scholarly journals ON DETERMINING THE COAL CARBONIZATION INDICATOR FOR ESTABLISHMENT OF MINE FIRE HAZARD GROUPS

2020 ◽  
Vol 1 (154) ◽  
pp. 306-311
Author(s):  
М. Antoshchenko ◽  
V. Tarasov ◽  
О. Zakharova ◽  
A. Petrov ◽  
A. Zakharova
Keyword(s):  
Carbon Content ◽  
Oxygen Content ◽  
Entire Range ◽  
Fire Hazard ◽  
Functional Dependence ◽  
Organic Mass ◽  
Mining Operations ◽  
Mine Fire ◽  
Endogenous Fire ◽  
Main Components

The article analyzes the dependence of endogenous fire hazards on the following factors: the degree of coalification, the total sulfur content, the thickness of the developed formations and their structure, the presence of tectonic disturbances. By the genetic propensity of coals to spontaneous combustion, three groups of coal sites are distinguished: І – Vdaf ≥ 41%, Сп ≤ 7, coals of marks D and partially G; ІІ – Vdaf = 40-30%, Сп ≤ 8, coals of marks D and partially F; ІІІ – Vdaf < 36%, Сп >8, coals of marks Zh, K, OS, T. Studies have shown that individual dependences of the decrease in the content of each component (Оo, Нo, No) significantly differ from each other. Decrease in oxygen content, as well as the sum of the main components, occurs with an increase in carbon content. The sum of the content of the main components decreases inversely to the increase in carbon content over the entire range of coal conversion from a small degree of their metamorphism (Со ≈ 70%) to anthracites (Со ≈ 98%). The dependence of decrease in oxygen content with increased carbon is nonlinear. With carbon content of more than 88%, there is a slight decrease in the rate of oxygen reduction in comparison to its decrease at earlier stages of metamorphism. Data analysis showed an almost functional dependence between the sum of the main components of the organic mass (0.995). A significant correlation of carbon with oxygen and hydrogen is observed. A significant scatter of points in experimental data is due to the diversity of composition of the source material, the conditions of its accumulation and transformation for different coal basins and individual coal sites. Studies have shown that the relationships between all the main components of the organic mass of coal during metamorphic transformations change significantly at different stages of these processes. The established dependence of the carbonization index on the carbon content at different stages of coalification allowed us to develop an engineering method for calculating the carbonization index for the entire range of coal metamorphism. The proposed method significantly clarifies the determination of the carbonization index, which is necessary not only for establishing the fire hazard of mine layers, but also for establishing other manifestations of the dangerous properties of coal sites during mining operations. Keywords: carbonization index, endogenous fire hazard, elemental composition, organic mass, metamorphism, coalification.

scholarly journals Metamorphism Indicators for Establishing the Endogenic Fire Hazard of Coal Mining Plants in Mining

2021 ◽  
Vol 12 (8) ◽  
pp. 242-248
Author(s):  
V. Tarasov ◽  
◽  
M. Antoshchenko ◽  
Ye. Rudniev ◽  
O. Zolotarova ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Content ◽  
Coal Mining ◽  
Oxygen Content ◽  
Entire Range ◽  
Spontaneous Combustion ◽  
Fire Hazard ◽  
Small Degree ◽  
Wide Range ◽  
Main Components

In coal mining, the problem of particular importance is the occurrence of endogenous fires and explosions of the methane-air mixture, which lead to the death of people. The aim of the study is to establish indicators that directly characterize the change in the elemental composition in the process of metamorphic transformations of coals and determine them tendency to spontaneous combustion. Statistical multivariate analysis showed that the degree of metamorphism is the most significant characteristic of the propensity of coal to oxidize. The sum of the content of the main components decreases inversely to the increase in carbon content over the entire range of coal conversion from a small degree of their metamorphism from coal to anthracites. The dependence of decrease in oxygen content with increased carbon is nonlinear. With carbon content of more than 88%, there is a slight decrease in the rate of oxygen reduction in comparison to its decrease at earlier stages of metamorphism. A significant correlation of carbon with oxygen and hydrogen is observed. A characteristic feature of coals containing up to 75% carbon is a wide range of changes in formation moisture and oxygen content in organic matter. It indicates minor transformations of coals at the early stages of metamorphism. One of the signs of an increase in the influence of metamorphic processes is a one-sided increase in the carbon content in organic matter and a functional decrease in the sum of the remaining components - hydrogen, nitrogen, sulfur and oxygen.

The current state of the problem of predicting spontaneous combustion and explosiveness of sulfide ores and host rocks at a depth of more than 1500 m.

2021 ◽  
pp. 77-80
Author(s):  
Z.G. Ufatova
Keyword(s):  
Moisture Content ◽  
Air Temperature ◽  
Initial Phase ◽  
Spontaneous Combustion ◽  
Fire Hazard ◽  
Free Access ◽  
Sulfide Ores ◽  
Working Face ◽  
Time In Treatment ◽  
Endogenous Fire

The mining factors of ore fire hazard during mining of the lower horizons of the Oktyabrskiy and Talnakhskiy northern deposits are considered. It is noted that the probability of self-heating of sulfide ores and the sulfide dust’s tendency to spontaneous combustion and explosiveness in certain sections of rich sulfide copper-nickel ores are quite high. The oxidation of sulfide ores occurs continuously due to the absorption of oxygen from the mine atmosphere and is accompanied by the release of heat. The oxidation can be accompanied by intense heating of the ore in mining conditions, with the accumulation of large volumes of broken rock mass for a long time in treatment and preparation workings and with free access of air to the bulk of the ore mass. The processes of ore and rock oxidation are especially intense when their moisture content is 1–4%. When the ore is heated above 35 °C, sulfurous gas (SO2) may be released. The main signs of the above-mentioned oxidative processes’ development and signs of the initial phase of a possible underground endogenous fire are indicated along with a constant increase in the temperature of the air coming from the bottom of the face. It is noted that in case of detecting at least one of the signs of a possible underground endogenous fire’s initial phase, urgent measures are taken to improve the ventilation of this working face, to ensure maximum intensity of shipped ore from the fresh stream and the content of sulfurous gas and hydrogen sulfide and mine air temperature are determined every 4 hours. If after two days on the outgoing stream there is no decrease in the content of sulfur dioxide and air temperature, then it should be considered that an endogenous fire has occurred. Measures for the prevention, localization and elimination of foci of spontaneous combustion are given. As an additional safety measure, it is recommended to moisten the dust, since sulfide dust becomes non-explosive at a moisture content of 9–9,5%, and at a humidity of 10% the dust does not transmit an explosive impulse.

Influence of Oxygen and Boron on Defect Production in Irradiated Silicon

1987 ◽  
Vol 104 ◽  
Author(s):  
P. J. Drevinsky ◽  
C. E. Caefer ◽  
S. P. Tobin ◽  
J. C. Mikkelsen ◽  
L. C. Kimerling
Keyword(s):  
Carbon Content ◽  
Oxygen Content ◽  
Boron Concentration ◽  
Electron Trap ◽  
Hole Trap ◽  
Defect Production ◽  
Interstitial Defects ◽  
Defect Reactions ◽  
P Type ◽  
Initial Results

ABSTRACTIntroduction rates of dominant defects have been determined for electron-irradiated, p-type silicon as a function of oxygen and boron concentration. Samples included those with oxygen content ranging from 8 × 1015 to 7 × 1017 cm−3. Initial results are described for samples with measured carbon content varying from 2 × 1015 to 6 × 1016 cm−3. Competing defect reactions involving the interstitial defects, Bi and Ci, and oxygen, boron, and carbon are observed. The identities of an electron trap (Bi-Oi) and a hole trap (Bi-Bs) have been clarified.

scholarly journals ON SUBJECT TO FORECAST CAUSAL FACTORS FOR SPONTANEOUS FIRES IN COAL MINES

2020 ◽  
Author(s):  
Vadym Tarasov ◽  
Keyword(s):  
Organic Matter ◽  
Elemental Composition ◽  
Analytical Data ◽  
Chemical Activity ◽  
Spontaneous Ignition ◽  
Mining Operations ◽  
Carbonization Process ◽  
Coal Beds ◽  
Operation Conditions ◽  
Main Components

Regulations for assessment of workable bed hazardous characteristics during the mining operations include the coal metamorphic grade classification indices borrowed from the industrial classifications without any proper scientific justification. For true forecasting the workable bed hazardous characteristics during the mining operations, the method to detect the metamorphic grades by changing the content of main components and moisture in the organic matter has been developed. Purpose. Development of the forecasting technique logical sequence for workable bed liability to spontaneous ignition in different stages of coal metamorphic conversion and their chemical activity during the mining operations. Methods. They are based on assumption of spontaneous fires with three blocks of factors independent of each other. The factors of block one describe the chemical activity of coals. They are defined by their elemental composition and properties at the different stages of bed metamorphic conversion. The second group of impacting factors characterizes the mining and geological conditions of bedding. It includes the coal beds position relative to each other, their occurrence depth, thickness and degree of inclination, presence of geological breaches and adjacent strata properties. The factors of block three is independently connected with the mining operation conditions. The forecasting technique for workable bed liability to spontaneous ignition avoids any stable correlation relationships between the factor parameters of three blocks under consideration. It allows separate consideration of each block and avoid their random correlations with factors of other blocks. Results. The statistical processing result analysis of more than 1000 coal samples with carbon content of 80÷94% has allowed establishing the relationship between the organic matter components and total moisture, as well as their share of participation in carbonization process that reflects the Donets Basin coal metamorphic conversions. Compliance of the initial data with analytical data of different coal deposits has been established. For the first time, the technique has been developed; and organic matter separate components and total moisture participation shares in coal carbonization process indices creation, which is one of evaluation criteria for workable bed metamorphic conversion degree for different deposits, have been established. The revealed regularities of change ambiguity for organic matter elemental composition components and their different participation shares together with the moisture in carbonization process have allowed establishing the distinctive features of the coal metamorphic conversion different stages for true forecasting the workable bed hazardous characteristics during the mining operations. In the course of this approach, the real chemical activity of coals is established by their elemental composition in different stages of bed metamorphic conversions; certain places of long-term contacts between the mine air and coal are differentially forecasted in the mine field. It enables the enhanced automated monitoring of mine air condition and revealing of spontaneous combustion places in early stages of their creation. Scientific novelty. The pattern of change for classification indices of coal industrial classification has been revealed to establish the workable bed hazardous characteristics during the mining operations. Practical relevance. Opportunity to improve the regulatory framework for safe processing of workable beds by establishing the interrelation between fossil coal metamorphic conversions and their elemental composition.

scholarly journals Preliminary results of tests on nitrogen cushion for combating fire hazard in longwalls rich in methane

2020 ◽  
Vol 174 ◽  
pp. 01066
Author(s):  
Dawid Szurgacz ◽  
Leszek Sobik ◽  
Jarosław Brodny ◽  
Maxim Grigashkin
Keyword(s):  
Fire Hazard ◽  
Main Idea ◽  
Extraction Process ◽  
Coal Extraction ◽  
Hard Coal ◽  
High Tendency ◽  
Preventive Actions ◽  
Wide Range ◽  
Endogenous Fire ◽  
Roof Support

Ventilation hazard is the most dangerous phenomena occurring in the hard coal extraction process. This particularly applies to endogenous fire hazard. In order to reduce it, it is necessary to improve the effectiveness of preventive measures. Hence this paper presents new solutions that substantially improve fire prevention effectiveness. The main idea is to develop and create an additional nitrogen cushion in the zone behind the powered roof support operating in a longwall face. The solution is based on installations for inerting of goafs and sections of the powered roof support. The nitrogen cushion restricts the access of air and oxygen to the area of goafs and limits the possibility of fire. Practical application of the developed solution allowed for effective reduction of fire hazard in conditions of a very high tendency of coal to self-ignite at short incubation period. This, in turn, enables safe exploitation and decommissioning of the longwall. Undoubtedly, the solution presented and the results obtained constitute a new approach to preventive actions in mines. It is the result of the work of theoretical and practical researchers. The solution is a combination of the potential of these two environments. The developed solution should find wide range of applications in the areas where endogenous fire and methane hazards occur.

Using pillar-free mining technologies in gently dipping and self-ignitable coal seams

2020 ◽  
pp. 64-77
Author(s):  
D. D. Golubev
Keyword(s):  
Fire Hazard ◽  
Coal Pillar ◽  
Kuznetsk Coal ◽  
Coal Seams ◽  
State Behavior ◽  
Mining Depth ◽  
Study Results ◽  
Endogenous Fire ◽  
Determination Of Parameters ◽  
Coal Seam Thickness

Gently dipping coal seams of the Kuznetsk Coal Basin are cut exclusively by longwalls with preliminary drivage of twin gate ways. At the same time, the source of self-ignition in mines is pillars of coal left in mined-out areas. Endogenous fire hazard grows with higher losses of loose coal in mined-out areas due to a persistent increase in mining depth and in size of longwalls. This research aims at development of an alternative mining technology for gently dipping coal seams to reduce the risk of initiation of self-ignition sources in mined-out areas and at the determination of parameters of the technology elements as functions of coal seam thickness and mining depth. A new concept of preparatory works and actual mining in selfignitable coal seams is described. The study results obtained with numerical modeling of the stress-state behavior of rock mass and the developed technology elements at different stages of longwalling are presented. The studies show that endogenous fire hazard is reduced by means of extraction of coal pillar on the same line with face and due to elimination of aerological connection between the operating longwall and earlier mined-out area owing to construction of a separation belt made of solidifying materials between them. The cross-effect of the widths of the solidifying material belt and coal pillar as the elements of the developed technology is estimated.

Modern methods to reduce evaporation and ensure safety when storing petroleum products in tanks

2021 ◽  
Vol 94 ◽  
pp. 65-75
Author(s):  
A. M. Kuzminskaya ◽  
◽  
M. V. Buzaeva ◽  
O. V. Ageeva ◽  
◽  
...  
Keyword(s):  
Negative Impact ◽  
Fire Hazard ◽  
Chemical Properties ◽  
Petroleum Products ◽  
Oil Refining ◽  
Chemical Additives ◽  
Long Term Storage ◽  
Main Components ◽  
Term Storage

Introduction. With long-term storage of gasoline in large-capacity tanks, the problem associated with their volatility becomes urgent. Evaporation of petroleum products and gasoline leads to a change in their physical and chemical properties, a decrease in the yield of light petroleum products during oil refining, and a deterioration in the performance characteristics of engines. In this regard, it becomes difficult to start engines, their reliability, fuel consumption increases and the service life is reduced. Lost light hydrocarbons pollute the environment and increase the fire hazard of enterprises. The aim of the work is to identify effective, inexpensive and safe methods for reducing the volatility of oil products, including gasoline, when stored in tanks. Research methods. A retrospective analysis of studies on the problems of reducing losses of petroleum products during their storage, transportation and use is carried out. Technical and organizational methods for reducing the evaporation of fuels and the use of chemical additives as an inexpensive and effective method for solving the problem of the volatility of gasolines are considered. The conclusion about the efficiency of using chemical additives to fuels to reduce volatility has been substantiated. Results and their discussion. Conclusions are made about the possibility of using surfactants as additives to reduce the evaporation of gasolines during long-term storage in tanks. The analysis of the main components and methods for the synthesis of surfactant compositions capable of creating a surfactant film at the liquid-atmosphere interface, which protects the liquid from evaporation. Conclusion. Reducing the volatility of gasoline with the use of inexpensive and effective additives introduced into the fuel in small quantities, not only reduces the explosion and fire hazard during storage in large tanks, reduces losses, but also prevents the negative impact on the environment from the ingress of low molecular hydrocarbons into it. Key words: volatility of petroleum products, losses during storage of gasoline, methods of reducing volatility, additives.

Influence of Smoke on Metallographic Structure of Short Circuited Melted Mark

2012 ◽  
Vol 591-593 ◽  
pp. 945-948 ◽  
Author(s):  
Lian Tie Wang ◽  
Wei Gao
Keyword(s):  
Grain Size ◽  
Carbon Content ◽  
Oxygen Content ◽  
Grain Shape ◽  
Short Circuit ◽  
Element Distribution ◽  
Gas Composition ◽  
Metallographic Structure ◽  
Smoke Particles ◽  
Normal Environment

When fire breaks out, the gas composition and concentration as well as smoke concentration of burning part vary from those in normal environment. The gas and smoke absorbed during solidification of short circuited melted mark occurred in such environment will certainly have an effect on grain shape, grain size, holes distribution and impurity element distribution of organization of melted mark. The gas in the environment has a certain influence on the organization of short circuited melted mark, but the influence is smaller than that of smoke. The reason may be that the gas is mingled with certain amount of tiny smoke particles inevitably which play a role in the solidification of melted mark. Compared with short-circuit samples in normal atmosphere, carbon content of short-circuit samples increases and oxygen content decreases in the environment of smoke.

Continuous automatic measurement of the temperature, oxygen content, and carbon content in melting steel in a two-bath furnace

Metallurgist ◽  
1973 ◽  
Vol 17 (6) ◽  
pp. 422-425
Author(s):  
V. A. Vanchikov ◽  
I. M. Konovalov ◽  
Yu. I. Bulatov ◽  
E. A. Nechaev ◽  
V. I. Krasovitskii
Keyword(s):  
Carbon Content ◽  
Oxygen Content ◽  
Automatic Measurement ◽  
Bath Furnace
Sign in / Sign up

Export Citation Format

Share Document