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101.
福建尤溪梅仙矿田铅锌银矿床特征及找矿方向 总被引:1,自引:0,他引:1
梅仙矿田铅锌银矿是福建省目前已发现规模最大的铅锌矿产地。自上世纪90年代以来,矿田内陆续发现和评价了丁家山、峰岩2处大型规模的铅锌矿床。矿床产于闽中裂谷带中新元古代东岩组绿片岩中,属块状硫化物型矿床。 相似文献
102.
Summary A mathematical programming model for scheduling open pit mining was developed and validated using data from a surface mining operation. A two-phase solution procedure was used involving repeated evaluations of an integer scheduling model and a simple transportation model. 相似文献
103.
104.
Summary This investigation concerns 3 longwall faces having variable strata and mining conditions, but supported by 202 tonnes hydraulic 6-leg chocks. Bearing capacity tests along the faces were conducted to evaluate the factors influencing floor deformation and failure. The effect of size, shape and perimeter of the base plates, thickness of the floor layer, time and moisture on the ultimate bearing capacity of the floor was measured and discussed. Application of this work is the prediction of stability and support performance of face ends, as well as the design of support systems and ground control on production faces. 相似文献
105.
湘西南采金“信”的地质解释 总被引:2,自引:0,他引:2
在湘西南民间开采脉金的活动中,人们积累了很多识别金富集的标志,简称“信”。本文收集列举了25种“信”,并相应地作了地质解释,评估了含金情况。从金的地球化学特性,论述了“信”与金富集的内在联系。 相似文献
106.
Summary This article discusses methods for providing a reliable forecast of the gas-dynamic behaviour of coal seams and adjacent strata. It shows that the ash content of carbonaceous materials determines their sorptive capacity (a universally applicable expression is presented for calculating the methane content of a sample) whilst the rate of methane desorption is a function of the degree of geological disturbance, i.e. the number and distribution of the macropores and fractures in the sample. This effect becomes less important as the sample ash content increases and effectively disappears above a certain value for high permeability materials.The quantity sorption-kinetic characteristic is shown to be a reliable means for quantifying methane emission behaviour. Large variations in coal sorption-kinetic characteristics are shown to occur over short distances as the geological structure of the seam changes, both vertically and horizontally. Consequently, sorption-kinetic characteristics may be used to predict the general level of methane emission from the seam and to quantify the risk of outburst inherent in disturbed areas of coal seams. 相似文献
107.
108.
David A. Newman 《Geotechnical and Geological Engineering》1989,7(2):163-170
Summary An indication of the complete stress-strain behaviour of coal was obtained through instrumenting a headgate yield pillar and monitoring the changes in vertical and horizontal pillar stress, pillar strain, and roof-floor convergence as a function of time and distance from the moving longwall face. A semiautomated monitoring program was conducted over a 5 month period as the longwall face advanced toward and eventually passed the instrumented pillar. The development of a confined core and yield zone within the pillar was confirmed by the vertical and horizontal stress changes. Thein situ pre-failure (208 to 661 MPa) and post-failure moduli (55 to 208 MPa) of the coal were determined from the change in pillar stress versus pillar strain. Thein situ moduli are an order of magnitude lower than the 3450 MPa, commonly assumed for coal. 相似文献
109.
Summary Little comprehensive information has been reported on the behaviour of room-and-pillar mines. The objective of this paper is to present case data on mine failures in the Illinois basin for use in practice. Presented are results of an ongoing study and details on the site characteristics of cases where sags have developed on the surface. Site data are reported to show the geologic, mining, and sag conditions that existed. Sags mainly develop from pillar, floor, or pillar-floor failure. The character of the sags depends upon the type of mine failure as well as the overburden response.Preliminary results show that the statistical no-risk tributary pressure decreases over 300% as the mine age increases from about 2 to 100 years at a long-term value of approximately 300 psi (2070 kPa). As more information is collected and more analysis is done, the allowable tributary pressure can be determined for different site conditions.A plot is also reported that depicts the relationship of the maximum subsidence to site conditions. It was found that the modified subsidence factor was heavily dependent upon the overburden rock thickness. 相似文献
110.
Derek L Smith 《The Australian geographer》1995,26(1):61-70
This paper compares pastoralists in South Australia in the nineteenth century with Australian mining companies in the twentieth century as they resist the efforts of government to extract a greater proportion of the wealth created in the exploitation of natural resources. In effect, in both cases the struggle relates to the allocation of economic rent between private and corporate capital on the one hand, and the owners of the resources, the people of Australia, on the other. It is difficult not to be impressed by the similarities in the ideologies, objectives and strategies of these two groups of resource exploiters, separated though they are by over one hundred years. 相似文献