ES2241494A1 - Disodium trioxosilicate production for clay deflocculation comprises crystallization from sodium silicate solution and polymers mixture with occlusion of organic polymer molecules - Google Patents

Abstract

The production of disodium trioxosilicates for clay deflocculation comprises the addition to a concentrated 1:1 stoichiometry sodium silicate solution, of an e.g. organic polymers solution at above 80 deg. C. Also claimed is a process using the trioxosilicates. The process promotes crystallization of e.g. disodium trioxosilicate pentahydrate with occlusion of molecules of the organic polymers.

Description

Manufacturing process of trioxosilicates of crystallized disodium with occlusions in its crystalline structure of additives of the type organic polymers and / or polyphosphates and their application in clays defloculation.

Object of the invention

The following invention, as expressed in the set forth herein, refers to a manufacturing process of disodium trioxosilicates crystallized with occlusions in its crystalline structure of additives of the type organic polymers and / or polyphosphates and their application in defloculation of ceramic clays.

With the present invention it is intended to prepare solid mixtures based on a majority product, the disodium trioxosilicate pentahydrate, containing one or more products incorporated in a completely homogeneous way within your crystal structure It's about taking advantage of the features of sodium silicate to crystallize from disodium trioxosilicate with a variable number of moles of water of crystallization, which it is used in this invention to absorb the water incorporated in the aqueous solution of the additives.

The proposed procedure consists of additive a solution formed by the liquid polymer mixture organic and / or polyphosphates on a main solution of stoichiometric sodium silicate moles SiO2 / moles Na 2 O = 1/1 that has undergone vacuum evaporation previous, up to a water content of less than 42% and a content in solids greater than 58%. The mixture is homogenized by stirring, the resulting solution being prepared for crystallization. A crystallized solid is obtained with a percentage of final water corresponding to the stoichiometric water of crystallization of the disodium trioxosilicate phase pentahydrate.

Scope

Clays defloculation in water is a well established and widely used technology in the ceramic industry. In grinding / deflocculation processes, together with water and clay, a series of additives (deflocculants) are used to reduce the viscous and thixotropic behaviors of suspensions prior to atomization.
tion.

Deflocculant additives more widely used in the ceramic industry are products such as carbonate sodium, different sodium silicates, polyphosphates, or sodium and ammonium salts of organic polymers of the acid type Acrylic, methacrylic or maleic.

The most commonly used deflocculant formulations They try to use the synergy of several components. The fact of use several components, and the possibility of presenting in different states: solid or liquid, increases the difficulty in formulation and dosage.

This patent is intended to present a system compact deflocculant, consisting of two or more components already attached:  disodium trioxosilicate pentahydrate, organic polymers and / or polyphosphates; as well as its manufacturing procedure.

Background of the invention

The majority product in the formulation of product described in this invention is disodium trioxosilicate Pentahydrate

The production of disodium trioxosilicates is performed in a crystallization process that can occur from different ways, one of which is included in the patent of Spanish invention no. 549886 with no. of publication ES8606200 to favor of the same owner as this file.

The salts produced on an industrial scale in these processes are disodium trioxosilicate nonahydrate and much more important for its production volume, the trioxosilicate of disodium pentahydrate; both products with structure crystalline

The crystalline phases are hydrated salts, perfectly defined by DRX (X-Ray Diffraction) and collected in the ICDD (International Center Diffraction Data) files with the numbers 19 1239 and 19 1241, respectively.
mind.

CAS numbers are:

\hskip0.52cm

10213-79-3Disodium trioxosilicate pentahydrate:

 \ hskip0.52cm 

10213-79-3

\hskip0.6cm

13517-24-3Disodium trioxosilicate nonahydrate:

 \ hskip0.6cm 

13517-24-3

The chemical formula of the pentahydrate phase is the next:

SiO_ {2} \ cdot Na_ {2} O \ cdot 5 H2O

with the following composition percentage in weight:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 28.30% \ cr Na2O: \ +
\ + 29.24% \ cr H2O: \ + \ +
42.46% \ cr}
    

The water content of these salts is very high given its molecular weight, and this is the main feature that it is used for the invention to be described herein memory.

The rest of the raw materials used in the formulation of the present invention, additives, are compounds Well known in the ceramic industry. These products are either sodium salts of organic polymers derived from acid acrylic, methacrylic or maleic; products that are normally marketed in the form of aqueous solutions; or you go out sodium polyphosphoric acids, which are presented in solid form generally, although they are very soluble in water.

Description of the invention

This document describes a manufacturing process of disodium trioxosilicates crystallized with occlusions in its crystalline structure of additives such as organic polymers and polyphosphates and their application in clays defloculation, in the case of crystalline solid disodium trioxosilicates can be produced by different techniques, so that the procedure understands:

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the use of a solution of 1: 1 stoichiometry sodium silicate concentrated to a water percentage less than stoichiometric 42%;

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dissolution additivation of above concentrated sodium silicate of another solution of organic polymers and polyphosphates at a temperature greater than 80 ° C;

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the crystallization, or of continuous form by spraying on a bed of the product itself solid, or discontinuously with previous sowing;

so that water is used Crystallization of the majority trioxosilicate crystalline phase of disodium pentahydrate getting the crystallization during occlusion of organic molecules added as a solution aqueous, this water becoming part of the molecule crystalline

The percentage of additives in the form of dissolution aqueous can reach up to 15%.

The product obtained is formed by agglomerates of disodium trioxosilicate crystals pentahydrate with incorporation within the interstices of the agglomerates of organic products derived from acrylic acid polymers or from polyphosphates or mixture of both, that is, a product is obtained crystallized solid

On the other hand, the product obtained is of special application as a deflocculating agent in processes industrial grinding / deflocculation of clays on track watery

Brief description of the figures

To complement the description below it will be done, and in order to help the understanding of characteristics of the invention, is attached herein of two figures, in an illustrative and non-limiting manner.

Figure 1 shows a diffractogram of X - ray intensity versus 2 \ Theta, crystals trioxosilicato disodium pentahydrate (black) pattern and intensities of the same phase as ICDD data base.

Figure 2.- Shows an X-ray diffractogram, intensity versus 2 \, of crystals of the product described in example No. 4, SP24-4 (in black) and intensity pattern of disodium trioxosilicate pentahydrate according to ICDD database .

As you can see the crystalline phase formed It is the same in both products.

Detailed description of the invention

To carry out the new procedure We begin by preparing a sodium silicate solution of a molar ratio SiO 2 / Na 2 O = 1.

       \ newpage
    

It is subsequently concentrated by evaporation to vacuum to a water content below 42% and a content in solids of more than 58%.

To this solution, thus adjusted, the dissolution of the additive chosen in varying concentrations up to a maximum of 15% on dissolution weight of the additive. Be homogenize the mixture by stirring, and this solution is already Ready to be crystallized. The percentage of water in this final solution corresponds to the stoichiometric water of Crystallization of the disodium trioxosilicate phase pentahydrate. The temperature will be above 80 ° C.

This solution is crystallized by sowing and subsequent cooling, producing a solid that is subsequently It can grind.

Crystallization can also be performed in a continuous process, on a closed circuit. The solution is spray on the solid so that granules of Different sizes of powder wet with the solution. This product It will pass through a zone of cooling and crystallization.

Finally, the product is classified by sizes and the chosen fraction is removed from the circuit for packaging, after which it returns to the initial zone. The withdrawn fraction must be adjusted to keep the flow rate constant within the circuit, taking into account the additions in the form of dissolution.

The product thus obtained consists of particles agglomerates of perfectly defined small crystals of disodium trioxosilicate pentahydrate, leaving the additives additives occluded in the macropores or interstices of the agglomerates in a completely homogeneous way without modifying their Appearance or properties.

In the measurements by DRX (X-Ray Diffraction) of the product crystallinity no differences are observed with Disodium trioxosilicate commercial pentahydrate, as can be Look at the diffractograms.

Water added in the additive solution is incorporated into the solid product as crystallization water of the disodium trioxosilicate phase pentahydrate that was in default.

With this you get one of the most facets important of the invention, transforming the additive into dissolution in a solid product homogeneously distributed within of the disodium trioxosilicate matrix.

By putting this product in aqueous solution, the disodium trioxosilicate crystals pentahydrate dissolve quickly given its high solubility, releasing the additives that they also go to dissolution, leaving both products in conditions to act at the same time according to the chosen application.

This procedure is achieved in a single process a completely homogeneous mixture of both components.

Next we will describe several examples:

Example No. 1

1000 gr was prepared in the laboratory. of a Sodium silicate solution with the following composition:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 26.36% \ cr Na2O: \ +
\ +
26.71% \ cr}
    

This solution was concentrated by evaporation, removing 49 g of water to get the next composition:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 28.79% \ cr Na2O: \ +
\ +
29.20% \ cr}
    

This solution was split into two parts same.

One of the parts was mixed by stirring with 25 g of a 41% aqueous solution of a sodium polyacrylate commercial. The temperature of the mixture rose above 80 ° C before sowing it with 25 g of trioxosilicate crystals of Disodium commercial pentahydrate powder. After the intimate mixing of sowing and dissolution, the product was spread on a tray a thin layer of approximately 5 mm where it cooled in a few minutes below 72 ° C, which is the temperature of crystallization.

In less than 5 minutes the product crystallized quickly, giving a hard and brittle solid, which was ground to sizes between 1.5-0.5 mm for later testing as clay deflocculant, (sample SP24-1, relative to the attached table).

The other part of the solution was mixed from the above form with 50 g of the same polyacrylate solution sodium, and above 80 ° C was seeded with 25 g of crystals of disodium trioxosilicate pentahydrate.

The crystallization obtained was also correct, giving a brittle solid and easy to grind, (sample SP24-11, relative to the attached table).

The subsequent dissolution in water of the product allowed to analyze the polyacrylate content as well as the percentage of SiO 2 and Na 2 O in both cases.

Example 2

1000 gr was prepared in the laboratory. of a Sodium silicate solution with the following composition:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 26.36% \ cr Na2O: \ +
\ +
26.71% \ cr}
    

This solution was concentrated by evaporation, removing 49 g of water to get the next composition:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 28.79% \ cr Na2O: \ +
\ +
29.20% \ cr}
    

This solution was split into two parts same.

One of the parts was mixed by stirring with 25 gr. of a 40% aqueous solution of sodium hexametaphosphate. The Mix temperature rose above 80 ° C before sow it with 25 gr. of disodium trioxosilicate crystals commercial pentahydrate powder. After the intimate planting mixture and solution, spread the product in a layer on a tray thin about 5 mm. where it cooled in a few minutes by below 72 ° C which is the melting temperature.

In less than 5 minutes the product crystallized quickly, giving a hard and brittle solid, which was ground to sizes between 1.5-0.5 mm for later testing as clay deflocculant, (sample SP24-2, relative to the attached table).

The other part of the solution was mixed from the previous form with 50 gr. of the same solution of hexametaphosphate sodium, and above 80 ° C was seeded with 25 g of crystals of disodium trioxosilicate pentahydrate.

The crystallization obtained was also correct, giving a brittle solid and easy to grind, (sample SP24-22, relative to the attached table).

The subsequent dissolution in water of the product allowed to analyze the polyphosphate content as well as the percentage of SiO 2 and Na 2 O in both cases.

Example 3

500 gr was prepared in the laboratory. of a Sodium silicate solution with the following composition:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 26.36% \ cr Na2O: \ +
\ +
26.71% \ cr}
    

This solution was concentrated by evaporation, removing 25 gr. of water to get the next composition:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 28.79% \ cr Na2O: \ +
\ +
29.20% \ cr}
    

This solution was mixed by stirring with 25 gr. of a 41% aqueous solution of a commercial polyacrylate and 25 gr. of 40% aqueous sodium hexametaphosphate solution. The Mix temperature rose above 80 ° C before sow it with 25 gr. of disodium trioxosilicate crystals commercial pentahydrate powder. After the intimate planting mixture and solution, spread the product in a layer on a tray thin about 5 mm. where it cooled in a few minutes by below 72 ° C which is the melting temperature.

In less than 5 minutes the product crystallized quickly, giving a hard and brittle solid, which was ground to sizes between 1.5-0.5 mm for later testing as clay deflocculant, (sample SP24-3, relative to the attached table).

Example 4

It was manufactured on an industrial scale.

They were prepared by concentration in vacuo from of a more dilute solution 43300 kg. silicate solution sodium of the following composition:

       \ dotable {\ tabskip \ tabcolsep # \ hfil \ + \ hfil # \ hfil \ + # \ hfil \ tabskip0ptplus1fil \ dddarstrut \ cr} {
 SiO2: \ + \ hskip1.7cm \ + 28.84% \ cr Na2O: \ +
\ +
29.25% \ cr}
    

In a 50 m 3 mechanically stirred reactor 3765 kg were added to the previous solution. of a solution 41% aqueous commercial sodium polyacrylate, and mixed during 15 minutes. The temperature of the mixture was maintained by above 80 ° C.

The above solution was sprayed into a rotary mixer-mixer on a bed of Disodium trioxosilicate ground pentahydrate.

After the exit of the mixer the solid formed is incorporates a rotary cooling system where it cools, and where the crystallization of the product ends.

The flow that leaves the cooling system is Sort by size in a vibrant sieves and collect the fraction between 1.5-0.5 mm. for packaging. This fraction should correspond to the dissolution feed added continuously to keep the flow rate constant on the circuit

The rest recirculates to a mill where it is ground and returns to the starting point closing the circuit.

Given the capacity of the circuit, the product separated in the first three hours was discarded to ensure that the additive content was as expected.

A sample of product was separated for testing clays defloculation posteriors (sample SP24-4, relative to the attached table).

With the previous six samples were made Clays defloculation tests to verify their effectiveness, compared to other trioxosilicate based deflocculant mixtures of disodium pentahydrate and sodium polyacrylate in solution, such how both products are currently used.

To check the effectiveness of the product resulting, defloculation tests have been performed following the usual procedures in the ceramic industry.

The industrial ceramic manufacturing process start by wet grinding / deflocculation of clays to obtain a slipper or suspension of clay in water with a solids content as high as possible but also with viscosity low, that allows the handling by pumping of this slip in its subsequent spray drying process.

The role of the deflocculant in this process is modify the clay / water colloidal system by eliminating or neutralizing attractive electrostatic charges and therefore increasing the Z potential of the suspension, getting values low viscosity

The clay paste used was a mixture red stoneware industrial. The solids concentration was 65% and 35% water

The water added was a water prepared in laboratory with salt contents similar to those used in Industrial processes, with high hardness and high concentration in chlorides. (30 ° F hardness and 600 ppm Chlorides).

The six deflocculants were used as Samples indicated and a seventh Reference consisting of a mixed deflocculant formed in 90% solid of trioxosilicate of disodium pentahydrate and 10% by dissolution at 40% of commercial sodium polyacrylate.

For grinding a ball mill was used laboratory of a liter of capacity with 500 gr. of balls of 20 mm alumina. diameter.

The viscosity of the suspension was measured by the standard industrial method of fall time in Ford cup no. Four.

The trials consisted of adding within the mill 500 g of clay paste, 270 g of water and the percentage deflocculant variable calculated on clay weight.

It is milled for a fixed time of 5 minutes, after which the viscosity is measured, after resting the slip inside the Ford cup for 60 s.

In the industrial process they are considered good viscosity values below 25 s of fall time that correspond to approximately 250 cp.

The results obtained are presented in the table or table 1.

one

Claims (4)

1. Method of manufacturing disodium trioxosilicates crystallized with occlusions in its crystalline structure of additives of the type organic polymers and / or polyphosphates, in the case of crystalline solid disodium trioxosilicates being able to be produced by different techniques, characterized in that the process comprises:

?

the use of a solution of 1: 1 stoichiometry sodium silicate concentrated to a water percentage less than stoichiometric 42%;

?

dissolution additivation of above concentrated sodium silicate of another solution of organic polymers and / or polyphosphates at a temperature greater than 80 ° C;

?

the crystallization, or of continuous form by spraying on a bed of the product itself solid, or discontinuously with previous sowing;

so that water is used Crystallization of the majority trioxosilicate crystalline phase of disodium pentahydrate getting the crystallization during occlusion of additive molecules added as a solution aqueous, this water becoming part of the molecule crystalline 2. Method of manufacturing disodium trioxosilicates crystallized with occlusions in its crystalline structure of additives of the type organic polymers and / or polyphosphates, according to claim 1, characterized in that the percentage of additives in the form of an aqueous solution can reach up to 15%. 3. Product obtained, according to claims 1 and 2, characterized by being formed by agglomerates of trioxosilicate crystals of disodium pentahydrate with incorporation within the interstices of the agglomerates of organic products derived from polymers of acrylic acid or of polyphosphates or mixture of both. 4. Application of the product obtained, according to the previous claims, as a deflocculating agent in the industrial processes of grinding / defloculation of clays on track watery