Method of reconditioning used wood

• US 5,882,427 A
• Filed: 02/02/1998
• Issued: 03/16/1999
• Est. Priority Date: 06/04/1996
• Status: Expired due to Fees

• Current Assignee: Fraunhofer-Gesellschaftzur Foerderung Der Angewandten Forschung E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Boehme, Christian, Michanickl, Andreas
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): CHAUDHRY, SAEED T
• Application Number:
  US08/973,111
• Time in Patent Office: 407 Days
• Field of Search: 134/6, 134/26, 134/27, 134/28, 134/29, 134/30, 134/34, 162/1, 162/63, 162/65, 162/81, 162/82, 162/70
• US Class Current: 134/6
• CPC Class Codes: B26F 3/004 by means of a fluid jet methods for use of abrasive blasting for cutting B24C1/045; guns for abrasive fluid jets B24C5/02; perforating by non-mechanical means, e.g. by fluid jet B26F1/26
• CPC Class Codes: B27L 11/007 Combined with manufacturing a workpiece
• CPC Class Codes: B27M 1/003 Mechanical surface treatment

Abstract

Method of separating the surface layer from the core of a piece of wood isescribed. In it, the surface of the piece of wood is initially pre-damaged or roughened and the piece of wood thus treated is thereafter soaked in water or an aqueous solution until the moisture of the wood in the surface layer is at least 30%. Thereafter, the piece of wood thus pre-treated is subjected to a steam process with steam at a temperature of 120 ° to 160 ° C. by which the surface layer to be removed is solubilized to an extent sufficient for removal from the piece of wood in a following step.

Claims

1. A method of reconditioning pieces of used wood carrying contaminants at its surface, comprising the steps of:

mechanically opening the surface structure of the wood;

soaking the wood in a fluid until the fluid in said surface structure amounts to at least 30%;

subjecting the wood to steam of a temperature between 120° and

160°

C. thereby to solubilize said surface structure; and

removing said solubilized surface structure.

2. The method of claim 1, wherein said wood is soaked in water.

3. The method of claim 2, wherein said wood is soaked in water containing an aggressive substance.

4. The method of claim 3, wherein said aggressive substance is from the group including nitric acid, sulfuric acid, potassium nitrate and sodium hydroxide.

5. The method of claim 1, wherein said surface of said wood is treated by a wood preservative and said fluid contains a complexing agent to insolubilize said wood preservative.

6. The method of claim 1, wherein an aggressive substance is added to said steam.

7. The method of claim 6, wherein said aggressive substance is from the group including ammonia and ozone.

8. The method of claim 1, wherein said steam is applied at no less than pressure.

9. The method of claim 1, wherein said surface is opened by at least one of incising, toothed rollers, knife rollers and drum rotors.

10. The method of claim 1, herein said fluid is at a temperature of between 60°

and 100°

C.

11. The method of claim 1, wherein said solubilized surface is removed by high pressure water jets.

12. The method of claim 11, wherein said high pressure water jets are directed against said surface at an angle between 85°

and 90°

.

13. The method of claim 11, wherein prior to said removal by high pressure water jets said solubilized surface is subjected to a mechanical removal step.

14. The method of claim 13, wherein said mechanical removal step includes at least one of wire brushing and sand blasting.

15. The method of claim 1, wherein said wood is cut up into chips following removal of said surface.