Calcium sulfate solution

The filtration behavior of asbestos fibers is evaluated through a drainage test using, generally, a saturated calcium sulfate solution. This test is... 

Fig. 1. Scanning electron micrograph of dried crystals of 5200 ppm calcium sulfate solution containing (a) zero, (b) 10, and (c) 25 mg/L of added...

For the lithium carbonate and calcium sulfate solutions operation with boiling apparently does not cause earlier visible scaling than with nonboiling conditions, other things being equal. Possibly scale is formed earlier but is obscured by the vapor bubbles. 

The slurry leaving the crystallizer is filtered to produce (i) a filter cake containing 96% calcium sulfate crystals and the remainder entrained saturated calcium sulfate solution, and (ii) a filtrate solution saturated with CaS04 at 30 C that also contains dissolved calcium nitrate. The filtrate is split, with a portion being recycled to mix with the solid calcium carbonate to form the slurry fed to the reactor, and the remainder being sent to the wastewater treatment facility. 

Crystallization from supersaturated solutions can occur by two processes, formation of new crystals or nucleation and growth on existing crystals. The internal surfaces of the scrubber can provide nucleation sites, thus resulting in scale formation. For many crystal systems, growth will occur without nucleation if suflBcient seed crystals are provided. Work by other investigators (3) has shown that supersaturated calcium sulfate solutions can be effectively desupersaturated by circulation of 1-5% gypsum seed crystals. 

CuAAsstiN, H. C. 1981. Estimation of calcium sulfate solution rate and effective aquifer surface area in a groundwater system near Carlsbad, New Mexico. Ground Water 19 287-97. 

Magnesium sulfate and calcium sulfate solutions of equal concentrations show approximately the same electrical conductivity [9]. If one compares electrical conductivity of the saturated calcium sulfate solution with the conductivity of various standard solutions of magnesium sulfate (see E6.5), one finds consistency in the concentration of the saturated solution ... 

Accordingly, for the pure saturated calcium sulfate solution we know (see Fig. 6.6) ... 

If one is dealing with a diluted calcium sulfate solution, saturation can be attained in three different ways (see Point A in Fig. 6.6) One continues to... 

Procedure Mix several pinches of calcium sulfate with water leave the mixture to stand overnight the solution becomes clear, a big solid residue can be observed at the bottom. Dip the conductivity tester into distilled water, then into the saturated solution. Prepare a 0.1 molar magnesium sulfate solution and dilute it with the help of the graduated cylinder once at 1 2 and once at 1 10. Measure the conductivity of these solutions and compare with the conductivity of saturated calcium sulfate solution. 

Observation Saturated calcium sulfate solution shows a good electrical conductivity. The saturated solution and the 0.01 molar solution of magnesium sulfate produce similar reading on the conductivity tester. This concentration can therefore be used for the calculation of the solubility product of calcium sulfate. 

Data derived from gypsum solubility in sodium chloride, sodium sulfate, and calcium chloride solutions were used in addition to calcium sulfate solutions. 

All solutions except pure calcium sulfate solutions had data up to 2.0 molal ionic strength. 

Fig. IX-21. The histograms showing the distribution of contact strength between two crystals of calcium sulfate dihydrate in supersaturated calcium sulfate solutions upon varying a - the degree of solution supersaturation, and b - duration of contact, t [16,17]...

The study of scale deposition with and without vibration was limited to determination of the feasibility of scale prevention and removal by vibration of the heat transfer surface. Calcium sulfate solutions and sea water were used as scaling liquors calcium sulfate because of the difficulty of preventing its deposi-... 

The experimental apparatus consisted of a vertically mounted tube with liquor flowing in the surrounding annular space and steam condensing inside. The tube was vibrating in a transverse direction. Initial heat transfer coefficients without vibration for calcium sulfate solutions averaged 580 B.t.u./hr. sq. ft. ° F. 

After the tube was completely covered with scale, the coefficient was reduced to 335 B.t.u./hr. sq. ft. ° F., a reduction of 40%. Scaling experiments using calcium sulfate solutions with the inner tube vibrating laterally at frequencies of 33 and 94 c.p.s. and amplitudes of 0.35 and 0.045 inch, respectively, showed reductions in heat transfer coefficients of only about one half those experienced without vibration. 

Hydrated supersulfated cement is highly resistant to snlfate attack, and may be used in applications in which the concrete is exposed to highly concentrated sulfate solutions. TTie high sulfate resistance is dne to the fact that most or all of the AI2O3 (except that in the residual, non-reacted slag) is present in the form of ettringite, or is bound within the formed C-S-H phase, and is not available for a reaction with sulfate ions. Such sulfate resistance is limited to alkah and calcium sulfate solutions, or to moderately acid solutions (down to abont pH=3.5), in which the sulfate ions are present in the form of ammoninm sulfate or even as free sulfuric add of low concentrations. 

The bridging of gypsum crystals with fluorite, calcile, and quartz, as well as the bridging of these crystals with each other in supersaturated calcium sulfate solutions, was also studied. In some cases, the calcium sulfite solutions contained electrolytes and surfactants. 

Effect of the Mutual Crystallographic Orientation of CaS04 x 2H2O Crystals on the Probability of Their Bridging (Wi,) in Supersaturated Calcium Sulfate Solutions of Supersaturation a and the Time of Contact, t... 

Work of Formation, A, of the Contact Nucleus for Different Mutual Crystallographic Orientations of CaS04 x 2H2O Crystals in Contact in Supersaturated Calcium Sulfate Solutions for Four Values of the Supersaturation, a... 

The experiments were carried out using a supersaturated calcium sulfate solution a = 1.8 and the time of contact t = 1000 s and with the applied compressive force,/ of either 1 or 10 dyn. The results of the experimental studies showed in aU cases a sharp transition from contacts with a strength... 

Probability of Bridging (IV ) of Different Crystals in Supersaturated Calcium Sulfate Solutions (a = 1.8 f = 1000 s)... 

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