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By Roger L. Beals, George A. Tweedy

I. INTRODUCTION. THE results of the cyanide-operations, given in detail in the following paper, show the progress that is being made at the Minas del Tajo. The old pan-amalgamation process, in operation up to and including 1905, while paying a profit on high-grade ores, was no longer able to treat profitably the ores in sight at that time, hence an alteration in the process was imperative. The success of this alteration is eloquently expressed by the following data Pan- Amalgamation. Cyanidation. 1905. 1907. 1903. Tons treated, . . 51,387 53,983 69,300 Value per ton (U. S. currency),. $10.75 $8.39 $8.28 Extraction, per cent., 65.00 88.50 S7.45 Extraction, per ton. .- $7.00 $7.4.; $7.24 Total cost, per ton treated, 6.50 4.311 4.01 Profit, per ton treated, . . 0.50 3.07 3.23.;

Feb 1, 1910

By D. Scott Barr

The Zarafshan/Newmont Joint Venture operates the Muruntau heap leach project, located in the Kyzylkum desert of central Uzbekistan. The mine produces more than 12.4 t/a (400,000 oz/year) of gold from low-grade oxide ore stockpiles adjacent to the Muruntau open pit. It is op¬erated by the Navoi Mining and Metallurgical Combine and is one of the largest gold resources known (Fig. 1). Since commissioning in 1995, total heap leach production has exceeded 21 t (675,000 oz). The joint venture uses four-stage crushing and screening to produce a final product for heap leaching, Merrill-Crowe processing and local refining.

Jan 1, 1998

Crandallite and millisite in Christmas Island 'B' and 'C' phosphate ores are rapidly decomposed by sodium hydroxide solutions at about 80QC. As these phosphates generally contain less than 1% silica, an alkaline extraction process can be designed, in which up to 95% of the sodium hydroxide used, may be recycled. The insoluble residue consists of an impure, highly reactive apatite, which in pot trials, has given good responses as a direct application fertiliser; alternatively this residue can be underacidulated to give a granular product with fertiliser potential. The hot leaching solution contains up to 95% of the alumina and approx- imately half of the phosphate from the original ore. Simple crystallising techniques have been developed on a laboratory-scale to use this leaching solution for producing smelter-grade alumina and detergent-quality trisodium phosphate. As the demand for detergents is limited, an investigation was made of the reaction between trisodium phosphate and slaked lime, derived from a high-grade New Zealand limestone occurring near Oamaru. The product is calcium phosphate, containing up to 40% P205, and less than 0.2% each of iron, aluminium and fluorine, and it should be a useful raw material for phosphoric acid manufacture. A preliminary economic evaluation of the whole process looks promising, And warrants further investigations, including pilot-plant work.

Jan 1, 1971

By W. W. Adams

The first full year of the second World War for the United States presented a picture of the metal-and nonmetal-mining 4 industry which, without proper analysis and explanation, would convey a distorted view of achievements during 1942, especially because employment at gold and silver (lode and placer) mines-the largest group-declined to such an extent that the over-all totals for the country were reduced even though increases were made at mines producing copper, lead-zinc, iron, miscellaneous metals, and non-metals. A complete panorama of the metal-and nonmetal-mining industry, exclusive of coal mining, reveals a decrease in the number of men employed, the man-hours of employment, and the accident-frequency rates. Were the gold and silver (lode and placer) mines to be considered as a separate category; it would be seen that the number of men employed at all the other groups of mines increased appreciably over 1941. These other increases must be considered important, since these mines produced the vital war minerals that made valuable contributions to the military successes of the United States and its Allies during the year. A separate analysis of each of the various groups of mines may be found elsewhere in this bulletin. For the purpose of maintaining continuity in this series of bulletins, however, the discussion in this introduction will be confined to the entire metal-and nonmetal-mining industry (excluding coal mining, for which a separate bulletin, No. 462, has been published).

Jan 1, 1945

By Yilin Fang, Alain Bonneville, Timothy. D. Scheibe, Zhijie Xu

"We present a hydro-mechanical model for geological sequestration of carbon dioxide. The model considers the poroelastic effects by taking into account the coupling between the geomechanical response and the fluid flow in greater detail. The simplified hydro-mechanical model includes the geomechanical part that relies on the linear elasticity, while the fluid flow is based on the Darcy's law. Two parts were coupled using the standard linear poroelasticity. Analytical solutions for pressure field were obtained for a typical geological sequestration scenario. The model predicts the temporal and spatial variation of pressure field and effects of permeability and elastic modulus of formation on the fluid pressure distribution.IntroductionIn order to achieve a substantial reduction of CO2 emissions and alleviate the atmospheric carbon problem, massive scale carbon sequestration is required involving millions of tons of carbon dioxide injection over several decades. The geomechanical response is important upon the injection of substantial supercritical carbon dioxide into deep geological formations. Supercritical CO2 is less dense than brine waters and the buoyancy driven flow of CO2 requires the aquifer to be capped by low permeability rock (""caprock"") to prevent the upward migration of C02 (as shown in Fig.1 ). Massive scale injection of C02 changes the overall stress state in the caprock and formation. This change leads to large deformation that can damage the caprock, create fractures, and open new flow paths for supercritical C02. Therefore, a coupled hydromechanical model becomes essential for the caprock integrity analysis."

Jan 1, 2012

By Stainier X.

The connexion between the Kent and the Continental coalfields on the one hand and the western British coalfields on the other has been for many years a controversial subject between geologists. These coalfields were once considered as detached portions of a former extensive sheet of Carboniferous deposits, but some geologists seem now to incline to the view that they were never connected. The writer hopes to show that the problem is one of the most difficult of geological investigations; that we are still far from a perfect solution; and that both of the extreme theories must be set aside. The physiography of NW Europe during the Carboniferous, with its various generations of earlier folds, is outlined and the features of the Lower and Upper Carboniferous anticlines and synclines discussed, followed by consideration of the denudation of the coalfields and local descriptions of the Malvernian range and Usk anticline, the Pennine chain, the Shropshire coalfield and the Kent coalfield. An attempt is made to trace the transverse Midland anticlines southwards and to deal with the intervening syncline: for example, if the dissymmetrical profile of the Pennine Chain holds good at its southern end then the syncline west of the chain must be deeper than the syncline east of it (the Kent syncline), and in this syncline the deepest part must be at its south-eastern corner, and therefore south of the diagonal ridge. T here is some actual evidence of the existence of Coal-Measures in this syncline, as the results of the Batsford and Burford borings prove. The hypothetical character of most of the conclusions will prove, beyond any doubt, how fa r geologists still are from a perfect settlement of this problem, and how much this settlement is dependent on the more or less advanced state of knowledge regarding all the geological features of these coalfields and of the surrounding country

Dec 1, 1916

By F. S. Crawford

Although it may be impracticable to adopt standard methods of safe working in all branches of mining, and although it may be impossible to establish a standard for each class of work at each mine, some of the iron-mining companies in the Lake Superior district have found that by adopting certain standard ways of performing certain of their operations they insure both more efficient and safer working conditions. Many companies have adopted the idea that the safe way of doing things is also the most efficient and economical way, and, through the medium of their safety conferences they are trying to find the safest way, and the most efficient way, of performing practically every operation about the mines. This activity will, undoubtedly, be continued at every operation which uses this method of doing safety work, because in the advance of industry changes must be made in the results required from time to time. A review of the safety standards and safety suggestions which have been arrived at by some of the companies in this the greatest iron-mining district in the world, will be of value to companies who are interested in improving the safety of their working conditions. So that attention may be directed to the methods in use, rather than to individual companies, all names have been omitted and companies are referred to only by letter.

Aug 1, 1931

By John E. Willson

Typical of southwestern Wyoming are coal structures that dip from 4 degrees to 17 degrees. Those at the Reliance and Winton mines of the Union Pacific Coal Company average 9 1/2 degrees and 15 degrees, respectively, and dip almost directly to the west. By using a hoist for main haulage. a method of mining has been developed whereby four places are driven on the pitch of the seam. Slightly upgrade from the strike at intervals of 300 feet, a two-entry system is driven to the north and to the south. In both fields, which are non-gassy, an exhaust system of ventilation is used. Slope, manway, and lower or haulage entries are placed on the intake. Two air-courses and upper or breaking entries are placed on the return. A retreat system of mining is used exclusively. From the opening of its first coal mine, in the year 1868, until 1923, when the Joy Loader was introduced into the Union Pacific Coal Company's operations, slopes, aircourses and manways were driven by hand. Development work was conducted on the night shift or off shift, and the main hoist was used for haulage. The slope was driven down the pitch with crosscuts turned at intervals of 75 feet and entries at 230 feet. Connections to the workings above were made by driving up the pitch 75 feet. Mule haulage was used to furnish cars to the hand loaders driving planes up the pitch. A sheave was placed at the upper end of the plane with a 1 1/4¬ inch hemp rope doubling around it and having one end attached to the car and the other to the mule. The mule, pulling downhill, raised to the working face a small wooden car of one-ton capacity.

Jan 1, 1941

By Thomas T., Read

DESIRABLE as it is to summarize what has been set forth in preceding chapters, the task can only be approached with great hesitation. What follows represents the personal views of the author at the moment of writing, reserving the privilege to change them on more mature reflection or in the light of further evidence. With that reservation they may be stated somewhat as follows. Education for the mineral industries falls into two categories; general education and technical vocational, using the word vocational not in its usual sense but to signify preparation for specific activities, in which sense a law school is a vocational school. Even at the beginning, as indicated in the first chapter, mineral industry education was partly general and, partly technical and that relationship still persists, because technical education requires a firm basis of general education. Our general American system is to provide free public' general education through the twelfth grade, or completion of high-school work, though there are already many technical vocational high schools, and even in a community where nearly all the young people are preparing for entrance to college there will be some who wish to qualify for employment at the end of the high-school course, or even on completing junior high. Our educational system, therefore, has not only to provide education for those who intend to proceed beyond the twelfth grade but also for those who, for a variety of reasons, may wish or be forced to cease full-time education at any level between the first and twelfth grades. This study has been chiefly concerned with the problem of what kind and how much technical education to provide for those who have completed the twelfth grade and who wish to make their living in the mineral industries. The obvious fact that the mineral industries employ all sorts of trained persons,

Jan 1, 1941

By Steve Dillingham

Blasting crews, explosive product drivers, drillers, blasters, supervisors, and salespeople all arrive daily at customer blast sites in vehicles of every type whether passenger cars, pickup trucks, or bulk trucks. The majority of these vehicles are company owned and re p re s e n t a substantial investment and risk for the company. That may explain why the costs resulting from blasting incidents is often surpassed by those involving motor vehicle accidents.

Jan 1, 2003

By Ad. Breyre

For more than 20 years, Belgium, leading all the coal-mining countries, has made increasing use of sheathed explosives, which wore first suggested by the late E. Lemaire, predecessor of the author as Director of the Institut National des Mines. It appears to the author that it will be valuable to show how the use of sheathed explosives has developed in Belgium, hour the various difficulties encountered in their manufacture have been overcome gradually, and the tyres of sheathing that have survived and the reasons for their survival.

Jan 1, 1940

By David Davison

Metafex®* is an inert material that is more energetic than explosives when activated. Because Metafex is inert until activated (a moment before use), it can profoundly change the logistics of systems and processes that require energetic materials. We have obtained positive test results for a Metafex configuration (called a flat pack) that operates at the practical voltage of ~20 kV. We describe the outcome of the testing and potential uses of the material.

Jan 1, 2006

Tunnels are being built around the world using TBMs and prefabricated segments or in situ concrete as linings. Clients demand high quality of these linings to guarantee a long-term stability and density of the tunnels. This paper describes the development and the use of segmental lining systems, including joints, important design criteria, installation procedures, possible mistakes and consequences, repair works and final results for different sites in Europe and around the world. The experience on these sites shows that damages may occur, if some essential aspects are not considered. These aspects include:parameters of the TBMs and back-up equipment such as fixation of jacking rams, movement of the back-up on the lining or ring reformer;parameters of the segments such as quality of moulds, quantity of reinforcement or structure of the joints; andparameters of the tunnel drive such as advance rate, ring-gap grouting or experience of the tunnel crew.All these aspects have to be considered very carefully in detail to get a good lining accepted in total.

Jan 1, 1999

By C. A. Hardie, G. F. Leichtle, J. A. Finch, J. A. Watson

"The recycling of wastepaper has become an important and common process worldwide. Techniques similar to those used in the mineral processing industry are used to produce high quality recycled fibres for use in newsprint. The mineral processing group at McGill University, in conjunction with the Pulp and Paper industry (Mechanical and Chemi-mechanical Wood Pulp Network), has adapted one of these techniques, column flotation, for the purpose of deinking wastepaper. This article describes the typical process of recycling wastepaper from a mineral processing point of view. It also presents results from McGill University’s flotation column test work at a Québec wastepaper recycling facility. IntroductionThe recycling of wastepaper has become an important and common process worldwide, including Canada which is now the world’s largest importer of wastepaper (CPPA, 1996). Much of the current drive to increase the utilization rate of recovered paper is a reaction to the solid-waste disposal problem that faces many Canadian and United States municipalities. The real problem in the disposal of solid waste is not the absolute amount of garbage that must be disposed of each year, but this amount in relation to available disposal capacity.Environmental restrictions on the creation of new landfill sites and incinerators (the two main options for disposal of municipal solid waste) have tightened the demand/supply balance in the solid waste disposal market. This shrinking availability of waste disposal sites in the face of increasing population with greater disposal requirements defines the Developed World’s solid waste crisis. Not only are there fewer disposal sites available, but the costs of using them is skyrocketing. These factors have increased government regulations mandating recycled paper content in newsprint. Conservation and environmental issues make the current drive for wastepaper recycling a real issue and business opportunity."

Jan 1, 1999

By William Gleason

While a fleet of 100 t (110 st) haul trucks were busy removing overburden from the open pit mine in the distance, a host of dignitaries, including congressmen and California state representatives, gathered for Molycorp?s official groundbreaking ceremony at the Mountain Pass Mine on April 20. The mine, recognized as arguably one of the richest rare earths deposits in the world, is at the center of Molycorps? strategic ?Mine to Magnets? plan. It aims to secure America?s future supply of rare-earth-dependent technologies by developing a strong domestic rare earth industry. Molycorp identifies rare-earth-dependent technologies as those that cannot be produced without rare earth materials. The list of these technologies is long and growing. It encompasses everything from personal electronics and batteries for hybrid cars to permanent magnet generator wind turbines and national defense applications.

Jan 1, 2011

By Ad. Breyre

For more than 20 years, Belgium, leading all the coal-mining countries, has made increasing use of sheathed explosives, which wore first suggested by the late E. Lemaire, predecessor of the author gas Director of the Institut National des Mines. It appears to the author that it will be valuable to show how the use of sheathed explosives has developed in Belgium, how the various difficulties encountered in their manufacture have been overcome gradually, and the tyros of sheathing that have survived and the reasons for their survival.

Jan 1, 1940

By Matthew A. Perras

With growing populations, infrastructure projects are utilizing underground space to expand transportation networks, water supply and sewer disposal systems and hydropower facilities. These new projects require large diameter tunnels to meet the growing demands. As the tunnel diameter increases, not all rock mass properties are scalable and precedent experience becomes less reliable. One such non-scaleable property is lamination thickness. Numerical modelling was conducted to determine the influence of lamination thicknesses on a 16 m diameter tunnel. Five different areas of excavation response were found to exist for laminations ranging between 0.16 to 16 metres in thickness. For this tunnel diameter, critical lamination thicknesses of 6 metre and 1 metre were found to exist. Above 6 metres the excavation response was similar to isotropic models. Below 6 metres the stresses and yield are channeled by the lamination boundaries, increasing plastic deformation. Below 1m multiple lamination units become unstable and the displacements increase significantly and the shape and extent of the yield zone size changes dramatically. The yield zone is controlled by bed deflections and bed parallel shear. As the lamination thickness decreases tensile failure first begins in the haunch area and progressively extends above the crown until a self-limiting plastic yield zone shape is reach at lamination thicknesses below 0.4 metres. Conclusions drawn from observations at the Niagara Tunnel Project are those of the authors.

May 1, 2009

By Gene Baker

A new Safety Library Publication (SLP), SLP-27, which is titled “Security in Manufacturing, Transportation, Storage and Use of Commercial Explosives” was recently released by the Institute of Makers of Explosives (IME). SLP-27 makes recommendations for both general security and enhanced security at explosives sites when security risk levels, declared by the Department of Homeland Security (DHS) using its Advisory System, have temporarily increased.

Jan 1, 2006

By Will H. Coghill, I. L. Feld, G. D. Coe

The object of this paper . is to make known the superior classification accomplished in a hydraulic classifier designed to make use of principles determined by recent research ... The details of the design , the results of preliminary research , and the final testing are given . The classifier of the new design shown in figure 1 and another one like it are in operation as concentration classifiers in a Birmingham iron- ore mill recovering 4 tons per hour of concentrates from table middling that ` otherwise would require regrinding and retabling . The four factors that contribute to the successful operation of these classifiers are ( 1 ) a teeter column of small diameter , ( 2 ) use of an open - bottom tooter column classifier with a periodic pincer instead of the usual type , which terminates in a vortex, ( 3 ) a sorting chamber under separate hydraulic control , and ( 4 ) a teeter column of more than the usual depth . · At the outset it must be stated positively what the authors mean by hydraulic classification : They mean the reconstruction of a multimineral ground product into fractions graded with respect to size , so that cach fraction has the heavy mineral segregated in the fine sizes and the light mineral segregated in the coarse sizes . This definition presupposes that in multiplespigot classification the low specific gravity minerals are carried beyond the first cells to the later ones . The reader must take into account that , from the standpoint of classification , " ores " may be divided into two types , represented - by the following : ( 1 ) Joplin flint - blende ores , which , because of the hardness of the flint and the softness of the blonde , yield upon comminution a product that already has the essence of classification ; and ( 2 ) Birmingham Big Seam iron oros , which contain " easily shelled - out " sca sand and , upon reduction to about 10 mesh , yield a heterogeneous mixture in which the size analyses of the respective " floats " and " sinks " arc almost identical .

Dec 1, 1945

By R. W. Stahl

The use of continuous mining machines has greatly minimized the necessity for blasting in coal mines, even during pillar recovery; however, explosives are still used to blast stumps. The use of improper blasting materials, improper procedures, or both has caused mine explosions and fires, with loss of life and property damage. Researchers and manufacturers are continuously improving explosives and blasting accessories; use of the more recently developed materials will make the blasting operation safer. Extreme caution is mandatory when blasting stumps, as the ignition of methane or coal dust may trigger an explosion or cause a fire. Since the blasting of stumps will no doubt continue, although often unnecessarily, this paper summarizes recent findings published by the Bureau of Mines and recommends safer methods.

Jan 1, 1962