Migration of lignosulfonates in a karstic-fractured-porous aquifer: History and prognosis for a Zn-Pb mine,Pomorzany, southern Poland

Lignosulfonate lyes, which had been deposited by a paper factory for about 50 years into Quaternary sediments and accumulated in a quasistagnant depression, became mobile when a depression cone caused by mine activity in a deeper aquifer reached the erosion window close to the disposal site. Their transport parameters in the karstic-fractured-porous carbonate aquifer are shown to be mainly governed by diffusion between the mobile water in karstic channels and fractures and the stagnant water in matrix, although the hydraulic conductivity is shown to depend mainly on the karstic system. The main transport velocity is, with a sufficient accuracy, related to the hydraulic conductivity by a simple model in which matrix porosity is the governing rock parameter. The dispersivity, although also governed by matrix diffusion, depends strongly on several parameters that are difficult to determine.     

淮河以北矿区地面沉降及其成因

根据多年的高程实测资料，查明了淮河以北矿区（主要是潘集地区）地面沉降的幅度、速率及范围；分析了该区地面沉降的内因和外因，为区内地面沉降的防治提供了依据。     

南桐二井采区突水动态研究

将南桐煤矿二井的突水动态划分为纯衰减型、波动衰减型、季节波动衰减型、波动稳定型和逐渐增大型５类，它们分别对应于采区与浅层长兴灰岩含水层、蒲河及大气降水的不同连通程度与方式。     

Fire and cyclone damage to woody vegetation on the north coast of the Northern Territory,Australia

Tree stem (>2 m tall) mortality was assessed following a late dry‐season wildfire across a seasonally flooded elevation gradient at Workshop Jungle, near Darwin, in the Northern Territory of Australia. For all species combined, dead stems had significantly smaller diameter at breast height (dbh) than living stems. Assessment of tree‐stem damage following a tropical cyclone at Cobourg Peninsula, NT, revealed that damaged stems had significantly greater dbh than undamaged stems for all tree species sampled across a boundary between monsoon rainforest and savanna. A greater proportion of stems were damaged by the cyclone than by the fire (28 per cent as against 18 per cent), although there were considerable between‐community differences in the proportion of damaged stems at the two sites. The fire caused little impact (<10 per cent) on total basal area of three different forest communities on the elevation gradient at Workshop Jungle. The cyclone was found to cause >50 per cent damage to total basal area of three different communities on Cobourg Peninsula. It is suggested that the combination of a cyclone followed by an intense fire in storm debris could potentially destroy a monsoon rainforest through its impact on all tree‐size classes. This may explain why some monsoon rainforests rapidly contracted following Cyclone Tracy that destroyed the city of Darwin on Christmas Day, 1974.     

An analysis of coal bump liability in a bump prone mine

Summary This paper presents an analysis of causes of bump in a deep coal mine. The analysis consists of in-mine measurement determination, analysis of physical and mechanical properties of mine materials and simulation of mine layout and mining sequence. Major factors contributing to the causes of bump have been reviewed and those that are related to this case have been identified and simulated analytically using a three-dimensional finite element method.     

Waterjet-assisted rock cutting systems — the present state of the art

Summary A review of the benefits of assisting mechanical tools, notably drag bits, with moderate pressure waterjets suitably directed with respect to the bit is given. These benefits include reduced bit forces, especially the bit normal force, reduced bit wear, reduced dust make, and reduced incidence of frictional sparking. The research work that has been conducted to date to investigate this phenomenon has been empirical in nature. Experiments are described that extend the data bank of this empirical knowledge. In addition, experiments aimed at gaining a better understanding of the fundamentals of the rock fragmentation process with this hybrid cutting method are outlined.Results from the first of these experimental series are used to make recommendations as to the position of the jet with respect to the bit, the stand-off distance between the nozzle exit and the bit/rock interface, and the jet energy. In addition, preliminary findings are reported regarding the increase necessary in the jet energy when the bit velocity is increased. Results from the second test series are discussed in the context of rock fracture behaviour induced by mechanical bits acting alone. The likely influence of waterjets on these fracture processes is analysed. It is concluded that, in terms of the bit force reductions, a dominant influence of the jets when used in conjunction with sharp drag bits, is continuous removal of the rock debris that forms ahead of the advancing bit. The observed reductions in bit wear and incidence of frictional sparking are attributed to reduced heat loading of the bit during the cutting operation. Reductions in the dust make are attributed to effective wetting of the fine rock particles before they become entrained in the airstream.     

Dynamic programming with colour graphics smoothing for open-pit design on a personal computer

Summary Dynamic programming is a technique which has been used to design the optimum final surface mining pit limit. In using dynamic programming there is a trade-off: if the geometric constraints are specified too strictly, the pit limit will not be the optimum, but if they are specified more loosely, then the computed pit contours must be smoothed. The smoothing process has usually been manual and is time consuming. In this paper a colour graphics computer routine is presented. This not only facilitates the smoothing but also has the following benefits: open-pit limits can be designed interactively on a personal computer; pit designs that are closer to the economic optimum can be obtained; and the engineer can bring his or her own experience and intuition to bear on the final open-pit design.     

The N663 stope experiment at Mount Isa Mine

Summary Factors affecting the stability of a trial open stope at a depth of 1000 m in fissile foot wall and hanging wall shales are discussed. A combination of systematic support using cable dowels, and reduced disturbance from blasting using low density explosives and single ring firing, allowed successful completion of the stope.     

Stresses and displacements due to underground mining using a finite element procedure

Summary A two dimensional finite element procedure is applied to simulate a coal mining excavation sequence. A procedure with linear solution steps is developed and applied to an idealized mountain cross-section with exceptionally thick coal seams and large dip angle. The results provide information on pillar pressure, floor and roof stability, displacement characteristics and surface subsidence.The results presented here were obtained in the course of research sponsored by the Department of Energy, Mines and Resources, Grant No. 69-2570.     

Mine ventilation planning in the 1980s

Conclusions In this paper, the author has attempted to trace the development of mine ventilation planning from the traditional, manual and largely empirical methods of the past to the numerate computer-based techniques of the 1980s.The computer revolution has changed the face of many engineering disciplines, not least mine environmental engineering. Nevertheless, the mining industries of the world have not all been equally progressive in adapting to the flexibility, power and practical utilization of the new methodologies. It is, for example, incongruous that current textbooks on mine ventilation separate completely the topics of network analysis and ventilation planning with very little cross-referencing. Many of the current generation of mine ventilation engineers recognize the need to know about computers but find difficulty in translating this into their daily work. The growing availability of self-teaching, friendly software for personal microcomputers, coupled with interactive graphics, will assist greatly in promoting uncomplicated but powerful usage of computers.Young engineers now graduating from universities and colleges have been brought up in a computer-oriented environment and are competent in interacting with these machines. Indeed, they wonder how the job was ever done without magnetic data bases and high-speed computation aid.