Briquette Properties

DRI can be produced in pellet, lump, or briquette form. When produced in pellets or lumps, DRI retains the shape and form of the iron oxide material fed to the DR process. The removal of oxygen from the iron oxide during direct reduction leaves voids, giving the DRI a spongy appearance when viewed through a microscope. Thus, DRI in these forms tends to have lower apparent density, greater porosity, and more specific surface area than iron ore. In the hot briquetted form it is known as hot briquetted iron (HBI). Typical physical properties of DRI forms are shown in Table 1. 

Modern charcoal retorts are charged with wood, biowaste (bark, sawdust, etc.), peat, and sometimes low-rank coals. Yield and properties (hardness, density, surface area, etc.) can vary widely so the desired end use must be considered. Charcoal from coniferous trees is soft and porous, while that from hardwoods is dense and strong. For barbecuing, charcoal is usually compressed into briquettes, with binders and additives chosen to improve handling and ease of ignition. 

Despite present trends toward use of synthetic polymers developed over the last 10 or 20 years, starches are still being widely used as an adhesive in such applications as the production of paper and paperboard products, warp sizing, and bonding charcoal briquettes. Because of a unique combination of properties and low cost, these adhesives are almost impossible to exclude from many applications, especially those involving the use of hot paste (size) for anchoring fibers. For starch molecules to act as an adhesive, they must be chemically or thermally hydrated. Then, their adhesive character is developed and modified in different ways by chemicals or other additives for different end uses. As renewable resources that are both economical and reliable, starch and dextrin are likely to continue to be significant factors in the adhesive market for many years. 

These investigations on correlations established between the raw material properties and briquettability of Rhenish brown coal led to the following results ... 

Catalysts of wood pyrolysis are used to increase the yield of charcoal and to obtain a charcoal with modified properties or to produce definite valuable volatile products. The substances promoting condensation reactions are employed if high jields of charcoal are desired (4, 5, 7). Some catalysts increase the apparent density of charcoal, the pore dimensions and their adsorbency nature. Of all silvichemicals charcoal is currenUy the most in demand Commercial interest is focused on deciduous wood charcoal or charcoal briquettes. 

Production of a powder tablet, compact, or briquette can be carried out by a number of techniques. Each method results in the manufacture of different types of products with respect to size, shape, and physical properties. However, all have in common a basic compaction mechanism. 

The ductility of asphalt is a measure of the flexibility of the asphalt and is expressed as the distance in centimeters that a standard briquette can be elongated before breaking (ASTM D-113, IP 32). Ductility is a combination of flow properties and reflects homogeneity, cohesion, and shear susceptibility it is an indication of fatigue life and cracking. 

Rapidly solidified powders of Al-Zn-Mg-Cu alloys were produced by high-pressure water atomization of the melt (method WA-N) [4], This process provides cooling rates up to 106 K/s. Compaction was performed by the preliminary compaction at room temperature of powder into briquettes, followed by insertion into a capsule. The capsules were hermetically sealed, then the briquettes were subjected to hot degassing and compaction. The composition, powder size fraction used from the WA-N process, and properties of rods of 6 mm in diameter (A, = 17.7) in T6 condition are given in Table 2. 

The mechanisms discussed above are universally present advantages of products obtained from high-pressure agglomeration. They may be applied for all materials destined for similar uses and requiring these characteristics. The most important properties of briquettes or granules produced vith high pressure agglomeration methods are ... 

Tab. 6.9-1 Alphabetical listing of raw materials, additives, metal products, and metal bearing wastes that have been and/or are being agglomerated to obtain various benefits Tab. 6.9-2 Advantages of briquettes made from hot cast iron borings as a melt charge for foundries [B.3, Vol. 10 (1965), 16-22] Tab. 6.10-1 List of some materials that can be used as or converted to solid fuels and have been or are being processed most commonly with agglomeration technologies to improve their properties (see also Tab. 6.10-3)...

Bio-briquettes prepared by blending biomass with coal have a significantly shorter ignition time. In addition, because of the low expansibility and caking property of bio-briquettes, sufficient air flow is maintained between the briquettes during continuous combustion such as in a fireplace. As a result, the bio-briquettes have superior combustion-sustaining properties and do not die ont in a fireplace or other heater even when the air supply is decreased. This makes it easy to adjust the combustion rate. 

Feed materials for briquettes include coals of different properties pretreated coals, low-temperature coke, high-temperature coke breeze, or mixtures of these. Various binders are used in manufacturing the briquettes. The binder may be obtained partly during the pretieatment of the coal or during the carbonization of the briquette. The thermal posttreatment of briquettes at different temperatures, with or without the influence of oxygen in the air, leads to briquettes that (depending on the feed material, the treatment method, and the treatment temperature) have properties more or less similar to those of coke. 

If anthracite or low-volatile coals are used as feed materials, the comminuted coal usually mixed with an additional binder such as pitch or sulfite liquor. The briquettes undergo carbonization in one of several steps. The thermal posttreatment depends on the type of briquettes being treated and the desired properties of the final product. Heating rate and residence time in the hot zone are the deciding factors however, the composition properties of the raw briquettes also influence the processing steps and the nature of the final product. 

The use of propane asphalt as a briquette binder has also been investigated propane asphalt is the propane-insoluble portion of petroleum residua (Speight, 1991). The asphalt has a lower penetration value than asphalts obtained by distillation or by oxidation. Propane asphalt has a relatively high temperature sensitivity, which may cause the briquettes to stick together. It is possible to alter the temperature sensitivity of the propane asphalt by the conventional methods of treatment that are used to alter asphalt properties for highway use (Speight, 1991,1992). 

There are few, if any, recognized specifications or standard tests available for measuring the mechanical properties of bituminous coal briquettes. The properties currently measured are the breaking strengths and the abrasion or attrition of the briquettes. 

Competition from petroleum derivatives (Speight, 1991) and the desire to produce environmentally acceptable household fuels from bituminous coal require that more and more attention be given to the burning properties of briquettes. Briquettes must have a high heating value anthracite pitch briquettes average 13,300-13,900 Btu/lb. 

Properties Wh. orthorhombic cryst. orcryst. powd., si. acetic acid-like odor sol. in water, pract. insol. in alcohol m.w. 130.12 dens. 2.015 m.p. 300 C Toxicology LD50 (oral, rat) 2650 mg/kg, (IV, mouse) 154 mg/kg poison by IV route mod. toxic by ing. primary eye irritant TSCA listed Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and fumes Uses Preservative for foods and silage animal nutrition briquette binder drilling fluids concrete setting accelerator lubricants chrome tanning aux. 

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