What is the usage of aluminum sulfate for every ton of paper produce for kraft paper and news print
Aluminium sulphate was the most extensively used chemical raw material in the papermaking industry. Its primary use was in the rosin sizing of paper where the rosin soap was reacted with aluminium sulphate to impart hydrophobis characteristics to the paper. The alum had a side benefit in fixing all types of anionic substances into the paper web. All types of paper, even those that were not sized, such as newsprint,were made using alum. This resulted in the paper being made under acidic conditions. The technology has changed markedly over the last 10 to 20 years with synthetic sizing agents being developed which do not require reaction with alum. In my country there is not 1kg of fine writing and printing paper made with rosin/ alum sizing, and no alum is used at all. Various synthetic highly charged cationic resins have been developed, such as polyacrylamide resins, polyethyleneimine resins, etc, whic are used as fixing and retention agents, so that alum has been virtually eliminated. To sum up the importance of aluminium sulphate as a papermaking chemical is now very limited.
