The CO2 storage is inorganic as bicarbonate dissolved in seawater and is considered permanent (60,000-100,000+ years). This process occurs as rocks weather and release magnesium or calcium cations. The "enhanced rock weathering" (ERW) process is all about speeding up the rate of release of these cations. Taking them out of a closed mountain not in the tropics and grinding them up, increasing their reactive surface area, speeds up the weathering process by many millions of years or more.

See: The role of soils in the regulation of ocean acidification - https://royalsocietypublishing.org/doi/full/10.1098/rstb.202...