Block Cave Drawbell Profile for Rapid Establishment
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Solution Overview
Problem
Conventional block cave mining methods face challenges in establishing new caves efficiently and economically, particularly in deeper, lower-grade, and harder rock environments, with high upfront capital costs and long lead times, as well as safety concerns due to high stress zones and seismic risks.
Innovation Solution
A new block cave concept with a single extraction level and no undercut level, utilizing a specific drawbell profile and drilling and blasting method to achieve high draw column heights of at least 450 m, reducing establishment time and capital costs, and improving safety by minimizing exposure to high stress zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional block cave mining methods are used with undercut levels, then ore extraction can be achieved, but establishment time and capital costs increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-fracturing the rock mass above the extraction level through controlled blasting before formal cave establishment. This pre-conditioning creates a more caveable rock structure, allowing the cave to propagate more quickly and reducing the overall establishment time from conventional 7 years to potentially 3-5 years while maintaining extraction efficiency
Solution Approach 2:
The patent segments the cave establishment process into distinct phases: initial extraction level development, pre-fracturing operations, controlled cave propagation, and production phase. This segmentation allows for optimized timing and resource allocation in each phase, reducing total establishment time while ensuring safe and efficient ore extraction
2Ease of manufacture
If conventional undercut levels are developed, then ore body fragmentation is achieved, but development cost and complexity increase
Solution Approach 1:
The patent merges the undercutting function and extraction level development into a single integrated process. By conducting controlled fracturing blasts from the extraction level itself rather than requiring a separate undercut level, the patent eliminates the need for additional development infrastructure while still achieving the necessary ore body fragmentation for efficient caving and extraction
3Ease of manufacture
If personnel work in undercut levels for blasting activities, then ore fragmentation is achieved, but safety risks from high stress zones and seismic activity increase
Solution Approach 1:
The patent uses controlled fracturing blasts as an intermediary mechanism to achieve ore fragmentation without requiring personnel to be physically present in high-stress undercut zones. The blasting operations can be conducted from safer locations, and the rock mass itself acts as the medium through which fragmentation energy is transmitted, reducing direct human exposure to hazardous conditions
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 approach enables quicker and more cost-effective development of block caves with improved safety and sustainability by reducing exposure to high stress zones and allowing for automation and remote operation, while maintaining high draw column heights and efficient ore extraction.
Implementation Method 1
Block cave mining is an efficient technique that leverages gravity and induced stress to support the efficient extraction of ore from an ore body
Implementation Method 2
undercutting is a process whereby a slice of the ore body (typically 5 to 20 m high) is mined using various drill and blast techniques
Data Source
AI summary
A block cave has a draw column height of at least 450 m, a caved volume, a single extraction level and noundercut level, a plurality of drawbells extending upwardly from the extraction level to the caved volume, and a plurality of pillars separating the drawbells and supporting the rock mass above the extraction level. Each drawbell has a drawbell height of at least 25 m. Each drawbell has the following profile when viewed from a direction perpendicular to a drawbell drive in the extraction level: a throat section having opposed parallel side walls extending upwardly from the extraction level, a tapered section above the throat section, and an undercut section above the tapered section.