end of the ventilation duct. This included additional measurements taken 1 meter and 10 meters past the termination of the ventilation duct, moving towards the entrance of the working area. The fieldwork was carried out in a typical dead-end stope at the Kupol gold-silver mine in the Chukotka Autonomous District, created by drilling and blasting. The volume of fresh air delivered to the working was maintained at a consistent rate of 17.4 m3/s across all scenarios, aligning with the mine’s standard air flow rate derived from the ventilation requirement for exhaust gases emitted by internal combustion engines of Load-Haul-Dump (LHD) machinery. With the duct’s terminal cross-sectional area at 0.8 m², this resulted in an inflow velocity averaging 21.75 m/s. Additionally, we included insights from three-dimensional numerical simulations performed in ANSYS Fluent, focusing on steady-state air movement and developed turbulence within the dead-end space. A comparative review of both empirical and modeled data shows that the ventilation jet, for all tested setback distances up to 21 m, successfully delivered air to the working face, where it then dispersed and initiated reverse flow patterns. These experiments led to the formulation of a linear relationship between the maximum relative velocity (compared to the initial jet velocity) at a distance of 1 m from the working face and a key geometric factor of the ventilation setup. This factor is the ratio of the duct’s setback distance to a characteristic dimension of the cross-sectional area, calculated as the square root of the cross-sectional area

About the productivity of shaft air heater located along the perimeter of pithead

In the existing shaft air heaters that heat the air for air suppliers in the cold season heater channel is used. Part of the air from heater goes to the channel, another one is sucked through pithead by general shaft pressure drawdown formed by main ventilation installation. Wherein, mix of two air flow leads to shaft heat regime violation that could break the pressurization of intertubular sealers. Moreover, heater channel design is associated with additional expenditures. Paper describes the air heater, located in the pithead. The location of a heater in one line along pithead perimeter is the key feature. In this case there is no need to design heater channel, thus, there is no problem with mix of cold and heated air flows. Air processing it the heater located on the perimeter of pithead and mix of cold and heated air flows in the supplier from the channel was modeled in the software Soldworks flow simulation. The comparative analysis of both types of heater proved efficiency of proposed design of installation, smooth propagation of heat field along the all cross-section of air supplier, decrease of consumption of electric power for air processing and installation operation by transformation negative natural common excavation traction to positive

Results of modelling of mine ventilation with air curtain installed into downcast and upcast shafts

Existing mine air heaters (MAH) that heat the air supplied into downcast shafts during the cold period are equipped with a heat channel. A part of the air from a MAH goes through a heat channel. Another part is sucked through a pit head by general depression created by a shaft main fan. That raises a problem of mixing of two air streams, which disturbs thermal regime in the shafts and could lead to violation of safety rules, in particular, create a breach of sealing of intertubular seals. Besides, there is a concern of energy saving during ventilation at underground mining enterprises. One of the reasons for energy efficiency reduce during air supply to a mine are external leaks appeared during ventilation by a suck method. The article presents proposed solution for both problems using air curtain. During air preparation in the cold period, it is proposed to place air curtain in an air downcast shafts above the junction of a heat channel and a shaft. That is done in order to prevent air infiltration (sucking) through a pit head. According to the paper air curtain should be used in the ventilation shaft to decrease outside air leakage in order to increase energy efficiency of a main fan performance. It is determined during mathematical modelling (in SolidWorks Flow Simulation software) of ventilation and air preparation that air curtain can increase efficiency of MAH and decrease energy consumption on ventilation

Towards effective indirect radioisotope energy converters with bright and radiation hard scintillators of (Gd,Y)3Al2Ga3O12 family

Ceramics of quaternary garnets (Gd,Y)3Al2Ga3O12 doped with Ce, Tb have been fabricated and evaluated as prospective materials for indirect energy converters of α-and β-voltaic. Samples were characterized at excitation with an X-ray source and an intense 150 keV electron beam and showed good temperature stability of their emission and tolerance to irradiation. The role of X-rays accompanied the α-particle emitting in the increase of the conversion efficiency is clarified. The garnet-type structure of the matrix in the developed materials allows the production of quality crystalline mass with a light yield exceeding that of the commonly used YAG: Ce scintillator by a factor of two times. © 2022 Korean Nuclear SocietyMinistry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2021-1353, FEUZ-2020-0060; Ministerstwo Edukacji i Nauki, MNiSW: 075-11-2021-070; Ministry of Science and Higher Education of the Russian FederationAuthors with affiliations b, d, e and f acknowledge support from Russian Ministry of Science and Education grant No. 075-15-2021-1353 . The scientific equipment provided by shared research facilities “Scientific Research Analytical Center of National Research Center “Kurchatov Institute” – IREA” was used, with financial support of Russian Federation, represented by the Ministry of Science and Higher Education, agreement No. 075-11-2021-070 dated August 19, 2021. The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project No. FEUZ-2020-0060 ) (authors with affiliation “c”).Authors with affiliations b, d, e and f acknowledge support from Russian Ministry of Science and Education grant No. 075-15-2021-1353. The scientific equipment provided by shared research facilities “Scientific Research Analytical Center of National Research Center “Kurchatov Institute” – IREA” was used, with financial support of Russian Federation, represented by the Ministry of Science and Higher Education, agreement No. 075-11-2021-070 dated August 19, 2021. The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project No. FEUZ-2020-0060) (authors with affiliation “c”)

The Saturation of the Response to an Electron Beam of Ce- and Tb-Doped GYAGG Phosphors for Indirect β-Voltaics

GYAGG:Tb (Ce) scintillators have been confirmed to be promising sources of light emission when excited by an intense 150 keV electron beam. The saturation of the scintillation yield under such excitation conditions has been studied. To explain the results obtained, a model that considers the Auger quenching mechanism was used. The Ce-doped material did not show saturation, whereas a moderate 30% drop of the yield was measured in the Tb-doped sample at the highest excitation beam intensity ~1 A/cm2. This put forward a way to exploit the Tb-doped scintillator for indirect β-voltaic batteries. © 2023 by the authors.National Research Council Canada, NRC; Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2021-1353, FEUZ 2023-0013The authors at NRC “Kurchatov Institute” and Moscow State University acknowledge support from the Russian Ministry of Science and Education, Agreement No. 075-15-2021-1353. Analytical studies have been carried out using the scientific equipment of NRC Kurchatov Institute IREA. The research at Ural Federal University was partially supported by the Ministry of Science and Higher Education of the Russian Federation (Project FEUZ 2023-0013)

Исторические аспекты и современное состояние проблемы лечения сочетанного атеросклеротического поражения коронарных и сонных артерий

In this study the primary focus will be on the problem of choosing the treatment tactic in patients with multifocal atherosclerosis. Nowadays, optimal timing of surgical interventions in these patients is controversial. In clinical practice it is usually determined by the severity of the combined coronary and carotid artery disease and the symptoms in patients. There are two main strategies: a staged approach, in which the most affected arteries are primarily revascularized, and a synchronous approach, in which carotid endarterectomy (CEA) and coronary revascularization are performed simultaneously. The presence of severe carotid artery disease is an important incremental risk factor for myocardial infraction after coronary artery bypass grafting (CABG) and needs either concomitant or staged surgical correction. In the absence of randomized controlled trials, guidelines regarding the management of these patients are based on data from single-center retrospective studies. The article indicates historical aspects and current research on multifocal atherosclerosis, as well as clinical guidelines for the management of these patientsВ работе сделан акцент на проблеме выбора тактики лечения пациентов с мультифокальным атеросклерозом. Сложность состоит в том, что на сегодняшний день объем и этапность хирургических вмешательств у данных пациентов являются спорными. В клинической практике тактику лечения определяют степень поражения коронарных и сонных артерий, а также симптоматика пациентов. Существуют две крупные стратегии лечения: этапный подход, при котором в первую очередь вмешательство происходит в наиболее пораженном бассейне, и синхронный, при котором каротидную эндартерэктомию и аортокоронарное шунтирование выполняют одномоментно во время одного наркоза. Пациенты с ишемической болезнью сердца, которым проводят каротидную эндартерэктомию, имеют высокий риск периоперационного инфаркта миокарда. В то же время атеросклероз сонных артерий увеличивает риск инсульта во время аортокоронарного шунтирования. При этом до сих пор отсутствуют крупные рандомизированные исследования, посвященные данной проблеме. В обзоре проанализированы исторические аспекты и современные исследования, посвященные мультифокальному атеросклерозу, а также клинические рекомендации по ведению данной когорты пациентов

Тонометрическое внутриглазное давление у взрослого населения: популяционное исследование

PURPOSE: To study the distribution of intraocular pressure (IOP) obtained by Maklakov tonometry in different age groups.METHODS: The study evaluated Caucasians without glaucoma aged 45-75. The participants underwent Maklakov tonometry with a 10 g tonometer at 09:00-12:00 with subsequent imprint evaluation by means of NesterovEgorov scale, measurements of central corneal thickness (CCT) and visual acuity. All the participants were divided into 3 groups by age: Group 1 consisted of participants aged 45-55, Group 2 comprised the ones aged 56-65, Group 3 included patients aged 66-75.RESULTS: In total 791 person were enrolled; 1 429 of 1 499 eyes (95.3%) were accepted into the study. IOP in Group I was 16.1±3.3 mmHg in Group 1; 16.3±3.3 in Group 2; 16.2±3.5 mmHg in Group 3. CCT in Group 1 was 545.7±14.6 μm; 545.3±15.4 μm in Group 2; 544.7±14.6 μm in Group 3. Visual acuity was 0.93±0.13 in Group 1; 0.89±0.15 in Group 2; 0.81±0.18 in Group 3. Average IOP in men was 16.4±3.3 mmHg, in women 16.5±3.3 mmHg. Age, vision acuity, CCT and IOP were within the normal distribution; IOP and CCT had no significant differences between the age groups. The measured parameters showed no significant intercorrelation. We found no significant difference between IOP in men and women.CONCLUSION: In a healthy population CCT and IOP values fall within a normal distribution and do not change significantly with age. IOP does not depend on sex. Average IOP in the studied population is 16.2±3.4 mmHg, average CCT is 545.3±15.1 μm.ЦЕЛЬ. Исследовать возрастные нормы внутриглазного давления (ВГД) при использовании тонометрии по Маклакову.МЕТОДЫ. Обследовали лиц европеоидной расы без глаукомы в возрасте 45-75 лет. Исследуемым измеряли ВГД тонометром Маклакова весом 10 грамм в период с 9:00 до 12:00 с последующей оценкой отпечатка по линейке Нестерова - Егорова, измеряли центральную толщину роговицы (ЦТР) и проверяли остроту зрения. Всех исследуемых разделили на три группы по возрасту: группа 1 — 45-55 лет, группа 2 — 56-65 лет, группа 3 — 66-75 лет.РЕЗУЛЬТАТЫ. Обследован 791 человек; из 1 499 глаз приняты 1 429 (95,3%). ВГД составило в группе 1 — 16,1±3,3 мм рт.ст.; в группе 2 — 16,3±3,3 мм рт.ст.; в группе 3 — 16,2±3,5 мм рт.ст. ЦТР составило в группе 1 — 545,7±14,6 мкм; в группе 2 — 545,3±15,4 мкм; в группе 3 — 544,7±14,6 мкм. Острота зрения составила в группе 1 — 0,93±0,13; в группе 2 — 0,89±0,15; в группе 3 — 0,81±0,18. Среднее ВГД у мужчин — 16,4±3,3 мм рт.ст., у женщин — 16,5±3,3 мм рт.ст. Возраст, острота зрения, ЦТР и ВГД имеют нормальное распределение; ВГД и ЦТР в разных группах достоверно не различаются. Наблюдаемые параметры ни в одном случае значимо не коррелируют друг с другом. Не выявлено разницы в ВГД у мужчин и женщин.ВЫВОДЫ. В здоровой взрослой популяции ЦТР и ВГД имеют нормальное распределение и не претерпевают значимых изменений с возрастом. ВГД не зависит от пола. Среднее ВГД в исследуемой популяции составляет 16,2±3,4 мм рт.ст., средняя ЦТР — 545,3±15,1 мкм

Mini-technology for obtaining aluminous cement

This article examines the feasibility of producing aluminous cement based on highly dispersed raw materials by using reverberatory electric furnaces with capacities ranging from 1.2 to 4.6 tons/day. A technology is developed for low-temperature solid-phase sintering and tests are performed on the resulting product. Recommendations are given on selecting and minimizing the cost of the necessary production equipment. An alternative sintering-based technology is also proposed, this technology involving the kiln roasting of aluminous cement in a discrete-continuous regime. © 2012 Springer Science+Business Media New York