Wood chips

Dry-Process Hardboard. Dry-process hardboard is produced by a dry—dry system where dry fiber is formed iato mats, which are thea pressed ia a dry coaditioa. A flow diagram of this process is showa ia Figure 6. Ia this process, wood chips, sawdust, or other residues are refiaed to fiber ia pressurized refiners. Wax and PF resia may be added ia the refiner or ioimediately outside of the refiner, ia the fiber-ejectioa tube or "blowliae." It is also aoted that a small amouat of dry-process hardboard is made with UF resia biaders. UF resias, because of their inherent faster curing at lower temperatures, can be added only at the blowline or ia a bleader located after the dryer. 

Pressing. There are a variety of fmit presses. Some presses are more suitable for one type of fmit than for others, but most can be used for any fmit with varying degrees of success. Some presses requite the use of a press aid such as diatomaceous earth or wood chips. Total juice yield from the original fmit defines press efficiency. Additional yield can be obtained by adding a small amount of water to the press cake and pressing again. 

Direct hydrohquefaction of biomass or wastes can be achieved by direct hydrogenation of wood chips on treatment at 10,132 kPa and 340 to 350°C with water and Raney nickel catalyst (45). The wood is completely converted to an oily Hquid, methane, and other hydrocarbon gases. Batch reaction times of 4 hours give oil yields of about 35 wt % of the feed the oil contains about 12 wt % oxygen and has a heating value of about 37.2 MJ /kg (16,000 Btu/lb). Distillation yields a significant fraction that boils in the same range as diesel fuel and is completely miscible with it. 

Bois de Rose. Bois de rose oil is obtained by steam distillation of wood chips from South American rosewood trees, Aniba rosaeodora. The tree, a wild evergreen, grows mainly in the Amazon basin. The oil is used as obtained in perfumery for its sweet, woody-floral odor and as a source of linalool [78-70-6] (3), which it contains to the extent of 70%. Linalool distilled from bois de rose oil is also used directly in perfumery and for conversion to esters, eg, the acetate (1). 

Particle board and wood chip products have evolved from efforts to make profitable use of the large volumes of sawdust generated aimually. These products are used for floor undedayment and decorative laminates. Most particle board had been produced with urea—formaldehyde adhesive for interior use resin demand per board is high due to the high surface area requiring bonding. Nevertheless, substantial quantities of phenol—formaldehyde-bonded particle board are produced for water-resistant and low formaldehyde appHcations. 

From antiquity, glues had been made almost entirely from materials of animal or vegetable origin, and were sensitive to moisture, oxidation, and bacterial or fungus attack. Because of these deficiencies, production of durable plywood, for example, was not possible. The modern plywood industry actually owes its growth to the availabiUty of relatively low cost urea adhesives. Plywood and chipboard or wood chip glues are often made at the plywood and chip board mill. 

In gluing, the adhesive must not saturate veneers or wood chips, but must remain in the glue line on the surface of the chips or between the pHes. The adhesives are generally of high viscosity so that they remain in the glue line. Thickeners and extenders, such as powdered pecan shells and wheat flour, are often used. 

J. L. Minor and N. Sanyer, "Oxygen Pulpiag of Wood Chips with Sodium Carboaate," ia Ref. 55 J. P. Hansoa and S. I. KokoUch, "Semichemical Pulpiag With Na CO and NaOH Combiaations," ia Ref. 55. 

Also, EPRI is iavestigatiag whole-tree bum power plants that will dry and bum SRWC fuel without requiring tree trimming, wood chipping, or other fuel preparation. The concept iavolves the combustion of tree crops from farms distributed within a 40-km radius of a given plant. 

Another furnace that does not require fuel preparation is the stoker boiler, which was used by New York State Electric Gas Corporation (NYSEG) in its TDE tests. At NYSEG, the stoker boiler, which has a 1649°C (3000°E) flame temperature (as does the cyclone boiler), has routinely blended low quaUty coal, and more recently, wood chips with its standard coal to reduce fuel costs and improve combustion efficiency. In the tire-chip tests, NYSEG burned approximately 1100 t of tire chips (smaller than 5x5 cm) mixed with coal and monitored the emissions. The company determined that the emissions were similar to those from burning coal alone. In a second test-bum of 1900 t of TDE, magnetic separation equipment removed metal from the resulting ash, so that it could be recycled as a winter traction agent for roadways. 

In the wood rosin process, rosin is isolated from aged pine stumps that have been left in fields cleared for farming or lumbering operations. The stumps are cut and shredded to pieces the size of matchsticks. The wood chips are then extracted with an appropriate solvent, eg, aUphatic or aromatic petroleum hydrocarbons or ketones. The extract is fractionally separated into nonvolatile cmde rosin, volatile extractibles, and recovered solvent. The dark rosin is usually refined further to lighter-colored products using selective solvents or absorption. 

Tall oil rosin is a by-product of paper manufacturing. Raw wood chips are digested under heat and pressure with a mixture of sodium hydroxide and sodium sulfide. Soluble sodium salts of lignin, rosin, and fatty acids are formed, which are removed from the wood pulp as a dark solution. The soaps of the rosin and fatty acids float to the top of the mixture, where they are skimmed off and treated with sulfuric acid to free the rosin and fatty acids. This mixture, known as cmde tall oil (CTO), is refined further to remove color and odor bodies fractional distillation separates the tall oil rosin acids from the fatty acids (see Tall oil). 

Typical raw material mix to produce one metric ton of silicon consists of 2500—3000 kg quartz, 1200—1400 kg of low ashcoal and/or charcoal, and 1500—3000 kg wood chips. From 11 to 14 MWh of electrical power, and prebaked carbon electrodes of 90—140 kg, are consumed. 

The principle uses of Na2S04 are in the manufacture of paper, soaps, and detergents. These accounted for 65% of U.S. consumption from 1990 to 1995, representing a significant shift from 1980 when paper production alone consumed 67%. Pulp (qv) and paper consume only 25% (2). The kraft paper process uses a mixture of sodium sulfide and sodium hydroxide to digest wood chips. Both the sulfide and hydroxide are generated, starting with sodium sulfate as the raw material. 

Wood Delignijication. The production of wood pulp (qv) for the paper (qv) industry consists of removing lignin (qv) from wood chips, thus freeing the ceUulose fibers. An aqueous solution containing 30—70 wt % sulfolane efficiently extracts the lignin from aspen. Western hemlock, and Southern pine wood chips. Pulp yields are from 50—75% (43,44). 

Miscellaneous uses for sodium cyanide include heat treating, metal stripping, and compounds used for clearing smut. Treatment of wood chips with sodium cyanide and CaCl2 reportedly increases the kraft cooking yield of pulp (qv) (64). 

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