EP0687483A1 - Process for the treatment and conditioning of solid or liquid effluents charged with heavy metals - Google Patents

Abstract

Processing of solid or liq. effluents contg. heavy metals comprises: (a) treating a liq. effluent or liq. extract of a solid effluent with a reducing agent to obtain a process soln.; (b) contacting the process soln. with a solvent in a first extraction vessel, where the solvent is capable of selectively extracting heavy metals, anions and alkali(ne earth)metals and comprises an organophosphorus extractant and a hydrocarbon; (c) passing the organic phase from (b) to a second extraction vessel and contacting it with an aq. soln. capable of extracting heavy metals from the organic phase; (d) contacting the aq. phase from (c) with a pptn. capable of precipitating. all the heavy metals in the form of insoluble and vitrifiable chemical species; (e) filtering off the ppte. and washing it with water; (f) recycling the filtrate from (e) for addn. to the process soln. from (a); and (g) vitrifying the ppte. from (e).

Description

The present invention relates to a process for the treatment and conditioning of solid or liquid effluents loaded with heavy metals. It aims to treat effluents from, for example, chemical processes for surface treatment, waste incineration processes or any other process leading to the formation of effluents heavily loaded with heavy metals and therefore extremely toxic. This process allows, more particularly, the selective recovery of these heavy metals with respect to chlorine or to alkali or alkaline earth metals.

The solid waste produced by these different chemical processes is particularly toxic for the environment because it has a fairly large soluble fraction which prevents its storage in landfills.

Furthermore, in the chemical surface treatment industry for example, the volumes of liquid effluents formed are generally very large. For example, a medium-sized company working in this type of industry can generate up to a tonne per year of sludge concentrated in metals. This represents extremely significant pollution throughout the national territory.

The purification technique for this type of effluent generally consists of carrying out a conventional neutralization and precipitation treatment, so as to form sludges liable to be stored in landfills of class "I" (that is to say an impermeable site intended to receive special industrial waste).

Mention may also be made, by way of example, of residues formed by household waste incineration processes. This waste or this residue comprises approximately 30% by weight of the initial bottom ash product, 3% by weight of the initial fly ash product and of the dechlorination products of the fumes (hereinafter referred to as REFIOM, i.e. REsidues Household Waste Incineration Smoke), the rest being non-condensable products. The bottom clinkers are relatively chemically inert and can be used after conditioning in road construction or be stored in landfills of class "II" (that is to say a semi-permeable site intended to receive ordinary industrial waste), or even in class III landfills (that is to say a permeable site receiving only inert waste). On the other hand, fly ash, formed by fine particles entrained by combustion gases and by gas neutralization products, have highly polluting characteristics, due to the high rate of the soluble fraction with a high content of leachable heavy metal compounds.

• calcium 10 à 30 % ;
• chlore 10 à 25 % ;
• sulfate 15 à 25 % ;
• silicium 3 à 15 % ;
• aluminium 2 à 6 % ;
• potassium 1 à 7 % ;
• sodium 1 à 4 % ; et
• métaux lourds 3 à 4%.

Finally, by way of example, French incineration plants thus produced in 1991 around 240,000 tonnes of REFIOM. In general, the constituents of these REFIOMs are as follows:

• calcium 10 to 30%;
• chlorine 10 to 25%;
• sulfate 15-25%;
• silicon 3 to 15%;
• aluminum 2 to 6%;
• potassium 1 to 7%;
• sodium 1 to 4%; and
• heavy metals 3 to 4%.

The polluting fraction consists essentially of heavy metals, the most common of which are zinc, lead, cadmium and chromium.

However, the composition of these "REFIOM" is very variable and depends on the techniques used for the purification of the fumes from the incineration processes (techniques by dry, semi-wet or wet routes).

For example, in dry or semi-wet incineration processes, REFIOMs can be washed with water, which allows the soluble fraction containing the majority of heavy metals to be entrained. The leachate is treated with sodium hydroxide which allows on the one hand the precipitation of these metals in the form of hydroxide and their recycling with the insoluble part resulting from the preliminary washing operation, the whole being able to be vitrified, and on the other hand the production of a sodium effluent containing the non-toxic anions and cations to be treated later. The wet processes can operate in a similar fashion, except washing, since the recovered effluent is already in the form of a suspension which undergoes the same precipitation treatment as previously described. The solid residue obtained can also be vitrified.

Numerous methods for treating these "REFIOMs" are already known from the prior art, associated or not with a subsequent vitrification treatment. Such methods generally consist in precipitating or fixing the heavy metals by treating the liquid effluent itself or a washing solution. "REFIOM" in an ion exchange column, (see for example US4873065 or US5041398).

The known methods have many drawbacks, such as the incomplete extraction of heavy metals, the formation of an insufficiently stabilized final residue in the form of sludge only capable of being stored in controlled landfills (class I) or the large quantity of additives to be used which results in high operating costs.

In addition, the implementation of vitrification requires compliance with a number of criteria. Thus, the vitrified elements must be digestible in the glass, so as to avoid the formation of heterogeneous phases or precipitates in large quantities. The anions (Cl, F, PO₄, SO₄) are the most troublesome elements due to their low solubility in glass which causes phase separations. The glasses then obtained are non-homogeneous and of poor quality, because the molten salt phase which is not vitrified contains a non-negligible proportion of toxic cations. In addition, the molten salt phases being lighter than the glass itself, the fairly high volatility of these salts is further increased by their contact with the gaseous atmosphere. In addition, waste and glass must be compatible.

Furthermore, whatever the effluents treated, that is to say liquid effluents or fly ash, a dechlorination treatment will be necessary. In the case of "REFIOM", treatment for confinement by vitrification always requires a preliminary chemical leaching operation intended to extract the chloride. The insoluble fraction consists essentially of silica and alumina, as well as some easily vitrifiable metal oxides.

Finally, the treated effluents may contain a high proportion (that is to say more than 50% by weight) of alkali metal salts (sodium and potassium) or alkaline earth metal salts (magnesium and calcium ). These salts do not present any particular nuisance for the environment and it is not necessary to make them inert in a specific matrix.

Despite all the above drawbacks and requirements, the vitrification technique remains extremely interesting.

Consequently, the object of the invention is to carry out a process for the treatment and conditioning of solid or liquid effluents loaded with heavy metals which make it possible to selectively separate from the effluent, chlorine and alkali or alkaline-earth metals in order to make the toxic residual fraction of the effluent containing heavy metals vitrifiable.

• a) réduire chimiquement à l'aide d'un agent réducteur l'effluent liquide ou l'effluent solide traité de façon à se présenter sous forme liquide, l'ajuster en pH pour obtenir.une solution réduite ;
• b) mettre, dans un premier appareil d'extraction, cette solution mère en contact avec un solvant organique contenant essentiellement un extractant organophosphoré et un hydrocarbure capable d'extraire sélectivement les métaux lourds, des anions et des métaux alcalins et alcalino-terreux ;
• c) mettre, dans un deuxième appareil d'extraction, la solution organique chargée en métaux lourds et issue du premier appareil d'extraction, en contact avec une solution aqueuse capable d'extraire les métaux lourds de la phase organique ;
• d) mettre en contact la solution aqueuse issue de l'appareil d'extraction avec un agent de précipitation capable de précipiter la totalité des métaux lourds contenus dans la solution aqueuse sous la forme d'espèces chimiques insolubles et vitrifiables ;
• e) filtrer la suspension obtenue, puis laver le précipité solide à l'eau afin de le séparer des eaux mères de lavage ; et
• f) vitrifier le précipité lavé filtré.

According to a characteristic of the invention, this method comprises the steps consisting in:

• a) chemically reduce using a reducing agent the liquid effluent or the solid effluent treated so as to be in liquid form, adjust it to pH to obtain a reduced solution;
• b) putting, in a first extraction device, this mother solution in contact with an organic solvent essentially containing an organophosphorus extractant and a hydrocarbon capable of selectively extracting heavy metals, anions and alkali and alkaline earth metals;
• c) put, in a second extraction device, the organic solution loaded with metals heavy and from the first extraction device, in contact with an aqueous solution capable of extracting heavy metals from the organic phase;
• d) bringing the aqueous solution from the extraction apparatus into contact with a precipitation agent capable of precipitating all of the heavy metals contained in the aqueous solution in the form of insoluble and vitrifiable chemical species;
• e) filter the suspension obtained, then wash the solid precipitate with water in order to separate it from the washing mother liquors; and
• f) vitrify the filtered washed precipitate.

This process applies to the treatment of various effluents and in particular solid or liquid effluents from chemical surface treatment processes or waste incineration processes. The process according to the invention allows selective recovery of heavy metals with respect to chlorine and to alkali or alkaline-earth metals and this in a solid form which is perfectly suitable for vitrification. We also recover inert salts vis-à-vis the environment and which can be used in road engineering for example.

To selectively extract metals, the solvent containing an extractant and a hydrocarbon must be chosen appropriately.

The choice of extractant is linked to the presence or not of calcium in the effluent to be treated. Thus, in the presence of calcium, bis- (2,4,4-trimethylpentyl) -monothiophosphinic acid will advantageously be used because of its good extraction power and its good selectivity with respect to alkali and alkali metals. -terreous or di- (2-ethylhexyl) -monothiophosphoric acid despite a slightly selective less good. On the contrary, in the absence of calcium, di- (2-ethylhexyl) -phosphoric acid, di- (2,4,4-trimethylpentyl) -phosphinic acid, mono (2-ethylhexyl) will be used. ester of (2-ethylhexyl) -phosphonic acid.

The hydrocarbon used is generally hydrogenated tetrapropylene (TPH). In some cases, the addition of an agent preventing the separation of the extractant and the diluent, for example a heavy alcohol C10 to C14, may be necessary.

During the various stages of extraction of the process, it is desirable on the one hand to strongly concentrate the metals extracted and on the other hand to avoid the formation of emulsions difficult to decant and which would harm the good hydrodynamic functioning of the apparatuses 'extraction. Care should therefore be taken on the one hand to use a highly concentrated solvent and on the other hand to ensure that the organic phase is lighter than the aqueous phase. This is the reason why the pure organophosphorus extractant (for example bis- (2,4,4-trimethylpentyl) -monothiophosphinic acid; density 0.93 and viscosity 195 centipoise) must be diluted with a liquid hydrocarbon less dense for example TPH; density 0.76).

However, the dilution factor should not be too large in order to be able to strongly concentrate the metals and not to have to increase the size of the extraction apparatus. In practice, the solvent is preferably diluted until it titers 0.2 to 1.0 mole of organophosphorus extractant per liter of hydrocarbon or better 0.6 mole per liter. This reduces the density of the viscosity of the organic solvent while increasing its interfacial tension with the aqueous contact solutions. Therefore, the first extraction step can take place at room temperature (20 to 25 ° C), which reduces its cost.

During the two stages of extraction of the process, precipitation of metal salts, followed by their redissolution is possible. In a settling mixer, these precipitates collect at the bottom of the settling tanks and become inaccessible to the solvent. Also, advantageously, the two extraction steps are carried out in a pulsed column because these devices are not very sensitive to the presence of solid matter. This avoids the above problem.

The quality of the extraction is highly dependent on the pH of the aqueous phase. However, during the extraction of metals which is carried out by cation exchange, the acidity of the aqueous phase increases. Care should therefore be taken to maintain the pH value as constant as possible by injections of a neutralizing agent at predetermined positions in the extraction apparatus. The pH of the aqueous phase is preferably maintained at a value between 4.5 and 6.5, or better still between 5.0 and 6.0 depending on the extractant used. Advantageously, the neutralizing agent used to adjust the pH is a concentrated sodium hydroxide solution.

Although the second extraction step can be carried out at room temperature (approximately 20 to 25 ° C), it is preferable to carry it out hot, that is to say between approximately 40 and 60 ° C, preferably 50 ° C, if you wish to purify the solvent from all of the metals before recycling it in the first extraction device. This hot treatment also has the advantage of avoiding the precipitation of lead chloride, the solubility of which is more limited in the second extraction apparatus.

The precipitation step transforms the metals into insoluble carbonates, that is to say a chemical form suitable for vitrification. Advantageously using powdered sodium carbonate or in solution at 200 g / l or powdered calcium carbonate which quantitatively precipitate the most troublesome heavy metals, such as cadmium, nickel, lead and zinc. Preferably, the precipitation pH is chosen at a value between 8 and 10, or better still 9, to limit the redissolution of aluminum and chromium hydroxides in particular. This precipitation step is generally carried out between 40 and 60 ° C or better about 50 ° C, which increases the speed of formation and maturation of the precipitates and makes it possible to avoid the untimely precipitation of lead chloride.

• en mettant dans un dispositif de lixiviation l'effluent solide à traiter en contact avec une solution de lixiviation et un acide minéral dilué avec une solution aqueuse et capable de solubiliser la fraction soluble de l'effluent solide pour former une suspension ;
• en introduisant cette suspension dans un dispositif de filtration, afin de la séparer en un solide résiduel insoluble et en un effluent liquide à introduire dans le premier appareil d'extraction ; et
• en lavant le solide résiduel insoluble par de l'eau.

Finally, when the effluent to be treated is in solid form, the method according to the invention comprises a first series of steps intended to make this effluent liquid. This is achieved:

• by putting in a leaching device the solid effluent to be treated in contact with a leaching solution and a mineral acid diluted with an aqueous solution and capable of dissolving the soluble fraction of the solid effluent to form a suspension;
• by introducing this suspension into a filtration device, in order to separate it into an insoluble residual solid and into a liquid effluent to be introduced into the first extraction apparatus; and
• by washing the residual insoluble solid with water.

Other characteristics and advantages of the invention will emerge more clearly on reading the following description, given by way of illustrative and nonlimiting example and made with reference to the attached single figure, schematically representing the installation necessary for the implementation of the method according to the invention.

As illustrated in the attached figure, the installation necessary for the implementation of the method according to the invention comprises six chemical engineering equipments, namely two extraction apparatuses, referenced 2 and 4 respectively, of the pulsed column type, an apparatus precipitation device 6, of the ripener-thickener type, a filtration device 8, of the continuous vacuum filter type with drum or strips or of the discontinuous filter type with press and vitrification equipment 10. Optionally, this device can also include concentration equipment 12.

When the effluent to be treated is in liquid form, this installation is sufficient. However, when the effluent to be treated is in solid form, the aforementioned installation is completed by a leaching device 14, advantageously consisting of an apparatus of the stirred tank type, mounted in cascade and the volume and number of which is adapted to the flow rate of the waste to be treated and by a filtration device 16, of the continuous vacuum type drum or band filter, or of the discontinuous press filter type.

The operation of this device will now be described in more detail, in the case of effluents to be treated which are in solid form. The solid effluent 18 is introduced with concentrated hydrochloric acid 20 into the leaching device 14 where the reaction takes place between 40 and 80 ° C. A control of the pH of the solid-liquid suspension 22 leaving the leaching device makes it possible to adjust the flow rate of hydrochloric acid 20. The pH is maintained between 0.5 and 3.0. The solid-liquid suspension 22 is introduced into the filtration device 16. The solid cake is washed with water 24 and the liquid filtrate 26 is recovered. The mother liquors from washing 28 are recycled to the leaching device 14 where they constitute the leaching solution. Advantageously, the flow rate of washing water 24 is adapted to the flow rate of solid waste, so as to obtain a filtrate 26 containing between 5 and 20% by weight of solids and a washed residual solid 30 containing less than 1% of chlorides.

The description which follows is common to the treatment of the filtrate 26 from the filtration device 16 or to an effluent to be treated which is presented directly in liquid form.

A reducing agent 32 and a filtrate 34 from the filtration device 8 are added to the filtrate 26 (or liquid effluent) as will be described later so as to form a mother solution 36. This is introduced at one end of the extraction apparatus 2, in which the non-alkaline and non-alkaline earth cations are selectively extracted from the anions, against the flow of an organic extraction solvent 38 introduced at the other end of the apparatus . The reducing agent 32 is, for example, sodium bisulfite, sodium metabisulfite, ferrous sulfate or sulfur dioxide.

The pH of the aqueous phase is adjusted by injections of a neutralizing agent at different points, referenced respectively 40, 42 and 44. The relative flow rate of the two solutions is adjusted so that the raffinate 46 leaving the first device contain less than 15.0 mg / l of heavy metals.

Advantageously, but not compulsory, the solvent 38 comes from the second extraction device 4. The organic solution loaded with heavy metals 48 leaving the first extraction device 2 enters the second extraction device 4 where it is treated counter-current and hot with an aqueous solution of hydrochloric acid 50. The acid titer of this aqueous solution of hydrochloric acid is such that the solvent 38 leaving the second extraction device 4 is sufficiently discharged not to generate leaks of heavy metals and in particular cadmium greater than 0.2 mg / l in the raffinate 46.

The aqueous extraction solution 52 loaded with heavy metals, originating from the extraction apparatus 4, is introduced hot into the precipitation apparatus 6 where it is treated using a precipitation agent 54 which can advantageously be sodium or calcium carbonate. This carbonate maintains a sufficiently alkaline pH for which the heavy metals are thus precipitated in the form of carbonates, the chloride anions remaining in solution.

The solid-liquid suspension 56 from the precipitation apparatus 6 is introduced into the filtration apparatus 8 and the filtrate obtained is recycled at 34. The solid precipitate 64 is washed by introduction of water at 58, while the waters outgoing washing mothers 60 are recycled to the extraction apparatus 4. The flow rate of washing water used is at least equal to the flow rate necessary for diluting the hydrochloric acid 62 introduced. The mother liquors from washing 60 and hydrochloric acid form the aqueous solution 50 introduced into the second extraction device 4. Preferably, the aqueous solution 50 contains between 0.1 and 6.0 mol / l hydrochloric acid. The relative flow rates of the washing water 58 and the hydrochloric acid are further adjusted so that the solvent 38 contains less than 50 mg / l of heavy metals.

Then, the washed precipitate containing less than 1% of chlorides 64 is treated with the residual solid 30 in the vitrification device 10 to produce an inert glass 66.

Optionally, the raffinate 46 can be treated in the concentration device 8 in order to recover, on the one hand, recyclable water 68, salts 70 crystallized or in the form of brine.

Examples of implementation of the process according to the invention are given below.

Example 1

In an installation similar to that which has just been described, a "REFIOM" is treated with a 1.5N hydrochloric acid solution, the filtrate 26 obtained has the following composition:
[C1⁻] = 41.5 g / l [Ca²⁺] = 28 g / l
[Na⁺] = 1.66 g / l [K⁺] = 3.25 g / l
[Cd²] = 21 mg / l [Zn²⁺] = 1060 mg / l
[Pb²] = 380 mg / l [Cr ^VI ] = 4.3 mg / l
[Fe³] = 100 mg / l [Mn²⁺] = 22.0 mg / l
[Mg²] = 600 mg / l [Ba²⁺] = 8.0 mg / l
and various other elements at lower concentrations, such as Ni, Co and V. The pH is equal to 1.7.

Sodium metabisulfite is added at a rate of 50 mg / l. The mother solution 36 and the organic solvent 38 are introduced into the first extraction device 2 with a solvent flow rate equal to 0.2 times the flow rate of the aqueous phase. The pH is checked at 5.5 by adding 1.0 N NaOH.

The organic solvent 38 titers 0.6 M / l of bis- (2,4,4-trimethylpentyl) -monothiophosphinic acid in TPH.

The raffinate 46 obtained has the following composition:
[C1⁻] = 39.5 g / l [Ca²⁺] = 26.3 g / l
[Na⁺] = 1.64 g / l [K⁺] = 3.22 g / l
[Cd²⁺] ≦ 1 mg / l [Zn²⁺] ≦ 1 mg / l
[Pb²⁺] ≦ 1 mg / l [Cr³⁺] = 1.4 mg / l
[Fe²⁺] = 95 mg / l [Mn²⁺] ≦ 1 mg / l
[Mg²⁺] = 590 mg / l [Ba²⁺] = 6.5 mg / l

The organic solution loaded with heavy metals 48 is treated in the second extraction device 4, against the flow of a 3N hydrochloric acid solution whose volume flow is five times lower than the flow of organic phase.

The first extraction operation 2 is carried out at an average temperature of the order of 22 ° C, while the second extraction operation 4 is carried out at the average temperature of the order of 50 ° C.

The de-extracted solvent 38 recovered contains less than 15 mg / l of residual heavy metals.

The aqueous extraction solution 52 has the following composition:
[C1⁻] = 107 g / l [Ca²⁺] = 38.1 g / l
[Na⁺] ≦ 1 g / l [K⁺] ≦ 1 g / l
[Cd²⁺] = 530 mg / l [Zn²⁺] = 26.3 g / l
[Pb²⁺] = 9.2 g / l [Cr³⁺] = 71 mg / l
[Fe³⁺] ≦ 105 mg / l [Mn²⁺] = 540 mg / l
[Mg²⁺] ≦ 1 g / l [Ba²⁺] = 31 mg / l

It is precipitated by sodium carbonate and the mother liquors from washing 60 recovered after filtration contain less than 15 mg / l of heavy metals.

Example 2

In an installation similar to that which has just been described, an effluent from a surface treatment plant is treated which has the following composition:
[C1⁻] = 410 mg / l [NH₄⁺] = 15 mg / l
[Na⁺] = 105 mg / l [K⁺] = 30 mg / l
[Cr ^VI ] = 45 mg / l [Zn²⁺] = 125 mg / l
[Fe³⁺] = 45 mg / l [Cu²⁺] = 10 mg / l
[Co²⁺] = 5 mg / l [Ni²⁺] = 10 mg / l
and various other elements in lower concentration, such as Al and F. The pH is equal to 1.8.

Sodium metabisulfite is added at a rate of 20 mg / l. The mother solution 36 and the organic solvent 38 are introduced into the first extraction device 2 with a flow rate of solvent equal to 0.2 times the flow rate of aqueous phase. The pH is checked at 5.5 by adding 1.0 N NaOH.

The organic solvent 38 titers 0.6 M / l of di- (2-ethylhexyl) -manothiophosphoric acid in TPH.

Raffinate 46 has the following composition:
[C1⁻] = 410 mg / l [NH₄⁺] = 15 mg / l
[Na⁺] = 105 mg / l [K⁺] = 30 mg / l
[Cr³⁺] ≦ 1 mg / l [Zn²⁺] ≦ 1 mg / l
[Fe²⁺] ≦ 1 mg / l [Cu²⁺] ≦ 1 mg / l
[Co²⁺] ≦ 1 mg / l [Ni²⁺] ≦ 1 mg / l

The organic solution loaded with heavy metals 48 is treated in the second extraction device 4, against the flow of a 3N hydrochloric acid solution whose volume flow is 5 times lower than the flow of organic phase.

The first extraction operation 2 is carried out at an average temperature of the order of 22 ° C, while the second extraction operation 4 is carried out at an average temperature of 50 ° C.

The de-extracted solvent 38 recovered contains less than 15 mg / l of residual heavy metals.

The aqueous extraction solution 52 has the following composition:
[C1⁻] = 100 g / l [NH⁴⁺] ≦ 1 mg / l
[Na⁺] ≦ 1 mg / l [K⁺] ≦ 1 mg / l
[Cr³⁺] = 1.10 g / l [Zn²⁺] = 3.15 g / l
[Fe²⁺] = 1.16 g / l [Cu²⁺] = 243 mg / l
[Co²⁺] = 103 mg / l [Ni²⁺] = 238 mg / l

It is precipitated by sodium carbonate and the mother liquors from washing 60 recovered after filtration contain less than 15 mg / l of heavy metals.

Claims (18)

Process for treating and conditioning solid or liquid effluents loaded with heavy metals, characterized in that it comprises the steps consisting in: a) chemically reduce using a reducing agent (32), the liquid effluent (26) or the solid effluent (18) treated so as to be in liquid form, to obtain a mother solution (36) ; b) putting, in a first extraction device (2), this mother solution (36) in contact with an organic solvent (38) essentially containing an organophosphorus extractant and a hydrocarbon capable of selectively extracting heavy metals, anions and alkali and alkaline earth metals; c) putting, in a second extraction device (4), the organic solution loaded with heavy metals and coming from the first extraction device (2), in contact with an aqueous solution (50) capable of extracting the heavy metals organic phase; d) bringing the aqueous solution (52) from the second extraction device (4) into contact with a precipitation agent (54) capable of precipitating all of the heavy metals contained in the aqueous solution (52) in the form of 'insoluble and vitrifiable chemical species; e) filter the suspension (56) obtained and recover the filtrate (34) in order to recycle it with the mother solution (36), then wash the solid precipitate (64) with water in order to separate it from the mother liquors for washing ( 60); and f) vitrifying the filtered washed precipitate (64). Treatment and conditioning method according to claim 1, characterized in that the reducing agent (32) is chosen from sodium bisulfite, sodium metabisulfite and ferrous sulfate or sulfur dioxide. Treatment and conditioning process according to claim 1, characterized in that the organophosphorus extractant can be chosen from bis- (2,4,4-trimethylpentyl) -monothiophosphinic acid or di- (2-ethylhexyl) acid -monothiophosphoric, in the presence of calcium in the mother solution, or among di- (2-ethylhexyl) -phosphoric acid, di- (2,4,4-trimethylpentyl) -phosphinic acid or mono (2-ethylhexyl ) ester of (2-ethylhexyl) -phosphonic acid, in the absence of calcium in the mother solution (36). Treatment and conditioning process according to claim 1, characterized in that the hydrocarbon is hydrogenated tetrapropylene (TPH). Treatment and conditioning process according to claim 1, characterized in that the organic solvent (38) consists of a mixture containing 0.2 to 1.0 mole per liter of organophosphorus extractant diluted in the hydrocarbon. Treatment and conditioning method according to claim 1, characterized in that the organic solvent (38) introduced into the first extraction device (2) comes from the second extraction device (4). Processing and conditioning method according to claim 1, characterized in that at least one of the extraction devices (2, 4) is a pulsed column. Treatment and conditioning method according to claim 1, characterized in that the treatment carried out in the first extraction apparatus (2) is carried out at a pH between approximately 4.5 and 6.5. Treatment and conditioning method according to claim 1, characterized in that the treatment carried out in the first extraction apparatus (2) is carried out at a temperature between 20 to 25 ° C approximately. Treatment and conditioning method according to claim 1, characterized in that the treatment carried out in the second extraction device (4) is carried out at a temperature between 40 and 60 ° C approximately. Treatment and conditioning method according to claim 1, characterized in that the precipitation treatment is carried out at a temperature of between 40 and 60 ° C approximately. Treatment and conditioning method according to claim 1, characterized in that the precipitation agent (54) is sodium carbonate or calcium carbonate. Treatment and conditioning method according to claim 1, characterized in that the aqueous solution (50) introduced into the second extraction device (4) is obtained from the mother liquors of washing (60) from the filtration (8 ) and continuously adjusted with a hydrochloric acid solution (62) so as to contain between 0.1 and 6.0 mol / l of hydrochloric acid. Treatment and conditioning method according to claim 1, characterized in that the raffinate (46) from the first device extraction (2) is concentrated so as to form salts (70) and an aqueous phase (68). Treatment and conditioning method according to claim 1, characterized in that the treatment of the solid effluent (18) so as to make it liquid is carried out: - by putting in a leaching device (14) the solid effluent to be treated (18) in contact with a leaching solution (28) and a mineral acid (20) diluted with an aqueous solution and capable of dissolving the soluble fraction of the solid effluent (18), to form a suspension (22); - by introducing this suspension (22) into a filtration device (16), in order to separate it into an insoluble residual solid (30) and into a liquid effluent (26) to be introduced into the first extraction device (2); and - washing the insoluble residual solid obtained with water (24). Treatment and conditioning method according to claim 15, characterized in that the leaching treatment is carried out at a temperature of between 40 and 80 ° C approximately. Treatment and conditioning method according to claim 15, characterized in that the leaching solution (28) consists of the mother liquor from the filtration device (16), added with hydrochloric acid so as to adjust the pH of the suspension at a value of approximately 0.5 and 3.0. Treatment and conditioning method according to claim 15, characterized in that the quantity of washing water (24) used in the filtration device (16) is such that after recycling in the leaching device (14), the suspension (22) obtained contains between 5 and 20% by weight of solid material.

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