Langbeinite calcium

If the contents of water-soluble K2O and Na20 are known, it is necessary only to calculate AT, and TV, from them, and R, and then to carry out stages 2 and 4. From AT, TV, and C the quantities of individual sulphate phases may be estimated as described in Section 3.5.6. In the example given, the calculation indicates that the sulphate phases account for all the SO3, 0.07% of Na20, 0.28% of KjO and 0.04% of CaO. These probably occur as aphthitalite (0.6%) and calcium langbeinite (0.1%). 

Sulphate ion is also supplied by the clinker, especially as alkali sulphates or calcium langbeinite, and Ca " ions are supplied by the clinker phases, including free lime. The alkali sulphates provide a highly available source of S04, but the alkali cations, or more probably the OH" ions that they produce, have additional effects (Section 7.6.3). 

Calcium langbeinite in interstitial phase Excess sulfate over equivalent alkalies (Long, 1983)... 

Potassium and sodium sulfates and their double sulfates with calcium and magnesium occur naturally in various salt lakes. Potassium sulfate also occurs in certain volcanic lava. Its double salt with magnesium occurs in nature, as the mineral langbeinite. 

Limestone and dolomite are widely used to supply calcium and magnesium when these nutrients are needed. Other magnesium materials include magnesium silicate, calcined brucite (MgO), magnesium sulfate, and langbeinite (K2SO4 2MgS04). 

The solution obtained by reaction of nitric acid with phosphate rock can be treated by the addition of a soluble sulfate to precipitate part or nearly all of the calcium as calcium sulfate (gypsum or hemihydrate). In commercial processes, ammonium sulfate, potassium sulfate, and sulfuric acid have been used. Langbeinite (K2S04 2MgS04) has been used experimentally. The calcium sulfate may be separated by filtration or allowed to remain in the product. In most plants, the calcium sulfate is removed to produce a higher grade product. Chemical reactions are ... 

Alsharari, M. A. (1999). Reclamation of Fine-Textured Sodic Soil Using Gypsum, Langbeinite and Calcium Chloride. PhD dissertation, Univ. of Arizona, 179 pp. 

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