EP3286354B1 - Use of alkane sulfonic acid for cleaning in the sugar industries - Google Patents

Description

The present invention relates to the field of sugar industries, and more particularly the cleaning of installations, including reactors, evaporators, containers, valves, pipes, pipes and others, used in the manufacture of sugar from natural plant materials, such as for example sugar cane or sugar beet.

When preparing sugar from plants, the sugar industry uses evaporators to concentrate the juices. During these concentrations of deposits appear over time. The accumulation of these deposits can cause disruptions in heat exchanges or even prevent some heat exchanges, which can lead to very significant economic consequences.

So it is necessary to clean such deposits, when they become too important and they finally hinder the manufacturing yields. These cleaning phases require manufacturing stops, and must therefore last as short as possible, while of course being as effective as possible.

Today, the cleaning of these deposits takes place most often chemically, with chelating agents, such as the sodium salt of EDTA, as described for example in the application WO2003 / 106735 or in acid medium, for example using hydrochloric acid, but also sulfamic or sulfuric acid, as described for example in "Chemical cleaning of sugar mill evaporators", WOS Doherty, Proc. Aust. Soc. Sugar Cane Technol., (2000), 22, 341-346 .

These deposits encountered in the sugar industry generally consist of a type of scale composed of various elements including salts, such as calcium carbonate, calcium oxalate, iron oxides, calcium phosphate, hydroxyapatite and aconitate, most often calcium and / or magnesium, as described in "Development of Descriptor Tools for the Characterization of Australian Sugar Mill Evaporator Scale", DW Rackemann et al., Proc. Int. Soc. Sugar Cane Technol., (2010), 27, 1-12 .

The problem encountered in the cleaning of this type of pie is the great difficulty of solubilizing aconitates, or salts of aconitic acid. Aconitic acid is equivalent to dehydrated citric acid and is predominantly in trans form in cane and beet sugar. Aconitic acid is found mainly in the form of tri-calcium salts and di-calcium and magnesium mixed salts, which are not available commercially.

However, even today, the literature hardly describes the problem related to the difficulty of solubilization of aconitates, an example being the elimination of these salts by washing with chelating agent solution such as EDTA salts as indicated above. (cf. WO2003 / 106735 or "Development of Descriptor Tools for the Characterization of Australian Sugar Mill Evaporator Scale", DW Rackemann et al ., ibid ., so that those skilled in the art today know only the effectiveness of EDTA salts for the removal of deposits in the sugar industry.

However, EDTA is now considered to pose risks to the environment, especially the aquatic environment, when it is used as a raw material for detergents. In addition, the biodegradability of EDTA is less than 10% (cf. European Union Risk Assessment Report, edetic acid (EDTA), PL-1, 49, (2004) )).

According to the work reported in "Chemical cleaning of sugar mill evaporators", WOS Doherty, Proc. Aust. Soc. Sugar Cane Technol., (2000), 22, 341-346 It is, however, learned that dilute acids, such as sulphamic acid, hydrochloric acid, and sulfuric acid, permit a slow attack of the salts of aconitic acid.

In spite of its effectiveness, hydrochloric acid (HCl) nevertheless has many drawbacks, among which mention may be made of the release of toxic, nauseating, irritating and tear vapors, as well as the problems of effluents due to the large quantities of chlorides discharged into the environment.

On the other hand, because of its chemical nature, the concentration of HCl is limited to about 37%, whereas it could be interesting, even desirable to have much higher acid concentrations to eliminate in particular all the deposits which accumulate during the preparation of the sugar.

Sulfuric acid is little used industrially, especially because of its corrosive nature. Similarly, sulphamic acid, whose releases are considered harmful to the environment, especially for aquatic organisms, is not an acid that can be widely used on an industrial scale.

Still other acids could be used, such as phosphoric acid, the release of phosphates, however, a major problem for the environment. Indeed, the use of phosphoric acid is today more than disputed, because of the releases of phosphates that it generates.

It has also been envisaged to use organic acids, such as, for example, acetic, citric, oxalic, glycolic, lactic, formic acids, etc. However, their acidity is lower than the aforementioned mineral acids, their effectiveness is lower and requires the use of larger quantities of products. WO 2008/144501 A2 describes a method of cleaning the residues of etching compositions comprising the use of a solution containing at least one C1-C6 alkylsulfonic acid.

In addition, some of the aforementioned acids are in solid form, which leads to handling and formulation difficulties (powdered powders), and therefore are not preferred acids for the use of the present invention. In addition some of these organic acids are considered harmful. This is particularly the case of oxalic acid and glycolic acid.

The work of DW Rackemann et al. ("Enhanced performance of caustic soda used for the removal of scale in sugar mill evaporators", International Sugar Journal, (2008), 110, 344-349 ) teach that sodium hydroxide is ineffective in dissolving calcium salts including calcium aconitate. In addition, the washing with sodium hydroxide must be followed by an acid wash (phosphoric acid, formic acid, sulphamic acid, sulfuric acid, hydrochloric acid). However, this process is inefficient because sodium hydroxide residues neutralize the acid and it is advisable to replace the acid with EDTA.

Thus, a suitable formulation appears to be a formulation containing 13% sodium hydroxide, 10% EDTA and 2% sodium gluconate. EDTA, however, is not a product that can continue to be used, especially for the reasons mentioned above.

There remains therefore a need for products, formulations and processes making it possible to overcome the disadvantages previously listed, in particular a need for acids which make it possible to effectively remove the deposits observed in the installations used for the manufacture of sugar, in particular with regard to from raw materials of plant origin and especially from sugar cane and sugar beet, and more generally in installations used for processes involving at least one step of evaporation of water from a mixture comprising at least one salt of aconitic acid capable of depositing.

In particular, there remains a particular need for products, formulations and processes for rapidly and effectively solubilizing the salts of aconitic acid, and in particular the magnesium and / or calcium salts of aconitic acid, while preserving the environment, ie products, formulations and processes which comply with the environmental and labor standards in force, and which do not have the drawbacks associated in particular with irritating gas emissions associated with the use of acid hydrochloric acid, or related to corrosive effects, including sulfuric acid.

Thus, a first object of the present invention is to provide products and formulations that are effective for the dissolution of the salts of aconitic acid in particular, and more generally, processes for cleaning deposits encountered in sugar-making installations, in particular particularly in the sugar industries.

Another object of the present invention is to provide an effective alternative to the acids commonly used in this application while avoiding discharges and effluents harmful to the environment, as well as toxic and nauseating gas emissions.

Other objects and advantages will become apparent from the description of the present invention which follows, which invention makes it possible to achieve the aforementioned objectives in whole or at least in part. Indeed, the Applicant has now discovered that it is possible to effectively clean solid deposits comprising at least one salt of aconitic acid, and this without the need to use EDTA, the salts of EDTA or the strong organic acids known from the prior art.

In the description of the invention which follows, the term "cleaning" is understood to mean the elimination and / or dissolution of deposits comprising at least one salt of aconitic acid, preferably a calcium salt and / or magnesium, this elimination may be partial or total, preferably total, without the aforementioned drawbacks, in particular the disadvantages on the environment, the disadvantages of gaseous releases and others, as will be described now.

It has thus been discovered that it is possible to effectively clean solid deposits comprising at least one aconitic acid salt and usually encountered in industries employing at least one step of evaporation of water from a mixture comprising at least one salt of aconitic acid capable of depositing, using a formulation based on at least one alkanesulphonic acid.

The formulations based on at least one alkane-sulphonic acid have, in particular, an efficacy at least equal to, or even improved, with respect to the hydrochloric acid which is the acid usually used in this field, or even with respect to the salts of the ethylenediaminetetraacetic acid (EDTA).

The alkane-sulphonic acids have the advantage of being less corrosive than hydrochloric acid, of not generating chlorides, of being biodegradable and of not giving off toxic or foul-smelling products, as well as of to be less polluting than phosphoric acid, because of the phosphates released into the environment. In addition, the alkanesulfonic acids can be used in more than concentrated form than hydrochloric acid.

As already indicated, the use of the present invention finds applications quite interesting in industries employing at least one step of evaporation of water from a mixture comprising at least one aconitic acid salt capable of deposit, and in particular during the manufacture of sugar from natural plant materials, such as for example sugar cane or sugar beet.

Indeed, the formulations based on (s) alkane-sulfonic acid (s) have in particular a greater ease of use and handling compared to products and formulations usually used for cleaning solid deposits comprising salts of aconitic acid. Indeed, the use of formulations based on alkane-sulfonic acid (s) produces no or few toxic, irritating or tear gas emissions.

Thus, and according to a first aspect, the present invention relates to the use of at least one alkanesulphonic acid of formula R-SO ₃ H, where R represents a saturated hydrocarbon chain, linear or branched, comprising from 1 to 4 atoms of carbon, for cleaning solid deposits comprising at least one salt of aconitic acid.

As indicated above, this type of solid deposition is usually encountered in industries employing at least one step of evaporation of water from a mixture comprising at least one salt of aconitic acid capable of depositing, and in particular during the manufacture of sugar from natural plant materials, such as for example sugar cane or sugar beet.

Thus, the invention relates to the use of at least one alkane-sulphonic acid as an active compound for cleaning solid deposits comprising at least one aconitic acid salt, said solid deposits being usually encountered in industries employing at least one step of evaporation of water from a mixture comprising at least one salt of aconitic acid capable of depositing, and in particular during the manufacture of sugar from natural plant materials, such as for example the cane sugar or sugar beet.

More particularly, the invention relates to the use of at least one alkanesulphonic acid for cleaning surfaces soiled by solid deposits comprising at least one aconitic acid salt, on all types of surfaces.

More specifically, the present invention provides a formulation, able in particular to replace the use of hydrochloric acid, for cleaning deposits comprising at least one salt of aconitic acid, or more simply "aconitates" in the rest of this exposed, said formulation comprising at least one alkanesulfonic acid which is a biodegradable acid, low toxicity, not releasing or little irritating or tear gas, not generating effluents harmful to the environment and can be used in form more concentrated as hydrochloric acid.

The aconitates, and in particular the aconitates encountered in the sugar industry are well known to those skilled in the art and lead, especially after many cycles of evaporation of aqueous sugar solutions, to solid deposits, more or less compact. The aconitates encountered are mainly aconitates of calcium and / or magnesium, and may be present in solid deposits in combination with other salts. As illustrative and nonlimiting examples of other salts that may be present in the solid deposits, mention may be made of carbonates, such as calcium carbonate, phosphates, such as tricalcium phosphate, hydroxyapatite, oxalates, such as calcium oxalate, sulphates, such as calcium sulphate, iron oxides, and others.

The use of the present invention allows the cleaning of aconitates, and more generally deposits comprising at least one aconitate, and which may be present on all types of surfaces, in particular hard surfaces, especially metallic surfaces (iron, aluminum, steel and the like). ), wood, polymers (plastics, paints, lacquers, varnishes), glasses, stones, ceramics, porcelains, terracotta, and others.

For the purposes of the present invention, the term "cleaning" is understood to mean the cleaning, stripping, of all types of surfaces, as indicated above, soiled, coated, covered, in whole or in part by residues, scales, deposits , dry or still wet, generated during the preparation of products obtained from plants and in particular from sugar cane or sugar beet, by elimination, dissolution, said residues, scales and deposits in general.

As indicated previously, the term "cleaning" also includes the partial or total elimination of solid deposits, comprising at least one aconitate, and which may have taken up unexpectedly, undesirably or undesirably in the installations. including reactors, evaporators, containers, valves, pipes, pipes and the like, used in the manufacture of sugar from natural plant materials, such as, for example, sugar cane or sugar beet, which are usually removed / removed by other chemical and / or mechanical means, such as brushes, trowels, shovels, pickaxes, hammers, jackhammers and others.

In the present invention, the term "alkane-sulphonic acid" is understood to mean alkanesulphonic acids of formula R-SO ₃ H, where R represents a linear or branched saturated hydrocarbon-based chain containing from 1 to 4 carbon atoms.

The alkane-sulphonic acids that can be used in the context of the present invention are preferably chosen from methanesulfonic acid, ethanesulfonic acid, n-propanesulfonic acid, iso- propanesulfonic acid, n-butanesulfonic acid, iso- butanesulfonic acid, sec- butanesulfonic acid, tert- butanesulfonic acid, and mixtures of two or more of them in all proportions.

According to a preferred embodiment, the alkane-sulphonic acid used in the context of the present invention is methanesulfonic acid or ethanesulphonic acid, and the acid used is preferably the acid. methanesulfonic.

Thus, the use according to the present invention uses at least one alkane-sulphonic acid chosen from linear or branched chain alkane sulphonic acids containing from 1 to 4 carbon atoms, and preferably at least methane acid. sulfonic (AMS).

Said at least one alkane-sulphonic acid that can be used in the context of the present invention can be used as it is, or in combination with one or more other components, that is to say in formulation. Any type of formulation comprising at least one alkanesulphonic acid may be suitable. As a rule, the formulation comprises from 0.01% to 100% by weight of alkanesulfonic acid, more generally from 0.05% to 90% by weight, in particular from 0.5% to 75% by weight, inclusive limits, of alkane-sulfonic acid (s), relative to the total weight of said formulation.

The formulation is, for example, an aqueous, organic or even hydro-organic formulation. The formulation may be prepared as a concentrated mixture, wherein the concentrated mixture may be diluted by the end user. Alternatively, the formulation may also be a ready-to-use formulation, i.e., it does not need to be diluted. Finally, within the meaning of the present invention, the formulation may be a pure alkanesulfonic acid, or a mixture of pure alkanesulphonic acids, that is to say that the formulation may contain only one or more acids. -sulfonic, with no other formulation additive or other solvent or diluent.

The concentration of alkane-sulfonic acid (s) in the formulation depends on many factors, among which may be mentioned the amount of deposits to be cleaned, the nature and shape of the surface to be cleaned, the temperature to which is applied formulation, and others. Those skilled in the art will be able to adapt, without undue effort, the appropriate concentration of acid in the formulation.

Concentrated solutions, for example from 60% to 100%, preferably from approximately 70% to 100% by weight of alkane-sulphonic acid (s), are thus preferred, relative to the total weight of said formulation, when it is desired to remove large amounts of deposits, or on the surface of materials that are not very sensitive to acid attacks. Less concentrated solutions of 0.01% to 60%, preferably 0.05% are preferred. at 50% for smaller quantities of deposits to be removed, or for the cleaning of deposits still wet, and / or on surfaces sensitive to acid attacks.

It is possible, for example, to use methanesulfonic acid in aqueous solution sold by Arkema under the name Scaleva®, or else under the name Lutropur® marketed by BASF, ready-to-use or diluted with water. in the proportions indicated above.

• solvants, agents hydrotropes ou solubilisants (par exemple alcools, esters, cétones, amides, et autres),
• biocides, désinfectants (acide bromo-acétique, acide peracétique, eau oxygénée, et autres),
• agents rhéologiques ou de texture ou épaississants ou gélifiants (sucres, polysaccharides, alginates, silice, silice amorphe, gommes et autres),
• acides organiques ou minéraux (par exemple sulfurique, phosphorique, nitrique, sulfamique, acétique, citrique, formique, lactique, glycolique, oxalique et autres),
• sels d'alcalins, d'alcalino-terreux, de métaux, en particulier les fluorures, chlorures, iodures, bromures d'alcalins et/ou d'alcalino-terreux, de préférence les chlorures et les fluorures, de préférence encore les fluorures, notamment les fluorures de sodium ou de calcium,
• retardateurs de flamme,
• conservateurs,
• tensio-actifs anioniques, cationiques, non-ioniques ou amphotères (tels que alcools et/ou amines éthoxylés, alkyl- et/ou aryl-sulfonates) émulsifiants, détergents, savons, et autres ;
• agents moussants, antimoussants,
• anti-gels (par exemple ethylèneglycol, propylèneglycol, et autres) ;
• colorants,
• inhibiteurs de corrosion,
• parfums, agents odorants,

et autres additifs connus de l'homme du métier.In addition to the alkane-sulfonic acid or acids, the formulation used in the present invention may optionally comprise one or more additives well known to those skilled in the art, such as those chosen from:

• solvents, hydrotropic or solubilising agents (eg alcohols, esters, ketones, amides, and others),
• biocides, disinfectants (bromoacetic acid, peracetic acid, hydrogen peroxide, and others),
• rheological or texturizing agents or thickeners or gelling agents (sugars, polysaccharides, alginates, silica, amorphous silica, gums and others),
• organic or inorganic acids (eg sulfuric, phosphoric, nitric, sulphamic, acetic, citric, formic, lactic, glycolic, oxalic and others),
• salts of alkalis, alkaline earth metals, in particular fluorides, chlorides, iodides, bromides of alkali and / or alkaline earth metals, preferably chlorides and fluorides, more preferably fluorides, in particular sodium or calcium fluorides,
• flame retardants,
• preservatives,
• anionic, cationic, nonionic or amphoteric surfactants (such as ethoxylated alcohols and / or amines, alkyl and / or aryl sulfonates), emulsifiers, detergents, soaps, and the like;
• foaming agents, antifoam agents,
• anti-gels (e.g. ethylene glycol, propylene glycol, and others);
• colorants,
• corrosion inhibitors,
• perfumes, odorous agents,

and other additives known to those skilled in the art.

The formulation in aqueous form is particularly advantageous in the so-called "cleaning in place" (or "cleaning in place" or "CIP" in English language) processes.

In addition, the use of alkanesulfonic acid (s), in particular methanesulfonic acid, makes it possible to control the acid content, in order to be able to adjust the acidity of the cleaning solution in the best possible way for a cleaning. Optimal reactors, pipes, evaporators .... This control of the acid content can be achieved by any method known per se, and for example by conductivity.

According to one variant, the formulation is a formulation in the form of a gel. It has indeed been observed that the formulations in the form of alkane-sulfonic acid (s) gel (s) are very effective for the removal of deposits comprising aconitates, as described above, not only because of the gel itself. even which allows a longer action of the acidic active principle (the gel "adheres" longer to the surfaces, compared to an aqueous formulation), but also has an improved cleaning power, compared to other gel formulations.

• de 0,01 % à 97 % en poids, de préférence de 0,05 % à 75 % en poids et plus particulièrement de 0,5 % à 70 % en poids, d'au moins un acide alcane-sulfonique, de préférence l'acide méthane-sulfonique ;
• de 0,1 % à 30 % en poids, de préférence de 0,5 % à 15 % en poids et plus particulièrement de 1 % à 10 % en poids, d'au moins un agent gélifiant ;
• de 0,1 % à 30 % en poids, de préférence de 0,5 % à 15 % en poids, d'au moins un additif choisi parmi ceux cités ci-dessus ; et
• le complément à 100 % d'eau et/ou solvant organique,

pour le nettoyage des dépôts solides comprenant au moins un sel d'acide aconitique.Thus, in another aspect, the present invention relates to the use of a gel form formulation comprising:

• from 0.01% to 97% by weight, preferably from 0.05% to 75% by weight and more preferably from 0.5% to 70% by weight, of at least one alkanesulfonic acid, preferably methanesulfonic acid;
• from 0.1% to 30% by weight, preferably from 0.5% to 15% by weight and more preferably from 1% to 10% by weight, of at least one gelling agent;
• from 0.1% to 30% by weight, preferably from 0.5% to 15% by weight, of at least one additive selected from those mentioned above; and
• the complement to 100% of water and / or organic solvent,

for cleaning solid deposits comprising at least one aconitic acid salt.

The gelling agents and the surfactants that can be used in the formulations in the form of a gel can be of any type. The person skilled in the art will know, without particular difficulty and drawing inspiration from the examples which follow, to choose and adapt the nature of the gelling agents and the appropriate surfactants.

In another aspect, the present invention relates to the use of a foaming gel formulation. Foaming gels are indeed everything particularly interesting because they produce a sticky foam, that is to say a foam adhering to soiled surfaces, while generally requiring a lower consumption of cleaning acid active ingredient, and have the advantage of being rinsed quite well effective, that is to say to be eliminated in a simpler and more efficient way, while requiring less water.

• de 0,01 % à 97 % en poids, de préférence de 0,05 % à 75 % en poids et plus particulièrement de 0,5 % à 70 % en poids, d'au moins un acide alcane-sulfonique, de préférence d'acide méthane-sulfonique ;
• de 0,1 % à 30 % en poids, de préférence de 0,5 % à 15 % en poids et plus particulièrement de 1 % à 10 % en poids, d'au moins un agent moussant ;
• de 0 à 30 % en poids, de préférence de 0,5 % à 15 % en poids et plus particulièrement de 1 % à 10 % en poids, d'au moins un agent gélifiant ;
• de 0 à 30 % en poids, de préférence de 0,5 % à 15 % en poids, d'au moins un additif choisi parmi ceux cités ci-dessus, dont de préférence de 0 à 10% en poids, de préférence de 0,1 à 5% en poids, d'un agent solubilisant ou hydrotrope, et de 0 à 20 % en poids, de préférence de 0,5 % à 10 % en poids, d'au moins un tensioactif ; et
• le complément à 100 % d'eau et/ou solvant organique,

pour le nettoyage des dépôts solides comprenant au moins un sel d'acide aconitique.Thus, the present invention also relates to the use of a foaming gel formulation comprising:

• from 0.01% to 97% by weight, preferably from 0.05% to 75% by weight and more preferably from 0.5% to 70% by weight, of at least one alkanesulfonic acid, preferably from methanesulfonic acid;
• from 0.1% to 30% by weight, preferably from 0.5% to 15% by weight and more particularly from 1% to 10% by weight, of at least one foaming agent;
• from 0 to 30% by weight, preferably from 0.5% to 15% by weight and more preferably from 1% to 10% by weight, of at least one gelling agent;
• from 0 to 30% by weight, preferably from 0.5% to 15% by weight, of at least one additive chosen from those mentioned above, preferably from 0 to 10% by weight, preferably from 0 to 1 to 5% by weight of a solubilizing or hydrotropic agent and 0 to 20% by weight, preferably 0.5 to 10% by weight, of at least one surfactant; and
• the complement to 100% of water and / or organic solvent,

for cleaning solid deposits comprising at least one aconitic acid salt.

Depending on the field and mode of application, the formulation may be prepared as a concentrate, and then diluted before use until the expected efficiency, viscosity and foaming power.

• les oxydes de diméthylalkylamine, la chaîne alkyle étant une chaîne « grasse », contenant par exemple de 10 à 30 atomes de carbone, de préférence de 12 à 22 atomes de carbone ;
• les oxydes d'amines éthoxylées ; et
• les mélanges de deux ou plusieurs d'entre elles.

In the foaming gel formulation above, the foaming agent may be chosen from foaming agents commonly used by those skilled in the art, and preferably from amine oxides, for example:

• dimethylalkylamine oxides, the alkyl chain being a "fatty" chain, containing, for example, from 10 to 30 carbon atoms, preferably from 12 to 22 carbon atoms;
• ethoxylated amine oxides; and
• mixtures of two or more of them.

The use of at least one ethoxylated amine oxide, such as, without limitation, Cecajel® OX100 from CECA, or Aromox® T12 from Akzo alone or combination with at least one dimethylalkylamine oxide allows to bring stability to the foaming gel.

Foaming agents, and in particular those described above, generally form gels when they are mixed with water, that is to say they increase the viscosity of the formulation, without it being necessary. to add a gelling agent. However, the addition of such a gelling agent is not excluded from the present invention.

Among the solubilizing or hydrotropic agents that may be used in the formulations according to the invention, mention may be made, for example and without limitation, of sodium xylene or cumene sulfonates. Such agents are however not essential in the acidic formulations according to the invention.

An aqueous, organic or hydro-organic formulation, in the form of a solution, a gel or in the form of a foaming gel, which is particularly preferred, is a formulation comprising from 0.01% to 95%, preferably from 0.05% to 75% more preferably from 0.5% to 50% by weight of methanesulfonic acid.

The formulations used according to the present invention, whether in liquid form, gels or foaming gels, concentrated or diluted, may be applied according to any method known to those skilled in the art, and in particular under pressure, or using a spray gun.

The concentration of alkane-sulfonic acid (s) can thus vary in very large proportions, depending on the nature and the quantity of residues to be removed, but also according to the nature of the surfaces to be cleaned.

The invention also relates to a solid deposition cleaning method comprising at least one salt of aconitic acid, which deposit of aconitate can be encountered in all types of industries employing at least one step of evaporation of the water of a mixture comprising at least one salt of aconitic acid capable of depositing, and in particular in the sugar-making industries from natural plant materials, such as, for example, sugar cane or sugar beet.

The present invention relates to a method for cleaning (ie solubilizing and / or eliminating), at least partial and preferably total, solid deposition comprising at least one aconitic acid salt, whether it is in wet or dried form, for example taken in bulk, and present on all types of surfaces, in particular hard surfaces, in particular metallic surfaces (iron, aluminum, steels and the like). ), wood, polymers (plastics, paints, lacquers, varnishes), glasses, stones, ceramics, porcelains, terracotta, and others.

Thus, the present invention relates to a process for removing deposits comprising at least one aconitic acid salt, as defined above, present for example on all types of surfaces, as indicated above, stained, coated, covered, in totality. or in part by residues, scales, deposits, dry or wet, generated during the preparation of products obtained from plants and in particular from sugar cane or sugar beet.

More particularly, the process of the present invention comprises at least one step of contacting an effective amount of at least one alkanesulfonic acid, as defined above, preferably methanesulfonic acid, in the form of a formulation. aqueous, organic or hydro-organic, in the form of a solution, gel or foaming gel, as just described, with a solid deposit comprising at least aconitic acid to be removed, by contact, immersion, spraying spraying, applying a more or less thick layer, possibly using appropriate tools known to those skilled in the art (brushes, brushes, spatulas, and others), said contacting step possibly being followed by one or more rinsing and / or drying steps.

The temperature at which the process is carried out, and in particular the step of contacting, can vary in large proportions and is generally between -20 ° C. and + 150 ° C., preferably between 0 ° C. and 80 ° C. C, more preferably between 10 ° C and 80 ° C. According to a preferred embodiment, the use temperature is the ambient temperature or a temperature between room temperature and about 80 ° C.

It can thus be envisaged to heat the alkane-sulfonic acid and the surface to be treated, this temperature may be identical or different, or to bring to temperature either the alkanesulfonic acid or the surface to be treated.

It is thus possible to treat surfaces soiled with solid deposits at ambient temperature (for example 10 ° C.) with the aid of an acid formulation (s). alkanesulphonic acid (s) raised to 70 ° C, or treat surfaces soiled by solid deposits at a high temperature (for example about 100 ° C) using an acid formulation (s) alkane- sulfonic (s) at room temperature (eg 20 ° C). It can also be envisaged to completely immerse the surfaces to be treated in an alkane-sulfonic acid (s) formulation (s), for example at a temperature of about 60 ° C., for example to remove solid deposits present in valves, pipes, and others.

In the process of the invention, it should be understood that it is possible to use at least one alkanesulfonic acid or any formulation comprising at least one alkanesulfonic acid, as described above.

Finally, after the treatment step (s), by contacting and then rinsing (s) possible (s), the cleaned surface can be, if necessary and if necessary, dried, according to any known method of the those skilled in the art, for example in the air, under a current of air more or less hot, in an oven, by heating (electric, heat lamps), wiping (paper or absorbent textiles), and others.

As indicated above, the alkanesulfonic acid is advantageously used in the form of a formulation, for example an aqueous, organic or hydro-organic formulation, in liquid form, of a gel or of a foaming gel, as defined above.

In the process of the invention as just described, effective amount means an amount for cleaning residues, scales, and generally solid deposits comprising at least one aconitic acid salt.

This amount can vary in large proportions, depending on the surfaces to be treated and the amount of solid deposits, the temperature and pressure of the formulation used, the desired duration of the cleaning process, and others.

Thus, the amount of acid will be advantageously established to allow complete, or as complete as possible, cleaning of the solid deposits of aconitates, while using a minimal amount of acid (s), essentially for economic reasons.

This cleaning operation of solid deposits of aconitates can be repeated once or more depending on the amount and nature of the solid deposits, and their degree of incrustation on the surfaces to be treated.

The contacting of an effective amount of at least one alkanesulphonic acid is followed by a reaction time necessary for the dissolution of the solid deposits which it is desired to eliminate, this reaction time varying from a few seconds to a few hours, or even a few days, depending on the temperature at which the cleaning is carried out, the application pressure of the alkane-sulphonic acid (s), the nature of the formulation comprising the said at least one alkane-sulphonic acid; , the quantity of deposits to be removed, their degree of incrustation, as well as the nature of the surfaces to be treated.

The treatment with at least one alkane-sulphonic acid as just defined can optionally be accompanied and / or preceded, and / or followed by one or more washes, and preferably preceded by one or more prewashes, if necessary, using a basic formulation comprising at least one mineral or organic base, preferably a mineral base, for example an alkali or alkaline earth metal hydroxide, for example sodium hydroxide, in all concentrations. These basic washes are quite preferably carried out before, or after, or before and after, but preferably not simultaneously with the cleaning with said at least one alkanesulfonic acid, in order to avoid the acid / neutralization reactions. which could adversely affect the quality of the cleaning sought.

The treatment with at least one alkane-sulphonic acid as just defined may optionally be accompanied and / or followed by one or more mechanical operations (stirring, scraping, brushing, and the like), in order to improve acidic chemical action, if necessary.

As indicated above, the treatment may be followed by one or more rinsing operations, for example with clear water, solvent (s) or mixture (s) water / solvent (s).

In the process of the invention as just described, the term "effective amount" means an amount allowing the dissolution and elimination of all or part of dirt, residue, scales, dry or not, deposits solids comprising at least one aconitic acid salt.

This quantity can vary in large proportions, depending on the surfaces to be treated and the amount of solid deposits, the temperature, the pressure of the formulation used, the nature of the formulation used, the desired duration of the removal process and the like.

Thus, the amount of acid will advantageously be adjusted to allow a total or at least partial, preferably total, elimination of residues, scales, dried or not, of said solid deposits of aconitates, while observing a minimal amount of acid ( s), mainly for economic reasons.

Alkanesulphonic acids, especially methanesulfonic acid, have been shown to be effective in cleaning solid deposits of aconitates, especially solid deposits encountered in the sugar-making industry, particularly from sugar cane. or sugar beet without generating irritating and tear gas emissions.

Furthermore, the use of at least one alkane-sulfonic acid according to the present invention has the advantage of generating little or no corrosion, especially during the cleaning of metal surfaces (many in particular in the sugar industries) , corrosion which is frequently observed on said metal surfaces when using solutions more or less concentrated in acids.

The alkane-sulphonic acids can also be used at high concentrations, in order to increase their effectiveness, which concentrations can be 50%, 70% or even 100% by weight, whereas the maximum concentration of hydrochloric acid can not be less than only 37%, due to the intrinsic chemical nature of this acid.

In addition, the alkane-sulfonic acids used in the present invention have, compared to arylsulfonic acids, the advantage of generating a lower chemical oxygen demand (COD) at the effluent treatment stations, and consequently allow a greater higher concentration of organic discharges in said stations.

The formulations that may be used in the context of the present invention may contain phosphorus compounds, such as, for example, phosphates, originating, for example, from phosphoric acid, but in small proportions, for example less than 10% by weight, preferably less than 10% by weight. 5% by weight, more preferably less than 1% by weight, relative to the total weight of the formulation, always with the aim of minimizing as much as possible the discharges harmful to the environment.

In addition, the formulations that may be used in the context of the present invention may contain sulfur-containing compounds, such as, for example, sulphates, originating, for example, from sulfuric acid, but in small proportions, for example less than 10% by weight, of preferably less than 5% by weight, more preferably less than 1% by weight, relative to the total weight of the formulation.

The formulations that may be used in the context of the present invention may contain chlorinated compounds, such as, for example, chlorides, originating, for example, from hydrochloric acid, but in small proportions, for example less than 10% by weight, preferably less than 10% by weight. 5% by weight, more preferably less than 1% by weight, relative to the total weight of the formulation.

The formulations that may be used in the context of the present invention may contain nitrogen compounds, such as, for example, nitrates, originating, for example, from nitric acid, but in small proportions, for example less than 10% by weight, preferably less than 10% by weight. 5% by weight, more preferably less than 1% by weight, relative to the total weight of the formulation.

The present invention described above shows that it is possible to eliminate solid deposits of aconitates on all types of surfaces, such as, and without limitation, metal surfaces (iron, steel, copper, alloys, and the like). ), concrete, cement, tiles, porcelain, wood, paper, cardboard, textiles, polymers (plastics, varnishes, paints, lacquers), glasses, and others.

The present invention also shows that it is possible to clean said surfaces of residues, dried or unwanted, undesirable, but also to remove solid deposits that may have accumulated in various containers, evaporators, ducts, valves, and others, and which are usually removed by acids which are not very respectful of the environment and / or which are corrosive with respect to the surfaces to be treated.

Thus, the alkane-sulfonic acids can advantageously be used as a replacement for the acids that are commonly known and used by those skilled in the art for the removal of solid deposits of aconitates, in a large number of fields of application, among which mention, in a non-limiting way, the sugar industries.

It should be understood that the use according to the present invention not only allows the cleaning of solid deposits of aconitates, but also and so Concomitant cleaning of other type (s) of dirt (s) may be present (s) on the surfaces to be treated, due to the acid nature of alkanesulfonic acids used.

For example, the alkane sulfonic acids used in the context of the present invention can be effective for cleaning any type of soiling, such as rust, scale, but also all types of organic fouling inherent in the manufacture of sugar especially from as indicated previously.

The present invention is now illustrated by means of the following examples, without being limiting in nature, and therefore can not be understood as likely to restrict the scope of the invention as claimed.

In order to assess the effectiveness of the alkanesulphonic acids in the cleaning of deposits comprising salts of aconitic acid, a calcium salt of aconitic acid is first prepared and then dissolution tests are carried out.

Example 1 Preparation of tricalcium aconitate trihydrate : Ca ₃ (C ₆ H ₃ O ₆ ) ₂ - 3H ₂ O

This preparation is described in the thesis of Niconor Niconey Reece, University of Louisiana; December 2003, "Optimizing aconitate removal during clarification" .

In a four-necked 500 mL equipped with a magnetic stirrer, a water condenser, a temperature probe and a pH probe, were introduced 8 g of aconitic acid trans- (0.0457 mol weight molecular = 174.). It is then added to 133 g with ultrapure water. The solution is then neutralized with 0.2 M potassium hydroxide (NaOH) to pH 11.3, then the pH is adjusted to the value 6 with 1N hydrochloric acid (HCl) solution.

The solution is then heated to 85 ° C., and then 228.5 ml of a 0.3M calcium chloride solution whose pH has been adjusted beforehand to 6 with 1N HCl are added.

The reaction medium is heated for 3 hours at 85 ° C. and a precipitate then appears, the medium is then filtered while hot. 10.6 g of a solid which is washed 3 times with 30 ml of hot water are recovered.

After drying in a vacuum oven at 50 mbar for 48 hours at room temperature, 7.4 g of a white solid are obtained, which is characterized by analyzes of its carbon, hydrogen and calcium content, and which comply with the formula Ca ₃ (C ₆ H ₃ O ₆ ) ₂ - 3 (H ₂ O).

Measurement of the solubility of tricalcium aconitate trihydrate

In a three-necked 50 ml equipped with a magnetic stirrer, a condenser and a temperature probe, are introduced 30 g of aqueous 1 M acid solution. The salt prepared as indicated above (tricalcium aconitate trihydrate ) is then added in portions of about 0.1 g, until undissolved crystals appear (saturation of the medium).

où M représente la masse de solution acide, et m représente la masse de sel introduite.The percentage of dissolved salt is calculated according to the following formula: $$\%\mathrm{dissolved\; salt}=\mathrm{m}/\left(\mathrm{M}+\mathrm{m}\right)$$

where M represents the mass of acidic solution, and m represents the mass of salt introduced.

Table 1 below summarizes the dissolution results of tricalcium aconitate trihydrate at 20 ° C. <u> - <b><i> Table 1 </ i></b> - </ u> tested acid % by weight of tricalcium aconitate trihydrate dissolved at room temperature (20 ° C) methanesulfonic acid 12.1% hydrochloric acid 12.1% sulfamic acid 11.9% sulfuric acid << 2.2%

Sulfuric acid is very inefficient with respect to the solubility of the salts of aconitic acid. Methane sulfonic acid surprisingly has an efficiency comparable to that of hydrochloric acid and slightly higher than that of sulfamic acid. However, methanesulfonic acid is much less corrosive than hydrochloric acid, whose vapors are irritating and toxic to the user. In addition, methanesulfonic acid is biodegradable.

Finally, sulphamic acid, whose releases are also considered harmful to the environment, in particular for aquatic organisms, is not an acid that can be widely used on an industrial scale.

Claims (10)

1. Use of at least one alkane sulfonic acid of formula R-SO₃H, in which R represents a linear or branched, saturated hydrocarbon-based chain comprising from 1 to 4 carbon atoms, for cleaning solid deposits comprising at least one aconitic acid salt.
2. Use according to Claim 1, wherein the alkane sulfonic acid is chosen from methanesulfonic acid, ethanesulfonic acid, n-propanesulfonic acid, iso-propanesulfonic acid, n-butanesulfonic acid, iso-butanesulfonic acid, sec-butanesulfonic acid, tert-butanesulfonic acid, and mixtures of two or more of them in any proportions.
3. Use according to Claim 1 or Claim 2, wherein the alkane sulfonic acid is methanesulfonic acid or ethanesulfonic acid, preferably methanesulfonic acid.
4. Use according to any one of the preceding claims, wherein said at least one alkane sulfonic acid is used in the form of a formulation, the amount of alkane sulfonic acid(s) being included from 0.01% to 100%, more generally from 0.05% to 90%, in particular from 0.5% to 75%, by weight, limits included, relative to the total weight of said formulation.
5. Use according to any one of the preceding claims, wherein said at least one alkane sulfonic acid is present in an aqueous, organic or aqueous-organic formulation, which is concentrated, ready to use, or to be diluted before use.
6. Use according to any one of the preceding claims, wherein at least one alkane sulfonic acid is used in combination with one or more additives chosen from:

   • solvents, hydrotropic or solubilizing or gelling agents (for example alcohols, esters, ketones, amides, and the like),

   • biocides, disinfectants (bromoacetic acid, peracetic acid, aqueous hydrogen peroxide, and the like),

   • rheological or texturing or thickening agents (sugars, polysaccharides, alginates, silica, amorphous silica, gums, and the like),

   • organic or inorganic acids (for example sulfuric acid, phosphoric acid, nitric acid, sulfamic acid, acetic acid, citric acid, formic acid, lactic acid, glycolic acid, oxalic acid, and the like),

   • flame retardants,

   • preservatives,

   • emulsifying anionic, cationic, non-ionic or amphoteric surfactants (such as ethoxylated alcohols and/or amines, alkyl and/or aryl sulfonates), detergents, soaps, and the like,

   • foaming agents, antifoams,

   • antifreezes (for example ethylene glycol, propylene glycol, and the like),

   • corrosion inhibitors,

   • dyes,

   • fragrances, odorizing agents,

   and other additives known to those skilled in the art.
7. Use according to any one of the preceding claims, wherein at least one alkane sulfonic acid is used in liquid, gel or foaming gel formulation.
8. Process for cleaning solid deposits comprising at least one aconitic acid salt, comprising at least one step of bringing an effective amount of at least one alkane sulfonic acid, preferably methanesulfonic acid, into contact with said solid deposits to be eliminated, by contact, immersion, sprinkling, spraying, application of a more or less thick layer, optionally by means of appropriate tools known to those skilled in the art (fine brushes, brushes, spatulas, and the like), said contacting step being optionally followed by one or more rinsing and/or drying steps.
9. Process according to Claim 8, characterized in that it is carried out at a temperature of between -20°C and +150°C, preferably between 0°C and 80°C, more preferably between 10°C and 80°C, preferably at ambient temperature or else at a temperature between ambient temperature and approximately 80°C.
10. Use according to any one of Claims 1 to 7, for cleaning solid deposits comprising at least one aconitic acid salt, on all types of surfaces, in particular metal, concrete, cement, tiling, tile, stone, porcelain, wood, paper, cardboard, textile, polymer (plastic, varnish, paint, lacquer), glass surfaces, and the like.