US 1524843 A
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Patented Feb. 3, 1925.
UNITED STATES CHARLES C. RUPREOHT, OF OLMSTED, ILLINOIS.
PROCESS OF PREPARING FULLERS EARTH.
To all whom it may concern:
Be it known that I, CHARLES C. RUPREci-rr, a citizen of the United States, residing at Olmsted, in the county of Pulaski and State of Illinois, have invented a certain new and useful Improvement in Processes of Preparing Fullers Earth, of which the following is a. full, clear, and 'exact description.
This intention relates toa process for thepreparation of fullers earth, with the View of increasing the efficiency thereof in accordance with the particular materials with which such earth is to be used,
As is well known, the peculiar property possessed by fullers earth of removing colors from oil or other solutions is believed to be due to an absorption (through the pores or cells of such earth) of the coloring matter-the action being mechanical and not chemical. I i i It has been found that fullers earth from different localities varies in its action upon liquids, some earths giving better results with a particular oil or material than with another oil or material and dilferent earths giving different results with the same oil or material. This has resulted in a selection, for a particular oil or material under treatment, of the grade of earth that has been gound by experience to be best adapted there- An examination of the different fullers earths discloses the fact that such'earths are of a highly porous nature, being mad of tubular cells'consisting mainly of hydrous aluminum silicate. The cells contained in any particular kind of fullers earth are of practically uniform size and shape, but they difi'er in size and shape-in difierent earths or earths from diiferent localities. Earths from one locality or deposit may contain cells of one particular shape and internal diameter while earths from other localities or deposits may and do contain cells of different shapes and diameters; and it istbe lievedtha-t this difference in the shapes and the internal diameters of the cells accounts for the different in the action of the various fullers earths upon oils and other materials. In an endeavor to secure a uniform and efficient action from fullers earth, it has been the practice to reduce the same to a dry condition and then grind'it to a fineness depending upon the use'to which it is to be put. For the treatment of mineral oil, the earthis reduced to a fineness of 15-30-mesh,
Application filed January 8, 1921. Serial No. 435,945.
30-60 mesh, and -90-mesh recording to the particular oil to be treated; While, for edible oils, the earth is frequently reduced to a fineness of 200 mesh. In drying the earth, the practice has been to heat it until all of the hygroscopic water hasbeen driven off and most of the combined water liberated, using for this purpose a temperature of at least 900 degrees F. This method of treatment has resulted in ruining manygood clays and has proven detrimental in' a great many cases, due to the excessive heating.
I have found that the entanglement of the coloring matterof oil or other materials under treatment in the pores or cells of fullers earth depends on three factors, namely; the size and shape of the. pores or cells 1n the earth, the dimensions of the coloring material (which maybe in a colloidal condition), and the surface conditions of the pores or cells. By the modes of treatment set forth hereinafter, I have been enabled to produce the proper conditions in the cells or poresof the earth to enable the latter to operate efliciently with any particular medium under treatment.
In some fullers' earth of low grade, the pores or cells have been found to be of such large size and the capillary and colloidal action of the same to be of such low intensity as to enable the retention of only a small portion of the coloring matter contained in the medium being treated. In, still other earths, the pores or cells are sosmall as to entangle only the smallest particles of the coloring matter, resulting in a .clogging of the earth and a decrease in its decolorizing power and eflioiency.
Where the pores or cells are of greater cross sectional area than is desirable, I subject the earth to either of the two following treatments l (A) I take advantage of the shrinkage characteristics of the earth in the following manner. Inthe process of manufacture and use, it is slowly and uniformly heated until most of the hygroscopic water is driven off. the shrinkage taking place gradually and at a temperature not much inexcess of 400 degrees F. In'continuation of the process, the earth is subjected to a'temperature greatly in excess of the former temperature for a period suflicient to give a set or surface hardening thereto which tends to maintain the internal structure ofthe earth against attrition. For the purpose ofsecuring this ing set in this condition through the sudden application of a higher temperature to its surface.
(B)As a modification of the manner of reducing the pore or cell area above described, the earth Will be first dried to an extent necessary to free it from most of the hygroscopic Water, after which itwill be percolated or saturated with a solution containing an organic or inorganic colloid, such as albumin, lue, or the mineral colloids.
The earth Wi I then be freed from most of,
the solution by percolation or other means and then dried, as in a rotary kiln. In the drying operation, the earth may be raised to atemperature suficient to secure carbonization of the colloidal material remaining in the pores; but this will not usually be necessary unless the material is very dense.
While I have referred to the use of colloidalmaterial for reducing the cross sectional area of the cells or pores and prefer this mode of reduction, I do not intend to be,
limited to the use of such material, as other materials may be employed, provided that they are capable of depositing upon the walls of the pores or cells a layer that will reduce the cross sectional area thereof but without entirely or unnecessarily obstructing the same. For instance, the earth may be saturated with coal gas and then heated sufliciently to break down the gas and deposit carbon within the pores, the heating operation being carried on in an atmosphere limited as to oxygen to render imperfect thecombustion of such gas.
In some cases, a material that will .act as a mordant may be employed for the purpose of reducing the cross sectional areas of the cells or pores. Instances of such mordants are stannic solutions-as a chloride, 'a chromate, or a sulphate of tin; also salts of alumina and-sihcic acidthe action depending upon the colloidal deposition of such material.
Where the pores or cells are of smaller cross section area than is desirable, I may enlarge the same as follows. The earth under treatment is subjected to the action of a solvent for the mineral matter, instances of such solvent being a solution of sodium hydrate or sodium carbonate, or of an acid, the solvent being capable of acting upon the silicates or other mineral matter of the earth. The solution is allowed to act upon the earth under treatment for a sufficlenttime to secure the proper enlargement of the pores or cells, after which it is neutral ized, as by Washing or by other suitable means, and the earth then dried and pre pared in the ordinary manner. An acid solvent that may be used to advantage is corbonic acid gas dissolved in water, the particular reagent not only enlarging the pores themselves but leaving the surfaces of the same in an active colloidal condition.
While my invention has been described as specially adapted for the 'ireparation of fullers earth it will be applicable to other clays, as I have found it possible through the mode of treatment described herein to impart a degree of decolorizing action to clays that previously did not possess such capability. Hence, b the use of the expression fullers eart in the claims, I do not ropose to limit my invention to the particu ar clays now known to the trade as fullers earth.
Having thus described my invention, what I claim is:
l. The process of preparing fullers earth which comprises drying the same to free it from hygroscopic water contained therein, saturating the earth thus treated with a .colloidal solution, removing from the pores or cells a proportion of such solution, an drying the earth.
2. The process of preparing fullers earth which com rises removing hygroscopic Water there rom, then treating the earth with a reagent capable of leaving within.
the pores or cells thereof surfaces of colloidal material, and drying the earth thus treated.
In testimony whereof, I hereunto aflix my signature.
CHARLES C. RUPRECHT.