EA047029B1 - PROCESSING AND PURIFICATION OF CARBONIC MATERIALS - Google Patents

Description

The present invention relates to a method for treating and/or purifying carbonaceous solids and to the use of nitrogen hydride as a dispersing agent to obtain and/or stabilize an aqueous suspension.

Carbon-rich materials such as carbon black, activated carbon, some pyrolysis products, graphite electrodes and many other graphite-based materials are of great industrial importance.

An important carbon-rich material is, for example, industrial carbon black, also known as carbon black. Unlike conventional soot, carbon black is produced by targeted pyrolysis of carbonaceous materials. These special manufacturing processes allow the synthesis of carbon black particles in the nanometer range, the primary particle size and surface structure of which can be tailored to the respective application areas. Annual production of carbon black was about 8 million tons in 1996 and is estimated to increase to more than 15 million tons by 2022. Carbon black is used primarily as an additive in many rubber products (rubber compound black) and as a colorant in plastics, paints, coatings and inks (black pigment). With nearly 85% of the world's annual production, most of its use is in the tire industry. The production of new carbon black (primary carbon black) requires significant amounts of raw materials and energy, and also generates significant amounts of carbon dioxide. At the same time, the European Union, for example, produces about 3.2 million tons of waste tires per year, and the United States of America even produces 4.4 million tons of waste tires per year. Efforts have already been made to recycle carbon black from old materials such as waste tires. Typically known recycling processes are based on pyrolysis of waste followed by recycling of the resulting pyrolysis residue. However, the carbon black thus produced (recovered carbon black) has a carbon content of only approximately 80% of that of newly produced carbon black, and is not an adequate alternative. In particular, the recovered carbon black often contains a high proportion of ash, which typically consists of zinc sulfide, zinc oxide, silica and/or alumina. This high ash content limits possible applications and thus reduces the value of the processed product. When reused in tire production, the ash components in the recovered carbon black cause, for example, a decrease in the strength and durability of the rubber. When used as a colorant for plastics, paints, varnishes or inks, the lower color intensity or blackness of the recovered carbon black is a limitation.

For example, a method for removing ash from waste tires is known from US patent application US 20150307714 A1. Chinese patent application CN 109266376 relates to a method for recycling and dissolving waste tires using peroxides and organic solvents at elevated temperature and pressure. Chinese patent application CN108384287 also relates to a method for recycling and dissolving waste tires. US patent application US 2018320082 A1 relates to a method for recycling waste tires using microwave radiation. From the international patent application WO 2013/175488 A2, a method for producing carbon black with a low sulfur content is known.

One of the disadvantages of the known methods is, for example, the use of high concentrations of acid or organic solvents, which are problematic from a health, environmental or handling point of view. In addition, prior art methods often have long extraction times and/or only recover structurally and morphologically modified low quality carbon black.

It is desirable to develop a new method for processing and purifying carbonaceous materials that does not have pre-existing disadvantages. There is a need for a method for efficiently processing and purifying carbonaceous materials, especially carbon black. There is also a need for a method for treating and purifying carbonaceous materials, especially carbon black, that does not require high concentrations of acid or organic solvents. There is also a need for a method for processing and purifying carbonaceous materials, especially carbon black, that does not require long extraction times and/or allows recovery of substantially intact structurally and morphologically carbon-rich materials, especially carbon black. In addition, a method of processing and purifying carbonaceous materials, especially carbon black, that provides a product of high purity and/or low ash content is required. In particular, there is a need for a process for recovering and purifying carbon black from waste tires that provides recovered carbon black that is similar, or ideally of the same quality, as newly produced carbon black, and in particular has a low ash content and/or or sulfur content and substantially unchanged physical properties compared to the carbon black originally used.

It is therefore an object of the present invention to provide a method for treating and purifying carbonaceous materials that does not have the pre-existing disadvantages. Another goal is

- 1 047029 is the creation of a method for effective processing and purification of carbonaceous materials, especially carbon black. Another goal is to provide a method for treating and purifying carbonaceous materials, particularly carbon black, that does not require the use of high concentrations of acid or organic solvents. Another object is to provide a method for processing and purifying carbonaceous materials, especially carbon black, that does not require long extraction times and/or allows recovery of carbon black that is substantially structurally and morphologically intact. Another object is to provide a method for processing and purifying carbonaceous materials, especially carbon black, that provides a product of high purity and/or low ash content. In particular, one object of the present invention is to provide a method for recovering and purifying carbon black from waste tires that provides recovered carbon black that is of similar or, ideally, the same quality as newly produced carbon black, and in particular has low ash and/or sulfur content, and substantially unchanged physical properties compared to the carbon black originally used.

One or more of the above objects is achieved by the method of treating and/or purifying carbonaceous solids according to the present invention. The method for treating and/or purifying carbonaceous solids according to the invention includes the steps of:

a) providing a mixture containing a carbonaceous solid and at least one inorganic compound;

b) providing an aqueous fluid containing nitrogen hydride;

c) providing an alkali metal hydroxide and/or an alkali metal;

d) bringing into contact the mixture of step (a), the fluid of step (b) and the alkali metal hydroxide and/or alkali metal of step (c).

e) subjecting the composition obtained in step (d) to reduced or increased temperature and/or reduced or increased pressure.

e) separating the carbonaceous solid from the composition obtained in step (e).

Surprisingly, it has been discovered that the method of the present invention can be used to selectively remove inorganic compounds, such as minerals and/or salts, from a carbon-rich solid mixture or suspension thereof. In addition, it has been found that the physical properties of the carbon present in the starting mixture are not altered or significantly altered by the process of the present invention. Thus, the method according to the invention makes it possible to obtain a solid with a very high carbon content and high functionality for further processing or use at a later stage.

Stage (a).

In step (a) of the method of the present invention, a mixture is provided which includes a carbonaceous solid and at least one inorganic compound.

For the purposes of this invention, an inorganic compound is a compound that does not contain carbon-hydrogen bonds and preferably does not contain carbon.

For purposes of the present invention, a carbonaceous solid is defined as a carbonaceous material that is poorly soluble in water, preferably very poorly soluble in water, and more preferably insoluble in water. As used herein, the term poorly soluble in water refers to a material that dissolves to 1-10 g/L (H2O) at 25°C. As used herein, the term very poorly soluble in water refers to a material that dissolves to 0.1-1 g/l (H2O) at 25°C, and insoluble in water as used herein refers to a material that dissolves to less than 0.1 g/l (H2O) at 25°C (for example, from 0.0001 to 0.1 g/l (H2O)).

The carbonaceous solid may be at least 80% (e.g., 80.0 to 99.8%), preferably at least 90%, more preferably at least 95% (e.g., 95.0 to 99) .8%) from carbon. In one embodiment of the present invention, the carbonaceous solid is present in the crystalline form of graphite.

Particularly preferably, the carbonaceous solid contains or consists of carbon black. For example, the carbonaceous solid may be at least 90%, preferably at least 95%, carbon black. The primary carbon black particles may have a diameter of from 1 to 600 nm, preferably from 10 to 300 nm. The grain diameter of the primary particles can be measured by laser diffraction. Primary carbon black particles can combine to form carbon black aggregates, which can have a diameter of 80 to 800 nm. These carbon black aggregates, in turn, can form superstructures in the form of carbon black agglomerates. In addition, carbon black may have a specific surface area of 5 to 1500 m ² /g, preferably 15 to 600 m ² /g, measured according to the BET method. In one embodiment of the present invention, the carbonaceous solid of step (a) consists of carbon black having an elemental composition of 90.0 to 99.7% C, 0.1 to 0.6% H, 0.01 to 0. 8% S and 0.2 to 3.5% O.

The at least one inorganic compound is preferably two or

- 2 047029 more inorganic compounds. The at least one inorganic compound may be a mineral and/or a salt, and is preferably a mixture of minerals and/or salts. In one embodiment of the present invention, the at least one inorganic compound is selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof. For example, the at least one inorganic compound may contain or consist of zinc sulfide, zinc oxide, silica, silicates, alumina, or mixtures thereof.

The at least one inorganic compound may be poorly soluble in water, preferably very poorly soluble in water, and most preferably insoluble in water. The above definitions of the expressions sparingly soluble in water, very sparingly soluble in water and insoluble in water apply.

The at least one inorganic compound is preferably an inorganic compound selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof, wherein the at least one inorganic compound is at least sparingly soluble in water, more preferably at least very sparingly soluble in water and most preferably insoluble in water.

The mixture may be in the form of a solid mixture or a suspension. In one embodiment, the mixture is present in the form of a suspension, preferably an aqueous suspension. In another embodiment, the mixture is present in the form of a solid mixture.

According to one embodiment of the present invention, the mixture of step (a) contains a carbonaceous solid with a mole fraction of more than 50% (for example, from 50 to 99%), preferably more than 70%, and more preferably more than 80% (for example, from 80 to 95%), based on the total molar amount of the mixture, and/or the mixture of step (a) includes at least one inorganic compound with a molar fraction of from 1 to 30%, preferably from 5 to 20% of the total molar amount of the mixture.

According to one embodiment of the present invention, the mixture of step (a) contains a carbonaceous solid with a mole fraction of more than 50% (for example, from 50 to 99%), preferably more than 70%, and more preferably more than 80% (for example, from 80 to 95%), based on the total molar amount of the mixture, and at least one inorganic compound with a molar fraction of from 1 to 30%, preferably from 5 to 20% of the total molar amount of the mixture.

In another embodiment of the present invention, the mixture of step (a) contains carbonaceous solids in an amount of more than 50 wt.% (for example, from 50 to 99%), preferably more than 70 wt.%, and more preferably more than 80 wt.% (for example, from 80 up to 95%), based on the total weight of the mixture, and/or the mixture of step (a) includes at least one inorganic compound in an amount of from 1 to 30 wt.%, preferably from 5 to 20 wt.% of the total weight of the mixture.

In one embodiment of the present invention, the mixture of step (a) contains a carbonaceous solid in an amount of from 70 to 99% by weight, and more preferably from 80 to 98% by weight, based on the total weight of the carbonaceous solid and at least one inorganic compound, and /or the mixture of step (a) includes at least one inorganic compound in an amount of from 1 to 30 wt.%, preferably from 2 to 20 wt.%, based on the total weight of the carbonaceous solid and at least one inorganic compound.

In one embodiment of the present invention, the mixture of step (a) contains a carbonaceous solid in an amount of from 70 to 99% by weight, and more preferably from 80 to 98% by weight, based on the total weight of the carbonaceous solid and at least one inorganic compound, and at least one inorganic compound in an amount of from 1 to 30% by weight, preferably from 2 to 20% by weight, based on the total weight of the carbonaceous solid and the at least one inorganic compound.

The weight percentage of carbonaceous solids in the mixture of step (a) and/or at least one inorganic compound in the mixture of step (a) can be determined in accordance with the standard method ASTM D150615; Standard Test Methods for Carbon Black Ash Content.

In one embodiment of the present invention, the mixture of step (a) is obtained by pyrolysis of carbonaceous material. Preferably, the mixture of step (a) is obtained by pyrolysis of waste tires or biomass, preferably waste tires. Thus, according to a preferred embodiment, the mixture of step (a) is obtained by pyrolysis of waste tires. According to another embodiment, the mixture of step (a) is obtained by pyrolysis of biomass.

According to another preferred embodiment, the mixture of step (a) is obtained from the pyrolysis of waste tires, and it contains a carbonaceous solid and at least one inorganic compound, where the carbonaceous solid comprises carbon black and the at least one inorganic compound is an inorganic compound selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof.

According to another preferred embodiment, the mixture of step (a) is obtained by pyrolysis of otra

- 3 047029 tires, and it contains a carbonaceous solid and at least one inorganic compound, where the carbonaceous solid includes carbon black and the at least one inorganic compound is an inorganic compound selected from the group consisting of one or more sulfides metals, one or more metal oxides, one or more silicates, and mixtures thereof, and at least one inorganic compound is at least sparingly soluble in water, more preferably at least very sparingly soluble in water, and more preferably insoluble in water.

According to another preferred embodiment, the mixture of step (a) is obtained from the pyrolysis of waste tires and includes a carbonaceous solid and at least one inorganic compound, wherein the carbonaceous solid consists of more than 90% carbon (for example, from 90 to 99.8% carbon). ), and the at least one inorganic compound is an inorganic compound selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof, and the mixture includes a carbonaceous solid with a mole fraction more than 70% and at least one inorganic compound with a mole fraction of from 5 to 20%, based on the total molar amount of the mixture.

According to another preferred embodiment, the mixture of step (a) is obtained from the pyrolysis of waste tires, and it comprises a carbonaceous solid and at least one inorganic compound, wherein the carbonaceous solid consists of more than 90% carbon black (for example, from 90 to 99.8 %), and the at least one inorganic compound is an inorganic compound selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof, where the mixture includes a carbonaceous solid with a molar proportions greater than 70% (for example, from 70 to 95%) and at least one inorganic compound with a mole fraction from 5 to 20%, based on the total molar amount of the mixture.

According to another preferred embodiment, the mixture of step (a) is obtained from the pyrolysis of waste tires, and it contains a carbonaceous solid and at least one inorganic compound, and the carbonaceous solid consists of more than 90% carbon (for example, from 90 to 99.8% ), and the at least one inorganic compound is an inorganic compound selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof, wherein the mixture includes a carbonaceous solid in an amount of more than 70 wt.% (for example, from 70 to 95%) and at least one inorganic compound in an amount of from 5 to 20 wt.% based on the total weight of the mixture.

According to another preferred embodiment, the mixture of step (a) is obtained from the pyrolysis of waste tires, and it contains a carbonaceous solid and at least one inorganic compound, and the carbonaceous solid consists of more than 90% carbon black (for example, from 90 to 99.8 %), and the at least one inorganic compound is an inorganic compound selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof, wherein the mixture includes a carbonaceous solid in the amount more than 70 wt.% (for example, from 70 to 95%) and at least one inorganic compound in an amount of from 5 to 20 wt.%, based on the total weight of the mixture.

Stage (b).

In step (b) of the method of the present invention, an aqueous fluid containing nitrogen hydride is provided. Nitrogen hydride in the context of the present invention is a chemical substance having at least one nitrogen-hydrogen bond. An aqueous fluid in the context of the present invention is an aqueous suspension, emulsion, solution or dispersion, preferably an aqueous solution. An aqueous fluid in the context of the present invention is a water-based fluid that preferably consists of at least 50 wt.% (for example, from 50 to 95 wt.%), more preferably 75 wt.% water, based on total mass of fluid.

Surprisingly, it has been discovered that the use of an aqueous fluid containing nitrogen hydride provides an advantage for the stability of the slurry of carbonaceous feedstock and process reagents. Additionally, it has surprisingly been discovered that use of the fluid described herein results in improved recovery of inorganic compounds from carbonaceous feedstock.

According to one embodiment of the present invention, the fluid of step (b) contains a nitrogen hydride selected from the group consisting of ammonia, inorganic ammonium salts, primary or secondary organic amines and ammonium salts thereof, and mixtures thereof.

Preferably, the fluid comprises a nitrogen hydride selected from the group consisting of ammonia, ammonium hydroxide, ammonium halides, guanidine, guanidine derivatives and ammonium salts thereof, and mixtures thereof. More preferably, the fluid comprises nitrogen hydride(s), ammonia and/or ammonium hydroxide, and most preferably ammonium hydroxide.

In one embodiment, the aqueous fluid contains nitrogen hydride in a concentration of from 0.001 to

- 4 047029

16.5 mol/L, preferably 0.05 to 5 mol/L and more preferably 0.09 to 0.9 mol/L. For example, the aqueous fluid may contain nitrogen hydride at a concentration of 0.05 to 0.25 mol/L.

According to one embodiment of the present invention, the aqueous fluid of step (b) is provided in an amount of from 2 to 200 L (fluid)/1 kg (mixture of step (a)), preferably from 5 to 150 L (fluid)/1 kg (mixture step (a)) and more preferably from up to 100 l (fluid)/1 kg (mixture of step (a)).

According to one embodiment of the present invention, the aqueous fluid of step (b) is provided in an amount of from 2 to 200 L (fluid)/1 kg (mixture of step (a)), preferably from 5 to 150 L (fluid)/1 kg (mixture step (a)), and more preferably from 10 to 100 l (fluid)/1 kg (mixture of step (a)), where the aqueous fluid contains nitrogen hydride in a concentration of from 0.001 to 16.5 mol/l, preferably from 0.05 to 5 mol/L and more preferably 0.09 to 0.9 mol/L.

The fluid of step (b) may contain one or more substances in addition to nitrogen hydride. These substances can be adapted to the nature of the inorganic compounds and/or to the amount of inorganic compounds in the mixture of step (a).

According to one embodiment of the present invention, the fluid contains one or more substances selected from the group consisting of alcohols, oxidizing agents, acids, nitrates and carbonates.

For example, the fluid may contain one or more alcohols. A suitable alcohol is a water-miscible alcohol such as ethanol.

The fluid may also contain one or more oxidizing agents. Suitable oxidizing agents are, for example, ozone, iodates, permanganates, peroxides or dichromates.

The fluid may also contain one or more acids. Suitable acids are, for example, organic acids such as acetic acid and/or oxalic acid, or inorganic acids such as hydrochloric acid, sulfuric acid and/or phosphoric acid. However, in a preferred embodiment, no acid is added to the fluid.

Stage (c).

In step (c) of the method of the present invention, an alkali metal hydroxide and/or an alkali metal is provided.

Preferably, in step (c) an alkali metal hydroxide is provided. The alkali metal hydroxide may be provided as a solid or in the form of a solution or suspension. Preferably, the alkali metal hydroxide is in the form of a solid. In principle, the alkali metal hydroxide can be any known alkali metal hydroxide. However, preferably the alkali metal hydroxide is selected from the group consisting of LiOH, NaOH, KOH or a mixture thereof, more preferably from the group consisting of NaOH, KOH or a mixture thereof. Most preferably, NaOH is used as the alkali metal hydroxide.

In another embodiment, step (c) uses an alkali metal, preferably sodium.

According to one embodiment of the present invention, the alkali metal hydroxide and/or alkali metal in step (c) is provided in a molar ratio to the inorganic compounds of the mixture of step (a) from 0.25:1 to 2:1. preferably from 0.5:1 to 1.5:1, more preferably from 0.75:1 to 1.25:1 and most preferably from 0.95:1 to 1.05:1.

According to one embodiment of the present invention, an alkali metal hydroxide, preferably NaOH, is provided in step (c) in a molar ratio to the inorganic compounds of the mixture of step (a) from 0.25:1 to 2:1, preferably from 0.5:1 to 1, 5:1, more preferably 0.75:1 to 1.25:1, and most preferably 0.95:1 to 1.05:1.

According to one embodiment of the present invention, an alkali metal hydroxide, preferably NaOH, is provided in step (c) in a molar ratio to the silicates present in the mixture of step (a) from 0.25:1 to 2:1, preferably from 0.5:1 to 1.5:1, more preferably from 0.75:1 to 1.25:1 and most preferably from 0.95:1 to 1.05:1.

According to another embodiment, an alkali metal hydroxide, preferably NaOH, is provided in step (c) in a stoichiometric amount relative to the inorganic compounds of the mixture according to step (a). According to another embodiment, an alkali metal hydroxide, preferably NaOH, is provided in step (c) in a stoichiometric amount relative to the silicates present in the mixture according to step (a).

Stage (d).

In step (d) of the method according to the invention, the mixture of step (a), the aqueous fluid of step (b) and the alkali metal hydroxide and/or alkali metal of step (c) are brought into contact.

With regard to possible and preferred embodiments of the mixture according to step (a), the aqueous fluid according to step (b) and the alkali metal hydroxide and/or alkali metal according to step (c), reference is made to the explanations in the previous sections.

The provided substances can be brought into contact in step (d) without active mixing, for example without the use of a mixing device. However, the provided substances can also be mixed in step (d). In a preferred embodiment, step (d) of the present invention

- 5 047029 includes mixing a mixture of step (a), the fluid of step (b) and the alkali metal hydroxide and/or alkali metal of step (c).

The contact of the provided substances can be carried out in any order or simultaneously. In one embodiment, the mixture of step (a) is first contacted with the aqueous fluid of step (b), and then with the alkali metal hydroxide and/or alkali metal of step (c). In another embodiment, the aqueous fluid of step (b) is first contacted with the alkali metal hydroxide and/or alkali metal of step (c), and then with the mixture of step (a). In one embodiment, the mixture of step (a) is simultaneously brought into contact with the aqueous fluid of step (b) and the alkali metal hydroxide and/or alkali metal of step (c).

An advantage can be achieved by first contacting the mixture of step (a) with the aqueous fluid of step (b) and then adding the alkali metal hydroxide and/or the alkali metal of step (c). Thus, according to a preferred embodiment of step (d), first the mixture of step (a) is brought into contact with the aqueous fluid of step (b), and then with the alkali metal hydroxide and/or the alkali metal of step (c). According to a more preferred embodiment of step (d), the mixture of step (a) is first mixed with the aqueous fluid of step (b), and then with the alkali metal hydroxide and/or the alkali metal of step (c).

The provided substances can be brought into contact in one or more reactors. For example, the provided substances can be mixed in a mixing unit. It is also possible to mix the substances one after another in two different mixing units. The corresponding reactors and devices are familiar to the person skilled in the art. According to one embodiment of the present invention, the mixture of step (a) is first mixed with the aqueous fluid of step (b) in the first mixing unit, followed by mixing the resulting composition with the alkali metal hydroxide and/or alkali metal of step (c) in the second mixing unit.

Preferably, the reactor(s) are equipped with a stirring device. In addition, the reactor(s) may be equipped with one or more pumping devices and/or solids addition devices. Such reactors and devices are familiar to those skilled in the art.

It is also possible to bring the provided materials directly into contact in a reactor, which can then also be used under the conditions of step (e). It may be, for example, a high pressure reactor or a hydrothermal reactor.

It may also be advantageous to heat the composition obtained in step (d) to increase the uniformity of the composition obtained in step (d) and/or the solubility of the added solids. Therefore, step (d) involves, according to one embodiment, heating the resulting composition. For example, the resulting composition can be heated to a temperature of from 25 to 100°C.

Stage (e).

In step (e) of the method of the present invention, the composition obtained in step (d) is subjected to reduced or elevated temperature and/or reduced or elevated pressure. The expression reduced or elevated should be understood to refer to a temperature of 20°C and/or a pressure of 1.013 bar (0.1 MPa) as reference points.

Step (e) can be described as a leaching process, i.e. a type of solid-liquid extraction in which the more soluble fraction, i.e. inorganic compounds are completely or partially removed from the insoluble, permeable solid phase in which the carbonaceous solid is present. For such a process, different conditions may be specified depending on the starting materials and reagents used for the process.

According to one embodiment of the present invention, the composition in step (e) is exposed to a temperature of -35 to 400°C, preferably from 25 to 300°C, and more preferably from 80 to 240°C, and/or the composition in step (e) is exposed to pressure from 100 Pa to 20 MPa (0.001 to 200 bar), preferably from 0.1 to 10 MPa (1 to 100 bar) and more preferably from 0.5 to 5 MPa (5 to 50 bar), and/ or the pH of the composition in step (e) is adjusted to a value from 0 to 14, preferably from 7 to 14, and more preferably from 9 to 13.

According to another embodiment of the present invention, the composition in step (e) is subjected to a temperature of -35 to 400°C, preferably 25 to 300°C, and more preferably 80 to 240°C, and a pressure of 100 Pa to 20 MPa (0.001 to 200 bar), preferably from 0.1 to 10 MPa (1 to 100 bar) and more preferably from 0.5 to 5 MPa (5 to 50 bar) and the pH of the composition in step (e) is adjusted to a value from 0 to 14, preferably from 7 to 14 and more preferably from 9 to 13.

According to a preferred embodiment, the composition obtained in step (d) is subjected to elevated temperature and/or pressure. According to a preferred embodiment of the present invention, the composition in step (e) is subjected to a temperature of 50 to 400° C. and a pressure of 0.2 to 20 MPa (2 to 200 bar). According to a preferred embodiment of the present invention, the composition in step (e) is subjected to a temperature of 80 to 400° C. and a pressure of 0.5 to 20 MPa (2 to 200 bar).

According to a preferred embodiment of the present invention, the composition in step (e) is

- 6 047029 is exposed to a temperature of 80 to 240°C and a pressure of 0.5 to 20 MPa (5 to 200 bar) and the pH of the composition is adjusted to a value of 9 to 13.

The time period for complete processing of the composition according to step (e) can be determined by one skilled in the art. Conventional quantitative and qualitative analytical methods such as conductivity measurements, pH measurements, mass spectrometry, powder diffraction, etc. can be used for this purpose.

In one embodiment, step (e) is performed for a period of time from 1 minute to 24 hours, preferably from 5 minutes to 10 hours, and more preferably from 15 minutes to 2 hours.

Step (e) according to the invention can also be carried out in stages. This means that the composition obtained in step (d) can be first subjected to a first condition of temperature and/or pressure, and then a second condition of a different temperature and/or pressure. It will be understood that such a stepwise process is not limited to two steps, but may also include three or more steps. Surprisingly, it has been discovered that a two or more step process can improve the extraction of certain inorganic compounds from the treated composition. For example, amorphous silica may be recovered from the composition at one stage and crystalline silica at another stage of the process.

In one embodiment of the present invention, step (e) is carried out in stages under at least two different conditions of temperature, pressure and/or pH, preferably under at least two different conditions of temperature and pressure.

In one embodiment of the present invention, step (e) is performed in two or more stages, each stage having a different temperature and/or pressure. For example, step (e) may be a two-step process in which, in a first step, the composition obtained in step (d) is subjected to a temperature of 100 to 200°C, preferably 160 to 180°C, and a pressure of 1 kPa to 5 MPa (0.01 to 50 bar) (e.g. 0.2 to 5 MPa (2 to 50 bar)), preferably 10 kPa to 1.5 MPa (0.1 to 15 bar) (e.g. 0.2 to 1.5 MPa (2 to 15 bar)), followed by a second stage at a temperature of 150 to 300°C, preferably 180 to 200°C, and a pressure of 1 kPa to 5 MPa (0 01 to 50 bar) (eg 0.2 to 5 MPa (2 to 50 bar)), preferably 1 to 2 MPa (10 to 20 bar).

It is also possible to add an additional amount of the aqueous fluid of step (b) and/or an additional amount of alkali metal hydroxide and/or an alkali metal of step (c) to the composition in step (e). According to one embodiment, step (e) includes adding an additional amount of aqueous fluid according to step (b) and/or an additional amount of alkali metal hydroxide and/or an alkali metal according to step (c).

It is also possible to remove the aqueous phase before adding an additional amount of aqueous fluid according to step (b) and/or an additional amount of alkali metal hydroxide and/or an alkali metal according to step (c). According to one embodiment, step (e) comprises removing the aqueous phase followed by adding an additional amount of aqueous fluid according to step (b) and/or an additional amount of alkali metal hydroxide and/or an alkali metal according to step (c).

Step (e) can be carried out in a reactor designed for a temperature of -35 to 400°C and a pressure of 100 Pa to 20 MPa (0.001 to 200 bar). Such reactors are known to those skilled in the art. For example, step (e) can be carried out in a high pressure reactor or a hydrothermal reactor. Moreover, step (e) can be carried out in a batch reactor, a semi-batch reactor or a flow reactor, preferably a batch reactor or a semi-batch reactor.

Stage (f).

In step (f) of the process according to the invention, the carbonaceous solid is separated from the composition obtained in step (e).

The carbonaceous solid can be separated by filtration. According to a preferred embodiment, step (f) comprises filtering the carbonaceous solid. In such a case, the carbonaceous solid is obtained as a residue and an aqueous filtrate is obtained.

One skilled in the art will select suitable filtration means. For example, carbonaceous solids can be separated by mechanical filtration through a filter membrane. Suitable filter membranes are, for example, microfiltration membranes. In one embodiment, a filter membrane is used that has an average pore diameter of greater than 1 μm, preferably 1 to 100 μm, more preferably 1 to 50 μm, and most preferably 1 to 20 μm.

Surprisingly, it has been found that the carbonaceous solid obtained in step (f) has the same physical properties or only slightly different physical properties than the carbonaceous solid present in the mixture of step (a). Therefore, the carbonaceous solid present in the mixture of step (a) can be obtained in step (f) unchanged or only in a slightly modified form.

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In one embodiment, the carbonaceous solid of step (f) has the same physical characteristics or only slightly different physical characteristics than the carbonaceous solid present in the mixture of step (a). According to one embodiment, the carbonaceous solid of step (f) has the same or only slightly different morphology from the carbonaceous solid present in the mixture of step (a). The morphology of a carbonaceous solid in the sense of the present invention refers to the structure and/or shape of the material. The structure and/or shape of a material can be determined, for example, by scanning electron microscopy (morphology), laser diffraction (particle size) or Raman spectroscopy (structure).

According to one embodiment of the present invention, the carbonaceous solid of step (f) is at least 80% (e.g., 80 to 99.8%), preferably at least 90%, more preferably at least 95% (e.g. 95 to 99.8%) of carbon, and preferably carbon black, and/or the separated carbonaceous solid of step (f) is present with inorganic compounds in an amount of less than 5.0 wt.% (for example, from 0.01 to less than 5 .0 wt.%), preferably less than 2.0 wt.% and more preferably less than 1.0 wt.%, based on the total weight of separated carbonaceous solids and inorganic compounds.

According to one embodiment of the present invention, the carbonaceous solid of step (f) consists of at least 80% (for example, from 80 to 99.8%), preferably at least 90%, more preferably at least 95% (for example, from 95 to 99.8%) from carbon.

According to one embodiment of the present invention, the carbonaceous solid of step (f) is at least 80% (e.g., 80 to 99.8%), preferably at least 90%, more preferably at least 95% (e.g. from 95 to 99.8%) of carbon, and preferably carbon black, and is present together with inorganic compounds in an amount of less than 5.0% by weight (for example, from 0.01 to less than 5.0% by weight), preferably less 2.0% by weight, and more preferably less than 1.0% by weight, based on the total weight of carbonaceous solids and inorganic compounds separated.

According to one embodiment of the present invention, the carbonaceous solid of step (f) is at least 80% (e.g., 80 to 99.8%), preferably at least 90%, more preferably at least 95% (e.g. from 95 to 99.8%) from carbon black.

According to one embodiment of the present invention, the carbonaceous solid of step (f) is at least 80%, preferably at least 90% (e.g., 80 to 99.8%), more preferably at least 95% (e.g. from 95 to 99.8%) of carbon, and preferably carbon black, and is present together with inorganic compounds in an amount of less than 5.0% by weight (for example, from 0.01 to less than 5.0% by weight), preferably less 2.0% by weight, and more preferably less than 1.0% by weight, based on the total weight of carbonaceous solids and inorganic compounds separated.

According to one embodiment of the present invention, the carbonaceous solid of step (f) consists of at least 80% (for example, from 80 to 99.8%), preferably at least 90%, more preferably at least 95% carbon ( for example, from 95 to 99.8%), and preferably carbon black, and is present together with inorganic compounds in an amount of less than 5.0% by weight (for example, from 0.01 to less than 5.0% by weight), preferably less 2.0 wt.% and more preferably less than 1.0 wt.%, based on the total weight of separated carbonaceous solids and inorganic compounds, wherein the inorganic compounds are selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates and mixtures thereof.

Particularly preferably, the carbonaceous solid separated in step (f) contains or consists of carbon black. For example, the carbonaceous solid may be at least 90%, preferably at least 95% (eg, 95 to 99.8%) carbon black. The physical and chemical properties of carbon black are known to those skilled in the art. For example, the primary carbon black particles may have a diameter of from 1 to 600 nm, preferably from 10 to 300 nm. The grain diameter of the primary particles can be measured using laser diffraction. Primary carbon black particles can combine to form carbon black aggregates, which can have a diameter of 80 to 800 nm. These carbon black aggregates, in turn, can form superstructures in the form of carbon black agglomerates. In addition, carbon black may have a specific surface area of 5 to 1500 m ² /g, preferably 15 to 600 m ² /g, measured according to the BET method. In one embodiment of the present invention, the carbonaceous solid of step (f) consists of carbon black having an elemental composition of 90.0 to 99.7% C, 0.1 to 0.6% H, 0.01 to 0. 8% S and 0.2 to 3.5% O.

Possible stages of the method.

In addition to steps (a)-(f), the method of the present invention may include additional method steps.

In step (f) of the present invention, after separation of the carbonaceous solid, an aqueous phase is formed. The method may include additional steps of treating the aqueous phase. Thus,

- 8 047029 additional raw materials can be obtained and/or extracted. Typically, this aqueous phase obtained in step (f) contains at least nitrogen hydride and/or its reaction products, hydroxide compounds and inorganic compounds and/or reaction products thereof. Depending on what composition is selected for the aqueous fluid, the aqueous phase obtained in step (f) may also contain other substances. For environmental and/or economic reasons, it may be advantageous to separate the nitrogen hydride and/or its reaction products, hydroxide compounds and inorganic compounds and/or their reaction products from the resulting aqueous phase.

According to one embodiment, the method further includes the step (g) of treating and/or recycling the aqueous phase obtained in step (f).

According to one embodiment, step (g) includes the following steps:

g1) separation of nitrogen hydride according to step (b) and/or its reaction products, and/or g2) separation of one or more inorganic compounds according to step (a) and/or their reaction products, and/or g3) recovery of process water.

According to one embodiment, step (g) includes the following steps:

g1) separating the nitrogen hydride according to step (b) and/or its reaction products, and g2) separating one or more inorganic compounds according to step (a) and/or their reaction products, and g3) recovering process water.

According to one embodiment, step (g) includes the following steps:

g1) separating the nitrogen hydride according to step (b) and/or its reaction products, and g2) separating one or more inorganic compounds according to step (a) and/or their reaction products from the composition obtained in step (g1), and g3) extracting process water from the composition obtained in step (g2).

According to one embodiment, step (g) includes the following steps:

g1) separating nitrogen hydride and/or its reaction products, namely one or more ammonium salts, and g2) separating one or more inorganic compounds according to step (a) and/or their reaction products, namely one or more sodium silicates from the composition obtained in step (g1), and g3) extracting process water from the composition obtained in step (g2).

Steps (g1), (g2) and/or (g3) can be carried out using techniques and devices known to the person skilled in the art.

Application

Another aspect of the present invention is the use of nitrogen hydride as a dispersing agent to obtain and/or stabilize an aqueous suspension comprising a carbonaceous solid and at least one inorganic compound.

The term obtaining and/or stabilizing an aqueous suspension within the meaning of the present invention means that a mixture of solid and liquid phases can be formed, in which the solid phase can be mixed with the dispersing medium without sedimentation, formation of larger aggregates and/or sedimentation.

Surprisingly, it has been discovered that nitrogen hydride can be used to stabilize an aqueous dispersion or suspension that contains a mixture containing a carbonaceous solid and at least one inorganic compound.

Preferred embodiments of the aqueous fluid and mixture containing solid carbonaceous matter and at least one inorganic compound are described above in the description of step (a) and step (b) of the method of the present invention.

In one embodiment, nitrogen hydride is used as a dispersing agent to form and/or stabilize an aqueous suspension containing a carbonaceous solid and at least one inorganic compound, where the carbonaceous solid is at least 90% carbon black (for example, from 90 up to 99.5%), and the at least one inorganic compound is a plurality of inorganic compounds selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof.

In one embodiment, nitrogen hydride is used as a dispersing agent to prepare and/or stabilize an aqueous suspension containing a carbonaceous solid and at least one inorganic compound, where the carbonaceous solid is at least 90% carbon black (for example, from 90 up to 99.5%), wherein the at least one inorganic compound is a plurality of inorganic compounds selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates and mixtures thereof, and a nitrogen hydride is selected from the group consisting of ammonia, inorganic ammonium salts, primary or secondary organic amines and ammonium salts thereof, and mixtures thereof, preferably from the group consisting of ammonia, ammonium hydroxide, ammonium halides, guanidine, derivatives

- 9 047029 aqueous guanidine and ammonium salts thereof, and mixtures thereof, more preferably one nitrogen hydride is ammonia and/or ammonium hydroxide and most preferably ammonium hydroxide.

Other incarnations

In a preferred embodiment, the method of treating and/or purifying carbonaceous solids according to the invention includes the steps of:

a) providing a mixture containing a carbonaceous solid, preferably carbon black, and at least one inorganic compound, where the mixture comprises a carbonaceous solid in an amount of from 70 to 99% by weight, and more preferably from 80 to 98% by weight, based on the total weight of the carbonaceous solid and at least one inorganic compound, and includes at least one inorganic compound in an amount of from 1 to 30 wt.%, preferably from 2 to 20 wt.%, based on the total weight of the carbonaceous solid and at least at least one inorganic compound;

b) providing an aqueous fluid containing nitrogen hydride;

c) providing an alkali metal hydroxide, preferably NaOH;

d) bringing into contact the mixture of step (a), the fluid of step (b) and the alkali metal hydroxide and/or alkali metal of step (c);

e) exposing the composition obtained in step (d) to elevated temperature in the range of 80 to 240° C. and elevated pressure in the range of 0.5 to 5 MPa (5 to 50 bar);

f) separating the carbonaceous solid from the composition obtained in step (e), wherein the carbonaceous solid obtained in step (f) consists of at least 80%, preferably at least 90%, more preferably at least 95% (for example, from 95 to 99.5%) of carbon, and preferably carbon black, and is present together with inorganic compounds in an amount of less than 5.0% by weight (for example, from 0.01 to 5% by weight) preferably less than 2.0% by weight, and more preferably less than 1.0% by weight, based on the total weight of carbonaceous solids and inorganic compounds separated.

Other aspects and embodiments of the present invention are as follows.

[1] A method for treating and/or purifying carbonaceous solids, comprising the steps of:

a) providing a mixture containing a carbonaceous solid and at least one inorganic compound;

b) providing an aqueous fluid containing nitrogen hydride;

c) providing an alkali metal hydroxide and/or an alkali metal;

d) bringing into contact the mixture of step (a), the fluid of step (b) and the alkali metal hydroxide and/or alkali metal of step (c);

e) subjecting the composition obtained in step (d) to reduced or increased temperature and/or reduced or increased pressure;

f) separating the carbonaceous solid from the composition obtained in step (e).

[2] The method according to paragraph [1], wherein the mixture of step (a) includes a carbonaceous solid in an amount of more than 50 wt%, preferably more than 70 wt%, and more preferably more than 80 wt%, based on the total weight of the mixture, and/or the mixture of step (a) includes at least one inorganic compound in an amount of 1 to 30% by weight, preferably 5 to 20% by weight, based on the total weight of the mixture.

[3] The method according to paragraph [1] or [2], in which the mixture of step (a) is a solid mixture and/or the mixture of step (a) is obtained by pyrolysis of carbonaceous material, preferably waste tires or biomass.

[4] The method according to any of the preceding paragraphs [1]-[3], wherein the carbonaceous solid is at least 80%, preferably at least 90%, more preferably at least 95% carbon, and preferably technical carbon, and/or at least one inorganic compound is at least one mineral and/or salt, preferably selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates and mixtures thereof.

[5] The method according to any of the preceding paragraphs [1] to [4], wherein the fluid of step (b) includes a nitrogen hydride selected from the group consisting of ammonia, inorganic ammonium salts, primary or secondary organic amines and ammonium salts thereof and mixtures thereof, preferably from the group consisting of ammonia, ammonium hydroxide, ammonium halides, guanidine, guanidine derivatives and ammonium salts thereof and mixtures thereof, more preferably the nitrogen hydride is ammonia and/or ammonium hydroxide and most preferably ammonium hydroxide, and/ or the fluid of step (b) further contains one or more substances selected from the group consisting of alcohols, oxidizing agents, acids, nitrates and carbonates.

[6] The method according to any of the preceding paragraphs [1] to [5], wherein the alkali metal hydroxide and/or the alkali metal of step (c) is provided in a molar ratio to the inorganic compounds of the mixture of step (a) from 0.25:1 to 2:1, preferably 0.5:1 to 1.5:1, more preferably 0.75:1 to 1.25:1 and most preferably 0.95:1 to 1.05:1, and/ or fluid

- 10 047029 in step (b) is provided in an amount of from 2 to 200 l (fluid)/1 kg (mixture of step (a)), preferably from 5 to 150 l (fluid)/1 kg (mixture of step (a)) ) and more preferably from 10 to 100 L (fluid)/1 kg (mixture of step (a)).

[7] The method according to any of the preceding paragraphs [1] to [6], wherein the composition in step (e) is exposed to a temperature of -35 to 400°C, preferably 25 to 300°C, and more preferably 80 to 240 °C, and/or the composition in step (e) is subjected to a pressure of from 0.1 kPa to 20 MPa (0.001 to 200 bar), preferably from 0.1 to 10 MPa (1 to 100 bar) and more preferably from 0.5 to 5 MPa (5 to 50 bar), and/or the pH of the composition in step (e) is adjusted to a value of from 0 to 14, preferably from 7 to 14 and more preferably from 9 to 13.

[8] The method according to any of the preceding paragraphs [1] to [7], wherein step (e) is carried out stepwise under at least two different conditions of temperature, pressure and/or pH, preferably under at least two different temperature conditions and pressure, and/or step (f) involves filtering the carbonaceous solid.

[9] The method according to any of the preceding paragraphs [1] to [8], wherein the carbonaceous solid of step (f) is at least 80%, preferably at least 90%, more preferably at least 95% of carbon, and preferably carbon black, and/or the separated carbonaceous solid of step (f) is present together with inorganic compounds in an amount of at least 5.0 wt.%, preferably at least 2.0 wt.% and more preferably at at least 1.0% by weight, based on the total weight of separated carbonaceous solids and inorganic compounds.

[10] The use of nitrogen hydride as a dispersing agent to obtain and/or stabilize an aqueous suspension comprising a carbonaceous solid and at least one inorganic compound.

Examples

The present invention is further described by the following examples.

Example 1 Example 2 Mixture quantity according to stage (a) (recovered carbon black) 1 g 60 g Amount of fluid according to step (b) (aqueous solution of NH ₄ OH) 50 ml 2.5 l Fluid concentration (NH4OH mol/l) 0.09 mol/l 0.1 mol/l Alkali metal hydroxide according to step (c) 0.135 rNaOH 12 rNaOH Pressure 0.82 MPa (8.2 bar) 1.12 MPa (11.2 bar) Temperature (Tmax) 160°C 180°C Exposure time Tmax 30 min 30 min

The mixture according to step (a) was a mixture obtained by pyrolysis of waste tires.

Claims (15)

1. A method for purifying carbonaceous solids, comprising the steps of: a) providing a mixture containing a carbonaceous solid and two or more inorganic compounds, where the carbonaceous solid includes carbon black; b) providing an aqueous fluid containing nitrogen hydride; c) providing an alkali metal hydroxide and/or an alkali metal; d) bringing into contact the mixture of step (a), the fluid of step (b) and the alkali metal hydroxide and/or alkali metal of step (c); e) subjecting the composition obtained in step (d) to elevated temperature and elevated pressure with respect to a temperature of 20° C. and a pressure of 1.013 bar (0.1 MPa) as control points; f) separating the carbonaceous solid from the composition obtained in step (e). 2. The method of claim 1, wherein the mixture of step (a) includes a carbonaceous solid in an amount of more than 50% by weight, preferably more than 70% by weight, and more preferably more than 80% by weight, based on the total weight of the mixture, and/ or the mixture of step (a) includes two or more inorganic compounds in an amount of 1 to 30% by weight, preferably 5 to 20% by weight, based on the total weight of the mixture. 3. The method according to claim 1 or 2, wherein the mixture of step (a) is a solid mixture and/or the mixture of step (a) is obtained by pyrolysis of carbonaceous material, preferably waste tires or biomass. 4. The method according to any one of the preceding claims 1 to 3, in which the carbonaceous solid consists - 11 047029 it is at least 80%, preferably at least 90%, more preferably at least 95% carbon, and preferably carbon black, and/or two or more inorganic compounds selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates and mixtures thereof. 5. The method according to any of the preceding claims 1 to 4, wherein the fluid of step (b) includes a nitrogen hydride selected from the group consisting of ammonia, inorganic ammonium salts, primary or secondary organic amines and their ammonium salts and mixtures thereof, preferably from the group consisting of ammonia, ammonium hydroxide, ammonium halides, guanidine, guanidine derivatives and ammonium salts thereof, and mixtures thereof, more preferably the nitrogen hydride is ammonia and/or ammonium hydroxide, and most preferably ammonium hydroxide and/or fluid the medium of step (b) further contains one or more substances selected from the group consisting of alcohols, oxidizing agents, acids, nitrates and carbonates. 6. The method according to any of the preceding claims 1 to 5, in which the alkali metal hydroxide and/or the alkali metal of stage (c) is provided in a molar ratio to the inorganic compounds of the mixture of stage (a) from 0.25:1 to 2:1, preferably from 0.5:1 to 1.5:1, more preferably from 0.75:1 to 1.25:1 and most preferably from 0.95:1 to 1.05:1 and/or fluid at the stage (b) provide in an amount of from 2 to 200 L (fluid)/1 kg (mixture of step (a)), preferably from 5 to 150 L (fluid)/1 kg (mixture of step (a)) and more preferably from 10 to 100 l (fluid)/1 kg (mixture of stage (a)). 7. The method according to any of the preceding claims 1 to 6, wherein the composition in step (e) is exposed to a temperature of from 25 to 300°C and more preferably from 80 to 240°C, and/or the composition in step (e) is subjected to subjected to a pressure of from 0.1 to 10 MPa (1 to 100 bar) and more preferably from 0.5 to 5 MPa (5 to 50 bar), and/or the pH of the composition in step (e) is adjusted to a value of from 7 to 14 and more preferably from 9 to 13. 8. Method according to any of the preceding claims 1 to 7, wherein step (e) is carried out in stages under at least two different conditions of temperature, pressure and/or pH, preferably under at least two different conditions of temperature and pressure. 9. The method according to any of the preceding claims 1 to 8, wherein the carbonaceous solid of step (f) consists of at least 80%, preferably at least 90%, more preferably at least 95% carbon, preferably carbon black, and/or the separated carbonaceous solid of step (f) is present together with inorganic compounds in an amount of from 0.001 to 5.0 wt.%, preferably from 0.001 to 2.0 wt.% and more preferably from 0.001 to 1.0 wt.%, based on the total mass of separated carbonaceous solids and inorganic compounds. 10. The method according to any of the preceding claims 1 to 9, further comprising step (g) of purifying and/or treating the aqueous phase obtained in step (f), comprising the following steps: g1) separation of nitrogen hydride according to step (b) and/or its reaction products, and/or g2) separation of one or more inorganic compounds according to step (a) and/or their reaction products, and/or g3) recovery of process water. 11. The method according to any of the preceding claims 1 to 10, wherein the two or more inorganic compounds of step (a) comprise two or more inorganic compounds that are at least sparingly soluble in water, preferably very sparingly soluble in water, and most preferably insoluble in water. 12. The method according to any of the preceding claims 1 to 11, wherein the aqueous fluid of step (b) has a nitrogen hydride concentration of from 0.001 to 16.5 mol/L, preferably from 0.05 to 5 mol/L and more preferably from 0.09 to 0.9 mol/l. 13. The method of claim 10, wherein step (g1) includes separating one or more ammonium salts, and step (g2) includes separating one or more sodium silicates from the composition obtained in step (g1), and step (g3) includes extracting process water from the composition obtained in step (g2). 14. The method according to any of the preceding claims 1 to 13, in which the carbonaceous solid of step (a) consists of from 90 to 99.8%, preferably from 95 to 99.8% carbon, preferably carbon black; the two or more inorganic compounds of step (a) include two or more inorganic compounds selected from the group consisting of one or more metal sulfides, one or more metal oxides, one or more silicates, and mixtures thereof; the aqueous fluid of step (b) includes a nitrogen hydride selected from the group consisting of am - 12 047029 monia, ammonium hydroxide, ammonium halides, guanidine, guanidine derivatives and ammonium salts thereof, and mixtures thereof, preferably consisting of ammonia, ammonium hydroxide and mixtures thereof; in step (c) providing an alkali metal hydroxide, preferably selected from NaOH, KOH and mixtures thereof; in step (d), the mixture of step (a), the fluid of step (b) and the alkali metal hydroxide of step (c) are mixed; in step (e), the composition obtained in step (d) is subjected to elevated temperature and elevated pressure, preferably a temperature of 80 to 240° C. and a pressure of 0.2 to 10 MPa (2 to 100 bar); and in step (f) separating a carbonaceous solid which consists of 90 to 99.8%, preferably 95 to 99.8% carbon, preferably carbon black. 15. The method according to claim 1, wherein the composition in step (e) is subjected to a temperature of 50 to 400° C. and a pressure of 0.2 to 20 MPa (2 to 200 bar).