阅读说明：本技术 一种综合利用氟硅酸钠高效生产氟化钠、氟化铝和四氯化硅的方法 (Method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by comprehensively utilizing sodium fluosilicate ) 是由 范川林 朱庆山 杨海涛 于 2018-07-04 设计创作，主要内容包括：本发明公开了一种综合利用氟硅酸钠高效生产氟化钠、氟化铝和四氯化硅的方法,所述方法包括流态化干燥工序、流态化分解工序、气相沉积工序、汽化工序和冷凝工序。在本方法中,氟硅酸钠经过流态化干燥得到无水氟硅酸钠；然后进入流态化分解工序,得到氟化钠产品以及富四氟化硅的混合气；在气相沉积工序,富四氟化硅的混合气与汽化后的三氯化铝反应,得到氟化铝产品和富四氯化硅混合气；富四氯化硅混合气经过冷凝工序得到四氯化硅产品,冷凝工序尾气送碱洗塔处理。本方法具有流程短,能耗低,环境友好,产品附加值高等优点。(The invention discloses a method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by comprehensively utilizing sodium fluosilicate. In the method, the anhydrous sodium fluosilicate is obtained by fluidized drying of sodium fluosilicate; then entering a fluidized decomposition process to obtain a sodium fluoride product and a silicon tetrafluoride-rich mixed gas; in the vapor deposition process, the mixed gas rich in silicon tetrafluoride reacts with vaporized aluminum trichloride to obtain an aluminum fluoride product and a mixed gas rich in silicon tetrachloride; and (3) the silicon tetrachloride-rich mixed gas is subjected to a condensation process to obtain a silicon tetrachloride product, and tail gas of the condensation process is sent to an alkaline washing tower for treatment. The method has the advantages of short flow, low energy consumption, environmental friendliness, high product added value and the like.)

1. The method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by comprehensively utilizing sodium fluosilicate comprises five processes of a fluidized drying process (1), a fluidized decomposition process (2), a vapor deposition process (3), a vaporization process (4) and a condensation process (5), and specifically comprises the following steps:

1) firstly, carrying out fluidization drying on a sodium fluosilicate raw material to obtain anhydrous sodium fluosilicate, and sending dry tail gas to an alkaline tower for treatment;

2) conveying anhydrous sodium fluosilicate to a fluidized decomposition process to obtain a sodium fluoride product and a silicon tetrafluoride-enriched mixed gas;

3) after the vaporization process, the aluminum trichloride enters a gas phase deposition process to react with the silicon tetrafluoride from a decomposition process to obtain an aluminum fluoride product and a silicon tetrachloride-rich mixed gas;

4) and (4) the mixed gas rich in silicon tetrachloride enters a condensation process, silicon tetrachloride products are obtained through condensation, and tail gas in the condensation process is sent to an alkaline washing tower for treatment.

2. The method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by using sodium fluosilicate according to claim 1, wherein the fluidized drying process (1) adopts a fluidized bed reactor, the drying temperature is 0-200 ℃, and the drying time is 0.1-36 h.

3. The method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by using sodium fluosilicate according to claim 1, wherein the fluidizing gas in the fluidizing and drying process (1) is hydrogen fluoride mixed gas, the volume ratio of hydrogen fluoride in the hydrogen fluoride mixed gas is 0.1-15%, and the rest gas is one or more of purified nitrogen, purified air and purified argon.

4. The method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by using sodium fluosilicate according to claim 1, wherein a fluidized bed reactor is adopted in the fluidized decomposition process (2), the decomposition temperature is 400-700 ℃, the retention time is 15-300 min, and the fluidized gas is one or more of purified nitrogen, purified air and purified argon.

5. The method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by using sodium fluosilicate according to claim 1, wherein the vapor deposition process (3) adopts a fluidized bed reactor, the fluidized gas is silicon tetrafluoride-rich mixed gas generated in the fluidized pyrolysis process (2), the reaction temperature is 200-600 ℃, and the molar ratio of aluminum trichloride to silicon tetrafluoride is 1.34-1.50.

6. The method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by using sodium fluosilicate according to claim 1, wherein the aluminum trichloride and a carrier gas enter a vaporization process (4) together, the vaporization temperature is 150-300 ℃, and the carrier gas is one or more of purified air, purified nitrogen and purified argon.

7. The method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by using sodium fluosilicate according to claim 1, wherein the aluminum trichloride is anhydrous aluminum trichloride.

Technical Field

The invention belongs to the field of chemical industry and materials, and particularly relates to a method for efficiently producing various chemicals (sodium fluoride, aluminum fluoride and silicon tetrachloride) by comprehensively utilizing sodium fluosilicate.

Background

China is a big country for producing phosphate fertilizers, and a large amount of fluosilicic acid is produced in the production. At present, the fluosilicic acid is mainly used for producing sodium fluosilicate. The sodium fluosilicate product has low value, excessive productivity and poor economic benefit. Therefore, the method has great economic and social benefits by innovating and developing the sodium fluosilicate to produce the high-added-value fluoride salt chemical product. Sodium fluorosilicate can be used to prepare sodium fluoride and silicon tetrafluoride by thermal decomposition. Sodium fluoride is an important fluoride salt and is a raw material for manufacturing other fluorides, and can be used for producing artificial cryolite. Silicon tetrafluoride is an important chemical raw material in the electronic and semiconductor industries, and is mainly used as an etching agent for tantalum silicide and silicon nitride.

But the sodium fluosilicate is easy to melt and agglomerate in the decomposition process of the fixed bed, so that the decomposition is incomplete and the energy consumption is increased. Silicon tetrafluoride is an indispensable chemical reagent in the electronic industry, but has small market capacity, and is difficult to be effectively matched with the huge amount of sodium fluosilicate. And the silicon tetrafluoride gas is difficult to store. In order to develop a wider silicon tetrafluoride application market, development of a new process and a new flow is urgently needed.

In order to solve the problem of melting and caking in the decomposition process of sodium fluosilicate, a large amount of research is carried out by scientific and technical personnel, and a corresponding patent technology is formed. Chinese patent 200910024293.6 discloses a method for pyrolyzing sodium fluosilicate by using a rotary reaction furnace, which comprises the steps of firstly drying at low temperature and negative pressure in a calcining furnace to remove moisture; then mixing the inert auxiliary agent and the dried sodium fluosilicate according to a certain proportion, and calcining and decomposing the mixture at high temperature in a rotary reaction furnace to obtain silicon tetrafluoride gas and a mixture of the inert auxiliary agent and sodium fluoride. Although the process can relieve the problem of melt agglomeration, the introduced inert auxiliary agent and sodium fluoride are difficult to decompose, and the utilization of the sodium fluoride is not facilitated. And the rotary reaction furnace is difficult to realize large-scale continuous production. Chinese patent 201510302232.7 discloses a method and a device for preparing silicon tetrafluoride by decomposing sodium fluosilicate at high temperature. Firstly, uniformly mixing sodium fluosilicate and a decomposition auxiliary agent, flatly paving the mixture in a tray in a thin-layer static mode, wherein the flatly paving thickness is 1-20 mm, stacking the tray on a tray frame, and placing the tray in a decomposition kettle body for heating and decomposition. However, the process still adopts fixed bed decomposition, has the disadvantages of small treatment capacity, complex operation, no contribution to large-scale continuous production, and needs to add a decomposition auxiliary agent to increase the cost. Chinese patent 201710216329.5 discloses a cyclic production process for preparing hydrogen fluoride from fluorosilicic acid, which involves thermally decomposing sodium fluorosilicate to prepare sodium fluoride solid and silicon tetrafluoride gas, but does not present a practical operation scheme. Chinese patent 201110258173.X discloses a method for preparing silicon tetrafluoride by using a rotary kiln, which comprises the steps of pre-reacting sodium fluosilicate with concentrated sulfuric acid to obtain fluosilicic acid, then performing low-temperature thermal decomposition by using the rotary kiln to obtain a mixed gas of hydrogen fluoride and silicon tetrafluoride, and finally performing freeze separation to obtain silicon tetrafluoride gas with higher purity. The process relates to the separation of the hydrogen fluoride and silicon tetrafluoride mixed gas, increases the production cost, and has smaller market capacity of silicon tetrafluoride. Chinese patent 200980156839.1 discloses a method and system for producing silicon tetrafluoride from fluorosilicates in a fluidized bed reactor. And thermally decomposing fluorosilicate to obtain silicon tetrafluoride gas, and the mixture of fluorosilicate and fluoride. A portion of the silicon tetrafluoride is recycled to the fluidized bed decomposition reactor for use as fluidizing gas. The mixture of fluosilicate and fluorine salt is added with fluosilicic acid to regenerate fluosilicate, and the fluosilicate is returned to the drying and decomposing process. The fluidized bed reactor in the process is an effective method for solving the problem of fusion agglomeration, silicon tetrafluoride is used as the fluidizing gas, no external gas is introduced, and the problem of separation and purification of mixed gas is avoided. However, the process regenerates the sodium fluosilicate after the sodium fluosilicate which is not completely decomposed is subjected to a wet process, and has the defects of long process, repeated drying and high energy consumption.

The fumed silica is widely applied to various fields of chemical industry, spraying materials, medicine, environmental protection and the like, and has very large market capacity. However, the process for preparing white carbon black by silicon tetrafluoride gas-phase hydrolysis requires very high temperature due to the limitation of thermodynamics, and has low reaction conversion rate and difficult industrial implementation.

In conclusion, the existing technology for comprehensively utilizing the sodium fluosilicate has the problems of melting agglomeration, incomplete decomposition, addition of an auxiliary agent, long flow process and the like. The obtained silicon tetrafluoride has small market capacity and is difficult to match with a large amount of sodium fluosilicate. Therefore, the technology for efficiently producing various chemical products by comprehensively utilizing the sodium fluosilicate is of great significance through technological innovation.

Disclosure of Invention

Aiming at the problems, the invention aims to provide a method for efficiently producing various chemicals (sodium fluoride, aluminum fluoride and silicon tetrachloride) by comprehensively utilizing sodium fluosilicate. The method has the advantages of short flow, low energy consumption, environmental friendliness, high product added value and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for producing sodium fluoride, aluminum fluoride and silicon tetrachloride by comprehensively utilizing sodium fluosilicate efficiently comprises five processes of a fluidization drying process 1, a fluidization decomposition process 2, a vapor deposition process 3, a vaporization process 4 and a condensation process 5, and specifically comprises the following steps:

1) firstly, carrying out fluidization drying on a sodium fluosilicate raw material to obtain anhydrous sodium fluosilicate, and sending dry tail gas to an alkaline tower for treatment;

2) conveying anhydrous sodium fluosilicate to a fluidized decomposition process to obtain a sodium fluoride product and a silicon tetrafluoride-enriched mixed gas;

3) after the vaporization process, the aluminum trichloride enters a gas phase deposition process to react with the silicon tetrafluoride from a decomposition process to obtain an aluminum fluoride product and a silicon tetrachloride-rich mixed gas;

4) and (4) the mixed gas rich in silicon tetrachloride enters a condensation process, silicon tetrachloride products are obtained through condensation, and tail gas in the condensation process is sent to an alkaline washing tower for treatment.

Preferably, the fluidized drying process 1 adopts a fluidized bed reactor, the drying temperature is 0-200 ℃, the drying time is 0.1-36 h, the fluidized gas is hydrogen fluoride mixed gas, the volume ratio of hydrogen fluoride in the hydrogen fluoride mixed gas is 0.1-15%, and the rest gas is one or more of purified nitrogen, purified air and purified argon.

Preferably, a fluidized bed reactor is adopted in the fluidized decomposition process 2, the decomposition temperature is 400-700 ℃, the retention time is 15-300 min, and the fluidized gas is one or more of purified nitrogen, purified air and purified argon.

Preferably, the vapor deposition process 3 adopts a fluidized bed reactor, the fluidized gas is the silicon tetrafluoride-rich mixed gas generated in the fluidized pyrolysis process 2, the reaction temperature is 200-600 ℃, and the molar ratio of aluminum trichloride to silicon tetrafluoride is 1.34-1.50.

Preferably, the aluminum trichloride and a carrier gas enter a vaporization process 4 together, the vaporization temperature is 150-300 ℃, the carrier gas is one or more of purified air, purified nitrogen and purified argon, and the aluminum trichloride is anhydrous aluminum trichloride.

Compared with the prior art, the invention has the following outstanding advantages:

(1) the invention adopts the fluidized bed reactor in the working procedures of drying, decomposition, vapor deposition and the like, strengthens mass and heat transfer, has no problem of fusion and agglomeration, saves energy and reduces consumption.

(2) In the fluidized drying process, the hydrogen fluoride mixed gas is introduced, and the hydrolysis of silicon is inhibited while drying.

(3) The invention does not need to add auxiliary agent in the decomposition process, reduces the production cost, does not introduce other materials, and can obtain pure sodium fluoride products.

(4) In the vapor deposition process, anhydrous aluminum trichloride and silicon tetrafluoride are introduced to react to obtain an aluminum fluoride product and a silicon tetrachloride product.

(5) The aluminum fluoride product can be used for aluminum metallurgy, and the silicon tetrachloride can be used for producing white carbon black, and both have larger market capacity and additional value.

The process for efficiently producing various chemical products by comprehensively utilizing the sodium fluosilicate can simultaneously obtain sodium fluoride products, aluminum fluoride and silicon tetrachloride products with large market capacity and high added value, adopts the fluidized bed reactor, has no problem of melting and caking, has the advantages of high efficiency, low energy consumption, good product quality and the like, and can effectively improve the process for producing various chemical products by comprehensively utilizing the sodium fluosilicate.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.

FIG. 1 is a schematic flow chart of the method for efficiently producing sodium fluoride, aluminum fluoride and silicon tetrachloride by comprehensively utilizing sodium fluosilicate.

Reference numerals: 1. fluidized drying process, 2 fluidized decomposition process, 3 vapor deposition process, 4 vaporization process, 5 condensation process.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. It should be noted that the examples are only for illustrating the technical solutions of the present invention, and not for limiting the same.