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By Chao Li, Kym Runge, Saeed Farrokhpay, Dee Bradshaw

"It is well known that froth phase has a controlling influence on the overall flotation performance. Froth recovery is expected to be affected by froth transportation behaviour. The latter has been represented by different volume balance and energy balance based models. In froth transportation models based on a volume balance, the froth phase is divided into different zones. The total froth residence time is the sum of the time spent in each zone and is dependent on the cell geometry, bubble burst rate and the position that bubbles enter into the froth phase. Alternatively, the froth transportation model based on an energy balance treats the froth phase as a block. In this model, froth height above the concentrate lip is being predicted by minimising the energy of the system which is dependent on the froth geometry, froth stability and froth rheology. The froth height can be used to calculate the froth efficiency of delivering mineralized bubbles from the pulp to the concentrate lip. This paper critically analyses the current models of froth transportation in flotation, and examines the limitations of these models. The importance of froth rheology, which is the resistance to the froth flow towards the discharging weir, in determining froth transportation, is also highlighted."

Jan 1, 2014

By C. A. C. Sequeira, G. N. Anastassakis

"The separation of fine or even smaller size mineral particles with conventional methods is inefficient due to the specific properties of fines (small mass, high specific surface area, and high surface energy per unit area). Hence, the production of high-grade concentrate with high recovery is very difficult to impossible and a significant share of mineral values is lost to the tailings. The aim of the current research is to investigate the possibility to efficiently separate value minerals from gangue of fine particle size. The objective of the current work is to develop separation schemes of fine mineral particles by combining an initial stage of particles agglomeration with the use of collectors (hydrophobic agglomeration) with a subsequent conventional separation method. In the current research, magnesite was used as mineral value to be separated: a) from quartz, and b) from mineral mixture (serpentine, ilmenite, and olivine). In each case, tests on single minerals and artificial mixtures were carried out. After hydrophobic agglomeration, the separation of magnesite from quartz was achieved by settling; in the second case (gangue: serpentine, ilmenite, and olivine), magnetic separation of the co-agglomerated gangue was applied. In both cases, the results of the preliminary tests on single minerals suggest that the separation of mineral value is feasible and efficient. These findings were also confirmed from the results of the tests on artificial mixtures of magnesite and gangue, either quartz only or mineral mixture. Both separation schemes provided with magnesite concentrates of commercial grade (95% magnesite) with high recovery. INTRODUCTION The generation of fine particles is inevitable in many operations of mineral commodities processing. Especially in the case of low-grade ores, the mineral value is finely disseminated in the ore, and considerable liberation occurs at a fine size range. Although there is not a uniform classification system with respect to mineral particles size, fines are usually characterized the particles with a size range of -100µm+20µm, very fines those of -20µm+5µm, ultra fines of -5µm+1µm, and colloids smaller than 1µm (Sivamohan, 1990)."

Jan 1, 2018

By Brian Lindner, Lidia Auret, Niel Knoblauch

In this paper, a fault detection and identification framework based on feature extraction and topology extraction methods is proposed, and evaluated on a simulated base metals refinery high pressure leaching process. Feature extraction methods included linear and kernel principal component analysis, while process topology information was extracted with linear cross-correlation, partial cross-correlation and transfer entropy. Connectivity maps were constructed to identify possible fault propagation paths to aid root cause analysis. The results indicate that process topology can enhance the fault identification capability of data-based process monitoring methods. The study of the considered base metals refinery pressure leaching process is ongoing, with future work including the creation of a fault library which would lead to further critical evaluation of the proposed fault detection and identification framework.

Jan 1, 2014

By Venkataramana Runkana, Shantanu Maheshwari

As the world reserves of high quality ores are getting depleted at a rate higher than ever, the liberation of valuable minerals from low grade ores is becoming more and more relevant and imperative. But, liberation of minerals from low grade ores requires grinding of ore to extremely fine sizes. High energy milling in a planetary ball mill is one such option where one can produce particles in the nano-meter range. Although planetary mill is employed extensively for ultrafine grinding, dynamics of grinding inside the mill is not fully understood because of the dependency of grinding kinetics on many interconnected phenomena like collisions between media, particles and wall, time dependent rheology, adsorption and desorption of dispersant, abrasion of media, agglomeration of particles, etc. It was well articulated in literature that media motion and number of media collisions have strong effect on grinding kinetics and final product size distribution. Simulations were carried out using the discrete element method (DEM) to compare the performance of a planetary mill with a ball mill, with and without lifters, in terms of impact energy and number of collisions and it was found that number of collisions is considerably high in the planetary mill. The high number of collisions might be the reason for production of ultrafine particles in the planetary mill. We have also fitted a population balance model (PBM) to experimental data from a laboratory scale planetary mill for prediction of particle size distribution. Unlike previous models, we have incorporated functional forms for the selection function and the breakage distribution function so that the number of parameters in the PBM is just five. The predicted product particle size distributions at different grinding times are in reasonably good agreement with experimental data.

Jan 1, 2014

By M. Canbazoglu

In this study, optimum sulphuric acid leaching parameters of zinc and other valuable metals from two different waelz clinker samples were researched. Origins of the samples are electric arc furnace dust and original non-sulphite zinc ore waelz clinkers. The main zinc mineral determined as zincite in these samples. Collective dissolution of zinc and other valuable metals in waelz clinkers can easily achieved by sulphuric acid leaching of them. 96% of zinc can be dissolved at 80 ºC, 60 g/L sulphuric acid concentration, 60 min. leaching time and 1/5 solid/liquid ratio. Almost 90% of Cd, Cu and Co in clinker dissolved at these conditions while dissolution of Fe was almost 20%. The consumed acid amount for dissolved per ton of zinc is approximately 1.7 tons at these conditions.

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

The reactivity of clay minerals and variety of these reactions are greater than any other known colloidal material. While it is acknowledged that clay minerals can cause problems in mineral flotation, the literature contains conflicting evidence, particularly with respect to the effect of clays on froth stability. It is well known that achieving and maintaining optimum froth stability is an influential factor in determining froth flotation performance. However, the presence of clay minerals in the ore is a major challenge to obtaining a stable froth. In fact, clay minerals could reduce froth flotation performance by both decreasing and increasing froth stability. The mechanism by which clay minerals affect froth stability is not fully understood and needs to be investigated further. In order to improve flotation performance, reliable knowledge of the effect of clay minerals on froth stability is essential which is discussed in this paper. Keywords: froth flotation, froth stability, clay, clay minerals

Sep 1, 2012

By Alban Lynch, Benigno Aquino, Hakan Dündar, Alexander Kalugin, Marco Delgado, Alberto Palomino, Ali Türkistanli

Dynamic separators are efficient dry classifiers because new designs during the last 50 years have reduced the by-pass and improved the partition curve. By contrast cyclones have been used as classifiers in wet grinding circuits for 50 years but without serious change and the early problems which were caused by high and variable by-pass, and different mineral specific gravities, still exist. High frequency screens are now used for wet separation and the operating characteristics of closed grinding circuits using cyclones or screens are discussed. Data come from circuits at the Condestable, Cerro Lindo, El Brocal and Catalina Huanca mines in Peru, the Eczacibasi mine in Turkey, and the Apatit mine in central Kola Peninsula in Russia. All classifier data are described by their partition curves and all mill data by their breakage rates. With cyclones the by-pass, d50, and sharpness of the partition curve change as operating conditions change but with high frequency screens the values vary little because the by-pass is low, the sharpness is high, and d50 depends on the aperture size. Data from all plants indicate that lower by-pass and sharper separation improve breakage rates and throughputs. An initial model of the screen is proposed.

Jan 1, 2014

By R. C. Miranda

Artificial vision systems are increasingly used to assist humans to perform different tasks in different areas. These systems are able to recognize patterns in complex images, which can provide multiple data. Currently, vision systems are used in both; monitoring traffic - which uses radars for vehicular plate recognition- as in metallurgical and food industries for strict quality inspections. Their use in mining occurs in measuring the speed of froth over the lip of a cell, in determining the shape and size of pellets, in obtaining from the tendency of mineral content and as a replacement for laboratory analysis of particle size. With this advanced tool, it is possible to achieve significant improvements in quality, productivity, and especially in reducing costs in pelletizing plant of iron ore. The objective of this paper is to contemplate the current situation of image analysis in the pelleting plants and glimpse at the potential applications that are being developed. This paper also presents the conception and implementation of an automatic control system of the pellets size distribution applied on a pelletizing plant of iron ore. The article demonstrates the strategy used for measuring the size distribution of the iron ore pellets, based on image analysis and the strategy implemented on advanced process control, which shows substantial gain on plant performance.

Sep 1, 2012

By Leming Ou, Qiming Feng, Yiping Lu, Pengyu Zhang, Qing Shi, Kun Liu, Guofan Zhang

"This paper introduces the mineralogical analysis of certain polymetallic copper-zinc ore in China with the aim of improving the flotation process. The main valuable elements, mineral phases and compositions of run-of-mine ore were inspected by the X-ray Fluorescence (XRF) and chemical analysis. For a deep known of the old process defects, Mineral Liberation Analysis system (MLAs) was employed to investigate the minerals liberation degree of selected key slurry points. Analysis results show that the run-of-mine ore belongs to the original copper-zinc polymetallic symbiotic ore at low oxidative level, which mainly contains 0.16% Cu, 4.43% Zn and 0.88% Sn. Gangue minerals are mainly silicate minerals, and zinc mineral is sphalerite. MLAs test illustrates that about 86% sphalerite has been dissociated in zinc flotation feed. In the current flotation process, over grinding of sphalerite monomer and insufficient liberation of intergrowths are the key problems need to be solved imminently. Up to this point, a new process consisted of two steps roughing unit is submitted in this research. It contributes two positive effects on zinc flotation performance: (i) separating sphalerite monomer timely to decrease overgrinding; (ii) improving zinc minerals intergrowths liberation efficiency. Flotation results indicate that the zinc concentrate grade increased 0.90% and the recovery improved 0.96% in the new flotation processINTRODUCTION Mineralogical analysis mainly focusses on solving mineralogy problems in minerals processing, assisting in minerals behaviors prediction and control for separation engineering (Falkovich, et al., 2001; Hillier, et al., 2003; Schouwstra and Smit, 2011). Process defects searching becomes its ordinary work, and flotation optimization appears to be its targets gradually. For example, Lucky Friday mine company (Idaho America) fails to obtain qualified lead concentrate as the change of ore properties (Nadoll, et al., 2011). Mineralogical analysis ascertains that there are too many dissociated sphalerite, pyrite and gangue particles exist in lead concentrate. According to this, more cleaning units are added to solve problems effectively. Kanowna Belle mine (Australia) takes a flash circuit in operation successfully with the aim of optimize flotation process, under the helps of mineralogical analysis and industrial test (Newcombe, et al., 2013). Lotter N.O. (2011) gives a deep description on how mineralogical data assisting mineral processing engineers to design and optimize flowsheet. For decades, quantitative and automated mineralogy techniques (Andersen, et al., 2009; Gu, et al., 2012; Oghazi, et al., 2009; Yu, et al., 2007) get well developed and hugely improve the veracity and repeatability of minerals properties measurement. Among these, MLAs (Gu, 2003) provided by JKMRC (Julius Kruttschnitt Mineral Research Center) is critically acclaimed all over the world. This analysis system can measure mineral phases composition and content, particles size, minerals occurrence and liberation degree directly."

Jan 1, 2018

By S. Gaydardzhiev

Laboratory batch tests having preliminary and orientation character aiming at improvement of the molybdenum flotation at Ellatzite copper processing plant in Bulgaria have been conducted. The following technological parameters have been screened to study their influence on the grade and recovery of copper and molybdenum during the rougher flotation stage: flotation pulp density, pH, addition of secondary collector and replacement of MIBC by pine oil as a frother. The results have shown that slightly better grade/recovery figures could be obtained for both copper and molybdenum at lower flotation pulp densities. The addition of kerosene has improved the recovery of molybdenum however, on the expense of that of copper. The effects from pH variation and the replacement of MIBC by pine oil as a frother have been almost negligible.

Sep 1, 2012

By M. Saghaeian, R. Hejazi, H. Abedini, M. Zare

Water recovery in mineral processing plants is one of the most important subjects because water supply is a critical matter economically and environmentally, especially in desert areas. In this paper, the filtration behaviour of two iron ore tailing sample has been investigated using laboratory scale vacuum and pressure filtration units. These samples including tailing from Sirjan and Zarand concentrate production plants with the d80 of 94 and 41 micron, respectively. The results show that by using vacuum filtration the cake moisture content of Sirjan sample would be about 24%. But the filtration time is too long and vacuum belt filter cannot be used in industrial scale. Adding about 40 g/ton of flocculant would decrease the filtration time by about 30% and make the vacuum belt filter appropriate for dewatering of this sample. For Zarand tailing sample, the vacuum filtration would produce a wet cake by about 31% moisture content. Filtration time is too long and adding flocculant would not improve the results very much. So pressure filtration must be used for dewatering of this sample. The results of laboratory tests show that using pressure filter would reduce the cake moisture content to 21%. The filtration time is logical, so this process can be used for Zarand tailing dewatering.

Jan 1, 2014

By Silvia Serranti, Giuseppe Bonifazi, Roberta Palmieri

The possibility to develop an efficient recovery and reuse of concrete materials from Demolition Waste (DW) represents one of the main targets applied to end-of-life constructions dismantling/recycling. The need to recycle end-of life concrete materials is strongly increasing in these last years for several reasons: i) the decrease of steady supplies of good quality natural aggregates, ii) the need to secure ample supplies of concrete aggregates to the construction industry and, finally, iii) the environmental constraints limiting the DW wastes disposal. The fulfilment of these goals produces several benefits, that is: i) a reduction of new resources consumption, ii) a strong reduction of the costs linked to transport and energy production, iii) the possibility to utilize materials, otherwise lost (e.g. land filled), iv) land preservation and, finally, v) the reduction of the environmental impact of new exploitation activities. A lot of efforts have been addressed to develop, set-up and apply innovative technologies to maximize DW conversion into useful secondary raw materials. The possibility to utilize efficient, reliable and low cost analytical tools to perform detection/control actions: i) to assess concrete characteristics, before demolition, and ii) to detect the presence of contaminants in coarse aggregates (e.g. bricks, gypsum, steel, glass, plastics, wood, etc.) represent the key issues to fulfil in order to develop innovative process/control actions/procedures inside the DW sector. In this paper a new technology, based on HyperSpectral Imaging (HSI) sensors is investigated to develop suitable and low cost strategies finalised to define and implement innovative smart detection engines for sorting and/or DW flow stream quality control, addressed to perform recovered materials and/or products certification. The proposed sensing architecture is fast, accurate, affordable and it can strongly contribute to bring down the economic threshold above which recycling is cost efficient.

Jan 1, 2014

By Osvaldo A. Bascur, J. Pat Kennedy

"The profitability of mining and metallurgical operations continues to lag behind that of other industries despite the technical advances that have occurred in recent years. A primary reason for poor performing in this economic sector is the lack of integration of mining and metallurgical information. The mine cut-off grade can be optimized if mining and metallurgical engineers have the data to optimize milling for the type of ore in hand.Integration of mine transactions, stockpile inventories, process flows and assays is the key to determining the economics for each blast strategy in a mining site. Real-time information from manufacturing assets greatly affects the profitability and flexibility of a company, but gross errors from faulty sensors, inaccurate instrument calibration, or incorrect process models may corrupt actionable information. New software tools can model the process, sift through available data to identify and eliminate gross errors, and use statistical data reconciliation to create materially balanced and consistent readings. The reconciled data is unified for use by both monitoring and decision making processes.Creating a real-time information environment where upgrade and change are allowed is becoming an accepted methodology to accelerate and simplify the integration of applications such as production monitoring, equipment performance management and yield and inventory management.This paper describes the data integration requirements in a mine, concentrator and port for unification of the redundant data. The capture of the mining events, stock pile management and the metallurgical information is the base requirements for a dynamic environment to reduce the overwhelming amount of information to unified set of information. Part of any decision support program should entail these results to continuously improve the measurement system to address the costs in mine and milling the ore."

Jan 1, 2003

By D. Steele, B. Ndlovu

"Adequate characterisation of clays is becoming increasingly important as operating mines move into areas of more complex ores. The processing therefore needs better mineralogical characterisation to identify problematic ores for better planning before issues arise. While a number of instrumental mineral characterisation methods are available, X-ray Diffraction (XRD) is widely recognised as perhaps the best technique for the identification and quantification of minerals, particularly clays. When an appropriate sequential and systematic sample preparation and treatment protocol is employed with instrumental XRD analysis individual clays can be uniquely identified, and the proportions of interstratified clays can also be quantified. The effect of sample preparation on the XRD analysis and identification of clays was investigated in this study. The results showed that sample preparation protocol is indeed critical to accurately analysis and characterisation of clays. For example, both dry grinding and micronizing affected the degree of crystallinity of kaolinite leading to the formation of reactive surfaces or changes in the physicochemical behavior. It was also found that the apparent degree of preferred orientation in platy minerals correlates directly with the amount of force/pressure applied during the preparation of backfilled powder samples. This work showed that manual preparation can produce highly variable peak intensities especially with minerals that show any preferred orientation. KEYWORDS Clay; XRD; kaolinite INTRODUCTION Clays are important in our life and they have numerous applications in modern world from cosmetics to environmental remediation. Therefore, clays have been extensively investigated for many years. Adequate characterisation of clays is becoming increasingly important as the mineral processing industry faces more complex mineralogy with the need for better mineralogical characterisation to identify problematic ores and plan accordingly. In most studies, X-ray diffraction (XRD) method has shown the unique capability to characterise mineralogy, especially for the fine grained size materials. The XRD technique is particularly diagnostic for clays. It is known that under ideal conditions, the peak intensities of an XRD diffractogram are proportional to the concentrations of individual minerals present in the sample. Hence, the qualitative mineralogical data obtained from XRD can be quantified, using either the internal or external standard methods. However, it is also known that clays are particularly sensitive to the influences of sample preparation method due to their physical characteristics (e.g. fine grain size, morphology, relative physical softness, crystallinity, thermal sensitivity) that could be destroyed by inappropriate preparation prior to the analysis. Thermal and mechanical treatment and grinding of clays can change their crystalline structure, and consequently, their characterisation results by XRD analysis. The behaviour of clays in grinding has been widely studied, especially for kaolinite (Miller and Oulton, 1970, Milocevic et al., 1992, Tomasevic-Canovic et al., 1992). With prolonged grinding time, the crystallinity of the clays can decrease (Filipovic-Petrovic et al., 2002). It has been shown that grinding may gradually cause the loss of hydroxyl ions of kaolinite (Gonzalez Garcia et al., 1991)."

Jan 1, 2018

By John Ralston

"Interfacial chemistry plays a pivotal role in bubble-particle capture, for it controls whether or not attachment occurs. Surface heterogeneity, degree of surface hydrophobicity, bubble nucleation and related phenomena influence the stability of the aqueous wetting film between a particle and an approaching bubble. The latter must be unstable if capture is to occur. Various techniques that may be used to quantify this interfacial, chemistry-dominated behaviour, are described.The efficient capture of specific particles by rising bubbles and the delicate control of interfacial chemistry that leads to selective capture are central issues in froth flotation. For efficient capture to occur between a particle and a bubble, they must undergo a close encounter, a collision process dominated by hydrodynamics. Should this encounter bring the particle and bubble within the range of attractive forces, the intervening liquid film between the bubble and the particle will drain, leading to a critical thickness at which rupture occurs. The liquid-vapour interface then retreats over the solid particle surface until a stable wetting perimeter is established. The particle and bubble are then joined after this attachment process. The particle may only be dislodged from this state if it is supplied with sufficient kinetic energy to exceed the detachment energy in this detachment process. These various events are now well documented and may be followed using high-speed videomicroscopy (Schulze, 1984; Nguyen et al., 2001).The process of collision can now be described quantitatively for single bubbles colliding with bubbles under various flow regimes (Dai et al., 1998) and appropriate scale up is possible for multiple bubble particle collisions occurring under turbulent conditions (Pyke et al., 2002). In this paper we will be concerned with the role of interfacial chemistry and how this influences the attachment process."

Jan 1, 2003

Mineral flotation is effective over a relatively narrow particle size range of approximately 10 µm to 150 µm. If the upper particle size limit can be increased, however, a run-of-mine ore may be coarse ground, and only the middlings are ground further to achieve required grades. This will result in significant energy savings and increased throughput. In this communication, methods of increasing the upper particle size limit will be discussed on the basis of a flotation model that can predict flotation from both hydrodynamic and surface chemical parameters. An example of increasing flotation recovery by control of a chemistry parameter is given.

Jan 1, 2014

By Heinrich Hutchison, Thomas von Moltke, Roelof F. Sandenbergh, Katarina P. Cerovic

In the leaching of gold in aqueous cyanide solutions the rate of gold leaching may be decreased by the passivation of the gold, that may however be prevented or reversed in the presence of lead species in solution. In the present study potentiostatic, potentiodyanamic and XPS (X-ray photoelectron spectroscopy) analysis were used to further clarify the action of lead ions on the anodic activity of gold in alkaline cyanide solutions. It was found that lead increased the gold dissolution rate as it deposited on the gold surface at potentials more positive than its reversible Nernst potential for bulk metal deposition, i.e. by underpotential deposition mechanism, but that it decreased gold activity if present as bulk plated lead on the gold.

Jan 1, 2003

By Y. G. Seredkin, A. A. Vasiliev, A. Y. Senchenko, A. V. Aksenov

"The valuable materials resulting from the processing of gold-bearing ores are often refractory to direct gold recovery through cyanidation. There are multiple methods for chemical liberation of gold prior to cyanidation such as pressure and biological oxidation as well as atmospheric oxidation which is typically used in combination with physical activation of material by ultrafine grinding such as the Albion ProcessTM. This paper will examine the data from process testworks carried out to estimate the efficiency of the Albion Process™ for the oxidation of materials with a wide composition range prior to cyanidation. The data will be compared to that obtained by direct cyanidation of the feed (without oxidation) and from the testing of pressure oxidation on the feed prior to cyanidation. Albion Process™ tests were conducted in Institute TOMS with participation of Glencore Technology Pty Ltd (Australia). Refractory concentrates obtained from the ores of several Russian and CIS deposits were used as feed for the testing. These concentrates were also subjected to a material composition study and testing using conventional recovery methods. The resulted test data make it possible to perform an integrated assessment of process properties for materials with different compositions, compare performance of various process flowsheets for the materials under study, and conclude on efficiency of Albion Process™ application for gold recovery from refractory materials different in their composition.INTRODUCTION It is often the case that gold ore concentrates are refractory to gold recovery by direct cyanidation. This refractory nature is as a rule attributable to fine gold dissemination in minerals, most often in pyrite and other sulphides, as well as to the increased amount of components impeding cyanide leaching of gold due to cyanide consumption and reducing process conditions. The refractoriness of the concentrates results in low gold recovery values when conventional cyanidation technology is used. In this context, various additional processes are applied to breakdown such refractory sulphide concentrates, i.e. mechanical breakdown (fine and ultrafine grinding), chemical breakdown (atmospheric oxidation, e.g. Leachox, acid-oxygen oxidation, pressure oxidation – POX, bacterial oxidation – BIOX), and thermochemical breakdown (various roasting methods). Such breakdown processes allow for increase in recovery of finely disseminated gold during the downstream cyanidation, however, their application is cost-intensive and does not always ensure economic benefit."

Jan 1, 2018

By Knut L. Sandvik, Erik Larsen

Crystalline silicon solar cells are the most important solar cells manufactured today. This will most probably remain the situation the next decade. The future silicon feedstock is most likely not reject from the production of electronic-grade silicon. There will probably be a more direct solar-grade silicon route, excluding the electronic-grade silicon "detour". Estimated global solar energy demand in 2001 required approximately 5,500 tons of silicon feedstock. This required 65,000 tons of quartz. If the trend continues, the solar energy demand in 2010 would require approximately 30,000 tons of silicon feedstock and 350,000 tons of quartz, although the need for quartz probably will be lower than this. Quartzite has been regarded as the most suitable primary raw material used in the silicon solar cell production chain. This may change as the raw material requirements for the production of metallurgical-grade silicon are most likely to change. In addition, quartz or other silica-containing minerals from other rocks may be of a higher purity or contain lesser amounts of the most harmful elements. This favours increased beneficiation of primary raw materials in the future solar silicon feedstock production chain.

Jan 1, 2003