In-situ Trona Undercut Mining via Solvent Dissolution
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Solution Overview
Problem
Current in-situ solution mining methods for trona beds face challenges such as limited productivity, high costs due to the need for extensive drilling, susceptibility to 'bicarb blinding,' and contamination from chloride and other soluble minerals, which reduce liquor quality and increase mining hazards.
Innovation Solution
The method involves injecting a solvent through unlined boreholes to systematically undercut the trona bed, creating a large surface area for dissolution while preventing contact with the roof to minimize contamination, allowing gravity to assist in exposing fresh trona and reducing chloride contamination by allowing the roof to sag without breaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If in-situ solution mining is used to extract trona, then mining safety is improved and operational costs are reduced, but productivity is limited due to small dissolution surface area
Solution Approach 1:
The invention transitions from conventional vertical borehole dissolution to horizontal undercut formation, creating a large surface area interface between solvent and trona ore. This dimensional change allows the solvent to contact and dissolve trona across an extended horizontal plane, dramatically increasing the effective dissolution surface area and thus productivity while maintaining the safety benefits of in-situ mining.
Solution Approach 2:
The undercut is designed to be a dynamic, evolving structure that progresses through the ore body as dissolution continues. The mobile nature of the undercut allows it to continuously expose fresh trona surfaces to the solvent, maintaining high dissolution rates and productivity throughout the mining operation rather than being limited by a static dissolution interface.
2Ease of manufacture
If extensive drilling is performed to access trona beds, then ore extraction is enabled, but costs increase significantly
Solution Approach 1:
The method performs preliminary undercut formation through controlled dissolution before full-scale production begins. By creating the undercut structure in advance through targeted solvent injection, the system prepares the ore body for efficient subsequent dissolution, reducing the need for extensive additional drilling and infrastructure development.
3Productivity
If solvent contacts ore roof, then dissolution continues, but contamination from chloride and soluble minerals increases
Solution Approach 1:
The invention extracts or removes the ore roof material through controlled dissolution and collapse, creating a physical separation between the solvent and the contaminant-bearing roof. By taking out the roof structure, the system prevents direct contact between the solvent and chloride-containing minerals, thereby protecting liquor quality while maintaining dissolution productivity through the exposed undercut surfaces.
Solution Approach 2:
The undercut structure serves as an intermediary zone between the solvent and the ore roof. This intermediate space allows dissolution to continue efficiently while preventing direct solvent-roof contact that would cause contamination. The undercut acts as a buffer or mediator that decouples the dissolution process from the contaminant source.
4Area of stationary object
If mechanical mining is used initially, then large trona surface area is exposed, but mining costs and hazards increase
Solution Approach 1:
The invention replaces mechanical mining systems with a chemical dissolution system. Instead of using machinery to physically break and expose trona surfaces, the system uses solvent injection to chemically dissolve and expose the ore, creating the undercut structure and exposing surface area through dissolution rather than mechanical force, thereby eliminating the need for complex mining infrastructure and associated hazards.
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 enhances productivity by creating a large trona surface area without initial mechanical mining, reduces contamination, and maintains liquor quality, thereby improving the efficiency and safety of trona extraction.
Implementation Method 1
dissolving at least a portion of the desired solute to form a liquor
Implementation Method 2
the downward movement by gravity of fractured ore rubble into the undercut
Data Source
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AI summary
In-situ solution mining method of an ore bed, particularly containing trona, which comprises exposing to a solvent an ore region inside a borehole drilled in the ore, and dissolving a desired solute within the exposed region to provide a liquor and create a voided 'undercut', such undercutting making the ore susceptible to gravitational loading and crushing. Unexposed ore falls into the undercut by gravity without breaking the ore roof resulting in exposure of fresh ore to the solvent and in preventing solvent exposure to contaminating material near the roof. The desired solute is eventually dissolved away in the entire bed from its floor up to its roof. Solvent injection may be delivered through a conduit positioned inside the borehole, and may be moved by retracting or perforating the conduit. The method may employ an advancing undercut initiated up-dip and traveling down-dip, or a retreating undercut initiated down-dip and traveling up-dip.