Design and Optimisation of Flotation Circuits with Large Cells

The recent trend of flotation plant design with cells as large as 300 m3 is mainly driven by economic considerat-ions such as lower capital, operating and maintenance costs. Large cells offer distinct economic advantages, but poses major challenges as flotation plant design consi-derations are signcantly different from that of the tradi-tional circuits with small cells. The conventional empirical scale-up relationships are not applicable for circuits with large cells. This is mainly due to the lack of understanding of metallurgical and design scale-up principles of large cells. In addition, large cell operation is not well understood The present trend of installation of fewer cells in a bank requires each cell to be operated very efficiently and tolerance for cell inefficiencies is very low

A general scheme for the effective-mass Schrodinger equation and the generation of the associated potentials

A systematic procedure to study one-dimensional Schr\"odinger equation with a position-dependent effective mass (PDEM) in the kinetic energy operator is explored. The conventional free-particle problem reveals a new and interesting situation in that, in the presence of a mass background, formation of bound states is signalled. We also discuss coordinate-transformed, constant-mass Schr\"odinger equation, its matching with the PDEM form and the consequent decoupling of the ambiguity parameters. This provides a unified approach to many exact results known in the literature, as well as to a lot of new ones.Comment: 16 pages + 1 figure; minor changes + new "free-particle" problem; version published in Mod. Phys. Lett.

Well-posedness for degenerate third order equations with delay and applications to inverse problems

[EN] In this paper, we study well-posedness for the following third-order in time equation with delay <disp-formula idoperators defined on a Banach space X with domains D(A) and D(B) such that t)is the state function taking values in X and u(t): (-, 0] X defined as u(t)() = u(t+) for < 0 belongs to an appropriate phase space where F and G are bounded linear operators. Using operator-valued Fourier multiplier techniques we provide optimal conditions for well-posedness of equation (0.1) in periodic Lebesgue-Bochner spaces Lp(T,X), periodic Besov spaces Bp,qs(T,X) and periodic Triebel-Lizorkin spaces Fp,qs(T,X). A novel application to an inverse problem is given.The first, second and third authors have been supported by MEC, grant MTM2016-75963-P. The second author has been supported by AICO/2016/30. The fourth author has been supported by MEC, grant MTM2015-65825-P.Conejero, JA.; Lizama, C.; Murillo-Arcila, M.; Seoane Sepúlveda, JB. (2019). 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The empirical prediction of bubble surface area flux in mechanical flotation cells from cell design and operating data

In the operation of mechanical flotation cells, the dispersion of gas into fine bubbles may be expressed by three indicators : bubble size, gas holdup and superficial gas velocity. Taken together, these properties determine the bubble surface area flux (S) in the cell, which has been found to have a strong correlation with the flotation rate constant (k). Previous work by the authors has indicated that it is possible to predict the value of k for a known ore in a cell from a knowledge of the bubble surface area flux generated in that cell. In order to make good use of this finding, an empirical model has been developed to predict S in mechanical flotation cells, using data from extensive pilot industrial scale test programs. The model is able to predict S from cell operating conditions, impeller design and feed properties. The model has been validated for different types and cell sizes, impeller types and ore types, in different independent investigations carried out at several concentrators in Australia and South Africa. This paper outlines the development of the model, the parameter estimation, and the validation using a number of additional data sets

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell part 2: Effect on gas holdup

Gas holdup was measured at different locations in a 2.8 m portable industrial scale subaeration flotation cell, treating zinc cleaner feed at Hellyer Concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems, and operated over a range of air flow rates and impeller speeds. The gas holdup was found to increase with increase in impeller speed as well as with increase in air flow rate, the manner in which it increased depended on the impeller type. Values ranged from 2% to 33%, with the greatest values produced by the Outokumpu impeller

Modelling of the Mt Isa rougher-scavenger copper flotation circuit using size-by-liberation data

A flotation model developed at the Julius Kruttschnitt Mineral Research Centre was used to predict the performance of copper rougher and scavenger circuits at the copper concentrator at Mount Isa Mines. The model describes the kinetic response of an ore in a flotation cell in terms of ore floatability, cell characteristics and froth recovery. The floatability parameters of the rougher feed ore were obtained directly from a detailed plant survey. Flotation analysis was carried out for twenty different size-by-liberation classes to account for the effects of particle size and liberation on flotation. This paper investigates the capability of the model to predict the flotation behavior of 20 different size-by-liberation classes in the rougher and the scavenger banks

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell. Part 5: Validation of k - Sb relationship and effect of froth depth.

A previous investigation carried out by the authors at the Hellyer concentrator, using a 3 m cell fitted with four different impellers treating plant zinc cleaner feed ore, suggested a linear correlation between flotation rate constant k and bubble surface area flux S. The relationship between k and S was found to be independent of impeller type. This paper describes an investigation at the Scuddles concentrator in Western Australia to validate the findings at Hellyer for a different ore. Unlike the Hellyer work for which only one froth depth was used, the Scuddles work was carried out at different froth depths using the same 3 m cell fitted in turn with three different impellers viz. Batequip, Dorr-Oliver and Outokumpu. The results confirmed the strong correlation between k and S at three different froth depths used for the study. Moreover, this relationship was found to be practically independent of impeller type. However, at shallow froth depth the k-S relationship was found to be linear, whereas at intermediate and deep froth depths the relationship was found to be non-linear with the froth playing an important role in the overall kinetics