SU1116008A1 - Method of obtaining potassium chloride - Google Patents

Abstract

1. A METHOD FOR OBTAINING KALIUM KHPORITS from hot saturated solutions, including cooling them with stirring, extracting potassium crystallisate from the resulting pulp by filtering followed by drying, dusting and returning the dust fraction to the beginning of the process, in order to increase the size of the crystals obtained, reducing their caking and energy consumption, the dust fraction is returned to the beginning of the process in a mixture with pulp, taken in an amount that provides the content in the solution of solid phases s 10-30 May.%. 2. The method according to p. 1, characterized by the fact that the mixing is carried out with a peripheral speed of 0.51, 5 m / s. (L

Description

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ABOUT

about

00 1. The invention relates to the production of potash fertilizers, namely potassium chloride, and can be used primarily in potash plants in the processing of sylvinites and brine brines to potassium chloride. A known method for the crystallization of potassium chloride from a hot saturated solution obtained by dissolving sylvinite is by cooling the solution in a multistage vacuum crystallization unit with horizontal C13 amylate crystallizer. According to this method, the cooling of the solution is carried out in 1A steps. After exiting the last stage, the resulting suspension is concentrated by settling, the crystalline pulp is filtered in centrifuges, the lysate potassium crystal is dried and released as a marketable product. The resulting product is finely dispersed. The average size of the crystals does not exceed 0.2 m, the content of the dust fraction with a particle size of less than 0.15 mm is more than 50%. The product is dusty, poorly dispersed, caking at snoring. The closest to the invention is the method of obtaining potassium chloride free, which consists in the fact that the solid phase of the suspension after crystallization is classified with the separation of coarse and fine crystalline fractions: the coarse crystalline fraction is dried and dedusted. The fine-crystalline and dusty fractions are treated with water and an acute vapor, the solution is 85% complete, and fed to the beginning of the crystallization process With 23. By this method, an increase in the particle size of the crystallized particles is achieved only by separating the small crystals and returning them to crystallization in order to overgrow the salt crystallizing from the solution, which leads to coarsening. The main mass of medium and large crystals does not increase in size. The amount of fine-crystalline and fine-particulate fractions separated from the crystallizer is from 20 to 80% or on average 50% of the mass of the finished product. These fractions are 85% dissolved in water and live steam, the resulting solution with the remaining 15% of fractions 8 2 is recycled to crystallization. Therefore, additional equipment must be installed to dissolve, and crystallization volume to increase by 42% for recrystallization, which leads to an increase in capital investment, and, in addition, requires an increase in energy and steam consumption. The aim of the invention is to increase the size of the crystals obtained, reduce their caking and reduce energy consumption. The goal is achieved by the fact that according to the method of obtaining potassium chloride from its hot, saline solutions, including cooling them with stirring, removing the potassium chloride crystallizer from the resulting pulp by filtering and then drying it, delivering it and returning the dust fraction to the beginning of the process, the dust fraction is returned at the beginning of the process, in a mixture with crystallisate, taken in an amount that provides 10-30 wt.% in the solid solution. In addition, stirring lead with the speed of the mixers 0, m / s 8, the proposed method enlarges not only small crystals, but the entire mass of crystals. Accordingly, the crystallization classification is not performed. If, according to known methods, the mechanism for enlarging crystals is the fouling of their salt from a solution, then in the proposed method the mechanism of enlarging is different. Due to the high solids content in the suspension supplied to the cooling, conditions are created for crystal splicing. Splicing occurs through the formation of a skeleton from the group of gritty crystals, filling of the pores of the skeleton with fine crystals and the final cementation of the packaging unit. The cementing agent for the formation of the skeleton and the scaling of the packaged aggregate is the nucleus K1, which is formed from the cooled cycnef 3MH liquid phase. For mixing with the saturated solution, the whole amount of dust fractions formed during drying and providing crystallized material with trapping in cyclones is supplied. The amount of crystallized matter (in the form of pulp) is given by the This mixture is mixed with the solution and is adjusted so that the total content of dust fractions and lysate crystal in the solution supplied for cooling is in the range from 10 to 30% by weight. 10 wt.% Corresponds to approximately one quantity: production crystallisate, iSO wt.% - ternary. The consolidation process is influenced mainly by 2 factors: the solids content in the suspension (the density of the suspension) and the intensity of the mixing of the suspension. When the content of the solid phase is less than 10 May, 7, the effect of crystal splicing with each other in the suspension coming to cooling is insignificant, mainly fouling of the crystal faces with salt from the solution without their splicing. With an increase in the content to 10% by weight,% and more, a sharp increase in the effect of the formation of crystals occurs, reaching its maximum of about 20% by weight. Taking into account this pattern, for small crystals with a more developed surface their content in the suspension should be less and, on the contrary, for larger crystals with a less developed surface for contact their content should be greater. The chosen mixing intensity limit expressed in the value of the peripheral speed of the mixers is necessary in order to keep the crystals in suspension in a suspended state, but no more, since the excess bulification leads to a deterioration of the contact between the crystals, prevent their Ivan and the destruction of aggregates. Naturally, for small crystals a low circumferential speed of 0.5 m / s is necessary, for large crystals a high one is 1.5 m / s. Primer p. The hot (95 ° С) saturated solution of KC1, obtained after dissolving sylvinite, is continuously fed to the crystallizer for cooling. The resulting suspension from the crystallizer is fed to the condensation tank. The clarified solution is drained from the settler, and the crystalline lysate pulp is filtered for filtration. Then, as from the filter, it enters the fluidized bed apparatus, where it is simultaneously carried out the classification of dry crystallisate in the upstream air with the collection of the dust fraction in the cyclone. In this mode, i.e. in the traditional way, the installation is continuously operating for 1-1.5 hours. Then, set the mode according to the proposed method. For this purpose, the crystallized pulp stream is divided into two parts. One part is fed for mixing with a saturated solution, and the other continues to flow into the filter. At the same time, the dust fraction from the cyclone is also mixed with the solution. The resulting slurry with a temperature of 75-85 ° C enters the mold, where it is cooled to 23-26 ° C. The cold suspension from the crystallizer is again separated, filtered, etc., and the cycle is repeated. Completed 3 experiments, showing 3 examples of the implementation of the proposed method: the solids content in examples 1-3 10, 30, 20 wt.% Respectively, the circumferential speed in examples 1-3 0.5; 1.5; 1 m / s, respectively. As can be seen from the table, the average size of the crystallized particles obtained by cooling the suspension, i.e. according to the proposed method, it is 0.56-0.72 mm, particles with a size less than 0.1 mm in the crystallisate are absent, whereas the average particle size of the crystallisate obtained upon cooling the solution, i.e. according to a known method, it is 0.120, 29 mm, in addition, the crystallisate contains up to 10% by mass of particles with a size less than 1 mm. According to the proposed method, the finished product (crystallized after drying) has an average particle size of 0.560.7 mm, dust particles (-0.1 mm) are absent in it; Parts 1 have a rounded shape. Thus, the proposed method allows to obtain coarse-grained, non-drip, sparingly and loose potassium chloride in 14-step vacuum crystallization plants.

Consumption of saturated solution

l / h

The residence time of the solution in the molds, h

The solids content in the pulp of crystallized, wt.%

The amount of pulp kristalliset supplied to the mixture with the solution, kg / h

The amount of dust fraction supplied to the mixture with the solution, kg / h

The solids content in the mixture (in suspension) of a solution of pulp of crystallized and dust fraction, wt.%

Speed of agitators, m / s

Quantity of finished product kg / h

The average particle size of crystallized, obtained by cooling the solution (by the known

100

200

300

0.5

0.75

46

48

51

240

80

160

about Q

2.5 /, 0

29-30

19-20

10-11

0.5

1.5

41

39

40

Claims (2)

1. METHOD FOR PRODUCING POTASSIUM CHLORIDE from its hot saturated solutions, including cooling them with stirring, isolating potassium chloride crystallizate from the resulting pulp by filtration, followed by drying, dust removal and returning the dust fraction to the beginning of the process, characterized in that, in order to increase the size of the obtained crystals, reducing their caking and reducing energy consumption, the dust fraction is returned to the beginning of the process in a mixture with pulp taken in an amount providing a solids content of 10-30 m e.%. 2. The method of pop. ^ characterized in that the mixing is carried out with a peripheral speed of 0.51.5 m / s. > 1 . eleven