US3826433A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for removing bark from wood chips
Assignee: United States Department of Agriculture
•
Filing: 1973-06-01
•
Granted: 1974-07-30
•
Expires: 1993-06-01
Abstract
Abstract A process to remove the bark from wood chips by breaking the bond between the bark and wood fractions followed by segregation of the bark particles from the clean wood chips. The process includes the steps of: steaming the wood chip mass to weaken the bark-wood bond and render the bark tacky; mechanically compressing the chips to partially break the bond between the bark and wood and to break a portion of the bark fraction into smaller particles; removing these particles, some of which adhere to the compressing medium, from further processing; subjecting the partially beneficiated chips to unique abrasion or milling processes to fragmentize the remaining bark; and segregating the resulting clean wood chips from the fragmented bark. The sequence of steps may be varied and the bark is removed from processing at different stages.
Inventors
- 👤 J Erickson
- 👤 W Hillstrom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:52
CPC Classifications
D; D21; D21B; D21B1/00; D21B1/02; D21B1/023
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
116 words
A process for removing the bark from wood chips in an unbarked wood chip mass, comprising the steps of: a. steaming said chips at a low pressure to render the bark fraction tacky and weaken the wood-bark bond, b. mechanically compressing said chips between two closely opposed, oppositely rotating surfaces to crush and partially break said bark fracTion into smaller particles, a portion of said particles adhering to said rotating surfaces, c. removing said broken bark by 1. scraping said adhering particles from said rotating surfaces, and 2. screening the remaining particles from the chips, d. abrading said chips to fragmentize any remaining bark, and e. segregating said fragmentized bark from the resulting clean wood chips.
Claim 2
Dependent Claim
116 words
A process for removing the bark from wood chips in an unbarked wood chip mass, comprising the steps of: a. steaming said chips at a low pressure to render the bark fraction tacky and weaken the wood-bark bond, b. mechanically compressing said chips between two closely opposed, oppositely rotating surfaces to crush and partially break said bark fracTion into smaller particles, a portion of said particles adhering to said rotating surfaces, c. removing said broken bark by 1. scraping said adhering particles from said rotating surfaces, and 2. screening the remaining particles from the chips, d. abrading said chips to fragmentize any remaining bark, and e. segregating said fragmentized bark from the resulting clean wood chips.
Claim 3
Dependent Claim
29 words
The process of claim 1 wherein said chips are steamed for a period of from a few seconds to 15 minutes at pressures of from 0 to 50 p.s.i.g.
Claim 4
Dependent Claim
28 words
screening the remaining particles from the chips, d. abrading said chips to fragmentize any remaining bark, and e. segregating said fragmentized bark from the resulting clean wood chips.
Claim 5
Dependent Claim
28 words
screening the remaining particles from the chips, d. abrading said chips to fragmentize any remaining bark, and e. segregating said fragmentized bark from the resulting clean wood chips.
Claim 6
Dependent Claim
41 words
oscillating one of said moving surfaces in a direction transverse to its continuously moving direction to fragmentize any remaining bark as said chips are transported through said process zone, and c. segregating said fragmentized bark from the resulting clean wood chips.
Claim 7
Dependent Claim
41 words
oscillating one of said moving surfaces in a direction transverse to its continuously moving direction to fragmentize any remaining bark as said chips are transported through said process zone, and c. segregating said fragmentized bark from the resulting clean wood chips.
Claim 8
Dependent Claim
13 words
The process of claim 1 wherein said chips are abraded by mechanical milling.
Claim 9
Dependent Claim
35 words
The process of claim 1 wherein said chips are abraded by being transported between two continuously moving, substantially parallel surfaces, one of said surfaces being oscillated in a direction transverse to its continuously moving direction.
Claim 10
Dependent Claim
110 words
The process of claim 4 wherein said chips are abraded by a. directing them into a process zone formed between two continuously moving, substantially parallel surfaces, each of said surfaces moving in opposite directions so as to converge toward one another at one end and away from one another at the opposite end of said process zone, said surfaces being so disposed to one another as to catch and hold said chips and transport them through said process zone, and b. oscillating one of said moving surfaces in a direction transverse to its continuously moving direction to fragmentize any remaining bark as said chips are transported through said process zone.
Claim 11
Dependent Claim
109 words
In a process for removing the bark from wood chips in an unbarked wood chip mass utilizing mechanical compression of the wood chips between two moving surfaces to crush the bark, and including separation of the crushed bark from the wood, the combination with said mechanical compression and separation of the following steps: a. steaming said chips at a low pressure to render the bark fraction tacky and weaken the wood-bark bond prior to said mechanical compression and separation, b. abrading said chips, following said mechanical compression and separation, by mechanical milling to fragmentize any remaining bark, and c. segregating said fragmentized bark from the resulting clean wood chips.
Claim 12
Dependent Claim
109 words
In a process for removing the bark from wood chips in an unbarked wood chip mass utilizing mechanical compression of the wood chips between two moving surfaces to crush the bark, and including separation of the crushed bark from the wood, the combination with said mechanical compression and separation of the following steps: a. steaming said chips at a low pressure to render the bark fraction tacky and weaken the wood-bark bond prior to said mechanical compression and separation, b. abrading said chips, following said mechanical compression and separation, by mechanical milling to fragmentize any remaining bark, and c. segregating said fragmentized bark from the resulting clean wood chips.
Claim 13
Dependent Claim
29 words
The process of claim 6 wherein said chips are steamed for a period of from a few seconds to 15 minutes at pressures of from 0 to 50 p.s.i.g.
Claim 14
Dependent Claim
90 words
In a process for removing the bark from wood chips in an unbarked wood chip mass utilizing mechanical compression of the wood chips between two moving surfaces to crush the bark, and including separation of the crushed bark from the wood, the combination with said mechanical compression and separation of the following steps: a. steaming said chips at a low pressure to render the bark fraction tacky and weaken the wood-bark bond prior to said mechanical compression and separation, b. abrading said chips, following said mechanical compression and separation, by
Claim 15
Dependent Claim
90 words
In a process for removing the bark from wood chips in an unbarked wood chip mass utilizing mechanical compression of the wood chips between two moving surfaces to crush the bark, and including separation of the crushed bark from the wood, the combination with said mechanical compression and separation of the following steps: a. steaming said chips at a low pressure to render the bark fraction tacky and weaken the wood-bark bond prior to said mechanical compression and separation, b. abrading said chips, following said mechanical compression and separation, by
Claim 16
Dependent Claim
29 words
The process of claim 8 wherein said chips are steamed for a period of from a few seconds to 15 minutes at pressure of from 0 to 50 p.s.i.g.
Claim 17
Dependent Claim
19 words
The process of claim 8 wherein said two moving surfaces are heated to increase bark adherence during mechanical compression.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-29 | 1978-01-28 | 1978-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-29 | 1982-01-28 | 1982-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-29 | 1986-01-28 | 1986-07-30 | $7700.00 | Window Closed / Lapsed |