RU2556894C1 - Method for integrated purification of molasses and its extraction from sucrose - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: method for integrated purification of molasses and its extraction from sucrose includes stages whereat molasses is diluted, reagents are added to it with further settlement of the generated non-sugar sediment; molasses is diluted with water or purified sugar juice until the content of dry substances is 20-50%; then reagents are introduced into the produced solution that are represented by a mixture of a mechanical coagulant, an acid agent, a non-anionic flocculant, a reagent accelerating the flocculation process, a decolourising reagent and a non-cationic flocculant; the solution is heated to 45-95°C and supplied into the decanter sump where it is maintained until sediment formation. Then the sediment is removed; the solution is filtered and delivered for electric dialysis purification to remove salts of alkaline and alkaline-earth metals. After such electric dialysis purification, the cleared solution is introduced into the process flow at the pre-defecation stage, saturation Stage 1, saturation Stage 2 or evaporation stage.

EFFECT: invention allows to ensure a high degree of molasses purification as well as the possibility of application at the stage of electric dialysis purification of any type anionic and cationic membranes.

3 cl, 1 tbl, 4 ex

Description

The invention relates to the sugar industry, namely: to integrated methods for the extraction of sucrose from thick semi-products of sugar production. It can be used to clean molasses and extract sucrose from it.

Molasses is a product of sugar production - an edema obtained by centrifuging massecuite in the last stage of crystallization, the separation of sugar from which directly by crystallization at a sugar factory based on existing technology is not economically feasible. The high sugar content in molasses (up to 50% by weight) has long been aroused the desire among manufacturers both in our country and abroad to extract this additional sugar. This led to the development of various methods for its desaccharification.

Methods for removing non-sugars (for example, in the form of various salts) from molasses using treatment with alcohol or using electrolysis have not received industrial application due to their high cost

Until the beginning of the 80s of the last century, sugar methods for desugaring molasses were widely used in practice. They are based on the fact that if the molasses solution is treated under appropriate conditions with alkaline earth metal oxides (calcium, strontium, barium), then insoluble compounds called sugars are formed. When filtering the stock solutions of the thus treated solution, sucrose in the form of sugars will remain in the precipitate on the filter, and non-sugar will be transferred to the filtrate. The resulting sugars are decomposed by carbon dioxide to form the corresponding alkaline earth salt and sugar solution. Then the sugar can be crystallized in pure form. The disadvantage of such methods is, in particular, that the resulting sugar has a high degree of contamination with salts of alkaline earth metals.

A known method of separating betaine and sugar fraction from molasses by passing molasses through a chromatographic column filled with sulfonated polystyrene divinylbenzene cation exchange resin in Na ⁺ form, followed by elution with water and fractional selection. One of the fractions, which is waste, is removed from the process and used as a feed concentrate, the other fraction is sugar and another is betaine, the remaining four fractions are returned to the system and combined with raw molasses (SU 1189334, B01D 15/04, 30.10. 1985).

The above process includes a sequence of several identical stages, therefore it is water and energy intensive and involves the formation of a large amount of waste. After each stage, the regeneration of the used ion-exchange resins is required, which is associated with the consumption of large volumes of inorganic alkalis and acids, and for this reason the above process is not environmentally friendly. In addition, the sucrose yield is quite low, since this method is aimed at isolating betaine from molasses.

A known method of producing sugar by crystallization from a viscous sugar-containing solution, involving the selection of sugar in the form of a crystalline shell on the cooled ribbed surface of the drums of roller molds [Matusevich L.N. Crystallization from solutions in the chemical industry. - M .: Chemistry, 1968, S. 188-191].

The disadvantage of this method is the low efficiency of the process, due to the small size of the interfacial surface: the ribbed surface of the drum is crystalline sugar.

A known method of producing sugar from molasses, which provides for its cooling to a supersaturated state, passing a stream of cooled supersaturated molasses in a vertical cylindrical mold through a suspended layer of a fine-grained nozzle with a temperature below the molasses temperature to crystallize sugar on the surface of the grains of the nozzle in the form of crystalline shells. This is followed by separation of the nozzle in the form of crystalline shells, separation of the nozzle from molasses at the end of crystallization, and dissolution of the crystalline shells with a solvent, and the nozzle is placed in a cylindrical chamber located in the mold with a diameter close to the diameter of the mold equipped with end gratings whose cell size is smaller than the nozzle size. Next, bring the camera with the nozzle into the low-frequency vibratory movement vertically. After crystallization, the crystalline shells are dissolved in the mold during the vibrational movement of the chamber with the nozzle (RU 2167941 C1, C13F 1/02, 05.27.2001).

The disadvantage of this method is its high cost, the complexity of the technological implementation and the low degree of purification of molasses. When the sucrose content in molasses below 35 wt.% Stops its adsorption on the surface of the nozzle. In addition, during adsorption on the surface of the nozzle, a large part of the impurities contained in molasses is captured by the sucrose molecules being captured, which leads to a decrease in the purity of the final product.

A known method of extracting sucrose from molasses, comprising mixing molasses with a solution of methanol, resulting in the formation of a single liquid phase, which is a solution saturated with sucrose. Separation of non-carbohydrate impurities is carried out by precipitation, sucrose crystallization occurs due to the supersaturation of the sucrose solution and the isolation of sucrose crystals (WO 0190422 A2, C13J 1/02, 11/29/2001).

The disadvantage of this method is the high resource intensity, the use of methanol and a large amount of waste.

A known method for the production of sugar syrup from sugar-containing raw materials (sugar beets or sugarcane), including grinding the latter, obtaining juice, ultrafiltration, ion-exchange purification, concentration of juice by reverse osmosis and evaporation to syrup. Before ultrafiltration, the juice is acidified to lower the pH, preheating it until coagulation of the proteins is achieved, followed by separation by filtration or centrifugation. Next, the juice is subjected to electrolysis using active electrodes, which give polyvalent ions upon dissolution and provide for coagulation of colloids with subsequent separation of the precipitate. In this case, the ultrafiltrate obtained is subjected to electrodialysis before ion exchange purification to demineralize it, and after it the sugar-containing solution is passed through a filter with a sorbent (RU 2114177 C1, C13F 3/00, 06/27/1998).

The disadvantage of this method is the complexity of the technical design and the fact that the purification of sugar juice using active electrodes is very long and energy-intensive, and therefore ineffective. The cleaning time consists of the time of dissolution of the electrode, the diffusion time of the active ion to the ion of the harmful salt and the chemical reaction of the formation of insoluble salt.

The closest analogue of the proposed method is a method for purifying molasses, comprising introducing into it a reagent precipitating non-sugar, and filtering to remove the precipitate of non-sugar. Before the introduction of the reagent, molasses is diluted with water to 40-50% solids and heated to a temperature of 55-65 ° C, while hydrogen peroxide is used as a reagent in an amount of 1.0-1.5 wt.% To the mass of molasses and, after filtering , 10-15% potassium permanganate solution is introduced into molasses in an amount of 1.0-1.5 wt.% to the mass of molasses for the formation of particles of manganese dioxide adsorbing non-sugar, followed by filtration (RU 2301266 C1, C13J 1/02, 06/20/2007).

The disadvantage of this method is that it does not provide sufficient separation of sugars from molasses in view of the presence in the molasses of alkali and alkaline earth metal salts such as potassium, sodium, magnesium, calcium, which interact with sucrose and interfere with its crystallization. Another disadvantage of this method is that it is not applicable to molasses of low quality with a low content of sucrose and a high content of calcium salts.

The objective of the proposed method is to increase the efficiency of the technological process of sugar production, ensuring the extraction of sugar from molasses without building a separate production for the processing of molasses and, as a result, reducing the cost of the process.

The technical result of the proposed invention is to provide a high degree of purification of molasses, as well as the possibility of using at the stage of electrodialysis purification of anionic and cationic membranes of any type.

The technical result is achieved due to the fact that a method is proposed for the complex purification of molasses and extraction of sucrose from it, in which molasses is diluted to 20-50% of solids with water or purified sugar-containing juice, reagents that discolor it and precipitate non-sugar are introduced into the solution, and precipitate formed sediment of non-sugars. Reagents are introduced into the diluted molasses solution, which is a mixture of an inorganic coagulant, an acid reagent, a non-anionic flocculant, a reagent that accelerates the flocculation process, a bleaching reagent and a non-cationic flocculant, heated to a temperature of 45-95 ° C and fed to a decanter in which it is maintained until a precipitate forms. Then the precipitate is removed, the solution is filtered and sent to electrodialysis to remove salts of alkali and alkaline earth metals, using anion-exchange and cation-exchange membranes as membranes, and any conductive materials as electrodes. After electrodialysis purification, the purified solution is returned to the process stream to the pre-defecation stage, or the 1st saturation stage, or the 2nd saturation stage, or the evaporation stage.

If necessary, before feeding the diluted molasses solution to the decanter, its pH is adjusted to 8.5-10 by adding milk of lime.

In industrial production, the process of obtaining sugar from sugar beets is a sequence of the following main stages. First, sugar beets are prepared: root crops are washed, cleaned of impurities and ground into shavings. Then loaded into a diffusion apparatus, where at a temperature of 70-75 ° C countercurrent water is supplied. In this case, from the fiber of beet chips, soluble substances are diffused into water with the formation of diffusion juice, which, in addition to sucrose, contains many other substances (non-sugars). Subsequent purification of diffusion juice is as follows. Initially, the juice goes through the stage of pre-defecation: it is processed with milk of lime with a gradual increase in pH to about 11.4. At this stage, neutralization reactions of the organic acids contained in the juice take place with calcium hydroxide, coagulation and precipitation of high molecular weight non-sugars in the form of pectins, proteins and protein degradation products, as well as the precipitation reaction of most of the anions of phosphoric, oxalic, acetic, citric, hydroxycitric, malic, tartaric acids and cations of magnesium, aluminum, iron. In addition, in an alkaline medium, high molecular weight non-sugars are precipitated, passing into a polyanionic form. But the decomposition reactions of a number of organic non-sugars contained in the diffusion juice, at the stage of pre-defecation, are just beginning, and higher alkalinity, temperature and duration of the process are necessary for their completion.

Immediately after the pre-defecation stage, the main defecation is carried out. At this stage, the decomposition of amides of acids, ammonium salts, reducing sugars, saponification of fats, additional precipitation of acid anions formed in the decomposition reactions, as well as the creation of excess lime necessary to obtain a sufficient amount of calcium carbonate particles at the subsequent stage of saturation are carried out.

As a result of the stages of pre-defecation and defecation, a water-insoluble precipitate is formed containing calcium carbonate, salts of organic acids and a coagulant consisting of high molecular weight non-sugars. Calcium, potassium and sodium hydroxides, salts of high molecular weight non-sugars, calcium sugar and sucrose remain dissolved in the defecated juice.

Next, the defecated juice with a flocculent precipitate passes through the next stage - the saturation stage, during which the juice is saturated with a saturation gas - carbon dioxide CO ₂ . At this stage, insoluble CaCO _{3 is} formed as a result of carbonation. The resulting positively charged CaCO ₃ particles serve as adsorption centers for negatively charged non-sugars - water-soluble decomposition products of reducing sugars, coloring materials, salts of high molecular weight non-sugars and organic acids, as well as coagulant polyanions of high molecular weight non-sugars. The interaction of polyanions with Ca cations on the surface of calcium carbonate particles displaces bound water from them and compacts the resulting aggregates, consisting of an organic shell containing mainly non-sugar and CaCO ₃ nuclei. This forms a solid precipitate, which is easily removed by mechanical filtration.

Next, filter the juice. As a result, the juice purified from the precipitate has approximately the following composition: solids 13-18 wt.%; sucrose 11-16 wt.%; nitrogenous substances 0.4-0.5 wt.%; ash 0.5-0.6 wt.%; calcium salts 0.015-0.025 wt.%. The purity of the juice is 89-92%, and the color 12-20 srvc. units

и небольшого количества $$S{O}_3^{2-}$$

. Сернистая кислота одновременно служит как антисептик и восстанавливает вещества, относящиеся к непредельным соединениям, и превращает их в бесцветные соединения. Сок при этом не очищается, т.к. обесцвеченные вещества остаются в растворе. Кроме того, сернистая кислота и ион $$HS{O}_3^{-}$$

блокируют карбонильные группы редуцирующих соединений (моносахаридов, триоз, продуктов их распада), препятствуя образованию красящих веществ. Это вызвано дегидратацией этих соединений с образованием непредельных соединений с двойной связью, превращающихся далее в присутствии гидросульфита натрия NaHSО₃ в сульфонаты.Next, the filtered juice goes through the sulfation stage (in cases where such a stage is at the sugar factory). Sulfation is the treatment of sugar solutions with sulfur dioxide SO ₂ . SO ₂ dissolved in water is in the form of a non-ionized sulfate hydrate H ₂ SO ₃ , ions $$HS{O}_3^{-}$$

and a small amount $$S{O}_3^{2-}$$

. Sulfuric acid simultaneously serves as an antiseptic and restores substances related to unsaturated compounds, and turns them into colorless compounds. The juice is not cleaned, because discolored substances remain in solution. In addition, sulphurous acid and ion $$HS{O}_3^{-}$$

block carbonyl groups of reducing compounds (monosaccharides, trioses, their decomposition products), preventing the formation of coloring substances. This is caused by the dehydration of these compounds with the formation of unsaturated compounds with a double bond, which are further converted in the presence of sodium hydrosulfite NaHSO ₃ into sulfonates.

The juice thus purified is sent to the evaporation chamber, where it evaporates to a sugar syrup containing 60-65% dry matter by evaporation of water.

The next step is the crystallization step. Its purpose is to isolate sugar dissolved in syrup in the form of crystals. Isolation of sucrose crystals is carried out in 2-3 stages. At the first stage, when the content of crystals in the massecuite, which is a mixture of sucrose crystals and intercrystalline liquid - molasses, reaches about 50 wt.%, The crystals are separated from the massecuite by centrifugation. In a subsequent step, the molasses isolated in the first step is again concentrated to a saturation and the remaining sucrose is crystallized. At the final stage of production, crystalline sugar and, as waste, molasses are obtained.

Molasses is a concentrated solution, in addition to sucrose, non-sugar, and, in particular, salts of alkali and alkaline earth metals, which prevent the crystallization of sucrose, are included.

Therefore, molasses, despite the high sugar content, is a waste of sugar production along with pulp and filter cake. It is used for other purposes. It is known that the amount of sucrose in molasses reaches 50 wt.% Or more. Considering the fact that 1 ton of sugar costs approximately 25,000-30000 rubles, and 1 ton of molasses - 2500-4000 rubles, the obvious advantage of creating a technology for the extraction of sucrose from molasses.

According to the developed method, the molasses obtained is pumped into a mixer, which also serves water or purified sugar-containing juice, to dilute molasses to 20-50% solids, which is necessary for further dissolution of the reagents in it. The adjustment of the pH of the diluted molasses is carried out with milk of lime to a pH of 8.5-10.

Inorganic coagulant, acidic reagent, non-anionic flocculant, a reagent accelerating the flocculation process, a bleaching reagent and a non-cationic flocculant are added to the resulting solution as reagents. This mixture, if necessary, is heated to a temperature of 45-95 ° C and served in the decanter decanter.

Inorganic coagulant is necessary for the adhesion of non-sugars and reduce their dispersion. As it can be used titanium or basic aluminum salts activated by multivalent anions of orthotitanic, polyphosphoric, silicic or sulfuric acids, aluminum oxalate, titanium, aluminum or iron sulfates, basic aluminum chloride in active form, their hydroxocomplexes and hydroxides.

An acidic reagent lowers the pH of the molasses solution and reacts with non-sugar complexes, activating them for coagulation. As it can be used orthophosphoric or polyphosphoric acid. Non-anionic and non-cationic flocculants are necessary for the coalescence of small particles formed during coagulation into flakes and for their further precipitation. As a non-anionic flocculant, it is recommended to use polycationites or polyampholytes in pure form or mixtures thereof, and polycationites or polyampholytes can be, for example, quaternary ammonium salts, polyepichlorohydrindimethylamines, polydiallyldimethylammonides, cationic and non-ionic polyacrylaminomethylene sulfenamides, polyacrylamide aminomethylenediamine, polyacrylaminethyl aminethyl aminomethylene-aminomethylene aminomethylene-aminomethylene-aminomethylene, Pure polyanionites or polyampholytes in pure form or mixtures thereof are recommended as non-cationic flocculants, moreover, nonionic, anionic polyacrylamides, sodium alginates, carboxymethyl cellulose, gelatin, casein, a mixture of aluminosilicate with organic modifiers can serve as polyanionites or polyampholytes.

The decolorizing reagent, being a strong oxidizing agent, decomposes non-sugar. As it is recommended to use organic or inorganic peroxides and hydroperoxides, in particular hydrogen peroxide or sulfur dioxide. Also, ozone can be used as such a reagent.

After mixing molasses with water or purified sugar juice and reagents, the solution is fed into the decanter decanter and kept in it until precipitation of non-sugars.

For the purpose of greater purification of molasses solution from non-sugars, an additional 10-15% solution of potassium permanganate in an amount of 0.5-2 wt.% To its mass can be added to it to form manganese dioxide adsorbing non-sugars, followed by filtration.

Next, electrodialysis purification of molasses solution is carried out from salts of alkali and alkaline earth metals, which, interacting with sucrose and holding it, do not allow it to further crystallize in a vacuum crystallizer. As membranes, anion-exchange and cation-exchange membranes of any type are used. This becomes possible due to preliminary reagent purification of molasses, as a result of which a significant part of high molecular weight non-sugars are removed from molasses, the presence of which in the solution makes it virtually impossible to conduct electrodialysis of such a solution, since membranes made using ion exchange resins quickly overgrow with high molecular weight compounds.

The flow rate of the molasses solution, which is subjected to electrodialysis treatment, is selected based on a given current density: with a decrease in current density, it is also advisable to reduce the flow rate.

It is permissible to use any conductive materials as electrodes.

The addition of reagents, decantation and electrodialysis treatment can be carried out one or more times. In the first cycle, the pH of the solution is adjusted with milk of lime to a value of 8.5-10. If the cycle is repeated if necessary, then the pH of the solution is adjusted with milk of lime to a value of 7.3-8.5 to completely decompose the complexes formed from alkaline earth metal salts and other impurities.

Regarding the repeated carrying out of complex purification of molasses (with reagents and electrodialysis), it is worth noting that the composition of molasses in sugar factories varies very widely depending on the quality of the raw material - sugar beets. Since it is almost impossible to predict the quality of molasses, since beets are raw materials, which, depending on the region and climate, digging time, shelf life, and many other factors, constantly change their composition, therefore, the decision to conduct repeated complex cleaning is carried out in the process of beet processing and depends on from the quality of cleaning.

After cleaning, the molasses solution is returned to the sugar production flow chart. In the event that, after cleaning, the molasses solution has a high degree of purification (the purity of the solution was 85-88%), it is mixed with sugar juice after the 1st saturation or before entering the evaporation chamber. If the degree of purification is lower (purity was 80-84%), the molasses solution is mixed with sugar juice before the saturation stage. If the degree of purification is low (purity less than 80%), the molasses solution is either mixed with sugar juice before the pre-defecation stage, or it passes the stage of reagent and electrochemical purification or only electrochemical purification of alkaline earth metal salts.

Example 1

In the production of sugar, molasses of the following composition was obtained, wt.%: Sucrose - 40.06, a mixture of glucose and fructose - 0.4, raffinose - 0.7, potassium ions - 3.3, calcium ions - 1.2, magnesium ions - 0.01, sodium ions - 1.1, organic acids - 2, 8, other non-sugar - 20.2, water - the rest. Thus, the solids content was 70 wt.%, Of which 41.16 wt.% Sugars, 28, 6 wt.% Non-sugars.

The original molasses was diluted with distilled and deionized water to 35% solids. The resulting molasses solution had the following composition, wt.%: Sucrose — 20.03, a mixture of glucose and fructose — 0.2, raffinose — 0.36, potassium ions — 1.68, calcium ions — 0.61, magnesium ions — 0.005 , sodium ions - 0.56, organic acids - 1.42, other non-sugar - 10.13, water - the rest, pH - 6.7. Thus, the sugar content was 20.59 wt.%, And non-sugars - 14.41 wt.%. The molasses solution was heated to a temperature of 74 ° C and its pH was adjusted by adding milk of lime to 9.0.

The following reagents were added to the resulting solution: aluminum sulfate (inorganic coagulant) 0.007 wt.% To the mass of molasses solution, phosphoric acid (acidic reagent) in an amount of 80 mg / l molasses solution, polycationite - polydiallyldimethylammonium chloride (non-anionic flocculant) 0.02 wt. % by weight of molasses solution, active silicic acid (a reagent that accelerates the process of flocculation of non-sugar particles) 0.015 wt.% by weight of molasses solution, potassium permanganate in an amount of 0.5 wt.% by weight of molasses solution, 30% hydrogen peroxide (decolorizing reagent r) in an amount of 0.8 wt.% by weight of molasses solution and anionic polyacrylamide (non-cationic flocculant) in an amount of 40 mg / l molasses solution. The solution was applied to a decanter decanter, in which it was kept for 2 hours 30 minutes. After that, the precipitate was removed mechanically, and the solution was sent for cleaning to the electrodialysis apparatus. Steel plates measuring 230 × 100 × 3 mm were used as electrodes.

The MK-40 heterogeneous membrane, which is a composite of KU-2 ion-exchange resin and polyethylene, was used as a cation exchange membrane. A heterogeneous MA-40 membrane, which is a composite of polystyrene crosslinked by divinylbenzene and polyethylene, was used as the anion exchange one. The set current density was 10 mA / cm ² . The molasses solution flow rate through the cell was 1 l / h.

The composition and properties of the obtained molasses are shown in table 1.

Example 2

The experiment was carried out analogously to example 1, however, as the cation exchange used sulfonation membrane MF-4SK. The membrane MA-40 was used as anion exchange. The set current density was 10 mA / cm ² . The molasses solution flow rate through the cell was 3 L / h.

Example 3

The experiment was carried out analogously to example 1, however, the MA-41 membrane was used as anion exchange. The set current density during electrodialysis cleaning was 50 mA / cm ² . The molasses solution flow rate through the cell was 5 l / h.

Example 4

The molasses solution obtained in Example 1 was heated to a temperature of 80 ° C, its pH was adjusted with milk of lime to 8.5, and the following reagents were added: sodium aluminate (inorganic coagulant) 0.011% by weight of molasses solution, hydrogen bromide (acid reagent) in an amount of 80 mg / liters of molasses solution, polyethylene oxide (non-anionic flocculant) 0.03% by weight of molasses solution, potassium permanganate in an amount of 1% by weight of molasses solution, hydrogen peroxide (bleaching reagent) in an amount of 0.8% by weight of molasses solution and anionic polyacrylamide (non-cationic flock Ulanta) in an amount of 40 mg / l molasses solution. Then they served in the decanter decanter, in which it was kept for 4 hours. After that, the precipitate was removed mechanically, and the solution was sent for cleaning to the electrodialysis apparatus. As the electrodes used titanium plates measuring 230 × 100 × 3 mm.

As a cation exchange, a homogeneous nafion-117 membrane was used, which is a copolymer of tetrafluoroethylene and perfluorinated sulfonated vinyl ether. The membrane MA-41I was used as anion exchange.

The set current density was 100 mA / cm ² . The molasses solution flow rate through the cell was 12 l / h.

The data obtained showed that the claimed method allows not only to perform general purification of molasses, but also to remove to a large extent molassogenic ions of alkaline (Na ⁺ , K ⁺ ) and alkaline earth metals (Ca ²⁺ ) that impede the release of sucrose due to crystallization. Based on experimental data, the possibility of using any cation-exchange and anion-exchange membranes as membranes in electrodialysis was confirmed.

Thus, the proposed method allows without significant capital costs and expansion of the technological scheme of the sugar factory to significantly increase the percentage of sucrose extraction and increase the environmental friendliness and profitability of sugar production.

Claims (3)

1. The method of complex purification of molasses and the extraction of sucrose from it, in which molasses is diluted, reagents are added to it, decolorizing and precipitating non-sugar, and then the precipitate formed of non-sugars is precipitated, characterized in that the molasses is diluted to 20-50% dry matter with water or purified sugar juice, reagents are introduced into the resulting solution, which are a mixture of an inorganic coagulant, an acid reagent, a non-anionic flocculant, a reagent that accelerates the flocculation process, a bleaching reagent, and a non-cationic flocculant, it is heated to a temperature of 45-95 ° C and fed to a decanter, in which it is kept until a precipitate is formed, then the precipitate is removed, the solution is filtered and sent to electrodialysis to remove salts of alkali and alkaline earth metals, using anion exchange and cation exchange membranes; after electrodialysis purification, the purified solution is introduced into the process stream at the pre-defecation stage, or at the 1st saturation stage, or at the 2nd saturation stage, or at the evaporation stage. 2. The method according to p. 1, characterized in that before feeding the diluted molasses solution to the decanter decanter, its pH is adjusted to 8.5-10 by adding milk of lime. 3. The method according to p. 1, characterized in that after electrodialysis purification reagents are added to the solution, which are a mixture of an inorganic coagulant, an acid reagent, a non-anionic flocculant, a reagent that accelerates the flocculation process, a bleaching reagent, and a non-cationic flocculant, the molasses solution being heated to temperature 30-60 ° C, adjust the pH to 7.8-8.5 and feed into the decanter decanter, in which it is kept until a precipitate is formed, after which the sediment is removed.