Automotive Recycling
Engineering Workshop at the
Nelson Mandela Metropolitan University NMMU
Port Elizabeth
South Africa 2011
Prof. Dr.-Ing. Joachim Schmidt
5 Recycling of materials from ELV´s
Engineering Workshop Automobile Recycling
2 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
5 Recycling of materials from ELV`s
Composite
Single materials Cutting Material recovery
Co
mp
lex
ity o
f p
art
s
Further
pyrometallurgical,
hydrometallurgical
or chemical
processes
Complex part
1 Extract
A key process step prior to metallurgical treatment of metals
is the crushing of composite materials with a subsequent
sorting. The same is true for polymeric materials.
The efforts made for the material treatment of the actual
recycling process is dependent on the complexity of the
material.
Products made of one single material are to be crushed or
compacted in general.
Engineering Workshop Automobile Recycling
3 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of materials from ELV`s
Composite
Single materials
Classification/Sorting
Cutting Material recovery
Co
mp
lex
ity o
f p
art
s Cutting
Further
pyrometallurgical,
hydrometallurgical
or chemical
processes
1 Extract
1-3 Extracts
Composite materials, such as the instrument panel must be
released through a crusher firstly and then sorted.
There will be several material flows (extracts), which are then
followed up in the recycling process.
Engineering Workshop Automobile Recycling
4 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of materials from ELV`s
Material recovery
Co
mp
lex
ity o
f p
art
s
Further
pyrometallurgical,
hydrometallurgical
or chemical
processes
Complex part
n Extracts
Dismantling
Very complex products, which may include contaminants, batteries, etc., are
firstly disassembled, then crushed and then sorted.
There will be various extracts here, with individual recycling process streams.
The more materials are available in a product, the more complex the building
structure, the more complex crushing and sorting processes to be applied.
Thus, of course, also increase the cost of recycling.
Engineering Workshop Automobile Recycling
5 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Processing of solid waste – principles of summative size reduction
Principle: Reduction of the particle size
Aim: Granulation of the material, extraction of the material
Twin-axis granulator
Pre-cutting of composites made of
plastics, rubber, steel, sheets
Stator shear
Rotor shear
Processroom
Sieve
Composit material
Output
Sieve
Granulator
Cutting of compact, bulky and
voluminous materials (plastics)
Engineering Workshop Automobile Recycling
6 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Density (gravity separation) Mechanical sortation
processes for solid
waste:
Single sorting
(picking) by hand
Single sorting by
sorting machines
with detector and
ejector (use of
physical
properties)
Mass flow sorting
by means of
physical
properties
Sorting processes for solid waste – concentration (sortation) of materials
Magnetism (magnetic separation)
Conductivity (eddy current separation)
Polarisation (electrostatic separation)
Friction (gravity separation)
Hardness (impact sorting)
Optical Properties (transmittance, ...)
…………………
Physical
properties
Geometrical Properties (circular, angular, ...)
Engineering Workshop Automobile Recycling
7 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Sorting processes for solid waste – Single sorting (picking by hand)
During manual sorting
employees are standing at a
convyor belt and sort out
the materials from the
material flow.
The eye is the detector and
the hands are the deflector
unit (ejector).
For the testing of materials,
the staff have tools, like
magnets, knives and files.
Engineering Workshop Automobile Recycling
8 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Sorting processes for solid waste – Single sorting by sorting machines
Detector
Ejector
Picking
Indentification
Controll
system
Activation Analysis
Metals: activation with x-ray, laser
Plastics: activation with infra-red beam
In the laser spectroscopy and X-ray
fluorescence analysis, the
materials are stimulated first and
the excitation signal is measured.
Through a unit of analysis the
ejctor is controlled and the material
flow is sorted herewith.
Engineering Workshop Automobile Recycling
9 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Sorting processes for solid waste – Single sorting by sorting machines
Electronics
Conveyor belt
Detector
Air
Air ejection
devise
Other
materials
Aluminium and
aluminium contained
parts
Aluminium sorting device
The aluminum parts slide
down on a strip and pass
through a detector coil.
The magnetic field is
disturbed by the coil and a
signal is sent through the
electronics to a
compressed air nozzle.
The aluminum parts are
blown into a sorting box.
Engineering Workshop Automobile Recycling
10 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Sorting processes for solid waste – Density (gravity separation)
Wet graphity separation works
according to the Archimedean
principle.
The impetus force of the
particles depends on the
density of the material.
Mixed plastics
types A and B
Material with
lower density
then separation
liquid, type A
Material with
higher density
then separation
liquid, type B separation liquid
Examples for densities
LDPE 0,92 g/cm3
HDPE 0,96 g/cm3
PP 0,91 g/cm3
PA 1,05 g/cm3
PS 1,13 g/cm3
PMMA 1,18 g/cm3
PVC 1,39 g/cm3
Engineering Workshop Automobile Recycling
11 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Separation of layer composites by dissolution
Layer
composite with
3 polymers
Solvent Solvent
Layer
composite with
3 polymers
Solvent with
polymers Solvent with
polymer 3
Solvent
Layer
composite with
3 polymers
Solvent and
polymers 1, 2, 3
Summativ dissolution Selectiv dissolution Delamination
For the separation of the layer-composites dissulution or delamination can be applied.
In dissulution the plastic mixture is dissolved in a solvent (summative-dissulution) or just one plastic
component is dissolved in a solvent (selective-dissulution).
A separation can then be performed by filtering of plastics and solvents.
Delamination dissolves only the interfacial of the multi-layers.
Engineering Workshop Automobile Recycling
12 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Example for delamination: Preparation of instrument panel
PUR foam
PVC skin
Pre shredding
Delamination
Separation Cutting
PP
Cutting Extrusion
Production
new parts
Magnetic separation
Production
residues
Instrument
panels from
Elv`s
Magnetic separation
Magnetic separation
Magnetic separation
An instrument panel is in most cases, a
three-layer composite of PP, PVC and
PUR.
For a separation of the materials the
interfaces are to be dissolved by
delamination.
In principle, all three materials could be
recovered in this process. In practice,
only the PP is used for new applications.
PVC skin and PUR foam are supplied to
an energy-recovery process.
Engineering Workshop Automobile Recycling
13 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of metallic materials – Steel recycling
Oxygen converter Ore Casting
Steel scrap
Blast furnace Forming/Rolling
20 mass-%
Steel is produced from ore, with the help of coke, oil, or shredder granules in blust furnace to reduce raw iron.
The raw iron is very brittle, and therefore the impurities must be removed. This is done in an oxygen converter. There, oxygen is blown on the steel melt and the impurities go into the slag or into the exhaust.
To cool the molten steel, about 20% steel scrap is add.
Engineering Workshop Automobile Recycling
14 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of metallic materials – Steel recycling
Electric arc furnace Steel scrap Steel
Zinc dust
Casting
100 mass-%
The second way is the direct melting of steel scrap in an electric arc furnace.
Between carbon electrodes and electric arc, melts the material. By adding of alloying
elements, the quality of the steel can be adjusted.
Today, all systems are provided with exhaust-cleaning systems. Thus, zinc dust from
surface-coated steel sheets can be regained.
Engineering Workshop Automobile Recycling
15 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of aluminium
Melting electrolysis Bauxite Casting/Alloying Forming/Rolling
Bayer
process
(chemical
process)
Primary aluminum is extracted from bauxite ore.
In the first step, all chemical contaminants are to be removed through a relatively
complicated process. The resulting alumina is then of a white powder.
Since the affinity of aluminum for oxygen is very high, a reduction with help of a
glaze flow- electrolysis must be conducted.
Engineering Workshop Automobile Recycling
16 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of aluminium
Furnace Aluminium scrap Casting Raffination
With the recycling of aluminum, the material is melted in a furnace. Depending on the
scrap type a variety of furnaces are available.
For the collection of impurities, the melt is covered with a molten salt. The molten salt
can also be recycled.
A newer procedure is the "spin nozzle" inert gas process. Agon is pressed by jets into
the melt and helps to float to the impurities.
Engineering Workshop Automobile Recycling
17 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Melting
furnace
Furnace Die casting
Dosing pump Pipe
Purifying system
Recycling of magnesium
Magnesium scrap
Processing/
cutting
The recycling of magnesium is limited mainly to post-production
and post-industrial material.
The material is melted in an electrically heated furnace, transported
through a pipe to a holding furnace and then fed to a die-casting
machine. A ceramic filter system is used for cleaning the material.
The whole process is under a protective gas.
Engineering Workshop Automobile Recycling
18 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of lead at the example of batteries
Used batteries Acid H2SO4
Shredder
Lead alloys
Furnace
Separation
Polypropylene
Refining/
Alloying
Lead sluge
Clean used lead
Starter batteries are first
shredded and the acid is
collected and reprocessed for
reuse.
The PP is removed from the
material flow by using a float-
sink separation.
The remaining lead is melted in a
furnace and refined.
Engineering Workshop Automobile Recycling
19 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of thermoplasts
Temperature behaviour of the E-modulus (PA)
Application
(elastic)
Processing
(plastically fluent )
Decomposition
(oil, gas)
At low temperatures the material
behaves elastically.
With increasing temperature, the
polymer chains can slide freely against
each other and the material behaves
plastically.
This is the processing temperature of
the material in an extruder or an
injection molding machine. This process
can be repeated.
Thermoplast with carbon-hydrogen polymer chains (PP, PE, ABS, PA,..)
Engineering Workshop Automobile Recycling
20 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of thermoplasts
In the extrusion, the material is plasticized and
kneaded.
New material as well as stabilizers, softeners
and addetives are added.
At the end the quality-granuale is ready.
PP new
material
Stabilizers , softeners,
additives, ...
Extrusion Regranulat
Moulding
injection
Sieving
Engineering Workshop Automobile Recycling
21 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of duromers (thermosets)
Thermoset with polymer chains. Here are also
strong bonds crosswise to the chains (Phenol-/
melamine formaldehyde, PUR (especially as foam in
the car)).
Decomposition
(oil, gas)
brittle
tough
Temperature behavior of the E-modulus (epoxy
resin)
Thermosets are formed from mixtures of resins
and curing agents, which are irreversibly
connected to each other. Therefore, re-melting
is not possible.
This also shows the temperature dependence
of the E-modulus. The material crystallizes
when heated and turns into an oily or gassy
phase.
Engineering Workshop Automobile Recycling
22 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of glass-fibre reinforced thermosets
Glas-fibre
reinforced
duromers
(thermosets)
Bumpers and other
parts
Pre-shredding
Metal separation
2-stage sifting
Sieving
Classification
Regranulat
Fibres
In most cases, thermosets are filled with glass fibers,
carbon fibers or aramid fibers.
The recovery of the fibers is priority in the recycling
processes. This material is repeatedly shredded and
screened.
At the end glass fibers are available that can be fed back
into the production process in principle.
Engineering Workshop Automobile Recycling
23 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of elastomers
Elastomer (rubber) with polymer chains.
Also weak crossed bonds to the chains.
Example: Styrene butadiene india rubber , NBR
Elastomers are made of rubber (nature india
rubber).
This rubber is vulcanized, which means it
builds up sulfur bridges, and thus the
material is irreversibly linked.
A melting like thermoplastics is not
possible.
In addition, the elastomer material usually
occurs as a composite in automobiles
(tyres, rubber seals).
Engineering Workshop Automobile Recycling
24 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of elastomers
Tires
(composite
rubber / steel)
Pre-shredding
Milling
Metal separation
Re-milling
Wind-sifter /
cyclone
Classification
Pulverized rubber
Rubber granulate
Rubber-
thermoplast
composites /
rubber-
thermoset
composites
The process starts with the separation of rubber and steel by means of a
shredder process (warm grinding process or Kryogen grinding process
under liquid nitrogen).
After the process rubber pieces or rubber powder is available.
Rubber powder is proportionally reallocated to the production of tires.
Rubber pieces can be processed as filler into new moldings with
thermoplastics or thermosets.
Engineering Workshop Automobile Recycling
25 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of elastomers – Playground (Orlando/USA)
The figure shows a Playground in Orlando
(USA). Shredded tires have been designed
as a safety latch.
Emanations arise in great heat.
Engineering Workshop Automobile Recycling
26 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Recycling of catalysts
Cr steel, CrNi
steel
Ceramic /
metal with
washcoat
Spring mat /
metal mesh
Noble
metals from
dust
Catalyst Decanning The catalyst consists of the
ceramic body, a source pad
and the catalyst housing.
On the ceramic body the
wash coat is applied, in
which the noble metals
platinum and rhodium can
be found.
The mat is made of a metal
or ceramic fiber.
The housing consists of a
high alloy chrome steel or
stainless steel.
First the exhaust system is
cut out of the vehicle with
cutter. Subsequently, the
catalyst is opened via mill.
The noble metals are won
back about a metallurgical
process from the
waschcoad.
Engineering Workshop Automobile Recycling
27 Prof. Dr.-Ing. Joachim Schmidt, Faculty of Vehicle Engineering
Mechanical processing of circuit boards
Polymer-
mixed
granules
Ferrous materials
Pollutants
(batteries, displays,
...)
Circuit board
Dismantling
Pre-shreddering
Magnetic sorting
Cutting
Classifying and sorting Copper plants
(50 % metals, copper content 20 %)
Copper-rich mixed metal granules Copper and
noble metals
from
electrolyses
If batteries, displays or other types
of contaminated components are on
the board, they must be dismantled
first.
Subsequently, the material is pre-
shredded and the ferrous metals
sorted out. A shredding reduces the
material size further. The result is a
mixture of plastic, ceramic and
metal, that is to be classified and
separated.
The final results are copper-rich
metal pellets and a polymer mixture.
The copper metal granule contain
about 20% copper and is sold on to
copper smelters.
