Cement manufacture

A plant for producing white cement which comprises:

• a. an inclined rotary kiln for burning granular or pulverous material to produce cement clinker, said clinker being discharged from a lower material outlet end portion of the kiln;
• b. a supply of a reducing agent such as fuel oil having a viscosity of approximately 110 centistokes;
• c. a stationary pipe connected to said supply of reducing agent and positioned within the kiln proper and adapted to spray the cement clinker with the reducing agent prior to its discharge from the lower material outlet end portion of the kiln;
• d. a first rotatable upper conveyor in the form of a cylindrical drum rotatable on its axis and having on its surface means defining a plurality of circumferentially adjacent compartments configured to receive sub-portions of said cement clinker discharged from the lower material outlet end portion of the kiln;
• e. means to introduce a predetermined amount of water successively into each compartment of the cylindrical drum as the first conveyor rotates and prior to receiving the hot clinker from the kiln;
• f. means to spray cooling water onto the clinker substantially immediately after the discharge thereof from the rotary kiln;
• g. a lower pneumatic air permeable conveyor positioned and adapted to receive the partially cooled hot clinker from the first upper rotatable conveyor and to facilitate movement of the hot clinker away from the rotary kiln and first rotatable conveyor;
• h. a first casing surrounding the lower material end portion of the rotary kiln in sealed relation therewith and a second casing substantially encompassing said rotatable conveyor and said lower conveyor in sealed communicating relation with the lower material outlet end portion of the kiln and the first casing, said first and second casings defining a passage therebetween for passage of water evaporating from the cement clinker;
• i. means to produce sub-atmospheric pressure of the atmosphere within said second casing so as to be less than the pressure of the atmosphere within the material outlet end portion of the kiln whereby cooling water evaporating from the clinker exiting the kiln passes to the second casing and thus the evaporated water is prevented from entering the kiln proper;
• j. means to direct cooling air into the second casing, through the air permeable lower conveyor and from said second casing;
• k. sensing means to detect the pressure of the atmosphere outside and adjacent the material outlet end portion of the kiln;
• l. dampening means to control the flow of cooling air through the second casing;
• and
• m. means to vary the dampening of said dampening means in response to signals transmitted by said pressure sensing means, the hot cement clinker discharged from said rotary kiln onto said rotatable conveyor after being subjected to said reducing agent within the kiln proper, and after discharge of said clinker, said water spray means being positioned and adapted to spray approximately 30-40% water by weight of clinker thereon while said rotatable conveyor rotates the clinker toward the lower conveyor at a rotational speed such that approximately 85-90% of water evaporates substantially immediately therefrom, said clinker being thereafter deposited upon said lower pneumatic conveyor and conveyed away from said rotary kiln, the speed of conveyance of said clinker being controlled to permit substantially all of the remaining cooling water to evaporate from the cement clinker while being conveyed away from said kiln.

A plant for producing cement which comprises:

• a. an inclined rotary kiln for burning cement clinker having an upper material inlet end portion and a lower material outlet end portion for discharge of the clinker;
• b. at least one stationary pipe positioned within the kiln proper and connected to a supply of reducing agent in the form of fuel oil having a viscosity of approximately 110 centistokes, said pipe being adapted to spray said reducing agent onto the clinker immediately prior to discharge of the clinker from the kiln;
• c. a cylindrical drum rotatable about its axis and positioned adjacent the lower material outlet end portion of the kiln, said cylindrical drum having on its surface means defining at least one compartment configured to receive portions of the hot clinker discharged from the kiln;
• d. means to spray cooling water onto the clinker substantially immediately after being discharged from the kiln and while being transferred onto said cylindrical drum;
• e. a linear air permeable conveyor positioned below said cylindrical drum an adapted to receive clinker from said cylindrical drum and to facilitate movement of said clinker away from said cylindrical drum while the clinker is simultaneously cooled thereon;
• f. a casing attached in substantially sealed communicating relationship with the lower material outlet end portion of the rotary kiln so as to enclose the atmosphere adjacent said lower material outlet end portion of the kiln;
• and
• g. means to control the pressure of the atmosphere within said casing so as to be less than the pressure of the atmosphere within the material outlet end portion of the kiln to prevent cooling water evaporating from the cement clinker exiting the kiln from entering the kiln proper, thereby maintaining at minimum levels the water contact and heat losses occurring within the kiln proper.