Sawdust

Wood flour and sawdust do not melt but rather decompose above 190°C. This is, again, due to a more susceptible to temperature lignin and hemicellulosics, and because pure cellulose decomposes above 240°C. 

Sawdust is essentially the same thing as wood flour except it is not ground but formed as a by-product of wood sawing. Sawdust typically consists of particles of 30-600 pm and larger in size. Sometimes sawdust is classified as particles of 20 pm-5 mm (5000 pm). Cost of wood flour and sawdust is typically of 6-8 0/lb, but it can vary depending on local conditions. 

Rice hulls are by-products of rice mills, where lighter rice hulls are separated from more heavy husked rice through aspiration. In some rice mills, hulls are ground and sold according to their sizes. 

Becanse rice hulls make about 20% of rough harvested weight of rice, rice mills across the United States, from California to Florida, with Arkansas, Missouri, Louisiana, and Texas in between, produce large amounts of rice hulls, namely more than 

5 billion pounds (1.25 million metric tons) a year. One of them is Riceland Foods, or Rice Hull Specialty Products (Stuttgart, AR), the world s largest miller of rice and a major supplier of milled rice hulls. Rice hulls are often sold for about 40/ton (2 cents a pound), though cost and availability generally vary from producer to producer. 

Explosive emulsions are minute droplets of ammonium nitrate solution emulsified to the texture of margarine in a fuel (often diesel). Because the ammonium nitrate remains in solution, it is not an explosive and maintains an inherent high degree of safety during transportation. Emulsions are sensitized just prior to use by the introduction of gas bubbles or glass microballoons which create voids around which ammonium nitrate solidifies (the explosive form). Initiation is caused by the shockwave of a high explosive detonator. 

Aromatic, see Terminology, Organic, p.244 By Mass, see Terminology, By Mass, p.232 Components, explosive train, n.o.s., see Initiating Explosives, p. 119 Desensitized, see Terminology, Desensitized, 

Small arms, see Ammunition, p.8 Solid, see Terminology, Solid, p.247 Wetted, see Terminology, Wetted, p.253 

see Terminology, Metals, p.242 Mixture, see Terminology, Mixture, p.243 Propellant, liquid, see Ammunition, p.8 Propellant, solid, see Ammunition, p.8 Salts, see Terminology, Salts, p.247 Samples, explosive other than initiating 

Class 1 comprises (a) Explosive substances (a substance which is not itself an explosive but which can form an explosive atmosphere of gas, vapour or dust is not included in Class 1), except those that are too dangerous to transport or those where the predominant hazard is appropriate to another class (b) Explosive articles, except devices containing explosive substances in such quantity or of such a character that their inadvertent or accidental ignition or initiation during transport shall not cause any effect external to the device either by projection, fire, smoke, heat or loud noise and (c) Substances and articles not mentioned under (a) and (b) which are manufactured with a view to producing a practical, explosive or pyrotechnic effect. UN 2.1.1.1, ICAO 2-1.1.1 

---

Furfural was first isolated in the eady nineteenth century. Dobereiner is credited with the discovery. He obtained a small amount of a yellow "oil" (too Htde to characterize) as a by-product in the preparation of formic acid (8). Other chemists found that the same "oil" having a charactedstic aroma could be obtained by boiling finely divided vegetable materials such as oats, com, sawdust, bran, etc, with aqueous sulfuric acid or other acids (9,10). The oil was present in the Hquid resulting from condensation of the vapors produced during heating. The empirical formula was determined by Stenhouse... 

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. 

Oxidizing Properties. Nitric acid is a powerful oxidizing agent (electron acceptor) that reacts violentiy with many organic materials (eg, turpentine, charcoal, and charred sawdust) (19,20). The concentrated acid may react explosively with ethanol (qv). Such oxidizing properties have had military appHcation nitric acid is used with certain organics, eg, furfuryl alcohol and aniline, as rocket propellant (see Explosives AND PROPELLANTS). 

The wide range of types of paper products results in a variety of sludges. SoHd wastes result from several sources within the mill, eg, bark, sawdust, dirt, knots, pulpwood rejects, flyash, cinders, slag, and sludges. Sludges often are disposed of in combination with residuals from other sources. Approximately 300 kg of soHd waste per ton of finished product is generated by the pulp and paper industry. 

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. 

Amino resins are manufactured throughout the industrialized world to provide a wide variety of useful products. Adhesives (qv), representing the largest single market, are used to make plywood, chipboard, and sawdust board. Other types are used to make laminated wood beams, parquet flooring, and for furniture assembly (see Wood-BASED composites and laminates). 

Wood Residuals. Chips, sawdust, and other residuals such as planar shavings are used as a primary source of fiber for some pulp mills. Chips are screened and placed in a purchased chip pile. Sawdust and other residuals obtained from wood processing plants must be cooked separately and requite special digesters and handling equipment. These materials may also be burned as hog fuel. 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

Other. Vinyl acetate resins are useful as antishrinking agents for glass fiber-reinforced polyester mol ding resins (165). Poly(vinyl acetate)s are also used as binders for numerous materials, eg, fibers, leather (qv), asbestos, sawdust, sand, clay, etc, to form compositions that can be shaped with heat and pressure. Joint cements, taping compounds, caulks, and fillers are other uses. 

Charcoal is produced commercially from primary wood-processing residues and low quaUty roundwood in either kilns or continuous furnaces. A kiln is used if the raw material is in the form of roundwood, sawmill slabs, or edgings. In the United States, most kilns are constmcted of poured concrete with a capacity of 40 to 100 cords of wood and operating on a 7- to 12-d cycle. Sawdust, shavings, or milled wood and bark are converted to charcoal in a continuous multiple-hearth furnace commonly referred to as a Herreshoff furnace. The capacity is usually at least 1 ton of charcoal per hour. The yield is - 25% by weight on a dry basis. 

One of the most promising substrates for future production of microbial biomass is the ceUulose contained in agricultural residues such as wood pulp, sawdust, feed-lot waste, com stover, rice huUs, nut sheUs, and bagasse, aU of which contain ceUulose as the principal carbon source. CeUulose contents range from 90% in cotton to 15—20% in dicotyledon leaves. Wood residues and grasses contain mixtures of ceUulose, hemiceUulose, and lignin. The major... 

Screw presses (Fig. 2) do not produce a clear liquid product. Frequendy, the product is further filtered in a filter press to give a clear Hquid product. Press aids are added to feed materials containing fine particles or particles that can deform and plug the slots in the edge of a screw press. Typical press aids include sawdust, rice hulls, perlite, and diatomaceous earth (see Diatomite). A vertical screw press is a continuous press that has been used for dewatering sewage sludge (2). 

A number of papers have appeared on the removal of heavy metals in the effluents of dyestuff and textile mill plants. The methods used were coagulation (320—324), polymeric adsorption (325), ultrafiltration (326,327), carbon adsorption (328,329), electrochemical (330), and incineration and landfiU (331). Of interest is the removal of these heavy metals, especiaUy copper by chelation using trimercaptotria2ine (332) and reactive dyed jute or sawdust (333). 

Its appeal Hes in the fact that synthesis gas can be produced from trash, municipal sewage, scrap wood, sawdust, newsprint, or other waste. The early work of Fischer and Tropsch on methanol synthesis showed that ethanol could be obtained in the process (165) and that by certain modifications the proportion of ethanol in the product could be increased (166). The Hterature concerning this method is extensive (167—176). The conditions that favor ethanol formation are 125—175°C and 1.42 MPa (14 atm) in the presence of reduction catalysts such as powdered iron. 

Cellulose acetate Silica gel Scoured wool Sawdust Rayon waste Fluorspar Tapioca Breakfast food Asbestos fiber Cotton linters Rayon staple Starch Aluminum hydrate Kaolin Cryolite Lead arsenate Cornstarch Cellulose acetate Dye intermediates Calcium carbonate White lead Lithopone Titanium dioxide Magnesium carbonate Aluminum stearate Zinc stearate Lithopone Zinc yellow Calcium carbonate Magnesium carbonate Soap flakes Soda ash Cornstarch Synthetic rubber... 

Flood and Kernel, Chem. Proc. (Sept. 8, 1973)]. Miscellaneous uses include the incineration of sawdust, carbon-black waste, pharmaceutical waste, grease from domestic sewage, spent coffee grounds, and domestic garbage. 

Coal, bituminous, mined, slack, V4 in and under 50 C36P Sawdust 10-13 5... 

Lumber and wood products Sawmills, millwork plants, wooden containers, miscellaneous wood products, manufacturing Scrap wood, shavings, sawdust in some instances, metals, plastics, fibers, glues, sealers, paints, solvents... 

Wood-fired power boilers are generally found at the mills where wood products are manufactured. They are fired with waste materials from the process, such as "hogged wood," sander dust, sawdust, bark, or process trim. Little information is available on gaseous emissions from wood-fired boilers, but extensive tests of particulate matter emissions are reported (19). These emissions range from 0.057 to 1.626 gm per dry standard cubic meter, with an average of 0.343 reported for 135 tests. Collection devices for particulate matter from wood-fired boilers are shown in Table 30-21. 

Woodflour, a fine sawdust preferably obtained from softwoods such as pine, spruce and poplar, is the most commonly used filler. Somewhat fibrous in nature, it is not only an effective diluent for the resin to reduce exotheim and shrinkage, but it is also cheap and improves the impact strength of the mouldings. There is a good adhesion between phenol-formaldehyde resin and the woodflour and it is possible that some chemical bonding may occur. 

---