Engineering360: "Iceland Project Is Turning CO2 to Stone"

A bit confused here: "CarbFix scientists inject carbonated water into basalt and hope it reacts with calcium and magnesium in the rock"

but then later you say

"CarbFix has demonstrated that over 95% of the CO₂ injected at the Hellisheidi geothermal power plant was mineralized within two years."

Clearly it is reacting, so where does the 'hope it reacts' enter into the picture?