Development history and evolution of cement grinding aids

Since the 1930s, cement grinding aids have been used in the cement industry. The earliest patents of the 1930s tested and used powdered mixtures of mineral oil, animal oil and petroleum cracking residues to improve the water resistance of cement products and improve the high early strength and processability of cement. It is combined with hydrochloric acid or calcium chloride, lime-type calcium-containing material and an inert adsorbent mineral material as a carrier. These admixtures greatly improve the water resistance of the cement series and improve its processability.

In the 1930s, "dissolved oil" was successively developed. In the 1940s, "Petroleum Hydrocarbon Emulsifier" was developed. In the patent, mineral oil and saponified products and sodium saponified oil of cereal oil were introduced as hydrating emulsifiers for spraying. Dispersion and lubrication, in which a large amount of organic alcohol ether diethylene glycol monoether and diethylene glycol solvent are used as a mixed solvent in the industrial field. In the 1960s, cement dewatering agents were vigorously developed, which improved and improved the performance of many cement series products. At this time, the series of Chengshui agents have been extended to various categories of nonionic surfactants, and several products in the water reducing agent series also act as grinding aids. After entering the 1980s, cement admixtures explicitly proposed to improve the grinding performance in cement processing in the performance of the cement series.

In the cement industry, the energy consumption of the grinding process is very high. For every ton of cement produced, about three tons of various materials need to be ground, and the electricity consumption of the grinding process accounts for 60-70% of the total electricity consumption of the cement production. However, about 97% of the energy consumed in the grinding process becomes waste energy and is wasted. Only a small part of the energy (.06 to 1%) is used to increase the specific surface area of the material. In today's increasingly fierce market competition, especially after implementing the 150 standard in the cement industry, how to improve the quality of cement and reduce the cost of cement has become a top priority for all manufacturers. Of course, there is also a need for green production. In order to reduce energy consumption, save energy, and improve grinding efficiency, it is one of the effective methods to add a small amount of grinding aid to the grinding process to improve the grinding efficiency. Adding a small amount of grinding aid during the grinding process can increase the yield under the same conditions of cement fineness and mill power consumption; it can also increase the specific surface area of the cement under the same conditions of cement production and mill power consumption. Improve the strength and quality of cement. Therefore, the use of grinding aids is an effective measure to improve cement grinding efficiency and reduce unit power consumption, and has great technical and economic benefits.

There are many kinds of grinding aids for cement grinding aids, and the grinding grinding effect varies greatly. There are more than one hundred applications. Grinding aids, the compositional differences can be divided into compounds and mixtures. The grinding aid can be divided into solid, liquid and gas grinding aids depending on the physical state of the addition. Solid grinding aids are generally in the form of granules or powders, and liquid grinding aids are mostly solutions or emulsions. The use of liquid grinding aids is easier to control than the use of solid grinding aids.

The cement grinding aid must meet the requirements of the national building materials industry standard. The building material industry standard is the technical basis for assessing whether the process admixture for cement grinding can be used for cement production. This standard stipulates the scope and requirements, test methods and evaluation criteria for the cement admixture process admixture on the performance of cement and concrete. The grinding aid must be a type of polar material with a very large dipole moment or an excellent surface active material. The most common organic substances at home and abroad are alkanolamines and polylight alcohols, but they are difficult to use due to cost problems.

Therefore, it is necessary to develop and research new varieties of grinding aids. The selection of new grinding aids should pay attention to the following problems. (1) The grinding aid must have a good grinding aid. At present, the indicators for verifying grinding efficiency are still based on the fineness and specific surface area of Boehmite. Conditional enterprises and research institutions use laser particle size analyzer to observe the particle size distribution of cement, which will be more accurate and true. For the cement particles, the particles of the building m should be reduced, and the proportion of the particles of 3 to 3 i0 m should be increased and the particle size tends to be more uniform, which is beneficial to the improvement of the cement strength. (2) The grinding aid has no adverse effect on the performance of the grinding material and the performance of the product. The setting time, strength and other properties of the grinding aid cement have no adverse effects, and there is no rusting effect on the steel bar, and the equipment components such as the mill are also No corrosion occurs. (3) The grinding aid is easy to operate, has no irritating odor, and has no harmful effects on the operator. (4) The sources of grinding aids are sufficient, easy to manufacture, and inexpensive.