He said they have approximately 1.5 million tons (1.5 millones de toneladas), and there may be more because there are other heaps/piles of tailings below/under the main one which can't be estimated properly at present.
He seems to be talking about the tailings pile itself, and not the tailings sent to the plant in Parral. You asked him how much material the JV had at the government processing plant in Parral, but he didn't address that.
Still, it's impressive to me that you got him to respond at all. I've tried twice, got nothing either time.