My read on this is that the tailings will have up to 10% unrecovered graphite/graphene in them (eg 90% recovery rates).  It is the graphite/graphene that is the benefit to the concrete industry.  Assuming the tailing are granular (sand or coarser) and the graphite/graphene ‘activates’ the concrete as earlier tests suggest they could be worth something.   Without the waste graphite I suspect the tailing would have no value and would have to be dealt with in a traditional means.  If the tailings are silt or clay like, the same holds true as they cause problems in concrete.

.... Been There