Dolomite, absorption

Chemical scrubbing systems for SO/ absorption fall into two broad categories (a) Disposable systems and (b) regenerative systems. Typical of systems in use for a number of years are those that use an aqueous slurry of an insoluble caldum compound, which can be discarded after use. Disposable 02-removal systems use aqueous slurries of finely ground materials, such as lime, limestone or dolomite, to produce a mixture of insoluble sulfites and sulfates. On passing through the scrubber, S02 from the waste gas dissolves to form sulfurous acid S02 ... 

The concentration profile of oxygen in the bed is fixed by establishing apriori a value for b as 4.5 and that of a as obtained from the assumed values of carbon conversion and sulfur absorption efficiencies. For a given oxygen profile the reaction rate constant, k3(To), and the size of the dolomite feed are varied. The changes in both of these parameters affect the value... 

The generation rate of sulfur dioxide reduces with the decrease in carbon conversion efficiency and hence the limestone requirement also decreases. A reduction in the carbon conversion efficiency from 99.5 to 70.0% causes a reduction in dolomite requirement from 27.5 to 18.9 g/s for a 99% sulfur absorption efficiency. 

Sanitary and also some domestic ware is manufactured from materials showing low water absorption (e.g. about 0.5%). Their composition is similar to that of porcelain and earthenware, but apart from feldspar or feldspar pegmatite, the mix also frequently contains other components serving as fluxes (limestone, dolomite, talc). The technology is essentially the same, the firing temperatures are 1250—1300 °C. Compared with porcelain, these materials lack translucency. Their surface is provided with white or coloured glazes. 

Natural waters in the acid range can arise by absorption of acidic atmospheric gases (Chap. 2) or by the accumulation of humic acids on percolation through peaty soils. They have the potential to mobilize elements of the rocks and soils, through which they flow. In limestone, dolomites, and similar rock formations, calcium, magnesium, and other elements may be dissolved, in the process increasing the pH. At the same time, these processes raise the hardness of water (e.g., Eqs. 4.22 and 4.23). 

The minerals found in United States coals continue to be studied with the availability of improved instrumental procedures such as x-ray diffraction, infrared absorption, and scanning electron microscopy beyond the traditional optical and chemical mineralogical techniques as applied to thin sections, polished pellets, and isolated particles. The minerals may be grouped into the silicates (kaolinite, illite montmorillonite, and chlorite), the oxides (quartz, chalcedony, hematite) the sulfides (pyrite, marcasite, and sphalerite) the sulfates (jarosite, gypsum, barite, and numerous iron sulfate minerals) the carbonates (ankerite, calcite, dolomite, and siderite) and numerous accessory minerals (apatite, phosphorite, zircon, rutile, chlorides, nitrates, and trace minerals). 

When the recommended daily allowance (RDA) for calcium is not met by the diet is (particularly in women), supplementation in the form of calcium salts is recommended. Calcium salts vary widely in calcium content by weight, calcium gluconate has 9%, calcium lactate has 13%, and calcium carbonate has 40% calcium. Absorption of calcium from salts may vary calcium carbonate is the most poorly absorbed. Bone meal and dolomite are not recommended sources of calcium, since they may contain lead, arsenic, mercury, and other toxic metals. A potential complication of excessive calcium intake is formation of urinary tract stones this risk may be reduced by ample fluid intake. 

Figures 2-4 summarize the currently available information on the stoichiometry and minor or trace element concentration of saddle dolomite in carbonates, sandstones and carbonate-sandstone mixtures. Saddle dolomite shows a variable elemental composition, from near-stoichiometric to calcian dolomite and/or ankerite. The bulk of published major, minor and trace element data on saddle dolomite are based on electron microprobe analyses, although some authors used powder X-ray diffraction analysis to determine the dolomite stoichiometry. Others used spectrometric techniques (e.g. atomic absorption) to analyse for trace elements. We found it difficult to evaluate this published information because some authors report bulk analyses of several crystals, whereas others report intracrystalline elemental variations. Moreover, analyses are often incomplete (e.g. wt% Fe and Mn no data on Ca and Mg) and cannot be directly recalculated in terms of mol%. Further, some authors report a single measurement whereas others list hundreds of data points.

Los Alamos tuff is so porous that water readily flows through it. Basalt being much less porous was used mainly in surface absorption experiments in which fissures and cracks were simulated. Finally, the relatively impervious Chicago dolomite was used 1n conjunction with a high pressure apparatus which was found necessary to effect movement of water through the material. The two latter rocks mentioned also were tested to observe the alteration of binding ability in the presence of salt solutions. 

Absorption of 237pu on Niagara Limestone (Chicago Dolomite) Data for Samples in a 0.5M Solution of NaCl at Equilibrium. 

Oil absorption 35 g/100 g talc surface area 12 m /g specific gravity 2.8 g/cm composition >97% talc, <3% dolomite. Source Silverline 403 Data Sheet. 

Flexural modulus, effect on, 147 Flexural strength, effect on, 147 In limestones, 146 In dolomite, 146 Mohs hardness, 146 Moisture content, 146 Muscovite, 146 Oil absorption, 146 Particle size, 146 Reinforcing effects, 146 Speciflc gravity, 146 Thermal properties, effect on, 146 Water absorption... 

The steady state concentration of magnesium species in a scrubber system using dolomitic lime will depend on several factors, including magnesium content of the limestone, system purge rate, and limiting maximum solubility. Whatever the concentration obtained, it seems likely to have a significant beneficial effect on absorption. 

Assessing the combination of factors under item (1) led us to estimate the make-up rate of fresh dolomite acceptor of 2.0% of the circulation rate. The average activity of the dolomite was assumed to be such that 70 mole % of the total CaO was converted to CaC03 before the acceptor was returned to the regenerator. The driving force for CO2 absorption was assumed to be 0.35 atm. 

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