Factors Affecting the Hammer Milling Process of Crude Seawater Salt

The importance of particle size of common salt, i.e. sodium chloride, has become a concern in many applications; and this is not excluding the salt sourced from solar evaporated seawater. Therefore, milling process to reduce the particle size of the salt is an important part. Hammer milling has an advantage that its open system can lead to higher capacity in one batch. The effects of varying parameters like mill speed and output screen size of hammer milling had been studied in earlier researches. However, the effect of choosing certain heating treatment temperature prior the hammer milling as well as its interaction with either mill speed effect or output screen size effect has not been investigated yet despite the importance of heating treatment of seawater salt. Therefore, this research was conducted to see the effects of heating temperature, mill speed, and output screen size as well as their significance and their interaction in crude seawater salt hammer milling by studying the particle size distribution of the milled samples using sieve analysis. The results showed that heating temperature was the most important factor, especially when rising the temperature from 110 °C to 125 °C, followed by output screen size and mill speed, respectively, in which the effect of changing output screen size as much as 4 times smaller was about 10% higher than the effect of increasing hammer mill speed as much as 2000 rpm. Optimizing the three aforementioned parameters can even produce better milling results than adding further milling (two-times milling).