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

Author(s):  
Vadym Tarasov ◽  

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.

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9603
Author(s):  
Kateřina Kuřavová ◽  
Jan Šipoš ◽  
Petr Kočárek

Detritus (decaying organic matter) and phyllodes of mosses are two main components in the diet of groundhoppers (Orthoptera: Tetrigidae). We studied the energy balance of consumed food under laboratory conditions in the detrito-bryophagous groundhopper, Tetrix subulata (Linnaeus, 1758). The results indicated that the energy food budget of this detrito-bryophagous groundhopper was comparable to those of small herbivorous grasshoppers (Acrididae: Gomphocerinae, Melanoplinae), which have a similar energy food budget of approximately 800–1,100 J/g. T. subulata consumed four times more detritus than mosses, although both components provided similar amounts of energy (ca. 15–16 kJ/g). However, in contrast with detritus, moss fragments passed through the digestive tract without a distinct change in their mass or a loss in their energy value. We assume that moss may cause the longer retention of semifluid mass of partly digested food in the alimentary tract; hence, the digestion and efficiency of nutrient absorption from detritus could be more effective.


2020 ◽  
Vol 201 ◽  
pp. 01014
Author(s):  
Mykola Antoshchenko ◽  
Elvira Filatieva ◽  
Vladyslav Yefimtsev ◽  
Vadym Tarasov

Currently, there is no reliable regulatory framework for determining the hazardous properties of coal seams, including the propensity of coal for spontaneous combustion. Under relatively identical mining engineering and geological conditions for mining coal seams, the probability of emergency situations is determined to a large extent by the genetic properties of coal. The research methodology is based on the classical definition of metamorphism, which characterizes the change in the composition and properties of coal. The analysis involves indicators that directly or indirectly characterize the elemental composition of organic and mineral mass, chemical activity and physico-mechanical properties. This will allow to establish a specific composition and properties that contribute to the manifestation of certain hazardous properties of coal seams during mining operations. It is shown that the modern industrial classification does not take into account the change in the organic and mineral constituents of coal, which does not make it possible to use it unchanged to predict the hazardous properties of coal seams.


2010 ◽  
Vol 61 (10) ◽  
pp. 2617-2624 ◽  
Author(s):  
I. Kabdaşlı ◽  
T. Arslan ◽  
I. Arslan-Alaton ◽  
T. Ölmez-Hancı ◽  
O. Tünay

In the present study, the treatment of metal plating wastewater containing complexed metals originating from the nickel and zinc plating process by electrocoagulation (EC) using stainless steel electrodes was explored. In order to improve the organic matter removal efficiency, the effect of H2O2 addition to the electrocoagulation (the combined EC/Fenton process) application was investigated. For this purpose, a wide range of H2O2 concentrations varying between 15 and 230 mM was tested. All EC and EC/Fenton processes were performed at an initial pH of 2.6 and at an optimized current density of 22 mA/cm2. Although up to 30 mM H2O2 addition improved the EC process performance in terms of organic matter abatement, the highest COD and TOC removal efficiencies were obtained for the combined EC/Fenton process in the presence of 20 mM H2O2. Nickel and zinc were completely removed for all runs tested in the present study after pH adjustments. At the optimized operation conditions, the combined EC/Fenton process proved to be an alternative treatment method for the improvement of organic matter reduction as well as complexed metal removal from metal plating industry wastewater.


2015 ◽  
Vol 28 (2) ◽  
pp. 89-91
Author(s):  
Renata Chalas ◽  
Ewelina Mielko ◽  
Joanna Zubrzycka-Wrobel ◽  
Jakub Nowak

Abstract Calcium silicate-based materials are interesting products widely used in dentistry. The study was designed to compare the chemical reaction between analyzed two preparates and dentin during cavity lining. In our work, dentinal discs were prepared from human extracted teeth filled with Biodentine and MTA+. The samples were then analyzed by way of SEM, EDS and Raman spectroscopy. The obtained results revealed differences in elemental composition between both materials. Biodentine showed higher activity in contact with dentine. Moreover, the interfacial layer in the tooth filled by Biodentine was wider than that in the tooth filled with MTA+. The applied methods of analysis confirmed that both materials have a bioactive potential which is a promising ability.


2020 ◽  
Vol 55 (2) ◽  
pp. 155-166
Author(s):  
Mehrnaz Sadrnourmohammadi ◽  
Kenneth Brezinski ◽  
Beata Gorczyca

Abstract The effect of ozonation on the structural and chemical characteristics of natural organic matter (NOM) and its isolated humic fractions, humic acid (HA) and fulvic acid, were studied using Fourier transform infrared coupled to attenuated total reflectance (FTIR-ATR), ultraviolet/visible (UV/Vis) spectroscopy, and synchronous scanning fluorescence (SSF) spectroscopy. The results were linked to the effect of ozonation on trihalomethane formation potential (THMfp) reduction for water standards with high THM precursors. Results showed that ozonation at a dose of 1 mg ozone/mg dissolved organic carbon (DOC) was capable of reducing DOC, UV absorbance at 254 nm (UV254), and THMfp by up to 42%, 95%, and 89% for the HA water standard, respectively. The study of UV/Vis, FTIR-ATR, and SSF revealed trends showing that ozone can alter the composition of DOC in the water standards, causing a significant reduction in aromaticity. The reduction of UV254 for each ozonated sample also affirms that ozone mainly targets aromatic moieties contained in NOM. FTIR-ATR results showed that the reduction of unsaturated functional groups, including aromatic rings and C = C bonds in the water standards tested, were the main components impacted by ozone application. SSF results also revealed that ozonation decreases the fluorescence intensity of the maximum peak – as well as the whole spectra.


1967 ◽  
Vol 45 (6) ◽  
pp. 895-906 ◽  
Author(s):  
D. M. Ross ◽  
L. Sutton

Behavior patterns in the sea anemones Stomphia coccinea and Actinostala new species are described by which these animals settled preferentially on shells of Modiolus modiolus (commensal of S. coccinea) after they have been made to swim in response to the appropriate stimuli (the starfishes Dermasterias or Hippasteria, the nudibranch Aeolidia papillosa, etc.). Tentacular and oral contact without adhesion, followed by great distension of the pedal disc and some flexion of the column towards the shell, were the main components of these behavior patterns. Anemones which had been allowed to settle on other surfaces not more than 6 h previously migrated to shells which were brought into contact with the tentacles. Shells which were boiled in alkali to remove organic matter lost their capacity to elicit the response. This behavior pattern is compared with that of Calliactis parasitica, a commensal of hermit crabs which shows a preference for settling on shells of large gastropods.


1985 ◽  
Vol 22 (12) ◽  
pp. 1930-1944 ◽  
Author(s):  
Tylon O. Willingham ◽  
Bartholomew Nagy ◽  
Lois Anne Nagy ◽  
David H. Krinsley ◽  
David J. Mossman

The Elliot Lake – Blind River, Ontario, paleoplacer deposits in the basal Matineda Formation, lowermost member of the 2.25–2.45 Ga old Huronian Supergroup, contain organic matter chemically consistent with kerogen. This substance is also referred to as thucholite. Uranium ores and some gold occur here, and these minerals may be in close association with the kerogen. Two uraniferous and auriferous stratiform kerogens, obtained from the Denison Mines Limited's Denison mine and Rio Algom Limited's Stanleigh mine, have been analyzed by combined high-vacuum pyrolysis – gas chromatography – mass spectrometry and by neutron activation. The reflectances of these samples have also been determined. Related samples containing dispersed kerogen have been examined by backscattered scanning electron microscopy. The polymer-like matrix of the two stratiform kerogens consists of aromatic, alkyl aromatic hydrocarbon, and sulphur moieties and contains 20 and 32% uranium with gold abundances in the parts per billion range. The reflectances of the two stratiform kerogens are generally higher than those of the dispersed kerogens; the atomic H/C ratios of the former are −0.6 and −0.4. Backscattered scanning electron microscopy and petrographic observations reveal a complex diagenetic history. Stratigraphic position and supportive analytical data suggest that the stratiform kerogens were probably derived from ancient mats of cyanobacteria, subjected to various radiation-induced reactions, and, at least in part, were affected in a manner similar to the surrounding rocks. The latter experienced physical and chemical diagenetic reactions, which often caused repeated mineral fracturing and led to the local development of authigenic carbonates and feldspar. Some of the chemical nature and history of the stratiform kerogens resemble those of the Witwatersrand carbon seam kerogens.


2013 ◽  
Vol 388 ◽  
pp. 83-90 ◽  
Author(s):  
Ang Li ◽  
Wai Soong Loh ◽  
Kim Choon Ng

This article presents a thermodynamic framework for a lithium bromide – water absorption chiller, in which a transient model is developed to simulate the operation process. Local energy and mass balance within the main components like absorber, regenerator, condenser, evaporator and solution heat exchanger is respected to investigate the behavior of the chiller. Experimental correlations are used to predict heat transfer of the related working fluids. The cooling water is set to typical cooling tower conditions of tropical countries such as Singapore. The coefficient of performance (COP) is evaluated against a range of heat source temperatures from 75oC to 100oC. The results indicate the operation conditions of the chiller at its maximum COP is 95oC to 100oC.


2013 ◽  
Vol 37 (5) ◽  
pp. 419-426 ◽  
Author(s):  
Dalmo Arantes de Barros ◽  
José Aldo Alves Pereira ◽  
Mozart Martins Ferreira ◽  
Bruno Montoani Silva ◽  
Diógenes Ferreira Filho ◽  
...  

Mining contributes to the life quality of contemporary society, but can generate significant impacts, these being mitigated due to environmental controls adopted. This study aimed to characterize soil physical properties in high-altitude areas affected by bauxite mining, and to edaphic factors responses to restoration techniques used to recover mined areas in Poços de Caldas plateau, MG, Brazil. The experiment used 3 randomized block design involving within 2 treatments (before mining intervention and after environmental recovery), and 4 replicates (N=24). In each treatment, soil samples with deformed structures were determined: granulometry, water-dispersible clay content, flocculation index, particle density, stoniness level, water aggregate stability, and organic matter contend. Soil samples with preserved structures were used to determine soil density and the total volume of pores, macropores, and micropores. Homogenization of stoniness between soil layers as a result of soil mobilization was observed after the mined area recovery. Stoniness decreased in 0.10-0.20 m layer after recovery, but was similar in the 0-0.10 m layer in before and after samples. The recovery techniques restored organic matter levels to pre-mining levels. However, changes in soil, including an increase in soil flocculation degree and a decrease in water-dispersible clays, were still apparent post-recovery. Furthermore, mining operations caused structural changes to the superficial layer of soil, as demonstrated by an increase in soil density and a decrease in total porosity and macroporosity. Decreases in the water stability of aggregates were observed after mining operations.


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