US1964985A - Manufacture of lubricating oil and paraffin wax - Google Patents

Description

Federated July 3, i934 OFFICE I /EIANUFACTPURE F LUBRICATING 01L [3ND PAR WAX corporation of Maine No lllrawing. Application April 26?, 1931,

, Serial No. 531,596

2 Claims.

This invention relates to the manufacture of parailin waxes from mineral oils and particularly to a method for the manufacture of such waxes in such manner as to admit of their recovery from mineral oils to a greater'degree and yield ironi'any particular wax bearing fraction: of a mineral oil than by any method heretofore known.

. The invention broadly contemplates a process w of separating solid hydrocarbons from liquid hydrocarbons comprising dissolving wax containing mineral oils in a solvent possessing the properties oi dissolving all the hydrocarbons contained therein at elevated temperature and hav F1155 ing a eelective'solvent action between the liquid hydrocarbons and solid hydrocarbons at relatively low temperature, chilling the liquid solution to a point where the solid hydrocarbons separate out, removing the liquid hydrocarbons in solution from the separated solid hydrocarbone, and subjecting the separated solid hydrocarbons to pressing under pressure sumcient to remove entrained oil and solvent, followed if desired by 1 t treatment of the solid hydrocarbons.

V In a prior application, Serial No. 313,346, I have described a method for the manufacture of low cold test oil by the removal of solid hydrocarbons from wax distillate. My present inven tion, which is a continuation in part of the aforementioned application relates to the treatment oi wax bearing fractions and to the further treatment of the separated solid hydrocarbons in such a er as to make them nierctable 35 and salable in the form known to the trade as 1 In the ordinary methods as used by the trade in the manufacture oi waxes from mineral oils, it has been customary either to obtain a heavy to distillate and apply heat to the distillate in order to remove or convert these-called amorphous was and render the was crystalline and there-- fore more easily separated or to make a rather narrow range medium viscosity distillate. The

-ii-wan distillate is chilled and run into a, filter prees oi the w I r irame and plate type and V allowed to stand in these presses under pressure until a desirable state of "ess lie obtained. lay reasonof the methods employed, either by to the destructive heat treatment oi the i or by reason of the solubility of the waxes in the nitrate, a great part of the wax ia'lost either being destroyed by heat or carried through the process oi filtering by the filtrate. I have dis to covered by the use of the herein mothods that not only can increased yields of waxes be obtained but in addition thereto waxes can readily be obtained having higher melting points than are obtained by ordinary methods.

In the preparation of a wax for sweating it is not only necessary that the wax should be left in a condition suitable for the sweating process but it is also necessary that the unsweated wax be in such condition that after sweating it shall retain the desired melting point and also ,the quality of retaining in its crystalline condition a tenacity or ductility sufficient for adherence not only .in itself but'sufficient for the purpose to which it is applied, that is, it must not be of the crumbly nature frequently found in highly refined wax. It also must, even in the high melting point series, be void of friability or crumbliness. It also must be free of adhering and contained oil so that in its use it can be handled either in its solid form or used for coatings, etc., without imparting a stain to articles in which it is wrapped or contained,.or without imparting to the hands of the person handling it the greasy feeling which accompanies an im perfectly refined paraflln wax. 7

Likewise paraiiln wax containing undesirable impurities may be totally unsuited for the manuiacture of foodcontainers because the retained and adhering oil-not only impartsunpleasant taste and odorto the food contained in the package but'in addition thereto stains the material wrapped in the wax paper and renders it unsalable. i

The usual methodoi removing thlscontained oil is we process known to the trade as sweat- 9o ing. By this sweating method all of the contaminating or harmful oil is removed and the wax takes on the desired characteristics. In this progess of sweating, the temperature of a crystallined mass of impure wax is. slowly raised to the point where the adhering oil separates out, this treatment being usually accomplished in succes-. sive steps witha gradually raised temperature in each step and is kept up and maintained until, as before stated, the wax shows the desired characteristics. In the manufacture of wax from socalled pressable distillate, as obtained in the trade by the exercise 0! reasonable care, it was easy to obtain a wax which was easily sweatable and ofiered no dimculty in manufacture.

In this method of the prior art, however, all the wax is not removed irom the pressable oil and the wax removed in pressing constitutes that portion which is more easily sweatable, while those free-*- tions remaining in the oil are relatively more (111- whereby in such process substantially all of the solid hydrocarbons are removed difiiculties have I been encountered in the manufacture of sweatable wax from the solid hydrocarbons removed from the wax bearing fractions. .The resulting separated solid hydrocarbons or wax concentrates do not satisfactorily respond to the usual sweating operation.

In place of the so-called sweating action the mass has a tendency to melt as awhole, that is, the mass has practically what is known inthe trade as a pour point rather than a melting point. It was very difiicult if not impossible to produce sweatable wax from wax bearing fractions where solvent extraction was used for the production of low cold test oils without a series of operations which were in themselves not only expensive but rather unreliable in their working i d results.

- commercial use since recrystallization carried too far while giving a parafiin wax of very high melting point may and frequently does result in a wax totally unsuited for the above mentioned purpose since it will not adhere to the paper and upon folding breaks and leaves the paper free from the wax coating, and also as used for moisture and air proof packages does not under heat make a tight seal because of this breaking away from the surface to which it should adhere.

I have discovered that by a suitable treatment of solid hydrocarbons separated from wax distillate or wax distillate equivalents, as described in my aforesaid prior patent application, there can readily be produced paraflin waxes of any desired melting point possessing all the characteristics or quality desired by the trade, and this treatment can be cheaply effected and readily applied as in the manner herein described.

My invention comprises dissolving a wax distillate in a solvent possessing the property of dis,- solving all of the hydrocarbons at elevated temperature, of say F. and above, and having a selective action between the liquid hydrocarbons carbons separated out in the press to continued pressure thus removing entrained solvent and oil from the solid hydrocarbons; then removing the solvent from the pressed solid hydrocarbons by evaporation, and further treating the solid hydrocarbons to remove any entrained oil which may be retained therein.

As an example: 1,000 gallons of wax distillate having a viscosity of 450 at 100 F. is dissolved at a temperature of 90? F. in a mixture of 1110 gallons of acetone and 1890 gallons of benzol, and the resulting mixture is cooled to 10 F. by passing through suitable cooling coils during which separation of the wax constituents as solid hydrocarbons occurs. The resulting admixture of liquor and solid hydrocarbons is then pumped into a filter press, such as a plate and frame type of press for example, to filter out the solid hydrocarbons and deposit them in the form of cakes within the press. The fiow of mixture to be filtered is continued into the filter press until indicated in the approximately a pressure of 400 lbs. is attained and the pressure is then maintained on thefilter press at this point for approximately 1 hours to produce a substantially oil free cake. The pressure is then cut off, the press opened and the solid hydrocagbons plus entrained mother liquor transferred to evaporating means where the solvent is evaporated oif. The crude wax thus obtained is transferred to sweating pans and sweated in the usual manner.

In the above described example the filter cake at the end of 1 hours will contain approximately 40% of retained solvent. The period'of pressing may be of a shorter or longer period depending on the, cake of material under treatment. The

period of time under which the mass is under pressure is easily determinedsince if the pressure is maintained long enough the wax is readily sweatable but if it contains too much solvent the concentration of undesirable material, upon removal of the solvent by evaporation, is too great to allow satisfactory sweating. The filter pressing operation is advantageously carried out at temperatures of 10 F. or below to obtain a satisfactorily and uniformly sweatable wax. The solvent recovered from the pressed cake. may be used by itself or be combined with that recovered from the main body'of filtrate for dissolving fresh wax distillate fractions from which solid hydrocarbons are to be separated.

The invention is not limited to the treatment of a wax distillate such as given in the example herein, but is adapted to the treatment of other wax containing fractions or precipitates obtained from crude oils and may, for example, embrace the treatment of solid hydrocarbons contained in a slack wax producedin the manufacture of low cold test lubricating oils such as disclosed in my prior application, Serial No. 313,346, and which material is an equivalent of the stock referred to in the example. While the example described advantageously sets forth one mode of operation, the invention is not restricted to any particular set of operating conditions such as that of temperature or pressure, as therein described, and it is therefore contemplated that many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are appended claims. I claim:

1. In dewaxing viscous wax-bearing mineral oil of cylinder stock viscosity, substantially free from constituents having a boiling point equal to or below that of gas oil, the method of obtaining from said wax-bearing oil in a single filtering operation a lubricating oil of around 0 F. pour test or below and a readily sweatable paraffin wax comprising with the wax-bearing oil a selective solventJiquidhaving the essential selective solvent action of a mixture of acetone and benaolv and which at temperatures of approximately 100? F. has substantially complete solvent action on a mineral oil wax distillate substantially free from constituents having a boiling point equal to or below that of gas oil and at temperatures of 5' F. and below has substantially complete solvent action on the liquid hydrocarbons therein but substantially no solvent action on the solid hydrocarbons therein and of such anature that upon cooling a solution of such wax-bearing mineral oil in the solvent liquid to 0 F. and removing the solid hydrocarbons-so precipitated and the solvent liquid, the

IesuIting oil has a cold test of substantially 0 F., cooling the mixture to a temperature at which substantially all of the solid hydrocarbons separate, introducing the cooled mixture to pressure filtering means, filtering from the mixture the mother liquor of solvent liquid and dissolved oil, forming a wax concentrate containing retained oil and solvent, holding the resulting concentrate within the filtering means and continuing to subject it to an increasing pressure until suflicient entrained oil is removed to convert said concentrate to a sweatable condition uponpevaporation therefrom of the solvent, removing the pressed concentrate, and evaporating and recovering the solvent therefrom.

2. In dewaxing viscous wax-bearing mineral oil of cylinder stock viscosity, substantially free from constituents having a boiling point equal to or below that of gas oil, the method of obtaining from said wax-bearing oil in a single filtering operation a lubricating oil of around 0 F. pour test or below and a readily sweatable paraflin wax comprising mixing with the wax-bearing oil acetone and benzol in such a ratio to each other and to the oil that the acetone and benzol together, at temperatures of approximately 100 F., have substantially complete solvent action on a the solvent liquid, the resulting oil has a cold test of substantially 0 F., cooling the mixture to a temperature at which substantially all of the solid hydrocarbons separate, introducing the cooled mixture to pressure filtering means, filtering from the mixture the mother liquor of solvent liquid and dissolved oil, forming a wax concentrate containing retained oil and solvent; holding the resulting concentrate within the filtering means and continuing to subject it to an increasing pressure until suflicient entrained oil is removed to convert said concentrate to a sweatable condition upon evaporation therefrom of the solvent, removing the pressed concentrate, and evaporating and recovering the solvent therefrom.

FRANCIS X. GOVERS.