FR3137303A1 - Method and system for separating a solid and at least one liquid from a suspension - Google Patents

Abstract

The present invention relates to a method for separating a solid and at least one liquid contained in a suspension by a separation system (1) configured to separate the solid and the liquid from the suspension, the separation system (1) comprising at least one tank (2) and a screw (4) configured to, when rotated, allow the suspension to move inside the tank (2), the method being characterized in that it comprises a step of: a) introducing into the reservoir (2) a rheology modifier adapted to fluidize the suspension. Figure for abstract: Fig. 1

Description

Method and system for separating a solid and at least one liquid from a suspension FIELD OF INVENTION

The present invention relates to the field of treatment of a solid-liquid mixture, more precisely to the separation of the solid and the liquid of a suspension and, even more particularly, to the dehydration of a sludge.

STATE OF THE ART

Sludge dewatering processes are generally carried out using a suitable separation system such as a centrifuge or a screw press. The system traditionally includes a screw which moves the mud within a tank. The sludge is introduced into the tank, then water is extracted from the sludge by centrifugal force or pressure. The water is discharged through a suitable water outlet and the dewatered sludge is discharged through a dewatered sludge outlet. The screw rotation drive device must be able to provide a sufficiently large torque to allow the dewatered sludge to move towards the outlet. The more the mud dehydrates, the more the deformation and flow stresses of the mud increase, which requires a greater torque to move the mud. However, the screw rotation drive device may be unable to provide the torque necessary to drive the screw. Consequently, in order not to damage the separation system, the separation system generally includes a draining system which makes it possible to empty the separation system when the torque to be provided necessary to drive the screw reaches a determined torque threshold, this is that is to say when the dehydrated sludge reaches a solid content greater than a determined threshold. We therefore understand that, currently, the dehydrated sludge obtained using existing separation systems cannot exceed a certain solid content. This implies that the performance of the separation system is limited, the dehydrated sludge still comprising water which it would be desirable to extract.

An aim of the invention is to improve the performance of a system for separating a solid and at least one liquid from a suspension and, more precisely, to enable part of the suspension to be obtained. depleted in liquid having a higher solid content than in the prior art.

The present invention thus relates to a process for separating a solid and at least one liquid contained in a suspension by a separation system configured to separate the solid and the liquid from the suspension, the separation system comprising at least a tank and a screw configured to, when rotated, allow the suspension to move inside the tank, the method being characterized in that it comprises a step of:
a) introduction into the tank of a rheology modifier suitable for fluidizing the suspension.

According to advantageous and non-limiting characteristics, taken alone or in any combination:

• the rheology modifier is introduced into a zone of the tank where the solid content of the suspension is greater than a solid content threshold;
• the rheology modifier comprises at least one element chosen from anionic acrylic acid polymer, sodium silicate, lignosulfonate, naphthalene sulfonate - formaldehyde condensate (NSF), polyisoprene sulfonic acid soda (Dynaflow -K), carboxylic acid derivative (AC 1320), carboxymethylcellulose, naphthalene additive (P), naphthalene-toluene additive (R), sulfonic acid,Tri-polyphosphate of sodium (STPP), sodium carbonate, xanthan gum, sodium calcium lignosulfonate (LS), polycarboxylic acid (PC), starch graft copolymer synthesized using styrene sulfonate ( SSS), hydroxyethyl acrylate (HEA) and sodium methylmercury (MBS), hydroxyethyl acrylate (HEA) and methylacrylic acid (MAA), humic acid-acrylic acid graft copolymer sulfonated (SHA), sulfonated acetone-formaldehyde (SAF), polyacrylic acid (PA) additives, poly(styrene-co-maleic anhydride-g-sodium naphthylamine sulfonate) (SMANS), poly (styrene-co-methoxypolyethylene glycol maleic acid monoester-g-naphthylamine sulfonate) (SMANP), sodium oleate (SO), sodium dodecyl benzene sulfonate (DBS), sodium lauryl sulfate, sulfonated used motor oil, newly synthesized tannic acid-acrylic acid (TAA) compound, newly synthesized tannic acid-itaconic acid (TIA) compound, oxidized methylated sulfonated lignin (OSL) , sulfonated melamine-formaldehyde resin (SMF), sodium copolymer of maleic acid and acrylic acid (MA-AAS), quicklime (CaO), p-tert-octylphenoxy-polyethoxyethanol (Triton 405), Rokanol LO18, Rokwinol 60 (polyoxyethylated sorbitol stearate), p-octyl polyethylene glycol phenyl ether (TX), polysorbate 20 (Aloe vera juice), saponin, polyoxyethylene polycarboxylic ether (PPA), polyoxyethylene lauryl ether (PXLE), alcohol additives, cetyl trimethyl ammonium bromide (CTAB), amphoteric surfactant synthesized using methyl acrylic acid (MAA), sodium allyl sulfonate (SAS) and methacryloxyethyltrimethyl (DMC), sodium dodecyl sulfonate "SDS" (anionic - synthetic) + Saponin (non-ionic - natural), hexadecyltrimethylammonium bromide "CTAB" (cationic - synthetic) + Saponin (non-ionic - natural), di-docyl ammonium bromide "DDAB" (cationic - synthetic) + Saponin (non-ionic - natural), sodium decyl benzene sulfate "SDBS" (cationic - synthetic) + Saponin ( non-ionic - natural), polycarboxylate acid (PCA), polyacrylic acid (PAA), sodium lignosulfonate (SLS), xanthan gum (XG), polypropylene oxide (PPO), polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), black liquor (containing alkaline salts and lignin constituents as well as cellulose and hemicellulose ), black liquor (containing alkaline salts and lignin constituents as well as cellulose and hemicellulose fibers), polyacrylic acids, sodium polyacrylate and phosphates (AG Disper), citric acid, sodium hydroxide, sodium hexametaphosphate (SHMP), lime, polyacrylamides, acti-gel, bio-additive extracted from Indian spinach, bio-additive extracted from Bellyache shrub, polyethyleneimines, polyvinylamines, polyacrylate, copolymer of (meth)acrylic acid and acrylamide, (meth)acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, polymers taurine modified, naphthalene sulfonates and hydroxymethyl diphosphonic acid polymers;
• the suspension is a phosphate slurry;
• the suspension is a mud containing clay;
• the quantity of rheology modifier introduced into the reservoir is between 0.04% and 0.8% by mass of the suspension;
• the quantity of rheology modifier introduced into the reservoir is between 0.04% and 0.2% by mass of the suspension;
• the solid rate threshold is greater than 62%.

According to another aspect, the invention relates to a separation system configured to separate a solid and at least one liquid from a suspension comprising a reservoir, a screw arranged in the reservoir and configured to, when rotated, allow moving the suspension inside the tank, the system being characterized in that it comprises at least one channel for supplying a rheology modifier into the tank.

According to advantageous and non-limiting characteristics, taken alone or in any combination:

• the rheology modifier supply channel extends from a rheology modifier inlet opening and opens into the reservoir, and the rheology modifier supply channel comprises at least one primary channel and a plurality of secondary channels , the primary channel extending from the rheology modifier inlet opening to an inlet port of each secondary channel, each secondary channel extending from the primary channel to a respective outlet opening of rheology modifier and outlet into the reservoir;
• the system comprises a conduit for conveying the suspension disposed in the screw and extending from an inlet opening of the suspension and opening onto the interior of the tank, and the screw extends in an axial direction and in which the rheology modifier supply channel is arranged to bring the rheology modifier to the reservoir such that the rheology modifier circulates in a first direction in the axial direction and the suspension conveying conduit is arranged to bring the suspension to the reservoir such that the suspension circulates in a second direction in the axial direction, the second direction being opposite the first direction;
• the system comprises a suspension delivery conduit disposed in the screw and extending from an inlet opening of the suspension and opening onto the interior of the tank, and part of the rheology modifier supply channel is coaxial with the suspension routing conduit;
• the system comprises an inlet opening for the suspension opening onto the interior of the tank, the screw extends in an axial direction, the rheology modifier supply channel is arranged to bring the rheology modifier to the tank such that the rheology modifier circulates in a first direction in the axial direction and the inlet opening of the suspension is arranged to allow the circulation of the suspension in the tank in a second direction in the axial direction, the second meaning being opposite to the first meaning;
• the screw comprises blades and the rheology modifier outlet opening is provided on a blade or between blades;
• The system comes in the form of a screw press or a horizontal screw centrifuge.

DESCRIPTION OF FIGURES

Other characteristics and advantages of the present invention will appear on reading the following description of a preferred embodiment. This description will be given with reference to the appended figures including:

- There represents a separation system according to a first embodiment;

- There represents a separation system according to a second embodiment;

- There represents a variant of the separation system shown in ;

- There represents a variant of the separation system shown in ;

- There illustrates the steps of a separation process.

DETAILED DESCRIPTION OF THE INVENTION

System

According to a first aspect, a separation system 1 is proposed configured to separate at least one solid and at least one liquid from a suspension. By definition, a suspension is a mixture formed of solid particles which float in a fluid. In the remainder of the description, we are particularly interested in mud, for example from the mining industry. Mud is a suspension typically comprising water (i.e. the liquid) and fine sedimentary particles of silt and clay (i.e. the solids). Thus, the separation system 1 is preferably adapted to separate at least one solid and at least one liquid from a sludge, preferably a sludge containing clay. Mud may also contain phosphates. However, the invention is not limited to the separation of solids and liquids from a sludge. Furthermore, the suspension may comprise two or more liquids, in particular liquids having different densities.

With reference to one of Figures 1 to 4, such a system comprises a reservoir 2 adapted to contain the suspension. The system includes a suspension inlet opening 82 to allow suspension inlet into the tank 2. The suspension inlet opening 82 can be located at different locations in the system as will be described hereinafter. description. The reservoir 2 comprises a wall which defines an internal volume of the reservoir 2. The reservoir 2 extends preferentially longitudinally in an axial direction D. In a certain embodiment, the reservoir 2 is adapted to be rotated relative to the axial direction D. This is the case for example of a separation system 1 taking the form of a horizontal screw centrifuge 4. The system also includes at least one solid outlet opening 90 to allow the exit of a part of suspension depleted in liquid (and therefore rich in solid). The system further comprises at least one liquid outlet opening 92 to allow the exit of a portion of suspension depleted in solid (and therefore rich in liquid). More particularly, according to an embodiment illustrated in Figures 1 and 3, the system comprises a chamber 94 in fluid communication with the reservoir 2 and adapted to receive a portion of suspension depleted in solid (and therefore rich in liquid) from the reservoir 2 to then allow the evacuation of the suspension part depleted in solid via the liquid outlet opening 92.

A screw 4 is placed in the tank 2. The screw 4 can take any appropriate shape extending preferably in an axial direction X. The screw 4 has a shape of revolution which extends along and around the axial direction such as a cylindrical shape of revolution, or tubular, centered on the axial direction X. Preferably, the axial direction X is collinear with the direction D so that the screw 4 extends in the same direction as the reservoir 2. The screw 4 comprises an external surface facing the wall of the tank 2. The screw 4 is configured to, when rotated, allow the suspension to move inside the tank 2.

Advantageously, the screw 4 comprises blades 10. Concretely, the blades 10 are arranged along the external surface of the screw 4. Preferably, the blades 10 are regularly arranged on the screw 4. By "regularly", we mean that the blades 10 are arranged equidistant from each other.

Screw 4 is at least partially hollow. Indeed, the screw 4 comprises at least one feed channel 6 of a rheology modifier. The supply channel 6 of the rheology modifier opens into the reservoir 2 extends from a rheology modifier inlet opening 66 to a rheology modifier outlet opening 69. In a certain embodiment, the feed channel 6 extends into the screw 4 in the axial direction.

By definition, rheology is the science, the study of the phenomena which condition the flow and deformation of matter (plasticity, viscosity, elasticity). As such, the rheological properties of a material include viscosity, plasticity and elasticity. Therefore, the rheology modifier is a substance suitable for modifying the rheological properties of a material. Rheology modifier is usually a solution. The rheology modifier comprises at least one element selected from anionic acrylic acid polymer, sodium silicate, lignosulfonate, naphthalene sulfonate - formaldehyde condensate (NSF), polyisoprene sulfonic acid soda (Dynaflow -K), carboxylic acid derivative (AC 1320), carboxymethylcellulose, naphthalene additive (P), naphthalene-toluene additive (R), sulfonic acid,Tri-polyphosphate of sodium (STPP), sodium carbonate, xanthan gum, sodium calcium lignosulfonate (LS), polycarboxylic acid (PC), starch graft copolymer synthesized using styrene sulfonate ( SSS), hydroxyethyl acrylate (HEA) and sodium methylmercury (MBS), hydroxyethyl acrylate (HEA) and methylacrylic acid (MAA), humic acid-acrylic acid graft copolymer sulfonated (SHA), sulfonated acetone-formaldehyde (SAF), polyacrylic acid (PA) additives, poly(styrene-co-maleic anhydride-g-sodium naphthylamine sulfonate) (SMANS), poly (styrene-co-methoxypolyethylene glycol maleic acid monoester-g-naphthylamine sulfonate) (SMANP), sodium oleate (SO), sodium dodecyl benzene sulfonate (DBS), sodium lauryl sulfate, sulfonated used motor oil, newly synthesized tannic acid-acrylic acid (TAA) compound, newly synthesized tannic acid-itaconic acid (TIA) compound, oxidized methylated sulfonated lignin (OSL) , sulfonated melamine-formaldehyde resin (SMF), sodium copolymer of maleic acid and acrylic acid (MA-AAS), quicklime (CaO), p-tert-octylphenoxy-polyethoxyethanol (Triton 405), Rokanol LO18, Rokwinol 60 (polyoxyethylated sorbitol stearate), p-octyl polyethylene glycol phenyl ether (TX), polysorbate 20 (Aloe vera juice), saponin, polyoxyethylene polycarboxylic ether (PPA), polyoxyethylene lauryl ether (PXLE), alcohol additives, cetyl trimethyl ammonium bromide (CTAB), amphoteric surfactant synthesized using methyl acrylic acid (MAA), sodium allyl sulfonate (SAS) and methacryloxyethyltrimethyl (DMC), sodium dodecyl sulfonate "SDS" (anionic - synthetic) + Saponin (non-ionic - natural), hexadecyltrimethylammonium bromide "CTAB" (cationic - synthetic) + Saponin (non-ionic - natural), di-docyl ammonium bromide "DDAB" (cationic - synthetic) + Saponin (non-ionic - natural), sodium decyl benzene sulfate "SDBS" (cationic - synthetic) + Saponin ( non-ionic - natural), polycarboxylate acid (PCA), polyacrylic acid (PAA), sodium lignosulfonate (SLS), xanthan gum (XG), polypropylene oxide (PPO), polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), black liquor (containing alkaline salts and lignin constituents as well as cellulose and hemicellulose ), black liquor (containing alkaline salts and lignin constituents as well as cellulose and hemicellulose fibers), polyacrylic acids, sodium polyacrylate and phosphates (AG Disper), citric acid, sodium hydroxide, sodium hexametaphosphate (SHMP), lime, polyacrylamides, acti-gel, bio-additive extracted from Indian spinach, bio-additive extracted from Bellyache shrub, polyethyleneimines, polyvinylamines, polyacrylate, copolymer of (meth)acrylic acid and acrylamide, (meth)acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, polymers taurine modified, naphthalene sulfonates and hydroxymethyl diphosphonic acid polymers.

The supply channel 6 is adapted to convey the rheology modifier into the reservoir 2. The supply channel 6 therefore ensures a fluid connection between a reserve of rheology modifier and the reservoir 2 of the separation system 1. The supply channel 6 the feed 6 is in fluidic communication with a reserve of rheology modifier via the rheology modifier inlet opening 66. The feed channel 6 opens into the reservoir 2. The screw 4 therefore defines at least one outlet opening rheology modifier 69. The rheology modifier outlet opening 69 can be located on the external surface of the screw 4 or on a blade 10 of the screw 4.

According to a preferred embodiment, the screw 4 defines a plurality of rheology modifier outlet openings 69. In this case, the rheology modifier outlet openings 69 are preferably located regularly on the external surface of the screw 4 In other words, the rheology modifier outlet openings 69 are preferably located equidistant from each other. The rheology modifier outlet openings 69 can also be located on the blades 10 of the screw 4, only on certain blades 10 among all the blades 10 of the screw 4 or on all of the blades 10 of the screw 4. A plurality of rheology modifier outlet openings 69 can also be located on the same blade. Thus, we can find rheology modifier outlet openings 69 at the level of the blades 10 and between the blades 10, on the external surface of the screw 4.

According to this embodiment, the feed channel 6 comprises at least one primary channel 62 and a plurality of secondary channels 64. The primary channel 62 extends from the rheology modifier inlet opening 66 to an orifice inlet 68 of each secondary channel 64. Each secondary channel 64 extends from an inlet orifice 68 of secondary channel 64, i.e. from the primary channel 62, to a respective rheology modifier outlet opening 69. Each secondary channel 64 therefore opens into reservoir 2. In this embodiment, the rheology modifier can be brought simultaneously into several zones of reservoir 2.

According to a first embodiment illustrated in Figures 1 and 3, the separation system 1 comprises a suspension inlet opening 82 located at the wall of the tank 2. In other words, the wall of the tank 2 defines the suspension inlet opening 82 and the suspension is conveyed into the tank 2 directly via the suspension inlet opening 82. This embodiment corresponds for example to a separation system 1 which is in the form of a screw press 4.

According to a second embodiment illustrated in Figures 2 and 4, the separation system 1 comprises a conveying conduit 8 of the suspension disposed in the screw 4. The conveying conduit 8 defines the suspension inlet opening 82 The delivery conduit 8 extends in the screw 4 from the suspension inlet opening 82 and to one or more suspension outlet openings. The delivery conduit 8 opens into the tank 2. As a result, the suspension is not routed into the tank 2 directly via the suspension inlet opening 82. According to this second embodiment, the suspension circulates in the conveying conduit 8, and therefore within the screw 4, before entering the tank 2. This embodiment corresponds for example to a separation system 1 which is in the form of a horizontal centrifuge with screw 4.

Similar to rheology modifier outlet openings 69, the suspension outlet opening(s) 84 are located on the external surface of the screw 4. The screw 4 therefore defines at least one suspension outlet opening 84. The screw 4 can define a plurality of suspension outlet openings 84. In this case, the suspension outlet openings 84 are typically located axially at the same level.

According to a preferred embodiment, the screw 4 defines a plurality of suspension modifier outlet openings 84. Consequently, the routing conduit 8 comprises at least one primary conduit 81 and a plurality of secondary conduits 83. The conduit primary 81 extends from the suspension inlet opening 82 to an inlet orifice 85 of each secondary conduit 83. Each secondary conduit 83 extends from an inlet orifice 85 of secondary conduit 83, i.e. from the primary conduit 81, up to a respective suspension outlet opening 84. Each secondary conduit 83 therefore opens into the tank 2. In this embodiment, the suspension can be brought simultaneously into several zones of the tank 2.

According to an embodiment illustrated in Figures 1 and 2, the separation system 1 is designed so that the suspension circulates countercurrent to the rheology modifier. More precisely, the rheology modifier circulates in a first direction in the axial direction the suspension circulates in a second direction in the axial direction (indicated by the dotted arrows), the second direction being opposite the first direction. According to this "counter-current" embodiment, when the rheology modifier enters the tank 2, turbulence is created between the suspension already present in the tank 2 and the rheology modifier which promotes mixing of the suspension with the rheology modifier.

In the embodiment illustrated in , the suspension inlet opening 82 is disposed at one end of the system opposite the end of the system at which the rheology modifier inlet opening 66 is disposed. The rheology modifier inlet channel 6 is arranged to bring the rheology modifier to the reservoir 2 such that the rheology modifier circulates in a first direction in the axial direction and in which the inlet opening of the suspension 82 is arranged to allow the circulation of the suspension in the tank 2 in a second direction in the axial direction, the second direction being opposite the first direction.

In the embodiment illustrated in , the conveying conduit 8 and the supply channel 6 are arranged so that the suspension circulates against the current of the rheology modifier. More precisely, the rheology modifier supply channel 6 is arranged to bring the rheology modifier to the reservoir 2 such that the rheology modifier circulates in a first direction in the axial direction axial that the suspension circulates in a second direction in the axial direction (indicated by the dotted arrows), the second direction being opposite the first direction.

According to another embodiment illustrated in Figures 3 and 4, the separation system 1 is designed so that the suspension circulates in the same direction as the rheology modifier. More precisely, the rheology modifier circulates in a first direction in the axial direction suspension circulates in this same first direction in the axial direction (indicated by the dotted arrows).

In the embodiment illustrated in , the suspension inlet opening 82 is disposed at the same end of the system at which the rheology modifier inlet opening 66 is disposed. The suspension inlet opening 82 is arranged to allow circulation of the suspension in the reservoir 2 in a first direction in the axial direction, the first direction being identical to the direction of circulation of the rheology modifier in the rheology modifier supply channel 6.

In the embodiment illustrated in , the delivery conduit 8 and the supply channel 6 are arranged so that the suspension circulates in the same direction as the rheology modifier. More precisely, the rheology modifier supply channel 6 is arranged to bring the rheology modifier to the reservoir 2 such that the rheology modifier circulates in a first direction in the axial direction axial suspension circulates in this same first direction in the axial direction (indicated by the dotted arrows).

Preferably, at least part of the rheology modifier supply channel 6 is coaxial with the suspension conveying conduit 8. More precisely, preferably, part of the rheology modifier supply channel 6 is arranged inside the suspension conveying conduit 8. Concretely, it is preferably a part of the primary channel 62 of the supply channel 6 which is coaxial with the primary conduit 81 of the conveying conduit 8 of the suspension.

Process

According to a second aspect, a method is proposed for separating a solid and at least one liquid contained in a suspension by the separation system 1 described above.

In reference to the , preferably, the method comprises a step of introducing a suspension into the tank 2 of the separation system 1. The suspension is introduced via the suspension inlet opening 82. If the separation system 1 is a system separation system 1 according to a first embodiment illustrated in Figures 1 and 3, the suspension enters directly into the tank 2 via the suspension inlet opening 82. If the separation system 1 is a separation system 1 according to a second embodiment illustrated in Figures 2 and 4, the suspension circulates in the conveying conduit 8 before entering the tank 2.

Typically, the separation of solid and liquid from the suspension is due to compression or centrifugal force.

More precisely, according to a first embodiment, the tank 2 is adapted to be rotated relative to its axial direction D. This rotation generates a centrifugal force which causes the projection of solid particles (heavier than the liquid) against the wall of the tank 2. The screw 4 of the separation system 1 which is also in rotation allows the movement of the suspension inside the tank 2 such that the liquid is moved in a direction of liquid evacuation according to the axial direction The solid and the liquid are then evacuated from the tank 2 respectively via the solid outlet openings 90 and the liquid outlet openings 92.

According to a second embodiment, the screw 4, when rotating, compresses the suspension so that the solid is separated from the liquid in the suspension. The solid and the liquid are then evacuated from the tank 2 respectively via the solid outlet openings 90 and the liquid outlet openings 92.

The separation process is characterized in that it comprises a step a) of introducing into the tank 2 a rheology modifier adapted to fluidize the suspension. The rheology modifier is first introduced into feed channel 6 via the modifier inlet opening. Then, the modifier flows through the inlet channel 6 and enters the tank 2 via the modifier outlet opening.

The modifier is advantageously introduced into a zone of the tank 2 where the solid content of the suspension is greater than a solid content threshold. More precisely, it is desired that the modifier be introduced into a strategic zone of the reservoir 2 where the solid content of the suspension is so high that, if no rheology modifier was introduced, the torque necessary to drive the screw 4 to move the suspension in this area of the tank 2 would become greater than the maximum torque that can be provided by the motor driving the screw 4. The solid content threshold is preferably greater than 62%.

Preferably, the quantity of rheology modifier introduced into the tank 2 is between 0.04% and 0.8% by mass of the suspension and, more preferably and in particular in the case where the suspension is a mud of phosphate clay, between 0.04% and 0.2% by mass of the suspension.

Thanks to the rheology modifier, it is possible to more effectively separate the solid from the liquid in the suspension. Indeed, at the end of a separation process, a liquid is generally obtained on one side and, on the other side, a solid mixed with liquid. The rheology modifier makes it possible to obtain a part of suspension depleted in liquid whose solid content is greater than a part of suspension containing solid obtained without the use of a rheology modifier.

The rheology modifier makes it possible in particular to compensate for the viscous behavior of the clay. Indeed, by modifying the rheological properties of the suspension, the rheology modifier makes it possible to reduce the deformation threshold stress and the flow threshold stress of the suspension and in particular of the part of the suspension depleted in liquid, preferably whose solid rate is greater than 62%. Consequently, the torque to be provided necessary to drive the screw to obtain a part of suspension depleted in liquid whose solid content is preferably greater than 62% is reduced.

The invention is not limited to the embodiments described and represented in the appended figures. Modifications remain possible, particularly from the point of view of the constitution of the various technical characteristics or by substitution of technical equivalents, without departing from general education.

Claims (15)

Method for separating a solid and at least one liquid contained in a suspension by a separation system (1) configured to separate the solid and the liquid from the suspension, the separation system (1) comprising at least one tank (2) and a screw (4) configured to, when rotated, allow the suspension to move inside the tank (2), the method being characterized in that it comprises a step of:
a) introduction into the tank (2) of a rheology modifier adapted to fluidize the suspension. Method according to claim 1, in which the rheology modifier is introduced into a zone of the tank (2) where the solid content of the suspension is greater than a solid content threshold. A method according to claim 1, wherein the rheology modifier comprises at least one element selected from anionic acrylic acid polymer, sodium silicate, lignosulfonate, naphthalene sulfonate - formaldehyde condensate (NSF), sodium hydroxide polyisoprene sulfonic acid (Dynaflow-K), carboxylic acid derivative (AC 1320), carboxymethylcellulose, naphthalene additive (P), naphthalene-toluene additive (R), sulfonic acid, sodium tri-polyphosphate (STPP), sodium carbonate, xanthan gum, sodium calcium lignosulfonate (LS), polycarboxylic acid (PC), starch graft copolymer synthesized using styrene sulfonate (SSS), hydroxyethyl acrylate (HEA) and sodium methylmercury (MBS), hydroxyethyl acrylate (HEA) and methylacrylic acid (MAA), humic acid-sulfonated acrylic acid (SHA) graft copolymer, sulfonated acetone-formaldehyde (SAF), polyacrylic acid (PA) additives, poly(styrene-co-maleic anhydride-g-naphthylamine sulfonate) sodium) (SMANS), poly(styrene-co-methoxypolyethylene glycol maleic acid monoester-g-naphthylamine sulfonate) (SMANP), sodium oleate (SO), sodium dodecyl benzene sulfonate (DBS) , sodium lauryl sulfate, sulfonated used motor oil, newly synthesized tannic acid-acrylic acid (TAA) compound, newly synthesized tannic acid-itaconic acid (TIA) compound, oxidized methylated sulfonated lignin (OSL), sulfonated melamine-formaldehyde resin (SMF), sodium maleic acid-acrylic acid copolymer (MA-ASA), quicklime (CaO), p-tert -octylphenoxy-polyethoxyethanol (Triton , saponin, polyoxyethylene polycarboxylic ether (PPA), polyoxyethylene lauryl ether (PXLE), alcohol additives, cetyl trimethyl ammonium bromide (CTAB), amphoteric surfactant synthesized using methyl acrylic acid (MAA), sodium allyl sulfonate (SAS) and methacryloxyethyltrimethyl (DMC), sodium dodecyl sulfonate "SDS" (anionic - synthetic) + Saponin (non-ionic - natural), hexadecyltrimethylammonium bromide " CTAB" (cationic - synthetic) + Saponin (non-ionic - natural), di-docyl ammonium bromide "DDAB" (cationic - synthetic) + Saponin (non-ionic - natural), sodium decyl benzene sulfate "SDBS" (cationic - synthetic) + Saponin (non-ionic - natural), polycarboxylate acid (PCA), polyacrylic acid (PAA), sodium lignosulfonate (SLS), xanthan gum (XG), polypropylene oxide (PPO), polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), black liquor (containing alkali salts and lignin constituents as well as cellulose and hemicellulose), black liquor (containing alkali salts and lignin constituents as well as cellulose and hemicellulose fibers), polyacrylic acids, sodium polyacrylate and phosphates (AG Disper ), citric acid, sodium hydroxide, sodium hexametaphosphate (SHMP), lime, polyacrylamides, acti-gel, bio-additive extracted from Indian spinach, bio-additive extracted from the Bellyache shrub, polyethyleneimines, polyvinylamines, polyacrylate, copolymer of (meth)acrylic acid and acrylamide, (meth)acrylic acid, 2-acrylamide acid -2-methylpropane sulfonic acid, taurine-modified polymers, naphthalene sulfonates and hydroxymethyl diphosphonic acid polymers. Method according to one of claims 1 to 3 in which the suspension is a phosphate slurry. Method according to one of claims 1 to 4 in which the suspension is a mud containing clay. Method according to one of claims 1 to 5, in which the quantity of rheology modifier introduced into the reservoir (2) is between 0.04% and 0.8% by mass of the suspension. Method according to claim 6 in combination with claims 4 and 5, in which the quantity of rheology modifier introduced into the reservoir (2) is between 0.04% and 0.2% by mass of the suspension. Method according to one of claims 5 to 7 in combination with claim 2, in which the solid content threshold is greater than 62%. Separation system (1) configured to separate a solid and at least one liquid from a suspension comprising a reservoir (2), a screw (4) disposed in the reservoir (2) and configured to, when rotated , allow the suspension to move inside the tank (2), the system being characterized in that it comprises at least one supply channel (6) of a rheology modifier into the tank (2). A system according to claim 9, wherein the rheology modifier feed channel (6) extends from a rheology modifier inlet opening and opens into the reservoir (2), and wherein the feed channel A rheology modifier (6) includes at least one primary channel (62) and a plurality of secondary channels (64), the primary channel (62) extending from the rheology modifier inlet opening (66) to 'to an inlet port (68) of each secondary channel (64), each secondary channel (64) extending from the primary channel (62) to a respective rheology modifier outlet opening (69) and opening into the tank (2). System according to one of claims 9 and 10, comprising a conveying conduit (8) of the suspension disposed in the screw (4) and extending from an inlet opening of the suspension (82) and opening onto the interior of the reservoir (2), in which the screw (4) extends in an axial direction and in which the rheology modifier supply channel (6) is arranged to bring the rheology modifier to the reservoir ( 2) such that the rheology modifier circulates in a first direction in the axial direction and in which the suspension conveying conduit (8) is arranged to bring the suspension to the reservoir (2) such that the suspension circulates in a second direction in the axial direction, the second direction being opposite the first direction. System according to one of claims 9 and 10, comprising a conveying conduit (8) of the suspension disposed in the screw (4) and extending from an inlet opening of the suspension (82) and opening onto the inside the reservoir (2), and in which part of the rheology modifier supply channel (6) is coaxial with the suspension conveying conduit (8). System according to one of claims 9 and 10, comprising an inlet opening of the suspension (82) opening onto the interior of the tank (2), in which the screw (4) extends in an axial direction and in in which the rheology modifier supply channel (6) is arranged to bring the rheology modifier to the reservoir (2) such that the rheology modifier circulates in a first direction in the axial direction and in which the suspension inlet opening (82) is arranged to allow the circulation of the suspension in the tank (2) in a second direction in the axial direction, the second direction being opposite the first direction. System according to one of claims 9 to 12, in which the screw (4) comprises blades (10) and the rheology modifier outlet opening (69) is arranged on a blade (10) or between blades ( 10). System according to one of claims 9 to 13, in the form of a screw press (4) or a horizontal screw centrifuge (4).