Data reconciliation for mineral and metallurgical processes : Contributions to uncertainty tuning and dynamic balancing : Application to control and optimization

Pour avoir un fonctionnement de l'usine sûr et bénéfique, des données précises et fiables sont nécessaires. D'une manière générale, une information précise mène à de meilleures décisions et, par conséquent, de meilleures actions pour aboutir aux objectifs visés. Dans un environnement industriel, les données souffrent de nombreux problèmes comme les erreurs de mesures (autant aléatoires que systématiques), l'absence de mesure de variables clés du procédé, ainsi que le manque de consistance entre les données et le modèle du procédé. Pour améliorer la performance de l'usine et maximiser les profits, des données et des informations de qualité doivent être appliquées à l'ensemble du contrôle de l'usine, ainsi qu'aux stratégies de gestion et d'affaires. Comme solution, la réconciliation de données est une technique de filtrage qui réduit l'impact des erreurs aléatoires, produit des estimations cohérentes avec un modèle de procédé, et donne également la possibilité d'estimer les variables non mesurées. Le but de ce projet de recherche est de traiter des questions liées au développement, la mise en œuvre et l'application des observateurs de réconciliation de données pour les industries minéralurgiques et métallurgiques. Cette thèse explique d’abord l'importance de régler correctement les propriétés statistiques des incertitudes de modélisation et de mesure pour la réconciliation en régime permanent des données d’usine. Ensuite, elle illustre la façon dont les logiciels commerciaux de réconciliation de données à l'état statique peuvent être adaptés pour faire face à la dynamique des procédés. La thèse propose aussi un nouvel observateur de réconciliation dynamique de données basé sur un sous-modèle de conservation de la masse impliquant la fonction d'autocovariance des défauts d’équilibrage aux nœuds du graphe de l’usine. Pour permettre la mise en œuvre d’un filtre de Kalman pour la réconciliation de données dynamiques, ce travail propose une procédure pour obtenir un modèle causal simple pour un circuit de flottation. Un simulateur dynamique basé sur le bilan de masse du circuit de flottation est développé pour tester des observateurs de réconciliation de données et des stratégies de contrôle automatique. La dernière partie de la thèse évalue la valeur économique des outils de réconciliation de données pour deux applications spécifiques: une d'optimisation en temps réel et l’autre de commande automatique, couplées avec la réconciliation de données. En résumé, cette recherche révèle que les observateurs de réconciliation de données, avec des modèles de procédé appropriés et des matrices d'incertitude correctement réglées, peuvent améliorer la performance de l'usine en boucle ouverte et en boucle fermée par l'estimation des variables mesurées et non mesurées, en atténuant les variations des variables de sortie et des variables manipulées, et par conséquent, en augmentant la rentabilité de l'usine.To have a beneficial and safe plant operation, accurate and reliable plant data is needed. In a general sense, accurate information leads to better decisions and consequently better actions to achieve the planned objectives. In an industrial environment, data suffers from numerous problems like measurement errors (either random or systematic), unmeasured key process variables, and inconsistency between data and process model. To improve the plant performance and maximize profits, high-quality data must be applied to the plant-wide control, management and business strategies. As a solution, data reconciliation is a filtering technique that reduces impacts of random errors, produces estimates coherent with a process model, and also gives the possibility to estimate unmeasured variables. The aim of this research project is to deal with issues related to development, implementation, and application of data reconciliation observers for the mineral and metallurgical industries. Therefore, the thesis first presents how much it is important to correctly tune the statistical properties of the model and measurement uncertainties for steady-state data reconciliation. Then, it illustrates how steady-state data reconciliation commercial software packages can be used to deal with process dynamics. Afterward, it proposes a new dynamic data reconciliation observer based on a mass conservation sub-model involving a node imbalance autocovariance function. To support the implementation of Kalman filter for dynamic data reconciliation, a procedure to obtain a simple causal model for a flotation circuit is also proposed. Then a mass balance based dynamic simulator of froth flotation circuit is presented for designing and testing data reconciliation observers and process control schemes. As the last part of the thesis, to show the economic value of data reconciliation, two advanced process control and real-time optimization schemes are developed and coupled with data reconciliation. In summary, the study reveals that data reconciliation observers with appropriate process models and correctly tuned uncertainty matrices can improve the open and closed loop performance of the plant by estimating the measured and unmeasured process variables, increasing data and model coherency, attenuating the variations in the output and manipulated variables, and consequently increasing the plant profitability

Computer aided Design and Optimization of Mineral Processing Plants by a State of the Art Simulator

Tata Research Development and Design Centre (TRDDC) has developed a state of the art mineral processing simulator called SimL8. It performs modelling, simulation and optimisation functions and provides viable strategies for enhancement of the performance of mineral processing plants. A number of case studies on plant diagnostics, grinding,classification, flotation and pressure filtration are taken up to demonstrate the utility of modelling and simulation on SimL8 platform

The characterisation of the lead flotation circuit at Black Mountain Mining (Pty) Ltd. using the floatability component model approach

Black Mountain Mining (Pty) Ltd. (BMM) is a base metal operation that has been producing chalcopyrite-, galena- and sphalerite-bearing concentrates for over 30 years. Silver is recovered in the concentrates as a result of elemental substitution within the crystal lattice of chalcopyrite and galena minerals. The primary objective of this study was to adapt the Floatability Component Model (FCM) as a simplified proof-of-concept model for the Lead flotation circuit of the BMM Concentrator based on plant- and laboratory-scale data. The model obtained, using the FCM approach in conjunction with the Woodburn and Wallin (1984) methodology, should give insight to the metallurgical team regarding the performance of the circuit based on the data pertaining to the feed characteristics of the Lead flotation circuit. Additionally, as a result of the known association of silver with galena minerals, an objective of the study was to be able to predict the response of silver based on the response of galena minerals. The model for the Lead flotation circuit of BMM Concentrator was developed in a single MS Excel spreadsheet and it was important that the raw data used to develop the model could be obtained easily, inexpensively and in a manner that was not disruptive to the operation

Towards the development of an integrated modelling framework underpinned by mineralogy

The mining industry is under increased pressure from many stakeholders to be forward thinking in its approach to sustainability. This requires a holistic approach to address techno-economic, environment and social issues, rather than just focusing on individual aspects of sustainability practice. The ability to do so requires an integrated modelling framework, underpinned by mineralogy so that the effect of ore variability on one or more of these factors can be simultaneously evaluated and optimised. This study focuses on the steps towards the development of this proposed framework using a case study of a polymetallic sulfide ore flotation circuit. The initial focus in the framework development is on integrating the techno-economic and the environmental aspects of sustainability. Thereafter the framework is used to consider a variety of scenarios evaluating the balance between techno-economic value and environmental burden. A sampling exercise was conducted around the intermediate and terminal streams of the flotation circuit processing polymetallic sulfide ore. All samples were characterised using both chemical assays and mineralogy (QEMSCAN). This formed the input data for the development of an ore specific element to mineral conversion (EMC) recipe that converts chemical assays to mineral grades. The EMC technique has the advantage of being fast, inexpensive and can be used on a routine basis. The recipe for this specific polymetallic sulfide ore was designed to calculate nine minerals in four different rounds, using least square method in the first two rounds and non-negative least square in the last two rounds. Sulfide minerals (chalcopyrite, galena and sphalerite) were calculated in the first round, barite was estimated in the second round, silicate minerals (garnet, biotite and quartz) were determined in the third round and pyrrhotite and magnetite were calculated on the last round. Data validation for EMC was performed by comparing calculated mineral grades against the measured mineral grades obtained from QEMSCAN. The accuracy was determined by evaluating the R2 value, the results were comparable as the R2 value was above 0.95 for all minerals. Mineral grades obtained from EMC of the assayed streams were used to carry out a mineral mass balanced of the flotation circuit. From the results, mineral grade and recovery were calculated and were used to evaluate metallurgical performance across the flotation circuit. The chalcopyrite (copper) concentrate was diluted with pyrrhotite (26 wt. %). The sphalerite concentrate (zinc) had the highest grade (94 wt. %) followed by galena (lead) with a concentrate grade of 85 wt. %. Sphalerite and galena achieved high recoveries over 90 %. From analysis of the flotation performance of the circuit, the results demonstrate an opportunity to improve the copper (chalcopyrite) concentrate quality. The diluted concentrate is likely to attract penalties during downstream processing (e.g. smelter) due to the presence of impurities (pyrrhotite). The concentrate can be upgraded by rejecting pyrrhotite in the first stage of the copper circuit. In addition, the mass balanced mineralogy results were used to calculate a theoretical potential of the final tailings to generate acid rock drainage (ARD). The ARD method used is based on the relative abundance of acid generating sulfide minerals (chalcopyrite, galena, sphalerite and pyrrhotite) and other minerals with the theoretical potential to neutralise the acid generated. The net mineralogically calculated acid producing potential was estimated as 46.4 kg H₂SO₄/ton. To further demonstrate the usefulness of the framework, a mineral splitter function was used to model the flotation circuit and test different hypothetical scenarios. Two hypothetical scenarios were investigated relative to the current operating condition of the flotation circuit. A sensitivity analysis on both scenarios was conducted to assess the effect of feed ore variability. The pyrrhotite feed grade was varied between 10 and 100 % of the base case and all sulfide mineral recoveries were kept constant. Scenario I considered improving Cu (chalcopyrite) concentrate grade in the Cu circuit by rejecting pyrrhotite. A Monte Carlo simulation was carried out by varying the pyrrhotite recovery to concentrate from a minimum of 2 % to a maximum of 18 % in the mineral splitter function. The results showed an increase in pyrrhotite grade in the final zinc tailings and an increase in the mineralogically calculated ARD potential (up to 53.9 kg H₂SO₄/t for tailings). Scenario II considered the installation of a magnetic separator to concentrate pyrrhotite in the final tailings and achieved a net acid producing potential of 15.2 kg H₂SO₄/t, which was lower than scenario I. The sensitivity analysis of scenario I showed a correlation between increased pyrrhotite feed grade with mineralogically calculated ARD potential (89.6 kg H₂SO₄/t). The results from sensitivity analysis of scenario II were lower were than scenario I (28.6 kg H₂SO₄/t). This shows that installation of a magnetic separator has the potential to mitigate ARD formation and produce a potential economic magnetite concentrate by-product. In conclusion this study has shown how mineralogy can be integral in developing an integrated modelling framework for simultaneously assessing techno-economic and environmental performance. The developed framework demonstrated the possibility of simultaneously balancing the trade-off, improving grade and mitigating the risk of ARD formation. It is a conceptual starting point for a new approach to traditional process mineralogy studies to start implementing sustainable development aspects on the operational level

The effect of ore blends on the mineral processing of platinum ores

Includes abstract.Includes bibliographical references (leaves 96-101).This thesis investigates the effect of ore blends on milling and flotation performance. Anglo Platinum's Waterval UG2 concentrator in Rustenburg processes ore from various shafts

HIGH FIDELITY KINETIC MODEL FOR FLOTATION: APPLICATIONS TO RARE EARTH ELEMENTS AND COPPER/MOLYBDENUM SEPARATIONS

A high-fidelity kinetic model was developed to identify and elucidate the effects of varying principle froth flotation parameters on the sub-processes that occur within and between the flotation zones. Whereas traditional models fail to adequately address froth recovery and recovery by entrainment, the high-fidelity model defines these phenomena based on an improved understanding of the pulp/froth interface. Solution chemistry considerations that govern rare earth mineral separation by flotation were identified, characterized, and optimized. Application of novel surfactants such H205 and salicylhydroxamic acid (collectors) and dimethyl glycol monobutyl ether (depressant) was evaluated to define optimal flotation conditions. The effect of pressure on fine particle entrainment was also studied because, with certain rare earth mineral ores, sufficient mineral liberation is not achieved at nominal flotation particle sizes. Pressure can be applied to produce the small bubble sizes required for fine particle flotation. The correct solution chemistry for flotation (and not entrainment) can then be utilized for the selective recovery of rare earth minerals. The predictive high-fidelity kinetic model was developed using experimentally derived and statistically significant rate equations and was confirmed through application to copper/molybdenum sulfide and rare earth mineral ore samples. The parametric models identified ideal flotation conditions that optimized the recovery of rare earth minerals using the novel collectors; when the same experiments were modeled using the high-fidelity kinetic model, recovery by entrainment was found to be significant. The effects of pressure on gas dispersion mechanisms, such as gas holdup, and how those mechanisms effect bubble size and kinetic parameters were determined

Development of a GIS based tool to analyze produced water from oil and gas wells and prediction of equilibrium concentrations using CalcAQ

2013 Fall.Includes bibliographical references.New extraction techniques based on hydraulic fracturing and horizontal drilling have significantly increased the available oil and gas in the United States. Producing oil and gas from shale formations is the main source of these unconventional resources. When shale formations are hydraulically fractured to increase the permeability, up to 5 million gallons of water can be used for each well. The significant use of water has caused concerns by several stakeholders, particularly in regions that are constantly facing water shortages such as Texas or Colorado. After the well is fractured, large amounts of water return as frac flowback and then after the well is put into production, water that is coproduced with oil and gas must be collected for the life of the well. The produced water has hazardous characteristics since it has been in contact with oil and gas for millions of years and disposal or reuse is an important part of an oil and gas operation. Current water management for produced water includes underground injection and surface disposal or reuse. Owing to a large amount of total dissolved solids (TDS), metals and hydrocarbons (e.g. BTEX) in the produced water, the brine needs to be treated to achieve acceptable water quality for subsequent disposal or reuse. Reusing and recycling of produced water for drilling and fracturing after appropriate treatment has multiple advantages including less truck traffic and lower fresh water demands. The objective of the research in this thesis was to integrate the OLI chemical equilibrium model into the OWM (Optimized Water Management) tool framework to allow chemical equilibrium calculations to be made for each well and in the aggregate throughout the Wattenberg oil and gas field of northern Colorado. The calculations from this model can then be used as design criteria for treatment train definition based on the desired water disposal outcome. OLI Systems software was developed for the chemical and oil and gas industry and is well suited as a module for calculating chemical equilibrium values for produced water and frac flowback water. The research described in this thesis includes predictions of equilibrium chemistry, solids precipitation and scale forming index, based on water quality data collected in the field. The model can also predict requirements for combining and treating produced water streams to achieve process objectives. At the same time, water quality will be analyzed after detailed sampling from various parts of the field. Finally, water quality after precipitation, settling and filtration has been used to estimate the osmotic pressure and design reverse osmosis processes for different levels of TDS rejection. This will be integrated with a customized ArcGIS tool that will help in predicting treatment specifics on a spatial scale

Application of column flotation technology for reduction of silica in zinc concentrate at Rajpura -Dariba mines, India

A 3000 t1d lead-zinc ore beneficiation plant was comm-issioned in 1983 to produce lead and zinc concentrates suitable for Hindustan zinc Limited 's smelters. The problems encountered in individual concentrates are mainly high graphite and lower lead grade in lead concentrate and comparatively high silica in zinc concentrate. Due to inherent nature of ore quality (graphite mica schist) the incidence of high graphite,lower grade of lead concentrate can be explained and taken care by use of effective graphite depressant or gravity techniques. It is observed during extensive laboratory scale tests by in-house R&D of HZL and by National laboratories in India and plant operations for decade, that type of ore quality (i.e. calc- silicate or graphite micaschist) does not affect zinc flotation and invariably the silica in zinc concentrate is reported between 5 to 8%, where as the requirement of HZL's smelters is 2.5% max. In this paper an account of extensive testing done at Central Research and Development laboratory of HZL (India), with operating plant at Rajpura-Dariba Mines is elaborated. It is observed that due to interlocking of gangue with sphalerite up to 2 micron size, fine grinding requirement for liberation of sphalerite and flotation of some gangue due to smearing of graphite on gangue during conintunition in ball mill, it is very difficult to effectively use graphite/gangue depressant for cont-rolling silica to a level of 2.5 % from 5-6%, without sacrifice of zinc recovery After careful and detailed study of zinc concentrate mineralogy and metallurgical results, the route of column flotation for zinc cleaning in place of conventional mech-anical cells was tried. Preliminary experiments were conducted on 3" diameter Diester make Flotaire column set-ulp at CRDL. The study indicated that flotation by use of column is effective in controlling free silica in conc-entrate by froth washing. The study was supplemented with detailed experimentation aimed at generating basic design data for pilot column for Rajpura Dariba concentrator.The data obtained was simulated on simulator developedby , M/s Engineers India limited and reconciled data was processed using computer software developed by EIL. The exercise indicated that by column flotation used in cleaning operations, the silica in zinc concentrate is reduced to a level of 4 %, the recoveries in cleaning operation remained nearly same

Geometallurgical Study of a Gravity Recoverable Gold Orebody

Sheeted vein gold deposits are often characterised by multiple sub-parallel veins and free-milling coarse gold. Inherent mineralisation heterogeneity results in grade and process parameter variability, which increases project risk if not quantified. Measured grade variability is often exacerbated by poorly designed sampling and testwork protocols. Protocols that are optimised within the framework of the Theory of Sampling (TOS) to suit the ore type, together with quality assurance/quality control systems, will reduce variability and provide fit for-purpose results. Geometallurgy can be broadly split into two key approaches: strategic and tactical (or operational). The strategic approach focuses on the whole orebody and long-term life-of-mine view, whereas tactical geometallurgy relates to a more short- to medium term view during mining. The geometallurgical approach requires spatially distributed samples within a deposit to support variability modelling. Diverse attributes from core logging, mineralogical/textural determination and small-scale tests are used to measure variability. This contribution presents a case study that emphasises an early-stage strategic geometallurgical programme applied to a gravity recoverable gold (GRG) dominated deposit. It exemplifies how data can be acquired from a well-designed and planned programme to support resource estimation, a pre-feasibility study, trial mining and fast-track to production. A tactical geometallurgical programme is embedded into the mine operation

Recovering the lost gold of the developing world : bibliographic database

This report contains a library of 181 references, including abstracts, prepared for Project R 7120 "Recovering the lost gold of the developing world" funded by the UK' s Department for International Development (DFID) under the Knowledge and Research (KAR) programme. As part of an initial desk study, a literature review of gold processing methods used by small-scale miners was carried out using the following sources; the lSI Science Citation Index accessed via Bath Information and Data Services (BIDS), a licensed GEOREF CD-ROM database held at the BGS's Library in Keyworth and IMMage a CD-ROM database produced by the Institution of Mining and Metallurgy held by the Minerals group ofBGS. Information on the search terms used is available from the author