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By Alessandro Blasi, Massimo Morgana, Corradino Sposato, Pietro Garzone, Giuseppe Devincenzis

The rare earth elements are essential for a diverse and expanding array of high-technology applications, which constitute an important part of the industrial economy of the 21st century. As a matter of fact, rare earth has been listed in the category of strategic elements in many countries becoming a core business for international research. Experimental tests have been carried out on a bench scale battery of mixer settler composed of 24 stages, each one with a volume of 150 ml. These trials have been performed at room temperature checked by a micro-climatic control system. The battery was setted in two sections: extraction and scrubbing section. Rare earths concentrations were obtained by ICP-OES analysis made on aqueous phase and on the stripped from organic phase. We obtained a complete separation of light rare earth (La, Ce, Pr, Nd) in two sub-groups: La/Ce and Pr/Nd.

Jan 1, 2014

By J. B. Newkirk, A. H. Geisler

The alloy Cu4Pd has a disordered face-centered-cubic structure when quenched from temperatures between 478ºC and the melting point (about 1100°C). Below 478ºC an ordered phase is stable. The results of a Debye-Scherrer X-ray analysis indicate that the ordered phase has a tetragonal unit cell described by the space group C24h — P42/mt with 2 Cu in 2a, 2 Cu in 2f, 4 Cu in 4j (x = 0.2, y = 0.6), 4Pd in 4j (x = 0.4, y = 0.2), and 8 Cu in 8k (x = 0.1, y = 0.3). The orientation relationship between the face-centered-cubic phase and the ordered tetragonal phase is given by: [100],,. // [130]al,. COO1Ia.d.//COO1I,,.. • The behavior of Cu,Pd is typical of ordering alloys except that the transformation is very sluggish. The increase in hardness and the microstructural and X-ray diffraction effects are interpreted in terms of coherency strains caused by the ordering. AN anomalous construction in the Cu-Pd phase diagram (Fig. 1) was reported in 1939 and has been allowed to stand without further published attention since that time. The odd figuration about the composition 10 to 27 atomic pct Pd is derived mostly from the work of Jones and Sykes.1 Evidently several features of this binary system require further study if the constitutional forms are to be well understood. The present paper includes a study of one of these features, that is, the crystal structure of a single ordered alloy containing nominally 20 atomic pct Pd. This choice of composition was suggested by the work of Harker and associates who determined the structure of Ni4Mo2 and Ni4W.3 The nature of the ordering process in Cu4Pd was studied also by observing the hardness, microstructure, and Debye-Scherrer patterns of specimens which had been aged at various temperatures after quenching from an initial disordering treatment. Experimental Methods A 20 gram ingot of Cu4Pd was made by melting spectrographically standardized copper from Johnson, Matthey, and Co., and commercially pure (99.5 + ) palladium in an argon-filled quartz tube. Chemical analysis showed that the ingot contained 80.0 atomic pct Cu. The ingot was rolled about 60 pct to a strip 0.060 in. thick and was homogenized for 16 hr at 950°C in low pressure argon. Rods cut from the rolled strip were worked into wire 0.015 in. in diameter, and specimens for hardness and microscopic examination were cut from the remaining strip. All specimens, with the exception of some of the wire, were given an initial disordering treatment by heating for 16 hr at 950°C, followed by water quenching. A 10 cm length of as-drawn wire was water quenched after being held in a temperature-gradient furnace4 for 89 days. Room-temperature Debye-Scherrer photograms were then made at points along the wire to determine the temperature below which the ordered phase was stable. Although the accuracy of temperature determination in the gradient was only about ±10 °C, the temperature gradient was sufficiently gradual that the sensitivity was much better and locations which had differed by as little as 1°C could be distinguished. An analysis of the crystal structure of the well ordered alloy was made by X-ray diffraction using a specimen cut from this wire. The change of Debye-Scherrer pattern as ordering progressed was studied by using isothermally aged samples of initially disordered wires. The wires were sealed under low-pressure argon in small quartz tubes for heat treatment. After the aging treatment, the tubes were quenched in water and photograms were made at room temperature in a 10 cm diam camera using filtered Cu kX. (A = 1.540511) Hardness was measured on a Vickers hardness tester using a 10 kg load and 2/3 in. objective lens. Reported values are the average of at least three impressions made on flat specimens 0.060 in. thick. After the hardness of a heat-treated sample had been measured, it was resealed in low-pressure argon and returned to the furnace for continued aging at the same temperature. In this way, two samples served for all aging times at each temperature. Hardness specimens which had been aged 500 hr or more were used for metallographic examination after the final aging treatment. A dilute potassium-dichromate etching solution was used.

Jan 1, 1955

By Matti Leiponen

During the last few years Outokumpu Oy has put forth efforts to develop the material handling in the Pori tankhouse. The final objective is full automation including cell loading. The fully automated material handling provides high quality anodes and cathodes as well as equipment and handling systems capable of very accurate cell loading. The new machines and equipment for accurate cell loading and the methods to produce high quality anodes and starting sheets are described in this paper.

Jan 1, 1987

By M. S. Seehra, V. S. Babu

"INTRODUCTION The accurate determination of the free silica index in coal mine dusts is an important requirement because severe health hazards are believed to be associated with the inhalation of respirable-sized silica particles.1-6 Free silica refers to the three polymorphs of silica (Si02)viz., quartz, cristobalite, and tridymite-although quartz is usually the dominant form in most mine dusts.6 The free silica index is the concentration in micrograms of free silica in air per m3 of air sampled corrected to standard conditions of 25°C and 760 mm/Hg, the present MSHA (Mine Safety and Health Administration) limit on time-averaged basis being 100 µ.g/m 3 for coal mines. A recent review7 has concluded that quartz, cristobalite, and tridymite particles impart nearly equal long-term hemolytic damage when compared on a per unit surface area basis.At present, two experimental methods-viz., transmission infrared spectroscopy (TIRS) and x-ray diffraction (XRD)-are commonly used for the determination of silica concentrations in mine dusts. In TIRS, which has been adopted by MSHA and is commonly called the P7 method, the silica absorption band near 800 cm - 1 is used for quantification. However the mineral kaolinite, which is commonly present in mine dusts, also has absorption band, albeit weaker, at 800 cm- 1• To correct for this interference, one uses the stronger 915-cm -1 band of kaolinite to determine the concentration of kaolinite, and the kaolinite contribution to the absorbance at 800 cm-1 is then determined from a calibration curve, leading to the determination of silica by subtraction. In the XRD technique, usually an internal standard such as CaF 2 is used to determine the concentration of silica from line intensity measurements. XRD has the added advantage that concentrations of quartz, cristobalite, and tridymite can be determined.8•9 In an exhaustive study on the precision of the techniques ofTIRS and XRD for monitoring worker exposure,9 the conclusion has been reached that both methods measure silica within 253 of the ""true"" value 953 of the time in a single laboratory."

Nov 1, 1995

By Pietro Navarra

A great deal of effort has been expended on how to optimize conventional water cooling circuits in furnace cooling elements, and the results have been largely satisfactory. However, there is a general agreement that the proximity of high-pressure water passages to the flow of molten furnace products is a safety concern. Nonetheless there exists little alternative to the formula: increasing furnace integrity implies the incorporation of more extensive forced-convection water cooling systems. Recent developments in evaporative cooling technology have resulted in the development of a high-capacity heat pipe capable of operating under the thermally intense environments of a metallurgical furnace. The system functions using several kg of a working fluid (water) in total, has no moving parts, and allows for a significant reduction in cooling water requirements. Full-scale pilot tests of a copper tap hole and slag launder were done in 2003 and2005, with detailed results given in this paper.

Jan 1, 2006

By Benito Barbabela Silva, Michel Garant, Mathieu Dubé

Pellets market challenging scenario has stimulated pelletizing experts to pursue innovative alternatives to process development in order to increase pellets competitiveness vis-à-vis sinter. When it comes to indurating process, pelletizing productivity is still limited and its OPEX inflated by the lower input of carbon into mixes due to quality impairment caused by magnetite formation in pellets core. This obstacle led to the rethinking of carbon distribution strategy within the green balls. To achieve such purposes, COREM through its precompetitive research program dedicated to its members, has proposed the layered pellets®, a two-stage balling technology. Balling in disc and pot-grate tests in COREM’s pilot plant were carried out to proof the concept, support the arising technology and evaluate its potential. According to first results, while CCS strongly improved, tumble and abrasion indexes as well dynamic LTD must be further investigated. Tests on four classes of equivalent carbon content pellets to evaluate layering strategy gave very good perspectives concerning the increase of productivity, and the reduction of fuel consumption and GHG emissions.

Oct 1, 2019

By S. Khallouk, J. Zollinger, J. R. Kennedy, E. Bouzy, B. Rouat, D. Daloz

Titanium aluminides recently replaced Ni-based superalloys as turbine blades in the last LP stage of aircraft engines. To extend their range of use at higher temperature their properties need to be improved, either by alloying or processing. An efficient solution is to reduce the grain size during the solidification process. In the first part of the paper, an overview is given on the possibilities for grain refinement of such alloys, based on literature data and new results. The most efficient grain refinement is obtained with boron addition which leads to boride formations that are detrimental for in-use properties of turbine blades. In this work, the use of the high grain refinement potency of inoculation with non-brittle particles has been used by developing new refractory-based inoculants. The effect of one of these inoculants on grain refinement of an as-cast structure in a Ti-46Al is presented; resulting in a reduction of the grain size by a factor of 3.While less efficient compared to the potency of boron containing alloys, the grain refinement is effective and does not introduce any embrittling particles.

Jan 1, 2015

By Donald W. Breck

Zeolites were first recognized as a new group of minerals by Cronstedt with the discovery of stilbite in 1756. The word zeolite was coined from the two Greek words meaning "to boil" and "a stone" because of the loss of water when heated in the mineralogist's blow pipe. (1) In 1845 it was discovered that certain soils have the power of retaining ammonium Salts. (2) These were the first ion exchange experiments. Later it was discovered that it was the hydrated silicates in the soil that produced this phenomenon and several years later a paper was published dealing with the action of dilute salt solutions on silicates which showed that this base exchange principal, which we now call cation exchange, is reversible. The quantitative cation exchange behavior of zeolite minerals, such as chabazite, was studied. As a result any aluminosilicate which exhibited the property of ion exchange was referred to as a "zeolite;" even today the term has been applied to clay minerals as well as synthetic organic ion exchange resins.

Jan 1, 1973

By C. Balci

Specific energy is defined as the amount of work required to break a unit volume of rock and is used to predict the performance of mechanical miners. It is obtained from full-scale rock cutting experiments, which require large block samples, experienced personnel and expensive equipment found in only a few research centres in the world. Estimation of the optimum specific energy, at which a given geological formation is excavated at optimum cutting geometry in the most energy efficient manner, from mechanical rock properties to predict the performance/efficiency of roadheaders is the basic aim of this study. The mechanical rock property tests require only core samples, which are easier to obtain and to test. In this context, full-scale rock cutting tests are performed on 23 different rock, mineral and ore samples including sandstone, claystone, tuffite, chromite, trona and copper collected from some operating mines in Turkey. The optimum specific energy values are obtained for each sample. Physical and mechanical property tests are performed on the core samples obtained from the same samples to determine uniaxial compressive strength, indirect (Brazilian) tensile strength, static and dynamic elasticity moduli, Schmidt hammer rebound values, density, and Cerchar abrasivity index. The relationships between the optimum specific energy and the mechanical rock properties are analysed using statistical methods. The results indicate strong relationships between the optimum specific energy and the mechanical rock properties. The strongest relationships are found by using uniaxial compressive strength and tensile strength. The performance models developed in this study are in good agreement with the empirical models previously developed for roadheaders and can be used reliably for prediction purposes. Keywords: Mechanical excavation, roadheader, performance prediction, rock cutting, optimum specific energy, mechanical properties of rocks.

Jan 1, 2004

By Joseph Poplawski, Christian O’Keefe, Robert Maron

"Unique and difficult minerals processing measurement situations will be described and the application of passive array-based technology for performing these measurements will be illustrated. Examples of these situations include volume flow measurements in froth lines and flotation feed lines with entrained air, slurry lines with magnetite and other magnetic ore, slurry lines with abrasive or corrosive materials, high pressure lines, and slurry and non-slurry lines exhibiting scale buildup. Other situations include measurement of entrained air levels in pipes and in flotation columns. These measurements are achieved through CiDRA’s patented passive sonar array-based technology. This technology performs two independent measurements – flow rate and entrained air amounts. Two hardware implementations of this technology have resulted in a non-intrusive flow and entrained air meter which easily is installed on the outside of the pipe, and a submersible version for entrained air or gas holdup measurements which is used in flotation processes. Recent developments in extending this technology to solve other unique measurement problems such as valve movement confirmation will be covered.INTRODUCTIONThe minerals processing industry faces many unique and challenging process control conditions and environments. In terms of flow measurements, many of these situations are not being properly served by traditional flowmeters such as ultrasonic meters, magmeters, turbine meters, orifice plate meters, vortex flow meters, Coriolis flow meters, and venturi meters. A new class of flowmeters has been developed that solves these unique situations and flow measurement problems. This new class of flowmeter technology utilizes sonar-based processing algorithms and an array of passive sensors to measure not only flow, but also fluid composition. It does so accurately, reliably and without making contact with the fluid. These measurements are performed on practically any type of fluid within virtually any type of pipe.PRINCIPLE OF OPERATIONSonar array-based flowmeters are ideal for tracking and measuring the mean velocities of disturbances traveling in the axial direction of a pipe. These disturbances generally will convect with the flow, propagate in the pipe walls, or propagate in the fluid or slurry. First let us focus on the disturbances that convect with the flow. The disturbances that convect with the flow can be density variations, temperature variations or turbulent eddies. The overwhelming majority of industrial flows will have turbulent eddies convecting with the flow, thus providing an excellent means of measuring the flow rate as described below."

Jan 1, 2008

By C. I. Basilio

Pearson's hard and soft acid and base (HSAB) principle may be applied to flotation systems. The HSAB principle states that hard acids prefer to bond with hard bases and soft acids prefer to bond with soft bases. By determining the Drago E and C parameters for the different components of a flotation system, the HSAB principle could be used to explain the selectivity of some collectors such as thionocarbamates against some minerals. Determination of these parameters is done by utilizing Drago's theory and flow micro-calorimetry.

Jan 1, 1991

By W. C. Maurer

A study of the mechanics of shear failure of rock under pressure has been made. The transition from brittle to ductile failure occurs when the friction along the fracture surfaces exceeds the shear strength of the rock. A machine has been developed for measuring both the shear strength of rock and the friction along rock fracture surfaces. In this shear machine, the fractures are forced along definite planes; as a result, the rock is stronger than in compression tests where the fractures choose the weakest paths through the specimens. Friction is composed of several forces: (1) the forces to slide irregulurities on surfaces over each other; (2) forces to shear some of these irregularities; (3) molecular attractions across the fractures; and (4) forces required to break bonds resulting from melting and welding at the tips of irregularities on the surfaces. Friction along rock fracture surfaces is not proportional to contact pressure as usually assumed; instead, it increases as the contact pressure raised to the 0.4 to 0.8 power. INTRODUCTION It is difficult to produce tensile stresses under the high compressive stresses present in the earth; therefore, in deep drilling and geological faulting, shear failure predominates. This shear failure mechanism is complicated because rock is a heterogeneous material containing pore spaces, microfractures, elastic discontinuities and other imperfections. A study of shear failure of rock under pressure has been made to obtain a better understanding of this complex mechanism. A machine has been developed and used to measure the shear strength of rock and friction along sheared surfaces. This machine has certain advantages over the compression test — shear properties can be measured under low normal stresses and shear stress and normal stress can be varied independently. The first part of this paper is a description of shear failure of rock under pressure. The role of shear strength and friction along fracture surfaces in the shear failure mechanism will be discussed. The second part consists of a description of the shear machine and a discussion of the shear strength and friction data obtained using this machine. It will be shown that shear strength depends upon the size of the stressed zone, and that friction does not increase linearly with contact pressure as usually assumed. Attempts are made to relate some of the new concepts to tectonic failure and to dril ling. SHEAR FAILURE IN ROCK TRIAXIAL TESTS The shear failure mechanism is illustrated by the triaxial test shown in Fig. 1. In this test, a cylindrical rock specimen is subjected to a confining pressure, PC, and an axial pressure, pa. These external pressures produce normal a and shear T stresses on inclined planes within the specimen equal to1 where 0 is the angle between the specimen axis and a normal to the inclined plane. Fig. 2 shows how triaxial specimens deform as the axial pressure is increased. The pressure is

Jan 1, 1966

By Diego Marquina, Jorge Terrones, Jose Morales

Si bien los incendios en el sector minero representan apenas el 1 % del total en todos los sectores, sus consecuencias son potencialmente críticas, por lo que resulta necesaria una evaluación constante de riesgos de incendio. En una evaluación de riesgo de incendio convencional (FRA, por sus siglas en inglés) se detallan los escenarios de riesgo de incendio a los cuales está expuesta una unidad minera, considerando las condiciones de la instalación, el análisis de los procesos, identificación de actos y condiciones subestándar, equipos u operaciones, reportes de incendio o amagos, entre otros factores que permitan identificar y analizar los escenarios de riesgo de incendio para definir su nivel de criticidad y aceptación del riesgo. Este enfoque diferenciado de FRA busca priorizar la inversión en protección contra incendios, al tomar en cuenta una tolerancia específica al riesgo de incendio, vida útil de la mina y la continuidad de procesos o recursos críticos para la operación en un nivel mínimo tolerable.

Sep 20, 2019

By A. Modi, C. Li, R. Kabwit, W. Y. Xinchao, R. Joshi

The KIMIN copper project can treat 1.7 million dry t/a copper-cobalt ore. It has three mills in operation, two using conventional milling in water and the third in raffinate. We introduce the project process circuit and the capital and operating costs of using the raffinate process compared with conventional milling in water. There is a capital saving of approximately 11.5% for major equipment by removing the pre-leach thickener. In addition, it also achieves an annual operating cost saving of USD 2.1 million due to an increase in 49% of acidic raffinate recycled and reduction in lime consumption. The features of CITIC’s new duplex stainless-steel ball mill ,as the key equipment of the system, are also introduced

Jan 1, 2023

By W. W. Agey

Under terms of cooperative agreements, the Federal Bureau of Mines Inter-mountain Experiment Station assisted the General Services Administration (GSA) in operating the manganese-ore purchasing depots at Deming. N. Mex., and Wenden, Ariz. A resident metallurgist stationed at the depots directed sampling of the ore lots for assaying, took samples for amenability testing, calculated acceptances for payments to shippers, and served as technical adviser to the depot manager. The Intermountain Experiment Station at Salt Lake City, Utah, tested the amenability of the ores to determine how much of the manganese could be recovered in concentrates assaying a minimum of 40 percent manganese (Mn) and containing a maximum of 16 percent iron (Fe), 15 percent silica (Si02) plus alumina (AI203), 0.3 percent phosphorus (P), and I percent copper (Cu) plus lead (Pb) plus zinc (Zn). All chemical analyses of the ores and test products were done at Salt Lake City. In all, 567 ore lots submitted to the Deming depot were tested by flotation to determine their amenability to concentration into specification-grade material; 421 lots were amenable, and 146 were unamenable, primarily because of high copper content or excessive silica or iron in the flotation concentrate. Chemical analyses totaling 42,700 were made on the ores submitted to the Deming depot and on the products of the amenability-test program.

Jan 1, 1959

By K. L. Bainbridge

This report describes the results of a study to determine which types of, and to what extent, mining wastes can contaminate groundwater through leaching of acid-forming or potentially toxic constituents. The primary focus of this study was on coal mining wastes, especially overburden spoils and preparation plant refuse. In addition, the potential for contamination by leachates from clean coal stockpiles was also examined. The study approach included investigation of (a) the amounts and geographic locations of mining wastes in the United States; (b) the chemical character of mining wastes, especially with regard to potentially acid-firming or toxic constituents; and (c) the extent to which acid and/or toxic components are leached from mining wastes by rainwater. To evaluate the leachability of coal wastes, a laboratory waste leaching method was developed during this study to specifically simulate the leaching process over a long-term. Waste samples collected during this study were also leached by the EPA extraction procedure and ASTM waste leaching method. Results of the three leach test methods were compared to evaluate their relative capabilities to predict the leachability of mining wastes.

Jan 1, 1980

By T. A. Rickard

The notion prevails that writing is a knack, that the skilful use of the pen is a gift of nature. This is an error. Dogberry may be responsible for it; he said: "To be a well-informed man is the gift of fortune, but to write and read comes by nature". Because Dogberry said it, we may be sure that Shakespeare thought otherwise. Ability of any sort may be partly innate, but my own observation and experience lead me to conclude that most of the easy writers have become so by constant practice. As I recall the names of men successful with the pen, I remember that most of them have written a great deal and have taken particular pains to improve their style. The suggestion that proficiency in the difficult art is a happy accident provokes a sardonic smile. The larger part of the great writing in our literature is the result of persistent effort. An easy fluency has been the undoing of many; their flamboyant and fantastic scribbling has proved as perishable as froth. This criticism applies to technical writing also; in order that a technical description or discussion may hold the interest of the reader, at least long enough to cause him to read it to the end, the writing must be done carefully and systematically; otherwise it will fail in its purpose of conveying information. Clearness is absolutely essential. "It is not enough to use language that may be understood; it is necessary to use language that must be understood."* The purpose of writing, at least of that which is meant to be read by others, is not only to express ideas but to communicate them. Lack of perspicuity may prove as %ad as

Jan 1, 1931

By Richard D. Lang

Introduction Argyle is located in the Kimberley region in northwest Australia (Fig. 1). It is a significant diamond discovery by world standards and is the first major diamond find in Australia. The deposit consists of a pipe and associated alluvial deposits. Before the 1970s, diamonds were known to exist only sporadically in Australia. They have been found occasionally in association with gold deposits in Western Australia. There is a small deposit near Copeton in New South Wales. Some alluvial occurrences have also been found in Victoria, South Australia, and New South Wales. The first indicator minerals in the Kimberley region of Western Australia were discovered in January 1973. Production from the alluvial deposits at Argyle began in 1983. A $430-million construction program to develop a mine and treatment plant capable of producing 25 million carats per year was completed in December (1 carat = 0.2 grams). Ownership and management Participants in the project are known as the Argyle Diamond Mines Joint Venture. The group consists of CRA Ltd., 56.8%; Ashton Mining Ltd., 38.2%; and the Western Australian Diamond Trust (formerly Northern Mining Corp.), 5%. The project is managed by Argyle Diamond Mines Pty. Ltd., a wholly-owned subsidiary of CRA. Marketing is undertaken separately by the Western Australian Diamond Trust and by Argyle Diamond Sales Ltd. (for CRA and Ashton Mining groups). History Ownership of the Exploration Joint Venture has changed over the last 12 years as various parties changed their shareholdings. The original Kalumburu Joint Venture was formed in 1972 with five participants, each holding a 20% interest. By 1983, a number of ownership changes had occurred. The end result is that two original participants have sold out. CRA now holds a 56.8% share and the Ashton Mining Group holds 38.2%. CRA also assumed project management in January 1977. Table 1 demonstrates the long lead times involved in developing a project.

Jan 1, 1986

By B. Burke

Magnesium and its alloys are attractive materials for use in automotive and aerospace applications because of the low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. The present paper reviews the efforts to improve the attractiveness of magnesium through non-traditional processing, and presents preliminary results of current work on producing magnesium alloys via powder metallurgy P/M. P/M can be used to alleviate the formability problem through near-net-shape processing, and also allows unique chemical compositions that can lead to new alloys with novel properties. The feasibility of producing magnesium powder metallurgy products utilizing the industrially dominant process of mixed powder blending, uniaxial die compaction and controlled atmosphere sintering was investigated. An alloy composition based on the commercial Mg alloy AZ31 (3% Al, 1% Zn) was used to facilitate comparison to similar wrought products. The optimal processing conditions (compaction pressure, sintering time and temperature, and quenching temperature) were found to maximize sintered density and mechanical properties.

Jan 1, 2007

By J Arola, B Kettunen, W M. Bond

Separation of fine and coarse particles as separate streams prior to flotation, and their differential treatments, could substantially increase recovery and reduce collector consumption. A series of simulations was carried out to quantify the benefits from plant scale implementation of such a treatment at the Ispat Inland flotation circuit (Minorca mine). The study involved detailed plant sampling and sample analysis to generate the data needed for simulation studies. Samples were taken from all the streams from flotation feed to final concentrate, as well as cell lips and cell pulp. Sampling was repeated for the second ore blend that was processed by the plant during different periods of a year. Sample analysis involved sieve analysis and size by size chemical analysis for total iron, magnetic iron and silica. Raw data were mass balanced, and flow rates within the circuit were calculated. Mass balanced data were used to calculate model parameters representing the existing conditions. Usim Pac was used for both mass balancing and simulation studies. Available pilot and bench scale data were utilised to define the modified flow sheet and expected performance. The simulated flow sheet included classification of flotation circuit feed by hydrocyclones. While the coarse fraction followed the existing flow sheet, the fine fraction was sent to a magnetic separator. Magnetic and rougher flotation concentrates were combined to form the final concentrate. Two simulations for each blend were carried out. The first one assumed that there would be no change in size by size kinetic behaviours of both gangue and magnetite due to this modification. This was named as the worst case scenario, in which particles had a longer residence time due to reduced flow rates within the flotation cells. The second scenario anticipated that there would be an increase in recoveries of gangue and magnetite going into froth launder due to more efficient use of collector in absence of fines. Results showed that pre-classification of flotation feed could improve the flotation recovery by 0.3 - 0.5 per cent, with the major benefit being significant reduction (40 - 60 per cent) in the amount of collector used.

Jan 1, 2005