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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

By John A. Rumball, Martin R. Houchin

Data from autogenous and semi-autogenous tests in a 1.67m diameter mill have been analysed in terms of a new model for rock abrasion. This model defines specific rate as the rate of production of fines (material less than 13mm) per unit mass of rock, where the term “rock” is applied to all ore pieces of ore coarser than the grate size. In most cases, an allowance for preliminary rounding and cleavage was made. A method has been developed to analyse steady-state data, using piecewise fitting to the cumulative size distributions. The model was compared to the well-established models, which are based on the population balance method. The specific rate increased for all rock sizes as the volume of 100mm balls in the mill was increased. Tests using a coarser feed and smaller balls provided further evidence that once rocks are rounded, abrasion is due to localised surface damage, caused by impacts, rather than rotational shear. An allowance for rapid rounding of jagged rocks, followed by less rapid abrasion of rounded pebbles was also tested, but the analysis was not conclusive. The average specific rate is a useful measure of the capacity of a primary mill. The effect of power intensity (kW/t of ore) was also investigated as a means of extrapolating the pilot-plant data to large production mills.

Sep 29, 2003

By Marzio Piller, Girolamo Belardi, Jure Mencinger, Paolo Bozano, Gianni Schena

"The hydrodynamics of the Tri-Flo™, a two stage cylindrical cyclone used in dense media separation, is studied using Computational Fluid Dynamics. The flow field is simulated with an Euler-Euler Volume of Fluid two-phase approach and the Reynolds stress turbulence model.A unique feature of the device is that the separation medium suspension is pumped and introduced tangentially into the two cylindrical compartments while the raw feed is conveyed to the feed hopper and fed at the axial inlet. This feature allows to use less pumping energy and limits the unavoidable production of fines. The Tri-Flo™ complex flow pattern is little known but central to the efficiency of the separation.The velocity field is computed within the two compartments of the separator. The interface of the air-core that forms in the inner axial part of the cylindrical sections is identified and visualized. The numerical results for a reduced-size 100 mm ID Tri-Flo™ are compared against laser Doppler measurements on a transparent acrylic model (Chinè, 1995) operated with water. The robustness of the model and its prediction capability are verified.The possibility to accurately predict the velocity profiles within the vessel and their dependence on the main Tri-Flo™ operating and geometrical variables paves the way to a better understanding of the functioning of the separator, its design improvements and scale-up."

Jan 1, 2014

By S. Narra

The importance of bio-products production is enhanced with the abundance and renewability of ligno- cellulosic biomass in comparison to the depleting fossil fuels especially in producing environment friendly energy. Lignin is obtained as a sludge residue from the pulp and paper industries as well as from the bio- ethanol /bio-gas production plants. Lignin is a renewable fuel with a high heating value equivalent to anthracite coal, low ash content and hydrophobic properties. The extracted lignin in paper and pulp mills is usually burnt at the mill directly to cover the energy production costs of the mill. The efficient utilization of lignin can reduce the percentage of lignin sludge used for energy production in comparison to the present situation. Presently the lignin is burnt /incinerated as sludge with minimum of 30 to 50 % moisture content. This high moisture content reduces the energy efficiency and simultaneously utilizes more amount of lignin sludge in producing the required energy. This paper explains a possibility of integrating sludge-pelleting techniques in paper and pulp mills. The integrated sludge-pelleting techniques would lead to an optimal utilization of lignin for energy and would simultaneously save the lignin resource for material utilization. The sludge pelleting process solves also the problem of handling, storage and explosion risks of lignin when compared to the present situation.

Sep 1, 2012

By Takashi Furuyama, Sukeyuki Mori, Tetsuo Ikejiri, Abel Bissombolo, Yoshitsugu Koga, Masamichi Hata

In Japan, the increasing number of automobiles newly put into circulation is followed by a larger amount of end-of-life vehicles from which valuable metals are being recovered in shredder and related plants. Nevertheless, the processing of these scrapped automobiles which has reach a recycling rate of about 75%, generates a huge volume of waste, locally known as .shredder dust., which is commonly dumped on landfills. The saturation and depletion of valuable disposal sites in the near future, as well as the social and environmental problems related to the accumulation of these residues disposals are a major challenge for the automobile shredding industry. To promote an alternative way for the management of these disposals, the authors have initiated and developed a system for their processing, on the basis that more than 90% of these residues are combustible materials that could be used as refuses derived fuel. The developed processing system points out the mechanical/physical separation of shredded automobiles residues into two streams by means of an ascending airflow passing through a vertical zigzag separator and, the compaction of the light-density fraction of materials (that is about 60% of auto shredder residue recovered as float products and mainly composed of cotton, sponges and light plastics) to form a refuse derived fuel (RDF), the density, calorific value and ignition loss of which are 1.19 g/cm3, 4470 kcal/kg and 60.7%, respectively.

Jan 1, 2003

By P. Somasundaran, Tarun Bhambhani, D. R. Nagaraj, P. Patra

"Certain non-sulfide gangue minerals are known to have a detrimental impact on flotation performance. When present in large amounts, they can negatively affect recoveries, grades and throughput at current operations, and dictate the viability and economics of a greenfield project. While the problem has been investigated for a long period of time, a scientific understanding of the mechanisms by which these minerals affect performance has not been obtained, and no acceptable solutions have been developed. This study focused on the role of physical aspects (e.g. shape, size and morphology) of these minerals as the underlying factors for poor performance. Flotation tests were conducted using model mineral systems to understand the impact of one phyllosilicate mineral (muscovite) on flotation kinetics, recoveries and grades. The study reveals that there is minimal impact on flotation kinetics, no impact on recoveries, but a very strong detrimental impact on concentrate grade. The traditional mechanisms of transport such as true flotation and entrainment are not sufficient in describing the extent of transport. The transport is attributed to the unique platy morphology of muscovite, which allows for action of buoyancy forces. Data also shows that the muscovite transport to the froth phase depends on particle size; coarser sized muscovite (100-150@) report to the froth phase in much larger amounts than medium sized muscovite (50-100@). At finer size fractions (<50@) the transport is also increased, and this is likely due to entrainment."

Jan 1, 2014

By Lucy van de Ruit, Megan Becker, Aubrey Mainza, Jenny Wiese

"UG2 chromitite ore is a complex, highly disseminated platinum ore from the Bushveld Complex in South Africa, with typical platinum group mineral (PGM) grain sizes below 15µm. The introduction of stirred mills to the platinum industry has enabled grinding to finer product sizes, which has improved liberation and recovery of the finely grained PGMs. However, reduction in particle size leads to an increase in chromite entrainment in the flotation concentrate, which has a negative impact on the subsequent smelting process. Factors such as particle size, froth structure, solids concentration and water recovery have all been identified as impacting entrainment, but whether particle shape also has a significant effect is unclear. The purpose of this study was to determine whether the recovery of chromite particles by entrainment during the flotation of UG2 ore is affected by particle morphology. A laboratory vertical stirred mill with inert ceramic media was used for grinding UG2 ore which was then floated in a batch flotation cell. Flotation feed and concentrate samples were analyzed using QEMSCAN to quantify the angularity and aspect ratio distributions of the particles. The stirred mill product was found to have relatively broad aspect ratio and angularity distributions, with the major mineral components (chromite and silicates) having very similar shape characteristics. Analysis of flotation feed and concentrate samples suggested that particle shape does not have a significant effect on chromite entrainment."

Jan 1, 2014

By Xianjun Lyu, Junxiang Wang, Peng Wu, Minjie Lian

"In recent years, the efficient cementation of mine tailings is a new way to manage mine solid wastes. The traditional cement materials have a slow setting time, large dosage and poor cementation strength for fine aggregate such as mine tailings. Therefore, the preparation of new type cementitious materials for the cementation of fine tailings has great potential in the treatment of mine waste solids. The paper mainly focuses on exploring the critical factors affecting the cementing performance of granulated blast furnace slag and its performance in the cementation of fine aggregate. Results indicate that the fineness of slag has a significant effect on its cementitious activity and Portland cement clinker has a better stimulation effect on the cementitious properties of slag than lime. And, anhydrite has a better early stimulation effect on the cementitious properties of alkali-activated slag compared to semi-hydrated gypsum and dihydrate gypsum. According to a series of tests on the cementation of fine iron tailings, the optimal ratio of slag, Portland cement clinker and anhydrite is determined as 60:30:10. Compared with P.O 42.5 ordinary Portland cement, the new slag based cementitious material shows much better cementing performance on fine tailings sample. Under the dosage of 12%, the compressive strength of fine tailings mortar using slag-based cementitious material in 3 curing days is increased to 168% that of using P.O 42.5 ordinary Portland cement, while the compressive strength in 28 days curing period is increased to 194%."

Jan 1, 2018

By M. V. S. Cavalcante

The quality of iron ore pellets, represented in terms of parameters such as cold compressive strength (CCS) and Tumble Index (TI), has a strongly influence on the productivity and energy of reduction furnaces like the blast furnace and on the quality of hot metal or liquid iron. The main objective of pelletization operations is to produce iron ore pellets of desirable specifications and ensure high levels of plant productivity and energy efficiency. Advanced process control of an industrial iron ore pellet induration process using a soft sensor for pellet quality and fuzzy-logic based control algorithm is described in this paper. The pellet quality soft sensor consists of a rigorous mathematical model of the induration process and a statistical model for the pellet quality parameters. The mathematical model is based on the fundamental principles of heat and mass transfer between gases and pellets, kinetics of drying and condensation of moisture, combustion of coke, calcination of limestone, and melting and solidification of pellets. The predictions of wind-box temperature profiles are in close agreement with the measured profiles. The time-temperature profiles of the pellets during induration, along with raw material characteristics and induration process operating conditions, are used as inputs to the quality model to predict cold compressive strength and the Tumble Index. The predictions of the quality soft sensor along with the rules based on fuzzy-logic derived from simulation results and operator experience are then utilized to control the induration process to achieve precise control of the quality parameters and to optimize the induration process in terms of fuel efficiency and productivity. The mathematical model is also utilized as a soft sensor for temperature, moisture and composition profiles of pellets and gases. Results of implementation of this model-based control strategy on an industrial scale induration process will be presented. Keywords: iron ore, pelletization, simulation, process control, optimisation

Sep 1, 2012

By F. Karakas

Water based paint formulations consist of some industrial minerals with quantities varying from 20 to 50 %. Quality of paint is directly related to these minerals used as pigment or filler in the production. Titanium dioxide is the most important and expensive pigment in paint formulations. Other minerals such as calcite and calcined kaolin are used as filler and mainly as a substitute for TiO2. Consequently, particle-particle interactions including adsorption, coating and size distribution of pigment mixture directly affects the paint quality. In the present paper, a new type of pigment mixture for possible use in architectural water based paints was developed through grinding. The effect of different types of grinding methods on physical properties of TiO2 and calcite mixture and the quality of paint produced by these mixtures have been revealed. Three different types of mills; conventional ball mill, vibratory ball mill and high-speed attritor were used for grinding of TiO2 and calcite. Viscosity, zeta potential and particle size distributions were used to characterize the pigment mixtures obtained upon grinding. The quality of paint was evaluated by standards based on both wet and dry paints such as viscosity, density, opacity and gloss. The paint produced with the pigment mixtures prepared in vibratory ball mill and high speed attritor showed improvement in physical properties particularly in the distribution and dispersion of mineral particles. Keywords: grinding, pigment, paint, TiO2, calcite

Sep 1, 2012

By Rob Morrison, Andrew Scott

"Long before a modern mine commences operations it has already become a wealth of information. After start up, it can generate enormous quantities of data - especially with semi-automated data acquisition by instrumented mine equipment.However, much of this data is of limited use for evaluation of (potential) performance unless it links in some way to the site business model.An underlying reason for this waste of data is that the different cultures, financial, technical, community, environmental, etc, not only have many areas of interest but also have very different conceptual models by which they evaluate performance.It is too ambitious to attempt to bring all of these cultures together - in a single step.However, the success of the Mine to Mill - project has demonstrated that substantial operational value can be added by using a more integrated approach to comminution. The next logical step is to integrate measurement and then to track performance from ore body model to saleable product and waste disposal. From resource to product also represents a path from very sparse, highly variable data to much more detailed measurement and more representative sampling.However, in both cases the data collected is strongly focused on the technical requirements - not on the business model.This paper considers how to define at least some of the key decision points in terms of some case studies.Performance data from many areas might be used to derive simple models which can then be used for forecasting and optimisation of planning."

Jan 1, 2003

By R. Imhof, S. E. Sánchez-Pino, H. Sprenger, S. A. Sánchez-Baquedano

"In 1992, Ingeniería de Minerales started with the introduction of pneumatic flotation technology in Chile and South America. This technology consists of vertical cells and gyratory cells, used mainly under actual operational conditions, with pilot units directly installed in the concentrator circuits of the industrial process. Successful industrial applications have been observed at Los Pelambres, in the molybdenum plant; at Codelco Andina in the molybdenum plant as pre-rougher to produce directly a final concentrate; in the copper circuit at Las Luces as pre-rougher producing final concentrate using sea water; at Minera Valle Aconcagua where a full automatic plant produces pre-concentrate from fresh tailings as feed; at the silica and silicate reverse flotation circuit of Compañía Minera del Pacífico; in cleaning the final concentrate of Zn by reverse flotation removing ultrafine carbonate; and in a plant that reprocesses fresh tailings from a copper slag flotation process. Positive operational changes in the design of the flotation circuit have been seen in plants using G-cells and V-cells, improving the performance of flotation circuits and the quality of final products. The high concentration of bubbles and micro turbulence produced by the pneumatic aeration units provide a high probability of collision and attachment, reducing dramatically the residence time. Though it is a pneumatic flotation, no compressed air is needed, and the equipment is characterized by low maintenance costs, full automation, savings in investment and energy."

Jan 1, 2014

By Ping Fang, Dezhou Wei, Zichuan Guan, Wengang Liu, Yanbai Shen

A new cationic collector, bis(2-hydroxy-3-chloropropyl) dodecylamine (N23), that can be dissolved in water easily was synthesized successfully. Its flotation performance to quartz was investigated compared with dodecyl amine in hematite reverse flotation system. It was found that N23 showed stronger collecting performance to quartz than dodecyl amine. The maximum recovery of 98% to quartz was obtained at a collector concentration of 43.3 mg/L in the pulp pH range of 6-9. This collector can be used to float quartz from hematite when starch was used as depressant. Optimal separating results with 90.06% iron recovery and 66.3% iron grade to artificially mixed sample were achieved at a collector concentration of 43.3 mg/L and a starch concentration of 23.3 mg/L at neutral pulp pH when hematite and quartz were mixed at a mass ratio of 3:2. The adsorption mechanism of the collector on quartz surface was investigated by infrared spectroscopic analysis and zetapotential measurements, which revealed that electrostatic attraction and hydrogen bonding adsorption occurred between the collector and quartz surface.

Jan 1, 2014

By V. Sovmen

The gold-ore Olympiada deposit is located within the Yenissei range (Krasnoyarsk Region, Russia). Primary sulphides ores are metasomatic changed rocks, mica-calcite-quartz structure with impurity amphiboles, chlorites, carbon, the rare thin grains of sulfides (up to 3%~5%) and native gold. The structures of ores are fine-grained, prevailing texture of ores - interspersed, vein-interspersed, band-interspersed, veinlet. The most important minerals in the deposit are: gold, arsenopyrite, pyrrhotite, antimonite, Sb-sulphosalt, quartz, muscovite, calcite, siderite, titanium minerals, chlorite and minor sulfides like chalcopyrite, galena, sphalerite, etc. A common problem in mineralogical studies applied to mineral processing (concentration, cyanidation, etc.) is the characterization of gold in ores and technological products. This paper discusses the behavior of minerals during technological process at operating factory in Olympiada Mine and gold distribution in the ores and products. For the mineralogical characterization of minerals ? combination of analytical techniques was used. Gold is encountered in the primary ores as free grains among rocks, growth with sulfides and nonmetallic minerals, inclusions in sulfides, sulphosalt, and nonmetallic minerals. The gold-sulphide ores of Olympiada deposit can be quite complicated for enrichment. With the purpose to increase the extraction of metal from concentrates by liberating the dispersed gold, forming inclusions in sul-fides, there is used technology of biooxidation of flotation concentrates in Olympiada Mine. Gold and the basic ore-forming minerals in the ores feed, sulphidic concentrates, biocakes, tailings of concentrates of flotation and products of hydrometallurgical leaching have been studied in the mineralogical research. During researches it is established that pyrrhotite was completely oxidized while arsenopyrite was oxidized almost completely in the bacterial oxidation process. Pyrite and antimony minerals behave similarly and were oxidized only partially. The main oxyhydroxides in the bacterial oxida-tion process are goethite, limonite and jarosite. The results of mineralogical researches showed reasons of losses of gold during hydrometallurgical enrichment.

Jan 1, 2014

By F. C. Araújo, T. Tavares, J. Leite

"This work presents the small-scale mining cluster of kaolin in Rio Grande do Norte (RN) and Paraiba (PB), both Brazilian states, including the following information: number of companies, process flowcharts, production numbers, mineralogical (XRD) and chemical (XRF) composition, granulometric distribution (screen and laser granulometer) and image analysis (SEM). Some social indicators in the region of the RN and PB States are presented in association with these data. The number of companies and their flowsheet were obtained through in situ visits and sample collection for technological characterization. The comparative study of the different flowsheets for kaolin production in the world was done using the databases and presenting the state of the art of kaolin processing. The results indicated that the mean feed typically contains 35-39% kaolin with quartz, muscovite and kaolinite as main mineralogical components and SiO2 (65.83%), Al2O3 (21.19%), K2O (3.9%), and Fe2O3 (0,63%) as main chemical constituents. The products of mineral processing are twofold, one between 74 µm and 37 µm, and the other smaller than 37 µm. The wastes of operation had major quantities of kaolin. The average Human Development Index (HDI) of the cluster region is approximately of 0.61, which shows an association between mineral processing plant and social indicators. The kaolin recovery, however, is between 30-55% for the three most common types of flowsheets that are currently used in the small kaolin mining cluster, indicating a need for technological improvement to achieve regional development. These data could be used incrementally to adapt the process plant currently used in the small-scale mining cluster of kaolin."

Jan 1, 2014

By A. Mainza, H. Hill, L. S. Bbosa

"Impact breakage is the most elementary size reduction mechanism in comminution devices. In comminution research, characterization of breakage is primarily concerned with the energy expended to cause it. The main challenges of this approach have been quantifying the actual energy requirements of impact breakage and developing mechanistic models to accurately describe the process. For engineering load analysis, fracture is characterized in terms of strengths such as yield stress and ultimate tensile stress, which govern the maximum loads specific materials can be subjected to before irreversible inelastic deformation and subsequently complete fracture occur. With this approach, the main challenge has been to elucidate the underlying mechanism, in the means that the load causes weaknesses in the material microstructure to act as sites for stress concentrations, leading to crack initiation, propagation and eventual failure. Studies dedicated to investigating particle fracture under impact loading have led to the development of several devices for conducting breakage characterization tests. These devices include the drop weight tester, split Hopkinson pressure bar, rotary breakage tester and the short impact load cell. All these have different particle loading and breakage methods, and thus can yield distinct information which can be compiled together to study a material and the nature of breakage. This work analyses the single impact breakage data obtained across the listed devices. A homogenous ore commonly known as blue stone is used for all breakage tests. The work is conducted using standard procedures specific to each device as closely as possible. Drop weight and rotary breakage tests were used to obtain hardness parameters based on an existing t10 breakage model, while split Hopkinson pressure bar and short impact load cell measurements provided properties based on conventional engineering load analysis. The results were used to highlight the significance of the loading geometry, impact mechanism and impulse on the extent of breakage."

Jan 1, 2018

By J. W. Ahn

Calcined calcium oxide from limestone is hydrated to manufacture calcium hydroxide, and then precipitated calcium carbonate is synthesized from calcium hydroxide. Precipitated calcium carbonate of various morphologies is obtained by controlled conditions of each step and characteristics of limestone, calcium oxide and calcium hydroxide. Especially characteristics of calcium hydroxide have the most influence on morphology of precipitated calcium carbonate character. In this study, therefore, it is investigated the specific surface area of calcium hydroxide and morphology of precipitated calcium carbonate according to hydration temperature. Calcium hydroxide hydrated at high initial temperature has larger particle size than that hydrated at low initial temperature. And formation yield of aragonite precipitated calcium carbonate has improved by using calcium hydroxide had larger particle size (hydrated at high initial temperature).

Jan 1, 2014

By A. Singh, M. Ntlhane, V. Ross, M. Dlame

"Fine valuable particles are often lost to flotation tailings streams due to inefficient collection by air bubbles as well as passivation of surfaces by oxidation and slimes. The application of high-shear hydrodynamic cavitation devices (HCDs) to overcome this problem has already proven to be a considerable success in the industry. This paper details the results of further investigations that were undertaken at Mintek to better understand the mechanisms involved when preconditioning feed slurries in an HCD. By promoting inter-particle attrition and conditions of high shear within the reactor, cleaning of particle surfaces is enhanced as well as the formation of superfine (nano) bubbles which are believed to aid their agglomeration and subsequent collection by normal sized bubbles. In order to broaden the envelope of understanding with regard to application of the technology, rather than tailings material as investigated earlier, a Platinum Group Mineral (PGM) UG2 ore from the Bushveld Complex in South Africa was used in this study. The results of a series of batch flotation tests in a 10L Denver cell are presented, being conducted after the feed has been subjected to different methods of preconditioning. It was demonstrated that the preconditioning significantly improved the flotation kinetics of the PGMs, the optimum being obtained after around 20 passes through the reactor. This was accompanied by a much enhanced recovery-mass pull relationship and a significant improvement in the grade-recovery response. Significantly, the selectivity between the PGM and the deleterious chromite (expressed as Cr2O3) gangue more than doubled under these conditions. Modelling of the PGM data by means of the modified Kelsall model indicated that both the fast and slow floating rate constants were improved.INTRODUCTIONIt is well known that the flotation recovery of fine and ultrafine particles, typically less than 10 micron in size, is a challenge (Yoon et al., 1989; Miettenin et al., 2010). Although these particles are typically well liberated, due to their very low mass and inertia, the collision efficiency with air bubbles is low as a result of the inability of particles to penetrate the liquid streamlines around bubbles. Hence the probability of contact is often regarded as the ratedetermining step in flotation of ultrafine particles. Introducing more power into conventional flotation machines is likely to solve only part of the problem, as conventional mechanisms are effective only to a point in terms of shear and micro-turbulence. Further challenges are posed by the treatment of low-grade or oxidised tailings dump material, where valuables are passivated due to prolonged exposure to the atmosphere or slimes. Over the years, various mitigating strategies have been investigated, including the use of dissolved air flotation (Martinez-Gomez et al., 2013; Calgaroto et al., 2015), shear flocculation (Subrahmanyam and Forssberg, 1990), seed or carrier flotation (Tabosa and Rubio, 2010), sonication to clean particle surfaces (Aldrich and Feng, 1999; Newell et al., 2006), high intensity conditioning (Bulatovic and Salter, 1989; Chen et al., 1999; Tabosa and Rubio, 2010), and various electrochemical approaches such as changing Eh in order to promote formation of dixanthogen, dissolution of oxidation products by lowering the pH, activation by sulphidisation (Newell et al., 2006; Becker et al., 2014), and the use of alternative collectors."

Jan 1, 2018

By Emile Scheepers, Chris Aldrich, Jacques J. Eksteen

The pneumatic injection of CaC2 powder into molten iron has become a very reliable and effective way to carry out desulphurisation. The key variables that influence the kinetics of this process are the condition and composition of the top slag, the oxygen activity in the hot metal and the injection conditions. Notable injection parameters include carrier gas flowrate, reagent flowrate, lance depth and initial sulphur concentration. A one-dimensional, steady-state model for momentum, heat- and mass transfer in rising gasliquid- powder plumes was developed for conditions relevant to the CaC2 refining process at Saldanha Steel?, South Africa. Combined with a model that predicts the contribution of the topslag to the process, the overall rate of desulphurisation as a function of time was determined, thereby quantitatively demonstrating the influence of the above-mentioned injection parameters on the kinetics of the desulphurisation process.

Jan 1, 2003

By K. Haga

In this study, flotation tests were performed to investigate behavior of enargite and chalcopyrite ores from different sources synthetically mixed for separation of enargite. Flotation parameters including; pH, reagents concentration and type and flotation time were controlled to obtain an enargite concentrate with high As and chalcopyrite concentrate and final tailings with As content below 0.5 mass%. The copper ore bearing enargite mineral contained 5.87 mass% As and 16.50 mass% Cu while the chalcopyrite bearing ore contained 0.32 mass% As and 21.63 mass% Cu. The two ore samples were mixed at 7:3 (enargite: chalcopyrite) by weight ratio to prepare a mixed ore sample with arsenic content at 3.16 mass% and 18.25 mass% Cu for the flotation study. For enargite single ore flotation, the 38?75 µm size fraction showed that over 98% enargite was selectively recovered within 5 min at slurry pH of 4.0 and arsenic content in the final tailings was reduced to 0.22 mass%. In mix ore (enargite+chalcopyrite) flotation, 97% of enargite was first removed at pH 4 followed by chalcopyrite flotation at pH 8, and over 95% recovery was achieved in 15 min flotation time. Arsenic content in the final tailings was reduced to 0.1 mass%.

Sep 1, 2012