High temperature calcination improves the strength of cement clinker

High temperature calcination and rapid cooling are both important measures to improve the quality of cement clinker, and in this paper we talk about what important impact high temperature calcination has on the quality of cement clinker.

Reviewing the previous research data, we can easily find that increasing the calcination temperature can improve the strength of cement clinker, and this view has also been verified in production practice. Some experts layer studied the influence of different calcination temperatures on the performance of clinker doped with compound mineralizer, the experimental results show that the clinker rate value is exactly the same, but the strength of clinker with the increase in combustion temperature and increase.

When the calcination temperature was increased from 1350°C to 1400°C and 1425°C, respectively, the 3d, 7d and 28d compressive strength increased from 23.6MPa, 41.3MPa and 52.7MPaMPa to 27.2MPa, 44.0MPa, 57.9MPa and 41.4MPa, 59.2MPa, 64.0MPa, respectively.

The alkali content of limestone in a cement plant is slightly high, and in order to reduce the calcination temperature and improve certain properties of cement, 1% of sulfuric acid slag is mixed into limestone, which makes the SO3 in clinker rise by 0.2% and the MgO content increase by 0.12%, resulting in a clinker heat consumption reduction of 80 KJ/Kg, a kiln cylinder surface temperature drop of 19℃, and an output increase of 1.4t/h, but the 7d strength decreases by 0.5MPa. This shows that the calcination temperature is lowered, the strength is also reduced.

Why high temperature calcination can improve the strength of clinker? Our technical experts have analyzed this.

1. High-temperature calcination can improve the content of silicate minerals in clinker and increase the content of A ore. High calcination temperature can burn SM higher material, so that the content of silicate minerals is increased, which can also improve the A ore content. Clinker firing process mainly occurs as follows: C2S + CAO → C3S. A ore is C3S with a small amount of solid solution of Fe2O3, Al2O3, MgO. calcination temperature increase can promote the above reaction, reduce F-CAO and increase C3S. from the above equation can be seen, each reduction of 1 mole of CAO can increase 1 mole of C3S. if by weight If calculated by weight, each 1% reduction of F-CAO can increase 4.07% of C3S.

2. High temperature calcination can improve the water hardening activity of A and B ores. High calcination temperature, in addition to the A ore content, may also be related to the increase in the activity of A and B ore. It is shown that the calcination temperature increases and A ore changes from MⅠ to MⅢ. MⅢ type hydrates slowly in the early stage, but the pulp is dense and the strength increases after 3d. When the calcination temperature was increased from 1400℃ to 1500℃, the compressive strength of C3S increased from 13.0MPa, 18.3MPa, 25.6MPa and 30.0MPa to 32.5MPa, 52.3MPa, 52.3MPa and 77.5MPa at 3d, 7d, 14d and 28d, respectively. The influence of calcination temperature on the strength of C3S is obvious. The calcination temperature increased from 1400℃ to 1500℃, the strength increased significantly, and the compressive strengths of 3d, 7d, 14d and 28d increased from 0.8MPa, 1.7MPa, 2.2MPa and 6.5MPa to 1.8MPa, 4.6MPa, 10.2MPa and 30.8MPa, respectively.

3. High-temperature calcination can reduce the actual content of the aluminum-containing phase, thus reducing its standard consistency water consumption and improving its compatibility with water reducing agents. In addition to the increase in calcination temperature can make the raw burned material and lightly burned material to reduce the viscosity of the liquid phase, the iron phase can be dissolved into more Al2O3, so that the iron phase from C4AF to C6A2F transformation, thereby reducing the C3A content. the reduction of C3A content can reduce the standard consistency of cement water consumption, improve its compatibility with water reducing agents.

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