MXPA98004161A - Aqueous compositions of silic - Google Patents

Abstract

The present invention relates to: A composition of an aqueous solution containing silicate, comprising: a) from 10% w / w to 50% w / w of a silicate compound selected from sodium and potassium silicates, or a mixture of such silicate compounds b) from 1% w / w to 5% w / w of a salt, the cations of which are selected from sodium and potassium ions and the anions from which they are selected from halogen, sulfate and carbonate ions , or a mixture of such salts, c) from 0.25% w / w to 5% w / w of ethylene glycol, and d) water. The silicate compound is preferably sodium silicate, especially sodium silicate having an average formula of Na2SiO3, Na6Si2O7, Na2Si3O7 or Na2Si4O9, or mixtures thereof. S is preferably sodium chloride. The composition is useful in the encapsulation of pollutants, inflammable inflammable materials and in the extinction of the

Description

AQUEOUS SILICATE COMPOSITIONS FIELD OF THE INVENTION The present invention relates to compositions of an aqueous silicate-containing solution, which are useful in the encapsulation of contaminants as well as for other purposes.

BACKGROUND OF THE INVENTION Germán Auslegeschrift No. 159797 describes the use of compositions containing water glass or liquid sodium silicate to convert the oil or harmless oil contaminants. However, the compositions described herein are two component composition systems that require the measurement of the components and mixing at the site of use. Germán Auslegeschrift No. 1248197 discloses compositions for the adsorption of oils and solvents, the compositions in question which are dry compositions consisting of mixtures or water soluble glass, solid salts and absorbent carriers, solids.

REF: 27605 BRIEF DESCRIPTION OF THE INVENTION It has been found that it is possible to prepare aqueous solution compositions, of a single component containing dissolved silicates as well as other components, compositions that make it possible to convert the harmless contaminants through the encapsulation and furthermore that they are stable and do not require any dissolution. , measurement or mixing at the site of use. In this way, the invention is a composition of an aqueous solution containing silicate, comprising a) from 10% w / w to 50% w / w of a silicate compound selected from sodium and potassium silicates, or a mixture of such silicate compounds; b) from 1% w / w to 5% w / w of a salt, the cations of which are selected from sodium and potassium ions, and the anions from which they are selected from halogen, sulfate and carbonate ions, or a mixture of such salts; c) from 0.25% w / w to 5% w / w of ethylene glycol; and d) water.

DETAILED DESCRIPTION OF THE INVENTION Due to availability as well as economic reasons, it is preferred that the silicate compound be a sodium silicate. As will be well known to a person skilled in the art, soluble silicates such as sodium silicate exist in various forms depending on, on the other hand, the average number of silicon atoms present in the silicate anion, and, on the other hand, , the average degree of salt formation among the available number of silicic acid hydroxy groups. In the case of sodium silicate, this ratio is often expressed as the molar ratio Na20: SiO2. and the commercially available sodium silicate products and the amounts can have a ratio within a very wide range. In this way, the sodium silicates useful in the present invention can have a molar ratio of Na20: SiO2 anywhere in the range of about 4: 1 to about 1: 4, preferably in the range of about 1: 1 to 1: 4 In this context, the specific examples of the sodium silicate components are those corresponding to an average, approximate formula of Na2Si03, Na6Si207, Na2Si307 or Na2Si409, or mixtures thereof, in particular Na2Si30. It is preferred that the silicate compound, in particular sodium silicate, be present in the composition in an amount of 13-31% w / w, preferably 15-31% w / w. in particular 18-31% w / w, especially 21-31% w / w, such as 27% w / w. The salt indicated under article b) above may be, for example, sodium chloride, sodium bromide, sodium iodide, sodium sulfate, sodium carbonate, potassium chloride, potassium bromide, potassium iodide, potassium sulfate. or potassium carbonate, or mixtures of such salts. However, for reasons of availability and economy, it is preferred that the salt used as article b) is sodium chloride. The salt, in particular sodium chloride, may be present in an amount of 1-4% w / w, preferably 2-4% w / w, in particular about 3% w / w. With respect to ethylene glycol present as article c) above, it is believed that this component exerts a stabilizing effect in terms of long-term stability. Thus, in the absence of ethylene glycol, it has been found that the silicate-containing composition will gradually develop a solid precipitate indicating the possible beginnings of an undesired silicate reaction. In a preferred embodiment, ethylene glycol is present in an amount of 0.5-4% w / w. more preferably 0.5% -3% w / w. in particular 0.5% -2% p / p. especially 0.5-1% w / w, such as 0.7% w / w. A presently preferred example of a composition according to the invention contains about 27% w / w of sodium silicate having an average formula near Na2Si3? 7 (usually a molar ratio of Na20: Si02 of 1: 3.1), approximately 0.7 p / p of ethylene glycol, and approximately 3% w / w of sodium chloride, the rest being water. For certain applications, it may also be desirable to include some special additives such as surfactants, for example nonionic surfactants such as ethoxylated fatty acids.; defoaming agents, for example silicon oils (such as dimethylpolysiloxane), or polyethylene oxide or polypropylene oxide; foaming agents to generate stable foams (for fireproofing or extinguishing fire), for example, foaming agents based on synthetic surfactants. Such agents may be included in varying amounts, depending on the type and function, but the typical contents are in the range of 0.1 to 5% w / w. One of the uses for which the compositions of the invention are particularly suitable is the treatment of contaminated solids such as soil or sand contaminated with oil or other hydrocarbon residues, mineral tar, or industrial chemicals such as pesticides (eg Aldrin ™). , Endrin ™ or Pentachloroplend ™), particles contaminated with heavy metals such as fly ash, incinerator slag, ground from old industrial sites, fluorescent light tube waste ("ribbon lights"), and the like. In this way, it has been found that when such materials are treated with the compositions of the invention, the compositions are capable, without any further treatment, of forming glass gels which very efficiently encapsulate contaminants and / or contaminated material to a degree which significantly reduces or even eliminates the possibility of subsequent leaching of the surrounding material. This makes it possible to store pollutants encapsulated in silicate and contaminated materials at uncontrolled or only marginally controlled deposition sites without any significant danger that contaminants are leached into the environment such as groundwater reservoirs. There are indications that if the material to be encapsulated is also treated with water-soluble substances containing divalent cations such as calcium-containing substances, for example slaked lime, together with the composition of the invention, the encapsulation is more efficient. Without being bound by any theory, it is believed that this effect can be attributed to the fact that divalent cations such as calcium are known to accelerate the gelation of waterglass solutions. Furthermore, it has been found that the pure water glass solutions, similar, the compositions of the invention can also be used in the fireproofing of various materials, in particular absorbent materials, such as textiles, paper, cardboard, roofing etc. , as well as domestic waste. In the treatment with the compositions of the invention, the material in question and any subcomponent thereof such as fibers, will become encapsulated in vitreous silicate gel. The advantage over ordinary water glass solutions is, however, that the effect is very rapid in that it is the gel formation which results in the fireproofing effect and not only a drying effect such as when using solutions of water glass, pure, ordinary. It is also contemplated that the fireproofing effect can also be improved by simultaneous treatment of the material in question with a resin for the purpose of preventing or reducing any migration of the composition, in particular, if the treated objective is subjected to direct weathering. . Such resins could conceivably be aqueous resin dispersions such as commercially available dispersions of phenolic, acrylic or styrene resins. In the same way, it has been found that the compositions of the invention can also be used to extinguish fires in materials that can be extinguished with water only with difficulty or not at all. In this way, it is. has found that the burning of automobile rubber tires, which under normal circumstances can not be extinguished by spraying with water, can in fact be extinguished effectively with compositions of the invention. It has also been observed that the compositions of the invention are capable of preventing the ignition of materials, the burning of which does not require the provision of external oxygen, such as fumiduous powder impellers for portable firearms, and it is contemplated that this effect may also be extended to impellers for missiles or explosives such as plastic explosives. In this way, the compositions of the invention can serve in the elimination or conversion into harmless of surplus war materials of such materials. Similarly, it may also be possible for the compositions to render highly flammable substances such as those in incendiary incendiary munitions, eg, napalm substances of i, harmless. to. the type of plastic-gelled solvent / petroleum mixture. When the compositions of the invention are used to treat contaminated solids, the compositions can be applied in amounts that vary over a wide range, depending on the type of contaminant, and the precise amount is not critical and can be easily established by the skilled person. in the technique through the routine test. However, as a general guide it can be said that an adequate amount of a composition of the invention can be from 1 to 50 parts by weight per 100 parts of the contaminated solid, preferably from 2 to 10 parts by weight. The composition can be applied in a very direct manner simply by emptying or spraying the composition in the contaminated material, for example soil contaminated with oil, if the contamination is restricted to the surface parts of for example the earth. In the case of contaminations located more deeply, the application can be made when drilling or drilling perforated pipes in contaminated soil and pumping the composition into the soil. In the case of non-coherent particulate materials such as fly ash, the composition of the invention can be simply sprayed onto the material, optionally while performing some short mixing operation such as in a rotating drum mixer similar to a concrete mixer. Similarly, when the composition of the invention is used for fireproofing purposes, the composition can be used in amounts over a wide range, depending on factors such as the flammability of the material, its ability to absorb aqueous solutions. Typical amounts may be in the range of 2 to as much as 70 parts by weight per 100 parts of the material that is flame retardant. The composition can (in the case of textiles or paper) be applied when spraying onto the material, or can (in the case of high volume material such as waste) be injected into the material in a manner known per se. The invention is further illustrated by the following non-limiting examples.

EXAMPLE 1 A composition of the following components was prepared: 1. 410 kg of an aqueous solution of 33% w / w of sodium silicate having a molar ratio of Na20: SiO2 of 1: 3.1. 2. 3.5 kg of ethylene glycol. 3. 100 kg of an aqueous solution 15% w / w of sodium chloride.

The composition was prepared by placing the sodium silicate solution in an 800 liter mixing vessel and gradually adding the ethylene glycol under vigorous stirring by means of a paddle stirrer. Subsequently, the sodium chloride solution was added gradually under vigorous stirring in the same manner. The clear, resulting solution had a density of approximately 1.3 g / ml.

EXAMPLE 2 This example is about tests performed to examine changes in the lixivity of organic soil contaminants through treatment with a composition of the invention, specifically the composition prepared in Example 1. The test was designed to test the composition's ability to immobilize diesel fuel and polychlorinated biphenyls (PCBs) located as contaminants in the soil.

General description of the tests Materials: The selection of contaminants was made based on a variety of factors. Diesel oil was selected primarily because this is the most widespread type of soil contaminant, and PCBs are selected primarily because of their environmentally high toxicity. The sand was used as a simplified model of a soil matrix. The reason for this type of soil was its relatively simple composition. When using sand, an attempt was made to reduce the number of factors that could influence the results of the test. On the other hand, it should be noted that more complex types of soil will likely have a positive effect on the binding of contaminants to the matrix. Consequently, the test performed in the sand should show a high degree of leaching of pollutants compared to other types of soil and therefore can be considered a stricter test.

Preparation of the test material: The contaminants were applied to the sand in the laboratory by dissolving the diesel and the PCBs in methylene chloride and by mixing the solution with the dry sand. Methylene chloride was evaporated while at the same time the sand was stirred. In this way, 1500 grams of sand were contaminated with 758 mg of diesel, and another lot of 1500 grams of sand were contaminated with 785 mg of PCB, which corresponds to 505 ppm of diesel and 523 ppm of PCB, respectively. After contamination, three small samples were taken from each batch and analyzed to control homogeneity.

Treatment with the composition of Example 1: After confirming the homogeneity of the contaminated batches, these were each divided into two: one for the treatment with the composition and one model without treatment. The treatment was carried out by spreading the batches of sand on aluminum trays and spraying them with the composition until the sand got wet. 13 grams of the composition of Example 1 were used for each of the two batches of test sand, 750 grams, corresponding to 1.7% w / w of composition based on the sand samples. After spraying, the sand was dried for 3 hours at room temperature. Two samples from each of the lots were taken and analyzed for homogeneity control.

Leaching procedure: For each component (ie, diesel or PCB), six independent experiments were performed; three with treated sand and three with untreated sand. In each experiment, 100 ml of stimulated rainwater (pH 4.0) was added to 50 g of dry sand sample. The mixture was mechanically stirred for 16 hours. After separation, the water phase was isolated by further analysis.

Chemical analysis: After the addition of internal standards, the water phases mentioned above were extracted with methylene chloride, and the extracts were analyzed by GC-MS. HE . performed the homogeneity tests directly on the sand samples before and after the treatment with the composition by putting out 50 grams of sand, adding internal standards and 5-10 ml of tap water and extracting with methylene chloride for 2 hours.

Results Homogeneity tests: The analyzes for the homogeneity of the contamination were carried out both before and after the treatment with the composition. The normal deviations in the triplicate determinations are shown in Table 1. The results include inhomogeneities in the batches as well as uncertainties in the chemical determination.

Encapsulation of pollutants The analyzes of the batches of sand before and after the treatment showed the quantities of contaminants that can be extracted with the analytical method. The part that after the treatment with the composition can not be extracted could be considered as encapsulated. Table 2 shows the amount of encapsulated contaminants.

Gasoil Table 3 shows the results of the leachate test for diesel. The sand had 25 mg of diesel oil added per 50 g of sand.

Leached from the PCB Table 4 shows the results of the leachate test for the PCB. The sand had 26 mg of the PCB added by 50 g of sand. conclusion The leachate of the diesel oil was reduced by 70%, when the sand was treated with the composition of Example 1. Similarly, the leachate of PCBs from the sand was reduced by 48%. The experiments also showed a reduction in a quantity of contaminants that can be extracted after the treatment of the composition. The diesel was reduced with 61%, while the PCB was reduced with 44%.

EXAMPLE 3 The purpose of the investigations in this example was to compare the fly ash and slag leachate before and after treatment with a composition of the invention to encapsulate the heavy metal-like contaminant components in waste materials such as fly ash and slag, and with which reduce the contamination of groundwater. The tests have been carried out in accordance with the European Prestandard CEN / TC292 / WG2 Doc 25, Tenth Draft: "Compliance test for leaching of granular waste materials and sludges". As the indicators for the leachate, the 5 elements Ni, Cu, Zn, Pb and Cd were selected. The reason for this selection was primarily that these elements give rise to serious environmental problems. Second, Zn was selected because of the high content of this element in both the fly ash and slag.

Procedures Test materials: The tests were performed on both treated and untreated samples of fly ash and slag. The samples were taken from a municipal incineration plant. The results of the chemical analyzes, which show the composition of the materials, are listed in Table 5 below. These results show good agreement with fly ash and typical slag (Niels Thygesen et al .: Risikoscreening af forureningskomponenter udvasket fra slagger, Vandkvalitetsin-stituttet (VKI), Denmark 1992). Due to the nature of the research it is necessary to dry the material and make a size reduction in a jaw crusher to a maximum size of 2 mm.

Table 5: Composition of laboratory samples of fly ash and slag used in the leachate tests Treatment with the composition of Example 1 Part of the dry samples of fly ash and slags were taken and treated with the composition. The treatment was carried out by spreading the waste material in a tray in a uniform layer of approximately 1 cm and spraying it with the composition according to Example 1 until it was all poorly moistened. The amount of the composition used for the spray was 470 ml / kg for the fly ash and 240 ml / kg for the slag. After the spray, the material is air dried for three days before proceeding with the leachate tests.

Lixiviado tests The leachate tests were performed in accordance with CEN / TC292 / WG2 DOC 25 Rev. 10, procedure C This means a two-stage test in L / S = 2 and L / S = 2-10. L / S is an abbreviation for the liquid-to-solid ratio, which describes the relationship between the accumulated amount of liquid (L in liters) that at any given moment has been in contact with the solid (S in kg of dry material). L / S is expressed in 1 / kg. The tests were carried out in 4 different materials: Fly ash treated with composition Dried fly ash Slags treated with the composition Dried slags The details of the test method are described in the normal draft of CEN. In the currently used method, minor changes have been incorporated. In this way, the principle of the modified method is as follows: 200 ml of simulated rainwater (20 mg / l of NaCl adjusted to pH 3.0 with HCl) to 100 grams of waste material.

After half an hour of suspension of the material, the pH was readjusted to 3 with HCl. After shaking the suspension for 6 hours, it was centrifuged, and the centrifuged material was filtered and analyzed. The remaining waste material was resuspended in 300 ml of simulated rainwater, and shaken for an additional 18 hours. After shaking the suspension, it was centrifuged and the eluate was filtered and analyzed. The agitation was carried out in 500 ml glass bottles with sealed teflon screw caps. The stirring temperature was 22 ° C. All the tests were done in duplicate Chemical analysis: All the eluates from the leachate tests were analyzed by the following parameters, the analysis for the metal content was carried out by ICP emission spectrometry (Plasma Coupled by Induction): pH Conductivity Chromium content (Cr) Nickel content (Ni). Copper content (Cu) Zinc content (Zn) Lead content (Pb) Cadmium content (Cd) The analyzes for chromium all showed values below the limit of detection, which was 0.02 mg / kg.

Results 10 Concerning conductivity and pH, the various eluates of the samples gave the following results: Raw fly ash: First eluate: Conductivity, 25 ° C: 131 mS / cm pH: 4.08 Second eluate: Conductivity, 25 ° C: 55.3 mS / cm pH: 5.26 20 Fly ash treated: First eluate: Conductivity, 25 ° C: 121 mS / cm pH: 5.94 Second eluate: Conductivity, 25 ° C: 38 mS / cm 25 pH: 6.32 Untreated slag: First eluate: Conductivity, 20 ° C: 72.5 mS / cm pH: 5.49 Second eluate: Conductivity , 20 ° C: 17.2 mS / cm pH: 6.48 Slag treated: First eluate: Conductivity, 20 ° C: 76.8 mS / cm. pH: 6.10 Second eluate: Conductivity, 20 ° C: 25.6 mS / cm pH: 6.52 The concentrations of each of the 5 elements listed above were measured in two eluates which had subsequently been in contact with the waste material. The analytical results are shown in Tables 6 and 7 below. The total amount of each item was calculated as the cumulative quantity of the 2 eluates, relative to the amount of sample. Table 6 shows the total amount of the washed out elements of the fly ash both treated and untreated. The table also shows the reduction in leachate by treatment with the composition according to Example 1. Table 7 shows the total amount of washed out elements of the slags both treated and untreated. The table also shows the reduction in lixivity by treatment with the composition according to Example 1. conclusion When comparing the leaching properties of waste material before and after treatment with the composition according to Example 1, the results demonstrate that for fly ash, the treatment has resulted in a very effective reduction of heavy metal leachate. , specifically between 50 and as high as 90% depending on the metal of interest. For the slag, the reduction was more varied, going from a relatively small reduction from a low percentage to more than 70%. It is believed that this can be greatly explained by the treatment procedure used without proceeding in the coating of the entire surface and the cavities in the granules of the slag.

EXAMPLE 4 In this example, the product of Example 1 was used to treat contaminated soil covered with an industrial site, the main pollutant that is automobile fuels, in particular diesel. For each sample measurement, 500 g of soil was weighed in a 5 liter plastic bucket. With respect to those samples where slaked lime was added, the lime was added in this time followed by manual agitation to ensure the good mixing of the lime in the soil sample. The quantity indicated in the following table is expressed in parts by weight per 100 parts of soil. The soil sample, with or without added lime, was then treated with the composition of Example 1 in the indicated amount and for the time indicated by the spray of the liquid composition using a hand-held garden sprayer while at the same time the soil sample was stirred. After the spray treatment, the sample was allowed to dry on standing at room temperature for 2 hours under a slight draft of a ventilation hood. The treated samples were then subjected to analysis according to the analytical method of the Danish Oliebranchens Mílj0-polje (Oil Industry Environmental Comittee) for the determination of the oil content in the soil samples. The analytical method is based on solvent extraction and gas chromatography and was carried out along with the following general lines: The soil sample was slurried in 20 ml of a 0.005M sodium pyrophosphate solution, and the mixture it was extracted with 20 ml of pentane on a shaking table for 2 hours. The pentane used contained an internal standard consisting of two compounds, specifically bromobenzene (high volatile pattern) and o-terphenyl (low volatile pattern). The gas chromatographic analysis was carried out at a relatively low temperature (approximately 35 ° C) and the calculation of the content of oil components was carried out in a normal manner by integrating the curved areas for the components having retention times corresponding to the alkane series of 6 to 10 carbon atoms, the alkane series of 10 to 28 carbon atoms and the alkane series of 28 to 35 carbon atoms. Also included in the analysis program was a reference sample of untreated soil as well as a sample treated with water only in order to establish any effect exerted by the water content of the composition of Example 1. The results obtained are shown in the Table 8 later.

Table 8 From the results it can be observed that although the water and the manual treatment caused a smaller reduction of the organic matter that can be extracted, the composition according to the invention, when used alone, caused a high reduction of organic matter which can be extracted, specifically up to 80% with a certain dependence on the amount of the composition added. In addition, when soil contaminated with slaked lime is also previously treated, the reduction in organic matter that can be extracted reaches as high as 99%. Without being bound by any theory, it is believed that since slaked lime adds soluble calcium ions to the system, and the polymerization or gelation of the dissolved silicates is improved in the presence of divalent ions, the slaked lime probably contributes to the encapsulation of contaminants by improving the gelation reaction.

EXAMPLE 5 This example deals with the properties of the compositions of the invention with respect to inflammable and inflammable objects and materials, in this case various types of cardboard.

Experiment a) Approximately 100 g of finely ground newspaper was treated with a sufficient amount of the composition of Example 1 to soak all the newspaper paper. The wet mass was then manually compressed to a wet board followed by drying at 110 ° C for 20 minutes and cooling to room temperature for 1 hour and subsequent drying at room temperature for 2 days, dry board measured 290 mm by 200 mm by 18.5 mm thick and had a density og 677 kg / m3. The cardboard was analyzed in accordance with ISO 2856 (a civil aviation materials test pattern) that involves heating with a propane burner. In this test, the material was subjected to the flame of a standard propane burner ISO 2685: 1992 (E) 178 mm in diameter at a distance of 75 mm from the burner. The temperature of the flame was monitored by means of thermocouples near the surface of the material, and the unexposed side of the material also had thermocouples mounted on it. The maximum temperature reached was 1080 ° C and the total exposure time was 15 minutes. Up to approximately 13 minutes after the initiation of the test, there was no visible flame attributable to the material; only small amounts of smoke could be observed on the back and the unexposed side of the board with a slight increase in smoke development over time. In the 13 minutes after the start and until the end of the test (15 min.), Intermittent to sustained flames could be observed on the non-exposed side. After the burner was removed after 15 minutes, the flames continued for an additional 1.3 minutes, after which the flames extinguished by themselves. The measurements of the cardboard after the test revealed that it had shrunk slightly in width and had lost approximately 80% by weight and had a hard surface coating. It is concluded that the composition of the invention is highly effective in inflammable flame retardant materials.

Experiment b) A mixture of 150 g of detoxified hemp fibers was mixed with 200 g of the composition of Example 1 followed by compression and drying in the same manner as in Experiment a). The cardboard obtained was attached to the flame of a Bunsen gas burner (approximately 800 ° C) for 15 minutes. No deterioration was observed (apart from some blackening).

Experiment c) A mixture of 220 g of wood sawdust, 100 g of polyvinyl alcohol glue solution (Unibond), 75 g of a 5 mm paper plate, 100 g of the composition of Example 1 and 750 ml of water, it was mixed well and compressed at a pressure of 2 bar to remove the excess fluid, and then dried with air at room temperature for 36 hours. The resulting dry cardboard was heated to 800 ° C as in experiment b), and no deterioration was observed, and no toxic fumes were developed.

EXAMPLE 6 This example is about the encapsulation of a waste containing heavy metals, specifically residues from the fluorescent tube, the primary contaminants of which are mercury, cadmium, zinc, copper and arsenic. First, the aluminum end caps of a tube were removed and the glass tube itself with the contaminants cracked into fine fragments. The broken tube (47 g) was mixed dry with 100 g of 10 mm paper plates. They mixed well 120 g of water and 20 g of PVA (polyvinyl alcohol) in a fluid composition followed by the addition of 100 g of the composition of Example 1 and again mixed again. The mixture of broken glass and paper was added to the fluid mixture and mixed well in a mixer for 5 minutes, and by means of a chopping or grinding machine, the mixture was fed into a plastic, cylindrical cover and was maintained at 24 ° C for 12 hours in a heating element. The plastic cover was removed, and the resulting cylindrical body was allowed to air dry at room temperature for 12 hours. The resulting solid body showed no signs of edge crushing or fragmentation.

EXAMPLE 7 Pollution treatment of portable firearms.

A sample of 50 grams of Pyrodex (a Hercules double base fumigation gunpowder, USA) was placed on a sheet of paper and sprayed with a sufficient amount of the composition of Example 1 to moisten each grain and mix. The black powder granules became a gray paste, and the paste was spread on the paper and dried for about half an hour at room temperature. After drying, an attempt was made to ignite a sample of the dust treated with a welding lamp or to burn propane paint (flame temperature of approximately 1000 ° C), but no explosion or burning was observed. Comparative tests using the same powder treated in the same manner with the composition of Example 1 diluted with water (1 part of the composition, 4 parts of water) resulted in the powder exploding or being violently burned when attached to the lamp of welding or burning propane paint. Therefore, it was concluded that the composition of the invention is highly effective in the conversion of the harmless polluting powder.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following claims is claimed as property.

Claims (12)

1. A composition of an aqueous solution containing silicate, characterized in that it comprises: a) from 10% w / w to 50% w / w of a silicate compound selected from sodium and potassium silicates, or a mixture of such silicate compounds; b) from 1% w / w to 5% w / w of a salt, the cations of which are selected from sodium and potassium ions, and the anions from which they are selected from halogen, sulfate and carbonate ions, or a mixture of such salts; c) from 0.25% w / w to 5% w / w of ethylene glycol; and d) water.

2. A composition according to claim 1, characterized in that the silicate compound is a sodium silicate.

3. A composition according to claim 2, characterized in that the sodium silicate has a molar ratio of Na20: Si2 in the range of about 4: 1 to about 1: 4, preferably from about 1: 1 to about 1. :4.

4. A composition according to claim 3, characterized in that the sodium silicate has an average formula of Na2Si03, Na6YES2? , Na2Si30 or Na2Si409, or mixtures thereof, in particular Na2SÍ3? .

5. A composition according to any of claims 1-4, characterized in that the silicate compound is present in an amount of 13-31% w / w, preferably 15-31% w / w. in particular 18-31% p / p, especially 21-31%, such as approximately 27% p / p-

6. A composition according to any of claims 1-5, characterized in that the salt is sodium chloride.

7. A composition according to any of claims 1-6, characterized in that the salt is present in an amount of 1-4% w / w, preferably 2-4% w / w, in particular about 3% w / w .

8. A composition according to any of claims 1-7, characterized in that the ethylene glycol is present in an amount of 0.5-4% w / w, preferably 0.5-3% w / w, in particular, 0.5-2% p / p, especially 0.5-1% w / w, such as 0.7% w / w.

9. A composition according to any of claims 1-8, characterized in that it comprises about 27% w / w of sodium silicate having an average formula near Na2Si307 (with a molar ratio of Na20: SiO2 of 1: 3.1), approximately 0.7 p / p of ethylene glycol and approximately 3% w / w of sodium chloride, the rest being water.

10. A method for encapsulating the contaminants, the method is characterized in that it comprises applying to the contaminants or the material containing them, a sufficient amount of a composition according to any of claims 1-9.

11. A method for the ignifugation of a flammable solid, the method is characterized in that it comprises applying to the flammable solid a sufficient quantity of a composition according to any of claims 1-9.

12. A method for extinguishing a fire, the method is characterized in that it comprises applying to the fire a sufficient quantity of a composition according to any of claims 1-9. * ((. "T" * i t 45 SUMMARY OF THE INVENTION A composition of an aqueous solution containing silicate, comprising: a) from 10% w / w to 50% w / w of a silicate compound selected from sodium and potassium silicates, or a mixture of such silicate compounds; b) from 1% w / w to 5% w / w of a salt, the cations of which are selected from sodium and potassium ions and the anions from which 10 are selected from halogen, sulfate and carbonate ions, or a mixture of such salts; c) from 0.25% w / w to 5% w / w of ethylene glycol; and d) water. The silicate compound is preferably sodium silicate, especially sodium silicate. 15 having an average formula of Na2Si03, NaeSi207, Na2Si307 or Na2Si 0., or mixtures thereof. S is preferably sodium chloride. The composition is useful in the encapsulation of contaminants, inflammable flame-retardant materials and in the 20 extinguishing the fire. 25