I can't believe it took me so long to replace hoppers feeding into my pressure chamber with itemducts. Suddenly, everything is literally 10 times faster.
@
Tylor the only way to prevent metals from mixing is preventing them from being in the same smeltery in liquid form at all. Basically this means you need more than one smeltery if you're using that for your ore smelting stuff. Furthermore, you'll need (or may need) buckets of molten metal so you can whitelist specific liquiducts to output specific metals.**
For example, lets say you have one smeltery with one drain connected to a liquiduct, and you're smelting lead and silver in there because those two don't alloy. Half a silver ingot could end up in the ingot cast, and then some lead might smelt and get sucked into the liquiduct.
Suddenly automation halts as your smeltery can't figure out how to get silver into the ingot cast since the duct is clogged with lead. In this case you would need two separate drains with liquiducts not connected to each other, draining to separate basins or casting tables, with an additional whitelist on the liquiducts to prevent more than one metal type flowing through and clogging things up (since as you probably know the metal which drains first is the one on the bottom of the smeltery interface).
In summation the solution is to have drains which have metals whitelisted,
which also do not alloy. This means basically copper and aluminum, copper and tin, gold and silver, iron and nickel can't be in the same smeltery.
** this part is a bit of a pain. 1000mb of metal doesn't form a full number of ingots or a block. Therefore you need to smelt enough metal down and pump it into a portable tank, use the bucket to make the whitelist, and then dump the bucket back into said tank so that it can drain back into the smeltery.