Open-pit Stripping for Underground Subsidence Control
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Solution Overview
Problem
Underground mining in coal mines results in large subsidence areas, requiring costly transportation and filling materials, which is inefficient and expensive.
Innovation Solution
A method that utilizes soil and rock strippings from an adjoining open-pit mine to fill and compact subsidence fractures, employing dynamic compaction and cement grouting to stabilize the surface, reducing material and transportation costs while ensuring safe mining practices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filling materials are transported from outside the mining area to fill subsidence fractures, then the subsidence area can be treated, but the transportation and material costs become high
Solution Approach 1:
The patent combines the open-pit mining operations with subsidence area treatment by using the strippings generated during open-pit mining as filling materials for underground mining subsidence fractures. This integration eliminates the need to transport filling materials from external sources, thereby reducing both transportation and material costs while maintaining effective subsidence treatment.
Solution Approach 2:
The system makes the open-pit mine serve its own waste material (strippings) as a resource for treating the underground mining subsidence problem. By utilizing self-generated strippings as filling material, the method eliminates dependency on external material sources and reduces overall operational costs.
2Reliability
If filling materials are transported from outside the mining area, then subsidence fractures can be filled, but transportation costs increase
Solution Approach 1:
The patent merges the open-pit mining process with subsidence treatment operations by utilizing strippings from open-pit mining as immediate filling material for underground subsidence fractures. This combination eliminates the need for separate material transportation operations, thereby reducing transportation time and associated costs.
3Quantity of substance
If strippings from open-pit mine are used to fill subsidence area, then material and transportation costs are reduced, but the filling process becomes more complex requiring screening and classification
Solution Approach 1:
The patent segments the filling process into distinct stages based on fracture size: medium and small fractures are filled with screened soil first, then small rock blocks; large fractures are filled with large rock blocks first, then small rock blocks. This segmentation allows for systematic processing of strippings through screening and classification, making the complex process manageable and efficient.
Solution Approach 2:
The patent applies different filling materials and methods to different locations and fracture types within the subsidence area. Medium and small fractures receive soil and small rock blocks, while large fractures receive large rock blocks first. This localized approach optimizes the use of screened strippings based on specific fracture characteristics.
4Reliability
If multiple filling stages are used for different fracture sizes, then filling effectiveness improves, but the operation time increases
Solution Approach 1:
The patent divides the filling operation into concurrent segments for different fracture sizes. Medium and small fractures are filled with screened soil and small rock blocks simultaneously, while large fractures are filled with large rock blocks and small rock blocks in sequence. This segmented approach allows parallel processing, improving overall productivity while maintaining filling effectiveness.
Data Source
AI summary
A method for controlling a subsidence area caused by underground mining in an adjoining open-pit mine, applied in an open-pit and underground coordinated mining process. In the method, a ground subsidence area caused by underground mining and production is directly filled and covered with overburden materials such as soil and rock discharged from an adjoining open-pit mine; small and medium fracture zones and large fracture zones caused by mining are timely backfilled, tamped, and levelled according to areas before the ground subsidence area appears, the thickness of the levelled soil layer is kept above 1 m, and the area slope is controlled within 7°. By fully using overburden materials from an adjoining open-pit mine, the method controls a subsidence area caused by underground mining and greatly shortens the discharge distance of the overburden materials from the adjoining open-pit mine, also solves the safety problems such as air leakage and spontaneous combustion of coal caused by fractures in mine subsidence, and brings significant economic and social benefits.