Newly harvested cassava raw materials are transported by truck from the ground to the factory. The truck is weighed on the weighbridge and sampled to determine the content of tapioca starch before being discharged onto a clean concrete floor, the so-called material staging platform.
The raw materials are shoveled by the forklift to the receiving hopper, and a vibrating feeding device is arranged under the hopper to transport the raw materials to the inspection conveyor.
By tilting the belt inspection conveyor, the worker can manually cut off the xylem of the roots of the cassava raw material to prevent the harder xylem from entering the lower honing section and reduce the load on the honing machine. The inspected raw material enters a dry de-dusting machine through a belt conveyor. The squirrel-cage dry de-dusting machine removes the coarse sand shovel and the skin (on-line cleaning). The sand and the skin residue are sieved into the sand collecting tank through a descaling machine, and are manually cleaned regularly.
The raw materials after the dry removal process enter a three-stage paddle cleaning machine, and the residual sand and broken skin are washed out. Process wastewater is added to the first-stage cleaning machine to soak the sand contained in the raw material. The raw materials are sent to the next level of relatively clean water tank through the first-stage water tank of different areas, and the clean washing water is added to the back washing machine, so that the cassava is cleaned by the countercurrent cleaning method. The cleaned material is delivered to a large dip conveyor. Regular discharge of sand and impurities in cleaning is required. On the large dip conveyor belt, it is possible to check again whether there are stems and remaining impurities such as branches in the raw material. The stems should be cut by hand. The inspected raw material is transported to the honing unit by a tilt belt conveyor.
Broken, honing unit
The raw materials from the washing unit enter the crusher and cut into pieces, and the raw materials are uniformly conveyed into the hopper of the honing machine through a specially designed cloth. The honing machine hones the potato pieces into a low-breaking rate potato syrup, that is, 50% of the cassava flour has not been separated and is combined with the fiber. It is necessary to add process water to dilute it during the honing process. The honed potato slurry is pumped into the sand remover through a slurry pump through a collection tank under the honing machine to remove the sand from the potato slurry. Since the cassava whole powder does not allow the cassava powder to be released as much as possible, but is combined with the fiber, the specially designed honing machine plays a vital role in the fineness of the whole powder and the freeness of the cassava powder.
Sand removal unit
In the sand removing unit, coarse particles such as sand and saw teeth are removed from the potato slurry. This unit includes ceramic swirl tube, sand collecting tank, automatic sand discharging valve and back flushing device. The backflushing avoids the loss of tapioca during the sand discharge. The potato slurry after the sand enters the dehydration unit.
Tapioca powder detoxification
Since the cassava skin contains toxic substances of hydrogen cyanide, the unit is subjected to a detoxification dehydration process using a plate and frame filter press.
When the potato slurry in the potato milk tank reaches a certain liquid level, the potato pulp is detoxified and dehydrated. The potato pulp is dehydrated by a plate and frame filter press. It is then transported to the tapioca drying process by conveyor belt.
Drying and packaging unit
The dehydrated cassava cake has a high water content of about 45-60% and enters the dryer through the feeder. The heat source of the airflow dryer is a steam heat exchanger. The wet cassava powder is heated by hot air and the water is evaporated. After drying, the tapioca powder is separated from the air in a cyclone. A shut-off seal is used at the bottom of the cyclone. The humid air exits the cyclone and is discharged to the atmosphere through the exhaust. The collected tapioca powder is transferred to a shaker unit to screen coarse particulate matter from the tapioca flour. The sieved tapioca powder is transferred to the cassava powder silo, temporarily stored and cooled.