US2534560A

US2534560A - Saccharate-ion exchange process

Info

Publication number: US2534560A
Application number: US37495A
Authority: US
Inventors: Ralph W Shafor
Original assignee: International Minerals and Chemical Corp
Current assignee: International Minerals and Chemical Corp
Priority date: 1948-07-07
Filing date: 1948-07-07
Publication date: 1950-12-19
Anticipated expiration: 1967-12-19

Description

mama Dec. 19,1956

Ralph W. Slider, L! Gatol,

Calm, "liner to International Minerals & Chemical Corporatlon, a corpo tion of New York No Drawing. Application July 'l, 1948,

' Serial No. 37.495

'This invention 1b the production of ugar or sugar syrups from sugar-bearing solutions. More particularly, the invention relates to the production of sugar or sugar syrup! from molasses or other sugar solutions which are amenable to the Steifenprocess.

The recovery of sugar from various sugar sources (for example. sugar beets, sugar cane, pineapple juice, etc.) conventionally involves the extraction of the su ar content of the particular raw materials, usually by" diffusion methods employing water as a solvent. and the sequential evaporation of the'raw sugar solutions and crystallization of the sugar contained therein. It is known that, in addition to the sucrose values which are dissolved from the aforementioned raw'materials, a substantial quantity'of inorganic salts, organic compounds, colloidal matter, gums, and otherobjectionable matter is also either dissolved or suspended in the sugar solutions. These impurities are objectionable for numerous reasons, in that they not only contaminate the sugar crystals which are produced in the normal course of the crystallization procedurcs, but also inhibit-and in some cases, prevent-the crystallization of considerable quantitles of sugar from residual molasses or mother liquors which are obtained after several succes- 'sive crystallization procedures. .Ithas been common practice to successively evaporate the sugar solutions and subject them to crystallization procedures in order to obtain the series of strikes of sugar crystals. Successive strikes" of sugar crystals become progressivelycontaminated with the aforementioned objectionable impurities, and

must be purifiedby charcoal treatmentor by other methods which are familiar to the sugar industry. Eventually a viscous dark-colored solution, commonly called molasses, is obtained from which no more sugar'can be obtained by crystallization. This is dueto the fact that the aforementioned impurities inhibit the crystallization of the residual sucrose values" from such mother liquors.

The, problems above mentioned have been overcome, to some extent, by subjecting the orig;

inal dilute sugar solutions containing the aforementioned impurities to the action of ion exchange resins. This is usually achieved by treating the impure sugar solutions sequentially with cation and anion exchange resins. It hasbeen established that a majority of .the aforemen- 9 Claims. (Cl. 127-47) ties which are inherently present in such solutions; for example, salts of sodium, potassium, magnesium, and calcium. These salts are normally present in the form of sulfates, chlorides, carbonates, and phosphates. Occasionally some ammonium salts may also be present. It is known that a majority or these inorganic impurities maybe removed from the raw sugar solutions by subjecting said solutions to the sequential action of cation and anion exchange materials under specifically controlled conditions. It

- has also been found that these exchange mate-- rials will adsorb a certain amount of organic impurities; for example, betaine,. glutamic acid, choline, leucine, glutamine, and certain dibasic acids which are also present in raw sugar solutions. The emciency of the exchange materials, insofar as the adsorption of the aforementioned organic impurities is concerned, is not nearly so .2 great as in the case 01 the inorganic impurities.

- conditions, about 90% of the inorganic impuri- This is due to the fact that the inorganic ions are preferentially adsorbed on the exchange materials, thereby desorbing the organicimpurities which pass into the sugar-containing eiiluent. In some instances, under specifically controlled ties present in the raw sugar solutions may be removed therefrom; whereas only about 60% of the. organic impurities present are removed therefrom. It has also been found that the col-f.

, loidal impurities present in raw sugar solutions (ior example, albumens, pectins, and certain in. soluble or colloidal proteins) are also adsorbed on the cation and anion exchange materials;

The latter feature is distinctly disadvantageous, due to the fact that the adsorption of such colloidal or insoluble material on the exchange ma terials greatly reduces the capacity of such materials insofar as their ability to adsorb the inorganic and other organic impurities is concerned.

' This necessitates the frequent regeneration of the tioned impurities may be removed from the raw 1 exchange materials by means of acidic or alka-r line materials in order to remove both the colloidal and insoluble impurities, as well as the adsorbed inorganic and other organic impurities. Obviously this adds substantially to the cost of this type of operation, -due to the fact that the operational cycle must bechanged at ,rather frequent' intervals in order to prevent leakage of the "adsorbed or dissolved impurities purified sugar solutions. 1

It has also been proposed to treat molasses, which is obtained in the sugar industry according to the procedures outlined above, by means of cation and anion exchange materials. This into the ally to the extent that the non-sugars are present in amounts up to 20% by weight of the molasses. This high concentration of impurities causes the prevention of iurther formation of sugar crystals in the molasses. A standard method whereby the sucrose values in the mollasses may be recovered is the well-known Steffen process. By suitably liming the molasses. about 90-95% of the sucrose may be precipitated from the molasses as calcium saccharate. The precipitated calcium saccharate is usually treated by carbonation procedures with carbon dioxide, thereby resulting in a sugar solution in which insoluble calcium carbonate is suspended. However, it has been found that the calcium saccharate precipitate occludes certain of the aforementioned impurities which also prevent the crystallization of all of the sugar from sugar solutions resulting from the Steffen process. For example, it has been found that only about 70% of the sugar present in such sugar solutions may be recovered by present methods of Steffenizing molasses.

In a patent application published by the Alie Property Custodian on May 11, 1943, Serial No.

359,575, filed by Smit, there is disclosed a process whereby molasses from sugar beet or cane sources is subjected to the sequential action of cation and anion exchange materials, thereby accomplishing the removal of substantial ties, and these must be removed by stopping the flow of molasses through the exchange materials and backwashing the exchange materials with water and acidic or alkaline solutions.

It is an object of the invention to provide an improved process for the production of sugar or sugar syrups from sugar-bearing solutions which are amenable to the Steffen process.

It is an object of the invention to provide an improved process for the production of sugar or sugar syrups from molasses.

It is a further object of the invention to provide an improved. process for the production of sugar or sugar syrups from molasses in order to substantially increase the amount of saleable sugar available therefrom.

amounts. of inorganic and organic impurities from the molasses. For example, a molasses resulting from successive crystallizations of beet I sugar solutions is subjected to the action of certain ion exchange resins of a carbonaceous nature, thereby removing substantial amounts of inorganic impurities, lesser amounts of organic impuritiespand accomplishing the adsorption of substantial amounts of colloidal and insoluble impurities." Due to the fact that the amount of said impurities is quite high, namely about 7-10% by weight of so-called non-sugars including inorganic and organic compounds as wellas colloidal matter, the operational cycle of the resin exchanges must be frequently changed.

The flow of molasses through the exchange matcrial must be interrupted and the exchange materials reactivated by appropriate acidic or sorptionof organic impurities such as betaine and glumatic acid, causing the latter materials to contaminate the sugar-bearing eiliuent. Furthermore, the high concentration of colloidal matter in molasses causes the rapid contamination of the exchange materials with such impuri- It is a further object of the invention to produce sugar syrups from molasses which have an improved flavor and color.

It is a further object of the invention to provide an improved process for the production of sugar or sugar syrups from molasses by an ion exchange process, whereby the adsorption capacity of the ion exchange materials is substantially improved, thereby reducing the cost of such an operation.

It is still a further object of the invention to provide an improved process for the production of sugar syrups of high purity from molasses, whereby substantially all of the organic nonsugars present therein, as well as the inorganic impurities therein, are removed from said molasses.

substantially in excess of that which is recovered by Stefienizing molasses.

The above objects, as well as others which will become apparent upon a more complete understanding of the invention which will be hereinafter completely described, are accomplished by subjecting a sugar solution which is amenable to the Steffen process, to such a process; and subjectingthe resultant sugar solution to the sequential action of cation exchange material, operating in the hydrogen cycle, and acid-adsorbing anion exchange material. novel process is applicable to any sugar-bearing solution which may be advantageously treated in accordance with the well-known Steffen process, the invention is particularly applicable to the recovery of sugar from molasses which is produced as an end product from the crystallization of sugar from cane sugar, beet sugar, and other raw sugar-containing solutions. The Steilen process is particularly applicable to impure sugar solutions which containabout 50% by weight of sucrose, together with about 5-20% by Weight'of non-sugar impurities of the type previously herein described.

In general, a concentrated impure sugar solution or molasses is usually diluted with water to produce a solution containing about 5-10% by weight of sucrose. Lime is added to such a sugar solution in an amount sufiicient to combine with substantially all the sucrose contained therein,

while maintaining the temperature thereof below about 150. The amount of lime necessary is While the instant 601d precipitate, and which contains about 90% of. the sucrose originally present in the diluted molasses solution. The calcium saccharate is separated by filtration, conventionally on an Oliyer drum filter, and the resulting filter cake is carefully washed with water. The filtrate or may then be slurried with water in any convenient amount. Preferably, the resultant mixture will contain about 14% by weight equivalent of sucrose The slurry is heated to a temperature of about 85 C. and is" treated with carbon dioxide either at reduced, atmospheric or above atmospheric pressure. This operation results in the production of a precipitate of calcium carbonate and a solution containing about 15% by weight of sucrose. The precipitated calcium carbonate isseparated from the residual sucrose solution by means of filtration, and the cake is care fully washed with water, the washings being added to the original sugar-containing filtrate. The filtrate contains about 14% by weight of sucrose having apurity of about 90%. This solution is sequentially treated with cation exchange material operating in the hydrogen cycle whereby inorganic cations (for example, calcium, potassium, and sodium) are adsorbed; and with acidassaloo charate slurry.,the non-sugar impurities present. in the resulting sugar solution consist of a small amount of calcium ions which are not precipitated by the carbonation procedure, together with minute amounts of sodium and potassium ions which are present as a result of occlusion on the 1 calcium saccharate cake. Substantially all of the colloidal and insoluble organic matter also'passes into the Steflens filtrate. Therefore, the sugar solutions resulting from the carbonation step of. the calcium saccharate slurry may be treated with cation and anion exchange materials while substantially free from said organic impurities, and the ion exchangematerials, therefore, have a greater capacity for the calcium ions andv minor amounts of sodium and potassium ions, due to the fact that the-exchange materials act as a clean-up and do not become rapidly contaminated with large amounts of organic impurities. It is known that most cation exchange materials have a preferential aflinity forcalcium ions as compared to alkali metal ions. Therefore, when purifying molasses solutions as such by means of a cation exchange treatment in accordance with prior processes, the accumulation ofcalcium ions on the cation exchange material causes progressively increased leakage of the alkali metal ions into the sugar-containing effluent. It has therefore been necessary to stop the now of molasses through the cation exchange material after a adsorbing anion exchange material which re- It has been found that by conducting the in-,

stant novel process in accordance with the procedure described above, it is possible to recoverabout 90-95% of the sucrose valuesinitially contained in molassesor similar impure sugar solutions. This is in contrast to recoveries of about "10% which are currently obtained in the sugar industry by Steffenizing molasses, due to the presence of inorganic and organic impurities in the resulting sugar solutions: Also, the operational cycle of the'cation and anionexchange resins is considerably prolonged in.comparison to ion exchange processes which have been previously adapted to the refining ofsmolasses or similar impure sugar solutions. It has been found that by Steflenizing such sugar solutions under carefully ,controlled conditions, a calcium saccharate cake may be obtained essentially free from organic, colloidal and insoluble impurities'which are normally and usually present in molasses, 'and which is also essentially free from sodium, potassium, and magnesium salts. By conducting the Steffen process as hereinabove described, substanrather short period, in order to prevent such an occurrence and to reactivatethe cation exchange resin with an appropriate acidic materiaL. In accordance with the instant novel process, substantially all of the alkali metal ions have been 7 eliminated prior to the treatment of the sugar solution with cation exchange material. Therefore, the latter is subject mainly to the adsorption of calcium ions and minute quantities of organic material, and it isv possible to remain on stream" for a longer period of time without contaminating the eilluent with inorganic impuri-' ties. It has been found that when molasses or similar sugar-bearing solutions are treated with cation exchange material operating in the hydrogen cycle, the abrupt decrease in pH of the molasses, while in the presence of the cation exchange material, causes increased precipitation of the aforementioned colloidal and insoluble organic materials; The. instant novel process is substantially free frofn this particular dimculty.

In the treatment of molasses or similar sugarbearing solutions with cation and anion exchange materials, as conducted in accordancewith prior procedures, it has been found that the exchange materials also adsorb certain organic nitrogenous compounds such as -betaine, glutamic acid, choline, leucine, glutamine, and certain dibasic acids which are inherently'present in such sugar solutions. On continuing the flow of such solutions through the cation exchange resin, these nitrogenous compounds are initially preferen tially adsorbed on the exchange materials but are rapidly desorbed as the concentration of alkali metal and calcium ions on the cation ex change material increases. Unless the flow of j molasses is stopped, these nitrogenous compounds tially all of the aforementioned impurities pass line sugar ishighly objectionable; .On the other drogen cycle.

. materials in accordance with the present process may be considerably prolonged in comparison to the operational cycle permitted in accordance with prior processes and the need for reactivation of the exchange materials is considerably reduced. The treatment of the sugar solutions resulting from the Steffen process, as hereinabove described, with cation exchange material, is preferably conducted by passing said sugar solutions through a bed of cation exchange material operating in-the hydrogen cycle. A plurality of beds, arranged either in series or in parallel, may also be employed. The effluent therefrom may be passed immediately into one or more beds of acid-adsorbing anion exchange material. While this is the preferred operational method, it is to be understood that the instant novel process is not necessarily restricted thereto, but that the sugar solutions may be treated or contacted with the ion exchange materials in several different ways, such as suspending the exchange material in the solutions being treated and, if desired, agitating the mixture by any suitable means; for example, by mechanical agitation or by blowing gases through the solutions, which are inert with respect thereto. The sugar solutions may be contacted with the ion exchange materials at difierent temperatures, depending upon the desired amount of inversion-of the sucrose which occurs at higher temperatures. Usually the temperature of the sugar solutions is so regulated that it is maintained below 30 C. while in contact with the exchange materials. The inversion of sucrose at temperatures above 30 C. is

caused by the acidic nature of the cation exchange-treated sugar solutions. If the latter are not neutralized in a short time by treatment with anion exchange materials, a substantial amount of inversion will occur, particularly at elevated temperatures.

As previously hereinbefore mentioned, the cat ion exchange materials are operated in the hy- This is accomplished by treating the cation exchange material with dilute acids,

preferably mineral acids; for example, sulfuric or hydrochloric acids of about 540% by weight. The excess acid is removed from the cation exchange material by washing the same with waterv until the wash water is very slightly acidic or neutral. The cation exchange material then has the ability to adsorb inorganic cations which are present in the sugar solutions, as well as minor amounts of other positively charged materials present in the solutions. Among the cation exchange materials which can be used are those produced by the treatment of humic materials with sulfur compounds; for example, the resins produced by treating lignite with concentrated sulfuric acid. Other cation exchange materials which are applicable are those produced by treating aromatic hydroxy compounds-such as phenols, tannins, etc. with concentrated sulfuric acid in order to introduce sulfonic acid groups; also resins produced by the condensation of aromatic phenols with aldehydesfor example, formaldehyde-with or without the aid of I catalysts. ,The latter group of cation exchange resins may be further modified by treatment with 7 catedby the pH of the efliuent from the cation 8 sulfuric acid in order to introduce groups therein.

A variety of anion exchange materials are applicable to the instant novel process, and among these may be mentioned resins produced by the condensation oi aromatic amines with aldehydes-i'or example, formaldehyde; resins produced by condensation of diphenyl amines with aldehydes; resins produced by the condensation of a mixture 01' aromatic amines with mono or disaccharides, or an aldehyde; and others. These are reactivated or initially prepared for use .as ion exchange resins by treatment with dilute aqueous solutions of alkali metal hydroxides or carbonates; for example, sodium hydroxide, p0- tassium hydroxide, potassium carbonate, sodium carbonate, etc.

Since one of the objects of the present invention is to produce sugar syrups having an improved color, it is preferable to employ ion exchange materials which are carbonaceous in nature'and which have been stabilized by special treatment in order to prevent discoloration of the sugar-bearing solutions. However, it is to be understood that, in the event that color is not of primary importance insofar as the resultant product is concerned, ion exchange materials which have not been color-stabilized may be employed as well as those which are not essentially carbonaceous in character.

The sugar-bearing solutions which result from the Steffeniz'lng of molasses or other appropriate sugar-bearing solutions are treated with a sufflcient quantity of cation exchange resin operating in the hydrogen cycles so that the pH of the treated solution is not more than about 3.5. This may be accomplished by passing the sugar-bearing solutions through a column or bed of cation exchange resin operating in the hydrogen cycle until the pH of the last portion of treated solution is not more than 3.5., Alternatively, the sugar-bearing solutions maybe treated batchwise with cation exchange material which is substantially saturated with hydrogen ions in an amount sufficient to lower the pH of the solutions to not more than about 3.5. The resultant solution is thereafter treated with acid-adsorbing anion exsuli'onic acid change material in anamount sufficient to substantially remove the acid therefrom. It is preferable to maintain the temperature of the sugarbearing solutions below 30 C., particularly in the presence of the cation exchange material and subsequent to treatment therewith, in order to minimize the inversion of the sucrose. The inversion may be kept ata minimum by treating the sugar solutions .which have been subjected to the action of the cation exchange material directly with anion exchange material, in order to reduce to a minimum the time during which the sugar solutions are in an acidic condition. The total time allowed to elapse while the sugar solutions are in contact with the cation exchange the cation exchange treatment.

When the capacity of the respective ion exchangematerials to move either cations or anions has been substantially exhausted, which is indiexchanger rising above 8.5 and that from the anion exchanger falling below about 6.5, the flow of sugar solution is stopped and the residual sugar solution contained in the exchangers is eluted by passing water through the exchangers, combining the wash solutions with the sugarcontaining eiiiuents. The cation exchange material is then reactivated or ,saturated with hydrogen ions by treatment with acidic solutions as described above while the anion exchange material is reactivated with alkaline-solutions in the manner previously described.

The substantially de-ionized sugar whose pH is approximately neutral is concentrated by a suitable evaporation step (for example. by evaporation at about 50 C.) in a vacuum to produce a solution containing about 60-80% of dry solids. This concentration step results in the carbonization of small amounts of sugar which somewhat darkens the resultant solution. The color may be removed by the usual conven tional methods; for example, by employing decolorizing carbon in appropriate quantities. Normally, the amount of carbon required will be between about and 10% by weight of sugar present in the concentrated solution. The carbontreated sugar solution is water-white and substantially free from ash (inorganic impurities) as well as organic impurities. It may be described as a liquid sugar? which may be used 1 as the fullequivalent of liquid sugars prod :ced by dissolving refined granulated sugar in water. These liquid sugars or syrups are particularly applicable to the canning, confection, soft drink,

and similar industries, especially when they con- .metal ions and colloidal organic matter are preferably treated with cation and anion exchange materials as herein previously described, maintainlng said sugar solution in a dilute state. By dilute state is meant a sugar solution whose .viscosity is so regulated that it may be convensolution change material by heating said solutions prior to or during contact with the cation exchange a material. The amount of inversion maybe regmaterial which will precipitate substantially all of the calcium ions without adding metallic cations to the resultant sugar solution. For example, a reagent selected from the group consisting ofcarbon dioxide, sulfur dioxide. phosphorus pentoxide, and hydrates thereof is particularly useful in precipitating calcium as the carbonate, sulfite, or phosphate. These reagents may be added to the calcium saccharate slurry directly, or in the form of aqueous solutions thereof.

The process as herein disclosed may be augmented by carbon treatment of the sugar solutions at various stages in the process. For example, when employing a procedure involving the sequential treatment of sugar-containing solutions through a cation exchange bed operating in the hydrogen cycle, and then through an acidadsorbing anion exchange bed,a bed of activated iently passed through beds of cation and anion solutions are in contact with the cation exchange material and prior to their treatment with anion carbon or charcoal may be placed ahead of the ation exchange chambenbetween the cation ex-- change chamber and the anion exchange chamher, or following the anion chamber. Treatment of the sugar solutions with activated carbon or charcoal is particularly useful in the event that elevated temperatures (for example, about C. or higher) are employed in ion exchange treatment of the sugar solutions for purposes of sucrose inversion. g

In a preferred embodiment of the invention. 100 lbs. of molasses resultin from the successive crystallization of sugar from sugar beet solutions and containing about by weight of sucrose. together with about 30-35% by weight of non-.

sugar impurities, are diluted with water to produce a solution containing between 5 and 10% by weight of sucrose. This solution is cooled to a temperature below 15 C. and, while maintained at this temperature, there is added thereto a exchange material. In order to maintain operable conditions at such temperatures, itis preferable to employ sugar-containing solutions having less than 25% by weight of sucrose. However, the process is not necessarily limited thereto and under certain conditions-for example, depending upon the porosity or apparent density of the ion exchange materials-it is possible to employ'sugar-containing' solutions of a higher sucrose content. In the event'that a certain amount of inversion of sucrose is desired, the temperature of the sugar-containing solutions while in contact with the cation exchange material may be allowed to rise, due to the exothermic reaction resulting from the adsorption .of inorganic ions on the cation exchange resin. In some 1 instances it may be advantageous to artificially sufficient amount of finely powdered quick lime (09.0) to precipitate substantially all of the sucrose contained in the molasses. Conveniently,

' about 50 lbs. of lime are added per 100 lbs. oi

washed with water in order that the cake may be substantially free from residual or mother liquors; Thewashings are combined with the original filtrate. The resultant filtrate is heated to about C., which results in the precipitation of a further quantity of calcium saccharate. This precipitate contains from about 6-8% by weight of the sucrose originally present in the undiluted molasses solution previously mentioned. This precipitate is separated from the solution by solutions while. in contact with the cationex- 7 filtration, washed, and the two filter cakes are vent inversion of the sucrose values.

ll combined and slurried with water to produce a slurry containing about 14% by weight equivalent of sucrose. This slurry is heated to a temperature of about 85 C. and is then treated with carbon dioxide at atmospheric pressure. This operation results in the formation of a precipitate of calcium carbonate and a residual sugar solution containing about 14% by weight of sugar. The precipitated calcium carbonate is separated from the sugar solution by means of filtration and the filter cake is washed with water. The

calcium carbonate cake may be either discarded or may be subjected to a calcining procedure whereby a calcium carbonate is converted into quick lime, the latter being reused in the Steffen process or in the original treatment of diffusion juice. The residual sugar solution, which contains about 14% by weight of sucrose, is pale yellow in color and contains sugar of about 90% purity. This solution is fed into the top of a bed of Amberlite IR-lOO resin a phenol-formaldehyde-sulfonic acid resin) which contains about one cubic foot of said resin, the bed having a depth of about three to six feet, which is operated in the hydrogen cycle and is passedthrough the cation resin bed until the last treated portion of the eiiiuent has a pH of about 3.5. The temperature of the sugar-containing solution as fed to the cation exchanger is maintained below 30 0., preferably below 20 C., by means of suitable heat exchange apparatus, in order to pre- The first portion of the efliuent from the cation exchanger subjected to crystallization procedures whereby solid sugar is obtained therefrom, or it may be will have a pH of about 1.5, and the flow of sugar solution is continued until the pH of the last treated portion is about 3.5. It has been determined that; if the pH of the effluent rises sub v stantially above 3.5, leakage of cation impurities into the eiiiuent will occur due to saturation of the cation resin with Ca ion and other impurities.

In'order to keep the inversion of the sucrose in the effluent at a minimum, said eilluent must be passed promptly through a bed of acid-adsorbing anion exchange material. Therefore,

foot of said resin in a bed whose depth is be-. tween about 3 and about 6 feet. The flow of the eflluent from the ,cation is fed into the top 2,341,907). The exchanger bed will contain.

about one cubic foot of resin, the bed having a depth of about 3 to 6 feet. -The anion resin has been previously treated with an alkaline solution of the type previously described. The eiiiuent from the cation exchange unit is passed continuously through the acid-adsorbing anion exchange unit. Under normal operating conditions, the pH of the eiiiuent is not permitted to go below about 6.5; The eflluent' from the anion exchange unit is next concentrated by evapora tion, preferably under vacuum, to produce a solution containing between about 60 and about 80% by weight of solids. Thesugar contained in the resulting solution has a purity of about 95-07% and contains about 94-95% of the sucrose contained in the original diluted molasses solution. Usually the. color of the con-' eifluent is about neutral.

used directly as an equivalent of so-called "liquid sugars which are produced by dissolving refined granulated sugar in water.

The ion exchange materials used in the above process may be reactivated or regenerated after their ability to adsorb impurities has been substantially exhaustedkby eluting the exchangers counter-currently with water and passing a 5% by weight solution of sulfuric acid (or the equivalent thereof) through-the cation exchange material until it is substantially saturated with hydrogen ions, and passing a 5% by weight solution of caustic soda through the anion exchange. The" excess acid and alkaline reagents are removedfrom the respective resins by eluting with water until the eilluent from the exchangers is approximately neutral.

An invert sugar syrup may be prepared in accordance with the instant novel process by operating as follows: The saccharate cake prepared by'stefienizing 100 lbs. of beet molasses, as herein previously described, is slurried with about an equal quantity of 'watenheated to about C., and carbonated by passing carbon dioxide resultant mixture is acid to thymophthalein.

The resultant precipitate of calcium carbonate is 'separated from the sugar solution on a leaf illter and polished on a suction filter. ,The filtrate, containing between about 10 and about 20% by weight of sugar, is passed through a column of Amberlite IR-IOO resin, operating in the hydrogen cycle, containing about one cubic sugar solution through the resin exchange column is continued until the last portion of the treated solution is not more than about 3.5. Half of the eilluent from the cation column is passed directly into a column of Amerlite lift-4 resin containing aboutone cubic foot of said resin in a bed whose depth is between about 3 and about 6 feet. The remaining half of the eilluent'from the cation column is heated to about 70 C. for approximately 45 minutes, in order to invert a substantial amount of the sucrose values contained therein and, after cooling to about 30 C., is then passed through the same anion exchange column until the pH of the The separate eflluents are evaporated to about 60% sugar solids content in a 28 -inch vacuum, or they may be blended,

followed by an evaporation step, and the resultant syrups decolorized with activated carbon, using about 7% by weight of carbon for the inverted syrup and about 5% by weight of activated carbon for the sucrose solutions, based upon the sucrose content of said solutions. The resultant water-white syrups may be blended to obtain any desired amount of inversion, and the blended syrups evaporated to any desired dry solids content. "The resultant syrups are substantially ash free, analyzing between 0.00 and about 0.03% by weight of inorganic contaminants. These invert syrups are particularly adapted to the sugar requirements of the canning, baking, and confection industries.

While the above preferred embodiments of the instant novel process have set forth certain temperature requirements, sugar solids content of the solutions being treated with cation and anion exchange resins. and sugar solids content of the resultant products, it is to be understood that the process is not necessarily limited to such illustrations but that obviously extensions and modifications may be employed without departing from the scope of the invention.

Having thus fully described the nature and character of the invention, what is desired to be secured by Letters Patent is:

1. A process for the purification of sugar solution prepared by acidifying calcium saccharate which is produced by liming a sugar-bearing solution, which comprises subjecting the resultant sugar solution to the sequential action of cation exchange material operating in the hydrogen cycle and acid-adsorbing anion exchange material.

2. A process for the purification of sugar solution prepared by acidifying calcium saccharate which is produced by liming molasses, which com prises subjecting said sugar solution to the sequentialaction of cation exchange material operatin in the hydrogen cycle and acid-adsorbing anion exchange material.

3. A process for the purification of sugar solution prepared by acidifying calcium saccharate which is produced by liming sugar beet molasses,

which comprises sequentially treating said sugar solution at a temperature below 30 C. with cation exchange material operating in the hydrogen cycle and acid-adsorbing anion exchange material.

4. A process for the purification of sugar solution prepared by acidifying calcium saccharate which is produced by liming sugar beet molasses, which comprises sequentially treatin said sugar solution at a temperature below 30 C. with cation exchange material which is substantially saturated with hydrogen ions in an amount sufficient to give the solution a pH not greater than about 3.5, and thereafter treating the solution with acid-adsorbing anion exchange material in an amount sufficient to substantially completely remove the acid therefrom.

5. A process for the purification of sugar solution prepared by acidifying calcium saccharate which is produced by liming molasses, which 14 solution is not more than about 3.5, and passing the eiiluent through a bed of acid-adsorbing anion exchange material until the eflluent therefrom is about neutral.

8. A process for producing a concentrated sugar solution by acidifying a sugar solution prepared from calcium saccharate which is produced by liming sugar beet molasses, which comprises passing said sugar solution containing less than 25% by weight of sucrose at a temperature below C. through a bed of organic cation exchange resin operating in the hydrogen cycle until the pH of the last portion of treated solution is not more than about 3.5, passing the efliuent through a bed of acid-adsorbing organic anion exchange resin until the pH of the eiiiuent is about neutral, and concentrating the resultant solution to increase the sugar solids content.

9. A process for the recovery of sucrose from molasses, which comprises adding lime to the,

molasses in an amount sufficient to precipitate substantially all the sucrose as calcium saccha rate, separating the latter from residual liquors, admixing an aqueous slurry of said calcium saccharate with a reagent selected from the group consisting of carbon dioxide, sulfur dioxide, phosphorus pentoxide, and hydrates thereof, separating the resultant insoluble inorganic calcium compounds from the resultant sugar solution, passing the latter at a temperature below 30 C. through a bed of cation exchange material operating in the hydrogen cycle until the pH of the last portion of treated solution is about 3.5, and

' passing the effluent through a bed of acid-adsorbcomprises subjecting said sugar solution to the sequential action of a bed of cation exchange material operating in the hydrogen cycle and a bed of acid-adsorbing anion exchange material.

6. A process for the purification of sugar solution prepared by acidifying calcium saccharate which is produced by liming sugar beet molasses. which comprises passing said solution at a temperature below 30 C. through a bed of cation exchange material operating in the hydrogen cycle, and passing the eflluent through a bed of acid-adsorbing anion exchange material.

"I. A process for the purification of sugar solution prepared by acidifying calcium saccharate which is produced by liming sugar beet molasses, which comprises passing said solution at a temperature below 30 6. through a bed of cation exchange material operating in the hydrogen cycle until the pH of the last portion of treated ing cation exchange material until the eflluent therefrom is about neutral.

RALPH W. SHAFQR.

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

UNITED STATES PATENTS Number Name Date 1,402,615 Hughes Jan. 3, 1922 1,534,166 Dahlberg Apr. 21, 1925 2,375,164 Bennett et al May 1, 1945 2,375,165 Nees et al. May 1, 1945 2,388,195 vallez Oct. 30, 1945 2,388,222 Berhman Qct. 30, 1945 FOREIGN PATENTS Number Country Date 116,691 Australia Mar. 9, 1943 OTHER. REFERENCES Haagensen, Ion Exchange Applied to Sugar Juice Purifier," Sugar, April 1946, pp. 36-42 (see page 38) Sussman, Catalysis by Acid-Regenerated Cation Exchangers," Ind. and Eng. Chem, December 1946, pp. 1228-1230 (see especially pa e 38).

Ber. No. 359,575, Smit (A. P. C.) published May 11, 1943.

Claims

1. A PROCESS FOR THE PURIFICATION OF SUGAR SOLUTION PREPARED BY ACIDIFYING CALCIUM SACCHARATE WHICH IS PRODUCED BY LIMING A SUGAR-BEARING SOLUTION, WHICH COMPRISES SUBJECTING THE RESULTANT SUGAR SOLUTION TO THE SEQUENTIAL ACTION OF CATION EXCHANGE MATERIAL OPERATING IN THE HYDROGEN CYCLE AND ACID-ABSORBING ANION EXCHANGE MATERIAL.