Preparation Of Sulphates For Cement Grinding Aids And Their Performance

In the cement industry, a large amount of energy is consumed in grinding the rawmaterials for cement production. In the process of grinding, the use of grinding aids is one ofimproving grinding efficiency. At the moment, in the domestic grinding aids market,triethanolamine is the main product. In addition, the price of triethanolamine is uncertainty. Itis not only expensive but also likely to be affected and fluctuant. Sulfates were synthesizedfrom sulfation of alkanol amines and amylum with aminosulfonic acid. It aims to reduceprices and enhance grinding effect.At last, complex of grinding aids（sulfate and polymaleicacid）can be used for seeking high-performance grinding aids.In the article, several additives were synthesized from alkanol amines andamylum.There are triethanolamine sulfate(GR1and GR2), diethanolamine sulfate(GR3),monoethanolamine sulfate(GR4), starch sulfate(GR5), and HPMA(GR6). In addition, there ismixture named GR7. Compared to triethanolamine, methods were used for grinding effects,which includes sieving residue、specific area、size distribution、the compression breakingresistence. It aims to filter our requirements. In addition, the hydration phenomenon wasinvestigated by SEM, X-ray. Finally, the action mechanism was discussed. The results wereshown below.(1)The optimal additive amount for TEA was0.03%and the optimal grinding time was35min. The synthesis of these compounds，GR2and GR4can significantly reduce the contentof coarse particles. The minimum sieving residue of45μm was up to5.07%and6.39%. ForGR1, it can improve the particle size distribution of cement effectively, especially, increasedthe grains with the size of3~32μm. On a macro level, it can increase compressive strength ofcement. The soundness, setting time and water demand for normal consistency of theresultant cement meet the requirements of JC/T667-2004《Cement grinding aids》.(2)The optimal proportion of several blends of grinding aids was0.015%GR2、0.01%GR4、0.02%GR6. In comparison to TEA,45μm sieving residue of cement is down3.9%. The3-day and28-day strength of the cement pastes improved by3.4MPa and7.4MPa.The formulated aids had good adaptability for beton.(3)In the hydration process of Portland cement，FTIR spectra confirmed that C-S-Htrended to change from to long chain to polymeric C-S-H. X-ray diffraction showed that thegrinding aids didn’t modify the cement hydration productions. C3S and C2S significantlyreduced and The hydration products increased. Cement paste was more dense by SEM. A lotof hydration products like spicula、rod、net structure filled in the internal to make cementpaste dense.The synthesized aids and the formulated aids have good performance and low price, mixed grinding aids works better than TEA, which is expected to be used in cement industry.