As noted by others you have a ...

As noted by others you have a wide range of solids-liquid separation options available to remove iron particulates from solution.  Your suggestion of magnetic separation is unconventional, but there is a ballasted clarification technology out of Singapore, I believe, that uses an iron ballast and magnetic separation.  I wouldn’t recommend you use the ballast as you wouldn’t be able to separate your iron sludge, but their magnetic separator may be of use.  Dissolved iron removal involves oxidation to produce a precipitate, which you have.  Chemically enhanced gravity separation may work, but it would be as effective as filtration, which is the conventional approach, with or without flocculants aids.  One unusual technology I recommend you consider is the Heron Industries SAF process.  It uses flotation technology that has been around for 100 years in the mining sector and is based on blending a hydrophobic surfactant, as a foam, with the water and floating the solids out.  Completely different from a DAF, as it does not use high pressures or dissolved gas. The company has about 200 industrial applications in the US.  A key advantage is the very small footprint and high solids content of the sludge it skims off the tank.  Because the surfactant that is used is hydrophobic, water drains out of the sludge very quickly - resulting in 15 - 20 percent solids without dewatering equipment.