Source Of Gypsum Research Articles

Rate of dissolution of gypsum from different sources and its effect on water infiltration of soil

Five sources of gypsum (pure, mined and three industrial) were pressed into pellets and their dissolution rate when suspended in water compared by measuring electrical conductivity of the stirred solution. Pellets of industrial phosphogypsum from Phalaborwa, Potchefstroom and Richards Bay all dissolved more rapidly than mined gypsum from Kimberley but more slowly than pure gypsum. Electron microscopy of partially dissolved pellet surfaces indicated surface texture—as influenced by crystallinity of the gypsum—as the probable factor controlling dissolution rate. The mined and industrial gypsum samples were applied in their original condition (Phalaborwa is granular) at a rate of 10 000 kg ha−1 to the surface of a dispersive, crusting (but non-sodic) soil placed in trays tilted at a 5% slope and exposed to distilled water applied as simulated rain (44 mm h−1). The fraction of the 50-mm rain which infiltrated was: control 17%, Kimberley 42%, Phalaborwa 44%, Richards Bay 62% and Potchefstroom 68%. Electrical conductivity of the drainage water was: Kimberley 110; Phalaborwa 160; Richards Bay 200 and Potchefstroom 240 mS m−1. Both granule size and crystallinity limit the effectiveness of gypsum as a crust inhibitor. Phalaborwa proved to be as effective as Potchefstroom during a second rain applied after the soil surface had dried. This was ascribed to the evaporative recrystallization of dissolved gypsum as a surface efflorescence. Because their attrition by dissolution and erosion will be slower, at least some coarse fragments may be desirable to prolong the benefit from dressing the soil surface with gypsum.

The sources of Mycenaean gypsum

The sources of gypsum, used as an interior building material in the Bronze Age palaces of Crete, some buildings at Akrotiri in Thera and in the mainland palaces at Mycenae and Tiryns, have been attributed by archaeologists to geological deposits in Crete itself, on mainland Greece, or in the Ionian islands of Zakynthos and Kephallenia. Isotopic analyses of sulphur and strontium have been used to characterize the Greek gypsum deposits and to investigate the provenance of gypsum excavated at Knossos, Hagia Triadha, Akrotiri, Mycenae and Tiryns. These analyses show that central Cretan gypsum deposits of Pliocene age supplied the Minoan palaces, Akrotiri on Thera and the palace at Mycenae. In contrast, Tiryns obtained its gypsum from Triassic gypsum deposits, either on Crete or in the Ionian islands or on mainland Greece.

Utilization of residuals from flue gas desulfurization

AbstractDiverse large‐scale sources of FGD gypsum, the plentiful waste by‐product from SO2 emissions cleanup in major industrial countries, are characterized in terms of properties including crystal form and contained impurities that affect commercial usability. New technology to expand FGD gypsum usage by economical conversion to alpha hemihydrate of calcium sulfate is detailed.

Calcium‐supplying Characteristics of Two Gypsum Materials on Southeastern Coastal Plain Soils

AbstractField studies were conducted on two soils to study the manner in which finely and coarsely divided gypsum materials supplied Ca to the soil depth where peanut (Arachis hypogaea L.) fruit absorb Ca. The finely divided material was characterized chemically as CaSO4 · 2H2O, approximately 72% CaSO4 or 20.2% Ca and physically as having 88% of the particles < 0.25 mm in diameter. The coarsely divided material was characterized chemically as CaSO4, approximately 92% CaSO4 or 26.5% Ca and physically as having 82% with particle diameters < 4.2 mm, but > 0.5mm. Each material was applied at three rates in randomized complete block experiments. At approximately 3‐week intervals, composite soil samples were collected at the 0‐ to 5‐, 5‐ to 10‐, and 10‐ to 15‐cm depths and extracted with acid (0.05N HCl + 0.025N H2SO4) extractant which was analyzed for Ca.The amount of Ca transported to a given soil depth was found to be related to the magnitude, order, and frequency of rainfall events. Generally, several small rainfall events resulted in accumulation of Ca near the soil surface, whereas, larger rainfall events resulted in a reduced Ca concentration near the soil surface for both materials. The fine gypsum material was found to be more effective in supplying Ca to the soil depth where peanut fruit are absorbing it early in the growing season than the coarser material.Dissolution of gypsum sources consisting of different particle sizes and subsequent transport of Ca into the fruiting zone of peanuts was not always closely related to the total amount of rainfall. Either the finely or coarsely divided gypsum could supply more Ca to the fruiting zone depending on the rainfall pattern.

Sulphates in African Inland Waters

MR. R. S. A. BEAUCHAMP states, “… the only sources of gypsum in East Africa are those contained in the Cretaceous deposits along the coast of Tanganyika Territory …”.