US628985A - Process of making lead sucrate. - Google Patents

Description

NlTED ra'rns FFICE,

cnoae KASSNER, or MUNSTER, GERMANY.

PROCESS OF MAKING LEAD SUCRATE.

SPECIFICATION forming part of Letters Patent No. 628,985, dated July 18, 1899. Application filed August 21,1395. Serial No. 559,987. (No specimens.)

To all whom, it may concern.-

Be it known that I, GEORG KASSNER, professor, a subject of theGerman Emperor, and a resident of Munster, in the Province of WVestphalia and German Empire, have invented a certain new and useful Improved Process of Manufacture of Sugar, (patented in Great Britain, No.14,925, August 7, 1895,) of which the following is a specification.

The best process that has been employed hitherto for extracting cane sugar from sacchariferous solutions in the condition of a compound dissolving with difficulty is unquestionably that which consists in turning to account the property which is possessed by barium hydrate and strontium hydrate of combining with cane sugar. This method of utilizing the alkaline earths is, however, attended with three somewhat serious drawbacks, which reside in the very nature of the chemical agents named, and therefore may be neither obviated nor preventedviz., first, that the hydrate of strontium and barium hydrate will only separate cane sugar and raffinose and have a destructive action upon the various kinds of glucose, so that the extraction and separation for m anufacturing or commercial purposes of glucose on the one hand andof cane sugar on the other, as well as the extraction of the soluble salts contained in the juices of plants, become impracticable; second, that the strontium or barium sucrates are by far too readily soluble to admit of the foreign salts and coloring agents being separated therefrom bylixiviation, and, third,that the process of regeneration of the alkaline earths from the carbonates formed in the saturation stage requires too high temperatures for its performance, thereby adding Very considerable to the cost of the fuel consumed, while the furnaces which have to be used in carrying it out are liable to speedy destruction.

Now the process forming the subject of this invention is free from the defects above enumerated. It involves the employment of OX- ide of lead as a separating agent and is based upon the fact (which is well known to scientists) that it yields combinations of sugar and lead which are only soluble with difliculty. This, as stated, was merely a scientific discovery, as was also the circumstance which was first pointed out by Dubrunfaut-that sucrate of lead forms at ordinary temperature, and that it does so gradually, when litharge is allowed to stand at rest together with a pure solution of sugar. These scientific data,taken by themselves, were of no practical value and totally unfit to render any service to the trade, lacking, as they did, various features essential to success; and, in truth, it has hitherto occurred to no one to attempt to render Du brunfauts discovery serviceable for the trade or market, for extracting sugar from molasses or from any'mixture embodying foreign or impure substances, much less for separating the several kinds of sugar from each other, all this having been impracticable for Want of experience and because the behavior of lead in the different cases alluded to was unknown. I therefore have assumed the task of ascertaining the requirements to be fulfilled, which, not having been known before, might not be complied with.

I have after numerous trials, partly unsuccessful, at length succeeded in devising a really serviceable process, and, what is better still, in imparting to it the character of a continuous circular process, (or what is sometimes called a cycle,) wherein all the materials or agents employed are brought back to their starting-points after having performed their respective duties.

The most important conditions upon which the successful performance of the process depends are as follows:

a. The oxide of lead employed should be in the form of a powder which must be as fine and as uniform as possible.

1). Between the oxide of lead and the sugar there should be a predetermined relation of weight, especially when the process is carried on on rational ].inesthat is to say, for manufacturing or commercial purposes.

0. The concentration of the solution should be so proportionedthat the resulting combination of oxide of lead with the sugar can be but slowly precipitated at the bottom of the vessel.

01. Care should be taken to insure as close and as uniform a contact as possible between the heavy insoluble oxide of lead and the solution of sugar. This may be done, for example, by keeping the mixture in violent motion or briskly stirring it until sucrate begins to form.

6. The separation of the sucrates should be so conducted that the various sorts of sugar may be collected separately. This last-mentioned result will be obtained by taking advantage of a fact which I have also had occasion to ascertain in the course of my labors namely, that where a mixture of various species of sugar is dealt with the oxide of lead will cause the glucose (levulose and dextrose) in its various forms to be precipitated first, while the cane sugar will not precipitate until afterward. The glucosate being precipitated first and the sucrate afterward, the former is removed mechanically before the precipitation of the latter. Attention should also be paid to the desideratum of obtaining the sucrate in' the condition of agglomerated lumps having the shape of small balls or warts and consisting of radially-disposed fine needle-shaped spherical aggregates of crystals or spherical masses of needleshaped crystals, inasmuch as it will be found that these spherical crystals are capable of being more readily washed out or extracted by lixiviation than would be the case if the glucosate were in a different form. The non-sugar bodies form lead salts which with a proper proportion of precipitant are precipitated simultaneously and jointly with the lead sucrate. The precipitate which is formed consists, therefore, of a mixture of the lead compounds of the non-sugar bodies and of sucrate. When this mixture suspended in water is treated with carbonic acid, only the lead sucrate becomes affected, while the combination of the non-sugars with lead is not affected by the carbonic acid. \Vhen decomposition of the lead compounds of non-sugars occurs, it only takes place after the lead sucrate has been decomposed. Most of these observa tions are entirely novel, and by putting them to practical use the improved process which forms the subject of this invention is carried out somewhat on the following lines:

Oxide of lead or hydrated oxide of lead, or mixtures containing oxide of lead, either hydrated or not and either in a complete or in a nascent form, are triturated with waterand uniformly stirred until they form a thin semiliquid mass. Among such mixtures equivalent to oxide of lead, and therefore it to be used as substances therefor, combinations or compounds of lead-salts with caustic alkalis or alkaline earths may be mentioned by way of example. After this trituration stage the sacchariferous solution (such as a solution of molasses, beetroot juice, or the like) which is to be precipitated and which has preferably been freed beforehand from such substances as will precipitate under the action of milk of lime (lime water) or by lead-acetate (neutral or basic) is added while being kept in a continual state of agitation by stirring. The

stirring should be so vigorous and the concentration of thesacohariferous juices should be so high that the oxide of lead may not readily go down to the bottom. Its descent must in fact be uniform in all parts of the mixture, inasmuch as it is most important for the purposes of sugar extraction and puri fication that there should be formed in as many points as possible centers of crystallization, lest the proper relation or proportion of the respective atomic weights of lead and sugar should be disturbed While the oxide of lead is collecting at the bottom, for if that precaution were not taken the oxide of lead might by being covered over with insoluble agglomerations or by becoming itself baked into a lump be withheld from the proper reaction, with the resultthat the precipitation of sugar would be, technically speaking, in-

complete, or the intimate contact of the sacchariferous solution with the oxide of lead, which is such an indispensable condition for the formation and separation of the saccharate, be effected by passing the sacohariferous liquids through oxide of lead. It is, however, most important that in producing the mixture directly by stirring awell-defined relation should be maintained between the oxide of lead and sugar, inasmuch as if the proportion of lead should be too small the sugar would remain unse'parated, while, on the other hand, too liberal an amount of lead would unduly add to-the difficulty of lixiviation and necessitate the consumption of too large a quantity of carbonic acid in the subsequent separation stage. The proper proportion, for example, may be to every one molecule of cane sugar a little over two molecules of oxide of lead and to everyone molecule of dextrose or inverted sugar, say, from about one and one-half to two molecules of oxide of leadt'. e., for about three hundred and forty-two parts in weight of cane sugar there are taken at least four hundred and forty-six parts of oxide of lead, and for one hundred and eighty parts in weight of glucose or the mixture of dextrose with levulose called inverted sugar there are taken from three hundred and thirty-four to four hundred and forty-six parts of oxide of lead. If instead of the oxide of lead a compound of lead is used, the equivalents of the abovenamed proportions will be employed. While stirring the mixture to make it thorough it should be slowly heated. Under the joint inliuence of these several factors a chemical combination or binding action will in a short time set in, the mixture beginning to solidify when this pointis about to be reached. The stirring is then continued until the mixture turns stiff by the formed sucrate, so that the heavy oxide of lead remains in suspension, though the stirring has ceased. In this man ner the oxide of lead not combined as sucrate may act on the sugar not converted into sucrate and form new amounts of the latter. As

soon as the formation of sucrate has begun 'sugar solution.

the stirring is discontinued, becausethe aggregates of crystals are formed in the best way if the mass reposes.

If it is intended to separate the cane sugar from the glucose, (dextrose and laevulose,) one adds at first the amount of oxide of lead equivalent to the glucose-4'. 8., for one molecule of glucose oneand one-half to two molecules of oxide of lead or for one hundred and eighty parts in weight of glucose three hundred and thirty-four to four hundred and forty-six parts in weight of oxide of lead. Then the glucosale is formed by stirring and heating the mass. The formed gl ucosate will be separated mechanically from the solution of sugar, and after standing at rest the solution contains, essentially, cane sugar without any glucose. After the separation of the glucosate the cane sugar will be converted into the sucrate by further addition of oxide of lead.

The compound of sugar and leade. 57., a combination of cane sugar and lead, a (30111- bination of glucose and lead, and one of the mixtures of dextrose and glucose called inverted sugar and lead or the like, or the mixtures of these combinationsobtained in the manner above described may be freed from the parts which have remained in a liquid state or which are soluble in water by filterin g or otherwise and then washing theinwith water or submitting them to the dialytic or diffusion process. The liquid separated in the first instance and not yet diluted with water in the treatment of molasses forms a valuable (because comparatively concentrated) solution of salt, with which little or no sugar is mixed; but should it be desired to obtain even these slight admixtures of sugar, if any, the salt solution need only be treated with further quantities of oxide of lead, which will lead to the extraction of the last remnants of sugar just referred to. The sucrate, having been carefully washed or lixiviated, when it is capable of any amount of further purification, will dissolve, but with great difficulty. I have found, indeed, that in the case of compounds of cane sugar and lead the relation is as one to eleven thousand parts of water. This sucrate then is triturated and treated with carbonicacid or gases containing carbonic acid (the saturation gases) until it is entirely decomposed. There forms an insoluble, mostly basic, carbonate of lead (white lead) and free sugar, the solution of which is separated from the salt of lead by filtration or the like and then further treated with a view to obtaining a marketable product. The lead is eliminated in toto by this process, so that not the slightest trace of it will be found in a carefully-filtered Besides, a reliable means of tracing the presence of and expelling any remnants of lead is afforded by sulphureted hydrogen and the corresponding sulphur compounds if it should happen that the operation has not been conducted with sufficient care to eliminate the lead in the first instance.

The muddy deposit resulting from saturation, from which the sugar has been extracted, mainly consists of basic carbonate of lead. This is then introduced into regenerating-fu rnaces, in which, by being slowly heated, it is reconverted into oxide of lead. By keeping the air out during the first heating stage and, if desired, by conducting a current of steam through the material heated there will only be produced in the first instance pure-1'. e., concentrated-carbonic acid, which will re turn to its proper place in the cycle of opera tions. After expelling the carbonic acid air may be admitted to the charge under treatmen 1;, the oxygen of which air will assist the regenerating action of the oxide of lead',while the organic admixtures of lead (the non-sacchariferous substances) will be entirely burned.

The advantage which the employment of the sugar-extracting process above described otters over all other existing processes resides in the fact that the carbonic acid contained in the mud collected in the saturation stage may be readily recovered in a high degree of.

concentration, seeing that basic carbonate of lead will decompose at temperatures not exceeding 250 centigrade or thereabout. Thus the heat required for highly-concentrated carbonic acid is obtained, which returns to its place in the cycle of operations, a result which it has not been possible to obtain in any of the extracting processes hitherto known. Superficial observers might raise this objection to the process herein describedthat in its performance a poisonous substance is made use of and that consequently the risk of incompletely separating it from the product of daily consumption would always remain attached to it; but this is a difficulty which the present state of industry enables to be very readily disposed of,'for it is one of the triumphs of modern science that it permits the most noxious or dangerous substances to be handied with the greatest ease and with a perfect avoidance of any danger being involved in the use or consumption of the final product.

Nothing, indeed, is easier than the entire elimination of any lead there may be still contained in the aqueous solutions. Such lead may, as a matter of fact, be separated with far greater facility than the (also poisonous) baryta, which, as is Well known, is an important factor in the sugar-extracting process known as the baryta saccharification process. Besides, as before stated, sulphureted hydrogen forms an excellent means for testing the product as to its absolute freedom from lead-a means which will be as readily available to the manufacturer as to the authorities and, indeed, to the consumers themselves.

I am aware that in the German patent of A. lVohl, No. 85,042, there is described a method of obtaining the sucrate of lead. My present invention, however, involves a particular process for manufacturing such com pound and the corresponding lead compounds of other sorts of su gar'for instance, glucosein a liquid containing several sorts of sugar.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is vto he performed, I declare that WhatI claim is- 1. The process of treating saccharine solutions, containing levulose, dextrose and cane sugar which consists in adding a lead salt and earth alkali to the solution and agitating it, whereby lead h'ydrate is formed in the mixture,precipitating the levulose and dextrose, removing these precipitates, allowing the remaining solution to stand until the sucrate crystallizes, and removing the sucrate.

2. The process of treating saccharine solutions, containing levulose, dextrose and cane sugar, which consists in adding a mixture of a lead salt with an alkali in about the pro portions specified and stirring the mixture,

wherehylead oxide is formed in the mixture, precipitating the levulose and dextrose, removing these precipitates, allowing the remaining solution to stand until the sucrate crystallizes, and removing the sucrate.

The process of treating saccharine solutions, containing levulose, dextrose and cane sugar which consists in adding a mixture of a lead salt with an alkaline earth in about the proportions specified and stirring the mixture whereby lead hydrate is formed in the mixture, precipitating the levulose and dextrose, removing these precipitates, allowing the remaining solution to stand until the sucrate crystallizes, and removing the sucrate.

Signed at Cologne, Germany, this 8th day of August, 1895.

GEORG KASSNER. Witnesses:

MARIA NAGEL, Torn WARNER.