Operations

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In comparison to other deposits around the world, the Holbrook Basin has several competitive advantages:

• Significant potash resources at relatively shallow depths;

• Existing infrastructure of rail, road, gas and power provides immediate access to markets and reduces capital costs;

• Year-round warm weather reduces capital and operating costs;

• No competition with the oil and gas industry;

• Proximity to large year-round potash markets in Arizona, California and Mexico.

Potash in the Holbrook Basin lies in two primary seams within the Supai Formation, the KR-1 and KR-2 seams. The KR-1 seam lies above the KR-2 seam and is unevenly distributed throughout the basin. The KR-2 seam is the primary target for delineation and development. In 2012, North Rim produced an NI 43-101 compliant technical report which estimated the Holbrook Project Resource in accordance with CIM standards and using a 40%-ft (grade x thickness) cutoff estimated the following:

Selective solution mining is an efficient, environmentally conscious method for extracting potash. It works by circulating heated brine, which is water saturated with common salt (sodium chloride) but undersaturated with potash (potassium chloride), through high‑grade ore zones. The heat, which requires a dedicated energy source, enhances the dissolution of valuable potassium chloride while leaving sodium chloride in place. As the process involves salts, it is carefully engineered to manage corrosion, scaling, and brine chemistry. This targeted approach minimizes waste, reduces surface tailings, conserves water, and can be paired with low‑energy crystallization methods, making it a sustainable and cost‑effective choice for modern potash production.

The Vertical Cavern Method of selective solution mining is shown in the four images below:

Image source: Qiu, B. & Hardy, M., An Overview of Solution-Mining Methodologies for Potash Mining, SMRI Spring Technical Conference 2023 (used with permission).

Selective solution mining of potash offers significant economic and environmental advantages compared to traditional underground mining methods.

Economic Advantages:

• Lower Upfront Capital Costs (CAPEX):
  
  
  • No need for expensive shafts, tunnels, or extensive underground infrastructure, dramatically reducing the initial investment required to start a mine.
     
  • Faster project development and implementation, leading to quicker returns on investment.
     
• Reduced Operating Costs (OPEX):
   
  • No Underground Workforce: Eliminates the need for a large underground labor force, reducing associated costs, safety risks, and training requirements.
     
  • Less Equipment: Requires significantly less heavy machinery and equipment compared to conventional mining.
     
  • Lower Break-Even Price: Can operate profitably at lower potash prices, providing a better hedge against market volatility.
     
  • Access to “Stranded” Deposits: Can extract potash from deeper or geologically complex deposits that would be uneconomical or too risky to access with conventional methods.
     
  • Scalability and Repeatability: Projects can often be developed in smaller, modular units, allowing phased expansion and reduced initial financial commitment.
     
  • Lower Transportation and Logistics Costs: Facilities can sometimes be “right-sized” for rural locations, reducing the impact on community infrastructure and optimizing transport.
     
• Higher Resource Recovery: Some selective solution mining techniques can extract more potash from the same deposit compared to conventional methods.
  

Environmental Advantages:

• Minimal Surface Disturbance/Footprint:
   
  • No Salt Tailings Piles: A major advantage is leaving salt waste (sodium chloride) underground, eliminating the need for massive, environmentally problematic surface tailings piles that can lead to salinization of land and water.
     
  • No Brine/Slimes/Cooling Ponds: Many selective solution mining processes reduce or eliminate the need for large surface evaporation ponds, which are prone to leaks and can impact local ecosystems.
     
  • Smaller Surface Facility Area: The overall surface footprint of the mining operation is much smaller.
     
• Reduced Water Consumption:
   
  • While solution mining uses water, selective methods often require significantly less fresh water than conventional solution mining, and can often utilize brackish or non‑potable groundwater, preserving freshwater resources.
     
  • The process can involve continuous recycling and reuse of brine, minimizing water loss.
     
• Lower Energy Consumption and Carbon Footprint:
   
  • Eliminates the energy needed for crushing and grinding rock.
     
  • Some projects can self-generate power using natural gas, reducing reliance on grid power—which may be coal‑fired—leading to net GHG reductions.
     
  • Newer technologies aim to optimize heat transfer, further reducing energy input for heating and cooling brines.
     
• Improved Safety: Eliminates the inherent risks of underground mining, such as tunnel collapses, fires, and dust exposure.
   
• Less Subsidence: Compared to conventional underground mining, solution mining generally results in less ground subsidence, protecting surface infrastructure and ecosystems.
   
• Preservation of Local Habitat: The minimal footprint and lack of waste piles help preserve surrounding natural environments and habitats.
   

In summary, selective solution mining offers a cleaner, more sustainable approach to potash extraction, aligning with modern environmental goals while delivering compelling economic benefits through lower initial investment and operational efficiencies.