In next two years, the current waste dump of Narynsukhait coal mine is predicted insufficient to accommodate the overburden as limited of the waste dump capacity. Thus, redesigning waste dump is paramount to increase ...In next two years, the current waste dump of Narynsukhait coal mine is predicted insufficient to accommodate the overburden as limited of the waste dump capacity. Thus, redesigning waste dump is paramount to increase capacity of the dump in future. This paper describes current condition of waste dump of Narynsukhait coal mine and then discusses the optimization of waste dump geometry by analyzing the effect of different waste dump’s bench configuration on slope performance. Optimization of the geometry is carried out by investigating and comparing the performance of geometrical combinations of bench height, bench angles and number of safety berm by means of numerical modeling. The model shows that increasing height of bench is able to induce shear stress in the bench and may initiate bench instable. However, the shear stress can be limited by having safety berm and/or reducing bench angle to satisfy the stability criteria.展开更多
A self-heating intensity index(SHII)based on the highest(pixel max.)and lowest(pixel min.)values taken from satellite thermal maps of burning coal waste dumps are proposed.The index enables the classification of such ...A self-heating intensity index(SHII)based on the highest(pixel max.)and lowest(pixel min.)values taken from satellite thermal maps of burning coal waste dumps are proposed.The index enables the classification of such fires in Ukrainian-and Polish coal waste dumps.Both in Ukraine and in Poland,varying thermal intensities during 1985–2019 are revealed,using the SHII and following thermal intensity threshold values,namely,extreme thermal activity([7),advanced(3–7),moderate(3–1.5),initial(1.5–1),no activity(<1).The SHII shows decreasing thermal activity in the selected Ukrainian coal waste dumps during 2017–2019.It aids in reconstructing the thermal history of the dumps.Analysis of satellite images revealed a large number of burning coal waste dumps in the Donetsk Coal Basin(Ukraine)with high thermal activity.Such burning likely reflects large amounts of organic matter and sulphides in the dumped material subjected to self-heating and self-burning processes,lack of compaction of the coal waste and/or high methane contents.Comparison of SHII values calculated from satellite-and drone thermal-camera images were compared to show that SHII from drone thermal images have much higher values than those from satellite images;the former have better resolution.Thus,SHII from Landsat-and drone images should be used separately in dump heating studies.展开更多
The coal mining residues from past mining activities in the Douro Coalfield are emplaced in many dumps near the mining areas,causing substantial environmental impacts.This study aims to contribute to the investigation...The coal mining residues from past mining activities in the Douro Coalfield are emplaced in many dumps near the mining areas,causing substantial environmental impacts.This study aims to contribute to the investigation of environmental impacts caused by the disposal of the residue in the Douro Coalfield through the determination of the geochemical composition of waste materials collected at 3 e 15 m depth,and of the water-leachable fraction produced by percolation in these materials inside the dump.The elements with higher concentration in the leachates are Ca,Cd,Co,Mg,Mn,Na,Ni,S,and Zn,indicating that they are the most easily leached and accessible elements for percolation and mobilization into the environment.The presence of these elements in the leachates is principally attributed to their occurrence as water-soluble ions in clays and sulphides affected by natural weathering conditions,which promotes their breakdown and occurrence as exchangeable ions.The leachates are classified as acid high-metal.Natural weathering and leaching in the Sao Pedro da Cova waste dump are the principal~paths for chemical elements to be percolated and mobilized to environment,posing risk to the soils,waters and ecosystems in the surrounding areas.展开更多
Berau Basin, a sub-basin of Tarakan Basin, had been developed during Eocene to Miocene period. Rocks in Berau Basin consist of sedimentary, volcanic and igneous rocks aged from Pre-tertiary until Quaternary epoch. The...Berau Basin, a sub-basin of Tarakan Basin, had been developed during Eocene to Miocene period. Rocks in Berau Basin consist of sedimentary, volcanic and igneous rocks aged from Pre-tertiary until Quaternary epoch. The youngest identified rock formation was alluvial deposit consists of mud, silt, sand, gravel and swamp with brown to dark color. This youngest rock formation is relatively weak geological condition and can cause problems in the coal mining operation. PT Berau Coal as one of the coal mining companies in Berau Basin area had experienced some problems related to the occurrence of alluvial deposit. A large failure has occurred at one of its out pit dumping?area which lies over the swamp material. The failure caused a higher operating cost since it made that the distance for waste rock dumping became to be farther than the designated area. Therefore, in order to prevent similar failure occurring at dumping area which lies above swamp material, an improvement of dumping site stability on weak geological condition has to be needed. The proposed method for improving the stability of out pit dumping area in weak geological condition is to construct the compacted layer of waste rock before the out pit dumping area construction. Based on experimental results, a minimum of 40 kPa pressure is needed to give a proper compaction to the waste rock. The result of numerical analysis by Finite Element Method (FEM) shows that construction of compacted layer on the base of out pit dumping area can improve its stability.展开更多
文摘In next two years, the current waste dump of Narynsukhait coal mine is predicted insufficient to accommodate the overburden as limited of the waste dump capacity. Thus, redesigning waste dump is paramount to increase capacity of the dump in future. This paper describes current condition of waste dump of Narynsukhait coal mine and then discusses the optimization of waste dump geometry by analyzing the effect of different waste dump’s bench configuration on slope performance. Optimization of the geometry is carried out by investigating and comparing the performance of geometrical combinations of bench height, bench angles and number of safety berm by means of numerical modeling. The model shows that increasing height of bench is able to induce shear stress in the bench and may initiate bench instable. However, the shear stress can be limited by having safety berm and/or reducing bench angle to satisfy the stability criteria.
文摘A self-heating intensity index(SHII)based on the highest(pixel max.)and lowest(pixel min.)values taken from satellite thermal maps of burning coal waste dumps are proposed.The index enables the classification of such fires in Ukrainian-and Polish coal waste dumps.Both in Ukraine and in Poland,varying thermal intensities during 1985–2019 are revealed,using the SHII and following thermal intensity threshold values,namely,extreme thermal activity([7),advanced(3–7),moderate(3–1.5),initial(1.5–1),no activity(<1).The SHII shows decreasing thermal activity in the selected Ukrainian coal waste dumps during 2017–2019.It aids in reconstructing the thermal history of the dumps.Analysis of satellite images revealed a large number of burning coal waste dumps in the Donetsk Coal Basin(Ukraine)with high thermal activity.Such burning likely reflects large amounts of organic matter and sulphides in the dumped material subjected to self-heating and self-burning processes,lack of compaction of the coal waste and/or high methane contents.Comparison of SHII values calculated from satellite-and drone thermal-camera images were compared to show that SHII from drone thermal images have much higher values than those from satellite images;the former have better resolution.Thus,SHII from Landsat-and drone images should be used separately in dump heating studies.
基金was developed under the ICT(project UIDB/04683/2020)with the reference POCI-01-0145-FEDER-007690.
文摘The coal mining residues from past mining activities in the Douro Coalfield are emplaced in many dumps near the mining areas,causing substantial environmental impacts.This study aims to contribute to the investigation of environmental impacts caused by the disposal of the residue in the Douro Coalfield through the determination of the geochemical composition of waste materials collected at 3 e 15 m depth,and of the water-leachable fraction produced by percolation in these materials inside the dump.The elements with higher concentration in the leachates are Ca,Cd,Co,Mg,Mn,Na,Ni,S,and Zn,indicating that they are the most easily leached and accessible elements for percolation and mobilization into the environment.The presence of these elements in the leachates is principally attributed to their occurrence as water-soluble ions in clays and sulphides affected by natural weathering conditions,which promotes their breakdown and occurrence as exchangeable ions.The leachates are classified as acid high-metal.Natural weathering and leaching in the Sao Pedro da Cova waste dump are the principal~paths for chemical elements to be percolated and mobilized to environment,posing risk to the soils,waters and ecosystems in the surrounding areas.
文摘Berau Basin, a sub-basin of Tarakan Basin, had been developed during Eocene to Miocene period. Rocks in Berau Basin consist of sedimentary, volcanic and igneous rocks aged from Pre-tertiary until Quaternary epoch. The youngest identified rock formation was alluvial deposit consists of mud, silt, sand, gravel and swamp with brown to dark color. This youngest rock formation is relatively weak geological condition and can cause problems in the coal mining operation. PT Berau Coal as one of the coal mining companies in Berau Basin area had experienced some problems related to the occurrence of alluvial deposit. A large failure has occurred at one of its out pit dumping?area which lies over the swamp material. The failure caused a higher operating cost since it made that the distance for waste rock dumping became to be farther than the designated area. Therefore, in order to prevent similar failure occurring at dumping area which lies above swamp material, an improvement of dumping site stability on weak geological condition has to be needed. The proposed method for improving the stability of out pit dumping area in weak geological condition is to construct the compacted layer of waste rock before the out pit dumping area construction. Based on experimental results, a minimum of 40 kPa pressure is needed to give a proper compaction to the waste rock. The result of numerical analysis by Finite Element Method (FEM) shows that construction of compacted layer on the base of out pit dumping area can improve its stability.
