Residual Coal Pillar Gasification with Pillar-Side Backfilling
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Solution Overview
Problem
The challenge of remining residual coal pillars in residual mining areas is complicated by their scattered occurrence, complex geological environment, and high mining risk, including spontaneous combustion and instability due to high temperatures during gasification, which poses safety and stability issues.
Innovation Solution
A method combining pillar-side backfilling and in-situ gasification, involving ground-based backfilling facilities and underground gasification devices, to ensure stability and safety by forming a comprehensive mining system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional physical mining methods are used to remine residual coal pillars, then the mining process can be completed, but the operation becomes complicated, mining cost increases, and safety risks arise from spontaneous combustion and roof instability
Solution Approach 1:
The patent replaces traditional mechanical mining methods with in-situ gasification technology. Instead of physically extracting coal through complex mining equipment and procedures, the coal is converted into gas in place through controlled gasification reactions, eliminating the need for complex mining operations and equipment while improving safety and efficiency
Solution Approach 2:
The residual coal pillar serves itself as the fuel source for gasification. The coal in place is converted into combustible gas through controlled reactions with injected gases, eliminating the need for external mining operations. The coal pillar essentially mines itself through in-situ transformation
2Reliability
If in-situ gasification is applied to residual coal pillars, then mining safety and efficiency improve, but high temperature causes thermal fracture and thermal expansion of coal pillars and rock strata, potentially leading to roof caving and gas leakage
Solution Approach 1:
The patent applies backfilling to the goaf space before conducting in-situ gasification. This preliminary action creates a protective buffer that prevents thermal fracture and roof caving during the high-temperature gasification process, while still allowing the gasification to proceed safely and efficiently
Solution Approach 2:
The backfilling material serves as a cushioning layer between the coal pillar and the roof rock strata. During gasification, this cushioning layer absorbs and distributes thermal stresses, preventing thermal fracture and roof caving while maintaining overall system stability
3Stability of the object's composition
If residual coal pillars are left in place to support the goaf, then roof stability is maintained, but coal resources are wasted and spontaneous combustion risk increases
Solution Approach 1:
The patent replaces physical coal extraction with in-situ gasification, converting the coal resource into useful combustible gas while maintaining goaf support. This substitution allows complete utilization of the coal resource without the need for physical mining operations that would compromise roof stability
Solution Approach 2:
The patent changes the physical and chemical state of the coal from solid to gas through controlled gasification reactions. This parameter change allows the coal to be fully utilized as an energy resource while the gasification process itself maintains the structural integrity needed for goaf support
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 the safety and efficiency of remining residual coal pillars, reduces waste, and stabilizes the roof, minimizing the risk of mine fires and environmental pollution.
Implementation Method 1
carrying out side supporting on the residual coal pillar in a goaf by using the pillar-side backfilling
Implementation Method 2
underground coal gasification technology is a chemical mining method that gasifies coal resources into combustible gas in situ
Implementation Method 3
enabling coal of the residual coal pillar to start burning and continuing a gasification reaction
Implementation Method 4
high temperature produced in the gasification process may lead to thermal fracture and thermal expansion of isolated coal pillars and roof and floor rock strata
Implementation Method 5
high temperature produced in the gasification process may lead to thermal fracture and thermal expansion of isolated coal pillars
Data Source
AI summary
Disclosed is a method for remining a residual coal pillar in a residual mining area by collaboration of pillar-side backfilling and in-situ gasification. The method includes the following steps of: ascertaining geological and hydrological conditions, a geometric shape and a reserve of a residual coal pillar; carrying out side supporting on the residual coal pillar in a goaf by using a pillar-side backfilling method; and carrying out the underground gasification mining on the residual coal pillar by means of an underground coal gasification process.