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By Paul W. Cleary

"DEM application in mineral processing has for many years been heavily focused on simulating mills of various types. This method can be used to simulate many other aspects of mineral processing operations and can be used both to enhance understanding of the underlying flows and of issues such a breakage, wear, blockage, product degradation, segregation and mixing. The application of DEM to four important classes of non-comminution problems and equipment commonly found in or near mineral processing plants are described. These are:- Particle transport (examples include a conveyor belt and an inclined screw conveyor)- Sampling (assessment of sample bias for cross-stream samplers)- Separation (the efficiency of vibrating screens)- Storage and reclaim (discharge from a multi-port hopper and segregation in a splitter bin with asymmetric ingoing and outgoing conveyor belts, apron feeders and impact plate)."

Jan 1, 2003

By C. L. Tang

Parts of the wastewater are reused directly and the rest moderately purified and reused, so the utilization rate of wastewater of the whole processing plant reaches 100 percent. At the same time, beneficiation indicators have been improved stably, and great economic and social benefits have been achieved.

Jan 1, 2014

By Georges Delemontex, Nigel Grigg

"Pre-concentration of precious metal and base metal ore types is becoming more relevant with the discovery, development and operation of many lower grade deposits around the world. The fluctuations in metal prices and currencies expose many mines to risks especially dealing with low and variable ore grades. Pre-concentration, the process of concentrating the valuable metal into a smaller mass yield, effectively results in the introduction of higher feed grades to milling circuits. Gangue rejection, the removal of lower S.G. waste rock from the circuit, not only results in higher downstream grades but also potentially removes harder, non-valuable mineral, providing significant power savings within the circuit. The pre-concentration or ‘gangue rejection’ process offers a number of benefits when considering the treatment of marginal ore deposits, especially if it can be performed at a coarse crush size; these benefits include a reduction of the operating costs and the feed of more metal units to the mill. Gekko Systems has effectively utilized the Inline Pressure Jig (IPJ) to pre-concentrate the valuable metal, achieving high primary recoveries into a range of mass yields resulting in upgrade ratios between 2 and 10 times. This paper explores: the benefits of pre-concentrating ‘marginal’ ore deposits prior to the milling circuit; the selective rejection of ore types that may affect either the recovery or comminution process; and also looks into the potential to effectively reduce the ‘cut-off’ grade when considering the mine planning process. Case studies of projects using the IPJ to pre-concentrate and reject gangue are also included. Pre-concentration and gangue rejection provide the potential to develop marginal ore deposits, thus providing higher grades, less gangue and more metal at a lower operating cost to producers."

Jan 1, 2014

By Amir Hajizadeh Omran, Mehdi Irannajad, Sima Mohammadnejad, Fardis Nakhaei

"This study presents an experimental program performed to investigate the effects of flotation variables including gas flow rate, froth depth, slurry solids percent, frother/collector dosage and pH on the froth bubble size during desulfurization of an iron ore. These conditions were varied using a central composite design (CCD). Image analysis techniques have been developed and used successfully to characterize the froth bubble size. Results of the CCD experiments showed that the flotation variables have different effects on the froth bubble size. The froth height, air flowrate, pH and solid content had the most important influence on the froth bubble size. The interaction between the collector-frother, pH-collector, frother-air flowrate, solid content-froth height, pH-froth height and solid content-pH were also significant. Process state can be accurately deduced from the froth surface appearance, providing a convenient way to quantify the parameters as a function of the process control. INTRODUCTION Flotation processes are subjected to a wide variety of process disturbances, some of which are made by the change in mineral features and others to variation in operating procedures. Feed and air flow rates, densities, size distributions and shapes of particles, surface properties, and reagent dosages and compositions can all change, often with significant effect on the performance of the plant (Moolman et al., 1996a). Flotation process efficiency is governed by the wettability of the solid as well as the surface tension at the liquid-gas. Both of these properties are influenced by operational conditions encountering in a flotation process. The structure of froths developed on the pulp surfaces of flotation cells has a remarkable effect on both the grade and recovery of minerals in the concentrate (Shean and Cilliers, 2011)."

Jan 1, 2018

By L. K. Smith

Flotation work conducted by CSIRO on both single minerals and high-arsenic copper ores from a number of sources, has shown it is possible to produce separate low-arsenic copper concentrates and high-arsenic copper concentrates from high-arsenic copper ores. The procedure involves controlled separations at high or low pulp potential regions exploiting subtle differences in the flotation behavior of the arsenic-bearing and non-arsenic-bearing copper minerals. An overview of several case studies investigating the applicability of the controlled potential flotation approach to the separation of copper and arsenic from sulfide copper ores is presented. It highlights the variables which influence the efficiency of the separation which include mineralogy, liberation and reagent selection. The procedure can produce a saleable low-arsenic copper concentrate, which can be directly smelted without penalty, and a high-arsenic low copper concentrate, which will require further processing. Keywords: flotation, copper, arsenic, controlled-potential flotation

Sep 1, 2012

By S. H. Morar

Froth flotation is a physico-chemical separation process that takes place in two phases; pulp and froth phase. It is widely recognised as a complex process, due to the range of interactions present within the system. Of critical importance is the role of the froth phase within the system. The pulp kinetics governs the maximum potential recovery within a flotation cell, while the froth phase governs the selectivity via the froth?s stability. Higher froth stability improves recovery at the expense of grade, and lower froth stability improves selectivity. It is well known that the two major factors affecting froth stability are attached particles and solution chemistry. This paper looks at a flotation bank at different froth depth and frother concentrations. The air recovery to the concentrate is determined at each condition and relates the effect of the operating conditions on froth stability and transport to the amount of solids that are recovered to the froth and concentrate by true flotation. The results presented show that, for a given process objective, which in this case was a consistent mass pull profile, depending on the operating conditions, solids recovery in the pulp is affected by the air rate required to maintain the target mass pull. To a smaller extent, the changes in the pulp composition affect down-stream pulp recovery. The variation in solids recovered into the froth drives the froth stability at the start of the flotation bank, while the frother drives the froth stability at the end of the bank. The performance in between these two extreme conditions arises from an interaction of these two effects. The consequences of these interactions can give rise to counter-intuitive responses that can confound efforts to optimise the performance of the bank.

Jan 1, 2014

By Andrew T. McBride, Malcolm S. Powell, Indresan Govender

"Current empirical Semi Autogneous Grinding (SAG) mill models contain assumptions concerning the amount of energy available for particle breakage, how this energy is distributed in the mill media and the rate at which the energy is transferred. Despite these assumptions the JK SAG model is highly functional with a proven track record. DEM provides a numerical framework to greatly improve on these assumptions that were necessary due to a lack of available input data.This paper identifies key outputs of the Discrete Element Method (DEM), such as energy spectra and impact probability distribution. It describes how they can be incorporated into current mill models utilising practical rock breakage data. The rate at which energy is transferred is shown to be dependent on particle position and mill rotational speed and not once per cycle as previously assumed. Based upon this an improved energy transfer methodology is presented. The fundamental outputs of the DEM are validated against experimental three-dimensional particle tracking data, so as to establish whether the DEM produces correct energy transfer predictions on the inter-particle level, which is crucial to this work."

Jan 1, 2003

By V. G. Prikhodko, G. I. Sukhinin, I. V. Yarygin, A. V. Fedoseev, S. A. Novopashin

"The first experiments on the vacuum drying of spherical clay sample are presented and the theoretical model of the process is considered. The model is based on the solution of the heat and the moisture transfer equations with the effective thermal conductivity and water diffusion coefficients for wet porous clay-like medium. The time and radial dependence of the temperature and the moisture were calculated for different initial conditions. The results obtained for the time dependence of the moisture content are in good agreement with the experimental results obtained in the initial period, when all the moisture in the sample did not freeze to form an ice crust. INTRODUCTION Capillary-porous materials very often occur in nature and in industry. A porous medium is a solid matrix with voids, or pores, which are continuously connected. These pores are usually filled with fluids or moisture, water vapor and air that can pass through the medium because the voids are interconnected. The void fraction in the solid matrix is referred to as the porosity. Porosity or void fraction is a measure of the void (i.e. ""empty"") spaces in a material, and is a fraction of the volume of voids over the total volume. The moisture content in porous media determines the properties of the porous body, its mechanical and thermo-physical properties, such as density, plasticity, viscoelasticity, swelling, cracking, and so on. Complex processes of heat and mass transfer occur in porous bodies when they are heated or cooled, during drying or freezing (Luikov,1966). The course of these processes depends essentially on the physical-chemical composition of the solid matrix of the porous body, on its fractal dimension, porosity and morphology. The clay and clay minerals are the most important porous materials in the history of the mankind (Mukherjee, 2013). Clay is a very fine grained, unconsolidated rock matter, which is plastic when wet, but becomes hard and stony when heated. It has its origin in natural processes, mostly complex weathering, transported and deposited by sedimentation within geological periods. Clay is composed of silica {SiO2), Alumina (Al2O3) and water (H2O) plus appreciable concentrations of oxides of iron, alkali and alkaline earth, and contains groups of crystalline substances such as quartz, feldspar, and mica. Building materials, bricks, and tiles, pottery, porcelain and faience are made from clay. Clay is used in the food and medical industry, and, not least, in the mining industry as a carrier containing aluminum, silicon and other valuable elements, as well as metals (copper, gold) as constituents, contained in the pores in the form of micro- and nano-particles or grains."

Jan 1, 2018

By X. Y. Zeng

Most Chinese titanium bearing minerals are the composition of magnetite vanadium and ilmenite. All of such mineral processing plants use low intensity magnetic separators to recover magnetite and vanadium goes with magnetite. In the past years most of the plant tails containing about 10% TiO2 were abandoned. Now many of these plants use SLon magnetic separators to recover ilmenite in the roughing stage, which can throw away most of the gangs and slimes with very low cost. The new development of applications of SLon magnetic separators in Chinese ilmenite processing industry is introduced in the paper.

Jan 1, 2014

By P. Pourghahramani

Several structural characteristics change during intensive milling such as chemical composition, phase transformation, crystallite size, lattice strain, lattice parameter (s) and solid reactivity etc. The creation of defects enhances the stored energy (enthalpy) in the solids and consequently causes a decrease of activation barrier for the process and/or subsequent processes. In this paper, the effects of milling on the structural changes of hematite have been investigated using dry millings. The structural changes have been characterized using a combination analysis of BET surface area measurements and X-ray diffraction (XRD) analysis. Besides, the hydrogen reduction behaviors and kinetics of mechanically activated samples and initial sample were studied using simultaneous thermal analysis (STA). The methods of Williamson-Hall and Warren-Averbach were used for analyzing of XRD patterns to resolve and extract the microstructural characteristics of hematite phases. It was concluded that the breakage and aggregation of particles take place mainly in the starting and prolonged stages of dry grinding, respectively. The BET surface area enlarged steadily over the grinding processes whatever milling methods were utilized. The characterization of structural changes revealed that the hematite milled under various conditions did not undergo any significant reaction or phase transformation during milling processes. In addition, X-ray amorphous phase con-tent increased gradually with extending the grinding intensity. The maximum X-ray amorphous phase exceeds about 81% after 9 hours of milling in both tumbling mill and vibratory mill. The Williamson-Hall plots revealed the anisotropic character of line broadening for deformed hematite and changes in the trend of microstructural characteristics as a function of milling time. It was found that the surface weighted crystallite size decreases and lattice strain increases over the grinding periods. The minimum surface weighted crystallites were calculated about 17.3 nm, 12.2 nm for the products of tumbling and vibratory mills respectively. The maximum lattice strain,, in the grinding with tumbling and vibratory mills was calculated about 4.44×10-3 and 3.95×10-3respectively. 21/210nmLe=<> The non-isothermal kinetic analysis of the products revealed that Fe 2O3 reduced to Fe in a two-step process via Fe3O4. Intensive grinding resulted in improved resolution of overlapping reduction events. It was also established that the mechanical activation had a positive effect on the first step of reduction. The prereduction step in the activated samples initiated and completed at lower temperatures than that in non-activated samples. The activation energy of reduction decreased at the first step of reaction with increasing the grinding intensity. Intensive milling increased slightly the average activation energy of the second step of reduction due to the present of finely agglomerated particles and intensive sintering of the particles in higher temperature ranges.

Jan 1, 2014

By J. A. Sweet

The issues facing graduate training in the mineral processing industry are not too different today from those that prompted the initiation of the Anglo American Platinum Graduate Development Programme (AGDP) in 2002. Graduate metallurgists in South Africa enter the industry from different undergraduate programmes at various tertiary institutions, and so the knowledge and skills of the young graduates varies. Further, the geographical expansion of the industry combined with the downsizing of business units means that there are fewer opportunities for young graduates to be mentored through their first few years on site. Anglo American Platinum chose to address these issues by implementing an intensive, structured graduate training programme for all their new metallurgical graduates, known as the AGDP. The first two years of experience of the AGDP, from the viewpoints of both graduates and lecturers, were presented to the mineral processing community at the IMPC in Turkey in 2006 (Sweet et al, 2006). From the beginning, the programme was structured in a modular fashion to include a basic technical ?toolbox? including statistics, the scientific method and sampling protocols, while the mineral processing content comprised advanced learning in comminution, classification and flotation (later extended to include hydrometallurgy). Technical communication ? both written and verbal ? was included from the start. The programme was focussed very strongly on site work (?learning by doing?), with a major integrated site campaign conducted and analysed by each cohort. In 2012 the AGDP will accept its ninth cohort into the programme. This paper describes how Anglo American Platinum and the University of Cape Town have developed and adapted the programme over the last few years, in response to the challenges of the global recession, skills retention, and the changing operational needs of the company. The programme, which was drawn up to accommodate around 15 concentrator-only graduates, now accommodates 35-40 concentrator, smelter and refinery graduates annually. The programme has also been modified to facilitate new graduates spending most of their first year on the operations. The benefits of the programme for Anglo American Platinum have been tangible, and will be discussed in the paper. Keywords: graduate training, technology transfer

Sep 1, 2012

"This research represents a shift away from empirical models that lock the industry into 50-year old inefficiencies with little response to operating variability. The mechanistic and intrinsically dynamic mill model under development steps up to a new paradigm using the latest computing capabilities and physical understanding of breakage and transport to transform predictive capabilities for design, optimisation and on-line control with variable feed. The milling process is broken down into discrete sub-processes, each of which can be modelled as an object in the whole model and in the model code. These objects can be upgraded or exchanged without having to rewrite or restructure the remainder of the code. Sub-processes include: feed into mill; transport along mill; presentation to impacting events; range of impacting forces; probability of being impacted in different zones in the mill as a function of particle size and density; suspension in slurry; and discharge out of the mill. The unit and processes surrounding the mill (feed and recycle conveyors, slurry pump and pipe, cyclone and recycle crusher) have also been modelled, in order to incorporate the effect of recirculating load coming from a cyclone or a recycle pebble crusher, respectively for ball mills or SAG mills. Each unit is modelled dynamically and PID controllers have been added to control pumping flowrate from sump and water addition for cyclone feed dilution. The paper demonstrates the predictive capability of a dynamic, mechanistic model and is used to test the sensitivity to the sub-processes, comparing different formulations and highlighting the aspects that require further development. Validation on pilot tests and application to industrial data is presented. This approach is currently undergoing industrial trial on sites, for use in on-line model-informed process control. Considerable further development is required to incorporate the full mechanistic structure planned for this model."

Jan 1, 2018

By Leon Lorenzen, Victor E. Ross, Anton W. Kleingeld

Key to successful innovation, whether at organization, industry or national level, is the alignment and utilization of resources in the most appropriate and efficient way. Innovation needs to be directed strategically, and it needs to be auditable in a systematic and integrated fashion. In the light of these considerations, this paper describes the construction and use of a topographical map of the innovation landscape. The purpose of the map is to provide a holistic view of the key factors that enable innovation (the so-called ’landmarks’), how well they are aligned to support a particular type/nature of innovation in the organization, and to identify possible gaps. The significance (importance) and height (performance) of the landmarks in supporting and enabling innovation within the organization is determined by means of a selfappraisal audit. The topography of the landscape derived thus is subsequently interpreted in terms of the organization’s particular innovation strategy and environmental context. The application of the Innovation Landscape Methodology is illustrated in a number of organizations within the Mining and Minerals Industry of South Africa. Important observations and conclusions regarding the strategic alignment of enabler strengths within these organizations are made.

Jan 1, 2003

Micro-fine disseminated molybdenite was ground in a laboratory stirred mill using steel media and zirconium media respectively. The floatability of ground molybdenite and slurry chemistry was investigated. It was found that the total recovery of ground molybdenite using zirconium media was higher while the pH and Eh of the slurry are lower than that using steel media. When steel media was used, iron oxy-hydroxides had been generated coated on the surface of molybdenite, and decreased the floatability of molybdenite, especially of the -10µm particles. The iron and lead oxy-hydroxides was generated by the reaction between steel media with pyrite and galena associated with molybdenite. It was also found that changing the grinding media to inert can benefit the flotation of molybdenite. Keywords: stirred mill, grinding environment, floatability, micro-fine disseminated molybdenite, fine grinding

Sep 1, 2012

By Z. L. Huang

A new porous apatite product was prepared using phosphorite from Yichang China by a tem-plate-directed method in self-made reaction equipment under constant temperature and pressure. The product was characterized by XRD, FT-IR and SEM. The results showed that the product was a kind of micrometer porous sphere three-dimensionally structured by apatite nanoflakes, that the average thickness of nanoflakes was about 50 nm, that the average pore size was about 1.2 µm and that the particle average size was about 20 µm. Great amounts of Ca2+channel, high special surface area and regular spherical shape show the potential promising applications of this special porous apatite product in the fields of catalyst, medication, chemical engineering and environment engineering

Jan 1, 2014

By Yong Liu, Peng Qian, Shu-Feng Ye, Shao-Jun Chu, Pei-Wei Han

"Chromite with a low mass ratio of Cr to Fe (Cr/Fe ratio) was treated by the carbochlorination method using solid chlorinating agent (MgCl2 and CaCl2) and carbon in the present paper. The results showed that iron could be selective removed mainly in the form of FeCl2. The removal of iron was indirectly, which consisted of the decomposition of solid chlorinating agent to release Cl2/HCl and the carbochlorination of FeO•Cr2O3 by Cl2/HCl and C. The Cr/Fe ratio increased as increasing temperature from 700 ? to 900 ? in air atmosphere, while the tendency was opposite in N2 atmosphere. The removal efficiency of iron by CaCl2 was better than that by MgCl2. At last, a new pelletizing process was proposed to treat fine chromite with a low Cr/Fe ratio based on carbochlorination method, which could produce the high quality roasted chromite pellets with higher Cr/Fe ratio and compressive strength. INTRODUCTION Chromite is mainly used for the production of ferrochromium. A high Cr/Fe ratio (>2) of chromite is usually required to meet the technical specification of ferrochromium.(Gasik, 2013) Attentions have been attracted to the economic and efficient methods for the recovery of chromium from lower-grade ores as the higher-grade ores become depleted. However, the Cr/Fe ratio is difficult to improve through the conventional beneficiation methods (such as gravity concentration, flotation) due to the spinel composition, although beneficiation methods could increase the metal content of chromite ores by removing gangues.(Nafziger, 1982) The main industrial mineral of chromite is (Fe,Mg)O•(Cr,Al,Fe)2O3, which belongs to spinel magnetite.(Liu, 2013) Iron should be selectively removed through the structural dissociation of spinel to increase Cr/Fe ratio.(Nafziger, 1982)"

Jan 1, 2018

By V. Yu. Ivanov, A. I. Yuryev, L. S. Lesnikova, M. S. Datsiev

"The Talnakh Concentrator was put into operation in 1981 using a direct selective process to produce copper, nickel and pyrrhotite concentrates.In 2001, a novel selective-bulk-selective (SBS) technology for the concentration of massive sulfide ore was implemented, that allowed to increase the valuable components recovery into target concentrates with feedstock grinding coarser than before. In 2003-2005, the process upgrading included the differentiated processing of nickelpyrrhotite products recovered at the different concentration stages and made it possible to significantly enhance the contrast of the pentlandite and pyrrhotite flotation properties and to simultaneously increase separation of polymineral intergrowths.The next stage of the PD concentration complex development is the Project ""Talnakh Concentrator Reconstruction and Technical Upgrading"" to raise its capacity by half. The project has three Phases.• Phase 1. Pilot startup was carried out in January 2015 following the installation of new OK-100 TC flotation machines, manufactured by Outotec.• Phase 2. The introduction of a new technology developed by the Polar Division specialists launched in mid-2016. The new technology is based on maximization of iron and sulfur removal into tailings and maintenance of non-ferrous and precious metals losses at the same level.After the realization of Phase 3, the annual capacity of the Talnakh Concentrator will raise by another ~ 40% at the expense of processing cuprous and disseminated ores currently being processed by the Norilsk Concentrator.By 2023, due to upgrading of the PD production facilities the emissions to the atmosphere will reduce by 75%.Polar Division of PJSC MMC Norilsk Nickel (PD) searches for the ways to solve its environmental issues. Thus, in 2016, the Nickel Plant was shutdown and a new flowsheet was introduced at Talnakh Concentrator. It resulted in the reduction of sulfur specific amount sent to pyrometallurgical processing as a component of the concentrates.The Talnakh Concentrator was put into operation in 1981 using a direct selective process to produce copper, nickel and pyrrhotite concentrates.In 1981, its design capacity for processing of Cu-Ni ores from Oktyabrsky and Taimyrsky Mines did not exceed 3 million tons per year.In 2001, a novel selective-bulk-selective (SBS) technology for the concentration of massive sulfide ore was implemented at the Talnakh Concentrator, that allowed to increase the valuable components recovery into target concentrates with feedstock grinding coarser than before."

Jan 1, 2018

By Sunil Tripathy, Y. Rama, Srinivasulu. A., Amit Ranjan

Process improvements in an operating plant are always challenging. Mineral beneficiation plants based on gravity concentration techniques need continuous evaluation and monitoring of its processes for getting maximum recovery and better grades. But, in an operating plant it is very difficult to control all the parameters due to numerous reasons such as unsteady operation, fluctuation in the quality of run-off-mine ore, overall flow rate etc. For better understanding of the beneficiation circuit, it is necessary to evaluate the critical operating parameters which affect the performance in terms of grade, recovery and throughput including losses of valuable materials into tailing. Accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play very critical role in performance of the circuit. In case of gravity operated beneficiation circuits of chrome ores where the quality of the feed and physical parameters varies continuously, the operators are required to modify the critical operating process parameters on continuous basis which is very difficult and tiresome. There are many causes of the data variability, including both error (sampling and assay), and real variation in performance due to changes in ore mineralogy, operating conditions and other factors. In this article, attempts made to evaluate the performance of ultra-fine beneficiation circuit in terms of silica reduction in the concentrate of chrome ore beneficiation plant (COB), India are discussed. The approach adopted and practical problems encountered during the study were also discussed. Results obtained from plant audit based on the above methodology has shown that SiO2 content in the concentrate can be reduced to <4%.

Jan 1, 2014

By J. Y. P. Leite

In the Borborema Pegmatitic Province (Brazil) exploitations of several minerals are conducted by small producers. They use traditional techniques of gravity concentration in small-scale plants as jigs and vibratory tables. During decades the mining activity generated tailings with economic interest in particularly columbite-tantalite. Samples collected in tailing piles of a gravity plant were characterized in mineral composition, which shows in the heavy fraction the minerals spodumene, columbite-tantalite, ilmeno-hematite, garnet and cassiterite. The light fraction presents quartz, feldspar and muscovite. The degree of liberation of spodumene and columbite-tantalite were determined using optical microscopy that presents liberation in 100 µm (90% to columbite-tantalite and 100% to spodumene). Centrifugal concentrator Falcon SB-40 was used for concentration of these minerals and presents 65% recovery in mass to two stages with mass reduction about 85%.

Sep 1, 2012

By W. G. Wu

More and more researches and applications of organic chelating agents as depressors or activators are carried out in the course of research and application of modern flotation. The paper puts forward the necessary condition of organic chelating agents as depressors or activators by analyzing the chelating chemical performance of organic chelating agents with metal ions and the stability of chelates formed by them; at the same time, puts forward four sufficient conditions of organic chelating agents as depressors or activators according to different hydrophilic capability of the chelates and different performance of depression and activation of organic chelating agents for minerals. Namely, the ?1+1/4? necessary and sufficient conditions of organic chelating agents as depressors or activators are put forward.

Jan 1, 2014