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A Critical Assessment On The Resources And Extraction Of Rare Earth Elements From Acid Mine Drainage, Christopher R. Vass
A Critical Assessment On The Resources And Extraction Of Rare Earth Elements From Acid Mine Drainage, Christopher R. Vass
Graduate Theses, Dissertations, and Problem Reports
Rare earth elements (REEs) are crucial to many modern products used in both civilian and defense applications. Currently, a reliable supply of these elements is uncertain with the clear majority of REE production and refining occurring predominately in China. Furthermore, domestic ore deposits with commercially attractive concentrations of REEs are uncommon in the United States. As a result, the identification of a domestic supply of these technology metals is essential not only for manufacturing consumer merchandise but also for national security. Recently, one promising source of REEs has been identified: coal and coal-byproducts. One of those is acid mine drainage …
Fundamental Mechanism Of Time Dependent Failure In Shale, Neel Gupta
Fundamental Mechanism Of Time Dependent Failure In Shale, Neel Gupta
Graduate Theses, Dissertations, and Problem Reports
In underground coal mines, mining activity disturbs the natural equilibrium state of in-situ stresses. The induced and in-situ stresses deform the rockmass surrounding the mine openings. Primary roof supports impede the deformation of the rockmass overlying the entries. However, failure can occur in the bolted rockmass, causing fatalities and injuries. The rockmass failure is erratic, and its occurrence often varies from a few days to months and years after the opening of the entry. One of the often-neglected factors in this process is the effect of time on the stability of mine openings, which can often be observed in the …
Time-Dependent Deformation And Associated Failure Of Roof In Underground Mines, Yuting Xue
Time-Dependent Deformation And Associated Failure Of Roof In Underground Mines, Yuting Xue
Graduate Theses, Dissertations, and Problem Reports
In underground coal mines, roof falls are a major contributor to injuries and fatalities. Studies have related the occurrence of roof fall to weak immediate roof, high horizontal stress, entry orientation, etc. An often-neglected factor in studies on this topic has been the influence of time-dependent behavior of the roof rock on roof falls. The time-dependent roof failure activity involves both intact and failed rocks. Numerical simulation techniques are available that include time-dependent behavior; however, they lack constitutive models that consider both the intact and the failed behavior of rock. In addition, input properties for the creep models only include …