The optimal solution depends on the mods you have. Off the top of my head:
RotaryCraft processing claims to have 5.06x ore multiplication for regular ores in NEI
Mekanism has 5x ore processing, though the initial steps are slow
Extra Utilities has a 1 coal + 1 ore = 3 ingot recipe in the QED and is super easy to set up
ThaumCraft lets you convert ores to native ore clusters which double, and can be thrown into the multi-block furnace for extra nuggets
If you have RotaryCraft and are far enough in to get a gas turbine running, a 2:1 acceleration gearbox will get the torque at the perfect spot and the extractor will handle all the stages for you. It's literally 4 blocks, and one is bevel gears because the extractor wants power from the bottom. A single piece of ore takes about 5 seconds to go through, but all stages run at once so the bottleneck is stage 3 which takes about 3 seconds each time (it's longer per ore, as it has 50% chance to double output at each step). You'll also get secondary ores, though not a huge amount that puts it squarely first for ore yield. The main concern with using a gas turbine for the speed is that the gas turbine chugs fuel pretty hard, a bucket lasts maybe a minute. A solar tower could probably also provide the needed power, but I've yet to try it.
Using Mekanism for 5x ore processing is pretty much the most complex method of ore multiplication, at least that I know of. On the plus side, the only requirements are power (which could be fed by the solar panels that will be on the salination plant) and a small source of sulphur (either the ore or gunpowder, last I checked). Most of the annoyance here is automating sulphuric acid production, and it'll take a fair bit of space to make it run fast enough.
Extra Utilities ore processing is incredibly easy to set up, the downside here is that it requires coal (actual coal, charcoal isn't going to work). Just make a QED, put a bunch of ender-flux crystals around it (they power it), and shove your ore/coal in there. The in-game description of the ender-flux crystals claim they need RF to run, but it seems to be incorrect...or it's smart enough to not do that when generators are disabled.
Mekanism also has a very fast 3x ore processing method that only requires power, which makes it good for a self-contained unit. The 4 machines involved can all be overclocked pretty hard, and will feed into each other when configured.
ThaumCraft in this case would be "I want as much as humanly possible and don't have the above options". Automation can be finicky at times, and you may not value the extra nuggets enough to consider this worth it. However, ore clusters are useful since they count as double in the smeltery, and have a pretty simple crucible recipe (the crucible can be automated) that only needs 1 ordo and 1 metallum, which are both pretty common (ordo can be made from stone slabs, metallum comes from most metals).