"The Plomosas feed will be batched through the plant for a few days each month in batches of 2,500t. The agreement will be reviewed annually after the first trial month batch"
Note that they are not selling the ore to Grupo Mexico. They are paying them to process it and selling a concentrate. If they haven't delivered 2,500 tons then they have not run a batch. The San Antonio mine is very big, there's probably a reason they want the ore delivered in 2,500 ton batches.
