Charcoal density

It is more tlian probable that these variations in the apparent densities of charcoals are to be ascribed to a difference in the depths of penetration of the hquids. Thus non-wetting liquids such as mercury would not readily penetrate the large macropores in the solid, far less into the micropores (below 100 A. in diameter) which exist in charcoal. We should thus anticipate that when mercury is employed as immersion liquid the charcoal density would be but small. Actually a value of only 0 865 was obtained by Harkins and Ewing. 

One hundred milliliters of an aqueous solution of methylene blue contains 3.0 mg dye per liter and has an optical density (or molar absorbancy) of 0.60 at a certain wavelength. After the solution is equilibrated with 25 mg of a charcoal the supernatant has an optical density of 0.20. Estimate the specific surface area of the charcoal assuming that the molecular area of methylene blue is 197 A. ... 

Typically, dry potassium nitrate is pulverized in a ball mill. Sulfur is milled into cellular charcoal to form a uniform mix in a separate ball mill. The nitrate and the sulfur—charcoal mix are screened and then loosely mixed by hand or in a tumbling machine. Magnetic separators may be used to ensure the absence of ferrous metals. The preliminary mix is transferred to an edge-mimer wheel mill with large, heavy cast iron wheels. A clearance between the pan and the wheels is required for safety purposes. The size of this gap also contributes to the density of the black powder granules obtained. Water is added to minimize dusting and improve incorporation of the nitrate into the charcoal. The milling operation requires ca 3 to 6 h. 

The impressed current protection method is used mainly for the internal protection of large objects and particularly where high initial current densities have to be achieved (e.g., in activated charcoal filter tanks and in uncoated steel tanks). There are basically two types of equipment those with potential control, and those with current control. 

The arrangement and distribution of anodes in gravel and activated charcoal filters is different. Cathodic protection of activated charcoal filters is basically feasible but requires a large number of electrodes and high protection current densities that are twice those for gravel bed filters, so that an electrically insulating layer can be deposited on the steel wall. 

Charcoal is not only employed in activated form for decoloring and adsorbing dissolved admixtures but also in its unactivated form as a filter aid. It can be used in suspensions consisting of aggressive liquids (e.g., strong acids and alkalies). As with sawdust, it can be used to separate solids that may be roasted. On combustion, the charcoal leaves a residue of roughly 2 percent ash. Particles of charcoal are porous and form cakes of high density but that have a lesser retention ability than does diatomite. 

Another emerging area m biofuels is pyrolysis, which is the decomposition of biomass into other more usable fuels using a high-temperature anaerobic process. Pyrolysis converts biomass into charcoal and a liquid called biocrude. This liquid has a high energy density and is cheaper to transport and store than the unconverted biomass. Biocrude can be burned in boilers or used in a gas turbine. Biocrude also can be chemical by altered into other fuels or chemicals. Use of pyrolysis may make bioenergy more feasible in regions not near biomass sources. Biocrude is about two to four times more expensive than petroleum crude. 

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. 

The accuracy of the measurement of radon concentrations with bare track detectors was found to be unsatisfactory due mainly to the changes of the deposition rate of radon progeny onto the detector as a result of air turbulence. In this work, therefore, a method was developed which can correct the contributions of the deposition to the track densities by classifying the etched tracks according to their appearance, i.e. round or wedge shaped. Using this method, about 30% improvement in the error of measurements was achieved. The calibration coefficient ob tained by experiment was 0.00424 tracks/cm /h/(Bq/m ), which agreed well with the calculated value. Comparison was also made of the present method with other passive methods, charcoal and Terradex, as to their performance under the same atmosphere. 

Nielson125 reports the synthesis of 7-((V-aIkylamino)- and T-(N,N-di-alkylamino)-l,3,5-triazaadamantanes by reductive alkylation of 94, which is obtained from 91 by an improved hydrogenation procedure (rhodium-charcoal catalyst, 25.5 psi). Paper chromatography54 and the Kovats indices and relative elution volumes of 1,3,5-triazaadamantane derivatives are measured.55 7-Amino-l,3,5-triazaadamantane is used as a vulcanization accelerator.127 7-(N,N-Dialkylamino)-l,3,5-triazaadamantanes are utilized as a new class of high-density fuel (DIADAM).128 Some 7-substituted 1,3,5-triazaadamantanes have bacteriostatic and fungistatic activity.129 7-Bromo-,... 

The determination of the density of charcoals by immersion in liquids has revealed a singular fluctuation of the apparent density with the nature of the liquid employed. The data obtained by Cude and Hulett J.A.G.S. XLii. 391, 1920), Harkins and Ewing ihid. XLiii. 1794,1921), and Williams Proc. Roy. Sog. A, xcviii. 224, 1920), are summarised in the following table, together with the compressibilities of the liquids for comparison. 

Howard and Hulett Jour. Phys. Ghem. Oct. 1924) brought forward additional evidence in favour of this hypothesis by determining the apparent densities of charcoals with helium gas in place of an immersion liquid with the following results ... 

On immersion of even well outgassed charcoal in water we must imagine that many of the micropores are not filled with water and thus an apparent diminution of the density of the solid occurs. These micropores cannot of course be empty for otherwise there is no reason why the liquid wetting the sides of the tubes should not fill them. If the micropores still contain small traces of gases not removed by the process of outgassing these will be compressed into pockets at the ends of the blind tubes, the pressure in the case of a micropore of 100 A. diameter would be about sixteen atmospheres. 

An attempt has been made to decide between these, two hypotheses advanced to explain the anomalous values obtained for density of charcoals by examining the density temperature curve for a system comprising water and charcoal. From a knowledge of... 

Woodmeal is of particular importance among combustible ingredients since apart from its stabilizing effect, discussed above, it enables the mixture to be retained in a loose state with a low density. Charcoal is another ingredient sometimes added. 

The density in this cose is therefore greater than that of water, hut still it varies to a certain extent with the temperature at which the substance has been prepared thus the charcoal obtained between the temporaturcs 302" and 515° Ftthr. decreases in density from 1 507 to 1 402 while, on the contrary, that which is afforded between 618 and 602" increases from P402 to 1-600 and from this point the density continues to increase, till, at the fusing point of the vessel, it becomes double that of water. 

The numbers in tha lost column were obtained by multiplying those of the preceding one by 1-036. Between the temperatures 572° and 752° tire conducting power is low, and is nearly the same in the wood and tha charcoal produced from it but when tho heat is elevated, the density of the charcoal increases rapidly, till it is about two-thirda that of iron. 

Both these systems of charring peat afford nearly the same yield of charcoal, when the operations have been properly attended to. It ranges from twenty-four per cent, by weight and twenty-seven by bulk when the peat is not thoroughly nir-dried but if this condition has boon attained, the product is about twenty-seven per cent, by weight, or thirty-two and a half by bulk a larger produce Is occasionally obtainad, but in those cases the exception must be attributed to the density and dry-... 

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