Three-Dimensional Modeling of Tailings Beach Shape

Abstract: Tailings (mining waste) disposal is a significant consideration for the mining industry, with the majority of the ore processed in most mining operations ending up as tailings. This creates large volumes of tailings, which must be handled and stored responsibly to avoid potential environmental catastrophes. The most common form of tailings storage facility is the impoundment, where tailings are contained within a basin, with beaches forming around the perimeter of the impoundment and a pond standing in the middle. A relatively new method of tailings storage is to create a “stack,” whereby the tailings solids form a large heap, with the discharge of tailings slurry from the apex of the heap. This method of tailings storage is finding greater popularity as the industry seeks to reduce the amount of water discharged with the tailings, and usually features the discharge of non‐segregating tailings slurry that flows turbulently in its own self‐formed channel down the tailings beach. It is of significant interest for mine operators and tailings engineers to be able to predict the shape of the beach that forms in either of these disposal scenarios. The key to being able to do this relies on a method of prediction of the beach slope. In this article two new beach shape models are presented for the three‐dimensional (3‐D) geometric modeling of the beach surface of a tailings stack that has been formed through the variable discharge of a non‐segregating slurry that periodically changes in its composition, whereby the overall discharge output is defined as a sequence of smaller finite periods of steady uniform discharge, each having its own resulting beach slope. A beach slope model previously presented by the authors has been used here to predict the applicable beach slope for each finite discharge regime. The shape models presented here present two different methods for the compounding of the individual tailings deposits that are generated by each of these finite discharge regimes. Historic tailings discharge data is run through both models, and the shapes predicted by the models are compared with aerial survey data of real tailings stacks. This work not only presents a method of tailings stack shape prediction, but also a plausible theory for explaining the concavity of tailings beaches. The models also have the potential to be developed further for the 3‐D modeling of tailings beaches formed in other types of storage facilities, such as impoundments or valleys.     

The thermal performance of window coverings in a whole house test facility with single-glazed sash windows

The residential sector is responsible for 29% of the total energy consumption of the UK, with 62% of this energy being used for space heating. Heat loss through the fabric of building elements is a crucial factor in the energy efficiency of homes, and a wide number of studies have looked at physical interventions to improve the energy efficiency of existing buildings, commonly called retrofit. This research considers the impact of window coverings on reducing heat loss from homes, a measure that is not commonly considered an energy efficiency intervention. Although the amount of glazing varies widely between homes, all windows are a significant factor contributing to heat loss. While physical changes such as double and triple glazing can improve the energy performance of buildings, the impact of curtains and blinds is not well characterised. Previous research into window coverings has been undertaken using laboratory tests, such as hotbox and small climatic chamber environments. This study presents the impact of window coverings on heat loss within a unique whole house test facility. This allows for a better replication of a real heating system and the effects that it has on localised heat transfer. This gives a more detailed picture of in situ performance, similar to that which may be found in the field.     

Photochemical degradation of thermoplastics

The general mechanism of polymer photodegradation is outlined, and various aspects are then discussed with reference to polyolefins, particularly polyethylene. It is shown that various impurities accelerate degradation and that carbonyl groups play a complex role in the process. Polyolefins can be stabilised against photodegradation by incorporation of suitable u.v. stabilisers or pigments, and the principles involved, including the synergism between u.v. stabilisers and antioxidants, are discussed.     

Smart Objects as Building Blocks for the Internet of Things

The combination of the Internet and emerging technologies such as near-field communications, real-time localization, and embedded sensors lets us transform everyday objects into smart objects that can understand and react to their environment. Such objects are building blocks for the Internet of Things and enable novel computing applications. As a step toward design and architectural principles for smart objects, the authors introduce a hierarchy of architectures with increasing levels of real-world awareness and interactivity. In particular, they describe activity-, policy-, and process-aware smart objects and demonstrate how the respective architectural abstractions support increasingly complex application.     

Rapid Determination of Dextrose Equivalent by Cryoscopy

This paper describes the development of a novel method for determination of Dextrose Equivalent of Malto-dextrins and glucose syrups. The new method uses depression of freezing point as a measure of the number of molecules in solution; Dextrose Equivalent is also a measure of the number of molecules in solution. The advantages of the cryoscopic method are its inherent rapidity (2 min per determination), its precision and the fact that previous expertise is not required.