Reaction of iron(III) oxide with nitric acid I'm currently working in a project in which I have to convert the iron oxides present in iron ore slime into ferric nitrate.

Iron ore slime is which has the particle size of below $\pu{0.15 mm}$ is being discarded as waste during the mining and processing stages iron ore and it will be stored at the tailing dam. It is estimated that $18~\%$–$25~\%$ of tailing will be generated during the processing of iron ore. The major compositions of iron ore slime are hematite, quartz, alumina, mica. So basically, it consists of ferric oxide and alumina, silica, magnesia, calcia, etc. impurities. I wanted to extract the iron part of the slime by converting it into water soluble ferric nitrate leaving behind the insoluble impurities. Even if some soluble impurities like clacium nitrate is formed then its not a problem.

I tried treating the slime with nitric acid both concentrated and dilute but no reaction was observed.
Please suggest me some useful ways to get ferric nitrate from iron ore slime — or any other steel industry waste product like mill scale, slag etc.
Yes, reacting iron(III) oxide with nitric acid would yield iron(III) nitrate.

$$\ce{Fe2O3 + 6HNO3 → 2Fe(NO3)3 + 3H2O}$$


  Iron(III) oxide react with nitric acid to produce iron(III) nitrate
  and water. Nitric acid - diluted solution. This reaction takes place
  slowly.(source)