A method for producing fumed silica

Abstract

The present application provides a method for producing gas phase silica, comprising: passing silicon halide into the silicon halide channel of the main raw material mixing channel, passing primary hydrogen into the primary hydrogen channel of the main raw material mixing channel, passing air into the primary air channel of the main raw material mixing channel, and then fully mixing in the main raw material mixing channel to form a main mixed gas, which is passed into the main channel of the burner nozzle; passing secondary hydrogen into the secondary hydrogen channel of the burner nozzle; passing secondary air into the secondary air channel of the burner nozzle; the secondary hydrogen channel surrounds the outside of the main channel, and the secondary air channel surrounds the outside of the secondary hydrogen channel; the main mixed gas, secondary hydrogen, and secondary air are burned at the burner nozzle to form gas phase silica. The present application can fully mix the main raw materials, thereby improving the output and yield of silica products.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of fumed silica, and in particular to a method for producing fumed silica. Background Art

[0002] Fumed silica, also known as fumed silica or aerosol silica, is an amorphous porous silica product made by high-temperature hydrolysis of halosilanes in a hydrogen-oxygen flame. Its primary particle size is between 7-40nm and its specific surface area is generally greater than 100m 2 / g, nano-silicon dioxide content is not less than 99.8%, and it is an extremely important inorganic nano-powder material. Due to its excellent stability, reinforcement, thickening and thixotropy, fumed silica is widely used in rubber, plastics, electronics, coatings, adhesives and sealants.

[0003] At present, due to factors such as process control conditions and reaction equipment, the productivity of fumed silica is low, and the pH value of the silica product is low, resulting in high deacidification costs in the later stage.

[0004] For example: Chinese patent application CN1686791A discloses an efficient and energy-saving process for synthesizing vapor phase silica, in which a mixture of two silicon halogen compounds that have been preheated, air and hydrogen are continuously and stably input into a reactor in proportion for mixing, a high-temperature combustion hydrolysis reaction occurs in a synthesis furnace, the synthesis furnace is continuously cooled by pressurized hot water during the reaction, the reaction raw materials are heated by the heat released by the reaction, and vapor phase silica synthesis is carried out. In the technical solution disclosed in the application document, the silicon halogen compounds are not mixed with hydrogen and air, resulting in a low yield of vapor phase silica prepared by this method and a low pH value of the product. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the yield of the existing fumed silica production method is low and the pH value of the product is low.

[0006] A method for producing fumed silica comprises: introducing silicon halide into a silicon halide channel of a main raw material mixing channel at a rate of 220 kg / h to 260 kg / h, introducing primary hydrogen at a rate of 220 m 3 / h~260m 3 / h into the primary hydrogen channel of the main raw material mixing channel, and the air is blown at 700Nm 3 / h~900Nm 3 / h rate into the primary air channel of the main raw material mixing channel, and then after being fully mixed in the main raw material mixing channel, the main mixed gas is formed and introduced into the main channel of the burner nozzle, and the pressure of the main channel is controlled to be 25kPa±2kPa and the temperature is 100℃±3℃; the secondary hydrogen is heated at 22Nm 3 / h~26Nm 3 / h rate into the secondary hydrogen channel of the burner nozzle, and control the pressure of the secondary hydrogen channel to 130kPa~150kPa and the temperature to 25℃±2℃; the secondary air is adjusted to 400Nm 3 / h is passed into the secondary air channel of the burner nozzle, and the pressure of the secondary air channel is controlled to be 40kPa±2kPa and the temperature is controlled to be 100℃±3℃; the secondary hydrogen channel surrounds the outside of the main channel, and the secondary air channel surrounds the outside of the secondary hydrogen channel; the main mixed gas, secondary hydrogen and secondary air are burned at the burner nozzle to form gaseous white carbon black.

[0007] As an option of the main raw material mixing channel in the above scheme, the main raw material mixing channel includes: a primary air channel, a mixing zone arranged behind the primary air channel; a necking zone is arranged at the connection between the air channel and the mixing zone, and a primary hydrogen channel and a silicon halide channel are arranged in the necking zone, wherein the primary hydrogen channel and the silicon halide channel share the same outlet.

[0008] Preferably, the mixing zone is further provided with some flow disturbance plates.

[0009] Preferably, the diameter of the main channel of the burner nozzle is 80 mm.

[0010] Preferably, the width of the secondary hydrogen channel is 10 mm, and the width of the secondary air channel is 10 mm.

[0011] Preferably, in the main raw material mixing channel, the rate of silicon halide introduced into the silicon halide channel is 240 kg / h, and the rate of hydrogen introduced into the primary hydrogen channel is 240 m / h. 3 / h, the air velocity in the primary air channel is 800Nm 3 / h; in the burner nozzle, the rate of hydrogen introduced into the secondary hydrogen channel is 24Nm 3 / h, the secondary air velocity in the secondary air channel is 400Nm 3 / h.

[0012] The silicon halide is at least one of SiCl4, SiHCl3, and CH3SiCl3.

[0013] The beneficial effects of this application are:

[0014] The present application uses primary hydrogen, primary air and silicon halide as the main raw materials for the production of gas phase white carbon black. The primary hydrogen, primary air and silicon halide are fully mixed in advance to obtain the main raw materials, and then the main raw materials are burned with secondary hydrogen and secondary air, thereby improving the reaction efficiency and the yield of white carbon black. By mixing the primary hydrogen, primary air and silicon halide, the generated HCl gas can be volatilized during the combustion process, reducing the acidity of the product, thereby reducing the subsequent deacidification cost of white carbon black.

[0015] The main raw material mixing channel used in the present application includes a primary air channel, which is arranged in a mixing zone behind the primary air channel; a necking zone is arranged at the connection between the air channel and the mixing zone, and the necking zone is arranged with a primary hydrogen channel and a silicon halide channel, wherein the primary hydrogen channel and the silicon halide channel share the same outlet. The primary hydrogen, primary air and silicon halide can be fully mixed by the device, so that the silicon halide can fully react with the combustion products of hydrogen and air, thereby increasing the yield of gas phase white carbon black. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the device used in the method for producing fumed silica in this application;

[0017] Figure 2 for Figure 1 Enlarged image at a;

[0018] Figure 3 Schematic diagram of the main raw material mixing channel used in Comparative Examples 1 and 2

[0019] Description of reference numerals:

[0020] 1. Main raw material mixing channel; 11. Primary air channel; 12. Silicon halide channel; 13. Primary hydrogen channel; 111. Neck shrinkage zone; 112. Mixing zone; 113. Spoiler;

[0021] 2. Combustion furnace;

[0022] 3. Burner nozzle; 31. Main channel; 32. Secondary hydrogen channel; 33. Secondary air channel; DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] like Figure 1~2An embodiment of the method for producing fumed silica of the present application is illustrated, the method comprising:

[0025] Silicon halide is introduced into the silicon halide channel 12 of the main raw material mixing channel 1 at a rate of 220kg / h~260kg / h, and primary hydrogen is introduced into the silicon halide channel 12 of the main raw material mixing channel 1 at a rate of 220m 3 / h~260m 3 / h into the primary hydrogen channel 13 of the main raw material mixing channel, and the air is heated at 700Nm 3 / h~900Nm 3 / h is passed into the primary air channel 11 of the main raw material mixing channel, and then fully mixed in the main raw material mixing channel 1 to form a main mixed gas, which is passed into the main channel 31 of the burner nozzle 3, and the pressure of the main channel 31 is controlled to be 25kPa±2kPa, and the temperature is 100℃±3℃. The above-mentioned silicon halide can be at least one of SiCl4, SiHCl3, and CH3SiCl3.

[0026] The secondary hydrogen is adjusted to 22 Nm 3 / h~26Nm 3 / h into the secondary hydrogen channel 32 of the burner nozzle 3, and control the pressure of the secondary hydrogen channel 32 to be 130kPa~150kPa and the temperature to be 25℃±2℃;

[0027] The secondary air is adjusted to 400Nm 3 / h rate into the secondary air channel 33 of the burner nozzle 3, and the pressure of the secondary air channel 33 is controlled to be 40kPa±2kPa and the temperature is controlled to be 100℃±3℃;

[0028] The secondary hydrogen channel 32 surrounds the outer side of the main channel 31, and the secondary air channel 33 surrounds the outer side of the secondary hydrogen channel 32;

[0029] The main mixed gas, secondary hydrogen and secondary air are burned at the burner nozzle to form gas phase white carbon black.

[0030] like Figure 1~2 In the above method, the main raw material mixing channel 1 comprises:

[0031] A primary air channel 11 is arranged in a mixing zone 112 behind the primary air channel 11; a necking zone 111 is arranged at the connection between the air channel 11 and the mixing zone 112, and a primary hydrogen channel 13 and a silicon halide channel 12 are arranged in the necking zone, wherein the primary hydrogen channel 13 and the silicon halide channel 12 share the same outlet. The mixing zone 112 is also provided with a plurality of interfering flow plates 113. The diameter of the main channel 31 of the burner nozzle 3 is 80 mm. The width of the secondary hydrogen channel 32 is 10 mm, and the width of the secondary air channel 33 is 10 mm. In a preferred embodiment, in the main raw material mixing channel 1, the rate of silicon halide introduced into the silicon halide channel 12 is 240 kg / h, and the rate of hydrogen introduced into the primary hydrogen channel 13 is 240 m / h. 3 / h, the air velocity in the primary air channel 11 is 800Nm 3 / h; in the burner nozzle 3, the rate of hydrogen introduced into the secondary hydrogen channel 32 is 24Nm 3 / h, the velocity of the secondary air introduced into the secondary air channel 33 is 400Nm 3 / h.

[0032] According to the implementation method provided by the present application, some specific experiments have been conducted on the present application, that is, the examples of preparing fumed silica using the fumed silica production method provided by the present application, and on this basis, some comparative examples are given. From these examples and comparative examples, it can be seen that the scheme provided by the present application has achieved good results. It should be noted that the following examples are only used to explain the present application in detail and do not limit the scope of protection of the invention in any way.

[0033] In the following embodiments and comparative examples, the parameters of the burner nozzle 3 and the main raw material mixing channel 1 used are as follows:

[0034] In the burner nozzle 3, the diameter of the main channel 31 is 80 mm, the cavity width of the secondary hydrogen channel 32 is 8 mm, and the cavity width of the secondary air channel 33 is 8 mm.

[0035] In the main raw material mixing channel 1, the diameter of the primary air channel 11 is 80 mm, the diameter of the primary air channel 11 is 8 mm, the diameter of the silicon halide channel 12 is 20 mm, the diameter of the necking zone 111 is 40 mm, and the diameter of the mixing zone 112 is 80 mm.

[0036] It should be noted that in order to maintain the temperature in each channel at a specific temperature, a thermal insulation interlayer is provided on each channel.

[0037] According to the parameters of the burner nozzle 3 and the main raw material mixing channel 1, specific embodiments and comparative examples are given below.

[0038] Embodiment 1:

[0039] SiCl4 is introduced into the SiCl4 channel 12 of the main raw material mixing channel 1 at a rate of 240 kg / h, and primary hydrogen is introduced into the SiCl4 channel 12 of the main raw material mixing channel 1 at a rate of 240 m 3 / h into the primary hydrogen channel 13 of the main raw material mixing channel, and the air is heated at 800Nm 3 / h is introduced into the primary air channel 11 of the main raw material mixing channel, and then fully mixed in the main raw material mixing channel 1 to form a main mixed gas, which is introduced into the main channel 31 of the burner nozzle 3, and the pressure of the main channel 31 is controlled to be 25kPa±2kPa and the temperature is 100℃±3℃;

[0040] The secondary hydrogen is heated to 24 Nm 3 / h into the secondary hydrogen channel 32 of the burner nozzle 3, and control the pressure of the secondary hydrogen channel 32 to be 140kPa±2kPa and the temperature to be 25℃±2℃;

[0041] The secondary air is adjusted to 400Nm 3 / h rate into the secondary air channel 33 of the burner nozzle 3, and the pressure of the secondary air channel 33 is controlled to be 40kPa±2kPa and the temperature is controlled to be 100℃±3℃;

[0042] The secondary hydrogen channel 32 surrounds the outer side of the main channel 31, and the secondary air channel 33 surrounds the outer side of the secondary hydrogen channel 32;

[0043] The main mixed gas, secondary hydrogen and secondary air are burned at the burner nozzle to form gas phase white carbon black.

[0044] Embodiment 2-3

[0045] The difference between Examples 2-3 and Example 1 is that the control parameters of each material are different from those of Example 1. The specific control parameters of each step are shown in Table 1.

[0046] Example 4

[0047] The difference between Example 4 and Example 1 is that a mixture of SiCl4 and SiHCl3 is introduced into the SiCl4 channel 12, wherein the introduction rate of SiCl4 is 120 kg / h, and the introduction rate of SiHCl3 is 120 kg / h, and the rest is the same as Example 1. The specific control parameters of each step are shown in Table 1.

[0048] Comparative Example 1

[0049] The difference between Comparative Example 1 and Example 1 is that primary air, primary hydrogen and SiCl4 are introduced into a common pipeline for natural mixing. Figure 3There is no necking area or mixing area in the pipeline, and the rest is the same as in Example 1. The specific control parameters of each step are shown in Table 1.

[0050] Comparative Example 2

[0051] The difference between Comparative Example 2 and Example 4 is that the primary air, primary hydrogen, SiCl4 and SiHCl3 are introduced into a common pipeline for natural mixing, such as Figure 3 , wherein the feeding rate of SiCl4 is 120kg / h, the feeding rate of SiHCl3 is 120kg / h, and the others are the same as in Example 1. The specific control parameters of each step are shown in Table 1.

[0052] Table 1 Reaction control conditions of various embodiments and comparative examples

[0053]

[0054] The fumed silica obtained in Examples 1 to 4 and Comparative Examples 1 to 2 was subjected to pH value detection, SiO2 content measurement and hourly production measurement. The results are shown in Table 2.

[0055] Table 2 White carbon black products obtained in various examples and comparative examples

[0056]

[0057] It can be seen from Example 1 and Comparative Example 1 that the white carbon black obtained in Example 1 has a higher yield, a higher SiO2 content in the white carbon black, and a higher pH value of the obtained white carbon black. It is presumed that the reason is that Example 1 uses the main pipeline provided by the present application, which enables the primary hydrogen, the primary air, and SiCl4 to be fully mixed, so that during the combustion of the burner, SiCl4 can fully react with the water and oxygen generated during the combustion process to obtain SiO2.

[0058] It can be seen from Example 4 and Comparative Example 2 that the white carbon black obtained in Example 4 has a higher yield, a higher SiO2 content in the white carbon black, and a higher pH value of the obtained white carbon black, which indicates that sufficient mixing of the main raw materials is beneficial to increasing the yield of white carbon black.

[0059] It can be seen from Example 1 and Comparative Example 1 that the pH of Example 1 is higher. It is presumed that the reason is that the heat release during the reaction of SiCl4 and water to generate SiO2 is small, so that the generated HCl can evaporate quickly and separate from SiO2.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing fumed silica, characterized in that: include: The silicon halide is introduced into the silicon halide channel (12) of the main raw material mixing channel (1) at a rate of 220 kg / h to 260 kg / h, and the primary hydrogen is introduced into the silicon halide channel (12) of the main raw material mixing channel (1) at a rate of 220 kg / h to 260 kg / h. 3 / h~260m 3 / h into the primary hydrogen channel (13) of the main raw material mixing channel, and the air is blown at 700Nm 3 / h~900Nm 3 / h is introduced into the primary air channel (11) of the main raw material mixing channel, and then fully mixed in the main raw material mixing channel (1) to form a main mixed gas, which is then introduced into the main channel (31) of the burner nozzle (3), and the pressure of the main channel (31) is controlled to be 25 kPa±2 kPa and the temperature to be 100°C±3°C; The secondary hydrogen is heated to 22 Nm 3 / h~26Nm 3 / h into the secondary hydrogen channel (32) of the burner nozzle (3), and the pressure of the secondary hydrogen channel (32) is controlled to be 130 kPa~150 kPa and the temperature to be 25°C±2°C; The secondary air is adjusted to 380 Nm 3 / h~420Nm 3 / h into the secondary air passage (33) of the burner nozzle (3), and the pressure of the secondary air passage (33) is controlled to be 40 kPa±2 kPa and the temperature to be 100°C±3°C; The secondary hydrogen channel (32) surrounds the outside of the main channel (31), and the secondary air channel (33) surrounds the outside of the secondary hydrogen channel (32); The main mixed gas, secondary hydrogen and secondary air are burned at a burner nozzle to form gas phase white carbon black; The main raw material mixing channel (1) comprises: A primary air channel (11) is arranged in a mixing zone (112) behind the primary air channel (11); a necking zone (111) is arranged at the connection between the primary air channel (11) and the mixing zone (112), and a primary hydrogen channel (13) and a silicon halide channel (12) are arranged in the necking zone, wherein the primary hydrogen channel (13) and the silicon halide channel (12) share the same outlet.

2. The method for producing fumed silica according to claim 1, characterized in that: The mixing zone (112) is further provided with a flow disturbance plate (113).

3. The method for producing fumed silica according to claim 1, characterized in that: The diameter of the main channel (31) of the burner nozzle (3) is 80 mm.

4. The method for producing fumed silica according to claim 1, characterized in that: The width of the secondary hydrogen channel (32) is 8 mm, and the width of the secondary air channel (33) is 8 mm.

5. The method for producing fumed silica according to claim 1, characterized in that: In the main raw material mixing channel (1), the rate of silicon halide introduced into the silicon halide channel (12) is 240 kg / h, and the rate of hydrogen introduced into the primary hydrogen channel (13) is 240 m / h. 3 / h, the air velocity in the primary air channel (11) is 800Nm 3 / h; In the burner nozzle (3), the rate of hydrogen introduced into the secondary hydrogen channel (32) is 24Nm 3 / h, the secondary air velocity introduced into the secondary air channel (33) is 400Nm 3 / h.

6. The method for producing fumed silica according to claim 1, characterized in that: The silicon halide is at least one of SiCl4, SiHCl3, and CH3SiCl3.

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