Apparatus and method for the continuous extrusion and partial

Abstract

An extruder for treating high-oil-content material such as certain oilseeds, is used to prepare the material for later solvent extraction of oil from the material. The extruder has an elongate barrel and a rotating wormshaft therein which advances the material from an inlet hopper to a discharge die plate having at least one restricted orifice. As the material advances through a series of compaction worms, it is worked and compressed. Steam may be injected to raise the temperature and moisture content of the material. The pressure on the material is increased and is maintained sufficiently high so as to prevent any water content from vaporizing even if its vapor pressure significantly exceeds atmospheric pressure. The barrel wall includes a perforate or slotted section downstream from a solid wall section, and preferably immediately before or close to the discharge die plate. This allows any oil which is liberated from the oil-bearing material being worked to drain out of the extruder, thus making it feasible to process high-oil-content materials in the extruder without the prior use of a screw press. The material exiting the die plate into atmospheric pressure expands because of vaporization of the moisture content, yielding a porous material very suitable for solvent extraction. The feed worm design provides for greatly increased throughput of material from the feed hopper to the compaction worm.