Method of providing a reactive cement constituent or concrete additive
A method of providing a reactive cement constituent or concrete additive includes at least the following steps: a) reworking a carbon-containing heap comprising at least coal and clay-bearing rock; b) extracting at least calcined rock; c) producing fine-grain calcined rock; and d) providing fine-grain calcined rock for use as cement constituent or concrete additive.
1 . A method of providing a reactive cement constituent or concrete additive, comprising:
a) identifying a heap starting material from a heap being an accumulation of tailings of extracted material from a coal mine comprising at least coal and clay-bearing rock, wherein the heap starting material comprises at least calcined rock including autogenously calcined clay formed through burnout of the coal;
b) selectively reworking the heap starting material and extracting the at least calcined rock from the heap starting material;
c) producing fine-grain calcined rock from the at least calcined rock; and
d) providing the fine-grain calcined rock, the fine-grained calcined rock being suitable for use as cement constituent or concrete additive.
2 . The method of claim 1 , wherein the calcined rock comprises clay.
3 . The method of claim 1 , wherein step b) comprises at least one of gravimetric sorting or sensory sorting.
4 . The method of claim 1 , wherein at least step b) or step c) comprises at least one of electrostatic separation or magnetic separation.
5 . The method of claim 1 , further comprising, after step b), conditioning at least a portion of the at least calcined rock by at least partly comminuting or drying the at least calcined rock.
6 . The method of claim 1 , wherein a separated fraction of the fine-grain calcined rock is mixed in step d) with further fractions of a cement composition.
7 . The method of claim 1 , further comprising establishing a hydraulic property of a cement composition or concrete composition by using calcined clay or rock from the fine-grain calcined rock.
8 . The method of claim 7 , further comprising using the calcined clay or rock as a substitute for cement clinker, fly ash or other synthetic pozzolans or natural pozzolanic additives.
9 . The method of claim 1 , further comprising producing a cement composition or concrete composition using calcined clay or rock from the fine-grain calcined rock.
10 . The method of claim 1 , wherein the heap starting material has an average portion of the coal of at most 15%.