Calcium sulfate precipitated

There are numerous variations of the wet process, but all involve an initial step in which the ore is solubilized in sulfuric acid, or, in a few special instances, in some other acid. Because of this requirement for sulfuric acid, it is obvious that sulfur is a raw material of considerable importance to the fertilizer industry. The acid—rock reaction results in formation of phosphoric acid and the precipitation of calcium sulfate. The second principal step in the wet processes is filtration to separate the phosphoric acid from the precipitated calcium sulfate. Wet-process phosphoric acid (WPA) is much less pure than electric furnace acid, but for most fertilizer production the impurities, such as iron, aluminum, and magnesium, are not objectionable and actually contribute to improved physical condition of the finished fertilizer (35). Impurities also furnish some micronutrient fertilizer elements. 

Excess calcium hydroxide is precipitated by usiag carbon dioxide and the calcium carbonate, calcium hydroxide, and calcium phosphite are removed by filtration. The filtered solution is treated with an equivalent amount of sodium sulfate or sodium carbonate to precipitate calcium sulfate or carbonate. Sodium hypophosphite monohydrate [10039-56-2] is recovered upon concentration of the solution. Phosphinic acid is produced from the sodium salt by ion exchange (qv). The acid is sold as a 50 wt %, 30—32 wt %, or 10 wt % solution. The 30—32 wt % solution is sold as USP grade (Table 12) (63). Phosphinic acid and its salts are strong reduciag agents, especially ia alkaline solution (65). 

This PAG contains 1—2% sulfate as soluble calcium sulfate. Sulfate has been found to make PAG products unstable precipitate forms in less than one week at 50°G. Sulfate, however, has also been seen to increase PAG activity in water clarification and is thus intentionally added in one preparation (24). Precipitated calcium sulfate creates a sludge disposal problem. Typical Al content as AI2O2 of PAG products made from alum is 6 —8%. 

If the water is permanently hard due to MgS04, and lime is added, the precipitates calcium sulfate, CaS04, and magnesium hydroxide, Mg(OH)4, result, which are removed by sedimentation. 

Dual Alkali A flue-gas desulfurization process. The sulfur dioxide is absorbed in aqueous sodium hydroxide and partially oxidized, and this liquor is then treated with calcium hydroxide to regenerate the scrubbing solution and precipitate calcium sulfate. Developed by Combustion Equipment Associates and Arthur D. Little. 

Synonyms anhydrous calcium sulfate-anhydrite muriacite karstenite anhydrous gypsum anhydrous sulfate of lime hemihydrate-plaster of Paris annalin dried gypsum dried calcium sulfate dihydrate-gypsum alabaster satin spar mineral white terra alha satinite light spar selenite precipitated calcium sulfate native calcium sulfate... 

In a 1.0 L sample of 0.01 M potassium sulfate, K2S04 what is the minimum number of moles of calcium chloride, CaCl2, that can be added to the solution before the precipitate calcium sulfate forms Assume that the addition of calcium chloride has a negligible effect on the total volume of the solution. Ksp for CaS04 =... 

Recover the acetate by treating the filtered reaction mixture with dilute sulfuric acid, and then filter-off the precipitated calcium sulfate. Then, distill the mixture at 110 Celsius to recover the acetic acid formed by the addition of sulfuric acid. Note if using hydrochloric acid instead of sulfuric acid, evaporate the left over reaction mixture to dryness after the distillation (to remove acetic acid), so as to recover the calcium chloride. Calcium chloride can be heated using a Bunsen burner so as to form anhydrous calcium chloride, which makes a powerful drying agent. Second note acetic acid is a useful by-product and can be used in a variety of applications. 

SYNS ALABASTER ANNAUNE C.I. 77231 C.I. PIGMENT WHITE 25 GYPSUM GYPSUM STONE LAND PLASTER UGHT SPAR MAGNESIA WHITE MINERAL W HITE NATIVE CALCIUM SULFATE PRECIPITATED CALCIUM SULFATE SATINITE SATIN SPAR SULFURIC ACID, CALCIUM(2+) SALT, DIHYDRATE TERRA ALBA... 

PRECIPITATED BARIUM SULPHATE see BAPOOO PRECIPITATED CALCIUM SULFATE see CAX750... 

Calcium sulfate dihydrate alabaster Cal-Tab-, Compactroh, Destab-, E516 gypsum light spar mineral white native calcium sulfate precipitated calcium sulfate satinite satin spar selenite terra alba USG Terra Alba. 

Aqueous solutions of lithium sulfate and calcium nitrate are mixed, forming the precipitate calcium sulfate. 

The precipitation is generally controlled so as not to remove all Mg2+ from seawater, as doing so would result in the possibility of co-precipitating calcium sulfate. The theoretical solubility of calcium sulfate is reached when about 75% of the magnesium has been precipitated from seawater. Fortunately, supersaturated solutions of calcium sulfate are quite stable and precipitation does not normally represent a problem of contaminating the Mg(OH)2 precipitate and extraction of magnesium from seawater can be safely carried out to 95% removal. 

Dihydrate, native calcium sulfate precipitated calcium sulfate gypsum alabaster selenite terra alba satinite mineral white satin spar light spar. Lumps or powder, d 2.32. It loses only part of its water at 100-150. Sol in water very slowly sol in glycerol. Practically insol in most organic sol -vents. 

Isolation of the sulfonic acids as salts is usually carried out in one of two ways. In one the sulfonation mixture is taken up in water, neutralized with slaked lime, and filtered from the precipitated calcium sulfate, whereafter the filtrate, which contains the calcium salt of the sulfonic acid, is treated with sodium carbonate which converts the calcium into the sodium salt after filtration from calcium carbonate the solution is concentrated until crystallization occurs or, if necessary, evaporated to dryness. This procedure, termed chalking in industry, can be applied to all sulfonic acids except for the few cases such as l-amino-4-hydroxynaphthalene-2-sulfonic acid that give sparingly soluble calcium salts however, it is inconvenient because of the large volumes of liquid that must later be evaporated to avoid this precipitation of... 

High levels of sulfate (in excess of about 500 mg/1) cause the water to be aggressive towards concrete. Lime can be used to precipitate calcium sulfate, but the residual sulfate concentration in solution may still be too high. Treatment with sodium aluminate and lime at pH 9.5 to 10.0 precipitates a Ca Al S04 0H complex and reduces the sulfate level to well below 500 mg/1 [28.2]. 

Note that this represents a system in which a sparingly soluble solid (calcium citrate) reacts with a liquid to give a liquid product (citric acid) and a solid precipitate (calcium sulfate). 

Precipitated calcium sulfate. See Calcium sulfate dIhydrate... 

Gypsum stone Land plaster Light spar Magnesia white Mineral white Native calcium sulfate Pigment white 25 Precipitated calcium sulfate Terra alba... 

Sulfur dioxide reacts with calcium hydroxide (lime water) to produce a white precipitate, calcium sulfate(IV). 

Crystal formation is indicative of the presence of calcium. Confirmation requires adding several drops of stock H2SO4 to dissolve the precipitate. Add several milliliters of methanol and heat gently. Precipitate (calcium sulfate) will reappear. 

The main drawback is the resulting additional sulfates with their effect on precipitating calcium sulfate and increasing water corrosivity. 

The manufacturing process for citric acid involves fermentation followed by downstream purification. A common method of purification is to treat the products of fermentation with lime slurry followed by reaction of the solid calcium citrate formed with aqueous sulfuric acid to give an aqueous solution of pure citric acid and a precipitate of calcium sulfate. Note that the final purification step represents a system in which a sparingly soluble solid (calcium citrate) reacts with a liquid product (citric acid) and a solid precipitate (calcium sulfate). Experimental data of Anderson et al. (1998) plotted as conversion versus time showed a sudden rise in conversion at 85%, the exact point at which precipitation started. This clearly suggests autocatalytic action by the precipitating solid. 

What must be the concentration of sulfate ion in order to precipitate calcium sulfate, CaS04, from a solution that is... 

The humidified gas flows into the JBR where it bubbles through a shallow zone of absorbent. Sulfur dioxide is absorbed, oxidized, and reacted with calcium ions to precipitate calcium sulfate and form a gypsum slurry. Make-up limestone is added as 20% slurry, air is blown into the bottom reactor zones of the JBR to enhance the oxidation reactions, and the product gypsum is continuously withdrawn as a slurry containing about 15% CaS04 2H2O. 

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