DE2008955C3 - Process for the production of high-percentage potassium chloride from aqueous solution containing KCl, NaCl, MgSo deep 4 and MgCl deep 2, by crystallization during cooling - Google Patents

Description

3 4

According to the method of the invention, the sation of MgSO ₄ -containing double salts at or after

Vapors introduced at a different point, namely in the crystallization of the practically NaCl-free KCl crystalline

the clarified hot starting solution and this serves sats is avoided.

Another task with a different solution- Only after these inventive steps have been recognized

v.eg. Only on this new approach is it possible to abandon the method of the invention.

sometimes possible. Potassium chloride with at least 60% manure, namely the production of potassium chloride with

Κ.ρ from kieseritic potash crude salts in one stage at least 60% K ₂ O from KCI-, NaCI-, MgSO ₄ - and

without the need for a covering process. MgCl ₂ -containing solutions, ie from kieseritic

A process for the production of crude potash salts has now been solved.

high percentage potassium chlorine from KCI-. NaCl-, io The method of the invention is for example

MgSO, and MgClj-e.nthlatender aqueous solution carried out as follows:

by dissolving the potash crude salt and heating it, 330 t / h of hard salt with 12% K ₂ O are added

Mixture dissolved by means of recycled exhaust steam, separating 617 m ³ / h dissolving lye (115 ° C) from the circuit,

Dissolution of the residue from the hot water with about 621 m ³ / h of 96% KCl

96 to 98% KCI saturation present solution and 15 saturated solution (95 ° C) the following combination

Crystallization found during cooling, which settles:

characterized in that such an amount of _{2 | 4 KC} , _{7g M c} , _{72 M so 144NaC} , ₇₈₅ H ₂ O / g / l saturated water vapor (vapors) is condensed in,

In this solution, 7 m ³ / h of water are condensed in the form of recirculation of the evaporating amounts of water 20 vapors, which prevents NaCl from crystallizing out from the downstream, which means that the evaporation plant originates, so that the solution is transferred to another Heating the solution is heated up to a maximum of about 100 C. This increased temperature the boiling point occurs, and by stirring Langbeinite favors the formation of Langbeinite, which is deposited under Einais crystals, from the hot solution leading of Langbeinite crystals as seed crystals until separated, one to maintain the turbidity 25 to a turbidity density of 550 g / l, After a dwell time in the stirring apparatus, part of the amount is returned and the other part of about 10 minutes has run out of the solution and the resulting MgSO ₄ content is 9 to 10 t / h of Langbeinite deposited. In a solution that has been switched to as much clarifier as the amount of Langbeinit saturation is added, the entire Langbeinit is mixed with water, as separated to prevent the 3 ° of the solution. About 90 to 100 t / h of NaCl crystallization is necessary as seed crystals back into the process during the following vacuum cooling, then the solution is increased and 9 to 10 t / h for a sulphate or mixed dilution to 20 to 40 ⁰ C is cooled, practically carried out ger production. The clarified solution was formed with NaCl-free KCl crystals and separated and ^{added to the 12 m 3} / h of water; together with and from the cooled solution after its 35 den 7 m ³ / h of water in the form of condensed heating, the amount of water evaporates, which as vapors the solution now has the following combined vapors in a known manner in the hot, high concentration:

saturated solution is condensed. 200 KCl, 79 MgCl ₂ , 58 MgSO ₄ , 140 NaCl, 790 H ₂ O / g / l

It was also found that the stirring time for

Crystallization of Langbeinit about 5 to 30 minutes 4 ° Due to the composition of the solution, the

and the pulp density can be achieved when the task is stirred, through the following varia-

Langbeinit at temperatures between 90 and 115 C vacuum cooling with constant return of the

by recirculation of Langbeinit as seed crystals, steaming amount of water into the cooling solution

is adjusted to about 200 to 50 g / l. just crystallize out potassium chloride. In the

The mother liquor, which is concentrated by evaporation, cools down to 35 ° C, falls about 56 t / h of potassium is returned to the dissolving apparatus and the chloride in it is produced, which after its separation from the rock salt that is present becomes a content of about 61% by shifting the solution and drying Dissolving equilibrium precipitated and in known K ₂ O has. The mother liquor discharged at 35 ° C as follows. Composition:

According to the method of the invention, the _{water introduced as water vapor into the 50 123 κα g5 MgC1 63} MgSO ₄ , 150 NaCl, 851 H ₂ O / g / l hot solution

After the KCI crystals have been separated off by means of the. For reuse in the dissolution process, the

heating the cooled solution by evaporation, the cooled solution is heated to about 115 ° C. Through the

be removed again. The evaporation of the trains- water addition of a total of 19 m ³ / h in the clarified

water is not economical in itself. After the solution, the volume has increased in spite of the

However, the process of the invention is less effective when it comes to the removal of the lye adhering to the residue and product

Evaporation of water vapor (vapors) increased to 624 m / h. Be in an evaporation plant

used, the clarified, hot, possibly high in KCI - now at about 115 ° C about 7 m ³ / h evaporated and oer

saturated solution condensed into the clarified solution via the usual solvent temperature. It

In addition, it is heated up by condensing and at the same ^{time the initial volume} of 617 m / h is generated again

to be diluted early. Through this measure, the solubilization solution is obtained with the following composition:

the economy of the process is achieved. 118 KCl 8? MgCl ₂ , 60 MgSO ₁ , 114 NaCl, 820 H ₂ O / g / l

In addition, the MgSO., Content of the heated

The solution is lowered by the simultaneous dilution. This solution is again used in the dissolving process, only turning the ⁶ S when the hot solution is stirred.

Deposition of Langbeinit instead of Leonit or The K ₂ O yield of the process is according to the

Schönit takes place. As a result, the MgSO ₄ content example is 92%. The implementation of the procedure will

the hot solution lowered so that a crystal) - illustrated by the scheme:

Through the pipe chute (I) the hard salt is in the crystallized KCI via the line (26), the

Dissolving device (2) given. The solution residue from the Kallgcfüß (27) and the line (28) in the clarifier (29)

Dissolving device (2) is pumped into the dissolving device (3). After the potassium chloride has been separated off

Brought post-release and then dehydrated from the process on the centrifuge (30) and in the

executed. The solution leaves the dryer (31) at about 95 ° C. in a dried state.

Dissolving apparatus (2) through line (4) and is in the The clarified, cooled solution is separated via the Lei clarifier (5) from the entrained fine sludge device (32) for preheating in the surface condensers, which are also carried out from the process 21) and from there via the steam. The clarified solution then passes through the heated preheater (33) into the evaporation system (9), line (6), and into the mixing condenser (7), in which io. After evaporation of the excess vapor through line (8) from the amount of evaporator, the amount of solution obtained is again that amount of solution that is condensed in system (9). The solution, which is heated to around 115 C, which is required for the dissolving pro / eß 100 ^c C, is passed through the line (10). Via the line (34) it is first pumped into the Langbeinit-Ausrührapparat (11), into the loosening apparatus (3) and then via the line (35) which at the same time through the line (12) Langbeinit- 15 into the loosing apparatus (2) led.
Seed crystals are introduced. According to the embodiment, the method of the invention offers the advantage that, of the Langbeinite, the pulp is pumped into the clarifier (14) through the line (13) by drawing hard salt as crude potash salt. The separated long product with a content of at least 60 ", ', K ₂ O beinit can be produced in a partial amount through the line (12) without a K ₂ O-Verwieder being returned to the stirring apparatus (11) and * The remaining amount is carried out through the line (15).

The solution freed from Langbeinit is then also used against the use of final caustic solutions

ßend through the line (16) in the first evaporator from the sulfate production offers the process of the

(17) pumped the multi-stage vacuum cooling system. finding the advantage that the production of potassium

From the stages of the vacuum cooling system are in the 25 chloride with at least 60% K ₂ O independent of the

Scheme only 4 steps have been drawn. Even before! Available amount of final liquor is.

Entry into the first evaporator (17) is through the Another advantage is that through the

Line (18) the amount of water added, which Langbeinit equipment the MgSO ₄ content of the circle

to prevent NaCl crystallization in the running solutions is reduced to such an extent that un-

subsequent vacuum cooling is necessary. 3 ° desired and uncontrollable deposition of sulfa

Through the line (19) that amount of water table double salts is prevented in the manufacture.

introduced into each evaporator (20), which is the opposite of the production of high-proof

the cooling corresponds to the amount of evaporated water. Potassium chloride by recrystallization of low

In the surface condensers (21), the percent potassium chloride is condensed in a complex evaporated water and the method of the invention offers the line (22) in the container (23) collected via the second system. With the advantage that it is done using known plant container (23) that amount of water is carried out over parts with little additional effort, the line (24) added, which is added before the first. It is of advantage that the energy expenditure evaporator (17) must be introduced into the solution in the evaporation on the heat content of, and the volume of water which transmit the last in, * ° the vapor in the solution and thus of the water-cooled stages of Vacuum cooling system to preheat the mother liquor in the surface steam and in the condensers (25) condensers of the vacuum cooling system to a tem water corresponds to the cooled solution and the essential part is recovered.

1 sheet of drawings

Claims (3)

Part of the kieserite goes with the dissolving process in patent claims: solution. The dissolved MgSO4 and KCl result in double salts, depending on the concentration 1. Process for the production of high-percentage Langbeinite (K ₂ SO, -2 MgSO ₁ ), tiger potassium chloride from KCl-, NaC! -, MgSO, - and 5 below this temperature Leon.t (K ₂ SO · MgSO ₁ · MgCl.-containing aqueous solution by dissolving 4 H ₂ O). Schön.t (K ₂ SO ₁ · MgSO ₁ · 6 H ₂ O) or Glaserit dissolve the crude potassium salt and heater, the mixture (3 K ₂ SO, · Na ₂ SO ₁ ). by means of recycled exhaust steam. Separation according to the example reaction equations of the solution residue from the hot with about 96 to 98% KCl saturation present solution io 2 KCl ₍ 3 MgSO, -K ₂ SO ₁ -2 MgSO _{1 r} MgCl ₂ and crystallization on cooling, that 2 KCI 1-2MgSO ₁ {4 H ₂ O- characterized in that such K ₂ SO ₄ - MgSO, - 4 H ₂ O \ - MgC I ₂ Amount of saturated water vapor (vapors). It is condensed that further heating occurs during the formation of the sulphatic double salt solution up to the boiling point and always MgCl ₂ , which influences the temperature of the NaCl in the solution by stirring out Langbeinite as crystals. These sulphate separated, separated from the hot solution, a double salt also get into the end product and to maintain the pulp density when lowering its Κ, Ο content. stir from Langbeinit required partial amount The double salts interfere with the operational process, as these returned and the other part is discharged on the surfaces of heat exchangers, pipelines and which thereby crystallize in the MgSO. content up to pipes and containers. In addition, the solution reduced in Langbeinitsaturation leads to the excretion of double salts to K ₂ O losses, water is added, as to prevent the z. B. by the fact that Langbeinit accumulates especially in the NaCl crystallization in the following vacuum dissolving residues. cooling is necessary, then the solution 25 These factors cause the lowering of the multi-stage cooling to 20 to 40 C, with K ₂ O content in the potash salt to be recovered, practically NaCl-free KCl crystals formed and a potash salt with at least 60 % K ₂ O however is separated and produced from the cooled solution of hard salts, must therefore after after their heating up, the amount of water is evaporated through an additional covering process according to the state of the art, which are fed as vapors into the hot, uphill 30. The covering can be with water or saturated solution is condensed. with final liquors (sulphate liquors) from the potassium sulphate manufacturer 2. The method as claimed in claim 1, characterized in that the identification takes place. When using sulphate liquor it is shown that the stirring time for the crystallization is therefore the amount of the potassium salt produced with about von Langbeinit about 5 to 30 minutes. 60% K ₂ O from the amount of potassium sulfate and the type 3. The method according to claims 1 and 2, 35 dependent on the implementation of the sulfate process. Characterized by the fact that the sludge density during the covering also results in K ₂ O losses due to the stirring out of Langbeinit at temperatures. between 90 and 115 C by recirculation of it is also known in place of covering in one Langbeinit as seed crystals to about 200 to 50 g / l, a costly second dissolving and cooling process that is set up. 40 to recrystallize the product of the first dissolution process, however, this also results in K ₂ O losses. The German Auslegeschrift 1 237 994 concerns a Process to improve the thermal efficiency efficiency when dissolving crude potash salts and crude 45 installing potash salts that are not high-proof Represent potassium chlorine. It is therefore a different one The production of potassium chloride with a task before. The dissolution of crude salt takes place with at least 60% K ₂ O can from SyIvinit with circulating mother liquor. In order to avoid hot dissolution from a mixing process which is as irreversible as possible in KCl between a hot solution containing NaCl and a solution containing caustic soda and cold crude salt, the cold mother liquor is cooled directly. When using raw salt mixed with kieserite, the recovery of condensers of a certain type of vacuum cooling potassium salts with more than 60% K ₂ O is not directly possible, because the plant and through the heat exchangers always make up the remaining potash salt accumulating in vacuum cooling systems heating conducted. The lye and the crude salt contain considerably less KCI and therefore the K ₂ O-55 are thus warmed up together to improve the content is only between 40 and 50%. These of the thermal efficiency compared to the known low K ₂ O contents are due to the MgCl ₂ -CelaIt th mode of operation, according to which the dissolving solution is conditioned on the solutions obtained in the hard salt operation. Boiling temperature heated and then MgCl _{2 to dissolve} affects the solubility of NaCl in addition to KCl. of raw salt is used. The solubility coefficient of NaCl is shifted towards ^positive. On the other hand, the method of the invention works with tive values, ie MgCl ₂ -containing solu- tion saturated water vapor (vapors), through which the solutions contain more NaCl in the heat than diluted in the solution will that in the downstream cold. The consequence of this is that when the vacuum cooling system cools, the crystallization of NaCl from hot, MgCl ₂ -containing solutions KCl and NaCl is prevented. The simultaneous supply of heat of the crystallize, whereby the K ₂ O content in the product ⁶ 5 condenses vapor leads to the heating of the printed matter. Solution at boiling temperature. Because of its negative The MoCl _{2 of} the hard salt solutions can come from the crude salt in considerable temperature coefficients. In addition, which is stirred out and carried out as crystals.