Method for producing high-purity phosphoric acid by quantum behavior control

Abstract

To provide a method for producing high-purity phosphoric acid that allows low-grade phosphoric acid to be obtained as high-purity phosphoric acid in an economical and industrial manner.SOLUTION: By utilizing a temperature difference between interior and exterior jackets of a cooling device, crystal growth positions and growth rates of phosphoric acid crystals are controlled by changes in molecular or quantum behavior of impurities in phosphoric acid, thereby suppressing a phenomenon of entrapment of impurities inside phosphoric acid crystals to obtain phosphoric acid crystals.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing high-purity phosphoric acid by controlling quantum behavior, and more specifically, to a method for producing high-purity phosphoric acid, which can economically and industrially produce high-purity phosphoric acid from low-grade phosphoric acid by controlling the crystal growth position and speed of phosphoric acid crystals through changes in the molecular or quantum behavior of phosphoric acid, water molecules, and impurities in a phosphoric acid raw material using the temperature difference between the internal and external jackets of a cooling device, thereby suppressing the confinement phenomenon of impurities inside the phosphoric acid crystals and obtaining phosphoric acid crystals. [Background technology]

[0002] Phosphoric acid is the only substance that can wet etch semiconductor silicon nitride film (Si3N4, SiN) and is an essential chemical material in the semiconductor manufacturing process. In this silicon nitride film etching process, impurities in the phosphoric acid etchant have a direct impact on semiconductor yield and the occurrence of defects, so their concentration is strictly controlled.

[0003] High-purity phosphoric acid suitable for use in semiconductor manufacturing can only be produced by a dry process in which yellow phosphorus (P4) is extracted from high-quality phosphate rock and then oxidized and burned at high temperatures of over 200°C, requiring significant process costs.

[0004] In addition, because reserves of high-quality phosphate rock are limited, there is a problem that the price of high-purity phosphoric acid will continue to rise due to the accelerating depletion of minerals, which will lead to economic problems such as increased semiconductor manufacturing costs.

[0005] Conventionally, various methods have been proposed for purifying phosphoric acid containing a large amount of metal ion impurities, such as membrane separation, ion exchange, and liquid extraction.

[0006] First, the membrane separation method has the advantage of high yield and purity of recovered phosphoric acid, but has the disadvantages of high membrane separation process cost and complicated operation method. Also, the corrosive nature of phosphoric acid can cause stability issues for the membranes used.

[0007] The ion exchange method uses ion exchange resin or calcium zeolite to remove acid. However, the ion exchange resin used here has a low ion exchange capacity and can only treat low-concentration acids. In addition, the ion exchange resin must be continuously replaced after ion exchange is complete, resulting in continuous process costs.

[0008] The liquid extraction method has the advantages of being able to operate the process continuously and requiring inexpensive equipment, but has the disadvantage of not being able to obtain phosphoric acid with the high purity required in semiconductor processes.

[0009] The crystallization method is a method of producing crystals from a saturated solution by controlling the rate of crystal nucleation and crystal growth.

[0010] The crystallization method is divided into a method using phosphoric acid seeds to promote nucleation of crystals and a method without using phosphoric acid seeds. When phosphoric acid seeds are not used, crystallization can only proceed by controlling the crystallization conditions to a temperature of -40°C or less, which results in a problem of high cost and time required to produce crystals.

[0011] Therefore, there is a demand for the development of a new method for producing phosphoric acid that can economically and industrially obtain high-purity phosphoric acid that does not contain unnecessary metals by separating impurities from a phosphoric acid raw material that contains a large amount of impurities. Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to provide a method for producing high-purity phosphoric acid by controlling quantum behavior, which allows phosphoric acid to be obtained economically and industrially.

[0013] According to the present invention, the temperature difference between the inner and outer jackets of a cooling device is utilized to change the molecular or quantum behavior of phosphoric acid, water molecules, and impurities in the phosphoric acid raw material, thereby controlling the crystal growth position and speed of phosphoric acid crystals, thereby suppressing the confinement phenomenon of impurities inside the phosphoric acid crystals and obtaining phosphoric acid crystals, thereby providing a method for producing high-purity phosphoric acid from low-grade phosphoric acid in an economical and industrial manner. [Means for solving the problem]

[0014] The present invention can provide a method for producing high-purity phosphoric acid, which includes a step (S1) of supplying phosphoric acid raw material containing impurities to a cooling device including an inner jacket and an outer jacket, and a step (S2) of adding phosphoric acid seeds to the cooling device to form phosphoric acid crystals, wherein the temperature difference between the inner jacket and the outer jacket is 5°C or more.

[0015] The temperature difference between the inner jacket and the outer jacket may be 40°C or less.

[0016] The temperature of the inner jacket may be 0 to 30°C.

[0017] The temperature of the outer jacket may be 5 to 50°C.

[0018] The concentration of the phosphoric acid raw material may be 85 to 91.6%.

[0019] The method for producing high-purity phosphoric acid of the present invention may further include, after the phosphoric acid crystal formation step (S2), a step (S3) of heating the inner jacket to 30 to 35°C to partially melt a part of the crystallized phosphoric acid.

[0020] The method for producing high purity phosphoric acid of the present invention may further include a step (S4) of heating the inner jacket to 40°C or higher after separating the partially melted phosphoric acid, thereby obtaining phosphoric acid crystals that are not melted in the partially melting step (S3).

[0021] The phosphoric acid raw material may have a total content of impurities including Al, K and Cu of 300 ppb or more.

[0022] The phosphoric acid obtained by the above method may contain Al, K and Cu at 1 ppb or less each. [Effects of the Invention]

[0023] When the method for producing high-purity phosphoric acid by controlling quantum behavior provided by the present invention is used, it is possible to produce high-purity phosphoric acid economically and industrially. DETAILED DESCRIPTION OF THE INVENTION

[0024] Unless otherwise defined herein, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used to describe the present invention are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention.

[0025] As used herein, the singular forms "a," "an," and "the" include the plural forms as well, unless the context clearly dictates to the contrary.

[0026] As used herein, the meaning of "comprising" embodies certain properties, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other certain properties, regions, integers, steps, operations, elements, components, and / or groups.

[0027] Although the present invention can be embodied in various forms through various modifications, specific embodiments will be described in detail below by way of example, but it should be understood that this is not intended to limit the present invention to the specific disclosed embodiments, and that the present invention encompasses all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention.

[0028] In this specification, when the positional relationship of two parts is described using, for example, "above," "on top," "below," or "to the side," one or more other parts may be located between the two parts, unless the expressions "directly" or "immediately" are used.

[0029] In this specification, when a temporal relationship is described using, for example, "after," "following," "next," or "before," the expressions "directly" or "immediately" are not used, and therefore non-consecutive cases may also be included.

[0030] As used herein, the term "at least one" should be understood to include all possible combinations of one or more associated items.

[0031] Hereinafter, a method for producing high-purity phosphoric acid according to a specific embodiment of the invention will be described in more detail.

[0032] According to one embodiment of the present invention, there is provided a method for producing high-purity phosphoric acid, comprising: a step (S1) of supplying impurity-containing phosphoric acid raw material to a cooling device including an inner jacket and an outer jacket; and a step (S2) of adding phosphoric acid seeds to the cooling device to form phosphoric acid crystals, wherein the temperature difference between the inner jacket and the outer jacket is 5°C or more.

[0033] As described above, a conventional method of purifying phosphoric acid by cooling to crystallize it is well known. However, if phosphoric acid seeds are not used, crystallization can only proceed by controlling the crystallization conditions at a temperature of -40°C or lower, which poses a problem of high cost and time required for producing crystals.

[0034] Therefore, in the present invention, the inventors have studied a method for promoting crystallization at room temperature using phosphoric acid seeds and further increasing purification efficiency. They have found that when a cooling device including an inner jacket and an outer jacket is used and the temperature difference between the inner jacket and the outer jacket is adjusted to a certain level, the crystal growth position and speed of phosphoric acid crystals can be controlled by changing the molecular or quantum behavior of phosphoric acid, water molecules, and impurities in the phosphoric acid raw material, thereby suppressing the trapping phenomenon of impurities inside the phosphoric acid crystals, thereby increasing purification efficiency and enabling high-purity phosphoric acid to be obtained economically and on an industrial scale, which has led to the completion of the present invention.

[0035] According to the present invention, the method includes a step (S1) of supplying phosphoric acid raw material containing impurities to a cooling device including an inner jacket and an outer jacket, and a step (S2) of adding phosphoric acid seeds to the cooling device to form phosphoric acid crystals. When the temperature difference between the inner jacket and the outer jacket is adjusted to 5°C or more, the efficiency of purifying impurities is improved and phosphoric acid of higher purity can be obtained.

[0036] First, the phosphoric acid raw material may be low-purity (industrial-grade) phosphoric acid available on the market, or phosphoric acid used in a semiconductor etching process may be recovered and used. From the viewpoint of resource recycling, however, it is preferable to recover and use phosphoric acid containing impurities used in a semiconductor process.

[0037] In the method for producing high purity phosphoric acid of the present invention, phosphoric acid raw material containing a large amount of impurities is supplied to a cooling device including an inner jacket and an outer jacket, and phosphoric acid seeds are then introduced into the cooling device to form phosphoric acid crystals. At this time, the temperature difference between the inner jacket and the outer jacket is set to 5°C or more, thereby increasing the efficiency of purifying impurities.

[0038] Specifically, by creating a temperature difference between the inner jacket and the outer jacket of the cooling device, sporadic crystal formation due to changes in the molecular or quantum behavior of phosphoric acid, water molecules, and impurities in the phosphoric acid raw material can be prevented, and crystal growth can be induced to begin on the surface of the inner jacket, thereby preventing the trapping phenomenon in which metal impurities are trapped inside phosphoric acid crystals and improving the purification efficiency of the metal impurities.

[0039] When phosphoric acid seeds are added to form phosphoric acid crystals, if there is no or only a slight temperature difference between the inner and outer jackets, phosphoric acid crystallization occurs sporadically, and impurities are trapped inside the phosphoric acid crystals due to the trapping phenomenon, which causes a large amount of impurities to be contained inside the phosphoric acid crystals, resulting in a decrease in the purity of the phosphoric acid obtained by crystallization.

[0040] On the other hand, when the temperature difference between the inner jacket and the outer jacket is adjusted to a certain level or more and phosphoric acid seeds are added to promote crystallization, the difference in phosphoric acid crystal growth rate between the inside and outside occurs due to changes in the molecular and quantum behavior of phosphoric acid, water molecules, and impurities in the phosphoric acid raw material, preventing sporadic generation of phosphoric acid crystals. By inducing phosphoric acid crystal growth to begin on the surface of the inner jacket, crystallization progresses so that impurities gather on the outer jacket side, increasing purification efficiency and enabling the production of high-purity phosphoric acid.

[0041] The cooling device includes an inner jacket and an outer jacket formed outside the inner jacket at a distance, and a reaction section having a certain space between the inner jacket and the outer jacket, where phosphoric acid raw material, phosphoric acid seeds, etc. are introduced and phosphoric acid crystallization proceeds.

[0042] That is, when the phosphoric acid raw material and phosphoric acid seeds are introduced into the reaction zone, which is the space between the inner jacket and the outer jacket, phosphoric acid crystals are formed and grow along the surface of the inner jacket so as to surround the inner jacket due to the temperature difference between the inner jacket and the outer jacket.

[0043] At this time, the temperature difference between the inner jacket and the outer jacket may be 5° C. or more, preferably 10° C. or more. If the temperature difference between the inner jacket and the outer jacket is less than 5° C., phosphoric acid crystals are generated sporadically, which may cause a problem of reduced purification efficiency due to a trapping phenomenon in which metal impurities are trapped in the phosphoric acid crystals.

[0044] Also, the temperature difference between the inner jacket and the outer jacket may be 40° C. or less. If the temperature difference between the inner jacket and the outer jacket exceeds 40° C., a problem may occur in which phosphoric acid crystals cannot grow sufficiently.

[0045] Specifically, the temperature of the inner jacket may be 0 to 30°C, and the temperature of the outer jacket may be 5 to 50°C.

[0046] At this time, within the temperature range, the inner jacket has a lower temperature than the outer jacket.

[0047] After supplying the phosphoric acid raw material containing impurities to a cooling device including an inner jacket and an outer jacket, phosphoric acid seeds are added to the cooling device to form phosphoric acid crystals. At this time, the amount of the phosphoric acid seeds may be 0.01 to 10 parts by weight based on 100 parts by weight of the phosphoric acid raw material.

[0048] If the amount of phosphoric acid seeds added is too small, problems may occur such as a slow phosphoric acid crystallization rate or no crystal growth, whereas if the amount of phosphoric acid seeds added is too large, phosphoric acid crystals may be generated sporadically. Therefore, it is preferable to add the phosphoric acid seeds in the above-mentioned amounts.

[0049] The method for producing high-purity phosphoric acid of the present invention may further include, after the phosphoric acid crystal formation step (S2), a step (S3) of heating the inner jacket to 30 to 35°C to partially melt a part of the crystallized phosphoric acid.

[0050] The crystallized phosphoric acid that grows along the surface of the inner jacket during the crystallization process contains pure phosphoric acid with almost no impurities inside the crystal, and the impurity content increases as you move closer to the crystal surface.

[0051] Therefore, by raising the temperature of the inner jacket to 30 to 35°C and partially melting part of the surface of the phosphoric acid crystal, impurities adhering to the surface can be removed to obtain phosphoric acid of higher purity.

[0052] Thereafter, after separating the partially melted phosphoric acid, the temperature of the inner jacket is raised to 40° C. or higher, and unmelted phosphoric acid crystals can be obtained in the partial melting step (S3) (S4).

[0053] The phosphoric acid raw material before purification contains a large amount of impurities, and specifically, the phosphoric acid raw material may have a total content of impurities including Al, K, and Cu of 300 ppb or more.

[0054] As described above, the method for producing high-purity phosphoric acid of the present invention can economically and industrially produce high-purity phosphoric acid. Specifically, the phosphoric acid obtained by the method can contain Al, K, and Cu at levels of 1 ppb or less, respectively. [Example]

[0055] Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0056] (1) Example 1 1,000 g of 91.6% phosphoric acid raw material containing impurities was supplied to a cooling device in which the inner jacket was set to 15°C and the outer jacket was set to 25°C (the temperature difference between the inner jacket and the outer jacket was 10°C).

[0057] 1 g of phosphoric acid seeds was added to the cooling device, and phosphoric acid crystallization was allowed to proceed for 1 hour.

[0058] After removing the uncrystallized phosphoric acid, the temperature of the inner jacket was raised to 30°C, and part of the crystallized phosphoric acid was partially melted and separated.

[0059] The remaining unmelted phosphoric acid crystals (779 g) were heated to 40° C. or higher until they were completely melted, thereby obtaining a final purified crystallized phosphoric acid.

[0060] (2) Example 2 The procedure was the same as in Example 1, except that the inner jacket was set to 0°C and the outer jacket to 25°C, to obtain 795 g of crystallized phosphoric acid (the temperature difference between the inner jacket and the outer jacket was 25°C).

[0061] (3) Example 3 The procedure was the same as in Example 2, except that the inner jacket was set to 0°C and the outer jacket to 40°C, to obtain 614 g of crystallized phosphoric acid (the temperature difference between the inner and outer jackets was 40°C).

[0062] (4) Example 4 The same procedure as in Example 1 was carried out, except that the concentration of the phosphoric acid raw material was set to 85%, to obtain 463 g of crystallized phosphoric acid.

[0063] (5) Comparative Example 1 The procedure was carried out in the same manner as in Example 1, except that the temperatures of the inner jacket and the outer jacket were both set to 15°C (no temperature difference between the inner jacket and the outer jacket), to obtain 600g of crystallized phosphoric acid.

[0064] (6) Comparative Example 2 1,000 g of 91.6% phosphoric acid raw material containing impurities was supplied to a cooling device in which the inner jacket was set to 5°C and the outer jacket was set to 50°C (the temperature difference between the inner jacket and the outer jacket was 45°C).

[0065] 1 g of phosphoric acid seeds was added to the cooling device, and phosphoric acid crystallization was allowed to proceed for 1 hour.

[0066] The uncrystallized phosphoric acid was removed, and the temperature of the inner jacket was raised to 30°C in an attempt to partially melt and separate some of the crystallized phosphoric acid. However, when the temperature was raised to 30°C, all of the crystallized phosphoric acid melted, and as a result, further heating (above 40°C) was not possible.

[0067] <Analysis of Metal Impurities in Crystallized Phosphoric Acid> The metal impurity contents in the phosphoric acid raw material, amorphous phosphoric acid and phosphoric acid separated by partial melting, and crystallized phosphoric acid obtained by heating to 40°C or higher were analyzed using ICP-MS.

[0068] Specifically, using an Agilent ICP-MS 8900, non-crystallized phosphoric acid, partially molten phosphoric acid, and crystallized phosphoric acid were diluted with DIW or 3% nitric acid to analyze the content of metal impurities in the samples.

[0069] [Table 1]

[0070] [Table 2]

[0071] According to Tables 1 and 2, it was confirmed that the metal content in the phosphoric acid obtained by the production method of the present invention is significantly reduced compared to that of the raw material phosphoric acid, and high-purity phosphoric acid can be obtained.

[0072] In the case of Comparative Example 1, the metal content was lower than that of the phosphoric acid raw material, but the refining effect was slight. In the case of Comparative Example 2, all of the phosphoric acid crystallized during the partial melting of phosphoric acid was dissolved, and no refining by crystallization was performed.

Claims

1. A step (S1) of supplying impurity-containing phosphoric acid raw material to a cooling device including an inner jacket and an outer jacket; (S2) adding phosphoric acid seeds to the cooling device to form phosphoric acid crystals; The temperature difference between the inner jacket and the outer jacket is 5°C or more. A method for producing high-purity phosphoric acid.

2. 2. The method for producing high-purity phosphoric acid according to claim 1, wherein the temperature difference between the inner jacket and the outer jacket is 40° C. or less.

3. 2. The method for producing high-purity phosphoric acid according to claim 1, wherein the temperature of the inner jacket is 0 to 30°C.

4. 2. The method for producing high-purity phosphoric acid according to claim 1, wherein the temperature of the outer jacket is 5 to 50°C.

5. After the phosphoric acid crystal formation step (S2), 2. The method for producing high-purity phosphoric acid according to claim 1, further comprising: a step (S3) of raising the temperature of the inner jacket to 30 to 35° C. to partially melt a portion of the crystallized phosphoric acid.

6. 6. The method for producing high-purity phosphoric acid according to claim 5, further comprising: a step (S4) of raising the temperature of the inner jacket to 40°C or higher after separating the partially melted phosphoric acid, thereby obtaining phosphoric acid crystals that are not melted in the partial melting step (S3).

7. 2. The method for producing high purity phosphoric acid according to claim 1, wherein the concentration of the phosphoric acid raw material is 85 to 91.6%.

8. 2. The method for producing high-purity phosphoric acid according to claim 1, wherein the phosphoric acid raw material has a total content of impurities including Al, K, and Cu of 300 ppb or more.

9. 2. The method for producing high-purity phosphoric acid according to claim 1, wherein the phosphoric acid obtained by the method contains Al, K and Cu each at 1 ppb or less.

Images