@Omakoshark absolutely. With a little patience and some work, you'll be able to use this rock in no time.
Simply, place a small pump/powerhead (or do water changes) in the container (the lowest spot possible for the highest stirring ability) - you want a nice amount of water flow. Begin performing 20%-50% water changes weekly, exactly like you would on your main display / main system.
You can either elect to use RODI doing water changes or use fully mixed salt for water changes. Either way, the goal is to bring the water chemistry (Check your water for runoff of the chemicals you used and leaching of whatever may be in the rocks porous areas) to a healthy place. You basically are aiming for new, healthy, unadulterated rock that you can use anywhere.
Refreshing the water with water changes eventually will bring your rock to exactly where you need it in order to use it for any projects.
There are generally more ways than one to do this, however, this is one method that is a simple and mostly hands off procedure that rewards you with usable rock.
We will be treating around 500 LBS of "Old-Dead-Base-Rock" I will make sure we put together a small writeup on how we achieve what it is I have described above.
Good luck my friend ;Joyful