阅读说明：本技术 一种光学级偏磷酸钕的制备方法 (Preparation method of optical grade neodymium 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钕的制备方法,包括如下步骤：配置磷酸二氢铵水溶液,并除去水不溶物；经过离子交换装置,以脱除有色金属和杂质离子；并结合氧化钕与光学级磷酸二氢铵固固中-高温两段法洁净煅烧反应,可制备得到光学级偏磷酸钕。本发明技术方案的制备方法对于原料的适应性较强,制备的光学级偏磷酸钕的主要技术指标均满足光学级原料的要求。(The technical scheme of the invention provides a preparation method of optical grade neodymium metaphosphate, which comprises the following steps: preparing an ammonium dihydrogen phosphate aqueous solution, and removing water insoluble substances; removing nonferrous metals and impurity ions by an ion exchange device; and the optical grade neodymium metaphosphate can be prepared by combining the neodymium oxide and the optical grade ammonium dihydrogen phosphate solid-solid medium-high temperature two-stage method for clean calcination reaction. The preparation method of the technical scheme of the invention has stronger adaptability to raw materials, and the main technical indexes of the prepared optical grade neodymium metaphosphate all meet the requirements of optical grade raw materials.)

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

(1) preparing an ammonium dihydrogen phosphate aqueous solution, and removing water insoluble substances;

(2) the ammonium dihydrogen phosphate aqueous solution passes through an ion exchange device to remove nonferrous metals and impurity ions;

(3) evaporating and concentrating to obtain concentrated solution, wherein the mass fraction of ammonium dihydrogen phosphate in the concentrated solution is more than 35%;

(4) cooling and crystallizing the concentrated solution, performing centrifugal separation, drying the separated solid substance to form optical-grade ammonium dihydrogen phosphate, and combining the separated liquid with the solution subjected to ion exchange in the step (2);

(5) optical-grade ammonium dihydrogen phosphate and neodymium oxide are uniformly mixed and subjected to polymerization reaction to obtain a neodymium metaphosphate intermediate;

(6) after clean pre-crushing the neodymium metaphosphate intermediate, calcining to obtain neodymium metaphosphate powder;

(7) and (3) cleanly crushing and cleanly mixing the neodymium metaphosphate powder to obtain the finished product of the optical grade neodymium metaphosphate powder.

2. The method of claim 1, wherein in step (1), the ammonium dihydrogen phosphate aqueous solution has a solute mass fraction of 7% to 17%.

3. The method according to claim 1, wherein in step (2), the ion exchange device is filled with cation exchange resin and anion exchange resin, the cation exchange resin comprises one or more selected from 001 × 4, 741, D001, iorreisin IR120 and iorreisin 35, and the anion exchange resin comprises one or more selected from D202, 201 × 4, 201 × 7, D406 and D407.

4. The method of claim 1, wherein in step (2), the flow rate of the aqueous ammonium dihydrogen phosphate solution through the ion exchange unit is from 1L/min to 5L/min.

5. The method of claim 1, wherein in step (3), the concentration solution contains 35-43% ammonium dihydrogen phosphate.

6. The process for preparing optical grade neodymium metaphosphate according to claim 1, wherein in the step (4), the cooling crystallization temperature is 20 ℃ to 30 ℃ and the crystallization time is 1h to 4 h.

7. The method for preparing optical grade neodymium metaphosphate of claim 1, wherein in the step (4), the separated solid substance is dried by a high efficiency boiling dryer, the inlet air temperature of the high efficiency boiling dryer is 130-160 ℃, the tower body temperature is 115-145 ℃, the outlet air temperature is 90-110 ℃, and the drying time is 1.5-4 h.

8. The method of claim 1, wherein in step (5), the molar ratio of neodymium oxide to optical grade ammonium dihydrogen phosphate is 1 (5.9-6.1).

9. The process for preparing optical grade neodymium metaphosphate according to claim 1, wherein the polymerization reaction in step (5) is carried out at a temperature of 470 ℃ to 560 ℃ for a reaction time of 5 hours to 10 hours.

10. The method of claim 1, wherein in step (6), the calcination temperature is 760 ℃ to 850 ℃ and the calcination time is 3h to 8 h.

Technical Field

The invention relates to the field of fine inorganic phosphorus chemical industry, in particular to a preparation method of optical grade neodymium 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 for manufacturing high performance laser glass and optical glass.

Rare earth elements are paid more attention from scientists and especially material experts of various countries due to unique performance and wide application, optical glass doped with rare earth ions is easy to prepare, has good optical properties, larger emission section and high quantum efficiency, is particularly used for improving the performance of optical functional glass and developing new optical functions of the glass, and rare earth becomes an indispensable important raw material. Various functional glasses doped with rare earth ions are being fully paid attention and applied in the fields of optical communication, laser protection, nonlinear optics and the like. Compared with the addition of rare earth oxide (such as neodymium oxide), the addition of rare earth metaphosphate (such as neodymium metaphosphate) into the laser glass raw material is more favorable for reducing the crystallization tendency of glass and improving the chemical stability and mechanical strength of the glass.

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 neodymium metaphosphate, so that the prepared neodymium metaphosphate meets the requirements 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 neodymium metaphosphate, which comprises the following steps:

(1) preparing an ammonium dihydrogen phosphate aqueous solution, and removing water insoluble substances;

(2) the ammonium dihydrogen phosphate aqueous solution passes through an ion exchange device to remove nonferrous metals and impurity ions;

(3) evaporating and concentrating to obtain concentrated solution, wherein the mass fraction of ammonium dihydrogen phosphate in the concentrated solution is more than 35%;

(4) cooling and crystallizing the concentrated solution, performing centrifugal separation, drying the separated solid substance to form optical-grade ammonium dihydrogen phosphate, and combining the separated liquid with the solution subjected to ion exchange in the step (2);

(5) optical-grade ammonium dihydrogen phosphate and neodymium oxide are uniformly mixed and subjected to polymerization reaction to obtain a neodymium metaphosphate intermediate;

(6) after clean pre-crushing the neodymium metaphosphate intermediate, calcining to obtain neodymium metaphosphate powder;

(7) and (3) cleanly crushing and cleanly mixing the neodymium metaphosphate powder to obtain the finished product of the optical grade neodymium metaphosphate powder.

It should be noted that the invention is applicable to all kinds of medical instrumentsThe neodymium oxide used may be a special grade neodymium oxide, which is Fe₂O₃Cu, Co, Cr, Mn, Ni and Pb 7 key impurity indexes, the total content is not more than 5ppm, wherein the total content of Co, Cr, Mn, Ni and Pb is not more than 2ppm, the content of Cu is not more than 0.2ppm, and Fe₂O₃Content of not more than 3ppm, Cl^-The total content of sulfate radicals is not more than 100ppm, Nd₂O₃Content (wt.)>99.5％。

Preferably, in the step (1), the solute mass fraction of the ammonium dihydrogen phosphate aqueous solution is 7-17%. More preferably, the concentration is 8 to 14%. And a precise cloth bag filter pressing mode is adopted when water insoluble substances are removed.

Preferably, in step (2), the ion exchange device is filled with cation exchange resin and anion exchange resin, the cation exchange resin comprises one or a combination of several of 001 × 4, 741, D001, iorreisin IR120 and iorreisin 35, and the anion exchange resin comprises one or a combination of several of D202, 201 × 4, 201 × 7, D406 and D407.

Preferably, the flow rate of the ammonium dihydrogen phosphate aqueous solution through the ion exchange unit is from 1L/min to 5L/min, and more preferably from 2L/min to 4L/min.

Preferably, in the step (3), the mass fraction of ammonium dihydrogen phosphate in the concentrated solution is 35% to 43%, and more preferably 36% to 40%.

Preferably, in the step (4), the cooling crystallization temperature is 20-30 ℃, and the crystallization time is 1-4 h. Further, the cooling crystallization temperature is 22-27 ℃, the crystallization time is 1-2.5 h, and circulating water cooling of a reaction kettle jacket or coil pipe is adopted.

Preferably, in the step (4), the separated solid matter is dried by a high-efficiency boiling dryer, wherein the air inlet temperature of the high-efficiency boiling dryer is 130-160 ℃, the tower body temperature is 115-145 ℃, the air outlet temperature is 90-110 ℃, the single feeding amount is 100-300 kg, and the drying time is 1.5-4 h. Furthermore, the air inlet temperature is 138-153 ℃, the tower body temperature is 122-138 ℃, the air outlet temperature is 95-105 ℃, the single feeding amount is 150-250 kg, and the drying time is 2-3 h. In order to ensure the product quality, the material contact part of the high-efficiency boiling dryer adopts a pure aluminum or pure titanium lining and the surface is highly polished, and the air inlet needs to be subjected to multi-stage purification treatment.

Preferably, in step (5), the molar ratio of neodymium oxide to optical grade ammonium dihydrogen phosphate is 1: (5.9-6.1) and the mixing time is 1-4 h. Furthermore, the mixing molar ratio of the neodymium oxide to the optical ammonium dihydrogen phosphate is 1 (5.95-2.05), and the mixing time is 1.5-3 h. In order to mix the two materials fully and uniformly, a two-dimensional or three-dimensional mixing mode is adopted, and the contact part of the materials is subjected to plastic spraying treatment.

Preferably, in the step (5), the temperature at which the polymerization reaction occurs is 470 ℃ to 560 ℃ and the reaction time is 5 hours to 10 hours. Furthermore, the temperature is 490-540 ℃, and the calcining time is 6-8 h. An electric furnace calcining mode can be adopted to provide heat for the polymerization reaction, in order to ensure clean and pollution-free calcining, the material contact part in the calcining process adopts high-temperature-resistant carbon fibers, and the hearth is made of Monel alloy or Hastelloy materials.

In the process of preparing neodymium metaphosphate through solid-solid calcination reaction, if a one-stage method-high temperature calcination is directly adopted, the phenomena that materials are sintered and seriously adhered to a hearth can occur, so that the materials are difficult to peel and take out after the calcination reaction is finished. In order to solve the engineering problem, a medium temperature region (470 ℃ -560 ℃) is firstly adopted to calcine and deaminate most of structural water and generate polymerization to generate a neodymium metaphosphate intermediate, and high temperature resistant carbon fiber is used as a material contact medium to facilitate the taking out of a calcined material. However, the problem that it is difficult to completely dehydrate neodymium metaphosphate in this temperature range, at most 96% of the structure water can be removed, and higher permanent temperature and further calcining equipment are needed to remove the final small amount of structure water.

Preferably, in the step (6), the calcining temperature is 760-850 ℃, the calcining time is 3-8 h, more preferably, the calcining temperature of the high-temperature electric furnace is 780-830 ℃, and the calcining time is 4-6 h. The calcining mode of the electric furnace can be adopted, and in order to ensure clean and pollution-free calcining, the high-temperature hearth is made of high-purity corundum or high-purity quartz.

Preferably, in the step (7), a ceramic pulverizer is adopted in the clean crushing process of the neodymium metaphosphate crushed powder, a two-dimensional or three-dimensional mixing mode is adopted in the clean mixing process, and the mixing time is 1 h-4 h, more preferably 1.5 h-3 h. The material contact part adopts plastic spraying treatment.

The preparation method of the optical grade neodymium metaphosphate provided by the technical scheme of the invention has the following beneficial effects: the industrial ammonium dihydrogen phosphate is purified by adopting an ion exchange method, and optical grade neodymium metaphosphate can be prepared by combining the neodymium oxide and the optical grade ammonium dihydrogen phosphate solid-solid medium-high temperature two-stage clean calcination reaction, so that the optical grade neodymium metaphosphate has strong adaptability to raw materials (the special grade neodymium oxide is a highly mature raw material in the market), and the main technical indexes of the optical grade neodymium metaphosphate can meet the requirements of the optical grade 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 neodymium 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 neodymium metaphosphate in accordance with the present invention comprises the following steps:

(1) preparing ammonium dihydrogen phosphate aqueous solution, and removing water insoluble substances (namely, filter pressing);

(2) the ammonium dihydrogen phosphate aqueous solution passes through an ion exchange device (i.e. a cation exchange resin and an anion exchange resin in figure 1) to remove nonferrous metals and impurity ions;

(3) evaporating and concentrating (concentrating) to obtain a concentrated solution, wherein the mass fraction of ammonium dihydrogen phosphate in the concentrated solution is more than 35%;

(4) cooling and crystallizing the concentrated solution, performing centrifugal separation, drying (boiling and drying) the separated solid substance to form optical-grade ammonium dihydrogen phosphate, and combining the separated liquid with the solution subjected to ion exchange in the step (2);

(5) optical-grade ammonium dihydrogen phosphate and neodymium oxide are uniformly mixed and subjected to polymerization reaction (namely, intermediate-temperature clean electric furnace calcination) to obtain a neodymium metaphosphate intermediate;

(6) after clean pre-crushing the neodymium metaphosphate intermediate, calcining (namely calcining in a high-temperature clean electric furnace) to obtain neodymium metaphosphate powder;

(7) and (3) cleanly crushing and cleanly mixing the neodymium metaphosphate powder to obtain the finished product of the optical grade neodymium metaphosphate powder.