RU2655211C1 - Method for obtaining soluble chlorine free potassium fertilizers (versions) - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: methods for obtaining soluble chlorine free potassium fertilizers are a cyclic process involving the execution in each cycle of a sequence of operations that are ion exchange reactions performed in one or more ion exchange columns using the same cation exchanger for all operations, prior to the beginning of each operation in the ionic form for this operation, each operation involves treating the cation exchanger with a solution that is the starting material of the said cyclic process for a given operation, obtain of the product of this operation and transfer of the cation exchanger into the ionic form for the next operation of the said sequence. One of the operations of this sequence involves treating the cation exchanger, being in Na form prior to the start of this operation, with solution of potassium chloride as the first starting material of said cyclic process, transferring the cation exchanger to the K form and preparing a sodium chloride solution.

EFFECT: high-purity chlorine free potassium mineral fertilizers using a wide range of raw materials, including acids.

26 cl, 11 dwg, 7 tbl, 12 ex

Description

The invention relates to a technology for the production of mineral fertilizers, and in particular to two variants of the method for producing instant chlorine-free potash fertilizers.

Chlorine-free potash fertilizers are among the most valuable fertilizers. In particular, monopotassium phosphate (MKF) is a very valuable complex fertilizer containing both potassium (34% K ₂ O) and phosphorus (52% P ₂ O ₅ ). Such fertilizer is widely used in vegetable growing, horticulture and floriculture. Recently, due to the growing demand for complex fertilizers in intensive crop production using drip irrigation technology, the water-soluble form of MKF, which is an almost pure salt, is potassium dihydrogen phosphate, which does not contain insoluble impurities. Almost the entire amount of water-soluble MKF consumed in Russia today is imported by import, mainly from Israel and Belgium. Another example of a valuable compound fertilizer is potassium nitrate, which simultaneously contains potassium (46% K ₂ O) and nitrogen (13% N-NO ₃ ). The bulk of nitrate consumed in Russia is imported from Chile and other countries.

Known methods for producing MCP by partial neutralization of phosphoric acid with carbonate or potassium hydroxide (M.E. Pozin. Technology of mineral fertilizers, L., "Chemistry", 1989, p. 304 [1]; RF patent No. 2164494, publ. 03/27/2001 [2]; RF patent No. 2261222, published on September 27, 2005 [3]; US patent No. 7601319, published on October 13, 2009 [4]). In this case, neutralization of potassium carbonate is carried out at elevated temperature to the calculated pH values, crystallization of the product is carried out with cooling [2, 3]. When using potassium hydroxide as a raw material, it is possible to isolate the product (crystallization) by direct granulation by spraying its mixture with phosphoric acid in a stoichiometric ratio [4]. The main disadvantage of these methods is the high cost of the used potassium raw materials. Another disadvantage is the need to use expensive thermal phosphoric acid to obtain soluble monopotassium phosphate or the need to purify the product by single or multiple recrystallization using industrial extraction phosphoric acid.

Known methods for producing monopotassium phosphate using cheaper raw materials - potassium chloride ([1], as well as: Chemical technology of inorganic substances / under the editorship of Akhmetov TG, in two books, M., "Higher School", 2002, Prince. 1, 688 pp. [5]; RF patent No. 2369585, published on 10/10/2009 [6]; US patent No. 3393044, published on July 16, 1968 [7]).

In particular, there is a known industrial method for producing MCP using potassium chloride, sulfuric acid and calcium phosphate ([1], p. 304; [5], p. 152). In accordance with this method, potassium chloride is treated with an excess of concentrated sulfuric acid at a temperature of from 80 ° C to 200 ° C to obtain hydrogen chloride vapors and a suspension of potassium hydrosulfate in sulfuric acid. Hydrogen chloride is disposed of to produce hydrochloric acid. An acidic suspension at a temperature of about 70 ° C is neutralized with calcium phosphate, for example, natural phosphorite, resulting in a suspension of gypsum in a mixed solution containing monopotassium phosphate and phosphoric acid. Gypsum is separated from the mixed solution by filtration, the solution is evaporated to a concentration of 50-60% MKF, and the latter is salted out from the cooled solution with methanol. The mother liquor is subjected to distillation to distill off the methanol returned to the process head, as well as to obtain phosphoric acid with up to 54% P ₂ O ₅ content.

The disadvantages of this method are the complexity of the technological process, including the need to combine the production of MKF with the production of other chemical products; the need to use special anti-corrosion equipment, as well as the harmfulness of production associated with the release of hydrochloric acid and methanol vapors. In addition, the disadvantage is the inability to obtain a water-soluble MKF in this way. At the same time, an attempt at subsequent purification, for example, by recrystallization, is also very laborious because of the need to use several successive stages of processing to achieve the required product quality.

Other methods for producing monopotassium phosphate using potassium chloride are known, in which a smaller number of technological stages are used and with which a smaller amount of by-products is associated ([6, 7]). In accordance with method [6], potassium chloride is decomposed with phosphoric acid at a temperature of 75 ÷ 100 ° C, and then the resulting pulp is heated to a temperature above 250 ° C in order to drive off the hydrogen chloride resulting from the decomposition reaction, which is captured by water to obtain medium hydrochloric acid concentration. In accordance with the method of [7], the resulting hydrogen chloride is extracted with an organic liquid at a temperature of 120-160 ° C, followed by decomposition of the organic complex with water to produce hydrochloric acid and returning the organics to the process. The methods [6, 7] retain a number of disadvantages inherent in the method [5], including the harmfulness of production, the need to use special anti-corrosion equipment, as well as the need for secondary processing of the product to obtain a water-soluble form of MPA.

A common drawback of the methods [5-7] is that these methods require the use of an excess of phosphoric acid compared with a stoichiometric amount, which leads to the production of a double compound of monopotassium phosphate and phosphoric acid, and this requires the use of a certain amount of potassium carbonate or hydroxide to obtain MCP .

A known method of producing a water-soluble MKF at temperatures below 100 ° C, based on the use of phosphoric acid and potassium chloride (US patent No. 4836995, publ. 06.06.1989 [8]). In accordance with this method, the interaction of phosphoric acid and extraction phosphoric acid (EPA) is carried out in a two-phase system containing mixed aqueous solutions and an organic phase immiscible with water, namely, long chain primary amines dissolved in kerosene. The hydrochloric acid formed in this process goes into the organic phase, namely, it interacts with the organic phase to form an amine complex with hydrochloric acid; a substantial part of the impurities contained in the initial EPA is also extracted into the organic phase. The aqueous phase is separated from the organic and additionally acidified with the starting phosphoric acid to obtain monopotassium phosphate and its crystallization to obtain solid MPA and the residual mixed solution returned to the process. The organic phase is regenerated with an alkaline agent, for example, calcium oxide or hydroxide, to obtain a solution of the chloride salt of an alkaline agent, for example, a solution of calcium chloride and the initial form of the organic phase, which is also returned to the process. The specified method also has significant disadvantages:

- the quality of the product depends entirely on the quality of the initial extraction phosphoric acid and it is not always guaranteed to obtain a soluble form of MKF without additional processing;

- difficult to recycle liquid waste of calcium chloride;

- kerosene has a certain (albeit small) solubility in water, due to which both products and waste are contaminated with the organic phase;

- the method is environmentally hazardous, especially in case of possible accidents and leakage of liquids;

- requires expensive equipment and an increased production culture in order to eliminate unpleasant odors at the production site.

Known methods for producing other potassium complex fertilizers, in particular potassium nitrate from potassium chloride, by the conversion method using calcium or ammonium nitrate ([1], p. 301; USSR copyright certificate No. 1248650, publ. 07.08.1986 [9]). In accordance with these methods, a cyclic process is carried out, each cycle of which consists of the stages of sorption and desorption of potassium. A solution of potassium chloride is passed through cation exchange resin, converting the ion exchanger into the K-form (sorption stage). Then, solutions of the corresponding nitrates (calcium or ammonium) are passed through it, obtaining at the output a solution of potassium nitrate and converting the ion exchanger into the calcium or ammonium form, respectively (desorption stage). In the next cycle, a solution of potassium chloride is again passed through the cation exchange resin, converting it again into the K-form and, at the output, a solution of calcium chloride or ammonium chloride is obtained. Next, carry out the stage of desorption and repeat the cycle. At least two cateonite columns operating at opposite stages are used to carry out the process in a continuous mode. Unfortunately, these ion-exchange methods do not provide a complete separation of solutions of different nature from each other, therefore only a small part of the filtrates leaving the columns are pure single-component solutions, the rest of the filtrates are mixed solutions that require subsequent complex processing for further use . In addition, the problem of recycling calcium and ammonium chlorides also remains.

A common drawback of all of the above methods [1-9] is that they are not universal, but are narrowly aimed at obtaining only one final product from the group of chlorine-free potash fertilizers.

Closest to the proposed method is the ion-exchange method for producing soluble chlorine-free potassium mineral fertilizers according to the patent of the Russian Federation No. 2201414, publ. 03/27/2003 [10]. In accordance with this method, ion exchange reactions are carried out cyclically. In this case, in each cycle, an ion exchange reaction is carried out with the participation of potassium chloride as the first starting material, using cation exchange resin in the form of an auxiliary component and converting it into a K-form to obtain a chlorine salt of the auxiliary component, as well as an ion exchange reaction with the participation of the chlorine-free salt of the auxiliary component as the second starting material, using the previously obtained cation exchanger in the K-form and converting it into the form of an auxiliary component to obtain the product in the form of chlorine-free potassium oh salt. In this case, the cation exchange resin is selected so that its selectivity to the auxiliary component is less than the selectivity to potassium, and the concentration of the indicated chlorine-free salt of the auxiliary component is chosen higher than the concentration of the saturated solution of the chlorine-free potassium salt. As the chlorine-free salt of the auxiliary component, sodium sulfate, ammonium nitrate, and ammonium dihydrogen phosphate can be used.

The method according to the patent [10] allows to obtain high-quality soluble chlorine-free potash fertilizers, however, this method has several disadvantages:

- the requirement for the properties of the used cation exchanger, namely the condition that it should have increased selectivity to potassium ion compared to other cations involved in the process, sharply narrows the range of ion-exchange materials used, leaving essentially only the possibility of using strongly acidic cation exchangers for which this condition performed in relation to the most accessible auxiliary components, such as sodium or ammonium ions;

- the same limitation makes it impossible to use cations of magnesium, calcium and other multiply charged ions as auxiliary components, and the chlorine-free salts of these cations as raw materials for the target product - soluble chlorine-free potassium fertilizer;

- the method involves only the use of chlorine-free salts containing an auxiliary component, which excludes the possibility of using any still widely available and relatively cheap substances, in particular acids (for example, sulfuric or phosphoric), for ion-exchange conversion of potassium chloride to a chlorine-free potassium fertilizer.

- as a result of the implementation of this method get a supersaturated solution from which the desired product crystallizes spontaneously. As a result, the range of raw materials suitable for use is narrowed, since in the presence of sparingly soluble impurities in the starting materials, the latter appear in the crystallized target product, creating the problem of its purification. For example, the presence of calcium in the starting material, which forms insoluble gypsum with the sulfate ion, is unacceptable.

Technical solutions for both variants of the present invention related to a method for producing soluble chlorine-free potash fertilizers are aimed at achieving a technical result consisting in providing the possibility of obtaining high-purity chlorine-free potash mineral fertilizers using a wide range of feedstock, including acids, and corresponding expansion of the range of fertilizers obtained by at the same time reducing the requirements for the content of poorly soluble raw materials in raw materials s or impurities capable of forming a sparingly soluble substance in the processes for obtaining the desired products. Below, when disclosing the essence of the invention and considering the frequent cases of its implementation, both types of other technical results can be mentioned in both cases.

The proposed method for the production of soluble chlorine-free potassium fertilizers according to the first embodiment, as well as the one closest to it, is a cyclic process, which includes in each cycle a sequence of operations that are ion exchange reactions carried out in one or more ion-exchange columns using each of a layer of the cation exchange resin, which is the same for all operations, is located in the ionic form specific to it before the start of each operation. Each operation includes the treatment of cation exchange resin with a solution that is the starting material of the specified cyclic process specific for this operation, obtaining the product of this operation and transferring the cation exchange resin to another ionic form specific to the next operation of the specified sequence. In this case, one of the operations of the indicated sequence includes processing the cation exchange resin, which is in the Na-form before the start of the operation, with a solution of potassium chloride as the first starting material of the indicated cyclic process, converting the cation exchange resin into the K-form, and obtaining a solution of sodium chloride.

To achieve the above technical result in the proposed method according to the first embodiment, in contrast to the closest known method, weakly acid cation exchange resin is used as a cation exchange resin, the same for all operations carried out in the indicated cyclic process. After the mentioned operation, including the treatment of the cation exchange resin with a solution of potassium chloride, an operation is carried out with the participation of a chlorine-free oxygen-containing acid as the second starting material of this cyclic process, including the treatment of the cation exchange resin obtained in the previous operation in the K-form, the layer of which is maintained in a fluidized state, with converting it to the H-form and obtaining a suspension containing the target product in the form of a potassium salt of the indicated chlorine-free oxygen-containing acid, and iltratsiyu or centrifuging the resulting suspension to purify it from low-soluble impurities. Then, the cation exchanger is continued to be treated in the indicated fluidized bed, using the suspension obtained by filtration or centrifugation for it, and this treatment is repeated and the filtration or centrifugation of the resulting suspension is carried out several times. Then, an operation is carried out with the participation of an additional starting material of the indicated cyclic process in the form of a solution of sodium alkali or soda ash, which is used to process the cation exchange resin obtained in the previous operation in the H-form, converting it into the Na-form specific for the first of the listed operations, and thereby creating the possibility of cyclical continuation of the specified process.

Provided by the proposed method according to the first embodiment, the implementation of the sequence of operations of ion exchange allows you to get the target product as a result of processing carried out in the second of these operations. The presence of this operation in the sequence of operations of the proposed method according to the first embodiment makes it possible to select from a number of oxygen-containing acids to produce an equally wide range of potassium salts, and the presence of a third ion-exchange operation, along with the first two, makes it possible to close the cycle. Moreover, this sequence of operations becomes possible due to the use of weakly acid cation exchanger, which exhibits increased selectivity to hydrogen cations (hydroxonium).

In contrast to the closest known method, providing for a supersaturated solution from which the desired product crystallizes spontaneously, in the proposed method according to the first embodiment, a suspension containing a solution of potassium chlorine-free fertilizer is obtained. At the same time, by maintaining the cation exchanger layer in a fluidized state, it becomes possible to remove from the column the entire solid phase of the resulting suspension containing poorly soluble impurities inevitably present in the starting materials, while in the dense cation exchanger layer a filtering effect would take place and some of the solid phase would remain in it by the end of the operation. In the proposed method, the suspension containing the solid phase withdrawn from the column is filtered or centrifuged, followed by processing the cation exchanger in the column in a circulating mode, which ensures both proper purification of the obtained target product and prevention of cation exchanger contamination in the column.

In the particular case, as an oxygen-containing acid in the implementation of the proposed method according to the first embodiment, extraction phosphoric acid can be used, previously subjected to purification by extraction with an organic reagent, for example, in accordance with the method according to the patent of the Russian Federation No. 2452685 (publ. 10.06.2012 [11]) , or (preferably) by the sorption method of "acid retention" in one of its following modifications:

- according to the method with periodic transmission of the initial EPA from bottom to top through a layer of strongly basic anion exchange resin in phosphate form until the acid “breaks through” and backward displacement of purified acid adsorbed on the anion exchange resin with water from top to bottom (RF patent No. 2544731, publ. March 20, 2015 [12]);

- according to the method subsequently called by its authors “NewKem-method”, using sorption systems with two liquid phases, based on reducing the volume of space between the sorbent granules occupied by the processed solution by filling the sorbent layer with an organic liquid substance that is not miscible with water, neither with this solution and does not chemically interact with its components of the processed solution (RF patent No. 2434679, publ. 11/27/2011 [13]; R.Kh. Khamizov. Sorption method of "acid retention". Some technological Opportunities for electrolyte separation. Sorption and chromatographic processes. 2013. V. 13. Issue 5, S. 600-604 [14]).

In another particular case, an nitric acid extract obtained by nitric acid decomposition of phosphate feedstock and containing phosphoric acid mixed with nitric acid, previously purified by the sorption NewKem method of acid retention, can be used as an oxygen-containing acid [13, 14].

As an oxygen-containing acid in the implementation of the proposed method according to the first embodiment, technical sulfuric acid of any kind can also be used, including contact, tower and regenerated.

In these cases, potassium phosphate, a mixture of potassium nitrate and potassium phosphate, and potassium sulfate are respectively obtained as the target product.

The proposed method according to the first embodiment can be implemented using a single ion-exchange column. In this case, the operations described above are stages that are alternately carried out in this column. However, it is more rational to carry out a cyclic process in several stages in each cycle so that at each stage the above-mentioned ion-exchange operations are carried out in three simultaneously operating ion-exchange columns with the same sorption layers of cation exchange resin, but in three different ionic forms before the operation - the Na-form, K-form and H-form, alternating from stage to stage of these ionic forms and solutions supplied to ion-exchange columns, which are the starting materials of this cyclic process, specific for related operations.

With this implementation of the method, the continuity of the preparation of the target product, the chlorine-free potassium salt, can be ensured.

At the end of each stage, it is advisable to wash each ion-exchange column with water, displacing the electrolyte in the column, and displace the water remaining in the column after washing with the solution supplied to the column for processing the cation exchanger in the next stage. Rinsing is carried out in order to ensure the purity of the products obtained and to prevent over-use of the solutions of the starting materials.

In the particular case of the method according to the first embodiment, the operation involving potassium chloride as the first starting material at each stage is carried out in the form of two simultaneously proceeding processes in two ion-exchange columns connected in series, which requires one ion-exchange column in addition to the three above. In the first of two simultaneously proceeding processes, the solution is treated with a potassium chloride solution of cation exchange resin, which is in the first of the indicated series-connected ion-exchange columns in mixed Na, K form before starting this operation, a solution is obtained which is the result of this treatment, and cation exchange resin is transferred in the first ion-exchange column from said mixed ionic form to pure K-form. In the second process, the solution obtained in the first process is treated with the cation exchange resin, which is in the second of the indicated series-connected ion-exchange columns in pure Na form, before starting this operation, a sodium chloride solution is obtained and cation exchange resin is transferred from the Na form to the specified mixed Na, K -form.

With this embodiment of the proposed method, a higher purity of the target product can be achieved and an overspending of the starting material is prevented. This is explained by the fact that during the actual conduct of ion exchange operations, there are processes of mutual diffusion in the cation exchanger layer and mixing in the solution. In such a process, there is no guarantee that at the time of the appearance of potassium ions in the resulting solution (when it is necessary to complete the stage of the cycle to avoid loss of the starting material), a pure K-form of cation exchange resin is obtained and some of the cation exchange resin still does not remain in the Na-form. In this case, at the next stage of the cycle, when the cation exchanger is treated with the second starting material (oxygen-containing acid), there is a risk of obtaining not a pure target product (for example, monopotassium phosphate using phosphoric acid), but a product contaminated with an admixture of sodium dihydrogen phosphate. When carrying out this operation in the form of two simultaneously proceeding processes in two series-connected ion-exchange columns, the probability of such a situation significantly decreases.

When implementing the proposed method according to the first embodiment, in this particular case, in each cycle at each stage, four ion-exchange columns with identical sorption layers of cation exchange resin, but in the four different ionic forms mentioned above (mixed Na, K-form, Na-form, K- form and H-form) with alternating from stage to stage in each of these columns of these forms and fed into the columns of substances involved in ion exchange, two of these four columns being used at each stage of the cycle to carry out two the ongoing processes of ion-exchange operations involving potassium chloride as the first starting material.

In this particular case, at the end of each stage, each ion-exchange column containing cation exchange resin in pure ionic form is washed with water, displacing the electrolyte in the column, and the water remaining in the column after washing is displaced with the solution supplied to the column for processing cation exchanger at the next stage.

To ensure a higher productivity of the process, it is advisable to select the rates of transmission of the solutions of the starting materials through the ion-exchange columns so that the moments of completion of the processing of cation exchange resin in all ion-exchange columns at each stage of the cycle coincide with each other.

The proposed method for the production of soluble chlorine-free potassium fertilizers according to the second embodiment, as well as the closest known one, is a cyclic process, which includes in each cycle a sequence of operations that are ion exchange reactions carried out in one or more ion-exchange columns using each of them a layer of the cation exchange resin, which is the same for all operations, located before the start of each operation in its specific ionic form. Each operation includes the treatment of cation exchange resin with a solution that is the starting material of the specified cyclic process specific for this operation, obtaining the product of this operation and transferring the cation exchange resin to another ionic form specific to the next operation of the specified sequence. In this case, one of the operations of the indicated sequence includes processing the cation exchange resin, which is in the Na-form before the start of the operation, with a solution of potassium chloride as the first starting material of the indicated cyclic process, converting the cation exchange resin into the K-form, and obtaining a solution of sodium chloride.

To achieve the above technical result in the proposed method according to the second embodiment, in contrast to the closest known method, a weakly acidic cation exchange resin is used as a cation exchange resin, the same for all operations carried out in the indicated cyclic process. After the mentioned operation, including the treatment of cation exchange resin with a solution of potassium chloride, an operation is carried out with the participation of a non-potassium salt of a chlorine-free oxygen-containing acid as the second starting material of the indicated cyclic process. This operation involves the treatment with this solution of the cation exchanger obtained in the previous operation in the K-form, converting it into the ionic form of the cation of the specified non-potassium salt and obtaining a suspension containing the target product in the form of the potassium salt of the indicated chlorine-free oxygen-containing acid. Then carry out the operation with the participation of the third starting material of the specified cyclic process in the form of a solution of chlorine-free oxygen-containing acid, different from the one whose salt solution is the second starting material of the specified cyclic process. This solution is used to treat the cation exchange resin obtained in the previous operation in the ionic form of the cation of the specified non-potassium salt, the layer of which is maintained in the fluidization state, converting it to the H-form and obtaining a suspension containing the additional target product in the form of a salt formed by the cation of the specified non-potassium salt and the chlorine-free anion oxygen-containing acid, a solution of which is the third starting material of the specified cyclic process. At the same time, the resulting suspension is also filtered or centrifuged to purify it from sparingly soluble impurities, and then the cation exchanger is continued to be treated in the indicated fluidized bed, using the resulting suspension subjected to filtration or centrifugation, and this treatment is repeated and the filtration or centrifugation following it is repeated. the resulting suspension several times. Then, an operation is carried out with the participation of an additional starting material of the indicated cyclic process in the form of a solution of sodium alkali or soda ash, which is used to process the cation exchanger obtained in the previous operation in the H-form. It is transferred to the Na form specific for the first of the listed operations, thereby creating the possibility of cyclical continuation of this process.

Provided by the proposed method according to the second embodiment, carrying out the sequence of operations of ion exchange allows to obtain the target product as a result of processing carried out in the second of these operations and an additional target product as a result of processing carried out in the third of these operations. The second of the above-mentioned ion-exchange operations, contained in the sequence of operations of the proposed method according to the second embodiment, makes it possible to select from a number of chlorine-free acids to produce an equally wide range of potassium salts. The presence of the third of the above-mentioned ion-exchange operations, which allows to obtain an additional target product in the form of a salt formed by the cation of the second starting substance and the anion of chlorine-free oxygen-containing acid, makes it possible to choose a combination of the second starting material and chlorine-free oxygen-containing acid, in which the second product is also a fertilizer forming in combinations with chlorine-free potassium fertilizer complex mineral fertilizer. The presence of the fourth ion-exchange operation along with the first three provides the possibility of closing the cycle. Moreover, the specified sequence of operations of the proposed method according to the second embodiment becomes possible due to the use of weakly acid cation exchange resin exhibiting increased selectivity to hydrogen ions.

In contrast to the closest known method, providing for a supersaturated solution from which the target product spontaneously crystallizes, in the proposed method according to the second embodiment, a suspension containing a solution of potassium chlorine-free fertilizer is obtained as the target product.

To remove insoluble impurities from this suspension that may be contained with them, depending on the purity of the starting materials used, it can be filtered or centrifuged at the final stage of the process.

At the same time, a suspension is also obtained containing an additional target product in the form of a salt formed by the cation of the second starting material and the anion of an oxygen-containing acid, which can also be a fertilizer. At the same time, by maintaining the cation exchanger layer in a fluidized state, it becomes possible to remove from the column the entire solid phase of the resulting suspension containing poorly soluble impurities inevitably present in the starting materials, while in the dense cation exchanger layer a filtering effect would take place, and some of the solid phase would remain in it by the end of the operation. In the proposed method according to the second embodiment, similarly to the method according to the first embodiment, the suspension containing the solid phase withdrawn from the column is filtered or centrifuged, followed by cation exchange resin processing in the column, which ensures both proper purification of the obtained target product and prevention pollution of cation exchanger in the column.

As the second and third starting materials, for example, solutions of, respectively, ammonium nitrate (ammonium nitrate) and purified extraction phosphoric acid can be used. In this case, the target product can be obtained - a solution of potassium nitrate and an additional product - monoammonium phosphate, collectively called ammophos, which is a valuable complex mineral fertilizer.

In the particular case, solutions of ammonium nitrate and sulfuric acid, respectively, to produce potassium nitrate and ammonium sulfate can also be used as the second and third starting materials.

In another particular case, a solution of ammonium sulfate is used as the second starting material, and a solution of phosphoric acid is used as the third starting material, resulting in potassium sulfate and monoammonium phosphate.

In another particular case, solutions of, respectively, monoammonium phosphate and sulfuric acid are used as the second and third starting materials to produce more valuable monopotassium phosphate and ammonium sulfate.

The proposed method according to the second embodiment, as well as the method according to the first embodiment, can be implemented using a single ion-exchange column. In this case, the operations described above are stages that are alternately carried out in this column. However, it is more rational to carry out a cyclic process in several stages in each cycle so that at each stage the above-mentioned ion-exchange operations are carried out in four simultaneously operating ion-exchange columns with the same sorption layers of cation exchange resin, but in four different ionic forms before the operation: Na-form, K-form, the ionic form of the cation of the specified non-potassium salt, the solution of which is the second starting material of the specified cyclic process, and the H-form, alternating from stage to stage of these ionic forms and solutions supplied to the ion exchange columns, which are the starting materials of the indicated cyclic process, specific to the corresponding operations.

With this implementation of the method, the continuity of obtaining the target product — the chlorine-free potassium salt and the additional target product — can be ensured.

At the end of each stage, it is advisable to rinse each ion-exchange column with water, displacing the electrolyte in the column. In this case, the water remaining in the column after washing is displaced by the solution supplied to the column for processing the cation exchanger in it at the next stage.

In the particular case of the implementation of the method according to the second embodiment, it is possible to carry out the first or last of the operations described above, or both of these operations, carried out with the participation of the first and additional starting materials, respectively, at each stage in the form of two simultaneously proceeding processes in two ion-exchange columns connected in series, t .e. using, in addition to the four above, another ion exchange column for each of these operations. The first of these processes involves the treatment with the starting material of the specified cyclic process specific for a given operation, cation exchange resin, which is located before the start of this operation in the first of these series-connected ion-exchange columns in mixed ionic form and containing cation exchange resin both in the ionic form specific to this operation, and in ionic form specific for the next operation of the indicated sequence. In this process, a solution is obtained which is the result of said treatment, and cation exchange resin is transferred from the indicated mixed ionic form to a pure ionic form specific for the next process step. The second process involves the treatment with the solution obtained in the first process of cation exchange resin, which is located before the start of this operation in the second of these series-connected ion-exchange columns in a specific ionic form for this operation. In this case, the product of this operation is obtained and the cation exchange resin is transferred to the indicated mixed ionic form for use in the next stage of the cyclic process, which is the proposed method.

When performing one or both of the above operations in the form of two simultaneously proceeding processes in two series-connected ion-exchange columns, a higher purity of the obtained products can be achieved and the excess consumption of the starting materials is reduced. As in the method according to the first embodiment, this is due to the fact that in the actual conduct of ion exchange operations, there are processes of mutual diffusion in the cation exchanger layer and mixing in the solution. In such a process, there is no guarantee that at the moment the ions of the starting material appear in the resulting solution (when it is necessary to complete the stage in order to avoid losses of the starting material), a pure form of the cation exchange resin treated with this substance is obtained, and some of the cation exchange resin still does not remain in its original form. In this case, at the next stage, when the cation exchange resin is treated with the second starting material, there is a risk of obtaining not a pure target product (for example, potassium nitrate when using ammonium nitrate as the second starting product), but a product contaminated with an admixture of sodium nitrate. When carrying out the same operation in the form of two simultaneously proceeding processes in two series-connected ion-exchange columns, the probability of such a situation significantly decreases.

In particular, when carrying out an operation involving a solution of potassium chloride as the first starting material of the proposed method in the first of the two processes, the solution is treated with a solution of potassium chloride of cation exchange resin, which is located before the start of this operation in the first of two ion-exchange columns used in this operation in the first mixed form and containing cation exchanger both in Na-form and in K-form, a solution is obtained which is the result of this treatment, and cation exchanger is converted into pure K-form. In the second process, it is treated with the solution obtained in the first process, the cation exchange resin, which is before the start of this operation in the second of the two ion exchange columns used in this operation, in pure Na-form, sodium chloride is obtained and the cation exchange resin is converted to the first mixed ionic form.

In the case described above, for the implementation of the proposed method according to the second embodiment, at each stage of the cycle, five ion-exchange columns with the same sorption layers of cation exchange resin, but in five different ionic forms, are required.

In this particular case, at the end of each stage, it is advisable to rinse each ion-exchange column containing cation exchange resin in pure ionic form with water, displacing the electrolyte in the column. In this case, the water remaining in the column after washing is displaced by the solution supplied to the column for processing the cation exchanger in it at the next stage.

It is advisable to select the transmission rates of the solutions of the starting materials through the ion-exchange columns in such a way that the moments of completion of the processing of cation exchange resin in all ion-exchange columns at each stage of the cycle coincide with each other. This ensures a higher productivity of the process.

The invention is illustrated by drawings, which show:

- in FIG. 1 - change in the ionic forms of cation exchange resin in ion-exchange columns supplied to them and solutions removed from them from stage to stage during the implementation of the cycle of the method according to the first embodiment;

- in FIG. 2a, 2b is a diagram of an apparatus for implementing the method according to the first embodiment using three ion-exchange columns in two special cases;

- in FIG. 3 - movement of the concentration front in the column in the process of ion exchange;

- in FIG. 4 - change in the ionic forms of cation exchange resin in ion-exchange columns supplied to them and solutions removed from them from stage to stage when implementing the method according to the first embodiment using four ion-exchange columns;

- in FIG. 5a, 5b is a diagram of an apparatus for implementing the method of the first embodiment using four ion-exchange columns in two special cases;

- in FIG. 6 is a change in the ionic forms of cation exchange resin in the ion exchange columns supplied to them and solutions removed from them from stage to stage when the process cycle according to the second embodiment is carried out using four ion exchange columns;

- in FIG. 7 is a diagram of an apparatus for implementing the method of the second embodiment using four ion-exchange columns;

- in FIG. 8 is a diagram of an apparatus for implementing the method of the second embodiment using five ion-exchange columns;

- in FIG. 9 is a change in the ionic forms of cation exchange resin in the ion-exchange columns supplied to them and solutions removed from them from stage to stage when the process cycle according to the second embodiment is carried out using five ion-exchange columns.

When implementing the method according to the first embodiment, operations are carried out in which, for example, the following ion-exchange reactions occur:

- the translation of the original Na-form of cation exchanger (R) in the K-form using the first source substance - a solution of potassium chloride and to obtain a solution of sodium chloride:

- the conversion of the K-form of cation exchange resin to the H-form using chlorine-free oxygen-containing acid as the second starting material, in this particular case, purified extraction phosphoric acid, to obtain a solution of the target product monopotassium phosphate:

- the conversion of the H-form of cation exchanger back to the Na-form when it is treated with a solution of soda ash, which is an additional starting material, to obtain water and carbon dioxide:

or with obtaining water - when treated with a solution of sodium alkali as an additional starting substance:

As the cation exchanger, for example, gel carboxyl cation exchanger type KB-4P-2 or macroporous carboxy cation exchanger type Lewatit CNP-80 can be used. The use of weakly acidic cation exchange resin is due to the fact that for the effective implementation of operations (3) or (3 '), the cation exchange resin must have the highest selectivity to hydrogen cations in comparison with other cations of the starting materials used in the method.

As already mentioned, the method according to the first embodiment can fundamentally be implemented in one ion-exchange column, carrying out in it successively the stages, which are operations involving the indicated reactions. However, in order to increase the productivity of the process and ensure the continuity of obtaining the target product, it is advisable to use several columns, and not with a simple increase in their number with parallel carrying out of the same processes in all columns, but with such an organization of the cyclic process when different operations are carried out simultaneously in different columns. At three stages, which correspond to reactions (1), (2) and (3) or (3 '), three columns are sufficient for such an organization of the process.

The change in the ionic forms of cation exchange resin in the ion-exchange columns supplied to them and solutions removed from them from stage to stage during the cycle of the method according to the first embodiment in three ion-exchange columns is illustrated in FIG. 1, and the installation diagram in which this method can be implemented is FIG. 2a. Said ion exchange columns in the diagram of FIG. 2a and FIG. 1 have the designations 1, 2, 3. Filtration or centrifugation of the suspension containing the target product, and collection in an auxiliary container of the obtained filtrate or centrifugation result used in the subsequent processing of cation exchange resin instead of extraction phosphoric acid solution, are indicated by the letters F and E, respectively, and are indicated by dashed lines lines.

Before the beginning of each stage of the cycle, the ionic forms of cation exchanger in different columns must be different, for example, in column 1 cation exchanger must be in Na-form; in column 2, in K-form, and in column 3, in H-form. Then, in these columns, it is simultaneously possible to carry out operations with reactions (1), (2), (3), respectively. In the next stage, operations with reactions (2), (3), (1), respectively, can be carried out simultaneously in the same columns; at the next stage — operations with reactions (3), (1), (2), respectively; then - again operations with a combination of reactions (1), (2), (3), etc.

In FIG. 2a, illustrating the hardware embodiment of the proposed method according to the first embodiment, allowing to organize the process of FIG. 1, along with the above-mentioned designations 1, 2, 3 of ion-exchange columns, the following designations are used:

5 - capacity for the first starting substance - a solution of potassium chloride;

6 - capacity for collecting the product of reaction (1) - sodium chloride solution;

7 - capacity for the second starting substance - oxygen-containing acid;

8 - capacity for collecting the target product;

9 - capacity for an additional initial product - a soda solution.

10 - a container for water;

Ф - filter or continuous centrifuge;

E - auxiliary capacity for collecting the obtained filtrate or the result of centrifugation;

H is the pump.

Shown in the diagram of FIG. 2a, the state of the valves corresponds to the first stage of the duty cycle (first line in FIG. 1), in which:

- the ion exchange column 1 is in the transmission mode of the first starting material - a solution of potassium chloride and the conversion of cation exchange resin in the K-form to obtain a solution of sodium chloride;

- column 2 - in the transmission mode of the acid, which is the second starting material, and the conversion of cation exchange resin to the H-form to obtain a solution of the target product;

- column 3 - in the mode of transmission of a solution of soda ash and the conversion of cation exchanger into Na-form with the receipt of water and carbon dioxide.

The cation exchanger in the columns after the described processing step goes into the indicated ionic forms, respectively. In the next step, as shown in FIG. 1, solutions of extraction phosphoric acid (from tank 7), soda (from tank 9) and potassium chloride (from tank 5) are respectively supplied to the columns, and the solution supplied to each of the columns is changed from stage to stage, so that the same column serves the same solution periodically every three stages, forming a cycle.

When passing a solution of oxygen-containing acid through a column with a potassium form of cation exchanger, a suspension containing the target product — potassium chloride-free fertilizer — is obtained at the outlet of the column. This operation is carried out using the calculated volume of the indicated acid, which, when reacted with a known amount of cation exchanger in the K-form in the column, allows to obtain monopotassium phosphate in accordance with reaction (2). The suspension subjected to filtration or centrifugation in an appropriate medium F is collected in auxiliary vessel E and then the contents of this vessel are fed to the column inlet instead of the extraction phosphoric acid solution, continuing to process the cation exchange resin in a circulating mode along the circuit: column — continuous filter or centrifuge (Ф) - auxiliary capacity E - pump N - column. The connection shown in the diagram of FIG. 2a and described in the following diagrams of a series-connected continuous filter or centrifuge (Ф), auxiliary tank E and pump H to a certain column, depending on the stage of the method, are carried out by appropriate switching of valves. Both the oxygen-containing acid solution and the suspension that has been filtered or centrifuged from the vessel E are passed through the column at a speed that ensures fluidization of the cation exchanger layer located in it. After such processing and the subsequent filtration or centrifugation of the resulting suspension are carried out several times, the purified suspension, which is the finished target product, from auxiliary vessel E is sent to vessel 8 to collect such a product. In this case, cation exchanger in the column is in the H-form in accordance with reaction (2).

When passing a soda solution through a column with a hydrogen form of cation exchanger, water is obtained at the outlet, which is sent to a container 10 (Fig. 2a), and when passing a solution of potassium chloride through a column with a sodium form of cation exchanger, a solution of sodium chloride is sent to the outlet to tank 6.

When shown in FIG. 2a, the feed lines for the solutions of the starting materials ensure that they are passed through the columns in a bottom-up direction, which is preferred. The flow directions of the solutions shown in FIG. 1 arrows match preferred.

It is advisable to rinse the columns after each ion exchange operation in them, because after the end of each stage of the cycle, in each column, the cation exchange resin of which has changed to another ionic form, there is an electrolyte solution with which it was converted to this ionic form. For example, in a column that is converted to K-form, between the grains of cation exchanger (in the porous space), and also above and (or) below the cation exchanger layer there will be a solution of potassium chloride.

In FIG. 2b shows a setup diagram in which the proposed method according to the first embodiment can be carried out with washing of ion-exchange columns. The installation in this diagram is shown in a state corresponding to passing water through columns. All designations in the diagram of FIG. 2b coincide with those used in FIG. 2a. However, shown in FIG. 2b, the water tank 10 is used not only for collecting water, in contrast to the installation according to the scheme of FIG. 2a, but also as a source of water used in washing, i.e. is a tank for recycled water.

During washing with water, it is possible to displace the electrolyte in the column from the column and return it back to the appropriate container where this solution is stored and from where it is supplied to the process. So, for example, after the first stage is completed and before the second stage of the cycle begins (see Fig. 1), the potassium chloride solution from column 1 can be returned to tank 5, phosphoric acid solution from column 2 to tank 7, and the soda solution from column 3 to capacity 9.

Since at the beginning of the next stage of the cycle there is water in each column before the corresponding operation, water needs to be forced out of the column, which is done by passing a solution, which is the starting material for each column, which must be fed into it at the next stage in order to process the cation exchanger in the column.

After displacing the water sent to the tank 10 for circulating water, certain liquids begin to come out of the columns:

- from a column with cation exchange resin, in Na-form during an operation involving reaction (1), - a solution of sodium chloride;

- from a column with cation exchange resin in K-form during an operation involving reaction (2), a suspension containing monopotassium phosphate;

- from a column with cation exchange resin in H-form during an operation including reaction (3), water.

As already explained in the disclosure of the invention, when carrying out operations with ion exchange reactions, there are processes of mutual diffusion in a layer of cation exchange resin and mixing in solution. These processes, which cause the formation of mixed solutions of electrolytes and mixed ionic forms of cation exchange resin, lead to the fact that the so-called ion exchange fronts are not perpendicular to the longitudinal axis of the ion exchange columns, but are stretched along the columns, as shown by dashed lines 36 in the lower part of FIG. 3. The solid line 35 in this figure shows the idealized shape of the fronts, in which one solution “pushes” the other, like a piston. In this case, the sorption layer 32 of cation exchanger in the column 31 (upper figure in Fig. 3) is divided into parts by an almost horizontal concentration front 33, which separates potassium ions from sodium ions, i.e. the potassium chloride solution displaces the sodium chloride solution in a "piston" manner with virtually no stirring. (It should be noted the conditional nature of Fig. 3 in that the potassium chloride solution is supplied from the top to the bottom of the column, although it is more appropriate to supply from the bottom to the top, as shown in Fig. 1 and other figures illustrating the implementation of both variants of the proposed method).

In the actual course of the process, when the front has the form 34 (the upper figure in Fig. 3), at the moment of the appearance of ions of the input solution at the output of the column (which, if the process was perfect, would indicate the completion of the cycle stage), part of the cation exchanger remains in its original form. This can lead to the next stage of the cycle, when another starting material is introduced into the column, to contaminate the product that should be obtained at this stage.

To prevent such a situation, the method according to the first embodiment proposes at least the conversion of the Na-form of the cation exchanger to the K-form at each stage in the form of two simultaneously proceeding processes using two columns connected in series, i.e. with a total number of columns in the installation equal to four. FIG. 4 and FIG. 5a, 5b illustrate such an implementation of the method: in FIG. 4 shows the change in the ionic forms of cation exchange resin in the ion-exchange columns supplied to and removed from them solutions from stage to stage over a single cycle, and in FIG. 5a and FIG. 5b is a diagram of an apparatus for implementing the method of the first embodiment using four ion-exchange columns in two particular cases. The ion exchange columns of FIG. 4, 5a, 5b have the designations 1, 2, 3, 4. The designations of the containers 5, 6, 7, 8, 9, 10 contained in the installations coincide with those used in FIG. 2a, 2b. As in the previous figures, illustrating the change in the ionic forms of cation exchange resin, filtering or centrifuging the suspension containing the target product, and collecting in the auxiliary container the resulting filtrate or the centrifugation result used in the subsequent processing of the cation exchange resin, are indicated by the letters F and E, respectively, and are indicated by dashed lines.

In the first stage (see Fig. 4), the indicated two columns, in which the operation including reaction (1) takes place in the form of two simultaneously proceeding processes, are columns 1 and 2. In column 1 (the first along the solution flow) the layer the cation exchanger is in mixed Na, K-form, and in column 2 following it, in pure Na-form. When the solution of the first starting material — potassium chloride — is sequentially passed through such a pair of columns, the cation exchanger in column 1 must completely transfer to the K-form no later than at the moment of the “leakage” of potassium ions through the cation exchanger layer in column 2 (the moment of the appearance of analytically detectable concentration of potassium chloride at the exit of the second column).

In the first process of operation (1), proceeding in column 1, cation exchange resin having a mixed Na, K form is treated with the first starting material (KCl). The resulting solution is fed into column 2. In column 2, the second process of this operation proceeds - treatment with said solution of cation exchanger in this column in pure Na-form. As a result, in column 1, cation exchange resin is prepared for use in the next stage of the cycle in K-form, and in column 2, cation exchange resin having mixed Na, K-form is also intended for use in the next stage of the process, and the product of the operation in question is sodium chloride .

In the next stage, the same operation will be carried out in another pair of columns, namely in columns 2 and 4 (see line 2 in the table in Fig. 4), which has the same combination of cation exchange forms as columns 1 and 2 in the previous stage.

In FIG. 5a illustrating a hardware embodiment of a method whose cycle steps are shown in FIG. 4, in addition to columns 1, 2 and 3 shown in FIG. 2a, 2b, column 4 is introduced. The remaining symbols in this figure coincide with those used in FIG. 2a, 2b. By switching the corresponding valves, four alternating stages of the duty cycle are provided. At each of them, the operation, including the reaction (1), is performed in two series-connected columns from among the four. At the stage corresponding to those shown in FIG. 5a to open valves, this operation is carried out in columns 1 and 2, the operation including the reaction (2) with the conversion of cation exchanger to the H-form and the desired product in the column 3, and the operation including the reaction (3) with the neutralization of H- forms of cation exchanger with soda solution in column 4.

It is easy to notice that for the implementation of the method as a whole, if it contains an operation carried out in the form of two simultaneously proceeding processes, not only one column, but even two columns is not enough, because the composition of the pair of columns in which the method operation is carried out is carried out in it is different in different stages: at the first stage these are columns 1 and 2, at the second stage - columns 2 and 4, at the third - 4 and 3, at the fourth - 3 and 1.

The installation, the circuit of which is shown in FIG. 5b, compared with the installation of FIG. 5a is supplemented with lines and switching elements that allow washing the columns with water at the end of each stage of the cycle, followed by its displacement with a solution supplied to the column for processing the cation exchanger in the column at the next stage. A feature of washing in this case is that the column in which the cation exchange resin is in mixed Na, K-form is not washed. At the same time, at the next stage, the solution leaving this column displaces water from the column connected in series with it, containing cation exchange resin in pure Na form.

At the beginning of the next stage, water is displaced from the remaining columns by the starting material specific for the operation carried out in the column. For example, before the start of the second stage (see Fig. 4), column 2 is not washed, and at the beginning of the second stage, the water remaining in it after washing, during which the extruded soda solution.

The state of the valves in FIG. 5b corresponds to the process of displacing water from columns that were washed after the end of the fourth and before the first stage, when column 1 was not washed. In this case, water is displaced from the remaining columns: from column 2 - with a solution leaving column 1 into which potassium chloride is fed from capacity 5; from column 3 — a solution of phosphoric acid supplied from tank 7; from column 4 — a soda solution supplied from tank 9. The displaced water enters the tank 10 for recycled water.

After completing the described procedures for washing and displacing water (see, for example, the line of Fig. 4, corresponding to the second stage), a suspension containing the target product — KH ₂ PO, resulting from the interaction with the feed solution of H ₃ PO ₄ located in this column of cation exchanger in pure K-form, the layer of which is in a state of fluidization. Next, the above-described processes of filtering or centrifuging this suspension and collecting the filtered or centrifuged suspension in auxiliary vessel E followed by acid replacement at the inlet of the column and continuing processing of the cation exchange resin supported in a fluidized state in a circulating mode, ending with transferring the finished target product to the one intended for its capacity is 8.

Water starts to come out of column 3, which is supplied to vessel 10, and from column 4, sodium chloride enters into vessel 6.

All of the above relates to the implementation of the method according to the first embodiment, using any other oxygen-containing acid as the second starting material.

So, when using sulfuric acid instead of operation (2) in the above set of reactions, reaction (4) is carried out:

and get as the target product potassium sulfate.

When using nitric acid instead of reaction (2) in the above set of reactions, reaction (5) is carried out:

and get potassium nitrate.

When using extraction phosphoric acid as the second starting material, it is advisable to preliminarily purify the latter by the sorption method of acid retention, for example, by the NewKem method [13, 14], or by the extraction method using organic reagents [11].

When implementing the proposed method according to the second embodiment, operations are carried out in which, for example, the following ion-exchange reactions occur:

- the same as in the method according to the first embodiment, the conversion of the initial Na-form of cation exchanger to the K-form using the first starting material - a solution of potassium chloride and to obtain a solution of sodium chloride:

- processing the obtained K-form of cation exchange resin for conversion to the NH ₄ form using a solution of non-potassium salt of chlorine-free oxygen-containing acid as the second starting material, in this particular case, ammonium nitrate (ammonium nitrate), to obtain the target product - potassium nitrate:

- the conversion of the obtained NH ₄ form of cation exchange resin to the H-form using a solution of chlorine-free oxygen-containing acid as the third starting material, different from the one whose salt solution is the second starting material, in this particular case, extraction phosphoric acid, to obtain an additional product - monoammonium phosphate (MAF):

- similar to that carried out in the method according to the first embodiment, the conversion of the H-form of cation exchanger back to the Na-form when it is treated with a solution of soda ash, which is an additional starting material, to produce water and carbon dioxide:

or with obtaining water - when treated with a solution of sodium alkali as an additional starting substance:

As a result of a set of operations, including carrying out reactions (1), (6), (7) and (3) or (3 '), from a relatively cheap and affordable starting materials: potassium chloride, ammonium nitrate and phosphoric acid, valuable chlorine-free potassium mineral is obtained fertilizer - potassium nitrate, as well as an additional, also valuable product - monoammonium phosphate. When these products are added together, nitroammophosk is obtained - one of the most valuable complex mineral fertilizers.

As in the method according to the first embodiment, for example, gel carboxyl cation exchanger type KB-4P-2 or macroporous carboxy cation exchanger type Lewatit CNP-80 can be used as cation exchanger. The use of weakly acidic cation exchanger, which is each of these, is due to the fact that for the effective implementation of operations (3) or (3 '), the cation exchanger must have the highest selectivity to hydrogen ions compared to other cations of the starting materials used in the method.

The proposed method according to the second embodiment, in principle, can be implemented in a single ion-exchange column, carrying out successive stages in it, representing operations with these four reactions. However, to increase the productivity of the process and ensure the continuity of obtaining the target product, it is advisable to use several columns in such an organization of the cyclic process, when different operations are carried out simultaneously in different columns. In the four stages to which the above reactions correspond, four columns are sufficient for such a process organization.

The change in the ionic forms of cation exchange resin in the ion-exchange columns supplied to and removed from them from stage to stage during the cycle of the method according to the second embodiment in four ion-exchange columns is illustrated in FIG. 6, and the installation diagram in which this method can be implemented is FIG. 7. The four ion exchange columns mentioned in the diagram of FIG. 7 and in FIG. 6 are designated 21, 22, 23, 24. As in the previous figures, illustrating the change in the ionic forms of cation exchange resin in the method according to the first embodiment, the method according to the second embodiment is carried out by filtration or centrifugation of a suspension containing an additional target product, and collection in the auxiliary container of the filtrate or the centrifugation result used in the subsequent processing of the cation exchanger are indicated by the letters F and E, respectively, and are indicated by dashed lines.

Before the start of each stage of the cycle, the ionic forms of cation exchange resin in different columns must be different, for example, before the start of the first stage in FIG. 6 in column 21, the cation exchanger must be in Na form; in column 22, in K-form; in column 23, in NH ₄ form; and in column 24, in H-form. Then, in these columns, it is possible to simultaneously carry out operations with reactions (1), (6), (7), (3), respectively. In the next stage, operations with reactions (6), (7), (3), (1), respectively, can be carried out simultaneously in the same columns; at the next stage, operations with reactions (7) (3), (1), (6), respectively; then, operations with reactions (3), (1), (6), (7), respectively, followed by operations with a combination of reactions (1), (6), (7), (3), etc.

The hardware embodiment of the proposed method according to the second embodiment is illustrated in FIG. 7, which shows a diagram of an installation for implementing the method, allowing to organize the process of FIG. 6. The designations used in this figure, along with the designations 21, 22, 23, 24 for the ion exchange columns already mentioned, partially coincide with the designations in FIG. 2a, 2b, 5a, 5b and have the following meaning:

5 - capacity for the first starting substance - a solution of potassium chloride;

6 - a capacity for collecting a solution of sodium chloride;

7 is a container for oxygen-containing acid, which in this case is, in contrast to the schemes of FIG. 2a, 2b, not the second, but the third starting material;

9 - capacity for an additional initial product - a solution of soda ash or sodium alkali;

10 - a container for water;

11 is a container for an oxygen-containing salt (in this case, ammonium nitrate), which is the second starting material;

12 - capacity for collecting a suspension containing the target product is potassium nitrate;

13 - capacity for collecting additional target product - monoammonium phosphate (MAP);

Ф - filter or continuous centrifuge;

E - auxiliary capacity for collecting the obtained filtrate or the result of centrifugation;

H is the pump.

The specified combination of starting and obtained products corresponds to a particular case in which the above reactions (1), (6), (7), (3) are performed.

Shown in the diagram of FIG. 7, the state of the valves corresponds to the first stage of the duty cycle (first line in FIG. 6), in which:

- the ion exchange column 21 is in the transmission mode of the first starting material - a solution of potassium chloride supplied from the tank 5, and the conversion of the cation exchange resin, which is in the Na-form, in the K-form to obtain a solution of sodium chloride entering the tank 6;

- column 22 - in the transmission mode of a solution of ammonium nitrate, which is the second starting material supplied from the tank 11, and the conversion of the cation exchange resin, which is in the K-form, in the NH ₄ form to obtain a solution of the target product entering the tank 12;

- column 23 — in the transmission mode of the acid solution, which is the second starting material supplied from the tank 7, and the conversion of the cation exchanger, which is in the NH ₄ form, into the H-form, to obtain an additional target product — monoammonium phosphate, which ultimately arrives into the container 13;

- column 24 - in the transmission mode of the solution of soda ash supplied from the tank 9, and the conversion of cation exchange resin, which is in the H-form, in the Na-form to obtain water entering the tank 10, and carbon dioxide.

In the diagram of FIG. Figure 7 shows preferred directions for passing solutions through columns from bottom to top. The same directions are shown in FIG. 6.

At the beginning of the next (second) stage, cation exchange resin in columns 21-24 is in the above ionic forms into which it is converted: potassium; ammonium (i.e., in the ionic form of a non-potassium salt cation, a solution of which is used as the second starting material); hydrogen; sodium. At this stage, as shown in FIG. 6, respectively, solutions are supplied to the columns: ammonium nitrate; acid, which is the second starting material; soda ash; potassium chloride.

Then, the solution supplied to each of the columns is continued from stage to stage, so that the same solution is fed into the same column periodically every four stages that form a cycle.

When passing a solution of non-potassium salt of a chlorine-free oxygen-containing acid, in this particular case, ammonium nitrate through a column with a potassium form of cation exchange resin, a suspension containing a solution of the target product, potassium chlorine-free fertilizer, is obtained at the outlet of the column.

This suspension in the presence of impurities in it, due to the presence of those in the starting materials, can be separated by filtration or centrifugation, not shown in the drawings.

By passing a solution of chlorine-free oxygen-containing acid, different from the one whose salt solution is fed into a column with cation exchange resin in K-form (in this particular case, extraction phosphoric acid), a suspension containing an additional target product is obtained through a column with cation exchange resin in the NH ₄ form (in this particular case - a solution of monoammonium phosphate). This operation is carried out using the calculated volume of the indicated acid, which, when reacted with a known amount of cation exchange resin in the NH ₄ form in the column, allows monoammonium phosphate to be obtained in accordance with reaction (7). The suspension subjected to filtration or centrifugation in the appropriate medium F is collected in auxiliary vessel E and then it is fed to the column inlet instead of the extraction phosphoric acid solution, while continuing to process the cation exchange resin in a circulating mode along the circuit: column — continuous filter or centrifuge (Ф) - auxiliary capacity E - pump H - column. Both the acid solution and the contents of the vessel E are passed through the column at a rate that ensures fluidization of the cation exchanger layer contained therein. After such processing and the subsequent filtration or centrifugation of the resulting suspension are carried out several times, the purified suspension, which is a ready-made additional target product, is sent from auxiliary tank E to tank 13 to collect such a product. In this case, cation exchanger in the column is in the H-form in accordance with reaction (6).

When a solution of soda ash is passed through a column with a hydrogen form of cation exchange resin, water is obtained at the outlet, a container 10 is intended for collection (Fig. 7), and when a solution of potassium chloride is passed through a column with a sodium form of cation exchanger, a solution of sodium chloride is obtained at the outlet.

It is advisable to rinse the columns after each ion exchange operation in them, because after the end of each stage of the cycle, in each column, the cation exchange resin of which has changed to another ionic form, there is an electrolyte solution with which it was converted to this ionic form. For example, in a column that is converted to K-form, between the grains of cation exchanger (in the porous space), and also above and (or) below the cation exchanger layer there will be a solution of potassium chloride. Flushing may be carried out in a plant having a circuit similar to that shown in FIG. 7, supplemented by switching valves and lines connecting the columns with a tank 10, which becomes in this case a tank for recycled water.

Since after washing at the beginning of the next stage there is water in each column, the latter is forced out of the column by passing through it a solution, which for each column is the starting material supplied to it at the next stage.

After completing the described procedures for washing and displacing water (see, for example, the line of Fig. 6, corresponding to the first stage) from the column 21 with cation exchange resin in the Na form during the operation including reaction (1), a solution of sodium chloride begins to come out; from the column 22 with cation exchange resin in the K-form during the operation including reaction (6), a suspension containing potassium nitrate; from the column 24 with cation exchange resin in the H-form during the operation, including reaction (3), water. A suspension containing an additional target product, monoammonium phosphate, which is the result of interaction with the supplied solution of H ₃ PO ₄ contained in the column of cation exchange resin in the NH ₄ form, the layer of which is in a state fluidization. Next, the above-described processes of filtering or centrifuging this suspension and collecting the filtered or centrifuged suspension in auxiliary vessel E followed by acid replacement at the inlet of column 23 and continuing processing of the cation exchange resin supported in a fluidized state in a circulating mode, ending with transferring the finished additional target product to capacity for it 13.

Subsequently, during all operations, as in the first stage, the solutions of the starting materials are supplied: from the tank 5 for the first starting material - a solution of potassium chloride; from a container 11 for an oxygen-containing salt, which is the second starting material; from a container 7 for oxygen-containing acid, which is the third starting material; from the tank 9 for an additional source substance - a solution of soda ash or sodium alkali.

Liquids resulting from ion exchange reactions are supplied respectively: into a container 6 for collecting a solution of sodium chloride; in a container 12 for collecting the target product - potassium nitrate; in the tank 13 to collect additional target product - monoammonium phosphate; in a tank 10 for recycled water.

In the second variant of the proposed method under consideration, other combinations of the oxygen-containing salt and oxygen-containing acid, which are the second and third starting materials, are possible than the above. So, when using sulfuric acid instead of phosphoric acid as the third starting material, the third operation in the above combination, i.e. operation (7) is replaced by operation (8):

and the result is potassium nitrate and ammonium sulfate.

When using ammonium sulfate instead of ammonium nitrate as the second starting material, the second operation in the above combination, i.e. operation (6) is replaced by operation (9):

and the result is potassium sulfate and monoammonium phosphate.

When monoammonium phosphate and sulfuric acid are used as the second and third starting materials, respectively, the second and third operations in the above combination, i.e. operations (6) and (7) are replaced by operations (10) and (8):

and get more valuable monopotassium phosphate and ammonium sulfate.

The proposed method according to the second embodiment includes all of the above when considering the method according to the first embodiment with respect to the influence of stretched fronts along the columns (see Fig. 3 and related text). To prevent the negative consequences of this phenomenon in the method according to the second embodiment, as in the method according to the first embodiment, it is possible to carry out separate ion exchange operations at each stage in the form of two simultaneously proceeding processes using two series-connected columns in plants containing an increased number of ion-exchange columns. The number of columns increases by the number of operations carried out in this way. This accordingly increases the number of stages in each cycle of the cyclic process, which is the proposed method.

In FIG. Figure 8 shows a diagram of an installation containing five ion-exchange columns and designed to carry out a cyclic process in which a set of operations is carried out, including reactions (1), (3), (6), (7), with the first of them being carried out in the form of two simultaneously proceeding processes using for her two series-connected columns. With the exception of position 25 of the fifth ion exchange column, all symbols in FIG. 8 coincide with the symbols in FIG. 7. Shown in FIG. 8, the state of the valves corresponds to the first of five stages, in which operations, including reactions (1), (6), (7), (3), are carried out respectively in ion-exchange columns: 21 and 22; 23; 24; 25.

The change in the ionic forms of cation exchanger in the ion-exchange columns supplied to and removed from them solutions from stage to stage when implementing the method using the installation of FIG. 8 is shown in FIG. 9. In this figure, as in the previous figures, illustrating the change in the ionic forms of cation exchange resin, filtering or centrifuging a suspension containing an additional target product, and collecting in the auxiliary container the resulting filtrate or centrifugation result used in the subsequent processing of cation exchange resin instead of acid, are indicated, respectively letters F and E and are indicated by dashed lines.

As already mentioned, in the case illustrated in FIG. 8 and 9, one of the operations is carried out in the form of two simultaneously proceeding processes using two series-connected columns, and such an operation is an operation involving a solution of potassium chloride as the first starting material of the cyclic process, which is the proposed method.

When carrying out this operation in the first of these two processes, the solution is treated with a solution of potassium chloride of cation exchange resin, which is located in the ion exchange column 22 in mixed Na, K form before the start of this operation. This cation exchange resin is treated with a potassium chloride solution supplied to column 22, and the solution exiting from it is fed into column 21. The cation exchange resin in column 22 is converted to pure K-form, and the cation exchange resin in column 21, which was in pure Na form before starting this operation goes into a mixed Na, K-form. The indicated change in the forms of cation exchange resin as a result of the described operation can be seen by comparing lines 1 and 2 of FIG. 9, corresponding to the first and second stages of the method. The result of this operation is a solution of sodium chloride at the outlet of the column 21, which is sent to a container 6 (Fig. 8).

In the installation for implementing the proposed method according to the second embodiment using the five ion-exchange columns of FIG. 8, it may be possible to flush the columns with water after the completion of each stage, for which this installation must be supplemented with switching valves and lines connecting the columns to a tank 10, which in this case becomes a tank for recycled water. All columns must be flushed, the cation exchange resin in which, after the completion of the stage, is in pure ionic form.

So, for example, in the first stage of the cycle, in the operation, carried out in the form of two simultaneously proceeding processes, a pair of columns 21 and 22 is used. Column 21, in which the cation exchanger, after completion of this stage, goes into a mixed ionic form (see Fig. 9), before the beginning of the next (second) stage is not washed.

The proposed method according to the first embodiment was carried out in laboratory conditions (examples 1-5) and in a pilot installation (example 6).

Example 1

To implement the method, three ion-exchange columns were used according to the scheme of FIG. 2b, loaded with 100 ml of a layer of carboxyl cation exchanger KB-4P-2 (initially - in the Na form). We used a 20% solution of potassium chloride of qualification “Technical”, 14.9% solution of purified extraction phosphoric acid (EPA) produced by the Belorechensk Mineral Fertilizer Plant, 5% solution of calcined soda of qualification “Technical”.

At the preparatory stage, EPA was purified in accordance with the method according to the patent [12] to obtain purified acid, the composition of which is presented in table 1.

Then the columns were prepared: the cation exchange resin in columns 2 and 3 was converted to the K-form by parallel passing through each of them 140 ml of potassium chloride solution (from the bottom up) from the tank 5 at a rate of 180 ml / h. In this case, the first portions of the liquid leaving the columns, which is water, located there in a free volume (40 ml in each column) were sent to a container of 10, then the next portions of 100 ml of sodium chloride solution leaving the columns (mixed with potassium chloride) sent to tank 6. Next, 40 ml of water was passed through each column from tank 10 (top to bottom) at the same speed, displacing a solution of potassium chloride (40 ml) from free volumes and returning it to tank 5. All these operations take 60 minutes time.

In addition, the cation exchanger in column 3 was converted to the H form by passing extraction phosphoric acid through it. The last operation was carried out as follows: 200 ml diluted 1.4 times (up to 14.9%) of purified acid were poured into a container 7 (Table 1) and the indicated volume was pumped from bottom to top through column 3, so that 40 ml of water in free the volume of the column, it fell into the tank 10, and 160 ml of the suspension through the filter F and the filtrate - then into the tank E. The pumping rate was kept at 600 ml / h. Under these conditions, due to the high density of the transmitted solution, the bed became fluidized, and the pumping time was 20 min. Without stopping the pumping, the valves and working pumps were switched (Fig. 2b) so that for another 20 minutes they pumped at the same flow rate in a circular pattern from tank E back to the same tank. Then the valves were switched so that the volume of the solution of the obtained target product equal to 150 ml was pumped into the tank 8 for the target product. Then, 50 ml water was supplied from column 10 to column 3 (at the same speed, but from top to bottom), and the product solution displaced from the column (50 ml) was supplied to container 8. All these operations for converting column 3 into the H form took 60 min After these operations, the state of the columns corresponded to that shown in the first row of FIG. one.

Then, a working cycle of three stages was carried out with passing through the columns solutions of the starting materials (potassium chloride, purified EPA and soda ash) with alternating columns and the solutions supplied to them in accordance with FIG. 1, washing the columns with water at the end of each stage and displacing the water at the beginning of each subsequent stage with the starting material intended for use in this stage.

A solution of 5% soda (total 900 ml) from the tank 9 was passed through the appropriate columns in a bottom-up direction at a speed of 950 ml / h. In this case, the first portion of 50 ml of liquid leaving the column (water from the free volume) was sent to a tank 10 for circulating water, and the rest was directed to the addition and preparation of a soda solution (not shown in the diagram of Fig. 2b). At the end of these operations, water was passed from tank 10 in a downward direction (at the same speed) through an appropriate column and a solution of unspent soda was displaced, a total of 40 ml and returned to tank 9. All these operations took 1 hour.

The modes and transmission rates of the starting materials remained as described above, except that the potassium chloride solution was not passed through two columns in parallel, but only through one column at each stage of the cyclic process.

During each operation of transferring cation exchange resin from the H-form to the Na-form, its layer expanded from 60 ml to 100 ml, the free volume of the liquid in the column changed from 50 ml to 40 ml.

During each operation of transferring cation exchange resin from the K-form to the H-form, its layer was compressed from 100 ml to 60 ml, the free volume of the liquid in the column changed from 40 ml to 50 ml.

In the conversion operations from the Na form to the K form, the volume of the cation exchanger layer and the free volume of liquid in the column did not change.

At each of the three stages of the stage, a suspension containing MCP was obtained (respectively, at the exit of the second, first and third columns). The suspension containing MCP collected during each stage was evaporated, the precipitates were dried, and their solubility, as well as their impurities, were checked.

Data on the chemical composition and solubility obtained in three successive stages of monopotassium phosphate are presented in table 2.

The results shown in table 2 correspond to the parameters of the best foreign samples of instant MKF.

Example 2

The preparatory and working steps were carried out analogously to example 1, except that a macroporous weakly acidic cation exchanger with carboxyl functional groups Lewatit CNP 80 (LanXess, Germany) was used. After the completion of each stage and subsequent operations on evaporation, separation and drying of the precipitates, solid, completely soluble products were obtained (MKF with a solubility of at least 230 g / l at 25 ° C) containing not less than 34% K ₂ O and in total not more than 0.02 % calcium, magnesium and iron.

Example 3

The preparatory and working steps were carried out similarly to examples 1 and 2, except that they used a porous weakly acid cation exchanger with carboxyl functional groups Purofine PFC 104 Plus (Purolite, United Kingdom, USA). After the completion of each stage and subsequent operations, solid completely soluble products were obtained (MKF with a solubility of at least 230 g / l at 25 ° C) containing not less than 34% K ₂ O and in total not more than 0.02% calcium, magnesium and iron.

Example 4

The preparatory and working stages were carried out similarly to examples 1 and 2, except that instead of purified extraction phosphoric acid, technical non-concentrated nitric acid of the 2nd grade (GOST R53789-2010) having the composition: HNO ₃ - 46% was used as the starting material. ; the residue after calcination (insoluble impurities) is 0.05%, previously diluted with water with a salinity of not more than 50 mg / l and a content of hardness salts of not more than 0.01 mEq / l, to a concentration of 18.4%. As the target product, potassium nitrate was obtained.

The content of components in the resulting combined product after three stages and solubility are presented in table 3.

Example 5

The preparatory and working processes were carried out as described in example 1, except that instead of purified extraction phosphoric acid (EPA), technical sulfuric acid (GOST 2184-77) of the sort "Tower" acid of the following composition was used: H ₂ SO ₄ - 76% ; iron - 0.05%; the residue after calcination (insoluble impurities) is 0.3%. The acid was diluted 10 times with water with a salinity of not more than 50 mg / l and a hardness salt content of not more than 0.01 mEq / l, to a concentration of 7.6%.

In the working cycle, the transmission rate of the diluted sulfuric acid solution was 225 ml / h (1.5 times higher than for EPA in example 1), the transmission rate of the soda solution was 500 ml / h.

The content of components in the resulting product and solubility are presented in table 4.

Example 6

When implementing the method according to the first embodiment, four ion-exchange columns according to the scheme of FIG. 5b, having a volume of 1 m ³ , filled with KB-4 carboxyl cation exchanger in commercial H-form, 600 l of layer in each column. Used a 20% solution of potassium chloride qualification "Technical" - the first starting material; 14.9% solution of extraction phosphoric acid, purified in accordance with the method according to the patent [12] - the second starting substance; 5% solution of soda ash qualification "Technical" - additional starting material.

At the preparatory stage, cation exchange resin in all columns except column 4 (Fig. 5b) was individually converted to the Na form by treatment with a soda solution. Then, through a series of columns connected in series 3 and 1, a solution of potassium chloride was passed, while the cation exchange resin in column 3 was converted into K-form, and in column 1 into mixed Na, K-form.

The transmission modes of soda solutions and starting materials were maintained as described in Example 1, except that the flow rates and pumped volumes were 4 orders of magnitude higher.

As a result, after completion of the preparatory stage, the cation exchanger in the columns was in the ionic forms shown in FIG. 4 in the first line corresponding to the beginning of the first stage of the cyclic process according to the first embodiment of the proposed method in the particular case when one of its operations is carried out in the form of two simultaneously proceeding processes:

- in column 1 - in mixed Na, K-form;

- in column 2, in the Na form;

- in column 3 - in K-form;

- in column 4 - in the H-form.

Then, a four-stage work cycle was carried out with passing through the columns solutions of the starting materials (potassium chloride, extraction phosphoric acid, soda ash) with alternating columns and the solutions supplied to them in accordance with FIG. 4 and washing the columns at the end of each stage, except for the column in which the cation exchange resin has transferred to the mixed ionic form (for example, after the end of the first stage, except for column 2).

Modes for each of the stages of the working cycle:

- the operation of treating a solution of potassium chloride with cation exchange resin in two successive columns (the first column along the stream in mixed Na, K-form, the second in Na-form) was carried out by passing through them 1400 l of potassium chloride solution (from the bottom up) capacity 5 with a speed of 1800 l / h. In this case, the first portions of the liquid leaving the second column, which is water, located there in a free volume (total 400 l) were sent to the tank 10, then the next portion of 1000 l of the pure sodium chloride solution leaving the tail column was sent to the tank 6. Next 400 L of water from the tank 10 (top to bottom) were passed through the front column, which passed into the K-form, from the top at the same speed, displacing the potassium chloride solution (400 L) from the free volume and returning it to the tank 5;

- a solution of 5% soda (total 9000 l) from the tank 9 was passed through the corresponding column in the direction from the bottom up with a speed of 9500 l / h. In this case, the first portion of 500 l of liquid leaving the column (water from the free volume) was sent to a tank 10 for circulating water, and the rest was directed to the strengthening and preparation of a soda solution (not shown in Fig. 8). At the end of these operations from the tank 10 in the direction from top to bottom (at the same speed), water was passed through the corresponding column and the solution of unspent soda was displaced, a total of 400 l, and returned to tank 9;

- passing extraction phosphoric acid through any of the columns at the appropriate stage was carried out as follows: from the tank 7, 2000 l of 14.9% purified EPA were pumped from the bottom up through the column, so that 400 l of water in the free volume of the column fell into the tank 10, and 1600 l of suspension — through filter F and then — filtrate — into tank E. The pumping rate was kept at 6000 l / h. Under these conditions, the bed became fluidized. Without stopping the pumping, the valves and the working pumps were switched (in accordance with the diagram of Fig. 5b) so that pumping was carried out for 20 minutes at the same flow rate in a circular pattern from tank E back to the same tank. Then, the valves were switched so that the volume of the solution of the obtained target product, equal to 1,500 l, was pumped into the container 8 for the target product. Then, from the tank 10, 500 l of water was supplied (at the same speed, but from top to bottom), and the displaced from the column a solution of the product (500 L) was fed into a container 8.

The duration of each stage (along with washing with water) was 1 h; the transmission rate of the purified EPA solution is 6000 l / h; the transmission rate of the potassium chloride solution is 1800 l / h; the transmission rate of the soda solution is 9500 l / h. All processes were carried out at a temperature of about 30 ° C.

The composition of the product is presented in table 5.

The results presented in the table correspond to the parameters known for the best foreign instant IFF samples.

The proposed method according to the second embodiment was carried out on a pilot installation (examples 7-12).

Example 7

To implement the method, five ion-exchange columns were used according to the scheme of FIG. 8, supplemented by switching valves and lines for supplying and discharging washing water. Columns having a volume of 1 m ³ were 60% filled with KB-4 carboxyl cation exchanger (initially in the H-form).

Used:

- 20% solution of potassium chloride qualification "Technical" - the first starting substance;

- 21.2% solution of ammonium nitrate (ammonium nitrate) - the second starting substance;

- 20.8% solution of extraction phosphoric acid, purified in accordance with the method according to the patent [12] (Table 1) - the third starting substance;

- 5% solution of soda ash qualification "Technical" - additional starting material.

At the preparatory stage, cation exchange resin in all columns except column 25 (Fig. 8) was individually converted to the Na form by treatment with a soda solution.

Then, a solution of potassium chloride was passed through two columns 24 and 25, sequentially in the direction from 25 to 24, while the cation exchange resin in column 24 was converted into K-form, and in column 23 into mixed Na, K-form. Then, through two columns 22 and 23, successively in the direction from 23 to 22, a solution of potassium chloride was passed, while the cation exchange resin in column 23 was converted into a K-form, and in column 22 into a mixed Na, K-form.

After passing after this a solution of ammonium nitrate through column 24, the cation exchange resin in it was transferred from the K-form to the ammonium form.

As a result, after completion of the preparatory stage, the cation exchanger in the columns was in the ionic forms shown in FIG. 9 in the first line, corresponding to the beginning of the first stage of the cyclic process according to the second variant of the proposed method in the particular case when one of the operations (for the exchange of potassium and sodium ions) is carried out in the form of two simultaneously proceeding processes:

- in column 21, in the Na form;

- in column 22, in mixed Na, K-form;

- in the column 23 - in the K-form;

- in column 24 — in the NH ₄ form;

- in column 25 - in the H-form.

Then, a five-stage working cycle was conducted with passing through the columns solutions of the starting materials (potassium chloride, ammonium nitrate, EPA and soda ash) with alternating columns and the solutions supplied to them in accordance with FIG. 9 and washing the columns with water at the end of each stage (except for those columns in which the cation exchange resin is in mixed ionic form before the start of the next stage, i.e., those that were the first in a pair of series-connected columns used in the operations carried out in the previous stage in the form of two simultaneously proceeding processes). So, for example, before the start of the third stage (Fig. 9), columns 21-24 were flushed and columns 25 were not flushed.

Modes and speed of transmission of solutions through the columns at each stage of the working cycle:

- a solution of 5% soda (total 9000 l) from the tank 9 was passed through the corresponding column in the direction from bottom to top at a speed of 6330 l / h. In this case, the first portion of 500 l of liquid leaving the column (water from the free volume) was sent to a tank 10 for circulating water, and the rest was directed to the strengthening and preparation of a soda solution (not shown in Fig. 8). At the end of these operations from the tank 10 in the direction from top to bottom (at the same speed), water was passed through the corresponding column and the solution of unspent soda was displaced, a total of 400 l, and returned to tank 9;

- the operation of treating a solution of potassium chloride with cation exchange resin in two successive columns (the first column along the stream in mixed Na, K-form, the second in Na-form) was carried out by passing through them 1400 l of potassium chloride solution (from the bottom up) capacity 5 with a speed of 1200 l / h. In this case, the first portions of the liquid leaving the second column, which is water, which was in the free volume there (400 l in total), were sent to a container 10; then, the next batch of 1000 l of pure sodium chloride leaving the tail column was sent to tank 6. Next, 400 l of water from tank 10 (from top to bottom) was passed through the front column, which transferred to the K-form, at the same speed, displacing the solution potassium chloride (400 l) from the free volume and returning it to the tank 5;

- passing extraction phosphoric acid through any of the columns at the appropriate stage was carried out as follows: 1335 l of 20.8% purified EPA were pumped from tank 7 (see table 1) from bottom to top through the column so that 400 l of water in the free volume of the column , fell into a container of 10, and 935 l of suspension through a filter F and then the filtrate into a container E. The pumping rate was kept at 4005 l / h. Under these conditions, the cation exchanger layer became fluidized. Without stopping the pumping, the valves and operating pumps of the installation were switched according to the scheme of FIG. 8, that pumping was carried out at the same flow rate in a circulating mode from tank E back to the same tank for 31 minutes. Then the valves were switched so that the volume of the solution of the obtained target product equal to 935 l was pumped into the tank 13 for an additional target product. Then, from a container 10, water (500 l) was fed into the column (at a rate of 1200 l / h, but from top to bottom), and the product solution displaced from the column (500 l) was supplied to container 8;

- the operation of processing each of the columns in the K-form with a 21.2% solution of ammonium nitrate at the appropriate stages was carried out as follows: 1486 l of ammonium nitrate solution (from the bottom up) was pumped through it from the tank 11 at a speed of 1257 l / h. In this case, the first portions of the liquid leaving the columns, which is water, located there in a free volume (400 l), were sent to a container 10, then, the next portions of 1085 liters of a solution of potassium nitrate leaving the column (mixed with potassium chloride) were sent to a container 12. Then 400 l of water were passed through the column from the tank 10 (from top to bottom) at the same speed, displacing the solution of ammonium nitrate (400 l) and returning it to the tank 11.

During each operation of transferring cation exchange resin from the H-form to the Na-form, its layer expanded from 600 L to 1000 L, the free volume of the liquid in the column varied from 500 L to 400 L.

During each operation of transferring cation exchange resin from the K-form to the H-form, its layer was compressed from 100 l to 60 l, the free volume of the liquid in the column varied from 40 l to 50 l.

In the conversion operations from the Na form to the K form, the volume of the cation exchanger layer and the free volume of liquid in the column did not change.

The duration of each stage (together with washing with water) was 1 h 30 min;

The composition of the obtained products are presented in table 6.

The presented results correspond to the parameters known for the best foreign samples of instant KNO ₃ and MAF.

Example 8

All operations were carried out in accordance with example 7, except that they used a macroporous weakly acid cation exchanger with carboxyl functional groups Lewatit CNP 80 (LanXess, Germany). Solid completely soluble products were obtained: KNO ₃ with a solubility of 450 g / l at 20 ° C, practically free of impurities, and monoammonium phosphate (MAP) with a solubility of at least 330 g / l at 20 ° C) containing at least 62% P ₂ About ₅ and a total of not more than 0.002% of calcium, magnesium and iron.

Example 9

All operations were carried out in accordance with example 7, except that they used a gel weak acid cation exchanger with carboxyl functional groups Amberlite IRC 86 RF 80 (Rohm and Haas, USA). Solid completely soluble products were obtained: KNO ₃ with a solubility of 450 g / l at 20 ° C, practically free of impurities, and monoammonium phosphate (MAP) with a solubility of at least 330 g / l at 20 ° C) containing at least 61.9% P ₂ About ₅ , 12% ammonium nitrogen and a total of not more than 0.0015% calcium, magnesium and iron.

Example 10

All operations were carried out in accordance with Example 7, except that instead of a 21.2% solution of ammonium nitrate, a 17.5% solution of ammonium sulfate was used. During the workflow, two products were obtained: potassium sulfate and monoammonium phosphate. The characteristics of the resulting products are shown in table 7.

Example 11

All operations were carried out in accordance with example 7 except that instead of a 25% solution of purified extraction phosphoric acid, a 25% solution of sulfuric acid was used. In the course of the workflow, two highly pure instant products were obtained: potassium nitrate (KNO ₃ ) and ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) with a total impurity content of not more than 0.001% in each of them.

Example 12

All operations were carried out in accordance with example 7 except that instead of a 21.2% solution of ammonium nitrate, a 24% solution of ammonium dihydrogen phosphate (MAP) was used, and instead of a 25% solution of purified extraction phosphoric acid, a 20% solution of sulfuric acid was used. In addition, the transmission rate of the solutions was chosen equal to 1.55 m ³ / h (instead of 1.25 m ³ / h). During the performance of all operations of the working process, two highly pure instant products were obtained: monopotassium phosphate (MKF) with a total impurity content of not more than 0.01% and ammonium sulfate (NH ₄ ) ₂ SO ₄ ) with a total impurity content of not more than 0.001%.

Information sources

1. Pozin M.E. Technology of mineral fertilizers, L., "Chemistry", 1989, 352 p.

2. RF patent №2164494, publ. 03/27/2001.

3. RF patent No. 2261222, publ. 09/27/2005.

4. US Patent No. 7601319, publ. 10/13/2009.

5. Chemical technology of inorganic substances / Ed. T.G. Akhmetova, in two books, M., "Higher School", 2002, Prince. 1, 688 s.

6. RF patent No. 2369585, publ. 10/10/2009.

7. US Patent No. 3393044, publ. 07/16/1968.

8. US Patent No. 4836995, publ. 06/06/1989.

9. Copyright certificate of the USSR No. 1248650, publ. 08/07/1986.

10. RF patent No. 2201414, publ. 03/27/2003.

11. RF patent No. 2452685, publ. 06/10/2012.

12. RF patent No. 2544731, publ. 03/20/2015.

13. RF patent No. 2434679, publ. 11/27/2011.

14. Khamizov R.Kh. Sorption method of "acid retention". Some technological possibilities for the separation of electrolytes. Sorption and chromatographic processes. 2013.V. 13. Vol. 5.P. 600-604.

Claims (26)

1. The method of producing soluble chlorine-free potash fertilizers, which is a cyclic process, which involves performing in each cycle a sequence of operations that are ion exchange reactions carried out in one or more ion-exchange columns using each layer of the same cation exchange resin, which is located before all each operation in ionic form for this operation, each operation includes the treatment of cation exchange resin with a solution, which is the starting material of the specified cyclic the process for this operation, obtaining the product of this operation and transferring the cation exchange resin into another ionic form for the next operation of the specified sequence, while one of the operations of the specified sequence includes processing the cation exchange resin, which is in the Na-form before starting this operation, with a solution of potassium chloride as the first initial substances of the specified cyclic process, the conversion of cation exchanger to the K-form and obtaining a solution of sodium chloride, characterized in that as cation exchanger, the same for all carried out in In this cyclic process of operations, a weakly acidic cation exchange resin is used, after the mentioned operation, which includes treating the cation exchange resin with a potassium chloride solution, an operation is carried out with the participation of a chlorine-free oxygen-containing acid solution as the second starting material of the cyclic process, including processing of the cation exchange resin obtained in the previous operation in the K form , the layer of which is maintained in a fluidized state, with its translation in the H-form and obtaining a suspension containing the target product in de potassium salt of the indicated chlorine-free oxygen-containing acid, as well as filtering or centrifuging the resulting suspension to purify it from sparingly soluble impurities, then continue to process the cation exchange resin in the specified fluidized bed, using the resulting suspension, filtered or centrifuged, and repeat this treatment and subsequent filtration or centrifugation of the resulting suspension several times, then an operation is performed with the participation of an additional initial of the substance of the indicated cyclic process in the form of a solution of sodium alkali or soda ash, which is used to process the cation exchange resin obtained in the previous operation in the H-form, converting it into the Na-form for the first of these operations and thereby creating the possibility of the cyclical continuation of the specified process. 2. The method according to p. 1, characterized in that as a second starting material of the indicated cyclic process, a solution of technical sulfuric acid is used, including contact, tower and regenerated, and a suspension is obtained containing the target product in the form of potassium sulfate. 3. The method according to p. 1, characterized in that as the second starting material of the indicated cyclic process, a solution of nitric acid extract obtained by nitric acid decomposition of phosphate raw materials and containing phosphoric acid mixed with nitric acid, previously purified by sorption method of acid retention, and receive a suspension, containing the target product in the form of a mixture of potassium nitrate and phosphate. 4. The method according to p. 1, characterized in that as the second starting material of the indicated cyclic process, an extraction phosphoric acid solution is used, previously purified either by the sorption method of acid retention or by the extraction method using organic reagents, and a suspension is obtained containing the target product in form of potassium phosphate. 5. The method according to any one of paragraphs. 1-4, characterized in that the cyclic process is carried out in several stages in each cycle and at each stage these operations are carried out in three simultaneously operating ion-exchange columns with the same cation exchange resin, but in three different ionic forms before the operation - Na-form, K -form and H-form, alternating from stage to stage of these ionic forms and the solutions supplied to the ion exchange columns, which are the starting materials of the indicated cyclic process for the corresponding operations. 6. The method according to p. 5, characterized in that the ratio of the transmission rates of the solutions of these starting materials through the ion-exchange columns is selected so that the moments of completion of the processing of cation exchange resin in all ion-exchange columns at each stage of the cycle coincide with each other. 7. The method according to p. 5, characterized in that at the end of each of these operations, the ion-exchange column containing the cation exchanger treated in this operation and the electrolyte remaining after this treatment are washed with water, displacing the indicated electrolyte, and the water remaining in the ion-exchange column after washing, they are displaced at the beginning of the next operation by the solution supplied to this column, which is the starting material of the indicated cyclic process for this next operation. 8. The method according to p. 7, characterized in that the ratio of the transmission rates of the solutions of these starting materials through the ion exchange columns is selected so that the moments of completion of the processing of cation exchange resin in all ion exchange columns at each stage of the cycle coincide with each other. 9. The method according to p. 5, characterized in that the operation involving a solution of potassium chloride as the first starting material of the specified cyclic process is carried out in the form of two simultaneously proceeding processes in two series-connected ion-exchange columns, using for this another ion-exchange column in addition to three indicated and carrying out in the first of these two simultaneously proceeding processes the treatment with a solution of potassium chloride of cation exchanger, which is located before the beginning of this operation in the first of the following of properly connected ion-exchange columns in a mixed Na, K-form, obtaining a solution resulting from this treatment, and converting the cation exchange resin in this ion-exchange column from the specified mixed ionic form into a pure K-form, and in the second process, the solution obtained in the first process is processed , cation exchange resin, which is located before the start of this operation in the second of these series-connected ion-exchange columns in pure Na-form, a solution of sodium chloride is obtained and cation exchange resin is transferred from the Na-form to the specified mixed u Na, K-form. 10. The method according to p. 9, characterized in that at the end of each stage, each ion-exchange column containing cation exchange resin in pure ionic form is washed with water, displacing the electrolyte in the column, and the water remaining in the column after washing is displaced with a solution, fed into the column for processing the cation exchanger located in it at the next stage. 11. The method according to p. 9, characterized in that the ratio of the transmission rates of the solutions of these starting materials through the ion exchange columns is selected so that the moments of completion of the processing of cation exchange resin in all ion exchange columns at each stage of the cycle coincide with each other. 12. A method for producing soluble chlorine-free potassium fertilizers, which is a cyclic process, which includes in each cycle a sequence of operations that are ion exchange reactions carried out in one or more ion-exchange columns using in each of them a layer of the cation exchange resin, which is identical for all operations, located before each operation in ionic form for this operation, each operation includes the treatment of cation exchange resin with a solution, which is the starting material of the specified cyclic about the process for this operation, obtaining the product of this operation and converting the cation exchanger into ionic form for the next operation of the indicated sequence, while one of the operations of the indicated sequence includes processing the cation exchanger, which is in the Na form before the start of this operation, with a solution of potassium chloride as the first substances of the specified cyclic process, the conversion of cation exchanger to the K-form and obtaining a solution of sodium chloride, characterized in that as cation exchanger, the same for all carried out in the specified the cyclic process of operations, use weakly acidic cation exchange resin, after the mentioned operation, which includes treating the cation exchange resin with a solution of potassium chloride, carry out an operation involving a solution of non-potassium salt of a chlorine-free oxygen-containing acid as the second starting material, including treatment of the cation exchange resin obtained in the previous operation with K- form with its conversion into the ionic form of the cation of the specified non-potassium salt and obtaining a suspension containing the target product in the form of feces of a salt of said chlorine-free oxygen-containing acid, then an operation is performed with the third starting material of the indicated cyclic process in the form of a solution of chlorine-free oxygen-containing acid, different from the one whose salt solution is the second starting material of the specified cyclic process, the solution obtained in the previous operation is treated with cation exchange resin in ionic in the form of a cation of said non-potassium salt, the layer of which is maintained in a state of fluidization, it is converted into the H-form and the a suspension containing an additional target product in the form of a salt formed by a cation of said non-potassium salt and an anion of chlorine-free oxygen-containing acid, the solution of which is the third starting material of this cyclic process, while filtering or centrifuging the resulting suspension to purify it from sparingly soluble impurities and then continue processing cation exchanger in said fluidized bed, using the resulting suspension subjected to filtration or centrifugation, and this treatment is repeated and the filtration or centrifugation of the resulting suspension is carried out several times, after which an operation is carried out with the participation of an additional starting material of the indicated cyclic process in the form of a solution of sodium alkali or soda ash, which is used to process the cation exchange resin obtained in the previous operation in Н- form, translating it into the Na-form for the first of the above operations and thereby creating the possibility of cyclical continuation of the specified process. 13. The method according to p. 12, characterized in that the solutions of ammonium nitrate and purified extraction phosphoric acid, respectively, are used as the second and third starting materials of the indicated cyclic process, and a suspension is obtained containing the target product in the form of a solution of potassium nitrate and a suspension containing additional product in the form of monoammonium phosphate. 14. The method according to p. 12, characterized in that the solutions of ammonium nitrate and sulfuric acid, respectively, are used as the second and third starting materials of the indicated cyclic process, and a suspension is obtained containing the target product in the form of potassium nitrate and a suspension containing an additional product in the form ammonium sulfate. 15. The method according to p. 12, characterized in that the solutions of ammonium sulfate and phosphoric acid, respectively, are used as the second and third starting materials of the indicated cyclic process, and a suspension is obtained containing the target product in the form of potassium sulfate and a suspension containing an additional product in the form monoammonium phosphate. 16. The method according to p. 12, characterized in that the solutions of monoammonium phosphate and sulfuric acid are used as the second and third starting materials of the indicated cyclic process, and a suspension containing the target product in the form of monopotassium phosphate and a suspension containing an additional product in the form of ammonium sulfate are obtained. 17. The method according to any one of paragraphs. 12-16, characterized in that the cyclic process is carried out in several stages in each cycle and at each stage these operations are carried out in four simultaneously operating ion-exchange columns with the same cation exchange resin, but in four different specified ionic forms before the operation: Na-form, K-form, the ionic form of the cation of the specified non-potassium salt, the solution of which is the second starting material of the specified cyclic process, and the H-form, alternating from stage to stage of these ionic forms and fed into the ion exchange lots of solutions, which are the starting materials of the specified cyclic process for the corresponding operations. 18. The method according to p. 17, characterized in that the ratio of the transmission rates of the solutions of these starting materials through the ion exchange columns is selected so that the moments of completion of the processing of cation exchange resin in all ion exchange columns at each stage coincide with each other. 19. The method according to p. 17, characterized in that the resulting suspension containing the specified target product is subjected to filtration or centrifugation to separate poorly soluble impurities from this product. 20. The method according to p. 17, characterized in that at the end of each stage, each ion-exchange column is washed with water, displacing the electrolyte in the column, and the water remaining in the ion-exchange column after washing is displaced at the beginning of the next operation with the solution supplied to this column , which is the starting material of the indicated cyclic process for this next operation. 21. The method according to p. 19 or 20, characterized in that the ratio of the transmission rates of the solutions of these starting materials through the ion exchange columns is selected so that the moments of completion of the processing of cation exchange resin in all ion exchange columns at each stage coincide with each other. 22. The method according to p. 17, characterized in that the operation of the specified sequence, carried out with the participation of the first starting material, or the operation carried out with the participation of the additional starting material, or both of these operations are carried out in the form of two simultaneously proceeding processes in two series-connected ion-exchange columns using in addition to the four indicated another ion-exchange column for each of these operations, the first of these processes includes the processing of the specified cyclic ocesa for this operation, cation exchange resin, located before the start of this operation in the first of the indicated series-connected ion-exchange columns in mixed ionic form and containing cation exchange resin both in ionic form for this operation and in ionic form for the next operation of the indicated sequence, obtaining a solution which is the result of this treatment, and the conversion of cation exchange resin from the specified mixed ionic form into a pure ionic form for the next operation of the specified sequence, and the second process includes processing to the solution obtained in the first process, cation exchange resin, which is before the start of this operation in the second of these series-connected ion-exchange columns in ionic form for this operation, obtaining the product of this operation and converting the cation exchange resin to the specified mixed ionic form for use in the next stage of the specified cyclic process . 23. The method according to p. 22, characterized in that in the form of two successive processes carry out an operation carried out with the participation of the first starting material of the specified cyclic process - a solution of potassium chloride, while in the first of these two processes carry out the treatment with a solution of potassium chloride of cation exchanger, located before the start of this operation in the first of two ion-exchange columns used in this operation in the first mixed ionic form and containing cation exchange resin in both Na-form and K-form, a solution is obtained that is resulting from this treatment, and the cation exchange resin is converted into a pure K-form, and in the second process it is treated with the solution obtained in the first process, the cation exchange resin, which is before the start of this operation in the second of the two ion-exchange columns used in this operation, in pure Na-form, is obtained sodium chloride and the cation exchange resin is converted to said first mixed ionic form. 24. The method according to p. 22 or 23, characterized in that the ratio of the transmission rates of the solutions of these starting materials through the ion exchange columns is selected so that the moments of completion of the processing of cation exchange resin in all ion exchange columns at each stage coincide with each other. 25. The method according to p. 22 or 23, characterized in that at the end of each stage, each ion-exchange column containing cation exchange resin in pure ionic form is washed with water, displacing the electrolyte in the column, and the water remaining in the column after washing is displaced the solution supplied to the column for processing the cation exchanger located in it at the next stage. 26. The method according to p. 25, characterized in that the ratio of the transmission rates of the solutions of these starting materials through the ion-exchange columns is selected so that the moments of completion of the processing of cation exchange resin in all ion-exchange columns at each stage coincide with each other.

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