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By A. Arik

Reliable ore reserve estimates for deposits with highly skewed grade disributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods. This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters.

Jan 1, 1990

By Enrique Folcini

El presente texto señala el proceso de la industria siderúrgica en América Latina y el contexto económico en que se desarrolló. La industria siderúrgica se impulsó a partir de la última I guerra mundial, y desde 1950 ha cuadruplicado su producción, a pesar de que el producto bruto de los países apenas alcanzó a duplicarse. Para los próximos años, se espera que la producción mundial tenga una leve desaceleración a causa de la parcial sobrecapacidad de producción existente en los países más desarrollados; de form que contribuirá el conocido fenómeno de la decreciente elasticidad de los consumos siderúrgicos a sus mayores niveles de ingresos.

Sep 1, 1970

By J. M. Rapkoch

In late October 1996, an acid plant at a major U.S. copper smelter was faced with unexpected and rapidly increasing pressure drop across the gas cooling tower in the acid plant, indicating a build-up on the packing. This threatened to halt operations if not resolved. Earlier that month, a smaller vessel in the acid plant was found to be completely plugged with lead sulfate. It was feared that a similar fate awaited the gas cooling tower unless the scale build-up was stopped. Although lead sulfate is present in most copper smelter acid plants, this accumulation was unusually severe. An investigation was launched to find the source of the lead, determine how lead is transported to the gas cooling tower, recommend operating practices to prevent such severe scaling, and seek ways to recycle the lead value in the scale covered polypropylene packing. Late in the investigation it was learned that the lead originated from an improperly executed recycling program.

Jan 1, 2000

By Charles Preble

El presente texto refiere la producción y consumo del cobre desde 1980 a 1984, deficiencias, reducción de costos y consumo a nivel nacional.

Nov 1, 1985

By O. Durand

The Cerro Verde Hydrometallurgical Plant, located at Arequipa in the southern part of Peru, started its operation in 1977 with a design capacity of 33,000 MT/year of copper cathodes. The plant has treated 61,055,000 MT of ore mainly oxides with a content of 1.01% total copper and 0.67% of soluble copper. The leaching plant has three pads that produce 4.0 gpl copper solution. The solvent extraction plant has four trains with three extraction stages, two stripping stages with a single mixer in all stages. The mixer-settlers are 316 stainless steel and the pumps are vertical turbines. The flowrates of 1,300 gal/mil of aqueous and 1,300 gal/min of organic at a 1/1 ratio. The electrowinning plant contains 208 commercial cells and 18 starting sheet cells. Each cell has 47 anodes and 46 cathodes. In addition to describing the hydrometallurgical plant, this paper also mentions efforts directed at reducing costs and improving operations. The initial results from leaching secondary sulfides, which started October 1985, are also discussed.

Jan 1, 1987

By Edgar Espinoza

En las últimas décadas el avance tecnológico de la informática, la telemática y el uso de los satélites ha producido una revolución tecnológica en todos los campos de la ciencia, entre otros. Por ello, las empresas tuvieron que reactualizarse a través de la implementación de microcomputadoras a sus unidades de producción que van desde los sistemas CAD hasta los equipos de levantamiento de datos de campo como teodolitos en interior mina o superficie. En ese sentido, el presente trabajo describe el proceso del sistema de información tipográfica en la minería subterránea, ya que provee de información a los distintos departamentos y software mineros existentes en el mercado y automatiza los procesos repetitivos y rutinarios en el departamento de Ingeniería y Geología.

Sep 13, 2001

By Peter Dare-Bryan, Will Hunt, Lee Julian

It is well-known that blasting has an economic effect on grade control activities. However, until recently, methods did not exist for measuring the grade control value change caused by the blast. Rules of thumb were the best method to minimize ore loss and dilution, as simulation has been traditionally constrained by time and computer power. Even with these rules followed, an extensive study performed on over 150 blasts showed that the value change caused by the blasts followed a normal distribution – some blasts created value, and some blasts destroyed value. The question naturally asked was “How can we ensure the blast designs are optimized to create value?” Recent advancements in computer power have enabled real-time blasting simulations that create post-blast grade control models before the blast is fired. Understanding what will happen before it happens allows blasters and grade control personnel to iterate designs, searching for the highest value achievable.

Feb 6, 2023

By Erwin Riyanto, Roy William, Karl Llewellyn

The Deep Mill Level Zone (DMLZ) mine is currently one of the deepest block cave mines in the world. The rock mass is heavily veined with little to no joints and faults are usually healed cohesive structures leading to difficult cave mining conditions. The caving process is improved if the rock mass contains fractures with sufficient density that it will cave by gravity as undercutting progresses. Hydraulic fracturing (HF) has been used to create fractures around the cave to improve mining. A seismic monitoring system has been used in DMLZ since the start of mining. Therefore, the seismic activities before, during and after HF can be monitored. Shear wave splitting is a process used to study the impacts of HF on the rock mass. This process involves the measurement of travel times from splitting shear waves after seismic events and using this to define the anisotropy within the rock mass and subsequently fracture density. This paper sets out the methodology for carrying out the interpretation of the shear wave splitting process using seismic data from the fracked cave crown and abutments along with an overview of the benefits to cave mining as result.

Apr 26, 2022

By LUDWIG VOGELSTEIN

WE are indebted to Mr. Barbour for his valuable contribution to the literature on copper statistics; it is to my knowledge the only intelligent attempt to throw light on a much misunderstood subject. If I should appear to criticize some of his findings and arguments, I do not want to leave the impression that I do not appreciate the article; I think Mr. Barbour has been painstaking, and even where one might not agree with his conclusions, he has opened our eyes and stimulated us in our search for the truth.' It might be well to define the term "secondary copper" and to make a few remarks about the origin and the reasons for the variation of the supply. Mr. Barbour has touched on these points, but not sufficiently to make them clear to those not in the business.

Jan 1, 1931

By Robert S. Williams

NO new ferrous alloys have been produced in the last five or six years that are as outstanding contributions to civilization as were the high-speed steels of the early part of the century or the stainless steels announced at the close of the World War. There have been, however, many developments of major importance having to do either with modifications of existing alloys or with new methods of treatment of older iron or steel alloys. Only a limited number of these new developments can be discussed and their selection does not necessarily imply that these are the most important but merely that they are of general interest rather than perhaps of greater importance in highly specialized fields.

Jan 1, 1939

By W. R. Ingalls

WHAT proportion of the national wealth is represented by' the producing mines of the country?' Or by the- mining and metallurgical industry-as a whole, for it is impossible to make-an economic distinction between the mines that produce the ore and the plant that is used to get the metals from it. The total national wealth in fixed property is about $270,000,000,000. How much for the mines? I do not know that any one 'else has ever tried to furnish answers to these questions. In making such an attempt I am conscious that the result can be nothing more than a rough approximation. Yet even that will give an idea of relative values. No separate valuation for the mines of the country has appeared in any inventory of the national wealth previous to that which I compiled and published for 1916. -In earlier census estimates mines were supposed to be included under the head of real estate. However, an examination of the laws and practices of the several states with respect to mine taxation will make it evident that no good idea of the value of the mines of the coun¬try is obtainable from the assessment rolls. In my previous estimate for 1916, I computed the value of the mines at $8,000,000,000, which was approxi¬mately 10 times their net income as reported to the Bureau of Internal Revenue. In making that estimate I fell grossly into error, for several reasons that it is unnecessary to explain, but chiefly because the net income of the mines of the country in that year was exceptionally large. The whole subject of valuing the mines of the country en bloc is extraordinarily difficult At the best, no one can hope to arrive at, anything more than a rough idea about it. However, elements of reason may be introduced and may be made to serve as chief bases.

Jan 1, 1921

By H Vigil, G. Peach

Long tunnels with only one access shaft pose many program problems for logistics, combine these with the requirement to drive directly out under the seabed for 10.2 km, and the program issues become even more challenging. The Musaimeer outfall tunnel was one such tunnel and to meet and eventually improve on the planned completion date required a complex and extensive management of all tunnel logistics required to support consistent tunneling for a two-year period. This technical paper will discuss the management issues and solutions implemented to meet the challenges of the Outfall tunnel construction.

Dec 1, 2022

By P. Nelson, R. O’Connell, J. Rostami

Tunnel boring machine (TBM) system utilization is a critical factor for predicting machine performance. The process of estimating machine performance, including rate of penetration (ROP) and machine utilization (U) must incorporate an understanding of site geology, TBM specifications and site management. The study herein presents a preliminary analysis of the different activity time and downtime components from hard rock TBMs at two project sites to evaluate their impact on machine utilization. A comparison of crew experience, first between shifts and then between projects is included to analyze its effect on utilization and downtime. This work presents the sensitivity of the utilization factor to selected activities in the projects and the impact of geology and site set-up/logistics on machine performance.

Jun 13, 2021

By Harry C. Wiess

RECENT announcement of further restrictions on gasoline consumption in the Mid-West and Southwest has focused public attention on current discussions of an oil scarcity. Conflicting arguments are advanced on the one hand that we have plenty of oil and will not need to restrict consumption as soon as transportation facilities are adequate, and on the other hand that a great impending shortage will require most drastic reductions in civilian consumption in order to provide adequate supplies for military purposes. Data can be presented to support both views, the result being that the public is confused and uncertain of where the truth lies. For a nation with about half of the known crude-oil reserves of the world and two thirds of the total production it seems almost incredible to the layman that any shortage can exist. Those familiar with estimates of future demand. however. show increasing concern regarding our ability to meet military demands without further restrictions in civilian use or wasteful production from our remaining reserves. Only by considering such facts as are available and can be made public can a true appraisal be made of whether or not we are faced with a shortage that will amount to a crisis in crude oil.

Jan 1, 1943

By T. R. Wright

THE Corporation operates concentrators in four camps: Casapalca. Morococha, Cerro de Pa-co, and Mahr. The present concentrator at Cerro de Pasco is the newest having been completed in 1943. and that at Casapalca the oldest, having been built originally as a gravity concentrator, in 1889. Prior to 1925 the Corporation's milling operations were confined to the beneficiation of silver-bearing copper ores, and treatment of these ore: by flotation was started in 1918. Although fairly large deposits of complex, fine-grained lead-zinc ores existed, little progress had been made in the treatment of such ores--in Peru or elsewhere-until the early 'twentics. The Casapalca concentrator began the selettive concentration of complex leadzinc ores by all-flotation methods in 1925, or contemporaneously with the commercial development of selective lead-zinc flotation in the United State:.

Jan 1, 1945

By Clyde E. Williams

DESPITE the confusion resulting from the depression and the beginnings of recovery, important progress in all branches of iron and steel metallurgy has been accomplished during the year 1933. Research work has been intensive and highly technical, with increasing attention paid to fundamentals. Plant application of research developments has been rapid. Highly specialized laboratory methods were used for the study of iron-ore concentration methods. More attention has been given by the blast-furnace operator to the sizing of ore and the elimination of fines from the charge by the use of sinter. Combustion in the open-hearth has been placed under better control and the insulation of open-hearth furnaces has spread rapidly, with resultant higher fuel efficiency and better control of the melting and refining operations. Control of iron oxide content in the slag and the determination of iron oxide and other inclusions in steel received great attention during the year.

Jan 1, 1934

By Games Slayter

NO reasonably well-informed person believes that the role of minerals, both metallic and nonmetallic, will be any less important in the future than it has been in the past. The contrary is true. Industrialization is based on mineral resources and man's ability to make use of them. A nation's standard of living, its political and military power, will continue to depend largely upon the extent to which it is industrialized-and minerals are the raw materials both of the machine and the power to run the machine. Minerals are also the raw materials of human health and stamina. The world's healthiest, most vigorous, and most long-lived peoples have always been those that have lived in regions of the globe where the earth is rich, and kept rich, in the phosphates and other minerals required for the production of the so-called growth foods. Only a small proportion of the land surface of the globe is suitable under any circumstances for large-scale production of these and other essential foods. As things stand, only a part of this land is capable of such production either because the soil minerals have been exhausted by cultivation, or because they never existed in the soil in sufficient quantities.

Jan 1, 1943

By Howard N. Eavenson

AN analysis of the bituminous coal situation by an authority who traces the production, mining, safety, markets and labor trends in comparison with other fuels. BEFORE 1918 the production of coal experienced a steady growth, with slight recessions in ouput in only twelve years (1837, 1841, 1852, 1855, 1861, 1874, 1876, 1889, 1894, 1905, 1909, 1914), and in each of these cases the loss was recovered in the following year and the increase continued. In each decade the output was doubled. Prices, while not high, allowed some profit. In 1918 during World War I, an output of 580 million tons was reached and with the exception of 1923 this total was not again reached until 1942, in World War 11. Losses of output in this period were much greater than ever before; in 1932 the total was 270 million tons less than in 1918 or 1923, and the loss after 1923 was not recovered until 1942. The greatest output was 631 million tons in 1947.

Jan 1, 1950

By Alan Stanley

The MacIntyre Development of the National Lead Co. is located at Tahawus, N. Y. The operations involve the mining and concentrating of a titaniferous iron ore to produce an ilmenite concentrate and a magnetite concentrate. Construction of the MacIntyre plant was commenced during the summer of 1941, when world conditions threatened to cut off the supply of Indian ilmenite. An open pit mining operation was developed and the crushing and milling equipment put in operation in July 1942. A general description of the operation was given in the Adirondack Issue of Mining and Metallurgy for November 1943. The metallurgy of the mill operation was described by Mr. Frank R. Milliken,* Plant Manager, National Lead Company, MacIntyre Development, and presented at the AIME New York Meeting, February 1948.

Jan 1, 1949

By G. S. Headley

At the Sullivan Mine, recent experience with sulphide fires, locally referred to as " hot muck", has necessitated extensive modifications to pillar mining design and operating procedures. Potentially hot pillars are now being designed and mined to prevent fires. Unusual safety hazards and difficulties are encountered in working with, and adjacent. to, existing pillar fires. Operating procedures developed for these conditions have proved successful for safe and continuing production. These changes have minimized the impact of hot ore on current operations and have promise for an improved future.

Jan 1, 1977