# US 4,394,166 A · Scrap metal recovery process

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- Number: US 4,394,166 A
- Document ID: US4394166A
- Status: Granted
- Kind: A
- Application number: 06/382,880
- Filed: 1982-05-28
- Granted: 1983-07-19
- Earliest claimed: 1982-05-28
- Assignees: The William L. Bonnell Company
- Inventors: James A. Kennedy
- Web page: https://patentgrep.com/patent/US4394166A

## CPC

- B03B 9/061: {the refuse being industrial}
- C22B 21/0007: {Preliminary treatment of ores or scrap or any other metal source (Bayer processes C01F)}
- Y02W 30/20: Waste processing or separation
- Y02W 30/52: Mechanical processing of waste for the recovery of materials, e.g. crushing, shredding, separation or disassembly
- B03B: SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

A method for recycling aluminum scrap containing thermal barrier material comprising the steps of comminuting the scrap to short pieces of a predetermined length, conveying the comminuted aluminum scrap to a storage hopper, continuously feeding comminuted aluminum scrap product to an indirect-fired rotary kiln, heating the scrap to a predetermined temperature for a sufficient amount of time to reduce the thermal barrier material in the scrap to combustible gas and cinder and produce a satisfactory aluminum melt furnace feed product, collecting and burning the combustible gases and vapors in a waste heat recovery afterburner to provide sufficient heating values for the scrap heating step, and then feeding the treated scrap to an aluminum melt furnace for melting and further processing.

## Claims

### Claim 1

Method for recycling aluminum scrap containing thermal barrier material, said method comprising the steps of:
(a) comminuting said scrap to pieces from about 18 to about 4 inches in length thereby preparing a relatively uniformly sized aluminum scrap product;
(b) conveying said comminuted aluminum scrap product to a storage hopper;
(c) continuously feeding the comminuted aluminum scrap product from said storage hopper to an indirect-fired rotary kiln;
(d) heating said scrap product in said indirect-fired rotary kiln to a temperature of about 800.degree. to 900.degree. F. for a period of about one-half to one hour thereby substantially completely removing said thermal barrier material as combustible gas and cinder producing a satisfactory aluminum melt furnace feed product;
(e) collecting and burning said combustible gases and smoke in a waste heat recovery afterburner to provide heating values for said step (d);
(f) transferring heating values provided in step (e) to said indirect-fired rotary kiln; and,
(g) feeding said feed product from said indirect-fired rotary kiln to an aluminum melt furnace for melting.

### Claim 2 (depends on 1)

The method of claim 1, wherein said aluminum scrap contains from about one to about ten weight percent of said thermal barrier material.

### Claim 3 (depends on 1)

The method of claim 1, wherein said aluminum scrap is comminuted to lengths from about 12 to about 15 inches in length.

### Claim 4 (depends on 1)

The method of claim 1, wherein said comminution of step (a) is carried out intermittently.

### Claim 5 (depends on 1)

The method of claim 1, wherein said comminuted aluminum scrap product is fed to said indirect-fired rotary kiln concurrently with the feeding of the heating values from said afterburner of said step (e).

### Claim 6 (depends on 1)

The method of claim 1, wherein said thermal barrier material in said aluminum scrap is selected from rigid polyvinyl chloride or polyurethane materials.

### Claim 7 (depends on 1)

The method of claim 1, wherein said thermal barrier material in said aluminum scrap is polystyrene.

### Claim 8 (depends on 1)

The method of claim 1, wherein said thermal barrier material in said aluminum scrap is plastic.

### Claim 9 (depends on 1)

The method of claim 1, wherein said aluminum scrap is covered with at least some oil, paint, thermal barrier material, or other foreign material.