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"Decreasing gold-in-ore grades is one of the main drivers of poorer productivity and rapidly escalating unit costs. Grinding costs, water use and reagent consumption are all intimately related to the ore grade processed. Various pre-concentration technologies have been developed that can be applied at various stages of crushing prior to ore grinding. This paper will review the amenability of ores to coarse particle barren gangue rejection for fine crush sizes in the pumpable particle size range (i.e., particles between 5 mm and 0.3 mm in size). The liberation of oxide gangue achieved during crushing is evaluated by proxy using sink-float analysis and the deportments of gold, sulfur, and arsenic into sinks and floats are monitored. Amenability of gangue rejection by continuous gravity separation is evaluated after various crushing modes (vertical shaft impact crushing, cone crushing, and HPGR crushing). The potential to identify coarse particle mineral association and liberation using three-dimensional x-ray computed tomography will be discussed.INTRODUCTIONThe aim of research in this area is to explore some of the attributes which make some ores amenable to preconcentration, or rejection of a significant component of the feed mass to tailings at a coarse liberation size. Characteristics such as ore type, mineralogy, breakage pattern, particle shape, and liberation characteristics may need to be examined to identify amenability to pre-concentration amenability.It is intended to focus on continuous gangue rejection in the pumpable size range (0.3–5.0 mm) as this remains one of the key opportunities to reduce processing costs through a combination of techniques including screening (for mineral differentiation rather than size classification only) and gravity separation (using jigs). This is to be contrasted to conventional preconcentration as performed with automatic ore sorters."

Jan 1, 2016

By Carla Da Corte, Kagisego Letsoalo, Ashma Singh

Banded Iron Formations (BIF) are sedimentary rock formations ranging in age from 0.8 to 3.8 billion years and consist of alternating layers of silica and iron. The thickness of the alternating layers varies between and within deposits, with this lithology forming approximately two-thirds of South Africa’s future low-grade hematite resources. The production costs for South African iron ore producers are approximately double that of the largest iron ore producers, namely, Brazil and Australia. This in conjunction with volatile commodity prices, necessitated a cost-sensitive beneficiation strategy for low-grade hematite to sustain the industry and extend life of mine. A BIF sample grading at 44% Fe and comprising predominantly of hematite and quartz with minor amounts of magnetite and goethite was subjected to three fines gravity processing routes to establish the amenability of this sample to beneficiation. To provide flexibility for iron ore producers who still have high-grade resources available, two product grades were considered, namely a 60% Fe product for further blending or a 63% Fe product for direct sales.

May 12, 2023

By V. V. Lvov, L. S. Chitalov

"The purpose of the research is intensification of physico-mechanical ore properties determination for ball grinding processes in comminution circuits. The research presents comparative studies aimed at intensification of Bond Ball Mill Work Index (BWi) determination, such as testing technique of Ahmadi and Shahsavari, Berry and Bruse, Gharehgheshlagh, Horst and Bassarear, Kapur, Magdalinovich. The subject of the research is a test procedure of apatite-nepheline, copper-nickel, gold-sulfide and iron ores for the Bond ball mill index. The Bond Ball Mill Work Index for the material firstly was determined by standard Bond test methodology. Two the most promising testing techniques - Ahmadi and Kapur testing techniques - were modified. For the Ahmadi technique it was proposed to pay attention to the circulating load, which should be stabilized on the value of 250% as fast as possible. Two methods were put forward to quicker stabilize the circulating load. For the Kapur technique it was proposed to use empirical coefficients, which is determined especially for the apatite-nepheline, copper-nickel, gold-sulfide and ores. The modified Ahmadi and Kapur techniques require no more than two cycles of ball grinding to determine BWi (while normally 6-8 cycles are required) and less than 5 kg of initial feed. The suggested modified Ahmadi and Kapur techniques allow to intensify the physico-mechanical ore properties determination for ball grinding processes and BWi test costs considerably, which makes them useful for mass sampling and monitoring strength properties of ores entering a concentrating mill. INTRODUCTION When designing concentrating mills, the choice of the technological scheme for ore pretreatment, particularly the type, quantity and size of the main process environment, the determination of optimal grinding conditions and the calculation of equipment load are carried out by preliminary studies of grinding in semi-industrial or laboratory-scale plants. Semi-industrial tests on full-scale plants provide the most reliable information for calculating specific loads for equipment. However, this requires a significant amount of ore samples, a high labor costs and the pilot plants. Thence the most researchers performed grinding tests with small laboratory equipment using small ore samples."

Jan 1, 2018

By E. P. Jennings

The abundance and value of the tellurium minerals of Colorado is well known, but, as yet, few analyses have been made of them, and I offer these as a small contribution to the chemistry of these valuable ores. 1. Native Tellurium.—The specimens from which the analyses of this mineral were made are from the " John Jay" Mine, Boulder County, Colorado, where it occurs in quite large masses, though mixed with more or less silica and iron pyrites. It is usually a finegrained, tin-white mineral, but sometimes occurs in distorted, hexagonal prisms in cavities in the quartz. Before the blowpipe it gives the reactions for tellurium, sulphur and iron; by cupellation, it yields a small amount of gold. An analysis of a coarsely crystallized specilnen gave the following results : Specific gravity, 5.10.5. Tellurium,.........68.40 Gold, :.........1.36 Iron pyrites,........24 92 Ferric oxide,.....4.37 Silica and silicates,........11.54 Silver, lead, and mercury,... traces. 100.59 Deducting the pyrites, iron oxide and silica, we have for the con]position of the mineral: Tellurium,..........97.78 Gold,.......... 2.27 100.00 Or, considering the gold to be in combination with tellurium to form sylvanite, we have : Nativc tellurium,........96.50 Sylvanite (An, Te3,),........4.50 100.00

Jan 1, 1879

By Persifor Frazer

It has been the aim of the writer, by measuring his base line on the territory of theoretical chemistry, to attempt to fix by triangula tion certain points within the domain of mineralogy. As the barest first experiment in this direction, a few of the hydrated oxides of iron have been selected, their theoretical construe tion reduced to percentage of the constituents into which the ordinary analytical methods would resolve them, and the results compared with actual analyses compiled from the most reliable sources; the accidental errors being as much as possible eliminated. This method seems to be a simple one and one easily pursued, but, as will shortly appear, it is beset with grave difficulties, all of which the writer does not pretend to have satisfactorily surmounted. In the first place arises the important question, what are we to understand by the hydrated oxides of iron ? In all books of chemistry and lexicons of minerals, the proposition, long ago taught by the earlier chemists, that water might exist in two forms of combination, viz., as water of crystallization or as water of constitution, is tacitly assumed. There is nothing in the principles of the new chemistry which is opposed to this; for (to carry the mind's eye into the process of con struction of the least units into which a definite chemical compound is capable of being divided without losing its characteristic proper ties), however unlikely it may seem, it is, nevertheless, possible that a given molecule of iron may, under certain conditions of heat, pressure, etc., attract to itself as many molecules of the water in which it is natant as: from the relative size, shape, attractive force, etc. of either, it is capable of taking up, and this complex system of associated molecules might oscillate as a physical unit so long as the conditions on which its existence was dependent remained unchanged. Moreover, it is highly probable that the first effect upon such a mole cule produced by physical or chemical forces would be to separate it into two or more simple ones of different kinds, while a further ap plication of these forces might rend asunder the bonds of the simpler compounds themselves.

Jan 1, 1879

By Charles A. Colton

The results of a series of analyses extending over a period of three weeks at the Cedar Point Iron Company's furnace, Port Henry, New York, are given in Tables I and 11. This furnace uses a very pure magnetite and Lehigh and Lackawanna anthracite. The flue leading the gas from the "down-comer" to the boilers was tapped by a 2 inch gas pipe, which carried the gas to the Orsat apparatus. The pressure of the gas not always being sufficient, owing to the small amount made, to force it into the apparatus, I omitted taking samples several days, and with the exception of the last three days of the campaign, made the analyses whenever opportunity offered. I find the Orsat apparatus, as described by Prof. Egleston," to work very well, with one exception. The CO is not absorbed as readily in the ammonia-copper solutiou as he states in his description of the apparatus, as many as 50, and sometimes GO, passes being necessary to absorb all the CO. The power of absorbing rapidly increases as the solution is used, and this would indicate that the more oxygen it contains the quicker will it do the work. Probably the addition of a small amount of some oxidizing agent would remedy this. When the furnace was working in its normal condition, I had no occasion for using the filter, the amount of fume being so small as not to canse any inconvenience. The gas burned with the flame peculiar to CO, and contained just enough solid particles to give it a slight reddish tinge.

Jan 1, 1879

By W. S. Keyes

The State of Nevada, known par excellence as " the Silver State," occupies the major portion of the wide plateau, or so-called Great Basin, lying between the Sierra Nevada range on the west and the Wahsatch range of the Rocky Mountains on the east. It extends from the 114th degree to the 120th degree of longitude, west of Greenwich. It is limited, on the north, by the 42d degree of latitude, and on the extreme south by the 35th degree of latitude. Its general shape is that of an irregular parallelogram, from which the lower or southwestern portion has been cut off by a diagonal southeasterly line; the missing portion forms a part of the State of California on the west. The Great Basin is made up of a succession of low hills, or minor mountain ranges, running very nearly north and south, with long valleys between them. All of these mountains are more or less metalliferous. On the westcrn rim, marking the eastern flank or foothills of the Sierra, we find granites, porphyries, and propylites. Here we note the great Comstock lode, with its free-milling gold and silver ores, and still further south the once prominent and the now reviving gold and silver-bearing districts of Esmeralda County, Nevada, and of Morro County, California. Next, at some distance to the east, we find the mining districts at and near Unionville, in Humboldt County. Still further to the east we find the Battle Mountain copper-silver district, north from the railroad, and southerly therefrom the Austin or Reese Ever, Belmont, and other districts. Still further east and north of the railroad, we find the Tuscarora, a new district of very

Jan 1, 1879

By Oswald J. Heinrich

The deposit of rock salt along the shores of Lake Huron, in Canada, has been brought before the public during the last six months, in consequence of the developments made by the diamond drill at Goderich. It is likely to be of more than common interest in the future, since now actual operations have been commenced to exploit the deposit and work it by regular mining. The methods of mining rock salt being but little known in this country, it may be of interest to make a few general remarks in regard to them before entering, upon the description of this new mining enterprise. According to the conditions under which salt is .found in nature, various methods have been resorted to, in course of time, to make it available for the human race. They consist in: A. Natural or solar evaporation. B. Artificial evaporation, either exclusively or in connection with the former. C. Mining the rock salt in its natural state, and converting it to a marketable product, if need be, by simply pulverizing it. Without going into the details of the various methods of making salt available in an economical point of view, dependent on its degree of pority, or on various local influences, we cannot refrain from alluding to the general principles which influence the mining and manufacturing of salt in countries where they have been carried on for hundreds of years. ECONOMICAL CONDITIONS FOR SUCCESS. Salt being one of the articles of prime necessity, and one universally distributed throughout nature, it must always be sold at a comparatively low price. It would even be quoted in the market at prices far below those now ruling, if it were not for the high duties generally imposed upon it, for purposes of state revenues. But looking closer into the subject, it will be found that this duty is probably one of the least oppressive, although in some countries it exceeds sixfold the cost of profitable production. To produce the article at the lowest possible cost requires, therefore, a

Jan 1, 1879

By Oswald J. Heinrich

During the last twenty years much has been done to investigate and define the Mesozoic formatibn of the United States along the Atlantic States, as well as in' the Territories. The investigations of Professors Hitchcock, Emmons, Hayden, H. D. Rogers, and those now in progress in connection with the geologicd surveys of Penn-

Jan 1, 1879

By AIME AIME

A REGULAR meeting of the Executive Board 'of American Engineering Council was held in the Onondaga Hotel, Syracuse, N.. Y., Feb. 14, 1921, with the president, Herbert Hoover, presiding. Reports of committees were presented and acted upon as follows: ENGINEER ON INTERSTATE COMMERCE COMMISSION The second meeting of the Committee was. called because it was represented to the Committee' on Pro¬cedure that the American Society of Civil Engineers, the American Association of Engineers, and the Ameri¬can Institute of Consulting Engineers were anxious to have President-elect Harding appoint an engineer to fill one of the vacancies on the Interstate Commerce Commission. The representative of The American Society of Civil Engineers agreed to endorse the recom¬mendations- of American Engineering Council, and the Committee on Procedure prepared and sent a letter to the President-elect, a - copy of this letter being sent to each member of the Board. No names were suggested. . The appointment of an engineer on the Interstate Commerce Commission was approved and the Board, after approving the action of the Committee 'on Procedure in writing the President-elect, voted that, if requested, the Committee on Procedure submit a list of not less than six names for the appointment of an engineer on the Interstate. Commerce Commission.

Jan 1, 1921

By J. E. Lema

America's bulk commodity transportation systems have taken on a new look in the 1970's and 1980's. Railroad systems, barge lines providing inland and intra- coastal waterway transportation, and Great Lakes carriers have undergone substantial changes through mergers and acquisitions, consolidations of ownership and control, and construction of modern intermodal transportation facilities linking railroads and water carriers. The new look has generated some concerns and opportunities with regard to producers and shippers of bulk commodities which are characterized by the necessity of moving large quantities of heavy materials long distances. Clearly such transportation requirements call for efficient railroad and water carrier services. Shippers of commodities like coal, grain, .chemicals, minerals, ores, forest products, petroleum products, and heavy manufactured goods find reductions in transportation competition lead to concerns that rates charged by carriers will not be sufficiently constrained by market forces. At the same time, new policies on contracting for railroad services can lead to greater efficiencies, a rewarding opportunity for carriers which should be shared with shippers and consumers of bulk commodities. Then, of course, there's a related problem that in the absence of effective competition, the benefits of increased carrier efficiency will not be passed on, in part, to shippers and consumers, causing losses in markets for producers.

Jan 1, 1986

By Theodore B. Counselman

Of all natural resources, iron ore made into steel is the most important both in tonnage and value. The primary reason for the prosperity of the United States in the last century has been its pre-eminence in domestic supplies of iron ore and steel. The depletion of these reserves by two world wars and by the demand for richer blast furnace charges, as well as the constantly growing world- wide demand for steel, has fostered the recent quest for new iron ore mines around the globe. These developments have made a dramatic change in the iron ore picture of the world. It is the purpose here, however, to look briefly at the development of the United States iron ore industry, which has played such an important role in the events leading to the modern day boom in iron ore exploration.

Jan 7, 1965

By Alan M. Bateman

Before World War II we proudly considered that we were the nation of all the world most richly endowed in mineral resources. We knew it was no accident that those countries abundantly supplied with mineral resources became the great manufacturing nations, and the politically and militarily strong ones; and that our own great industrial cities sprang up where coal and iron met. We all reallized, especially we of the mining profession, that the energy of fuels and the solidity of metals spelled industrial growth and in turn industrial might and that other nations came to regard mineral self-sufficiency as one of the chief goalsof economic nationalism.

Jan 1, 1949

By R. H. Colquhoun, A. W. Bolland, H. J. H. Pieterse

"American Barrick Resources Corporation acquired the goldstrike property in north eastern Nevada in early 1987. Since that time, the company has undertaken an extensive development program. This paper will overview the milling, autoclaving, and heap leaching facilities which are part of the $400-million Betze development plan. Gold production at the Mine has increased from 40,000 ounces per annum in 1987 to more than 500,000 ounces in 1991. And in 1992 Goldstrike will be the single largest North American gold mine when it produces 1,000,000 ounces.1. SUMMARYAmerican Barrick Resources Corporation acquired the Goldstrike property in northeastern Nevada in early 1987. Since that time, the company has undertaken an extensive development program. This paper will overview the milling, autoclaving, and heap leaching facilities which are part of the four year, $440- million Betze Development Plan. Gold production at the Goldstrike Mine has increased from 40,000 ounces per annum in 1987 to more than 500,000 ounces in 1991. In 1992, Goldstrike will be one of the largest North American gold mines, when it produces appro approximately 1,000,000 ounces.2. INTRODUCTIONAmerican Barrick Resources Corporation is in the process of developing the Betze gold deposit, located on Barrick's Goldstrike property in the Carlin area of Nevada, U.S.A.The Goldstrike Mine has 17.9 million ounces of proven and probable reserves and an additional 460,000 ounces of possible reserves. Additionally, the Purple Vein deposit, one mile north of the Mine, is expected to add at least 4 million ounces of reserves by year end 1991.The Goldstrike ore body contains both oxide and sulphide ore. The largest part of the reserves are contained in the high grade, deep sulphide ore. Mining of the sulphide ore contained in the Betze deposit involves the removal of large quantities of overlying oxide ore. Oxide ore is treated through one of the following processes:-"

Jan 1, 1992

By Thomas T., Read

ALTHOUGH the first colonists in the area that is now the A United States, whether Spanish, French or English in nationality, were usually keenly interested in the possibilities of mineral wealth, it is a curious and interesting fact that none of them happened upon the mineral deposits that eventually were to make this the greatest mineral-producing country; up to 1800 it would probably have been rated as rather poor in minerals. Spanish explorers traversed the southeastern United States with- , out finding the Appalachian gold deposits that aroused so much interest in the early nineteenth century; Coronado sought in vain for the seven golden cities of Cibola; and the important gold \ deposits of California were not discovered until the political sovereignty of the region had passed from Mexico, which had held it for three centuries. The French also held Canada for nearly two centuries (and the British for another century) without finding the mineral deposits in Ontario and Quebec that now are so important. Though they knew of the copper of the Keweenaw peninsula, the lead ores. of Wisconsin and Missouri, and the coal of Illinois in the seventeenth century, these deposits were all too remote for exploitation. In the area held by Great Britain, iron smelting was planned at Jamestown as early as 1619 and was actually begun at Lynn, Mass., in 1643. The industry grew slowly, at first, but had reached considerable importance before the Revolution. Commercial bituminous coal mining began about 1750 in Virginia but anthracite mining in Pennsylvania was not started until 1800. As a result there was naturally little interest in the technical aspects of mineral prodnction here before 1800 by any except the few people who were actually engaged in it. Students of natural science were much interested in minerals, however. The activities of those who rank as geologists are so thoroughly covered in

Jan 1, 1941

By S. Schina

Part of the Imittos Western Peripheral Motorway in Athens is the twin road tunnel in the vicinity of American College, with 20m excavation diameter. In the paper, the environmental and other requirements, the geometry and the geological – geotechnical characteristics of the rock formations in the construction area are given. Information regarding the modeling and analysis methods that are used for the design of the temporary support, the final lining and the wedge and slope stability analysis is described thoroughly. Finally, the results of the analyses are compared with these of measurements and general remarks during the construction of the tunnels.

Jan 1, 2001

By G. W. Tower

THE YEAR 1931 was for most American copper producers one of restricted output but extremely low production cost.. When compared with 1929, the marked reductions in costs achieved in 1931, operating at rates in many instances a third to a half of capacity, can only be regarded as remarkable. In fact, the recent shut-down of several large operations suggests the probability that 1931 costs represent a bare minimum for many properties. Before discussing the 1931 results a few remarks on cost data are appropriate. The type of cost tabulation here presented was first published in 1929, (A. B. Parsons. E. & M. I. June 8, 1929), and has appeared each, succeeding year following in general the calculation method and company set-up of the original article. (. G. W. Tower, E. & III. L, July 8. 1930; S. D. Strauss, E. & M. J.; July 27, 1931). As far as possible the leading American copper companies are included. In considering these cost tabulations it must be borne in mind that the information from which they have been prepared is entirely contained in the annual report of each company; and that a multiplicity of interests and a condensed income statement for some of the larger companies, such as Cerro de Pasco and Kennecott, make the cost figure an arbitrary one depending upon sundry metal credits, metal products, miscellaneous income, etc. For Granby, Howe Sound. Magma, and Noranda, sundry metal credits are important. Furthermore Andes, Chile and Greene Cananea give costs only against copper sold. Although the individual costs here figured are by no means absolute they are computed by the same method each year and offer a basis of annual comparison; and with attention to footnotes the premises on which the costs are based may be easily followed.

Jan 1, 1932

By C. W. EICHRODT

NUMEROUS requests for the suspension of publicity make difficult the preparation of the annual review of copper metallurgy for 1934. In the United States, sales allocations indirectly have set restrictions on the scope of activities of producers and refiners, and necessitated closer cooperation between secondary and primary producers. However, the feeling exists that preparations for a return of intense competition should not he neglected, and careful investigations are being conducted for ways and means of improving industrial positions and production methods. In all probability, efficiency in technique and equipment will prove of far greater importance in the near future than production capacity, and many important developments in copper metallurgy later will be found to have been born during the current year.

Jan 1, 1935

By D. A. Bruce

The use of small diameter cast-in-place bored piles is becoming increasingly popular in the United States. Such inserts are used as conventional load bearing piles, and are generally referred to as pin piles. The other major application is for the in situ reinforcement of soil slopes or excavations. The paper reviews the applications, construction, design and performance of inserts of each type.

Jan 1, 1989

By W. R. Ingalls

IN THE years immediately preceding 1914, the American people earned an aggregate income of 33 to 34 billion dollars, of which they saved about five billion, the annual saving being expressed mainly in the form of houses and railway extensions; to a less extent in public utilities, public improvements, factories and mines; and to a very small extent in foreign investments. It appeared needful that we should save and invest annually in these ways about 15 per cent. of our aggregate income in order to keep the development of our plant, so to speak, ahead of our steadily growing needs. The common knowledge that at present our housing and railway facilities are inadequate suggests immedi-ately that we have been running behind the pre-war ratio of reinvestment. Since 1919, we have not had any carefully prepared, authoritative estimates of the national annual income. However, with some experience in this subject, I have ventured to make rough estimates, which rest on solid foundations, although some rather empirical develop-ments are involved. Such estimates would be consid-ered good work in this field if they fell within limits of 10 per cent., plus or minus. Even so, these data are more useful when quickly available than more accurate data that are belated; for recognizing that there is a margin of error we can at least get a reasonable and approximate idea of how things are going.

Jan 2, 1923