Patent ID: 7235117

Claim:
A process for producing a porous sulpha sponge iron compound having a plurality of Fe 2 /Fe 3 cores forming interstatially stabilized clusters which comprises the steps of magnetically separating haematite having the following composition: SiO 2 3.28% Al 2 O 3 3.74% Fe 2 O 3 92.40% CaO 0.42% MgO 0.19% P 2 O 5 0.08% Na 2 O 0.00% SO 3 0.04% Cl 0.0001% Mn 2 O 3 0.14% and having trace elements such as Au, Pt and Ag therein, dissolving the separated haematite in hydrochloric acid to form an acidic solution, concentrating and treating said acidic solution with ammonium hydroxide to form a precipitate, depositing the precipitate on haematite, and drying and powdering the haematite with deposited precipitate to obtain the porous sulpha sponge iron compound.