To help significantly reduce comminution energy consumption, MistyWest designed and built a laboratory scale apparatus to pulverize porous rock via rapid expansion of supercritical CO2.
Background
Envisioning Labs is an award-winning innovation and R&D firm focused on developing social and technological solutions that counter climate change and foster a carbon-neutral future. They partner with mission-aligned organizations, like MistyWest, to collaborate on solving complex challenges that support the UN Sustainable Development Goals.
The mining sector presents numerous possibilities for minimizing carbon emissions. One especially promising opportunity is comminution, the process of breaking rocks into smaller rocks, which consumes 3-4% of all electric power generated on the planet. Envisioning Labs’ subsidiary Rockburst Technologies is working to significantly reduce comminution energy consumption through their patent-pending Transcritical CO2 Pulverization (tCO2) technology, which ruptures rocks along grain boundaries without grinding media.
The Solution
MistyWest designed a ‘one-shot’ proof-of-concept apparatus with a 200ml pressure chamber that was filled with small rocks, pressurized with CO2, heated to supercritical state, and then rapidly vented into another chamber. The first attempt weakened the rocks enough that they disintegrated in-hand. Additional tests were able to directly produce fine powder in as little as two cycles.
Following the smashing success of the proof-of-concept, MistyWest’s engineering physics team, in collaboration with Rockburst, devised a novel thermodynamic cycle that was later designed and built into a 3m tall experimental system. The system featured industrial process control of hydraulic pistons, valves, active heating and cooling, along with instrumentation to automate the CO2 pulverization cycle and quantify the total energy required. This allowed Rockburst to gain valuable understanding of the parameter space while optimizing the “recipe” for maximum comminution performance with minimum energy consumption.
Outcomes
After taking over the experimental operation of the system, Rockburst Technologies and UBC Mining were able to successfully and safely demonstrate ~50% energy reduction. The industrial apparatus continues to demonstrate the technology of pulverizing rock with transcritical CO2, aiding Rockburst in securing investment for future development.
