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By T. Nghipulile, G. Dzinomwa, J. Kurasha, M. Amwaama, B. Mapani, K. Maweja, T. E. Moongo

The effect of mineralogy on the grindability was investigated using three copper ores – two sulphides and one oxide. The dominant copper minerals were identified by optical microscopy and mineral chemistry derived from SEM-EDS analysis. The sample designated sulphide 1 was borniterich, sulphide 2 ore was mainly chalcopyrite, and the oxide ore was predominantly malachite and minor azurite. The gangue minerals were identified using semi-qualitative XRD analysis. Sulphide 1 contained more than 80% (w/w) of quartz compared to about 70% in the other two ores. The Bond work indices were 13.8, 21.6, and 17.3 kWh/t for sulphide 1, sulphide 2, and oxide ore respectively. This suggested that the chalcopyrite-rich ore is the hardest, while the malachite-rich ore has intermediate hardness, and the bornite-rich ore is the softest. The brittleness indices of the ores were calculated using the chemical composition of the gangue, and a good correlation between brittleness indices and Bond work indices was observed, which highlights the importance of the gangue composition in determining the fracture behaviour of the ores. There is scope for further investigation into the relationship between ore mineralogy and comminution behaviour using other breakage characterization techniques.

Mar 30, 2023

By Albert L. Toenges, Frank A. Jones

"INTRODUCTION The introduction of mechanized pining in coal mines, which has speeded loading, has emphasized the importance of efficient underground transportation systems. The purpose of this investigation is to study and analyze various systems now in use, and to derive conclusions therefrom. This report may be helpful to operators who are planning new systems of transportation or who are revising present systems to increase their efficiency. This paper is the first of a series on this subject and describes some systems of transportation utilizing rail haulage.ACKNOWLEDGMENTThe information used in preparing this report was obtained through the courtesy and cooperation of the officials of the companies whose mines wore studied. The descriptions of the transportation systems at the mines included herein have been checked for accuracy, and publication of the data has been approved by the executives of the several operating companies."

Jun 1, 1940

EDITORIAL comments on the anthracite report of the Federal Fact-finding Coal Commission, which became public on July 5, together with an analysis of its more important conclusions, will be found on another page of this issue. In this place, only a few extracts from the report, bearing more directly on technical matters, can be quoted, for lack of space. COST OF MINING Mining cost, as it stands on the books of each mining company, represents the average cost of the total output, all sizes, of anthracite. Egg coal has at least five times the market value of barley, but these' sizes are mined together and their costs can not be separated. Mine costs directly reflect the conditions under which these deposits of coal are recovered. Even within the few counties in which anthracite is found there is a conspicuous range of natural conditions. The distinc-tion between the Northern, Middle, and Southern field, or, as they are also termed, the Wyoming, Lehigh, and Schuykill regions, is primarily geologic and topo-graphic, but the effects of the natural conditions largely control costs. The contrast is great between Some of the level-lying beds of moderate but fairly constant thickness under the broad Wyoming Valley, where mining and underground haulage present relatively simple problems to the engineer, and the steeply pitching or overturned and faulted beds of variable thickness in the Schuykill field, where crushed coal' and treacherous roof multiply the difficulties of mining; and increase the unavoidable waste. Even more direct is the connection between geologic processes and the, differences in the character of the coal as mined, the varying proportions of large and small sizes demanding differences in preparation and resulting in different average prices realized for the product of the mines.

Jan 8, 1923

By David Wilshaw

Continuous Surface Wave (CSW) testing has been the “next big thing” in ground characterization for the last 25 years. The technique uses surface geophones to measure the speed at which Rayleigh waves (generated by a vibratory source) travel through the ground over a range of frequencies. The velocity at which surface waves travel through the ground is directly related to ground stiffness; the velocity of shorter wavelengths is influenced by the stiffness of shallower soil layers, while the velocity of longer wavelengths is influenced by the stiffness of deeper layers. Measuring the surface wave velocity over a range of frequencies, therefore, allows a stiffness / depth profile to be produced. Using the small-strain stiffness data measured by the CSW technique greatly improves the accuracy of simple limit state analyses; the data are also of sufficient quality for use in Finite Element modelling. Nonetheless, the technique has suffered from a perception of high cost, low productivity, and poor repeatability. An improved Advanced Continuous Surface Wave (ACSW) testing system has been developed by Ground Stiffness Surveys in the United Kingdom, has been deployed there commercially for several years, and is now available in the United States. ACSW uses an automated electronic control system that generates vibrations (from a purpose designed and manufactured portable seismic “shaker”) at different frequencies, measured across a 3m (10-foot) array of geophones, linked to a robust data acquisition and analysis software package. The range of applications in geologic and geotechnical site characterization includes rapid preliminary non-intrusive site assessments (utilizing published soil correlations); stiffness profiling to detect discrete layers (such as a variation in rockhead); average stiffness profiling for earthwork or ground improvement control testing, Working Platform stability assessments, foundation settlement analysis, rock quality and rippability assessments, and void detection.

Oct 1, 2022

By AIME AIME

THE Wednesday morning session was devoted entirely to the consideration of the tentative code for coal mine ventilation. A. W. Hesse is chairman of this subcommittee. E. A. Holbrook presided at the session and assisted by A. W. Hesse and George S. Rice, gave the historical background of the movement for a ventilation code. They stressed the point that this was to be an engineer's code, and that it was hoped that it might serve as a valuable guide to operating companies in securing greater efficiency as well as safety in ventilation. The discussion was continued into the afternoon session, and by adjournment the entire' code had been covered.' Many sections were referred back to the Committee for further study and several new sections were suggested. The various opinions and new ideas brought out during the discussion proved very valuable and. contributed much to the progress being made in the preparation of this code.

Jan 1, 1929

By Peter Richards, Alexander Lewis-Gray, Mark Davies, Nicholas Katsikaros

"Gekko Systems developed the Gekko Resin Exchange Column (G-REX) in order to optimise the recovery of gold in complex leach-to-electrowinning processes, as an intermediate step using a highly gold-selective resin to isolate contaminant metals. The AuRIX®100 resin produced by Purolite is licensed exclusively to Gekko, with the G-REX column designed specifically for this resin (Lewis-Gray et al, 2015). Operational experience has been gained at the CGT Ballarat Gold Plant in near continuous operation since 2008, treating unclarified concentrate leach solution. The extension of the technology to higher throughputs and more complex chemistry is discussed.Aurix®100 ResinAuRIX®100 resin is a cross-linked polystyrene alkaline resin developed by Henkel (Virnig et al, 1996). The resin beads are off-white in colour, spherical, with a nominal size of 100% +600µm. This resin is highly selective for gold and silver over many metals, by way of extracting precious metal cyanide complexes from leach solutions with a pH less than 11.5. The higher end of the pH scale produces best selectivity according to the order of preference: Au > Ag > Hg > Zn > Ni > Cu > Co > Fe. Purolite produces the resin and Gekko Systems maintains licensing of AuRIX®100 resin for use in its G-REX column as part of its unique suite of gravity gold handling equipment.Significant cost savings over carbon-in-solution (CIS) systems are realised with AURIX®100 resin, of around 4% to 12% in capital savings and 27% to 40% in operating costs (Virnig et al, 2004). Allied to this is that AuRIX®100 resin is not susceptible to fouling, that is, the resin does not load with inorganic salts or organic compounds which would affect the loading and extraction of precious metals. To counter any potential for fouling by inorganic salts, in service a dilute acid wash is carried out periodically on the resin to unblock resin pores."

Jan 1, 2016

Charles H. White, Harvard University, Cambridge, Mass, (communication to the Secretary*):—In answer to Mr. Jar-man's questions I am able to say that constant use (during term-time) since 1901 has shown the new appliances in our laboratory to be very satisfactory. The draft in the hoods is sufficient to lift the fumes promptly from the baths and hotplates ; and the occasional application of stove-polish,—usually about three times a year, at the recess-periods,—so well protects all iron-work in the hoods that, up to the present time, there is very little evidence of the corroding action of acid fumes. Iron should never be used in the construction of hoods above

Jan 1, 1906

By Albert L. Toenges, Louis A. Turnbull, Henry E. Dekay, James N. Scudder

A preliminary survey of coke and steel plants conducted by the Bureau of Mines in cooperation with the Office of Solid Fuels Coordinator and under the auspices of the Coke Production Committee indicated that a very appreciable increase in pig-iron production would be obtained if pres- ent blast furnaces were supplied with a more uniform coke. Control of the sulfur and ash content of coal used for making coke is an important factor in producing uniform coke and thus increasing blast- furnace efficiency. In some mines producing metallurgical coal, the analysis of the coal bed shows a wide range of sulfur and ash content. To obtain production of coal with minimum deviation in sulfur content sampling, grading, selective mining, blending, and surface preparation are practiced at some mines with satisfactory results. The mines selected for this study have developed these methods and are successfully producing coal of uniform sulfur and ash content. The systems employed at different mines vary according to the physical character- istics of the coal bed, the manner of occurrence of impuritites in the coal, the development plan and mining system, surface preparation and the acceptable impurity content of the prepared coal. The ash content of the coal can be controlled by face preparation and in the cleaning plant. The introduction of some method or practice at other mines might make possible the use of coal for inetallurgical purposes that otherwise could not be used for making coke because of the wide variation of sulfur and ash content.

Dec 1, 1943

By B. E. Eakin, A. L. Lee, M. H. Gonzalez

Expeximental viscosity and density data of lour natural gases are presented for temperatures from WO to 340F and pressures from 100 to 8.000 psia. A correlation is also discussed and results reported. INTRODUCTION This investigation is one of several efforts by the authors to provide viscosity data for pure hydrocarbons and mixtures. Results of some pure hydrocarbons and their mix tures have been presented." Several predictive methods and correlations have also been reported.'," This paper presents the experimental viscosity and density data of four natural gases and confirms a correlation in a previous study. APPARATUS The viscometer was described previously. 2,6 A bank of stainless steel pycnometers was included to determine density in conjunction with the viscosity measurements (Fig. I). DATA AND MATERIALS The natural gases were furnished by the Atlantic Richfield Co. (Samples 1 and 21, the Continental Oil Co. (Sample 3) and the Pan American Petroleum Corp. (Sample 4). Table 1 shows the composition of these gases obtained by mass spectrometer analysis. The pure component viscosity data used in the correlation have been published."".'"', '" Experimental and calculated viscosity data for the natural gases are presented in Tables 2 through 5. CORRELATION Starling and Ellington"' have reported several semi-empirical expressions based to a certain extent on the theory of viscosity advanced by Born and Green.' The final expression presented by Starling and Ellingto'n is: i'. (micropoise) -- /t,, exp rX(7') p ..... (I) Eq. 1 was modified by Lee et 01." to represent mixture and pure component data simultaneously. This equation has the form: F = K exp [XpY] :.........(2) where K=- (7.77 i 0.0063M)Ti 122.4 + 12.9M +T .................(3) ' ' ' X= 2.57 + ---1914.5+ 0.0095M .... (4) Y = 1.11 -r 0.04 X ........(5) Over the pressure and temperature range studied in this investigation, this equation represents the data on methane, ethane, propane, n-butane and four methane-n-butane mixtures with a standard deviation* of ? 1.89 per cent. Density data by Sage and Lacey" were used to fit the equations. Eq. 2 gives reliable values of the viscosity of light hydrocarbons without prior knowledge of experimental viscosity values, but accurate density data must be available. Eq. 2 was used to predict viscosity values for the natural gases studied in this paper. The particular set of parameters contained in Eqs. 3 through 5 gave values that reproduced experimental data within 25 per cent. Needless to say, in using Eq. 2 better density values will give better viscosity results. However, those engineers who do not have accurate density values at hand or the time, or such facilities as a library, computer, etc. readily available, may feel uneasy in using Eq. 2. Therefore, the authors sought the easiest but by no means best density prediction method, which was reported by Kaf 30 years ago. A set of density values, which were calculated based on Kay's method, and a generalized compressibility factor chart were used to fit Eq. 2. The results are:

Jan 1, 1967

By J. R. Boyle

The Bureau of Mines developed cost estimates fur the disposal of phosphate rock washer slimes by pond settling, from a study of the method used at the International Minerals a Chemical Corp., Moralyn Phosphate Operations, Polk County, Fla. Data were obtained by basing phosphate production and slime generation statistics on plant capacity rather than on actual company records. Cost estimates, which were prepared as a guide in evaluating alternative disposal methods and in identifying needed areas of research, could be applicable to any Florida plant using the same disposal method. To conserve mineral resources and to improve environmental conditions, the Bureau recommends further research directed toward developing alternative methods of disposal, including the recovery of water and P205 values from the slimes.

Jan 1, 1969

The reported values of the standard reduction potentials of the Au(NH3)2+/Au(0) and Au(S2O3)23-/Au(0) couples are reviewed to emphasise the experimental difficulties associated with the measurement of reliable values for these quantities. The standard reduction potential for Ag(I)/Ag(0) in ammonia and thiosulphate solutions measured at ionic strength 0.1 and 25oCis used to predict the following relevant stability constants () for gold complexes based on the linear free energy correlations: Au(NH3)2+2 = 1013, Au(S2O3)23-2 = 1024 and Au(NH3)43+4 = 1033. The equilibrium constant ( 10-11) for the reaction Au(S2O3)23- + 2NH3 = Au(NH3)2+ + 2S2O32- based on these stability constants is in reasonable agreement with the measured value (10-9) based on potentiometric and spectroscopic data when excess ammonia was added to a solution of Na3Au(S2O3)2. This also indicates that the stability constant of Au(NH3)2+ is 9 to11 orders of magnitude less than that of Au(S2O3)23-. Relevant species distribution and Eh-pH diagrams based on the revised data are presented.

Jan 1, 2003

By R-H Yoon

The MicrocelTM column flotation technology has been developed based on the fundamental understanding that the first-order flotation rate constant increases approximately as the inverse cube of bubble size. In this technology, bubbles in the range of 100-400 pm are generated by pumping aerated slurry through an in-line static mixer. The high-shear agitation provided by the in-line mixer produces small air bubbles without requiring large frother additions. This column has been tested successfully for processing a variety of non-metallic minerals including kaolin clay, graphite, phosphate, and feldspar.

Jan 1, 1993

By Özcan Y. Gülsoy

Coal beneficiation with optical sorting has not yet been studied in detail. Optical separation of coal from gangue particles as a dry method can be used as an alternative to the other enrichment methods. Developments in optical and pneumatic technology put the optical sorting one step forward by means of applicability of the mechanical sorting to the mineral industry. Because of the inefficient separation performance, dry separation of coal is very limited in industrial applications. Therefore, optical sorting depending on color differences between two minerals can be introduced to coal beneficiation systems. In this study, coal samples obtained from Konya-Ilgin region (Central Anatolia-Turkey) were separated by optical sorter and the results were evaluated. The conventional floatability tests for Ilgin coal are conducted by collecting most of the feed material at 1.3-1.4 g/cm3 density range. Separation of Ilgin coals with heavy medium methods will not be possible because of poor density difference between coal and its impurities. There are important color differences among the floated particles at 1.3-1.4 g/cm3 density range. Therefore, Ilgin coal is subjected to optical sorting in a pilot scale optical sorter. Different size fractions were fed to the optical sorter and then rejected and accepted particles by equipment were analyzed. Ash content of the accepted particles was reduced to 25-35 % and ash in tail increases up to 55-60 % after sorting. Although most of the material floated at low densities, optical sorter separated the feed into two different quality products. This study has the potential to clarify applicability of optical sorting even to non-floatable coals and to provide an important contribution to both industrial applications and literature.

Sep 1, 2012

By Canterford J. H, Sparrow G. J, Dyson N. F

Pressure leaching of a bulk flotation concentrate prepared from a complex Cu-Pb-Zn sulphide ore was carried out at 150 and 190¦C under 1050 kPa oxygen overpressure in 1 L and 4 L titanium autoclaves to extract zinc, and to obtain residues for smelting tests and leach liquors for purification and recovery of the zinc by electrowinning. Dissolution of 95% of the zinc was achieved at both temperatures. Copper and iron dissolution and the degree of oxidation of the sulphide sulphur to elemental sulphur or sulphate depended on the temperature of the leach. At 190¦C, a jarosite (a basic iron sulphate) was the major iron-containing material in a residue that contained 17% total sulphur. Its formation was associated with dissolution of 18% of the iron. At 150¦C, oxidation of the sulphide sulphur and dissolution of the iron were significantly less. Only 7% of the iron was dissolved and a residue containing 25% total sulphur, present as a lead jarosite, lead sulphate, and elemental sulphur, was obtained. The formation of small pellets of unreacted sulphides coated with elemental sulphur caused problems during the leaching at 150¦C, and also during scale-up from the 1 L to the 4 L autoclave at 190¦C. At 150¦C the concentrate required two stages of leaching to achieve dissolution of over 90% of the zinc. These problems are discussed.

Jan 1, 1989

By B. M. Larsen, T. E. Brower

INTRODUCTION AND SUMMARY BY "thermochemical factors" we refer to those variables which affect the net heat which must be put into the bath in order to make a heat of steel from any given set of charge materials. This is admittedly only one phase of the production rate problem. The whole problem includes also consideration of rate of charging, flame radiation intensity, rate of optimum fuel input obtainable without undue damage to the furnace structure and any variations in conditions such as stirring, slag volume or viscosity which affect the rate at which heat can flow down and away from those exposed surfaces where the heat is first received from the flame. Because a given type of charge in a shop is often considered as being nearly constant in both physical and chemical characteristics from one heat to another, and because such a state of affairs may be thought of as resulting in a reasonably constant net heat requirement, this requirement is usually neglected as an invariable, inevitable matter, about which nothing can be done. With normally variable charge, and variable percentages of limestone and cold pig, however, the net heat requirement can be subject to very appreciable change; it may also be affected by such things as the currently popular procedure of blowing oxygen into the bath, To bring the general problem of production rate into better perspective, therefore, it seems worthwhile to try to evaluate the net bath heat requirement and the amount by which it may change through variation in different factors. Because our calculated values of net heat are admittedly uncertain, we have tried to check them in part by statistical data on actual production rates over rather large groups of commercial heats. The results of calculation of net heat requirements in a wide range of actual commercial practices may first be summarized briefly. We find a wide range between the extremes of different practices, as would be expected, with duplex practice (essentially blown metal plus hot metal) having essentially a zero net heat requirement, an all-cold charge practice somewhat over 1 million Btu per ton of steel and a high hot metal practice about 0.75 million Btu per ton. Over the commercial range of scrap plus hot metal practice, increasing the percentage of hot metal from 40 to 78 pct, with other factors nearly constant, decreased the net heat by only some 5-10 pct, The net heat is increased by about 1.2 pct for each I pct of the metallic charge present as cold pig. Calculated values of oxygen supplied by air varied from about 25 up to 60 lb per ton of steel, and in a 60 pct hot metal practice, an increase from 32 to 52 lb oxygen from air decreased the calculated net heat from 0.88 to 0.74 million Btu per ton. Use of pure cold oxygen to substitute for about one half of the total charge ore (about 28 lb oxygen replacing 145 lb ore per ton of steel) decreased the

Jan 1, 1948

By Lysle E. Shaffer

TEACHING engineering students how to write and speak effectively -is one of the greatest problems facing the technical schools today. No phase of engineering education has received more criticism, and rightly so, for the criticism is justified. Year after year we continue to graduate men that are indifferent to the use of a tool they will need every day of their lives. Our young engineers cannot write a clear, concise report, and their business letters are a disgrace to the profession that takes pride in precision. The problem is not new. The remark ascribed to Sir James Barrie, that "The man of science appears to be the only man who has something to say, just now-and the only man who does not know how to say it" is as uncomfortably true today as it was thirty years ago. The records of meetings of engineering educators and the transactions of the engineering societies show that the inability of the engineer to communicate his ideas has been discussed for years. Engineering educators, prodded by industry, have recognized that the problem exists, but they have not solved it. Instead they continue to expose the student to composition and rhetoric, hustle him through English and American literature, and then blame his high school because he does not know enough English grammar to write a clear sentence. We must face the fact that the graduate is not going to reflect on the high school, but on his college. If the high school has shirked the job, the responsibility for correction rests on the faculty of the professional school.

Jan 1, 1948

By E. Allain

Extraction of basic metals from sulfides by conventional pyrometallurgical processing leads to the emission of SO2. To avoid this inconvenient, low temperature selective chlorination of sulfide concentrates could be an alternative. However, such process generates hazardous chlorides SxCly. A part of sulfur chlorides such as SCI2 can be recycled as a chlorinating agent of metal sulfides. Hydrolysis of sulfur chlorides, using a solution containing Na2S.9H2O, led to the recovery of more than 90 pct of elemental sulfur. Reduction of SxCly by hydrogen was investigated between 300 °C and 800 °C. About 70 and 90 pct of elemental sulfur were recovered from SC12 and S2C12, respectively. A flow sheet for the chlorination of metal sulfides and the treatment of sulfur chlorides was suggested.

Jan 1, 1998

By Ken Sublette

The mining industry has been a leader in the application of ultrasonic level monitoring systems, utilizing the "sonar-in-air" concept for the accurate inventorying of material not only as an end within itself, but going on to activate alarms, turn off feeders, operate tripper systems, and totalize the inventory in numerous bins as well as other more sophisticated applications. The virtues of ultrasonic level monitoring are no doubt appreciated by most users. However, to be of maximum service to the expanding mining industry, the manufacturer must be fair in pointing out ultrasonic's limitations as well as its virtues. The limitations can be surmounted with new technology and through a proper understanding of the principles of operation and application.

Jan 6, 1974

By AIME AIME

IN RESPONSE to a request from the president- elect of the Institution of Civil Engineers of Great Britain, Mr. Calvin W. Rice, secretary of the American Society of Mechanical Engineers, prepared a brief history of the joint activities of engineering societies in the United States, from which we have taken the following facts. National Societies Our first joint activities were in collection with the celebration of the eightieth birthday of "Uncle John" Fritz in 1902, and it is of interest to note that two of the members of the original celebration committee, Messrk. . Ambrose Swasey and Jesse Merrick Smith, will be members of the official deputation to England in June. Mr. Rice, also,' was .a member, of the original committee.

Jan 1, 1921

By I Ametov, S Harmer, R Alford

A process that allows selective flotation separation of low Cu/S ratio minerals (chalcopyrite and pyrite) from high Cu/S ratio minerals (bornite and chalcocite) from a mixed copper mineral concentrate under controlled oxidative-reductive potential conditions has been developed. The process has been extensively tested on samples with varying mineralogy using laboratory batch flotation tests and mini pilot plant trials.In this process, the mixed final copper mineral concentrate is purged with nitrogen, and then treated with sodium dithionite to achieve a slurry Eh in the -200 to -100 mV standard hydrogen electrode (SHE) range. Flotation was then carried out using nitrogen gas. As a result, a low Cu/S ratio concentrate (<1.3) and a high Cu/S ratio (>1.6) tailing stream were produced. QEMSCAN analysis of the flotation products showed that more than 85 per cent of the chalcopyrite and 95 per cent of the pyrite reported to the froth concentrate. Chalcocite and bornite were almost evenly distributed between the concentrate and tailing streams.Surface analysis studies, focused on the mechanism of separation, showed that at a negative redox potential xanthate and possibly dixanthogen are the dominant hydrophobic species on the surface of chalcopyrite and pyrite. As a result, the flotation of these minerals remained unaffected. In contrast, a much lower concentration of xanthate species on the surface of chalcocite and bornite particles was observed. Therefore, it is likely that at low Eh the copper xanthate complex desorbs from the chalcocite and bornite surfaces, causing a decrease in surface hydrophobicity and the diminished floatability of chalcocite and bornite.CITATION:Ametov, I, Harmer, S, Grano, S and Alford, R, 2014. Selective flotation of chalcopyrite and pyrite from a mixed copper mineral concentrate under controlled redox potential conditions, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 131–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014