Method for producing anhydrous hydrogen fluoride by using high-silicon high-calcium fluorite powder

Abstract

The invention provides a method for producing anhydrous hydrogen fluoride by using high-silicon and high-calcium fluorite powder. The method comprises the following steps: reacting mixed sulfuric acid with the high-silicon and high-calcium fluorite powder to obtain crude hydrogen fluoride gas; carrying out primary impurity removal, pre-purification, purification and cooling on the crude hydrogen fluoride gas to obtain purified hydrogen fluoride gas; cooling the purified hydrogen fluoride gas firstly and then cooling with a refrigerant to obtain crude hydrogen fluoride liquid; uncondensed impurities in the purified hydrogen fluoride gas are treated in a water washing tower to obtain a byproduct fluosilicic acid, and residual gas is discharged after being desulfurized in a tail gas tower and reaching the standard; heavy component impurities at the bottom of the rectifying tower are discharged from a residue discharging pipeline, and hydrogen fluoride liquid at the upper part of the rectifying tower enters a degassing tower; the hydrogen fluoride liquid is separated in the degassing tower, light component gas impurities at the upper part of the degassing tower are discharged from an exhaust pipeline, and anhydrous hydrogen fluoride is obtained at the lower part of the degassing tower. The method for producing anhydrous hydrogen fluoride by using high-silicon high-calcium fluorite powder provided by the invention has the advantages of low production cost and high quality of the prepared product.

Description

Technical Field

[0001] The invention relates to the technical field of anhydrous hydrogen fluoride production, and in particular to a method for producing anhydrous hydrogen fluoride by utilizing high-silicon and high-calcium fluorite powder. Background Art

[0002] Anhydrous hydrogen fluoride is mainly used as a raw material for preparing refrigerants, high-purity hydrogen fluoride, lithium hexafluorophosphate and other products. Its production mainly uses high-quality fluorite powder and sulfuric acid as the main raw materials.

[0003] The main characteristics of metal-associated fluorite ore are: complex metal types and low calcium fluoride content. It is difficult to develop and utilize it. It is difficult to upgrade it into high-quality fluorite powder after mineral processing. Moreover, its use in the production of anhydrous hydrogen fluoride will seriously restrict the increase of its added value.

[0004] In view of the demand for fluorite powder in the production of anhydrous hydrogen fluoride, anhydrous hydrogen fluoride can currently be produced by using high-silicon and high-calcium fluorite powder obtained after beneficiation of fluorite ore that co-exists with metals such as lead, zinc, and tungsten.

[0005] Therefore, there is an urgent need to develop a method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder with low production cost and high product quality. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for producing anhydrous hydrogen fluoride by using high-silicon and high-calcium fluorite powder with low production cost and high product quality.

[0007] In order to solve the above technical problems, the present invention provides a method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder, comprising the following steps:

[0008] Mixed sulfuric acid and high-silicon and high-calcium fluorite powder are reacted in a reactor to obtain crude hydrogen fluoride gas;

[0009] The crude hydrogen fluoride gas is sequentially preliminarily impurized by countercurrent mixed sulfuric acid in the gas guide pipe, pre-purified by countercurrent pre-purifying acid in the pre-purification tower, purified by countercurrent crude hydrofluoric acid in the purification tower, and then cooled to obtain purified hydrogen fluoride gas at a temperature of 40°C-60°C;

[0010] The purified hydrogen fluoride gas is first cooled to 20℃-30℃ in a water cooler, and then cooled by a refrigerant in a two-stage cryogenic freezer to obtain a crude hydrogen fluoride liquid which is temporarily stored in a crude product storage tank;

[0011] The uncondensed impurities in the purified hydrogen fluoride gas are treated in a water scrubber to obtain byproduct fluorosilicic acid, and the remaining gas is discharged after being desulfurized to the standard in a tail gas tower;

[0012] The crude hydrogen fluoride liquid is pumped and pressed into a distillation tower for separation. The heavy component impurities at the bottom of the distillation tower are discharged from the exhaust pipeline, and the hydrogen fluoride liquid at the top of the distillation tower enters a degassing tower;

[0013] The hydrogen fluoride liquid is separated in the degassing tower, the light component gas impurities in the upper part of the degassing tower are discharged from the exhaust pipeline, and anhydrous hydrogen fluoride with a purity of more than 99.99% is obtained in the lower part of the degassing tower.

[0014] Furthermore, the mixed sulfuric acid is a mixture of 105wt% oleum and 98wt% sulfuric acid, and the mass ratio of the 105wt% oleum to the 98wt% sulfuric acid is 1:1-4:1.

[0015] Furthermore, the high-silicon and high-calcium fluorite powder is a fluorite powder with a SiO2 content greater than 2.0wt% and a CaCO3 content greater than 4.0wt%.

[0016] Preferably, the SiO2 content in the high-silicon and high-calcium fluorite powder is 2.0wt%-2.5wt%, and the CaCO3 content is 4.0wt%-6.0wt%.

[0017] Furthermore, the mass ratio of the mixed sulfuric acid to the high-silicon and high-calcium fluorite powder is 1.1:1-1.25:1.

[0018] Furthermore, the mixed sulfuric acid enters the reactor through an air duct connected to the reactor to react with high-silicon and high-calcium fluorite powder. During the process of the generated crude hydrogen fluoride gas being discharged from the air duct to the pre-purification tower, it contacts in reverse with the mixed sulfuric acid flowing from the air duct to the reactor to initially remove impurities.

[0019] Furthermore, the reaction furnace is an externally heated rotary reaction furnace, the rotation speed of the reaction furnace is 1.7rpm-2rpm, and the outlet temperature of the mixing chamber of the reaction furnace is 450℃-600℃.

[0020] Furthermore, the pre-purification acid is a mixture of 98wt% sulfuric acid and water, and the water content in the pre-purification acid is 6wt%-15wt%.

[0021] Furthermore, the refrigerant is ethylene glycol with a mass percentage concentration of 30%-40%.

[0022] Furthermore, the reboiler of the distillation tower and the reboiler of the degassing tower are both heated by steam, and the distillation tower is pressurized and controlled, with the tower pressure being controlled at 240 Kpa-270 Kpa.

[0023] The present invention provides a method for producing anhydrous hydrogen fluoride by utilizing high-silicon and high-calcium fluorite powder. The crude hydrogen fluoride gas is preliminarily purified by countercurrent contact between mixed sulfuric acid entering a reaction furnace and crude hydrogen fluoride gas generated by a reaction and flowing from the reaction furnace to a pre-purification tower. The problem of dust generated by the reaction easily blocking the pre-purification tower is solved, and sulfuric acid mist mixed in the crude hydrogen fluoride gas is washed by the mixed sulfuric acid and refluxed to the reaction furnace to continue to participate in the reaction. The conversion rate of the high-silicon and high-calcium fluorite powder can also be effectively improved.

[0024] In addition, the present invention provides a method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder, which uses high-silicon and high-calcium fluorite powder with a fluorite grade of less than 97wt% as a raw material, and reacts with mixed sulfuric acid to obtain crude hydrogen fluoride gas, which is subjected to multi-stage fine purification and condensation by a pre-purification tower, a purification tower, a water cooler, and a deep cooler, and can efficiently remove a large amount of impurities mixed in the crude hydrogen fluoride gas produced by the reaction of high-silicon and high-calcium fluorite powder with mixed sulfuric acid, which not only solves the problem of shutdown caused by the blockage of the system by the crude hydrogen fluoride gas, but also helps to increase the output of anhydrous hydrogen fluoride products. At the same time, the quality of the anhydrous hydrogen fluoride products produced can be improved, so that the purity of the anhydrous hydrogen fluoride products produced can reach more than 99.99%, which can reach the superior grade in the national standard GB / T 7746-2023, and can fully meet the normal use of the production of refrigerants and other products.

[0025] At the same time, the present invention provides a method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder. The high-silicon and high-calcium fluorite powder with high impurity content, low grade and low price can produce anhydrous hydrogen fluoride with a purity of more than 99.99%, which not only expands the selectivity of raw material fluorite, improves the utilization rate and added value of co-existing fluorite ore, but also can significantly reduce the production cost per ton of hydrogen fluoride, greatly improving the market competitiveness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] See also Figure 1 The present invention provides a method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder, comprising the following steps:

[0028] Step 1) Preparation of hydrogen fluoride: Mixed sulfuric acid and high-silicon and high-calcium fluorite powder are reacted in a reactor to obtain crude hydrogen fluoride gas.

[0029] The mixed sulfuric acid is a mixture of 105wt% oleum and 98wt% sulfuric acid, and the mass ratio of the 105wt% oleum to the 98wt% sulfuric acid is 1:1-4:1.

[0030] Among them, the high-silicon and high-calcium fluorite powder is a fluorite powder with a SiO2 content greater than 2.0wt% and a CaCO3 content greater than 4.0wt%.

[0031] As a specific implementation of the present invention, high-silicon and high-calcium fluorite powder with a SiO2 content of 2.0wt%-2.5wt% and a CaCO3 content of 4.0wt%-6.0wt% is selected.

[0032] In this way, the use of high-silicon and high-calcium fluorite powder with high impurity content and low grade to produce anhydrous hydrogen fluoride products can not only expand the selectivity of raw material fluorite and improve the utilization rate and added value of co-existing fluorite ore, but also, due to the low price of co-existing fluorite ores such as high-silicon and high-calcium fluorite powder, it can also greatly reduce the production cost of anhydrous hydrogen fluoride products, thereby greatly improving the market competitiveness of the product.

[0033] Among them, according to the composition and content of the mixed sulfuric acid and the impurity content of the high-silicon and high-calcium fluorite powder, the mass ratio of the mixed sulfuric acid to the high-silicon and high-calcium fluorite powder is controlled to be 1.1:1-1.25:1.

[0034] Among them, the chemical equation for the reaction of mixed sulfuric acid and high-silicon and high-calcium fluorite powder is as follows:

[0035] H2SO4+CaF2=2HF+CaSO4;

[0036] H2SO4+CaCO3=CaSO4+CO2+H2O;

[0037] 4HF+SiO2=SiF4+2H2O.

[0038] Among them, as a specific embodiment of the present invention, the reactor adopts an externally heated rotary reactor, and in order to make the high-silicon and high-calcium fluorite powder and the mixed sulfuric acid be evenly mixed and fully reacted, the speed of the reactor is set to 1.7rpm-2rpm. In addition, since the reaction of fluorite and sulfuric acid is an endothermic reaction, in order to improve the reaction efficiency, in order to avoid excessively high reaction temperature causing energy waste and causing the temperature of hydrogen fluoride discharged inside and outside the air duct to be too high, and in order to avoid excessively low reaction temperature causing insufficient material reaction and reducing the conversion rate of fluorite, therefore, the outlet temperature of the mixing chamber of the reactor is controlled at 450℃-600℃ according to the amount of feed.

[0039] Since the reaction is based on high-silicon and high-calcium fluorite powder with high impurity content and low grade, the crude hydrogen fluoride gas produced will contain impurities such as sulfur dioxide, water, sulfuric acid, sulfur trioxide, silicon tetrafluoride, carbon dioxide, etc. Therefore, the crude hydrogen fluoride gas produced needs to be subsequently purified.

[0040] Step 2) Hydrogen fluoride purification: The crude hydrogen fluoride gas is sequentially removed by countercurrent mixed sulfuric acid in the air duct, pre-purified by countercurrent pre-purifying acid in the pre-purification tower, purified by countercurrent crude hydrofluoric acid in the purification tower, and then cooled to obtain purified hydrogen fluoride gas at a temperature of 40°C-60°C.

[0041] Specifically, the crude hydrogen fluoride gas enters the air guide pipe and contacts the mixed acid in the reverse flow for preliminary impurity removal, then enters the pre-purification tower and contacts the pre-purification acid in the reverse flow for pre-purification, then enters the purification tower and contacts the crude hydrofluoric acid in the reverse flow for re-purification, and finally cools down to 40-60°C to obtain purified hydrogen fluoride gas.

[0042] Among them, as a specific embodiment of the present invention, mixed sulfuric acid is directly sent into the reactor through an air duct connected to the reactor to react with the high-silicon and high-calcium fluorite powder pre-added into the reactor, and the crude hydrogen fluoride gas produced is discharged from the air duct to which the mixed sulfuric acid is added to the pre-purification tower for subsequent purification. In the process of the crude hydrogen fluoride gas being discharged from the air duct to which the mixed sulfuric acid is added to the pre-purification tower, the crude hydrogen fluoride gas is reversely contacted with the mixed sulfuric acid flowing from the air duct to the reactor to preliminarily purify the crude hydrogen fluoride gas, which can not only solve the problem that the dust produced by the reaction is easy to cause blockage of the pre-purification tower, but also can wash the sulfuric acid mist mixed in the crude hydrogen fluoride gas back to the reactor through the mixed sulfuric acid to continue to participate in the reaction, and can also effectively improve the conversion rate of the high-silicon and high-calcium fluorite powder.

[0043] The pre-purification acid is a mixture of 98 wt % sulfuric acid and water, and the water content in the pre-purification acid is 6 wt %-15 wt %.

[0044] In the pre-purification tower, the crude hydrogen fluoride gas is fully contacted with the counter-flowing pre-purification acid, so that dust, sulfuric acid mist, moisture and other impurities in the crude hydrogen fluoride gas can be washed away.

[0045] Among them, the crude hydrogen fluoride gas can be purified again after being fully contacted with the crude hydrofluoric acid flowing in the reverse direction in the purification tower to remove impurities such as dust, elemental sulfur, sulfuric acid, and water in the crude hydrogen fluoride gas.

[0046] After the crude hydrogen fluoride gas has been purified multiple times as described above, the purified hydrogen fluoride gas obtained still contains impurities such as silicon tetrafluoride, carbon dioxide, sulfur dioxide, and water.

[0047] Step 3) Hydrogen fluoride condensation: The purified hydrogen fluoride gas first enters a water cooler for initial cooling, and the temperature is initially reduced to 20-30° C., and then enters a two-stage deep freezer, and is further cooled by the refrigerant to obtain a crude hydrogen fluoride liquid, which is stored in a crude product storage tank.

[0048] The refrigerant is ethylene glycol with a mass percentage concentration of 30%-40%.

[0049] Through the above condensation treatment, the hydrogen fluoride and part of the impurities in the purified hydrogen fluoride gas can be condensed to obtain a crude hydrogen fluoride liquid, while the uncondensed gas impurities such as HF, SiF4, SO2, CO2 in the purified hydrogen fluoride gas are subjected to subsequent water washing treatment.

[0050] Step 4) Water washing treatment: The uncondensed impurities in the hydrogen fluoride gas are purified and treated in a water washing tower to obtain a by-product of fluorosilicic acid, and the remaining gas is discharged after the desulfurization reaches the standard in the tail gas tower.

[0051] Specifically, the uncondensed impurities in the purified hydrogen fluoride gas are introduced into the water scrubber from the bottom, and the washing water is sprayed into the water scrubber from the top, and fully contacted and reacted with the uncondensed HF, SiF4, SO2, CO2 and other gas impurities in the purified hydrogen fluoride gas introduced from the bottom of the water scrubber to obtain the by-product fluorosilicic acid, and the remaining gas enters the process tail gas tower for desulfurization and then meets the emission standards.

[0052] The chemical equation for the hydrolysis reaction between HF and SiF4 and water to obtain the byproduct fluorosilicic acid is as follows:

[0053] SiF4+2HF+H2O=H2SiF6+2H2O.

[0054] The water washing temperature is controlled at 50℃-60℃, and the water washing flow rate is controlled at 0.5-1.5m 3 / min.

[0055] Step 5) Hydrogen fluoride distillation: The crude hydrogen fluoride liquid is pressurized by a pump and then pumped into a distillation tower for distillation separation.

[0056] The reboiler of the distillation tower is heated by steam, and the distillation tower is pressurized and controlled, with the tower pressure controlled at 240Kpa-270Kpa.

[0057] After the crude hydrogen fluoride liquid is separated in the distillation tower, the heavy component impurities at the bottom of the distillation tower are discharged from the exhaust pipeline, and the hydrogen fluoride liquid at the top of the distillation tower enters the degassing tower.

[0058] The hydrogen fluoride liquid from the upper part of the distillation tower enters the degassing tower for further separation. The reboiler of the degassing tower is heated by steam. The light component gas impurities in the upper part of the degassing tower are discharged from the exhaust pipeline. Anhydrous hydrogen fluoride with a purity of more than 99.99% can be obtained at the lower part of the degassing tower.

[0059] The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder provided in an embodiment of the present invention, when separating crude hydrogen fluoride liquid in a distillation tower and a degassing tower to obtain anhydrous hydrogen fluoride product, utilizes the property that the components in the crude hydrogen fluoride liquid have different volatilities, that is, the vapor pressures of the components are different at the same temperature, so that the light components (low boiling substances) in the liquid phase are transferred to the gas phase, and the heavy components (high boiling substances) in the gas phase are transferred to the liquid phase, thereby achieving the purpose of separating the crude hydrogen fluoride liquid to obtain anhydrous hydrogen fluoride.

[0060] The following is a specific description of a method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder provided by the present invention through examples.

[0061] Example 1

[0062] The method of the present invention is used to produce anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder, and the steps are as follows:

[0063] (1) Preparation of hydrogen fluoride: A mixed sulfuric acid (a mixed acid of 105 wt% oleum and 98 wt% sulfuric acid in a mass ratio of 2:1) and a high-silicon and high-calcium fluorite powder (SiO2 content of 2.2 wt%, CaCO3 content of 5 wt%) were added to an externally heated rotary reactor in a mass ratio of 1.18:1 to react and produce a crude hydrogen fluoride gas. The outlet temperature of the mixing chamber of the externally heated rotary reactor was controlled to be 560° C., and the rotation speed of the externally heated rotary reactor was 1.7 rpm.

[0064] (2) Hydrogen fluoride purification: The crude hydrogen fluoride gas produced in the externally heated rotary kiln enters the air duct and is fully contacted with the mixed acid (a mixed acid of 105 wt% oleum and 98 wt% sulfuric acid in a mass ratio of 2:1) flowing in a countercurrent manner to preliminarily remove impurities such as dust and sulfuric acid mist. The crude hydrogen fluoride gas then enters the tower from the lower part of the pre-purification tower and is fully contacted with the pre-purification acid (a mixed solution of 98 wt% sulfuric acid and water, with the water content in the pre-purification acid being controlled to be 10 wt%) flowing in a countercurrent manner to again wash away impurities such as dust, sulfuric acid mist, and water in the gas. The pre-purified HF gas enters the purification tower for a third purification. The temperature of the purified HF gas drops to 50° C. and enters the water cooler.

[0065] (3) Hydrogen fluoride condensation: The crude hydrogen fluoride gas passes through a water cooler to intercept most of the fluorosilicic acid and elemental sulfur, achieving the fourth purification of the HF gas. The water-cooled HF gas enters the hydrogen fluoride deep cooling, further reducing the HF gas temperature to 10°C, liquefies it, forms liquid crude HF, and enters the hydrogen fluoride distillation. The uncondensed gas (containing a large amount of SiF4) enters the water washing process.

[0066] (4) Water washing treatment: A large amount of SiF4 and uncondensed HF enter the water washing treatment together, and the gas and liquid are countercurrently absorbed. The liquid after water washing passes through the heat exchanger to remove the heat generated by the reaction from the system, and the water washing temperature is controlled at 50°C and the water washing flow rate is controlled at 0.8m 3 / min, all SiF4 in the gas is converted into fluorosilicic acid to produce high-quality fluorosilicic acid, and the other gases enter the tail gas absorption system for treatment.

[0067] (5) Hydrogen fluoride distillation: The crude HF cooled down from the hydrogen fluoride condensation system is pumped into a distillation tower. The distillation tower is pressurized and the tower pressure is controlled at 240 KPa. Heavy components such as sulfuric acid, fluorosilicic acid, and water in the crude HF are discharged from the bottom of the tower. HF and other light components are condensed at the top of the tower and enter the light removal tower. The tower pressure is controlled at 140 KPa. SO2 is removed from the top of the tower. The bottom of the tower is cooled to produce anhydrous hydrogen fluoride product. The hydrogen fluoride product is subjected to product quality analysis. The analysis results of the anhydrous hydrogen fluoride product are shown in Table 1. As can be seen from Table 1, the embodiment of the present invention obtains anhydrous hydrogen fluoride of superior quality.

[0068] Example 2

[0069] The method of the present invention is used to produce anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder, and the steps are as follows:

[0070] (1) Preparation of hydrogen fluoride: Mixed sulfuric acid (a mixed acid of 105 wt% oleum and 98 wt% sulfuric acid in a mass ratio of 2.2:1) and high-silicon and high-calcium fluorite powder (SiO2 content of 2.35 wt%, CaCO3 content of 5 wt%) were added to an externally heated rotary reactor in a mass ratio of 1.185:1 to react and produce crude hydrogen fluoride gas. The outlet temperature of the mixing chamber of the externally heated rotary reactor was controlled to be 565° C., and the rotation speed of the externally heated rotary reactor was 1.72 rpm.

[0071] (2) Hydrogen fluoride purification: The crude hydrogen fluoride gas produced in the externally heated rotary kiln enters the air duct and is fully contacted with the mixed acid (a mixed acid of 105 wt% oleum and 98 wt% sulfuric acid in a mass ratio of 2.2:1) flowing in a countercurrent manner to preliminarily remove impurities such as dust and sulfuric acid mist. The crude hydrogen fluoride gas then enters the tower from the lower part of the pre-purification tower and is fully contacted with the pre-purification acid (a mixed solution of 98 wt% sulfuric acid and water, with the water content in the pre-purification acid being controlled to be 10 wt%) flowing in a countercurrent manner to again wash away impurities such as dust, sulfuric acid mist, and water in the gas. The pre-purified HF gas enters the purification tower for a third purification. The temperature of the purified HF gas drops to 49° C. and enters the water cooler.

[0072] (3) Hydrogen fluoride condensation: The crude hydrogen fluoride gas passes through a water cooler to intercept most of the fluorosilicic acid and sulfur, achieving the fourth purification of the HF gas. The water-cooled HF gas enters the hydrogen fluoride deep cooling, further reducing the HF gas temperature to 7°C, liquefies it, forms liquid crude HF, and enters the hydrogen fluoride distillation. The uncondensed gas (containing a large amount of SiF4) enters the water washing process.

[0073] (4) Water washing treatment: A large amount of SiF4 and uncondensed HF enter the water washing treatment together, and the gas and liquid are countercurrently absorbed. The liquid after water washing passes through the heat exchanger to remove the heat generated by the reaction from the system, and the water washing temperature is controlled at 55°C and the water washing flow rate is controlled at 1.0m 3 / min, all SiF4 in the gas is converted into fluorosilicic acid to produce high-quality fluorosilicic acid, and the other gases enter the tail gas absorption system for treatment.

[0074] (5) Hydrogen fluoride distillation: The crude HF cooled down from the hydrogen fluoride condensation system is pumped into a distillation tower. The distillation tower is pressurized and the tower pressure is controlled at 250 KPa. Heavy components such as sulfuric acid, fluorosilicic acid, and water in the crude HF are discharged from the bottom of the tower. HF and other light components are condensed at the top of the tower and enter the light removal tower. The tower pressure is controlled at 150 KPa. SO2 is removed from the top of the tower. The bottom of the tower is cooled to produce anhydrous hydrogen fluoride product. The hydrogen fluoride product is subjected to product quality analysis. The analysis results of the anhydrous hydrogen fluoride product are shown in Table 1. As can be seen from Table 1, the embodiment of the present invention obtains anhydrous hydrogen fluoride of superior quality.

[0075] Example 3

[0076] The method of the present invention is used to produce anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder, and the steps are as follows:

[0077] (1) Preparation of hydrogen fluoride: Mixed sulfuric acid (a mixed acid of 105 wt% oleum and 98 wt% sulfuric acid in a mass ratio of 2.4:1) and high-silicon and high-calcium fluorite powder (SiO2 content of 2.5 wt%, CaCO3 content of 6 wt%) were added to an externally heated rotary reactor in a mass ratio of 1.19:1 to react and produce crude hydrogen fluoride gas. The outlet temperature of the mixing chamber of the externally heated rotary reactor was controlled to be 570° C., and the rotation speed of the externally heated rotary reactor was 1.75 rpm.

[0078] (2) Hydrogen fluoride purification: The crude hydrogen fluoride gas produced in the externally heated rotary kiln enters the air duct and is fully contacted with the mixed acid (a mixed acid of 105 wt% oleum and 98 wt% sulfuric acid in a mass ratio of 2.4:1) flowing in a countercurrent manner to preliminarily remove impurities such as dust and sulfuric acid mist. The crude hydrogen fluoride gas then enters the tower from the lower part of the pre-purification tower and is fully contacted with the pre-purification acid (a mixed solution of 98 wt% sulfuric acid and water, with the water content in the pre-purification acid controlled to be 10 wt%) flowing in a countercurrent manner to again wash away impurities such as dust, sulfuric acid mist, and water in the gas. The pre-purified HF gas enters the purification tower for a third purification. The temperature of the purified HF gas drops to 48°C and enters the water cooler.

[0079] (3) Hydrogen fluoride condensation: The crude hydrogen fluoride gas passes through a water cooler to intercept most of the fluorosilicic acid and sulfur, achieving the fourth purification of the HF gas. The water-cooled HF gas enters the hydrogen fluoride deep cooling, further reducing the HF gas temperature to 5°C for liquefaction to form liquid crude HF, which enters the hydrogen fluoride distillation, and the uncondensed gas (containing a large amount of SiF4) enters the water washing process.

[0080] (4) Water washing treatment: A large amount of SiF4 and uncondensed HF enter the water washing treatment together, and the gas and liquid are countercurrently absorbed. The liquid after water washing passes through the heat exchanger to remove the heat generated by the reaction from the system, and the water washing temperature is controlled at 58°C and the water washing flow rate is controlled at 1.2m 3 / min, all SiF4 in the gas is converted into fluorosilicic acid to produce high-quality fluorosilicic acid, and the other gases enter the tail gas absorption system for treatment.

[0081] (5) Hydrogen fluoride distillation: The crude HF cooled down by the hydrogen fluoride condensation system is pumped into the distillation tower. The distillation tower is pressurized and the tower pressure is controlled at 270 KPa. The heavy components such as sulfuric acid, fluorosilicic acid, and water in the crude HF are discharged from the bottom of the tower. HF and other light components are condensed at the top of the tower and enter the light removal tower. The tower pressure is controlled at 180 KPa. SO2 is removed from the top of the tower. The bottom of the tower is cooled to produce anhydrous hydrogen fluoride product. The product quality analysis of the hydrogen fluoride product is performed to obtain the anhydrous hydrogen fluoride product analysis results as shown in Table 1. It can be seen from Table 1 that the embodiment of the present invention obtains anhydrous hydrogen fluoride of superior quality.

[0082] Table 1

[0083]

[0084] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder, characterized in that: The steps include: Mixed sulfuric acid and high-silicon and high-calcium fluorite powder are reacted in a reactor to obtain crude hydrogen fluoride gas; The crude hydrogen fluoride gas is sequentially preliminarily impurized by countercurrent mixed sulfuric acid in the gas guide pipe, pre-purified by countercurrent pre-purifying acid in the pre-purification tower, purified by countercurrent crude hydrofluoric acid in the purification tower, and then cooled to obtain purified hydrogen fluoride gas at a temperature of 40°C-60°C; The purified hydrogen fluoride gas is first cooled to 20℃-30℃ in a water cooler, and then cooled by a refrigerant in a two-stage cryogenic freezer to obtain a crude hydrogen fluoride liquid which is temporarily stored in a crude product storage tank; The uncondensed impurities in the purified hydrogen fluoride gas are treated in a water scrubber to obtain byproduct fluorosilicic acid, and the remaining gas is discharged after being desulfurized to the standard in a tail gas tower; The crude hydrogen fluoride liquid is pumped and pressed into a distillation tower for separation. The heavy component impurities at the bottom of the distillation tower are discharged from the exhaust pipeline, and the hydrogen fluoride liquid at the top of the distillation tower enters a degassing tower; The hydrogen fluoride liquid is separated in the degassing tower, the light component gas impurities in the upper part of the degassing tower are discharged from the exhaust pipeline, and anhydrous hydrogen fluoride with a purity of more than 99.99% is obtained in the lower part of the degassing tower.

2. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 1, characterized in that: The mixed sulfuric acid is a mixture of 105wt% oleum and 98wt% sulfuric acid, and the mass ratio of the 105wt% oleum to the 98wt% sulfuric acid is 1:1-4:

1.

3. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 2, characterized in that: The high-silicon and high-calcium fluorite powder is a fluorite powder with a SiO2 content greater than 2.0wt% and a CaCO3 content greater than 4.0wt%.

4. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 3, characterized in that: The SiO2 content in the high-silicon and high-calcium fluorite powder is 2.0wt%-2.5wt%, and the CaCO3 content is 4.0wt%-6.0wt%.

5. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 4, characterized in that: The mass ratio of the mixed sulfuric acid to the high-silicon and high-calcium fluorite powder is 1.1:1-1.25:

1.

6. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 5, characterized in that: The mixed sulfuric acid enters the reactor through an air duct connected to the reactor to react with high-silicon and high-calcium fluorite powder. During the process of the generated crude hydrogen fluoride gas being discharged from the air duct to the pre-purification tower, it contacts the mixed sulfuric acid flowing from the air duct to the reactor in reverse order to initially remove impurities.

7. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 6, characterized in that: The reaction furnace is an externally heated rotary reaction furnace, the rotation speed of the reaction furnace is 1.7rpm-2rpm, and the outlet temperature of the mixing chamber of the reaction furnace is 450℃-600℃.

8. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 1, characterized in that: The pre-purification acid is a mixture of 98 wt % sulfuric acid and water, and the water content in the pre-purification acid is 6 wt %-15 wt %.

9. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 1, characterized in that: The refrigerant is ethylene glycol with a mass percentage concentration of 30%-40%.

10. The method for producing anhydrous hydrogen fluoride using high-silicon and high-calcium fluorite powder according to claim 1, characterized in that: The reboiler of the distillation tower and the reboiler of the degassing tower are both heated by steam, and the distillation tower is pressurized and controlled, with the tower pressure being controlled at 240Kpa-270Kpa.

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