Anthracite, oxidation

Although the authors in this sand study reported the iron content of the sand, there remains a possibility that noniron species were acting as catalysts. In fact, a study of coal (anthracite) oxidation by hydrogen peroxide indicates that formation of hydroxyl radical occurs even after the removal of iron from the coal [47], This study suggested that surface sites on the coal may have acted as catalytic centers for hydroxyl radical formation. Whereas coal is... 

Coal storage results in some deterioration of the fuel owing to air oxidation. Moreover, if inadequate care is taken, spontaneous heating and combustion may result. As the rank of coal decreases, it oxidizes more easily and must be piled more carefully. Anthracite does not usually present a problem. 

Traditional types of gravity and pressure media bed filters (such as sand and anthracite filters) are widely used to remove suspended solids and improve the clarity of raw water. They are also used following aeration or oxidation and chemical precipitation softening. 

With Carbon,—If caustic soda is heated to dull redness with charcoal or anthracite or some other form of pure carbon, hydrogen is evolved and sodium carbonate and sodium oxide produced, in accordance with the following equation —... 

When pulverized calcium oxide is heated with carhon (crushed coke or anthracite) in an electric furnace, calcium carbide is produced ... 

The principal Zn ores are Zn blende (Zn sulfide, sphalerite) and calamine (Zn carbonate, smithsonite), both of which can be converted into the oxide by roasting. The volatility of Zn at bright red heat enables the metal to be extracted from the ore by distln. Toward this end the powdered oxide is mixed with a stoichiometric excess of anthracite and heated to 1200— 1300° in a retort causing the Zn oxide to be reduced ... 

Contrary to H2S, the amount of S02 evolution remains constant with coal maturation. The peak temperature of S02 rises from about 350 C for the peat sample to about 650 C for the anthracite sample. This temperature increase with coal maturation could be due to a loss of inflammable volatile matter which accelerates the char oxidation, and a relative enrichment of the char in condensed aromatic nuclei more resistant to pyrolytic breakdown, as seen by PTP and Py-GC, but also to a reduction of the size of micropores during coalification which hampers oxygen penetration into the solid matrix. 

Carbon molecular sieves are produced by controlled pyrolysis and subsequent oxidation of coal, anthracite, or organic polymer materials. They differ from zeolites in that the micropores are not determined by the crystal structure and there is therefore always some distribution of micropore size. However, by careful control of the manufacturing process the micropore size distribution can be kept surprisingly narrow, so that efficient size-selective adsorption separations are possible with such adsorbents. Carbon molecular sieves also have a well-defined bi-modal (macropore-micropore) size distribution, so there are many similarities between the adsorption kinetic behavior of zeolitic and carbon molecular sieve systems. 

Heard I, Senftle FE. Chemical oxidation of anthracite with hydrogen peroxide via the Fenton reaction. Fuel 1984 63 221-226. 

Figure 69. Low-temperature-oxidation Test of Anthracite Coal 48/100-mesh, Temperature 300 deg C.

Figure 70. Initial Oxidation Rates of Anthracite Coal.

In this equation q0 is the initial oxidation rate in cu cm of oxygen consumed (N.T.P.) per 100 g of dry anthracite coal at 20.93 percent oxygen, T the temperature in deg C, and d the diameter of the particles in mm. Eq (12-18) is empirical. If the oxidation were precisely proportional to the surface, the exponent of d would be —1. It is interesting to note the importance of temperature. Small variations in temperature will produce large changes in the value of qo. Scott and Jones stressed the importance of constant temperature during tests. 

Calculate the initial oxidation rate of 1000 lb anthracite coal at 20.93 percent oxygen, the average diameter of the particles being 0.2 cm and the temperature of the surrounding air 350 deg C. 

Effect of particle size on the rate of oxidation of anthracite. U. S. Bur. Mines Rept. Investigations 3546. 

Waters that may be contaminated with high concentrations of turbidity may want to consider a top layer of anthracite to capture these solids. This protects the greensand and ensures that the greensand is free and clear to proceed with oxidation and filtration of metals. A 15 - 18-inch layer of anthracite is recommended. 

Charcoal and lampblack effect the reduction more easily than anthracite, complete reduction being effected with the former at 900° C-, some 20 to 30 per cent, of charcoal in excess of that required in the above equation being desirable. At higher temperatures the reduction proceeds much more rapidly. By briquetting the charcoal and cobalt oxide, using some organic material, such as molasses, as binder, reduction may be effected at a slightly lower temperature. 

In this method, lime (calcium oxide) is reduced by carbon (coke or anthracite) CaO -i- 3C - CaCj + CO = 465 kJ/mol... 

The calcium oxide is produced immediately prior to reduction from high purity limestone. This enthalpy of the reaction is +465.6kJ/mol and is provided by electric power and results in the consumption of Soderberg electrodes made from anthracite. The cell is tapped to release the molten carbide which is produced in 80% purity. The off-gas from the cell is typically 80% carbon monoxide and about 10% hydrogen. Following the production of calcium carbide, acetylene is produced by addition of water to the carbide ... 

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