Carbonates heating

Other recovery methods have been used (10). These include leaching ores and concentrates using sodium sulfide [1313-82-2] and sodium hydroxide [1310-73-2] and subsequentiy precipitating with aluminum [7429-90-3], or by electrolysis (11). In another process, the mercury in the ore is dissolved by a sodium hypochlorite [7681-52-9] solution, the mercury-laden solution is then passed through activated carbon [7440-44-0] to absorb the mercury, and the activated carbon heated to produce mercury metal. Mercury can be extracted from cinnabar by electrooxidation (12,13). 

The Shawinigan process uses a unique reactor system (36,37). The heart of the process is the fluohmic furnace, a fluidized bed of carbon heated to 1350—1650°C by passing an electric current between carbon electrodes immersed in the bed. Feed gas is ammonia and a hydrocarbon, preferably propane. High yield and high concentration of hydrogen cyanide in the off gas are achieved. This process is presently practiced in Spain, AustraUa, and South Africa. 

Graphitic carbon normally refers to soft carbon heated above about 2100°C. The probability of finding turbostratie disorder begins to decrease as the heat-treatment temperature increases to above 2100°C. When the heating temperature reaehes above 3000°C, graphite forms. Coneeptually, graphite is a graphitic carbon with no or very little turbostratic disorder. 

A variety of materials have been p aolysed at temperatures near 700°C which showed behavior similar to that in Fig. 2 for the CRO550 sample [28-30]. Yata et al. [28] and Mabuchi et al. [29] noticed that their carbons heated at these temparatures contained substantial hydrogen. However, they proposed that the large capacity and hysteresis was due to the storage of lithium in the pores of the materials. It was our idea that the hydrogen in these materials could be playing a crucial role. Therefore we synthesized several series of materials at different temperatures and studied them. 

Cast irons are iron with high levels of carbon. Heat treatments and alloying element additions produce gray cast iron, malleable iron, ductile iron, spheroidal cast iron and other grades. The mechanical properties vary significantly. Nickel-containing cast irons have improved hardness and corrosion resistance. Copper or molybdenum additions improve strength. 

Fig. 60. TMBA- and MS-curves of the decomposition of calcium carbonate. Heating rate...

It has been shown that if hydrogen is passed over pure carbon heated to 1150° C., direct chemical union takes place, methane or marsh gas being formed —... 

The same degree of methylation as by refluxing with methanol was achieved by blowing a stream of methanol vapor and nitrogen over the carbon heated to 120°. 

There remains the question why activated carbons differ from carbons heat-treated at 1200° with respect to the relative position of the carboxyl groups. Perhaps this difference is based on the structure of the edges of the carbon layers. Hennig (87, 88) found, by observations with single crystals of graphite, that after oxidation with dry oxygen the armchair configuration of the periphery resulted ... 

Since the late 1980s, there has been a proliferation of new potential reduced-exposure products (PREPs), promoted by the industry with the claims of reduced harm, in all the four categories that were summarized earlier (Stratton et al. 2001 Hatsukami et al. 2002, 2005). These include (a) modified tobacco products, such as several denicotinized brands and reduced TSNA emission cigarettes (b) chewing gum impregnated with tobacco (c) smokeless tobacco products with claimed reduced nitrosamine levels and (d) cigarette-like products (carbon-heated smoking devices). 

Fig. 35. Oscilloscope tracings of oxygen effects. Top decay of EPR signal of coals, charred sugars and activated carbons heated above 100° with increase in oxygen pressure. Bottom decay of EPR signal in activated carbons with increase in oxygen pressure (181).

However, when the pentachloride is heated with hydrocarbons, a beta-form of M0CI4 forms. The product always is contaminated with carbon. Heating the pentachloride with molybdenum metal forms the same beta-MoCR. Reaction with hydrogen bromide yields molybdenum tetrabromide. 

Although the preparation has been repeated, there have been no other reports of the type of reaction, (described in 1923) in which carbazole in the presence of excess potassium hydroxide and nitrobenzene at only 50°C gave a good yield of 9-(4-nitrophenyl)-carbazole, presumably via an adduct such as 43 subsequently oxidized by excess nitrobenzene and/or air. More recent examples of N-arylation of carbazoles have involved copper catalysis in reaction of aryl halides with carbazoles. Thus, copper bronze and potassium carbonate heated with the carbazole and the appropriate aromatic halide have produced 9-(4-methoxyphenyl)- and 9-(2-tolyl)carbazoles 9-(4-phenylphenyl)carbazole, l,4-di(carbazol-9-yl)benzene, 4,4 -di(carbazol-9-yl)biphenyl, and 9-(2-pyridyl)- and 9-(2-quinolyl)carbazoles 9-[2-(2-phenylphenyl)phenyl]- and 9-[2-(4-methylphenyl)phenyl] carbazoles 9-(3-bromo-6-nitrophenyl)-, 9-[3-(carbazol-9-yl]-, 9-(2-nitrophenyl)-, 9-(4-methyl-2-nitrophenyl)-, 9-(4-methoxycarbonyl)-l-nitro-, and l-nitro-9-(4-tolyl)carbazoles 9-(2-methoxycarbonylphenyl)carbazole 9-[2- 2-... 

Transfer a 5.0g sample to a tared porcelain or silica crucible (previously heated and cooled in a desiccator) and add sufficient ale to cover the sample. Place the crucible on a hot plate at low heat and ignite the ale. When the ale bums out and the sample is completely carbonized, heat the crucible over a Bunsen burner und1 all the carbonaceous matter of sample disappears. Then cool In a desiccator and weigh. Calc the gain in wt as % ash. In case of an abnormally high result, run a blank on the ale used... 

Two-thirds of the requisite amount of arsenious oxide are first added and the remainder after the reaction has progressed for a time, the gas being passed continuously. The arsenic trichloride may be distilled off and does not require purification. The reaction is somewhat violent, however. Arsenic trichloride may also be prepared conveniently by passing carbonyl chloride over a mixture containing 80 per cent, of arsenious oxide and 20 per cent, of carbon heated at 200° to 260° C. the yield is almost quantitative.15... 

Chlorides Aluminum chloride AlClj 6H20. white crystals, soluble, by reaction of aluminum hydroxide and HC1. and then crystallizing anhydrous aluminum chloride A1C1-, white powder, fumes in air, formed by reaction of dry aluminum oxide plus carbon heated with chlorine in a furnace, used as a reagent in petroleum refining and other organic reactions. 

Sulfide Boron sulfide, B2S3, white solid, unpleasant odor, irritating to the eyes, reactive with water to form boric acid and hydrogen sulfide, formed by reaction of boron oxide plus carbon heated in a current of CS2 ai red heat. 

Figure 10.12 Voltammetry of ascorbic acid at glassy carbon heat-treated at (a) 520°C, (b) 650°C, (c) 750°C. Scan rate = 0.1 V/s. [Adapted from Ref. 41.]...

---