FORFARANDE OCH ANORDNING FOR GENOMFORANDE AV EN ATMINSTONE PARTIELL KALCINERING AV ETT FORVERMT, PULVERFORMIGT KALKHALTIGT RAMATERIAL, SPECIELLT CEMENTRAMJOL

摘要

A method of burning pulverous raw materials in a rotary kiln is disclosed wherein the material is preheated and at least partially calcined prior to subjecting it to a finishing heat treatment such as sintering. The calcination of the raw material is accomplished prior to the final burning by feeding preheated at least partially calcined raw material to the upper inlet end portion of an inclined rotary kiln and mixing it intimately with a fuel capable of producing a combustible gas. The combustible gas thus produced is passed to a calcination chamber communicating with the upper end of the rotary kiln. Substantially uncalcined raw material is suspended in the gas mix while an oxygen-containing gas capable of supporting combustion in the calcination chamber is provided causing the oxygen-containing gas to be ignited and calcined substantially isothermally. A rotary kiln plant for practicing the method is also disclosed in which the raw material is at least partially calcined in a calcination chamber communicating with the rotary kiln.