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By Emmanuel Pornillos

Dado que en el Perú, la actividad minera utiliza el minado subterráneo para la explotación de minerales, se revalúa el uso de estos en pasta cementada para el relleno de las labores subterráneas, así como los relaves desaguados para su disposición superficial. En ese sentido, el presente texto señala las experiencias de diseño y operacionales de sistemas múltiples para la aplicación de relaves en superficie y subterráneo en el Perú, de forma que se pueda optimizar la selección de equipamiento y una operación robusta.

Sep 1, 2013

By R. P. Beyer

[The Bureau of Mines has measured the low-temperature heat capacities and high-temperature enthalpies of crystalline K2Si2O5 as part of a program for advancing mineral resources technology with energy economy. High-temperature enthalpies of glassy and liquid K2Si2O5 and crystalline K2SiO3 were also mea¬sured. An adiabatic calorimeter operating over the range 5 to 308 K was used for the heat capacity measurements for K2Si2O5 from which the standard entropy at 298.15 K, S°298 = 45.55 ±0.05 cal/deg-mole, was calculated. Tabulated values of Cp°, S°, -(G° -HO°)/T, and H°-HO° from 5 to 300 K are given for K2Si2O5. A copper-block drop calorimeter was used in the enthalpy measurements, operating from 298.15 to 1,198 K for K2SiO3 and from 298.15 to 1,453.8 K for K2Si2O5. No transitions were found for K2SiO3. The KI2Si2O5 showed two reversible first order transitions, one at 510 K with a heat of transition of 0.29 kcal/mole and one at 867 K with a heat of transition of 0.38 kcal/mole. The heat of fusion for K2Si2O5 20 5 was calculated to be 8.42 kcal/mole. Relative enthalpies are given in equation form, and high-temperature values are tabulated for Cp°, S°, - (G°-H°298 )/T, and H°-H°298 . Also tabulated are ?H°, ?G°, and log K for formation of K2SiO3 and K2Si2O5 from both the elements and the oxides.]

Jan 1, 1979

By James S. Graham

Marine design and construction methods are presented on the caisson foundations for the tower piers at the Brooklyn, Ben Franklin, Delaware Memorial 1st, Tappan Zee, Walt Whitman, Throgs Neck, Verrazano Narrows, Delaware Memorial 2nd, and Newport Bridges. All of the bridges are founded on caissons, bearing on bedrock, soil, or piling. Caissons at the Tappan Zee Bridge are partially supported by piling and partially by buoyant forces. General subsurface conditions for each are provided. The purpose of this paper is inform engineers how bridge foundations using caissons were built over major waterways in the Northeastern USA in the past, anticipating a surge of new bridge construction in the near future.

Jan 1, 2013

By Will Mitchell, Ford F. Miskell, C. L. Sollenberger

THE taconites in general are hard, tough ores, difficult to grind. Liberation of iron mineral constituents usually is accomplished by grinding the ore through at least 100 mesh, and often it has been found necessary to grind substantially through 325 mesh to achieve satisfactory recovery and grade in the concentration process. Because of the fineness of grind required and the enormous tonnages of material contemplated for treatment in the future, costs resulting from grinding media wear and power consumption, together with capital investment required for comminution, approach astronomical figures. Economy in any one of these elements per ton of material ground could very well reflect a considerable saving to the ferrous industry in yearly costs. With this in mind, the Research Laboratories of Allis-Chalmers Manufacturing Co. have launched a program to discover means of effecting this economy. The initial phase of the work as described here deals with a heat treatment of crushed raw ore, followed by thermal shock in cooling, for the preparation of rod mill feed. Several investigators 1-5 have noted an improvement in the grindabilities of ores treated in this manner. One investigator2 subjected low grade iron ores to heat treatment in an electric furnace. Basing his conclusions on screen analyses of crushed products, he observed that treated ore was more easily crushed than the untreated. He reported that observation of the treated and untreated ore through a microscope revealed cracks following the grain boundaries in treated ore, whereas no cracks were present in untreated ore. However, few if any have quantified the improvement in terms of total hp hours saved, reduction of wear of grinding media, or reduction of capital costs of grinding equipment involved. By means of Bond rod mill and ball mill grindabilities6 and by comparative wear tests, the conditions maintained during this investigation have been definitely evaluated. Heat treatment experiments have been made on a batch scale in a muffle furnace, followed by continuous scale experiments in a rotary kiln under various conditions of temperature, atmosphere, retention time, and quenching to determine the combination that would give the greatest improvement in the grindability of a taconite without affecting adversely the magnetic susceptibility of the magnetite. From these data, relative costs have been calculated for grinding both untreated and heat treated ore on a basis of plant capacity of 120 tons per hour. Heat requirements for a rotary kiln, as well as the kiln capacity required for the treatment, have been estimated. For these tests 50 tons of ore were obtained from the Aurora mine of the Erie Mining Co., Hibbing, Minn. The ore was reported' to have been selected from the magnetic portion of the lower chert horizons. An average chemical analysis of this portion is shown in Table I and an approximate mineralogical analysis is shown in Table II. No attempt was made to differentiate between the various silicates because the compositions vary widely on the different horizons and depend on the degree of oxidation. Minnesotite, however, is the predominant silicate. The siderite grains were dispersed throughout the ore but were essentially associated with the rock-forming minerals. In a series of preliminary tests in which batches of -6 mesh ore were heat-treated in a muffle fur-

Jan 1, 1952

By L. D. Tracy

The first study of this subject hits been made in Illinois, but as opportunity affords, similar studies will be made in other States. It is hoped that the data obtained will assist the coal-mining industry to standardize the forms of leases, and so avoid some of the abstruse and ambiguous clauses which slay be found in many of them and the consequent liability of costly litigation. In some of the publications of the Illinois Mining; Investigations prepared under a cooperative agreement with the U. S. Bureau of Mines, the Illinois State Geological Survey and the Engineering Experiment Station of the University of Illinois, the coal areas of the 'State have been divided into eight geological districts, each district being treated separately. This report covers District No. VI of that classification, and it is hopped that studies of the other districts will be completed in the near future and similar results published.

Jan 1, 1926

By Stephen Hamilton

This case history details the issues surrounding the rock drilling industry’s growing demand for straight holes, the importance of straight holes and the introduction of a new production drilling systems that can effectively and economically drill a true bore hole. Since the introduction of the hydraulic rock drill, the rock drilling industry has asked for a drilling system that would provide the fast penetration and low operating costs of Top Hammer drilling systems combined, with the directional control of Tube or DTH drilling techniques.

Jan 1, 1999

By W. A. Wright

The use and abuse of social media restate common employee relations issues. Business solutions to these issues require advanced preparation. Employers should establish and enforce social media policies to guide their reactions to employees? social media posts that reflect on the employer and its business.

Jan 1, 2011

By Harry Seltz

INTERMETALLIC compounds are formed in many binary metal systems. Some compounds are stable to their melting points, and others decompose at lower transition temperatures. Even those of the first class are dis-sociated in the liquid state, as indicated by the continuous for in of their solubility curves at their melting points1. While the lattice structures of some of these compounds have been determined, their thermodynamic properties have not been investigated. In this paper is described the determination of the free energy and heat of formation of the compound CdSb, which is of the first class mentioned above, melting congruently at 455° C. This compound shows a rhombic structure, and the lengths of the edges of the elementary cell containing four molecules are: a =6.52, b = 8.60, c = 4.16 A.2 There are three possible methods of determining the free energy of formation of a compound of this type. The first method, applying the third law of thermodynamics, requires the measurement of its heat capacity preferably to liquid hydrogen temperatures, and a calorimetric determination of its heat of formation. The second method involves the study of the equilibrium of the compound in some gas reaction, such as: CdSb + CO2 = CdO + CO + Sb From the known free energies of formation of CdO, CO2 and CO the free energy of formation of CdSb could be calculated. The third method measures the electromotive force of a galvanic cell in which the cell

Jan 1, 1935

By A. J. Duncan, S. Viswanathan, Q. Han

"Measurements of liquid permeability in the mushy zones of Al-15.42% Cu and Al-8.68% Cu alloy samples have been performed isothermally just above the eutectic temperature, using eutectic liquid as the fluid. A modified method has been developed to determine the specific permeability, Ks, as a function of time during the test from the data collected on these alloys. Factors affecting permeability measurements are discussed. Permeabilties are observed to vary throughout the experiment. This is attributed to rnicrostructural coarsening and channeling that occurs in the sample during the experiment. The permeability is related to the rnicrostructure of the sample using the Kozeny-Carman equation. The correlation between the measured Ks, liquid fraction, gL and the specific solid surface area, Sv, improves markedly when compared to previous studies in which rnicrostructural coarsening was ignored.IntroductionThe permeability of interdendritic liquids flowing through dendritic structures ·is an important parameter needed to predict the level of porosity in castings. The permeability is a component of Darcy's Law, used to estimate the pressure drop due to the resistance to the flow of interdendritic fluid to feed shrinkage. Therefore, much research has focused on measuring the permeability of alloys in the mushy zone (1-10). The Kozeny-Carman equation for liquid permeability in the mushy zones of alloys may be written as"

Jan 1, 1999

By J. V. Bymark

It is the intent of this paper to discuss the autogenous grinding circuit at Hibbing Taconite. The scope of the presentation includes; a brief history, the process flowsheet and the steps taken to improve mill productivity, availability and metallurgical performance. Hibbing Taconite is located near the center of the Mesabi Range in Northern Minnesota 100 miles from the Canadian border and 80 miles north of the Lake Superior Port Cities of Duluth and Superior. A 105 mile railroad connects us with the port of Superior, Wisconsin, where our pellets are loaded into lake carriers for lower lake destinations. It is worthy to mention the Mesabi Range's most famous landmark which is immediately to the south of our mine area. This is the Hull Rust Mahoning Mine which operated until the mid-1970's producing more than 700 million tons of red ore between 1893 and 1973.

Jan 1, 1985

"The Cordillera contains numerous porphyry deposits and prospects, many containing economic quantities of copper, molybdenum, gold and tungsten. Over the lost twenty years, different phases of exploration have been driven by individual commodity prices and new discoveries. Exploration methods have remained largely unchanged since the 1960s and 1970s with the range of techniques chosen for each situation depending on the stage of the program, the type of porphyry target and the local environment. Improvements or changes to techniques have resulted from awareness of specific features in new deposits or regional problems. During the last ten years much of the emphasis has been on the re-evaluation of known porphyry deposits with more exploration in areas previously recognized as prospective. Re-evaluation of known deposits has resulted in increased reserves, often with improved gold grade, and the discovery of new zones. Several new deposits have been discovered including gold-only deposits of probable porphyry affinity.Research related to porphyry deposits has followed trends in exploration and has been directed toward the type of deposits that have been of current interest. In addition to research on specific deposits and areas, general research related to porphyry deposits has addressed three broad themes. The first theme involves the role of tectonic processes and the nature of source regions. Although different in detail, recent tectonic models suggest that a tectonic change or hiatus may be important for the generation of metal-rich magmas from various source regions and subsequent fractionation that permits volatile saturation. The second theme is based on magmatic processes, particularly the generation of a volatile phase enriched in metals. This research supports the general orthomagmatic model for porphyry deposits and has helped to define the influence of specific variables in the generation of different types of porphyry deposits. Finally, research on alteration and mineralization has provided evidence for different types of fluids and fluid processes involved in the formation of porphyry deposits. These data also support the orthomagmatic model but indicate additional complexity in magmatic-hydrothermal systems including the role of external fluids. Although important advances have been made, research has had a limited impact on exploration.Exploration and research on deposits that occur in the peripheral and upper parts of porphyry systems have been important over the last ten years. Although considerable advances have been made, the relationship of different styles of peripheral mineralization to magmatic processes in the core of the system remains ambiguous. An improved understanding of the processes that generate zoning, peripheral mineralization, and the surrounding alteration envelopes would be beneficial to exploration."

Jan 1, 1995

By Jürgen Brune, Purushotham Tukkaraja

This editorial introduces a special focus issue on mine ventilation innovations. It highlights key areas such as ventilation on demand, automation, thermal management, atmospheric monitoring systems, and prevention of mine fires and explosions. The issue aims to address the critical role of mine ventilation in maintaining the health and safety of miners.

Mar 21, 2022

By Alexander Sutulov

1. INTRODUCTION According to the classical economic approach of the open market economy, copper supply should be regulated by market forces which are (a) demand and (b) prices. In fact, demand is of primordial importance because prices are a reflection of supply-demand balance: they go up in times of shortages of supply and down when over-supply situation exists. In the past few years, this basic mechanism of market economy has been under pressure from a number of non-market forces, such as social and monetary problems of sane important copper producing countries; structural changes in copper mining companies through mergers with oil companies; and other factors which greatly contributed to distortion of the basic supply-¬demand equation. As a result, we have faced in the last three years a situation of oversupply rarely seen in the past, with a catastrophic fall in copper prices, huge losses at mines and unprecedented indebtedness of copper producers. This has deep repercussions in the copper business and its future supply outlook. This is particularly so when taking into consideration that high indebtedness and high interest rates conspire against the very survival of some traditional producers. As we write this comment (July of 1985), close to one half of U.S. copper production capacity is closed down, sane of it for good, while the same precarious situation exists in Canada, Australia, Zambia, and some other primary producers who cannot face present low prices with equally low costs. The question is then what this situation means for the medium-¬term future, until the end of this decade, Particularly when taking into consideration the fact that some of the factors influencing it are of a long-term character. 2. SUPPLY-DEMAND SITUATION IN THE LAST FIVE YEARS Since the last boon year, in 1979, when world copper consumption reached a record of 9.8 million metric tons of refined copper, demand dropped to only 9.0 million tons in 1982, when the crisis bottomed out, and then steadily recovered to the level of 9.7 million tons in 1984. Meanwhile, copper production, which in 1979 was only 9.4 million tons, in spite of the fall in demand, grew to 9.7 million tons in 1981 and 1983 and only temporarily was cut to 9.4 million tons in 1982 and to 9.5 million tons in 1984. As a result of this imbalance, hugh copper stocks were accumulated with supply systematically out¬growing demand by over 2 million tons at one time. With the Western World refined copper demand running at an average of 115,000 tons per week, this oversupply was equivalent to between 15 and 18 weeks production, i.e. twice as large as normal. This was immediately reflected in very low copper prices. Another contributing factor to relatively low copper prices was the lack of speculator interest for this commodity. Between 1981 and 1984 the world experienced a very intensive period of wealth distribution, high interest rates and intensive restructuring off world economy and its industrial sector. Therefore, much of the available money was attracted to more lucrative and attractive investments rather than to the lack-luster performance of copper, and for that matter, of the metal sector in general. The much announced and discussed recovery of the U.S. economy since 1983, and particularly in 1984, with an overall growth of the GNP by 6.8% in 1984, happened to be more oriented to the service sector than the industrial sector and therefore this recovery was not adequately reflected in copper consumption nor to metals in general. This put serious doubts about the future demand for copper. Consequently copper prices failed to improve in spite of an apparent fall in stocks and a healthy increase in the demand for copper since 1982. At the time of this writing (July, 1985), although same analysts claim that the available stocks are running at about 8 weeks of supply, which are considered to be below normal, copper prices are still very low at between 65 and 67 cents per pound of copper. Part of the answer may be the normal seasonal slow-down period in the Northern Hemisphere due to summer vacations and

Jan 1, 1986

By J. A. Porter

In offering some data relative to this property, and the treatment of its ores, it is proper to say that a purely scientific article has not been attempted. It is hoped, however, that the economic conditions presented may be of interest to the members of the Institute, and that a discussion upon the concentration of the ore may throw some light upon a very unsatisfactory part of the work. The Smuggler-Union mines are located at the head of the San Miguel river, just south of the water-shed between Ouray and Telluride. The latter town, reached by the Denver and Rio Grande railway, is most picturesquely situated, at ail altitude of 8500 feet, in a narrow valley, the lower portion of which exposes only the sedimentary rocks. Along the sides of the valley, large masses of coarse alluvial deposits are left high above the present channel of the stream. Although much placer-work has been done, and some very rich material has been found, the limited extent of the isolated tracts has made placer-mining in this locality generally unprofitable. The valley terminates two miles above Telluride in an amphitheater around which walls rise abruptly several thousand feet. Here the company's mill is situated, being reached by a Bleichert tramway from the mines and also by a spur of the Rio Grande railway from Telluride. At this point, not only are the reddish sandstone and conglomerate beds exposed, but the contact between the conglomerate and the overlying gray volcanic breccia is plainly in view, even at a distance of many miles. A marked stratification is noticeable, indicating the successive layers of igneous breccia, locally termed trachyte. Throughout the entire region this is the favorite name among the miners for the rocks composing the igneous cap of the San Juan

Jan 1, 1897

By Liu Liching, Yan Hongjiu

"In China, the electromagnetic induction initiating system f or blasting engineering has been greatly developed in recent years. With this system, the total number of detonators that may be blasted in each round has been increased from 420 to 940 as a result of the invention of a powerful exploder, and the length of leg wires of a detonator has reached 12 metres. These developments make the new system suitable for blasting engineering of medium scale. Another attractive feature of this system is a set of testing instruments which have been invented that enable a final check of the system to be made before firing as in normal electric blasting. This paper reports on these developments.IntroductionThe initiating system for blasting explosives is one of the key factors to the success of blasting engineering, along with the progress of explosives and blasting technology. Today, we have initiating systems which may be divided into two groups: electric and non-electric. The earliest initiating system was non-electric. Many mines, as well as many projects where rock excavation was involved, were blasting non-electrically before the new nonelectric initiating system came into use in the 1970s. Electric and non-electric initiating systems are the two main initiating systems which are now being widely used, each having its advantages and disadvantages. In electric blasting, the blasting supplies and the blasting circuit can be checked before it is used or fired and, therefore, is regarded to be more reliable. In many large-scale blasting engineering where reliability of the initiation is of great concern, a checkable initiating system is preferable. The electric initiating system is not considered to be as safe as the non-electric initiating system due to its inability to choose proper ignition energy. Therefore, a non-electrical initiating system would be preferable where a hazard of stray currents or static electric energy exists. At this stage of development, one would say it would be advantageous to develop a new initiating system."

Jan 1, 1988

By M. Nagamori, A. J. Plumpton

"A low-grade concentrate from the Crevier Township, Quebec, containing 1.8% Ta205 and 13.7% Nb205 was reduced with carbon at 1600°C, and niobium and tantalum were selectively absorbed in liquid iron. To slag off the zirconia-rich gangue, some silica and lime were added as flux. Metallic iron was added in such a way that the combined contents of TaC and NbC did not exceed 20% in the ferroalloy . Up to 95% of the niobium, and up to 80% of the tantalum contained in the concentrate were recovered in the metal. The ferroalloy was ground finely and dissolved in 2 wt % sulphuric acid to leach out iron and silicon preferentially. The insoluble residue consisted principally of NbC and TaC, the calcination of which yielded an enriched concentrate comprising 80% Nb2O5 and 8% Ta2O5. The insoluble residue could also be chlorinated to obtain an impure liquid of Nb2Cl5 and TaCl5. Process variables and their effects are discussed in terms of higher metal recoveries in the smelting.IntroductionPresently, about one-third of the world production of tantalum comes from the pyrometallurgical reprocessing of tin slag, a by-product of tin smelting, containing sometimes 2 to 10% Ta205 and about the same amount of Nb205. Upon heating tin slags with carbon at about 1600°C in an electric furnace, tantalum and niobium oxides are converted to TaC and NbC, which are absorbed by the coexisting phase of molten metallic iron(1,2). The Fe-Nb-Ta-C melts cannot be decarburized by oxidation because of the preferential formation of Nb and Ta oxides over CO gas(3). So, the ferroalloys containing tantalum and niobium carbides are commercially treated by acid-leaching and I or chlorination to eliminate iron and thus permitting the eventual recovery of purified tantalum and niobium oxides(2).Absorbing Ta and Nb carbides in molten iron was first proposed and demonstrated by Zimmerley and Back(4) in 1957 in order to recover selectively tantalum and niobium from lowgrade concentrates. The process was successfully applied to the electric furnace smelting of tin slags by Hunter and Fursmant(5) over a period preceding 1965."

Jan 1, 1985

By A. E. Halim, J. F. Brune

The 2006 Sago, Darby, and Aracoma mine disasters in the United States (US) forced the US government to implement the 2006 MINER Act and additional regulations that require all US underground coal mines to install and maintain refuge chambers to manage entrapment emergencies, in particular, fires and explosions. However, there is a debate on whether barricading in refuge chambers is a good strategy to survive such emergencies. Australian coal mines are not required to use refuge chambers and, instead, have adopted a strategy that focuses on instructing and training miners to self-escape to the surface. This paper analyzes merits and problems of using refuge chambers and self-escape to the surface to manage emergencies in fires or explosions in an underground coal mine. The authors found that the use of refuge chambers may not be the best strategy during extensive fires or when multiple explosions happen. In these situations, mine rescuers are unlikely able to extract miners who are sheltered in chambers and conversely, self-escape may save more lives than sheltering. Chances for successful self-escape are further improved by regular, externally assessed training such as Level 1 Emergency Exercises required in the Australian State of Queensland. These exercises put pressure on mine operators to ensure and maintain the effectiveness of their emergency management system.

Market confidence is on the rise and industry leaders turning toward the vast and diverse region of Latin America are faced with abundant, yet daunting, opportunity. From the iron orebodies of Brazil to the renowned copper mines of northern Chile, drilling teams in Latin America are often faced with abrasive, broken ground. These types of ground conditions tear up coring bits rapidly, making it extremely difficult for even the most seasoned drilling teams to maintain effective productivity. The drilling challenges faced in this rich and opportune region are being met today by advanced coring technology, bringing with it the potential for increased productivity in Latin American mineral exploration.

Jan 3, 2010

By H. Saito

To Japan, which is scarce in natural resources, limestone is the only mineral resource comparatively rich in ore reserves and having broadly recognized outstanding quality. Distribution of the limestone deposits extends from Hokkaido in the north to Kyushu and Okinawa in the south, and the deposits are located in a manner of framework formation of the Islands of Japan. Studies of the geological ages of these ore deposits reveals that almost all of the main ore deposits west of Kanto Area belong to the Carboniferous Period - Permian Period of the Paleozoic Era. Also in the east of Kanto Area, deposits belonging to the Paleozoic Era constitute the main part, although recently there are increasing examples of reclassifying the geological age of the deposits heretofore considered as Paleozoic Era to the Triassic Period of the Mesozoic Era by the recent discoveries of the fossils of conodont, etc. Large ore deposits and main ore deposit groups are given in the Figure 1, which shows that the deposits are roughly found well distributed throughout the country.

Jan 1, 1982

By William P. Shinn

Jan 1, 1881