CN117682528A - Process and device for producing silicon dioxide - Google Patents
Process and device for producing silicon dioxide Download PDFInfo
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- CN117682528A CN117682528A CN202311732091.3A CN202311732091A CN117682528A CN 117682528 A CN117682528 A CN 117682528A CN 202311732091 A CN202311732091 A CN 202311732091A CN 117682528 A CN117682528 A CN 117682528A
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- silicon dioxide
- sulfuric acid
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- aqueous solution
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 310
- 239000000377 silicon dioxide Substances 0.000 title claims abstract description 153
- 235000012239 silicon dioxide Nutrition 0.000 title claims abstract description 115
- 238000000034 method Methods 0.000 title claims abstract description 40
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims abstract description 126
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 192
- 238000006243 chemical reaction Methods 0.000 claims description 112
- 239000007864 aqueous solution Substances 0.000 claims description 69
- 239000004111 Potassium silicate Substances 0.000 claims description 59
- 235000019353 potassium silicate Nutrition 0.000 claims description 59
- 229910052913 potassium silicate Inorganic materials 0.000 claims description 59
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 claims description 58
- 239000000243 solution Substances 0.000 claims description 57
- 238000003860 storage Methods 0.000 claims description 51
- 239000000047 product Substances 0.000 claims description 40
- 239000007788 liquid Substances 0.000 claims description 36
- 230000003068 static effect Effects 0.000 claims description 21
- 238000001816 cooling Methods 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 14
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 14
- 235000011151 potassium sulphates Nutrition 0.000 claims description 14
- 238000006386 neutralization reaction Methods 0.000 claims description 13
- 239000006227 byproduct Substances 0.000 claims description 9
- 239000012295 chemical reaction liquid Substances 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 8
- 239000012530 fluid Substances 0.000 claims description 6
- 239000002244 precipitate Substances 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 3
- 239000012043 crude product Substances 0.000 claims 1
- 238000010521 absorption reaction Methods 0.000 abstract description 9
- 239000003921 oil Substances 0.000 abstract description 9
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 abstract description 4
- 239000004115 Sodium Silicate Substances 0.000 abstract description 3
- 150000003839 salts Chemical class 0.000 abstract description 3
- 229910052911 sodium silicate Inorganic materials 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 3
- 239000002699 waste material Substances 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 abstract description 2
- 239000013078 crystal Substances 0.000 description 32
- 239000002245 particle Substances 0.000 description 15
- 238000007599 discharging Methods 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000002253 acid Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000005119 centrifugation Methods 0.000 description 5
- 239000006179 pH buffering agent Substances 0.000 description 5
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 5
- 238000005054 agglomeration Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 4
- 230000008025 crystallization Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- FWFGVMYFCODZRD-UHFFFAOYSA-N oxidanium;hydrogen sulfate Chemical compound O.OS(O)(=O)=O FWFGVMYFCODZRD-UHFFFAOYSA-N 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- JTNCEQNHURODLX-UHFFFAOYSA-N 2-phenylethanimidamide Chemical compound NC(=N)CC1=CC=CC=C1 JTNCEQNHURODLX-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- CXZMFTCPWAVKQA-UHFFFAOYSA-N [Si](=O)=O.S(O)(O)(=O)=O Chemical compound [Si](=O)=O.S(O)(O)(=O)=O CXZMFTCPWAVKQA-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910021485 fumed silica Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 229910000343 potassium bisulfate Inorganic materials 0.000 description 1
- CHWRSCGUEQEHOH-UHFFFAOYSA-N potassium oxide Chemical compound [O-2].[K+].[K+] CHWRSCGUEQEHOH-UHFFFAOYSA-N 0.000 description 1
- 229910001950 potassium oxide Inorganic materials 0.000 description 1
- LUMVCLJFHCTMCV-UHFFFAOYSA-M potassium;hydroxide;hydrate Chemical compound O.[OH-].[K+] LUMVCLJFHCTMCV-UHFFFAOYSA-M 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Landscapes
- Silicon Compounds (AREA)
Abstract
The invention discloses a process and a device for producing silicon dioxide, which belong to the technical field of chemical equipment, and continuously produce high oil absorption value silicon dioxide by taking crude silicon dioxide and potassium hydroxide as raw materials, and solve the problems of high waste salt, large equipment quantity, large occupied area and unstable product indexes of the existing process for intermittently producing silicon dioxide by using sodium silicate.
Description
Technical Field
The invention belongs to the technical field of chemical equipment, and particularly relates to a process and a device for producing silicon dioxide.
Background
Silica is a generic term for white powder X-ray amorphous silicic acid and silicate products, mainly referring to precipitated silica, fumed silica, ultrafine silica gel, etc., and is widely used for manufacturing glass, quartz glass, optical fibers, important parts of the electronic industry, optical instruments, handicrafts, and refractory materials.
The existing process for producing silicon dioxide is intermittent production by using sodium silicate and sulfuric acid kettle, and has the following technical difficulties: 1. the performance indexes such as purity, particle size, specific surface area, oil absorption value and the like of the silicon dioxide product are greatly affected by the conditions such as reaction temperature, seed crystal, pH and the like, and the condition consistency of each batch cannot be ensured in intermittent production, so that the problem of large performance fluctuation of the silicon dioxide product exists; 2. the sodium sulfate-containing wastewater is produced by utilizing the reaction of sodium silicate and sulfuric acid, so that on one hand, the raw material utilization rate is low, the cost is increased, and on the other hand, the environmental pollution is large, and along with the increasing environmental protection requirements, the risk of elimination is faced.
Disclosure of Invention
In order to solve the above problems, an object of the present invention is to provide a process and apparatus for producing silica.
The invention aims to achieve the aim, and the aim is achieved by the following technical scheme:
a process for producing silica comprising the steps of:
1) Storing pure water in a first storage tank, a second storage tank storing sulfuric acid solution, and a third storage tank storing hydrogen
An aqueous potassium oxide solution;
the mass fraction of the sulfuric acid solution is 60-90%, and the mass fraction of the potassium hydroxide aqueous solution is 20-48%;
2) Opening a bottom discharging valve of the third storage tank, and controlling the bottom discharging valve through interlocking of a flowmeter and the valve to enable potassium hydroxide aqueous solution to enter a potassium silicate reaction kettle; then, a bottom discharge valve of a crude silicon dioxide bin is opened, so that crude silicon dioxide enters a potassium silicate reaction kettle, and the temperature of the potassium silicate reaction kettle is controlled to be 40-60 ℃ to obtain potassium silicate reaction liquid;
the feeding mass ratio of the potassium hydroxide aqueous solution to the crude silicon dioxide is 1: 3.5-21;
3) Opening a discharging valve at the bottom of the potassium silicate reaction kettle, allowing potassium silicate reaction liquid to enter a potassium silicate curing kettle from the bottom, controlling the temperature of the potassium silicate curing kettle to be 40-60 ℃, continuously curing for 0.5-3 h, and obtaining curing liquid after curing reaction is finished;
4) Opening discharge valves at the bottoms of the pure water first storage tank and the sulfuric acid solution second storage tank, enabling the pure water first storage tank and the sulfuric acid solution second storage tank to be distributed into 3 strands of sulfuric acid water solutions with different mass fractions through interlocking control of a flowmeter and the valves, enabling the sulfuric acid water solutions to enter a static mixer for full mixing, and controlling the temperature of the static mixer to be 40-60 ℃; the mass fraction of the 1 st strand of sulfuric acid aqueous solution is 2-4%, the mass fraction of the 2 nd strand of sulfuric acid aqueous solution is 8-12%, and the mass fraction of the 3 rd strand of sulfuric acid aqueous solution is 15-28%; the feeding amount of the 1 st sulfuric acid aqueous solution is 1-2% of the total feeding amount of potassium hydroxide and silicon dioxide, the feeding amount of the 2 nd sulfuric acid aqueous solution is 93-95% of the total feeding amount of potassium hydroxide and silicon dioxide, and the feeding amount of the 3 rd sulfuric acid aqueous solution is 3-6% of the total feeding amount of potassium hydroxide and silicon dioxide;
5) Respectively introducing the curing liquid obtained in the step 3) and 3 strands of sulfuric acid aqueous solution with different mass fractions obtained in the step 4) into a silicon dioxide reaction tower for neutralization reaction, controlling the temperature of the silicon dioxide reaction tower to be 40-60 ℃, and controlling the pH value of the neutralized solution to be 4-6 by adjusting the feeding quantity of the 3 strands of sulfuric acid aqueous solution with different mass fractions;
6) After neutralization reaction is carried out for 0.5-1 h, silicon dioxide feed liquid is obtained, a discharge valve at the bottom of a silicon dioxide reaction tower and a feed and discharge valve of a delivery pump are opened, the obtained silicon dioxide feed liquid is separated into a first flow feed liquid and a second flow feed liquid through interlocking control of a flowmeter and the valves, wherein the first flow feed liquid returns to the silicon dioxide reaction tower to play a role of a pH buffering agent and a seed crystal;
the mass of the first flow material liquid is 10-20% of the total mass of the silicon dioxide material liquid;
7) Introducing the second fluid material liquid obtained in the step 6) into a cooling curing kettle, controlling the temperature of the cooling curing kettle to be 10-20 ℃ and the curing time to be 0.5-5 h, and obtaining a mixed product after curing is completed;
8) And (3) introducing the mixed product obtained in the step (7) into a centrifugal machine for centrifugation, wherein the obtained centrifugate is a byproduct potassium sulfate solution, and drying the obtained precipitate to obtain the product silicon dioxide.
The silica reaction tower adopts a mode of feeding with different sulfuric acid concentration gradients, thereby solving the problem of avoiding agglomeration of silica crystals of the product. The agglomeration among crystals in the crystallization process is a main reason for unstable particle size of a silicon dioxide product, and the invention aims to solve the problem of crystal agglomeration in the synthesis process and creatively adopts a method of adjusting the acidity of a reaction system in a gradient manner to realize the depolymerization behavior of particle agglomerates. By setting different mass fractions of sulfuric acid, the acid-base neutralization reaction intensity in the reaction system is greatly different, the reaction system with high reaction intensity is favorable for depolymerizing the agglomerates, and the particle size of the product is small. This is because the sulfuric acid having a local concentration exceeding that of sulfuric acid has solubility for silica, and the silica having a lower crystallinity at the bond points is dissolved easily because the "bond points" in the middle of the agglomerates are dissolved preferentially in the dissolution process, and the agglomerates of large particles are dispersed into a plurality of small particles having a uniform particle diameter after the "bond points" are dissolved.
According to the invention, the silica crystals are contained in the first flow material liquid in the discharge pipeline of the silica reaction tower and returned to the reaction tower, so that the silica crystals play a role in seed crystal, and are combined with the 1 st strand sulfuric acid aqueous solution, so that the effect of activating the seed crystal by acid etching is achieved, and the problems of uneven particle size distribution, low specific surface area and low oil absorption value of the product are effectively solved. The seed crystal is a key factor for inducing the crystallization and growth of the product in the crystallization process, and the activity and the size of the seed crystal directly determine the number and the size of crystal nuclei in the silica crystallization process, thereby influencing the final particle size of the product. Untreated silica particles have a high degree of crystallinity on the crystal surface, a low surface energy on the crystal, and a low activity in inducing crystal growth, and it is difficult to provide active sites for continued crystal growth. According to the invention, through the silicon dioxide-sulfuric acid solution, the surface of the silicon dioxide crystal is subjected to acid etching to become 'rugged', namely crystal defects are generated. The surface energy of the defect position of the crystal is higher, a large number of unstable chemical bonds exist, and the crystal can be used as an active site for continuous growth of the crystal, so that the crystal has a very good induction function in the later crystal growth process, and the problems of nonuniform particle size distribution and poor micro morphology of the product are solved.
In the invention, the potassium sulfate solution is contained in the first flow material liquid in the discharge pipeline of the silicon dioxide reaction tower and returns to the reaction tower, thereby playing a role in buffering pH and reducing the content of byproduct crude silicic acid. The potassium silicate feed liquid is directly contacted with sulfuric acid, so that a reaction of preparing weak acid from strong acid can be generated, and orthosilicic acid is generated. Returning the first flow material liquid containing potassium sulfate to the reaction tower, the potassium sulfate reacts with sulfuric acid to produce potassium bisulfate, thereby playing a role in buffering pH value and reducing the local H of the material liquid + The concentration reduces the generation probability of the orthosilicic acid.
Preferably, in the step 1), the mass fraction of the sulfuric acid solution is 70-80%, and the mass fraction of the potassium hydroxide aqueous solution is 40-48%.
Preferably, in the step 3), the temperature of the potassium silicate curing kettle is controlled to be 50-55 ℃.
Preferably, in the step 4), the temperature of the static mixer is controlled to be 50-55 ℃, wherein the mass fraction of the 1 st strand of sulfuric acid aqueous solution is 2-3%, the mass fraction of the 2 nd strand of sulfuric acid aqueous solution is 8-10%, and the mass fraction of the 3 rd strand of sulfuric acid aqueous solution is 15-20%.
Preferably, in the step 5), the temperature of the silica reaction tower is controlled to be 50-55 ℃, and the pH of the neutralized solution is controlled to be 5-6.
Preferably, in the step 7), the temperature of the curing kettle is controlled to be 10-15 ℃.
The process for producing the silicon dioxide is realized by the following devices:
the bottom of the third storage tank is connected with the upper part of the potassium silicate reaction kettle through a pipeline d, the crude silicon dioxide bin is connected with the upper part of the potassium silicate reaction kettle through a hose e, the bottom of the potassium silicate reaction kettle is connected with the bottom of the potassium silicate curing kettle through a pipeline f, the potassium silicate curing kettle is connected with the top of the silicon dioxide reaction kettle through a pipeline g, the bottom of the first storage tank is connected with one end of 3 static mixers through a pipeline a1-3 respectively, the bottom of the second storage tank is connected with the side parts of the static mixers through a pipeline n1-3 respectively, the other end of the 3 static mixers is connected with the side parts of the silicon dioxide reaction kettle through a pipeline c1-3 respectively, the bottom of the silicon dioxide reaction kettle is connected with a feed inlet of a conveying pump through a pipeline h, a discharge outlet of the conveying pump is connected with the top side sections of the silicon dioxide reaction kettle and the bottom of the cooling curing kettle respectively through a pipeline i and a pipeline b, the bottom of the cooling curing kettle is connected with a centrifugal machine through a pipeline k, and the side parts of the centrifugal machine are connected with the product potassium sulfate solution storage tank through a pipeline m.
The silica reaction device adopts a continuous tower reactor, solves the problem of control difference of each batch of reaction conditions of the batch reactor, and ensures the stability of product performance.
The stirring mode of the silica reaction tower adopts a paddle type equiradial flow stirring mode, so that the reaction feed liquid flows in a plug flow mode, and the feed liquid is ensured to react in a certain pH gradient.
The pipeline a1-3, the pipeline n1-3, the pipeline d and the pipeline j are provided with volume flowmeter and controllers, the pipeline e is provided with a rotary valve for controlling solid feeding rate, and each pipeline is provided with a valve and a pump.
Compared with the prior art, the invention has the following advantages:
(1) The process for producing silicon dioxide shortens the production period, saves the time of intermittent reaction and dumping, greatly improves the utilization rate of equipment, and mainly stabilizes the process operation condition so as to stabilize the performance index of the product.
(2) The process for producing the silicon dioxide fundamentally solves the problems of large amount of sodium sulfate wastewater and waste salt generated in the traditional process for preparing the silicon dioxide by using the water glass, reduces the cost by 30-50%, and has the beneficial effects on environmental protection.
(3) The invention adopts the silica reaction tower to carry out continuous reaction, (1) the method benefits from the adoption of the gradient feeding mode of sulfuric acid solutions with different mass fractions in the reaction process, thereby not only ensuring the index of large specific surface area and high oil absorption value of the product silica, but also solving the problem of agglomeration of the product silica crystals; (2) the method has the advantages that the silicon dioxide crystals are contained in the first flow material liquid in the discharge pipeline of the silicon dioxide reaction tower in the reaction process and returned to the reaction tower, so that the effect of the seed crystal is achieved, the seed crystal is combined with the first flow of sulfuric acid aqueous solution, the effect of activating the seed crystal by acid etching is achieved, and the problems of uneven particle size distribution, low specific surface area and low oil absorption value of the product are effectively solved; (3) the method is beneficial to the way that the potassium sulfate solution is contained in the first flow material liquid in the discharge pipeline of the silicon dioxide reaction tower in the reaction process and returns to the reaction tower, so that the effect of buffering pH is achieved, and the content of the byproduct ortho-silicic acid is reduced.
(4) The process for producing the silicon dioxide and potassium sulfate solution has higher automation degree, reduces personnel operation, reduces the contact frequency of personnel and materials, reduces labor cost, improves safety coefficient, greatly reduces the production amount of waste water and waste salt from the process, and reduces production cost by-products of recoverable potassium sulfate.
Drawings
FIG. 1 is a schematic view of a process plant for producing silica according to the present invention;
in the figure, 1-a first tank 1; 2-a second tank 2; 3-a third tank 3; 4-a crude silicon dioxide bin; 5-potassium silicate reaction kettle; 6-a potassium silicate curing kettle; 7-a static mixer; 8-a silica reaction tower; 9-a delivery pump; 10-cooling and curing the kettle; 11-a centrifuge; 12-product potassium sulfate solution storage tank.
Detailed Description
The foregoing is further elaborated by the following description of embodiments of the present invention, which are given by way of example only, and should not be construed as limiting the scope of the present invention. All techniques implemented based on the above description of the invention are within the scope of the invention.
Example 1
As shown in FIG. 1, the bottom of the third storage tank 3 is connected with the upper part of the potassium silicate reaction kettle 5 through a pipeline d, the crude silica silo 4 is connected with the upper part of the potassium silicate reaction kettle 5 through a hose e, the bottom of the potassium silicate reaction kettle 5 is connected with the bottom of the potassium silicate curing kettle 6 through a pipeline f, the potassium silicate curing kettle 6 is connected with the top of the silica reaction kettle 8 through a pipeline g, the bottom of the first storage tank 1 is connected with one end of 3 static mixers 7 through pipelines a1-3 respectively, the bottom of the second storage tank 2 is connected with the side part of the static mixers 7 through pipelines n1-3 respectively, the other end of 3 static mixers 7 is connected with the side part of the silica reaction kettle 8 through pipelines c1-3 respectively, the bottom of the silica reaction kettle 8 is connected with a feed inlet of a conveying pump 9 through a pipeline h, a discharge outlet of the conveying pump 9 is connected with the side part of the top of the silica reaction kettle 8 and the bottom of a cooling curing kettle 10 through a pipeline i and a pipeline b respectively, the bottom of the cooling kettle 10 is connected with 11 through a pipeline k, the side part of the centrifuge 11 is connected with a product sulfuric acid solution 12 through a pipeline m.
The stirring mode of the silicon dioxide reaction tower 8 adopts a paddle type radial flow stirring mode, so that the reaction feed liquid flows in a plug flow mode, and the feed liquid is ensured to react in a certain pH gradient.
The pipeline a1-3, the pipeline n1-3, the pipeline d and the pipeline j are provided with volume flowmeter and controllers, the pipeline e is provided with a rotary valve for controlling solid feeding rate, and each pipeline is provided with a valve and a pump.
Example 2
The first storage tank stores pure water, the second storage tank stores sulfuric acid solution with the mass fraction of 90%, and the third storage tank stores potassium hydroxide aqueous solution with the mass fraction of 20%; opening a bottom discharge valve of a third storage tank of the potassium hydroxide aqueous solution, and enabling the potassium hydroxide aqueous solution to enter a potassium silicate reaction kettle through interlocking control of a flowmeter and the valve; then the bottom discharge valve of the crude silicon dioxide bin is opened, a rotary valve is arranged at the bottom, so that the crude silicon dioxide enters a potassium silicate reaction kettle, the temperature of the potassium silicate reaction kettle is controlled to be 60 ℃, and the feeding mass ratio of the potassium hydroxide aqueous solution to the crude silicon dioxide is 1:21, a step of; opening a discharging valve at the bottom of the potassium silicate reaction kettle, and allowing potassium silicate reaction liquid to enter a potassium silicate curing kettle from the bottom, wherein the temperature of the curing kettle is controlled to be 60 ℃; continuously curing for 3 hours, opening discharge valves at the bottoms of the pure water first storage tank and the sulfuric acid second storage tank, and distributing the pure water first storage tank and the sulfuric acid second storage tank into 3 sulfur with different mass fractions through interlocking control of a flowmeter and the valvesThe acid solution enters a static mixer for full mixing, the temperature of the static mixer is controlled to be 60 ℃, wherein the mass fraction of the 1 st sulfuric acid solution is 4%, the mass fraction of the 2 nd sulfuric acid solution is 12%, and the mass fraction of the 3 rd sulfuric acid solution is 28%; the feeding amount of the 1 st strand of sulfuric acid aqueous solution is 1% of the total feeding amount of potassium hydroxide and silicon dioxide, the feeding amount of the 2 nd strand of sulfuric acid aqueous solution is 93% of the total feeding amount of potassium hydroxide and silicon dioxide, and the feeding amount of the 3 rd strand of sulfuric acid aqueous solution is 3% of the total feeding amount of potassium hydroxide and silicon dioxide; after the curing reaction is finished, the curing liquid overflows from a potassium silicate curing kettle to enter a silicon dioxide reaction tower, and is subjected to gradient neutralization reaction with sulfuric acid aqueous solutions with different mass fractions in the silicon dioxide reaction tower, the temperature of the silicon dioxide reaction tower is controlled to be 60 ℃, and the pH value of the neutralized solution is controlled to be 6 by adjusting the feeding amount of the sulfuric acid aqueous solution; after the neutralization reaction is carried out for 1h, separating out a silicon dioxide product, opening a discharge valve at the bottom of a silicon dioxide reaction tower and a feeding and discharging valve of a conveying pump after the silicon dioxide reaction is finished, and carrying out interlocking control through a flowmeter and the valve to divide the silicon dioxide reaction tower into 2 pipelines with different mass flow rates, wherein a first flow rate returns to the silicon dioxide layering tower to play a role of a pH buffering agent and a seed crystal, and the mass fraction of the first flow rate accounts for 20% of the total flow rate; the second fluid material enters a cooling curing kettle from the bottom, the temperature of the curing kettle is controlled to be 20 ℃, and the curing time is 5 hours; after the products are uniformly mixed in a cooling curing kettle, the products are put into a centrifugal machine for centrifugation, the obtained centrifugate is a byproduct potassium sulfate solution, the obtained precipitate is dried, 5.6kg of silicon dioxide is obtained, the purity of the products is 99.19%, the average particle size is 46.38nm, the heating decrement is 5.37%, the burning decrement is 3.2%, and the specific surface area BET is 176m 2 /g, oil absorption 268, g/100g.
Example 3
The first storage tank stores pure water, the second storage tank stores sulfuric acid solution with the mass fraction of 60%, and the third storage tank stores potassium hydroxide with the mass fraction of 48%; opening a bottom discharge valve of a third storage tank of the potassium hydroxide aqueous solution, and enabling the potassium hydroxide aqueous solution to enter a potassium silicate reaction kettle through interlocking control of a flowmeter and the valve; then the bottom discharge valve of the crude silicon dioxide bin is opened, the bottom is provided with a rotary valve, so that the crude silicon dioxide enters a potassium silicate reaction kettle, and potassium silicate is controlledThe temperature of the reaction kettle is 40 ℃, and the feeding mass ratio of the potassium hydroxide aqueous solution to the crude silicon dioxide is 1:3.5; opening a discharging valve at the bottom of the potassium silicate reaction kettle, and allowing potassium silicate reaction liquid to enter a potassium silicate curing kettle from the bottom, wherein the temperature of the curing kettle is controlled to be 40 ℃; continuously curing for 0.5h, opening discharge valves at the bottoms of the pure water first storage tank and the sulfuric acid second storage tank, enabling the pure water first storage tank and the sulfuric acid second storage tank to be distributed into 3 strands of sulfuric acid solutions with different mass fractions through interlocking control of a flowmeter and the valves, enabling the sulfuric acid solutions to enter a static mixer for full mixing, controlling the temperature of the static mixer to be 40 ℃, wherein the mass fraction of the 1 st strand of sulfuric acid solution is 2%, the mass fraction of the 2 nd strand of sulfuric acid solution is 8%, and the mass fraction of the 3 rd strand of sulfuric acid solution is 15%; the feeding amount of the 1 st strand of sulfuric acid aqueous solution is 2% of the total feeding amount of potassium hydroxide and silicon dioxide, the feeding amount of the 2 nd strand of sulfuric acid aqueous solution is 95% of the total feeding amount of potassium hydroxide and silicon dioxide, and the feeding amount of the 3 rd strand of sulfuric acid aqueous solution is 6% of the total feeding amount of potassium hydroxide and silicon dioxide; after the curing reaction is finished, the curing liquid overflows from a potassium silicate curing kettle to enter a silicon dioxide reaction tower, and is subjected to gradient neutralization reaction with sulfuric acid aqueous solutions with different mass fractions in the silicon dioxide reaction tower, the temperature of the silicon dioxide reaction tower is controlled to be 40 ℃, and the pH value of the neutralized solution is controlled to be 4 by adjusting the feeding amount of the sulfuric acid aqueous solution; after the neutralization reaction is carried out for 0.5h, separating out a silicon dioxide product, opening a discharge valve at the bottom of a silicon dioxide reaction tower and a feeding and discharging valve of a conveying pump after the silicon dioxide reaction is finished, and carrying out interlocking control through a flowmeter and the valve to divide the silicon dioxide reaction tower into 2 pipelines with different mass flow rates, wherein a first flow returns to the silicon dioxide layering tower to play a role of a pH buffering agent and a seed crystal, and the flow rate of the first flow accounts for 10% of the mass fraction of the total flow rate; the second fluid material enters a cooling curing kettle from the bottom, the temperature of the curing kettle is controlled to be 10 ℃, and the curing time is 0.5h; after the products are uniformly mixed in a cooling curing kettle, the products are put into a centrifugal machine for centrifugation, the obtained centrifugate is a byproduct potassium sulfate solution, the obtained precipitate is dried, 5.5kg of silicon dioxide of the products is obtained, the purity of the products is 99.13%, the average particle size is 45.94nm, the heating decrement is 5.72%, the burning decrement is 3.5%, and the specific surface area BET is 174m 2 /g, oil absorption 264 g/100g.
Example 4
The first storage tank stores pure waterThe second storage tank stores 70% of sulfuric acid solution by mass fraction, and the third storage tank stores 40% of potassium hydroxide water-soluble by mass fraction; opening a bottom discharge valve of a third storage tank of the potassium hydroxide aqueous solution, and enabling the potassium hydroxide aqueous solution to enter a potassium silicate reaction kettle through interlocking control of a flowmeter and the valve; then the bottom discharge valve of the crude silicon dioxide bin is opened, a rotary valve is arranged at the bottom, so that the crude silicon dioxide enters a potassium silicate reaction kettle, the temperature of the potassium silicate reaction kettle is controlled to be 50 ℃, and the feeding mass ratio of the potassium hydroxide aqueous solution to the crude silicon dioxide is 1:15; opening a discharging valve at the bottom of the potassium silicate reaction kettle, and allowing potassium silicate reaction liquid to enter a potassium silicate curing kettle from the bottom, wherein the temperature of the curing kettle is controlled to be 50 ℃; continuously curing for 1.5h, opening discharge valves at the bottoms of the pure water first storage tank and the sulfuric acid second storage tank, enabling the pure water first storage tank and the sulfuric acid second storage tank to be distributed into 3 strands of sulfuric acid solutions with different mass fractions through interlocking control of a flowmeter and the valves, enabling the sulfuric acid solutions to enter a static mixer for full mixing, controlling the temperature of the static mixer to be 50 ℃, wherein the mass fraction of the 1 st strand of sulfuric acid solution is 2.5%, the mass fraction of the 2 nd strand of sulfuric acid solution is 9%, and the mass fraction of the 3 rd strand of sulfuric acid solution is 18%; the feeding amount of the 1 st strand of sulfuric acid aqueous solution is 1.2% of the total feeding amount of potassium hydroxide and silicon dioxide, the feeding amount of the 2 nd strand of sulfuric acid aqueous solution is 94% of the total feeding amount of potassium hydroxide and silicon dioxide, and the feeding amount of the 3 rd strand of sulfuric acid aqueous solution is 4% of the total feeding amount of potassium hydroxide and silicon dioxide; after the curing reaction is finished, the curing liquid overflows from a potassium silicate curing kettle to enter a silicon dioxide reaction tower, and is subjected to gradient neutralization reaction with sulfuric acid aqueous solutions with different mass fractions in the silicon dioxide reaction tower, the temperature of the silicon dioxide reaction tower is controlled to be 50 ℃, and the pH value of the neutralized solution is controlled to be 5 by adjusting the feeding amount of the sulfuric acid aqueous solution; after the neutralization reaction is carried out for 0.75h, separating out a silicon dioxide product, opening a discharge valve at the bottom of a silicon dioxide reaction tower and a feeding and discharging valve of a conveying pump after the silicon dioxide reaction is finished, and carrying out interlocking control through a flowmeter and the valve to divide the silicon dioxide reaction tower into 2 pipelines with different mass flow rates, wherein a first flow returns to the silicon dioxide layering tower to play a role of a pH buffering agent and a seed crystal, and the flow rate of the first flow accounts for 12% of the mass fraction of the total flow rate; the second fluid material enters a cooling curing kettle from the bottom, the temperature of the curing kettle is controlled to be 15 ℃, and the curing time is 2.5h;after the products are uniformly mixed in a cooling curing kettle, the products are put into a centrifugal machine for centrifugation, the obtained centrifugate is a byproduct potassium sulfate solution, the obtained precipitate is dried, and the products of 5.8kg of silicon dioxide, 99.25% of product purity, 46.55nm of average particle size, 5.12% of heating decrement, 3.05% of burning decrement and 178m of specific surface area BET are obtained 2 /g, oil absorption 272 g/100g.
Example 5
The first storage tank stores pure water, the second storage tank stores 80% of sulfuric acid solution by mass fraction, and the third storage tank stores 45% of potassium hydroxide water by mass fraction; opening a bottom discharge valve of a third storage tank of the potassium hydroxide aqueous solution, and enabling the potassium hydroxide aqueous solution to enter a potassium silicate reaction kettle through interlocking control of a flowmeter and the valve; then the bottom discharge valve of the crude silicon dioxide bin is opened, a rotary valve is arranged at the bottom, so that the crude silicon dioxide enters a potassium silicate reaction kettle, the temperature of the potassium silicate reaction kettle is controlled to be 55 ℃, and the feeding mass ratio of the potassium hydroxide aqueous solution to the crude silicon dioxide is 1:18; opening a discharging valve at the bottom of the potassium silicate reaction kettle, and allowing potassium silicate reaction liquid to enter a potassium silicate curing kettle from the bottom, wherein the temperature of the curing kettle is controlled to be 55 ℃; continuously curing for 2.5h, opening discharge valves at the bottoms of the pure water first storage tank and the sulfuric acid second storage tank, enabling the pure water first storage tank and the sulfuric acid second storage tank to be distributed into 3 strands of sulfuric acid solutions with different mass fractions through interlocking control of a flowmeter and the valves, enabling the sulfuric acid solutions to enter a static mixer for full mixing, controlling the temperature of the static mixer to be 55 ℃, wherein the mass fraction of the 1 st strand of sulfuric acid solution is 3%, the mass fraction of the 2 nd strand of sulfuric acid solution is 10%, and the mass fraction of the 3 rd strand of sulfuric acid solution is 20%; the feeding amount of the 1 st strand of sulfuric acid aqueous solution is 1.5% of the total feeding amount of potassium hydroxide and silicon dioxide, the feeding amount of the 2 nd strand of sulfuric acid aqueous solution is 94.5% of the total feeding amount of potassium hydroxide and silicon dioxide, and the feeding amount of the 3 rd strand of sulfuric acid aqueous solution is 5% of the total feeding amount of potassium hydroxide and silicon dioxide; after the curing reaction is finished, the curing liquid overflows from a potassium silicate curing kettle to enter a silicon dioxide reaction tower, and is subjected to gradient neutralization reaction with sulfuric acid aqueous solutions with different mass fractions in the silicon dioxide reaction tower, the temperature of the silicon dioxide reaction tower is controlled to be 55 ℃, and the pH value of the neutralized solution is controlled to be 5.5 by adjusting the feeding amount of the sulfuric acid aqueous solution; after 0.6h of neutralization reaction, separating out a silicon dioxide product, and ending the silicon dioxide reactionThen, opening a discharge valve at the bottom of the silica reaction tower and a feed-in and discharge valve of a delivery pump, and controlling the discharge valve and the valve in an interlocking manner through a flowmeter to divide the discharge valve into 2 pipelines with different mass flow rates, wherein a first flow rate returns to the silica layering tower to play a role of a pH buffering agent and a seed crystal, and the mass fraction of the flow rate of the first flow rate accounting for the total flow rate is 15%; the second fluid material enters a cooling curing kettle from the bottom, the temperature of the curing kettle is controlled to be 18 ℃, and the curing time is 4 hours; after the products are uniformly mixed in a cooling curing kettle, the products are put into a centrifugal machine for centrifugation, the obtained centrifugate is a byproduct potassium sulfate solution, the obtained precipitate is dried, 5.8kg of silicon dioxide is obtained, the purity of the products is 99.28%, the average particle diameter is 46.93nm, the heating decrement is 5.05%, the burning decrement is 2.9%, and the specific surface area BET is 181m 2 /g, oil absorption 275 g/100g.
While the foregoing describes the embodiments of the present invention, it is not intended to limit the scope of the present invention, and various modifications or variations may be made by those skilled in the art without the need for inventive effort on the basis of the technical solutions of the present invention.
Claims (9)
1. A process for producing silica, characterized by: the method comprises the following steps:
1) Introducing a potassium hydroxide aqueous solution and crude silicon dioxide into a potassium silicate reaction kettle, controlling the temperature of the potassium silicate reaction kettle to be 40-60 ℃ to obtain a potassium silicate reaction liquid, continuously curing the obtained potassium silicate reaction liquid for 0.3-3 h, and controlling the curing process temperature to be 40-60 ℃ to obtain a curing liquid;
the feeding mass ratio of the potassium hydroxide aqueous solution to the silicon dioxide is 1: 3.5-21;
2) Mixing pure water and sulfuric acid solution to obtain 3 strands of sulfuric acid aqueous solutions with different mass fractions, controlling the temperature to be 40-60 ℃ in the mixing process, and then introducing the obtained 3 strands of sulfuric acid aqueous solutions with different mass fractions and the curing liquid prepared in the step 1) into a silicon dioxide reaction tower for neutralization reaction, wherein the neutralization reaction is carried out for 0.5-1 h, so as to obtain silicon dioxide feed liquid;
3) And 2) dividing the silica feed liquid prepared in the step 2) into a first flow feed liquid and a second flow feed liquid, wherein the first flow feed liquid returns to the silica reaction tower, the second flow feed liquid is cooled and cured for 0.5-5 h at the temperature of 10-20 ℃, after curing, centrifuging, wherein the obtained centrifugate is a byproduct potassium sulfate solution, and the obtained precipitate is dried to obtain the product silica.
2. The process for producing silica according to claim 1, wherein: the mass fraction of the potassium hydroxide aqueous solution in the step 1) is 20-48%; the mass fraction of the sulfuric acid solution in the step 2) is 60-90%; and in the step 2), the temperature of the silica reaction tower is controlled to be 40-60 ℃.
3. The process for producing silica according to claim 1, wherein: the 3 strands of sulfuric acid aqueous solutions with different mass fractions in the step 2), wherein the mass fraction of the 1 st strand of sulfuric acid aqueous solution is 2-4%, the mass fraction of the 2 nd strand of sulfuric acid aqueous solution is 8-12%, and the mass fraction of the 3 rd strand of sulfuric acid aqueous solution is 15-28%; the mass of the 1 st strand of sulfuric acid aqueous solution is 1-2% of the total feeding amount of potassium hydroxide and silicon dioxide, the mass of the 2 nd strand of sulfuric acid aqueous solution is 93-95% of the total feeding amount of potassium hydroxide and silicon dioxide, and the feeding amount of the 3 rd strand of sulfuric acid aqueous solution is 3-6% of the mass of potassium hydroxide and silicon dioxide; and the pH value of the neutralized solution is controlled to be 4-6 by adjusting the feeding amount of 3 strands of sulfuric acid aqueous solution with different mass fractions.
4. The process for producing silica according to claim 1, wherein: the mass fraction of the potassium hydroxide aqueous solution in the step 1) is 40-48%, and the temperature of the curing process in the step 1) is controlled to be 50-55 ℃; the mass fraction of the sulfuric acid solution in the step 2) is 70-80%, and the temperature of the silica reaction tower in the step 2) is controlled to be 50-55 ℃.
5. The process for producing silica according to claim 1, wherein: in the step 2), the temperature in the mixing process is controlled to be 50-55 ℃, and 3 strands of sulfuric acid aqueous solutions with different mass fractions are adopted, wherein the mass fraction of the 1 st strand of sulfuric acid aqueous solution is 2-3%, the mass fraction of the 2 nd strand of sulfuric acid aqueous solution is 8-10%, and the mass fraction of the 3 rd strand of sulfuric acid aqueous solution is 15-20%; and the pH value of the neutralized solution is controlled to be 5-6 by adjusting the feeding amount of 3 strands of sulfuric acid aqueous solution with different mass fractions.
6. The process for producing silica according to claim 1, wherein: and 3) cooling and curing the second fluid material liquid at the temperature of 10-15 ℃.
7. The process for producing silica according to claim 1, wherein: the process for producing the silicon dioxide is realized by the following devices:
the bottom of the third storage tank (3) is connected with the upper part of the potassium silicate reaction kettle (5) through a pipeline d, the crude product silicon dioxide bin (4) is connected with the upper part of the potassium silicate reaction kettle (5) through a hose e, the bottom of the potassium silicate reaction kettle (5) is connected with the bottom of the potassium silicate curing kettle (6) through a pipeline f, the potassium silicate curing kettle (6) is connected with the top of the silicon dioxide reaction tower (8) through a pipeline g, the bottom of the first storage tank (1) is connected with one end of the 3 static mixers (7) through pipelines a1-3 respectively, the bottom of the second storage tank (2) is connected with the side part of the static mixers (7) through pipelines n1-3 respectively, the other end of the 3 static mixers (7) is connected with the side part of the silicon dioxide reaction tower (8) through a pipeline c1-3 respectively, the bottom of the silicon dioxide reaction tower (8) is connected with a feed inlet of a conveying pump (9) through a pipeline i and a pipeline b respectively, the discharge outlet of the conveying pump (9) is connected with the top side part of the silicon dioxide reaction tower (8) and the bottom of the curing kettle (10) through a pipeline b respectively, and the bottom of the cooling kettle (10) is connected with the bottom of the centrifuge (11) through a pipeline m) through a cooling pipeline (11).
8. The process for producing silica according to claim 7, wherein: the stirring mode of the silicon dioxide reaction tower (8) adopts a paddle type radial flow stirring mode, so that the reaction feed liquid flows in a plug flow mode, and the feed liquid is ensured to react in a certain pH gradient.
9. The process for producing silica according to claim 7, wherein: the pipeline a1-3, the pipeline n1-3, the pipeline d and the pipeline j are provided with volume flowmeter and controllers, the pipeline e is provided with a rotary valve for controlling solid feeding rate, and each pipeline is provided with a valve and a pump.
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