Still takes time to run the recycling systems and therefor money.

Also, think of it this way - you spend $X per 1000 bricks, but you can only sell 10% of those bricks. The remaining bricks get melted down at a cost of $Y. You then spend $9X/10 to produce another 900 bricks, of which only 90 are sellable. Rinse and repeat until all bricks are viable. You’ll have spent a hell of a lot of money producing the later batches.