Issue link: https://www.e-digitaleditions.com/i/1380119
18 / June 2021 powderbulk.com The mill was designed to pro- duce a particle size of 90 per- cent less than mesh 200 (d 90 = 75 microns) at a capacity of 4,000 to 5,000 lb/h and an alternative parti- cle size of 95 percent less than mesh 325 (d 95 = 44 microns) at a capacity of 1,400 to 1,800 lb/h. "Combustibility of the milled material must also be taken into account," said Johansson. "Our FCM mills are 10-bar (145-psi) pres- sure safe to contain a possible dust explosion and are ATEX certified. Typically, the product receiver will have a suppression system, but for some applications, the system can instead be inerted with nitrogen to mitigate the combustion risk of very fine ground organic materials." The mill receives the lactose powder directly from a dryer via a pneumatic conveying system and baghouse receiver. After mill- ing, the powder is transported to packaging equipment for final packaging in 25-kilogram bags or 900- kilogram totes. fine particles. To exit the grinding chamber, fine particles must pass through a classifier, which is a cage of blades spinning like a turbine wheel, that acts as a screen. The classifier wheel only lets particles that are small enough pass through and rejects larger particles, caus- ing them to remain in the grind- ing chamber for additional size reduction. The fine particles that exit the mill are collected in a bag- house receiver. Mill operators can easily adjust the output's particle size distribution without needing to shut down the mill by increasing or decreasing the classifier wheel's speed. Other system parameters also adjust easily, allowing for tight particle size control. "We specify equipment based on the customer's capacity and target particle size requests," said Tomas Johansson, director of Stur- tevant's FCM mills division. "We also take into consideration mate- rial characteristics such as hard- ness and abrasiveness." on another large lactose project for a different cheese company in Wisconsin. After reviewing the various options for fine grind- ing mills on the market, the com- pany decided that Sturtevant was the best fit for this project as well and purchased one FCM 650 air classifier mill, along with several auxiliary items. The FCM 650 is a midsized, high-speed impact mill with an internal air classifier and features a pressure- shock-resistant mill chamber and a 75-kilowatt (100- horsepower) main drive motor. "We were looking for a food- grade unit that could easily adapt to different mesh sizes," said Mark Dachel, general manager of Stain- less Technologies. "We decided to work with Sturtevant because we felt their machine met our needs and allowed for flexibility as mar- ket demands changed." In operation, material enters the mill's grinding chamber through a feed inlet and is then impacted by a series of spinning pins or blocks, which reduce the material into The mill receives the lactose powder directly from a dryer via a pneumatic conveying system and baghouse receiver. The mill features a Type 304 stainless steel rotor and liner and Type 440 stainless steel heat-treated mill blocks.