I have a small problem with iron. Have maybe 300 ml of solution with 15-20g of iron. Solution has some silver in it with gold foils and flakes. Would like to clean up iron to get valuables out. I added small amount of silver in to solution to use up possible nitric. Im thinking of adding sulfuric as suggested, but i don't know how much. I have 96% sulfuric but not much experience of sulfuric, especially this strong. Sure i will do it carefully by tiny amount at the time but still wondering.
The values are going to be cemented out in the bottom of the solution. The iron present, would have cemented out everything, copper, silver, gold, other PMGs.
How I got mine out, I let it settle for a while, about a week. I siphoned off the solution without disturbing any sediment on the bottom. I had 2000 ml , I siphoned off down to 150-200 ml of solution, leaving everything on the bottom.
The remaining solution, I boiled until dry. I put it all in a melt dish and heated with a torch to oxidize the iron, not hot enough to melt any. Once it was oxidized, I repeated the process of nitric acid boils to remove the iron oxides using diluted nitric acid. Wash, rinse, repeat until nitric boils were clear.
That took about 4 days, slowly repeating the steps until I was left with a clear solution and gold foils/powders/sediment. Then went to aqua regia, refined it twice in aqua regia for the final result.
usually I process 14-18k nuggets and Placer gold from my operations.
I'll be washing it and getting the chemicals off in the morning 
