Porose Pulver

A tube (20 cm. long and 2 cm. in diameter) with a porous disk (porosity 3 or medium) sealed in at one end and with an ungreased ground joint, is arranged as shown in Fig. 8. Rhodium(III) chloride 3-hydrate (11.0 g. 0.042 mol) is pulverized and placed on top of the disk. The apparatus... 

Some of the tar sands were extracted exhaustively with benzene-ethanol (3 1.) in a Soxhlet extractor to yield organic materials, and only those materials so obtained will be subsequently referred to as bitumens. This process does not remove all organic materials from some tar sands, and so another method of extraction was used. In the alternate procedure, tar sands first were pulverized in a mortar and pestle. Tnen the sample was transferred to Erlenmeyer fiasks and treated with successive volumes of n-heptane until less than 25 mg of material was dissolved. Each volume of heptane solution was filtered on a sintered glass funnel (coarse porosity), and the heptane then was removed. After heptane was observed to dissolve little material, the solvent was changed to benzene and after this to a mixture of benzene-methanol (1 1). Finally, the sands were extracted with several portions of warm pyridine. 

Another problem with pulverized samples is that their packing density varies as a function of the depth. This is known as the porosity effect, and for the Bragg-Brentano geometry, it may be expressed using two different approaches ... 

The coke used in the blast furnace should have a high carbon content, low mineral matter, and sulfur contents and should have an appropriate porosity as well as good strength to ensure that it gives good reactivity and does not pulverize to choke the gas flow in the blast furnace even at high temperatures. 

Consulting a Tyler Standard Screen Scale Table, it can be read the value of the screen equivalent diameter as 0.208 mm, so the pulverized coal may be considered a fine powder. Since the particles are taken as spherical, the ideal porosity =0.4 can be used for calculation. Finally, from any reference book (or appendix of some engineering textbook) listing physical properties of materials, at approximately 25°C the density of air is of the order of 1.2 kg/m. Substituting directly into Equation 7.5 ... 

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