US1155741A - Process of treating sugar-cane. - Google Patents

Description

rna nnrornrcn OF BOSTON, MASSACHUSETTS,

A CORPORATION OF NEW JERSEY.

= PROCESS OF TREATING SUGAR-CANE.

No Drawing.

To all whom it may concern Be it known that I,'TENNANT LEE, aciti-.

zen of the United States, residing at Dedham, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Processes of Treating Sugar-Cane, of which the followmg is a specification. r

This invention is a process hav ng for its ob ect a more advantageous 'ut1l1zat1on of ,so-called bagasse or megass? which terms are herein synonymously used to designate the moist woody residues from the milling of sugar-cane. v

agasse is at present commonly burned as fuel for steam generation. Usually the bagasse production of a cane'sugar factory is somewhat less than its total fuel requirements, rendering it necessary to supplement the bagasse by other forms of fuel.

It has frequently been proposed to utilize the bagasse as paper stock, and many attempts to accomplish this have beenmade. Such utilization hasfnot heretofore proven commercially practicable, partly on account of the comparatively low yield and inferior grade of paper obtained, and partly on account of the necessity involved in all prior methods of substituting for the bagasse other and more-expensive fuels, as wood,

gcoal or oil.

I cellent. commercial jected, and that present invention, exgrades of paper are obtained from the bagasse, Withsatisfactory yields from the raw material, and without excessive expenditure for other fuel.

The present invention is based on the following considerations :Ordinary mill-badelivered to the burners, contains approxlmately 50 per cent.- of moisture associated with a variety of plant tissues which are. not equally adapted for paper-making purposes. Furthermore, it is commonly believed that these tissues have been injured or impaired for paper-making According to the purposes by the heavy crushing and milling operations to which they have been subsuch. injury accounts. large-measure for the weakness and inferior quality of the paper heretofore produced from bagasse.

Careful studies of the actual condition of the plant tissues in the bagasse from a heavy nnlling-plant, located in the tropics, and comprising a cane crusher and nine Specification of Letters Patent.

mak1ng purposes,

' is such that I selectedfiber Patented Oct. 5, 1915.

Application fil ed September 16, 1913. Serial No. 790,126.

rollg have now shown :that while such injury as is above referred to has in fact been incurred by the fibers, this injury is, contrary to expectations, very largely confined to the thick-walled ground tissues adjacent the rind, and to the highly silicious' cells of the rind itself. Even aside from the im pairment of the fibers due to the crushing and milling, the rind and adjacent tissues have proven to be ill adapted for paperowing to their brittle character, their high silica-content, their resistance to alkaline lyes, and the associa- -tion therewith of coloring-matters.

The or pith, likewise paper stock, and

thin-walled ground tissue, constitutes a very inferior is largely destroyed in the usual processes of digestion. v

y process contemplates such treatment of the moist bagasse as will result in the separatlon therefrom of those fibers, or a certain proportion thereof, which are in I themselves best adapted for paper-making,

and which have not been lmpaired in value for this purpose by the crushing and milling operations. Such fi for convenience termed selected fiber. The separation and separate recovery of the selected fiber involves a partial drying of the original moist bagasse, and such treatment of the partially dried material as will eliminate therefrom, as completely as may be practicable, the soft pith-cells on the one hand, and the hard rind and impaired heavy-walled, ground tissue on the other here are hereinafter hand. These rejected portions of the tissue, 7

usually constituting more than 50 per cent. of the woody matter of the original bagasse, are conveyed directly to the burners and utilized forge eration of steam. While the weight, of pa 'ially dried material thus available for fuel is materially less than the weight of the bagasse from which it was de rived, its fuel value per unit of weight is materially greater than that of the original moist bagasse,.-so that the requirements of the factory for other fuels are not excessively increased. At the same time, the character and condition of the selected fiber am able to prepare therefrom excellent grades of paper; and the shrinkage in the preparation of paper stock from this fiber is no longer excessive, because the is substantially uniform in respect to the action of the alkaline lye or other liquor used for digestion, by reason of its comparative freedom both from the highly sensitive pith and from the highly resistant rind. Hence this process overcomes each of the known disadvantages of the use of bagasse forpaper-making purposes, viz., the inferior grade of the paper, the heavy shrinkage of the stock, and the total loss of the fuel value of the bagasse. It is also advantageous that the new process may be used in connection with existing milling-plants by mere additions to the existing equipment.

The present process may be carried out as follows :The moist bagasse is dried, preferably by agitation in a current of highly heated gases of combustion, to a moisturecontent of 15 to 25 per cent, and is thereby brought to such condition-that those portions of the pith which still adhere to the fibrous strips may be, to a' large degree, shaken free by impact. or detached by a shredding or picking process. The degree to which the drying is carried is chosen solely with reference to the facility with which the component tissuesmay be separated. Satisfactory results as regards the detachment of the pith and the separation of the selected fiber from the pith and rind may be obtained by the use of a Williams ulverizer, or other impact device, followed y screening by a series of vibratory screens of varying mesh; or in general any device or series of devices capable of detaching the pith and separating the selected fiber may 1 be employed, whether their use involves one or more operations. For. example, the separate recovery of the selected fiber may be accomplished by methods involving-the use of air flotation. The rejected fractions of the bagasse, which may be designated for convenience the pith. and rind portions, are

conveyed directly to the burners, their'increased fuel value due to the partial drying largely compensating the withdrawal of the selected fiber. The selected fiber is preferably washed, usually by systematic diffusion, and is then-digested for the preparation of paper stock. The condition of digestion are chosen with reference to the requirements ofthis substantially uniform selected fiber,

thereby avoiding the necessity which is inherent in processes utilizing the harder fibers of the rind and. adjacent parts, of carrying out the digestion under such drastic conditions that the more sensitive fibers, in-

cluding those herein referred to as selected fibers, are either destroyed or their value greatly impaired. The following conditions have been successfully employed, it being understood that the invention is not limited thereto :The selected fiber is digested for about eight hours under forty pounds steam pressure, in presence of caustic soda equivalent to above fourteen per cent. by weight of the dry fiber. The weak sugar liquors from the washing of the selected fiber are preferably applied to maceration between the mills whereby the sugar-content of the selected fiber is conserved, and the total yield of sugar is correspondingly increased.

1. The herein-described process of treating moist sugar-cane bagasse to prepare therefrom a fibrous concentrate suitable for paper-making, and a fuel, which consists in drying the moistbagasse to'a condition suitable for the-mechanical grading of the plant tissues, mechanically dissociating said tissues and separating the harder and softer tissues from the intermediate selected fiber suitable for paper-making.

2. In a process of utilizing moist bagasse from sugar-cane, the steps which consist in drying the bagasse to a condition suitable for the mechanical grading of the plant tissues, mechanically dissociating said tissues, separating the harder and softer tissues from the intermediate selected fiber, and digesting the selected fiber.

3. In a process of utilizing moist bagasse from sugar-cane, the steps which consist in drying the bagasse to a condition suitable for the mechanical grading of the plant tissues, mechanically dissociating said tissues, separating the harder and softer tissues from the intermediate selected fiber, washing the selected fiber, and digesting the washed fiber.

In testimony whereof I affix my signature in presence of two witnesses.

TENNANT LEE.

Witnesses J AS. H. BLAGKWOOD, G. P. TOWNSEND.

Corrections in Letters Patent No. 1,155,741;

specification requiring correction as follows:

8 It is hereby certified that in Letters Patent No. 1,155,741, granted October 5, 1915 upon the application-of Tennant Lee, of Ded ham Massachusetts, for an I improvement Processes of Treating S1 1gar-Cane,err0rs abpeer in the printed dition readwond'itions; same page, line 65, for the word abovev read about; and

that the said Letters Patent should' be read with these corrections therein that."

the same met conformto' the record of the case in the PetentOtfic- Signed and sealed this Zndday 9f November, A. D., 1915, v .R. F. WHITEHEAD, I

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