Alkali sulfate

For details of the extraction procedures for alkali sulfate from clinker, x-ray diffraction analysis, and specific chemical requirements for the formation of these phases, see Gartner and Tang (1987). 

Relationships of alkali sulfate to delayed ettringite formation (DBF) and reported expansion therefrom are unlikely, according to Miller and Tang (1996). 

For most studies, XRD remains a dependable and rapid mode of analysis for establishing the varieties of sulfate phases. However, their locations, crystal sizes, and, to some extent, their abundances are best described by microscopy. Some of the alkali-sulfate phases are listed below  

Calcium sulfate inverts at 1195°C to alpha anhydrite, which is monoclinic with lamellar twinning like plagioclase and has an n of 1.50, n of 1.56, and birefringence of 0.060. Beta anhydrite is obtained by heating 

Fly ash is composed of tiny spherical and ellipsoidal beads and bubbles of glass, typically containing other phases. Other common constituents are irregular carbon particles, hematite, magnetite, tridymite, cristobalite, quartz, mullite, and spinel. It may contain small amounts of belite, aluminate, and free lime. The RI of the glass is 1.50 to 1.63. 

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Sulfates. Indium metal and its oxides dissolve in warm sulfuric acid to give a solution of the trisulfate [13464-82-9], In2(S0 2- It is a white, crystalline, deUquescent soHd, readily soluble in water that forms double salts with alkaLi sulfates and some organic substituted ammonium bases. Concentration of the acidified trisulfate solution produces indium acid sulfate crystal [57344-73-7], In(HS0 2> other reaction conditions give basic sulfates. 

Sodium and potassium are restricted because they react with sulfur at elevated temperatures to corrode metals by hot corrosion or sulfurization. The hot-corrision mechanism is not fully understood however, it can be discussed in general terms. It is believed that the deposition of alkali sulfates (Na2S04) on the blade reduces the protective oxide layer. Corrosion results from the continual forming and removing of the oxide layer. Also, oxidation of the blades occurs when liquid vanadium is deposited on the blade. Fortunately, lead is not encountered very often. Its presence is primarily from contamination by leaded fuel or as a result of some refinery practice. Presently, there is no fuel treatment to counteract the presence of lead. 

Excess sodium hydroxide present can also be troublesome as the alkali reacts with the SO3 present in the gas stream to form a range of alkali sulfates which in themselves are highly corrosive to metallic components. In addition, the combination of alkali sulfate -l- V2O5 can result in compounds having melting points as low as 600°E. This situation is only encountered when alkali is present in amounts in excess of that which can react stoichiometrically with V2O5, since the formation of alkali vanadates is favored over that of alkali sulfates. 

In addition to the four compounds discussed above, the final Portland cement may contain gypsum, alkali sulfates, magnesia, free lime and other components. These do not significantly affect the properties of the set cement, but they can influence rates of hydration, resistance to chemical attack and slurry properties. 

Muller et al. 215) have isolated ssCrOl", 50CrO, s MoOl, 100M0O4" in isomorphous alkali sulfates and measured the metal isotope shifts for vs Fs)-In another paper, the chromate(VI) ion was isolated in a KBr lattice with different divalent cations in conjunction (276). In this case it was quite obvious that ion pairs were isolated in the host lattice. This possibility must always be taken into consideration. 

The compound also is prepared by treating alkali sulfate, such as sodium or potassium sulfate with a solution of mercury(ll) nitrate. 

Red monoclinic crystals density 2.59 g/cm loses all its water molecules at 120°C decomposes at 700°C sparingly soluble in water, less soluble in hot water dissolves in concentrated sulfuric acid forming Y(HS04)s insoluble in alkalis forms double salts with alkali sulfates. 

The replacement of Portland cement by fly ash class F (ASTM C 618) has been found to reduce the rate of slump loss in a prolonged mixed concrete, and the extent of the reduction is greater with increased cement replacement (Fig. 7.37). Fly ash also was found to be beneficial in reducing slump loss in concretes with conventional water-reducing and retarding admixtures [95], The effect of fly ash on reducing slump loss can be attributed to chemical and physical factors. It was found that the surface of fly ash particles may be partly covered with a vapor-deposited alkali sulfate that is readily soluble [103, 104], Thus the early hydration process of Portland cement is effected because sulfate ions have a retarding effect on the formation of the aluminates. Indeed, fly ash was found to be a more effective retarder than an... 

The double alkali sulfates will probably nut be alums. 

The 7-lactones described below can be prepared in good yield in a one-step process by radical addition of primary fatty alcohols to acrylic acid, using di-tert-butyl peroxide as a catalyst. A patent claims a high yield when the reaction is carried out in the presence of alkali phosphates or alkali sulfates [196]. 

The Preparation of Alums.—Since aluminum sulfate is a commercial chemical, the aluminum alums can be prepared by crystallizing the salt along with the double molecular weight of an alkali sulfate. Chromium and ferric sulfates are not well crystallized and have limited uses, so that they are not readily obtained. The preparation of their alums involves the preliminary preparation of the sulfates themselves. 

The molten salt systems listed earlier are among those most frequently used as solvents for electroanalytical chemistry. This list is by no means inclusive because in many cases there are subspecies of these melt systems that have not been covered that enjoy equal or only slightly less popularity than the systems that were discussed. In addition, there are a number of molten salts used for electrochemistry that have not achieved the level of popularity of the systems described in the preceding sections. Molten alkali sulfates, for example, Li2S04-K2S04 eutectic (80.0-20.0 mol%, mp = 535°C) [55,56], are included in this category. 

Iron(II) sulfate forms double salts of formula M2S04 FeS04 hH O with alkali sulfates. Iron(II) ammonium sulfate [7783-85-9] (Mohr s salt),... 

Sulfates in coal ash are derived from two sources (1) sulfates (generally of calcium or magnesium) present as such in the coal sample, and (2) sulfates formed by the absorption of sulfur oxides by the basic constituents of the ash during incineration of the coal and occurring mainly as calcium sulfate but also, to some extent, as alkali sulfates. The quantity of sulfates from the first source is usually very small and, in normal cases, can generally be neglected in comparison with those derived by absorption. Consequently, a determination of the sulfate in the ash enables a measure of the quantity formed during incineration to be established. 

Figure3-33. Tetrahedral sulfurconfigurations /ra/w the left sulfones sulfuric acid alkali sulfates.

Fractional precipitation is similar to fractional crystallization technique but takes advantage of basicity differences and solubility differences. Separation of yttrium from yttrium earths by fractional precipitation is an example of differences in basicity. Separation of yttrium earths from cerium earths by double alkali sulfate precipitation in the form of double sulfates is an example of fractional precipitation. 

From trends in the enthalpies and entropies of sublimation for the other alkali sulfates (4), we would estimate a H (1200 K)... 

Ozonization of Thio-y-pyrones (6). Thio-y-pyrone and 2,6-dimeth dthio-y-py-rone react with ozone at a slower rate than the corresponding y-pyrones. The thio-y-pyrones take up 3 molecules of ozone. Not only do the C=C bonds react with ozone, but oxidation of the sulfur atom also occurs. When the reaction product of the ozonization is treated with dilute alkali and hydrogen peroxide, the solution contains alkali sulfate in an amount corresponding to the sulfur content of the thiopyrone. 

Natural anhydrite is extracted by open cast or underground mining. A hardenable product is obtained by fine grinding to < 0.2 mm particles and the addition of activators (ca. 2% heavy metal or alkali sulfates, or calcium hydroxide) to natural anhydrite. 

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