Abstract: A method of calcining mineral components such as bituminous limestone in which heat is recovered from the calcining process and is used to liberate volatilizable substances within the mineral matter before the latter is subjected to calcination. The volatilized and pyrolytically decomposed substances form a fuel which is burned to produce the calcining gas mixture.

Abstract: In the treatment of bulk materials with hot gases below the melting point of the charge component it is desired to prevent a formation of undesired crusts during normal operation and when the rotary kiln is operated at a reduced speed during short-time trouble. For this purpose, a controlled dissipation of heat is effected in several sections of the rotary kiln in that the shell of the kiln and the refractory lining are cooled so that the temperature of that portion of the inside surface of the rotary kiln which is submerged below the charge is always maintained at or up to 50.degree. C. below the temperature of the charge disposed thereover.

Abstract: A process is disclosed for producing quicklime by a calcining treatment with a hot gas in a rotary kiln, wherein solid carbonaceous fuel for producing hot gas is fed into the charging end of the rotary kiln and an oxygen-containing gas is blown through nozzle blocks into the charge disposed over nozzle blocks in the heating-up zone beginning at the point where ignitable particles of the solid fuel first appear, the improvement wherein:(a) an oxygen-containing gas is blown through nozzle blocks into the charge disposed over nozzle blocks in that region of the heating-up zone which begins with the appearance of ignitable particles of the solid fuels and which ends where the temperature in the charge does not rise further;(b) oxygen-containing gases are blown through nozzle blocks into the charge disposed over nozzle blocks in a calcining zone which succeeds said heating-up zone and at such a rate that the temperature in the charge is held constant and for as long as the temperature remains constant,(c) oxygen-c

Abstract: Residual materials which become available in metallurgy and contain oxides and volatilizable non-ferrous metals or compounds thereof are treated in a rotary kiln with solid carbonaceous reducing agents and are thus directly reduced in a high proportion to sponge iron whereas a substantial part of their non-ferrous metal content is volatilized. The solids discharged from the rotary kiln are sieved with a parting size of about 3 to 10 mm, depending on the feed grading of the residual materials and their disintegration characteristics, so that a major part of the unmagnetic material is included in the fine fraction. The coarse fraction is subjected to an electro-slag resistance process. The fine fraction is subjected to an electro-magnetic separation. The magnetic fraction is subjected to the resistance slag-refining process. The unmagnetic fraction is incorporated in and bonded to the feed mixture for the rotary kiln by a tumbling or pelletizing operation.

Abstract: A process for the calcining of limestone or hydrated lime by thermal treatment thereof with hot gases in a rotary kiln through which the kiln atmosphere and the charge are countercurrently passed, which kiln is fed with solid carbonaceous fuel, is described. The invention resides in introducing an oxygen-containing gas into a horizontal region across the rotary kiln defined by a point along the length of the kiln where ignitable particles of said solid fuel first appear and a second point along the length of said rotary kiln which is spaced from the charging end of said kiln not more than 50% of the length thereof. The oxygen-containing gases are injected through nozzle blocks in said rotary kiln, and oxygen-containing gas is introduced into the free space of said kiln.

Abstract: When in the direct reduction of iron-oxide-containing materials in a rotary kiln solid, carbonaceous reducing agents having a high content of volatile constituents are charged to the rotary kiln at its charging end, a reoxidation of the sponge iron can readily occur in the final portion of the reduction zone unless a definite surplus of solid reducing agent is there maintained. To reduce the required surplus while still positively avoiding reoxidation, reducing gases and/or liquid hydrocarbons are introduced in said final portion by means of tubular air nozzles at least partially into the charge located above the air nozzles beginning with at least 75 percent metallization.

Abstract: In a Waelz process of volatilizing zinc and lead from iron-containing and oxide-containing material in an inclined rotary kiln, which is charged at its upper end with the material together with solid carbonaceous reducing agent having a high content of volatile combustible constituents, wherein the reduction and volatilization are effected below the softening point of the charge, metallic iron-containing material is discharged from the lower end of the rotary kiln, combustion air is sucked into the lower end of the rotary kiln, and the exhaust gases are sucked from the upper end, the improvement which comprises blowing oxygen-containing gases through tubular air nozzles into the charge disposed over said tubular air nozzles in that region of the heating-up zone which begins where ignitable particles of the solid reducing agent begin to occur and which terminates at up to 50 percent of the length of the kiln.

Abstract: Iron oxide-containing materials, such as iron ores, are directly reduced to produce sponge iron by a treatment with solid carbonaceous reducing agents in a rotary kiln at temperatures below the softening and melting point of the charge wherein the kiln atmosphere flows opposite to the direction of movement of the charge. At least part of the solid carbonaceous reducing agent is charged in an agglomerated form into the rotary kiln at the charging end thereof and oxygen containing gases are fed into the rotary kiln. A highly reactive, solid carbonaceous reducing agent containing 20-50% volatile constituents are charged in agglomerated form into the rotary kiln the charging end thereof and are heated up at such a rate that the reducing agent disintegrates into fine particles substantially in and before the end of the heating-up zone of the rotary kiln.

Abstract: A process for directly reducing iron oxide-containing materials to provide sponge iron by heating said iron oxide-containing materials in a rotary kiln while employing a solid carbonaceous reducing agent having a high content of volatile combustible components, wherein oxygen-containing gases are injected into the rotary kiln at a controlled rate through shell pipes into the free kiln space and the charge is moved through the rotary kiln countercurrently to the flow of the kiln atmosphere, is described. The invention lies in injecting oxygen-containing gases at controlled rates through nozzle blocks into the charge disposed over said nozzle blocks and in injecting oxygen-containing gases at controlled rates through shell pipes into the free kiln space in that region of the heating-up zone defined by a point along the length of the heating-up zone where ignitable particles of the solid reducing agent first appear and a second point before the reducing zone.