Briquette

Ductility is the elongation, at the moment of failure, of a standard bitumen briquette that is stretched at a predetermined speed and temperature. References are the NF T 66-006, ASTM D 113, IP 32 methods. 

Grades, Quality Control. Fluorspar is marketed ia several grades metallurgical fluorspar (metspar) is sold as gravel, lump, or briquettes. The minimum acceptable assay is 60% effective calcium fluoride. The effective value is determined by subtracting from the contained calcium fluoride 2.5% for every percent of Si02 found ia the complete analysis apparently based on the following stoichiometry (1) ... 

In the briquetting process, ore fines usually are mixed with a binder and are formed into compact masses between two rotating roUs. The roUs exert pressures of 1.5-4.2 t/cm in forming the briquettes. In the nodulizing process, which is relatively uncommon commercially, ore fines are heated in a rotary kiln to a temperature, usually 1250—1370°C, at which the ore begins to melt and bind. The ore balls in the kiln to form nodules that are discharged and cooled. 

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. 

The hot reduced fines are pneumatically transported to an atmospheric pressure hoi ding dmm from which they are fed to the briquetting machines. The hot briquettes are separated, cooled on a circular grate, and deUvered to an outdoor storage pile. 

Plants for briquette production exist in the eastern part of Germany, AustraHa, and India. German transport costs pet unit of heating value ate about 40% less for briquettes than for lignite. 

Briquettes must be transported carefliny to avoid breakage. They ate usually dumped into piles in sheds and frequently ate screened to remove smaller broken particles. Hand-stacking significantly improves storage quaHty, and permits mote material to be stored in a limited volume. 

Briquettes have a heating value of 16.7-23.4 MJ/kg (7, 200-10,000 Btu/lb) or from 2—3 times the value of a typical brown coal primarily because of the moisture loss. 

Briquettes bum similarly to bituminous coal, although some tend to disintegrate on combustion. Alow (<6-7%) ash content increases the possibility of disintegration. Normal combustion depletes the combined oxygen and volatile matter in the coal quiddy, effectively changing its composition and combustion behavior, making control of combustion difficult. 

Low Temperature Carbonization. The Lurgi Sptlgas process was developed to carbonize brown coal at relatively low temperatures to produce tars and oils (Fig. 5). A shaft furnace internally heated by process-derived fuel gas (Spblgas) is used. The product can range from a friable coke breeze to hard lump coal depending on the quality of the briquettes used in the feed. The briquettes, made in normal extmsion presses, break down into smaller sizes during carbonization. 

The briquettes are distributed over bunkers and dried for about 5 h at 150°C (0.5% moisture), then descend to the lower carbonization zone for another 5 h at 500—800°C. Heating is provided by burning the purified product gas with air using from 35—48% of the gas. The rest usually is used for... 

The conditions of pyrolysis either as low or high temperature carbonization, and the type of coal, determine the composition of Hquids produced, known as tars. Humic coals give greater yields of phenol (qv) [108-95-2] (up to 50%), whereas hydrogen-rich coals give more hydrocarbons (qv). The whole tar and distillation fractions are used as fuels and as sources of phenols, or as an additive ia carbonized briquettes. Pitch can be used as a biader for briquettes, for electrode carbon after coking, or for blending with road asphalt (qv). 

Operating parameters of this German plant, on the basis of one cubic meter of raw gas, iaclude 0.139 m O2, 0.9 kg briquettes, 1.15 kg steam, 1.10 kg feed water, 0.016 kWh, and 1.30 kg gas Hquor produced. Gasifier output is 1850 m /h and gas yield is 1465 m /t dry, ash-free coal. The coal briquettes have a 19% moisture content, 7.8% ash content (dry basis), and ash melting poiat of 1270°C. Thermal efficiency of the gas production process is about 60%, limited by the quaHty and ash melting characteristics of the coal. Overall efficiency from raw coal to finished products is less than 50%. 

When magnesium oxide is chlorinated in the presence of powdered coke or coal (qv), anhydrous magnesium chloride is formed. In the production of magnesium metal, briquettes containing CaCl2, KCl, NaCl, MgO, and carbon are chlorinated at a temperature such that the electrolyte or cell melt collects at the bottom of the chlorinator, enabling the Hquid to be transferred directly to the electrolytic cells. 

Sohd form maleic anhydride is produced from molten maleic anhydride as briquettes or pastilles weighing 0.5 to 20 g. Flaked maleic anhydride is used in some areas of the world but is not generally accepted in the United States because of the high dust content. Briquettes or pastilles are packed in... 

The general sales specification under which maleic anhydride is sold ia the United States specifies a white fused mass or briquettes of 99.5% minimum assay and 52.5°C minimum crystallisation poiat. The melt color specification is 20 APHA maximum with a maximum APHA color of 40 after two hours of heating at 140°C. Four grams of maleic anhydride ia 10 milliliters of water are to be completely soluble. The resulting solution is to be colodess. The acidity resulting from maleic acid is allowed to be a maximum of 0.2%. 

Manganese metal made by this process is 99.9% pure. It is in the form of irregular flakes (broken cathode deposits) about 3-mm thick, and because of its brittleness, has Httle use alone. Most of the electrolytic manganese that is used in the aluminum industry is ground to a fine size and compacted with granulated aluminum to form briquettes that typically contain 75% Mn and 25% Al. 

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