Search Documents

By Keli Vanessa Salvador Damin

O tratamento de austenitização é de fundamental importância para a qualidade do aço Hadfield, já que é o tratamento que garantirá a total austenitização do material. Dentre as variáveis que devem ser controladas estão à temperatura de tratamento e velocidade de resfriamento. O presente trabalho aborda um estudo de caso sobre o controle da temperatura dentro do forno de tratamento térmico bem como o comportamento da temperatura da água na piscina durante o resfriamento do material.

Aug 16, 2017

By A. R. Sorta, D. C. Sego

ABSTRACT Temperature, solute, texture, and thixotropic effects on time domain reflectometry (TDR) measurements of water content in oil sands tailings are investigated. Results indicate that TDR water content measurements are influenced by temperature, residual bitumen, and percent clay in the tailings. A correction of 0.03–0.10/ °C must be applied to the apparent dielectric constant (Ka) to account for the effect of temperature. The Ka-volumetric water content relationships of slurries differ significantly from the commonly used Topp calibration equation. The age of the tailings and the addition of phosphogypsum did not influence TDR water content measurements.

Jan 1, 2013

By J. E. Tiffany, S. S. Lubelsky

For blasting in coal mines the U. S. Bureau of Mines recommends that permissible explosives be used exclusively, that these shall be fired electrically, and that where feasible the working place shall be cut or sheared. These recommendations are made to promote safety and prevent mine explosions. Although permissible explosives are not flameless, their lower flame temperature and shorter duration of flanie make their use safer than that of nonpermissible explosives. Mixtures of air with both methane and bituminous coal dust, which are liable to occur in coal mines, may be ignited by coming in contact with any type of flame or spark of sufficient temperature and duration or by the firing of a blast. In a working place where a blast is to be fired, in addition to the use of permissible explosives, adequate ventilation for the dilution and removal of accumulations or outbursts of flammable gas should be provided. Bituminous coal mines should be rock-dusted as a means of rendering the coal dust harmless The efficient use of permissible explosives depends upon the proper preparation of the working place, standardized drilling, the strength characteristics of the explosive, and the use of a proper weight of charge. Experienced shotfirers should load, tamp and fire all holes. The major part of the information and data here presented is based on the results of efficiency tests made in large producing mines of Pennsylvania and Illinois. Bureau of Mines Report of Investigations, Serial No. 2697, describes how a standard method of blasting was worked out and put into operation in a mine in southern Illinois.' This paper contains a description of the methods worked out subsequently in another mine in that district. Descriptions of tests in two Pennsylvania mines are given in Bulletins 11 and 19 of the Carnegie Institute of Technology.2 These tests

Jan 1, 1928

By Ralph H. Sweetser

Carbon in pig iron is not only essential but, ordinarily, it is the most abundant metalloid present; iron without carbon could not be pig iron. Carbon in pig iron has been accepted, but seldom specified. How it gets into the pig iron as it is being smelted in the blast furnace, and why just about so much of it enters into the pig iron in certain blast furnaces, and more of it,; or less of it, enters the pig iron in other blast furnaces, or in the same blast furnace under varying conditions, are problems that have not yet been satisfactorily solved. During my own practical blast-furnace experience, I collected analyses of pig iron, including the graphitic and combined carbon, and recorded them in reference to the percentage of silicon present, having in mind the generally accepted explanation that "silicon drove out the carbon." To this actual experience, I have added some analyses given to me by J. B. Rogers, who was superintendent of the blast furnaces of the Ashland Iron & Mining Co., Ashland, Ky., and was making "silvery iron" at the time. These analyses are shown in Table 1. The analyses do not tell the whole story, but they show that with Pocahontas beehive coke, the total carbon was generally high. The data relating to the composition of the slag are lacking but my own customary practice was to have a rather basic slag. During my experience in making pig iron for the Bessemer and open-hearth departments, there were times when the steel men would complain about some mysterious quality in the pig iron that caused bad steel, in spite of the fact that the percentages of silicon, sulfur, phosphorus and manganese were within the specifications. Many reasons were advanced for this undetermined "poison" in the pig iron, but the favorite one offered by the steel men was that the blast-furnace man had "oxidized" the pig iron at the tuyeres in his eagerness to get big production and low cost. To these complaints of the users of steel-making pig irons were added those of the gray iron-foundry men and the malleable iron men. These groups are unaninlous in their conclusions that the trouble lies with the blast-furnace men; but there is not yet any harmonious conclusion as to the exact cause and remedy.

Jan 1, 1927

By Henrique Kahn, Daniel Uliana, Carina Ulsen, Guilherme Nery

"Gold has been a material in high demand since the dawn of humanity. After hundreds of years of exploitation, the increasingly search for gold occurs in lower grade deposits with greater extraction difficulty. Therefore, for maximum efficiency, deep knowledge of the characteristics of these minerals and their associations is crucial, which is acquired through an accurate and rigorous routine of process mineralogy and batch extraction tests. The industrial gold process extraction occurs by gravity concentration, sulphides flotation and cyanidation. For gravity concentration, it is fundamental to establish the proportion of free or coarse gold grains and its association to heavy minerals; regarding flotation, the most relevant data are the proportion of gold associated to sulphides and their liberation by the surface area; for cyanidation, it is crucial to evaluate gold accessibility and the kinetics of leaching. Thus, the characterization of gold associations and liberation is vital to establish the plant design, to optimize operating plants and to reduce gold losses. Our aim is the characterization of gold occurrence in low-grade Brazilian deposits with complex mineralogical assemblages to support processing flowchart definition and to predict metallurgical recoveries. Gold distribution in light and heavy minerals was evaluated by heavy liquid separation and the occurrence of gold in free or locked particles was carried out on heavy products by SEM-based automated image analysis using the MLA system. All the products of heavy liquid separation were cyanidated in head samples with different milling conditions to evaluate the reaction kinetics and maximum recovery."

Jan 1, 2014

By Matsufumi Takaya, Yukihiro Sakamoto

"Electric field emission properties from CVD diamond fabricated using pulse-modulated microwave plasma CVD were studied. Diamond was synthesized by microwave plasma CVD apparatus equipped with a pulse-modulated microwave power supply. Pulse conditions were varied from 1 to 10 seconds for pulse periods and from 0.1 to lHz for pulse frequency either. Surface morphologies of the deposits were differed by pulse frequency and duty cycle. As a result, FE properties prepared by different pulse duty cycle were different from continuous film which synthesized using continuous microwave significantly. Highest current density was obtained from the uneven morphology diamond film prepared at 17.5% pulse duty cycle.FE properties of the CVD diamond were depended on surface morphologies that related to the pulse conditions.1. IntroductionDiamond has excellent physical and chemical properties as an industrial material. Especially, hydrogen terminated diamond had the negative electron affinity (NEA) 1) and CVD diamond has this NEA property either as deposited 2). So the electron emission source to the FED is expected as one of this application of CVD diamond as cold cathode of electric devices. We studied on FE properties of various CVD diamond, pulse microwave plasma CVD diamond showed better property than those of other CVD diamond 3).This report studied on· the effect of the duty-cycle of pulse modulate microwave condition on FE properties of the diamond fabricated by pulse modulated microwave plasma CVD."

Jan 1, 2000

By P. A. Boeck

The thermal insulation of high-temperature equipment for industrial purposes is a subject that has not received from engineers and designers the attention its importance deserves. This may be attributed to a number of causes: In the first place, heat flow is a rather difficult factor to measure under the working conditions of an industrial furnace, and until the comparatively recent introduction into certain operations of the heat balance sheet, with a systematic attempt to account for the discrepancies in the totals, the various causes of heat losses and the reasons for their existence were not brought to light. Moreover, such rapid advancement and radical changes in the design of equipment, especially in metallurgical lines, have occurred that practice has apparently outdistanced the theory of design. In the modern tendency toward greatly increased size of units, effort has seemingly been made to utilize the heat of fuel gases without proper attention having been paid to conserving heat energy and confining it strictly to the points of maximum activity. The systematic study of the thermal properties of structural materials, which is being carried out by various government bureaus and also by a number of technical societies, is forming the basis for more intelligent and consistent work in the economically important subject of prevention of fuel waste. Advantages of Insulation It is not necessary in this practical and utilitarian age to enlarge upon the need of prevention of heat losses, but attention may advantageously be called to the other benefits derived simultaneously with the saving in fuel and the increase in thermal capacity of furnaces when properly insulated. In most industrial furnaces—which are here spoken of in the broadest sense, indicating general high-temperature equipment for any purpose and heated in any manner—the operations are generally carried on through a temperature range which has been found by practice to give the most ef-

Jan 1, 1916

By O. D. Sherby, J. E. Dorn

SEVERAL years ago Zener and Hollomon1 suggested that the flow stress of metals might be related to the temperature and strain rate in accord with the functional equation: s=s(eeh/rt) [1] at the same state. The Zener-Hollomon relation also contains the significant tacit implication that the energy for activation, AH, is substantially independent of the state of the material. The utility of this method for correlating creep data with tensile data was illustrated in a preliminary reportL on the effect of alloying additions on the secondary creep rates of binary a solid solutions in aluminum as shown for Al-Mg alloys in Fig. 1. Not only do the secondary creep and ultimate tensile properties for each alloy correlate well on this plot but in addition the activation energy, AH = 17,900 R cal per mol. is identical for the various compositions. Similar types of curves correlating the secondary creep rates at 422°K (300°F) with ultimate tensile data were also obtained for a series of dilute a solid solutions of copper, germanium, zinc, and silver in aluminum. In all cases the activation energy for creep, AH, was found to be equal to about 17,900 R cal per mol independent of the type of alloying element or its concentration. The coincidence of the activation energies for these alloys is probably due to the fact that the activation energies for creep are rather insensitive to small composition changes. Alloying additions, as shown in Fig. 1, however, increased the stress necessary to obtain equivalent values of ee?H/RT. Thus the stress level in curves of the type represented by Fig. 1 gives the relative creep strengths of the various alloys. Inasmuch as these correlations between creep and tensile data were obtained for creep tests at 422°K, it appeared advisable to ascertain the range of secondary creep rates and temperatures over which correlations between creep and tensile data could be made on the basis of the Zener-Hollomon relationship. If, for example, the activation energy changes with different ranges of creep temperatures, the utility of the proposed analysis would be severely weakened. But if AH is constant not only for all dilute alloys, but also over wide ranges of temperature and secondary creep rates, confidence will be developed not only in the broad utility of the Zener- Table I. Chemical Analysis':' and Grain Size of Alloys Mean Grain Residual Impurities. Wt Pct Diam- Alloying Atomic-eter, Element Pct Si Fe Cu Mg Mn mm Aluminum 99.987 0.003 0.003 0.006 0.001 0.25 Magnesium 1.617 0.003 0.004 0.006 0.26 Copper 0.101 0.003 0.003 0.0006 0.001 0.29 Zinc 1.616 0.003 0.005 0.007 0.001 '0.26 * The authors express their appreciation to the Aluminum Company of America for the preparation and chemical analyses of these alloys. Hollomon relationship, but also in its theoretical justification. The following investigation was instituted in order to ascertain the range of validity of the Zener-Hollomon relationship when it is applied to creep and tension data. Materials, Equipment, Technique In view of rather extensive correlatable data now available on the plastic properties of a series of binary a solid solutions of magnesium, copper, germanium, zinc, and silver in aluminum, these alloys were again selected for the present investigation. Previous reports have already covered the tensile properties of these alloys at subatmospheric temperatures," and at elevated temperature," as well as their fatigue properties at atmospheric temperatures, nd their creep properties at 422°K.' Resistivity measurementsa as well as precision lattice constant determinations? evealed that these alloys are a solid solutions. After homogenization. 0.100 in. thick sheets were rolled to 0.070 in. in thickness and recrystallized to about the same grain size. Since the details of these treatments were reported previously," they will not be repeated here. In order to appropriately reduce the scope of creep tests in this investigation only the typical alloys shown in Table I were investigated. All creep specimens were machined such that their tensile axes were in the rolling direction of the 0.070 in. sheet stock. The gage section was 2 in. long and 0.500 in. wide with a reduced section of 3.50 in. Creep strains were measured by means of rack and pinion type extensometers with a sensitivity of 0.005 in. per division. Readings were estimated to 1/10 of

Jan 1, 1953

By Ramkrishna Agarwal

A low grade iron ore is mined underground at Grace Mine using the panel caving method. Most of the development work is located in footwall. The runways for LHD equipments are heavily supported with steel sets on five foot centers. The sets are embedded in two to three feet of concrete. The initial cost of support is one of the largest single costs of production. During the process of ore-win¬ning, supports frequently fail, necessitating expensive repair. There is no systematic pattern to the failure of supports. A rock mechanics program was launched to isolate causes and their relative contributions to the failure of supports. The preliminary results are presented. A typical portion of a runway is instrumented to monitor rock mass movements around the runway and the corresponding response of supports as various mining activities are carried out in the neighborhood. We believe that such a program is a prerequisite to any remedial measure to alleviate pressure problem at Grace Mine.

Jan 1, 1973

By Joseph Perry

MAGNESITE is found in 22 California counties, but many of the deposits are too small or too impure to be of commercial value. Several of sub-stantial size and quality were entirely exhausted by wartime operation. At present, three properties comprise the only known workable deposits in the state. Of these, the Western mine and the Patterson mine have been known and worked for many years, and have been described in con-siderable detail in various publications, therefore need only brief mention here, because of their proximity to the Bald Eagle mine. The latter, recently developed, is unusual in type of ore deposit, plant design and operation, as well as products made, and very little has been written concerning it. WESTERN MINE The Western mine, 32 miles south of Livermore, Calif., was formerly operated by C. S. Maltby. It has been a consistent producer for many years.1 The ore is of amorphous variety, occurring along fracture zones in serpentine. The veins vary greatly in width, the average being perhaps 8 ft., with the maximum indicated in one early stope of 40 ft.; 2 ft. is considered the minimum for economical mining. The strike of the veins is predominantly north and south, with dip to the west varying from 40° to 75°. Walls are well defined and as a rule firm and easily supported, Veins range in length from a few hundred feet to 1000 or more. Their maximum vertical extent is about 350 ft., but many run less. Early mining consisted of open-cut and glory-hole work on the larger outcrops. This was followed underground by a modified shrinkage system, the waste and low-grade horses being removed by hand sorting on the tramming levels and transported to surface dumps. Filled-stope mining is used now, in order to eliminate the handling of waste, which has

Jan 1, 1938

By D Yan, D Connelly

Beneficiation of magnetite is an integral part of the future of iron ore processing. Historically, the focus of Western Australian producers has been on exporting direct shipping ore (DSO) namely haematite. The future for new DSO resources is limited so companies are changing their emphasis into processing the very large, undeveloped magnetite ores in Western Australia (WA), using beneficiation to produce shippable magnetite concentrates. These magnetite resources require higher cost processing techniques such as fine grinding and beneficiation to produce saleable concentrates. This distinct difference, from the DSO ores, has led to the development of a number of new technologies. This paper reviews: the different techniques used for magnetite beneficiation and provides some case studies in the WA industry; the use of mineral liberation analysis (MLA) to describe the nature, grain size, occurrence and associations of the mineralisation;the consideration of coarse cobbing as a critical upgrading; the application of high pressure grinding rolls (HPGR) to save energy; how the field of magnetic separation has resulted in new machines with higher field strength (SLon Separators); ultra fine grinding requirements of magnetite concentrates; andthe application of reverse flotation to reduce silica in the concentrates.

Jan 1, 2009

By Ian Orford, Peter Radziszewski, Lud Strah

"An autogenous grinding circuit was commissioned at the Brunswick concentrator in October 1998. The AG mill was subsequently converted to SAG operation in May 1999 for a number of reasons. The mill had 48 rows of the NORCAST top-hat integral lifter/liners configured in Hi-Lo mode. A charge motion simulation study, the results of which are the subject of this presentation, was initiated to develop a better understanding of SAG mill behaviour. Using a design of experiments approach, a lifter face angle was determined that would increase mill power draw. Once determined, lifter profiles were modified and installed in July 2001, and a second set installed in February 2002. Resulting changes in mill power consumption are presented.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is a large lead/zinc mine and began milling ore in 1964. The ore is massive sulphide with approximately 20% valuable minerals, 60% pyrite and 20% silicates. In October 1998, an autogenous grinding circuit was commissioned at the Brunswick concentrator (Cooper, Orford, Larsen, 2001).At the time, the autogenous grinding circuit replaced existing surface crushing plants, fine ore storage, rod mills and primary ball mills. The 8.54 m diameter x 4.27 m long (EGL) ANI mill was subsequently converted to SAG operation in May 1999.The mill had 48 rows of the NORCAST top-hat integral lifter/liners and was operated initially with all shell lifters at the same height. Following problems with packing and abnormal wear pattern, the profile was changed to a high-low configuration.Further, it was found that over the life of the lifters, mill power draw and throughput varied considerably. Although a change in mill power draw was expected following lifter replacement (predicted during mill design to be in the order of 300-400 kW), the replacement of the worn lifters with new high lifters resulted in mill power draw decreased by some 1000 kW."

Jan 1, 2003

By M. C. Ruiz

This work outlines the results of leaching studies on a copper concentrate containing chalcocite (Cu2S) and digenite (Cu9S5) with an acid saline solution of cupric chloride oxygenated at ambient pressure. The variables studied included the stirring speed, concentration of cupric ions, concentration of HCI, concentration of chloride ions, oxygen flow rate, temperature and time. The leaching system was found to be very effective for the dissolution of the concentrate. Over 95% of the copper was dissolved in 30 minutes with negligible dissolution of iron. The dissolution of copper increased with the stirring speed up to about 400 rpm and depended little on the total chloride concentration. The oxygen flow rate affected the dissolution of copper only below 0.1 1/min. The concentration of HC1 did not influence the dissolution providing its was sufficient to avoid the precipitation of copper oxychloride. The study of the effect of the temperature showed a maximum in copper dissolution around 90 "C

Jan 1, 1997

By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

Rutile ore is an important resource for the production of titanium products, and flotation is an efficient method to enrich rutile from its deposits. Motivated by strong commercial demand for titanium metal and alloys, substantial efforts have been made to improve the flotation efficiency of rutile. Styryl phosphonic acid (SPA) and salicyl hydroxamic acid (SHA) are commonly used as collectors for rutile flotation, and lead (Pb) ions can be used as activators for rutile flotation with SPA or SHA. Xanthates have a price advantage over SPA and SHA for the flotation of sulfides as SPA and SHA prices are higher than xanthate prices. In this work, we found that when rutile is activated by lead ions, amyl xanthate is an efficient collector for rutile flotation at pH 8. A slightly basic slurry can be readily obtained. Moreover, the price of amyl xanthate is lower than that of SPA or SHA. In this regard, this flotation strategy has the potential to be used in industry. Furthermore, the adsorption features of amyl xanthate on the Pb-activated rutile surface was investigated by experimental methods, which provides insight into the role of lead ions in rutile flotation.

By T. W. Camm

Aristotle made the observation that man is a political animal. Engineers often like to think they are above the fray when it comes to organizational politics, but most organizational theorists believe politics is a fundamental dynamic in any group. This paper examines the various ways that people use power within organizations to negotiate the political interactions in the work place.

Feb 27, 2013

By G. van Aswegen

The geometry and morphology of a set of low-angle fractures around a stope in a deep Witwatersrand gold mine are explained in terms of extension fractures forming under variable conditions of stress. Primary extension fractures (E1) form some distance ahead of an advancing stope along the s1, s2 plane. With stope advance, a couple of these fractures end up in a stress regime conducive to transpressional shear and a secondary set of extension fractures(E2) is formed at a high angle to the primary fractures. i.e. at a low angle to the stope. As the E2 fractures are undermined, they migrate into a stress regime of transtensional shear and a third set of extension fractures (E3) may develop between E2 fractures. These have sigmoidal shapes, being parallel to the E2 fractures at the E2 discontinuity where s3 is negative, and curved through the un-fractured rock between E2 fractures where s3 is positive at the instant of fracturing. The fractures all display fractographic features characteristic of dynamic extension failure with striae indicative of the direction of rupture propagation and the local, instantaneous orientation of s1.

Jan 1, 2012

By G. W. Poling, E. M. Coelho

"Sedimentary phosphate ores make up approximately 87% of the world's known reserves and are generally more difficult to beneficiate than igneous ores. In almost all cases, desliming prior to flotation represents the major source of losses. Laboratory studies of selective desliming of sedimentary ores are presented. Some fundamental studies with pure mineral systems are also discussed. Selective desliming, especially using selective flocculation, gave the best performance. Possible industrial applications of this selective flocculation-flotation procedure are discussed.IntroductionPhosphate ores are a major source of raw materials used in inorganic fertilizers (which supply nitrogen, phosphorus and potassium). Approximately 96% of the total world production of phosphate is utilized in the fertilizer industry. Reserves and production data are available in the literature. Today deposits with grades as low as 4% P2O5 are exploited in a few cases. However, in some northern African deposits, ore grades are still as high as 33 - 35% P2O5. Hout pointed out in 1982 that approximately 200 million tonnes of phosphate ore were upgraded by flotation only.Although there is a large number of phosphate minerals (over 300, only those in the apatite series are important ore minerals in phosphate ores. The most common member in this series is fluorapatite – Ca5(PO4)3F. However, in sedimentary phosphate rocks, many different substituents occur in the apatite lattice. Carbonate-fluorapatite (or francolite) is one of the most common names used to describe sedimentary apatites. It can be represented by the empirical formula:"

Jan 1, 1986

By L. M. Scovell

The Internet and its related technologies will radically change the way that mines manage and control their maintenance, repair, and operating supply chains. The Internet is creating new distribution channels and offers new technology platforms with significant advantages over more traditional methods. Mines will have to re-evaluate both the strategies and the tactics employed in these areas. Mines will use e-commerce to integrate their maintenance, repair, and operating supply chains. The integration will extend beyond traditional trading partners to a worldwide network of communities with similar interests and goals. The changes will transform the way mines operate, lower mining costs, and thereby increase their chances of success in an increasingly competitive environment.

Jan 1, 2000

By A Hekmat, M Fuentes, F Armijo, R Castro, F Rodriguez

Interpreting the behaviour of granular material and simulating the gravity flow are complex processes in cave mining methods. In this paper, a new Cellular Automata based code – FlowSim – is used as a flexible tool to simulate the gravity flow and subsidence zone in block caving mines. The simulation results of the gravity flow model in a real scaled mine as well as a scaled physical model are presented in this study. In this research, FlowSim was first calibrated at a mine, based on the information obtained from smart markers. These markers were located in five points of the second block of the Esmeralda sector, at the El Teniente copper mine, Codelco, Chile. The calibration was performed with the objective of reducing the discrepancy between the extraction zone defined by markers in the mine and FlowSim outputs. Regarding the mine data, FlowSim was calibrated with the minimum error of ten per cent between real and simulated results. Then, the calibrated FlowSim model was used to simulate the flow behaviour of a scaled physical model. This model was constructed in the Block Caving Laboratory of the University of Chile to scale down the same block of the Esmeralda sector with the scale of 1:200. The FlowSim outputs show that this software enables the simulation of the gravity flow of the scaled model with less than five per cent discrepancy in grade and dilution entry to the drawpoints. According to the obtained results, this paper recommends FlowSim as an appropriate tool which can improve the design of production level in block caving and can enhance the prediction of the subsidence zone and dilution entry.CITATION:Castro, R, Hekmat, A, Fuentes, M, Armijo, F and Rodriguez, F, 2016. FlowSim – a versatile flow simulation tool to quantify extraction and design alternatives for block caving, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 645–652 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By W. E. Horst

Flotation feed was hell constant for batch laboratory tests and continuous pilot and commercial plant tests on a spodumene ore to determine the relation.ship between flotation behavior and the size and type of flotation machine. Results. showed that additional retention time would be needed in the plant flotation circuit to duplicate laboratory or pilot plant performance when operating Dariables of the. plant flotation machines remained unchanged. During the past few years of operation at Kings Mountain, N. C., full-scale flotation has generally yielded poorer metallurgical results than those obtained in the laboratory or pilot plant. After 2 min in each size of Denver flotation machine in the spodumene rougher circuit, pilot recovery (41.7 pct) was almost three times that of the plant (13.6 pct) and about twice that of the laboratory (21.0 pct). Pilot and commercial plant data are based on continuous operation, and laboratory results on batch testing of rougher performance. The ore is a pegmatite containing spodumene, feldspar, quartz, mica, and amphibolite. Data were accumulated to evaluate the scale-up relationships between laboratory, pilot plant, and plant flotation cells. Flotation rate constants and dimensional analysis were used to define the relationship existing between flotation behavior and scale of operation. Measuring Flotation Rates: Efficiency of the rougher stage was measured by flotation rate, defined as the recovery that can be attained within a given time." • The problem of measuring flotation rates has been studied by many investigators, whose methods have varied. Published studies an flotation kinetics have been summarized recently by Gaudin.l When comparing flotation rates, it is more satisfactory to compare straight line relationships between recovery and flotation time than exponential curves resulting from plotting cumulative recovery vs cumulative flotation time. To convert the exponential curves into straight line relationships, rate equations were applied similar to those used in chemical kinetics to study the velocity of chemical reactions. Two rate equations have been used in this investigation to measure efficiency of the various cells: 1.5 order Rate Equation dR/dt=k (A-R)1.0 [Eq.1] Second Order Rate Equation dR ---- - K(A - R)2 [Eq. 2] dt Upon integration Eq. 1 becomes 1/(A-R)1/2=k/2 t+1/A1/2 [Eq. 3] and Eq 2 becomes: or fEq. 4] t/R=1/A2K+t/A [Eq. 4] where R = cumulative recovery [percent recovery of total value (spodumene) in flotation feed]. A = initial concentration, pct (100 pct of mineral to be separated). t = flotation time (minutes). k = flotation rate constant for 1.5 order rate equation [units: 1/(percent) 0.5 (min)1. K = flotation rate constant for second order rate equation [units: 1/(percent) (min) 1.

Jan 1, 1959