Mechanical Separator & Washer

    To remember the function of this machine, we use the acronym CWSF, to Convey Washed Sinkers & Floaters.

    This station contains one machine, which is distinguished by two distinct elements, however, serves four primary purposes in the processing of coffee; to 1). Convey cherries from the hopper to bucket elevators, which will take them to the de-pulpers, 2). Filter out external impurities from the cherries, 3). Wash the cherries or any remaining external impurities, and 4). Separate the cherries into two categories of quality, sinkers and floaters, based on their internal density.

  1. 1. All cherries are loaded into a hopper.

    1. a. Cherries are fed to the machine from the hopper, through a manually controlled and opened chute.

    2. b.As cherries exit the hopper they are received by the first element of the machine, the vibrating screens.

  1. 2.The vibrating screen serves as both a conveyor and screen, taking the cherries from the hopper to the separator, while filtering out impurities.

    1. a. Cherries are vibrated forward, as three brackets on both sides of the conveyor, rock back and forth quickly, creating gradual forward motion.

    2. b. As forward motion happens, they pass over a two different series of openings, which allow small impurities, such as pebbles, sand, stems to pass through, while retaining larger impurities, such as leaves, sticks.

      1. i.The first perforated screen contains small openings, which allow the cherries to continue forward, while causing small impurities, such as pebbles, sands, and stems to fall through.

      2. ii.The second perforated screen, contains larger openings, which allow the cherries to pass through, however retain any larger impurities, such as leaves and sticks, which can must be removed by hand.

      3. iii.Once reaching the end of the screened conveyor, the cherries enter the second element of the machine, called the mechanical syphon.

  1. 3.The mechanical syphon is a reservoir, holding roughly 400 gallons of water, and divided into a right and left chamber, acts as separator, syphon, and washer of the cherries.

      1. a.All cherries enter the left chamber of the mechanical syphon.

      2. b.Cherries within the mechanical syphon are immediately separated into two qualities, called sinkers and floaters.

      3. c.This is a natural function, caused by the presence of water within the mechanical syphon and gravity.

      4. d.Heavy and dense beans entering the water naturally sink.

      5. e.Light and hollow beans entering the water naturally float.

      6. f.These two qualities of beans take different trajectories. 

      7. g.The first category of cherries, sinkers; once reaching the bottom of the mechanical syphon, are pumped upward, through a flat-channel, from the left to the right chamber.

      8. h.Cherries categorized as sinkers, are then channelled out of the syphon, into the final stage of the machine.

      9. i.The second category of cherries, floaters, remain on the surface of the water, continuing through the left chamber, before channelled out of the syphon, into the final stage of the machine.

      10. j.Cherries departing the syphon, are emptied from each of their two chambers, onto two distinct, vibrating, perforated screens, distinguished for either sinkers or floaters. 

      11. k.As cherries are emptied onto the screens, they are washed of any dirt or impurities remaining as they left the syphon.

      12. l.Both vibrating screens channel the cherries into two bucket elevators, one which carries the floaters to de-pulpers, and another, which carries the sinkers to the unripe bean separator.