EP2579987B1 - Use of the naturally occurring magnetic components of ores - Google Patents

Description

The present invention relates to a method for separating at least one first substance, which is a hydrophobic metal compound or carbon, from a mixture comprising these at least one first substance, at least one second substance, which is a hydrophilic metal compound, and magnetic particles, comprising the following steps (A) at least partially separating the magnetic particles by applying a magnetic field gradient, optionally in the presence of at least one dispersing agent, in order to obtain a mixture comprising at least a first substance and at least a second substance and a reduced amount of magnetic particles, the step ( A) separated magnetic particles are used in step (B), and the magnetic particles separated in step (A) are hydrophobized on the surface with at least one surface-active substance before use in step (B), (B) contacting the mixture e Containing at least a first substance and at least a second substance from step (A) with the magnetic particles obtained in step (A) and optionally further magnetic particles which are hydrophobicized on the surface with at least one surface-active substance, so that the at least one first Attach substance and the magnetic particles, the attachment being effected by attractive forces between the at least one first substance and the magnetic particles, (C) separating the addition product from the mixture from step (B) by applying a magnetic field gradient and (D) splitting the separated addition product from step (C) in order to obtain the at least one first substance and the magnetic particles separately.
In particular, the present invention relates to a method for enriching ores in the presence of gait.
Methods for separating value ores from mixtures containing these are already known from the prior art.
WO 02/0066168 A1 relates to a process for the separation of valuable ores from mixtures containing these, in which suspensions or slurries of these mixtures are treated with particles which are magnetic and / or floatable in aqueous solutions. After adding the magnetic and / or buoyant particles, a magnetic field is applied so that the agglomerates are separated from the mixture. However, the degree of binding of the magnetic particles to the ore and the strength of the bond is not sufficient to carry out the process with a sufficiently high yield and effectiveness.

US 4,657,666 discloses a process for the enrichment of value ores, wherein the gait present in the gangue is reacted with magnetic particles, whereby agglomerates are formed due to the hydrophobic interactions. The magnetic particles are made hydrophobic on the surface by treatment with hydrophobic compounds, so that there is a connection to the ore. The agglomerates are then separated from the mixture by a magnetic field. The cited document also discloses that the ores are treated with a surface activating solution of 1% sodium ethyl xanthate before the magnetic particle is added. In this method, a separation of valuable ore and magnetic particles takes place by destroying the surface-activating substance which has been applied to the valuable ore in the form of the surface-activating solution. Furthermore, only C ₄ hydrophobizing agents are used for the ore in this process.

US 4,834,898 discloses a method for separating non-magnetic materials by contacting them with magnetic reagents which are coated with two layers of surface-active substances. US 4,834,898 further discloses that the surface charge of the non-magnetic particles to be separated can be affected by various types and concentrations of electrolyte reagents. For example, the surface charge is changed by adding multivalent anions, for example tripolyphosphate ions.

SR Gray, D. Landberg, NB Gray, Extractive Metallurgy Conference, Perth, 2-4 October 1991, pages 223-226 discloses a method for recovering small gold particles by contacting the particles with magnetite. Before contacting, the gold particles are treated with potassium amyl xanthate. A method for separating the gold particles from at least one hydrophilic substance is not disclosed in this document.

WO 2007/008322 A1 discloses a magnetic particle, which is hydrophobic on the surface, for the separation of impurities from mineral substances by magnetic separation processes. According to WO 2007/008322 A1 a dispersant selected from sodium silicate, sodium polyacrylate or sodium hexametaphosphate can be added to the solution or dispersion.

WO 2009/030669 A2 discloses a method for separating valuable ores from mixtures of these with the gait through magnetic particles, the valuable ore first being hydrophobicized with a suitable substance, so that the hydrophobicized valuable ore and the magnetic particles can accumulate and be separated off. WHERE 2009/065802 A2 discloses a similar method for separating ore from gait by magnetic particles, the attachment of magnetic particles and ore based on different surface charges. Both methods can still be improved in terms of their efficiency.

1. (A) wenigstens teilweises Abtrennen der magnetischen Partikel durch Anlegen eines magnetischen Feldgradienten, gegebenenfalls in Gegenwart wenigstens eines Dispersionsmittels, um eine Mischung enthaltend wenigstens einen ersten Stoff und wenigstens einen zweiten Stoff und eine verringerte Menge an magnetischen Partikeln zu erhalten, wobei die in Schritt (A) abgetrennten magnetischen Partikel in Schritt (B) eingesetzt werden, und wobei die in Schritt (A) separierten magnetischen Partikel vor Verwendung in Schritt (B) an der Oberfläche mit wenigstens einer oberflächenaktiven Substanz hydrophobiert werden,
2. (B) Inkontaktbringen der Mischung enthaltend wenigstens einen ersten Stoff und wenigstens einen zweiten Stoff aus Schritt (A) mit den in Schritt (A) erhaltenen magnetischen Partikeln sowie gegebenenfalls weiteren magnetischen Partikeln, die an der Oberfläche mit wenigstens einer oberflächenaktiven Substanz hydrophobiert sind, so dass sich der wenigstens eine erste Stoff und die magnetischen Partikel anlagern, wobei das Anlagern durch anziehende Kräfte zwischen dem wenigstens einen ersten Stoff und den magnetischen Partikeln erfolgt,
3. (C) Abtrennen des Anlagerungsproduktes aus der Mischung aus Schritt (B) durch Anlegen eines magnetischen Feldgradienten und
4. (D) Spalten des abgetrennten Anlagerungsproduktes aus Schritt (C), um den wenigstens einen ersten Stoff und die magnetischen Partikel separat zu erhalten.

The object of the present invention is to provide a method by which magnetic particles which are present in natural ore mixtures can be effectively separated, so that they do not interfere with the subsequent magnetic separation of the agglomerates containing valuable ore, for example in order to reduce the space-time yield of the Process, as well as a subsequent processing of the value ore to increase. A further object of the present invention is to provide a method by which at least one first substance, in particular an ore of value, can be efficiently separated from mixtures comprising at least one first substance, at least one second substance, in particular the gait, and magnetic particles. Furthermore, it is an object of the present invention to treat the first substance to be separated in such a way that the adduct between magnetic particles and the first substance is sufficiently stable to ensure a high yield of the first substance in the separation.
According to the invention, these objects are achieved by a method for separating at least one first substance, which is a hydrophobic metal compound or carbon, from a mixture comprising this at least one first substance, at least one second substance, which is a hydrophilic metal compound, and magnetic particles comprising the following steps:

1. (A) at least partially separating the magnetic particles by applying a magnetic field gradient, optionally in the presence of at least one dispersing agent, in order to obtain a mixture comprising at least one first substance and at least one second substance and a reduced amount of magnetic particles, the step ( A) separated magnetic particles are used in step (B), and the magnetic particles separated in step (A) are hydrophobicized on the surface with at least one surface-active substance before use in step (B),
2. (B) bringing the mixture comprising at least a first substance and at least a second substance from step (A) into contact with the magnetic particles obtained in step (A) and, if appropriate, further magnetic particles which have been hydrophobicized on the surface with at least one surface-active substance, so that the at least one first substance and the magnetic particles accumulate, the accumulation taking place by attractive forces between the at least one first substance and the magnetic particles,
3. (C) separating the adduct from the mixture from step (B) by applying a magnetic field gradient and
4. (D) cleaving the separated addition product from step (C) in order to obtain the at least one first substance and the magnetic particles separately.

In the context of the present invention, “hydrophobic” means that the corresponding particle is inherently hydrophobic, or can subsequently be rendered hydrophobic by treatment with the at least one surface-active substance. It is also possible for an intrinsically hydrophobic particle to be additionally rendered hydrophobic by treatment with the at least one surface-active substance.

In the context of the present invention, “hydrophobic” means that the surface of a corresponding “hydrophobic substance” or a “hydrophobized substance” has a contact angle of> 90 ° with water against air. In the context of the present invention, “hydrophilic” means that the surface of a corresponding “hydrophilic substance” has a contact angle of <90 ° with water against air.

In a further preferred embodiment of the process according to the invention, the at least one hydrophobic metal compound is selected from the group of the sulfidic ores, the oxidic and / or carbonate-containing ores, for example azurite [Cu ₃ (CO ₃ ) ₂ (OH) ₂ ], cuprite [Cu ₂ O] or malachite [Cu ₂ [(OH) ₂ | CO ₃ ]]), or the noble metals and their compounds.

Examples of sulfidic ores which can be used according to the invention are e.g. B. selected from the group of copper ores consisting of covellite CuS, molybdenum (IV) sulfide, chalcopyrite (copper pebbles) CuFeS ₂ , bornite Cu ₅ FeS ₄ , chalcocyte (copper luster) Cu ₂ S, zinc blende ZnS, galena PbS, pentlandite (Ni , Fe) _x S with x approximately equal to 0.9, and mixtures thereof.

The at least one second substance is preferably selected from the group consisting of oxidic and hydroxide metal compounds, for example silicon dioxide SiO ₂ , silicates, aluminosilicates, for example feldspar, for example albite Na (Si ₃ Al) O ₈ , mica, for example muscovite KAl ₂ [(OH , F) ₂ AlSi ₃ O ₁₀ ], garnets (Mg, Ca, Fe ^II ) ₃ (Al, Fe ^III ) ₂ (SiO ₄ ) ₃ , Al ₂ O3, FeO (OH), FeCO ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ and other related minerals and mixtures thereof.

Accordingly, untreated ore mixtures which are obtained from mine deposits are preferably used in the process according to the invention. In a preferred one Embodiment of the method according to the invention, the first substances to be separated are made hydrophobic on the surface.

In addition to the at least one first and the at least one second substance, there are magnetic particles in the mixture to be treated according to the invention.

According to the invention, all magnetic particles known to the person skilled in the art can be present in the mixture to be treated according to the invention.

M

ausgewählt aus Co, Ni, Mn, Zn und Mischungen davon und

x

≤ 1,

hexagonalen Ferriten, beispielsweise Barium- oder Strontiumferrit MFe₁₂O₁₉ mit M = Mg, Ca, Sr, Ba, und Mischungen davon.In a preferred embodiment of the process according to the invention, the mixture to be treated according to the invention contains magnetic particles selected from the group consisting of magnetic metals, for example iron, cobalt, nickel and mixtures thereof, ferromagnetic alloys of magnetic metals, magnetic iron oxides, for example magnetite (Fe ₃ O ₄ ), maghemite (Fe ₂ O ₃ ), pyrrhotine (Fe _1-x S with 0 <x <0.5), ilmenite (FeTiO ₃ ), other minerals of the FeO-Fe ₂ O ₃ -TiO ₂ system , cubic ferrites of the general formula (I)

M ²⁺ _x Fe ²⁺ _1-x Fe ³⁺ ₂ O ₄ (I)

With

M

selected from Co, Ni, Mn, Zn and mixtures thereof and

x

≤ 1,

hexagonal ferrites, for example barium or strontium ferrite MFe ₁₂ O ₁₉ with M = Mg, Ca, Sr, Ba, and mixtures thereof.

The average size of the magnetic particles present in the mixture to be treated according to the invention is generally from 100 nm to 100 μm.

In the mixture to be treated according to the invention, the magnetic particles are generally in an amount of 0.05 to 10% by weight, preferably 0.1 to 5% by weight, particularly preferably 0.2 to 2% by weight, in each case based on the entire mixture.

In a preferred embodiment of the method according to the invention, the mixture comprising at least one first substance, at least one second substance and magnetic particles in step (A) is in the form of particles with an average size of 100 nm to 100 μm, see for example US 5,051,199 . In a preferred embodiment, this particle size is obtained by grinding. Suitable processes and devices are known to the person skilled in the art, for example wet milling in a ball mill.

Thus, a preferred embodiment of the method according to the invention is characterized in that the mixture containing at least a first substance, at least a second substance and magnetic particles is ground to particles with an average size of 100 nm to 100 μm before or during step (A).

Preferred mixtures have a content of at least one first substance, in particular sulfidic minerals, of at least 0.4% by weight, particularly preferably at least 1% by weight, in each case based on the mixture as a whole.

The at least one second substance, in particular oxidic minerals, is preferably present in the mixture to be treated according to the invention in an amount such that the sum of magnetic particles, at least one first substance, at least one second substance and optionally further minerals results in 100% by weight .

Examples of sulfidic minerals which are present in the mixtures which can be used according to the invention are those mentioned above. In addition, sulfides of metals other than copper can also be present in the mixtures, for example sulfides of iron, lead, zinc or molybdenum, ie FeS / FeS ₂ , PbS, ZnS or MoS ₂ . Furthermore, oxidic compounds of metals and semimetals, for example silicates or borates or other salts of metals and semimetals, for example phosphates, sulfates or oxides / hydroxides / carbonates and other salts, for example azurite [Cu ₃ (CO ₃ ) ₂ (OH) ₂ ], malachite [Cu _{2 [} (OH) ₂ (CO ₃ )]], barite (BaSO ₄ ), monacite ((La-Lu) PO ₄ ). Further examples of the at least one first substance which is separated off by the process according to the invention are noble metals, for example Au, Pt, Pd, Rh etc., preferably in the solid state.

A typically used ore mixture which can be separated by the inventive method has the following composition: about 30 wt .-% SiO _2, about 30 wt .-% Na (Si ₃ Al) O _8, 2 wt .-% FeCuS ₂ , approx. 0.01% by weight MoS ₂ , approx. 1% by weight Fe ₃ O ₄ , balance chromium, iron, titanium and magnesium oxides.

The individual steps of the method according to the invention are described in detail below:

Step (A):

Step (A) of the method according to the invention comprises at least partially separating the magnetic particles by applying a magnetic field gradient, optionally in the presence of at least one dispersing agent, in order to obtain a mixture comprising at least one first substance and at least one second substance and a reduced amount of magnetic particles , wherein those separated in step (A) magnetic particles are used in step (B), and the magnetic particles separated in step (A) are hydrophobicized on the surface with at least one surface-active substance before use in step (B).

The magnetic particles can generally be separated off by all magnetic separation processes known to the person skilled in the art.

In one embodiment, step (A) of the process according to the invention is carried out without the addition of a dispersing agent, i. H. carried out in the absence of a dispersant.

Step (A) of the process according to the invention is carried out in a second, preferred embodiment in dispersion, i.e. H. carried out in the presence of at least one dispersant, d. H. the at least one first substance, the at least one second substance and the mixture containing the magnetic particles is present in at least one dispersant. If the mixture to be treated is provided in bulk, step (A) of the method according to the invention preferably first comprises the preparation of a dispersion. Methods for producing a dispersion are known to the person skilled in the art.

All dispersants in which the mixture to be treated according to the invention is not completely soluble are generally suitable as dispersants. Suitable dispersants are selected, for example, from the group consisting of water, water-soluble organic compounds, for example alcohols having 1 to 4 carbon atoms, and mixtures thereof. In a particularly preferred embodiment, the dispersant is water.

In general, the amount of dispersant can be selected so that a dispersion is obtained which is easy to stir and / or convey. In a preferred embodiment, the amount of mixture to be treated is 10 to 50% by weight, particularly preferably 25 to 40% by weight, based on the total slurry or dispersion.

Suitable devices for magnetic separation, preferably on an industrial scale, are known to the person skilled in the art.

Step (A) of the method according to the invention can be carried out in all suitable devices known to the person skilled in the art, for example in a wet drum separator, high-gradient magnetic separator or related devices.

Step (A) of the process according to the invention can be carried out at any suitable temperature, for example 10 to 60 ° C.

In step (A) of the method according to the invention, the magnetic particles which are present in the minerals to be treated preferably are at least partially separated off in order to obtain a mixture comprising at least one first substance and at least one second substance and a reduced amount of magnetic particles.

According to the invention, the magnetic particles in step (A) are generally separated off at least 50%, preferably at least 60%, particularly preferably at least 70%, very particularly preferably completely. It is preferred according to the invention to remove as large a proportion of the magnetic particles as possible in step (A) of the method according to the invention in order to obtain the described advantages according to the invention to the greatest extent possible.

After step (A), the separated magnetic particles can generally be separated from the remaining dispersion by all methods known to the person skilled in the art.

After step (A) of the process according to the invention, on the one hand a mixture containing at least a first and a second substance in a dispersing agent, and on the other hand magnetic particles, separately from one another, are obtained.

The magnetic particles obtained in step (A) of the process according to the invention, in particular the ferromagnetic minerals, can be used as raw material according to the invention and can be supplied to workup processes known to the person skilled in the art, for example smelting processes.

In a preferred embodiment of the method according to the invention, the magnetic particles obtained in step (A) are optionally subjected to further steps before use in step (B), for example grinding the particles to an average size of 100 nm to 20 μm, preferably by wet grinding.

The crushing is wet, preferably aqueous, in a ball mill, such as. B. in a rotary or agitator ball mill. Inert bodies with a diameter of 1 to 50 mm, consisting of metal or preferably of ceramic materials, can serve as grinding media.

The magnetic particles separated in step (A) are hydrophobized on the surface with at least one surface-active substance before use in step (B) or, depending on the embodiment of step (B), are functionalized accordingly.

The hydrophobization is preferably carried out by contacting the comminuted magnetic particles, which are separated off in step (A), with a suitable hydrophobizing agent, e.g. B. long-chain fatty acids, phosphonic acids, phosphoric acid mono- or diesters, or their salts, alternatively generated with mono- or dialkylsilanols, for example in situ by hydrolysis of corresponding alkyl alkoxysilanes, mono- or dialkylsiloxanes. The hydrophobization can be carried out in an aqueous or organic, preferably aqueous, medium. In one embodiment, a drying and / or calcination step, for example at a temperature below 200 ° C., of the hydrophobized magnetic particle is carried out before the reuse in step (B). However, a method is preferred which dispenses with this drying step.

An advantage of the method according to the invention, in particular step (A) according to the invention, is that magnetic particles which have a disruptive effect on the overall method are removed from the mixture before the at least one first substance is actually separated off. The separation according to the invention in step (A) removes the naturally occurring magnetic particles which are inactive in step (B) of the method according to the invention, as a result of which the space-time yield of the entire method can be increased. In the preferred embodiment, in which the magnetic particles separated in step (A) are reused in step (B) of the process according to the invention, the amount of magnetic particles to be used can additionally be reduced.

Step (B):

Step (B) of the method according to the invention comprises contacting the mixture comprising at least a first substance and at least a second substance from step (A) with magnetic particles which are hydrophobicized on the surface with at least one surface-active substance, so that the at least one first Attach material and the magnetic particles, the attachment taking place by attractive forces between the at least one first material and the magnetic particles.

In step (B) of the process according to the invention, it is generally possible to use all magnetic particles known to the person skilled in the art which meet the requirements of the process according to the invention, for example dispersibility in the dispersant used and ability to form sufficiently stable agglomerates with the at least one first substance.

Furthermore, the magnetic particles should have a sufficiently high saturation magnetizability, for example 25-300 emu / g, and a low remanence, so that the agglomerate can be separated from the dispersion in sufficient amount in step (C) of the process according to the invention.

M

ausgewählt aus Co, Ni, Mn, Zn und Mischungen davon und

x

≤ 1,

hexagonalen Ferriten, beispielsweise Barium- oder Strontiumferrit MFe₁₂O₁₉ mit M = Mg, Ca, Sr, Ba, und Mischungen davon.In a preferred embodiment of the method according to the invention, magnetic particles are selected in step (B) of the method according to the invention, selected from the group consisting of magnetic metals, for example iron, cobalt, nickel and mixtures thereof, ferromagnetic alloys of magnetic metals, magnetic iron oxides, for example magnetite (Fe ₃ O ₄ ), maghemite (Fe ₂ O ₃ ), pyrrhotine (Fe _1-x S with 0 <x <0.5), ilmenite (FeTiO ₃ ), other minerals of FeO-Fe ₂ O ₃ -TiO ₂ System, cubic ferrites of the general formula (I)

M ²⁺ _x Fe ²⁺ _1-x Fe ³⁺ ₂ O ₄ (I)

With

M

selected from Co, Ni, Mn, Zn and mixtures thereof and

x

≤ 1,

hexagonal ferrites, for example barium or strontium ferrite MFe ₁₂ O ₁₉ with M = Mg, Ca, Sr, Ba, and mixtures thereof.

In step (B) magnetite Fe ₃ O _{4 is} very particularly preferably used as the magnetic particle.

The size of the magnetic particles used according to the invention is preferably 10 nm to 1 μm.

The magnetic particles separated in step (A) are used in step (B). It is furthermore possible that in this preferred embodiment further magnetic particles of the same or a different type are added to the magnetic particles obtained in step (A) before they are used in step (B).

B

ausgewählt ist aus linearem oder verzweigtem C₃-C₃₀-Alkyl, C₃-C₃₀-Heteroalkyl, gegebenenfalls substituiertes C₆-C₃₀-Aryl, gegebenenfalls substituiertes C₆-C₃₀-Heteroalkyl, C₆-C₃₀-Aralkyl und

Y

eine Gruppe ist, mit der die Verbindung der allgemeinen Formel (II) an die magnetischen Partikel anbindet.

In a preferred embodiment, the magnetic particles used in step (B) of the process according to the invention can be hydrophobicized on the surface with at least one surface-active substance, for example with at least one hydrophobic compound selected from compounds of the general formula (II)

BY (II),

wherein

B

is selected from linear or branched C ₃ -C ₃₀ alkyl, C ₃ -C ₃₀ heteroalkyl, optionally substituted C ₆ -C ₃₀ aryl, optionally substituted C ₆ -C ₃₀ heteroalkyl, C ₆ -C ₃₀ aralkyl and

Y

is a group with which the compound of general formula (II) binds to the magnetic particles.

In a particularly preferred embodiment, B is a linear or branched C ₆ -C ₁₈ alkyl, preferably linear C ₈ -C ₁₂ alkyl, very particularly preferably a linear C ₁₂ alkyl. Heteroatoms optionally present according to the invention are selected from N, O, P, S and halogens such as F, Cl, Br and I.

In a further particularly preferred embodiment, Y is selected from the group consisting of - (X) _n -SiHal ₃ , - (X) _n -SiHHal ₂ , - (X) _n -SiH ₂ Hal with Hal equal to F, Cl, Br, I, and anionic groups such as - (X) _n -SiO ₃ ^3- , - (X) _n -CO ₂ ^- , - (X) _n -PO ₃ ^2- , - (X) _n -PO ₂ S ^2- , - (X) _n -POS ₂ ^2- , - (X) _n -PS ₃ ^2- , - (X) _n -PS ₂ ^- , - (X) _n -POS ^- , - (X) _n -PO ₂ ^- , - (X) _n -CO ₂ ^- , - (X) _n -CS ₂ ^- , - (X) _n -COS ^- , - (X) _n -C (S) NHOH, - (X) _n -S ^- with X = O, S, NH, CH ₂ and n = 0, 1 or 2, and optionally cations selected from the group consist of hydrogen, NR ₄ ⁺ with R the same independently of one another hydrogen and / or C ₁ -C ₈ alkyl , Alkali, alkaline earth metals or zinc, further - (X) _n -Si (OZ) ₄ with n = 0, 1 or 2 and Z = charge, hydrogen or short-chain alkyl radical.

If n = 2 in the formulas mentioned, there are two identical or different, preferably identical, groups B bound to a group Y.

Very particularly preferred hydrophobizing substances of the general formula (II) are alkyltrichlorosilanes (alkyl group with 6-12 carbon atoms), alkyltrimethoxysilanes (alkyl group with 6-12 carbon atoms), mono- and dialkyl esters of phosphoric acid (alkyl group with 6-15 carbon atoms), long-chain saturated and unsaturated fatty acids such as B. lauric acid, oleic acid, stearic acid or mixtures thereof.

According to the invention, the at least one first substance to be separated and the magnetic particles accumulate in step (B) of the method according to the invention.

The attachment according to step (B) can generally be carried out by all attractive forces known to the person skilled in the art between the at least one first substance and the magnetic particles. According to the invention, essentially only the at least one first substance and the magnetic particles accumulate in step (B) of the method according to the invention, whereas the at least one second substance and the magnetic particles essentially do not accumulate.

In a preferred embodiment of the method according to the invention, the mixture comprising at least one first substance and at least one second substance is ground before or during step (B) to give particles with a size of 100 nm to 100 μm.

In a preferred embodiment of step (B) of the method according to the invention, the at least one first substance and the magnetic particles are deposited due to hydrophobic interactions, different surface charges and / or compounds present in the mixture which selectively couple the at least one first substance and the magnetic particles , on.

The alternatives mentioned for the attachment of the at least one first substance and the magnetic particles are explained in detail below.

Embodiment B1:

In this particularly preferred embodiment B1 of the process according to the invention, step (B) is carried out by first bringing the at least one first substance contained in the mixture into contact with a surface-active substance in order to make it hydrophobic, this mixture is further brought into contact with magnetic particles, so that the magnetic particles and the at least one first substance that is hydrophobicized on the surface attach.

In the context of the present invention, "surface-active substance" means a substance which is able to remove the surface of the particle to be separated, i. H. of the at least one first substance, in the presence of the other particles which are not to be separated, so that an attachment of a hydrophobic particle is brought about by hydrophobic interactions. Surface-active substances which can be used according to the invention selectively attach to the at least one first substance and thereby bring about a suitable hydrophobicity of the first substance.

In the context of the present invention, “selective addition” means that the distribution coefficient of the surface-active substance between the surface of the at least one first substance and the surface of the at least one second substance is generally> 1, preferably> 100, particularly preferably> 10000, that is, the surface-active substance preferably attaches to the surface of the at least one first substance and not to the surface of the at least one second substance.

A

ausgewählt aus linearem oder verzweigtem C₃-C₃₀-Alkyl, C₃-C₃₀-Heteroalkyl, gegebenenfalls substituiertes C₆-C₃₀-Aryl, gegebenenfalls substituiertes C₆-C₃₀-Heteroalkyl, C₆-C₃₀-Aralkyl ist und

Z

eine Gruppe ist, mit der die Verbindung der allgemeinen Formel (III) an den wenigstens einen ersten, abzutrennenden Stoff anbindet, bedeuten.

In embodiment B1 of step (B) of the process according to the invention, a surface-active substance of the general formula (III) is preferred in the process according to the invention

AZ (III)

used, which binds to the at least a first substance, wherein

A

selected from linear or branched C ₃ -C ₃₀ alkyl, C ₃ -C ₃₀ heteroalkyl, optionally substituted C ₆ -C ₃₀ aryl, optionally substituted C ₆ -C ₃₀ heteroalkyl, C ₆ -C ₃₀ aralkyl and

Z.

is a group with which the compound of the general formula (III) binds to the at least one first substance to be separated.

In a particularly preferred embodiment, A is a linear or branched C ₄ -C ₁₂ alkyl, very particularly preferably a linear C ₄ or C ₈ alkyl. Heteroatoms optionally present according to the invention are selected from N, O, P, S and halogens such as F, Cl, Br and I.

In a further preferred embodiment, A is preferably a linear or branched, preferably linear, C ₆ -C ₂₀ -alkyl. Furthermore, A is preferably a branched C ₆ -C ₁₄ -alkyl, the at least one substituent, preferably having 1 to 6 carbon atoms, preferably in the 2-position, being present, for example 2-ethylhexyl and / or 2-propylheptyl.

In a further particularly preferred embodiment, Z is selected from the group consisting of anionic groups - (X) _n -PO ₃ ^2- , - (X) _n -PO ₂ S ^2- , - (X) _n -POS ₂ ^2- , - (X) _n -PS ₃ ^2- , ^- (X) _n -PS ₂ ^- , ^- (X) _n -POS ^- , - (X) _n -PO ₂ ^- , - (X) _n -PO ₃ ^2- - (X) _n -CO ₂ ^- , ^- (X) _n -CS ₂ ^- , - (X) _n -COS ^- , - (X) _n -C (S) NHOH, - (X) _n -S ^- with X selected from the group consisting of O, S, NH, CH ₂ and n = 0, 1 or 2, with optionally cations selected from the group consisting of hydrogen, NR ₄ ⁺ with R, independently of one another, hydrogen and / or C ₁ - C ₈ alkyl, alkali or alkaline earth metals. According to the invention, the anions mentioned and the corresponding cations form neutral compounds of the general formula (III).

If n = 2 in the formulas mentioned, there are two identical or different, preferably identical, groups A bonded to a group Z.

In a particularly preferred embodiment, compounds are used selected from the group consisting of xanthates AO-CS ₂ ^- , dialkyldithiophosphates (AO) ₂ -PS ₂ ^- , dialkyldithioposphinates (A) ₂ -PS ₂ ^- , dithiocarbamates A ₂ N-CS ₂ ^- , Xanthogenic acid ester AOC (= S) -S-A ', thionocarbamate A-NH-C (= S) -S-A', carboxythionocarbamate AOC (= O) -NH-C (= S) -S-A ', where A 'each aryl or short chain alkyl group, and unsaturated aliphatic radicals such as. B. allyl, buten-2-yl, 2-methylpropen-2-yl, or selected from the group mentioned for A, and A is independently a linear or branched, preferably linear, C ₆ -C ₂₀ alkyl, for example n Octyl, or a branched C ₆ -C ₁₄ alkyl, the branching preferably being in the 2-position, for example 2-ethylhexyl and / or 2-propylheptyl. The counterions in these compounds are preferably cations selected from the group consisting of hydrogen, NR ₄ ⁺ with R, independently of one another, hydrogen and / or C ₁ -C ₈ -alkyl, alkali or alkaline earth metals, in particular sodium or potassium.

Very particularly preferred compounds of the general formula (III) are n-octyl xanthates, di-n-octyl dithiophosphates, 2-ethylhexyl and 2-propylheptyl xanthates and dithiophosphates, for example sodium or potassium n-octyl xanthate, sodium or potassium di-n-octyldithiophosphate, or mixtures of these compounds.

For noble metals, for example Au, Pd, Rh etc., particularly preferred surface-active substances are mono-, di- and trithiols or 8-hydroxyquinolines, for example described in EP 1 200 408 B1 .

For metal oxides, for example FeO (OH), Fe ₃ O ₄ , ZnO etc., carbonates, for example azurite [Cu (CO ₃ ) ₂ (OH) ₂ ], malachite [Cu _{2 [} (OH) ₂ CO ₃ ]] particularly preferred surface-active substances octylphosphonic acid (OPS), (EtO) ₃ Si-A, (MeO) ₃ Si-A, with the meanings given above for A or long-chain saturated or unsaturated fatty acids such as. As oleic acid, lauric acid, etc. In a preferred embodiment of the process according to the invention, no hydroxamates are used as surface-active substances for modifying metal oxides.

For metal sulfides, for example Cu ₂ S, MoS ₂ , etc., particularly preferred surface-active substances are mono-, di- and trithiols or xanthates.

In a further preferred embodiment of the process according to the invention, Z is - (X) _n -CS ₂ ^- , - (X) _n -PO ₂ ^- or - (X) _n -S ^- with X equal to O and n equal to 0 or 1 and one Cation selected from hydrogen, sodium or potassium. Very particularly preferred surface-active substances are 1-octanethiol, potassium n-octylxanthate, potassium butylxanthate, octylphosphonic acid or carboxythionocarbamates AOC (= O) -NH-C (= S) -S-A ' and oxycarbonylthioureas AOC (= O) -NH-C (= S) -NH-A 'with the abovementioned meanings for A' and A.

The at least one surface-active substance is generally used in an amount sufficient to achieve the desired effect. In a preferred embodiment, the at least one surface-active substance is used in an amount of 5 to 1000 g per ton of mixture to be treated.

Further details of this embodiment are given in the WO 2009/030669 A2 disclosed.

Suitable magnetic particles are mentioned above. In embodiment B1, magnetic particles are particularly preferably used which are hydrophobized on the surface with at least one surface-active substance. Particularly preferred surface-active substances are the above-mentioned compounds of the general formula (II).

Embodiment B2:

In this further embodiment B2 of step (B) of the process according to the invention, the mixture to be treated from step (A) is first mixed with at least one hydrocarbon in an amount of from 0.01 to 0.4% by weight, based on the sum of treating mixture and at least one hydrocarbon in contact, and this mixture is further brought into contact with magnetic particles.

Embodiment B2 is particularly advantageous if, in addition to the at least one first and at least one second substance, at least one third substance is also present in the mixture. The at least one third substance is preferably selected from the group that has already been mentioned for the at least one second substance, the at least one second and the at least one third substance being different.

In the context of the present invention, hydrocarbon means an organic chemical compound which is essentially composed of carbon, hydrogen and optionally oxygen. If the hydrocarbons which can be used according to the invention also contain oxygen in addition to carbon and hydrogen, this is present, for example, in the form of ester, carboxylic acid and / or ether groups. In step (B) according to embodiment B2 of the process according to the invention, both an essentially uniform hydrocarbon and a mixture of hydrocarbons can be used.

Hydrocarbons or mixtures which can be used according to the invention generally have a low viscosity under the conditions of the process according to the invention, so that they are liquid and easily mobile under the process conditions according to the invention. It is preferred to use hydrocarbons or mixtures which have a viscosity of 0.1 to 100 cP, preferably 0.5 to 5 cP, in each case at 20 ° C.

Hydrocarbons or mixtures which can be used according to the invention generally have a flash point of 20 20 ° C., preferably ≥ 40 ° C. The present invention therefore also relates to the method according to the invention, the at least one hydrocarbon having a flash point of 20 20 ° C., particularly preferably 40 40 ° C.

In a preferred embodiment of the process according to the invention, the at least one hydrocarbon is selected from the group consisting of mineral oils, vegetable oils, biodiesel, BtL fuels (biomass-to-liquid), products of coal liquefaction, products of the GtL process (gas to liquid) Natural gas) and mixtures thereof.

Mineral oils are, for example, crude oil derivatives and / or oils produced by distillation from lignite, hard coal, peat, wood, petroleum and possibly also other mineral raw materials. Mineral oils generally consist of hydrocarbon mixtures of paraffinic, i.e. H. saturated chain hydrocarbons, naphthenic, d. H. saturated annular hydrocarbons, and aromatic hydrocarbons.

A particularly preferred crude oil derivative is diesel or gas oil. Diesel generally has a composition known to those skilled in the art. Essentially, diesel is based on mineral oil, i.e. H. Diesel is a fraction in the separation of mineral oil by distillation. The main components of diesel are mainly alkanes, cycloalkanes and aromatic hydrocarbons with about 9 to 22 carbon atoms per molecule and a boiling range from 170 ° C to 390 ° C.

Other names for suitable petroleum derivatives include: light gas oil (boiling point 235-300 ° C, depending on the specification also "diesel""dieselfuel""DK""heating oil light""HEL"), heavy gas oil (boiling point 300 to 375 ° C), and (in the USA) "No. 2 Fuel"
Vegetable oils are generally among the fats and fatty oils that are obtained from oil plants. Vegetable oils consist of triglycerides, for example. Vegetable oils suitable according to the invention are selected, for example, from the group consisting of sunflower oil, rapeseed oil, safflower oil, soybean oil, corn oil, peanut oil, olive oil, herring oil, cottonseed oil, palm oil and mixtures thereof.

Biodiesel generally has a composition known to those skilled in the art. Biodiesel essentially contains methyl esters of saturated C ₁₆ -C ₁₈ and unsaturated C ₁₈ fatty acids, in particular rapeseed oil methyl esters

Coal liquefaction products can be obtained, for example, by the Fischer-Tropsch or Sasol process. The BtL and GtL processes are known to the person skilled in the art.

In a preferred embodiment of the method according to the invention, in embodiment B2 of step (B), diesel, kerosene and / or light gas oil is used as the hydrocarbon. On a laboratory scale, diesel from the brands Solvesso® and / or Shellsol® can be used advantageously.

In step (B) according to embodiment B2 of the process according to the invention, at least one hydrophobizing agent can optionally also be added. Suitable hydrophobicizing agents are the above-mentioned compounds of the general formula (III).

Embodiment B3:

In this further embodiment B3 of step (B) of the process according to the invention, the mixture to be treated from step (A) is first brought into contact with at least one hydrophobizing agent, so that an adduct is formed from the at least one hydrophobizing agent and the at least one first substance. This adduct is then brought into contact with magnetic particles functionalized on the surface with at least one polymeric compound which has an LCST ( Lower Critical Solution Temperature ) at a temperature at which the polymeric compound has a hydrophobic character, so that the adduct and the functionalized magnetic particles agglomerate.

In embodiment B3 of step (B) of the process according to the invention, preference is given to using at least one water repellent according to the general formula (III) shown above. The statements made above also apply to the preferred embodiments.

The at least one hydrophobizing agent is generally used in an amount sufficient to achieve the desired effect. In a preferred embodiment, the at least one hydrophobizing agent in an amount from 0.01 to 5% by weight, based on the at least one first substance present in the mixture.

Furthermore, embodiment B3 of step (B) comprises contacting the adduct of at least one first substance and hydrophobicizing agent with magnetic particles that are surface-functionalized with at least one polymeric compound that has a transition temperature LCST ( Lower Critical Solution Temperature ). The above-mentioned can be used as magnetic particles.

In embodiment B3, the magnetic particles are functionalized on the surface with at least one polymeric compound.

The polymeric compounds used according to the invention are distinguished by the fact that they have a transition temperature LCST ( Lower Critical Solution Temperature ). Below this LCST, the polymeric compound has a hydrophilic character, since the polymer chain has a hydration shell, for example due to the addition of water molecules. Above the LCST, the polymeric compound has a hydrophobic character, since the polymer chain is no longer surrounded by a hydration shell, for example. Depending on the polymeric compound, the reverse case is also possible, namely that the polymeric compound has a hydrophobic character below the LCST and has a hydrophilic character above the LCST. If such a polymeric compound is heated from below the LCST to a temperature above the LCST, the polymeric compound switches from hydrophilic to hydrophobic at the LCST, or vice versa. The polymers which can be used according to the invention thus have a hydrophilic or hydrophobic character, depending on the temperature.

The change in the polymeric compound from hydrophobic to hydrophilic or vice versa corresponds to a phase transition which generally takes place in a closed system in a narrow temperature range of, for example, 0.5 ° C. In an open system, the phase transition can extend over a broader range of, for example, 15 ° C., for example by changing the concentration of the components present, for example polymers and / or foreign substances, varying the pH and / or the pressure. The temperature range in which the transition takes place generally increases with increasing chain length. When changing the molecular properties from hydrophilic to hydrophobic, some water molecules generally remain attached to the polymer, which are released successively. This process is generally completely reversible as long as the polymeric compound is not chemically modified, for example by increasing the pH.

The properties described for the polymeric compounds which can be used according to the invention are essentially also present in the case of the particles, in particular magnetic particles, modified with these polymeric compounds.

In a preferred embodiment of the method according to the invention, the polymeric compound is hydrophobic above the LCST and hydrophilic below the LCST.

According to the invention, all polymeric compounds which have an LCST, ie. H. which have a hydrophilic or hydrophobic character at different temperatures. In the context of the present invention, “polymer” means a, preferably organic, compound with a molecular weight of at least 500 g / mol, preferably 500 to 10,000 g / mol, particularly preferably 1000 to 7000 g / mol.

In a preferred embodiment of the process according to the invention, the at least one polymeric compound is selected from the group consisting of polyvinyl ethers, for example polyvinyl methyl ether, poly-N-alkyl-acrylamides, for example poly-NC ₁ -C ₆ -alkyl acrylamides, in particular poly N-isopropylacrylamide, or N-alkyl-acrylamide-acrylamide copolymers, poly-N-vinyl-caprolactams, copolymers based on alkylene oxides, for example copolymers of ethylene oxide, propylene oxide and / or butylene oxide, preferably polymeric compounds, obtainable by alkoxylation of C ₁ -C ₁₂ alcohols with 1 to 130 units of ethylene oxide, propylene oxide and / or butylene oxide, and mixtures thereof. Suitable polymeric compounds and processes for their preparation are, for example, in Li et al., International Journal of Pharmacology (2006), 2 (5), 513-519 , and Crespy et al., Polymer International (2007), 56 (12), 1461-1468 , called. These polymeric compounds are hydrophilic below the LCST and hydrophobic above the LCST.

According to the invention, the polymeric compounds mentioned which have an LCST are bonded to the corresponding magnetic particles by means of functional groups. These functional groups can be present per se in the polymeric compounds mentioned, or the functional groups can be introduced into the polymeric compounds by processes known to the person skilled in the art, i. H. the polymeric compounds are functionalized.

und Mischungen davon, besonders bevorzugt ausgewählt aus der Gruppe bestehend aus Thiolgruppe -SH, Carbonsäuregruppe -CO₂H, gegebenenfalls zumindest teilweise veresterte Phosphonsäuregruppe -PO₃R'₂ mit R' gleich Wasserstoff oder C₁-C₆-Alkyl (Va), gegebenenfalls zumindest teilweise veresterte Phosphorsäuregruppe -O-PO₃R"₂ mit R" gleich Wasserstoff oder C₁-C₆-Alkyl (Vb), Hydroxamatgruppe (Vc). Die Xanthogenatgruppe (Vd) ist bevorzugt für die Kupplung an sulfidische Verbindungen geeignet.Suitable functional groups are those which ensure a sufficiently strong bond between magnetic particles and polymeric compound, for example selected from the group consisting of thiol group -SH, carboxylic acid group -CO ₂ H, optionally at least partially esterified phosphonic acid group -PO ₃ R ' ₂ with R' is hydrogen or C ₁ -C ₆ -alkyl (Va), optionally at least partially esterified phosphoric acid group -O-PO ₃ R " ₂ with R" is hydrogen or C ₁ -C ₆ -alkyl (Vb), hydroxamate group (Vc), xanthate group (Vd)

and mixtures thereof, particularly preferably selected from the group consisting of thiol group -SH, carboxylic acid group -CO ₂ H, optionally at least partially esterified phosphonic acid group -PO ₃ R ' ₂ with R' equal to hydrogen or C ₁ -C ₆ alkyl (Va), optionally at least partially esterified phosphoric acid group -O-PO ₃ R " ₂ with R" equal to hydrogen or C ₁ -C ₆ alkyl (Vb), hydroxamate group (Vc). The xanthate group (Vd) is preferably suitable for coupling to sulfidic compounds.

F

funktionelle Gruppe, die selektiv an den wenigstens einen Magnetpartikel bindet,

B

Alkylrest mit 1 bis 6 Kohlenstoffatomen,

EO

Ethylenoxid,

PO

Propylenoxid,

BuO

Butylenoxid,

x

ganze oder gebrochene Zahl von 0 bis 130, bevorzugt 0 bis 40

y

ganze oder gebrochene Zahl von 0 bis 130, bevorzugt 1 bis 35 und

z

ganze oder gebrochene Zahl von 0 bis 130, bevorzugt 0 bis 40,

wobei 1 ≤ x+y+z ≤ 130, bevorzugt 10 ≤ x+y+z ≤ 130 gilt, bedeuten.In a preferred embodiment, the at least one polymeric compound is at least one functionalized copolymer of ethylene oxide, propylene oxide and / or butylene oxide, particularly preferably a compound of the general formula (VI)

F - [(EO) _x - (PO) _y - (BuO) _z ] -B (VI)

wherein

F

functional group that binds selectively to the at least one magnetic particle,

B

Alkyl radical with 1 to 6 carbon atoms,

EO

Ethylene oxide,

PO

Propylene oxide,

BuO

Butylene oxide,

x

integer or fractional number from 0 to 130, preferably 0 to 40

y

integer or fractional number from 0 to 130, preferably 1 to 35 and

e.g.

integer or fractional number from 0 to 130, preferably 0 to 40,

where 1 ≤ x + y + z ≤ 130, preferably 10 ≤ x + y + z ≤ 130.

In the compound of the general formula (VI), F denotes a functional group which binds selectively to the at least one magnetic particle. The choice of this functional group depends on the at least one magnetic particle to which the functional group is to bind. A bond which is stable to dissociation should preferably be formed between the at least one magnetic particle and the at least one polymeric compound of the general formula (VI).

und Mischungen davon, besonders bevorzugt eine gegebenenfalls zumindest teilweise veresterte Phosphonsäuregruppe (Va) oder eine gegebenenfalls zumindest teilweise veresterte Phosphorsäuregruppe (Vb).In a preferred embodiment, F is selected from the group consisting of carboxylic acid group -CO ₂ H, optionally at least partially esterified phosphonic acid group -PO ₃ R ' ₂ with R' equal to hydrogen or C ₁ -C ₆ alkyl (Va), optionally at least partially esterified Phosphoric acid group -O-PO ₃ R " ₂ where R" is hydrogen or C ₁ -C ₆ alkyl (Vb), hydroxamate group (Vc), xanthate group (Vd)

and mixtures thereof, particularly preferably an optionally at least partially esterified phosphonic acid group (Va) or an optionally at least partially esterified phosphoric acid group (Vb).

The functional groups Va to Vd are preferably bound to the polymer via free electron pairs.

In the general formula (VI), B denotes an alkyl radical having 1 to 6 carbon atoms, for example methyl, ethyl, propyl, butyl, for example n-butyl, pentyl, hexyl.

The polymeric compounds of the general formula (VI) have an LCST which generally depends in each case on the amount of the individual alkylene oxides, ie. H. Ethylene oxide, propylene oxide and / or butylene oxide, is dependent in the polymer. A polymeric compound that is composed exclusively of propylene oxide has, for example, an LCST of <-10 ° C. A polymeric compound that is made up exclusively of ethylene oxide has, for example, an LCST of> 120 ° C. By choosing the type and amount of the alkylene oxides, an LCST of the polymeric compound can be set which is suitable for the process according to the invention.

In a preferred embodiment, the LCST of the polymeric compound used in the process according to the invention is -10 to 100 ° C., particularly preferably 5 to 45 ° C., very particularly preferably 20 to 40 ° C. In general, the LCST of a polymeric compound is in a temperature range of approx. 5 to 15 ° C. The width of this range is generally dependent on the uniformity, ie the monodispersity, of the polymeric compound used. The higher the monodispersity, the narrower the range of the LCST.

Processes for the preparation of polymeric compounds of the general formula (VI) are known to the person skilled in the art.

The functionalization of the magnetic particles with the at least one polymeric compound can be carried out by all methods known to the person skilled in the art. In a preferred embodiment, the magnetic particles are functionalized with the at least one polymeric compound by first producing the magnetic particles themselves using known processes. These magnetic particles are then modified by contacting a solution of the functionalized polymeric compound, in particular compounds of the general formula (VI), in water or in an organic solvent, for example low molecular weight alcohols or ketones, and the product obtained is used to remove excess polymer Washed compound with an appropriate solvent.

The contacting in embodiment B3 of step (B) is preferably carried out at a temperature at which the polymeric compound used has a hydrophobic character, so that the switchable functionalized magnetic particles and the hydrophobized at least one first substance agglomerate. Depending on the polymeric compound, this temperature can be above or below the LCST, preferably the temperature is above the LCST.

The contacting in embodiment B3 of step (B) is preferably carried out at a temperature which is greater than the LCST of the polymeric compound and less than the boiling point of the suspending agent used, particularly preferably at a temperature which is 1 to 20 ° C. above the LCST lies. Thus, in a preferred embodiment, the contacting according to embodiment B3 is carried out at a temperature of 6 to 65 ° C., particularly preferably 21 to 60 ° C.

In the event that the polymeric compound has a hydrophobic character below the LCST, the contacting is carried out in embodiment B3 at a temperature which is above the melting temperature of the suspending agent used and below the LCST of the polymeric compound. In this case, the contacting in embodiment B3 is preferably carried out at a temperature which is 1 to 20 ° C. below the LCST. In this case, the contacting in embodiment B3 is therefore preferably carried out at a temperature of -15 to 44 ° C., particularly preferably 0 to 39 ° C.

Embodiment B4:

In this further preferred embodiment B4, step (B) of the process according to the invention is carried out by producing a dispersion of the mixture comprising at least a first substance and at least a second substance and the magnetic particles in a suitable dispersant, and adjusting the pH of the dispersion obtained to Value at which the at least one first substance and the magnetic particles carry opposite surface charges so that they agglomerate.

All magnetic particles known to the person skilled in the art which meet the requirements of embodiment B4 of step (B) of the process according to the invention can be used as magnetic particles, for example dispersibility in the dispersant used and ability to agglomerate with the at least one first substance. Furthermore, the magnetic particles should have a defined coating with surface charges at a defined pH. These surface charges can be quantified with the so-called ξ potential. The above-mentioned magnetic particles are preferably used.

In a preferred embodiment of the method according to the invention, the dispersion prepared according to embodiment B4 from step (B) contains at least one buffer system. Suitable buffer systems for setting a specific pH are known to the person skilled in the art and are commercially available. For example, the carbonic acid-silicate buffer is suitable for a weakly acidic pH range (pH = 5.0-6.2). A similar pH range (pH = 5.2-6.7) can be set using 2- (N-morpholino) ethanesulfonic acid. The ammonia buffer is suitable for a pH value in the alkaline range (pH = 8.2-10.2). The addition of a buffer system to the suspension serves to set a suitable pH that is relatively stable.

The dispersion produced according to embodiment B4 of step (B) of the process according to the invention preferably has a pH of 2 to 13. The pH of the dispersion produced depends on the isoelectric points of the substances to be separated. The limits of the pH range are also determined by the stability of the magnetic particles used, for example Fe ₃ O _{4 is} not stable below pH 2.88.

According to the invention, the pH of the dispersion obtained is adjusted to a value at which the at least one first substance and the magnetic particles carry opposite surface charges, so that they agglomerate.

The agglomeration of the at least one first substance and the magnetic particles is based on their different surface charge in aqueous suspension as a function of the pH.

The surface charge of a particle in equilibrium with the surrounding liquid phase is determined by the zeta potential ξ. This varies depending on the pH of the solution or suspension. At the isoelectric point (IEP) the surface charge of the particle changes sign, i.e. the zeta potential ξ to be measured is exactly at the isoelectric point. If the zeta potential ξ on the y axis is plotted against the pH value on the x axis in a coordinate system, the resulting curve at the isoelectric point intersects the x axis.

Particles with different surface charges agglomerate with each other, while charged particles repel each other.

In the dispersion prepared according to embodiment B4 of step (B), there are at least a first substance, at least a second substance and magnetic particles with the isoelectric points IEP (1), IEP (2) and IEP (M), where IEP (1) ≤ IEP (M) ≤ IEP (2) applies. The following relationship holds IEP (1) ≤ pH ≤ IEP (M), i.e. the pH of the suspension lies between the isoelectric points of the at least one first substance and the magnetic particles, the at least one first substance and the magnetic particles have opposite surface charges, while the at least one second substance and the magnetic particles have the same surface charge , so that the at least one first substance and the magnetic particles agglomerate. The reverse is the case if the pH lies between the isoelectric point of the magnetic particles and the at least one second substance, i. H. IEP (M) ≤ pH ≤ IEP (2), so that the magnetic particles and the at least one second substance agglomerate, while the magnetic particles and the at least one first substance repel each other due to the same surface charge.

The isoelectric point of the substances present in the mixture, comprising at least a first substance, at least a second substance and magnetic particles, can be determined via the ξ potential of the individual substances in aqueous solution. The measured ξ potential varies with the device type used, the measurement method and the evaluation method. Important parameters to be specified are temperature, pH value, concentration of the salt background solution, conductivity and measuring voltage, so that the parameters mentioned must be known for comparable measurements.

Further details on this and exemplary isoelectric points of various preferred metal oxides and sulfides are in WO 2009/065802 A2 disclosed, the content of which is expressly referred to.

In preferred embodiment B4 of step (B) of the method according to the invention, the pH is therefore preferably set to a value which lies between the isoelectric point of the at least one first substance and the isoelectric point of the magnetic particles.

The pH can be adjusted by all methods known to the person skilled in the art, for example adding at least one basic or at least one acidic compound to the dispersion obtained. Whether a basic or an acidic compound has to be added depends on the pH value of the dispersion produced. If the pH of this dispersion is less than the range between the isoelectric point of the at least one first substance and the isoelectric point of the magnetic particles, at least one base is added to increase the pH. If the pH of this dispersion is greater than the range between the isoelectric point of the at least one first substance and the isoelectric point of the magnetic particles, at least one acid is added to lower the pH.

Suitable basic compounds are selected from the group consisting of organic or inorganic bases, for example ammonia, sodium hydroxide solution NaOH, potassium hydroxide solution KOH, amines, for example triethylamine, soluble alkali metal carbonates and mixtures thereof.

Suitable acidic compounds are selected from the group consisting of organic or inorganic acids, for example mineral acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, organic acids such as formic acid, acetic acid, propionic acid, methanesulfonic acid and mixtures thereof.

For example, the pH value for separating Cu ₂ S from SiO _{2 is} preferably adjusted to pH 3. To separate MoS ₂ from SiO ₂ , the pH is preferably set to> 2.

Embodiment B5:

F¹

funktionelle Gruppe, die selektiv an den wenigstens einen Magnetpartikel bindet,

F²

funktionelle Gruppe, die selektiv an den wenigstens einen ersten Stoff bindet,

A

Struktureinheit ausgewählt aus CRH₂-Gruppe mit R ausgewählt aus Wasserstoff oder linearem oder verzweigtem Kohlenstoffrest mit 1 bis 30 Kohlenstoffatomen, aromatischer oder heteroaromatischer Einheit, cyclischer oder heterocyclischer Einheit, ungesättigter, verzweigter oder unverzweigter Kohlenstoffkette mit 2 bis 30 Kohlenstoffatomen, Heteroatom oder Kombinationen der vorgenannten Struktureinheiten,

n

ganze Zahl von 1 bis 100,

x

ganze Zahl von 1 bis 4 und

y

ganze Zahl von 1 bis 4 bedeuten,

oder einem Addukt von beiden mit der Mischung enthaltend den wenigstens einen ersten Stoff und wenigstens einen zweiten Stoff in Kontakt gebracht, so dass sich aus den magnetischen Partikeln, der bifunktionellen Verbindung der allgemeinen Formel (VII), und dem wenigstens einen ersten Stoff ein Addukt bildet.In this further preferred embodiment B5 of step (B) of the process according to the invention, the magnetic particles together with at least one bifunctional molecule of the general formula (VII)

(F ¹ ) _x - (A) _n - (F ² ) _y (VII),

wherein

F ¹

functional group that binds selectively to the at least one magnetic particle,

F ²

functional group that binds selectively to the at least one first substance,

A

Structural unit selected from CRH ₂ group with R selected from hydrogen or linear or branched carbon radical with 1 to 30 carbon atoms, aromatic or heteroaromatic unit, cyclic or heterocyclic unit, unsaturated, branched or unbranched carbon chain with 2 to 30 carbon atoms, hetero atom or combinations of the aforementioned Structural units,

n

integer from 1 to 100,

x

integer from 1 to 4 and

y

are integers from 1 to 4,

or an adduct of both is brought into contact with the mixture comprising the at least one first substance and at least one second substance, so that an adduct is formed from the magnetic particles, the bifunctional compound of the general formula (VII), and the at least one first substance .

F ¹ and F ² each represent functional groups which bind selectively to the magnetic particles (F ¹ ) or to the at least one first substance (F ² ).

In the context of the present invention, “selective” means that the corresponding functional group F ¹ or F ² is 50 to 95%, preferably 70 to 98%, particularly preferably 80 to 98%, based on F ¹ , of the magnetic particles or , based on F ² , bind to the at least one first substance, in each case in the presence of the at least one second substance, in each case based on all bonds between functional groups and components present in the mixture.

In a preferred embodiment, F ¹ denotes a functional group which binds selectively to the magnetic particles in the presence of silicates, particularly preferably selected from phosphonic acid group -OP (OH) ₂ or carboxylic acid group-COOH.

worin

Y

unabhängig von einander S, NH, O, bevorzugt unabhängig von einander S oder O,

X

N, P, CH₂, bevorzugt N,

a, b, c, d

unabhängig von einander ganze Zahl von 1 bis 6, bevorzugt 1 oder 2, bedeuten.

In a further preferred embodiment, F ² denotes a functional group which binds to the at least one first substance in the presence of oxidic ores, for example the abovementioned ones, in particular SiO ₂ or albite, particularly preferably selected from the group consisting of the group consisting of thiol group -SH, hydroxyl group -OH, xanthate -OCSSH, thiolate -S ^- , dihydroxy group, for example 1,2-dihydroxy or 1,3-dihydroxy group, a dithiol group, for example 1,2-dithiol or 1 , 3-dithiol group, a thiohydroxy group, for example 1,2-thiohydroxy or 1,3-thiohydroxy group, functional groups of the general formula (VIII) and mixtures thereof.

wherein

Y

independently of one another S, NH, O, preferably independently of one another S or O,

X

N, P, CH ₂ , preferably N,

a, b, c, d

independently of one another are integers from 1 to 6, preferably 1 or 2.

Functional groups F ^{2 of} the general formula (VIII) are bound to - (A) _n - via the free bond to X.

Very particularly preferred functional groups F ^{2 of} the general formula (VIII) are selected from the group of the compounds of the formulas (VIIIa), (VIIIb), (VIIIc), (VIIId) and (VIII):

In the general formula (VII) A denotes structural unit selected from CRH ₂ group with R selected from hydrogen or linear or branched carbon radical having 1 to 30 carbon atoms, aromatic or heteroaromatic unit, Cyclic or heterocyclic unit, unsaturated, branched or unbranched carbon chain with 2 to 30 carbon atoms, hetero atom or combinations of the aforementioned structural units, preferably CH ₂ group, it being also possible according to the invention that in the basic structure formed by - (A) _n - the bifunctional compounds -CC double and / or triple bonds are present. Heteroatoms are, for example, O, S, N, and / or P. Suitable aromatic or heteroaromatic units are selected, for example, from substituted or unsubstituted aromatic or heteroaromatic units having 6 to 20 carbon and optionally heteroatoms, for example phenyl, benzyl and / or naphthyl. The aromatic units can be linked into the chain via the 1,2, 1,3 and / or 1,4 positions.

In the compound of the general formula (VII), x and y describe the number of functional groups F ¹ or F ² present in the molecule. X and y are preferably independently of one another 1, 2 or 3, particularly preferably 1 or 2, very particularly preferably 1.

A very particularly preferred compound of the general formula (VII) is (2-mercapto-phenyl) phosphonic acid

In a preferred embodiment of the process according to the invention, the functional group F ¹ in the compound of the general formula (VII) binds to the at least one magnetic particle and the functional group F ² in the compound of the general formula (VII) to the at least one first substance.

After step (B) of the process according to the invention, in particular after carrying out the preferred embodiments B1, B2, B3, B4 or B5, the dispersion contains agglomerates of magnetic particles and the at least one first substance, the at least one second substance and optionally at least a third substance in front. According to the invention, this dispersion is preferably transferred directly to step (D).

Step (C):

Step (C) of the process according to the invention comprises separating the addition product from the mixture from step (B) by applying a magnetic field gradient.

Suitable devices for magnetic separation in step (C), preferably on an industrial scale, are known to the person skilled in the art.

Step (C) of the method according to the invention can be carried out in all suitable devices known to the person skilled in the art, for example in a wet drum separator, high-gradient magnetic separator or related devices.

Step (C) of the process according to the invention can be carried out at any suitable temperature, for example 10 to 60 ° C.

In step (C) the addition product from step (B) can, if appropriate, be separated off by all processes known to the person skilled in the art.

Step (D):

Step (D) of the method according to the invention comprises cleaving the separated addition product from step (C) in order to obtain the at least one first substance and the magnetic particles separately.

The cleavage method used in step (D) of the process according to the invention depends on the method by which the agglomerates were formed in step (B).

The splitting can be carried out by methods which are suitable for splitting the adduct in such a way that the magnetic particles can be recovered in a reusable form. In a preferred embodiment, the magnetic particles, particularly preferably together with magnetic particles separated in step (A), are used again in step (B).

In a preferred embodiment, the splitting in step (E) of the process according to the invention is carried out by treating the adduct with a substance selected from the group consisting of organic solvents, basic compounds, acidic compounds, oxidizing agents, reducing agents, surface-active compounds and mixtures thereof.

Examples of suitable organic solvents are methanol, ethanol, propanol, for example n-propanol or iso-propanol, aromatic solvents, for example benzene, toluene, xylenes, ethers, for example diethyl ether, methyl t-butyl ether, ketones, for example acetone, aromatic or aliphatic hydrocarbons, for example saturated hydrocarbons with, for example, 8 to 16 carbon atoms, for example dodecane and / or Shellsol®, diesel fuels and mixtures thereof. The main components of diesel fuel are mainly alkanes, cycloalkanes and aromatic hydrocarbons with about 9 to 22 carbon atoms per molecule and a boiling range between 170 ° C and 390 ° C.

Examples of basic compounds which can be used according to the invention are aqueous solutions of basic compounds, for example aqueous solutions of alkali and / or alkaline earth metal hydroxides, for example KOH, NaOH, lime milk, aqueous ammonia solutions, aqueous solutions of organic amines of the general formula R ² ₃ N, where R ^{2 is} independent of one another is selected from the group consisting of C ₁ -C ₈ alkyl, optionally substituted with further functional groups. In a preferred embodiment, step (E) is carried out by adding aqueous NaOH solution up to a pH of 13, for example for the removal of Cu ₂ S modified with OPS. The acidic compounds can be mineral acids, for example HCl, H ₂ SO ₄ , HNO ₃ or mixtures thereof, organic acids, for example carboxylic acids. H ₂ O ₂ , for example, can be used as the oxidizing agent, for example as a 30% by weight aqueous solution (perhydrol). H ₂ O ₂ or Na ₂ S ₂ O ₄ is preferably used for the removal of Cu ₂ S modified with thiols.

Examples of surface-active compounds which can be used according to the invention are nonionic, anionic, cationic and / or zwitterionic surfactants.

In a preferred embodiment, the adduct of hydrophobic substance and magnetic particles is cleaved with an organic solvent, particularly preferably with acetone and / or diesel. This process can also be supported mechanically. In a preferred embodiment, ultrasound is used to support the cleavage process.

In general, the organic solvent is used in an amount sufficient to cleave as much as possible the entire adduct. In a preferred embodiment, 20 to 100 ml of the organic solvent are used per gram of adduct of hydrophobic material and magnetic particles to be cleaved.

In embodiment B3 of step (B) of the process according to the invention, in which agglomerate formation takes place by means of polymeric compounds which have an LCST ( Lower Critical Solution Temperature ), the separation of the agglomerates in step (E) can be carried out by setting a temperature is, in which the polymeric compounds has no hydrophobic character, so that the agglomerates are split.

In embodiment B4 of step (B) of the process according to the invention, in which the formation of agglomerates takes place by adjusting the pH of the dispersion obtained to a value at which the at least one first substance and the magnetic particles carry opposite surface charges, the separation of the Agglomerates occur by setting a pH value at which the at least one first substance and the magnetic particles have the same surface charges, so that the agglomerates are split.

According to the invention, after the cleavage in step (D), the at least one first substance and the magnetic particles are present as a dispersion either in said cleavage reagent, preferably an organic solvent, and / or in water.

In a preferred embodiment, the method according to the invention additionally has the following step (E):
(E) separating the magnetic particles from the mixture from step (D) to obtain the at least one first substance.

The magnetic particles can be separated from the solution comprising these magnetic particles and the at least one first substance by means of a permanent or switchable magnet. In a preferred embodiment, the separation in the optional step (E) is carried out analogously to step (C) of the method according to the invention. Individual process parameters, for example solids content, flow rate, can be changed accordingly in step (E).

After the magnetic particles have been separated off, the desired at least one first substance is present in a dispersion optionally containing a cleavage reagent and / or water.

The first substance to be separated, preferably the metal compound to be separated, is preferably separated from the cleavage reagent, for example an organic solvent, for example by distillation.

The first substance obtainable in this way can be purified by further processes known to the person skilled in the art. The solvent can, if appropriate after purification, be returned to the process according to the invention. If after the magnetic particles have been separated off there is a dispersion of the at least one first substance in water, the water can likewise be removed by processes known to the person skilled in the art, for example distillation, filtration, decanting and / or centrifuging.

In steps (A), (B), (C) (D) and / or optionally (E) according to the invention, further dispersing agent can optionally be added to the present dispersion. According to the invention, further dispersing agents can be added in order to obtain dispersions with lower solids contents in the individual steps.

Suitable dispersants to be added are all dispersants which have already been mentioned with regard to step (A), in particular water.

According to the invention, the optional addition of dispersing agents can be carried out by all processes known to the person skilled in the art.

Claims (10)

1. A process for separating at least one first material which is a hydrophobic metal compound or coal from a mixture comprising this at least one first material, at least one second material which is a hydrophilic metal compound and magnetic particles, which comprises the following steps:

   (A) at least partial removal of the magnetic particles by application of a magnetic field gradient, optionally in the presence of at least one dispersing medium, to give a mixture comprising at least one first material and at least one second material and a reduced amount of magnetic particles, where the magnetic particles which have been separated off in step (A) are used in step (B) and magnetic particles separated off in step (A) are hydrophobicized on the surface by means of at least one surface-active substance before use in step (B),

   (B) contacting of the mixture comprising at least one first material and at least one second material from step (A) with the magnetic particles obtained in step (A) and optionally further magnetic particles which have been hydrophobicized on the surface by means of at least one surface-active substance so that the at least one first material and the magnetic particles agglomerate, where the agglomeration is effected by forces of attraction between the at least one first material and the magnetic particles,

   (C) separation of the agglomeration product from the mixture from step (B) by application of a magnetic field gradient and

   (D) dissociation of the agglomeration product separated off in step (C) in order to obtain the at least one first material and the magnetic particles separately.
2. The process according to claim 1, wherein the at least one hydrophobic metal compound is selected from the group consisting of sulfidic minerals and oxidic and/or carbonate-comprising minerals.
3. The process according to claim 1, wherein the at least one hydrophilic metal compound is selected from the group consisting of oxidic and hydroxidic metal compounds.
4. The process according to any of claims 1 to 3, wherein magnetic particles selected from the group consisting of magnetic metals, for example iron, cobalt, nickel and mixtures thereof, ferromagnetic alloys of magnetic metals, magnetic iron oxides, for example magnetite, maghemite, pyrrhotin, ilmenite, further ferromagnetic minerals of the FeO-Fe₂O₃-TiO₂ system, cubic ferrites of the general formula (I)
   
           M²⁺ _xFe²⁺ _1-xFe³⁺ ₂O₄     (I)
   
   where

   M is selected from among Co, Ni, Mn, Zn and mixtures thereof and

   x ≤ 1,

   hexagonal ferrites, for example barium ferrite or strontium ferrite MFe₁₂O₁₉ where M = Mg, Ca, Sr, Ba and mixtures thereof
   are used in step (B) of the process of the invention.
5. The process according to any of claims 1 to 4, wherein the magnetic particles obtained in step (A) are comminuted to an average size from 100 nm to 20 µm before use in step (B).
6. The process according to any of claims 1 to 5, wherein the magnetic particles are separated off in step (A) to an extent of at least 50%.
7. The process according to any of claims 1 to 6, wherein the dispersion medium is water.
8. The process according to any of claims 1 to 7 additionally having the following step (E):
   (E) separation of the magnetic particles from the mixture from step (D) in order to obtain the at least one first material.
9. The process according to any of claims 1 to 8, wherein the at least one first material and the magnetic particles agglomerate in step (B) as a result of hydrophobic interactions, different surface charges and/or compounds present in the mixture which selectively couple the at least one material and the magnetic particles.
10. The process according to any of claims 1 to 9, wherein the mixture comprising at least one first material and at least one second material is milled to particles having an average size of from 100 nm to 100 µm before or during step (B).