Phase II – Technology of  laboratory for performing the clinkers with low temperature (June 2008)

The objectives specific to this phase were the following:

• Sampling and physical-chemical characterization current raw materials (limestone, clay)
• Calculation of dosages for raw mix formula
• Performing of raw mix with mineralizators (laboratory technology)
• Characterization of clinker burning (through determinations of free CaO at different temperatures and through thermo-gravimetric analyze ATD)

Within the phase no. 2 laboratory technology in order to obtain the clinkers of Portland cement of low temperature, which is constituted in a real modality of decreasing the energetic consumptions and of CO₂ emissions at clinker manufacturing was performed.

Raw mix of usual raw materials (limestone, clay and pyrite ash) were prepared, characterized through a saturation degree in lime of  0,96 and silica modulus about 2 (current mixture used  in the cement plants from country) which were additived with different proportions of mineralizator substances.  In quality of mineralizators, substances from fluorides class (NaF and KF), oxides (SnO₂, TiO₂ and CuO) and mixed combinations fluoride – oxide (NaF+SnO₂ and NaF+CuO) were used.

Assessment of technological behavior at clinker burning of the raw mixes with mineralizators was made in comparison with that of non-mineralized raw meal and aimed to the influence exercised by mineralizators type and proportion on different stages of transformation for mineralized raw mix in the burning period, with finally forming of Portland clinker.

A benefic influence was stated on fluorides, especially of NaF dosed in proportion of  0,5-0,8%, in the range of temperatures comprised between  1100…1300 ^oC. The determinations of free CaO at 1350 ^oC (30 minute plateau) confirmed the fact that mineralized mixtures with fluorides present values of CaO below 1%, while at mineralized raw meal this value is over 3%.

Clinker burning temperature of the raw meals mineralized with fluorides or oxides may be reduced with up to 70 ^oC, with benefic effects on caloric consumptions and on CO₂ emissions_.
Mineralizator effect exercised by the combination fluoride + oxide is superior to individual action exercised by each component.