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By William Conger, Greg Schick

Grinding media consumption is a major cost variable in industrial mineral comminution circuits. Specifically, industrial SAG media consumption results from a combination of surface abrasion wear, media breakage, surface spalling and rejection size from the mill. Three main consumption rates; weight of media consumed per time, per kWh and per weight of ore ground are defined and compared. Recent industrial data has provided an opportunity to relate consumption in terms of weight of media consumed to weight of ore ground (g/tonne) and weight of media consumed per kWh of energy consumed (g/kWh) with SAG specific grinding energy consumed (kWh/tonne). Using relationships developed from this data it is possible to project SAG media consumption in future mineral comminution circuits.

Jan 1, 2014

By Z. K. Liu

Production of the amines collectors and cation surfactant gives out the liquid waste containing high COD (Chemical Oxygen Demand) and ammonium & nitrogen, which is difficult to be treated with conventional biological method to reach waste water discharge standard. In this paper an engineering practice of treatment on the liquid waste by the technology combined high effective microbe with A/O (Anaerobic& aerobic) process is presented. The quality of treated water comes up to class A national standard for discharging.

Jan 1, 2014

By Hongchun Lou, Yan Zhang, Xianjun Lu

"The potential of Fe(NO3)3 modified attapulgite was assessed for the adsorption of phosphorous removal from aqueous solutions. Natural attapulgite was modified by Fe(NO3)3, and thus the composite adsorption materials could be obtained. Also phosphorous adsorption characterization on the iron-coated attapulgite was investigated in this research. Taken overall the results suggested that phosphorous adsorption capacity could be improved markedly by adopting ferric modified-attapulgite. The optimum phosphorous adsorption were developed in the experimental conditions of the solid-to-liquid Ratio 1g/L, the initial phosphorous concentration 5 mol•L-1, reaction time 120 min, temperature 25 ? and pH=4.0, the removal efficiency is 92.28% for the modified attapulgite. In comparison of batch experimental results of phosphorous adsorption onto natural and iron-coated attapulgite, it has provided much more likely the same change trend. On the other hand, the outcomes of this analysis indicated that ferric modified adsorbent was notably influenced by adsorption element over natural attapulgite. The Freundlich isotherm adequately described the adsorption course of phosphorous onto ferric modified-attapulgite with the correlation coefficient R2 goodness of fit of 0.9690."

Jan 1, 2014

By Yizhong Yuan, Dao Li, Nannan Xue, Tao Liu, Yimin Zhang

A new multi-stage counter-current circulation leaching process for extracting vanadium from stone coal was proposed, and the main factors on multi-stage counter-current circulation acid leaching process were investigated. The results show that the vanadium recovery could reach 86% under the conditions of sulfuric acid concentration of 4 M, liquid to solid ratio of 2 mL/g, temperature of 95 °C, reaction time of 60 min, mean particle size of 125 µm and circulation acid leaching stage of three. The losses of vanadium in acid leaching solution appeared during the four-stage acid leaching process. The strong adsorption performance of new formed KAl(SO4)2(H2O)12 crystal was main reason.

Jan 1, 2014

By M. Karamoozian

Modelling and optimisation of the power draw of large SAG mills are important due to the large power draw which modern mills require (5~10 MW). The cost of grinding is the single biggest cost within the entire process of mineral processing. Traditionally, modelling of the mill power draw has been done using empirical models. Although these models are reliable, they cannot model mills and operating conditions, which are not within the model database boundaries. Also, due to their static nature, the impact of the changing conditions on the power draw, within the mill, cannot be deter-mined using such models. Despite advances in computing power, on-line modelling of large plant scale mills could be a time consuming task. On the other hand, using on-line parameters for model-ling, result in more reliable control of SAG mill without performing any more costly tests. In this paper, SAG mill power draw is modelled using neural network approach. Six inputs, namely: solid percent, two bearing pressures, noise, recycle and feed rate were used to model the power draw. The produced model shows an acceptable correlation coefficient, R2 =0.9623.

Jan 1, 2014

By G. R. Forbes

Flotation froth machine vision systems provide consistent real-time measurements pertaining to the state of the flotation cell being monitored. Typical measurements include froth velocity, froth colour, froth texture and froth stability. This paper presents the results from test work conducted on the molybdenite rougher circuit at the Kennecott Utah Copper Concentrator during February 2006. Machine vision results show that it is not possible to accurately determine bubble size distribution information for the molybdenite froth, despite using state-of-the-art methods. Instead, it is necessary to make use of texture measurements to classify the various different froth states. Numerous combinations of texture measurements and classifiers are used to determine the best combination. Results show that the Fourier ring based texture measurements perform the best when both K nearest neighbour and Gaussian mixture model classifiers are used. The concentrate grade of the flotation cell is modelled using combinations of froth velocity and froth texture descriptors. The results show that by using a linear combination of these descriptors rather than either one by itself it is possible to account for a much larger percentage of the variation observed in the concentrate grade data. Adjusted R2 values of 92% and 84% are achieved when modelling the copper and the molybdenite concentrate grade respectively.

Jan 1, 2014

By M. Ghiani, P. Massacci, A. Manni, R. Peretti, Center for Mining and Mineralurgical Studies, S. Serranti

"The research study has been devoted to point out the better way to process a colemanite concentrate characterised by a high content of two kind of As sulphides (realgar and orpiment) finely disseminated in the matrix of the boron mineral.Scanning Electron Microscopy analyses have been carried out to determine all the mineralogical constituents and to evaluate their distribution, frequency and mutual relationships.There is a not neglectable part of realgar highly disseminated into the colemanite crystals.The orpiment recurs in small acicular crystals of 20÷30 µm in length and 5 µm in width, very difficult to liberate from the colemanite mineral particles.The colemanite concentrate, in fact, has been addressed to a chemical plant which products were boric acid and gypsum, the contaminated by As. It was unacceptable for further applications and very dangerous if rejected in the environment.Grinding tests under dry and wet conditions have been carried out in order to evaluate the liberation modality of the As sulphide minerals from the colemanite.Some difficulties have been overtaken in order to obtain a selective liberation of the As sulphides from the colemanite even if a certain decreasing in As grade in the higher size classes has been registered.All the comminution products have been analysed by SEM monitoring the liberation degree of the mineralogical constituents.Flotation tests have been carried out after different comminution flow sheet adopting different modulating conditions in order to evaluate the influence of the following parameters:• collector concentration versus contaminants concentration (As minerals) in the froths;• kind and quantity of the frothing agent to maximise the mineral recovery in the froths;• kind and quantity of the modulating agents to maximise the selectivity of the process;• conditioning modalities in order to obtain a suitable dispersion of fines and to avoid segregation of Asbearingparticles together with colemanite ones;• solid/liquid ratio of the pulp to minimise the water flow into the plant."

Jan 1, 2003

By Minna Päällysaho

For the first time, the idea of sustainable development was recognised at a high political level at the UN Conference on Environment and Development held in Rio de Janeiro in 1992 (UNEP, 1992). Then the governments of the world committed themselves to promote sustainable development in their national activities and international co-operation. In 2001, the European Council approved the EU Strategy for Sustainable Development (European commission, 2011). This complements and supports the EU?s so-called Lisbon Strategy (European council, 2000) on competitiveness. The revised Strategy for Sustainable Development was approved in June 2006. Recently sustainability has had an important role in policy and decision-making while the public awareness towards limits of the environment has been rising. However, the indicators of industrial sustainability satisfy primarily the needs of corporate management and global investors. The information is often broad and non-specific and might occasionally even give a false impression. Moreover, contradictions between environmental, economical and social aspects also point out the unreliability of existing sustainability indexes. Therefore, the current state of affairs serves the interests of neither the industry nor the policy makers. Current corporate sustainability indexes and indicator systems need to be assessed with scientific methods encompassing the identification of their strengths and weaknesses. This requires quantitative and qualitative assessment and synthesis of existing indexes and indicator systems, providing new data on the functionality of existing corporate sustainability indicators. Therefore, the assessment lays the foundation for the development of new, more balanced sustainability index. Our first aim in this multidisciplinary article is to analyse existing global sustainability indexes for process industry. Second, we will introduce a first version of a new sustainability index for process industry, which includes the environmental, social and economic impacts of the plant, as well as legislation aspects.

Sep 1, 2012

By Robin J. Batterham

Alumina demand is steadily climbing around the world and is likely to continue to do so for many years. In such a commodity industry, the question arises as to what effort should be expended on innovation, given that for an individual company, the drivers of change are cost and quality as the market demand is essentially assured. This is of course a long-term view. The current conditions are less attractive. In this presentation, we review the broad issues that are considered targets for collaborative development by the industry as recently updated in the alumina industry roadmap published by the International Aluminium Institute in 2010. While they cover areas such as ?mine rehabilitation, residue management and use, alumina production from high sulfur bauxite, bauxite beneficiation, energy efficiency and alternative technologies for alkali and alumina recovery from bauxite residues,? it must be remembered that each refinery is different in terms of the feed material and the circumstances of waste disposal. Of particular interest is the more competitive area of breakthrough technologies. In the presentation, we will consider a range of opportunities that could transform the industry, from relatively near term possibilities such as bauxite activation through possibilities to eliminate crystallization as currently practiced to complete alternatives, such as the use of hyperaccumulating plants. Against this optimism, some of the realities that hold back breakthrough innovation will be presented for discussion.

Sep 1, 2012

By Lev Malytin, Alexander Dyachenko, Roman Kraydenko

"A new method of processing beryllium raw materials based on interaction of beryllium mineral with ammonium fluoride was developed. Possibility of extracting ammonium tetrafluoroberyllate from bertrandite and phenakite minerals is proved. The developed technology allows replacing the outdated sulfate technology developed by Materion Corporation. INTRODUCTION Beryllium is a strategic metal, which is produced only in three countries: the USA, China and Kazakhstan. The world production of beryllium amounts to only 300 tons per year. More than 75% of the world beryllium production is manufactured from oxide beryllium ores in the USA by Materion Corporation. In Russia there is a large-scale beryllium ore deposit «Ermakovskoye» containig over 1 million ton of ore. Concentration of beryllium in ore amounts to 1,2%. Since the mineral base of ore is calcium fluoride, the sulfate technology of Materion Corporation cannot be used. After alloying and sulphuric acid leaching the fluorine-ion found in fluorite and beryllium together evolve into the aqueous phase. At the stage of Be(OH) precipitation fluoride-ion prevents complete isolation of beryllium into the phase of hydroxide, which increases the loss of beryllium. A new ammonium-fluoride method for processing high-fluoride beryllium ores has been developed at Tomsk Polytechnic University. The ammonium-fluoride method involves fusion of ammonium fluoride (NH4HF2) with a beryllium concentrate. The concentrate containing 10% of beryllium oxide and 25% of calcium fluoride is produced by flotation from the ore of Ermakovskoe deposit. The main component of the ore concentrate is fluorite CaF2, which does not react with NH4HF2. Beryllium in this concentrate is represented by two minerals: phenakite Be2(SiO4)2 and bertrandite Be4[Si2O7](OH)2. Ammonium fluoride, unlike sulfuric acid, does not react with calcium fluoride and is not consumed for decomposing the mineral base of the concentrate. Ammonium fluoride is an accessible and environmentally safe reagent, worth up to $ 1,200 per ton. The total amount of ammonium fluoride is recycled and is used for decomposing a new batch of beryllium concentrate."

Jan 1, 2018

By Lev Malytin, Alexander Dyachenko, Roman Kraydenko

"A new method of processing beryllium raw materials based on interaction of beryllium mineral with ammonium fluoride was developed. Possibility of extracting ammonium tetrafluoroberyllate from bertrandite and phenakite minerals is proved. The developed technology allows replacing the outdated sulfate technology developed by Materion Corporation. INTRODUCTION Beryllium is a strategic metal, which is produced only in three countries: the USA, China and Kazakhstan. The world production of beryllium amounts to only 300 tons per year. More than 75% of the world beryllium production is manufactured from oxide beryllium ores in the USA by Materion Corporation. In Russia there is a large-scale beryllium ore deposit «Ermakovskoye» containig over 1 million ton of ore. Concentration of beryllium in ore amounts to 1,2%. Since the mineral base of ore is calcium fluoride, the sulfate technology of Materion Corporation cannot be used. After alloying and sulphuric acid leaching the fluorine-ion found in fluorite and beryllium together evolve into the aqueous phase. At the stage of Be(OH) precipitation fluoride-ion prevents complete isolation of beryllium into the phase of hydroxide, which increases the loss of beryllium. A new ammonium-fluoride method for processing high-fluoride beryllium ores has been developed at Tomsk Polytechnic University. The ammonium-fluoride method involves fusion of ammonium fluoride (NH4HF2) with a beryllium concentrate. The concentrate containing 10% of beryllium oxide and 25% of calcium fluoride is produced by flotation from the ore of Ermakovskoe deposit. The main component of the ore concentrate is fluorite CaF2, which does not react with NH4HF2. Beryllium in this concentrate is represented by two minerals: phenakite Be2(SiO4)2 and bertrandite Be4[Si2O7](OH)2. Ammonium fluoride, unlike sulfuric acid, does not react with calcium fluoride and is not consumed for decomposing the mineral base of the concentrate. Ammonium fluoride is an accessible and environmentally safe reagent, worth up to $ 1,200 per ton. The total amount of ammonium fluoride is recycled and is used for decomposing a new batch of beryllium concentrate."

Jan 1, 2018

By R. Batterham

"The history of mineral processing is indeed long and has always been tied to mining methods of the day. While many new processes and devices have been developed, the most significant trend in recent times has been the ever increasing scale of operations. There is serious doubt this ongoing trend is enough to match the global trend of falling grades and rising energy demands needed for mineral processing. As well we see that globally, the social licence to operate for mining (and hence mineral processing) is far from secure. Indeed, some argue that mining as we know it is dying and in the future, mining will be much more environmentally secure, even to the extent of insisting upon “in place” recovery and only bringing to the surface the valued product. In this paper we comment on the ramifications of broader uptake of more sustainable mining for mineral processing methods and address the specific question of whether recent progress in in place recovery will lead to a timely breakthrough. The answer proposed is that this is possible in the next 10 - 20 years but in the meantime, the focus is just as likely to be on removal of waste much earlier in circuits. Either way, mineral processing as we know it will change significantly. INTRODUCTION Mineral processing has a long history well covered in a recent publication (Habashi, 2006) who points out “the ancient Egyptians knew already that it would be easier to melt an earth rich in gold particles than another which is poor. As a result, all efforts were made to enrich the gold by washing away the light gangue minerals. Similarly, another ancient method for enriching gold particles from a river stream was by means of fleece, hence the Greek myth of the “golden fleece”. Since the middle ages, striving for improved economics has driven a string of innovative developments in milling and separation. The reader is again referred to the informative and illustrative text by Habashi."

Jan 1, 2018

By Dee Bradshaw

"Process mineralogy’ is a form of applied mineralogy which focuses on addressing problems associated with the processing of ores. ‘Mineralogy’ is the scientific study of minerals and ‘mineral processing’ is the production of concentrates from ores. ‘Process mineralogy,’ however can be defined as the practical study of minerals associated with the processing of ores, concentrates and smelter products for the development and optimisation of metallurgical flowsheets, including the waste and environmental management considerations. This hybrid discipline consists of teams that include geologists, mineralogists, samplers, mineral processors and often others, working together. The degree of cross-training, communication and trust dictates the potential capacity of the team and where an appropriate work dynamic is fostered, in which relationships flourish as much as does the ethic of technical excellence, it is possible to develop technical capabilities that surpass those of conventional teams. The world’s demand for metals is ever increasing and ore deposits available for extraction and processing are lower grade and more complex, often containing deleterious elements that require tailored treatment. Generally, in the past, the technical challenges only needed to be overcome and assessed economically to make an ore deposit viable; increasingly and in the future, a more sustainable approach including environmental and societal considerations is needed. Process mineralogical assessment is increasingly providing the critical information that stands between failure or collapse and survival or success of some mining operations. In this paper, selected case studies are used to demonstrate the valuable role of the process mineralogy tools being used to provide the platform for innovative technology development. Their common attributes are discussed and distilled, thus providing some insights and potential guidance for addressing some of the likely future challenges of the mining industry."

Jan 1, 2014

By Bertil I. Pålsson

The most common REE containing mineral that is worked today is bastnäsite. It means that mineral processes are adapted to it and that the metallurgical separation techniques for winning of individual REE are adapted to bastnäsite concentrates. For all other deposit types, suitable mineral processing methods and separation technologies need to be adapted and/or developed. Preliminary mineralogical analyses indicate that slightly less than half of the REE in the tailings dumps at LKAB/Kiruna are associated to apatite. The rest is in the minerals monazite (maybe associated to apatite) and allanite. At least allanite is probably not floatable with reagents commonly used for apatite. Mass and element distributions for the tailings sand reveal that very little apatite is present above 300 µm, and that approx. 30 % is below 20 µm. REE does not follow P2O5 completely and are also present in coarser fractions. Flotation results show that the best condition for both apatite and REE winning is pH 9, high collector addition and low dosage of water glass. Under these conditions, the lab-scale flotation gives an apatite concentrate with at least 30 % P2O5 at 70 % recovery. REE follows apatite in the cleaner steps but only partly. Its recovery is approx. half compared with apatite. The reason for the low REE recovery is likely to be that REE to a large extent is trapped in non-winnable minerals, especially allanite. The REE grades in the concentrate are expected to be in the range 3000 ? 4500 g/ton. Keywords: flotation, REE, apatite, monazite, allanite

Sep 1, 2012

By S. Swaroopa

Copper-chromium mixed oxides are widely used as catalyst for organic chemicals industry, NOx and CO oxidation, solid propellant etc. In the present investigation, one such spent Cu-Cr catalyst has been tested for recovering copper and chromium values through hydrometallurgical route. The spent catalyst used in this study contains about 42% Cu and 36% Cr. Phase analysis through XRD indicates that major phases are copper chromium oxide (CuCrO2) and copper chromate (CuCr2O4) while minor phase is copper oxide (Cu64O). SEM images show that high energy ball milling changes surface morphology significantly ? more regular shaped grains in unmilled samples changed to fine agglomerates. Surface area also changes significantly due to milling. Preliminary leaching experiments with NH3 and H2SO4 media using unmilled samples indicate that both the media are suitable for selective extraction of copper. About 55% copper recovery is achieved in 2 h using 1.2 M NH3 + 0.2M (NH4)2SO4 solution at 100°C. Increasing NH3 concentration or temperature does not improve the recovery significantly. Under the above conditions chromium, dissolution is insignificant (max. 2.24%). XRD analysis of the residue indicates that copper chromate fraction (CuCr2O4), which is a spinel structure, remains mostly intact. In sulphuric acid media at ambient temperature, 47% copper recovery is achieved with 7.5% (v/v) H2SO4 and maximum of 57% with the increase in acid concentration to 20%. However, 67% recovery is achieved by increasing the leaching temperature to 150°C. High energy ball milled samples show improved leaching efficiency. Under the leaching conditions of 7% H2SO4 (v/v), 2% pulp density, 80°C an unmilled sample yields 47% Cu recovery whereas 3h and 5h milled samples yield 65% and 90% Cu recovery respectively in 2h leaching time. Influence of temperature is also more pronounced in milled sample leaching in comparison to unmilled sample. Water leaching of alkali (NaOH) roasted milled sample carried out at 750°C for 2 h with 100% NaOH (w/w) resulted in 80% Cr recovery as compared to 37% Cr recovery using unmilled sample under the same conditions. Keywords: spent catalyst, copper, chromium, leaching, mechanical activation, roasting

Sep 1, 2012

It is well known that the crushing and grinding steps in the mineral processing of ores represent a substantial proportion of total energy, cost and carbon emission in mining. For instance a recent study calculated that 36% of the energy consumed by gold and copper producing mines in Australia was attributable to comminution (Ballantyne et al, 2012). Understanding this component of a business is essential in a world seeking to lower production costs, improve earnings and reduce its carbon footprint. The issue commands the attention and support of industry leaders in the mining sector, government, equipment manufacture, engineering design and research organizations. Furthermore, several researchers have often stated that globally, comminution processes consume between 3-4% of the world?s electrical energy production (Daniel and Lewis-Gray, 2011). In 2009-10, Australia?s Federal Government Energy Efficiency Opportunity (EEO) participants in the mining sector used 336.5 PJ, representing approximately 6 percent of Australia's total energy use. It is evident that the current practices of breaking rocks in tumbling mills are relatively inefficient (Fuerstenau and Abouzeid, 2002). Research and improved engineering design has established that a range of improved blasting, crushing and grinding techniques and flow sheets may lower project costs and carbon footprint. These include relatively simple process flow sheet strategies such as gangue rejection or pre-concentration prior to size reduction, a better combination of grinding technologies (both current and new systems), and selection of coarser grind sizes where ore and waste mineralogy allow. Yet, despite this systematic and detailed research, the industry remains somewhat reluctant to implement these strategies. CEEC (Coalition for Eco-Efficient Comminution) was established in 2011 to support knowledge sharing and change in an area of high-energy consumption for the global mineral industry. CEEC is a not-for-profit industry company, funded by grants from world wide industry companies, whose mission is to accelerate knowledge and technology transfer in the field of energy-efficient comminution. The key benefit to the mining sector arising from CEEC?s activities will be an increase in the rate at which more energy-efficient comminution data sets, processes, and technologies are developed, demonstrated, shared and applied. This will contribute directly to the industry?s target of reducing operating costs and carbon emissions. CEEC International Ltd and JKTech Pty Ltd teamed together to facilitate the inaugural CEEC Workshop, in June 2012. The purpose of the workshop was to produce a roadmap to provide guidelines for how (1) operations can achieve best EEC practice in the short to medium term, in collaboration with vendors, engineering companies and other service providers, and (2) what R&D is needed to achieve paradigm change in EEC in the medium to long term, e.g. 75% reduction in comminution energy in 10 years.

Sep 1, 2012

By Mike Hollitt

The first decade of the 21st century was one of fundamentally changed dynamics for the minerals industry. Following intense globalization commencing in the late 20th century production is now concentrated into large businesses that can compete across geography in diverse commodities. Asian industrialization and urbanization is now the main driver of growth in demand for energy and materials. Demand for the output of these industries has risen sharply, reversing decade long trends to reduced real commodity prices. Supply responded with expansions of existing mining and processing operations, and large investment in new resource development. Development of new, lower grade or more remote resources was stimulated. Resource development by global entities in frontier environments reinforced the importance of effective forms of social contract, and of stronger environmental performance. The worst economic shock in decades provoked no significant pause despite large impacts on corporate ownership. State owned enterprises commenced unprecedented foreign direct investment in minerals and energy resources. A thrust towards resource nationalism re-emerged as governments sought to ensure that the export of state owned resources contributes more strongly to government revenue, reducing the burden of trade in scarce resources on other trade-exposed sectors. The unprecedented combination of forces at work has made future predictions difficult, with day-by-day volatility in anticipated corporate fortunes, and investment plans. The challenge for process innovation (and for exploration) has been to keep up, maintaining a lid on costs as lower grade and more challenging ore bodies are brought on quickly in a context of competition for land use, community expectations and continued care for natural and living environments. While new projects have provided the necessary platforms for implementation of innovative approaches, there is evidence that a gap may have emerged between the pace of growth and the pace of innovation. The history of a century of process innovation in the context of growth of output, declining resource grades and commodity prices is presented. The necessary conditions for accelerated process innovation are considered, and future needs and approaches are discussed. Keywords: process innovation, resource development

Sep 1, 2012

By M. Marinov

The Bulgarian deposits of quartz-kaolin raw materials are localized in the NE Bulgaria. For many years, the quartz-kaolin sand separation has been performing by water washing technology. After wet separation the raw material yields two products ? washed kaolin (different grades) and quartz sand (different grades). Research and development program has started to improve the quartz-kaolin sand separation. The program has undertaken an increasing of processing capacity, to decrease the losses in the tailings and to provide production of new quartz sand grades. The kaolin-silica raw materials from Vetovo open mine and the technological tailings from Vetovo processing plant were characterized. It was established that there are a lot of losses of quartz in final tailings. New approach on kaolin-silica raw material separation was tested in laboratory scale. The test work was performed on Derrick Stacksizer screening machines. The results of laboratory experiment show that there are possibilities to increase the quartz sand recovery and to start the production new grade sand. The full-scale pilot test was performed including the following units: two Derrick Stacksizer screening machines equipped with 0.430 mm and 0.150 mm opening Derrick Urethane Panel, respectively; Flat bottom DN 500 Hydrocyclone and DN 100 Hydrocyclon. The pilot test data clearly demonstrate that the Derrick Stacksizer screening machines are suitable for Bulgarian silica-kaolin raw material. Based on the test data a new quartz-kaolin separation technology was developed. The new technology was introduced in Vetovo processing plant increasing processing capacity and decreasing the losses of quartz in final tailings. Additionally the production of silica sand grade PK 0.16 is increased and starts the production a new grade PK 0.10.

Sep 1, 2012

The concept of the Unified Comminution Model (UCM) was presented at the 23rdIMPC. The model utilises computational techniques to calculate the mechanical environment in any comminution device, and then incorporates the outcomes from rock breakage tests to predict the product from a device. The model is fully mechanistic, and incorporates the capability to simulate novel equipment. This paper presents the progress on the first application of this concept to applied comminution equipment. This novel comminution model aims to integrate all comminution models within a single struc-ture. This will provide a step change in the predictive power of comminution models, and include a wide range of particle properties that will enable it to be linked to the upstream and downstream process of mining and recovery. Major advances over current models will be the capability to predict liberation, preferential grinding, performance of new and novel devices, and to have power as an integral driver of the comminution simulation process. The methodology and model structure have been developed. An equation within a population balance framework has been derived as the basis for the UCM. A set of SAG mill pilot has been used as the first test case. The breakage characteristics of the ore have been extensively tested utilising a new range of breakage tests required by the rigorous UCM structure. The mill was simulated with the EDEM - DEM software. A partial test simulation of the pilot SAG mill has been conducted. This serves to demonstrate the feasibility of this modelling technique, but still lacks important ore characterisation components that are under development. The study has raised a number of significant challenges to the accepted understanding of the comminution process. Through addressing these challenges considerable insight has been gained into the energy environment in mills and the requirements of breakage testing. The ore characterisation methods and energy transmission derived from DEM simulations remain as major research items.

Jan 1, 2014

By N. S. Phala

Declining gold grades, mineralogical complexity of ore bodies, increasing input costs, more stringent conditions in the licenses to operate, and uncertain gold price dynamics combine to exert significant ongoing pressure on margins of gold producers. Innovative approaches of extracting the metal from its ores are required to realize value from existing and future assets. In a conventional gold processing plant, size reduction of mined ore to produce floatable or leachable product is a significant cost contributor. A step change in cost reduction will be attained if radically energy efficient grinding approaches can be developed, replacing tumbling mills. In the path towards that goal, some quick wins are possible through waste rejection before grinding, and pre-treatment of mill feed to reduce grinding energy demands. Gold locked in complex mineralizations puts pressure on margins by increasing cost per oz (typically high $/t and low metal recoveries) in the hydrometallurgical steps. Gold miners are primarily price takers. The current narrow range of gold uses (predominantly investment and jewellery) is not an entirely desirable state. Some diversification into commercial uses would potentially be a price stabilizer. In this paper, promising research directions, some not always fully explored in the gold metallurgy research space, are highlighted to stimulate radical innovation for substantial value enhancements. The author strongly believes a shift from a traditionally conservative and incremental innovation approach to a more aggressive one, across all aspects of the gold metallurgy value stream (processes to products), is what the industry needs. Keywords: gold metallurgy value stream, thiobaccilus ferroxidants, HPGR

Sep 1, 2012