Overloaded Thickener

Drive Assemblies The drive assembly is the key component of a sedimentation unit. The drive assembly provides (1) the force to move the rakes through the thickened pulp and to move settled solids to the point of discharge, (2) the support for the mechanism which permits it to rotate, (3) adequate reserve capacity to withstand upsets andtem-poraiy overloads, and (4) a reliable control which protects the mechanism from damage when a major overload occurs. 

Effectively an overloaded thickener. Rotating rake feeds sands to central underflow... 

Hydraulic cylindrical tank classifier Om tp (M-F) Hydraulic form of overloaded thickener. Siphon-Sizer (N-F) uses siphon to discharge underflow instead of rotating rake. 1.0 to 40 1.4 mm to 45 im (25 mm) 1 to 150 Not critical 0.4 to 15 20 to 35 0.75 to 11 Two-product device giving very clean underflow. Requires relatively little hydraulic water (2 t/t solids feed). Used for washing, desliming, and closed circuit grinding. 

Respiratory effects typically associated with inhalation of particulates and lung overload have been observed in animals. The pulmonary toxicity of alchlor (a propylene glycol complex of aluminum chlorhydrate), a common component of antiperspirants, was examined in hamsters in a series of studies conducted by Drew et al. (1974). A 3-day exposure to 31 or 33 mg Al/m3 resulted in moderate-to-marked thickening of the alveolar walls due to neutrophil and macrophage infiltration and small granulomatous foci at the bronchioloalveolar junction (a likely site of particulate deposition). A decrease in the severity of the pulmonary effects was observed in animals killed 3, 6, 10, or 27 days after exposure termination. Similar pulmonary effects were observed in rabbits exposed to 43 mg Al/m3 for 5 days (Drew et al. 

The above model was further employed to study observed patterns of cardiac hypertrophy. First, the initial size of the ventricle was consistent with that of a normal dog. Second, a pressure overload was created by raising mean aortic pressure. The model was then used to recompute ventricular size for the new afterload condition. Results show the classic wall thickening and increased wall thickness-to-diameter ratio (W/D), consistent with observed concentric hypertrophy. Third, volume overload was imposed by elevating cardiac output. In this case, the model predicted an increase in diameter with relatively little increase in the W/D ratio, referred to as eccentric hypertrophy. Lastly, the sarcomere function was impaired and its effect on the ventricle evaluated. An eccentric form of hypertrophy resulted. The diameter-to-length... 

Fig. 27.16. Thickening of the intralobular septa, which is a result of fluid overload in lymphatic vessels...

When the feed concentration Cp is greater than the critical concentration, the thickener is said to be overloaded. This situation is depicted in Figure 3.17. Here... 

Figure 3.19 Alternative total flux plot shape overloaded thickener...

In an overloaded thickener, the concentration in the bottom section of the thickener is equal to (when the total flux plot does not go through a minimum) ... 

Fig. 6.2.8. Pulmonary edema due to fluid overload in a 28-year-old woman after allogeneic HSCtransplantation. HRCT scan through upper lobes shows smooth septal thickening in a gravity-dependent distribution. The left interlobar fissure is also prominent due to subpleural edema. (With permission from Franquet et al. 2005a)...

---