Drill Head Gas Suction for Contamination-Free Rock Chip Sampling
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Solution Overview
Problem
Existing air drilling techniques for exploration drilling suffer from contamination of rock chip samples due to contact with sidewall rock and inadequate flow of compressed air, resulting in small and broken rock chip samples.
Innovation Solution
A drill head design featuring a supply passageway for compressed gas and a return passageway with strategically positioned ports that create a gas pressure difference to draw loose material into the return passageway and transport it away from the cutting face via an inner tube, reducing contamination and improving sample size and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If compressed air is supplied down the hole through a hollow drill rod in rotary air blast drilling, then rock chips can be blown up to the surface, but significant contamination of the rock chips occurs from contact with the sidewall rock
Solution Approach 1:
The drill rod is segmented into an outer drill rod and an inner tube that extends inside it, creating separate flow paths. The supply passageway is formed between the outer drill rod and inner tube, while the return passageway is inside the inner tube, preventing contamination of rock chips during transport to the surface
Solution Approach 2:
The inner tube acts as an intermediary structure that creates a dedicated return path for rock chips inside the drill rod. This intermediary element separates the rock chip transport path from the compressed air supply path and prevents contact with the hole sidewall, thereby eliminating contamination
2Quantity of substance
If compressed air is injected into the bottom of the hole via an annular area between the drill rod and inner tube in air core drilling, then rock cuttings can be blown up the inner tube, but the forceful supply of compressed air causes contamination between rock cuttings from the cutting surface and cuttings from higher layers
Solution Approach 1:
The harmful forceful injection of compressed air at the bottom of the hole is extracted and replaced by a suction mechanism. The drill head includes a return passageway with an opening proximate to the drill cutters that draws rock chips away from the cutting face through suction, eliminating the contamination caused by forceful air injection
Solution Approach 2:
Instead of forcing compressed air upward to blow rock chips to the surface, the invention inverts the approach by creating a suction effect that draws rock chips into the return passageway and transports them upward, thereby preventing contamination from forceful air supply
3Quantity of substance
If existing air drilling techniques are used, then rock chips can be removed from the cutting face, but the flow of compressed air is inadequate to blow larger rock chips and they break into smaller pieces
Solution Approach 1:
The invention inverts the conventional approach of blowing rock chips with compressed air by using a suction mechanism. The return passageway creates a vacuum effect that draws rock chips away from the cutting face through the opening proximate to the drill cutters, preventing breakage while effectively removing even larger rock chips
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
The drill head design enhances the quality and size of rock chip samples by minimizing contamination and efficiently removing larger rock chips, leading to improved productivity in exploratory drilling operations compared to conventional air drilling techniques.
Implementation Method 1
a flow of gas directed into the return passageway by the one or more ports generates a gas pressure difference between the opening and the return passageway, to thereby cause loose material to be drawn into the return passageway through the opening
Implementation Method 2
loose material to be drawn into the return passageway through the opening and transported away from the drill head via the inner tube
Data Source
AI summary
A drill head including: an elongate housing, a first end of the housing being coupled to an end of a drill pipe in use; a base at a second end of the housing, one or more drill cutters being attached to the base; a supply passageway at least partially within the housing, the supply passageway being supplied with a flow of gas in use; a return passageway at least partially within the housing, a first end of the return passageway being connected to an end of an inner tube extending inside the drill pipe in use, and a second end of the return passageway forming an opening in the base proximate to the one or more drill cutters; and one or more ports for directing at least some of the flow of gas from the supply passageway into the return passageway in a flow direction extending away from the base and towards the inner tube, to thereby cause loose material to be drawn into the return passageway through the opening and transported away from the drill head via the inner tube in use.