Classifying – separating – and assorting solids – Precedent preparation of items or materials to facilitate... – Selective differentiation
Patent
1996-10-30
2000-06-06
Nguyen, Tuan N.
Classifying, separating, and assorting solids
Precedent preparation of items or materials to facilitate...
Selective differentiation
209 3, 209214, 241 2414, B03C 100, B02C 700
Patent
active
06070733&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to the treatment of waste materials, such as shredder waste (also called Shredderleichtraktion in German) or residues. This waste arises from the recycling of bulky metal scrap by fragmentising using, e.g. a hammer mill. The heavy metal scrap typically is automobile bodies, white goods, light iron, heavy steel, structural steel. The raw material is fed into the hammermill, initially shred, and cleaned magnetically and by eddy currents to produce ferrous and non-ferrous products on separate production lines.
About 75% of old cars are fed into shredder installations for recycling the materials. About 25% of the shredder charge remains as non-recoverable residues and is disposed of mainly in landfill sites. The shortage of landfill capacity has in recent years driven up the costs of properly disposing of these residues. This cost increase, together with the decline in profits, is increasingly resulting in a disposal crisis for the car recycling business. The difficult situation regarding disposal has already led to the closure of shredder plants. This results in a shortage for the steel industry of an important source of raw material for steel manufacture and like processes.
The shredder waste typically comprises metals, plastics, wood and rubber, and depending on the nature of the material being fragmented will also contain copper, aluminium and other elements derived from say stainless steel, and possibly silica.
SUMMARY OF THE INVENTION
It is an object of this invention to provide means for recovering as much as possible of the ingredients of the shredder waste for economic re-use. The waste material may be considered as a source of carbon, i.e. the plastics, wood and rubber, and of metals for the steel works, e.g. aluminium. The copper is of value in smelting or refining. More specifically, the invention provides a method to remove, or substantially reduce, the copper content and/or the SiO.sub.2 from glass or sand to provide a waste material containing the carbon sources and appropriate metals to be added to steel manufacturing furnaces without risk, and a copper enriched component which may be used in smelting or refining.
In one aspect, the invention provides a method of treating the light fraction of fragmented material, the method comprising fragmenting fragmentable material to provide a heavy fraction and a light fraction; characterised by reducing the size of the light fraction to particles of injectable size; mixing the particles with a magnetic substance to provide particles coated with the magnetic substance and particles which are not so coated; subjecting the mixture to magnetic separation; injecting the magnetised particles into the furnace.
One typical shredder waste has the following composition before separation of the heavy fraction (% by weight):
______________________________________ Fe (total)
25.4 Fe (2+) 2.74 Fe (met.)
3.86
SiO2 30.9 Al2O3 8.5 CaO 5.2
MgO 2.5 TiO2 1.36 P 0.13
Mn 0.21 Na 1.98 K 0.94
Cu 2.81 Pb 0.37 Zn 4.37
Cd <0.001 Cr 0.15 Ba 0.28
Ni 0.13 Mo <0.05 Co 0.015
Sn <0.05 As <0.01 Sb <0.1
V 0.006 C 0.13 S 0.83
Hg <0.00002
______________________________________
Depending on the source the fraction may contain plastic which has entrapped other materials by being subjected to heat and/or pressure. The metal bits must be released from a plastic cover before they can be teased out.
The shredder light fractions are heterogeneous mixtures of plastic, rubber, wood, textile residues, glass, iron and non-iron particles, plastic fibres and inert materials. The non metallic makes up about 25% of the total weight. There are variously sized `balls` of the fine plastic fibres, which enclose small particles of the above-mentioned materials. There are also small iron and non-iron particles in these balls, including copper in the form of small wires, partly in the shape of small rods, as well as in the form of minute pellets or tiny spirals. Some of these
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Heckert Multiserv PLC
Nguyen Tuan N.
Towner Alan G.
LandOfFree
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