Refining of agricultural oils and other agricultural extracts results in troublesome waste products and do not produce optimum yeilds.
For example, bleaching earths are used after crude oils are refined with alkali and washed with water. They are used to absorb trace quantities of undesirable constituents from refined oils. Bleaching earths (clays) can be natural earths (Diatomaceous Earths) and can contain silica/silicates, or even carbon or activated carbon. They are used in approximately 1% concentrations to the crude, once-refined oil to improve refining and water washing. Attempts have been made to recover some oil. See Orth, Jr., U.S. Pat. No. 4,285,832, issued Aug. 25, 1981 which is hereby incorporated by reference.
Spent bleaching earth is a disposal problem in that it is saturated with oil and spontaneously combusts. Waste treatment amounts to paying a disposal company to take it away.
Furthermore, there are many valuable chemicals or potentially valuable chemicals which exist in the soapstocks from the caustic refining of vegetable oils, marine oils and animal fats. It would be desirable to extract them intact and efficiently.
One of the by-products of the process invented by the present applicant and described in the above references is a black paste, which would ordinarily represent a significant disposal problem.
Another disposal problem is interphase, which is produced by the oil refining process, for animal feed. Interphase is a mixture of oil, water and surfactants which forms at the boundary between the acid water and the acid oil. Because it represents a significant disposal problem, it is normally desirable to minimize the production of interphase. The easiest way to do this is to start refining with degummed oil. Degummed oil is more expensive than non-degummed oil. See Dijkstra et al., U.S. Pat. No. 4,698,185, issued Oct. 6, 1987 which is hereby incorporated by reference. It would be desirable to be able to use economically use the less expensive non-degummed oil.
One of the reasons why the interphase is difficult to dispose of is that it normally contains a great deal of sodium as a result of the sodium hydroxide refining process. This interferes, to some extent, with its use and value as an animal feed containing a great deal of fat value.
Two agricultural oil refining technologies would benefit from improved yields. One technology called the “Miscella” technology uses hexane both to extract and to aid in refining the oil. The other technology, called the “Zenith” process, bubbles the crude oil through a mass of caustic to achieve refining. These technologies are described in, for example, the following publications, which are hereby incorporated by reference:
Ziegler, U.S. Pat. No. 2,670,362 (Miscella)
Suzuki et al., U.S. Pat. No. 5,166,376, issued 24 Nov. 1992 (Miscella)
Soloman, “The Zenith process and the Kaminskij method afford lower losses in refining vegetable oils”, Revue Francaise des Corps Gras 1972, 19 (2) 107–111 (Zenith)
Kirby, U.S. Pat. No. 4,276,227, issued 30 Jun. 1981 (Zenith)
Additional background information on Miscella Refining follows. Most oilseed crushing plants in the United States utilize a solvent called hexane to remove the oil from the crushed seed (soybean, cottonseed, corn germ, etc.). The oil and hexane mixture is called miscella. Most soybean crushing plants separate the hexane from the oil prior to caustic refining. The “hexane free” oil is called crude oil.
The main difference in “miscella refining” is that the hexane remains with the oil until after the caustic refining is completed while “conventional refining” requires that the hexane be removed from the oil prior to entering the refining process.
In conventional crude oil refining the oilseed is crushed and the vegetable oil is extracted with hexane. The hexane is then removed from the mixture, leaving crude oil. A caustic (normally sodium hydroxide) is added to the crude oil. After intimate mixing, the crude oil and caustic are heated to facilitate the reaction of the caustic with the free fatty acids present in the crude oil. The fatty acids react with the caustic to form soapstock that is then separated from the refined oil by a centrifuge. The refined oil can then be further processed or pumped to storage.
Miscella refining is used extensively for refining cottonseed oil. The cottonseed crushing plant utilizes hexane to extract the oil from the crushed seed. This mixture of oil and hexane (miscella) enters the refining system where the caustic (normally sodium hydroxide) is added to the miscella. After intimate mixing the miscella and caustic soda are heated to facilitate the reaction of the caustic with the free fatty acids present in the oil. The fatty acids react with the caustic to form soapstock that is then removed from the oil by a special explosion proof centrifuge. The refined oil and hexane mixture must then be processed through an evaporator to remove any traces of the hexane. The refined oil can then be further processed or pumped to storage.
Silica/Silicates are used in oil refining to improve refining and water washing, with some resulting disposal problems.
Some oil refiners decrease the water washing needs in the refining process by the use of amorphous silica (or silicates) such as Tri-Syl in a “modified caustic refining”. See for example Welsh et al., U.S. Pat. No. 5,231,201, issued 24 Jul. 1993 and Toeneboehn et al., U.S. Pat. No. 5,298,638, issued 29 Mar. 1994, both of which are hereby incorporated by reference.
As an example, after the oil is refined it is put in a holding tank. Next, 0.4% amorphous silica is added and the oil is stirred to mix in the silica and then held. The mixture is then introduced into a filter press with bleaching earth (fuller's earth). The silica/clay remainder is a disposal problem.
There are problems raised by the high levels of sodium which could be present in various forms of oil refining fertilizer products (especially when a sodium caustic is used for refining) and the fact that most plants cannot tolerate those levels of sodium.
In refining sugar from sugar beets a waste stream of potassium sulfate is created and considered a serious problem. This material is very high in potassium and sulfur. The industry recovers sucrose from the raw sugar solution via ion exchange techniques. Sulfuric acid is employed as the ion exchanger vehicle. When the sucrose has been “extracted” by this technique the beet molasses left over is termed “raffinate” and is used as cattle feed. The potassium and sulfur are problems for cattle feed.
Industry would welcome an economical way to make potassium soaps. Dilute solutions of K Soaps are used as pesticides. They also have other biocidal (e.g. fungicidal and herbicidal) properties.
Agricultural oil is often degummed before refining, especially caustic refining. Natural gums in the oil have been thought to interfere with the refining process, to lower yields, and to increase problems with disposal of waste products. Therefore, degummed oil is used, despite its higher cost. Again, it would be desirable to be able to use economically use the less expensive non-degummed oil.
Soapstock from refining of agricultural oils may be directly incorporated into animal feeds. The feeds are for horses, sheep and cattle. Other feeds may use soapstock. The buyers (people) like the “aesthetics” of the feed when soapstock has been added as it imparts a “glossy” yellow color reminiscent of corn/grain (the eye appeal is strictly cosmetic to the farmer—the animals don't know the difference between feeds other than by taste) and, in the manufacture of feed “blocks”, appears to act as a release agent—i.e. the feed blocks don't stick to the equipment. Up to ⅓ of all the soapstock in the US is incorporated into feeds. Changes in refining that would improve this additive would benefit the industry.
Sodium soapstock rapidly ferments and cannot be transported from refineries to feed formulators without stabilization—e.g. by adding sulfuric acid in order to partially acidulate during transport.
It should be noted that pH may have an important effect upon both soapstock integrity and, in particular, the stability of a liquid fertilizer made from the soapstock. Such plant food products have been formulated at a pH of about 6.5. It was noticed that, after sealing the pouring spout with a foil sealer, pressure was exhibited as evidenced by the convex shape of the foil sealer and the appearance of the container in general. The addition of propionic acid was considered but, instead, the pH of the formulation was lowered in another manner to about 5.0. No pressure was observed after 6 months of storage.
The problems mentioned above are obviated and the desiderata described are obtained by various aspects of the present invention.
It is, therefore, a principal object of the invention to provide improvments in agricultural/biological (plant, animal, fish) oil refining, extracts and by-products of these and other raw material refining processes, and improvements in fertilizer composition and effectiveness.