The Essentia Smeltery is great but it is still throwing a lot of Flux into the air and is not very efficient. In order to be able to make something more efficient, you need to dig into Alchemical Metallurgy once again.
You now know how to make Alchemical Brass. You can also make metals such as Thaumium. Make one ingot of Thaumium to move on. Revisit your research table as well.
In the Crucible, using 2 Arcane Pedestals and an iron ingot as the catalyst will net you two Thaumium ingots. Don’t forget to sliver out the remaining Essentia.
Once completed, you can craft Thaumium Blocks, Armor, plates and Tools.