阅读说明：本技术 一种光学级偏磷酸锶的制备方法 (Preparation method of optical-grade strontium 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锶的制备方法,包括如下步骤：按一定比例使锶源、磷酸和水在加热、加压条件下发生反应,得到粗磷酸二氢锶溶液,所述锶源为氧化锶或氢氧化锶；调节所述粗磷酸二氢锶溶液的浓度,并以一定流速经过离子交换树脂,以脱除有色金属和杂质离子；蒸发浓缩,获得含磷酸二氢锶浓度在24％以上的提浓液；脱除提浓液中的游离水和结构水,获得偏磷酸锶中间体粉体；经煅烧,获得光学级偏磷酸锶成品。本发明的制备方法对于原料氢氧化锶的适应性强,采用离子交换法除杂,间接加热洁净喷雾煅烧结合高温电炉洁净煅烧的方式,可制备出高纯度的偏磷酸锶,各项指标均满足光学玻璃和激光玻璃原料的要求。(The technical scheme of the invention provides a preparation method of optical grade strontium metaphosphate, which comprises the following steps: reacting a strontium source, phosphoric acid and water in a certain proportion under the conditions of heating and pressurizing to obtain a crude strontium dihydrogen phosphate solution, wherein the strontium source is strontium oxide or strontium hydroxide; adjusting the concentration of the crude strontium dihydrogen phosphate solution, and passing through ion exchange resin at a certain flow rate to remove nonferrous metals and impurity ions; evaporating and concentrating to obtain concentrated solution containing strontium dihydrogen phosphate with concentration of more than 24%; removing free water and structural water in the concentrated solution to obtain strontium metaphosphate intermediate powder; and calcining to obtain the optical grade strontium metaphosphate finished product. The preparation method has strong adaptability to the raw material strontium hydroxide, adopts the mode of removing impurities by an ion exchange method, and combining indirect heating clean spray calcination with high-temperature electric furnace clean calcination, and can prepare high-purity strontium metaphosphate, and all indexes of the strontium metaphosphate meet the requirements of optical glass and laser glass raw materials.)

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

(1) reacting a strontium source, phosphoric acid and water in a certain proportion under the conditions of heating and pressurizing to obtain a crude strontium dihydrogen phosphate solution, wherein the strontium source is strontium oxide or strontium hydroxide;

(2) adjusting the concentration of the crude strontium dihydrogen phosphate solution, and passing through ion exchange resin at a certain flow rate to remove nonferrous metals and impurity ions;

(3) evaporating and concentrating to obtain concentrated solution containing strontium dihydrogen phosphate with concentration of more than 24%;

(4) removing free water and structural water in the concentrated solution to obtain strontium metaphosphate intermediate powder;

(5) and calcining to obtain the optical grade strontium metaphosphate finished product.

2. The method for preparing optical grade strontium metaphosphate according to claim 1, wherein in the step (1), the molar ratio of the strontium source to the phosphoric acid is 1 (1.97-2.03), the mass ratio of the phosphoric acid to the water is 1 (2.0-3.6), the reaction temperature is 125-145 ℃, the reaction pressure is 0.3-0.55 MPa, and the reaction time is 3-6 h.

3. The method for preparing optical grade strontium metaphosphate of claim 1, wherein in step (2), the concentration of said crude strontium dihydrogen phosphate is adjusted to 7% -17%.

4. The method of claim 1, wherein the ion exchange resin comprises a cation exchange resin comprising 741, D001, iorreiesin nir1200F, iorrein 1600, iorrein 252, or a combination thereof, and an anion exchange resin comprising 201 x 4, 201 x 7, D201, D406, or a combination thereof.

5. The method of claim 1, wherein the flow rate through the cation exchange resin and the anion exchange resin is 1L/min to 5L/min.

6. The method of claim 1, wherein the concentration of strontium dihydrogen phosphate in the concentrate is from 24% to 30%.

7. The method of claim 1, wherein the optical grade strontium metaphosphate is dehydrated by feeding the concentrate to a spray calcination tower, wherein the spray calcination tower has an inlet air temperature of 710 to 800 ℃, an upper tower section temperature of 680 to 760 ℃, a middle tower section temperature of 650 to 730 ℃, a lower tower section temperature of 620 to 700 ℃, an outlet air temperature of 390 to 465 ℃ and a flow rate of the concentrate into the tower body of 6 to 13L/min.

8. The method for preparing optical-grade strontium metaphosphate of claim 7, wherein the material contact part in the spray calcination tower is made of high-purity alumina lining, the spray head is made of titanium-palladium alloy, the heating mode is indirect heating, and the intake air needs to be subjected to multi-stage purification treatment.

9. The method for preparing optical grade strontium metaphosphate of claim 1, wherein the optical grade strontium metaphosphate is calcined by an electric furnace, the hearth of the electric furnace is lined with high-purity corundum or high-purity quartz material, the calcination temperature is 780-860 ℃, and the calcination time is 5-12 h.

Technical Field

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

Disclosure of Invention

In view of the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a method for preparing optical grade strontium metaphosphate.

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

(1) reacting a strontium source, phosphoric acid and water in a certain proportion under the conditions of heating and pressurizing to obtain a crude strontium dihydrogen phosphate solution, wherein the strontium source is strontium oxide or strontium hydroxide;

(2) adjusting the concentration of the crude strontium dihydrogen phosphate solution, and passing through ion exchange resin at a certain flow rate to remove nonferrous metals and impurity ions;

(3) evaporating and concentrating to obtain concentrated solution containing strontium dihydrogen phosphate with concentration of more than 24%;

(4) removing free water and structural water in the concentrated solution to obtain strontium metaphosphate intermediate powder;

(5) and calcining to obtain the optical grade strontium metaphosphate finished product.

Preferably, in the step (1), the molar ratio of the strontium source to the phosphoric acid is 1 (1.97-2.03), the mass ratio of the phosphoric acid to the water is 1 (2.0-3.6), the reaction temperature is 125-145 ℃, the reaction pressure is 0.3-0.55 MPa, and the reaction time is 3-6 h. Further preferably, the molar ratio of the strontium source to the phosphoric acid is 1 (0.985-2.015), the mass ratio of the phosphoric acid to the water is 1 (2.1-2.9), the reaction temperature is 130-140 ℃, the reaction pressure is 0.38-0.47 MPa, and the reaction time is 3.5-5 h.

Preferably, in the step (2), the concentration of the crude strontium dihydrogen phosphate is adjusted to 7 to 17 percent. More preferably, it is 9% to 15%.

Preferably, the ion exchange resin comprises a cation exchange resin and an anion exchange resin, the cation exchange resin comprises 741, D001, IONRESIN IR1200F, IONRESIN1600 and IONRESIN252, and the anion exchange resin comprises 201 × 4, 201 × 7, D201, D406 and D407.

Preferably, the flow rate through the cation exchange resin and the anion exchange resin is 1L/min to 5L/min. More preferably, it is 2L/min to 4L/min.

Preferably, the concentration of the strontium dihydrogen phosphate in the concentrated solution is 24-30%, and more preferably, 26-29%.

Preferably, the concentrated solution is sent to a spray calcining tower for dehydration, wherein the air inlet temperature of the spray calcining tower is 710-800 ℃, the temperature of the upper section of the tower body is 680-760 ℃, the temperature of the middle section of the tower body is 650-730 ℃, the temperature of the lower section of the tower body is 620-700 ℃, the air outlet temperature is 390-465 ℃, and the flow rate of the concentrated solution pumped into the tower body is 6-13L/min. Further, the air inlet temperature is 750-780 ℃, the temperature of the upper section of the tower body is 720-750 ℃, the temperature of the middle section of the tower body is 685-720 ℃, the temperature of the lower section of the tower body is 660-685 ℃, the air outlet temperature is 420-455 ℃, and the flow rate of the concentrated solution pumped into the tower body is 7-11L/min.

Preferably, in order to ensure the product quality, the material contact part of the calcining tower adopts a high-purity alumina lining, the spray head is made of titanium palladium alloy, the heating mode adopts indirect heating, and the air inlet needs to be subjected to multi-stage purification treatment.

The indirect heating is adopted, and the problem that the highest inlet air temperature of a spray calcining tower can only reach 780-800 ℃ (the tower body temperature can only reach 700-.

Preferably, the material is calcined by an electric furnace, a hearth is lined by high-purity corundum or high-purity quartz material, the calcining temperature is 780-860 ℃, and the calcining time is 5-12 h. Furthermore, the calcining temperature of the electric furnace is 800-840 ℃, and the calcining time is 7-10 h.

The preparation method of the optical grade strontium metaphosphate in the technical scheme of the invention has the following beneficial effects:

the adaptability to the raw material strontium hydroxide is strong, the method of removing impurities by an ion exchange method, and combining indirect heating clean spray calcination with high-temperature electric furnace clean calcination can prepare high-purity strontium metaphosphate, and each index meets the requirements of optical glass and laser glass raw materials.

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 strontium 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 method for preparing optical grade strontium metaphosphate in accordance with the present invention comprises the following steps:

(1) reacting a strontium source, such as strontium hydroxide, phosphoric acid and water, in a certain proportion under the conditions of heating and pressurizing to obtain a crude strontium dihydrogen phosphate solution;

(2) adjusting the concentration of the crude strontium dihydrogen phosphate solution (i.e. the concentration adjusting step in fig. 1), and passing through an ion exchange resin at a certain flow rate to remove non-ferrous metals and impurity ions;

(3) evaporating and concentrating to obtain concentrated solution containing strontium dihydrogen phosphate with concentration of more than 24%;

(4) removing free water and structural water in the concentrated solution (namely the clean spray calcination step in figure 1) to obtain intermediate powder of strontium metaphosphate;

(5) and calcining (namely calcining in a clean electric furnace in figure 1) to obtain the finished product of the optical grade strontium metaphosphate.

The following describes in detail the method for preparing optical grade strontium metaphosphate according to the present invention with reference to specific examples.