Grinding Characteristics of Coriander Seed with Reference to Physical Properties and Energy Consumption

Abstract

Coriander (Coriandrum sativum) at three moisture content (5.7, 11.4 and 17.2 %, db) were ground using a micro pulverizer hammer mill with different grinder screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg/h) at 3000 rpm. Specific energy consumption were found decreased from 204.67 to 23.09 kJ/kg for increased levels of feed rate and grinder screen openings. The highest specific energy consumption was recorded for 17.2 % moisture content and 8 kg/h feed rate with 0.5 mm screen opening. Average particle size decreased from 0.99 to 0.47 mm with increase of moisture content and decrease in grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg/h feed rate. Bond's work index and Kick's constant were increased from 0.61 to 3.07 kWh/kg, 0.073 to 0.324 kWh/kg with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of coriander seed were found decreased from 4.92 to 2.29 and 0.002 to 1.600 with the increase of moisture content, feed rate and grinder screen opening. The loose and compact bulk densities varied from 210 to 475 kg/m³ and 231 to 550 kg/m³, respectively for various mass fractions of sieve analysis. Bond's work index and Kick's constants were affected significantly by feed rate and moisture content for all screen openings except 0.5 mm.