Underground Coal Mining via Intermediate Bridges and Sealing Layers
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Solution Overview
Problem
Existing methods for recovering unexploited coal in boundary open-pit mines face challenges such as low resource recovery rates, high transportation costs, and slope stability issues, with steep end-slope mining being inefficient and underground mining being restricted by construction difficulties and air leakage.
Innovation Solution
An underground mining method involving shaft construction, intermediate bridges, sealing of slopes, digging of auxiliary and main inclined shafts, constructing a water-sealed pit bottom, and laying water purification slopes to facilitate efficient coal extraction while maintaining slope stability and reducing air leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steep end-slope mining is used to recover unexploited coal, then resource recovery rate is improved, but slope stability deteriorates
Solution Approach 1:
The patent transitions from surface-level steep end-slope mining to underground mining operations. By introducing vertical shafts and horizontal roadways into the underground dimension, the system recovers coal resources without altering the surface slope geometry, thus maintaining slope stability while achieving resource recovery through subsurface access points
Solution Approach 2:
The patent introduces intermediate bridges as intermediary structures that connect different underground levels and provide support. These bridges act as mediators between the mining operations and the overlying slope, distributing loads and preventing direct disturbance to the slope stability while enabling coal recovery at multiple levels
2Productivity
If underground mining is used to improve coal recovery, then resource recovery rate is improved, but construction complexity and cost increase
Solution Approach 1:
The underground mining system is divided into modular components: multiple shafts (first main inclined shaft, second main inclined shaft, auxiliary vertical shafts), intermediate bridges at different levels, and segmented mining areas. This segmentation allows for phased construction and operation, reducing overall complexity by breaking down the large-scale underground mining project into manageable units
Solution Approach 2:
The intermediate bridges serve multiple functions simultaneously: they provide structural support for the slope, create access pathways for mining equipment, serve as platforms for shaft construction, and enable ventilation and drainage. This multi-functionality reduces the need for separate specialized structures, thereby reducing overall construction complexity
3Productivity
If underground mining is implemented, then coal recovery is improved, but air leakage during ventilation worsens
Solution Approach 1:
The patent employs sealing layers (including water-sealed layers and clay sealing) as flexible barrier films that line the underground openings, shafts, and intermediate bridges. These sealing films conform to the irregular underground geometry while effectively blocking air leakage pathways, maintaining ventilation efficiency throughout the mining operations
Solution Approach 2:
The water-sealed layer acts as an intermediary barrier between the underground mining environment and the external atmosphere. This water-filled sealing layer provides a flexible, self-adjusting seal that prevents air leakage while allowing for minor movements and deformations in the surrounding rock and structures
4Stability of the object's composition
If shaft construction platform is positioned higher, then slope stability is improved, but transportation distance increases
Solution Approach 1:
The patent uses inclined shafts that traverse through the slope at an angle, creating a three-dimensional transportation pathway. This inclined dimension allows the shaft construction platform to be positioned higher on the stable slope while the shaft itself provides a direct diagonal route to the coal seam, reducing the horizontal transportation distance compared to surface-level access
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances resource recovery rates, reduces transportation costs, and improves slope stability by using a network of shafts and bridges to efficiently extract coal while minimizing air leakage and environmental impact.
Implementation Method 1
laying mining area clay on the working slope where no intermediate bridge is built and on a side slope with an outcrop of the coal seam as a sealing layer to seal the slopes
Implementation Method 2
filling clay into the digging space to form an artificial water barrier layer
Implementation Method 3
subsurface flow wetlands for purifying mine water discharged from the auxiliary vertical shafts and collecting atmospheric precipitation in the pit
Data Source
AI summary
An underground mining method for unexploited coal in a boundary open-pit mine is provided. A shaft construction platform is arranged at one rock step to two rock steps above a coal seam. Intermediate bridges are built starting from a pit bottom. Mining area clay is laid on a working slope where no intermediate bridge is built and on a side slope with an outcrop of the coal seam as a sealing layer to seal the slopes. Auxiliary vertical shafts and main inclined shafts are dug. The pit bottom is dug downward to form a digging space on a side close to the working slope between two adjacent ones of the intermediate bridges, and clay is filled into the digging space to form an artificial water barrier layer. A roadway communicating the main inclined shafts and the auxiliary vertical shafts is constructed, and a coal seam stope face is arranged.