KR19990073935A - Method for producing tertiary calcium phosphate - Google Patents

Abstract

The present invention provides a water phase slurry containing a precipitate near pH 7 by reacting an aqueous calcium hydroxide solution with a first aqueous calcium phosphate solution, and filtering, drying, calcining, and pulverizing the third calcium phosphate precipitate from the aqueous slurry. Provided is a production method capable of industrially mass-producing pure white tricalcium phosphate superior in purity to the product obtained in the method.

Description

Method for producing tertiary calcium phosphate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing calcium phosphate that is used as a raw material for adsorbing raw materials such as main car, clay for porcelain, mixed raw material of ceramic glaze, abrasive ingredient of toothpaste, other refractory materials and heat resistant tiles.

Recently, as the demand for high-purity calcium phosphate increases, research into a method of manufacturing the same has been actively conducted.

As a method for producing such calcium phosphate, a dry synthesis method in which a powdered raw material is subjected to a solid phase reaction at a high temperature, and a wet synthesis method in which a raw material solution or a raw material slurry is reacted are known.

However, these methods have a problem that it is difficult to provide a product with high purity. Moreover, when the high purity calcium phosphate is prepared by the wet synthesis method, the synthesis step is complicated and expensive.

For example, the conventional wet synthesis method for producing calcium phosphate by reacting calcium chloride (CaCl ₂ ) with dibasic sodium phosphate (Na ₂ HPO ₄ ) has high manufacturing cost since a large amount of hydrochloric acid and ammonium hydroxide are used during the reaction. It is difficult to mass-produce, and the reaction is complicated. After the reaction, unreacted Ca (OH) ₂ , NaCl, NH ₄ Cl, etc. remain in the reaction solution, which makes it difficult to separate the calcium phosphate precipitate from the aqueous solution. In particular, since the unreacted Ca (OH) ₂ is contained in the obtained calcium phosphate, the purity is lowered, so that the mixing amount is limited when used as a ceramic clay or glaze.

In addition, as a source of calcium phosphate, in addition to the above synthesis method, bone ash obtained by mass gathering and calcining bovine bone (Fon Ash) was imported as a raw material for porcelain in the United Kingdom and the like, but pollution, such as odor and soot, is generated during processing. There is a problem, since the yellow discoloration during the firing process, the amount actually added to the ceramic glaze is limited, the production of natural bone ash is gradually decreasing, it is difficult to purchase as a raw material.

Under these circumstances, the present inventors have conducted extensive research to solve the above problems, and as a result, the aqueous calcium hydroxide solution and the first calcium phosphate solution are reacted to obtain an aqueous slurry containing a precipitate near pH 7, and from this aqueous slurry It was found that by filtering, drying, calcining and pulverizing the calcium phosphate precipitate, it is possible to provide a production method capable of industrially mass-producing pure white tricalcium phosphate having higher purity than the product obtained by the conventional wet method. On the basis of this, the present invention was completed.

That is, an object of the present invention is to provide a manufacturing method that can be industrially produced pure white calcium phosphate of high purity easily.

The present invention,

An aqueous solution of calcium hydroxide (Ca (OH) ₂ lime oil) and a first solution of calcium phosphate (Ca (H ₂ PO ₄ ) ₂ ) were reacted to contain tricalcium phosphate (Ca ₃ (PO ₄ ) ₂ ) near pH 7. An aqueous slurry is obtained, and the tricalcium phosphate is filtered from the obtained aqueous slurry, followed by drying, calcining and pulverization.

Calcium hydroxide (Ca (OH) ₂ ) used in the production method of the present invention is a wet grinding of pure white high purity CaO obtained by firing a processed shell (source of calcium carbonate such as shell shell and oyster shell) at 1100 ° C. in an electric furnace. It is preferable to obtain by.

When using calcium hydroxide manufactured by domestic limestone producers, lower and intermediate products should be of high quality because they are difficult to use due to color, iron content, etc.

The first calcium phosphate used in the production method of the present invention is prepared by reacting calcium carbonate or processed shell with a phosphate solution (H ₃ PO ₄ ).

Specifically, the method for preparing the third calcium phosphate of the present invention is first prepared by adding 30 g to 80 g of calcium hydroxide to 1 liter of water to make a dilute calcium hydroxide aqueous solution, and then adding the first calcium phosphate to 1 liter of water in the aqueous solution at room temperature. After the reaction was performed by adding the first aqueous calcium phosphate solution obtained by adding 70 g to 150 g, the reaction was stopped and left to stand at pH 7, and then the aqueous phase slurry was separated, and the third calcium phosphate was filtered from the aqueous phase slurry. The water is removed by drying at a temperature of 40 to 100 ° C., calcined in an electric furnace, and then pulverized to obtain tricalcium phosphate particles.

The first calcium phosphate aqueous solution may be used as it is the filtrate of the first calcium phosphate obtained by reacting limestone or processed shell, water, phosphoric acid and then filtered with a filter cloth.

When firing the dried third calcium phosphate in an electric furnace, the temperature is preferably 800 to 900 ° C. In addition, when grinding, it is preferable to grind in a ball mill to make fine particles, but other grinding apparatus may be used. The final particles obtained are packed by filtration screen with constant particle size.

Example

The calcium hydroxide was calcined by washing the oyster shell treated in the electric furnace at a temperature of 1100 ℃, mixed with the pure white CaO produced in a slurry state with water and then pulverized in a pulverizer using a fine particle calcium hydroxide separated by a screen of 250 to 325 mesh It was.

150 g of calcium hydroxide obtained above was dissolved in 3 liters of water to prepare an aqueous calcium hydroxide solution.

The first calcium phosphate is reacted with 3 liters of water, 2 mol of H ₃ PO ₄ (85% of industrial phosphoric acid), and limestone (1 mol to 1.2 mol) to stop the generation of CO ₂ bubbles. The filtrate was used as it is. The concentration of the filtrate is about 7%.

After the aqueous calcium hydroxide solution and the first calcium phosphate solution obtained above were reacted with vigorous stirring in a 10 liter stainless steel reaction vessel with a reaction stirrer at room temperature, the reaction was stopped when the pH reached about 7 An aqueous slurry containing tricalcium phosphate was obtained from the reaction vessel, filtered through a filter cloth, and dried at 80 ° C for 10 hours. The yield was about 73%. The dried tricalcium phosphate was calcined with an electric at 1300 ° C. for 5 hours and then pulverized with a grinder to obtain a final tricalcium phosphate powder.

The calcium hydroxide may be used as a product of Jangja Co., Ltd. or non-acid lime, but the color of the final tricalcium phosphate is pale yellowish brown, or the whiteness is slightly reduced.

The third calcium phosphate obtained by the production method of the present invention can be used in materials such as ceramics of the highest quality because the whiteness, strength, transparency and the like are significantly improved compared to the products obtained by the conventional synthetic method.

In addition, the method for preparing tricalcium phosphate of the present invention is compared with the conventional wet synthesis method for preparing tricalcium phosphate by reacting an aqueous solution of calcium chloride (CaCl ₂ ) with a solution of dibasic sodium phosphate (Na ₂ HPO ₄ ), Since many _secondary raw materials (Na ₂ CO ₃ , HCl, NH ₄ OH, etc.) are not added, the production cost is low and economical, and since there is almost no unreacted substance remaining in the aqueous slurry after the reaction, high purity tricalcium phosphate can be obtained. Since the manufacturing process is simple, mass production is possible as an industrial raw material.

Claims (6)

The aqueous calcium hydroxide solution at 30 to 80 g concentration per liter of water and the first calcium phosphate aqueous solution at 70 to 150 g concentration per liter of water were reacted to obtain an aqueous slurry near pH 7, and the third calcium phosphate was filtered from the aqueous slurry. And then drying, calcining, and pulverizing. The method according to claim 1, wherein the calcium hydroxide (Ca (OH) ₂ ) is obtained by wet pulverizing pure white high purity CaO obtained by firing calcium carbonate or a processed shell at 1100 ° C in an electric furnace. The method according to claim 1, wherein the first calcium phosphate is prepared by reacting calcium carbonate or a processed shell with a phosphate solution (H ₃ PO ₄ ). The method according to claim 1, wherein the third calcium phosphate is dried at a temperature of 40 to 100 ° C. The method according to claim 1, wherein the third calcium phosphate is fired in an electric furnace at a temperature of 800 to 900 占 폚. The method according to claim 1, wherein the first aqueous solution of calcium phosphate is used as it is in the filtered filtrate state after reacting limestone or processed shell, water and phosphoric acid.