DD293742A5 - METHOD FOR RECOVERING COPPER AND PHENOLPLASTS FROM PCB SURFACES - Google Patents

Abstract

The invention includes a process for the recovery of copper and phenolic plastics from PCB waste. The method relates to the separation of copper from copper-clad thermosetting Schichtpreszstoffen, wherein the crushed material is subjected to a floating-sink sorting by means of halogenated hydrocarbons, in particular bromoform-chloroform mixtures. According to the principle of densimetric separation, the phenolic component floats on the solvent, while the copper particles can be recovered from the bottom of the apparatus and both fractions can be fed to a separate work-up. The used heavy liquid can be used in a cycle process. {Copper recovery; densimetric separation; Sink-float sorting; Leiterplattenabfaelle; organic solvents; halogenated hydrocarbons; thermoset laminates; Kreislauffuehrung; Schwerefluessigkeit; crushing}

Description

The present invention relates to the separation of copper from waste (chips, plates and the like) of printed circuit board production, as may occur in particular in operations that further mechanically process copper-coated plastics after an etching process as well as in those, laminated with metal foils thermosetting laminates handle and process.

Characteristic of the known state of the art

E ¹ Si processing of mineralized and fossil raw materials is widely used by densimetric separation possibilities. Here, in addition to flotation and air-viscous methods are used. In DE-PS 25 55093 the use of screening stages, hydrocyclones and magnetic sheaths for processing and separation of autoshredder debris is proposed. Such mechanical methods fail in the desired copper PCB separation, since a sufficiently high selectivity by the use of cyclones or air classifiers is difficult to achieve. The recovery of magnetic materials from solid mixtures is dedicated to the proposal according to DE-PS 2635161. An application to the copper separation is not possible by nature.

Chlorinated and fluorinated hydrocarbons, such as. As trichloroethane, tetrachloroethane, carbon tetrachloride, are proposed as a heavy medium for the divorce of aluminum-coated packaging material (DD-PS 249370). A disadvantage of these methods is the high toxicity of the proposed chlorinated hydrocarbons and the environmentally hazardous aspect of chlorofluorocarbons. No information is available on the separation possibilities of copper and phenolic materials with suitable liquids.

In addition to the proposals, which are based on the principle of swimming-sink sorting, electrostatic processes (DE-OS 2936856), flotation process (DD-PS 112082) or melting process are known for the separation of metal foils of plastic substrates. In general, this is always to be expected with a high control effort or especially when using elevated temperatures in conjunction with the phenolic plastic material of the circuit boards to consider a significant risk to the environment.

Object of the invention

The object of the invention is a method which allows, with little technical and economic effort in a well controlled manner without any special use of energy, as complete as possible separation of metal-coated plastics, such. As copper-coated circuit boards to achieve in their starting materials.

Explanation of the essence of the invention

The invention has for its object to address a method which allows to separate metal-coated plastics in a cost effective manner in the metal and plastic component, which in turn are fed to a reuse

According to the invention the object is achieved in that the coated material by means of crushing machines of known design (agitator mills, cutting mills, hammer mills) is cut to a particle size = 0.300 mm, if it is not already present by other treatment in such a grain, and to further complete metal Plastic separation is subjected to the known methods of swimming-sink sorting.

As gravity liquid organic solvents are used with a density significantly> 1.3 g / cm ³ and <8.96 g / cm ³ , since a separation between phenoplast (p = 1.2 ... 1.3g / cm ³ ) and copper ( p = 8.96 g / cm ³ ). Conveniently, a medium with a density turns out to be 1.7 g / cm ³ . Such a density includes solvents such as:

p / g · cm " ³ bromoform 2.89 Trifluorchloridbromethan 2.24 ethylene bromide 2.18 Tetrachlorethylene 1.62 Tetrachloroethane 1.60 Tetrachloromethane 1.59 bromobenzene 1.52 chloroform 1.48 trichloroethane 1.46

According to the invention, mixtures of said solvents can be used, with those in the foreground, which cause minimal environmental impact and easy to make densities around 1.7 g / cm ³ adjustable such. B. bromoform-chloroform mixtures.

When using the mentioned or similar separation media, a chemical reaction with the material to be separated is excluded.

According to the known principle of densimetric separation, the heavier copper particles deposit on the bottom of the apparatus, while the lighter plastic component can be skimmed off the liquid surface. An optimal separation is possible only after intensive mixing of the solvent with the comminuted material and a subsequent short settling phase (2-5 minutes).

embodiment

Each 10.00 g of crushed copper-clad circuit boards with a mean particle size of d = 0.300mm were introduced into 50 ml of solvent, preferably a mixture consisting of bromoform / chloroform with a density of ρ = 1.75 g / cm ³ , with vigorous stirring. After complete mixing and a sedimentation time of 2 to 10 minutes, the specific lighter plastic component could be skimmed off. The copper collects at the bottom of the vessel. A wet chemical examination of the individual components gave the following values:

Mass / gw _Cu /% m _Cu / g W _GS 5 _{on the} iku _P (! T /%

Copper Chips 1.13 93.5 1.11 97.51

Phenolic chips 8,87 0,32 0,03 2,63

Thus, in a single process step, 97.5% of the copper with a 98.5% by weight copper can be separated within a few minutes.

The used heavy liquid can be used in a continuous cycle.

Claims (1)

Process for the densimetric separation of metal-coated plastics, in particular copper-clad phenoplasts, characterized in that the comminuted material having a particle size preferably d 0.300 mm, with a heavy liquid containing a halogenated hydrocarbon, but in particular a mixture of bromoform and chloroform of the preferred density ρ = 1 , 7 g / cm ^3, is between the plastic material and that of the copper, is mixed, so that after a short sedimentation time, the specific lighter plastic component floats on the liquid while the copper is sinking. Field of application of the invention