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Gravity Thickening
Published in Ko Higashitani, Hisao Makino, Shuji Matsusaka, Powder Technology Handbook, 2019
A thickener is a sedimentation basin that is employed to concentrate a slurry prior to filtration or centrifugation. Normally a larger fraction of the total liquid is removed in thickening than in subsequent operations. In most cases, the particles in a thickener settle collectively in the zone settling regime. As illustrated in Figure 5.18.4, the bottom part of a thickener is filled with a layer of settled solids, which increases in concentration with greater depths. A clarified liquid separates from the thickened liquid at the interface and is taken off at the top. A thickener therefore fulfills the dual function of providing a concentrated underflow and a clear liquid overflow. In designing a thickener, the areas needed for clarification and thickening are therefore examined separately. The larger of the two areas determines the size required to achieve the specified performance.
Gravity Separation/Sedimentation
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
A thickener is a sedimentation unit that operates according to the principle of gravity settling. Compared to other types of liquid/solid separation devices, a thickener’s principal advantages are Simplicity of design and economy of operationIts capacity to handle extremely large flow volumesVersatility, as it can operate equally well as a concentrator or as a clarifier
Equalization and Primary Treatment
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
Ronald G. Gantz, Janos Lipták, David H.F. Liu
Waste-activated sludge creates a handling problem in many treatment plants. It is a light, fluffy material, composed of bacteria, rotifers, protozoa, and enough filamentous organisms to make concentration difficult. The underflow from a final clarifier may only contain 1 % solids. Pumping this much water to digesters is inefficient and can lead to digester failure. Accordingly, wastewater treatment facilities use thickening devices to concentrate the sludge to 5 to 7% solids. In addition to gravitational thickeners used in the past, flotation and centrifugal thickeners are also used.
Analysis of settling performance of coal fines tailing polymer using central composite rotatable design optimization
Published in International Journal of Coal Preparation and Utilization, 2022
Conventional coal preparation (CPP) plants generate around 20% of the mined coal as less than 500 micron size (Hansdah, Kumar, and Mandre 2017; Kumar, Bhattacharya, and Mandre 2014, 2016; Parekh 2009) that is generally disposed due to high handling cost. Industrial dewatering circuit mostly contain a filter, cyclone, centrifuge; to lower the moisture level to 20-30% in the final dewatered product which reflect high capital and operating cost. Coal and mineral processing plant tailings usually contain colloidal particulate matters with a huge amount of clay materials that pose significant challenges in dewatering (Philip et al. 2011). Therefore, it is indispensable to choose a low-cost dewatering method usually by sedimentation in a thickener to make it feasible to reuse a huge volume of water present in dilute coal slurry (Sabah and Erkan, 2004). Thickeners are conventionally selected based on the settling rates of the slowest settling particles and conditions for minimum disturbance of the medium (water) through which the particles settle (Gupta and Yan 2006).
Preparation and characterization of emulgels loaded with sweet fennel oil
Published in Journal of Dispersion Science and Technology, 2020
Jenifer Santos, Nuria Calero, Julia García-Capitán, José Muñoz
A gelation agent can be added to the emulsion in order to form an emulgel system. There are several compounds used as thickeners or gelation agents such as polysaccharides, clays and oxide gels. Aerosil 200 is a fumed silica that form a 3D network in aqueous solutions.[17] Because of that, it is a great candidate to form an emulgel. It has been included in multitude of systems: rubbers, plastics, coatings, adhesives, cements, sealants and even in food products.[18–21] In addition, a recent study has pointed out the role of Aerosil 200 protecting an interface oil-water.[22] It was experimentally shown and theoretically justified that silica particles can attach at the oil-water interface and stabilize emulsions.[23–26] This has a similar behavior that emulsions stabilized by starch.[27] However, there is a lack of information about the stability of emulsions stabilized by Aerosil 200 with aging time greater than a week.
Clean fracturing fluids for tight reservoirs: opportunities with viscoelastic surfactant
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Xiaojiang Yang, Jincheng Mao, Zhangxin Chen, Yanan Chen, Jinzhou Zhao
Hydraulic fracturing techniques were proposed and the first job was performed in 1947 at the Hugoton Field (Carman and Cawiezel 2007). This job was done in a vertical well and it created a simple two-wing fracture. Since then, fracturing with a water-based fracturing fluid has been widely used in modern stimulation. Likewise, polymers like guar and their derivatives have been the most widely used thickeners. Recent technologies have allowed hydraulic fracturing to be applied in horizontal wells and have made multistage fracturing possible. Polymer-based fracturing fluids, such as the guar polymer, with their wall-building characteristics, can quickly form a layer of cake filter on crack faces thereby preventing further leakoff of the fluids into the surrounding bedrock. This means that the amount of fluid needed for the given length of a fracture is greatly reduced in comparison to a non-viscous fluid. The formation damage is also reduced.