FR2924948A1 - Liquid, aqueous, acidic formulation, useful to treat coatings or composite materials based on plaster and asbestos fibers, comprises water soluble acidic products, complexing agent of alkaline earth elements, and soluble surfactant - Google Patents

Abstract

Liquid, aqueous, acidic formulation, comprises: one or more water soluble acidic products; a complexing agent of alkaline earth elements; and soluble surfactant compatible with the acidic medium, to treat the coatings or composite materials based on plaster and asbestos fibers for disintegrating and facilitating removal. An independent claim is included for a process for using the formulation, comprising spraying the liquid formulation under low pressure on the asbestos material to be disintegrated.

Description

AQUEOUS, ACIDIC LIQUID FORMULATION FOR FACILITATING THE DISAGGREGATION AND REMOVAL OF AMIANT MATERIALS. The present invention relates to a formulation, aqueous liquid, acid, sprayable under pressure, intended to disintegrate composite materials based on hydraulic binders, in particular calcium sulphate, and containing, among other additive, asbestos fibers. The invention also relates to the method of implementing this formulation.

In the latter half of the 20th century, large quantities and large varieties of coating formulations containing asbestos fibers have been used in building and construction in general. These coatings were put in place to fulfill various objectives, among others, sound and heat insulation objectives and fire-fighting objectives. In particular they must delay as much as possible the moment of collapse of concrete structures or metal structures in case of fire. They are therefore found 20 especially on concrete ceilings and on structural elements, in particular metal.

Since the dangers of asbestos, and in particular of its divided forms (dust) are now well established, it is necessary to remove these asbestos coatings, especially in public buildings. This work of asbestos removal must be done under very strict conditions of hygiene and safety, and is therefore strictly regulated.

The invention particularly relates to the removal of ceiling tile coatings which contain among other components, plaster, possibly calcium carbonate and asbestos fibers. This mixture is projected, in the form of an aqueous suspension, and adheres after hydraulic setting of the plaster on the surfaces to be protected. The product is known commercially in various forms, the most common being the Progypsol brand.

The removal of this product, during the asbestos removal of buildings, is made difficult by the fact that it has good mechanical strength. Its elimination most of the time, can be achieved only manually, which makes the operation long, expensive and very painful for the operators.

However, it is currently favored by the water spray, which softens the product a little, but which also has other disadvantages on the working conditions.

The invention therefore relates to an aqueous formulation, sprayable as water alone, but in much less amount, and quickly disintegrates the coated coating, so greatly facilitate its removal by scraping and the speed of achieving this withdrawal.

Most fire-retardant coatings, also known as retarders, contain, among other things, products that expand in volume by heat. This expansion is obtained by a gassing, in particular CO2 carbon dioxide, and as such these formulations often contain alkaline earth carbonates.

The product according to the invention, which aims to disintegrate the coating, is an acid composition, but not corrosive, odorless, containing active ingredients whose actions will be added to lose its mechanical strength to said coating.

The composition according to the invention is a liquid, aqueous, acidic formulation containing one or more acidic products, soluble in water. A complexing agent for alkaline earth metals. A soluble and acid-compatible surfactant for treating plaster and asbestos-containing coatings or composite materials to disintegrate them and facilitate their removal. This composition contains mainly:

An organic acid soluble in water, odorless or weakly scented, capable of solubilizing the hydraulic binder and especially plaster (or gypsum, or calcium sulfate in hydrated forms) to decompose the calcium carbonate, but not corrosive vis-à-vis screw metals.

A surfactant, wetting compatible and soluble in acidic media, intended to accelerate the penetration of the product in the core of the material to be disintegrated.

An organic complexing agent of alkaline earth elements, particularly calcium, compatible and soluble in acidic media, intended to accelerate, by its complexing role, the rate of dissolution of calcium sulfate (plaster) in the acid medium.

- Water This liquid formulation, aqueous acid, is characterized in that the acid product or products are selected from odorless organic acids and classified non-corrosive. The organic acids will be particularly selected from citric, lactic, sulfamic, tartaric, adipic, succinic, glutaric, maleic acids, alone or in mixture with one another. Of course it could have been advantageous to use strong acids such as hydrochloric acid or sulfuric acid at appropriate dilutions. The disintegration efficiency of the composite had been higher and especially faster. But the notorious disadvantages such as the aggressiveness of the manipulators and the 3o risks of corrosion of the various parts of the buildings mean that these acids are not claimed in the preferred forms of the invention. Similarly, it is preferable to avoid the use of odorous acid products that may be inconvenient for operators and neighbors, such as acetic acid, sometimes cited in the public domain as an acid capable of eliminating plaster based stains. . The organic complexing agents will be chosen from amino-acetic, aminophosphonic or phosphonic acid, in acid form or in the form of salts, in particular sodium. Such additives may be chosen from organic phosphonated amino-complexing agents, and more particularly from sodium ethylene diaminotetraphosphonate and sodium diethylenetriaminopentaphosphonate, known under the trade names Briquest 4230 and Briquest 543, or the Dequest products. equivalent to Briquest.

The surfactant may be an anionic product, a cationic product, a nonionic product, an amphoteric or zwitterionic product, but more particularly an amphoteric agent or a nonionic agent. The formulation according to the invention will be characterized in that the surfactant is selected from amphoteric and / or nonionic compounds; Such additives may be chosen from organic surfactants of the amphoteric family, of general formula R 1 N + (CH 3) 2 CH 2 -COO-, with R = C 8 to C 18, and more specifically commercial products such as Mirataine H2CHA, 15 or Mirataine. JCHA corresponding to the formula: CHùCHù000H RùN: z Hz CHZ COONa For nonionic surfactants, they will be chosen in particular in the products of ethoxylation and or of propoxylation of fatty alcohols or fatty acids

The proportions of each component will be between:

For the acid or mixture of acids, 2 and 60%, preferably 5 and 30% expressed as active ingredients. For the surfactant, from 0.1 to 10%, preferably from 1 to 5%, expressed as active ingredients. For the complexing agent, from 0.1 to 30%, preferably from 1 to 10%, expressed as active ingredients; The complement to 100 of the formulation consists of water, and can be in particular of city water distributed by the public water networks. The process according to the invention consists in spraying the above-described formulation with a liquid-pressure sprayer (single-fluid nozzle of the Airless type), under reduced pressure (0.5 to 3 kg), on the material that has been aminated. to disintegrate. The wetting proportions, expressed in kg of liquid formulation per kg of coating, are between 0.05 and 0.7, preferably between 0.1 and 0.4.

The formulation is allowed to stand and act before it is scraped off for at least 1 hour, preferably 12 hours. Advantageously, the spraying can take place the day before the evening of the beginning of the removal, and be renewed once if necessary, before the intervention.

The present invention will be better understood through the following exemplary embodiments:

Example 1

100 liters of the following composition are prepared in a dissolver mixer of suitably stirred liquids:

City water 50% Adipic acid, succinic, glutaric acid mixture (1) 20% Briquest 422 25S (2) 25% 25 Mirataine JCHA (3) 5%

(1) Product sold under the name AGS and containing 30% adipic acid, 30% glutaric acid, and 40% succinic acid. (2) Complexing agent in 25% solution in water (sodium tetraaminophosphonate) (3) Amphoteric surfactant in 42% solution in water.

The composition is mixed until a liquid is obtained. homogeneous, that is to say until complete dissolution of the AGS mixture.

The product thus obtained is kept in storage under frost-free conditions, to avoid the risk of crystallization. It is referenced under the trade name ATP Sol 2 in the following example.

Example 2

Three pieces of samples of approximately 20 g of Progypsol, handled with the necessary precautions (dust mask, gloves) are placed in glass cups and then immersed in an excess of aqueous liquid (50 cc), which is:

Pure water, as a control for the first sample A mixture of 20% AGS acids in water for the second sample The formulation of Example 1, ATP Sol 2, for the third sample.

The 3 systems thus obtained are left standing for 12 hours, then the 3 cups are visually observed and photographed under a predominantly red artificial light. The visual observation makes it possible to conclude that the formulation 20 according to Example 1 has a higher efficiency than that of immersion in pure water, but also with regard to immersion in a simple acid mixture at the same concentration as the formulation according to Example 1. The accompanying photograph is eloquent and confirms the visual impression.

Claims (9)

1) Liquid, aqueous, acidic formulation, containing: - One or more acidic products, soluble in water. A complexing agent of the alkaline earth elements. A soluble and acid-compatible surfactant for treating coatings or composite materials based on plaster and asbestos fibers to disintegrate them and facilitate their removal. 2) liquid formulation, acidic aqueous, according to claim 1characterized in that the acid product (s) are (are) chosen from odorless and non-corrosive organic acids. 3) aqueous liquid formulation, acid, according to the preceding claim, characterized in that the acids are selected from citric acid, lactic, sulfamic, tartaric, adipic, succinic, glutaric, maleic. 4) Formulation according to claim 1, characterized in that the complexing agent is selected from aminoacetic compounds, aminophosphonic or phosphonic, in acid form or in the form of salts, especially sodium. 25 5) Formulation according to claim 1, characterized in that the surfactant is selected from amphoteric and / or nonionic compounds; 6) Formulation according to one of the preceding claims, characterized in that the acid content (expressed as active material) is between 2 and 60%, preferably between 5 and 30% expressed as active ingredients. 7) Formulation according to one of the preceding claims, characterized in that the surfactant content is between 0.1 and 10%, preferably between 1 and 5% expressed as active ingredients. 8) Formulation according to one of the preceding claims, characterized in that the content of complexing agent (expressed as active materials) is between 0.1 and 30%, preferably between 1 and 10% expressed as active ingredients. 9) A method of using the formulation according to one of claims 1 to 8, characterized in that the liquid formulation is sprayed under low pressure on the host material to be disaggregated 20 45