CA1060902A - Process of recovering oil from vegetable raw materials containing more than 25% oil - Google Patents
Process of recovering oil from vegetable raw materials containing more than 25% oilInfo
- Publication number
- CA1060902A CA1060902A CA235,739A CA235739A CA1060902A CA 1060902 A CA1060902 A CA 1060902A CA 235739 A CA235739 A CA 235739A CA 1060902 A CA1060902 A CA 1060902A
- Authority
- CA
- Canada
- Prior art keywords
- oil
- process according
- extracted
- liquid
- cake
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000002994 raw material Substances 0.000 title claims abstract description 29
- 230000008569 process Effects 0.000 title claims abstract description 28
- 235000013311 vegetables Nutrition 0.000 title claims abstract description 7
- 239000007788 liquid Substances 0.000 claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000002904 solvent Substances 0.000 claims abstract description 17
- 239000000463 material Substances 0.000 claims description 44
- 244000105624 Arachis hypogaea Species 0.000 claims description 9
- 235000020232 peanut Nutrition 0.000 claims description 8
- 235000014633 carbohydrates Nutrition 0.000 claims description 5
- 150000001720 carbohydrates Chemical class 0.000 claims description 5
- 235000020238 sunflower seed Nutrition 0.000 claims description 5
- 240000002791 Brassica napus Species 0.000 claims description 4
- 235000004977 Brassica sinapistrum Nutrition 0.000 claims description 4
- 244000060011 Cocos nucifera Species 0.000 claims description 4
- 235000013162 Cocos nucifera Nutrition 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000006286 aqueous extract Substances 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- 150000001298 alcohols Chemical class 0.000 claims 1
- 239000007864 aqueous solution Substances 0.000 abstract description 2
- 239000003921 oil Substances 0.000 description 67
- 235000019198 oils Nutrition 0.000 description 67
- 238000000605 extraction Methods 0.000 description 18
- 239000005418 vegetable material Substances 0.000 description 18
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 12
- 239000007789 gas Substances 0.000 description 9
- 238000005325 percolation Methods 0.000 description 9
- 241000196324 Embryophyta Species 0.000 description 8
- 238000001035 drying Methods 0.000 description 7
- 238000000227 grinding Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 235000006008 Brassica napus var napus Nutrition 0.000 description 5
- 240000000385 Brassica napus var. napus Species 0.000 description 5
- 229920002472 Starch Polymers 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 230000035699 permeability Effects 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 102000004169 proteins and genes Human genes 0.000 description 4
- 108090000623 proteins and genes Proteins 0.000 description 4
- 235000019698 starch Nutrition 0.000 description 4
- 239000008107 starch Substances 0.000 description 4
- 235000010777 Arachis hypogaea Nutrition 0.000 description 3
- 244000068988 Glycine max Species 0.000 description 3
- 235000010469 Glycine max Nutrition 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- 235000017060 Arachis glabrata Nutrition 0.000 description 2
- 235000018262 Arachis monticola Nutrition 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 240000006240 Linum usitatissimum Species 0.000 description 2
- 235000004431 Linum usitatissimum Nutrition 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 244000000231 Sesamum indicum Species 0.000 description 2
- 235000003434 Sesamum indicum Nutrition 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 235000004426 flaxseed Nutrition 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000000638 solvent extraction Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 235000003276 Apios tuberosa Nutrition 0.000 description 1
- 235000010744 Arachis villosulicarpa Nutrition 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 244000299461 Theobroma cacao Species 0.000 description 1
- 235000009470 Theobroma cacao Nutrition 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 235000013312 flour Nutrition 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 210000003097 mucus Anatomy 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 235000016709 nutrition Nutrition 0.000 description 1
- 230000035764 nutrition Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- -1 starch Chemical class 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000002311 subsequent effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 235000015112 vegetable and seed oil Nutrition 0.000 description 1
- 239000008158 vegetable oil Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11B—PRODUCING, e.g. BY PRESSING RAW MATERIALS OR BY EXTRACTION FROM WASTE MATERIALS, REFINING OR PRESERVING FATS, FATTY SUBSTANCES, e.g. LANOLIN, FATTY OILS OR WAXES; ESSENTIAL OILS; PERFUMES
- C11B1/00—Production of fats or fatty oils from raw materials
- C11B1/02—Pretreatment
- C11B1/04—Pretreatment of vegetable raw material
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Fats And Perfumes (AREA)
- Extraction Or Liquid Replacement (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A process of recovering oil from vegetable raw mate-rials containing more than 25% oil, in which the raw materials are precleaned and, if desired, precrushed and are ground once or more times in roll mills and are moistened and dried before the oil is extracted with a solvent. The process is characterized in that the ground raw material is moistened and mixed with 1-10%
of a liquid, particularly water or an aqueous solution, and is then dried to an optimum moisture content of 4-15%, which depends on the nature of the raw material, before the latter is extracted with a solvent.
A process of recovering oil from vegetable raw mate-rials containing more than 25% oil, in which the raw materials are precleaned and, if desired, precrushed and are ground once or more times in roll mills and are moistened and dried before the oil is extracted with a solvent. The process is characterized in that the ground raw material is moistened and mixed with 1-10%
of a liquid, particularly water or an aqueous solution, and is then dried to an optimum moisture content of 4-15%, which depends on the nature of the raw material, before the latter is extracted with a solvent.
Description
This invention relates to a process of recovering oil from vegetable raw materials containing more than 25% oil, in which the raw materials are precleaned and, if desired, pre-crushed and are ground once or more times in roll mills and are moistened and dried before the oil is extracted with a solvent.
In the recovery of oil from oil-containing plants, the oil should be separated as completely as possible from the remaining vegetable material (extracted cake). When the oil has been purified and processed further i. is mainly used for human nutrition. The extracted cake is a high-grade animal feed rich in proteins.
The recovery of the oil in a high yield and the pro-duction of an extracted cake containing less than 2% residual oil is enabled in that the vegetable material is extracted with a solvent, mainly with a gasoline fraction, such as hexane or heptane. Before the extraction the oil-containing material must be suitably pretreated. It must be precleaned to remove undesired accompanying matter and is then disintegrated to expose the oil in the cells.
In some cases, e.g., in the processing of soybeans containing 17-19% oil, it is sufficient to disintegrate the vegetable material by grinding on roll mills and the material can then be immediately subjected to extraction.
In other cases, particularly in the processing of all vegetable materials having a high oil content, above 25~, such as peanuts (40-50~), copra (60-70%), rape and rapeseed (35-50~), linseed (35-40%), sesame (45-55%), and sunflower seed (30-35%), a direct extraction of the disintegrated material cannot be carried out with satisfactory results or involves an unecono-mically high structural expenditure. The reason for the diffi-culties resides in that the disintegration of the material having a high oil content results in the formation of mechanically un-stable particles, which tend to disintegrate further into very - 1- ~
lOf~O90Z
fine particles, which reduce the permeability of the material to the extracting solvent. This results in a very long ex-traction time and gives rise to a need for very large ex~raction plants. If the grinding is controlled to avoid a formation of very fine particles, the cells of the plants are not sufficiently opened and the extracted cake will have excessively high residual oil contents.
For the reasons stated above, such vegetable materials having a high oil content are usually pressed in common practice today to remove a major portion of the oil before the extraction.
Pressing may be carried out in a batch process by means of presses operated in most cases under hydraulic pressure, or in a continuous process, e.g., by screw extruders. The press cake produced by the pressing operation contains at least 4% oil and in products which are subsequently extracted may contain 14-20%
oil. The press cake is disintegrated and then subjected to a -~
normal solvent extraction by which the oil content is reduced to 1-2%. The equipment used in the pressing process is su~jected ~ .
to high wear and involves a high expenditure for maintenance and - ~ -service. It has been attempted to reduce the wear by heating the vegetable material before it is pressed, so that the viscosity of the oil is reduced and the oil can flow out more easily. The pressing results in an additional temperature rise of the mate-rial, which is subsequently extracted, and temperatures of 160-180C may be reached. At such high temperatures, the oil is deteriorated and undesired accompanying substances, such as mucus, are dissolved too. As a result, a hot-pressed oil is poorer in color and taste and high losses are incurred during the sub-sequent refining of the oil.
For this reason there have been numerous attempts to develop processes which enable or facilitate a direct extraction of vegetable materials having a high oil content. For instance, it has been proposed in the Journal of ~merican Oil Chemists' Soc., 49 (1972), page 364 ~, to extract seeds having a high oil content in a two-stage process. After a first extraetion stage, in which percolation is carried out as in the conventional processes, the solvent is removed from the extracted cake and the latter is reground to the desired particle size and is then extracted with solvent in an extraction tower in an immersion proeess. Whereas this process results in an extracted cake or flour which has a sufficiently low residual oil eontent, the proeess involves a high expenditure as regards equipment and supplies.
Another proeess is used to proeess powder material, such as rice, bran, cocoa, etc., which is treated to increase the particle size before being extracted (German Patent Application M 21418 IV a/23a,publishedAugust2, 1956; inventor: ~riedrich ~ugustOetken). It isexplieitlystated inthepatentapplicationthat that process cannot be adopted, as a rule, for the treatment of the above-described vegetable materials having a high oil content.
More recently, a grinding proeess for oil-eontaining material has been diselosed (prospeetus published by Bauermeister, Hamburg). For that process, the material must be eooled to low temperatures (-196C) with liquid nitrogen. Sueh operation is expensive.
Whereas the grinding of vegetable material having a high oil eontent in roll mills does not result in a powder it does not result in distinet, stable flakes, as would be required for an effieient extraetion. Sueh distinet, stable flakes ean be obtained by grinding a material having a low oil eontent, sueh as soybeans.
Partieularly great diffieulties are involved in the extraetion of a material whieh has a high oil content and whieh has been repeatedly ground in roll mills. On the other hand, repeated grinding operations are required when it is desired to 1~6090Z
extract a previously extracted cake to a low residual oil content.
It is an object of the invention in the extraction of vegetable raw materials which contain more than 2~ oil and for this purpose to pretreat the ground raw material in such a manner that the raw materials can be processed in a single, continuous extraction stage within a short extraction time so as to leave a satisfactorily low residual oil content.
This object is accomplished in that the ground raw material is moistened and mixed with 1-lO~ of a liquid, and is then dried to an optimum moisture content of 4-15%, depending upon the nature of the raw material, before the latter is extracted with a solvent. ~ -;
According to a further preferred feature of the invention, previously extracted and deoiled cake in an amount of ~.
In the recovery of oil from oil-containing plants, the oil should be separated as completely as possible from the remaining vegetable material (extracted cake). When the oil has been purified and processed further i. is mainly used for human nutrition. The extracted cake is a high-grade animal feed rich in proteins.
The recovery of the oil in a high yield and the pro-duction of an extracted cake containing less than 2% residual oil is enabled in that the vegetable material is extracted with a solvent, mainly with a gasoline fraction, such as hexane or heptane. Before the extraction the oil-containing material must be suitably pretreated. It must be precleaned to remove undesired accompanying matter and is then disintegrated to expose the oil in the cells.
In some cases, e.g., in the processing of soybeans containing 17-19% oil, it is sufficient to disintegrate the vegetable material by grinding on roll mills and the material can then be immediately subjected to extraction.
In other cases, particularly in the processing of all vegetable materials having a high oil content, above 25~, such as peanuts (40-50~), copra (60-70%), rape and rapeseed (35-50~), linseed (35-40%), sesame (45-55%), and sunflower seed (30-35%), a direct extraction of the disintegrated material cannot be carried out with satisfactory results or involves an unecono-mically high structural expenditure. The reason for the diffi-culties resides in that the disintegration of the material having a high oil content results in the formation of mechanically un-stable particles, which tend to disintegrate further into very - 1- ~
lOf~O90Z
fine particles, which reduce the permeability of the material to the extracting solvent. This results in a very long ex-traction time and gives rise to a need for very large ex~raction plants. If the grinding is controlled to avoid a formation of very fine particles, the cells of the plants are not sufficiently opened and the extracted cake will have excessively high residual oil contents.
For the reasons stated above, such vegetable materials having a high oil content are usually pressed in common practice today to remove a major portion of the oil before the extraction.
Pressing may be carried out in a batch process by means of presses operated in most cases under hydraulic pressure, or in a continuous process, e.g., by screw extruders. The press cake produced by the pressing operation contains at least 4% oil and in products which are subsequently extracted may contain 14-20%
oil. The press cake is disintegrated and then subjected to a -~
normal solvent extraction by which the oil content is reduced to 1-2%. The equipment used in the pressing process is su~jected ~ .
to high wear and involves a high expenditure for maintenance and - ~ -service. It has been attempted to reduce the wear by heating the vegetable material before it is pressed, so that the viscosity of the oil is reduced and the oil can flow out more easily. The pressing results in an additional temperature rise of the mate-rial, which is subsequently extracted, and temperatures of 160-180C may be reached. At such high temperatures, the oil is deteriorated and undesired accompanying substances, such as mucus, are dissolved too. As a result, a hot-pressed oil is poorer in color and taste and high losses are incurred during the sub-sequent refining of the oil.
For this reason there have been numerous attempts to develop processes which enable or facilitate a direct extraction of vegetable materials having a high oil content. For instance, it has been proposed in the Journal of ~merican Oil Chemists' Soc., 49 (1972), page 364 ~, to extract seeds having a high oil content in a two-stage process. After a first extraetion stage, in which percolation is carried out as in the conventional processes, the solvent is removed from the extracted cake and the latter is reground to the desired particle size and is then extracted with solvent in an extraction tower in an immersion proeess. Whereas this process results in an extracted cake or flour which has a sufficiently low residual oil eontent, the proeess involves a high expenditure as regards equipment and supplies.
Another proeess is used to proeess powder material, such as rice, bran, cocoa, etc., which is treated to increase the particle size before being extracted (German Patent Application M 21418 IV a/23a,publishedAugust2, 1956; inventor: ~riedrich ~ugustOetken). It isexplieitlystated inthepatentapplicationthat that process cannot be adopted, as a rule, for the treatment of the above-described vegetable materials having a high oil content.
More recently, a grinding proeess for oil-eontaining material has been diselosed (prospeetus published by Bauermeister, Hamburg). For that process, the material must be eooled to low temperatures (-196C) with liquid nitrogen. Sueh operation is expensive.
Whereas the grinding of vegetable material having a high oil eontent in roll mills does not result in a powder it does not result in distinet, stable flakes, as would be required for an effieient extraetion. Sueh distinet, stable flakes ean be obtained by grinding a material having a low oil eontent, sueh as soybeans.
Partieularly great diffieulties are involved in the extraetion of a material whieh has a high oil content and whieh has been repeatedly ground in roll mills. On the other hand, repeated grinding operations are required when it is desired to 1~6090Z
extract a previously extracted cake to a low residual oil content.
It is an object of the invention in the extraction of vegetable raw materials which contain more than 2~ oil and for this purpose to pretreat the ground raw material in such a manner that the raw materials can be processed in a single, continuous extraction stage within a short extraction time so as to leave a satisfactorily low residual oil content.
This object is accomplished in that the ground raw material is moistened and mixed with 1-lO~ of a liquid, and is then dried to an optimum moisture content of 4-15%, depending upon the nature of the raw material, before the latter is extracted with a solvent. ~ -;
According to a further preferred feature of the invention, previously extracted and deoiled cake in an amount of ~.
2-15~, preferably 3-8~, is added to the ground raw material before, during or after the moistening step. This results in a further improvement of the process. It has been found that the admixing of extracted cake which has only a low residual oil content of 1-2~ has a particularly desirable effect on the permeability of the bed to be extracted.
The addition of the extracted cake in the proportions stated above to oil-containing raw materials, such a~ peanuts containing 40% oil, will only slightly change the oil content.
It has also been found that a moistening of the material above the optimum moisture content, followed by a drying or cooling to a temperature near the boiling point of the solvent, has particularly desirable effects as regards the permeability and extraction.
In a preferred embodiment of the invention, part of the extracted cake to be added is suspended in the li~uid and the liquid containing 8-12~ suspended cake is used to moisten A
.. ~
the ground raw material, which may contain additional extracted cake, which has been recycled.
Starch and proteins will be dissolved from the ex-tracted cake by the liquid in which the cake is suspended. It has been found that starch and proteins are particularly desi-rable in the pretreatment as binders for the fine powder par-ticles of the ground raw material. This improves the perme-ability of the material to be extracted.
Such suspension need not be used if, according to a further preferred feature of the invention, an aqueous extract obtained from the extracted cake is added as a liquid. Such aqueous extract will also contain the starch and proteins which are suitable as binders for the fine powder particles. If a suspension of extracted cake or an extract from the extracted cake is not used, additional preferred features of the invention reside in that carbohydrates, such as starch, may be added in amounts of up to 6% by weight. The carbohydrates tend also to preferentially agglomerate the finest particles.
In accordance with a further preferred feature of the invention, the moistened and ground raw materials are dried in a stream of gas, preferably air, at a temperature of 50-150C.
This procedure affords the advantage that the mixture to be extracted is carefully dried in this temperature range and the raw material is not heated above 90C. The oil is not de-teriorated at this temperature.
According to a further preferred feature of the in-vention the dried raw material is cooled in a stream of gas, preferably air. Such cooling will be required only when the highest temperature of the gas being dried to the optimum moisture content of 4-15% is above the boiling point of the olvent.
According to a further preferred feature of the in-~v -~060902 vention, the ground material is disposed on inclined rotary disks or tumbling barrels during the mixing and moistening steps.
According to a further pre~erred feature of the in-vention, the several process steps, such as grinding, admixing the extracted cake, moistening, mixing, drying, cooling and extracting are performed continuously and with smooth transi-tions.
According to a further preferred feature of the in- -vention, the vegetable raw materials consist preferably of rape seed, sunflower seed, copra, peanuts, etc.
In the process according to the invention, vegetable material having a high oil content is subjected to a special treatment, by which the material is brought into a state in which it can easily be extracted with a solvent in an extraction plant. The process is particularly distinguished in that the material is treated most carefully so that high-grade vegetable oils and an extracted cake having a low residual oil content are obtained.
The process will now be described more fully and with reference to examples.
The vegetable material having a high oil content, in most cases an oil seed, such as peanuts, linseed, rape and rape seed, sesame or sunflower seed, is precleaned as usual by sieving and sifting to remove foreign matter and is then dis-integrated.
In the processing of coarse vegetable material, such as copra, peanuts, sunflower seeds, the disintegration includes a precrushing step. This preliminary disintegration is usually effected by toothed rolls. The material is subsequently dis-integrated by smooth rolls, so that the oil is exposed. The dis-integration and destruction of the individual cells of the plants is promoted in that the rolls rotate preferably at different . 1060902 speeds so that the material to be ground is not only squeezed but is also subjected to an additional shear stress.
The disintegrated material is then moistened and fed to a mixer. The moistening with a liquid, preferably with water or an aqueous solution or an aqueous suspension, is suitably effected in the mixer.
The mixer may consist of equipment which is known in the art, e.g., a mixing drum, screw mixer, or rotary disk. The usual equipment, such as spray nozzles, is also used to moisten the material with a liquid.
The oil can be extracted particularly easily and in a high yield from the vegetable material if the latter has an optimum water content. Depending on the nature of the material, this water content is in the range of 4-15%, in most cases 5-10%, e.g., in the case of rape between 5~ and 8%.
If the material to be extracted has a low water content after it has been transported or stored, the deficient water or excessive water is added when the material is moistened with a liquid. Thè quantity of liquid to be added in excess of ~-the optimum water content is, according to a preferred feature of the invention, up to 15%, preferably 1-10%. The moistening liquid consists preferably of water, although alcohol, methanol etc. may also be used. Solutions of carbohydrates etc., having a solids content up to 10%, are also suitable, also solutions or suspensions of extracted cake. By the operation of the mixer the liquid is uniformly mixed with the plant material to be extracted.
When the material has been moistened with a liquid and has been mixed through, the material is dried to remove the liquid which is in excess of the optimum liquid content. This is suitably accomplished by means of a gas stream which is not saturated with the vapor of the liquid to be removed. In most ' ~ ~
cases, air may be used as a drying gas. For this purpose the gas stream is passed through the material to be dried in known equipment, e.g., a vibratory dryer. To accelerate the drying, the gas stream may be heated although the temperature of the gas entering the dryer is preferably kept under 150C. When the vegetable material has been dried, it may be necessary to cool the material if its temperature is more than 10C above the boiling point of the solvent used for the extraction. ~ust as for drying, a gas stream is used for cooling. This treatment does not necessarily result in a measurable increase of the largest particle size of the disintegrated vegetable material.
It has surprisingly been found that the described preliminary treatment results in a preferential bonding of the fine particles of the vegetable material so that they do not result in clogging during the subsequent extraction and that they do not inhibit the percolation and flow of the solvent through the material.
The vegetable material which has been dried to the optimum moisture content has a sufficiently high mechanical stability and can no lon~er be mechanically changed by handling.
The plant material which has thus been treated is immediately subjected to solvent extraction, by which the oil is recovered under the same conditions as in the case of oil plants having a low oil content, such as soybeans.
The b~havior of vegetable material having a high oil content during extraction can be much improved in that part of the deoiled cake having a residual oil content of 0.5-2% is admixed to the starting material having a high oil content before, during or after the mo-stening of said material. It will be entirely sufficient to recycle up to 15%, preferably less than 10%, based on the feed of oil-containing material.
Example 1 Groundnut seed was precrushed by grooved rolls and was 106090;Z
then ground by smooth rolls. The material contained 50.3~ oil and 5.6~ moisture. Without additional treatment, part of the material was tested in a testing arrangement for an evaluation of its behavior during extraction. Another part of the dis-integrated material was sprayed with water on a rotary disk and was then dried with a stream of air - inlet temperature 100C, outlet temperature 62C - in a vibratory dryer and was then tested for its behavior during extraction.
The extraction arrangement for evaluating the behavior during extraction consisted of a container, in which a bed of the oil-containing material to be investigated was provided on a screen grate. The bed had in all cases a height of 300 mm.
The container was thermostat-controlled and kept at a constant temperature of 50C. The bottom of the container was provided with an outlet opening for the oil-laden solvent, which in this case consisted of hexane. A predetermined quantity of hexane at 50C was pured over the oil-containing material in accordance with an exact time schedule and the times were measured which were required for the percolation of the solvent through the bed (percolation time) and until 90% of the solvent had drained from the bed (draining time). When the material had been extracted five times with hexane, the extracted material was removed from the equipment and the residual oil content was determined. The following amounts were measured:
l. Untreated peanut material Percolation time 26 sec.
Draining time 600 sec.
Residual oil content 1.1%
2. Treated peanut material Water content after moistening 10.4%
Water content after drying 5.3%
Percolation time 9 sec.
_ g _ Draining time 120 sec.
Residual oil content 1,0%
Whereas the residual oil content was approximately the same, the draining time was reduced by a factor of 5.
Example 2 Summer rape which contained 38.5% oil and 5.7~ moisture was repeatedly ground by smooth rolls. As in Example 1, part of the material was directly tested for its behavior during ex-traction and a second part was moistened with water, dried, and then tested.
The following results were obtained:
1. Untreated summer rape Percolation time 590 sec.
Draining time - 4900 sec.
Residual oil content 3.9%
2. Treated summer rape Water content after moistening 11.3~
Water content after drying5.3%
Percolation time 32 sec.
Draining time 300 sec.
Residual oil content 1.1%
In this case the pretreatment resulted in a reduction of the residual oil content from 3.9% to 1.1% and in a decrease of the draining time by a factor of about 16.
Example 3 In this example the same material was used as in Example 2 and the effect of a recycling of extracted cake was investigated. The extracted cake was mixed with the ground summer rape before the same was moistened with water.
The test had the following results:
~060902 Quantity of recycled scrap 0% 2~ 5% 10%
Water content after moistening 11.3% 10.5% 11.3% 11.2%
Water content after drying 5.3% 5.6% 5.8% 5.6%
Percolation time 32 sec. 15 sec. 11 sec. 15 sec.
Draining time 300 sec. 150 sec. 90 sec. 120 sec.
Residual oil content 1.1% 0.9% 0.9% 0.9~
It is apparent from this example that the recycling of extracted cake in an amount of about 5~ had resulted in a reduction of the draining time and of the residual oil content compared to the treatment of summer rape in accordance with Part 2 of Example 2.
The addition of the extracted cake in the proportions stated above to oil-containing raw materials, such a~ peanuts containing 40% oil, will only slightly change the oil content.
It has also been found that a moistening of the material above the optimum moisture content, followed by a drying or cooling to a temperature near the boiling point of the solvent, has particularly desirable effects as regards the permeability and extraction.
In a preferred embodiment of the invention, part of the extracted cake to be added is suspended in the li~uid and the liquid containing 8-12~ suspended cake is used to moisten A
.. ~
the ground raw material, which may contain additional extracted cake, which has been recycled.
Starch and proteins will be dissolved from the ex-tracted cake by the liquid in which the cake is suspended. It has been found that starch and proteins are particularly desi-rable in the pretreatment as binders for the fine powder par-ticles of the ground raw material. This improves the perme-ability of the material to be extracted.
Such suspension need not be used if, according to a further preferred feature of the invention, an aqueous extract obtained from the extracted cake is added as a liquid. Such aqueous extract will also contain the starch and proteins which are suitable as binders for the fine powder particles. If a suspension of extracted cake or an extract from the extracted cake is not used, additional preferred features of the invention reside in that carbohydrates, such as starch, may be added in amounts of up to 6% by weight. The carbohydrates tend also to preferentially agglomerate the finest particles.
In accordance with a further preferred feature of the invention, the moistened and ground raw materials are dried in a stream of gas, preferably air, at a temperature of 50-150C.
This procedure affords the advantage that the mixture to be extracted is carefully dried in this temperature range and the raw material is not heated above 90C. The oil is not de-teriorated at this temperature.
According to a further preferred feature of the in-vention the dried raw material is cooled in a stream of gas, preferably air. Such cooling will be required only when the highest temperature of the gas being dried to the optimum moisture content of 4-15% is above the boiling point of the olvent.
According to a further preferred feature of the in-~v -~060902 vention, the ground material is disposed on inclined rotary disks or tumbling barrels during the mixing and moistening steps.
According to a further pre~erred feature of the in-vention, the several process steps, such as grinding, admixing the extracted cake, moistening, mixing, drying, cooling and extracting are performed continuously and with smooth transi-tions.
According to a further preferred feature of the in- -vention, the vegetable raw materials consist preferably of rape seed, sunflower seed, copra, peanuts, etc.
In the process according to the invention, vegetable material having a high oil content is subjected to a special treatment, by which the material is brought into a state in which it can easily be extracted with a solvent in an extraction plant. The process is particularly distinguished in that the material is treated most carefully so that high-grade vegetable oils and an extracted cake having a low residual oil content are obtained.
The process will now be described more fully and with reference to examples.
The vegetable material having a high oil content, in most cases an oil seed, such as peanuts, linseed, rape and rape seed, sesame or sunflower seed, is precleaned as usual by sieving and sifting to remove foreign matter and is then dis-integrated.
In the processing of coarse vegetable material, such as copra, peanuts, sunflower seeds, the disintegration includes a precrushing step. This preliminary disintegration is usually effected by toothed rolls. The material is subsequently dis-integrated by smooth rolls, so that the oil is exposed. The dis-integration and destruction of the individual cells of the plants is promoted in that the rolls rotate preferably at different . 1060902 speeds so that the material to be ground is not only squeezed but is also subjected to an additional shear stress.
The disintegrated material is then moistened and fed to a mixer. The moistening with a liquid, preferably with water or an aqueous solution or an aqueous suspension, is suitably effected in the mixer.
The mixer may consist of equipment which is known in the art, e.g., a mixing drum, screw mixer, or rotary disk. The usual equipment, such as spray nozzles, is also used to moisten the material with a liquid.
The oil can be extracted particularly easily and in a high yield from the vegetable material if the latter has an optimum water content. Depending on the nature of the material, this water content is in the range of 4-15%, in most cases 5-10%, e.g., in the case of rape between 5~ and 8%.
If the material to be extracted has a low water content after it has been transported or stored, the deficient water or excessive water is added when the material is moistened with a liquid. Thè quantity of liquid to be added in excess of ~-the optimum water content is, according to a preferred feature of the invention, up to 15%, preferably 1-10%. The moistening liquid consists preferably of water, although alcohol, methanol etc. may also be used. Solutions of carbohydrates etc., having a solids content up to 10%, are also suitable, also solutions or suspensions of extracted cake. By the operation of the mixer the liquid is uniformly mixed with the plant material to be extracted.
When the material has been moistened with a liquid and has been mixed through, the material is dried to remove the liquid which is in excess of the optimum liquid content. This is suitably accomplished by means of a gas stream which is not saturated with the vapor of the liquid to be removed. In most ' ~ ~
cases, air may be used as a drying gas. For this purpose the gas stream is passed through the material to be dried in known equipment, e.g., a vibratory dryer. To accelerate the drying, the gas stream may be heated although the temperature of the gas entering the dryer is preferably kept under 150C. When the vegetable material has been dried, it may be necessary to cool the material if its temperature is more than 10C above the boiling point of the solvent used for the extraction. ~ust as for drying, a gas stream is used for cooling. This treatment does not necessarily result in a measurable increase of the largest particle size of the disintegrated vegetable material.
It has surprisingly been found that the described preliminary treatment results in a preferential bonding of the fine particles of the vegetable material so that they do not result in clogging during the subsequent extraction and that they do not inhibit the percolation and flow of the solvent through the material.
The vegetable material which has been dried to the optimum moisture content has a sufficiently high mechanical stability and can no lon~er be mechanically changed by handling.
The plant material which has thus been treated is immediately subjected to solvent extraction, by which the oil is recovered under the same conditions as in the case of oil plants having a low oil content, such as soybeans.
The b~havior of vegetable material having a high oil content during extraction can be much improved in that part of the deoiled cake having a residual oil content of 0.5-2% is admixed to the starting material having a high oil content before, during or after the mo-stening of said material. It will be entirely sufficient to recycle up to 15%, preferably less than 10%, based on the feed of oil-containing material.
Example 1 Groundnut seed was precrushed by grooved rolls and was 106090;Z
then ground by smooth rolls. The material contained 50.3~ oil and 5.6~ moisture. Without additional treatment, part of the material was tested in a testing arrangement for an evaluation of its behavior during extraction. Another part of the dis-integrated material was sprayed with water on a rotary disk and was then dried with a stream of air - inlet temperature 100C, outlet temperature 62C - in a vibratory dryer and was then tested for its behavior during extraction.
The extraction arrangement for evaluating the behavior during extraction consisted of a container, in which a bed of the oil-containing material to be investigated was provided on a screen grate. The bed had in all cases a height of 300 mm.
The container was thermostat-controlled and kept at a constant temperature of 50C. The bottom of the container was provided with an outlet opening for the oil-laden solvent, which in this case consisted of hexane. A predetermined quantity of hexane at 50C was pured over the oil-containing material in accordance with an exact time schedule and the times were measured which were required for the percolation of the solvent through the bed (percolation time) and until 90% of the solvent had drained from the bed (draining time). When the material had been extracted five times with hexane, the extracted material was removed from the equipment and the residual oil content was determined. The following amounts were measured:
l. Untreated peanut material Percolation time 26 sec.
Draining time 600 sec.
Residual oil content 1.1%
2. Treated peanut material Water content after moistening 10.4%
Water content after drying 5.3%
Percolation time 9 sec.
_ g _ Draining time 120 sec.
Residual oil content 1,0%
Whereas the residual oil content was approximately the same, the draining time was reduced by a factor of 5.
Example 2 Summer rape which contained 38.5% oil and 5.7~ moisture was repeatedly ground by smooth rolls. As in Example 1, part of the material was directly tested for its behavior during ex-traction and a second part was moistened with water, dried, and then tested.
The following results were obtained:
1. Untreated summer rape Percolation time 590 sec.
Draining time - 4900 sec.
Residual oil content 3.9%
2. Treated summer rape Water content after moistening 11.3~
Water content after drying5.3%
Percolation time 32 sec.
Draining time 300 sec.
Residual oil content 1.1%
In this case the pretreatment resulted in a reduction of the residual oil content from 3.9% to 1.1% and in a decrease of the draining time by a factor of about 16.
Example 3 In this example the same material was used as in Example 2 and the effect of a recycling of extracted cake was investigated. The extracted cake was mixed with the ground summer rape before the same was moistened with water.
The test had the following results:
~060902 Quantity of recycled scrap 0% 2~ 5% 10%
Water content after moistening 11.3% 10.5% 11.3% 11.2%
Water content after drying 5.3% 5.6% 5.8% 5.6%
Percolation time 32 sec. 15 sec. 11 sec. 15 sec.
Draining time 300 sec. 150 sec. 90 sec. 120 sec.
Residual oil content 1.1% 0.9% 0.9% 0.9~
It is apparent from this example that the recycling of extracted cake in an amount of about 5~ had resulted in a reduction of the draining time and of the residual oil content compared to the treatment of summer rape in accordance with Part 2 of Example 2.
Claims (13)
1. A process of recovering oil from vegetable raw materials containing more than 25% oil, in which the raw materials are precleaned, precrushed and are ground once or more times in roll mills and are moistened and dried before the oil is extracted with a solvent, characterized in that the ground raw material is moistened and mixed with 1-10% of a liquid and is then dried to an optimum moisture content of 4-15%, depending upon the nature of the raw material, before the latter is extracted with a solvent.
2. A process according to claim 1, characterized in that the moistening liquid is selected from the group consisting of water, alcohols and solutions of carbohydrates having a solids content of up to 10%.
3. A process according to claim 2, characterized in that water is added as moistening liquid.
4. A process according to claim 1, characterized in that previously extracted and deoiled cake in an amount of 2-15% is added to the ground raw material before, during or after the moistening step.
5. A process according to claim 4, characterized in that the previously extracted and deoiled cake is added in an amount of 3 to 8%.
6. A process according to claim 4, characterized in that part of the extracted cake to be added is suspended in the liquid and the liquid containing 8-12% suspended cake is used to moisten the ground raw material.
7. A process according to claim 6, characterized in that an aqueous extract obtained from the extracted cake is added as moistening liquid.
8. A process according to claims 4, 6 or 7, characterized in that carbohydrates in an amount below 10% by weight are added to the liquid.
9. A process according to claim 1, characterized in that the moistened and ground raw materials are dried in a stream of gas, at a temperature of 50-150°C.
10. A process according to claim 1, characterized in that the dried raw material is cooled in a gas stream.
11. A process according to claims 9 or 10, characterized in that the gas employed is air.
12. A process according to claim 1, characterized in that the ground material is disposed on inclined rotary disks or tumbling barrels during the mixing and moistening steps.
13. A process according to claim 1, characterized in that the vegetable raw material is selected from the group consisting of rape seed, sunflower seed, copra, peanuts and mixtures thereof.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2453911A DE2453911C3 (en) | 1974-11-14 | 1974-11-14 | Process for extracting oil from vegetable raw materials with an oil content of more than 25% |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1060902A true CA1060902A (en) | 1979-08-21 |
Family
ID=5930761
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA235,739A Expired CA1060902A (en) | 1974-11-14 | 1975-09-16 | Process of recovering oil from vegetable raw materials containing more than 25% oil |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5173006A (en) |
| BE (1) | BE835575A (en) |
| CA (1) | CA1060902A (en) |
| CS (1) | CS199603B2 (en) |
| DE (1) | DE2453911C3 (en) |
| FR (1) | FR2291265A1 (en) |
| IT (1) | IT1048712B (en) |
| NL (1) | NL7507983A (en) |
| PL (1) | PL97962B1 (en) |
| SE (1) | SE430514B (en) |
| SU (1) | SU615869A3 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2722245A1 (en) * | 1977-05-17 | 1978-11-23 | Akzo Gmbh | PRODUCTION OF EDIBLE OIL FROM CRUDE SOYA OIL |
| CZ202267A3 (en) | 2022-02-11 | 2023-04-19 | Farmet A.S. | Oilseed processing method and oilseed processing equipment |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE970855C (en) * | 1954-01-08 | 1958-11-06 | Metallgesellschaft Ag | Process for the extraction of oils, fats or other extractable substances from rice bran, grain bran, cocoa, bleaching earth and similar powdery raw materials |
| NL7302358A (en) * | 1973-02-20 | 1974-08-22 |
-
1974
- 1974-11-14 DE DE2453911A patent/DE2453911C3/en not_active Expired
-
1975
- 1975-07-04 NL NL7507983A patent/NL7507983A/en not_active Application Discontinuation
- 1975-08-21 FR FR7525890A patent/FR2291265A1/en active Granted
- 1975-09-16 CA CA235,739A patent/CA1060902A/en not_active Expired
- 1975-11-03 SU SU752188492A patent/SU615869A3/en active
- 1975-11-10 JP JP50136144A patent/JPS5173006A/ja active Pending
- 1975-11-13 CS CS757683A patent/CS199603B2/en unknown
- 1975-11-13 SE SE7512788A patent/SE430514B/en unknown
- 1975-11-13 PL PL1975184689A patent/PL97962B1/en unknown
- 1975-11-13 BE BE6045249A patent/BE835575A/en not_active IP Right Cessation
- 1975-11-13 IT IT29255/75A patent/IT1048712B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| SE430514B (en) | 1983-11-21 |
| JPS5173006A (en) | 1976-06-24 |
| SE7512788L (en) | 1976-05-17 |
| PL97962B1 (en) | 1978-04-29 |
| NL7507983A (en) | 1976-05-18 |
| SU615869A3 (en) | 1978-07-15 |
| DE2453911B2 (en) | 1980-05-29 |
| FR2291265A1 (en) | 1976-06-11 |
| IT1048712B (en) | 1980-12-20 |
| BE835575A (en) | 1976-05-13 |
| FR2291265B1 (en) | 1979-01-05 |
| DE2453911A1 (en) | 1976-05-20 |
| CS199603B2 (en) | 1980-07-31 |
| DE2453911C3 (en) | 1985-01-10 |
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