Method for preparing phosphorus pentoxide from phosphorite
By calcining phosphate rock at low temperature and combining it with the reaction of sulfuric acid and water, the problems of high cost and insufficient utilization of by-products in the preparation of phosphorus pentoxide in the existing technology have been solved, realizing the efficient production of phosphorus pentoxide from low-grade phosphate rock and improving product purity and recovery rate.
Patent Information
- Application Number
- CN202511436482.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-09
- Publication Date
- 2025-12-19
AI Technical Summary
Existing methods for preparing phosphorus pentoxide are costly and do not fully utilize byproducts. Furthermore, existing phosphate rock requires high grades, making it difficult to meet the production needs of low-grade phosphate rock.
Solid-phase powder was prepared by low-temperature calcination of phosphate rock, which was then reacted with sulfuric acid and water and filtered to obtain a liquid-phase system. Finally, a dehydration condensation reaction was carried out to obtain phosphorus pentoxide.
This method enables efficient preparation of phosphorus pentoxide under low-temperature conditions, is applicable to low-grade phosphate rock, reduces process requirements and costs, and improves product purity and recovery rate.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of mineral utilization technology, and in particular to a method for preparing phosphorus pentoxide from phosphate rock. Background Technology
[0002] Phosphorus pentoxide, an essential industrial raw material, has been continuously improved for efficient and low-requirement preparation. Currently, the common method is the oxidative combustion method, which involves mixing raw materials, silica, and carbon, burning the mixture, and then oxidizing it in the presence of oxygen to generate high-temperature phosphorus pentoxide vapor. While this method has a simple process flow, it requires the addition of raw materials and high-temperature processing, resulting in high costs and the generation of numerous byproducts that cannot be effectively utilized. If wet-process phosphoric acid production is used, the grade of the raw ore must be very high, which existing phosphate rock cannot meet. Therefore, providing a phosphorus pentoxide preparation method with lower requirements for ore and process has become an urgent problem to be solved. Summary of the Invention
[0003] The purpose of this invention is to overcome the defects in the prior art and provide a method for preparing phosphorus pentoxide from phosphate rock.
[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing phosphorus pentoxide from phosphate rock, comprising the following steps: (1) Calcination of phosphate rock yields solid powder; (2) After reacting the solid powder, sulfuric acid and water, the liquid phase system is obtained by filtration; (3) The liquid phase system is subjected to dehydration condensation reaction to obtain the phosphorus pentoxide.
[0005] Preferably, the calcination temperature in step (1) is 300~500℃.
[0006] Preferably, the calcination time in step (1) is 10-14 hours.
[0007] Preferably, the concentration of sulfuric acid in step (2) is 70-75%.
[0008] Preferably, the mass ratio of solid powder to sulfuric acid in step (2) is 1:3~4.
[0009] Preferably, the mass ratio of the solid powder to water in step (2) is 1:1.5~2.
[0010] Preferably, the reaction temperature in step (2) is 75~85℃ and the time is 2~4h.
[0011] Preferably, the reaction speed in step (2) is 1500~2000 rpm.
[0012] Preferably, the dehydration temperature of the dehydration condensation reaction in step (3) is 75~85℃, the absolute dehydration pressure is 1~20kPa, and the phosphoric acid concentration is 30~35%.
[0013] Preferably, the condensation temperature of the dehydration condensation reaction in step (3) is 300~330℃.
[0014] This invention provides a method for preparing phosphorus pentoxide from phosphate rock, comprising the following steps: (1) calcining phosphate rock to obtain a solid powder; (2) reacting the solid powder, sulfuric acid, and water, and then filtering to obtain a liquid system; (3) subjecting the liquid system to a dehydration condensation reaction to obtain the phosphorus pentoxide. This invention uses low-temperature calcination to pre-treat phosphate rock to obtain a solid powder, in which the phosphate rock is converted into calcium phosphate and calcium fluoride. In subsequent reactions, this product reacts with sulfuric acid and water to produce gypsum, phosphoric acid, calcium sulfate, and hydrogen fluoride gas. The product is then filtered and concentrated to obtain phosphorus pentoxide. The solution provided by this invention is applicable to low-grade phosphate rock and has low process requirements. It can effectively obtain intermediate products without the need for high-temperature calcination, thus enabling the production of phosphorus pentoxide, and has practical application value. Detailed Implementation
[0015] This invention provides a method for preparing phosphorus pentoxide from phosphate rock, comprising the following steps: (1) Calcination of phosphate rock yields solid powder; (2) After reacting the solid powder, sulfuric acid and water, the liquid phase system is obtained by filtration; (3) The liquid phase system is subjected to dehydration condensation reaction to obtain the phosphorus pentoxide.
[0016] In this invention, the calcination temperature in step (1) is preferably 300~500℃, more preferably 350~450℃, and even more preferably 380~420℃.
[0017] In this invention, the calcination time in step (1) is preferably 10-14h, more preferably 11-13h, and even more preferably 11.5-12h.
[0018] In this invention, the concentration of sulfuric acid in step (2) is preferably 70-75%, more preferably 71-74%, and even more preferably 72-73%.
[0019] In this invention, the mass ratio of solid powder to sulfuric acid in step (2) is preferably 1:3~4, more preferably 1:3.2~3.8, and even more preferably 1:3.4~3.6.
[0020] In this invention, the mass ratio of solid powder to water in step (2) is preferably 1:1.5~2, more preferably 1:1.6~1.9, and even more preferably 1:1.7~1.8.
[0021] In this invention, the temperature of the reaction in step (2) is preferably 75~85℃, more preferably 76~84℃, and even more preferably 78~82℃; the time is preferably 2~4h, more preferably 2.5~3.5h, and even more preferably 2.8~3.2h.
[0022] In this invention, the reaction speed in step (2) is preferably 1500~2000 rpm, more preferably 1600~1900 rpm, and even more preferably 1700~1800 rpm.
[0023] In this invention, the dehydration temperature of the dehydration condensation reaction in step (3) is preferably 75~85℃, more preferably 76~84℃, and even more preferably 78~82℃; the absolute dehydration pressure is preferably 1~20kPa, more preferably 5~15kPa, and even more preferably 8~12kPa; and the phosphoric acid concentration is preferably 30~35%, more preferably 31~34%, and even more preferably 32~33%.
[0024] In this invention, the condensation temperature of the dehydration condensation reaction in step (3) is preferably 300~330℃, more preferably 305~325℃, and even more preferably 310~320℃.
[0025] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0026] Example 1
[0027] Phosphate ore was crushed and calcined at 400℃ for 12 hours, and the solid powder was collected. The solid powder, sulfuric acid (72% concentration), and water were mixed, with a mass ratio of solid powder, sulfuric acid, and water of 1:3.5:2. The mixture was reacted at 80℃ and 1800 rpm for 3 hours, and filtered to obtain a liquid system. The liquid system was dehydrated at 80℃ and 10 kPa to obtain a 33% phosphoric acid solution. Then, condensation was carried out under a nitrogen atmosphere at 320℃ to collect a white solid, which is phosphorus pentoxide.
[0028] Example 2
[0029] Phosphate ore was crushed and calcined at 330℃ for 13 hours, and the solid powder was collected. The solid powder, sulfuric acid (75% concentration), and water were mixed, with a mass ratio of solid powder, sulfuric acid, and water of 1:3:2. The mixture was reacted at 80℃ and 1500 rpm for 2.5 hours, and filtered to obtain a liquid system. The liquid system was dehydrated at 75℃ and 5 kPa to obtain a 35% phosphoric acid solution. Then, condensation was carried out under a nitrogen atmosphere at 300℃ to collect a white solid, which is phosphorus pentoxide.
[0030] Example 3
[0031] Phosphate ore was crushed and calcined at 470℃ for 10 hours, and the solid powder was collected. The solid powder, sulfuric acid (71% concentration), and water were mixed, with a mass ratio of solid powder, sulfuric acid, and water of 1:4:1.5. The mixture was reacted at 78℃ and 2000 rpm for 3.5 hours, and filtered to obtain a liquid system. The liquid system was dehydrated at 83℃ and 17 kPa to obtain a 31% phosphoric acid solution. Then, condensation was carried out under a nitrogen atmosphere at 310℃ to collect a white solid, which is phosphorus pentoxide.
[0032] Example 4
[0033] Phosphate ore was crushed and calcined at 440℃ for 13 hours, and the solid powder was collected. The solid powder, sulfuric acid (75% concentration), and water were mixed, with a mass ratio of solid powder, sulfuric acid, and water of 1:3.8:1.7. The mixture was reacted at 76℃ and 1900 rpm for 4 hours, and filtered to obtain a liquid system. The liquid system was dehydrated at 76℃ and 4 kPa to obtain a 35% phosphoric acid solution. Then, condensation was carried out under a nitrogen atmosphere at 325℃ to collect a white solid, which is phosphorus pentoxide.
[0034] Example 5
[0035] Phosphate ore was crushed and calcined at 410℃ for 11.5 h, and the solid powder was collected. The solid powder, sulfuric acid (74% concentration), and water were mixed, with a mass ratio of solid powder, sulfuric acid, and water of 1:3:2. The mixture was reacted at 80℃ and 1900 rpm for 2.5 h, and filtered to obtain a liquid system. The liquid system was dehydrated at 74℃ and 6 kPa to obtain a 33% phosphoric acid solution. Then, condensation was carried out under a nitrogen atmosphere at 330℃ to collect a white solid, which is phosphorus pentoxide.
[0036] Example 6
[0037] Phosphate ore was crushed and calcined at 370℃ for 14 hours, and the solid powder was collected. The solid powder, sulfuric acid (70% concentration), and water were mixed, with a mass ratio of solid powder, sulfuric acid, and water of 1:4:2. The mixture was reacted at 82℃ and 1700 rpm for 4 hours, and filtered to obtain a liquid system. The liquid system was dehydrated at 75℃ and 17 kPa to obtain a 35% phosphoric acid solution. Then, condensation was carried out under a nitrogen atmosphere at 310℃ to collect a white solid, which is phosphorus pentoxide.
[0038] The recovery rate of phosphorus and the purity of phosphorus pentoxide prepared in Examples 1-6 are shown in Table 1.
[0039] Table 1. Statistics on recovery rate and purity
[0040] It can be seen that the method provided in this application can effectively recover phosphorus from phosphate rock under low-temperature calcination, and the purity of the prepared phosphorus pentoxide reaches 99.3%, achieving high-quality preparation of phosphorus pentoxide.
[0041] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing phosphorus pentoxide from phosphate rock, characterized in that, Includes the following steps: (1) Calcination of phosphate rock yields solid powder; (2) After reacting the solid powder, sulfuric acid and water, the liquid phase system is obtained by filtration; (3) The liquid phase system is subjected to dehydration condensation reaction to obtain the phosphorus pentoxide.
2. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 1, characterized in that, The calcination temperature in step (1) is 300~500℃.
3. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 2, characterized in that, The calcination time in step (1) is 10~14h.
4. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 3, characterized in that, The concentration of sulfuric acid in step (2) is 70-75%.
5. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 4, characterized in that, In step (2), the mass ratio of solid powder to sulfuric acid is 1:3~4.
6. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 5, characterized in that, The mass ratio of the solid powder to water in step (2) is 1:1.5~2.
7. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 6, characterized in that, The reaction in step (2) is carried out at a temperature of 75~85℃ for 2~4 hours.
8. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 7, characterized in that, The reaction speed in step (2) is 1500~2000 rpm.
9. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 8, characterized in that, The dehydration temperature of the dehydration condensation reaction in step (3) is 75~85℃, the absolute dehydration pressure is 1~20kPa, and the phosphoric acid concentration is 30~35%.
10. The method for preparing phosphorus pentoxide from phosphate rock as described in claim 9, characterized in that, The condensation temperature of the dehydration condensation reaction in step (3) is 300~330℃.