Search Documents

By F. K. Mulenga, M. Lusambo

"Geometallurgical models are a strategic tool used primarily in planning, diagnosis, and process optimisation. This paper discusses the development of a predictive model for flotation recovery at Kansanshi concentrator in Zambia as a function of key operational parameters. Daily data for milling and flotation from the circuit processing the copper sulphide ore was analysed. This data, recorded over a period of one year of production, was collected from diverse sensors measuring semi-autogenous milling and flotation parameters. Statistical analysis showed that copper head grade, acid-insoluble, and acid-soluble copper, SAG mill throughput, ball mill load, and tonnage of feed material to the SAG mill in the -125 +63 mm size fraction contributed to the prediction power of the proposed empirical model by as much as 90%. Finally, a proposal was made for the development of a simulation model under MODSIM®, a flexible tool for mineral processing applications. This was to test the limitations of the empirical model for future refinement. IntroductionKansanshi is the largest copper mine in Africa and the world’s eighth largest copper producer, with a total of 253 272 t of copper produced in 2016 (Newall, 2017). It is located approximately 10 km north of Solwezi, the capital and administrative headquarters of the North Western Province, Republic of Zambia. The ore deposit consists predominantly of chalcopyrite and malachite with variable amounts of chalcocite, bornite, chrysocolla, and azurite. Because of the varying proportions of sulphide and oxide copper minerals, the ore is classified into three distinct categories: sulphide, mixed, and oxide ores. As such, three separate processing circuits are used to mill the ore down to a standard targeted grind size of 80% passing 150 µm before froth flotation and leaching.A lot of research and development has been done to improve the performance of the sulphide ore circuit at Kansanshi. Despite the research efforts and subsequent operation, the sulphide ore circuit did not attain the target recovery and grade for 2016, primarily because of the complexity of the orebody.The constant drive to achieve the set production target of recovery and concentration grade after froth flotation motivated the development of a tool for the prediction of recovery. The anticipated benefit is not only to enable the plant to apply corrective actions when needed, but also to make a tool available for the quick assessment of the plant performance of the. For that purpose, data spanning June 2016 to May 2017 was analysed, cleaned up and curvefitted to an empirical model. In doing so, key parameters were determined and calibrated to represent the behaviour of the plant."

Nov 1, 2018

By R. Lechuti-Tlhalerwa

"Geometallurgy aims to improve mining project value by predicting the impact that ore and waste characteristics will have on mining and metallurgical processes. This requires integration of rich spatial models of orebody characteristics with validated process response models. These models have, until recently, been constrained by the spatial coverage and representativity of relevant data and the ability to validate predictions made.The revolution in the diversity and volume of data and computational power that is now becoming available for integrated geoscientific modelling of orebodies, and stochastic simulation of mining and mineral processes is accelerating. By embracing emergent integrated data analysis and simulation techniques, geoscientists and engineers can lead a transformation in the way the mining value chain, from orebody to recovery, can be conceived, evaluated, and operated by using the geometallurgical paradigm.This paper describes a methodology that is applied to an existing diamond operation. Analysis of spatial and process data is used to build an integrated geometallurgical value chain model (IGVCM). This IGVCM is used to generate geometallurgical options and evaluate their potential outcomes. The model facilitates the use of flexible, highly configurable, and potentially automated intelligent approaches to evaluate mining and mineral process configuration, and results in more robust design outcomes. The approach described here, and its successful implementation has potential to deliver step-changes in value. IntroductionGeometallurgy aims to identify treatability risks – and opportunities – that arise from the interaction of orebody characteristics with mining and treatment. Improved understanding of the rock/process relationships allows project planners and production teams to predict performance, identify potential shortfalls, and thus enable the proactive creation and evaluation of strategies to mitigate these risks. These advanced insights also create opportunities for continually improving operational performance through dynamically adapting and improving the process response to the changing properties of the ore (Figure 1)."

Apr 1, 2019

By S. T. Johansen, B. T. Løvfall, T. Rodriguez Duran

In this paper we develop a physics-based model for lining erosion in steel ladles. The model predicts the temperature evolution in the liquid slag, steel, refractory bricks, and outer steel shell of the ladle. The flow of slag and steel is due to forced convection induced by inert gas injection, vacuum treatment (extreme bubble expansion), natural convection, and waves caused by the gas stirring. The lining erosion takes place by dissolution of refractory elements into the steel or slag. The mass and heat transfer coefficients inside the ladle during gas stirring are modelled based on wall functions which take the distribution of wall shear velocities as a critical input. The wall shear velocities are obtained from computational fluid dynamics (CFD) simulations for a sample of scenarios, spanning out the operational space, and a model is developed using curve fitting. The model is capable of reproducing both thermal and erosion evolution well. Deviations between model predictions and industrial data are discussed. The model is fast and has been tested successfully in a ‘semi-online’ application. The model source code is available to the public at [https://github.com/SINTEF/refractorywear].

Apr 16, 2024

By B. D. H. Knights

In November 2009 Mintek installed the FloatStar? advanced flotation stabilization system on Vale's Cauê iron ore beneficiation plant in Brazil. In September 2010 the system was upgraded to include flotation optimization. The circuit consisted of two parallel cleaner circuits producing final concentrate. The tailings from the cleaner section passed through a scavenger circuit. Large, well-instrumented feed sumps played an important role in circuit stability, presenting a good opportunity for advanced control. Previously the plant was controlled using distributed control system (DCS) level control only. The flotation circuit processes roughly 30kt/day. The FloatStar system provided advanced control of the flotation circuit as well as of the sumps feeding the circuit. The system underwent a lengthy trial to assess the benefit that it provided. Two data sets were analysed, showing performance under advanced stabilization and optimization respectively. Several validation and consistency criteria were employed to ensure the quality of the analysis. Iron recovery and iron tailings grade were used to measure system performance. The analysis showed that the system increased recovery by up to 2.7%. In addition, the system decreased the iron tailings grade by between 1.2% (from 23.5% to 22.3%) and 4.3% (from 31.3% to 27.0%) during different test campaigns. The analysis also showed that the entire FloatStar stabilization system was active for 72.7% of the time from first activation to the end of the first data set (approximately 200 days). From the analysis it was concluded that under similar conditions for 'ON' and 'OFF' tests, the system provides a clear benefit. It was also found that over the longer term, the system continues to provide a benefit. This finding suggests that the results were not simply due to a short-term advantage. The size of the data set, as well as the magnitude of the recovery improvements, lends considerable confidence to these results. Therefore, it can be concluded that the FloatStar control system provides substantial benefit to operations at this site.

Jan 1, 2012

By A. S. Ratnayake, H. C. S. Subasinghe

In this study, we review the role of mechanical activation in the pyrometallurgical, hydrometallurgical, and electrometallurgical processing of titanium feedstock. Mechanical activation has been shown to decrease the activation energy of chemical reactions, thus enhancing process efficiency and product quality by reducing processing time and energy consumption. Pyrometallurgical processing is energy-intensive and time-consuming. Hydrometallurgy is costly, requires high-grade feed material, and generates toxic waste. Waste generation and process complexity are the major drawbacks of electrometallurgy and solvent extraction. Bioleaching via a mechanically activated pyrometallurgical process can be identified as an alternative method, but the lengthy processing time is the major disadvantage. Mechanically activated titanium concentrate can be used in a finely tuned combined metallurgical process to overcome the challenges and drawbacks in these technologies.

Aug 3, 2023

By F. Reyes, M. Hilden, G. Forbes, M. Yahyaei

Since AlphaGo defeated the best human player in the game of Go in 2016 - something thought to be an impossible achievement - machine learning, deep learning and reinforcement learning have caught the attention of scientists, the media and the general public alike. This recent development in machine learning (let us remember that neural networks have been available for decades now) opens new possibilities in the areas of modelling and process control. However, little has been reported in the minerals processing industry about these new possibilities and opportunities. This paper presents and introduces the topic of reinforcement learning and the different platforms that allow its implementation. The paper shows the consequences of using reinforcement learning for the specific area of process control and optimisation. As an example, the authors present the use of reinforcement learning for the control of a SAG mill closed with a pebble crusher using industrial data from an operation. A comparison with advanced model-based process control is provided, showing the benefits and shortcomings of reinforcement learning as a new control and optimisation technique. Keywords: Reinforcement learning, deep learning, process control, process optimisation

Jan 1, 2020

By X. J. Lyu, Q. Liu, M. J. Lian, X. Q. Cao, X. F. You, B. O. Erdenekhuyag, H. Y. Zang

The slag-tailings based artificial reef concrete (ARC) is made of CaO-CaSO4 activated granulated blast furnace slag (GBFS) as cementitious material and deslimed gold ore tailings as aggregate. In order to investigate the potential application of the material as ARC, the strength development, hydration characteristics and application performance were investigated under different preparation conditions. Results indicated that using seawater as the mixing water can effectively promote the hydration of slag and generate a large amount of hydration products such as ettringite, CSH gel, hydrotalcite and Friedel ’s salt in the early curing period and so render the material with good early compressive strength. Seawater curing can also accelerate the hydration reaction in the early stage of hydration. The hydration reaction of slag and the compressive strength of ARC can be effectively promoted by increasing the specific surface area of slag. The 28-day compressive strength of the slag-tailings based ARC prepared with 30-50% CaO-CaSO4 activated slag and 50-70% tailings can reach to 19.88-42.87 MPa. Also, the material has a low surface pH value, good resistance to chloride ion penetration, and sulfate corrosion. Keywords: Artificial reef concrete, granulated blast furnace slag, deslimed gold ore tailings, compressive strength, hydration characteristics

Jan 1, 2020

By J. Sehata, J. Tshilongo, I. Govender, S. Pikinini, T. L. Moodley, M. Raedani

In the face of dwindling Merensky ore reserves in the early 1990s, Mintek developed the MF2 flotation circuit to economically recover platinum group metals from the shallow upper group-2 chromitite reef. By aligning the primary and secondary grind to the platinum group metal liberation kinetics, excessive fine chromite generation was avoided, and thus one could consistently produce high-grade concentrates (>200 g/t platinum group metals) with low chrome content (<3% Cr2O₃), well within smelter tolerances. This, coupled with upper group- 2's low-cost open-pit mining, made it particularly attractive to investors and mining houses alike. As a result, deeper lying reefs like middle group and lower group with lower platinum group metals grades and complex mineralogy, were primarily mined only for chromite using density-based separation processes (like spirals), of which the waste tailings are best classified as secondary platinum group metals resources. Today, with global platinum group metal demand rising and high grade upper ground-2 reserves rapidly diminishing, the industry must revisit these middle group and lower group tailings. Mineralogical analysis reveals several challenges: Middle group tailings feature platinum group metals locked within silicate matrices, while lower group tailings contain fine chromitite fragments, and are hosted within non-floating laurite grains, each presenting liberation and gangue issues. Smelter constraints still demand concentrates below 3% Cr₂O₃, requiring solutions that consider both platinum group metals recovery and chrome entrainment. To develop a solution, two lower group chrome spiral tailings samples were obtained from a large chrome mine: Sample A (+425 μm – 106 μm) and Sample B (−106 μm). Initial assays showed Sample B contained higher platinum group metal grades but also higher Cr₂O₃. As such, different blends of flotation feeds were evaluated using ratios of 90:10 (C1) and 80:20 (C2) of Sample A to Sample B, targeting the coarse fraction's lower chrome content while recovering valuable platinum group metals from the fines. This work proposes a practical route for mining houses to unlock additional platinum group metal value from lower group ore spiral tailings. By optimising blending ratios and reagent suites, it is possible to meet smelter chrome and platinum group metal grade thresholds, whilst still obtaining economically viable PGM recoveries.

Mar 6, 2026

By R. P. King

"A model of the flotation process can be used effectively for design and control. For design purposes it can be used to predict the performance of a large plant from laboratory and pilot plant data. It can be used for control purposes to assess the utility of any proposed operating modification to an existing plant, and it can also be used to determine optimal control settings for best operating performance.A model has been developed that will allow for variations in feed properties and for variations in fineness of grind. The model can be used to assess the effects of reagent addition rate, aeration rate and pulp level on plant performance and these are the control variables that are used individually or together in all operating flotation plants. The model provides for a distribution in the values for flotation rate constants, particle size and mineral fraction, and, because of its complexity, requires a large computer when it is to be applied to a typical plant configuration. The computational method that is used to apply this model to such configurations is described in this paper, and particular attention is paid to the problem of allowing for feedback of tailings from cleaners and recleaners."

Jan 1, 2014

Paper written on project work carried out in partial fulfilment of B. Eng (Metallurgical Engineering) degree Electrowinning is an attractive method to recover gold from the relatively concentrated aurodicyanide solutions produced by the elution of loaded carbon, provided that the plated gold can be easily removed using high pressure water sprays. In practice, difficulty with the removal of the gold is occasionally experienced and has been correlated with the presence of high concentrations of copper in the eluate. In this work, the influence of copper on the electro-plating of gold was further investigated using a laboratory electrowinning cell with a rotating disc cathode, polarization, and adhesion tests. It was found that the reduction of copper will compete with gold electrowinning at high copper tenors and that the adhesion of the precipitated gold is also increased under these conditions. Keywords: reduction, adhesion, morphology, current efficiency, limiting current.

Jan 1, 2004

By T. Szendrei and S. Tose

Historical approaches to the problem of flyrock based on correlation studies and regression analysis, including artificial neural networks and similar techniques, are inherently incapable of addressing two core issues – root causes of flyrock and projection velocity. A further shortcoming of correlation techniques is that they give no information on the influence of rock size and shape on the flight distance. The scaled depth of burial model for crater blasting in the collar zone and bench face does not specifically address the question of flyrock velocity. A third approach, based on flight trajectory calculations, often neglects the very significant effects of air resistance on the trajectory. Some trajectory models incorporate air resistance but use an implausible fragment velocity model that cannot propel sizeable rocks to distances much beyond 150 m. Nonetheless, trajectory calculation incorporating the effects of air drag affords the most promising approach to the prediction of flyrock range. A unique and insightful feature of the proposed realistic flight modelling is that it collapses all suspected causes of flyrock, many of which are not well understood, to just a single parameter – the launch velocity. This indicates that the root causes of flyrock lie in the mechanisms of momentum transfer to broken rock and suggests new avenues of study.

Dec 13, 2022

Solvent loading: It is agreed that it is advantageous, as far as reagent cost is concerned, to operate at maximum solvent loading. However, owing to the fact that no reliable automatic solvent flow controller is yet available, control tends to be erratic with the result that there is risk of losing uranium. As can be seen from Mr Tunley&apos;s plot, the graph representing total ammonia cost is fairly flat between loadings of 3.5 and 4.0 gpl, while the graph representing uranium loss in the raffinate is steep. It is, therefore, safer to operate slightly below optimum loading in the absence of absolute control. Should the purity of the final product gain importance, operation at optimum loading or even slightly above, may be advantageous. Solvent losses and clarification of pregnant solution: The cost of replacing solvent, as indicated by Mr Carman, represents a high percentage of the overall Purlex costs. It is, therefore, agreed that, amongst other factors, efficient clarification of the pregnant solution and mixer-settler design have an important bearing on the cost. However, as at Blyvooruitzicht, the Buffelsfontein plant can tolerate a suspended solids content of 50 ppm without serious deterioration in efficiency. An increase in the suspended solids content from 15 to 50 ppm normally accounts for an increase of approximately 1 ppm in amine loss. Clarification of acidic pregnant solutions is much more difficult than that of alkaline solutions. Sand clarifiers are being used at Buffelsfontein with moderate success. Clarified solutions containing less than 20 ppm of solids in suspension can be produced, depending on the quantity and type of flocculant used in the filtration process, the thickness and the grading analysis of the sand beds and the quality of supervision. An on-stream duty of approximately 0.15 gallon per sq ft of surface area is obtained. Hydraulic handling of clarifier sand, while cleaning, may effect the efficiency of a clarifier, as size segregation of sand particles may lead to inefficient "pockets" in a sand bed. Control of the solution level in the sand clarifier also affects the quality of the effluent. Exposure of the sand bed invariably causes a cloudy effluent. Recycling of the final and initial solution discharged before and after skimming the clarifier sand improves the clarification efficiency significantly. Post-precipitation of silica and possibly sulphate salts, after clarification, may give a false impression of inefficient clarification. This phenomenon is more pronounced when treating hot supersaturated solutions. Ageing and cooling of the solution before clarification assist in stabilising the solution and reduce precipitation after clarification. The maintenance cost of sand clarifiers at Buffelsfontein is in the order of 0.35 cent per metric ton of solution treated. A redundant ion-exchange column has been tested successfully, either as a primary or a secondary clarifier, depending on the quality of the filtrate treated. The conventional pebble and sand beds in the column have been retained. Operation was enhanced by the addition of a two-foot deep resin bed as a filtering medium. The suspended solids content was reduced to less than 5 ppm. Mixer-settlers: Mixer-settler design is a controversial subject but, in view of the high costs of solvent compared to relatively low pumping costs, it is believed that mixing and pumping functions should be separated. Separate facilities for pumping and mixing not only give greater operational flexibility but also permit eventual changes in the flow circuit as technology develops. Scrub technique: Unlike the pilot plant, where the crud was carried away in the aqueous phase, crud is carried over with the organic phase in the full-scale plant. This carry-over of crud into the strip bank aggravates crud formation in the first strip stage. This phenomenon may result from a slight difference in settler design and/or a variation in the relative phase depths in the two plants. Bypassing of the scrub aqueous solution from the fourth to the second stage was introduced in order to avoid dilution and partial neutralisation of the acid added to the third stage, as it is known that a low pH value enhances the transfer of iron into the aqueous phase. The low aqueous flowrate in the third scrubbing stage was overcome by introducing an aqueous phase recycle. Gleaning: Mr MacDonald&apos;s contribution on "gleaning" was most informative. This process for recovering solvent from raffinate seems to show at least as much promise as coalescers and other methods employed to date. Similar tests conducted at Buffelsfontein pilot plant gave 60 per cent amine recovery from raffinate containing 10 ppm amine. However, the circuit was not operated at equilibrium and recovery may be expected to drop as the amine concentration of the "Gleaner" circuit increases.

By T. Moodleya, I. Govender

Despite the widespread use of DEM to simulate particle processes, comparatively little work has been done to evaluate its accuracy. One of the reasons is a lack of available measurement techniques that can capture dynamic information at the momentum transfer timescale which is lower than 10-6 s - typical of the kinetics occurring within the drum. This work makes use of Positron Emission Particle Tracking (PEPT), an in-situ method capable of measuring 3D kinematic data at 1000 frames per second. PEPT measurements are performed using 3 mm and 5 mm mono-size glass beads in a 300 mm diameter rotating drum at critical speeds that are relevant to industry. We undertake systematic ‘tuning’ of DEM with a view to optimising the agreement between experiment and simulation. To ensure an equitable comparison scale, both the DEM and PEPT data are coarse grained within representative volume elements. This work seeks to validate DEM predictions against experimentally derived PEPT kinematic measurements. Keywords: PEPT, nuclear imaging, DEM, Tumbling Mills

Jan 1, 2020

By J. H. Cloete, S. M. Bradshaw, D. K. Chibwe

"The primary function of a tundish in the steelmaking industry is to serve as a buffer tank, accepting molten steel from the batch ladle process and allowing it to be cast continuously. However, modern steelmaking has more stringent demands for the quality of the steel product, requiring increased control over the properties of the molten steel before casting. For this reason tundishes have been developed as metallurgical reactors to serve as the final step in refining of the molten steel by removing non-metallic inclusions, preventing the formation of new inclusions, and promoting chemical and thermal homogeneity. In this study the flow behaviour in a four-strand tundish was investigated by means of a half-scale water model as well as numerical modelling. Both the numerical study and physical model were used to characterize residence time distribution (RTD) in the vessel and calculate properties pertaining to the tundish flow regime. Three different tundish configurations were investigated: a bare tundish with no flow control devices, a tundish with a turbulence inhibitor and a tundish with both a turbulence inhibitor and a dam.The physical and numerical models showed that a tundish without flow control devices was prone to significant short-circuiting. A tundish with a turbulence inhibitor was shown to be successful in preventing short-circuiting and provided surface-directed flow, which aids inclusion removal in the slag. Despite the benefits of the use of turbulence inhibitors, it was observed that the upward-directed flow increased the maximum turbulence kinetic energy near to the surface by approximately 120% compared with the bare tundish. Therefore the potential for slag entrainment should be considered during the design and operation of tundishes utilizing turbulence inhibitors."

Jan 1, 2014

By M. Paricheh, M. Rahmanpour

"The cost efficiency and high reliability of semi-mobile or combined in-pit crushing-conveying (IPCC) and truck systems, compared to conventional truck-shovel systems alone, make them more attractive for use in modern mining operations. Semi-mobile systems, which are the most common systems in open-pit mining, combine the advantages of both systems such that fewer trucks are required, operating costs are lowered, and the operation is environmentally sound. One major aspect of utilizing this system is determining the location of the in-pit crusher and the timing of relocations. Facility location models are rarely used in the mining sector, but these models may be used for solving the in-pit crusher location problem. To this end, the main parameters affecting the IPCC location in open pit mines are reviewed and examples given of how they are applied to a dynamic location-relocation problem. Subsequently, the model is implemented for Sungun copper mine in Iran and the number and the exact time of relocations of the IPCC units determined. IntroductionNowadays, compared to the last century, metal prices are more volatile, average and cut-off grades have decreased, and stripping ratios increased. From a mining engineering point of view, many ore deposits with simple access and low capital and operating costs have been exhausted. The remaining deposits are located at depth, with no easy access, which requires high initial capital costs (Osanloo, 2012). Mining at great depths and high tonnages is possible only through open pit mining. Today, more than 80% of open pit mines in the world use a shovel-truck system for loading-hauling operations (Osanloo, 2010).With increasing depth, haulage distances increase and the number of loads per truck decreases. As a result, fuel, tyre, and depreciation costs per ton increase. Owing to these factors, open pit mining at great depth (300 to 1000 m) using shovel-truck systems faces some technical and economic problems. In-pit crushing-conveying (IPCC) systems have been known in the mining industry for many decades. The idea was introduced in 1956 in Germany. Today, the cost efficiency and high reliability of IPCC make it more appealing than conventional shovel-truck operation, especially in longer life projects with lengthy transportation distances and high production rates (Koehler, 2003). Since 1956, different aspects of this system have been reviewed by many researchers. Barua and Lanergan (1985) developed a computer program that compares the tonnage aspects of various conveyor layouts. They believed that to maximize the economic benefit of lower haulage costs associated with in-pit conveying, one must first minimize the cost of the flatter slope, which is expressed in terms of additional stripping or tied-up ore. Dos Santos and Stanisic (1987) evaluated the design of a high-angle conveyor at the Majdanpek copper mine. Then, Sturgul (1987) applied GPSS (general purpose simulation system) to find the best location of an in-pit crusher."

Jan 1, 2017

By D. K. Chibwe, P. Taskinen

"Typical operation of industrial Peirce-Smith converters (PSCs) used in copper smelting results in several common phenomena such as excessive splashing, slopping, tuyere blockage, and low converter campaign life due to high tuyere line refractory erosion. These phenomena give rise to an inefficient operation from both a process and an energy perspective.This investigation presents numerical and physical models of flow patterns, mixing, solid-liquid mass transfer, and slag-matte phase distribution in a slice model of an industrial PSC. For physical simulations, a 0.2-scale cold model was developed. Water, kerosene, air, and sintered benzoic acid compacts were used to simulate matte, slag, injected gas, and solid additions into the PSC. The two- and three-dimensional numerical simulations of the three-phase system were carried out using volume of fluid (VOF) and realizable k- e (RKE) turbulence models to account for the multiphase and turbulence nature of the flow respectively. These models were implemented using the commercial computational fluid dynamics numerical code FLUENT.Both numerical and physical simulations were able to predict, in agreement, the mixing and dispersion characteristics of the system in relation to various blowing conditions employed in the investigation. Measurement of mass transfer characteristics conclusively indicated that fluid flow in the PSC is stratified. Both blowing configuration and volume of slag in the converters were found to have significant effects on mixing propagation, wave formation, and splashing.The splashing and wave motion in these converters are known to cause losses of metal/matte and potential production time due to the requirement for intermittent cleaning of the converter mouth, resulting in reduced process throughput. To prevent these losses and hence to increase process efficiency, we propose a combined blowing configuration using top lance and lateral nozzles. The numerical simulations were conducted on combined, as well as lateral, blowing conditions. In comparison, the recent results of the combined blowing concept were found to be encouraging."

Jan 1, 2014

By M. Kerr

Background- History The most significant change in mining since the late 1970?s has been the emergence of very large scale mining operations , which have been developed to ensure profitability with relatively low grade ores. These large tonnage operations have resulted in the development of larger unit sized machines in all operations of beneficiation, solid-liquid separation and dewatering. Often only a few flotation lines are installed and tonnages up to 25 ktpd and beyond are not uncommon. The increased throughputs have led to the development of circular, reactor type tank designs. The reactor cell system is the most up to date flotation cell design to utilise the principles of circular cell design. The Svedala DV mechanism was specially developed to suit the RCS machine giving good solids handling characteristics and excellent metallurgical performance. Development of UG2 ore type flotation equipment The equipment was developed and optimised by Svedala process from 1995. A higher energy specification was requested by industry. This amounted to 3kW/m3 for installed volume. Existing designs were at 1.5kW/m3. Hence various modifications were required to achieve the required power input. The first 50m3 machines were installed and developed at Impala Platinum?s UG2 circuit over a one year period. Once reliability and performance was achieved, over 300 large volume flotation cells were installed at Anglo Platinum and Lonmin operations as well. Pilot Plant Development The Impala Platinum High Energy pilot plant was commissioned in 2002 and had an installed power exceeding 5kW/m3. It was operated for over a year at the tailings dam booster station and was fundamental to the large scale scavenging plant design. All experience in overcoming mechanical and operational problems was applied in scale up design principles. A very robust mechanism was designed to accommodate the additional power input from installed motors, as well as the high SG (>1.5) of the feed source. The pilot plant flowsheet is shown in the figure below.

Jan 1, 2007

The development of 3D multi-parametric models facilitate the provision of resource information well in advance of the mining face. Using the model, one can evaluate mining areas not only for grade and tonnage predictions but also for predictions of rock mass quality. Blast design and milling requirements can be derived from the rock mass quality predictions. This information can be used for overall mine planning and evaluation, costing, production optimization and slope design. This allows the full range of mining activities and costs to be interconnected, there by lowering costs and improving efficiencies through the application of the multi-parametric model. Feasibility studies for new projects require an expected budget expenditure estimate to within5% of actual costs. This level of accuracy is expected by mining companies and investors but cannot be achieved without a sound knowledge of the rock mass variability. By developing a 3Dmulti-parametric model as part of the feasibility study and using the same geological model exploration boreholes, a significantly better understanding of the rock mass conditions can be obtained. This rock mass information can be used for equipment selection, economic pit layouts, processing plant design, underground mining layouts and support requirements, to name but a few design parameters that depend on rock mass conditions. The initiative at Anglo Platinums, Potgietersrust Platinum Ltd.?s (PPRust) operation, has delivered significant results showing improvements across the mine to mill value chain. These include increased loading rates, reduced electricity and crushing consumables, as well as higher plant throughput. The ore reserve model has gained international acceptance as an invaluable tool for a mining operation. Certainly most financial organizations will not invest in a mining project that does not have an ore reserve model. There is the potential for multi-parametric models to be recognized as vital tools in the mining process, as is the case with ore reserve models.

Jan 1, 2006

By S. W. Jacobsz, E. P. Kearsley, N. K. Schoeman

A physical modelling approach was adopted to simulate the process of cave mining propagation at various horizontal to vertical stress state ratios, and image data was captured and used to characterize the resulting failure mechanisms. Image processing was integrated into the study to determine minor principal strains in models to identify where critical extensional strains had been exceeded relative to crack propagation. The study exhibited a scale factor magnitude of 119 using a calculated critical extensional strain value of 0.014% for the modelling material used. It was perceived that cave propagation occurred through successive parallel extensional ‘fracture bands’ in all cases, as noticed in models of prior studies, deviating from that described by the Duplancic model. Cracks tended to bisect regions of minor principal strain equal to the critical extensional strain, which suggests ‘fracture banding’ is an acceptable failure mode for brittle, rock-like materials. Moreover, it was found that models with lower horizontal to vertical stress ratios (K ratios) showed a greater degree of vertical development of the caving mechanism (at similar vertical stresses), while the vertical extent of the cave was suppressed in models with higher K ratios. Models subjected to larger vertical stresses experienced slower cave formation in latter time-steps. These models exhibited larger two-dimensional caved perimeters and areas, respectively.

Nov 30, 2022

By E. G. Galvez, E. Mate, L. A. Cisternas, C. Cruz, L. Cortés, M. E. Osorio

Designing and optimising flotation circuits are critical for mineral beneficiation plants, and therefore several procedures have been published. The modelling of flotation circuits with the objective of design and optimisation is problematic in that different approaches are used for the modelling of flotation units and regrinding units. Usually, regrinding models are based on particles characterised by their size, while flotation models are based on species characterised by fast and slow classes. The relationship between particle size and liberation can be used, but it requires laboratory studies that are time-consuming and costs are high. It is therefore not surprising that few studies on flotation circuit design and optimisation include flotation units and regrinding units simultaneously. In this paper, it is proposed to model the regrinding stage using species characterised by fine-slow, medium-fast, and coarse-slow flotation species. In deep, the regrinding model is derived from a population balance approach based on flotation species. The fraction of these species at the feed and product of the grinding unit is determined by flotation tests. Then, based on these data, the model parameters can be determined by a regression estimation procedure. A local ore was used to validate the model. Keywords: Modelling, flotation circuit, grinding circuit, process design

Jan 1, 2020