CN116407875A - A kind of preparation method of potassium carbonate - Google Patents

Abstract

The invention relates to the field of chemical industry, in particular to a preparation method of potassium carbonate. The preparation method comprises the following steps: the potassium chloride solution is utilized to pass through a resin column to obtain a saturated resin column for adsorbing potassium ions; the potassium chloride solution in the saturated resin columns for adsorbing potassium ions is emptied, the potassium chloride on the surfaces of N saturated resin columns connected in series is washed, and the washing water is emptied; the discharged potassium chloride solution returns to the leaching resin column; adding ammonium bicarbonate solution into M washed saturated resin columns connected in series to exchange potassium ions on the saturated resin columns, and converting the saturated resin columns into lean resin columns after the exchange is completed; evacuating ammonium bicarbonate in the X series resin-lean columns, washing, and reusing the resin-lean columns for adsorbing potassium ions after evacuating washing water; the discharged ammonium bicarbonate solution is returned for potassium ion exchange. The invention improves the utilization rate of potassium chloride and ammonium bicarbonate, and improves the leaching efficiency and the resin turnover efficiency.

Description

A kind of preparation method of potassium carbonate

technical field

The invention relates to the field of chemical industry, in particular to a preparation method of potassium carbonate.

Background technique

Potassium carbonate is an important chemical reagent, currently mainly used in high-grade potassium glass, pesticides and food additives. The rapid development of my country's automobile industry and the rapid growth of high-grade potassium glass for vehicles have rapidly expanded the use of potassium carbonate in potassium glass.

At present, the preparation technology of potassium carbonate is mainly ionic membrane electrolysis-carbonization process and ion exchange process. The ionic membrane-fluidized bed method is mainly used abroad, and the ion exchange process is mainly used in China.

Problems existing in the current ion-exchange potassium carbonate production process: ①The utilization rate of potassium chloride is low, resulting in the loss of potassium ions and increasing the production cost. After several technical transformations in a factory in Shandong, the utilization rate of potassium chloride was only increased to 85% %, the utilization rate of potassium chloride in the new production line of a factory in Zhejiang is 93.7%, which is the highest level at present; ②The concentration of potassium bicarbonate solution is low, and the subsequent evaporation consumes a lot of energy. 3. The utilization rate of ammonium bicarbonate is not high, which increases the production cost. The utilization rate of ammonium bicarbonate in a mainstream production plant is 85.8%; 4. The concentration of ammonium chloride in the adsorption tail liquid is low. Cause ammonium chloride recovery difficulty big cost is higher.

Zhang Junxian et al. improved the collection method of the effluent in the exchange and regeneration process. By recycling the effluent in the exchange process to the front of the next exchange, and recycling the effluent in the regeneration process to the front of the next regeneration, the chlorination produced The concentration of ammonium solution is increased from 4% to 9%, and the utilization rate of single-column potassium ions reaches 87%.

In Chen Yong's master's thesis "Experimental Research on Three-Column Series Ion Exchange Process in Potassium Carbonate Production", the utilization rate of potassium chloride in single-column operation was 83.2%. After using three-column series process, the highest utilization rate of potassium chloride was 91.2%, The highest concentration of K in the potassium bicarbonate eluent was 32g/L, and the concentration of NH ₄ Cl in the adsorption tail liquid increased from 39g/L in a single column to 55g/L.

Song Yan introduced the technological transformation of Lunan Chemical Fertilizer Plant in the article "Potassium Carbonate Process Transformation". After the transformation, the consumption of potassium chloride per ton of potassium carbonate dropped from 1350kg to 1270kg, and the utilization rate of potassium chloride increased from 80% to the transformation. 85% after.

According to the EIA publicity report of Zhejiang Dayang Potassium Carbonate Project, the production of one ton of potassium carbonate consumes 1.153 tons of potassium chloride, with a utilization rate of 93.7%, and 1.335 tons of ammonium bicarbonate, with a utilization rate of 85.8%.

The patent of publication number CN101481124A discloses "a production process of potassium carbonate", but for the core of the process - ion exchange process and operation, there is no in-depth introduction, and no ion exchange process parameters, operation process and method are proposed.

The patent with the publication number CN107140660A discloses "a production process of potassium carbonate", which gives a concentration of potassium chloride in the adsorption stock solution of 2 to 5%, and a utilization rate of potassium chloride of 93%, without giving other key parameters and indicators , Potassium chloride concentration is too low lead to long adsorption time resin turnover rate decreased, seriously affecting production capacity, potassium chloride utilization rate of 93%, is also low.

Contents of the invention

The technical problem to be solved by the present invention is: to provide a preparation method of potassium carbonate, improve the utilization rate of potassium chloride and ammonium bicarbonate, improve the rinsing efficiency and resin turnover efficiency.

The invention provides a kind of preparation method of potassium carbonate, comprises the following steps:

Step S1: using potassium chloride solution to pass through the resin column to obtain a saturated resin column that adsorbs potassium ions;

Step S2: Empty the potassium chloride solution in the saturated resin column adsorbing potassium ions, wash the potassium chloride on the surface of N series saturated resin columns, and empty the washing water; the discharged potassium chloride solution returns to step S1 As potassium chloride adsorption stock solution, through the resin column;

Step S3: adding ammonium bicarbonate solution to the washed saturated resin columns connected in series to exchange potassium ions on the saturated resin columns, after the exchange is completed, the saturated resin columns are converted into lean resin columns;

After the washing of the saturated resin column connected in series in step S2 is completed, the M+1 position is connected to perform potassium ion elution;

Step S4: Empty the ammonium bicarbonate in the X poor resin columns connected in series, and then wash them. After emptying the washing water, the poor resin columns are reused for adsorbing potassium ions; the discharged ammonium bicarbonate solution returns to step S3, and For potassium ion elution;

For the lean resin column that has been exchanged in series in step S3, access the X+1 position to wash the lean resin column;

Among them, 5≥N≥2; 5≥M≥2; 5≥P≥2.

Preferably, in the step S1, three columns are connected in series for potassium ion adsorption to obtain a saturated resin column for adsorbing potassium ions,

The saturated resin column is connected to the N+1 position for serial washing;

The solubility of the potassium chloride solution is 200-350 g/L.

Preferably, the flow rate of the potassium chloride solution passing through the resin column per hour is 0.5 to 3 times the volume of the resin filled, and the passing time is 30 minutes to 90 minutes.

Preferably, in the step S2, the potassium chloride solution in the saturated resin column adsorbing potassium ions is exhausted and blown off with compressed air;

The potassium chloride on the surface of N series saturated resin columns is washed by adopting the method of connecting three columns in series and liquid inflowing from the upper part and discharging liquid from the lower part.

Preferably, the washing water used for washing is tap water or pure water, and the flow rate of the washing water passing through the resin column per hour is 1 to 5 times the volume of the resin loaded, and the passing time is 10 minutes to 60 minutes.

Preferably, in the step S3,

Three columns are connected in series, the upper part is fed into the lower part and the lower part is discharged, adding ammonium bicarbonate solution and potassium ions on the saturated resin column for elutriation. The concentration of the ammonium bicarbonate solution is 160-250g/L.

Preferably, the flow rate of the ammonium bicarbonate solution passing through the resin column per hour is 1 to 4 times the volume of the resin filled, and the passing time is 15 minutes to 90 minutes.

Preferably, in the step S4, the ammonium bicarbonate solution in the lean resin is exhausted and blown off with compressed air;

The poor resin column was washed by adopting the method of three columns connected in series, and the upper part was liquid-injected and the lower part was liquid-outlet.

Preferably, the washing water used for washing is tap water or pure water, and the flow rate of the washing water passing through the resin column per hour is 2 times to 5 times the volume of the resin loaded, and the passing time is 10 minutes to 60 minutes.

Preferably, said N=3; M=3; P=3.

Compared with prior art, the preparation method of salt of wormwood of the present invention has following beneficial effect:

(1) Using the operation method of three columns in series, with the shortest operation time, the adsorption, rinsing, and washing times are matched to each other, which greatly improves the resin turnover utilization rate;

(2) Multi-column series operation mode is adopted to realize that the first column K is saturated while the tail column K has not yet penetrated during adsorption, and the first column NH ₄ ⁺ is saturated while the tail column NH ₄ ⁺ has not yet penetrated during elution, so as to improve the utilization rate of KCl to More than 99%, NH ₄ HCO ₃ utilization rate is more than 95%.

(3) For the washing of saturated resin and poor resin, the feed liquid in the resin column is emptied and blown off with compressed air, and then tandem washing is carried out without cumbersome operations such as catching the air. The washing volume is small, the washing efficiency is high, and the volume of washing water The control is precise, the washing water saturated with resin just returns to prepare KCl adsorption stock solution, and the washing water poor in resin just returns to prepare NH ₄ HCO ₃ eluent.

(4) The concentration of NH ₄ Cl in the adsorption tail liquid is high, up to 160-180g/L, and the concentration of K in the eluent is high, up to 70g/L.

Description of drawings

Fig. 1 represents the flow chart of preparation method of potassium carbonate of the present invention.

Detailed ways

In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

The invention adopts an ion exchange process and a fixed-bed continuous ion exchange device to convert potassium chloride into potassium bicarbonate. Multiple exchange columns form a set of continuous ion exchange system, which implements circular circulation operation.

The embodiment of the present invention discloses a kind of preparation method of potassium carbonate, as shown in Figure 1, comprises the following steps:

Step S1: using potassium chloride solution to pour through the lipid column to obtain a saturated resin column that adsorbs potassium ions;

Preferably, three columns are connected in series for potassium ion adsorption to obtain a saturated resin column for adsorbing potassium ions,

According to the situation of the resin columns in series, the resin column at the first position is saturated first, and the saturated resin column is connected to the N+1 position for series washing; the resin column at the second position is replaced by the first adsorption column, and the resin columns at the following positions are replaced in turn.

The solubility of the potassium chloride solution is preferably 200-350 g/L, more preferably 270-300 g/L.

The hourly flow rate of the potassium chloride solution passing through the resin column is 0.5-3 times, preferably 0.5-1.5 times, the volume of the resin filled, and the passage time is preferably 30-90 minutes, more preferably 45-60 minutes.

The ammonium chloride in the tail liquid after adsorption is recovered.

Step S2: Empty the potassium chloride solution in the saturated resin column adsorbing potassium ions, wash the potassium chloride on the surface of N series saturated resin columns, and empty the washing water; the discharged potassium chloride solution returns to step S1 As potassium chloride adsorption stock solution, eluting resin column;

Preferably, the potassium chloride solution in the saturated resin column for adsorbing potassium ions is exhausted and blown off with compressed air;

The potassium chloride on the surface of N series saturated resin columns is washed by adopting the method of connecting three columns in series and liquid inflowing from the upper part and discharging liquid from the lower part.

The washing water used for the washing is tap water or pure water, and the flow rate of the washing water passing through the resin column per hour is 1 to 5 times of the resin filling volume, preferably 3 to 5 times, and the passing time is preferably 10 min to 60 min, more preferably Preferably it is 15 min to 30 min.

According to the washing conditions of the resin columns in series, the resin column at the first place is washed clean first, and after it runs smoothly, it can be switched down and connected to the M+1 position. The resin column in the second position is the first to replace the resin column, and the resin columns in the following positions are replaced in turn.

Step S3: adding ammonium bicarbonate solution to the washed saturated resin columns connected in series to exchange potassium ions on the saturated resin columns, after the exchange is completed, the saturated resin columns are converted into lean resin columns;

The potassium ions on the saturated resin column are elutriated by adding ammonium bicarbonate solution in the way of three columns connected in series, liquid in the upper part and liquid out in the lower part, and the concentration of the ammonium bicarbonate solution is 160-250g/L.

The hourly flow rate of the ammonium bicarbonate solution through the resin column is 1 to 4 times, preferably 1 to 2 times, the volume of the resin filled, and the passage time is preferably 15 min to 90 min, more preferably 45 min to 60 min.

After the M serially washed saturated resin columns run smoothly, after the washing of the serially connected saturated resin columns in step S2 is completed, the M+1 position is inserted for potassium ion exchange.

According to the ion exchange situation of series resins, the resin column at the first position is the first to complete the exchange, and after running smoothly, it can be switched down and connected to the X+1 position. The resin column in the second position is the first to replace the resin column, and the resin columns in the following positions are replaced in turn.

Step S4: Empty the ammonium bicarbonate in the X poor resin columns connected in series, and then wash them. After emptying the washing water, the poor resin columns are reused for adsorbing potassium ions; the discharged ammonium bicarbonate solution returns to step S3, and For potassium ion elution;

After the ammonium bicarbonate in the X series of lean resin columns runs smoothly, for the lean resin columns that have been exchanged in series in step S3, the X+1 position is connected to wash the lean resin columns;

Among them, 5≥N≥2; 5≥M≥2; 5≥P≥2.

In the step S4, the NH ₄ HCO ₃ solution in the lean resin is exhausted and blown off with compressed air;

The poor resin column was washed by adopting the method of three columns connected in series, and the upper part was liquid-injected and the lower part was liquid-outlet.

The washing water for the washing is tap water or pure water, and the flow rate of the washing water passing through the resin column per hour is 2 to 5 times, preferably 4 to 5 times, the volume of the resin filled, and the passing time is preferably 10 min to 60 min, more preferably Preferably it is 15 min to 30 min.

According to the washing conditions of the resin columns in series, the resin column at the first place is washed clean first, and after running smoothly, it can be switched down and connected to step S1, placed at the last position of the resin column, and continued to be recycled.

In order to further understand the present invention, below in conjunction with embodiment the preparation method of potassium carbonate provided by the invention is described in detail, protection scope of the present invention is not limited by following examples.

Example 1

The size of the resin column is Φ _{inner diameter} 27mm×1000mm, outer diameter 32mm, filled with resin 400ml, resin height 700mm, a group of 12 resin columns of the same size, 3 columns in series adsorption K, 3 columns in series washing KCl, 3 columns in series elution K, Three columns are connected in series to wash NH ₄ HCO ₃ , and the resin column is operated in a circular cycle.

Series adsorption: prepare KCl concentration of 280g/L, and enter the 10#-11#-12# three-column series adsorption at a flow rate of 320ml/h. After 45 minutes of adsorption, the potassium adsorbed on the 10# resin column reaches 69gK/L resin, The concentration of K in the effluent tail liquid of 12# tail column is 0.95g/L. The first column 10# is saturated and switched off, and then the 11# column is used as the first column, the tail column is connected to the 1# column, and 11#-12#-1# continues the three-column series adsorption.

Wash the KCl in the saturated resin: empty the KCl solution in 10#, blow off the KCl solution remaining in the saturated resin column and the resin surface with compressed air, collect the KCl solution, and return it as the original adsorption solution. Connect the 10# column to the back of the 9# column, and turn on 8#-9#-10# to wash KCl in three columns. Use tap water or pure water as detergent, flow rate of 960ml/h, enter 8#-9#-10# three columns in series to wash KCl, after washing for 15min, collect 240ml of washing water, return to prepare KCl adsorption stock solution.

Series elution: prepare NH ₄ HCO ₃ concentration of 200g/L, with a flow rate of 400ml/h, enter the 5#-6#-7# three-column series elution K, after leaching for 45min, the potassium adsorbed on the 5# resin column Only the 0.12gK/L resin is left, and the K concentration in the eluent flowing out of the 7# tail column is 66g/L, and the NH ₄ ⁺ concentration is 1.8g/L. The first column 5# was switched off after the elution was completed, and then the 6# column was used as the first column, the tail column was connected to the 8# column, and the 6#-7#-8# continued the three-column elution in series.

Wash the NH ₄ HCO ₃ in the lean resin: empty the NH ₄ HCO ₃ solution in 5#, and use compressed air to blow off the residual NH ₄ HCO ₃ solution in the lean resin column and the lean resin, and collect the discharged NH ₄ HCO ₃ solution , return as eluent. Connect the 5# column to the back of the 4# column, turn on 3#-4#-5# to wash NH ₄ HCO ₃ in three columns. Use tap water or pure water as detergent, with a flow rate of 1600ml/h, enter the 3#-4#-5# three columns to wash NH ₄ HCO ₃ in series, after washing for 15 minutes, collect 400ml of washing water, return to prepare NH ₄ HCO ₃ rinse agent.

According to adsorption K—saturated resin washing KCl—leaching K—lean resin washing NH ₄ HCO ₃ , the operation time of each process is the same, and they are matched and connected with each other. The 12 exchange columns realize the circular circulation operation and realize the efficient utilization of the resin.

The above ion exchange operations have achieved good results: KCl utilization rate ≥ 99%, NH ₄ HCO ₃ utilization rate ≥ 95%; saturated resin K absorption capacity reaches 70g/LR, K concentration in KHCO ₃ eluent is 68g/L, washing adsorption The concentration of NH ₄ Cl in the tail liquid reaches above 160g/L, the washing operation is simple and the effect is good, and the concentration of Cl ^- in the eluent is about 25mg/L, which meets the requirements for potassium carbonate products.

The descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. a preparation method of salt of wormwood, is characterized in that, comprises the following steps: Step S1: using potassium chloride solution to pass through the resin column to obtain a saturated resin column that adsorbs potassium ions; Step S2: Empty the potassium chloride solution in the saturated resin column adsorbing potassium ions, wash the potassium chloride on the surface of N series saturated resin columns, and empty the washing water; the discharged potassium chloride solution returns to step S1 As potassium chloride adsorption stock solution, through the resin column; Step S3: adding ammonium bicarbonate solution to the washed saturated resin columns connected in series to exchange potassium ions on the saturated resin columns, after the exchange is completed, the saturated resin columns are converted into lean resin columns; After the saturated resin column in series in step S2 is washed, the M+1 position is inserted for potassium ion exchange; Step S4: Empty the ammonium bicarbonate in the X poor resin columns connected in series, and then wash them. After emptying the washing water, the poor resin columns are reused for adsorbing potassium ions; the discharged ammonium bicarbonate solution returns to step S3, and for potassium ion exchange; For the lean resin column that has been exchanged in series in step S3, access the X+1 position to wash the lean resin column; Among them, 5≥N≥2; 5≥M≥2; 5≥P≥2. 2. the preparation method of salt of wormwood according to claim 1, is characterized in that, in described step S1, three columns are connected in series and carry out potassium ion adsorption, obtain adsorption potassium ion saturated resin post, The saturated resin column is connected to the N+1 position for serial washing; The solubility of the potassium chloride solution is 200-350 g/L. 3. the preparation method of salt of wormwood according to claim 2 is characterized in that, described potassium chloride solution per hour is 0.5 times～3 times of resin filling volume by the flow rate of resin column, and passing time is 30min～90min . 4. the preparation method of salt of wormwood according to claim 1 is characterized in that, in described step S2, the potassium chloride solution in the saturated resin column of adsorption potassium ion is exhausted and blows off with compressed air; The potassium chloride on the surface of N series saturated resin columns is washed by adopting the method of connecting three columns in series and liquid inflowing from the upper part and discharging liquid from the lower part. 5. the preparation method of salt of wormwood according to claim 4 is characterized in that, the washing water of described washing is tap water or pure water, and the flow of washing water per hour by resin column is 1 times ~ of resin filling volume. 5 times, the passing time is 10min~60min. 6. the preparation method of salt of wormwood according to claim 1 is characterized in that, in described step S3, Three columns are connected in series, the upper part is fed into the lower part and the lower part is discharged, and the ammonium bicarbonate solution is added to exchange the potassium ions on the saturated resin column. The concentration of the ammonium bicarbonate solution is 160-250g/L. 7. the preparation method of salt of wormwood according to claim 6 is characterized in that, the flow of described ammonium bicarbonate solution per hour by resin column is 1 time～4 times of resin filling volume, and passing time is 15min～90min . 8. the preparation method of salt of wormwood according to claim 1 is characterized in that, in described step S4, the ammonium bicarbonate solution in poor resin is exhausted and blows off with compressed air; The poor resin column was washed by adopting the method of three columns connected in series, and the upper part was liquid-injected and the lower part was liquid-outlet. 9. the preparation method of salt of wormwood according to claim 1 is characterized in that, the washing water of described washing is tap water or pure water, and the flow of washing water per hour by resin column is 2 times ~ of resin filling volume. 5 times, the passing time is 10min~60min. 10. the preparation method of potassium carbonate according to claim 1, is characterized in that, described N=3; M=3; P=3.

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