Coal Excavation Research Articles

Model studies of an open-pit mine bottom loaded by artesian water pressure

Experimental modelling methods are used for prediction of deformation and groundwater outflows at the bottom of an open-pit mine during the excavation of brown coal. Thermal gas-bearing artesian water exerts an uplift pressure on the impervious subsoil of the coal seam and threatens the stability of the mine bottom. The breakthrough of the mine bottom would seriously affect the groundwater regime and may endanger mining activities. The mining is carried out within the protection zones of the Carlsbad spa springs. Results of model studies are used to determine protective hydrogeological and mining measures for providing the maximum protection for the open-pit mine and the spa springs.

Selection of the best desalination technology for highly saline drainage water from coal mines in southern Poland

Black coal excavation from most coal mines in Poland is accompanied by discharge of highly saline drainage water to the surface waters. To avoid this ecological hazard, various technologies were considered during 1990–1992. Technical requirements, presented in this paper, led to the choice of technology of thermal desalination with the carnallite method. Advantages of this method have been presented including low salinity of treated water and the possibility of practical application of the process by-products as substrate for the chemical industry. Authors discuss possible risk associated with this method such as negative impact of energy production (for purposes of desalination) on the natural environment or surpassing of desalination by-products.

Selection of the best desalination technology for highly saline drainage water from coal mines in southern Poland

Black coal excavation from most coal mines in Poland is accompanied by discharge of highly saline drainage water to the surface waters. To avoid this ecological hazard, various technologies were considered during 1990–1992. Technical requirements, presented in this paper, led to the choice of technology of thermal desalination with the carnallite method. Advantages of this method have been presented including low salinity of treated water and the possibility of practical application of the process by-products as substrate for the chemical industry. Authors discuss possible risk associated with this method such as negative impact of energy production (for purposes of desalination) on the natural environment or surpassing of desalination by-products.

Reclamation planning for abandoned mining subsidence lands in Eastern China: A case study

ABSTRACT China has a long hlatocy of coal mining and more than 96% of coal output is takan from underground mines each year. with the excavation of coal from underground, aevere aubaidanca often result. which produce many subsidanca lands. This paper explores the principle and method of reclamation planning for abandened mining subsidence lands and present a case study in eastern China. A 373 ha of abandoned mining subsidance land in Anhui province was selected as an experiment site. Since China ls a developing country and land shortage is severe in this area, the high economic benefits from the reclaimed land was the final reclamation goal Based on the topography of subsidence lands |some parts of the abandoned lands were wetland or lake-like trough restoring farmland and fishponds were chosen as post-reclamation land uses. The elevation of reclaimed lands was the key for restoring farmland successfully because of the high underground water level in this area, and the optimum fishpond size and side-slop ...

Reclamation Planning for Abandoned Mining Subsidence Lands in Eastern China - A Case Study

ABSTRACT China has a long hlatocy of coal mining and more than 96% of coal output is takan from underground mines each year. with the excavation of coal from underground, aevere aubaidanca often result. which produce many subsidanca lands. This paper explores the principle and method of reclamation planning for abandened mining subsidence lands and present a case study in eastern China. A 373 ha of abandoned mining subsidance land in Anhui province was selected as an experiment site. Since China ls a developing country and land shortage is severe in this area, the high economic benefits from the reclaimed land was the final reclamation goal Based on the topography of subsidence lands |some parts of the abandoned lands were wetland or lake-like trough restoring farmland and fishponds were chosen as post-reclamation land uses. The elevation of reclaimed lands was the key for restoring farmland successfully because of the high underground water level in this area, and the optimum fishpond size and side-slop ...

Analysis of Coalbed Methane Stimulations in the Warrior Basin, Alabama

Summary An objective of the U.S. DOE's in-house coalbed methane R&D effort has been to improve coalbed hydraulic fracturing techniques by improving the understanding of stimulation treatments. Current efforts focus on examining data from coal mine excavations to observe stimulation results, conducting Nolte-Smith analyses to characterize fracture behavior, and exercising DOE/METC's stimulation modeling codes. Test Wells DHM-6 and DHM-7, two research degasification wells located in the Oak Grove field, AL, were analyzed in this project. METC's hydraulic fracture models predicted Well DHM-6 coalbed wing lengths 3 to 5% greater than the excavated wing length. This modeling was based on observation of fluid penetration into the shale roof rock and on guidelines derived from the Nolte-Smith method, which indicated vertical propagation into the bounding strata. Results to date indicate that the Nolte-Smith method may provide adequate interpretation of coalbed fracture behavior when the effects of variable injection rates, natural fracture fluid interaction, and the interface effects of coalbed and bounding formations are considered. Further evaluation of hydraulic fracture models that predict the effects of geologic discontinuities on coalbed fracture propagation is recommended. Additionally, a future mine excavation to expose the coalbed roof rock and to assess the extent of vertical fracture propagation is suggested.

A late Middle Devensian interstadial site at Sourlie, near Irvine, Strathclyde

Sourlie, near Irvine (Fig. 1), is certainly one of the few and probably the only site in the whole of Scotland where, to date, irrefutable stratigraphical evidence demonstrates that during the Quaternary period the country was subjected to glaciation in both Late Devensian and pre-Late Devensian times (cf. [Mitchell et al. 1973][1]; [Lowe 1984][2]; [Bowen et al. 1986][3], pp. 320–3; [Bowen and Sykes 1988][4]). The relevant field evidence, preliminary results of laboratory analysis and some conclusions concerning the significance of the site at Sourlie are presented below. Temporary, open-cast coal excavations at Sourlie in 1986 exposed thin (to 0.6 m) lenses of organic-rich sediments (unit D1, Table 1 and Fig. 2) contained within local pockets on the upper surface of a layer of glacio-fluvial deposits (C). The latter sediments overlie an ablation deposit (B), which rests on a basal grey lodgement till (A) that contains clasts of (mainly) local sedimentary rocks. Units D1 and D2 are overlain by two distinctly different deposits. The lower of these, a thinly developed pink-brown diamicton (E), contains a mixture of clasts of local and far-travelled sedimentary, igneous and metamorphic rocks, together with occasional fragments and rare complete valves of marine molluscs. The overlying, thicker, upper grey lodgement till (F) is devoid of shell fragments. In grain-size characteristics, clay mineralogy and geochemistry its matrix closely resembles that of unit A, but, in addition to containing clasts of local sedimentary rocks, unit F contains basic igneous rock fragments that have been transported at least a . . . [1]: #ref-16 [2]: #ref-12 [3]: #ref-1 [4]: #ref-2

Structural properties of coal and the effect on coal excavation by high pressure waterjet impact : Mazurkiewicz, M; Summers, D A In: Ground Movement and Control Related to Coal Mining (papers to the Symposium, Illawarra, August 1986)P51–56. Pub Parkville: Aus IMM, 1986

Structural properties of coal and the effect on coal excavation by high pressure waterjet impact : Mazurkiewicz, M; Summers, D A In: Ground Movement and Control Related to Coal Mining (papers to the Symposium, Illawarra, August 1986)P51–56. Pub Parkville: Aus IMM, 1986

Optimization of rated capacities of coal mines in Kuzbass in the framework of a dynamic multiplicative model

The authors analyze the optimization of the rated design capacity of a single coal mine without constraints. The rate of return is used as the target function of the problem. The authors solve the problem in a dynamic statement considering the trends of wholesale coal prices, coal excavation costs, and capital investment in mine construction. The variables optimized in the model are the rated design capacity and the pay reserve of coal in the mine field. The regression relationships of the technical and economic indicators of Kuzbass mines are shown, as are the multiplicative regression relationships of coal mining costs for the Kuzbass production associations. Optimal parameters of the statistical average coal mines of production associations of Kuzbass for the existing times of construction are presented. The authors' estimates shown that the optimal design capacity of a mine is substantially affected by wholesale coal prices.

Optimal control of hopper unloading on collection conveyor

This article describes a computer simulation and control approach for optimizing the configuration of a hopper-belt conveyor system for the excavation of coal from underground mine workings. The purpose of the approach is to optimize the placement of hoppers along the conveyor route for maximum load capacity and optimal load distribution. The simulation is based on linear programming and has been implemented to control hopper loading and unloading in the Krasnoarmeiskaya mine No. 1 of the Krasnoarmeiskugol' Coal Production Association. Input criteria are given.

Current state and development trends in the theory of hydraulic coal excavation

1. The existing methods of calculation of the coal excavation performance of hydraulic giants lack an adequate scientific basis. The destructibility criteria used, either are incapable in principle of describing the true properties of coal (Ry) or reflect the specifics of hydraulic destruction to a limited extent and characterize the interaction of the jet with the coal mass incompletely (ψ0). 2. Attempts at developing a general criterion of coal destructibility by a hydraulic jet, as well as a phenomenological theory of strength, have been unsuccessful because of the extreme complexity of the phenomena and the large number of factors of different nature contributing to them. 3. It is necessary to study the interaction of the jet with the coal mass to determine the patterns of the process and develop a scientific basis for hydraulic mining. 4. The most promising trend of research is the development of continuous theory of defect accumulation and the theory of macrocracks. For practical purposes, it is desitable to develop a method for calculating the parameters of hydraulic excavation for given basic conditions.

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

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.

Development of a safer, more efficient hydraulic-based technique for rapid excavation of coal, rock and other minerals. Report. 38F : CHATTERTON, NE US BUR. MINES PB 245 343/AS, APR. 1975, 100P

Development of a safer, more efficient hydraulic-based technique for rapid excavation of coal, rock and other minerals. Report. 38F : CHATTERTON, NE US BUR. MINES PB 245 343/AS, APR. 1975, 100P

The influence of random poisson's ratio on displacements in an elastic half-plane

Displacement boundary problems are considered for the homogeneous isotropic elastic half-plane with random Poisson's ratio ν. Probability densities, expected values and variances of the displacement field u, ν are determined and evaluated for uniform probability distribution of ν. As an example the effect of a discontinuity of the boundary vertical displacement ν0 = ν0(x, 0) is determined and used to obtain the settlement of the earth surface under a coal excavation.