KR20070013664A - New proces for producing silica and fluorine compound from hexafluorosilicic acid - Google Patents

Abstract

A novel process for producing nanoporous silica and sodium fluoride using hexafluorosilicic acid and a sodium-containing compound, particularly sodium silicate, generated as a byproduct from a phosphate fertilizer plant or a phosphoric acid production process is provided to constantly control physical properties of nanoporous silica, to completely separate nanoporous silica from sodium fluoride, to obtain high purity sodium fluoride using a reverse osmosis membrane, and to substantially reduce energy consumption compared to an existing process. In the process for producing nanoporous silica and fluorine compound using hexafluorosilicic acid and sodium silicate, a process for producing nanoporous silica and fluorine compound using hexafluorosilicic acid as a starting material comprises: separating nanoporous silica hydrogel by quantitatively separating hexafluorosilicic acid and sodium silicate in the state that an eddy flow is formed in a high speed instantaneous reactor to which a pressure of 1 kg/cm^2 or more is applied by a quantitative pump such that 20 to 25% hexafluorosilicic acid and 15 to 18% sodium silicate are controlled by an equivalent ratio in the adjusted pH range; passing the remaining sodium fluoride through a first filter to remove large particles; filtering and concentrating the sodium fluoride passing through the first filter by a reverse osmosis membrane; and drying the sodium silicate passing through the reverse osmosis membrane to produce sodium fluoride with a high purity of 99.7% or more.

Description

New proces for producing silica and fluorine compound from Hexafluorosilicic acid

 1 is a starting material using a hexafluorosilicate solution and a silicate solution in the present invention

       Overall process flow schematic for the preparation of nano pore silica and sodium fluoride.

Figure 2 is a schematic diagram of a novel instantaneous fast quantitative reaction device designed in the present invention.

 3 is concentrated from sodium fluoride to high concentration of sodium fluoride by reverse osmosis;

      Schematic diagram of a concentration system using an R / O membrane.

4 is an XRD (X-ray diffraction analysis) pattern of the sodium fluoride crystals prepared according to the present invention.

Figure 5 is a crystal picture of sodium fluoride by SEM (electron microscopy) and components by EDS

        This is the result of analyzing the content of the element.

Figure 6 shows the XRD (X-ray diffraction analysis) pattern of the nano-porous silica prepared by the present invention.

7 is a SEM photograph of the nano-porous silica prepared by the present invention and by the EDS

        Elemental analysis content analysis result.

The present invention is made of phosphate fertilizers and by-products silicon tetrafluoride and by-products generated in the process

 Preparation of nano-porous silica and sodium fluoride, economically useful materials using silicic fluoride

The present invention relates to a method for producing nanoporous silica and fluorine compounds using silicic acid as a starting material,

 Since 1960, W. Szmidt and W. Philip, Wasserglass in der Giesserei Technik, Giesserei-

Praxis (1960) №8. Germany, W. A. Czermiezow and G. Baranow, Chemicz, Promysl 2 (1961) 53.

USSR, D. Waren, Precept development in silicate based foundary processes, Brit. Foundrumen, t.64

(1971) №12. -UK, A. Krysztafkiewicz, Chemia Stosowana, 28 (1984) 47-Poland, A.

Krysztafkiewicz, B. Rager and M. Maik, Journal of Hazadous aterials, 48 (1996) 31-49. -

Poland, Jeong, S. et al., Journal of Colloid and Interface Science 192 (1), 156-161 (1997)-Korea,

R. Vacassy et al., Journal of Colloid and Interface Science 227, 302-315 (2000)-

Switzerland, Dong-Hyo Yang et al., Korean J. Chem. Eng., 17 (4), 401-408 (2000)-Korea et al.

The researchers have also studied the recovery and application of silica and sodium fluoride,

4,308,244 has also been filed for the same purpose. However, analyzing such research and patent content

All research conducted from 1960 to 2000, except for US patents, is simpler than commercial purposes.

This research is for the purpose of research and finally, after separating the silica and sodium fluoride, increase the purity or control the property

They are reproducible and impossible to make uniform. And in the case of patent US 4,308,244

In the process of the initial reaction in the manufacturing process of the fluorine compound and the amorphous silica is represented in the container represented by the precipitation tank

By installing the stirrer in the middle and supplying silica hexafluoride and sodium-containing compound, amorphous silica

It is produced in a molten state and sodium fluoride is present in the solution in an ionic state, so that amorphous silica and liquid

After separating sodium sulfide, amorphous silica is recovered, and in case of sodium fluoride, sulfuric acid is added after evaporation and concentration.

Finally form the form of hydrofluoric acid and sodium sulfate. But here the hexafluorosilicate

In the case of the precipitation tank where the and sodium-containing compound meet, simply install the stirrer in the container

When the injected silicic acid and sodium-containing compound are analyzed or observed microscopically, they are completely mixed and uniformly

Until mixing, there are many areas of high silicon hexafluoride and many sodium-containing compounds

It becomes an uneven state to an area | region to make. In this case, silicic hexafluoride and sodium-containing compounds

Due to the imbalance, the pH-rich acidic zones indicate that

PH is basic in the region of high solution of low sodium containing compounds

When it meets in equivalence ratio, it is liquid solution near neutral and pH is close to 7. By these processes

In case of preparing silica, nucleated growth coagulation primary from Si (OH) 4 ions generated initially during sol-gel reaction

Microscopic control of conditions that control uniform physical properties in the production of particles leading to particles, that is, pH

It is impossible to do. Therefore, control of surface area, pore size, pore volume, pore diameter, etc.

In addition to being impossible, it was impossible to separate the silica component in sodium fluoride. Thus commercial

It is a process that is impossible to prepare silica having nano pores with necessary physical properties. Also produced hydro

Sodium fluoride slurry by evaporation to separate the gel and commercialize sodium fluoride in the remaining solution

There is a costly problem because it makes energy. Also finally produced sodium fluoride sludge

Sulfuric acid is added to the slurry to produce hydrofluoric acid and sodium sulfate, generating another waste and

To produce commercially available products, not only energy costs, but also waste and wastewater treatment costs.

D) Commercial production is not possible due to corrosion of the work environment and production facilities by hydrofluoric acid. So in 1960

From 1980 to 1980, numerous studies found that commercial production was not possible due to these various problems.

Now, anywhere in the world, nano-porous silica and sodium fluoride using by-products of phosphoric acid and phosphate fertilizer plants

There is no commercially produced place.

  The technical problem to be achieved in the present invention is generated as a by-product from phosphate fertilizer plant or phosphate manufacturing process.

Is used to remove nanoporous silica and sodium fluoride using silicate and sodium-containing compounds, especially sodium silicate.

The process relates to a novel process for the preparation of a process, which according to the above process involves the reaction of

A novel process for producing nanoporous silica and sodium fluoride.

In order to solve the problem that the pH varies depending on the equivalence ratio at the time of meeting, the existing US patent

When the compounds containing silicic acid and sodium are added to a reaction vessel equipped with a stirrer as in US Pat. No. 4,308,244,

The equivalence ratio is different for each site where the substance meets, and thus the production and growth morphology of primary particles are different.

In addition, this problem is compensated for the disadvantage that the physical properties of the final silica is impossible, the present invention is silicate silicate and sodium silicate

By using the reactor of FIG. 2, the cerium solution can control the equivalence ratio during the reaction.

The equivalence ratio is controlled anywhere so that the desired pH can be controlled. So special

By using the produced reaction device, it is possible to uniformly control the physical properties of the hydrogel produced by the reaction of two materials.

Nanoporous silica, such as local gelling phenomenon, surface area, pore volume, pore diameter, etc.

It is a novel manufacturing method that allows the physical properties of to be constantly controlled. Also, the local equivalence ratio is different

Due to this, there is a way to solve the problem that nanopore silica and sodium fluoride are not completely separated.

The technical problem to be achieved in the invention. Another important technical challenge is the use of silicate and sodium silicate.

After separating the resulting nano-porous silica hydrogel to separate and concentrate the sodium fluoride in the remaining solution

Sodium fluoride remaining in the solution, instead of the conventional method of evaporation and concentration,

The particles are removed and a high purity sodium fluoride is obtained using the R / O membrane. Finally by drying

A method for producing at least 99.7% of the sodium fluoride powder phase. This method is 10% of existing energy costs

It is a breakthrough method that only takes a degree.

On the other hand, the present invention is a silicon tetrafluoride which is a by-product of the phosphate fertilizer and the phosphoric acid manufacturing process and an aqueous solution thereof.

 Of nanoporous silica and sodium fluoride, which are economically useful materials,

In the preparation of nanoporous silica and fluorine compounds starting from silicic fluoride, the silicic acid and sodium silicate solution are mixed and separated by using a high-speed instantaneous reaction device to control the desired pH by controlling the equivalence ratio.

 2 is a high speed instantaneous reaction apparatus using nanoporous silica and silicic acid as a starting material by the wet method.

At 2 degrees, component A is a sodium silicate or sodium-containing compound that can provide constant control over time

It is supplied from the metering pump which is present, and is drawn in to 2 of FIG. 2 inside of FIG. 2 is outside

Sodium silicate with a pressure of more than 1 kg / cm 2 to be introduced into the chamber is instantaneously homogenous with the silicic acid solution of component B.

Vortex is generated internally so that it can be mixed easily. Component B of FIG.

As a hydrofluoric acid, a certain amount is supplied from the outside by a metering pump and has a special structure through 3 of FIG.

At the tip of 3, like a component A, the pressure is introduced into a liquid that takes more than 1kg / ㎠ and at the tip 2 of FIG.

Under pressure and vortices, the pressure of B component, silicic acid is applied again,

As the current flows uniformly in a state where a flow is generated, the pH is controlled by the existing amount,

The problem of not being able to match the equivalence ratio of the conventional site was solved. The process according to the invention is such a special reaction

The reaction can be used to produce uniform and continuous nanoporous hydrogels.

Each number in the figure has the following structure. Where component A means sodium silicate and component B

Sodium containing compounds, including sodium silicate. 1: component A or sodium silicate feeder, 2: component

A dispersion vortex device of A, 3: component B, that is, a silica hydrofluoric acid supply device, 4: component A, B primary homogeneous mixing device, 5: component A, B secondary

It is composed of a homogeneous mixing device, and precisely precisely pressurized sodium silicate and pressurized silicic acid

In the case of reaction in No. 4 of FIG. 2 by means of a metering pump, both substances are

It can be reacted at a uniform equivalence ratio instantaneously. In particular, sodium silicate reacted in the present invention

The pH varies depending on the equivalence ratio after the reaction in the reaction of and silicic acid.

When the pH is acidic liquidity and the sodium silicate is supplied in excess, the liquidity after the reaction is basic.

Therefore, existing methods in the manufacturing process of nano-porous silica and sodium fluoride to be achieved in this study

It is possible to solve the problem of locally changing pH when mixing two substances.

  The hydrogel produced in this way can be separated from the solution as a solid phase and remain in the remaining solution after separation.

Sodium fluoride is dissolved in the solution, and the solution is separated from the conventional method by evaporative concentration.

In order to solve this problem, using a reverse osmosis device such as a third degree, it was concentrated with high purity sodium fluoride and finally

Sodium fluoride can be recovered by drying.

 The separated silica hydrogel is a nano-porous silica to control the physical properties of the nano-pores present therein

Temperature is controlled from 10-90 ℃ to 3-10 by pH controlled water and temperature control

The time is controlled from 0 to 100 hours so that the properties and characteristics of nanoporous silica can be used for each application.

The surface area, pore volume, pore size, etc. can be controlled.

       (2) [functions and actions]

In FIG. 2, the final pH depends on the pH conditions after the reaction when sodium silicate and silicic acid are controlled at a specific equivalent ratio.

It is possible to control the purity of no-porous silica and sodium fluoride.

Separation of sodium fluoride is difficult and the reason is the formation of sodium fluoride, which causes

Reaction mechanism for the production of nanoporous silica and sodium fluoride, which are present as pure water and are objects of the present invention

The mechanism can be expressed as follows and these reactors are basic, especially pH within 7.5-9.8

Lose.

3 (Na2O 3.0 SiO2) + 20 H2O + H2SiF6 → 10 Si (OH) 4 + 6NAF + H2O

10 Si (OH) 4 → 10SiO2 + 20H2O

In the case of the starting material sodium silicate, the molar ratio of sodium oxide and silicon oxide is silicon oxide per 1 mol of sodium oxide.

Can be from 1 to 3.5 molar ratios. In the case of silicic acid, the concentration can be more than 3%.

       EXAMPLE

Example 1

From the storage tank in which the quantitative reaction system was installed, with 18% sodium silicate and B component

Feed 25% silicic acid. By adjusting the pump speed in the metering pump, the sodium silicate and

The first rate inside the instantaneous high-speed reactor is controlled by controlling the equivalence ratio of two substances by using the rapid quantitative reactor.

The reactants mixed in the homogeneous reaction section and the second homogeneous reaction section ensure that the pH after the final reaction is the base and is accurate.

The pH should be about 8.5-9.5. When a three-dimensional hydrogel is produced from the colloid,

The silica hydrogel in the mold and the sodium fluoride in the solution are separated. 600 kg of hydrogel obtained by separating

It is transferred to 6㎥ polymerization tank where pH and temperature can be controlled.

Nanoporous silica high by supplying and discharging to the polymerization tank containing the hydrogel at a flow rate of 20L / min

Condensation polymerization of silanol groups on the outside and inside of the drawgel controls surface area, pore volume, and pore diameter.

It was. Physically controlled nano-porous silica hydrogels were dried at 150 ° C. for 20 hours in a box dryer.

After controlling the water content to 2% or less, BET surface area measurement result was 330㎡ / gr, pore volume was 0.9ml / gr, average pore size

A 420 kg zero gel having a physical property of 10.9 nm was obtained.

Example 2

From the storage tank in which the quantitative reaction system was installed, with 18% sodium silicate and B component

Feed 25% silicic acid. By adjusting the pump speed in the metering pump, the sodium silicate and

The first rate inside the instantaneous high-speed reactor is controlled by controlling the equivalence ratio of two substances by using the rapid quantitative reactor.

The reactants mixed in the homogeneous reaction section and the secondary homogeneous reaction section ensure that the pH after the final reaction is acidic and accurate.

The pH should be about pH 2-5. Solids generated when a hydrogel with a three-dimensional network structure is generated from the colloid

The silica hydrogel is separated from the sodium fluoride solution. 600kg of hydrogel obtained by separating

And the temperature is controlled to transfer to 6㎥ polymerization tank pH is 4, the temperature of 40 ℃ continuously controlled water 20L

Nanoporous silica hydro by feeding and discharging to the polymerization tank containing the hydrogel at flow rate of / min

Surface area, pore volume, and pore diameter were controlled by polycondensation of silanol groups present on the outside and inside of the gel.

All. Physically controlled nano-porous silica hydrogel was dried in a box dryer for 20 hours at 150 ° C.

After controlling the content to less than 2%, the BET surface area measurement result was 650㎡ / gr, pore volume 0.35ml / gr, average pore size

450 kg of zero gel having a physical property of 3.0 nm was obtained.

Example 3

 15% sodium silicate and B as component A in FIG.

Supply 20% silicic acid. By adjusting the pump speed in the metering pump, the sodium silicate and

The first rate inside the instantaneous high-speed reactor is controlled by controlling the equivalence ratio of two substances by using the rapid quantitative reactor.

The reactants mixed in the homogeneous reaction section and the second homogeneous reaction section ensure that the pH after the final reaction is the base and is accurate.

The pH is 8.5-9.5. The reactant passed through the high-speed quantitative reaction nozzle is filled with water in advance.

The agitator was attached inside the polymerization tank to supply the mixture while stirring.

Adjust to 15gr / 100ml. When the final solid content is 5-15gr / 100ml, the pH of the polymerization unit

And the desired surface area, pore volume and pore size. Temperature in the polymerization bath is 20-

By controlling the temperature to 90 ℃, pH 2-10 to control the properties of the nano-porous silica hydrogel. Property control is complete

When the precipitated nanoporous silica suspension is filtered and washed with a filter press, the particle size is reduced to 2-

A precipitated silica of about 100 μm was obtained. As a result of measuring the physical properties of the obtained nanoporous silica,

50 micrometers surface area of 250 m <2> / gr, pore volume 1.0 ml / gr, and average pore size nanoporous silica were obtained.

 Example 4

15% sodium silicate and B as component A in FIG.

Supply 20% silicic acid. By adjusting the pump speed in the metering pump, the sodium silicate and

The first rate inside the instantaneous high-speed reactor is controlled by controlling the equivalence ratio of two substances by using the rapid quantitative reactor.

The reactants mixed in the homogeneous reaction section and the secondary homogeneous reaction section ensure that the pH after the final reaction is acid and

The pH should be about 3.5-4.5

The agitator is attached inside the polymerization tank and supplied with stirring.

Adjust to 15gr / 100ml. When the final solid content is 5-15gr / 100ml, the pH of the polymerization unit

And the desired surface area, pore volume and pore size. Temperature in the polymerization bath is 20-

The physical properties of the nano-porous silica hydrogel are controlled by controlling the temperature at 40 ° C. and pH 3-5. Property control completed

When the precipitated nanoporous silica suspension is filtered and washed with a filter press, the particle size is reduced to 2-

A precipitated silica of about 100 μm was obtained. As a result of measuring the physical properties of the obtained nanoporous silica,

Nanoporous silica with a surface area of 354 m2 / gr, pore volume of 0.75 ml / gr, and an average pore size of 8.4 nm

there was.

High purity nano-porous silica and fluoride from silicic acid and sodium ion-containing compounds proposed by the present invention

As a technique of separating the thorium is completed, the process of phosphate and phosphate fertilizers

Nanoporous silica and sodium fluoride as functional inorganic materials from silicic acid, an industrial waste generated on a scale

By manufacturing fertilizers, fertilizer companies and related companies that produce silicic acid can be transformed into environmentally friendly companies.

It is also a groundbreaking invention that created new electricity through the production of sodium fluoride.

Claims (4)

In the method for producing nanoporous silica and fluorine compound using silicate and sodium silicate, 1kg / by a metering pump to control 20-25% silicic acid and 15-18% sodium silicate in the equivalence ratio in the pH range Separation of quantitatively in the state of vortex in the high speed instantaneous reaction device with the pressure of more than cm to separate nanoporous silica hydroadhesion, and the remaining sodium fluoride removes the large particles through the primary filter and filter as R / O membrane. A method for producing nanoporous silica and fluorine compounds based on silicic hexafluoride which is concentrated and dried to produce high purity sodium fluoride of 99.7% or more. The method for controlling the density of silanol groups present in and out of the nanoporous silica by supplying the nanoporous silica hydrogel separated in claim 1 to the hydrogel with pH and temperature controlled water in an acid and base atmosphere. A method of preparing sodium fluoride powder by making sodium fluoride in high concentration by the reverse osmosis method in the sodium fluoride solution separated in claim 1 and drying the ah. A method of preparing sodium fluoride and nanoporous silica by separating the hydrogel produced in claim 1 by a filter press and drying the sodium fluoride in the remaining filtrate to a high concentration by a reverse osmosis method.

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