My preferred setup is a little more complex. I have an input chest and a sorting machine. Then from the the sorting machine I sort them into the macerator or the furnace or back to the chest overflow chest. In that physical order. Then I have a retriever sucking from those three into the input chest. Finally there is a separate colored line for ingots to leave the system. What happens is the retriever controls how fast the system runs. It doesn't pull new ores or dusts till the macerator and furnace are empty. But anything coming out of the macerator usually goes straight into the furnace.