Abstract: A sinterable mixture comprising iron-containing materials and solid fuel is sintered on a sintering machine; to decrease the rate at which exhaust gas is to be removed and to produce a desirable sinter, a part of the exhaust gas is enriched to an oxygen content of up to 24% by the addition of higher-oxygen gases and is then recirculated as a recycle gas, and exhaust gas is removed as a tail gas from the process only at a rate which corresponds to the rate of the gas which is formed during the sintering process plus the rate of the gas added for enriching plus the rate of inleaked air which has infiltrated from the outside minus the rate of oxygen consumption.

Abstract: For a separation into a purified fraction and a polluant concentrate, contaminated soils are ground in a drum to which loose pieces acting like grinding elements have been added and with a net energy input of 4 to 16 kWh per 1000 kg throughput. The speed is 50 to 90% of the critical speed ##EQU1## The suspension discharged from the drum is separated by sieving into a relatively coarse fraction and a relatively fine fraction. The relatively coarse fraction is discharged as a purified fraction and the relatively fine fraction is desludged. The separated sludge is dewatered and is subsequently delivered as a polluant concentrate. The desludged remainder of the finer fraction is dewatered and is subsequently delivered as purified soil.

Abstract: Disclosed is a process for burning cattle dung at a temperature of from 500.degree. to 780.degree. C., preferably from 650.degree. to 780.degree. C., in the presence of one or more aluminum-containing substances selected from the class consisting of bauxite, kaolin and aluminum compound-containing ash from furnaces for firing solid fuels. A major part of the alkalies contained in the cattle dung and a substantial part of the chlorine are retained in combined form in the resulting furnace ash.

Abstract: A process for sintering iron ore mixtures containing solid fuels on sintering strands in which uniform sinter is obtained throughout the depth of the charge by igniting the surface of the charge and subsequently treating it with hot gases under a set of defined conditions.

Abstract: A process and apparatus for sintering material are described wherein a moist sintered material is passed by a travelling grate through an ignition zone, a sintering zone, and a cooling zone with strand cooling of the sintered material being effected. The sintered material is passed through a purging zone of higher flow rate and lesser area than a subsequent initial cooling zone, followed by a final cooling zone. Cooling air from both the purging zone and the initial cooling zone is heated by the sintered material and removes dust particles therefrom. The resultant dust-laden air from the purging zone is de-dusted by conventional means, and the dust-containing heated air from the initial cooling zone is conducted to the sintering zone and forced downwardly through the moist material in the sintering zone.

Abstract: A process for controlling the speed of strand sintering machines through utilization of the temperature of collected waste gas as measured in the collector pipe as the controlled variable provides improved response by utilizing as an additional controlled variable the temperature of the waste gases at the windboxes. Either the average temperature of those waste gases that leave the windboxes at a temperature above approximately 100.degree. C. or the location of the burn-through point as determined from the temperature of the waste gases at the windboxes can be used as the additional variable. In the latter case, the temperature of the collected waste gases can be used to automatically control the desired variable in a secondary cascade-type control loop in which the location of the burn-through point is the actual value and the travel speed is the regulated quantity.

Abstract: A process for controlling the quality of sintered iron ore in which the Fe.sup.+ content of the sintered or is regulated by controlling the recycled-fines feed rate. The recycled-fines feed rate, determined by a prior art recycled-fines balance controller, is modified by a desired fines withdrawal rate generated in an Fe.sup.+ content controller as the difference between the actual Fe.sup.+ content of the sintered ore and a desired content. In a preferred form, the difference between the recycled-fines feed rate and the desired fines withdrawal rate is also applied to the Fe.sup.+ content controller.

Abstract: A process and apparatus for sintering material are described wherein a moist sintered material is passed by a travelling grate through an ignition zone, a sintering zone, and a cooling zone with strand cooling of the sintered material being effected. The sintered material is passed through a purging zone of higher flow rate and lesser area than a subsequent initial cooling zone, followed by a final cooling zone. Cooling air from both the purging zone and the initial cooling zone is heated by the sintered material and removes dust particles therefrom. The resultant dust-laden air from the purging zone is de-dusted by conventional means, and the dust-containing heated air from the initial cooling zone is conducted to the sintering zone and forced downwardly through the moist material in the sintering zone.