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Continuous, steady-state laboratory flotation tests showed that the recovery of cha1copyrite from a naturally occurring ore, under conditions closely resembling those of plant practice, could be expressed in terms of a first order rate equation.Tests on full-scale plant flotation cells, using impulse tracers, indicated ideal mixing of the pulp in the cells.It was demonstrated that values of first order flotation rate constants can onlv be obtained from conventional methods of analysis in special cases.Analysis of a plant sampling campaign by the author supported a first order kinetic equation for two mineral species, and for the individual size fractions of one of these.The effect of stage-addition of reagents is interpreted in kinetic terms.

Jan 1, 1966

By J. L. Wilson

"Many modern concentrators with VSD driven SAG mills still rely on the control room operator to manually adjust the speed in reaction to increasing bearing pressure. All too often, the problem with this strategy is by the time the operator reacts with a sudden speed increase, the SAG Mill is likely already on its way to loading up. To assist the new operators, the SAG Mill at B2Gold’s Fekola Mine in Mali needed a robust control that could handle load changes and unmeasured disturbances with minimal operator intervention. With modern Distributed Control Systems (DCS) powerful enough to run advanced control, they often have Model Predictive Control (MPC) blocks built in or available as an “add-on” license, and thus MPC can be readily implemented within the modern concentrator with a relatively low added capital cost. This paper discusses an implementation of two single output MPC controllers to control the SAG Mill at Fekola. This was implemented using the existing signals and advanced control blocks available to the installed DCS.INTRODUCTION Many modern concentrators with VSD driven SAG mills still rely on the control room operator to manually adjust the speed in reaction to increasing bearing pressure. All too often, the problem with this strategy is that by the time the operator reacts with a sudden speed increase, the SAG Mill is likely already on its way to loading up. The next step the operator may take may be to cut back the feed rate, or production until the SAG is once again stable. With this sudden reaction comes an abrupt change in SAG rotational speed and power consumption that sends a surge of material down the circuit as the mill suddenly ejects more pulp. Furthermore, choosing a higher rotational speed can lead to higher than normal liner wear as the cataract overshoots the toe of the charge and impacts the liners. After start-up at B2Gold’s Fekola Gold Mine in 2017, the SAG mill was being controlled manually. The SAG rotational speed was adjusted manually by the operator in step changes depending on whether the SAG bearing pressure was increasing, decreasing or stable. During this time of manual control, the SAG fresh feed rate was also adjusted to a tonnage setpoint with a PID controller. Generally, the SAG fresh feed rate setpoint was kept at a target value, but then the feed rate was throttled back if the SAG mill or grinding circuit showed signs of overloading. The extra challenges were that the operators had limited experience and were concurrently learning how the plant operated. Also, they were also occupied with managing situations in the rest of the plant. Often their attention was drawn away from the SAG mill and during that time, the SAG Mill would load up before they could react."

Jan 1, 2019

By Arthur F. TQggQrt

THE approximate status of education in ore dressing in 1871 is reflected by Rossiter W. Raymond in an article written at that time presenting the curricula and descriptions of the laboratories at the various mining schools in the United States. For the most part, the curricula in which ore dressing was taught were for mining engineering. They comprised courses in geology, mining, and pyrometallurgy about equal in point or credit weights; a short course in ore dressing, and a somewhat longer course in assaying; and courses in surveying, hydraulics, power, and strength of materials-all superimposed on a broad foundation of physics, chemistry, and mathematics. Some curricula contained a fair content of the humanities. Then, as now, the emphasis on fundamentals was greater in the older colleges and universities. The report on the Columbia School of Mines, then relatively young, emphasized that a large percentage of its students were college graduates. As technical and scientific knowledge grew, first metallurgy and then geology were set up as separate curricula. So far as curriculum designation is con-

Jan 1, 1947

By A. B. Young

THERE were produced in this country in 1923 probably in the neighborhood of 12,000 or 13,000 tons of refined and crude arsenic, by far the greater portion coming as a by product of smelting operations. Early this year copper smelters were producing arsenic at the rate of about 425 tons per month and lead smelters at the rate of 7;0 tons per month. During the entire eighteen years prior to 1919, there were produced in the United States only 47,000 tons of arsenic, which amounts to only 25 per cent. of the present output. The great increased demand has come about through the augmented use of arsenates as insecticides and arsenates as weed killers. In an extract from "Mineral Resources of the United States" on "Arsenic in 1922," Messrs. Heikes and Loughlin say, "The minimum possible demand for arsenic in 1923 was estimated at the end of 1922 to be about 13,000 tons, including 2000 tons for plate glass manufacturers, 3000 tons for lead arsenate, 3500 tons for calcium arsenate, 1500 tons for weed killers, 1200 tons for Paris green, 1000 tons for sheep dips and 750 tons for proprietary mixtures. More recent information, however, indicates twice as great a demand for calcium arsenate." The latter has found great use in the last three or four years as a weapon to combat the boll weevil pest of the southern cotton belt. ~t the present writing refined white arsenic is being quoted on the New York market at from 13)d c. to 1455 c. per Ib., while the average price during the eighteen-year period just mentioned was 4.8 c.

Jan 1, 1924

By J. Blodget Britton

IN the Journal of the Franklin Institute for May, 1870, there is published a description of a Colorimeter, together with a modification of the method proposed by Professor Eggertz, for determining combined carbon in iron and steel. An instrument of the kind there described, but of a little higher range, though in other respects not differing materially from the one originally made and used in the Iron-Masters' Laboratory, I now submit to your inspection ; and I propose, also, to make some determinations with it for the purpose of showing how quickly they may be made, and enabling you to form some judgment of what reliance can be placed in the results. Professor Eggertz proposed only a single standard, and the solution to be tested should be diluted to exactly correspond in color with that of the standard, and the per cent. of carbon calculated after carefully noting and making allowance for the measures of water used in diluting. In practice, difficulty was found in bringing the color of the normal solution down to the exact shade of the standard ; also other difficulties were met with in conducting the process, causing delay and interfering with the accuracy of the results. To materially overcome these, and after numerous attempts, an instrument such as is now before you suggested itself to me; and also I concluded to use a larger quantity of metal than directed by Eggertz, and, in addition, to filter the solution from its insoluble matter before making the comparison ; and, more recently, to use an acid of just such strength as would completely dissolve the metal without the application of heat. Experimenting with these changes from the original method I obtained reasonably good results. The instrument, you will observe, consists of a series of tubes, sixteen in number, two and a half inches long, and about half an inch in diameter, standing upright, and securely fastened in a light, portable, walnut-wood frame, but separated one from the other so as to allow just sufficient space between to place for comparison the tube containing the solution to be tested. The tubes are filled with

Jan 1, 1873

By C. L. Workman-Davies

Noise is a form of pollution arising mainly from the activities of man. One such activity is mining, in which man, as in many of his other activities, uses machinery of various kinds to achieve safe, healthy, and economic production. Trackless mining makes use of an advanced state of technology over that required In traditional mining methods. One of the advantages of the former, as distinct from any disadvantages it may have, is a reduction in noise levels, the number of people exposed to noise, and the duration of their exposure to noise. This paper briefly examines why noise is a problem and what various countries are doing about it in terms of standards, codes of practice, and regulations. It also investigates the extent to which noise is a problem in mining and how trackless mining alleviates this problem. The question is then posed as to whether South Africa is not setting too high a standard at this stage of its national development by comparison with what is being done by other, more-advanced countries.

Jan 1, 1989

By H. Colijn

Feeders are used to provide a means of control for the withdrawal of bulk materials from storage units, such as bins, bunkers, silos and hoppers. This control function can only be performed properly as long as the bulk materials flow by gravity to the feeder in a uniform and uninterrupted fashion. A feeder can do many things, but it should never be considered a suction pump: During the past few years various papers have been written and presented on feeders and their application. 1,2,3,4,5,6,7,8,9)* It is not the intent of this paper to cover the same ground, and the readers are therefore ad¬vised to consult the referenced publications for supplementary information. This paper will be confined to some specific design criteria of bin feeders, such as feeder load and power requirements. Special attention is given to the basic design criteria of vibratory feeders.

Jan 1, 1968

By P J. Harris, C T. OÆConnor

Collectors are used to impart hydrophobicity on particles thus increasing their chances of reporting to the froth phase. Also, the extent to which naturally hydrophobic gangue particles, such as talcaceous minerals, report to the froth can be reduced by the use of depressants. Thus the use of collectors and depressants will directly influence the extent to which hydrophobic particles report to the froth. However these hydrophobic particles will also have a direct effect on the characteristics of the froth phase, more strongly hydrophobic particles causing a reduction in the stability of the froth with the expected concomitant effects on grade and recovery. This study included microflotation (ie frothless flotation) and batch flotation of various ores using a number of different collectors and depressants and a newly developed froth imaging device (SmartfrothTM). Flotation performance was characterised by mass and water recovery, and recoveries and grades of the valuables. This paper shows how the various reagents influenced the behaviour of the pulp and froth phases. The critical importance of managing the type and dosage of reagents used in flotation with a view to optimising their influence on the froth phase is discussed.

Jan 1, 2005

By F. W. Bradley

GOLD is a large subject. One could talk about its geological or mineralogical occurrences, prospect- i11.g for it, mining of .it, its metallurgy or its marketing; but I have decided to limit my discussion to gold as a business-that is, to its production and marketing. In the production of gold, it is necessary to consider the many possible sources, the quantities available, the capital and operating costs and the chances of price-breaking competition. So in the following remarks I shall endeavour to point out that though gold is found in every formation constituting the earth's crust, though it is possible to-find it free in great concentrated placer deposits on the surface, though there are still large unprospected areas of both the surface and the crust, though it may be possible to produce it by the cheapest labor on earth, and by processes not as yet developed, it still has an unlimited market at a definite price. There is no reasonable fear of disturbance by the finding of bountiful deposits, or by cheapening the cost of production due to devaluation, or by the development of any easy processes for direct, or for by product, production.

Jan 1, 1932

By Osvaldo Guilherme Comineli

While the hot cracking of Cu-containing steels is a serious and widely known problem for the industry, the literature reports that copper only slightly impairs the hot-ductility measured in laboratory. A distinction is drawn between hot ductility and hot shortness and the respective cracking operating mechanism involved at the respective range of temperature. The representability of the laboratory assessment of hot cracking of Cu-containing steels by hot tensile tests compared with actual results in industrial practice is discussed. The effectiveness of the variable affecting in each cracking mechanism and respective temperature range, focused in improving the hot cracking assessment of Cu-steels and the relative importance of oxidation will also be discussed. It is concluded that the hot tensile test in argon might be a good simulation if properly interpreted and that the role of oxidation is secondary in causing hot shortness. A schematic diagram for the hot tensile test is proposed.

Oct 30, 2017

By Zheng Wei, Jian Cheni, Zhenliang Weng, Wei Liang, Hongbo Zhu, Jinhui Peng, Linqing Dai, Qianxu Ye

"By testing the dielectric constant and the dielectric loss factor of concentrated Dahongshan, mill scale, anthracite and light-burned dolomite in different frequency and temperature, and by studying the temperature-rising characteristics of the materials in the microwave field of 2.45GHz in frequency, the research in the paper shows that to reach at 1250°C under the same condition -2KW the microwave power and 30g the mass --the time concentrated Dahongshan takes is 330s, whereas the millscale is 855s and the anthracite is 820s. About the last one, the higher the temperature is, the stronger the absorptivity is. After the temperature has rose to 400°C, the anthracite's absorptivity increases dramatically. The result of the research would serve as the foundation of the further study on making direct reduced iron by microwave heating.1. IntroductionUnder the microwave fields, materials' dissipation of dielectric bodies would generate thermal effect. Therefore, the dielectric constant and the dielectric loss factor are closely related to materials' ability of absorbing microwave energy-the larger the dielectric constant and the dielectric loss factor are, the stronger the material's ability of absorbing microwave energy is, and the better the thermal effect would be[1-2]. In order to research how to make reduced iron from iron ore fines by microwave heating deeply and systematically, the test of raw materials' dielectric constants and dielectric loss factors are of the essence. What's more, because a mineral' conductivity is influenced by its components and crystal structure[3], it is necessary to study different materials' different temperature-rising characteristics; hence such studies would provide theoretical foundation of further research."

Jan 1, 2012

Paper presented at the Mining Institute of Scotland's annual general meeting held in Glasgow, 8th April 1916. Although there is nothing novel or difficult about the sinking described, circular shafts are not numerous in Scotland so the details connected with such a sinking may be of interest. The shaft was sunk at Dykehead Colliery, Larkhall, which has been worked for over 50 years from the upper seams. It became necessary to sink another shaft to serve as a replacement downcast, by which the output might be maintained and some of the lower seams won. As the sandy clays regularly caused bulging into the rectangular shaft and sinking of the surrounding ground it was decided to make the new shaft circular and to enclose its mouth in a foundation-block of concrete resting on the solid clay. Details are given of the sinking, brick seating and lining, kettle strike, water-rings and doorhead lintels as well as the permanent fittings, winding gear and the cages themselves

Dec 1, 1916

By Walter R. Hibbard

Precipitation in the northeastern United States, Florida, California and in many industrialized areas of the world is now more acidic (lower pH) than can be accounted for by natural causes. At the same time, the acidity of many lakes and streams in the northeastern United States has been measured and found to be similar to that of actual rain. These facts have led to conclusions that the two conditions are related. Coal burning utilities, 700 to 1000 miles upwind, have been accused of being the cause, leading to proposals for strict emission controls on the alleged offenders. The costs of these controls would place an estimated $10 to $15 billion capital burden on utility customers in about 15 states plus $2 to $6 billion annual operating costs. There appears to be no direct well-established scientific evidence that the accused are guilty but that the indictment is based largely on circumstantia1 evidence. This study examines the evidence, describes the situation and proposes what must be done to reduce the acid precipitation in an orderly cost beneficial manner. It is interesting to observe that studies by the different adversaries on the acid precipitation issue come to different conclusions largely because they do not read the same literature, but selectively develop evidence to support their own points of view, This study will try to review the issues impartially and reach a position of scholarly balance.

Jan 1, 1982

By J Taylor, L Richards, M McKenzie

When a collapse in its services shaft caused rapid gas build up and its premature closure in. 1951, the Blackwater Mine at Wiauta was in full production with significant ore reserves yet to be mined. A total of nearly 23 tonnes of gold was produced from the mine during its 44 year life. It was New ZealandÆs deepest underground mine, producing gold from an extensive sub-vertical mineralised quartz reef that averaged 0.6 m in width. Mining was by stoping between adits and short shafts, latterly with the main mine access through the 840 m deep Prohibition shaft. Macraes Mining Company Ltd are presently investigating the possibility of reopening the mine. This paper outlines a preliminary assessment of the main geotechnical factors for achieving the reopening, using recent exploration and old mine information. The greywacke host rock mass in the vicinity of the quartz reef has been evaluated using both these sources, and the paper discusses how the geological structure, intact and rock mass strengths, the rock mass defects, in situ stresses, and groundwater inflows may effect the reopening and support of the prohibition shaft, the excavation methods and support for a new supplementary shaft, and the likely excavation and support requirements for working adits and stopes in the rejuvenated mine.

Jan 1, 1996

By David Montgomery

The feasibility of building a calibrator for the DuPont D-100 audio dosimeter is discussed. The desired specifications are used as guidelines but the possibility of their relaxation is also considered. Commercially available equipment is surveyed and found to not satisfy the guidelines. Several alternate concepts are investigated, and recommendations for further work are presented.

Jan 1, 1974

By Peter N. Yanker

The two types of dryers used in the drying of copper concentrates are the rotary dryer and the spray dryer. The rotary dryer has until recent history been the traditional drying method used, Although spray dryers have been used in the chemical field for many years it is only recently that they have been accepted for drying of copper concentrates. The comparison made here will apply in a narrower sense to the drying of copper concentrates as fed into the reverbatory furnaces of the Smelter. To compare a rotary dryer and a spray dryer, which are two totally different methods and pieces of equipment, it is best to view them as systems each made up of certain elements

Jan 1, 1976

By George F. Learning

TOTAL DIRECT IMPACT The uranium mining industry's principal economic impacts on the Texas economy are the result of three flows of money from the industry into the remainder of the state's economy. These three are: (1) money paid to individuals (personal income) ; (2) money paid to other businesses (business income); and (3) money paid to state and local governments (government revenues). As these direct payments from the uranium industry to various other sectors of the Texas economy subsequently circulate and recirculate within the state, the indirect effects of uranium mining's direct impacts multiply to reach amounts significantly higher than the direct income flows alone. Over the past decade, the uranium mining industry has substantially increased its role as a provider of jobs, personal income, business income, and government revenues in Texas. The growth has come almost exclusively in a largely rural, seven-county area that lies within the triangle formed by the Laredo, San Antonio, and Corpus Christi metropolitan areas. The uranium mining industry, in fact, has been the major dynamic element in this rural area despite relative stagnation in most of the region's other basic economic sectors. Over the three years from 1976 to 1978, the South Texas uranium mining industry directly contributed a total of $115 million to the economy of the seven- county region in which it operated and $164 million to the economy of the entire state of Texas. In 1979 alone, the total direct contribution of the industry to the Texas economy had climbed to $124 million in personal, business, and government income. PERSONAL INCOME IMPACT In the period from 1976 through 1978, the South Texas uranium mining industry provided an average of $12.5 million in personal income each year directly to residents of Atascosa, Bee, Duval , Karnes, Live Oak, McMullen, and Webb counties -- the seven Texas' counties that make up the South Texas Uranium Belt. A1 though 84 percent of this resulted from the employment of area residents in uranium industry jobs, some amounts were also provided by the payment of rents and royalties to land owners for the use of their land and mineral rights in uranium mining operations. In 1979, the uranium industry provided approximately $38 million to residents of the Uranium Belt and the rest of Texas. This was more than double the average of $16.1 million provided to Texas residents during the 1976 to 1978 period. The full importance of the uranium industry as a source of personal income, however, should not be reckoned merely by the amount of wages and salaries that it pays directly to its own employees, nor by its rent and royalty payments paid directly to land and mineral rights owners living in Texas. The added payments that the industry makes directly to other Texas businesses and state and local governments in Texas are themselves converted into personal income as those business firms and government units in turn pay their employees. All of the direct income payments made by the uranium industry circulate and recirculate within the state's economy, multiplying their impact as they go, until they eventually all leak out of the state as federal taxes or as payments to individuals or businesses located outside of Texas. The combined circulation and recirculation of the direct personal, business, and government income that was provided by the-uranium industry in Texas during 1976, 1977, and 1978 resulted in an average annual amount of indirect personal income of more than $83 mill ion. This alone was $20 mill ion more than the industry's average annual sales during the same years. The total of combined direct and indirect personal income contributed to the Texas economy by the uranium mining industry in that same three-year period thus averaged almost $100 million annually. In 1979, the amount of indirect personal income contributed to the Texas economy by the circulation of uranium mining's direct contributions had risen to about $196 million, more than double the average of the previous three years. The combined direct and in- direct personal income impact in 1979 thus amounted to $234 million. BUSINESS INCOME IMPACT The income provided directly to other Texas business firms through the purchase of needed goods and services by the uranium industry has been twice as big as the industry's payrolls. In 1976, 1977, and 1978, the South Texas uranium industry spent an average of almost $36 million each year to buy both goods and services from other Texas businesses. By 1979, this direct contribution to the Texas economy had swollen to $76 million. The biggest share of the uranium industry's payments to other businesses have gone to contracting firms, including both construction firms and those providing specialized mining services. In the past four years, about 40 percent of the direct payments made by Texas uranium producers to other Texas firms have been to contractors. Texas wholesale and retail firms have also shared in the business sales provided by the South Texas uranium mining industry. Over the past four years, Texas wholesale and retail trade businesses have accounted for about 34 percent of the uranium mining industry's purchases from other Texas businesses. Public utilities firms have received another six per- cent, while Texas manufacturers and transportation firms have accounted for about five percent each. The other sectors of the state's economy, including other mineral industries, agriculture, finance, insurance, real estate, and services, have accounted

Jan 1, 1980

By C. R. Speers

The induced elastic stresses in the sidewalls of gold-mining tunnels at a depth of 4000 m in the Witwatersrand exceed the peak compressive strength of even the best-quality quartzite rocks. Laboratory tests measuring post-yield stress versus strain response show that brittle fracture occurs, followed by a loss in strength associated with strain-softening behaviour. Numerical modeling based on an assumed Mohr-Coulomb criterion fitted to the test results shows that large ongoing deformations of the sidewall occur, leading to total tunnel failure without adequate support. A methodology is presented to enable a quick assessment to be made of support requirements in terms of ground characteristic curves for numerically derived pressure versus displacement. From these curves, estimates can be made of the force levels for cable bolting and of the thickness and strength requirements for shotcrete linings. As an example of its application, the methodology is used in a comparison of the relative stability efficiencies of a square-shaped tunnel and a horizontal ellipse-shaped tunnel.

Jan 1, 1996

By E. Herrera, L. Mariscal

"Ilo Copper Smelter operates since 2007 with an ISASMELTTM furnace as a single smelting unit (1,200,000 tpy) associated with two Rotary Holding Furnaces for separation of matte and slag, and which directly produces a discard slag. Southern Peru continually has been improving the slag chemistry of its ISASMELTTM furnace in order to reduce copper losses, given its big economic impact due to large slag mass generation. The present paper describes the influence of the CaO, Al2O3 and magnetite content in the slag of the ISASMELTTM furnace correlated with the SiO2/Fe ratio and its liquidus slag. Also it defines the best slag chemistry and operating practice in order to reduce the copper losses without compromise the bricks life of the furnace.INTRODUCTIONIlo Copper Smelter of Southern Peru (Grupo Mexico) is located on the southern coast of Peru, and treats mainly copper concentrates produced in its own mines (Toquepala and Cuajone).The modernized smelter was commissioned in 2007 and operates with an ISASMELT™ furnace as a single smelting unit (1,200,000 tpy), which is associated with two Rotary Holding Furnaces (RHF) for separation of matte and slag. This slag is directly sent to the dump. Figure 1 shows the smelter flow diagram.The ISASMELT™ process is a bath-smelting process using a single lance. The lance tip is immersed into a molten slag bath contained within the stationary, vertical, refractory-lined ISASMELT™ furnace. The injection of oxygen-enriched air, through the lance into the slag results in a highly turbulent molten bath. Feed material falling into the turbulent bath from above reacts rapidly, resulting in extremely high productivity for a relatively small bath volume."

Jan 1, 2012

By S. R. Borrowman

Mill tailings from conventional uranium extraction processes contain nearly all of the radium originally in the ore. Such tailings require controlled storage in perpetuity to safeguard the surrounding environment from radioactive contamination. Alternatives to controlled storage of the tailings are (1) removal of the radium from the tailings for separate storage or use or (2) removal of the radium when processing the uranium ore. In laboratory tests conducted by the Federal Bureau of Mines, radium was leached from tailings using either hydrochloric acid or ethylenediamine tetraacetic acid. A hydrochloric acid leaching method was used to extract both radium and uranium from the ore to yield tailings containing less radium than those produced by either conventional sulfuric acid or alkaline leaching processes. From 77 to 94 percent of the radium in mill tailings was concentrated by sedimentation in slime fractions representing nearly 25 weight-percent of the original sample.

Jan 1, 1975