Coffee Mill - Page 2
Coffee cherries are received in semi-dry receivers (Pic 8, Pic 9 and Pic 10), from which, the re circulated water transports the coffee to a 1.87 cubic meter siphon, which remains full of water during the entire pulp extraction process (Pic 11, Pic 12 and Pic 13). The siphon separates the low-density coffee cherries from those with a higher density. In other words, heavy coffee cherries continue the process, while floaters are excluded from it. High density coffee cherries are conveyed by water pressure to a pebble separator, preventing the introduction of pebbles and any other foreign objects to the de pulping machines (Pic 14). Coffee cherries are then carried by recirculated water to the de pulping machines where the pulp is removed to expel the two coffee beans from within the fruit (Pic 15, Video 1, Video 2 and Video 3). These coffee beans are transported by the same re circulated water to fermentation tanks in which they remain untouched until optimum fermentation is reached, in order to naturally separate the beans from the mucilage covering the parchment of the coffee beans (Video 4 and Video 5).
Such fermentation must be closely monitored, and the time to achieve it depends on; the environmental temperature, relative humidity and the amount of pectin and bacteria in the water. If water has already been recirculated several times, it is rich in bacteria and pectin, which reduces the fermentation time. If the minimum temperatures are too low, fermentation takes more time. For such reason, a strict fermentation control is required to obtain a healthy, flawless cup quality. The gap between excellent and rotten is a matter of minutes. The same water, conveying coffee cherries to the de pulping machines, transports the coffee pulp; through a non-water leaking pipeline to a helicoid, which separates the pulp from the water and conveys the pulp to a blower that evenly spreads it under cover. Coffee pulp remains under cover for a controlled aerobic decomposition in order to serve as earthworm feed (Pic 16). Coffee pulp is recycled into an organic fertilizer. Water returns to the re circulation circuit. Any water that may have been absorbed by the pulp is drained with time, and goes directly to the clarification tanks to be treated as mentioned above.
Once optimal fermentation is accomplished, coffee beans are conveyed to a concrete channels measuring one meter high, forty centimeters wide, with an inclination of two point five percent (Pic 17, Pic 18, Pic 19 and Video 6). These channels main purpose is again, to separate high density beans from those of lower densities. This is the second separation stage; carried out under the same bean density principles used in the first stage. High-density coffee beans continue the process and are washed, while floating coffee beans are removed from the process and treated and processed separately as low-quality coffee beans. An independent water circuit is used to convey coffee beans from the fermentation tanks to the separation concrete channels. Subsequently to separation, coffee beans are transported employing the same water to a washing machine in which coffee beans are washed and separated from the wastewater. The water employed for this process belongs to a closed circuit of three cubic meters. This water carries coffee from the fermentation tanks to the separation channels, helps to separate the floating coffee beans, and washes the coffee in the washing machine or pump. Coffee is pump-washed, and then conveyed through a pipeline circuit where coffee ends its washing stage. Once coffee goes through the washing pump, it is separated from the wastewater through an “adelio”, propelling the coffee beans to a sorting pipe which is the third classification stage (Pic 20 and Video 7). The water employed to transport coffee beans to the separation channels, separating coffee beans and transport the beans to the washing pump is replaced on the daily basis (Pic 21). Once this water has been employed, the same becomes part of the closed water circuit for pulp extraction, due to the fact that during the pulp extraction process, water was lost through absorption by the pulp and water levels need to be maintained.
While in the sorting pipe, coffee beans are mixed with clean water (Video 8 and Video 9). In the sorting pipe, the third sorting and separation stage begins. Once again, high-density coffee beans are separated from those with low density. Subsequently, coffee is conveyed by clean water to concrete channels of laminate flow. These channels are thirty centimeters high, forty centimeters wide with less than one percent inclination. In these concrete channels coffee beans experience a fourth and last separation process in the wet mill process (Pic 22, Pic 23, Pic 24 and Video 10). In this stage, coffee beans flow in water inside the eighteen meter channel. The slight inclination and subtle water pressure allows low-density coffee beans to roll over high-density coffee beans and be deposited in the last two meters of the eighteen meter channel. All the coffee beans deposited in the last two meters of the channel are removed from the process and become part of low-quality coffee beans which are processed separately. Water employed in the sorting pipe and the concrete channels of laminate flow, is pectin and bacteria free and meets the DQO requirements to return to the water-bearing strata with no risk of contamination. However, we have the infrastructure to recirculate and treat such water as well.