JPS6197116A - Manufacture of purified potassium phosphate - Google Patents

Abstract

PURPOSE:To manufacture efficiently purified potassium phosphate utilizable as fertilizer by washing potassium phosphate sludge having adsorbed polyalkylene glycol separated by filtration with a solvent. CONSTITUTION:Potassium hydroxide used as a catalyst in the manufacture of polyalkylene glycol from alkylene oxide is neutralized with phosphoric acid and filtered. The resulting potassium phosphate sludge having adsorbed polyalkylene glycol is washed with a solvent which dissolves polyalkylene glycol and does not dissolve potassium phosphate, e.g., methanol or methylene chloride. The adsorbed polyalkylene glycol is removed by extraction, and purified potassi um phosphate is manufactured. The resulting soln. contg. the extracted polyalkylene glycol is distilled. The solvent is recovered and used again, and the polyalkylene glycol is recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing potassium phosphate from potassium F31F-, which is purified from phosphorus obtained from a polyalkylene glycol production process.

(Prior art) When producing polyalkylene glycol ruby from alkylene oxide, caustic power IJ'& is usually used as a catalyst, but this caustic potash is neutralized with phosphoric acid in the refining process, and as potassium phosphate crystals. Separated with a filter (usually called rsy). In addition to potassium phosphate, this P3 potato contains polyalkylene glycol in an amount equal to or more than potassium phosphate, and a small amount of magnesium silicate.
The reality is that we have no choice but to dispose of it. By the way, the potassium phosphate in this P5'l- is effective as a fertilizer component, and can be used as a fertilizer if only a small amount (or polyalkylene glycol) is removed.

(Problem to be Solved by the Invention) Conventionally, polyalkylene glycol was removed from Konoto Sanmine by vacuum suction using a special filter 7, but this method did not allow polyalkylene glycol to be removed. The removal rate is low (normally, only about 60 to 70% of the polyalkylene glycol contained in F5% can be removed. Also, PS'J may ignite during the process of removing polyalkylene glycol by vacuum suction, etc.) For this reason, this P taro has no value as fertilizer (currently it is treated as industrial waste).

The purpose of the present invention is to produce refined potassium phosphate that can be used as fertilizer from Toshihaya, which was conventionally disposed of, and also to recover polyalkylene glycol contained in P3, which is an effective use of resources. It is to provide Z.

(Means for Solving the Problems) In order to achieve the above object, the present inventors have made extensive studies and have finally completed the present invention.

That is, the present invention provides potassium phosphate IP3'! obtained from the process of producing polyalkylene glycol wM from alkylene oxide. This is a method for producing refined potassium phosphate, characterized by washing with f w solvent.

In the method of the present invention, neutralization with phosphoric acid is carried out in a caustic potash polyalkylene glycol, which is a catalyst used when producing polyalkylene glycol wH from alkylene oxide,
Polyalkylene glycol Y obtained by subsequent filtration
The target is adsorbed potassium phosphate. This potassium phosphate r4 usually contains about 50% by weight of polyalkylene glycol and other metal compound impurities contained in the caustic potassium catalyst.

Note that alkylene oxide includes ethylene oxide, propylene oxide, butylene oxide, and the like. Depending on the purpose, these may be polymerized singly, as a mixture, or in parts to form polyalkylene glycols.

The solvent used in the method of the present invention is preferably one that dissolves the polyalkylene glycol in heat, does not dissolve potassium phosphate, and has a low boiling point that can be easily recovered or dried.

Examples of such solvents include lower alcohols such as methanol, ethanol, isopropa, and alcohol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ethers such as diethyl ether, tetrahydrofuran, and dioxane, hexane, heptane, petroleum ether,
Examples include hydrocarbons such as petroleum benzine, ligroin, benzene, toluene, and xylene, and halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, 1.2 dichloroethane, chlorobenzene, orthodichlorobenzene, and the like. Among them, methanol, methylene chloride, and chloroform are preferable because they have a low boiling point and dissolve in a high concentration of polyalkylene glycolone.One of the embodiments of carrying out method Z of the present invention is to remove the polyalkylene glycolone remaining in PjT. In the polyalkylene glycol manufacturing process, a p-passage vessel is usually used.
Install one or two or more filters, continue filtration until a certain amount of F>Hayabusa accumulates in the filter, remove the accumulated F4 from the filter, and then remove the polyalkylene glycol remaining in P4, or The latter mode is usually preferred, in which an extraction device using a solvent is installed in the filter in which 3% F is accumulated, and the polyalkylene glycol in the P sequence is extracted and removed by passing the solvent through the filter. The time required for this extraction varies depending on the size of the filter, but it usually only takes a few hours, which is about 1/8th the time compared to the conventional vacuum suction method (and the removal rate is greatly increased). There is no risk of P floating catching fire.

This allows F3'! Since the polyalkylene glycol in - is almost completely removed, F3'/- becomes almost potassium phosphate and can be used as fertilizer. If it is further purified, it can be used for other purposes as potassium phosphate.

Furthermore, since the solvent containing polyalkylene glycol χ can be easily separated into the polyalkylene glycol and the solvent by distillation, the solvent can be reused, while the polyalkylene glycol can be recovered as a product.

(Example) The present invention will be explained below with reference to Examples.

Example 1 Potassium phosphate P4 from the polypropylene glycol manufacturing process (60% polypropylene glycol, 66% potassium phosphate, 4% others) was passed through a filter containing 400 kg of methylene chloride as a solvent at a rate of 150 t/min to produce F4Y. Washed. Table 1 shows the content of polypropylene glycol in F4 over time at this time.

Comparative Example 1 Polypropylene glycol was removed by suction using a conventional vacuum suction method at a vacuum level of 100 maHr from a filter containing 40 Dkg of P-bond.

The content of polypropylene/glycol over time in (p4) at this time is shown in Table 7.

As shown in Table 1, it can be seen that the method according to the present invention can remove polypropylene glycol contained in Tojun in almost a short time.

Examples 2 to 4 The same experiments as in Example 1 were conducted except that methanol, acetone, and chloroform were used as the medium.

The results are shown in Table 7-2.

(Effect of the invention) According to the method of the invention, compared to the conventional vacuum suction method,
It has the following advantages.

(1) The removal rate of polyalkylene glycol increases significantly, and P-build becomes almost potassium phosphate, which can be used as fertilizer.

Furthermore, if purified, it can be used for other purposes as potassium phosphate.

(2) Polyalkylene glycol can be recovered as a product.

(3) The time required to remove polyalkylene glycol can be greatly shortened.

(4) There is no risk of ignition when removing polyalkylene glycol.

As described above, the method of the present invention makes effective use of F. peregrines, which were conventionally disposed of, as a resource and makes a significant contribution to industry.

Claims (1)

[Claims] 1) A method for producing purified potassium phosphate, which comprises washing with a solvent a potassium phosphate filtrate obtained from the step of producing polyalkylene glycol from alkylene oxide.