Dolomite specification

Thermal Properties. Because all limestone is converted to an oxide before fusion or melting occurs, the only melting point appHcable is that of quicklime. These values are 2570°C for CaO and 2800°C for MgO. Boiling point values for CaO are 2850°C and for MgO 3600°C. The mean specific heats for limestones and limes gradually ascend as temperatures increase from 0 to 1000°C. The ranges are as follows high calcium limestone, 0.19—0.26 dolomitic quicklime, 0.19—0.294 dolomitic limestone, 0.206—0.264 magnesium oxide, 0.199—0.303 and calcium oxide, 0.175—0.286. 

Undesirable solids are drilled cuttings and those solids sloughed into the borehole. They usually occur in all size ranges from colloidal to coarse. The specific gravity of commonly encountered drilled solids ranges from 2.35 (shale), through 2.65 (sand), 2.69 (limestone), to 2.85 (dolomite) see Table 4-57 [29]. 

Xanthated fatty acid mixture is a new line of collectors, specifically designed for beneficiation of oxide copper ores that contain dolomitic and carbonaceous gangue minerals [19]. This collector was developed after extensive laboratory development testwork. The effectiveness of this collector was compared to a standard xanthate collector in a series of continuous locked cycle tests (Table 19.5). 

As a specific example of the problem, let us calculate the equilibria for an actual case study a deep water from the Sarcidano region (Sardinia, Italy) in equilibrium with Mesozoic dolomites (Bertorino et al., 1981). The compositions in mEq/1 of water sampled in a drilled well are listed in table 8.8. The in situ temperature is 21 °C we assume here that the in situ T is 25 °C at 1 bar, to simplify calculations. We also assume for the sake of simplicity that the main ion species in solution are HCO3, Mg, Ca, CO3, OH, and H, and that all Ca and Mg are in the ionic forms Ca and Mg. ... 

The steady-state luminescence spectra of three different plastics are characterized by blue luminescence with Amax = 445-465 nm, while much broader liuninescence band with yellow color characterizes the dolomite rocks. These spectra are different, but not enough to differentiate between them from big distance. The decay properties have been also checked in order to improve the selective feature. It was found that luminescence intensity of rocks in the blue part of the spectrum is drastically diminished after specific delay time, while the decrease of intensity in the yellow part of the spectrum is mush more moderate. Liuninescence intensity of all plastics also diminishes after such delay, nevertheless remaining mush stronger then intensity of rocks luminescence in the blue part of the spectrum. The comparison of plastic and rock time-resolved spectra in specific time window clearly demonstrate that they are absolutely different, which made confident discrimination possible (Fig. 7.3). 

We may now examine specific information from chemical analyses of the Great Lakes (7, 8, 13) to determine to what degree the variations of the proposed model fit the actual data. Rather than consider all of the variables at once, it is simpler to consider smaller portions to get a better idea of what actually is happening. We shall look at calcium carbonate equilibria, dolomite equilibria, phosphate equilibria, and silicate equilibria. 

The most common reagent for the extraction of trace metals from carbonate phases in soil is lmoll-1 sodium acetate acidified to pH 5 with acetic acid (Kunze, 1965). Carbonate phases effectively attacked include dolomite, but the presence of acetic acid also promotes the release of metals specifically sorbed on inorganic and organic substrates (Tessier et al., 1979). 

The Mg to Ca surface ratios for dolomite in both seawater solutions were statistically identical. A Mg to Ca surface ratio of 3 is predicted from a simple site-specific adsorption model, and is in reasonable agreement with observed values. 

The sulfur sorbent that has received the most attention is limestone because of its widespread availability and low cost. Unfortunately the conversion of limestone to calcium sulfate results in a volumetric increase, and it can be readily shown (8 ) that for particles that do not permit volumetric expansion on reaction the maximum conversion attainable is about 59 percent (the value is dependent on the specific volumes of reactant and product). This constraint can be avoided by use of dolomite, since the MgO is not sulfated and the void volume produced by the decomposition of MgCO and CaCO is sufficient to permit complete calcium utilization, but at the expense of an added weight of sorbent and added energy requirement for calcination. The above conclusions follow from consideration of the stoichiometric relations ... 

TABLE 7.1. Specific Surface Area and Acid-Dissolution Kinetic Parameters of Calcite, Dolomite, and Limestone Samples... 

The dolomite used has a typical chemical composition of 44% MgCOs and 53% CaCOs. The raw dolomite was charred in a furnace at 8S0°C for a period of 6-18 hours producing a CaCOa/MgO porous structure. Specific surface area was measured using BET nitrogen adsorption employing a Sorptomatic 1900. 

The use of dolomite and lime in the gasifier favours the formation of NH, probably by catalysing the conversion of HCN to NHj [ I ]. This can be an advantage for the overall process since it facilitates methods for downstream cleaning that are specific for NHj. 

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