I might try a floor buffer with a red pad and some detergent first. If that doesn't get the stains out try "calcium lime and rust remover",
its in the janitorial section at La Casa Depot.
It may slightly etch the surface. So do a test area first and have water handy to dilute it real quick, its pretty mild though. I saw it used at the Kaufman House down in Palm Spring to remove some stains on the white pool deck and it worked real well. Every other cleaner we tried although more expensive did nothing . Then find a sealer or wax for the Terazzo, off hand I can't recommend any