Sassor
purifying meal
The Sassores separators or scrubbers are using the principles of density and air resistance , to separate particles husk ( chaff) of endosperm ( flour).
After the cylinders milled product is classified under planschisters , large bran particles are separated and sent back to the group milling . The separation plansifter is the only difference in particle size , therefore classified in the same product will have bran particles of the same particle size of the endosperm.
The purifiers can be used to separate the bran particles of endosperm based on the difference in density and air resistance . This classification is achieved through a sieve made with direct suction on the product , the lighter product rich in shell passes over the screens suspended in the air , while the heavier , rich endosperm is sifted .
The purpose of this separation is to grind products with similar characteristics always the same cylinder and obtain flour of superior quality . The separation of the particles of bran and endosperm by a scrubber depends on the difference in aerodynamic property of the particles . These properties depend on the size , density and air resistance of these particles.
The material supplied to the classifier is composed of three categories :
Endosperm particles ;
Particles of endosperm and bran ;
Particles of pure bran ;
In general, the particles contain large amounts of bran , tends to be lighter than one with less bran. When a mixture of these three types of particles is exposed to an air stream ( moving upward) , and the mixture is stratified in various separate layers ( from bottom to top ) :
Particles of pure endosperm in the background ;
Particles composed of bran and endosperm in the middle;
Particles of pure bran on top .
In reality, however the cleanser separation is not so simple , though it has been classified in planschister and to be seemingly homogeneous mixture with respect to particle size the mixture contains particles of different sizes.
The mixture separated in the scrubber is generally composed of 6 to 7 components:
Particles of pure , small and large endosperm;
Endosperm and bran particles , small and large ;
Particles of pure , small and large bran ;
Fine particles of flour .
Therefore, placing the mixture on a sieve and exposing it to a stream of air from bottom to top , the mixture separates into multiple layers, but there is no clear dividing line between them.
The following layers are produced from the bottom up :
• Small particles of pure endosperm in the background ;
• Large pure endosperm particles ;
• Small particles composed of endosperm and bran ;
• Large Composite particles of endosperm and bran ;
• large bran particles ;
• Small particles of bran ;
• Very fine particles of bran and flour , above all .
To achieve good separation purifier in this last layer should be eliminated . This is achieved by a good regulation of the system avoiding breakage of grain formation of very fine particles of bran and good in plansifter sieve to remove particles of flour. The more calibrated for the product to be classified, it is next particle size difference , the better the work Sassor . The sieves Sassor are distributed so that the power input screen is thinner aperture and near the exit aperture is higher.
The aperture size is chosen so that the thinner endosperm can be sieved through a sieve closest to the entrance, but the larger the particle the more it is run through the Sassor before finally passing through the screen or not . The thinner the endosperm , which is screened at the entrance , is separated by Sassor purer product , while coarse endosperm , which is sieved near the end of sieving , is usually adhered to particles of endosperm bran formed, and not is as pure as separate early . Particles of pure bran and bran with endosperm are separated on the sieve ( rejection ) , and collected in a special output at the end of Sassor .
Control Sassor
For a control function and successful purifiers , we should note the following items :
• Feed speed :
The product should be supplied to the purifier , so that a continuous layer is formed on the screen . If there are areas without layers of products, the air enters at a higher speed , resulting in a suspension of particles of endosperm. With this there will be an uneven distribution of air, causing a separation or stratification poor product .
• Moves sifter :
The oscillating sifter as well as the slope and the alignment should be checked properly. Excessive vertical movement too advances the product, the product sufficient movement will stop at the top of the sieve preventing air to pass through the sieve . The setting is only effective when sifter screens are appropriately strained ( stretched ) , the tension should be checked regularly and adjusted if necessary .
• Airflow :
Excessive air flow will load endosperm particles to the vacuum system . Lack of air will carry particles of bran to the meal . The air consumption of Sassores is approximately 50 m3 per min , so you must ensure free access to air purifiers . Low air pressure slows the purifier and poor separation .
• Limit the ability : The cleanser should work as close to capacity.
• Cover the sieve ( screen ) :
The screen number in scrubber to be used depends largely on the particle size of the product being supplied to the scrubber and the velocity of feeding.
The 1st screen must be larger than the smallest particles of endosperm opening being provided as the last screen opening should be equal to or slightly larger endosperm particles , so as to allow them to be separated.
The sieves and the Air
The mesh size has to increase from the first to the last sieve. The air velocity is also increasing .
A great feature of this operation is the passage of air through the sieves .
The distribution of the product on the screen has to be uniform so that it classifies .
A moderate speed favors the first sieve classification.
The air flow must be regulated so as not charging light particles .
Brushes
The cleaning system shall be provided so as to " disengage " the meal . A malfunction of the brushes completely nullifies the function of the machine , sending products rich in endosperm to the end of grinding .
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