阅读说明：本技术 一种光学级偏磷酸钙的制备方法 (Preparation method of optical-grade calcium metaphosphate ) 是由 蒋加富 于 2020-05-15 设计创作，主要内容包括：本发明技术方案提供了一种光学级偏磷酸钙的制备方法,包括如下步骤：将钙源与磷酸、水按一定比例在加热、加压条件下发生反应,得到粗磷酸二氢钙溶液,其中钙源选自氢氧化钙或氧化钙；调节粗磷酸二氢钙溶液的浓度并使其经过离子交换树脂,以脱除有色金属和杂质离子；将经过离子交换树脂后的溶液蒸发浓缩,提浓至25％以上；进行第一次洁净煅烧,以脱除游离水和结构水,得到偏磷酸钙中间体粉体；进行第二次洁净煅烧,获得光学级偏磷酸钙成品。本发明技术方案的制备方法对于原料氢氧化钙或氧化钙的适应性强,制备出的偏磷酸钙纯度较高,各项指标均满足光学玻璃和激光玻璃原料的要求,为激光玻璃和民用光学玻璃工业化生产提供一种关键高纯原材料。(The technical scheme of the invention provides a preparation method of optical-grade calcium metaphosphate, which comprises the following steps: reacting a calcium source with phosphoric acid and water according to a certain proportion under the conditions of heating and pressurizing to obtain a crude calcium dihydrogen phosphate solution, wherein the calcium source is selected from calcium hydroxide or calcium oxide; adjusting the concentration of the crude calcium dihydrogen phosphate solution and enabling the crude calcium dihydrogen phosphate solution to pass through ion exchange resin to remove nonferrous metals and impurity ions; evaporating and concentrating the solution after ion exchange resin, and concentrating to more than 25%; carrying out first clean calcination to remove free water and structural water to obtain calcium metaphosphate intermediate powder; and carrying out secondary clean calcination to obtain the optical grade calcium metaphosphate finished product. The preparation method of the technical scheme of the invention has strong adaptability to the raw material calcium hydroxide or calcium oxide, the prepared calcium metaphosphate has high purity, all indexes meet the requirements of the raw materials of optical glass and laser glass, and a key high-purity raw material is provided for the industrial production of the laser glass and the civil optical glass.)

1. A preparation method of optical-grade calcium metaphosphate is characterized by comprising the following steps:

1) reacting a calcium source with phosphoric acid and water according to a certain proportion under the conditions of heating and pressurizing to obtain a crude calcium dihydrogen phosphate solution, wherein the calcium source is selected from calcium hydroxide or calcium oxide;

2) adjusting the concentration of the crude calcium dihydrogen phosphate solution and enabling the crude calcium dihydrogen phosphate solution to pass through ion exchange resin to remove nonferrous metals and impurity ions;

3) evaporating and concentrating the solution after ion exchange resin, and concentrating to more than 25%;

4) carrying out first clean calcination to remove free water and structural water to obtain calcium metaphosphate intermediate powder;

5) and carrying out secondary clean calcination to obtain the optical grade calcium metaphosphate finished product.

2. The method for preparing optical grade calcium metaphosphate according to claim 1, wherein the molar ratio of said calcium source to said phosphoric acid is 1 (1.97-2.03), and the mass ratio of said phosphoric acid to water is 1 (2.1-3.5).

3. The process for preparing optical grade calcium metaphosphate according to claim 1, wherein in step 1), the reaction temperature is 120-140 ℃, the reaction pressure is 0.25-0.5 MPa, and the reaction time is 3-7 h.

4. The method of claim 1, wherein the concentration of the crude monocalcium phosphate solution is adjusted to 8% to 16%.

5. The method of claim 1, wherein the flow rate of the crude monocalcium phosphate solution through the ion exchange resin is from 1L/min to 5L/min.

6. The method of claim 1, wherein the ion exchange resin comprises a cation exchange resin and an anion exchange resin, the cation exchange resin comprises one or more of 732, D401, D402, D405, IONRISI 1600 and IONRISI 35, and the anion exchange resin comprises one or more of 201 × 7, D201, D202, D407 and IONRISI IRA 400.

7. The process for preparing optical grade calcium metaphosphate according to claim 1, wherein in step 3), the concentration is 25% to 30%.

8. The method for preparing optical grade calcium metaphosphate according to claim 1, wherein the concentrated calcium dihydrogen phosphate solution enters the spray calcination tower at a flow rate of 5L/min to 13L/min for the first clean calcination, wherein the inlet air temperature is 720 ℃ to 800 ℃, the upper section temperature of the tower body is 690 ℃ to 770 ℃, the middle section temperature of the tower body is 660 ℃ to 740 ℃, the lower section temperature of the tower body is 630 ℃ to 705 ℃, and the outlet air temperature is 400 ℃ to 475 ℃.

9. The method for preparing optical grade calcium metaphosphate according to claim 1, wherein the second clean calcination is carried out in an electric furnace, the calcination temperature of the electric furnace is 760 ℃ to 860 ℃, and the calcination time is 4h to 10 h.

Technical Field

The invention relates to the field of fine inorganic phosphorus chemical industry, in particular to a preparation method of optical-grade calcium metaphosphate.

Background

Metaphosphate is the most stable phosphate among dibasic phosphates, and is a basic raw material for the production of phosphate glass. The high-purity metaphosphate has excellent light transmittance, so that the metaphosphate can be used as an important raw material of laser glass in a high-power laser (such as national scientific engineering-Shenguang plan) and also can be used as an important raw material of some advanced optical equipment such as camera lenses, high-definition cameras, smart phone lenses and mobile phone panel substrates. The transition metals of Fe, Co, Ni and the like can cause strong absorption of metaphosphate glass in the near ultraviolet to infrared regions, and the optical performance of the glass is influenced. Therefore, the preparation of high purity metaphosphate raw material becomes the key to the manufacture of high performance laser glass.

Although China is a large country for producing phosphorus chemical industry, the development of high-additive and fine phosphorus chemical industry products is lagged, and the competitiveness of the international market is lacked. In view of technical blockade of international peers, the economic benefits of enterprises can be improved only by independent innovation, deep development of refined phosphorus chemical products is enhanced, high-tech content of the products is improved, and additional value of the products is improved.

Disclosure of Invention

In view of the above-mentioned current state of the art, the technical problem to be solved by the present invention is to provide a method for preparing optical grade calcium metaphosphate, wherein the main index of the prepared calcium metaphosphate can meet the requirement of manufacturing optical glass and laser glass.

In order to solve the technical problems, the technical scheme of the invention provides a preparation method of optical-grade calcium metaphosphate, which comprises the following steps:

1) reacting a calcium source with phosphoric acid and water according to a certain proportion under the conditions of heating and pressurizing to obtain a crude calcium dihydrogen phosphate solution, wherein the calcium source is selected from calcium hydroxide or calcium oxide;

2) adjusting the concentration of the crude calcium dihydrogen phosphate solution and enabling the crude calcium dihydrogen phosphate solution to pass through ion exchange resin to remove nonferrous metals and impurity ions;

3) evaporating and concentrating the solution after ion exchange resin, and concentrating to more than 25%;

4) carrying out first clean calcination to remove free water and structural water to obtain calcium metaphosphate intermediate powder;

5) and carrying out secondary clean calcination to obtain the optical grade calcium metaphosphate finished product.

Preferably, the molar ratio of the calcium source to the phosphoric acid is 1 (1.97-2.03), and the mass ratio of the phosphoric acid to the water is 1 (2.1-3.5). More preferably, the molar ratio of the calcium source to the phosphoric acid is 1 (1.985-2.015), and the mass ratio of the phosphoric acid to the water is 1 (2.2-2.9).

Preferably, in the step 1), the reaction temperature is 120-140 ℃, the reaction pressure is 0.25-0.5 MPa, and the reaction time is 3-7 h. Further preferably, the reaction temperature is 125-135 ℃, the reaction pressure is 0.3-0.45 MPa, and the reaction time is 4-6 h.

Preferably, the concentration of the crude monocalcium phosphate solution is adjusted to 8% -16%, the flow rate of the crude monocalcium phosphate solution passing through the ion exchange resin is 1L/min-5L/min, further, the concentration of the crude monocalcium phosphate solution is adjusted to 9% -14%, and the flow rate of the crude monocalcium phosphate solution passing through the ion exchange resin is 2L/min-4L/min.

Preferably, the ion exchange resin comprises cation exchange resin and anion exchange resin, the cation exchange resin comprises one or more of 732, D401, D402, D405, IONRISI 1600 and IONRISI 35, and the anion exchange resin comprises one or more of 201 × 7, D201, D202, D407 and IONRISI IRA 400.

Preferably, in the step 3), the concentration is 25 to 30 percent. More preferably, the concentration is 26-28%.

Preferably, the concentrated calcium dihydrogen phosphate solution enters a spray calcining tower at the flow rate of 5L-13L/min for first clean calcination, wherein the air inlet temperature is 720-800 ℃, the upper section temperature of the tower body is 690-770 ℃, the middle section temperature of the tower body is 660-740 ℃, the lower section temperature of the tower body is 630-705 ℃, and the air outlet temperature is 400-475 ℃.

And further, the concentrated calcium dihydrogen phosphate solution enters a spray calcining tower at the flow rate of 7L/min-10L/min for first clean calcination, wherein the air inlet temperature is 740-780 ℃, the upper section temperature of the tower body is 710-755 ℃, the middle section temperature of the tower body is 680-725 ℃, the lower section temperature of the tower body is 655-690 ℃, and the air outlet temperature is 420-450 ℃.

In the process of spray calcination, in order to ensure that materials are not polluted, clean calcination is required to be ensured, only an indirect heating mode is adopted, and the following problems are that the highest air inlet temperature of a spray calcination tower can only reach 780-800 ℃ (the tower body temperature can only reach 700-740 ℃), and in the working condition of instantaneous calcination dehydration, the temperature section is difficult to completely dehydrate for the calcination of calcium metaphosphate, 97% of calcium dihydrogen phosphate structural water can be removed at most, and higher lasting temperature and further calcination equipment are required to remove the final trace structural water. Therefore, the invention adopts a secondary calcination method, and carries out secondary clean calcination in an electric furnace, wherein the calcination temperature of the electric furnace is 760-860 ℃, and the calcination time is 4-10 h.

Furthermore, the calcining temperature of the electric furnace is 790-840 ℃, and the calcining time is 6-9 h. The hearth is lined with high-purity corundum or high-purity quartz material.

The preparation method of the optical grade calcium metaphosphate provided by the technical scheme of the invention has the following beneficial effects: the method has strong adaptability to the raw materials of calcium hydroxide or calcium oxide, adopts a mode of removing impurities by an ion exchange method, indirectly heating, cleaning, spraying and calcining and combining with the cleaning and calcining of a high-temperature electric furnace, and the prepared calcium metaphosphate has high purity, all indexes meet the requirements of optical glass and laser glass raw materials, and a key high-purity raw material is provided for the industrial production of the laser glass and the civil optical glass.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor.

Fig. 1 is a flow chart of a method for preparing optical grade calcium metaphosphate according to the technical scheme of the invention.

Detailed Description

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, the features and the effects of the present invention.

As shown in fig. 1, the preparation method of optical grade calcium metaphosphate in the present invention comprises the following steps:

1) reacting a calcium source (illustrated in figure 1 by taking industrial calcium hydroxide as an example) with industrial phosphoric acid and water according to a certain proportion under the conditions of heating and pressurizing to obtain a crude calcium dihydrogen phosphate solution;

2) adjusting the concentration of the crude calcium dihydrogen phosphate solution and enabling the crude calcium dihydrogen phosphate solution to pass through ion exchange resin to remove nonferrous metals and impurity ions;

3) evaporating and concentrating the solution after ion exchange resin, and concentrating to more than 25%;

4) carrying out first clean calcination to remove free water and structural water to obtain calcium metaphosphate intermediate powder;

5) and carrying out secondary clean calcination to obtain the optical grade calcium metaphosphate finished product.