Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines

Yu Wen; Ziling Song; Bo Zhao; Mingjia Lv

doi:doi:10.11648/j.ijees.20251006.14

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Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines

Yu Wen^*

, Ziling Song, Bo Zhao, Mingjia Lv

Published in International Journal of Energy and Environmental Science (Volume 10, Issue 6)

Received: 28 October 2025 Accepted: 20 December 2025 Published: 27 December 2025

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Abstract

Inclined coal-seam open-pit mines with internal dumping commonly reserve an end-side retaining ditch when turning from horizontal advance to along-strike excavation. Selecting a single fixed ditch level is straightforward but ignores year-to-year variability in stripping volumes and haulage distances, which can inflate the combined transportation and secondary stripping costs. This study proposes a two-stage optimization framework for planning the ditch-height trajectory during the turning period. First, a maximum economic ditch height is derived via an economic-compensation model that balances the revenue from overlying coal recoverable after turning against the added costs of longer haulage and increased external dumping, with cost/revenue streams discounted using a compound-interest formulation. Second, within this upper bound, a total-cost minimization model couples annual stripping transportation costs during turning with the secondary stripping cost after turning. The model enforces annual waste-volume balance among inner dumping, ditch storage, and external dumping, preferred waste-flow directions, bounds on ditch height, and limits on height differences between adjacent years. Haulage distances are calculated from centroid locations of stripping and dumping stages extracted from 3DMine, and the resulting dynamic program is solved using a sequential recursion method. A seven-year case study (2023-2029) outputs an optimized fluctuating ditch scheme with yearly ditch heights of 214.5, 190.5, 206.7, 201.3, 189.6, 181.2, and 166.0 m, reducing the cumulative cost by 148.32 million CNY compared with the conventional constant-level ditch plan. The framework offers a practical decision tool for parameterizing retaining ditches and improving the overall economics of gentle-slope turning in inclined coal-seam open-pit mines.

Published in	International Journal of Energy and Environmental Science (Volume 10, Issue 6)
DOI	10.11648/j.ijees.20251006.14
Page(s)	162-173
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

Open-pit Mine, Inclined Coal Seam, Ditch Height Optimization, Fluctuating Ditch, Optimization Modeling

References

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APA Style

Wen, Y., Song, Z., Zhao, B., Lv, M. (2025). Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines. International Journal of Energy and Environmental Science, 10(6), 162-173. https://doi.org/10.11648/j.ijees.20251006.14

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ACS Style

Wen, Y.; Song, Z.; Zhao, B.; Lv, M. Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines. Int. J. Energy Environ. Sci. 2025, 10(6), 162-173. doi: 10.11648/j.ijees.20251006.14

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AMA Style

Wen Y, Song Z, Zhao B, Lv M. Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines. Int J Energy Environ Sci. 2025;10(6):162-173. doi: 10.11648/j.ijees.20251006.14

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@article{10.11648/j.ijees.20251006.14,
  author = {Yu Wen and Ziling Song and Bo Zhao and Mingjia Lv},
  title = {Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines},
  journal = {International Journal of Energy and Environmental Science},
  volume = {10},
  number = {6},
  pages = {162-173},
  doi = {10.11648/j.ijees.20251006.14},
  url = {https://doi.org/10.11648/j.ijees.20251006.14},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijees.20251006.14},
  abstract = {Inclined coal-seam open-pit mines with internal dumping commonly reserve an end-side retaining ditch when turning from horizontal advance to along-strike excavation. Selecting a single fixed ditch level is straightforward but ignores year-to-year variability in stripping volumes and haulage distances, which can inflate the combined transportation and secondary stripping costs. This study proposes a two-stage optimization framework for planning the ditch-height trajectory during the turning period. First, a maximum economic ditch height is derived via an economic-compensation model that balances the revenue from overlying coal recoverable after turning against the added costs of longer haulage and increased external dumping, with cost/revenue streams discounted using a compound-interest formulation. Second, within this upper bound, a total-cost minimization model couples annual stripping transportation costs during turning with the secondary stripping cost after turning. The model enforces annual waste-volume balance among inner dumping, ditch storage, and external dumping, preferred waste-flow directions, bounds on ditch height, and limits on height differences between adjacent years. Haulage distances are calculated from centroid locations of stripping and dumping stages extracted from 3DMine, and the resulting dynamic program is solved using a sequential recursion method. A seven-year case study (2023-2029) outputs an optimized fluctuating ditch scheme with yearly ditch heights of 214.5, 190.5, 206.7, 201.3, 189.6, 181.2, and 166.0 m, reducing the cumulative cost by 148.32 million CNY compared with the conventional constant-level ditch plan. The framework offers a practical decision tool for parameterizing retaining ditches and improving the overall economics of gentle-slope turning in inclined coal-seam open-pit mines.},
 year = {2025}
}

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TY  - JOUR
T1  - Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines
AU  - Yu Wen
AU  - Ziling Song
AU  - Bo Zhao
AU  - Mingjia Lv
Y1  - 2025/12/27
PY  - 2025
N1  - https://doi.org/10.11648/j.ijees.20251006.14
DO  - 10.11648/j.ijees.20251006.14
T2  - International Journal of Energy and Environmental Science
JF  - International Journal of Energy and Environmental Science
JO  - International Journal of Energy and Environmental Science
SP  - 162
EP  - 173
PB  - Science Publishing Group
SN  - 2578-9546
UR  - https://doi.org/10.11648/j.ijees.20251006.14
AB  - Inclined coal-seam open-pit mines with internal dumping commonly reserve an end-side retaining ditch when turning from horizontal advance to along-strike excavation. Selecting a single fixed ditch level is straightforward but ignores year-to-year variability in stripping volumes and haulage distances, which can inflate the combined transportation and secondary stripping costs. This study proposes a two-stage optimization framework for planning the ditch-height trajectory during the turning period. First, a maximum economic ditch height is derived via an economic-compensation model that balances the revenue from overlying coal recoverable after turning against the added costs of longer haulage and increased external dumping, with cost/revenue streams discounted using a compound-interest formulation. Second, within this upper bound, a total-cost minimization model couples annual stripping transportation costs during turning with the secondary stripping cost after turning. The model enforces annual waste-volume balance among inner dumping, ditch storage, and external dumping, preferred waste-flow directions, bounds on ditch height, and limits on height differences between adjacent years. Haulage distances are calculated from centroid locations of stripping and dumping stages extracted from 3DMine, and the resulting dynamic program is solved using a sequential recursion method. A seven-year case study (2023-2029) outputs an optimized fluctuating ditch scheme with yearly ditch heights of 214.5, 190.5, 206.7, 201.3, 189.6, 181.2, and 166.0 m, reducing the cumulative cost by 148.32 million CNY compared with the conventional constant-level ditch plan. The framework offers a practical decision tool for parameterizing retaining ditches and improving the overall economics of gentle-slope turning in inclined coal-seam open-pit mines.
VL  - 10
IS  - 6
ER  -

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Author Information

Yu Wen

College of Mining, Liaoning Technical University, Fuxin, China

Contact Email

http://orcid.org/0009-0007-1576-3800
Ziling Song

College of Mining, Liaoning Technical University, Fuxin, China;College of Environmental Science and Engineering, Liaoning Technical University, Fuxin, China
Bo Zhao

Huaneng Yimin Coal Power Co., Ltd. Yimin Open-pit Mine, Hulunbuir, China
Mingjia Lv

Shandong Gold Mining Co., Ltd. (Laizhou) Sanshan Island Gold Mine, Laizhou, China

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APA Style

Wen, Y., Song, Z., Zhao, B., Lv, M. (2025). Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines. International Journal of Energy and Environmental Science, 10(6), 162-173. https://doi.org/10.11648/j.ijees.20251006.14

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ACS Style

Wen, Y.; Song, Z.; Zhao, B.; Lv, M. Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines. Int. J. Energy Environ. Sci. 2025, 10(6), 162-173. doi: 10.11648/j.ijees.20251006.14

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AMA Style

Wen Y, Song Z, Zhao B, Lv M. Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines. Int J Energy Environ Sci. 2025;10(6):162-173. doi: 10.11648/j.ijees.20251006.14

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@article{10.11648/j.ijees.20251006.14,
  author = {Yu Wen and Ziling Song and Bo Zhao and Mingjia Lv},
  title = {Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines},
  journal = {International Journal of Energy and Environmental Science},
  volume = {10},
  number = {6},
  pages = {162-173},
  doi = {10.11648/j.ijees.20251006.14},
  url = {https://doi.org/10.11648/j.ijees.20251006.14},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijees.20251006.14},
  abstract = {Inclined coal-seam open-pit mines with internal dumping commonly reserve an end-side retaining ditch when turning from horizontal advance to along-strike excavation. Selecting a single fixed ditch level is straightforward but ignores year-to-year variability in stripping volumes and haulage distances, which can inflate the combined transportation and secondary stripping costs. This study proposes a two-stage optimization framework for planning the ditch-height trajectory during the turning period. First, a maximum economic ditch height is derived via an economic-compensation model that balances the revenue from overlying coal recoverable after turning against the added costs of longer haulage and increased external dumping, with cost/revenue streams discounted using a compound-interest formulation. Second, within this upper bound, a total-cost minimization model couples annual stripping transportation costs during turning with the secondary stripping cost after turning. The model enforces annual waste-volume balance among inner dumping, ditch storage, and external dumping, preferred waste-flow directions, bounds on ditch height, and limits on height differences between adjacent years. Haulage distances are calculated from centroid locations of stripping and dumping stages extracted from 3DMine, and the resulting dynamic program is solved using a sequential recursion method. A seven-year case study (2023-2029) outputs an optimized fluctuating ditch scheme with yearly ditch heights of 214.5, 190.5, 206.7, 201.3, 189.6, 181.2, and 166.0 m, reducing the cumulative cost by 148.32 million CNY compared with the conventional constant-level ditch plan. The framework offers a practical decision tool for parameterizing retaining ditches and improving the overall economics of gentle-slope turning in inclined coal-seam open-pit mines.},
 year = {2025}
}

Copy | Download

TY  - JOUR
T1  - Optimization of Retaining Ditch Height for Gentle Slope Turning in Inclined Coal Seam Open-pit Mines
AU  - Yu Wen
AU  - Ziling Song
AU  - Bo Zhao
AU  - Mingjia Lv
Y1  - 2025/12/27
PY  - 2025
N1  - https://doi.org/10.11648/j.ijees.20251006.14
DO  - 10.11648/j.ijees.20251006.14
T2  - International Journal of Energy and Environmental Science
JF  - International Journal of Energy and Environmental Science
JO  - International Journal of Energy and Environmental Science
SP  - 162
EP  - 173
PB  - Science Publishing Group
SN  - 2578-9546
UR  - https://doi.org/10.11648/j.ijees.20251006.14
AB  - Inclined coal-seam open-pit mines with internal dumping commonly reserve an end-side retaining ditch when turning from horizontal advance to along-strike excavation. Selecting a single fixed ditch level is straightforward but ignores year-to-year variability in stripping volumes and haulage distances, which can inflate the combined transportation and secondary stripping costs. This study proposes a two-stage optimization framework for planning the ditch-height trajectory during the turning period. First, a maximum economic ditch height is derived via an economic-compensation model that balances the revenue from overlying coal recoverable after turning against the added costs of longer haulage and increased external dumping, with cost/revenue streams discounted using a compound-interest formulation. Second, within this upper bound, a total-cost minimization model couples annual stripping transportation costs during turning with the secondary stripping cost after turning. The model enforces annual waste-volume balance among inner dumping, ditch storage, and external dumping, preferred waste-flow directions, bounds on ditch height, and limits on height differences between adjacent years. Haulage distances are calculated from centroid locations of stripping and dumping stages extracted from 3DMine, and the resulting dynamic program is solved using a sequential recursion method. A seven-year case study (2023-2029) outputs an optimized fluctuating ditch scheme with yearly ditch heights of 214.5, 190.5, 206.7, 201.3, 189.6, 181.2, and 166.0 m, reducing the cumulative cost by 148.32 million CNY compared with the conventional constant-level ditch plan. The framework offers a practical decision tool for parameterizing retaining ditches and improving the overall economics of gentle-slope turning in inclined coal-seam open-pit mines.
VL  - 10
IS  - 6
ER  -

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