scholarly journals The Method of Combating Coal Spontaneous Combustion Hazard in Goafs—A Case Study

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4538 ◽  
Author(s):  
Dawid Szurgacz ◽  
Magdalena Tutak ◽  
Jarosław Brodny ◽  
Leszek Sobik ◽  
Olga Zhironkina
Keyword(s):  
Carbon Dioxide ◽  
Chemical Composition ◽  
Fire Hazard ◽  
Basic Element ◽  
Original Method ◽  
Water Mixture ◽  
Effective Response ◽  
Endogenous Fire ◽  
Large Material ◽  
High Level

One of the major natural hazards occurring during the process of mining exploitation are endogenous fires. They cause very large material losses and constitute a threat to the health and life of the workers. Such fires usually start and develop in the goafs. The remaining coal and the oxygen-containing air flowing at a certain rate may lead to endogenous fires. The basic element of the assessment of the occurrence of an endogenous fire and the degree of its development is the chemical composition of the air flowing out of the longwall and the goafs. The monitoring of this composition also makes it possible to assess the severity of such a fire. The damage that can be caused by the endogenous fire requires scientific and experimental research being carried out on a wide scale in order to limit its occurrence and development. All papers and research mentioned in the paper aim to find a tool that will help to control the fires. The paper discusses the development of a new and original method of combating the threat of endogenous fires. It is based on the installation designed to feed an ash and water mixture or an ash and water mixture with carbon dioxide to goafs. The foundation of the paper is a method based on a vast depth of expertise and knowledge gained by the authors in the field of combating endogenous fires. The developed installation prepares and transports ash and water mixtures together with carbon dioxide to the zones with high probability of endogenous fires. The mixture is a preparation of the surface of a mine, and later, it is transported underground by pipelines to the goafs where a high level of the fire hazard was identified. The construction of the system and the composition of the mixture used are both original solutions; their practical application limited the process of spontaneous heating of coal. Monitoring the chemical composition of gases in the air of the goafs made it possible to control the effects of applied measures; it proved that carbon dioxide used as an inert gas disturbs the process of carbon oxidation, and the water and ash mixture limits the inflow of the air with oxygen. The advantage of the method is particularly evident in the case of the exploitation of deposits where coal has a short incubation time. This original approach allows for a better and more effective response to endogenous fires.

scholarly journals Influencing Factors of the Mineral Carbonation Process of Iron Ore Mining Waste in Sequestering Atmospheric Carbon Dioxide

2021 ◽  
Vol 13 (4) ◽  
pp. 1866
Author(s):  
Noor Allesya Alis Ramli ◽  
Faradiella Mohd Kusin ◽  
Verma Loretta M. Molahid
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Chemical Composition ◽  
Iron Ore ◽  
Divalent Cations ◽  
Mining Industry ◽  
Mining Waste ◽  
Aluminum Silicate ◽  
Mineral Carbonation ◽  
Carbonation Process

Mining waste may contain potential minerals that can act as essential feedstock for long-term carbon sequestration through a mineral carbonation process. This study attempts to identify the mineralogical and chemical composition of iron ore mining waste alongside the effects of particle size, temperature, and pH on carbonation efficiency. The samples were found to be alkaline in nature (pH of 6.9–7.5) and contained small-sized particles of clay and silt, thus indicating their suitability for mineral carbonation reactions. Samples were composed of important silicate minerals needed for the formation of carbonates such as wollastonite, anorthite, diopside, perovskite, johannsenite, and magnesium aluminum silicate, and the Fe-bearing mineral magnetite. The presence of Fe2O3 (39.6–62.9%) and CaO (7.2–15.2%) indicated the potential of the waste to sequester carbon dioxide because these oxides are important divalent cations for mineral carbonation. The use of small-sized mine-waste particles enables the enhancement of carbonation efficiency, i.e., particles of <38 µm showed a greater extent of Fe and Ca carbonation efficiency (between 1.6–6.7%) compared to particles of <63 µm (0.9–5.7%) and 75 µm (0.7–6.0%). Increasing the reaction temperature from 80 °C to 150–200 °C resulted in a higher Fe and Ca carbonation efficiency of some samples between 0.9–5.8% and 0.8–4.0%, respectively. The effect of increasing the pH from 8–12 was notably observed in Fe carbonation efficiency of between 0.7–5.9% (pH 12) compared to 0.6–3.3% (pH 8). Ca carbonation efficiency was moderately observed (0.7–5.5%) as with the increasing pH between 8–10. Therefore, it has been evidenced that mineralogical and chemical composition were of great importance for the mineral carbonation process, and that the effects of particle size, pH, and temperature of iron mining waste were influential in determining carbonation efficiency. Findings would be beneficial for sustaining the mining industry while taking into account the issue of waste production in tackling the global carbon emission concerns.

scholarly journals Quantification of Carbonic Contamination of Fused Silica Surfaces at Different Stages of Classical Optics Manufacturing

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1620
Author(s):  
Robert Köhler ◽  
Domenico Hellrung ◽  
Daniel Tasche ◽  
Christoph Gerhard
Keyword(s):  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Decisive Role ◽  
Fused Silica ◽  
Process Step ◽  
Carbon Contamination ◽  
Silica Surfaces ◽  
Carbon Impurities ◽  
High Level ◽  
Glass Surfaces

The chemical composition of ground and polished fused silica glass surfaces plays a decisive role in different applications of optics. In particular, a high level of carbon impurities is often undesirable for further processing and especially for gluing or cementing where adhesion failure may be attributed to carbonic surface-adherent contaminants. In this study, the surface carbon content at different stages of classical optics manufacturing was thus investigated. Two different standard processes—grinding and lapping with two final polishing processes using both polyurethane and pitch pads—were considered. After each process step, the chemical composition and roughness of the surface were analysed using X-ray photoelectron spectroscopy and atomic force microscopy. An obvious correlation between surface roughness and effective surface area, respectively, and the proportion of carbon contamination was observed. The lowest carbon contamination was found in case of lapped and pitch polished surfaces.

scholarly journals Controlled atmosphere GMAW welding of transportation vehicles and production machines parts made from 30MnB5 steel

2018 ◽  
Vol 216 ◽  
pp. 03001 ◽  
Author(s):  
Evgeny Ivanayskiy ◽  
Aleksei Ishkov ◽  
Aleksandr Ivanayskiy ◽  
Iakov Ochakovskii
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Chemical Composition ◽  
Controlled Atmosphere ◽  
Shielding Gas ◽  
Reducing Atmosphere ◽  
Metal Composition ◽  
Gmaw Welding ◽  
Welding Materials

The paper studies the influence of shielding gas on the composition and the structure of weld joint metal of 30MnB5 steel applied in essential parts of automobiles and tractors. The welding was performed in inert, oxidizing and reducing atmospheres. It was established that TIG welding with argon used as shielding gas did not provide the required mechanical properties when using conventional welding materials. Carbon dioxide during MAG welding caused partial burning of alloying elements. Carbon monoxide used as shielding gas was proved to form reducing atmosphere enabling to obtain chemical composition close to the base metal composition. Metallographic examinations were carried out. The obtained results provided full-strength weld, as well as the required reliability and durability of welded components and joints.

scholarly journals Chemical composition and toxicity of some Agro waste-derived insecticides against Angoumois grain moth, Sitotroga ceralella (Olivier) [Lepidoptera: Gelechiidae] infesting stored paddy grains

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Michael Olufemi Ashamo ◽  
Kayode David Ileke ◽  
Ayomiposi Idowu Onasile
Keyword(s):  
Chemical Composition ◽  
Adult Emergence ◽  
Adult Mortality ◽  
Agricultural Wastes ◽  
Sitotroga Cerealella ◽  
Angoumois Grain Moth ◽  
Egg Hatchability ◽  
Mortality Effect ◽  
Maize Cob ◽  
High Level

Abstract Background Agriculture being one of the major practices in the world has contributed to environmental pollution, especially in developing countries where there were no equipment to recycle the agricultural wastes. Considering the high level of infestation of paddy by Sitotroga cerealella and the high level of pollution caused by agricultural wastes, this research investigated the chemical composition and toxicity of agro wastes (rice husk, maize cob, groundnut and cowpea pods) as eco-friendly protectants of paddy against Sitotroga cerealella. Parameters assessed include adult mortality, oviposition, adult emergence and egg hatchability. Gas chromatography and mass spectrophotometry were used to isolate and characterize the active compounds present in the most effective crude extract. Results The results of the study revealed that all agricultural wastes showed high mortality effect on S. cerealella. Cowpea pod powder was the most toxic to adult paddy moth that caused 33.33%, 36.67%, 46.67%, 50% and 60% mortality of S. cerealella at concentrations 0.1 g, 0.2 g, 0.3 g, 0.4 g and 0.5 g/20 g of paddy grains after 24 h of exposure, respectively. The Cowpea pod, groundnut pod and maize cob extracts caused 100% mortality of S. cerealella at concentration 0.5 ml/20 g of paddy grains after 96 h of exposure, respectively. The lethal concentrations LC50 and LC90 of cowpea pod after 24 h were 0.16 and 0.64 ml which were the lowest of all agro waste extract tested. GC–MS analysis revealed that 19 chemical compounds were present in cowpea pod extract, 9, 12-Octadecadienoic acid (a methyl ester) has the highest percentage total of 39.57% and 4-Pentenal, 2-methylene (0.12%) has the least percentage total. Conclusion All the observations revealed that cowpea pod was the most effective. The findings also suggested that the selected agricultural wastes have a promising insecticidal potential and can be used as alternatives to synthetic chemical insecticides for the control of stored product insects.

scholarly journals Saturated Densities of Carbon Dioxide+Water Mixture at 304.1 K and Pressures to 10 MPa.

2000 ◽  
Vol 79 (2) ◽  
pp. 144-146 ◽  
Author(s):  
Rikio YAGINUMA ◽  
Yoshikazu SATO ◽  
Daisuke KODAMA ◽  
Hiroyuki TANAKA ◽  
Masahiro KATO
Keyword(s):  
Carbon Dioxide ◽  
Water Mixture

scholarly journals Fermentation profile and chemical composition of cassava root silage

2021 ◽  
Vol 51 (3) ◽  
pp. 191-198
Author(s):  
Juliana Schuch PITIRINI ◽  
Rosana Ingrid Ribeiro dos SANTOS ◽  
Francy Manoely da Silva LIMA ◽  
Ilano Silva Braga do NASCIMENTO ◽  
Jehmison de Oliveira BARRADAS ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Dry Matter ◽  
Soil Acidity ◽  
Neutral Detergent Fiber ◽  
Fresh Matter ◽  
Cassava Root ◽  
Aerobic Stability ◽  
Fermentation Profile ◽  
Silage Production ◽  
High Level

ABSTRACT The use of cassava root silage for animal feeding is a suitable option for farmers who grow cassava as an alternative product and for cattle ranchers who have to deal with high prices of corn. Our objective was to determine the effects of cassava genotypes and the correction of soil acidity on the microbial population, fermentation characteristics, chemical composition, aerobic stability and losses of cassava root silage. We used a 2 × 3 factorial design in completely randomized blocks, with four replications. We evaluated two cassava genotypes (Caeté and Manteiguinha) and three methods of soil acidity correction (lime, gypsum, and lime+gypsum). The roots were harvested 11 months after planting, ensiled in PVC silos, and stored for 45 days. No interaction was observed between genotypes and soil acidity correction for any of the evaluated parameters. The silage of Caeté genotype showed the highest concentration of dry matter (421 g kg-1 fresh matter) and non-fibrous carbohydrates (893 g kg-1 dry matter), and the lowest concentrations of neutral detergent fiber (37.1 g kg-1 dry matter) . No significant differences were observed among treatments for lactic acid bacteria, yeast and mold counts in silages. Both genotypes resulted in silages with an adequate fermentation profile and considerably high aerobic stability, but with high effluent loss. The Caeté genotype showed to be potentially better for silage production due to its higher dry matter recovery. Due to the high level of effluent loss, it is recommended to test the effect of a moisture-absorbing additive during the ensiling process of these cassava roots.

scholarly journals Effect of Using Different Rations in Nutrition of High-Productive Cows on Milk Quantity and Quality

2015 ◽  
Vol 15 (2) ◽  
pp. 185
Author(s):  
Goce Cilev ◽  
Živko Gacovski ◽  
Biljana Petrovska ◽  
Jovan Stojković
Keyword(s):  
Chemical Composition ◽  
Milk Production ◽  
Milk Fat ◽  
Dry Matter ◽  
Control Group ◽  
Daily Production ◽  
Group I ◽  
Production Increase ◽  
High Level ◽  
Experimental Group

This paper shows the results of production and chemical compo­sition of cow’s milk on a farm MILKO-HF, Prilep, R. Macedonia with capacity of 100 cows of Holstein-Frisian breed divided into two groups (control and experimental). In control group I which was fed in a standard way of nutrition (ration used on the farm), average daily production of milk per cow ws 22.49 kg with the following chemical composition of milk: average daily content of milk fat is 3.75%, protein 3.57%, lactose 4.65%, nonfat dry matter 9.56% and total dry matter 13.31%. In experimental group II which were fed with the ration according to normatives, average daily production of milk per cow is 24.04 kg with the following chemical composition of milk: average daily content of milk fat is 3.99%, protein 3.57%, lactose 4.65%, non-fat dry matter 9.58% and total dry matter 13.57%. The obtained results show the increase in milk production for 1.55 kg-6.89% and better chemical composition of milk in the experimental group of cows. Thus, dry matter was increased from 13.31% to 13.57%-1.95%, milk fat content from 3.75% to 3.99%-6.4%, nonfat dry matter from 9.56% to 9.58%-0.21%, while the content of protein and lactose stayed on equal level. It was determined that the normed nutrition has influenced on production increase and better chemical composition of milk without unnecessary spent high level of nutrient i.e. nutrition of cows according to recommended normative.

Computational UV Spectra for Amorphous Solids of Small Molecules

2021 ◽  
Author(s):  
Austin Michael Wallace ◽  
Ryan C. Fortenberry
Keyword(s):  
Carbon Dioxide ◽  
Interstellar Medium ◽  
Small Molecules ◽  
Gas Phase ◽  
Amorphous Solids ◽  
Uv Spectra ◽  
Ammonia Water ◽  
Gas Phase Molecules ◽  
High Level

Ices in the interstellar medium largely exist as amorphous solids composed of small molecules including ammonia, water, and carbon dioxide. Describing gas-phase molecules can be readily accomplished with current high-level...

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