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Materials Handling and Conveying
Published in B. K. Bala, Agro-Product Processing Technology, 2020
A bucket elevator consists of buckets attached to a chain or a belt that revolves around two pulleys, one at top and the other at the bottom. The vertical lift may range from a few meters to more than 50 m. Bucket elevators may be classified as (1) spaced bucket elevators and (2) continuous bucket elevators. Bucket elevators are efficient but more expensive. High efficiency results from the absence of frictional loss from sliding of materials on the housing.
Bucket Elevators and Bucket Carrierss
Published in Muhammad E. Fayed, Thomas S. Skocir, Mechanical Conveyors, 2018
Muhammad E. Fayed, Thomas S. Skocir
The bucket elevator is one of the few conveyors designed for the primary purpose of elevating material. The earliest recorded use of the bucket elevator dates back to the days of Babylon. Wicker baskets sealed with pitch were fastened to a rope strung between two wooden sheaves. The sheaves were turned by slaves. This system was used to elevate water for irrigation purposes.
A novel dry beneficiation process for coal
Published in International Journal of Coal Preparation and Utilization, 2022
Liang Dong, Ziming Wang, Enhui Zhou, Xuan Wang, Gongmin Li, Xuchen Fan, Bo Zhang, Chenlong Duan, Zengqiang Chen, Zhenfu Luo, Haishen Jiang, Yuemin Zhao
The separation principle of the ADMFB is illustrated in Fig. 1. Design parameters of the air dense medium fluidized bed (ADMFB) is shown as Table 1. Magnetite powder (0.074–0.3 mm) and coal fines (−0.5 mm) are used as the dense medium. A gas–solid fluidized bed is generated using compressed air. The bed density can be controlled to a value between the densities of clean coal and tailings by adjusting the content of coal fines in the dense medium. The coal fed into the ADMFB is separated based on the density difference between the clean coal and gangue. The separation density depends on the bed density. Clean coal floats on the bed surface and is transported to discharge outlet by clockwise rotating dialers and a counter-clockwise rotating bucket elevator in turn. Gangue sinks to the bed bottom, from where it is conveyed by a scraper conveyor to the discharge outlet. The ADMFB can be used for the dry beneficiation of coal with sizes ranging from 100–6 mm. The separation efficiency is approximately 93%, and the probable error E ranges from 0.05 to 0.08 g/cm3. The separation effect worsens with the decrease in coal size.
Modelling of pilot scale vertical roller mill operated in overflow mode
Published in Mineral Processing and Extractive Metallurgy, 2021
Loesche OGPmobile is a fully automated system. Measured parameters during operation can be followed from the control room. This unit can be operated in two different grinding modes named as air swept and overflow mode. In the overflow mode, there is an external two-stage air classification system consisting of static and dynamic types and separate from the mill body (Figure 1). This system was developed to reduce the specific energy consumption of the whole system since the material transportation is carried out mechanically instead of pneumatically. Overflow mode provides convenience for model development because it enables to collect the samples around the units involving in comminution, i.e. grinding and classification. Data obtained from the overflow mode grinding test was used for model development. During the operation, fresh feed is fed to the static classifier initially, and the fine product of it is directed to the dynamic classifier before the grinding action. The coarse streams of both static and dynamic classifiers are sent to the mill to be ground. Then the ground material is mixed with the fresh feed stream and is conveyed mechanically, e.g. belt conveyor, bucket elevator, to the static classifier again. Dynamic classifier fine product is collected as final product in a following bag filter.
Integrated maintenance policies for performance improvement of a multi-unit repairable, one product manufacturing system
Published in Production Planning & Control, 2021
James M. Wakiru, Liliane Pintelon, Peter Muchiri, Peter Chemweno
During the operation, as illustrated in Figure 3, a continuous evaluation of the system running hours is carried out. If the system running hours is not equal to the time between the occurrences of process stoppage and is equal to the time between PM interventions, it is assumed that a PM action is undertaken. Mathematically, this is denoted as (). This intervention exploits the economic dependence by clustering multiple units due for preventive maintenance, where a block replacement policy (BRP) is implemented. For example, the raw mill, fan, and bucket elevator can be maintained preventively considering one PM interval, since, they portray nearly similar inter-failure duration characteristics as revealed from data analysis. PM intervention is undertaken following a PM interval (900 h) moreover, repair time under preventive maintenance, of 7 + WEIB (5.89, 0.584), both derived from empirical data.