Mineral Processing Data Research Articles

A quantitative approach to the influence of pyrite separation on Cu-processing tailings: a case study at Reps, Mirdita district, Albania

Sulfide-rich tailings are a well-known environmental threat due to their production of acid drainage (AD) and release of potential toxic elements (PTE) to the local environment. The presence of heterogeneous materials produces complex environmental signatures and complicates the quantitative prediction of contamination. The present work provides a method of quantifying such heterogeneities, starting from mineral processing data of the Reps, Mirdita (Albania) site. A quantitative flow sheet (QF) method was applied to a selected dump site of the Mirdita copper mining district where secondary pyrite separation had been used in the past. The site is subject to long-lasting (103 years) AD processes with significant release of PTE into the local environment. The tailings at the Reps site are divided into two classes based on the sulfide S content, respectively, represented by high-sulfide-content (S > 10 wt%) materials (hS) and low-sulfide-content (S < 3 wt%) material (lS). The reconstruction of the QF allowed us to identify the hS tailings as the discharge of single-flotation processing lines. This material accounts for about 82% of the total potential H2SO4 production, even though it represents < 20% of the entire tailing discard. The QF is a useful tool for the evaluation of heterogeneity and consequently for the modeling of waste management within abandoned sites and in working plants. Given a good quantification, heterogeneity can in fact support the setting of pyrite separation lines or the separate management of pyrite-rich tailing dumps.

DISTRIBUTION OF RARE EARTH ELEMENTS IN METAMORPHIC ROCKS OF PLATTENKALK GROUP AT CENTRAL CRETE, GREECE

Within the metamorphic rocks of the Plattenkalk Group, in an occurrence at Tallaia Mountains, central Crete, light rare earth elements Cerium and Lanthanum are found. The studied rare earths are seen in an epidote group mineral, allanite. Scanning Electron Microscopy of the samples showed clearly the crystals of allanite (prekinematic crystals) and their grain size. Mineral processing was conducted for the size fractions: (&lt;10 μm), (10-212 μm) and (212-1000 μm), according to the magnetic properties and grain size of allanite. After magnetic separation of the fraction (&lt;10 μm) and (212-1000 μm) rare earths Ce and La were observed to have higher concentrations in the magnetic products. In conclusion, (according to the microscopic and mineral processing data) the optimum grain size for the beneficiation of allanite is the size fraction (10-212 μm).

Justification and development of innovative technologies for integrated processing of complex ore and mine waste

The article presents the theoretical and experimental research findings aimed to create a basis for the development of innovative integrated processing technologies for complex ore and mine waste. It is found that introduction of nonmechanical energy treatment by an accelerated electron beam in the ore dressing circuits increases rebellious mineral processing data. The features of a flotation unit process are analyzed from the viewpoint of improvement of collecting and selecting abilities of a reagent and relationship between these abilities and molecular structure of the reagent. The authors define flotation activity of reagents and offer a flotation contact formation criterion. It is proved to be effective and promising to use magnesium- and manganese-bearing minerals for sorption purification of mine effluents in order to reduce metal loss in the wastewater discharge and to minimize damage of natural water bodies.

Analysis of chromite processing plant data by first order autoregressive model

Many mineral processing data can be monitored by a time series model. This research presents results of analysis and simulations of a chromite processing plant data determined by time series model. The plant data obtained by shift to shift include feed grade, concentrate grade, tailing grade, Cr/Fe ratio in concentrate. All the chromite processing data were found stationary over time. The autocorrelation was high for feed grade and Cr/Fe ratio. Weaker autocorrelation was observed for concentrate grade and tailing grade. Autoregressive integrated moving average (ARIMA, 1,0,0) or first order autoregressive (AR, 1) model, was found to fit all data very well. The models obtained have been also shown to be used for the near future estimation of these data. The time constant which is an indicator of sampling frequency of the data sets were determined. It was found that sampling frequency was enough for concentrate and tailing grade and their original values can be used in process control charts for monitoring. On the other hand, the sampling frequency should be reduced for feeding grade and Cr/Fe ratio for the same aims hence ARIMA residual charts were more suitable to monitor their values.

Application of multivariate tools to mineral processing data analysis and modeling: Flotation case

This paper summarizes work on the application of multivariate methods such as principal component analysis (PCA), projection to latent structure (PLS), and neural networks (NN) to process data analysis and modeling. Potential applications dealing with a flotation circuit are addressed with particular attention to the comparison of results obtained from the application of these multivariate techniques.

Reconciliation of mineral processing data containing correlated measurement errors

Steady-state values of stream properties (species flowrates) of a mineral processing circuit are usually estimated by averaging values sampled during a given time interval. A major source of data inaccuracy is the integration error, i.e. the error generated by the dynamic variations of the stream properties around their steady-state values. The paper shows that these sampling errors are significantly reduced by appropriate reconciliation methods based on material conservation equations. The optimal error compensation is obtained by minimizing a quadratic function where the weighting factors take into account the integration error covariance from stream to stream and species to species. The method is illustrated for a flotation circuit modelled by a state-space representation. The data variance reduction is compared for different weighting strategies of a quadratic reconciliation criterion. For the studied system, it seems that ignoring measurement error correlation, using a standard weighted least-squares criterion instead of the optimal quadratic function, does not degrade too much the ability of the reconciliation procedure to reduce the data variance.

A two-tier approach to the mass balance of multi-level mineral processing data. Part 2: Splicing of stream flows and global balance over a circuit

In the second stage of a new 2-tier approach to mass balancing, an algorithm is employed for splicing together the hierarchy of material flows within the streams that connect the nodes of a circuit in a manner that ensures reconciled and consistent data with minimum deviations from measured values and performance indices. The smoothened data are extracted by minimization of an error function in which the weighting factors for data points and performance indices can be adjusted to alter the distribution of errors in order to emphasize different flows selectively. Qualitative criteria for reliability of the smoothened data are proposed. For demonstration of the 2-tier method, two sets of flotation plant data are mass balanced. The results indicate that this technique could be a versatile and reliable solution to the problem of reconciling and analyzing plant scale mineral processing data.

A two-tier approach to the mass balance of multi-level mineral processing data. Part 1: Performance index and local balance around a node

The most reliable estimate of the performance index of a node, defined as the ratio of flow rates of a component in an exit stream and the feed stream, is obtained by a local mass balance around the node using data pertaining to only those flows that are linked directly to it. It is argued that these performance indices provide useful underpinnings for the global mass balance of multi-nodal mineral processing circuits. Based on this reasoning a new 2-tier method of mass balancing is proposed in which errors are distributed over the reconciled data not only with least possible deviations from measured values but also with minimum perturbations of performance indices of the individual nodes. The method entails estimations of performance indices, followed by their incorporation in a set of mass balance equations that splice together in a consistent manner the exit and entry streams connecting the nodes of the network. In Part 1 of this communication, an algorithm is presented for mass balance around a node and computation of the associated performance indices. For demonstration, two sets of plant data, having multi-level hierarchical flow structures are reconciled. The possible role of the performance index for assessing the quality of the measured data and detailed node-by-node analyses of the circuit performance is briefly discussed.

Redundancy analysis of complex sets of mineral processing data for mass balance computation

The study deals with the analysis of the feasibility of mass balance calculations for complex set of mineral processing data involving the measurement of flowrates, slurry dilution, liquid composition, solid composition, particle size distribution, assays within particle size classes etc… A method is presented for determining the unmeasurable variables which are calculable, and the measured variables which are redundant i.e. adjustable by any least squares procedure. The approach, which is called redundancy analysis, is based on the linearization of the system of mass conservation equations and on its decomposition in a row-echelon form. A global and a hierarchical procedures are proposed and illustrated on a simple mineral processing flowsheet for which a complex set of data is available.

An efficient algorithm for mineral processing data adjustment

The Mineral Processing Material Balance problem and the available computer packages for automated solution are outlined. Current solution techniques require considerable storage space to solve most practical problems. In this paper, we introduce a novel implementation based on existing formulations which allows large problems to be solved on a personal computer. A prototype package of this approach is discussed in detail and comparisons are made with an existing package on standard test problems. The treatment of the special cases which arise in material balance problems are discussed and test examples are included.

Mass balance calculations around mineral processing units using composition analyses within particle-size classes

This paper proposes an extension to an already available mass balance algorithm for mineral processing data. A typical set of data which can be processed by the proposed method contains flowrates measurement, particle-size analyses, global chemical analyses and, simultaneously, chemical analyses within particle-size classes. The method which is developed is based on a suboptimal approximation of a weighted least-squares procedure where the mass conservation equations, including the coherency constraints between the chemical analyses within particle-size class and the global analyses, act as constraints of the optimization problem. An illustration for the grinding circuit of a uranium-bearing phosphate ore is given.