Calcined clay tailings and/or calcined mine waste, and associated systems and methods

A system for calcining tailings, comprising:

• a calciner configured to receive and heat dewatered tailings to a temperature no more than a predetermined threshold temperature of no more than 1000° C. and produce calcined tailings;
• a burner configured to produce heated air having a temperature within a range of 600-1100° C., wherein the dewatered tailings are heated in the calciner via the heated air;
• and
• a milling device configured to receive the calcined tailings and produce a milled product comprising—
• a percent alumina within a range of 1-15%, and
• a percent silica within a range of 10-30%.

A system for calcining tailings, comprising:

• a precalcining subsystem configured to process dewatered tailings and produce processed tailings, wherein the dewatered tailings comprise clay minerals;
• a burner configured to produce a heated air stream having a temperature within a range of 600-1100° C.;
• and
• a calciner downstream of the precalcining subsystem and configured to heat the processed tailings via the heated air stream to produce calcined tailings, wherein the calcined tailings comprise a temperature no more than 1000° C., a pozzolan, and a moisture content of no more than 0.1%.