PRECIPITATION OF COLLOID SILICA FROM HYDROTHERMAL SEPARATE BY COAGULANTS ADDITION ( KAMCHATKA , RUSSIA )
We have carried out the experiments on coagulation and precipitation of silica from the separate of Verkhne-Mutnovsky geothermal electric power plant (Mutnovskoe hydrothermal field). Silica precipitation from the water solution was conducted in two ways: by adding slaked lime CaO and by electrocoagulation treatment on aluminium electrodes. Silica precipitation with addition of slaked lime was carried out under laboratory conditions at the temperature of 20 and 96 °C. Сolloid and monomeric silica concentrations, solution pH, flakes sizes and physical-chemical properties of material precipitated with different quantities of added lime were determined. We also carried out series of experiments on solution treatment of mixed type: addition lime with freshly precipitated flakes, and addition lime with sea water. In the experiments on electric coagulation, current intensity and distance between electrodes were changed. Dependence of silica concentration on treatment duration was studied. Quantities of electric energy and anode aluminium consumed for reducing of silica concentration to a certain level were obtained. The results of our experiments can be used for developing of technological scheme of silica precipitation and utilization optimal for Verkhne-Mutnovsky geothermal electric power plant.
SILICA COAGULATION AND PRECIPITATION IN HYDROTHERMAL SOLUTION ( KAMCHATKA , RUSSIA )
Studied were the processes of coagulation and precipitation of silica in the hydrothermal solution. Experiments were carried out on colloid silica coagulation and precipitation by various types of metal cations. Residual concentrations of silica and cations in the treated solution were determined, as well as pH and amount of Ca, Mg, Al and Fe in the settled material depending upon the coagulants consumption at 20°C and 96°C. Stability of colloid silica in hydrothermal solution was studied, as well as the mechanism of coagulation and precipitation of silica by metal cations.
Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin, Texas
The Mississippian Barnett Formation of the Fort Worth Basin is a classic shale-gas system in which the rock is the source, reservoir, and seal. Barnett strata were deposited in a deeper water foreland basin that had poor circulation with the open ocean. For most of the basin's history, bottom waters were euxinic, preserving organic matter and, thus, creating a rich source rock, along with abundant framboidal pyrite. The Barnett interval comprises a variety of facies but is dominated by fine-grained (clay- to silt-size) particles. Three general lithofacies are recognized on the basis of mineralogy, fabric, biota, and texture: (1) laminated siliceous mudstone; (2) laminated argillaceous lime mudstone (marl); and (3) skeletal, argillaceous lime packstone. Each facies contains abundant pyrite and phosphate (apatite), which are especially common at hardgrounds. Carbonate concretions, a product of early diagenesis, are also common. The entire Barnett biota is composed of debris transported to the basin from the shelf or upper oxygenated slope by hemipelagic mud plumes, dilute turbidites, and debris flows. Biogenic sediment was also sourced from the shallower, better oxygenated water column. Barnett deposition is estimated to have occurred over a 25-m.y. period, and despite the variations in sublithofacies, sedimentation style remained remarkably similar throughout this span of time.