scholarly journals Unsaturated mine tailings disposal

2021 ◽  
Vol 44 (3) ◽  
pp. 1-12
Author(s):  
Luciano Oldecop ◽  
Germán Rodari
Keyword(s):  
Mine Tailings ◽  
Void Ratio ◽  
Mine Wastes ◽  
Laboratory Studies ◽  
Air Drying ◽  
Tailings Disposal ◽  
Disposal Facility ◽  
Complex Process ◽  
Two Stages

Filtered tailings is the disposal technology that is most likely to yield an unsaturated state of the tailings. Such state has important benefits. A dam to contain the mine wastes is no longer needed, the risk of polluting seepage is minimized, and liquefaction of tailings is prevented. Filtering also allows most of the water mixed with the tailings to be recovered and reused in the process. The resulting material can be handled with traditional soil moving equipment to form a stack, for instance. While the idea is simple, the multiple phenomena involved in the tailings unsaturated disposal make up a complex process. The present work is based on a case study, the Casposo Mine filtered tailings disposal facility, located in the central Andes of Argentina. Throughout ten years of operation, a series of field and laboratory studies have been carried out to characterize the phenomena that intervene in the disposal of filtered tailings. Two stages were studied in detail: air drying upon tailings discharge and tailings compression under the weight of the subsequent lifts of the stack. Flocculant agents were found to have an outstanding influence in the tailings behaviour. Because of the multiple influencing factors, the process outcome (namely, the tailings water content and their void ratio) is highly variable. To deal with such variability, projects must include enough redundancy. In this regard, the case study’s incorporation of waste rock layers interspersed between tailings layers was a successful experience.

The Implementation of Biological Phosphorus and Nitrogen Removal with the Bio-Denipho Process on a 265,000 PE Treatment Plant

1992 ◽  
Vol 25 (4-5) ◽  
pp. 161-168 ◽  
Author(s):  
J. Einfeldt
Keyword(s):  
Nitrogen Removal ◽  
Treatment Plant ◽  
First Year ◽  
In Series ◽  
Design Loads ◽  
Last Stage ◽  
Two Stages ◽  
The City ◽  
Biological Phosphorus

A process, called Bio-Denipho, for combined biological phosphorus and nitrogen removal in a combination of an anaerobic tank and two oxidation ditches is described. In this process the anaerobic tank consisting of three sections working in series is followed by two oxidation ditches. These too are working in series, but with both inlet to and outlet from the tanks changing in a cycle. The Bio-Denipho process is described specifically for the process itself and as a case study for the implementation of the process on a 265,000 pe wastewater treatment plant for the city of Aalborg in Denmark. The plant was designed and erected in two stages and the last stage was inaugurated October 31,1989. Lay-out and functions for the plant is described and design loads, plan lay-out and tank volumes are given in this paper together with performance data for the first year in operation.

scholarly journals Optimization of Low Head Axial-Flow Turbines for an Overtopping BReakwater for Energy Conversion: A Case Study

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4618
Author(s):  
Antonio Mariani ◽  
Gaetano Crispino ◽  
Pasquale Contestabile ◽  
Furio Cascetta ◽  
Corrado Gisonni ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Control Strategy ◽  
Energy Production ◽  
San Antonio ◽  
Axial Flow ◽  
Complex Process ◽  
Low Head ◽  
Wave Power Conversion ◽  
And Control

Overtopping-type wave power conversion devices represent one of the most promising technology to combine reliability and competitively priced electricity supplies from waves. While satisfactory hydraulic and structural performance have been achieved, the selection of the hydraulic turbines and their regulation is a complex process due to the very low head and a variable flow rate in the overtopping breakwater set-ups. Based on the experience acquired on the first Overtopping BReakwater for Energy Conversion (OBREC) prototype, operating since 2016, an activity has been carried out to select the most appropriate turbine dimension and control strategy for such applications. An example of this multivariable approach is provided and illustrated through a case study in the San Antonio Port, along the central coast of Chile. In this site the deployment of a breakwater equipped with OBREC modules is specifically investigated. Axial-flow turbines of different runner diameter are compared, proposing the optimal ramp height and turbine control strategy for maximizing system energy production. The energy production ranges from 20.5 MWh/y for the smallest runner diameter to a maximum of 34.8 MWh/y for the largest runner diameter.

A hydrochemical and isotopic case study around a near surface radioactive waste disposal

2007 ◽  
Vol 95 (1) ◽  
Author(s):  
Zs. Szántó ◽  
É. Svingor ◽  
I. Futó ◽  
L. Palcsu ◽  
M. Molnár ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Waste Treatment ◽  
Radioactive Waste Disposal ◽  
Ion Chemistry ◽  
Continuous Transition ◽  
Near Surface ◽  
Disposal Facility ◽  
Treatment And Disposal ◽  
Site Characterisation

As part of the site characterisation program for the near surface radioactive waste treatment and disposal facility (RWTDF) at Püspökszilágy, Hungary, water quality and environmental isotope investigations have been carried out. Water samples for major ion chemistry, tritium,The chemical composition of groundwaters presented a continuous transition from waters situated on one side to waters on the top and on the other slope of the disposal suggesting the mixing of the three hydrochemical “endmembers”.Most of δ

Innovation Failure: Losing Sight of the Big Picture

2013 ◽  
Vol 14 (4) ◽  
pp. 301-306 ◽  
Author(s):  
Anna Fortoul Obermöller
Keyword(s):  
Teaching And Learning ◽  
Innovation Process ◽  
Multiple Perspectives ◽  
Passenger Car ◽  
Complex Process ◽  
Significant Step ◽  
Big Picture ◽  
Entrepreneurial Activities ◽  
The Impact

The Case Study section of the International Journal of Entrepreneurship and Innovation serves two purposes. First, the case studies presented are concerned with problematical issues that are pertinent to students of entrepreneurship. Thus they constitute appropriate teaching and learning vehicles on a variety of postgraduate and undergraduate programmes. Each case study is accompanied by a set of guidelines for the use of tutors. Second, it is envisaged that those engaged in entrepreneurial activities will find the cases both interesting and useful. The case of PSA Peugeot Citroën's electric passenger car is an example of an innovation perceived as a failure because of its disappointing sales volume. Yet, by limiting our assessment of the electric passenger car to a short-term perspective, we may miss out on an essential part of its value. As part of a wider innovation process, the electric passenger car project is a significant step for PSA in its expertise regarding electric vehicles. Key learning outcomes: (a) to understand that innovation is a complex process with fuzzy frontiers, both in time and space; (b) to understand that innovation is a long-term investment with spillovers into other projects; (c) to be aware of the multiple perspectives that may be adopted when examining innovation; and (d) to be aware of the impact of labelling a project a failure.

scholarly journals Revisiting the Organic Template Model through the Microstructural Study of Shell Development in Pinctada margaritifera, the Polynesian Pearl Oyster

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 370 ◽  
Author(s):  
Jean-Pierre Cuif ◽  
Yannicke Dauphin ◽  
Gilles Luquet ◽  
Kadda Medjoubi ◽  
Andrea Somogyi ◽  
...  
Keyword(s):  
Pearl Oyster ◽  
Nacreous Layer ◽  
Prismatic Layer ◽  
Pinctada Margaritifera ◽  
Microstructural Study ◽  
Leading Role ◽  
Complex Process ◽  
Gathering Data

A top-down approach to the mineralized structures and developmental steps that can be separated in the shells of Pinctada margaritifera was carried out. Detailed characterizations show that each of the two major layers usually taken into account (the outer prismatic layer and the inner nacreous layer) is actually the result of a complex process during which the microstructural patterns were progressively established. From its early growing stages in the deeper part of the periostracal grove up to the formation of the most inner nacreous layers, this species provides a demonstrative case study illustrating the leading role of specifically secreted organic structures as determinants of the crystallographic properties of the shell-building units. Gathering data established at various observational scales ranging from morphology to the nanometer level, this study allows for a reexamination of the recent and current biomineralization models.

Field Performance and Analysis of 3-m-Diameter Induced Trench Culvert under a 19.4-m Soil Cover

2008 ◽  
Vol 2045 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Bethanie A. Parker ◽  
Rodney P. McAffee ◽  
Arun J. Valsangkar
Keyword(s):  
Pressure Distribution ◽  
Earth Pressure ◽  
Field Performance ◽  
Overburden Pressure ◽  
Vertical Pressure ◽  
Earth Pressures ◽  
Design Loads ◽  
Horizontal Pressure ◽  
Two Stages

An induced trench installation was instrumented to monitor earth pressures and settlements during construction. Some of the unique features of this case study are as follows: (a) both contact and earth pressure cells were used; (b) part of the culvert is under a new embankment and part was installed in a wide trench within an existing embankment; (c) a large stockpile was temporarily placed over the induced trench; and (d) the compressible material was placed in two stages. The maximum vertical pressure measured in the field at the crown of the culvert was 0.24 times the overburden pressure. The maximum horizontal pressure measured on the side of the culvert at the springline was 0.45 times the overburden pressure. The column of soil directly above the compressible zone settled approximately 40% more than did the adjacent fill. The field results at the crown and springline compared reasonably with those observed with numerical modeling. However, the overall pressure distribution on the pipe was expected to be nonuniform, the average vertical pressure calculated by using numerical analysis on top of the culvert over its full width was 0.61 times the overburden pressure, and the average horizontal pressure calculated on the side of the culvert over its full height was 0.44 times the overburden pressure. When the full pressure distribution on the pipe is considered, the recommended design loads from the Marston–Spangler theory slightly underpredict the maximum loads, and the vertical loads control the design.

scholarly journals Client's immersed and distanced speech and therapist's interventions in emotion-focused therapy for depression: an intensive analysis of a case study

2016 ◽  
Vol 19 (2) ◽  
Author(s):  
Ana Bela Couto ◽  
Eunice Barbosa ◽  
Sara Silva ◽  
Tiago Bento ◽  
Ana Sofia Teixeira ◽  
...  
Keyword(s):  
Laboratory Studies ◽  
Clinical Change ◽  
Emotion Focused Therapy ◽  
Client Variables ◽  
Observational Measures ◽  
Helping Skills ◽  
System A ◽  
Therapeutic Dialogue ◽  
The Relationship

Previous laboratory studies have explored the importance of participants adopting an immersed or distanced perspective in the analysis of their experiences. These studies concluded that distancing allows analyzing emotions in a healthier way and immersion leads to higher vulnerability. However, in psychotherapy, the relationship between these perspectives and clinical change has been less investigated. The present study aims to contribute to understanding how these variables evolve during psychotherapy and also to explore the therapist’s contributions to this process. This study analyzes a good-outcome case of emotion-focused therapy for depression through two observational measures of psychotherapy process: the measure of immersed and distanced speech – which identifies client’s adoption of an immersed or distanced stance when talking about their problems – and the helping skills system – which identifies therapist’s interventions focused on exploration, insight or action. Results showed a decrease of immersed speech and an increase of distanced speech along the process, with a higher frequency of exploration skills preceding both types of client’s speech. Finally, the evolution of therapist’s and client’s speech showed a reasonable flexibility of therapeutic dialogue throughout the sessions, in particular due to the evolution of client variables (evidencing a higher diversity of behaviors).

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