Process for producing a cement clinker at low temperature

A process for producing a cement clinker comprising the steps of:

• (i) mixing one or more starting materials providing each:
• at least one or more of CaO, SiO2, Al2O3, and Fe2O3;
• and, optionally, SO3;
• and/or at least other one or more compounds comprising the elements of these oxides, to form a raw meal comprising CaO, SiO2, Al2O3, and Fe2O3;
• and, optionally, SO3;
• and/or at least other one or more compounds comprising the elements of these oxides, wherein the molar ratios among the aforementioned oxides and/or other one or more compounds comprising the elements of these oxides is given by Formula I:
• (CaO)1(SiO2)a(Al2O3)b(Fe2O3)c(SO3)d (Formula I)
• wherein:
• “a” is comprised from 0.05 to 1,
• “b” is comprised from 0.1 to 0.6,
• “c” is comprised from 0.001 to 0.25, and
• “d” is comprised from 0 to 0.3,
• and wherein at least 35% (p/p) of the starting materials of the raw meal have a critical microwaves absorbance temperature (Tc) comprised from 15 to 650° C. and a critical microwaves absorbance time (tc) comprised from 1 min to 1 h;
• (ii) heating the raw meal by irradiating with microwaves until reaching a sintering temperature comprised in a range from 300 to 950° C., wherein the irradiating time to reach the sintering temperature is comprised in a range from 15 min to 3 h;
• (iii) maintaining the microwave sintering temperature of step (ii) during a time comprised from 1 min to 3 h by further irradiating with microwaves;
• and
• (iv) cooling the clinker obtained in step (iii).