Physical apparent density

DRI can be produced in pellet, lump, or briquette form. When produced in pellets or lumps, DRI retains the shape and form of the iron oxide material fed to the DR process. The removal of oxygen from the iron oxide during direct reduction leaves voids, giving the DRI a spongy appearance when viewed through a microscope. Thus, DRI in these forms tends to have lower apparent density, greater porosity, and more specific surface area than iron ore. In the hot briquetted form it is known as hot briquetted iron (HBI). Typical physical properties of DRI forms are shown in Table 1. 

S.P. Howell J.E. Tiffany, "Methods for Routine Work in the Explosives Physical Laboratory of the Bureau of Mines , USBurMines Technical Paper 186, Wash, DC (1918), 14-15 (Detn of apparent specific gravity by sand method) 4) C.E. Munroe J.E. Tiffany, "Physical Testing of Explosives , USBurMines Bull 346, Wash, DC (1931), 22-3 (Detn of apparent sp gr by sand test) 24 (Detn of shaking density) 5) Vennin, Burlot Lecorche" (1932), 154 (Gravimetric apparent density) 6) Pepin Lehalleur (1935), 41, 54 62 (Densite de enlargement) 99-100 (Densimeters of Bianchi and of Bode) 7) Hayes (1938), 50 (Loading density)... 

Physical properties Density Specific gravity Pore structure True density as measured by helium displacement Apparent density Specification of the porosity or ultrafine structure of coals and nature of pore structure between macro, micro, and transitional pores... 

Several catalyst densities are used in the literature. True density may be defined as the mass of a powder or particle divided by its volume excluding all pores and voids. In a strict physical sense, this density can be calculated only through X-ray or neutron diffraction analysis of single crystal samples. The term apparent density has been used to refer to the mass divided by the volume including some portion of the pores and voids, and so values are always smaller than the true density. This term should not be used unless a clear description is given of what portion of the pores is included in the volume. So-called helium densities determined by helium expansion are apparent densities and not true densities since the measurement may exclude closed pores. 

Table 12 shows some of the physical properties of palm oil. The apparent density is an important parameter from the commercial point of view since it is used for volume to weight conversions. It can also be used as a purity indicator. 

This survey deals with the fundamental morphological parameters of foamed polymers including size, shape and number of cells, closeness of cells, cellular structure anisotropy, cell size distribution, surface area etc. The methods of measurement and calculation of these parameters are discussed. Attempts are made to evaluate the effect and the contribution of each of these parameters to the main physical properties of foamed polymers namely apparent density, strength and thermoconductivity. The cellular structure of foamed polymers is considered as a particular case of porous statistical systems. Future trends and tasks in the study of the morphology and cellular structure-properties relations are discussed. 

The direct contact model has some difiiculties, however. In fluidized beds, gas bubbles of very low solid content are usually considered to exist in the dense phase (H14, K13, T19). Also, the cloud layer is negligibly thin, due to small (/ r for the usual fluid catalyst beds, according to equa-ticMis of Davidson and Harrison (D3) and Murray (M47). The streamlines of gas phase through a bubble have been observed to pass through the cloud, but not through the bubble wake (R17). Thus there seems little possibility of believing that the bubble gas is in direct contact with a substantial amount of catalyst in the bubble phase (see also Secticxi VI,A). Furthermore, the direct contact model is applied to the data by Gilliland and Knudsen, and v in Eq. (7-9) is calculated to fit the data. Calculation (M26) shows that the volume of catalyst, with an apparent density the same as for the emulsion, which contacts the bubble gas freely exceeds the volume of bubble gas itself (v/ib = 3.3, 2.0, and 1.5, respectively, for Uc. = 10, 20, and 30 cm/sec). This seems to be unsound physically. 

A peak similar to that shown in Fig. 2.25 is observed on a sihcon surface with about 40 A of thermally grown oxide and the peak becomes higher and broader with additional anodic thickening. The apparent density depends on light intensity and on whether the sample is biased cathodicahy or anodically before the measurement This capacitance peak, however, disappears almost completely in the presence of HF, which dissolves silicon oxide. Thus, the surface states of a silicon electrode in KCl solution, according to Madou et are physically associated with the unsaturated bonds at the Si/Si02 interface. On the other hand, in similar solutions, Chazalviel °° found that surface states, situated at about 0.9eV below the conduction band, are caused by the adsorbed ions but not the oxide. Thus, for an oxide-covered electrode (e.g., 12nm... 

Other physical characteristics such as refractive index and apparent density of the oil are as given in Table 3.7. 

Processing production of coal sample and physical mechanic parameters test are in strict accordance with the provisions of Measurement method of coal and rode physical and mechanical properties (GB/T 23561-2009), and Measurement method of coal seam impact tendency classification index (MT/T 866-2000). The experiment determined natural apparent density, compressive strength, consistent coefficient, elastic modulus, deformation modulus, wave velocity, rock burst energy index, elastic energy index, dynamic failure time, and other parameters. The determination results as shown in Table 1. 

Caution must be exercised when extrapolating these results to real systems that may deform, shrink, puff, or undergo thermally driven physical or chemical changes. Such a system is likely to produce lower apparent density... 

Scale invariance radically changes the very meaning of physical properties. Consider density, for example. It is usual to speak of the density of zinc, of mercury, o/paper (in fact, of a given type of paper), as if this were some immutable property of the material under consideration. But what is the density of a crumpled up ball of paper Cut a series of squares out of some brown paper or newspaper, with sides L varying between a few centimetres and a metre, for example. The thickness and density of the paper itself remain the same, provided we have used the same roll or the same newspaper when cutting out the squares. The mass M of the squares is thus a linear function of their area, in other words, of L. Screw the squares up one by one so as to make roughly spherical balls. What is the relation now between the mass M of these balls and their size (their mean diameter) R In other words, what is their apparent density It is intuitively clear that the answer will not be simple. There is little chance of obtaining the same kind of relation as before, i.e., M and at the same time, it would be difficult to make the balls so compact that all porosity was removed, and thereby obtain a relation of type M -... 

The apparent density (p) of PU foams derived from HL polyols were in a range of 0.04-0.075 gcm . Compression strength of the above PU foams was in a range 0.2-1.0 MPa and modulus of elasticity in the range 5-10 MPa. Glass transition temperature can be varied from 80 to 120°C. Thermal conductivity of the foam was 0.032-0.037 Wm which was smaller than in the usual commercial PU foams derived from petroleum. All the above physical properties and the cost-performance are better or compatible with commercial PU products. 

The remaining physical property of interest is particle density, usually expressed in kg/m [g/cm ]. Particle density refers to the mass per unit volume of the particle itself, not of the aerosol (the density of which is called concentration, as described in the next section). Liquid particles and crushed or ground solid particles have a density equal to that of their parent material. Smoke and fiime particles may have apparent densities significantly less than that predicted from their chemical composition. This is a result of the large amount of void space in their highly agglomerated structure, which may resemble a cluster of grapes. In this book particles are assumed to have standard density —that is, the density of water, 1000 kg/m [1.0 g/cm ]—unless specified otherwise. 

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