CN115893340A - Method for preparing phosphorus pentafluoride by utilizing solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide - Google Patents
Method for preparing phosphorus pentafluoride by utilizing solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide Download PDFInfo
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Abstract
The invention discloses a method for preparing phosphorus pentafluoride by utilizing a solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide, which is implemented by drying CaF 2 And putting the sludge into a closed reactor filled with ceramic balls, and heating while performing ball milling or adding an organic solvent for performing ball milling. Heating at a temperature to remove CaF 2 The temperature of organic matters in the sludge is higher than that of CaF in the temperature for removing the organic matters 2 And P 2 O 5 The temperature at which the solid phase reaction occurs; then adjusting the temperature to room temperature or lower than the solid-phase reaction temperature, and adding P into the reactor under the dry condition 2 O 5 Continuing to perform ball milling; then raising the temperature to a preset solid phase reaction temperature, and carrying out solid phase reaction of ball grinding and oscillation on the ball grinding mixture under the vacuum drying condition; caF 2 Sludge and P 2 O 5 Mixing and generating solid phase reaction to generate PF 5 Gas, obtained PF 5 The reaction product is led out from the closed reactor, compressed, condensed and rectified to obtain PF 5 And (5) producing the product. The invention adoptsThe phosphorus pentafluoride is prepared from the solid waste, so that the preparation cost is reduced, and a brand-new way is provided for the production of lithium batteries.
Description
Technical Field
The invention discloses a method for recycling calcium fluoride sludge resources, belonging to the technical fields of inorganic, chemical and environmental technologies.
Background
Phosphorus pentafluoride is an important inorganic fluoride and is widely applied to the industrial field. It can effectively improve semiconductor performance, is a raw material for synthesizing organic macromolecules such as phthalate ester, and can be used as a catalyst to improve the selectivity of metal.
With the development of the era, the demand of lithium batteries is continuously increasing. The phosphorus pentafluoride is used as a raw material to prepare the excellent lithium hexafluorophosphate electrolyte, so that the performance of the lithium battery can be remarkably improved. However, at present, the research on the preparation of phosphorus pentafluoride in China is very little, and the research on the phosphorus pentafluoride in foreign countries begins in the 50 th of the 20 th century.
At present, the research on the preparation of phosphorus pentafluoride at home and abroad can be roughly divided into an indirect method and a direct method. The indirect method means that reactants firstly generate an intermediate product, and then the intermediate product is processed to obtain the phosphorus pentafluoride. The intermediate products are mainly phosphorus trioxide and hexafluorophosphoric acid. The direct method means that the phosphorus pentafluoride can be generated by one step of reactants.
The indirect method for preparing the phosphorus pentafluoride has complex steps and is easy to generate more impurities.
The direct method has the problems of violent reaction of reactants, difficult control of the reaction process, high cost of raw materials and difficult application to industrial production due to the safety and economic benefit of the preparation process.
Patent document publication No. CN101417791 discloses a method for preparing a phosphorus pentafluoride crude product by reacting elemental phosphorus and fluorine gas, and condensing, distilling and separating the crude product to obtain a high-purity phosphorus pentafluoride product. However, the reaction of fluorine gas and elemental phosphorus is very violent, a large amount of heat is released, and the reaction process is not easy to control.
Patent document publication No. CN101353161A discloses a method, which adopts phosphorus pentachloride solution obtained by mixing under low temperature condition, and introduces anhydrous hydrogen fluoride gas under the protection of inert gas to contact and react with the phosphorus pentachloride solution to obtain phosphorus pentafluoride. The method also has the advantages of violent reaction, large amount of impurities in the synthesized product and low purity. And phosphorus pentachloride is solid at room temperature and difficult to handle. Phosphorus trichloride is a liquid at room temperature and is easier to handle than phosphorus pentafluoride.
Patent document publication No. CN110072807a discloses a method of producing a phosphorus pentafluoride gas by reacting phosphorus trichloride, chlorine and an excess amount of anhydrous hydrogen fluoride, in which the heat of reaction resulting from the generation of phosphorus pentafluoride can be removed by utilizing the latent heat of vaporization of hydrogen fluoride. Although this method is low in material cost and safe, the reaction apparatus is complicated.
In conclusion, most of the existing phosphorus pentafluoride preparation methods have the characteristics of high cost, complex steps, low safety and the like. Therefore, the search for a safe and feasible preparation method of phosphorus pentafluoride with a simple preparation method is an urgent problem to be solved in the field.
Patent document publication No. CN103253641A discloses a method for preparing high-purity phosphorus pentafluoride gas by a solid phase method. Mixing phosphorus pentoxide and calcium fluoride solid phase, and heating to generate phosphorus pentafluoride gas under the condition of excessive phosphorus pentoxide. The method does not relate to solution, can eliminate moisture interference in the whole reaction process, is beneficial to the production process and the final product, has simple reaction process, and is easy to realize industrialized popularization.
Calcium fluoride is the main component of fluorite ore, which is a non-renewable resource. In addition to fluorite, calcium fluoride is also produced from fluorine-containing waste gas, wastewater, fluorine-containing sludge and the like produced in the fluorine chemical industry, such as the metallurgical industry, the fluorine organic chemical industry, the photovoltaic industry, display screen enterprises, the integrated circuit industry and the like. As shown in table 1 below, calcium fluoride sludge was produced for different industry enterprises.
TABLE 1 main component and content (wt%) of dry basis of four enterprises fluorine-containing sludge
Note: l.o.i. in table 1 is the loss on ignition, i.e. the loss on removal of organic matter including the organic flocculant PAM.
[Al 2 (OH) n Cl 6-n ] m Is polyaluminium chloride flocculant.
The Integrated Circuit (IC) industry has rapidly developed in China in recent years to produceCalcium fluoride sludge produced by IC industry mainly based on chip manufacture is a new fluorine pollution source in the last decade of China. In the process of treating monocrystalline silicon wafer products in the IC industry, a large amount of hydrofluoric acid is used for etching silicon wafers, fluorine-containing wastewater is discharged, and a large amount of calcium fluoride sludge is generated after treatment. The chemical/coagulating sedimentation treatment process is the mainstream treatment process of the fluorine-containing wastewater at present. The process comprises adjusting pH of wastewater, and adding CaCl into a sedimentation tank 2 Or CaF formation from CaO 2 Precipitating, adding Polyacrylamide (PAM) or polyaluminium chloride (PAC) for flocculation to obtain CaF as main component of sludge 2 And SiO 2 And is therefore commonly referred to as calcium fluoride sludge.
At present, the main disposal mode of calcium fluoride sludge is a landfill method. The method is simple and convenient, but occupies land and causes resource waste. And if the treatment is not proper, the fluorine ions contained in the water pollute the surrounding soil, further pollute underground water and drinking water for human and influence the health of human beings. Although calcium fluoride has very little solubility in water, at 18 ℃,100 g of water dissolves only 0.0016g, i.e. 16mg/L, in terms of fluoride ion, which is 7.9mg/L, this value far exceeds the limit of 1.0mg/L of fluoride in drinking water specified in sanitary Standard for Drinking Water (GB 5749-2006). Therefore, how to utilize calcium fluoride sludge as resources is the focus of attention at present.
At present, the resource utilization of calcium fluoride sludge mainly comprises purification technologies of calcium fluoride, such as a flotation enrichment method, a normal pressure distillation method, an acid cleaning purification method and a fluorine-containing wastewater purification method. The calcium fluoride sludge is taken as a fluorite substitute for industrial resource recycling, such as fine aggregate making in the concrete industry, brick making in the building industry, adsorption material making and the like.
The technologies for recycling the calcium fluoride sludge have the defects of low added value, high cost and difficult industrial popularization. How to recycle calcium fluoride sludge efficiently is a problem which needs to be solved urgently at present.
Disclosure of Invention
In order to solve the problems of the prior art, the invention aims to overcome the defects in the prior art, and provides a method for preparing phosphorus pentafluoride by utilizing the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide, so that the preparation cost of the phosphorus pentafluoride is reduced, and the high-efficiency reutilization of the calcium fluoride sludge is realized; the phosphorus pentafluoride is prepared from the solid waste, so that the preparation cost is reduced, and a brand-new way is provided for the production of lithium batteries.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
a method for preparing phosphorus pentafluoride by utilizing solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide comprises the following steps:
(1) Mixing CaF 2 Drying and pretreating sludge to remove water, and then drying the CaF 2 Putting the sludge into a closed reactor filled with ceramic balls, and carrying out ball milling while heating or adding an organic solvent for ball milling to obtain purified CaF 2 Sludge; the heating temperature is CaF removal 2 The temperature of the organic matters in the sludge is higher than that of CaF 2 And P 2 O 5 The temperature at which the solid phase reaction occurs;
(2) Purifying CaF 2 The temperature of the sludge is adjusted to room temperature, and P is added into the reactor under the drying condition 2 O 5 Continuing to perform ball milling to obtain CaF 2 Sludge and P 2 O 5 Ball milling the mixture;
or purified CaF 2 The temperature of the sludge is adjusted to be lower than CaF 2 Sludge and P 2 O 5 At a temperature at which the solid phase reaction takes place, a predetermined amount of P is added to the reactor under dry conditions 2 O 5 Continuing to perform ball milling to obtain CaF 2 Sludge and P 2 O 5 The mixture was ball milled.
Or purified CaF 2 The temperature of the sludge is adjusted to CaF 2 Sludge and P 2 O 5 At a temperature at which the solid phase reaction takes place, a predetermined amount of P is added to the reactor under dry conditions 2 O 5 Continuing to perform ball milling to obtain CaF 2 Sludge and P 2 O 5 The mixture was ball milled.
(3) Will warm upIncreasing the temperature to a predetermined solid phase reaction temperature of not less than 200 ℃, and subjecting the CaF to vacuum drying 2 Sludge and P 2 O 5 Performing solid phase reaction of ball grinding and oscillation on the ball-milled mixture;
CaF 2 sludge and P 2 O 5 Mixing and generating solid phase reaction to generate PF 5 Gas, obtained PF 5 The reaction product is led out from the closed reactor, compressed, condensed and rectified to obtain PF 5 And (5) producing the product.
Preferably, in the step (1), the ball milling is performed at any one of a high speed, a low speed and an alternation of high speed and low speed.
Preferably, in the step (1), the calcium fluoride sludge comprises calcium fluoride sludge produced in the microelectronics industry, the photovoltaics industry and the fluorine chemical industry or fluorine-containing wastewater produced by subjecting CaO, caCl and the like to treatment 2 Or Ca (OH) 2 ) Precipitating the resulting calcium fluoride sludge.
Preferably, in the step (1), the heating temperature is 400-800 ℃, the reaction time is 10-240min, and CaF is removed 2 Organic matters in the sludge.
Preferably, in the step (1), the organic solvent is at least one of dimethylformamide, dimethyl sulfoxide, dimethylacetamide, tetrahydrofuran and dichloromethane; preferably, the solid-liquid ratio of the calcium fluoride sludge to the organic solvent calculated according to the mass ratio is 1:5 to 1:20.
preferably, in the step (2), a predetermined amount of P 2 O 5 According to the dried CaF 2 Sludge and P 2 O 5 Adding CaF in a mass ratio 2 Sludge and P 2 O 5 The mass ratio is between 0.5 and 1 to 5:1; p 2 O 5 And CaF 2 The ball milling and mixing time of the sludge is 10 min-5 h.
Preferably, in the steps (1) to (3), the rotation speed of the ball mill is 100 to 2000rpm. The oscillation frequency is 50-200rpm.
Preferably, in the step (3), P 2 O 5 And CaF 2 The solid phase reaction time of the sludge is 1 to 8 hours, and the preset reaction temperature is 200 to 400℃。
Preferably, in the step (3), the oscillation is performed in any one of a high frequency, a low frequency, and an alternating manner of the high frequency and the low frequency.
Preferably, in the step (3), the gas pressure in the reactor before the reaction is pumped to 0-0.5 MPa, and the gas pressure is controlled in the range of 0.1-1.5 MPa during the reaction.
Preferably, in the step (3), when the condensation is performed, the condensed cooling medium is industrial alcohol, and the industrial alcohol is frozen by liquid nitrogen.
Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:
1. the method comprises the steps of carrying out solid-phase reaction on calcium fluoride sludge and phosphorus pentoxide to prepare phosphorus pentafluoride gas; the invention adopts cheap calcium fluoride sludge solid waste to prepare the phosphorus pentafluoride product with high added value, thereby realizing the unification of environmental and economic benefits;
2. the invention solves the problem of high-efficiency utilization of calcium fluoride sludge, and avoids the environmental pollution of the calcium fluoride sludge; the phosphorus pentafluoride is prepared by adopting solid wastes, so that the preparation cost is reduced, and a brand-new way is provided for the production of lithium batteries.
Detailed Description
The above-described scheme is further illustrated below with reference to specific embodiments, which are detailed below:
example 1
In this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform a solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be heated for 1 hour at 500 ℃ while ball milling. The ball milling frequency is: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed. The ball milling can ensure that the calcium fluoride sludge is heated uniformly, and organic matters in the sludge are better removed. The alternate ball milling at high and low rotation speeds can make the equipment have a buffer, so that the ball mill can better operate. The heating is to remove organic matters in the calcium fluoride sludge, so that the calcium fluoride can not be wrapped by the organic matters and can better generate solid-phase contact reaction with the phosphorus pentoxide.
After ball milling, the temperature of the reactor is reduced to room temperature, and phosphorus pentoxide is added into the reactor according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 for mixing and ball milling under the protection of dry nitrogen at room temperature. The ball milling time is 1h, and the conditions are as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed. The ball milling can increase the contact surface of the calcium fluoride sludge and the phosphorus pentoxide, so that the calcium fluoride sludge and the phosphorus pentoxide are mixed more fully.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, heating the reactor, carrying out temperature programming at the speed of 5 ℃/min, finally controlling the temperature to be 280-300 ℃ and the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of edge ball edging oscillation. The temperature programming makes the mixture heating more even, vibrates under the condition of ball-milling because the ball-milling probably makes the reaction material caking, vibrates and to make the material of caking disperse the mixture again to make the reaction more abundant.
The reaction time was 3h. The ball milling frequency is: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed. The oscillation frequency was 50rpm for 10 minutes and 100rpm for 20 minutes, and thus the high speed/low speed was alternately oscillated. The adoption is ball-milling in turn and is shaken to make the reaction material mix more evenly, and the reaction is more thorough, also plays a cushioning effect to equipment. The high-frequency ball milling/low-frequency oscillation and the low-frequency ball milling/high-frequency oscillation are matched to ensure that the solid-phase reaction state reaches the best and the buffering effect of the equipment is the best. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 2
This embodiment is substantially the same as embodiment 1, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform a solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, then the dried calcium fluoride sludge is put into a ball-milling closed reactor filled with ceramic balls, and the ball-milling and the heating are carried out simultaneously for 1 hour at the heating temperature of 500 ℃. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed.
After ball milling, the temperature of the reactor is reduced to room temperature, phosphorus pentoxide is added according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 under the protection of dry nitrogen, and the temperature is raised to 120 ℃ for mixing and ball milling. The materials are heated in the mixing process, so that on one hand, a dry mixing environment can be kept, and the phosphorus pentoxide is prevented from deliquescing; on the other hand, preheating before solid-phase reaction can promote more uniform mixing of materials, and some volatile impurities can be removed, so that the preheating function is realized in advance for the occurrence of the solid-phase reaction. The ball milling time is 1h, and the conditions are as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, further heating the reactor, carrying out temperature programming at the speed of 5 ℃/min, raising the temperature to 280-300 ℃, controlling the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of ball edge grinding oscillation.
The reaction time was 3h. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min, ball milling is carried out for 20 minutes at 300-500 r/min, and the ball milling is carried out at high speed/low speed alternately. The oscillation frequency was 100rpm. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 3
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform a solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, then the dried calcium fluoride sludge is put into a ball-milling closed reactor filled with ceramic balls, and the ball-milling and the heating are carried out simultaneously for 1 hour at the heating temperature of 500 ℃. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed.
After ball milling, the temperature of the reactor is reduced to room temperature, and phosphorus pentoxide is added into the reactor according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 under the protection of dry nitrogen. The reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, heating the reactor, carrying out temperature programming at the speed of 5 ℃/min, controlling the temperature to be 280-300 ℃, and controlling the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of edge ball edging oscillation. The two materials are directly heated to the solid phase reaction temperature after being mixed, so that the temperature control process is simplified, but the reaction time needs to be increased to ensure that the two materials are fully mixed, are uniformly heated and completely react.
The reaction time was 4h. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed. The oscillation frequency was 100rpm. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 4
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform a solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be ball milled and heated for 1 hour at the heating temperature of 500 ℃. The ball milling frequency is as follows: the rotating speed is 300-500 r/min.
After ball milling, the temperature of the reactor is reduced to room temperature, phosphorus pentoxide is added into the reactor according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 under the protection of dry nitrogen gas at room temperature, and then mixed and ball milled. The ball milling time is 2h, and the conditions are as follows: the rotating speed is 300-500 r/min. The low rotation speed of the ball mill may cause insufficient mixing of the two materials, and can be adjusted by increasing the ball milling time.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, heating the reactor, rapidly raising the temperature to 280-300 ℃, controlling the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of ball edge grinding oscillation. The rapid temperature rise can save the time for achieving the scheduled solid-phase reaction, but the possibility of nonuniform heating of the mixed materials exists, and the reaction effect is influenced.
The reaction time was 3h. The ball milling frequency is as follows: the rotating speed is 300-500 r/min. The oscillation frequency is: 50rpm20 min, 200rpm10 min. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 5
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be ball milled and heated for 1 hour at the heating temperature of 500 ℃. The ball milling frequency is as follows: the rotating speed is 1000-1500 rpm. The continuous high-speed operation of ball milling can increase the loss of equipment.
After ball milling, the temperature of the reactor is reduced to room temperature, and phosphorus pentoxide is added into the reactor according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 for mixing and ball milling under the protection of dry nitrogen at room temperature. The ball milling time is 1h, and the conditions are as follows: the rotating speed is 1000-1500 rpm.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, heating the reactor, rapidly heating to the solid phase reaction temperature of 280-300 ℃, controlling the gas pressure below 0.15MPa, and carrying out the solid phase reaction of ball edging oscillation.
The reaction time was 3h. The ball milling frequency is as follows: the rotating speed is 1000-1500 rpm. The oscillation frequency was 100rpm. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 6
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform a solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be ball milled and heated for 1 hour at the heating temperature of 500 ℃. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min, ball milling is carried out for 20 minutes at 300-500 r/min, and the ball milling is carried out at high speed/low speed alternately.
After ball milling, the temperature of the reactor is reduced to room temperature, and phosphorus pentoxide is added into the reactor according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 for mixing and ball milling under the protection of dry nitrogen at room temperature. The ball milling time is 1h, and the conditions are as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, heating the reactor, controlling the temperature to be 280-300 ℃ and the gas pressure to be below 0.15MPa, and carrying out ball-milling solid-phase reaction. The reaction is not vibrated, and the simple ball milling can cause the materials to be agglomerated and influence the full reaction.
The reaction time was 3h. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min, ball milling is carried out for 20 minutes at 300-500 r/min, and the ball milling is carried out at high speed/low speed alternately. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 7
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform a solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be ball milled and heated for 1 hour at the heating temperature of 500 ℃. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed.
After ball milling, the temperature of the reactor is reduced to room temperature, and phosphorus pentoxide is added into the reactor according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 under the protection of dry nitrogen gas at room temperature. The reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And heating the reactor after the leakage detection is qualified, controlling the temperature to be 220-280 ℃ and the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of ball edge grinding oscillation. The solid-phase reaction temperature directly influences the reaction, the reaction is incomplete due to low-temperature control, and only part of mixed materials react to generate a small amount of phosphorus pentafluoride.
The reaction time was 3h. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed. The oscillation frequency was 100rpm. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 8
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform a solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be ball milled and heated for 1 hour at 650 ℃. On the premise of not destroying the crystal form state of calcium fluoride sludge components, the high heating temperature can better remove the organic matters in the sludge. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min and for 20 minutes at 300-500 r/min, and the ball milling is carried out alternately at high speed and low speed.
After ball milling, the temperature of the reactor is reduced to room temperature, phosphorus pentoxide is added into the reactor according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 2:1 under the protection of dry nitrogen, and the temperature is controlled to be 90 ℃ for mixing and ball milling. The ball milling time is 1h, and the rotating speed is 1500-2000 r/min.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, further heating the reactor, raising the temperature to 280-400 ℃, controlling the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of ball edge grinding oscillation. If the temperature is controlled too high, many side reactions occur and the yield of phosphorus pentafluoride is greatly reduced.
The reaction time was 2h. The ball milling frequency is 1500-2000 r/min, and the oscillation frequency is 100rpm. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 9
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be ball milled and heated for 1 hour at 650 ℃. The ball milling frequency is as follows: ball milling is carried out for 10 minutes at 800-1000 r/min, ball milling is carried out for 20 minutes at 300-500 r/min, and the ball milling is carried out at high speed/low speed alternately.
After ball milling, the temperature of the reactor is reduced to room temperature, phosphorus pentoxide is added according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 1:1 under the protection of dry nitrogen at room temperature, and the temperature is controlled at 90 ℃ for mixing and ball milling. The ball milling time is 1h, and the rotating speed is 1500-2000 r/min. The addition of phosphorus pentoxide is insufficient, and the reaction is incomplete. Calcium fluoride in the sludge cannot be converted into the target phosphorus pentafluoride product due to the absence of phosphorus pentoxide.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, further heating the reactor, raising the temperature to 280-350 ℃, controlling the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of ball edge grinding oscillation.
The reaction time was 3h. The ball milling frequency is 1500-2000 r/min, and the oscillation frequency is 50rpm. The low oscillation frequency may not break up the agglomerated mixture, thereby affecting the reaction. And (3) leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain a phosphorus pentafluoride product.
Example 10
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls to be ball milled and heated for 1 hour at the heating temperature of 550 ℃. The ball milling frequency is: 800-1000 rpm.
After ball milling, the temperature of the reactor is reduced to room temperature, phosphorus pentoxide is added according to the mass ratio of the phosphorus pentoxide to the calcium fluoride sludge of 1:2 under the protection of dry nitrogen at room temperature, and the temperature is controlled at 90 ℃ for mixing and ball milling. The ball milling time is 1h, and the rotating speed is 1500-2000 r/min.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, further heating the reactor, raising the temperature to 280-350 ℃, controlling the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of ball edging oscillation.
The reaction time was 2h. The ball milling frequency is 1500-2000 r/min, and the oscillation frequency is 200rpm. And (3) leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain a phosphorus pentafluoride product.
Example 11
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform solid-phase reaction includes the following steps:
firstly, calcium fluoride sludge is put into a drying oven to be dried for 24 hours at 105 ℃, and then the dried calcium fluoride sludge is put into a ball milling reactor filled with ceramic balls according to the solid-liquid ratio of 1:5 adding dimethyl formamide (DMF) organic solvent (or dimethyl sulfoxide (DMSO), dimethyl acetamide, tetrahydrofuran, dichloromethane and the like) for ball milling for 1h, wherein the ball milling frequency is as follows: 800-1000 rpm. After ball milling, filtering, washing the solid product with water, and then drying. And an organic solvent is added, and according to the principle of similarity and intermiscibility, organic matters in the calcium fluoride sludge can be dissolved in the organic solvent, so that energy consumption and atmospheric pollution caused by high-temperature calcination are avoided.
Under the protection of dry nitrogen, phosphorus pentoxide is added according to the mass ratio of 2:1 of the phosphorus pentoxide to the solid product, and the temperature is controlled at 90 ℃ for mixing and ball milling. The ball milling time is 1h, and the rotating speed is 1500-2000 r/min.
After ball milling, the reactor was evacuated to a pressure of 0.1MPa and the evacuation valve was closed. And after the leakage detection is qualified, further heating the reactor, raising the temperature to 250-320 ℃, controlling the gas pressure to be below 0.15MPa, and carrying out solid phase reaction of ball edge grinding oscillation.
The reaction time was 3h. The ball milling frequency is 1500-2000 r/min, and the oscillation frequency is 100rpm. And leading out the obtained phosphorus pentafluoride reaction product from the closed reactor, compressing, condensing and rectifying to obtain the phosphorus pentafluoride product.
Example 12
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, in the method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide, indexes such as heating temperature, ball milling frequency mixed with phosphorus pentafluoride, reaction time, reaction temperature, reaction pressure, oscillation frequency of reaction and the like of the calcium fluoride sludge in the above embodiments can be adjusted and combined according to the index range of the technical scheme, and are not limited to the above embodiments.
In summary, the invention relates to a method for preparing phosphorus pentafluoride by using calcium fluoride sludge and phosphorus pentoxide to perform solid-phase reaction, and dry CaF 2 And putting the sludge into a closed reactor filled with ceramic balls, and heating while performing ball milling or adding an organic solvent for performing ball milling. The ball milling comprises high speed, low speed and high speed/low speed alternation; the heating temperature is CaF removal 2 The temperature of the organic matters in the sludge is higher than that of CaF 2 And P 2 O 5 The temperature at which the solid phase reaction occurs. Thereafter, the temperature is adjusted to room temperature or lower than the solid-phase reaction temperature, and a predetermined amount of P is added to the reactor under dry conditions 2 O 5 Continuing to perform ball milling; then, the temperature is raised to a predetermined solid phase reaction temperature, and the ball-milled mixture (CaF) is dried under vacuum 2 Sludge + P 2 O 5 ) Carrying out solid-phase reaction while applying oscillation, wherein the oscillation comprises high frequency, low frequency and alternation of the high frequency and the low frequency; caF 2 Sludge and P 2 O 5 Mixing and generating solid phase reaction to generate PF 5 Gas, obtained PF 5 The reaction product is led out from the closed reactor, compressed, condensed and rectified to obtain PF 5 And (5) producing the product. The method of the invention prepares the phosphorus pentafluoride gas by the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide. The method aims to prepare the phosphorus pentafluoride product with high added value by adopting the cheap calcium fluoride sludge solid waste, and realize the unification of environmental and economic benefits.
While the embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and various changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the present invention may be made in the form of equivalent substitutions without departing from the technical principle and inventive concept of the present invention.
Claims (9)
1. A method for preparing phosphorus pentafluoride by utilizing solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide is characterized by comprising the following preparation steps:
(1) Mixing CaF 2 Drying and pretreating sludge to remove water, and then drying the CaF 2 Putting the sludge into a closed reactor filled with ceramic balls, and carrying out ball milling while heating or adding an organic solvent for ball milling to obtain purified CaF 2 Sludge; the heating temperature is CaF removal 2 The temperature of organic matters in the sludge is higher than that of CaF (sludge derived Filter) 2 And P 2 O 5 The temperature at which the solid phase reaction occurs;
(2) Purifying CaF 2 The temperature of the sludge is adjusted to room temperature, and P is added into the reactor under the drying condition 2 O 5 Continuing to perform ball milling to obtain CaF 2 Sludge and P 2 O 5 Ball milling the mixture;
or purified CaF 2 The temperature of the sludge is adjusted to be lower than CaF 2 Sludge and P 2 O 5 At a temperature at which the solid phase reaction takes place, a predetermined amount of P is added to the reactor under dry conditions 2 O 5 Continuing to perform ball milling to obtain CaF 2 Sludge and P 2 O 5 The mixture was ball milled.
Or purified CaF 2 The temperature of the sludge is adjusted to CaF 2 Sludge and P 2 O 5 At a temperature at which the solid phase reaction takes place, a predetermined amount of P is added to the reactor under dry conditions 2 O 5 Continuing to perform ball milling to obtain CaF 2 Sludge and P 2 O 5 The mixture was ball milled.
(3) Raise the temperature toA predetermined solid phase reaction temperature of less than 200 ℃, under vacuum drying conditions to said CaF 2 Sludge and P 2 O 5 Performing solid phase reaction of ball grinding and oscillation on the ball-milled mixture;
CaF 2 sludge and P 2 O 5 Mixing and generating solid phase reaction to generate PF 5 Gas, obtained PF 5 The reaction product is led out from the closed reactor, compressed, condensed and rectified to obtain PF 5 And (5) producing the product.
2. The method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide according to claim 1, characterized in that: in the step (1), the ball milling is performed at any one of a high speed, a low speed and an alternate high/low speed.
3. The method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide according to claim 1, characterized in that: in the step (1), the calcium fluoride sludge comprises calcium fluoride sludge produced in the microelectronics industry, the photovoltaics industry and the fluorine chemical industry or fluorine-containing wastewater produced by the processes of CaO and CaCl 2 Or Ca (OH) 2 ) Precipitating the resulting calcium fluoride sludge.
4. The method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide according to claim 1, characterized in that: in the step (1), the heating temperature is 400-800 ℃, the reaction time is 10-240min, and CaF is removed 2 Organic matters in the sludge;
in the step (1), the organic solvent adopts at least one of dimethylformamide, dimethyl sulfoxide, dimethylacetamide, tetrahydrofuran and dichloromethane; the solid-liquid ratio of the calcium fluoride sludge to the organic solvent calculated according to the mass ratio is 1:5 to 1:20.
5. the method for preparing pentafluoro according to claim 1, wherein the calcium fluoride sludge is reacted with phosphorus pentoxide in solid phaseThe method for phosphorizing is characterized by comprising the following steps: in the step (2), a predetermined amount of P 2 O 5 According to the CaF after drying 2 Sludge and P 2 O 5 Adding CaF in a mass ratio 2 Sludge and P 2 O 5 The mass ratio is between 0.5 and 5:1; p is 2 O 5 And CaF 2 The ball milling and mixing time of the sludge is 10 min-5 h.
6. The method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide according to claim 1, characterized in that: in the steps (1) to (3), the ball milling rotation speed is 100 to 2000rpm. The oscillation frequency is 50-200rpm.
7. The method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide according to claim 1, which is characterized in that: in said step (3), P 2 O 5 And CaF 2 The solid phase reaction time of the sludge is 1 to 8 hours, and the preset reaction temperature is 200 to 400 ℃;
in the step (3), the oscillation may be performed in any one of a high frequency, a low frequency, and an alternating high frequency and low frequency.
8. The method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide according to claim 1, characterized in that: in the step (3), the gas pressure of the reactor is pumped to 0 to-0.5 MPa before the reaction, and the gas pressure is controlled to be within the range of 0.1 to 1.5MPa in the reaction process.
9. The method for preparing phosphorus pentafluoride by using the solid-phase reaction of calcium fluoride sludge and phosphorus pentoxide according to claim 1, characterized in that: in the step (3), when condensation is performed, the condensed cooling medium is industrial alcohol, and the industrial alcohol is frozen by liquid nitrogen.
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| CN117535685A (en) * | 2024-01-09 | 2024-02-09 | 常熟理工学院 | Method for recycling elemental phosphorus from municipal sludge |
| CN117535685B (en) * | 2024-01-09 | 2024-04-02 | 常熟理工学院 | Method for recycling elemental phosphorus from municipal sludge |
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