US2493507A

US2493507A - Method of producing gilsonite suspensions

Info

Publication number: US2493507A
Application number: US656170A
Authority: US
Inventors: Manson Daniel
Original assignee: DOROTHY C SUTHERLAND; ETHEL MARY SUTHERLAND
Current assignee: DOROTHY C SUTHERLAND; ETHEL MARY SUTHERLAND
Priority date: 1946-03-21
Filing date: 1946-03-21
Publication date: 1950-01-03
Anticipated expiration: 1967-01-03

Description

Patented Jan. 3, 1950 TENT QFFECE METHOD OF PRODUCING GILSONITE SUSPENSIONS Daniel Manson Sutherland, Morrisville, Fa -assignor to Ethel Mary Sutherland and Dorothy C. Sutherland; both of M iJrrisviIIeIPaQ Serial No. 656,170 2 Claims. (01. 252- 115) No Drawinghi. Application March 21, 1946;

This invention-relates v to gilsonite suspensions and to improved paper and paper board products and to the process of manufacturing the same. More particularly, it relates to suspensions of gilsonite in water-and to the production of paper or paper board products having particles of gilsonite in close association with the fibers thereof.

It has heretofore been proposed to incorporate emulsions o f relatively soft asphaltic or bituminous materials as binders in fibrous paper or paper board pulps. 7

These emulsions are generally made by adding an earth filler suchas bentonite to the molten asphalt orbituin'en. Consequently the size of the globule of asphalt or bitumen is controlled by the amount of filler in the mixture. Naturally the larger the amount of filler the smaller the globule will be. 'These emulsions are usually stable when first compounded but become unstable as to globule size when diluted down to paper-making consistencies, varying from 0.4 to 0.8 per cent. Such asphalt emulsions are usually made from grades having a melting point of 140 F. to 180 F. and 'owing'to their gummy nature tend to delay the drainage rate on .the forming wire and soon cause"pitch spots on the surface of the wire which prevent proper formation of the sheet. I

In place of the-relatively soft asphaltic substances referred'to above, the-present invention has to do withgilsonitewhich is avery hard asphaltite and which can be ground to small particles. Such particles .of gilsonite, while having about the same specific gravity as water, cannot be dispersed orsuspendedtherein in their natural state without the aid .of emulsifiers or surface tension reducers. .Itis possible to obtain a gilsonite emulsion by the use of such emusifier substances but such emulsions are objectionable for use in the commercial paper manufacturing art. Gilsonite pastes have also been suggested but have not proved commercially practical.

I have found that the above-mentioned difiiculties can be overcome by the use of a novel suspension of gilsonite in water which suspension is formed and maintained without resort to emulsifiers 0r pastes. Y v

It is therefore an object of this invention to provide a suspension of gilsonite particles in water without the use ofemulsifiers or pastes and toprovide a process for producing such a susens n- A further object of this invention is to provide improved paper or paper board products composed of pulp fibers having specially treated gilsonite in close association therewith and to provide a processior the nanuiacturef of such products; f Other objects will appear from the'ifollowin g Since the specific "gijavityof gilsonite lies'betwe'en 1.065 and 11070 it "might :be" supposed that finely ground particles thereofvvould 'forifi a suspension if added to waterg npwever, due to 'the fact that such particles in their'natural state are not "wetted on contact withwa'tr, no such suspension'results. When added to water thegroun'd particles of gilsonite float on tnesurface as slayer and'do not form a suspensioneven' bnfagitation. Particles having such non wettable ch'aracteri'stics'cannot be used in the making of'p'aper since they would not be broughtint'o associationwith' the pulp fibers except at the upper 1 surface oflthe pulp suspension. Moreover, their presence in such form 'would adversely a'iTectthe paper making operation. I have discovered that this resistance to'wetting byiwater' disappears if the particles of gilsonite are subjected to the action of a vacuum and exposed to ater'before'ftheyare again exposed to air. 'After'such'particles have been wet ,by water they form,.a suspension,and are no longer adversely affected by exposure of the suspension to air since the vacuum-extracted particles are protected by the waterfilm on their surfaces. In order to'protect'theparticles from exposure to air before wetting itis necessaryto removethe .air contained in the water. If this pr c i =n Ql Wed;. a u an a numb of particlespfigilsonite,willencounter air containedin the Water before .being Wetted, and if this cu r be Wet n ti ni pr ve ted nt the air can be removed fron 'such particles},

In carrying out my invention, I firstgrind gilsonite to the desired degree of fineness.' The particles of gilsonite are then transferred to n a container where they; are mixed with a predetermined volume f water forming alayer o n the be'from 1 to"30"per cent*solids based on the weight 3 this purpose the degree of vacuum obtainable by the usual water vacuum pump is suificient but higher vacuums may be employed by using mercury or oil pumps. In either case I believe that the eiTect of the vacuum is to extract air and some occluded gases from the particles of gilsonite, particularly from the surface areas, and to remove the occluded air from the water. The result is that the vacuum-extracted gilsonite particles become wetted by the water and form a suspension therein. In order to bring 'the water into contact with all of the vacuum-extracted particles of gilsonite, it is helpful to' provide means for agitating the mixture. This has the further advantage of allowing the air contained in the water to make its way. upward through the overlying layer of unwetted gilsonite particles. water has lost substantially all of its occluded air and many of the particles of gilsonite have lost, by vacuum-extraction, the air film at their surfaces and a certain proportion of occluded air and gases. Particles in this condition are referred to in this specification and the appended claims as vacuum-extracted which term is intended as a designation of such particles after exposure to vacuums of the type referred to above. As such particles become vacuum-extracted they become wetted by the water, thus making possible the further vacuum-extraction of additional underlying particles of gilsonite. The final result, after continued exposure to the action of the vacuum, is a suspension of substantially all of the gilsonite particles. As used in this specification and in the appended claims the term suspension is intended to designate a mixture of finely divided particles in water maintained without undue settling over moderate time periods. Some or all of such particles may be kept from settling by Brownian motion as in the case of true suspensoids. The length of time required to achieve this result is dependent upon the concentration of gilsonite particles and the degree of vacuum used. For relatively'low'Yac uums of the order of 50 millimeters of mercury (absolute) down to 1 millimeter of mercury (absolute), and suspensions of about 5% solids, the time required is from 5 to v minutes. This time may be shortened considerably where relatively higher vacuums are employed. After the vacuum extracted particles of gilsonite have formed a" suspension in the water the vacuum may be broken and the suspension exposed to air without adverse effects.

As an alternative to the process described above, the finely divided gilsonite may be subjected to the action of a vacuum in the absence of water and the vacuum-extracted particles thus formed may then be added to water from which substantially all air has been removed. Or water of this nature may be directly added to the vacuum-extraction container in which the gilsonite has'been treated. In either case it is essential to prevent exposure of the vacuum-extractedgilsonite particles to the air and to prevent the occlusion of air in the water prior to the wetting and suspending action.

While the suspension formed in the process described above has many uses where it is desired to use gilsonite, it is ideally suited for use in the production of paper or paper board products where it is desired to bring particles ofgilsonite A point is finally reached at which theinto close association with the fibers making up the paper pulp, and particularly where it is desired to use such particles as a sizing. This is accomplished by using a suspension of vacuumextracted gilsonite in water having a consistency of approximately 30 per cent solids which is then added in the fan pump of the paper or paper board machine. The amount of vacuum-extracted gilsonite which will be retained in association with the fibers will vary according to the grade of paper or paper board being manufactured. For example a corrugated board used in the manufacture of corrugated boxes may retain as high as 30 per cent vacuum-extracted gilsonite based on the airdry weight of the pulp fibers.

It is standard practice in paper or paper board manufacture to return to the fan pump the white water which escapes the fourdrinier or cylinder wires. Consequently particles of gilsonite which are'not retained in association with the fibers will be recovered and made available for association with additional fibers after passing through the fan pump. Any excess white water not returned through the fan pump can" be routed to standard save-alls where the gilsonite can be recovered. Y 7

It will be understood that the gilsonite suspension of the present invention will have many applications and uses in addition to thespecific application to the manufacture of paper and paper board products as described above.

Having thus described my invention, 1 claim: 1. Ihe method of producing a suspension of finely divided hard particles of gilsonite in water which'consists in subjecting finely divided hard particles of gilsonite to the action of a vacuum at a temperature below the melting point of said gilsonite particles, thereby substantially freeing the surfaces of said particles of air, subjecting water to the action of a vacuum thereby substantially removing all air, and mixing said particles and said'water while excluding air during the mixing step. 7

2. The method of producing a suspension of finely divided hard particles of gilsonite in water without the use of an emulsifier which consists in floating said particles on water at a temperature below the melting point of said particles, subjecting the particles and the water to the action of a vacuum whereby substantially all air is withdrawn from the surfaces of said particles and whereby substantially all air is removed from said water, and agitating the thus treated particles and water thereby forming a suspension of gilsonite particles in water,

DANIEL MANSON SUTI -IERLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Cornell June 11;, 1940

Claims

1. THE METHOD OF PRODUCING A SUSPENSION OF FINELY DIVIDED HARD PARTICLES OF GILSONITE IN WATER WHICH CONSISTS IN SUBJECTING FINELY DIVIDED HARD PARTICLES OF GILSONITE TO THE ACTION OF A VACUUM AT A TEMPERATURE BELOW THE MELTING POINT OF SAID GILSONITE PARTICLES, THEREBY SUBSTANTIALLY FREEING THE SURFACES OF SAID PARTICLES OF AIR, SUBJECTING WATER TO THE ACTION OF A VACUUM THEREBY SUBSTANTIALLY REMOVING ALL AIR, AND MIXING SAID PARTICLES AND SAID WATER WHILE EXCLUDING AIR DURING THE MIXING STEP.