Emre Işık
Chemical Engineer / Lyksor Chemistry Inc. Cement Admixtures Sales Manager
Introduction
Cement additives are utilized over half a century in order to increase productivity of grinding process. However, in present circumstances, they are indispensable construction materials since cement quality is vitally important and in particular, due to the responsibility of being a country in an earthquake zone. Cement additives are such materials referred in the literature as “chemical admixtures” added during standard production of cement.
Grinding, the most important stage in the cement production process, is an operation consuming the maximum energy. Accordingly, vertical mills became an important part of the grinding operation as an alternative to ball mills commonly used in the sector because of low energy cost thereof in recent times of high-costs of energy.
The key issue in vertical mills is the difficulty of maintaining a stable operation and steadfast regime. The factors, such as how easily or difficult clinker is ground, temperature, and sizes of the materials fed, have impact on performance of mills.
The most important input ensuring formation of deposits, minimizing vibration, and controlling temperature in vertical mill operations is water pulverized into mill, which is very innocently our life source. Even though water is considered as a convenience in cement production, it may also yield to adverse disappointing results in terms of cement quality. Therefore, water may be a very compromising material when used in cement production.
Pre-hydration
It is highly possible to encounter pre-hydration during grinding as result of supplying water into a mill and causing dampening of cement. We may consider this outcome as a disadvantage of vertical mills in comparison to ball mills.
However, it is now possible to contain pre-hydration with the utilization of advanced technology of cement additives.
Cement additives has become indispensable inputs for the sector by providing operational convenience in vertical mills (e.g., deposit formation, vibration elimination, supplying pulverized water at lower amounts), and consequently, affecting cement quality positively (in terms of viscosity, workability, cement and concrete strength, and socket arrangement).
Supplying pulverized water into vertical mills is one of the unavoidable but most effective methods in order for controlling vibration, formation of a good grinding deposit on the grinding table, and maintaining the exit temperature of mills. Although it is a challenging target to zero the amount of pulverized water with chemicals in vertical mills, it is still possible to see some rare and short-term examples in the world.
Industrial Operation Example – 1
As seen in the table below, it is not possible to deny the advantage of vertical mills when compared to total energy consumption thereof to the same of ball mills.
Industrial Operation Example – 2
In the table below, the impact of cement chemicals on vertical mill operations and cement quality is obvious.
Conclusion
Positive impact of cement additives on vertical mills may be listed as follows;
1. It helps to reduce the amount of pulverized water supplied into mills by 40-50%. This, in turn, helps lowering the hot gas need of a mill leading to lower energy consumption.
2. A much more stable and constant operation is possible in mills. Particularly, it facilitates reaching to much higher tonnages in production by means of stable operation of mills. Moreover, it enables working at much lower vibration values. Consequently, it reduces maintenance costs for mills.
3. We may interpret the advantage of working with lower amount of water as lowered levels of pre-hydration of cement. This will return as compressive strength.
4. The key benefits of such cement produced in vertical mills by utilizing cement additives in terms of concrete performance are low water requirement, cement viscosity, and workability.