Abstract: A process and apparatus for desulfurizing coal which removes sulfur in the inorganic and organic form by preferentially heating the inorganic iron sulfides in coal in a flowing gas to convert some of the inorganic iron sulfides from a pyrite form FeS.sub.2 to a troilite FeS form or a pyrrhotite form Fe.sub.1-x S and release some of the sulfur as a gaseous compound. The troilite and pyrrhotite forms are convenient catalyst for removing the organic sulfur in the next step, which is to react the coal with chemical agents such as alcohol, thus removing the organic sulfur as a liquid or a gas such as H.sub.2 S. The remaining inorganic sulfur is left in the predominantly higher magnetic form of pyrrhotite and is then removed by magnetic separation techniques. Optionally, an organic flocculant may be added after the organic sulfur has been removed and before magnetic separation. The flocculant attaches non-pyrite minerals with the pyrrhotite for removal by magnetic separation to reduce the ash-forming contents.

Abstract: An improved method of removing pyritic sulfur and other contaminants from the coil in a coal-oil slurry. In such a slurry, raw pulverized coal is suspended in fuel oil. In practicing the process, the slurry is heated to a temperature of about 220.degree. C., at which temperature hexagonal pyrrhotite is converted to highly ferromagnetic monoclinic pyrrhotite which can be removed by a magnetic separator.

Abstract: A separator to receive a fluid slurry containing magnetic particles and non-magnetic particles and operable to increase the concentration of the magnetic particles at one region within the slurry and deplete the concentration of the magnetic particles at another region of the slurry. There are no moving parts in this separator and its operation is continuous.

Abstract: A magnetic separator having multiple staggered layers of porous magnetic material positioned to intercept a fluid stream carrying magnetic particles and so placed that a bypass of each layer is effected as the pores of the layer become filled with material extracted from the fluid stream.