Search

EP-4741132-A1 - PROCESS FOR SEPARATING METALS AND/OR PLASTICIZERS FROM PARTICLES WITH A POLYMERIC MATRIX

EP4741132A1EP 4741132 A1EP4741132 A1EP 4741132A1EP-4741132-A1

Abstract

To separate metals (20) and/or plasticizers (19) from particles (3) with a polymer matrix, the particles (3) are provided either as granular particles with an average initial particle size in a first particle size range of 1 mm to 12 mm or as planar particles with a wall thickness of no more than 2 mm and an average initial particle size in a first particle size range of 2 mm to 100 mm. The provided particles (3) are suspended (4) in a liquid solvent (5), selected from solvents in which the polymer matrix of the particles (3) swells without dissolving the polymer matrix, and the polymer matrix of the particles (3) is allowed to swell in the solvent (5). Shear forces (9) are applied to the particles (8) to break up the swollen polymer matrix into fragments (10) with an average fragment size in a second particle size range of 0.05 mm to 0.8 mm. The fragments (15) are separated from the metals (20) and the plasticizers (19) from the solvent (5) (18).

Inventors

  • Deinert, Dr. Jürgen

Assignees

  • D&G Recycling GmbH

Dates

Publication Date
20260513
Application Date
20241111

Claims (15)

  1. Method for separating metals (20) and/or plasticizers (19) from particles (3) with a polymeric matrix, comprising the steps - Providing the particles (3) either as granular particles with an average initial particle size in a first particle size range of 1 mm to 12 mm or as planar particles with a wall thickness of a maximum of 2 mm and an average initial particle size in a first particle size range of 2 mm to 100 mm, - Suspending (4) the provided particles (3) in a liquid solvent (5) selected from solvents in which the polymeric matrix of the particles (3) swells without dissolving the polymeric matrix, and allowing the polymeric matrix of the particles (3) to swell in the solvent (5), - Applying shear forces (9) to the particles (8) to break up the swollen polymer matrix into fragments (10) with a mean fragment size in a second particle size range of 0.05 mm to 0.8 mm, - separate separation of the extracted fragments (15) and the metals (20) and/or plasticizers (19) from the solvent (5).
  2. Method according to claim 1, - wherein a composition of the solvent (5) is adjusted and/or an additional extraction agent immiscible with the solvent (5) is added to extract the metals (20) and/or the plasticizers (19) from the fragments (10), - wherein the fragments (10) are extracted with the solvent (5) or with the solvent (5) and the additional extraction agent, - wherein the extracted fragments (15) are separated separately from the metals (20) and/or the plasticizers (19) from the solvent (5) or from the solvent (5) and the additional extraction agent.
  3. The method of claim 2, wherein an acid is added to adjust the composition of the solvent (5) and/or to add the additional extraction agent that is immiscible with the solvent (5), wherein the acid optionally adjusts the pH of the solvent to a range of 1 to 5.
  4. Method according to claim 3, wherein the acid is carbonic acid with a CO2 partial pressure of at least 2.0 MPa on the solvent (5).
  5. The method of claim 2, wherein an alkali is added to adjust the composition of the solvent (5) and/or to add an additional extraction agent that is immiscible with the solvent (5), wherein the alkali is optionally used to adjust the pH of the solvent to at least 9.
  6. The method of claim 5, wherein the lye is aqueous or alcoholic sodium hydroxide solution, optionally containing at least 8% by weight sodium hydroxide, or aqueous or alcoholic potassium hydroxide solution, optionally containing at least 8% by weight potassium hydroxide.
  7. Method according to any of the preceding claims, wherein the particles (3) are provided with a polymeric matrix based on PVC and/or PVDF and/or PE and/or LDPE and/or HDPE, wherein the plasticizers (19) are optionally phthalate plasticizers to more than 50 wt percent and/or constitute 25 wt percent to 75 wt percent of a fraction of the particles (3) comprising the polymeric matrix.
  8. Method according to any of the preceding claims, wherein the metals (20) in the particles (3) are lead and/or aluminium to more than 50% by weight, wherein, optionally, the metals (20) in the particles (3) are present to more than 50% by weight in the form of metal salts and/or metal oxides and/or metal hydroxides.
  9. Method according to one of the preceding claims, wherein the polymeric matrix is allowed to swell (7) until its volume has increased by 10% to 100% and wherein the swollen matrix is broken up into fragments (10) whose mean particle size is not greater than 50% of the mean initial particle size increased by the swelling of the polymeric matrix and, in the case of planar particles, also not greater than 50% of their wall thickness increased by the swelling of the polymeric matrix.
  10. Method according to any of the preceding claims, wherein the solvent (5) is selected from more than 50% by weight of: - hydrocarbons and/or - alcohols and/or - Tetrahydrofuran (THF) or cyclohexanone.
  11. Method according to one of the preceding claims, wherein - the solvent (5) has a boiling point of at least 90 °C at normal pressure and/or - the temperature of the solvent (5) during swelling (7) is set within a temperature range of 20 K to 10 K below the boiling point of the solvent (5).
  12. Method according to one of the preceding claims, wherein - to exert the shear forces (9) on the particles (8) the solvent (5) with the particles (3) suspended therein is stirred and/or passed between counter-rotating disks and/or - to separate the fragments (15) from the solvent (5), the fragments (15) are filtered from the solvent.
  13. Method according to any of the preceding claims, - wherein the total process time from suspending (4) the particles (3) in the solvent (5) to separating the fragments (15) from the solvent (5) does not exceed 60 min and/or - wherein residual concentrations of the metals (20) and/or the plasticizers (19) in the separated fragments (15) are less than 0.1 percent by weight and preferably not more than 0.05 percent by weight.
  14. Method according to one of the preceding claims, wherein , in order to separate (18) the metals (20) and/or plasticizers (19) from the solvent (5), the solubility of the metals (20) and/or plasticizers (19) in the solvent (5) is reduced by changing the pressure, temperature, pH value and/or composition of the solvent (5).
  15. Method according to one of the preceding claims, wherein to separate the metals (20) and/or plasticizers (19) from the solvent (5) the solvent (5) is evaporated, wherein the solvent (5) is subsequently condensed.

Description

The invention relates to a method for separating metals and/or plasticizers from particles with a polymer matrix. When recycling many plastics, metals and/or plasticizers contained within the plastics, as well as metals bonded to the plastics, pose a problem. In many cases, the metals and plasticizers present in plastics fundamentally preclude their reuse because they hinder the plastics' technical reusability and/or because their potential health hazards make them no longer permissible as additives. Lead is one example of a metal that was used in plastics production for a long time but is now prohibited. However, lead, particularly as toxic lead salts, is present in significant concentrations in many existing plastics. Another particularly relevant metal is aluminum, which can be found, for example, in fire retardant additives for plastics in the form of bauxite, and which can also be bonded to plastics, especially in the form of aluminum foil. The most significant plasticizers that prevent the direct reuse of plastics are those based on phthalates, also referred to here as phthalate plasticizers. In order to enable the reuse of plastics that contain or are combined with potentially disruptive or prohibited metals and plasticizers, these metals and plasticizers must be safely reduced to residual concentrations below permissible limits. STATE OF THE ART From the JP 4 685 728 B2 A process is known for obtaining a raw material from a lead-containing flexible PVC starting material, in which a plasticizer and a lead compound are removed from the starting material. The plasticizer can be a phthalate plasticizer. The starting material is crushed to a suitable size and then contacted with a mixture of supercritical carbon dioxide and an aliphatic alcohol with 1 to 3 carbon atoms. To bring the carbon dioxide to a supercritical state, a temperature and pressure above the critical point of 31 °C and 7.375 MPa are set. Specifically, contacting is carried out at a temperature of 55 °C and a pressure of 10 MPa for 20 minutes. If the contacting is repeated 22 times with fresh mixture, the residual concentration of the plasticizer in the PVC material is less than 10 ppm. The lead extracted from the starting material as lead carbonate with the liquid mixture is precipitated from the liquid mixture. No information is provided regarding the residual lead concentration in the PVC. The known process is very complex due to the use of supercritical carbon dioxide. TASK OF INVENTION The invention is based on the objective of demonstrating a method for separating metals and plasticizers from particles with a polymer matrix, which is suitable with limited effort for reprocessing various plastics containing metals and/or plasticizers as well as adhering metals for reuse. SOLUTION The object of the invention is achieved by a method having the features of independent claim 1. The dependent claims relate to preferred embodiments of the method according to the invention. DESCRIPTION OF THE INVENTION In a process according to the invention for separating metals and/or plasticizers from particles with a polymeric matrix, the particles are either granular, i.e., as in Particles extending at least approximately equally in all three dimensions, with an average initial particle size in a first particle size range of 1 mm to 12 mm, preferably from 1 mm to 5 mm, or as planar, i.e., essentially two-dimensional, particles with a wall thickness of less than 2 mm, preferably less than 1 mm, and an average initial particle size in a first particle size range of 1 mm to 100 mm, preferably from 2 mm to 70 mm, are provided. This may require the comminution of larger particles. This can be done in any method known in principle. The provided particles are suspended in a liquid solvent in which the polymeric matrix of the particles swells without dissolving the polymeric matrix, and the polymeric matrix is allowed to swell. The liquid solvent, hereinafter referred to simply as the "solvent," is selected from solvents that penetrate the polymeric matrix of the particles, causing it to swell, but that do not dissolve the polymeric matrix under the conditions under which it is allowed to swell. Thus, in the process according to the invention, the solvent is selected and used not as a dissolving agent for the polymeric matrix, but as a swelling agent. After swelling, shear forces are applied to the particles to break up the swollen polymer matrix into fragments with an average fragment size in a second particle size range of 0.05 mm to 0.8 mm, preferably 0.1 mm to 0.5 mm. Only the shear forces, which are used in a controlled manner in the inventive process to adjust the average fragment size within this second particle size range, cause the polymer matrix of the swollen particles to break up. Even then, the polymer matrix does not dissolve in the solvent; rather, each of the fragments into which the swollen particles are broken up retains a contiguous portio