SU1208078A1 - Method of crystallization of refined alpha-lactose from solution - Google Patents

Description

The invention relates to methods for the crystallization of lactose by gradually cooling the supersaturated solution under isohydric conditions and can be used in the dairy industry in the production of refined milk sugar.

The purpose of the invention is to increase the yield of crystalline mass and the size of the resulting crystals, as well as increasing the degree of homogeneity of the latter.

The method of crystallization of refined (vi-lactose from solution is carried out as follows.

The refined lactose syrup with a frequency of 99 units is adjusted to a solids content of 65% at 75 ° C and carefully filtered. Then set the cooling rate of the solution at 5 ° C / h with continuous stirring. Upon reaching a supersaturated solution of an initial crystallization temperature of 70 ° C, seed is introduced in the form of finely ground milk sugar crystals to form crystallization centers. The subsequent growth of crystals is carried out when the solution is cooled to a final crystallization temperature of 15 ° C at a constant speed under isohydric conditions and continuous vibration of vibration on the crystal mass by harmonic vibrations at a frequency f 11-15 s and amplitude

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1-3.

The intensification of lactose crystallization in the unsteady field of forced infrasonic harmonic oscillations is due to a significant increase in mass transfer in the dispersed system of supersaturated solution-crystals based on additional rotational-vibrational movements of quasi-pyramidal lactose crystals around the pyramid-centered inertia centers.

Such turning movements in the crystal solution make crystals oriented by the main axes of the pyramids, perpendicular or at an angle to the direction of oscillation. The crystals oriented by the main axes along the direction of the oscillations make joint reciprocating movements with the solution without turns. In the first case

ten

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Crystals exert considerable tangential forces, which increase the speed of the flow of the supersaturated solution around the latter and lead to a decrease in the thickness of the boundary saturated layer on the crystals and even to its detachment. A crystallized solution of lactose, which is in a field of gravity, turns out to be subject to the action of a field of inertial forces in a space covered by vibrational effects. At the same time, the insignificant dynamic viscosity of the lactose solution and low absorption of infrasonic vibrations are important. In the case of continuous movement, the action of the fields of inertia and gravity is summed, resulting in a dispersed system 20 under a pulsating load and additional frictional forces on the interface arise, strengthening mass transfer and increasing the yield of the crystalline phase.

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Example 1 According to the known method, a refined syrup with a purity of 99 units, (optical density 0.07) is brought to a dry matter content of 65% at 75 ° C and carefully filtered. The filtered syrup in the amount of 2.5 liters is transferred to a laboratory crystallizer preheated to the same temperature, which contains a jacketed cylindrical body and a stirrer. After that, the cooling rate of the solution is set at 5 C / h and the angular speed of the stirrer is set to 0.1 rad / s. When the saturated crystallization pacTBopQM temperature of 70 ° C is reached, seed is introduced in the form of finely ground dairy milk crystals to form crystallization centers. The subsequent growth of the crystals is carried out by cooling the solution at a constant speed under isohydric conditions to a final crystallization temperature of 30 ° C with continuous stirring. crystal size (V) 35%,

In the implementation of the proposed method, the crystallization of lactose in the initial stage is carried out analogue312П8078

in laboratory crista ko a ka

talizer, equipped with a movable bottom in the form of a flat disk, driven in reciprocating oscillatory motion. After the seed is introduced into the solution during the subsequent growth of the crystals, the crystal mass is subjected to vibration by harmonic vibrations with f 11c- and A 1-1P-m. At a final temperature of 30 ° C, the technological parameters are determined in the crystallisate, which are: in 36.4% , d 195 m, V 30.6%.

From the obtained data it follows that the proposed method allows to increase the yield of the crystalline phase from the solution by 17.4% and the size of the crystals by -2 times, moreover, the degree of crystal uniformity increases by 12.6%.

PRI mme R 2. The crystallization process is carried out with the same starting product and under the same initial conditions as in Example 1 and starting from the stage of growing lactose crystals, the crystal mass is subjected to vibration with harmonic oscillations C and A 5-10 m. The technological parameters of crystallisate at the following: urn 34.1%, d 163 µm, V 32.2%. Thus, in comparison with the known method, the yield of the crystal mass is increased by 10%, and the size of the crystals obtained is 1.66 times, in addition, the degree of homogeneity of the crystals increases.

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PRI M E R 3. The process of crystallization of lactose is carried out analogously to example 1, and the vibro-processing of the crystallizing dispersion system from the stage of crystal growth is carried out in harmonic vibrations with f 15c and A 1 10 m. The technological parameters of crystallisate at 30 ° C are: lga 36.2%, d 191 microns, V 31.2%, which, compared with the known method, gives an increase in the yield of the crystalline mass by 16.7% and the size of the crystals obtained by 1.95 times, as well as an increase in the degree of homogeneity of the crystals by 10, 9%.

Example 4. The process of crystallization of lactose is carried out, analogously to example 1, and the vibro-processing of the crystallizing dispersed system from the stage of crystal growth is performed by harmonic vibrations c-f 15c and A m. Technological parameters of crystallisate at 30 C are composed: lt 33.2 %, d 156 microns, V 34.1%, which compared with the known method gives an increase in the yield of the crystal mass by 7.1% and the size of the resulting crystals in

0 1.6 times, as well as an increase in the degree of crystals by 2.6%.

PRI me R 5. The process of crystallization of lactose is carried out analogously to example 1, and the vibration treatment

5 of the crystallizing dispersion system from the stage of crystal growth is produced by harmonic oscillations with f 13 and A 3-10 m. in comparison with the known method gives an increase in the yield of crystalline mass by 18.4% and the size of the resulting

5 crystals 2.1 times, as well as an increase in the degree of homogeneity of the crystals by 14%.

Example 6. The process of crystallization of lactose is carried out similarly to Example 1, and the vibro-processing of the crystallizing dispersion system from the stage of crystal growth is performed by harmonic vibrations from f 9 and 5-10 m. The technological parameters of crystallized at 30 C are: dt 31.2 %, d 95 microns, V 35.2%, which practically does not give advantages compared with the known method.

Example7. Crystal process

lactose lysing is carried out similarly to example 1, and the vibration treatment

the crystallizing dispersed system from the stage of crystal growth is produced by harmonic baths with f 17 and m. The technological parameters of crystallized at 30 ° C are: d m 30.8%, d 82 µm, V 39%, which is slightly worse than the characteristics of crystallized,

0 obtained in a known manner.

The data of examples 6 and 7 indicate the absence of a positive effect with the parameters of vibration treatment outside the intervals

f 11-15 s- and A 1-10 - 5-10-m.

Thus, the proposed method in comparison with the known permissible

It is necessary to increase the yield of the crystalline mass by 7.1-17.4% as a result of a more intensive crystallization process and the size of the resulting lactose crystals by 1.6–2 times, and also to increase the degree of homogeneity of the crystals by 2.6–12.6 % due to the alignment of temperature and concentration fields in the crystallizing dispersion system. Increasing the size of the resulting crystals

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 and reducing the heterogeneity of their particle size distribution provide improved conditions for the crystallization centrifugation. At the same time, the loss of lactose in mellus due to the ingress of small crystals into the microcrystal solution during the centrifugal separation, sediment decreases, since the number of small crystals in the crystallizer decreases.

Claims (1)

- METHOD OF CRYSTALLIZING REFINED OB-LACTOSE FROM THE SOLUTION, which provides for the formation of crystallization centers in the initial supersaturated solution and subsequent crystal growth upon cooling the solution at a constant speed under isohydric conditions with continuous stirring, characterized in that, in order to increase the yield of crystalline mass, increase the size of the obtained crystals and increase the degree of homogeneity of the latter, when crystals are growing, the crystal mass is subjected to vibration, harmonic oscillations with a frequency of 11-15 s and an amplitude of 1-10. 5> 10 ' ^e m.