JB3 said:
In a 'by-product', if it remains viable to 'produce' the main commodity (say, zinc), the cost of production of the by-product approaches zero.
Edit: on top of that, any 'profit' made in selling the by-product over its effectively zero production cost goes to making the primary product even more viable to produce, further driving up the supply of the by-product...
In a 'by-product', if it remains viable to 'produce' the main commodity (say, zinc), the production of the by-product will remain viable too.
In a 'by-product', if it does NOT remain viable to 'produce' the main commodity (say, zinc), the production of the by-product will NOT remain viable too.
Silver comes with the main product.
Silver goes with the main product.
If demand for zinc stays the same as before, or drops for whatever reason, then it doesn't make economical sense to use silverbased, or any profits to produce more.
And likely, profit even won't be achieved at all in the first place, because a dropping price will erase them, as to punish / correct for overproduction.
When mining, or recycling, processes ground, or waste, then this effectively links everything that in what is processed, together, and this link is not lost only in a specific direction, but in both.
Maybe an idea to recognize that your / any equation has two sides.