Methods for producing cement comprising a supplementary cementitious material, and cement obtainable thereby

Abstract

The invention is concerned with a method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of: producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material; producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm; and blending the milled cement clinker and the supplementary cementitious material; wherein the method is a continuous process comprising the step of calcining the raw material of the supplementary cementitious material in a kiln with a separate heating unit and/or combustion unit. Further, the invention is concerned with a method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of: producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material; producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm, wherein at least 5 wt % of the particles have a particle size of above 4.75 mm; and blending the milled cement clinker and the supplementary cementitious material. The invention is also concerns a cement comprising milled cement clinker and a supplementary cementitious material, wherein the supplementary cementitious material comprises an amorphous constituent of more than 30 wt % as measured by XRD, wherein the supplementary cementitious material comprises less than 70 wt % of inert components selected from the group comprising mullite, spinel, feldspar, diopside, mica, or combinations thereof, and wherein the color of the cement in the range of 130-160, 130-160, 120-160, wherein the measurement of the cement color is conducted by a RGB2 colorimeter, wherein the colors are referenced to a RGB scale of 0 to 255.

1 . Method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of:
 producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material;   producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm; and   blending the milled cement clinker and the supplementary cementitious material;   
       wherein the method is a continuous process comprising the step of calcining the raw material of the supplementary cementitious material in a kiln with a separate heating unit and/or combustion unit. 
     
     
         2 . The method according to  claim 1 , wherein the milling of the calcined raw material of the supplementary cementitious material and the milling of the cement clinker are conducted together, subsequently to mixing the components, or wherein the milling of the calcined raw material of the supplementary cementitious material and the milling of the cement clinker are conducted separately, followed by mixing the milled components. 
     
     
         3 . The method according to  claim 1 , wherein the calcining of the raw material of the supplementary cementitious material is conducted by heating the raw material at a heating rate of 200° C./min or less, preferably 150° C./min or less, more preferably 100° C./min or less to a distinct calcining temperature. 
     
     
         4 . The method according to  claim 1 , wherein the calcining of the raw material of the supplementary cementitious material is conducted at temperature of 500 to 980° C., preferably 700 to 950° C. 
     
     
         5 . The method according to  claim 1 , wherein the raw material of the supplementary cementitious material has an average particle size of 5 to 250 mm, preferably 10 to 200 mm, more preferably 20 to 150 mm. 
     
     
         6 . The method according  claim 1 , wherein the content of the supplementary cementitious material in the cement is 1 to 50 wt %, preferably 5 to 45 wt %, more preferably 10 to 40 wt %, most preferably 15 to 35 wt %, based on the overall weight of the cement. 
     
     
         7 . The method according to  claim 1 , wherein the calcining retention time of the raw material of the supplementary cementitious material at the calcining temperature is selected, depending on the particle size of the raw material of the supplementary cementitious material. 
     
     
         8 . The method according to  claim 1 , wherein the method further comprises the step of crushing the raw material of the supplementary cementitious material prior to calcining, preferably by a device selected from the group comprising a roller press, a jaw crusher, a hammer rusher, a cone crusher, or a combination thereof. 
     
     
         9 . The method according to  claim 1 , wherein the method further comprises the step of screening the raw material of the supplementary cementitious material prior to calcining, wherein the raw material of the supplementary cementitious material is separated in at least two fractions, which differ in their average particle sizes, wherein one of the fractions is used for calcining, preferably by a device selected from the group comprising a trommel screen, a vibrating screen, an air sieve, or a combination thereof. 
     
     
         10 . The method according to  claim 1 , wherein the method further comprises the step of storing and/or preheating the raw material of the supplementary cementitious material prior to calcining. 
     
     
         11 . The method according to  claim 1 , wherein the method is a continuous process comprising the step of calcining the raw material of the supplementary cementitious material in a kiln, wherein the kiln is preferably a rotary kiln and/or a vertical shaft kiln. 
     
     
         12 . The method according to  claim 11 , wherein calcining the raw material of the supplementary cementitious material is conducted with in a kiln with a separate heating unit and/or combustion unit, wherein the heating unit is preferably a device selected from the group comprising an electrical furnace, a solar tower, a waste heat device, a plasma burner, or a combination thereof, and wherein the combustion unit is preferably a device selected from the group comprising a grate furnace, a rotary kiln, a fluidized bed, or a combination thereof. 
     
     
         13 . The method according to  claim 1 , wherein the method further comprises the step of cooling the supplementary cementitious material after calcining, preferably with gas containing 0-21% oxygen, wherein the cooling is preferably conducted with a cement cooler and/or a rotary heat exchanger, wherein the cooler exhaust gas is preferably returned up-stream to the process. 
     
     
         14 . Method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of:
 producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material;   producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm, wherein at least 5 wt % of the particles have a particle size of above 4.75 mm; and   blending the milled cement clinker and the supplementary cementitious material.   
     
     
         15 . Cement comprising milled cement clinker and a supplementary cementitious material, wherein the supplementary cementitious material comprises an amorphous constituent of more than 30 wt % as measured by XRD, wherein the supplementary cementitious material comprises less than 70 wt % of inert components selected from the group comprising mullite, spinel, feldspar, diopside, mica, or combinations thereof, and wherein the color of the cement in the range of 130-160, 130-160, 120-160, wherein the measurement of the cement color is conducted by a RGB2 colorimeter, wherein the colors are referenced to a RGB scale of 0 to 255.