Novel Stone Dust Looping Process for Ventilation Air Methane Abatement

This multi‐phase project is concerned with the mitigation of mine site greenhouse gases (GHG) and specifically focuses on the development and demonstration of a novel stone dust looping (SDL) process for the abatement of ventilation air methane (VAM). The relevant research and development activities of this multi‐phase program of study are:

• Phase I:  Examination of the performance characteristics of a laboratory‐scale proof of concept SDL prototype under controlled settings;
• Phase II: Mine site process integration and bench scale demonstration;
• Phase III: Demonstration of the SDL concept in the once‐through single‐reactor configuration (i.e. no stone dust regeneration) using an existing 1 m3/s fluidised‐bed plant at the University of Newcastle; followed by techno‐economic assessment of the single‐reactor configuration and scale‐up studies;
• Phase‐IV: Piot‐scale demonstration of the SDL concept in the twin‐reactor configuration using a 200 m3/h setup (to be designed, built and commissioned as part of Phase‐IV); followed by techno‐economic assessment of the twin‐reactor configuration and scale‐up studies.

The final phase of the project focusses on the development of the stone dust looping technology. The previous phases of the project, which focused on the demonstration of the concept at laboratory and prototype-scale, identified two versions of the SDL process, namely:

• V1. A single-reactor configuration which is simple but lacks features such as drainage gas integration, CO2 capture and the ability to regenerate calcium oxide particles through the calcination of stone dust particles.
• V2. A twin-reactor configuration which is more complex but features drainage gas integration, in-situ CO2 capture, a manifold gas switching (MGS) train and the necessary hardware for calcination of stone dust particles.

Previous research and development efforts directed towards the SDL process have primarily focused on the first version of the process (i.e. single-reactor configuration). However, phase 4 aimed to investigate and assess the merits of the second version (i.e. twin-reactor configuration) from both a technical and economic point of view. Hence the objectives of Phase-IV of the SDL program of study were defined as:

• Design, construction and commissioning of a 200 m3/h (~56 L/s) twin-reactor pilot-scale unit;
• Experimental campaign using the 200 m3/h pilot-scale unit;
• Scale-up rules derivation; and
• Techno-economic assessment.

The key findings for the project were:

• Overall assessment: from a technical standpoint, the stone dust looping process is capable of abating ventilation air methane at concentrations less than alternative technologies.
• An optimised stone dust looping process was identified to address the limitations of manifold gas switching.
• Challenges for the practical implementation of the SDL process.
• The levelised abatement cost for the SDL process would likely be greater than other abatement processes.

Stages 1, 2, 3 and the most recently completed stage 4 are provided as a single report.