Method and device for burning-off precious metal-containing materials

• US 8,188,329 B2
• Filed: 03/27/2008
• Issued: 05/29/2012
• Est. Priority Date: 09/27/2005
• Status: Active Grant

• Current Assignee: Heraeus Deutschland GmbH & Co. KG (Heraeus Holding GMBH)
• Original Assignee: Heraeus Precious Metals GmbH & Co. KG (Einhorn Verwaltungsgesellschaft mbH)
• Inventors: Nowottny, Christian, Meyer, Horst, Grehl, Matthias, Schäfer, Dieter, Alt, Hans-Joachim, Glab, Wilhelm
• Primary Examiner(s): Lorengo, Jerry
• Assistant Examiner(s): SMITH, JENNIFER A
• Application Number:
  US12/056,524
• Publication Number:
  US 20080295749A1
• Time in Patent Office: 1,524 Days
• Field of Search: None
• US Class Current: 588/321
• CPC Class Codes: C22B 11/021 Recovery of noble metals from waste materials
• CPC Class Codes: C22B 7/001 Dry processes
• CPC Class Codes: F23G 2207/102 for pressure
• CPC Class Codes: F23G 2207/30 Oxidant supply
• CPC Class Codes: F23G 2208/10 Preventing or abating fire or explosion, e.g. by purging
• CPC Class Codes: F23G 2209/141 Explosive gases
• CPC Class Codes: F23G 5/0273 using indirect heating
• CPC Class Codes: F23G 5/16 in a separate combustion chamber
• CPC Class Codes: F23G 5/50 Control or safety arrangements
• CPC Class Codes: F23G 7/006 wires, cables production and refining of metals C22B, e.g. from scrap to produce non-ferrous metals C22B7/00; salvaging material from cables H01B15/003
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

A recycling furnace and method are provided for processing potentially explosive precious metal-containing materials having organic fractions that combust with great energy, the furnace including a switching facility for alternating operation of a burning-off chamber of the furnace between: (A) pyrolysis or carbonization under protective furnace gas in an atmosphere comprising maximally 6 wt-% oxygen, and (B) oxidative combustion of the organic fractions including carbon. The furnace has indirect heating and a control that determines the end of the pyrolysis or carbonization by a sensor and controls the switching facility to supply air or oxygen to the interior of the furnace. Steps (A) and (B) are carried out sequentially in the furnace chamber, wherein neither the batch is changed, nor the furnace is opened. After the end of step (A) is determined, step (B) proceeds right after the pyrolysis or carbonization by supplying air or oxygen. A dosing of liquid or liquefied substances during the pyrolysis is controlled by at least one parameter of post-combustion. Thermal post-combustion is used for two furnace chambers, one operated for pyrolysis or carbonization and the other operated as a combustion chamber.

Claims

1. A method for recycling potentially explosive precious metal-containing materials having organic fractions that combust with great energy, the method comprising the steps:

(A) pyrolyzing or carbonizing the materials under reduced oxygen supply, and (B) oxidatively combusting the organic fractions, wherein steps (A) and (B) are carried out sequentially in an indirectly heated furnace chamber, such that a batch in the chamber is not changed and the furnace is not opened, wherein step (A) comprises establishing an oxygen-depleted atmosphere containing maximally 6 wt-% oxygen in the interior of the chamber by making it inert with protective furnace gas, and determining an end point of the pyrolysis or carbonization, wherein step (B) proceeds right after the pyrolysis or carbonization by supplying air or by supplying oxygen to the chamber, wherein the method is carried out in batch operation in first and second chambers, wherein step (A) is carried out on a first batch of material in the first chamber while a second batch of material is supplied to the second chamber, then step (B) is carried out for the first batch in the first chamber while step (A) for the second batch proceeds in the second chamber, and while a switch to step (B) is made in the second chamber, the first chamber is again supplied with material for step (A) and wherein the first and second chambers are operated in alternating operation with a single thermal after-combustion.

2. The method according to claim 1, wherein precious metal contents of at least 0.001 wt-% are present in the materials.

3. The method according to claim 1, wherein a supply of materials for step (A) proceeds slowly and continuously rather than batch-wise.

4. The method according to claim 1, wherein, in steps (A) and (B), precious metal fractions and ash are received in capture troughs arranged underneath a combustion goods supply or a pyrolysis goods supply.

5. The method according to claim 1, wherein step (A) is carried out at a temperature of 200 to 800°

C.

6. The method according to claim 1, wherein step (B) is carried out at a temperature of 600 to 1200°

C.

7. The method according to claim 1, further comprising dosing liquid or liquefied materials during the pyrolysis, and controlling the dosing by at least one parameter of post-combustion.

8. The method according to claim 7, wherein the dosing is controlled by a temperature sensor.