WO2017042601A1

WO2017042601A1 - A process for sugar extraction from sugar juices by removing impurities from raw sugar juices

Info

Publication number: WO2017042601A1
Application number: PCT/IB2015/001582
Authority: WO
Inventors: Pradeep MATHUR
Original assignee: Mathur Pradeep
Priority date: 2015-09-11
Filing date: 2015-09-11
Publication date: 2017-03-16

Abstract

The present invention related to the process for sugar extraction from sugar juices by removing impurities from raw sugar juices comprising clarification of raw sugar juice in electro-coagulation skid or continuous pipeline, removal of floe, addition of collected molasses to raw sugar juice, re-clarification and/or clarification of raw juice-molasses mixture and collecting clear sugar juice. In the present process optionally the electro- coagulated sugar juice alone or in combination with molasses is treated further with multiple stages of electro-coagulation. The process allows producing white sugar below 45 ICUMSA directly from juice at economical cost eliminating the intermediate step of producing raw sugar..

Description

A PROCESS FOR SUGAR EXTRACTION FROM SUGAR JUICES BY REMOVING IMPURITIES FROM RAW SUGAR JUICES

FILED OF INVENTION:

[001] The present invention relates to a process for sugar extraction from sugar juices by removing impurities from raw sugar juices. More particularly the present invention relates to single stage extraction process to remove impurities/colorants/heavy metals/non sugar nutrients from raw sugar juice/syrup/melt. The invention clarifies the raw/mixed juice to near water clarity by removing all impurities prior to or after the heat treatment or any chemical treatment given to the juice, thus ensuring removal of all possible colour deterioration elements.

BACKGROUND OF THE INVENTION AND PRIOR ART

[002] In conventional method, clarification is defined as the separation of solids from sugar liquid. Raw juice is a solution of sucrose mixed with a variety of insoluble and suspended matter such as bagacillo, soil, sand, clay, starch, waxes, fats and gums. It also contains soluble impurities such as proteins, glucose, fructose, oligosaccharides, polysaccharides, organic acids, amino acids, colorants etc. Inorganic materials in sugar cane juice are mainly

Ca, P, Mg, Na, K, Si, S, Al and CI ions. Organic non-sucrose materials include organic acids, nitrogen-containing compounds and colorants. The sugar colorants are very complex mixture of organic compounds from various sources. They can be categorized into two main types, natural colorants resulting from the stevia/cane/beet plant and those developed during the juice processing.

[003] The fundamental purpose of sugar cane/Beet juice/syrup/molasses removing impurities in it is to produce, Stevia/Cane/Beet juice/syrup with the lowest concentration of insoluble and soluble impurities to achieve maximum extraction of sugar and further to separate and concentrate the non-sugar nutrients as micronutrients. [004] Clarification affects juice filterability, evaporator heat transfer coefficients, sucrose crystallization and the quality and quantity of sugar produced. It therefore affects the colour, crystal morphology, crystal content, ash and polysaccharide content of sugar.

[005] US 20090126720 Al discloses an invention which comprises a sugar cane juice clarification process comprising at least the steps of addition of lime; addition of anionic inorganic colloid, and separation of the resulting sugar cane juice.

[006] US 6132625 discloses a process to clarify water streams containing bio solids resulting from processing food and organic residues, which comprises contact of the stream with an anionic colloid, which may be a silicate micro gel, and an organic polymer to flocculate the bio solids.

[007] US 6228178 describe a process for producing white sugar with nano-filtration membranes. These membranes have very small pores, and therefore remove a high proportion of impurities from the juice. However, the flow through the membranes is slow because of the small pore size, requiring large membrane surfaces and significant pumping, capital, and operating costs. Because dissolved inorganic impurities are not removed by filtration, the quantity of molasses produced and the resulting sugar loss in molasses are little affected.

[008] WO 00/60128 describes a process employing two stages of ion exchange following membrane separation. The first stage, using a strong acid cationic resin, removes cations from the juice. The low pH requires cooling the juice to a low temperature, about 10 C, to prevent loss of sucrose due to acid inversion. Then follows a weak base anion exchange to remove anions. The bulk of the inorganic species and a large proportion of colour compounds are removed by the ion exchange steps. However, further decolourization is required, using a strong anion exchange in chloride form to reduce the colour sufficiently that white sugar may be crystallized.

[009] GB280321 relates to the improved process and apparatus for separating and purifying electrically diluted or undiluted molasses and sugar juice by electrolysis. The process involves two phases. In first phase the sugar solution is brought in contact with cathode and water is brought in contact with anode to eliminate the acid increase alkalinity. In second phase the sugar solution is brought in contact with anode and water is brought in contact with cathode to eliminate the salt. The process eliminates acid and salt from the molasses.

[0010] US1256758 discloses the process of refining sugar. The process relates to an electrolytic process for removal of acids, bases of salts from solution of sugar for increasing the purity of sugar solution and facilitating further utilization. Sugar solution, is treated under electrolytic process, due to which the impurities in the solution are made susceptible to pass through porous partitions to make in contact with anode and cathode electrodes being immersed in a stream of fresh water. Said electrodes, on contact with the impurities in the sugar solution remove and clear it.

[001 1] GB302375 discloses method of purifying sugar. The invention provides electrolytic and osmotic methods of coagulating, precipitating and further separating impurities in starch converted dextrose solutions. An apparatus which is an electrolyte cell with two compartments separated by a diaphragm. Further, the process remove impurities from starch converted dextrose solutions.

[0012] US5281279 relates to the process for producing refined sugar from raw juice. The process for producing refined sugar from cane/beet raw juice which bypasses the traditional manufacturing of intermediate product called raw sugar. Raw juice is treated with a flocculent.

[0013] Therefore it is desirable to have a simple, efficient and economical electro- coagulation/electrolysis clarification process which removes excess impurities and minimizes colour formation/reduces turbidity in raw sugar juice using simple equipment, simple methodology and just electricity instead of expensive chemical reagents.

OBJECT OF INVENTION

[0014] The main object of the present invention is to provide a process for sugar extraction from sugar juices by removing impurities from raw sugar juices. [0015] Another object of the present invention is to achieve higher extraction of sugar from molasses and to reduce sucrose losses in molasses and ease in skimming non-sugar nutrient to make enriched micronutrient mixture from the clarified sugar juice.

[0016] Further object of the present invention is to produce full refined sugar below 45 ICUMSA from raw sugar syrups and/or from clarified raw sugar juices, and saving steam in the process.

[0017] Yet another object of the present invention is to increase sugar production by as low as 8% extra sugar production to as high as 25% higher sugar production from the clarified sugar juice as compared to conventional method.

[0018] Another object of the present invention is to remove impurities at raw juice and syrup stage, which helps in avoiding the deterioration of impurities in the heated process of sugar recovery and allowing a single stage full sugar recovery process.

[0019] Yet another object of the present invention is to sugar mills to completely do away with any lime process, saving manpower, allow hassle free production, remove requirement of bagasse in clarification and minimize scalation problems in machinery.

[0020] Further object of the present invention is to removes the smallest colloidal particles because the applied electric field sets them in faster motion, thereby facilitating the coagulation and also gas bubbles produced during electrolysis carry the pollutant to the top of the juice solution where it can be more easily concentrated, collected and removed.

[0021 ] Another object of the present invention is to eliminate pH adjustment is unnecessary since EC performs well in a large pH range and individual treatment cells are easily replaced without the need for unit shutdown.

[0022] Further object of the present invention is to provide easily expandable modular construction, continuous noiseless operation, minimal operator attentions, low operating cost, low power requirement, low maintenance and provide consistent and reliable results. SUMMARY OF THE INVENTION

[0023] The present invention related to a process for sugar extraction from sugar juices by removing impurities from raw sugar juices. The process for removing impurities from sugar juices comprises clarification of raw sugar juice in electro-coagulation skid or continuous pipeline, removal of floe, addition of collected molasses to raw sugar juice, re-clarification and collecting clear sugar juice. In the present process optionally the electro-coagulated sugar juice is treated further with electro-coagulation. In the present invention mixed stevia/cane juice/sugar beet juice, syrup or clarified sugar cane juice or clarified sugar beet juice, raw sugar melt, molasses added to raw sugarcane/ sugar beet juice/syrup/melt are used as raw sugar juice.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The nature of the invention and the manner in which it is performed is clearly described in the specification. The invention has various components and they are clearly described in the following pages of the complete specification.

[0025] The invention refers to process to achieve higher sugar extraction by removal of undesirable impurities, colorants, heavy metals, non-sugar nutrients and reduce the turbidity in the medium and adding generated molasses to raw juice/syrup/melt for re-clarification thus allowing a much higher extraction of sugar by electrolysis referred as electrocoagulation (EC). Since a large proportion of the impurities are removed by this process, the amount of molasses and consequently the loss of sugar in molasses are substantially reduced thereby achieving higher sugar extraction than the conventional sugar processing methods. The process can also achieve zero loss of sucrose in molasses.

[0026] The present invention relates to a process for sugar extraction from sugar juices by removing impurities from raw juice/syrup/melt comprises following steps:

(a) The raw sugar juice is clarified by the electro-coagulation to remove all impurities.

(b) The floe is removed.

(c) The juice obtained in step (b) is re-clarified. (d) The molasses is collected and added to raw sugar juice and clarified by electrocoagulation to remove impurities and reduce sucrose losses in molasses.

(e) Again the floe is removed.

(f) The clear juice obtained in step (e) is re-clarified.

The present invention optionally comprises following steps:

(g) The primary electro-coagulation treated raw juice or mixture of molasses and raw sugar juice is passed through a secondary electro-coagulation system.

(b) The floe is removed.

(c) The juice obtained in step (c) is re-clarified.

The mu ltiple stages of electro-coagulation is done if more clarification is needed.

[0027] The non-sugar nutrients from the electro-coagulation treated sugar solutions alone and/or with added molasses are skimmed and further dried to obtain an enriched micronutrient formulation.

[0028] Sludge dewatering is done to remove water as much water possible from the sludge by applying any common dewatering filtration method. The sludge cake shall be used as high value fertilizer or feed/food grade minerals. In addition, it is also be used as a juice extract for the taste profile to replicate.

[0029] In the present invention mixed stevia/cane juice/sugar beet juice, syrup or clarified sugar cane juice or clarified sugar beet juice, raw sugar melt, molasses added to raw sugarcane/ sugar beet juice/syrup/melt, lime clarified juice and diluted juice are used as raw sugar juice.

[0030] In the present invention the electro-coagulation is done either batch wise or continuous pipeline for a short interval at low intensity current.

[0031] The floe formed by in the process is larger and more stable and so can be easily separated by conventional floe removal methods like dissolved air flocculation (DAF) system and/or ion exchange methodology and/or membrane filtration and/or activated granular columns and/or organic/inorganic polymers and/or powder activated carbon based filtration or any other floe removal system, not limiting the type of floe removal process to be used subsequent to invented process. The heavy metals and other impurities are removed to obtain clear syrups from any syrups contamination in the dextrose solutions, sugar solutions and molasses.

[0032] The process for removing impurities from raw sugar juice is more particularly defined with help of an apparatus for electro-coagulation. An apparatus for electrocoagulation includes electro-coagulation feed tank, electro-coagulation feed pump, electrocoagulation skid and electro-coagulation reactor.

[0033] An electro-coagulation/electrolysis reactor is provided for treating raw sugar juice single and/or in combination with molasses added to it and removing impurities there from. There are multiple charged plates located parallel to one another within the housing. Adjacent plates are typically oppositely charged and raw sugar juice and/molasses will pass between the plates as it flows through the reactor. The electric field between the plates will help encourage coagulation of impurities in the form of floes, which may be removed from the electro-coagulation skid by any floe removal methods.

[0034] The set up requires a DC power source having an insulation support enclosure with positive and negative electrode plates disposed thereon. The electrode plates are insulated for each other but remain in direct contact with the sugarcane juice as it flows between the electrodes. The DC power supply induces opposite charges on alternate electrodes thereby generating an electric field between adjacent electrodes to cause the electrodes to ionize and go into solution for interaction with the impurities in the cane juice as it flows through the reactor. It also requires a resistance box to regulate the current density and a multimeter to read the current values. The conductive metal plates are commonly known as 'sacrificial electrodes'. The 'sacrificial anode' lowers the dissolution potential of the anode and minimizes the passivation of the cathode. The sacrificial electrodes may be made up of the same or of different materials as the anode. Each pair of 'sacrificial electrodes' is internally connected with each other, and has no interconnections with the outer electrodes. Thus, during electrolysis, the positive side undergoes anodic reactions, while on the negative side, cathodic reaction is encountered. Consumable metal plates, such as iron, steel or aluminium, are usually used as sacrificial electrodes to continuously produce ions in the system. The released ions neutralize the charges of the particles and thereby initiate coagulation. [0035] Coagulation and flocculation occur in successive steps intended to overcome the forces stabilizing the suspended particles, allowing particle collision and growth of floe and then removed by conventional methods. In the electro-coagulation process, an electric field is applied to the medium for a very short time, and the treated dispersion transferred to an integrated clarifier system where the juice-contaminant mixture separates into a floating layer, a mineral-rich sediment, and medium.

[0036] Herein, aluminium/iron ions are released from the anodes, inducing coagulation, and hydrogen bubbles are generated at the metal cathodes, enabling flotation of the floe.

[0037] The main reactions occurring at the anode and cathode in electro-coagulation process when aluminium is used as electrode material is as follows.

At anode:

Al→Al ³⁺ + 3e- (1) 2H₂0→0₂ + 4H⁺+ 4e^" (2)

In Solution:

Al³⁺+ 3H₂0→A1 (OH) ₃(s) + 3H ⁺ (g) (3) At cathode: 2H₂0 + 2e^"→ H 2 + 20H^* (4)

Overall reaction: 2Al(s) + 6H₂0 (1)→2A1 (OH) ₃(s) + 3H ₂(g) (5)

The main reactions occurring at the anode and cathode in electro-coagulation process when iron is used as electrode material is as follows.

At anode:

4Fe(s)→ 4Fe⁺² + 8e (1) 4Fe⁺²(aq) + 10H₂O (1) + 0₂ (aq)→ 4Fe (OH)₃(aq) + 8H+ (aq) (2) At cathode:

8H+ (aq) + 8e→ 4¾ (g) (3) Overall: 4Fe(s) + 10 H₂0 (1) + 0₂ (aq)→ 4Fe (OH)₃(aq) + 4H₂ (g) (4)

[0038] The invention is illustrated more in detail in the following examples. The examples describe and demonstrate embodiments within the scope of the present invention. These examples are given solely for the purpose of illustration and are not to be construed as limitations of the present invention, as many variations thereof are possible without departing from the and scope.

Examples

Example I

[0039] Collected molasses was added to raw cane juice before liming and subjected to single

EC clarification followed by double EC clarification.

Result:

Table 1 shows comparison between the process of the present invention with the conventional process.

Attribute Conventional Example 1 Example 2

method Single EC Double EC Example A

PH 5.8 7.8 8.1

Colour ICUMSA at 6161.86 1150.88 785.74

420nm UI(Method -7)

Colour ICUMSA at 1985.03 277.79 82.71

560nm UI(Method -7)

Turbidity at 900 nm 155.25 1.65 0.75 Conclusion:

[0040] The improvement in color is observed when the process of the present invention is applied. The secondary EC treatment gives better results than single/primary EC treatment. The percentage reduction in colour after secondary EC treatment is 87.24 % in comparison to control.

Example II:

Table 2 compares the properties of the lime clarified sugar juice which was further clarified using the process of the present invention.

Conclusion: The improvement in color and turbidity is observed when the process of the present invention is applied.

[0041] While various embodiments of the present invention been described in detailed, it is apparent that modification and adaptation of those embodiments will occur to those skilled in the art. It is expressly understood, however, that such modifications and adaptations are within the spirit and scope of the present invention as set forth in the following claims.

Claims

We Claim,

1. A process for sugar extraction from sugar juices by removing impurities from raw sugar juices comprises following steps:

a) clarifying the raw sugar juice by the electro-coagulation to remove all impurities;

b) removing the floe;

c) re-clarifying the juice obtained in (b);

d) collecting molasses and adding to raw sugar juice and clarification by electrocoagulation to remove impurities and reduce sucrose loss in molasses; e) again removing the floe;

f) re-clarifying the clear juice obtained in (e).

2. The process for sugar extraction from sugar juices by removing impurities from raw sugar juices as claimed in claim 1, wherein optionally the primary electrocoagulation treated raw juice or the primary electro-coagulation treated mixture of molasses and raw sugar juice is passed through a secondary electro-coagulation system.

3. The process for sugar extraction from sugar juices by removing impurities from raw sugar juices as claimed in claim 1 , wherein optionally the multiple stages of electro-coagulation is done.

4. The process for sugar extraction from sugar juices by removing impurities from raw sugar juices as claimed in claim 1, wherein the non-sugar nutrients from the electro-coagulation treated sugar solutions alone and/or with added molasses are skimmed and further dried to obtain an enriched micronutrient formulation.

5. The process for sugar extraction from sugar juices byremoving impurities from raw sugar juices as claimed in claim 1, wherein the electro-coagulation is done either batch wise or continuous pipeline for a short interval at low intensity current. The process for sugar extraction from sugar juices by removing impurities from raw sugar juices as claimed in claim 1, wherein the raw sugar juice is selected from the mixed stevia/cane juice/sugar beet juice, syrup or clarified sugar cane juice or clarified sugar beet juice, raw sugar melt, molasses added to raw sugarcane/ sugar beet juice/syrup/melt, lime clarified juice and diluted juice.