A virgin chromite orebody located in eastern India is planned to be extracted by sub-level open stoping method. The portal of the decline and vertical shaft is planned to locate in the footwall side of the orebody to access the deposit. Design of proper supporting system for the underground stope is important for the safe extraction of orebody. In this paper, two dimensional finite element modelling techniques have been employed to determine the stress and displacement distributions around the stope and rib pillar and also estimated the tensile zone that may occur in the crown, sill and rib pillars. Based on development of the stress, displacement and tensile zone in the roof and rib pillar; roof bolting grid pattern is established.
Keywords: Finite element model, rib pillars, stope, joints, principal stress and bolt
The formation mechanism of clastic reservoirs in the Upper paleozoic in southeastern Ordos basin is systematically studied by using a large number of rock and mineral analysis and testing data. It is pointed out that the sedimentary environment, petrological characteristics, burial diagenesis, abnormally high fluid pressure and medium environment of salt lake water are the formation mechanisms that control the diagenetic evolution and reservoir property of the reservoirs. And it is put forward that the main reservoir space for the high efficiency reservoirs of sandstone in the upper paleozoic of the Ordos basin includes various types of denudation pores and residual intergranular pores, and that the plastic particle content and particle size in the detrital component of the reservoir are the important mechanisms for the formation of the reservoir.
Keywords: upper paleozoic,clastic reservoir, formation mechanism, ordos basin
In view of the characteristics of low permeability and tight reservoir and the requirement of fracturing fluid, the fracturing fluid system of ma-s high efficiency drag reducer is developed, and its performance is evaluated. Using the indoor evaluation device of drag reducer, the Ma-s high efficiency drag-reducing agent fracturing fluid system has high drag reduction performance, the best concentration is 0.07%, and has a certain stability, the 120h drag reduction rate is lowered by 8%. The resistance to mild and shear properties was tested by Rheometer, the temperature rises from 25 to OC, viscosity drops 0. 025pa.s, shearing time from 0 s to 1800s, apparent viscosity reduces 0.0075 Pa.s, when the velocity is 20m/s, the drag reduction rate is 61%, then with the flow rate increases, the drag reduction rate drops, But the decline was smaller, at a minimum of 53%. With the successful application of 5 wells in the field of ma-s drag-reducing agent fracturing fluid, the maximum frictional resistance of the tubing can be reduced by 61%, which provides an effective way for the efficient reconstruction of tight reservoirs.
Keywords: Low permeability tight reservoir, drag reducer fracturing fluid, fracturing
A high activity photocatalysts N-ZnO has been synthesized by hydrothermal method. The characterization of the prepared N-ZnO nano-composite has been examined by SEM, TEM, ultraviolet-visible diffuse reflectance spectroscopy, X-ray diffraction, elemental analysis, Brunauer-Emmer Teller surface area. Under irradiation (>360 nm), N-ZnO shows high photocatalytic activity for the debromination of polybromo diphenyl ethers (PBDEs). The photocatalytic degradation kinetics of PBDEs has been investigated under different reaction conditions. The N-ZnO nano-composite exhibits excellent photostability after four run experiments. The possible photoreductive mechanism has been proposed. This study provides an efficient method to removal of halogen organic pollutants.
Keywords: N-doped ZnO, photoreduction, degradation; polybrominated diphenyl ether, pollutants
Developing new energy is an important way to optimize energy structure, which makes significant sense on improving energy efficiency, reducing carbon emission, and lowering external dependence degree. New energy power generation costs are generally higher than conventional ones at this time. They would quickly decrease because of their scale effects, as technology improving and the scale expanding. Referring to the developing trend of new energy power generation costs, this paper sets the minimize generation costs and pollutant emission as optimization objectives, selects primary energy consumption and new installed generation capacity of each year as decision variables, and establishes an optimization model for new energy and energy structure. By setting and calculating the optimal energy structure, new energy developing scale, generation capacity and building sequences, we can get comparative results of power generation costs under three different scenarios, namely reference scenario, energy security scenario and low-carbon scenario. And use a sensitive analysis to clear the effect of total energy consumption and non-fossil energy consumption proportion. A simulation result shows resource and environmental benefits would be greater than new energy exploration and utilization costs. The larger scale, greater benefits and the less operation cost of the energy system as well as the lower external dependence degree will occur. Therefore, China should adhere to low-carbon energy structure developing direction, to improve energy conversion and utilization efficiency, to strengthen investment in new energy and finally achieve energy development strategies and goals.
Keywords: new energy, energy structure, electric structure, multi-objective, multi-scenario
Through accelerated chloride corrosion test in the concrete structure, the chloride ion concentrations at different depths of the concrete added with special protection and without special protection at different corrosion times are tested, and the effects of special protection on the diffusion coefficient of chloride ion and chloride ion concentration on the surface of the concrete are studied. The reduction coefficient of the chloride ion diffusion coefficient and the reduction coefficient of the surface chlorine ion concentration are introduced to carry out performance test on the effects of the special protection. And the test results show that: The special protection can reduce the diffusion coefficient of the chloride ions in the concrete by 31.3% and lower the chloride ion concentration on the surface of the concrete by 22.67%. And the special protection can improve the service life of the concrete structure in the environment of chloride ion corrosion to a relatively large extent.
Keywords: concrete structure, chloride ion, special protection, performance test
Spontaneous combustion of coal causes substantial material damage and endangers the safety of workers both in the actual extraction of coal and during its transportation, preparation and storage. For these reasons, great attention is paid to the prevention and early detection of early-stage spontaneous combustion. The issue of early detection of spontaneous combustion at coal stockpiles was addressed by the research project TA01020351 solved in the Czech Republic in 2011-2014. The project was focused on spontaneous combustion of lignite, on laboratory tests of indicator gases of spontaneous combustion, and on the verification of the laboratory tested gaseous products and the development of temperature changes at lignite stockpiles. Brief information about the project have been published in the JMMF in September 2012, pp. 193-196.Read more
Although, there are a number of safety management systems available but the near-misses, dangerous occurrences, incident and accidents occur every day and it became worst and known to be a major concerned in mining industry. In this paper, a coal mine accident has been analysed which showed reoccurring disturbances during routine operation were present in the contributory path of the accident. The reoccurring disturbances were the warning from the system toward the organisation and could be seen as pre-warning signals. It is necessary to investigate all the pre-warning which are unknown, as well as to identify all the underlying causes. As a result suitable action can be taken against them for the prevention of accidents in future.
Keywords: Accident investigation, pre-warning signals, safety indicators, risk assessment
Coal is chief source of energy in India and accounts for 55% of country’s energy need (www.coal.nic.in). Indian coal mining industry is manpower-intensive. Despite majority of coal mining is done by public sector coal companies, accident rates remain high compared to other major coal producing nations (except China). Human failures have been found to be major attributes of coal mining accidents. To identify human errors in accidents 96 fatal and serious accidents befell between 2009 and 2014 in a large public sector coal company of central India were analyzed on human factor analysis and classification system – mining industry (HFACS-MI). Analysis revealed that violations, skill based errors, decision errors, inadequate leadership and physical environment were the major contributing factors. These findings stress upon the need to focus on reduction of human errors during mining operations to arrest present trend of accidents. The results of the study represent a preliminary findings and subsequent detailed study is required to pinpoint activity-wise human failures.
Keywords: Accidents; coal mining; human errors; human factor analysis and classification system – mining industry (HFACS – MI)
This paper proposed an approach of a quantitative analysis to evaluate the accident causation in underground coal mines in India. The Bayesian structural equation modelling (SEM) is the best multivariate analysis to comprehend the safety measures for reducing accidents in underground coal mines in India. In this paper, an accident causation model have been proposed and developed for structural equation modelling with Bayesian inferences by using workers response on the basis of their perception of the parameters of several hazards which has to be measured by considering mine, miners and management variables and to achieve zero accident potential (ZAP), identification of hazards and actual cause of accident analysis is crucial. Moreover, Bayesian inferences in structural equation modelling has to be applied to identify the hazards and Markov Chain Monte Carlo sampling in the form of Gibbs sampling has to be applied for parameter estimation.
Keywords: Hazards, occupational safety, Bayesian SEM