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SINCE you have asked me many times in particular how those mirrors are made that are commonly called spheres,* and even though I have told you at other times, I do not wish to omit writing of it here again in detail, so that you may have as complete information as I can give you, both in order to satisfy you fully and because it belongs among the subdivisions of the subject that I have proposed. Concerning this, I first tell you that it was an ancient discovery, and in those times as today was celebrated, and worthily so. For the effects these mirrors produce are miraculous things incomprehensible to me, and the more I think about it the more I am bedazzled with wonder, nor do I know how to explain by theory of perspective the causes demonstrated by their effects. Marvelous indeed is the beauty of their shining clearness, but much more so is the fact that (according to the shape that the craftsman has chosen to give them) they reflect back the shadow of the things

Jan 1, 1942

By Case JE

Complete Bouguer and isostatic anomaly maps compiled for Costa Rica provide new insights into the crustal structure and mineralization. Terrain corrections were approximated from the station to a radial distance of 167 km by computer using a 3- minute digital elevation model of Costa Rica and surrounding areas. Isostatic corrections, based on Airy-Heiskanen compensation, were also calculated from 0 to 167 km using the 3- minute elevation model and from 167 km to 180 degrees using combined topographic and isostatic reduction maps. Costa Rica can be divided into four main terranes based on gravity data: a Pacific coastal region, a Pacific inland area, a central region, and a Caribbean coastal region. Negative gravity anomalies along the Pacific coastal margin correlate with an offshore sedimentary basin, and large positive anomalies correlate with mafic and ultramafic igneous rocks on the Santa Elena, Nicoya, and Osa Peninsulas, and at Puerto Quepos. Pacific inland anomalies are separated from the Pacific coastal region by a steep gravity gradient, and over the Coast Ranges a major gravity low overlies a thick section of low- density sedimentary rocks. In the central region, a major gravity low occurs over a thick low-density Quaternary volcanic complex in the Cordillera Central, north of San Jose. A prominent feature of the Caribbean coastal region is an interrupted gravity low over the Limon Basin that reflects a thickening of low-density sedimentary rocks. A conspicuous gravity lineament, trending northeast separates northern and southern Costa Rica. The lineament is defined by the termination of several major gravity anomalies including those over the Coast Ranges, Cordillera Central, Puerto Quepos, and Limon Basin. In addition, the lineament correlates with other geological and geophysical data including: northeast-trending faults, the southern limit of large Quaternary volcanoes, the segmentation of the middle America volcanic belt, and a seismicity gap. This lineament may be the expression of a previously unrecognized major northeast- trending fracture zone in central Costa Rica. An important economic implication of the gravity lineament is a correlation with the termination of gold and porphyry copper deposits in Costa Rica.

Jan 1, 1987

This paper addresses the role of mine geology in mining geotechnics. The role is assessed and discussed in terms of five main elements; geotechnical complexity, geological complexity, mine scale, percentage sampling and geological uncertainty. Lastly, the overall objectives and mine geology requirements are listed in terms of the various mine development stages; exploration, feasibility-design and operating.

Jan 1, 1993

By George W. Hezzelwood

THE Balatoc mine, one of the Haussermann group,† is on the Island of Luzon, the largest of the Philippine group, about 260 km north of Manila, and 12 km from the city of Baguio The Baguio district is the most important gold-mining area of the Philippines, with 14 producing mines in 1939, milling 2,358,804 tons of ore, yielding [P]40,881,048, approximately 55 per cent of the total Philippine production of [P]74,131,216 PRODUCTION HISTORY The Balatoc mine began production In January 1929 with a 150-ton cyanide mill Increases in mill capacity have taken place as follows March, 1932, to 330 tons June, 1933, to 470 tons December, 1933, to ;15 tons July, 1934, to 700 tons December, 1934, to loon tons May, 193, to 1200 tons October, 1938, to 1300 tolls April, 1939, to 2000 tons January, 1941, to 2T50 tons Production during the period of expansion has steadily increased in total value in spite of the fact that grade of ore milled has dropped-from $31 06 in 1929 to $5 78 in1940 Annual reports give production as shown in Table I, the average value, being based on gold at the old price of $20 67 per ounce [ ] GEOLOGY The ore occurs in quartz-calcite veins that vary in width from narrow stringers to mineralized zones 40 to 30 ft wide Wall rocks consist largely of diorites, with some andesite, and a fragmental breccia called locally the "Balatoc plug " Texture of the ore varies widely in the different vents-from a soft, highly altered, gouge material filled with quartz fragments through a soft, unaltered quartz-calcite to a hard, massive quartz ore Three major vein systems have been extensively developed, and smaller amounts of work have been done on several others These veins strike east-west to N 60°, clipping south from 50° to 90°, and are essentially tension breaks between a series of faults or shears striking N 30°E to N 30°E and clipping southeast from 50° to 90° The shear veins and tension veins probably formed more or less simultaneously,

Jan 1, 1942

By D. Harker, E. Epremian

The constitution of the nickel-tungsten system has been studied by a number of investigators, the most recent of which are Ellinger and Sykes.1 On the basis of metallography, electrical resistivity and hardness measurements and some X ray diffraction work, they constructed a consitution diagram (Fig 1). Ellinger and Sykes report a0 for the alpha face-centered cubic phase (nickel saturated with tungsten) as 3.66?.‡ The gamma phase (tungsten saturated with nickel) is given as body-centered cubic, but no value of a. is recorded. At 43 pct tungsten by weight (approximately 20 at. pct) a beta phase is reported, but structure and lattice parameter are not known. Primarily on the basis of metallographic evidence, they conclude that beta is a new phase and rule out the possibility of formation of a superlattice since they- observe a new phase in the microstructure. Grube and Schlecht2 report an ordering reaction in a system similar to the Ni-W (Ni-Mo) and Harker3 has shown that NirMo forms a superlattice upon the pre-existing face-centered cubic lattice of the alpha phase. Elliniger arid Sykes observed a change in the diffraction pattern of a 4.3 pct W alloy upon aging and attributed it to the formation of a new phase. Thus, there appears to be some question as to the character of the beta phase reported by Ellinger and Sykes. The purpose of the present work is to determine precisely the structure and nature of the beta phase in the Ni-w system of X ray diffraction methods. Experimental Procedure One inch diameter ingots of 43.66 pct, 40.15 pct and 34.06 pct .tungsten by weight (19.8, 17.6 and 14.1 at. pct respectively) were melted and cast under vacuum from electrolytic nickel and pure wire filament grade tungsten. The ingots were soaked for 16 hr at 1300°C in a hydrogen atmosphere furnace, then swaged at this temperature and finally drawn to 0.020 in. diam wire. Some of the bar stock was retained in 1/2 in. diam rod for hardness and metallographic studies. Wire samples for diffraction work were sealed in evacuated quartz tubes and subjected to the various solution and aging heat treatments in a hydrogen furnace. X ray photograms were taken in a Debeye-Slierrer camera using copper K radiation filtered by nickel foil. Results X RAY DIFFRACTION The lattice parameters of the alpha and gamma phases at saturation were determined by an X ray photogram of the 19.8 at. pct W alloy after solution heat treatment at a temperature well within the alpha-gamma range above the peritectoid temperature (17 hr at 1150°C—oil quenched). The alpha phase was found to be face-centeted cubic with a. of 3.594 ± 0.001?, while the gamma phase was determined as body-centered cubic with a. of 3.158 ± 0.001?. Exactly the same phases and parameters were ohtained with the 17.6 at. pct W alloy for the same solution heat treatment. Thorough analysis was made of an X ray photogram of a 19.8 at. pct alloy sample in the quenched and aged condition (solution treated 1T hr at

Jan 1, 1950

A major domestic aluminum producer raised its price for primary aluminum metal from 44 cents per pound to 48 cents per pound, effective August 5, 1976. Other major producers have increased their list prices by equivalent amounts COAL: The strike which began July 19 in southern West Virginia enlarged by early August to involve approximately 80,000 miners in nine States. As of August 4, the aggregated loss of production is estimated to be 5.8 million tons. Reportedly, at this time, the railroads which serve the struck areas are feeling the largest impact with coke plants and electric utilities relying on stocks which are generally high.

Jan 1, 1976

By G. K. Derby

The Bureau of Mines investigated methods for removing dragline bucket wire rope terminations with the objective of finding efficient methods that are safer than the method most commonly used at U.S. surface mines, which is to use the explosive impact of a projectile fired from a cannon to remove the rope termination. Removal of a wire rope termination for repair or replacement requires separation of the wedge and socket that lock together to secure the rope end. The Bureau investigated currently used methods and improved upon and tested two safer alternate methods for removing wire rope terminations. A cannon test program was conducted, using 40-and 50-gr primer (detonating) cord, to establish the possible force produced with a 4-in-bore cannon and a 55-lb projectile. Wedge and socket units supplied from cooperating mines were separated under controlled conditions to establish data on separation force requirements. The two alternate methods investigated were use of the force generated by (1) a pendulum ram and by (2) a portable hydraulic pusher. Both methods are capable of providing sufficient force to effect wedge and socket separations on draglines with up to 78-yd3 buckets under normal conditions.

Jan 1, 1984

By Mirian Mamani

Estudio sobre los diferentes tipos de depósitos de zinc ubicables en los Andes Centrales. Tras destacar el extraordinario potencial que ofrece Perú, la autora precisa que debido a que los magmas son fértiles, se formaron yacimientos en columnas corticales favorables para incrementar las concentraciones de zinc en las rocas intrusivas y rocas sedimentarias (calizas y dolomitas); se tienen las mejores estructuras (e.g., fajas corridas y plegadas) que favorecieron el emplazamiento de los fluidos y excitación térmica en el tiempo geológico por radiactividad de los depósitos; y lo más importante, que se encuentran en su mayoría preservados debido a que las tasas de erosión donde afloran son mínimas.

May 31, 2019

By Kitzinger F

The economic climate of the Canadian mining industry forced an increased interest in rapid, continuous excavation techniques for hard rock formations. The potential applications and advantages of continuous mining over the present drill- blast-muck labour intensive cyclical methods are considerable. Noranda investigated an electrical technique, Plasma Blasting showing considerable promise for mining hard rock. The background of the technology and the theory of blasting rock with electricity is described. The Plasma Blasting process is based on the fast discharge of stored electrical energy into a small amount of electrolyte, suitably located in the rock. The electrical energy converts the electrolyte into high pressure plasma, which expands very quickly, thereby, generating a shock wave. This shock wave produces a stress field inside the rock, resulting in a blast similar to that made by chemical explosives, but without the deleterious fumes. Noranda is currently blasting boulders of 4-5 tonnes and is at present constructing a mobile, autonomous secondary rock breaker for underground and open pit applications. Tests on in situ hard rock formations will lead to the development of a continuous mining machine. Production rates of 500 tonnes per man-shift could be obtained with such a machine.

Jan 1, 1990

By W. E. Armstrong

Gypsum was first exploited as ?a commercial proposition in this province by the Union Mining Company which, in 1900 opened quarries on the east shore of Lake Manitoba, near the present site of Gypsumville. This company established a mill at the head of Portage Bay on the lake, and the manufactured plaster was carried by the companies boats to McArthur's siding on the Whitemouth river near Westbourne, Man., from which point it was distributed. In 1904 a reorganization took place and the Manitoba Gypsum Company Limited bought out the original company, and operated the original mill for about one year when it was destroyed by fire. There were many factors which rendered the operation of a mill at the quarries very difficult; lack of rail transportation for bringing in supplies, and the impossibility of local power development made manufacturing costs very high. Satisfactory distribution could not be affected because of water transportation and poor terminal facilities at McArthur's siding. For these reasons the new mill was built at Winnipeg, where cheaper power and better distributing facilities permitted the industry being placed in a better position. The company continued to bring the gypsum rock by steamer to Totogan, from which point it was transported by rail to Winnipeg. This period was one of steady expansion as the product became better known and more universally accepted as a wall finishing material. Unfortunately, in 1909, this new mill was destroyed by fire, causing a serious set-back to the company, at a time when the steady growth of the western market gave every promise of the industry being placed on a profitable basis.

Jan 1, 1925

By John Petersen

Heap bioleaching technology has become well established for the exploitation of copper sulfide ores. Still, in many operations the rate of copper extraction is rather slow, often taking two years or more to recover 80% of the copper. Chalcocite, the most common secondary copper sulfide, leaches by a two-stage mechanism. The first stage is rapid, whereas the second stage has a high activation energy and proceeds slowly at ambient temperatures. Nonetheless, this rate is still considerably faster than what is typically realized in a full-scale heap. A comprehensive column bioleaching study of a chalcocite ore has shown that the chalcocite columns are leached in a zone-wise fashion. The first zone corresponds to the first stage of chalcocite leaching, where all ferric produced by the bacteria is immediately consumed and all acid entering with the feed solution is consumed within a relatively narrow band. The second stage of chalcocite leaching proceeds much more slowly in the wake of the first stage, within a zone that grows gradually over the entire length of the column. The overall rate of leaching is thus determined by the rate of acid supply into the column rather than by mineral or bacterial kinetics, at least until the entire column is engaged in second-stage chalcocite leaching. In full scale heaps, there is evidence to suggest that solution distribution favours channelling between relatively large clusters of material which are exposed only to stagnant solution. Reagents have to migrate into such clusters by diffusion, which retards the delivery of acid dramatically. Thus, we believe that the rate of chalcocite oxidation in heaps is governed by sideways diffusion rather than downward migration. Column experimental results have been reproduced with a comprehensive heap-modelling tool. The model predicts that by simply changing the length of the average diffusion channel from column conditions (a few cm) to heap conditions (tens of cm), extraction times can change from weeks to years under otherwise identical conditions.

Jan 1, 2003

By L. B. Berger

Tests and observations of a Diesel-powered locomotive used for under-ground haulage, in a-clay mine were made by representatives-of the Bureau of Mines .primarily to determine the composition of the exhaust gases produced by the engine under actual haulage conditions-and to determine the effects of the operation on the quality of the mine atmosphere. In addition to ascertaining these conditional t proved interesting to analyze the test, data in regard to certain other performance, characteristics of the engine. This report presents results of tests of the mine locomotive, prefaced by a brief resume of the performance characteristics of Diesel engines to facilitate discussion.

Jan 1, 1948

By R Simonato

It is now recognised that rotary sample division is by far the best laboratory tool for extracting subsamples from a lot of material. In terms of sampling theory, rotary division, by virtue of the fact that it can extract many increments from the lot during the division process, radically reduces the variance due to distributional heterogeneity in the sample being divided. There are a number of occasions in sample preparation when it is necessary to extract a subsample of a target mass. To do this with rotary dividers taking a fixed fraction of the starting mass is a tedious task. In response to this problem, a variable split sample divider has been designed and built for the mineral industry. This paper discusses the utility of the device and presents test data showing that the machine is capable of making accurate mass split while overcoming segregation in the material being divided.

Jan 1, 2008

By E. R. Palowitch, P. H. Broussard

The United States aims to achieve some modicum of energy self-sufficiency through means such as conservation, increased domestic oil and gas production, substitution by the electric utilities of coal or coaloil mixtures for oil and gas, and development of a viable synthetic liquid fuels industry. Coal's role in attaining this goal will necessitate doubling coal production by the end of the 1980's. And if the United States does in fact become the World's Saudi Arabia of coal, the total annual production to meet these domestic needs and export markets could double again by the year 2,000. As only a small portion of our Nation's reserves are recoverable by state-of-the-art surface mining methods, most of the coal produced in the future will have to be mined underground (Averitt, 1975). But this projected increase in coal demand is occurring in the face of a decade of radically decreasing productivity. Specifically, average worker productivity in underground coal mines has decreased from 14.2 tonnes (metric tons) per workershift in 1969 to 7.2 tonnes per worker-shift in 1979; and 95 percent of coal produced underground during this period was produced by room-and-pillar methods (U.S. Dept. of Energy, 1980). Although there is no complete agreement on the impact of recent Federal legislation, there is strong correlation between the dramatic decrease in productivity in underground coal mining and the implementation of the recent Federal mine health and safety regulations (U.S. Congress, 1969). A review of the wide range of coal mining research, development, and demonstration projects currently being funded by the federal government and by industry gives little encouragement for increasing worker productivity on room-and-pillar sections underground in the immediate future (Palowitch, 1978). Conversely, the opportunities for increasing production/productivity underground with longwall methods appear somewhat more encouraging. Although at least one longwall face in the U.S. did produce more than one million tonnes of coal in a single year, the national two-shift average production from one hundred or so longwall faces is about 1,000 tonnes per day (Huwood-Irwin Co., 1978 and Consolidation Coal Company, 1976). Clearly, there exists some real opportunities for improvement. One of these opportunities is to automate the cutter-loader.

Jan 1, 1981

By Alan E. Gallie

One of the requirements for the successful waging of war is an unlimited supply of iron ore. In the spring of 1941 the demand for iron ore was expected to exceed the supply. This was particularly so in the case of high-grade lump iron ore, essential to the open-hearth process of making steel. The bulk of Canada's iron ore was imported from the United States. At this time, Canada was making every effort to conserve United States funds for more vital purchases. For these reasons, the development of Canadian iron ore resources became of prime importance. Several companies undertook investigations and one of these examined the old Josephine deposit. Location The Josephine property is in the district of Algoma, in the Michipicoten area of the Sault Ste. Marie mining division of Ontario. It is 120 miles north of Sault Ste. Marie and 20 rail-miles east of Michipicoten harbour, on lake Superior (see Figure 1). Transportation in the area is furnished by the Algoma Central and Hudson Bay railway. The Michipicoten branch of this line passes within a mile of the Josephine mine. Michipicoten harbour provides a port through which iron ore is currently shipped. Power in the area is supplied by the Great Lakes Power Company, with generating plants on Michipicoten river, on Montreal river, and on St. Mary's river at Sault Ste. Marie. A series of transmission lines cover the district and one of these is connected to the Josephine mine by a 3 ½-mile branch line. History The Josephine property was staked by Alois Goetz in 1899. Before the claims could be recorded, the township in which they are located was given to the Algoma Central & Hudson Bay railway as part of a land grant. As a result, the ownership remained in dispute until August 24th, 1906, when a settlement was arbitrated by the Honourable Frank Cochrane. His ruling is interesting and is quoted in part.

Jan 1, 1947

By R. J. Marcotte, C. T. Eddy, R. J. Smith

The objectives of the investigation herein reported were to determine: (I) the S-curves for certain selected cast steels, (2) whether or not the published S-curves for wrought steels are satisfactory for use on cast steels of similar composition, and (3) to prepare hardenability curves of the selected cast steels. In order to make the final comparisons between cast and wrought steel more completely tangible, it was deemed advisable not only to determine S-curves for the steels submitted in the cast condition but also to roll some of the cast-steel test bars and determine comparison S-curves on such wrought material. This procedure eliminates the composition variable and makes it possible to reveal the differences resulting from plastic deformation of the cast structure in addition to providing the comparison with published data on wrought steels. Cast Steels The cast steels selected for the preparation of S-curves, or time-temperature transformation curves, were similar to S.A.E. series 1030, 2330, 4130 and 4330. Of these the 1030 was supplied by The Crucible Steel Casting Co., Cleveland, Ohio, and the other three by The Sawbrook Steel Castings Co., Lockland, Ohio. The steels were furnished in the as-cast condition. The manufacturers supplied the chemical analyses and the properties that could be obtained in the heat-treated condition—all of which is summarized in Table I. The metallographic and dilatometric procedures and equipment were in general standard. The specific technique employed was described in a report of the Steel

Jan 1, 1945

By Murray Jacobson

The Federal Coal Mine Health and Safety Act of 1969 established mandatory dust sampling of coal mines according to procedures prescribed in the Mandatory Health Standards, title 30, Code of Federal Regulations, part 70, published in the Federal Register on April 3, 1970. A laboratory was established in the Pittsburgh Field Health Group of the Bureau of Mines to process the coal mine dust samples collected by the mine operators. This paper describes the laboratory and presents the equipment and procedures used in processing these samples.

Jan 1, 1971

"Industry Guide 7 contains the Securities and Exchange Commission’s basic mining disclosure policy. It provides guidance for Registrants on various matters including the definition and disclosure of proven and probable reserves and the definitions of exploration, development and production stages. The definitions and disclosure instructions contained in this Guide apply to all public mining entities and their public disclosures. As NI 43-101 is law in Canada, the SEC allows mineral resources and mineral reserves prepared under CIM Definition Standards for issuers that are reporting in Canada but are also registered with the SEC. The SEC places conditions on the disclosure of these estimates. US shareholders are cautioned that the requirements under NI 43-101 and the CIM Definition Standards differ significantly from those of Industry Guide 7.Note: this Guide contains the Commission's basic mining disclosure policy. The definitions and disclosure instructions contained in this Guide apply to all public mining entities and their public disclosures pursuant to the rules of Regulation S-K. Questions regarding the application of these definitions and rules to specific situations should be asked of the Commission's mining engineers or geologists at either the Office of Engineering, Division of Corporation Finance, 202-272-3252, or the Branch of Geology, Central Regional Office, 303-844-1000.(a) Definitions. The following definitions apply to registrants engaged or to be engaged in significant mining operations:(1) Reserve. That part of a mineral deposit which could be economically and legally extracted or produced at the time of the reserve determination.Note: Reserves are customarily stated in terms of DoreD when dealing with metalliferous minerals; when other materials such as coal, oil shale, tar, sands, limestone, etc. are involved, an appropriate term such as Drecoverable coalD may be substituted.(2) Proven (Measured) Reserves. Reserves for which (a) quantity is computed from dimensions revealed in outcrops, trenches, workings or drill holes, grade and/or quality are computed from the results of detailed sampling and (b) the sites for inspection, sampling and measurement are spaced so closely and the geologic character is so well defined that size, shape, depth and mineral content of reserves are well- established.(3) Probable (Indicated) Reserves. Reserves for which quantity and grade and/or quality are computed from information similar to that used for proven (measured) reserves, but the sites for inspection, sampling, and measurement are farther apart or are otherwise less adequately spaced. The degree of assurance, although lower than that for proven (measured) reserves, is high enough to assume continuity between points of observation.(4)(i) Exploration StageDincludes all issuers engaged in the search for mineral deposit (reserves) which are not in either the development or production stage."

Jan 1, 2003

By Medhurst TP, Trueman R

The aim of the paper was to model numerically some aspects of the extraction of coal pillars by split and fendering. A two-dimensional elasto-plastic plane strain model with strain softening and interface mod- elling was used. The model was able to simulate the improvement of conditions experienced in lifting from the fender, when the roof adjacent to the fender has caved. In contrast, when a stook was left, providing support to a span of uncaved roof, the model pre- dicted the fender would suffer considerably more de- formation and strain.

Jan 1, 1992

Although the last decade has seen the growth of many new licencing and approval requirements for the exploration and mining industries, there remains in each State of Australia and the Northern Territory a predominant "Mining Act" containing provisions for the grant of exploration and mining tenements. What then are the rights and duties of tenement holders either by virtue of a Mining Act or through other approval and licencing mechanisms? What rights and duties does a person acquire when he is granted an exploration licence or a mining lease? In this paper I will attempt to cover these types of questions using in particular examples from New South Wales. I will also refer to a range of other subordinate approvals and licences which today's society requires and the need for ethics and recognition of liabilities.

Jan 1, 1995