Processing and Purification of Carbonaceous Materials

Abstract

The present invention relates to a process for the processing and/or purification of carbon black comprising the steps of: a) providing carbon black containing impurities b) providing an aqueous fluid comprising a nitrogen hydride c) providing an alkali metal hydroxide and/or an alkali metal d) contacting 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 an elevated temperature in the range of 80 to 240° C. and an elevated pressure in the range of 5 to 50 bar f) separating a carbonaceous solid from the composition obtained in step e). The present invention further relates to the use of a nitrogen hydride as a dispersing agent for producing and/or stabilizing an aqueous suspension.

Claims

1. A process for processing and/or purifying carbonaceous solids comprising the steps of: a) providing a mixture comprising a carbonaceous solid and at least one inorganic compound, b) providing an aqueous fluid comprising a nitrogen hydride, c) providing an alkali hydroxide and/or an alkali metal d) contacting 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 a reduced or increased temperature and/or to a reduced or increased pressure f) separating a carbonaceous solid from the composition obtained in step e).

2. The process according to claim 1, wherein the mixture of step a) comprises the carbonaceous solid in an amount of from 50 to 99 wt. %, based on a total weight of the mixture, and/or wherein the mixture of step a) comprises the at least one inorganic compound in an amount of from 1 to 30 wt. %, based on the total weight of the mixture.

3. The process according to claim 1, where the mixture of step a) is a solid mixture, and/or wherein the mixture of step a) is obtained by pyrolysis of a carbonaceous material, preferably scrap tyres or biomass.

4. The process according to claim 1, where the carbonaceous solid consists of from 80 to 99.8%, of carbon, and/or wherein the at least one inorganic compound is at least one mineral and/or salt selected from the group consisting of one or more metal sulphides, one or more metal oxides, one or more silicates and mixtures thereof.

5. The process according to claim 1, wherein the fluid of step b) comprises 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; and/or wherein the fluid of step b) additionally comprises one or more substances selected from the group consisting of alcohols, oxidizing agents, acids, nitrates and carbonates.

6. The process according to claim 1, wherein the alkali hydroxide and/or alkali metal in step c) is provided in a molar ratio to the inorganic compounds of the mixture of step a) in the range of from 0.25:1 to 2:1, and/or wherein the fluid in step b) is provided in an amount ranging from 2 L (fluid)/1 kg (mixture of step a)) to 200 L (fluid)/1 kg (mixture of step a)).

7. The process according to claim 1, wherein the composition in step e) is subjected to a temperature of −35° C. to 400° C., and/or wherein the composition in step e) is subjected to a pressure of 0.001 to 200 bar, and/or wherein the pH of the composition in step e) is adjusted to a value of 0 to 14.

8. The process according to claim 1, wherein step e) is carried out stepwise under at least two different conditions of temperature, pressure and/or pH.

9. The process according to claim 1, wherein the carbonaceous solid of step f) consists of from 80 to 99.8%, of carbon, and/or wherein the separated carbonaceous solid of step f) is present together with inorganic compounds in an amount of from 0.001 to 5.0 wt. %, based on the total weight of the separated carbonaceous solid and the inorganic compounds.

10. The process according to claim 1, comprising a step g) of treating and/or working-up an aqueous phase obtained in step f), comprising the following steps: g1) separating the nitrogen hydride according to step b) and/or reaction products thereof, and/or g2) separating one or more inorganic compounds according to step a) and/or reaction products thereof, and/or g3) recovering the process water.

11. The process according to claim 1, wherein the at least one inorganic compound of step a) comprises two or more inorganic compounds which are at least poorly water soluble.

12. The process according to claim 1, wherein the aqueous fluid of step b) has a concentration of nitrogen hydride in the range of 0.001 to 16.5 mol/L.

13. The process according to claim 10, wherein step g1) comprises separating one or more ammonium salts, and wherein step g2) comprises separating one or more sodium silicates from the composition obtained in step g1), and wherein step g3) comprises recovering the process water from the composition obtained in step g2).

14. The process according to claim 1, wherein the carbonaceous solid of step a) consists of from 90 to 99.8% of carbon, wherein the at least one inorganic compound of step a) comprises two or more inorganic compounds selected from the group consisting of one or more metal sulphides, one or more metal oxides, one or more silicates and mixtures thereof, wherein the aqueous fluid of step b) 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, wherein in step c) an alkali hydroxide, is provided, wherein in step d) the mixture of step a), the fluid of step b) and the alkali hydroxide of step c) are mixed, wherein in step e) the composition obtained in step d) is subjected to an elevated temperature and an elevated pressure, preferably a temperature in the range of 80° C. to 240° C. and a pressure in the range of 2 to 100 bar, and wherein in step f) a carbonaceous solid is separated which consists of from 90 to 99.8%.

15. A dispersant for producing and/or stabilizing an aqueous suspension comprising a nitrogen hydride, wherein the aqueous suspension comprises a carbonaceous solid and at least one inorganic compound.

Description

EXAMPLES

[0153] The present invention is further described by the following examples:

TABLE-US-00001 Example 1 Example 2 Amount of mixture 1 g 60 g according to step a) (recovered carbon black) Amount of fluid according 50 mL 2.5 L to step b) (aqueous NH.sub.4OH solution.) Concentration of the fluid 0.09 mol/L 0.1 mol/L (NH.sub.4OH mol/L) Alkali hydroxide 0.135 g NaOH 12 g NaOH according to step c) Pressure 8.2 bar 11.2 bar Temperature (T.sub.max) 160° C. 180° C. Holding time of T.sub.max 30 min 30 min

[0154] The mixture according to step a) was a mixture obtained by pyrolysis of scrap tyres.