Optimization of Platinum Concentrator Performance (2010) PDF

VALENTA, M.M. and MAPHETO, H. Application of fundamentals in optimizing platinum concentrator performance. The 4th International Platinum Conference, Platinum in transition ‘Boom or Bust’, The Southern African Institute of Mining and Metallurgy, 2010. Application of fundamentals in optim...

VALENTA, M.M. and MAPHETO, H. Application of fundamentals in optimizing platinum concentrator performance. The 4th International Platinum Conference, Platinum in transition ‘Boom or Bust’, The Southern African Institute of Mining and Metallurgy, 2010. Application of fundamentals in optimizing platinum concentrator performance M.M. VALENTA and H. MAPHETO Metallicon Process Consulting (Pty) Ltd A number of challenges face platinum concentrator plant operators. These challenges include the increase in operating costs, the increase in smelter cost for the processing of concentrate, the shortage and cost of power, and the tightening of specifications on concentrate quality by the toll- smelting operations. Over the years the focus has moved from extracting the platinum group metals (PGM) from the Merensky Reef to the UG2 Reef. This has a number of advantages including the higher ‘basket price’ for UG2 concentrate, reduced mining cost per unit volume as a result of the higher density of UG2, and the reduction in overall concentrate tonnage to be smelted. In many cases the Merensky ore has been fully exploited and it makes sense for the focus to shift to the UG2 ore that can be accessed through the Merensky shaft infrastructure. The presence of relatively high levels of chromite in UG2 concentrate is, however, a major disadvantage due to the problems associated with smelting such a concentrate in conventional submerged arc furnaces. In addition to increasing the specification on the minimum PGM grade of concentrates, smelters have had to impose strict specifications on the levels of chromite in the concentrate. The threat of high penalties has forced concentrators to change their modus operandi, often resulting in a significant loss in recovery. The final concentrate grades and PGM recoveries are shown to vary significantly throughout the industry. The reasons for this include varying ore mineralogy and different operating philosophies. This would therefore imply that the opportunity exists to optimize the operations by considering fundamental aspects such as the PGM mineralogy and the application of appropriate technologies. By returning to the fundamentals of flotation and applying the findings of detailed process reviews, it has been possible to increase the concentrate PGM grade, reduce the concentrate chromite grade, and in some cases increase the recovery of PGM to concentrate. This paper presents case studies where this approach has been used to successfully optimize concentrator performance, resulting in lower operating cost and higher PGM production. Introduction Concentrators have been forced to reevaluate their current The volatility in the platinum market combined with the operations and identify opportunities to improve recoveries fluctuation in the operating cost observed since 2008 has and grades. This paper presents case studies where, through motivated operations in the platinum industry to optimize analysis of current operations and the application of their processes. This has not only been the case for the fundamental principles, improvements have been made in smaller operators in the industry who have limited concentrator performance. resources, but also for the larger organizations that The case studies have been limited to UG2 concentrators due to the added complexity in the UG2 concentrator recognized that a fresh unblinkered perspective may be design and more stringent concentrate specifications. needed. The concentrators have been threatened by increases in the cost of labour and consumables as well as higher The UG2 Reef smelter costs. Direct smelter costs are linked to the grade of The UG-2 ore is a platinum-bearing chromitite ore that concentrate related to overall concentrate tonnage produced. Additional smelter costs are incurred as penalties contributes a growing proportion of the platinum group that have resulted from more stringent specifications on the metal (PGM) production from the Bushveld Igneous minimum PGM grade and maximum chromite grade (in the Complex in Northern South Africa (McLaren and de case of UG2 concentrate). Villiers, 1982, Phillips et al., 2008). The complexity of Advances in technology have offered avenues to increase design of a UG2 concentrator circuit is primarily due to the recoveries and concentrate grade. However, this would PGM mineralogy and the fact that the ore contains multiple require the investment of significant amounts of capital that gangue phases with significantly different characteristics, has not been readily available in recent times. i.e. silicates and chromitite (Valenta, 2007). APPLICATION OF FUNDAMENTALS IN OPTIMISING PLATINUM CONCENTRATOR PERFORMANCE 13  The ore contains trace amounts of base metal sulphides This paper focuses on the optimization of the that, despite their low concentration, are of importance as concentrator operation that has an influence on all the they frequently occur in association with many of the PGM- downstream processes. The preferred concentrator process bearing minerals. The copper head grade varies between for the extraction of PGM to concentrate is akin to sulphide 0.005% and 0.02%, whereas the nickel grade varies flotation and also results in the recovery of the base metal between 0.025% and 0.05%. sulphides (BMS). This process utilizes the natural and The mode of occurrence of the PGMs in the ore is induced hydrophobicity of the PGM minerals to separate complex and the PGMs occur in various minerals including the PGM minerals from the gangue phases. The success of metal alloys, sulphides, oxides, tellurides, etc. PGM the process is thought provoking given the low containing grains in UG2 ore are small and rarely exceed concentration of BMS and PGM sulphide minerals. 30 micron in diameter. The average grain size can be as However, recoveries in excess of 90% have been achieved. fine as 6 micron. This complex mineralogy poses a The presence of multiple gangue phases and the relatively challenge to the metallurgist from a mineral liberation and fine grain size of the PGM require a more involved circuit extraction perspective. design than is typical for a conventional base metal The PGM grade of the feed to the UG2 concentrators sulphide circuit. typically varies from 2.0 g/t to 5.5 g/t. The feed grade is The entrainment of chromite to the UG2 flotation affected by the stoping height in the mine, how much of the concentrate adds another challenge to the concentrator hangingwall and footwall is included in the mining cut, and operator in that limits are placed on the amount of chromite the presence of gangue partitions between the chromitite allowed. Excess chromite in the concentrate results in the seams. The chromitite content in the feed can vary from as build-up of highly refractory chromite spinel layers in the low as 25% to as high as 40% (Philips et al., 2008). furnaces, thus affecting furnace operation and furnace availability and increasing operating costs (Philips et al., Processing of UG2 ore 2008). The supply chain for the production of PGMs is complex as The circuit that forms the basis of most UG2 is illustrated in Figure 1. The first metallurgical stage in the concentrators in the industry is illustrated in Figure 2. This production of platinum group metals and gold (PGM+Au) is commonly referred to as an MF2 circuit. The particle size is the production of a concentrate as feedstock to the of the feed to the primary flotation circuit is typically 35% smelter. The smelter-converter stage is followed by a passing 75 µm and that of the feed to the secondary circuit refining stage for the production of primarily copper and is typically 75% passing 75 µm. The conventional flotation nickel, and a further refining stage for the production of the stages typically consist of rougher, cleaner, and recleaner individual PGM+Au metals. stages. There have been a number of advances in the design of the circuit, including the cleaner cell configuration, the open circuiting of the cleaner tailing stream, and separate secondary processing of the chromite and silicate-rich streams. Ultrafine grinding of tailing steams has also been introduced with grinds as fine as a P80 of 53 microns, resulting in improved recoveries. A typical reagent suite for UG2 flotation includes an activator (CuSO 4), collector (SIBX), CMC depressant (carboxy methyl cellulose) and frother (DOW200) (Overbeek, Loo and Dunne, 1984). These reagents are added in various proportions in a variety of addition points Figure 1. The platinum group metal supply chain throughout the circuit. Figure 2. Typical circuit for the processing of UG2 ore 14 PLATINUM IN TRANSITION ‘BOOM OR BUST’ UG2 concentrator grades and recoveries In the recovery of PGMs and BMSs to the concentrate, The graph in Figure 3 presents data gathered by the authors the predominant process is true flotation. The predominant that illustrate the typical variability in the concentrate grade process responsible for the recovery of gangue phases in the produced on UG2 concentrators operating on the Bushveld UG2 flotation process is, however, entrainment, with a Igneous Complex. In addition, the PGM recovery can vary lesser proportion being recovered by flotation. from 70% to 90%. The variability in the results can be Both sub-processes affect the grade of the final attributed to PGM mineralogy, circuit configuration, and concentrate and the metallurgist must consider the operating philosophy. interaction between the sub-processes and the effect these Amendments to the penalty clauses in the toll treatment processes have on the response of the various minerals in agreements have become more stringent and concentrates the ore. with a Cr 2 O 3 grades exceeding 1.5% start incurring penalties. Some toll smelters will not tolerate concentrates Parameters to consider in flotation exceeding 3% for long periods and instances have occurred In controlling and optimizing a flotation plant various where concentrates have not been accepted. parameters have to be considered. These can be grouped as It is interesting to note that no UG2 concentrators within those parameters that are inherent in the ore, parameters our database are able to achieve the minimum of 1.5% that are related to the mechanical equipment, and the Cr2O3. Some concentrators producing concentrates with operational parameters relating to the environment within high Cr2O3 grades are saved by blending their concentrates the solids-water mixture. (Table I.) with low Cr2O3 containing concentrates from Merensky The parameters can be controlled to a lesser and greater concentrators or other UG2 concentrators producing low extent by the metallurgist to optimize the circuit and Cr2O3 grade concentrates. maximize the amount of saleable PGM. Considering the sub-processes in flotation Optimization methodology It has been widely accepted that the process of flotation is a The process of conducting a review of the operation of a combination of a number of individual sub-processes. concentrator varies for every concentrator depending on the Simply put, the process whereby solids and water are available metallurgical resources, the state of the operation, transferred from the pulp phase to the froth phase can be and the level of instrumentation/control being exercised on described by considering the sub-processes of true flotation the plant. and entrainment (Bradshaw et al., 2005). The author’s experience has been that the establishment True flotation can be described as the selective chemical of a formal steering committee including key role players sub-process where hydrophobic minerals are attached to the from the operation as well as outside consultants has had a bubbles rising through the pulp. Entrainment is described as better chance of success than simply introducing outside a non-selective physical sub-process where solids and water consultants or expecting the in-house metallurgists to are transferred to the froth in the bubble lamella and bubble simply continue with their duties. The steering committee interstices. should include key role players such as the senior engineering personnel and operations personnel so as to ensure continuity and commitment. The process of optimizing the plant operation includes: A review of the design test work upon which the plant was designed A review of the mineralogy of the ore Gaining an understanding of the geology of the deposit Analysis of the historical operating data and results Analysis of the plant running time and availability of unit operations Generating of a mass balance of the current operation to assess the unit capacities, residence times, stage efficiencies, upgrade ratios and flotation response Laboratory flotation tests of samples taken from the plant to determine flotation characteristics Conducting assay-by-size analysis of the various streams Figure 3. Variability in concentrate grade for UG2 concentrators Developing various scenarios based on the data Table I Parameters to consider in optimizing a flotation circuit Inherent parameters Mechanical parameters Operational parameters PGM mineralogy Circuit design Mill power Feed grade Type of equipment Pulp density Gangue dilution Classification circuit Reagent type Flotation cell geometry Reagent dosage Reagent dosage point Froth depth Aeration rate APPLICATION OF FUNDAMENTALS IN OPTIMISING PLATINUM CONCENTRATOR PERFORMANCE 15  Identifying opportunities for process optimization This can be determined by comparing the flotation Determining the cost of changes response of samples in the laboratory taken from the plant Optimizing operational parameters and studying the resultant flotation kinetics. Furthermore, Implementation of recommendations. the capacity to perform detailed mineralogical analysis has The most successful exercises have been those where the increased significantly of late, allowing the metallurgist to consultant is part of a steering committee and decisions are quantify the relative abundance of the mineral species, the made as a collective. Decisions are seen as group decisions degree of liberation, and the mode of occurrence of the and not as instructions from an outside party. In many cases various minerals. Unfortunately there is still a time delay of this does result in debate and discussion. However, once the up to three months to obtain detailed mineralogical decision has been taken the collective can then move analysis. forward. Understanding the floatability of the minerals in the ore is not only important in determining what flotation capacity Applying the flotation fundamentals (residence time) will be required in each stage of the circuit, In a number of cases the author has found that in optimizing but will also govern the operating strategy that is to be a PGM flotation circuit it has been necessary to consider applied to each flotation class. Fast floating minerals the fundamental processes occurring within the flotation require very little residence time and the author has found cell. For the purposes of this paper the author has divided that they are relatively immune to high depressant dosage the case studies into four areas namely the effect of pulp resulting in relatively high concentrate grades and characteristics, the reagent suite, the mineralogy, and the recoveries. cell geometry. Slow floating minerals are, however, prone to yield low recoveries at high grades and should therefore be treated in Considering the pulp characteristics a different circuit. In the first instance it is important to consider the mixing environment within the flotation cell. The duty of the Cell geometry and the flow of concentrate impeller arrangement is twofold: firstly to suspend the The cell geometry affects the hydrodynamics within a slurry within the cell, and secondly to disperse the air within the flotation cell. flotation cell and the relatively high specific gravity of The efficiency of the impeller is governed by the impeller chromite often results in chromite settling at the bottom of size, speed, geometry, and cell geometry. The mixing flotation cells. This effectively reduces the residence time efficiency is also governed by the viscosity of the slurry in the cells and increases the risk of cells sanding up. This that is affected by the particle size distribution, the slurry is also governed by the relative position of the impeller density, and the nature of the ore. High viscosity slurries arrangement, the design of the impeller arrangement, and inhibit the dispersion of the gas within the slurry. The effect the aspect ratio of the flotation cell. of high slurry viscosity on flotation performance has been The relative geometry between the cell volume and described by Nel et al. (2007). launder lip is an important consideration when considering Slurry density also has a significant effect on the a cell for a specific duty within a flotation circuit. Does the entrainment of solids and the effect of high slurry density operator require a short lip length for finer grade control or on the entrainment of chromite has been described longer lip to maximize recovery at the expense of grade? (Valenta, 2007). Case studies Ensuring a balance in the reagent suite The importance of maintaining a balance in the reagent This section of the paper discusses various case studies suite has been discussed by Valenta (2007). Frother has illustrating how the findings of a process review and the been shown to have a significant effect on the entrainment subsequent implementation of changes to fundamental of solids to the concentrate. Particularly in the case of operating parameters have improved the efficiency of chromite entrainment, this has been shown to be significant. operations. The amount and type of collector used is important in The fundamental parameters discussed are pulp density, determining what floatable minerals species are recovered cell geometry, flotation kinetics, circuit configuration, and to the concentrate. It is has been shown that collector can the reagent suite. affect the amount of entrained solids being recovered to the The case studies and the changes made may seem to be concentrate (Valenta, 2007) and that the importance of simple and obvious within the context of this paper. collector choice must not be underestimated. However, on a complex UG2 concentrator these parameters The use of depressant in the depression of floatable are normally clouded by other challenges that hide the true gangue species is well understood in the industry source of the poor efficiency. The findings presented were (Bradshaw et al., 2005). The balancing of the depressant the outcome of detailed structured process reviews. addition with the dosage of collector and frother addition is In the case studies graphs are presented over the period very important in the optimization of a PGM flotation plant. prior to the change and post the change to illustrate the effect of the change in flotation parameter. Due to the Considering the flotation response of the ore inherent noise in the data characteristic of a concentrator A key consideration in plant operation is the variability in operation, a seven day moving average is plotted to the floatability of the various mineral species in the ore. illustrate the trend. The flotation response is governed by a number of factors All PGM analysis reported was done by fire assay with including what minerals species are present and their lead collection and the analysis is an indication of the relative abundance, the degree of oxidation, the degree of content of the four elements (4E) i.e. platinum, palladium, liberation, and the mode of occurrence. rhodium, and gold in the samples. 16 PLATINUM IN TRANSITION ‘BOOM OR BUST’ Case study 1: Changing the pulp density to improve cell density in flotation circuits in order to reduce the overall performance capital cost of the project is very attractive; however, The metallurgical team was approached to help in the consideration must be given to the effect of operating at optimization of the concentrator as the flotation recoveries high pulp densities on the operability of the flotation cells. were low and did not meet the recoveries indicated by the The high chromite content in the concentrate can also be laboratory and pilot-plant test work. explained by the high pulp density. The effect of pulp The process review conducted by the metallurgists density on the entrainment of gangue mineral has been revealed that the flotation recovery in the primary rougher discussed (Valenta, 2006) and this fact must be taken into bank of the plant was very poor in comparison with the test account when designing the circuit. work findings, and typical recoveries observed on other operations. In addition, the chromite content of the rougher Case study 2: Reagent optimization in reducing concentrate was very high resulting in the final concentrate chromite in concentrate not meeting specification. In this case the concentrator was not able to meet the Mineralogical analysis of the primary rougher tailing stringent Cr2O3 grade specified in the smelter contract. A identified a significant proportion of the PGM as being plant audit was conducted and it was revealed that the liberated sulphides PGMs that would normally be overall frother dosage was very high and that frother was recovered. This implied that the losses were flotation being added to the cleaner flotation stages. process related, and not due to insufficient mineral The study of the effect of frother type and concentration liberation. on the entrainment of particles has been the topic of much Attempts to increase the aeration rate to the flotation cells work (Laskowski, 1993, 2004). The effect of frother dosage did not improve the recovery and the cells tended to geyser on the entrainment of chromite to the flotation concentrate with large bubbles rising to the surface and disturbing the has been presented in other work (Valenta and Harris, froth indicating that the flotation cell mechanisms could not 2007). disperse any more air. Based on the success in controlling the concentrate A number of changes were made to the reagent suite chromite content on other plants as reported in previous including an increase in the addition of copper sulphate, the publications (Valenta, 2007) the chromite in concentrate on introduction of a dithiophosphate collector, the introduction this concentrator was significantly reduced by reducing the of an alternative xanthate collector, and an increase in the frother to the primary and secondary rougher stages, as overall collector dosage. The changes to the reagent suite illustrated in Figure 5. The operators were given the latitude were not successful and the mass recovery to the to change the frother dosage to the two rougher banks. concentrate remained low. However, the combined frother dosage was not allowed to An analysis of the availability of the primary rougher be more than 17 g/t of feed. Although the Cr2O3 grade is flotation cells revealed that the flotation cells tended to trip still above the 1.5% mark, the risk of the concentrator regularly on electrical overload. A survey of the operation having the concentrate returned is significantly reduced. found that the flotation cells were drawing well in excess of The smelter penalties were also significantly reduced. the rated loading of the motors (3 kW/m3 of flotation cell It is interesting to note from the Figure 5 that once the volume). effect of frother had been demonstrated to the operation Running the flotation cells empty indicated that the high personnel, the variation in frother dosage has reduced power draw was not due to mechanical problems but rather significantly. due to the high pulp density that the cells were being It must be noted that the change in frother dosage was not operated at. The relative pulp density in the feed to the first done in isolation. As discussed in a previous paper rougher cell was constantly above 1.5 with the last rougher (Valenta, 2007), the control of concentrate grade requires a cells operating at relative pulp densities in excess of 1.65. balancing of the reagent suite. The reduction in the frother The high pulp density/viscosity would account for the dosage also required a concomitant increase in the collector high power draw under load and the poor recovery as the dosage to the cleaner bank and a decrease in the depressant pulp density would inhibit the dispersion of gas in the dosage to the rougher bank. flotation cells. A similar situation was previously reported on cleaner flotation cells on a UG2 concentrator (Nel et al., 2007). It was recommended that the pulp densities be reduced, and the improvement in primary rougher recovery is illustrated in Figure 4. The rougher concentrate sample is not normally taken on shift and special samples had to be taken as part of the optimization programme. The primary rougher recovery was calculated using the two product formula (using the shift sample assays for the feed and tailing streams) and the corresponding average pulp density was extracted from the data historian. The change resulted in the operators being able to increase the air to the flotation cells without a repetition of the geyser effect. The ability to add more air also allowed for changes to be made to the reagent suite, specifically an increase in depressant to change to froth stability. The control of pulp density and effect of pulp density on the operation of the flotation cells is often overlooked. The Figure 4. Effect of reducing pulp density on primary rougher opportunity for the design metallurgists to increase the pulp efficiency APPLICATION OF FUNDAMENTALS IN OPTIMISING PLATINUM CONCENTRATOR PERFORMANCE 17  Based on the findings of the laboratory test work, primary and secondary rougher concentrates exhibiting similar flotation behaviour were combined in different cleaner circuits, as illustrated in Figure 6. The results of the change in the flotation circuit are illustrated in Figure 7. It must be stressed that the change in flotation circuit alone did not result in an increase in the concentrate grade but it allowed for the optimization of the reagent suite. Where previously high depressant dosage to the primary cleaner circuit had resulted in a collapse in the flotation froth, this change in the circuit allowed for the addition of high depressant dosage with no loss in flotation recovery for the whole circuit. The final concentrate grade of the overall circuit Figure 5. Effect of frother dosage on the chromite content in increased and the risk of not meeting the minimum grade concentrate specification was addressed. Case study 4: Increasing the PGM grade by changing Case study 3: Meeting grade specifications by the cell geometry optimizing the circuit Flotation cells are supplied in different shapes and sizes In certain cases the design of the flotation circuit does not depending on the hydrodynamics within the flotation cell. suit the ore mineralogy and the flotation kinetics exhibited Furthermore, various configurations of concentrate launders by the PGMs. with different lip lengths have been designed to cater for Matching the flotation kinetics of the various the flow of concentrate from the cell. These changes to the concentrates to allow for the production of a high grade concentrate launder lip length are driven by a number of primary concentrate and a low grade secondary concentrate factors including the floatability of the mineral and the has found favour in the UG2 industry. desired grade of concentrate required from the cell in In this specific case the feed to a UG2 concentrator whichever application. changed and it was found that the concentrator could not The metallurgical team was faced with the dilemma that achieve the concentrate specification stipulated by the the desired concentrate grade could not be achieved even smelter agreement. Addition of depressant was not though both the depressant dosage had been increased and successful as high depressant dosage resulted in the cleaner the aeration rate had been reduced to a minimum. In other cell froth collapsing. A survey was conducted and the words, the flow of concentrate could not be reduced any opportunity was identified to increase the grade of the further without resulting in a collapse of the froth and no concentrate without compromising the overall flotation concentrate being recovered. recovery. It is known that flotation concentrate flow rate can be Flotation tests were done on samples taken of the various controlled by the adjustment of the cell concentrate weir rougher flotation concentrates and it was found that the (Woollacott and Eric, 1994). In banks of trough cells concentrates could be grouped according to the flotation consisting of up to four cells per bank cell slats have been response in the laboratory cell. It was also observed that the used to control froth depth in one cell relative to the level in concentrates appeared to respond differently to depressant other cells. In so doing the introduction of cell weirs result dosage with some froths collapsing while other froth in a reduction in the effective lip length in the bank of remained stable and yielded high concentrate grades. flotation cells. Figure 6. Changes made to the flotation circuit based on flotation kinetics 18 PLATINUM IN TRANSITION ‘BOOM OR BUST’  Figure 7. Increased primary concentrate grade with change in Figure 8. Increase in grade with a change in lip length flotation circuit depressants on the behaviour of the froth phase in In this case the flotation cells used as primary final flotation. Centenary of Flotation Symposium, cleaner cells were tank cells that were introduced as part of Brisbane, Australia, 2005. a circuit configuration exercise similar to the one described LASKOWSKI, J.S. Frothers and Flotation Froth, Mineral in Figure 7. Tank cell pulp levels are normally controlled Processing and Extractive Metallurgy Review, per cell and the need for slats on tank cells has not been a vol. 12, 1993. requirement. Based on the successful use of slats on trough cells to LASKOWSKI, J.S. Testing flotation frothers, control concentrate flow rate on other operations it was Physicochemical Problems in Mineral Processing, recommended that slats be installed at regular intervals on vol. 38, 2004. the circular cell lip. The improvement in concentrate grade with a reduction in the lip length is illustrated in Figure 8. MCCLAREN, C.H. and DE VILLIERS, J.P.R. The The change in the lip length allowed for a further increase Platinum-Group Chemistry and Mineralogy of the in the depressant dosage with a concomitant increase in the UG-2 Chromitite Layer of the Bushveld Complex. final concentrate grade. Economic Geology, vol. 77, 1982. pp. 1348–1366. NEL, E., COETZEE, V.E., KUMALINGA, N., and Conclusions VALENTA, M. The effect of high cleaner feed The operator of a UG2 concentrator is faced with a number density due to upstream thickening on cleaner circuit of challenges from a concentrate grade and recovery performance. Minerals Engineering International perspective. In some cases operations have to compromise Flotation ’07 Conference, Cape Town, 2007. the recovery in order to meet strict concentrate grade OVERBEEK, P.J., LOO, J.P., and DUNNE, R.C. The specifications imposed by the smelter. This is made development of a concentration procedure for difficult by the presence of two major gangue phases in the Platinum Group Metals and Chromite from the UG-2 ore and the complex mineralogy of the PGM minerals. Reef of the Bushveld Complex. 1st Symposium on The case studies discussed illustrate that the opportunity Precious Metals Recovery, Nevada, USA, 1984. exists to optimize the concentrators through a process of detailed analysis, identification of problem areas and the PHILIPS, R.E., JONE, R.T., and CHENNELLS, P. optimization of the fundamental flotation parameters. The Commercialisation of the Conroast process, Third changes do not have to involve complex costly circuit International Platinum Conference ‘Platinum in changes and incremental improvements can be made to the Transformation’, SAIMM, 2008. concentrator performance through the implementation of VALENTA, M.M. Balancing the reagent suite to optimize changes to the fundamental parameters. grade and recovery, Minerals Engineering Journal, The optimization methodology has been successfully vol. 20, iss. 10, August 2007. used on UG2 and Merensky operations and will be applicable to most flotation plants. VALENTA, M.M. and HARRIS, M.C. Evaluation of The establishment of a team including the consultants, Entrainment in Flotation within a Mechanistic maintenance and operational staff is paramount to the Framework. SAIMM Minerals Processing 2005 success of any such optimization endeavour. Alienation of Conference, Cape Town, 2005. the metallurgist is very common in cases where the metallurgist is introduced as a ‘fixer’. That is not the VALENTA, M.M. and HARRIS, M.C. Quantifying the objective and a common goal for the identification of effect of entrainment in mineral flotation using a opportunities and optimization of the operation must be mechanistic model. Minerals Engineering established from the outset. International Flotation ’07 Conference, Cape Town, 2007. References WOOLLACOTT, L.C. and ERIC, R.H. Mineral BRADSHAW, D.J., HARRIS, P.J., and O’CONNOR, C.T. Extraction: An Overview, SAIMM Monograph Series The effect of collectors and their interaction with M8, Chapter 5D: Flotation, 1994. APPLICATION OF FUNDAMENTALS IN OPTIMISING PLATINUM CONCENTRATOR PERFORMANCE 19  Michael Matthew Valenta Managing Director, Metallicon Process Consulting (Pty) Ltd A product of the Belfast High School, Michael graduated from Wits University in 1990 with a degree in Extractive Metallurgy. He joined Mintek in 1991 in the Sulphide Flotation Group where he took over the responsibility for the pilot plant operations. The focus of the Sulphide Flotation Group at that stage was the optimisation of the flotation process for the recovery of PGM from the UG2 ore. Much work was done in understanding the effect of various parameters on the recovery and grade of flotation concentrate. He left Mintek in 1994 and worked for Lonplats for nine years, of which he spent 4 years as Plant Superintendent at the Karee Concentrator, and three years as Production Manager at the Western Platinum Refinery. Michael joined Hatch in 2003 as Consulting Metallurgist and spent much of his time consulting in South America and South Africa on concentrator projects. Michael left Hatch in 2005 to establish Metallicon Process Consulting, a consulting company focussing on providing process engineering services to the industry. Metallicon has provided process engineering services to the majority of the Platinum producers in the industry. He is a founding member of the Metanza Group of Companies that is developing various opportunities in the platinum industry including the recovery and beneficiation of Platinum Group Metals and chromite from tailings and low grade streams. Michael is a past president of the Mine Metallurgical Managers’ Association and has served on the MMMA council for the past 12 years. In that period he has represented the MMMA on the SAIMM council. He is a registered professional engineer under ECSA and is also registered on the international register as defined by the Washington Accord. 20 PLATINUM IN TRANSITION ‘BOOM OR BUST’