US1511664A - Process of making fiber for paper, etc - Google Patents

Description

VIGGO DREWSlEN, F BROOKLYN, NEW YORK, ASSIGNOR TO WEST VIRGINIA PULlP NEW YORK, N. Y., A CORPORATION OF DELAWARE.

AND rarer. COMPANY, or

PROCESS OF MAKING FIBER FOR PAPER, ETC.

No Drawing. Application filed July 19, 1920, Serial N 0. 397,484. Renewed November 14, 1922. serial No. 600,987. a

Be-it known that I, VIGGO DREWSEN, a

, citizen of the United States, and resident of the borough of Brooklyn, county of Kings, city and State of New York, have made certain new and useful Improvements Relating to Processes of Making Fiber for Paper, Etc, of which the following is a specification.

Thisv invention relates especially to processes for producing fiber from wheat straw, rice straw, etc., by treating the raw fibrous material under pressure in a suitable monosulphite solution and then, preferably, after removing the treating liquor, subjecting the fiber to a second acid treatment as in a bisulphite solution to further purify the fiber and facilitate bleaching.

With wheat straw, rice straw, and other suitable cereal straws such as barley, rye, oat and flax straw, the raw fibrous material may be cooked for four to eight hours or so in a monosulphite solution. under a pressure of sixty to ninety pounds more or less, to remove from the cellulose at least the larger part of the soluble material which gives the cooking liquor a dark greenish or brownish tinge. This waste liquor can advantageously be converted by treatment with slaked lime which combines with the organicv material thus releasing and precipitating the magnesium compounds it the "sulphite used is the normal or monosulphite of magnesium. It is still better to use dolomite lime for this treatment of the waste liquor; since,

in this case, the lime combines with the organic compounds precipitating the magnesium compounds from the dolomite together with thosedisplaced from the waste liquor.

The fibrous material, after this first or preliminary treatment with magnesium, so dium or other soluble sulphite, preferably of alkaline character and reaction, can advantageously be treated with a' suitable acid treating liquor such as sulphuric or sulphurous acid or the acid sulphites or sulphates, these being cheap and available acid materials. A desirable way of effecting this acid treatment is to have the fiber pulp suspend; ed in enough water so as to pump freely and then run the same through a treating, scrubbing or percolating tower into which sulphur dioxide may be run, preferably in hot condition from the sulphur burners, etc. after a preliminary electrostatic purification.

This treatment, which may be efiected at atmospheric or moderate pressure in some cases, should be continued until the acid has thoroughly acted on the plup liquor and gives it an acid reaction; the acid treatment dissolves out some further organic material which gives the li nor a dirty greenish tinge and leaves the pn p in a very much cleaner and whiter condition so that the subsequent bleaching of the pulp is greatly simplified, only a few per cent of bleach being required to give thoroughly satisfactory results, and for some purposes further bleaching is unnecessary, which makes possible a still higher yield of strong fiber. After this sulphur dioxide treatment the liquor may be run through a screen to remove the pulp and the liquor reused for another treatment in some cases, which prevents waste of the absorbed sulphur dioxide, the absorbed gas being, of course, recovered by being eliminated by heat treatment of the final liquor when its reuse is undesirable. This sulphur dioxide or other acid treatment of the pulp produces in the treating liquor, acid sulphites of magnesium or other material; so that the fibrous material is first treated with an alkaline treating solution and then with an acid solution which more thoroughly eliminates all soluble components without drastic or injurious action on the fiber.

Incommercially operating this process, the first waste liquor from the raw fibrous material may be treated with calcined and slaked dolomite in powdered form and this brings down, with the magnesia of the dolomite, the magnesia which had been held in organic solution in the waste liquor, both vthese magnesia components being removed by filter-pressing. This magnesia is preferably purified by calcining to eliminate any traces of combined organic material, and then it may be dissolved by carbon dioxide treatment under pressure to produce the acid magnesium carbonate or bicarbonate of magnesium. This solution may advantageously be filter-pressed which thus removes any silica or other insoluble material;

and the solution may then be treated with magnesium acid sulphite which produces the normal sulphite of ma esia and liberates carbon dioxide whic may be reused in' the other step of the process to the extent necessary and the surplus sold.

A surplus of magnesia is also produced in this process which can be disposed of so as to help pay for the primary raw treatpyrites.

ing materials, dolomite and sulphur or may be transformed into the bisulphite form by treatment with sulphur dioxide, for use in the foregoing step of the process.

It is sometimes desirable, also, to treat the calcined magnesia which may be produced as above described from the first waste liquor of the process with sulphur dioxide in water suspension to form magnesium monosulphite; or, if desired,- the original magnesia precipitated from the waste liquor may be treated with sulphur dioxide without such calcining purification treatment so as to form the monosulphite or bisulphite directly therefrom. Where sodium monosulphite is usedas the treating liquor the soda may be recovered, as by evaporating ,and calcining or dry distilling the waste sulphur dioxide.

whilecarbondioxidejs set free.

liquor, and then leaching may be used tov recover the soda in caustic, carbonate or sulphate form. It is preferable however, to

Rice straw, when treated with magnesium monosulphite or other suitable monosulphite in the manner described, is uite completely separated into its ultimate bers which are extremely fine and strong; and these delicate fibers are not appreciably injuredor seriously reduced in strength by this'treating agent. The diameter of'these ultimate .rice straw fibers is about .006 mm. which is,

of course, very much finer than wheat straw fiber which has a diameter of about .020 mm. while sulphite fiber has an average diameter or width of about .030 min. This rice straw fiber, which may, of course, be

' bleached and refined in various ways,

especially by treatment with an acid sulphite solution after removal of the original monosulphite cooking liquor, is especlally desirable for fine or high-grade papers including Bible paper, tissue paper, cigarette paper, etc. The small diameter of this rice straw fiber, which is ractically the same length as the fiber o wheat straw, etc., gives to the rice straw fiber extremely good felting or paper-making qualities so that strong and tough paper can readily be produced even in extremely thin grades.

In some cases for cheaper grades of paper, card-board etc., wheat, rice or oat straw Part of the magnesium sulphite' may be under-cooked with magnesium or sodium monosulphite, so that a large part but not all of the connective tissue is dis solved or removed. A treatment of two to four hours under a pressure of forty to sixty pounds or so per square inch, usually gives this result and renders the fibrous material sufficiently separable, so that by a beating or mechanical refining treatment, the fiber may be rendered suitable for news print or other medium grade papersand a yield of fifty to sixty per cent or more of such relatively coarse fiber can be secured from some grades of ordinary wheat straw for instance.

This invention has been described in connection with a number of illustrative materials, proportions, conditions, arrangements'and orders of steps, to the details of which disclosure the invention is not of course to be limited, since what is claimed as new and what is desired to be secured by Letters Patent is set forth in the appended claims:

1. The process of producing fiber from cereal straw which comprises cooking the same under pressure in a strong water solution of magnesium monosulphite, removin the treating liquor and suspending the fi r in water to form a flowable pulp and repeatedly treating the pulp with hot sulphurous acid gas to dissolve and remove additional organic'material and form a readily bleachable strong fiber.

2. The process of producing fiber from cereal straw which comprises cooking the same under pressure in a solution of magnesium monosulphite and repeatedly treating the treated fiber with hot sulphurous acid gas to dissolve and remove additional organic maierial and form a readily bleachable strong ber.

3. The process of, producing paper fiber from cereal straw which comprises cooking the same under pressure in a strong water solutionv of soluble monosulphite, removing the treating liquor and suspending the fiber in water to form a fiowable pulp and treating the pulp with sulphurous acid material to dissolve and remove additional organic material.

4. The process of producing paper fiber from cereal straw which comprises cooking the-same under pressure in a solution of S01- uble monosulphite, removing the treating liquor and suspending the fiber in water to form a flowable pulp and treating the pulp with an acid reagent to dissolve and remove additional organic material.

5. The process of producing fiber from cereal straw or other raw fibrous material whlch comprises cooking the same. under pressure in a solutlon of. alkaline-monosulphite, and subjecting the fibrous material to an acid treatment dissolve and remove ad LMLQM ditional organic material and form a more readily bleachable strong fiber.

6. The process of producing paper fiber from wheat straw which comprises boiling the straw under pressure in a soluble monosulphite solution having an alkaline reaction and treating the fiber with a hot acid sulphite solution to remove additional organic gnaterial and promote the bleaching of the ber.

7. The rocess of producing fiber from straw which comprises boiling the straw under pressure in a soluble monosulphite solution and treating the fiber with a hot acid sulp-hite solution to remove additional organic material and promote the bleaching of the fiber.

8. The process of producing paper fiber from wheat or rice straw which comprises boiling the straw under pressure in a m esium monosulphite solution having an aline reaction, removing the treating liquor and treating the fiber with a hot acid sulphite solution to remove additional organic fpgeterial and promote the bleaching of the 9. The process of producing paper fiber from straw which comprises boiling the straw under pressure in a magnesium monosulphite solution having an alkaline reaction and treating the fiber with a hot acid solution to remove additional organic material and promote the bleaching of the fiber.

VIGGO DREWSEN.