Milling tea-leaf makes powdered tea as a byproduct of powder tea or Maccha. Recently, these powdered-teas are used for various application such as confectionery. Generally, powdered tea is produced by vibrating ball mill and is applicable for food quality of product in terms of colour, flavour and particle size. Conventional vibrating ball mill can produce the particle size at the same level with milling by stone. However, the process time is longer than general impact mill at more than 10 hours and very low capacity (around 100g per hour). In cases where tea is milled by vibrating ball mill, several milling lines are required to increase the production volume.
In order to achieve average particle size or 10-20 micron as same size as vibrating ball mill at high capacity, ACM pulverizer has been utilized. ACM pulverizer can reach the required particle size at high capacity, but it couldn’t product the product with high level of colour and flavour. ACM uses large amount of air for processing and it causes oxidization damage to chlorophyll.
Glacis, grinding machine with specially design cooling mechanism, can keep the product temperature at a low level during grinding. Comparing with ACM operation at the same power, necessary air volume for Glacis is 1/3 of that of ACM, which inhibits the oxidization of product.
As Glacis is not equipped with classifier, it need a classifier separately to reject coarse particles. Normally, vibrating sieve is applied to separate the particles larger than 200 micron. However, continuous operation is not possible because the sieve mesh can clog. So, Glacis is combined with air classifier Micron Separator. Because of this process steps, initial cost is higher than conventional impact mill. However, the production capacity is largely increased with high quality product.