JPS595551B2 - Ensobun no Sukunaikarihiriyou no Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a potassium fertilizer with a low chlorine content from potassium chloride by a wet method.

Conventionally, when producing water-soluble potash fertilizer with low chlorine content from potassium chloride, the dry method involved volatilizing the chlorine content at high temperatures, which easily corroded the equipment, and the resulting potassium phosphate turned into a soluble condensation salt. There are drawbacks that change.

On the other hand, in the wet method, ammonium dihydrogen phosphate (or ammonium sulfate) and potassium chloride are metathesized in an aqueous solution saturated with only potassium phosphate (or potassium sulfate), and phosphorus is extracted by utilizing the temperature-dependent solubility difference of each component. A method is known in which only potassium phosphate (or potassium sulfate) is precipitated and separated by filtration, but in this method, a portion of the potassium phosphate (or potassium sulfate) is eluted into the filtrate, so the yield of phosphorus is reduced. In addition to this, it is difficult to separate and recover by-product chloride contained in the filtrate, and when the filtrate is discharged from the system, it is difficult to dispose of it due to its large amount.

In order to solve these problems, the present inventors focused on the principle of flotation operation used in mineral beneficiation as a result of various studies, and decided to use this method when producing potash fertilizer by a wet method using the double decomposition reaction described above. The present invention was achieved by discovering that by applying the technology, a water-soluble potash fertilizer with a low chlorine content can be efficiently obtained together with by-product chloride, and the amount of wastewater can be reduced.

That is, the present invention provides an equivalent ratio of ammonium dihydrogen phosphate (
or ammonium sulfate) and potassium chloride are added in excess to a saturated solution of the mixture to undergo double decomposition, and potassium phosphate (or potassium sulfate) and potassium chloride, each containing ammonium ions as a reaction product, are precipitated in the solution. A cation scavenger for the potassium phosphate and an anion scavenger for the potassium sulfate were added to the resulting suspension, and each precipitate was separated by flotation. Another invention relates to a method for producing a potash fertilizer with less chlorine valve, which is characterized by separating and flotating one side, and separating and recovering both the floated matter and the suspended matter from the mother liquor. When separating and recovering the floating material and the suspension in the liquid, the filtrate is recycled and reused as a mixed saturated mother liquor for metathesis, and the obtained nitrogen-containing potassium phosphate (or potassium sulfate) is added to the potassium chloride saturated solution. Then metathesis is carried out again, potassium phosphate (or potassium sulfate) with a low nitrogen content is precipitated in the liquid, the precipitate is separated and recovered, and this filtrate is used as the excess potassium chloride added in the first metathesis reaction. The present invention relates to a method for producing a potash fertilizer that uses less chlorine.

Next, the details of the present invention will first be explained about the case where potassium phosphate fertilizer is produced from ammonium dihydrogen phosphate and potassium chloride. Excess amounts of the two components in an equivalent ratio are added to cause double decomposition.

Since this reaction proceeds due to the difference in solubility, the reaction products are precipitated and suspended in the solution as potassium phosphate and potassium chloride, which respectively contain ammonium ions.

A cation scavenger such as a primary amine containing laurylamine acetate as a main component is added to this suspension at a rate of 0.5 to 1.0 g per I Kp in terms of potassium chloride, and the suspension is floated by a conventional method. When the selection operation is carried out, the chloride in the reaction product adheres to the bubbles and floats up, while the phosphate remains as a suspension in the liquid.

When the floating matter and the suspended matter in the liquid are separated from the mother liquor by filtration, a potassium chloride fertilizer containing ammonia nitrogen and a potassium phosphate fertilizer containing less chlorine can be obtained as cakes.

On the other hand, the filtrate can be repeatedly used again as a mother liquor for the metathesis reaction (reaction system 1).

In order to refine the potassium phosphate fertilizer obtained here and further increase its potash component ratio, the above filtered potassium phosphate cake containing ammonia nitrogen is dispersed and mixed in a potassium chloride saturated solution to further induce the double decomposition reaction. As the process progresses, the nitrogen content in potassium phosphate is transferred to potassium chloride.

When this is separated by filtration, a potassium phosphate fertilizer with a low nitrogen content can be obtained (reaction system ■).

If this filtrate is recycled, the nitrogen content of potassium chloride will increase and the progress of the metathesis reaction will be hindered.
It is used as excess potassium chloride.

The amount of liquid increased by this addition is maintained by discharging a corresponding amount from the filtrate of reaction system I to the outside of the system to maintain equilibrium within the system.

According to the law, a liquid with a lower ammonia content is used as the circulating mother liquor in reaction system I, so the degree of double decomposition in this system is greater than when the mother liquor is circulated only within the system. Therefore, the required amount of potassium chloride saturated solution to be added to reaction system H is reduced.

Next, to explain the case of manufacturing potassium sulfate fertilizer from ammonium sulfate and potassium chloride, as above, a mixed saturated solution of ammonium sulfate and potassium chloride is used as the mother liquor, and an excess of the two components in a chemical equivalent ratio is added to the mother liquor to undergo double decomposition. do.

As a result of the reaction, potassium sulfate and potassium chloride, each containing ammonium ions, are precipitated in the solution, so an anion scavenger such as petroleum sulfonic acid or sodium dodecylbenzenesulfonate is added to this suspension in terms of potassium chloride IK.
When added at a rate of 0.2 to 0.5 g/p and flotation performed in a conventional manner, the sulfate in the reaction product separates and floats to the surface with air bubbles, while the chloride remains as a suspension in the liquid. do.

When the floating matter and the suspended matter are separated from the mother liquor by filtration, a cake-shaped potassium sulfate fertilizer and a potassium chloride fertilizer containing ammonia nitrogen with a low chlorine content are obtained, and the filtrate is recycled as a reaction mother liquor. (reaction system ■).

In order to increase the potassium component ratio of the obtained potassium sulfate fertilizer, the above-mentioned potassium sulfate cake containing ammonia nitrogen may be dispersed and mixed in a potassium chloride saturated solution, double decomposed, and then filtered. This yields a potassium sulfate fertilizer with a low nitrogen content (reactive system ``)''.

The filtrate is mixed with the reaction mother liquor of reaction system I.

Next, the present invention will be explained based on a real sister example.

However, AN in the table is the nitrogen equivalent content of ammonia nitrogen.

Actual example 1 1000g ammonium dihydrogen phosphate and 6 potassium chloride
98g and 4953g of mixed saturated liquid (mother liquor) of these two components.
I put it inside and caused it to decompose.

This is an amine-based scavenger containing laurylamine as the main component.
．． 39 g was added and flotated for 10-15 minutes in a flotation machine.

The floating matter and the suspended matter in the liquid were separated by filtration to obtain 634 g of nitrogen-containing potassium chloride fertilizer and 1080 g of nitrogen-phosphate potassium fertilizer with a low chlorine content.

4937 g of the filtrate is repeatedly used as a reaction mother liquor (reaction system 1).

In order to increase the potassium content of the nitrogen-potassium phosphate fertilizer, the above-mentioned nitrogen-potassium phosphate was dispersed and mixed in 1,336 g of a potassium chloride solution, and this was filtered to obtain 1,000 g of a potassium phosphate fertilizer (reaction system ①).

1416 g of this filtrate is used as a metathesis solution in reaction system I.

In this case, 1400 g of the filtrate of reaction system I was drained out of the system to balance the liquid volume.

The production test results of the nitrogen phosphate potassium fertilizer and the potassium phosphate fertilizer obtained in reaction systems 1 and 2 are shown in Tables 1 and 2, respectively.

If you try to obtain a fertilizer equivalent to the nitrogen phosphate potassium fertilizer shown in Table 1 using the conventional method using the solubility difference, water is required to dissolve the chloride, so the amount of waste water will be reduced. 3 to 4 are generated for every 1 potash fertilizer, and P2O associated with this
The loss for 6 was 15%.

In contrast, according to the present invention, no drainage occurs.

When obtaining a potassium phosphate fertilizer with a high phosphorus content using the solubility difference method, 6 to 8 times as much waste liquid was generated per 1 potash phosphate fertilizer, but in the present invention, it can be kept to 1.5 to 1.8 times. I can do it.

Actual Sister Example 2 812 g of ammonium sulfate and 976 g of potassium chloride were metathesized in 4072 g of a saturated liquid mixture (mother liquor) of these two components.

To this was added 0.3 g of a petroleum sulfonic acid scavenger, and flotation was carried out for 8 to 10 minutes using a flotation machine.

Nitrogen sulfate potassium fertilizer 1066 with low chlorine content by filtering out floating matter and suspended matter in the liquid,! 7 and 740 g of nitrogen-containing potassium chloride were obtained.

4054 g of the filtrate is repeatedly used as a reaction mother liquor (reaction system I).

When increasing the potassium content of the nitrogen-potassium sulfate fertilizer, the above-mentioned potassium nitrogen sulfate was added and circulated in 789 g of a saturated potassium chloride solution.

This was filtered to obtain 1000 g of potassium sulfate fertilizer.

(Reaction system ■). 855 g of this filtrate is used as a metathesis solution in reaction system I.

In this case, the amount of waste liquid from reaction system I was 837 g.

Tables 3 and 4 show the production test results of the nitrogen sulfate potassium fertilizer and the phosphate potassium fertilizer obtained in reaction systems I and H, respectively.

When trying to obtain a nitrogen sulfate potassium fertilizer composition equivalent to that shown in Table 3 by the solubility difference method, water is required to dissolve ammonium salts and chlorides.

In this case, the amount of drained liquid was 2 to 3 times the amount of the nitrogen sulfate potassium fertilizer per 1, and the loss of S04 associated with this was 13%.

In contrast, according to the present invention, no drainage occurs.

Furthermore, when obtaining a potassium sulfate fertilizer with a high potash content using the solubility difference method, 3 to 4 times more wastewater was generated per 1 part of the potassium sulfate fertilizer, but in the present invention, the amount was only 0.8 to 1.0 times.

As described above, according to the present invention, by applying the flotation operation, it is possible to reduce the amount of waste liquid, and it is also possible to reduce the amount of waste liquid by applying the flotation operation.
The yield of O5 or SO4 can be increased, and the by-produced chloride can be recovered as a solid, which eliminates the need for condensation and can be used as a raw material for fertilizer.

Claims (1)

[Claims] Ammonium dihydrogen phosphate or ammonium sulfate and potassium chloride in an equivalent ratio of 1 are added in excess to a mixed saturated solution of these to cause double decomposition, thereby producing potassium phosphate or potassium phosphate containing ammonium ions in the solution, respectively. Potassium sulfate and potassium chloride are precipitated, and a cation scavenger for potassium phosphate and an anion scavenger for potassium sulfate are added to the resulting suspension for flotation. A method for producing a potash fertilizer with a low chlorine content, characterized by separating and floating one side of the precipitate through an operation, and separating and recovering both the floated substance and the suspended substance from the mother liquor. Ammonium dihydrogen phosphate or ammonium sulfate and potassium chloride in an equivalent ratio of 2 are added in excess to a mixed saturated mother liquor of these for double decomposition to produce potassium phosphate or potassium sulfate and potassium chloride each containing ammonium ions in the mother liquor. A cation scavenger for potassium phosphate or an anion scavenger for potassium sulfate is added to the suspension obtained, and the precipitate is removed by flotation. One of them is separated and floated, the floating material and the suspended material in the liquid are separated and recovered from the mother liquor, and the filtrate is recycled as the mother liquor, and the obtained potassium phosphate or potassium sulfate is added to a potassium chloride saturated solution. The method is characterized in that the compound is added and metathesized again, potassium phosphate or potassium sulfate with a low nitrogen content is precipitated in the solution, the precipitate is separated and recovered, and the filtrate is used as an excess additive for potassium chloride in the metathesis reaction. A method for producing potash fertilizer with low chlorine content.