Furnaces charcoal

Holzkohlen-brennerei, /. charcoal burner, -brennofen, m. charcoal furnace, -eisen, n. charcoal iron, -feuer, n. charcoal fire, -klein, n., -losche, /. charcoal dust, charcoal smalls, -meiler, m. charcoal mound (cf. Meiler). -ofen, m. charcoal oven, -pulver, n. powdered charcoal, -roheisen, n. charcoal pig iron, -staub, m. charcoal dust, -tecr, m. charcoal tar. 

Fig. 290 is another charcoal furnace, representing those in use at Pennsylvania in America, The height of this furnace, says Overmann, is thirty-two foot, width... 

Towards the close of the eighteenth century there was considerable improvement in the trade m other parts of the country, for coke was now being used. In 1790 England possessed no fewer than 81 coke and 25 charcoal furnaces. In 1917 the total number of blast furnaces was 496, and of these an average of 324 were in blast at any moment during the year. The enormous growth in the output of pig iron since 1740 is well illustrated by the following table. 

A modification of Dumas vapour density method was used by Mitscherlich, who measured higher temperatures (270°-700°) with an air thermometer, the cylindrical glass tube containing the substance being put inside an iron tube heated in a charcoal furnace. For 300" a metal bath was used. He determined the vapour densities of bromine, sulphur, phosphorus, arsenic, mercury, sulphur trioxide, phosphorus pentachloride, antimony pentachloride, calomel and other mercury salts, and arsenious oxide. Sodium and potassium vapours attacked glass. He used H2 = i as unit with H = i the number of atoms in an equal volume found were i for mercury, 2 for bromine, 6 for sulphur, 4 for phosphorus and arsenic. The densities of phosphorus pentachloride and of antimony pentachloride were half the normal values. Mitscherlich did not appreciate the consequences of Avogadro s hypothesis e.g. he says i vol. of... 

At red heat, a low carbon ferrous metal, in contact with carbonaceous material such as charcoal, absorbed carbon that, up to the saturation point of about 1.70%, varied in amount according to the time the metal was in contact with the carbon and the temperature at which the process was conducted. A type of muffle furnace or pot furnace was used and the kon and charcoal were packed in alternate layers. 

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. 

To alleviate the air pollution problem associated with charcoal kilns and furnaces, the gases from the kiln and furnaces are burned (see Airpollution CONTROLMETHODS). They can be burned with additional fossil fuel to recover heat and steam (110,111), or in afterburners to nearly eliminate visible air pollution and odors (112). 

Metafile arsenic can be obtained by the direct smelting of the minerals arsenopyrite or loeUingite. The arsenic vapor is sublimed when these minerals are heated to about 650—700°C in the absence of air. The metal can also be prepared commercially by the reduction of arsenic trioxide with charcoal. The oxide and charcoal are mixed and placed into a horizontal steel retort jacketed with fire-brick which is then gas-fired. The reduced arsenic vapor is collected in a water-cooled condenser (5). In a process used by Bofiden Aktiebolag (6), the steel retort, heated to 700—800°C in an electric furnace, is equipped with a demountable air-cooled condenser. The off-gases are cleaned in a sembber system. The yield of metallic arsenic from the reduction of arsenic trioxide with carbon and carbon monoxide has been studied (7) and a process has been patented describing the gaseous reduction of arsenic trioxide to metal (8). 

C. J. Macedo, E. A. O. d Avila, and J. G. Brosnan, Startup of a Closed Carbide Furnace Using Charcoal as a Reducing Mgent, Vol. 43, Electric Furnace Proceeding, Atianta, Ga., 1985. 

The earliest method for manufacturiag carbon disulfide involved synthesis from the elements by reaction of sulfur and carbon as hardwood charcoal in externally heated retorts. Safety concerns, short Hves of the retorts, and low production capacities led to the development of an electric furnace process, also based on reaction of sulfur and charcoal. The commercial use of hydrocarbons as the source of carbon was developed in the 1950s, and it was still the predominate process worldwide in 1991. That route, using methane and sulfur as the feedstock, provides high capacity in an economical, continuous unit. Retort and electric furnace processes are stiU used in locations where methane is unavailable or where small plants are economically viable, for example in certain parts of Africa, China, India, Russia, Eastern Europe, South America, and the Middle East. Other technologies for synthesis of carbon disulfide have been advocated, but none has reached commercial significance. 

Depending on energy and raw material costs, the minimum economic carbon disulfide plant size is generaHy in the range of about 2000—5000 tons per year for an electric furnace process and 15,000—20,000 tons per year for a hydrocarbon-based process. A typical charcoal—sulfur facHity produces approximately 5000 tons per year. Hydrocarbon—sulfur plants tend be on the scale of 50,000—200,000 tons per year. It is estimated that 53 carbon disulfide plants existed throughout the world in 1991 as shown in Table 2. The production capacities of known hydrocarbon—sulfur based plants are Hsted in Table 3. The United States carbon disulfide capacity dropped sharply during 1991 when Akzo Chemicals closed down a 159,000 ton per year plant at Delaware City, Delaware (126). The United States carbon disulfide industry stiH accounts for about 12% of the total worldwide instaHed capacity. 

Charcoal is generally satisfactorily activated by heating gently to red heat in a crucible or quartz beaker in a muffle furnace, finally allowing to cool under an inert atmosphere in a desiccator. Good commercial activated charcoal is made from wood, e.g. Norit (from Birch wood), Darco and Nuchar. If the cost is important then the cheaper animal charcoal (bone charcoal) can be used. However, this charcoal contains calcium phosphate and other calcium salts and cannot be used with acidic materials. In this case the charcoal is boiled with dilute hydrochloric acid (1 1 by volume) for 2-3h, diluted with distilled water and filtered through a fine grade paper on a Buchner flask, washed with distilled water until the filtrate is almost neutral, and dried first in air then in a vacuum, and activated as above. To improve the porosity, charcoal columns are usually prepared in admixture with diatomaceous earth. 

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