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The situation of coal mine safety production is still quite severe. Most coal mine accidents are caused by gas or coal dust explosion. Therefore, the monitoring and control of underground gas and coal dust is the key link to realize coal mine safety production. In this paper, through the data acquisition, processing and calculation of the monitored values, the corresponding optimization model and the optimization calculation formula of absolute gas emission and relative gas emission are obtained. Through the given data, the absolute gas emission and relative gas emission of each monitoring point in the coal mine are calculated every day. The absolute gas emission and relative gas emission of the total return air roadway are used to identify whether the mine belongs to "low" or "high" gas mine. Considering the possibility of gas explosion and coal dust explosion, the deviation degree between coal dust and the lower explosion limit of coal dust under the influence of gas concentration is cited to measure. The table shows the unsafe degree corresponding to different gas concentration and coal dust concentration. Through the diversion of air volume in each shaft and roadway, it is determined that the best total ventilation volume is the sum of the air volume of inlet roadway I and II and the roadway where the local fan is located (including the air volume of the local fan).Under the simplified assumption, the model is evaluated, popularized and improved through error analysis. [ABSTRACT FROM AUTHOR]

The effect of peach shell biochar (PSB) amendment on sheep manure (SM) composting was investigated. Five different ratios of PSB were applied (0%, 2.5%, 5%, 7.5%, and 10% PSB), and named T1 to T5, and run 50 days of composting experiment. It was found that PSB (especially 7.5% and 10%) could improve the compost environment, regulate the activity of microorganisms and related enzymes, and promote the decomposition of compost. 7.5% and 10% PSB advanced the heap into the thermophilic stage and increased the maximum temperature, while also increasing the germination index by 1.40 and 1.39 times compared to control. Importantly, 10% PSB effectively retained more than 60% of carbon and 55% of nitrogen by inhibiting the excess release of NH 3 and greenhouse gases. High proportion PSB amendment increased the activity of dehydrogenase and cellulase, but inhibited protease and urease. The correlation results indicated that PSB changed the key bacterial genus, and there was a stronger association with environmental factors at 7.5% and 10%. Therefore, 7.5% and 10% peach shell biochar can be used as appropriate proportions to improve composting conditions. [Display omitted] • Peach shell biochar enhanced the temperature of thermophilic period. • The germination index of biochar modified group was 1.14–1.40 times than control. • Peach shell biochar reduced NH 3 and greenhouse gas emissions during composting. • 10% biochar increased dehydrogenase and cellulase activities. [ABSTRACT FROM AUTHOR]

Aiming to improve the accuracy of predicting aquaculture wetlands derived greenhouse gas emissions, built on rough sets, a new model for predicting aquaculture wetlands derived greenhouse gas emissions is designed. The data of greenhouse gases in aquaculture wetland were collected and normalized. Based on the processed data, the gas emission relationship model of aquaculture wetland greenhouse was constructed. The rough set theory is used to construct a model for predicting aquaculture wetlands derived greenhouse gas emissions. So far, the prediction of aquaculture wetlands derived greenhouse gas emissions is realized. The experimental results show that the prediction model based on rough set improves the prediction accuracy and reduces the prediction time. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista CESUMAR: Ciências Humanas e Sociais Aplicadas is the property of Revista Cesumar - Ciencias Humanas e Sociais Aplicadas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The further development of coal mining in diffierent countries and in India is connected with many problems. The emission of gas, sudden outbursts of gas and coal, minefires, dustiness, spontaneous combustion, methane concentration are very serious problems. This article deals with solving these problems. It describes a new method applied in coal mines in the Czech Republic that has brought very good results. [ABSTRACT FROM AUTHOR]

During coal mining, gas concentration transfinite usually occurs when gas emission increases, and in this paper, we analyzed the reasons that lead to an increase in gas emission. Based on field investigation data, three types of gas concentration transfinite were identified: transitory, continuous, and abnormal fluctuation gas emissions. We draw gas concentration change curves for each type. In the presence of gas concentration transfinite, wind quantity can be increased by varying the frequency of the mine ventilator to dilute the gas. In this paper, we propose two methods for varying the frequency of the ventilator, using a frequency-concentration ( f-w ) control of the follow-up wind quantity and automatic control of the curve value. The transfer function of the f-w control method and a database of ventilator characteristic curves at different frequencies were established. Using the Da Liuta mine ventilation system, an experimental model for wind quantity adjustment was setup in a ventilation network branch using a variable-frequency ventilator. Considering the fire and explosion risks associated with the real gas, carbon dioxide was instead released to simulate gas emission in the experiment. A carbon dioxide release model was set up using the gas concentration change curves. The experimental results show that the mine ventilator variable-frequency control automatically adjusted the branch wind quantity, which strictly followed the f-w control method and the automatic control of the curve value. Increasing the carbon dioxide concentration caused the mine ventilator variable-frequency controller to increase the branch wind quantity automatically to keep the carbon dioxide concentration under the threshold value. The experimental results demonstrate the feasibility and efficiency of the two methods, and theoretical guidance for adjusting the ventilation branch quantity for a variable-frequency mine ventilator is provided. [ABSTRACT FROM AUTHOR]

Gas emission prediction is very important to gas drainage, controlling and utilization. Many gas emission prediction methods have been proposed; however, there currently is no widely used method because of accuracy issues. Stress, gas pressure and coal property are the main influential factors of gas emission. Fluid–solid coupling occurs during gas seepage. Based gas is primarily a result of fallen coal, work face and roadway coal walls. A dynamic gas emission prediction model is established in this paper, and the influential parameters of gas emission are considered comprehensively. The values from the dynamic and normal gas emission prediction models are compared with and without prevention measures and at various driving speeds. The results demonstrate that the dynamic model has higher accuracy than the normal model under the different conditions. Moreover, the dynamic model can be widely used in coal engineering because it comprehensively considers the factors of gas emission. The research is helpful in gas drainage, controlling and utilization. [ABSTRACT FROM AUTHOR]

In the last decades, saving energy and protecting environment became the most important topics for search and survey. The energy engineer for any chemical process is obliged by restrictions of “Kyoto Protocol” for limitation of carbon dioxide emissions from fuel combustion, so he does his best to reduce utility consumption and thus reduce gas emission. Proper designing of the heat exchanger network (HEN) for any process is an effective and successful method to minimize utility consumption and therefore minimize gas emission (mainly carbon gases (CO 2 ) and sulfur gases (SO x )). Fuel switching coupled with energy targeting achieved the least gas emission. In this work we choose a hydrotreater unit of a petroleum refinery as a case study due to its effective role and its obvious consumption of utility. We applied the methodology of energy targeting through HEN design (using pinch technology) at several values of mean temperature difference (Δ T min ); where the maximum percentage of energy saving was 37% for hot and cold utility which directly leads to percentage reduction of gas emission by 29% for CO 2 and 17% for SO x . Switching fuel oil to other types of fuel realized gas emission reduction percentage where the maximum reduction established was through natural gas fuel type and reached 54% for CO 2 and 90% for SO x . Comparison between existing design and the optimum Δ T min HEN led to few modifications with the least added capital cost for the hydrotreater existing design to revamp it through four scenarios; the first one depended on fuel switching to natural gas while the second one switched fuel to diesel oil, in the third scenario we applied heat integration only and the fourth one used both of heat integration and fuel switching in a parallel way. [ABSTRACT FROM AUTHOR]

The objective of this research was to evaluate the emission and distribution of methane and volatile organic compounds (VOCs) from solid waste disposal site in Thailand. Gaseous emissions from solid waste piles with and without soil cover were determined. Highest average methane emission rate was found to be 53.51 g/m2.d from solid waste pile with cover soil during rainy season. This rate was significant higher than 20.87 g/m2.d under dry season and 5.23 g/m2.d and 3.99 g/m2.d from open waste pile under rainy and dry conditions respectively. The emission of BTE× compounds was found highest from the waste pile with cover soil under dry condition at 7.11×10-2, 9.76×10-2, 4.8×10-2 and 7.62×10-2 g/m2.d. The source of VOCs was identified in fresh waste samples. The dispersion of methane and BTEX compounds in ambient air was modeled. The to×icity of BTEX compounds to workers and nearby communities was at low level as determined by hazard inde×. However, the carcinogenicity risk from benzene to those people were found to be 2.45×10-5 and 2.85×10-5, respectively. Geno-to×icity study using plant comet assay (Pothos) suggested that there was a relationship between DNA damage after 96 hours e×posure and VOC emission rate from solid waste disposal area. [ABSTRACT FROM AUTHOR]

Gas emission is affected by many factors. Effects of atmospheric pressure on coal mine gas emission have become a rising concern. Basing on the gas emission at Y485 fully mechanized working face of Tangshan mine and atmospheric pressure, the paper had carried out online monitoring with sensors for 20 days continuously. Calculating the average values of atmospheric pressure and the expectation values of return air gas concentration of each hour on every monitoring date according to monitoring data, affection laws of atmospheric pressure to gas emission at fully mechanized working face were studied combining the weather and temperature of monitoring dates. It pointed out that the atmospheric pressure declines along with the rising of temperature and the gas emission at fully mechanized working face could be restrained if the atmospheric pressure rises, otherwise it could be promoted to release, the affection of variation of atmospheric pressure to gas emission was 0.0575%/hPa on cloudy day, and was 0.0446%/hPa on sunny day, and it was predicted that the peak time of gas emission at fully mechanized working face was from 12 o’clock to 16 o’clock according to the data processing results. [ABSTRACT FROM AUTHOR]

In order to accurately predicting gas emission in coal mines, the complicated nonlinear characteristics of gas emission was analysis, the prediction method was put forward for gas emission based on self-organizing data mining. It was used the ternary quadratic polynomial for the local function and the original variable was used in each generation, and the minimum deviation principle was used for criteria of model selected. And then, the high-order equation of prediction was established for gas emission by self-organizing data mining method. The fitness relative error of this prediction model was ±0.03% and predictive relative error was ±1.45% to gas emission in coal mine. The results show that: self-organizing data mining method can automatically analyze non-linear relation between the gas emission and the factors, and can be establish the explicit high order equation to descript the gas emission laws, and the prediction model has enough prediction accuracy for application of actual engineering in coal mines. [ABSTRACT FROM AUTHOR]

CO 2 gases stored underground may escape from the reservoir site to other places and even through the soil layer into atmosphere, thus identify the leakage source is therefore a crucial problem after leakage occurring. The paper introduced a direct method to solve the inverse problem combined with the optimization method, which is Occam regularization method. This method was applied to estimate the source parameters. Firstly, the calculation process of Occam regularization method was introduced and then the feasibility of its application for source parameters identification was proved by simulation and experiment data. The results showed that, Occam regularization method is able to estimate source parameters successfully. [ABSTRACT FROM AUTHOR]

In order to accurately predicting gas emission in coal mines, the complicated nonlinear characteristics of gas emission was analysis, the prediction method was put forward for gas emission based on self-organizing data mining. It was used the ternary quadratic polynomial for the local function and the original variable was used in each generation, and the minimum deviation principle was used for criteria of model selected. And then, the high-order equation of prediction was established for gas emission by self-organizing data mining method. The fitness relative error of this prediction model was ±0.03% and predictive relative error was ±1.45% to gas emission in coal mine. The results show that: self-organizing data mining method can automatically analyze non-linear relation between the gas emission and the factors, and can be establish the explicit high order equation to descript the gas emission laws, and the prediction model has enough prediction accuracy for application of actual engineering in coal mines. [ABSTRACT FROM AUTHOR]

Gas emission is affected by many factors. Effects of atmospheric pressure on coal mine gas emission have become a rising concern. Basing on the gas emission at Y485 fully mechanized working face of Tangshan mine and atmospheric pressure, the paper had carried out online monitoring with sensors for 20 days continuously. Calculating the average values of atmospheric pressure and the expectation values of return air gas concentration of each hour on every monitoring date according to monitoring data, affection laws of atmospheric pressure to gas emission at fully mechanized working face were studied combining the weather and temperature of monitoring dates. It pointed out that the atmospheric pressure declines along with the rising of temperature and the gas emission at fully mechanized working face could be restrained if the atmospheric pressure rises, otherwise it could be promoted to release, the affection of variation of atmospheric pressure to gas emission was 0.0575%/hPa on cloudy day, and was 0.0446%/hPa on sunny day, and it was predicted that the peak time of gas emission at fully mechanized working face was from 12 o’clock to 16 o’clock according to the data processing results. [ABSTRACT FROM AUTHOR]

Uncontrolled and excessive gas emission may affect normal production and even result in serious disasters such as gas explosion and coal and gas outburst. To find out the essence of abnormal gas emission under mining induced stress, in this work, we conducted experiments on gas emitting from coal cores under mining-induced stress paths, and systematically discussed the controlling mechanism of stress change on gas emission. The results show that at the initial period, gas emission rate decreases regardless of the stress path. In this period, stress has little effect on gas emission, and it is mainly controlled by the attenuation of gas pressure gradient. In the middle period, the gas emission rate fluctuates with time. The tipping points of the gas emission rate in this stage is mainly caused by expansion of pores, opening of primary fractures and newly exposed surface induced by shear slip of the primary isolated fractures. With the further increase of the stress difference, failure of the coal core may occur, which creates a large amount of new exposure surfaces, and significantly improves the gas emission rate. Comparing with the minimum value before failure, the gas emission rate of PDS coal after failure increases by 82.35%–990.91%, and that of the JZS coal increases by 75.0%–175.0%. To verify the laboratory test results, in a recently completed research project, we implemented the technique of stress-relieved gas re-extraction in Shoushan coal mine in China. The results show that mining activity can affect the gas extraction in coal seams within 50 m from the coal wall of the working face. The average gas concentration of the boreholes drilled in the mining-disturbed zone is above 40%, and the average net gas flowrate of single borehole reaches 30 L/min. The gas extraction amount in the mining-disturbed zone, with borehole number less than 1% of the total, accounts for 55.1% of the total gas extraction amount in the roadway. This practice could be used as a valuable example for other coal mines with similar geological conditions. • Experiments on gas emission in coal cores under mining-induced stress paths are conducted. • Relation between gas emission rate and stress follows the quadratic function. • Excessive gas emission during underground mining is related to coal failure. [ABSTRACT FROM AUTHOR]

The article focuses on a study on the emissions of hydrogen sulfide gas during removal of stored spent mushroom compost (SMC). Topics discussed include health and safety risks of removal of hydrogen sulfide associated SMC, study of hydrogen sulfide concentration, moisture, and temperature at indoor and outdoor sites, and short-term exposure limit (STEL) study. It mentions the protocols need to be followed during removal of SMC to prevent the risks of exposure to toxic hydrogen sulfide gas.

Abstract: For the purpose of making effective analysis and full use of gas measuring data in mines to achieve more accurate gas emission quantity prediction, studied the method for gas emission time series analysis to achieve gas emission quantity prediction based on the Gaussian process regression model. Two methods for gas emission time series analysis were proposed, the relationship between gas emission quantity and time (Q-T) model and autoregression model, considered gas emission time series as a function of time in Q-T model, while constructed the Gaussian process regression model from gas emission time series itself completely in autoregression model. The results of case study show that Gaussian process model can describe the objective laws and the developing trends of mine gas emission, its predictive results are accurate and reliable, therefore, the application of the Gaussian process regression in gas emission time series analysis is a feasible and effective method for gas emission quantity prediction, it has high practical application value. [Copyright &y& Elsevier]

Abstract: 14211 was a prepared mining-face in Xin’ an Coalmine, Henan province, and it has not been done any work for mining so far. Geological parameters selected in this paper include seam thickness, burial depth, sandstone ratios in 20m and 40m coal seam roof, gas content and minor faults. With the calculating results of gas emission from 2007 to 2010 in other working faces, this paper interpreted the influence on gas emission of selected geological parameters. The gas emission was combined with characters of micro-cracks, permeability and isothermal adsorption. The results demonstrated that, in 14211 preparing face, there is a negative correlation between the absolute gas emission and 20m-sandstone ratio, while a significant positive correlation between the absolute gas emission and the 40m- sandstone ratio. There is gas conductivity in 20m-sandstone, adjacent to the coal seam roof. And this effect becomes so less indistinguishable in sandstone far away from coal seam that it transforms to the gas-storage effect, which is the same with tight sand and mud stone. Analysis concluded that this phenomenon is intimately associated with macroscopic type of coal and characteristic of micro-crack, isothermal adsorption and permeability. [Copyright &y& Elsevier]

Abstract: This paper introduces three kinds of mathematical prediction models: grey prediction, new information, and metabolism. The three prediction models were verified and analyzed by the example of the mine in Hegang, as a result, it is showed that the new information model predictions’ result was more accurate, the information model combines with the monitoring system can realize the dynamics of coal mine gas emission projections. [Copyright &y& Elsevier]

Abstract: According to the geological exploration about gas information in Liuzhuang Coal Mine, the gas pressure during well construction parameters, and the actual gas emission from tailgate and track trough, the author calculated and got the gas content of the first coal face; combining with coal mining conditions and coal bed methane occurrence conditions, the authors selected the gas emission coefficient from rock k1, the gas emission coefficient from pre-drainage tunnel k 2 , the gas emission coefficient from residual coal k 3 and a series of other forecast parameters, and used sub-source prediction method to calculate the gas emission from mechanized mining face and the adjacent layer. Finally, the author got the total gas emission about the first coal mining face in the 11-2 coal seam in Liuzhuang Coal Mine, which provides a theoretical basis for the gas control in Liuzhuang Coal Mine. [Copyright &y& Elsevier]

Abstract: Underground coal mining needs effective technical methods for the control of gas emissions in order to be able to work under safe conditions. Based on the coal seam geological conditions among the Xuan Gang region, a major part of theoretical research and technical development has been directed to this purpose. According to the roles of mining fractures development and relief gas flow, a novel method for the comprehensive gas drainage was proposed and engineering practiced in the mining field, which includes long drilling boreholes, oblique crossed boreholes and upper corner flexible drainage pipelines. Compared with previous gas control measurements, the total gas drainage ratio significantly enhanced from 30% to 67.33% (No.51109 working face) and 76.44% (No.51105 working face). The ventilation air methane concentration of working face greatly decreased down to about 0.3%. Field tests shows that it is an effective method for gas control, which ensured the safety production of underground coal mine. The proposed gas drainage technology provides a novel approach for the three-soft coal seam gas management in China. [Copyright &y& Elsevier]

Abstract: By analyzing the definition, mechanism of action, determination methods and damage degree of mine gas and heat, a conclusion can be reached that these two types of object (or be known as physical quantity) have similarities to a large extent. First, both of the mine gas and the mine heat are caused by field changes that respond to the mining activities. Second, we can use relative equipments and the element method to do quantitative determination and analysis. Third, the phenomenon which gas and temperature exceed the limit occurrs frequently in the return corner and other specified place. According to the above similarities, we proposed that the exploitation of mine heat should be brought into the mine green mining technology system, to form the mining technology of extracting coal, gas and heat together, which can enrich and perfect the green mining technology system. [Copyright &y& Elsevier]

To ensure the mining safety of working face in the protective seam and meanwhile extract pressure-relief gas of the lower protected seam and eliminate its outburst risk, the present study researched into fracture development of floor coal-rock mass of the protective seam and migration rule of pressure-relief gas from a protected seam so as to obtain an effective pressure-relief gas extraction method. The results show that after the upper protective seam was mined, mining-induced fracturing floor coal-rock mass fell into two zones: a floor heave fracture zone and a floor heave deformation zone. Lower protected seams located at different fracture subzones were different in the degree and characteristics of fracture development, and penetration borehole drilling from the floor roadway effectively extracted pressure-relief gas. The engineering practice of the Hongling coal mine in Shenyang indicated that for a lower protected seam in the floor heave fracture zone, taking the one time seam spacing (16 m) as the spacing between penetration boreholes ensured the mining safety of the No.321 working face in the protective seam and completely eliminated the outburst risk of the lower protected seam, the No.12 coal seam. [ABSTRACT FROM AUTHOR]

Gas emission in underground coal mines is of crucial importance. It is the potential cause of several health and safety issues such as gas explosion and gas poisoning. The emission of toxic and explosive gases in underground workings creates an unsafe environment, complicates the design of ventilation system, and increases the operating cost. The prediction of gas emission has long been associated with levels of uncertainty arising from parameters such as gas content and composition. This paper aims to identify the parameters affecting the uncertainty associated with the gas emission and determine the gas emission using the Monte Carlo simulation (MCS). A three-dimensional Computational Fluid Dynamics (CFD) model is developed to estimate the gas distribution and required airflow rate for ventilating the mine workings considering the gas content uncertainty. The CFD simulation is also carried out using the Monte Carlo modeling results to determine the effect of the uncertainty associated with the gas emission on the distribution of the required airflow rate. Several ventilation scenarios are investigated to determine the optimum ventilation air characteristics. It is found that for any specific design scenario, the ventilation system can be designed such that the mining operation can be carried out safely and with minimum cost. • Impact of gas emission uncertainty on performance of an auxiliary ventilation system is studied. • Monte Carlo and CFD are used for uncertainty analysis and fluid flow simulation, respectively. • Gas concentration increases with an increase of gas emission rate and a decrease of exhaust flow. • Gas emission uncertainty affects required ventilation design requirements and associated cost. • Critical gas emission needs be determined for selecting the most appropriate ventilation system. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Combustion of a new blending fuel (dried sewage sludge with coke) has been investigated. • Results showed that the co-combustion of DSS with coke possesses a positive energy balance. • A-2 was chosen as the best blend sample in both fuel efficiency and pollution. • Gas sensors showed that CH 4 emission is higher than other gases in all samples. Abstract Co-combustion of urban dried sewage sludge (DSS) and coke in existing infrastructures is potentially an energy efficient sustainable management option. The main objective of the present study was to examine the amount of energy release and the resulting pollutant emissions from co-combustion of coke in the presence of DSS as a cheap and accessible matter, for the first time. To investigate the effects of combustion temperature on gases emissions, the isothermal combustion of five blend samples was carried out in a lab-scale electrically heated tube furnace connected to a gas sensor setup. The combustion of blend samples was characterized in terms of their proximate and ultimate analyses and calorific values. Also, the heating values and thermal characteristics of the samples were analyzed and compared with the results from thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Measurement results showed that a 1-to-4 DSS-coke ratio was optimal because of its similar characteristic and pollution emissions with coke. Therefore, such a blend can be used instead of pure coke in smelting iron ore in a blast furnace. Furthermore, according to the results of the DSC analysis, this sample has a positive effect on the heat value of coke and the amount of released energy was increased by about 40%. [ABSTRACT FROM AUTHOR]

To be effective, environmental policies must be informed by reliableassessments of the impact of economic activities. In turn, such impact assessments require comprehensive information on the pollution profiles of particular activities. In most countries and for many activities, such an information base does not exist. This article contributes to the environmental impact assessment process by introducing a method for filling part of the information gap with respect to industrial activities. It presents a pollution-estimation model that draws from published sources of information and allows analysts to obtain order-of-magnitude estimates of the pollution generated by an industrialactivity. As an illustration, the model is applied to estimate the air emissions of a petroleum refinery under two different operating scenarios. Thus, it provides its potential users policy-makers operating in a context of information scarcity with a means to review theoperation and pollution-generation characteristics of any industry in a comprehensive and rigorous manner. (c) 1998 Elsevier Science Inc. [ABSTRACT FROM AUTHOR]