Leaching in general and bollman extractor description

1. BOLLMAN EXTRACTOR
Presented by
Padmaratinam.C.U
3rd
year Bio

2. LEACHING
• Leaching is solid-liquid extraction
• In order to separate a desired solute component from a
solid phase, the solid is contacted with a liquid phase
• The two phases are in intimate contact and the solute
diffuses from solid to liquid phase resulting in separation
• This is called LEACHING

3. SOLUTES AND SOLVENTS
SOLUTES EXTRACTED BY LEACHING
 Vegetable seeds like cotton seeds, soybeans, linseeds,
peanuts, rice bran, castor beans
 Metal processing industries like copper, nickel, gold
and cobalt
SOLVENTS USED FOR LEACHING
 Petroleum napthals, Hexane, chlorinated hydrocarbons
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4. EQUIPMENTS FOR LEACHING
• Fixed bed leaching
- uses typical fixed bed diffuser or extracter
• Moving bed leaching
- uses Bollman extractor, Hildebrandt extractor
• Agitated solid leaching
- counter current leaching using thickeners
Other extractors used include ROTOCEL, FRENCH
STATIONARY BASKET EXTRACTOR, KENNEDY EXTRACTOR,
CONTINUOUS HORIZONTAL EXTRACTOR
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5. BOLLMAN EXTRACTOR
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6. VERTICAL EXTRACTOR
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7. Description
• Bollman extractor – one of basket type machine
• It consists of a vapor tight vertical chamber in which a
series of baskets are attached to a chain conveyor
• The baskets are provided with perforations at the
bottom
• Dry flakes or solids are added at the upper right side to a
perforated basket or bucket in a closed casing
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8. Continued…….
• As the baskets on the right descend they are leached by a
dilute solution of oil in solvent called half
miscella*
• The liquid percolates downward through the moving
baskets and is collected at the bottom as a strong solution
or full miscella*
• The baskets moving upward on the left are leached counter
currently by fresh solvent sprayed on the top basket
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9. Continued………
• The wet flakes are dumped as shown in the figure and
are removed continuously using a screw conveyor
• Usually the conveyor speed is one revolution per hour
and solvent to fresh meal(seeds) ratio is 1
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10. Recovery of solvent
• The recovery of solvent from both the miscella and the
leached seeds or beans is an essential part of the
vegetable oil leaching process
• In a typical arrangement, the filtered miscella is passed
to an evaporator for removal of solvent followed by final
stripping in a tray column to produce solvent-free oil
• The wet seeds are streamed to remove residual solvent
and air-cooled
• Ventilated gases from condenser can be to an absorber
to recover any solvent
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11. Continuous Horizontal Extractor
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12. Kennedy Extractor
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13. Hildebrandt Extractor