US1688904A - Process fob - Google Patents

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PROCESS FOR SIMJLTANEOUSLY MAKING SUGAR AND PAPER PULP FROM CANE Filed Aug. 50, 1927 fhper Pa 2,0

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EUGENIO ANTONIO VAZQUEZ, OF HABANA, CUBA, ASSIGNOR '10 VAZCANE PROCESS, INC., A CORPORATION OF DELAWARE.

PROCESS FOR SIMULTANEO'USLY MAKING SUGAR AND PAEER PULP FROM CANE.

Application filed August 30, 1927, Serial No. 216,848, and in Cuba June 2, 1927.

This invention relates to the treatment of vegetable tissues, such as sugar-cane, and, more particularly, to a process and a combination of apparatus whereby the soluble products and the cellulose of the plant tissue are recovered in forms suited to subsequent manufacturing processes.

In the production of sugar, particularly from sugar-cane, it has heretofore been the usual practice to tear or crush the cane into shreds and then to pass the shredded cane between heavy rolls by which the saccharine juices are squeezed out of the plant tissues. These rolls are of cast iron, Weighing frequently as high as fifteen tons each; and the cane is passed successively through several sets of such rolls adjusted progressively closer together.

In some cases it has been the practice to add water to the cane just prior to passing it through some of the rolls. This dilutes any juice remaining in the cane and facilitates its removal.

It has also been suggested to shred the cane and then after thoroughly drying it to saturate it with water, which is later pressed out carrying with it a large part of the sugars. Another method which has been proposed is to slice or granulate the cane and remove the sugar by a diffusion process. In all of these processes the pieces of cane must be large enough to permit ready diffusion of the water, generally about one quarter inch, and the residue is in the form of a course stringy mass commercially known as bagasse. This bagasse has been generally regarded as a waste product and burned in the steam plant of the sugar mill. How-- ever, in recent years, due to the diminishing supply of forest wood, considerable attention has been attracted to bagasse as a raw material for the manufacture of paper pulp. Although much research has been conducted and many plans have been proposed for making paper from bagasse, none has been attended with great commercial success. So far as I am aware, the only important commercial utilization of bagasse is in the production of insulatin wallboard, in which, after a special prellminary treatment, the coarse filaments of the bagasse are pressed into a loose felt. The filaments of this board are not to be confused With the fibers or fiber aggregates of a paper pulp, but resemble more closely blades of dry grass or hay.

I have discovered a novel process by which I am able to recover sugar from the sugarcane .more completely than has heretofore been considered possible, and at the same time to produce a cellulose pulp in a. form which is well adapted for the production of paper, board and other paper pulp or cellulose products.

My process consists, briefly, in separating the cane by grinding or abrading it into individual fibers or aggregates of relatively few fibers, so small as to be unsuitable for any of the prior methods of sugar recovery. This comminuted material I disperse in a solvent bath in which it is agitated until the solvent is thoroughly worked into the fibers, the solvent-or more accurately, the sugar solutionis then separated from the comminuted cane and the latter redispersed in a second bath. In this bath the material is again agitated in the same manner as in the first, after which it is again separated. These steps of dispersing, agitating and separating are repeated as often as is necessary to complete the separation of sugar from I the cane. In order to avoid adding unnecessary amounts of liquid I circulate the solvent counter-current to the cane; that is I add fresh water only to the final bath; and the weak solution separated from each bath becomes the solvent liquid for another until in the initial bath it is removed as relatively concentrated sugar solution and taken to the boiling house.

The fibers of this pulp product, since they have not been subjected to the injurious crushing action of the usual sugar mill, are stronger and altogether more desirable than fibers which have been produced from bagasse and having been substantially separated they are in a condition suitable for the manufacture of paper or board.

I have also found that when my invention is followed a considerable economy in power is eflected, since I eliminate entirely the use of crushing rolls and shredders.

In the practice of my invention I prefer to use a combination of apparatus such as I have shown in the accompanying diagrammatic drawing. Each element of this combination is an apparatus already well known to the art. However, I believe myself to be the first to use such apparatus in the present combination, and I believe that the process, as well as the product, resulting from the use of this apparatus is novel.

Referring now to the drawing, I have shown at l a hopper or magazine adapted to hold a supply or sugar-cane or other material to be treated. At the bottom of this hopper is a grindstone 2 running in a re ceptable 8 containing a bath of solvent llquld. Consequently the operation of the grindstone will cause the solution to be carried to the cane and cause the grinding to take place in a substantial amount of liquid. This apparatus will be recognized as a magazine grinder known to the art of making wood pulp. The magazine 1 is shaped adjacent the stone 2, "so that, as the latter revolves, the cane is crowded against the stone and held from passing through to the receptacle 3. In this way, the individual fibers or fiber aggregates are torn away from the cane and distributed into the liquid bath, producing a pulp resembling niechanical wood pulp or ground wood. This pulp passes directly to an agitator or mixing box 4, or may first be screened to remove larger pieces of cane which may have found their way into the pulp. An agitatorblade 5 in the mixer maintains the pulp in suspension.

The overflow from the mixing box 4 passes into a separator 6, which in the present case is shown as a pulp thickener, well known in the paper making art. In this form of separator a cylindrical screen 7 revolves partially submerged in the pulp so that the water, or liquid, passes through the screen and is drawn off through the opening 8, while the solid portion of the pulp is deposited on the screen, carried out of the bath and scraped by the doctors 9 into a second mixing box 4. The pipe 1O discharges the weak sugar solution from a subsequentseparator 6 into this mixing box. Any number of separators and mixing boxes may be used according to the nature of the material being treated and the conditions, such as the temperature of the 'water'and the velocity ofthe passage through the apparatus. Into the last mixing box fresh water is directed from the pipe 11, and from the first'separator the strong sugar solution is discharged through the pipe 12 to the sugar boiling house. The liquid from the second separator is conducted through the pipe 10 to the grinder 2, where it is sprayed uniformly over the surface of the grindstene. The pulp from the last separator is discharged into the conduit 13, from whence it is taken directly to a paper making plant or to a machine where it is made into pulp lap for shipment. Thecountencurrent washing of the finely divided vegetable material is enhanced by the successive separations of the pulp from the liquid. This repeated separation and redistribution of the pulp produces a more intimate circulation of the water through and into the fibers, thereby dissolving all of the sugar, while the mechanical treatment to which the material is thus subjected produces a further separation and brushing out 01" the fibers, which reduces the amount or beating required in the subsequent treatment 01 the paper pulp.

ii the pulp is to be used in'in'iediately in the manufacture of paper or board, one or more of the agitators may be of the type known to the paper art as continuous heaters, having a perforated back-fall through which the beaten pulp is withdrawn to the separators. Likewise, each of the units of the apparatus is intended to be exen'iplary, and I may use any other units which accomplish similar results.

I have found in practice using the process and apparatus described above that it is possible to obtain aln'iost complete extraction with only thirty percent dilution of the natural juice content of the cane. This is materially less than is required, for example, in the continuous diffusion apparatus now used in the beet sugar industry. Since all of the water must be evaporated, it is evidently important to reduce to a minimum the amount oi" water added during the extraction of sugar from the cane.

I believe that the increased efiiciency of my extraction process is in a large part due to the reduction of cane to minute particles aggregates of relatively few fibers each. Be cause o1. this thorough separation, every cell of the plant tissue is exposed to the leaching actionol the solvent and a substantially com plete extraction of the sugar takes place. In the accompanying claims I have used the term fibers to define this separation into individual fibers or aggregates of relatively few fibers and to distinguish from the shredding and separation into relatively coarse filaments as known to the prior art.

It is preferable in the leaching process to use assolvent only distilled water. A cheap source of distilled water for this purpose is found in the condensed vapors from the evaporators in the sugar house. In this way all unnecessary impurities, which might be introduced with the solvent are avoided and the sugar refining simplified to that extent.

It has heretofore been thought necessary when preparing bagasse for paper making to separate the pith from the fibers of the cane. I have found, however, that when the cane is treated according to my novel process this is unnecessary and a good grade pulp is produced utilizing all of the cellulose contained in the cane. The fiberless cellulose may even improve the quality of the paper since it is readily hydrated to form a binder lOO for the fibers. My process gives a pulp which resembles in many respects mechanical or ground wood pulp and may be similarly used alone or in admixture with chemical pulps for the production of newsprint, board, etc. Also, the fibers may be subjected to a chemical treatment to dissolve any remaining non-cellulose material for the production of pure cellulose or chemical pulp. Such chemical treatment is greatly facilitated by the comminuted condition of the pulp.

I claim:

1. A process for recovering sugar from fibrous vegetable materials which comprises separating the material into fibers, agitating the fibers in a leaching liquid, separating the liquid from the undissolved fibers, and recovering the sugar from the leaching liquid.

2. A process for simultaneously producing paper pulp and extracting sugar from sugar cane which comprises separating the sugar cane into fibers, subjecting the said fibers in the presence of a leaching solvent to a mechanical treatment adapted to further separate the cellulosic fibers and to promote the leaching out of the sugar therefrom, and separating the resulting fibrous pulp from the resulting sugar solution.

3. The process according to claim 2 in which the particles of sugar cane during the mechanical treatment are moved in co antercurrent to the leaching solvent.

4:. The process according to claim 2 in which the particles of sugar cane are first dispersed in a relatively strong sugar solution, agitated therein, separated therefrom, and then redispersed, agitated in, and separated from successively weaker solutions until the pulp is finally washed in and separated from a bath of clear solvent, the leaching solvent being circulated from the last bath to the first progressively as it dissolves more sugar.

5. The process of recovering sugar and paper pulp from sugar cane which comprises abrading the sugar cane to reduce it to fibers, leaching said fibers with a sugar solvent and separating the resulting sugar solution from the fibrous pulp.

6. The process of producing paper pulp from fibrous vegetable materials which comprises abrading the tissue to reduce it to fibers and subjecting it simultaneously to a countercurrent leaching and a mechanical treatment adapted to promote the dissolution of noncellulose materials and to further separate said fibers. I

7 The process according to claim 6 in which the mechanical treatment comprises alternately thickening the pulp and mixing it again in a solvent.

8. The process of recovering sugar and paper pulp from sugar cane which comprises abrading the sugar cane in the presence of a dilute sugar solution to reduce the cane to fibers, leaching said fibers with a sugar solvent and separating the resultant sugar solution from the fibrous pulp.

9. The process of producing paper pulp from fibrous vegetable materials which comprises abrading the tissue in the presence of a substantial amount of liquid to reduce the tissue to fibers and subjecting it simultanously to a countercurrent leaching and a mechanical treatment adapted to promote the dissolution of non-cellulose materials and to further separate said fibers.

10. The process of recovering sugar and fiber pulp from sugar-cane which comprises separating the sugar-cane into fibers by means of an abrasive surface moving in contact with the sugar-cane in the presence of a liberal supply of solvent liquid, successively removing the resultant pulplike mass from the solvent liquid, and resubjecting it to the action of the solvent liquid so that the solvent liquid passes from the pulplike mass having the smallest amount of soluble content to the pulplike mass having the largest amount of soluble content, and finally separating the sugar solution from the fibrous pulp.

In testimony whereof I afiix my signature.

EUGENIO ANTONIO VAZQUEZ.

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