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Charcoal, lead content

Fuel, chiefly charcoal, usually has a low lead content and, in many cases, the trees from which it came were growing near the ore deposit and tend to have incorporated lead of the same isotopic composition as the ore deposit. In most cases, the isotope composition of lead in the smelted copper has not been perturbed away from that of lead in the copper ore. Further isotopic comparisons of copper ores and associated Bronze Age copper slags are needed to examine this question more extensively. Comparisons that have already been made bear out the hypotheses just advanced. [Pg.165]

Toxicology Prolonged inh. of high cones, may lead to a deposition of tricaldum phosphate crystals in the lung tissue TSCA listed Precaution Will not support combustion smolders like charcoal phosphate content is dissolved in adds Hazardous Decomp. Prods. CO, CO2 Cosmic Black 6 [Ebonex]... [Pg.210]

Properties BIk. powd. fineness 3-15 readily disp. in aq. and oil-based vehicles insol. in water sp.gr. 2.60 vise. 78-80 KU oil absorp. 0.42-0.45 pH 8.8-9.0 anionidnonionic 5 /o pigment 10.2% C Toxicology Prolonged inh. of high cones, may lead to a deposition of tricaldum phosphate crystals in the lung tissue TSCA listed Precaution Will not support combustion smolders like charcoal phosphate content is dissolved in acids Hazardous Decomp. Prods. CO, CO2 Cosmic Black 500 WB [Ebonex]... [Pg.210]

Fig. 6. Dependence of hydrogenation rate for dimethylethynylcar-binol in water at 40 C on lead content with various carriers 1) Barium sulfate 2) calcium carbonate 3) silica (II) 4) charcoal 5) silica (I). Fig. 6. Dependence of hydrogenation rate for dimethylethynylcar-binol in water at 40 C on lead content with various carriers 1) Barium sulfate 2) calcium carbonate 3) silica (II) 4) charcoal 5) silica (I).
The metallic arsenic is obtained primarily from its mineral, arsenopyrite. The mineral is smelted at 650 to 700°C in the absence of air. However, the most common method of production of the metal involves reduction of arsenic trioxide, AsOs with charcoal. Arsenic trioxide is produced by oxidation of arsenic present in the lead and copper concentrates during smelting of such concentrates. The trioxide so formed, readily volatilizes and is collected in a dust flue system where further treatment and roasting can upgrade the trioxide content. The trioxide vapors are then condensed and further purified by pressure leaching and recrystallization techniques. It is then reduced with charcoal to give metallic arsenic. [Pg.62]

Preparation of Lead. a. Thoroughly mix 5 g of lead(II) oxide and 0.5 g of finely ground charcoal. The lead(II) oxide must be preliminarily dried in a drying cabinet at 100 °C, and the charcoal roasted in an iron crucible covered with a lid. Put the mixture into a porcelain crucible, spill charcoal over it, and roast it in a muffle furnace at 800 °C. After 10 or 15 minutes, mix the contents of the crucible with a carbon rod and again roast them during 30 minutes. Pour out the molten lead onto a chamotte dish. Cool the metal bead and keep it for following experiments. Calculate the yield in per cent. Write the equations of the reactions. [Pg.270]

Obviously this wide distribution of the 14C formed in the atmosphere lakes time it is believed to require a period of 500-1000 years. This time is not. however, a deterrent to radiocarbon dating because of two factors die long half-life of I4C and the relatively constant rate of cosmic-ray formation of l4C in the earth s atmosphere over the most recent several thousands of years. These considerations lead to the conclusion that the proportion of 14C in the carbon reservoir of the earth is constant, and that the addition by cosmic ray production is in balance with the loss by radioactive decay. If this conclusion is warranted, then the carbon dioxide on earth many centuries ago had the same content of radioactive carbon as the carbon dioxide on earth today, Thus, radioactive carbon in the wood of a tree growing centuries ago had the same content as that in carbon oil earth today. Therefore, if we wish to determine how long ago a tree was cut down to build an ancient fire, all we need to do is to determine the relative 14C content of the carbon in the charcoal remaining, using the value we have determined for llie half life of 14C. If the carbon from Ihe charcoal in an ancient cave has only as much 14C radioactivity as does carbon on earth today, then we can conclude that the tree which furnished llie firewood grew 5730 30 years ago. [Pg.1414]

Basic techniques for producing charcoal have not changed over the years although the equipment has. Charcoal is produced when wood is burned under conditions in which the supply of oxygen is severely limited. Carbonization is a term that aptly describes the thermal decomposition of wood for this application. Decomposition of carbon compounds takes place as the temperature rises, leading to a solid residue that is richer in carbon than the original material. Wood has a carbon content of about 50 percent, whereas charcoal of a quality suitable for general market acceptance will be analyzed as follows fixed carbon 74-81 percent, volatiles 18-23 percent, moisture 2-4 percent, and ash... [Pg.1284]

Figure 6 shows that the increase in zinc and copper content in the charcoal is due to their concentration in this product. The pyrolytic liquids content in these two metals is very variable. But the majority of zinc and copper is found in the charcoal as well as for nickel, lead and chromium. The same conclusion was observed for CCB (Copper, Chromium, Arsenic) treated wood [2]. [Pg.1371]

As even the optimized hydrogenation conditions gave rise to not more than 89% enantioselectivity it became very important to find an efficient purification procedure which would allow the enrichment of the desired (-(-enantiomer. A rapid screening of several weak and strong acids led to an acceptable solution. The acetates of both the racemate 11 as well as the (-)-enantiomer 12 are readily crystalline salts but the acetate of the desired (S)-enantiomer is less soluble in toluene at 0°C than that of the racemate by a factor of 10. Thus it could be crystallized in overall yield of 84%, content 99.1%, 98.9% ee. Finally it was noticed that traces of iridium (70-200 ppm) in the acetate salt hindered the following reaction in the synthetic sequence, by leading to decomposition of the formic acid (used as for-mylation reagent). A treatment of the octahydroisoquinoline solution with charcoal prior to precipitation of the acetate salt lowers the Ir content to 20-40 ppm. This new quality can then be formylated without problems under the standard conditions. [Pg.296]

The commercial catalyst used for hydrogenation was a palladium on charcoal catalyst (type 37), manufactured by Johnson Matthey (UK)) with metal content 4.89% and supplied as powder. The Pd metal was d osited on the exterior sur ce of the charcoal The Pd/Ii02 catalyst was prepared using sodium tetrachloropalladate (II), supplied by Johnson Matthey (UK) and titanium dioxide, firom Degussa (Germany). The hydrogen gas was supplied by BOC (UK), with >99.98% purity and was used directly fi om cylinder. The reactant, butyne-l,4-diol 99%, was procured firom Aldrich (UK) and water and 2-propanol obtained firom Fisons (UK), were used as solvents. Additives such as lead acetate, quinoline, thiophene and triethyl phosphite were supplied by Aldrich (UK) and cupric acetate, zinc su hate, ferric nitrate and potasaum hydroxide were provided by Fisons (UK). [Pg.60]


See other pages where Charcoal, lead content is mentioned: [Pg.211]    [Pg.87]    [Pg.132]    [Pg.280]    [Pg.151]    [Pg.251]    [Pg.305]    [Pg.1062]    [Pg.1168]    [Pg.82]    [Pg.171]    [Pg.407]    [Pg.50]    [Pg.1056]    [Pg.1607]    [Pg.1608]    [Pg.14]    [Pg.130]    [Pg.47]    [Pg.208]    [Pg.202]    [Pg.548]    [Pg.171]    [Pg.356]    [Pg.424]    [Pg.436]    [Pg.151]   
See also in sourсe #XX -- [ Pg.165 ]




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Charcoal

Lead content

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