Search Documents

The Bureau of Mineral Resources has been engaged in regional geological and geophysical field work in the Alligator River and Cobourg Peninsula area since 1971, following the discovery of major uranium deposits. Geophysical work commenced with a regional airborne magnetic and radiometric survey which was followed up by some helicopter and ground work in August 1973. The interpretation of the earlier radiometric work is presented in conjunction with the results obtained from the follow-up work. Analyses of 100 outcrop and drill core samples collected have provided basic information on the physical properties and concentrations of uranium and thorium in various rock types. The uranium determinations were made by X-ray fluorescence and delayed neutron analysis, good agreement being obtained between the two methods. X-ray fluorescence was the main analytical technique used because of its ability to produce both uranium and thorium determinations.

Jan 1, 1975

A research and testing facility has been developed at Simtars to allow the spontaneous combustion testing of coal on a large scale. In this adiabatic reactor, the coal particle sizing is closer to that which could be found in the goaf and therefore the reaction is more likely to simulate the underground situation. This allows aspects of the spontaneous combustion process and methods for detecting a heating to be investigated which cannot be done in an operational mine. Up to 18 tonnes of run of mine or crushed coal is loaded into the reactor and allowed to self-heat while the temperature and gas profiles within the coal pile are monitored. The gases evolved from the coal are analysed using a fixed gas monitor system and gas chromatography to determine which of the common mine fire indicators and ratios can be used to predict the onset and progress of coal heatings. Benchmarking of the inherent propensity of a coal to spontaneously combust at both the large- and laboratory-scale is also possible by comparing the sample against previously tested samples. It has been found that the coal particle size affects both the time it takes for the coal to react and the location of the developing heating. The heatings generate approximately one metre from the inlet but in the crushed coal case do not progress to an advanced heating stage until the æhot spotÆ migrates towards the coal surface where there is an increased oxygen supply. Physical properties such as the compressive strength of the coal also affect the heating size and the time it takes for a heating to develop. Higher strength coals appear to oxidise more slowly and therefore take longer to self-heat as oxidation of the coal is the heat-generating step in the spontaneous combustion process. The best indicators of the state of the heating were found to be CO make and GrahamÆs ratio which are independent of air flow. Investigation of a potential spontaneous combustion should begin as soon as the CO make or GrahamÆs ratio exceed the background levels. The results from the tests undertaken on a number of Queensland and NSW coals are reported here together with the implications for the mining industry.

Jan 1, 2005

By N. Pearson, F. Calizaya

PT Freeport's mine in Irian Jaya, Indonesia uses a number of 500 m (1,640 ft) long vertical ore passes to transfer ore from the open pit to the mill. The current tonnages moved are in the order of 125 kt/d (138,000 stpd) and this will be increasing to 240 kt/d (265,000 stpd). This amount of falling rock generates high pres¬sures in the ore bins, when ore feed is terminated the pressure is no longer constrained resulting in back blasting of materials and air the ore passes. Three methods were tested to try and eliminate or reduce this problem; recirculation the entrained air, widening of the orepasses and relieving the pressure the back blast. The final method proved to be the most effective in the short term. As a long term so¬lution the orepasses are currently undergoing widening.

Jan 1, 2000

PT Freeport's Mine in Irian Jaya, Indonesia uses a number of 500m long vertical ore passes to transfer ore from the open pit to the mill. The current tonnages moved are in the order of 125 ktpd and this will be increasing to 240 ktpd. This amount of falling rock generates high pressures in the ore bins, when ore feed is terminated the pressure is no longer constrained resulting in back blasting of materials and air up the ore passes. Three methods were tested to try and eliminate or reduce this problem; recirculation of the entrained air, widening of the orepasses and relieving the pressure of the back blast. The final method proved to be the most effective in the short term. As a long term solution the orepasses are currently undergoing widening.

Jan 1, 1998

By V. Grujic, M. Grujic, D. Salatic

"Two areas are involved in the research work of the comminution process (crushing and grinding). The first one involves the changes of the size class distribution values that are definded by the differential equations in the function of the ore property and working conditions. The second area involves the comminution of the different levels in order to optimize the working parameters and to decrease the operational costs in the grinding process.We have studied, in detail, the possibility of functioning the crusher at the maximal loading, over 4500 kN, ball mills with diameters larger than 5.0 m and semiautogenous mills with diameters larger than 10.0 m.Using the computers, we have achieved the maximal loading range of the crusher, over Fc ? 4500 kN in the crushing process. In the grinding process, using the adequate differential equations in the automation process, we have established the correlation between the pulp mass capacity in the mill, pulp dencity, ore fineness in the pulp and recirculating ore charge.With the appopriate text, equations and graphs, this paper shows the results of our several years research work in the laboratory and in the ore comminution plant of Majdanpek Copper Mine."

Jan 1, 2003

By T. J. Close

On September 10, 1991, Secretary of the Department of Interior Manuel Lujan deleted the Silver Peak Range North Wilderness Study Area from the list of U.S. Bureau of Land Management lands in Nevada to be considered for wilderness designation. This decision was based in part on the U.S. Bureau of Mines mineral investigation of the wilderness study area which found that it has indications of precious metals resources. The following is a summary of the results of that mineral investigation. The study area lies between the Silver Peak and Dyer mining districts of west-central Nevada. The Silver Peak mining district, to the east, has a long mining history dating back to 1907 when precious-metals-bearing veins were discovered. The major producer in the Silver Peak district was Sunshine Mining Company's Sixteen-to-One silver mine. During the Bureau's study the Sixteen-to-One mine was operating; it has since been idled due to low silver prices. Precious metals-bearing veins were discovered in the Dyer district, to the west of the study area, in the 1860's. Mineral activity in Dyer district consisted mainly of prospecting. The Silver Peak study area itself has no mining history and contains only a few mining claims, but the Bureau examined 13 mineralized sites, most previously unknown and unclaimed. These sites are along two zones that cross the study area from the Silver Peak to the Dyer mining district. The two zones transect a volcanic center of fractured and altered rocks that contain epithermal veins of quartz, calcite, and jasperoid with gold, silver, and base metals. At the surface these veins are poorly defined and poorly mineralized. The more than forty veins examined in the study area are as thick as 17 feet and as long as 1,000 feet. Samples from surface exposures of these veins contained as much as 0.02 ounce per ton gold, 2.1 ounces per ton silver, 1.0 percent copper, 2.6 percent lead, and 0.4 percent zinc. Analyses of the Bureau data disclosed no vein large enough or of high enough grade to be classified a mineral resource. However, most do have indications of silver-and gold-bearing resources at depth. Subsurface exploration had to be done on the vein at the Sixteen-to-One mine to outline reserves (a vein averaging about 22 feet thick and containing 6-to 7-ounces per ton silver); the same is true of veins in the Silver Peak Range North Wilderness Study Area.

Jan 1, 1993

By T. J. Close

The Silver Peak Range North Wilderness Study Area was deleted from the list of US Bureau of Land Management lands in Nevada to be considered for wilderness designation. This decision was based in part on the US Bureau of Mines mineral investigation of the wilderness study area which found indications of precious- and base-metal-resources. The study area lies between the Silver Peak and Dyer mining districts of west-central Nevada. The Bureau examined 13 mineralized sites, most of which were previously unknown and unclaimed. These sites are along two zones that cross the study area from the Silver Peak mining district to the Dyer mining district. The two zones transect a volcanic center of fractured and altered rocks that contain epithermal veins of quartz and calcite with gold, silver, and base-metals. At the surface, these veins are poorly defined. Exposures of the more than forty veins examined were as thick as 17 ft and as long as 1000 ft. Samples from these veins contained significant amounts of precious- and base-metals-as much as 0.02 oz per ton gold, 2.1 oz per ton silver, 1.0% copper, 2.6% lead and 0.4 % zinc. No vein large enough or of high enough grade to be classified a mineral resource was disclosed by the sample data. However, most do have indications of precious- and base-metal-resources at depth. Subsurface exploration of some of the veins is recommended.

Jan 1, 1995

By Tomb. T. F., R. A. Haney

During the past several years, the Mine Safety and Health Administration (MSHA) has conducted studies in underground mining operations to obtain information on occupational exposures to diesel particulate (DP), mine environmental DP levels and on the effectiveness of methodologies used to control DP. The studies conducted were representative of four coal mines and 10 metal mines. The metal mines included two lead-zinc mines, one limestone mine, two potash mines, one zinc mine and four salt mines. Three of the four coal mines were using disposable diesel exhaust filters to remove particulate from the exhaust and one was using a reusable wire mesh filter. Results of these studies indicate that average DP levels in coal mines not using exhaust filters range from 0.9 to 2.1 mg/m3, The use of exhaust filtration devices reduced these levels by about 50% to 90%. Studies conducted in metal and nonmetal mines showed average DP levels ranging from 0.3 to 1.6 mg/m3.

Jan 1, 1996

By T. F. Tomb

on' January 6, ,1992, the Mine Safety and Health Administration (MSHA) issued an Advanced Notice of Proposed Rule Making (ANPRM) for diesel particulate (DP). The ANPRM identified five areas where the Agency was seeking additional information to assist in the rule making process. These areas were exposure 'limits, risk assessment, consideration of other information, sampling and monitoring methods, and feasibility. The period for submitting information relative to the ANPRM closed July 10, 1992. Prior to issuance of the ANPRM, the agency was involved in conducting studies to evaluate sampling and control technologies and to gather information with respect to occupational exposures to diesel particulate in underground mining operations employing diesel-powered equipment. Since issuance of the notice, additional studies have been conducted to provide supplementary information in these specific areas. Results of these additional studies indicate that average DP levels in coal mines not using aftertreatment range from 0.9 to 2.1 mg/m3. Aftertreatment devices can reduce these levels by approximately 50 to 90 percent. Studies conducted in metal and nonmetal mines showed average DP levels ranging from 0.3 to 1.6 mg/m3.

Jan 1, 1994

By Ken Schei, Martin Reed, Samuel Bowser, John Wright

From October 18 through October 21, 2001, United States Antarctic Program blasters opened ten access holes for research divers in 11-ft. thick sea ice at Explorers Cove, McMurdo Sound, Antarctica. During this project, a blasting seismograph with a hydrophone accessory was used to monitor the underwater shock waves associated with the blasting technique. Shock wave values averaged 42.3 psi for initial (cratering) shots and 5.9 for subsequent clearing shots, indicating that the ice absorbs most of the shock wave. The results also provide data for refining safety protocols for divers and for the protection of marine biota.

Jan 1, 2003

By J. B. Newsom

DURING July and August, 1931, the Bloomington Limestone Co.,. at Bloomington, Ind., ran a single wire saw on ledge No. 2 at Maple Hill quarry. The ledge was hard rock, much harder than the average Indiana limestone. It was opened at two ends for a depth of about 20 ft., leaving a 130-ft. section between. During the tests 21 cuts were made in this ledge, to an average depth of 10.42 ft., for a total effective cutting area 028,445 sq. ft. The actual area sawed was about 20 per cent higher, as we did not level down in the center, preferring to cut deeper on the ends. The various cuts were carefully, logged, and the results plotted. A study of these results is interesting, as it enables a forecast of probable future costs to be made, and also because it points out the limitations of wire saws, and the lines development should logically take. Some of the inferences to be drawn are discussed below. Best Length of Cut.-No. trouble was due to length of cut, except that we could not easily level down a long cut, and it is probable that longer cuts, say up to 200 f t., can be made. Obviously, longer cuts will result in a higher sawing rate, in square feet per hour if- they do not cause stoppages. Working Higher Ledges.-The cuts averaged 10.42 ft. high by 130 ft. long. A study of several logs indicated that during only about 15 per cent of the cutting time was the saw cutting to its full efficiency; that is, during about 85 per cent of the time the saw was bedding in at the ends and not cutting well in the center, or the ends were below the floor line and only part of the wire was doing effective cutting. This does not mean that the wire was cutting to only 15 per cent of its capacity, but it means that during about 85 per cent of the time part of the cutting was being wasted. If higher ledges had been worked, the wire would have cut to its full efficiency a large part of the time, as it would have had a greater distance; to saw after it had bedded in to the ledge before the ends went down below the floor level. The exact saving to be expected cannot be calcu-lated, but it would be large, if really high cuts were made.

Jan 1, 1932

By G. H. Ruggles

POPULAR opinion, as it might be termed, has always been of the trend that a flotation reagent added to the ball mill during grinding would be more thoroughly mixed with the pulp and for that reason more effective in the production of low tailing. That there are other effects, inimical to good flotation, when using so-called chemical reagents, is brought out by the series of tests outlined in Table 2. It was defi-nitely proved that if either the T. T. mixture (20 per cent thiocarbanalid-80 per cent orthotoluidin) or po-tassium xanthate were added to the ball mill the result-ing flotation concentrate would be lower in copper and higher in insoluble than the concentrate produced by adding these same reagents without the ball mill cir-cuit. With the T. T. mixture four sets of tests were made. The screen analyses of the flotation feed show that there was very little difference in the original grind-ing. When the T. T. mixture was added to the head of the flotation machine the flotation concentrate had a little over 61 per cent solids -200 mesh. If the mix-ture was put into the ball mill the flotation concentrate had but 40.7 per cent of the solids -200 mesh for one set of tests, and 49.0 per cent for the other set. With the mixture at the head of flotation the total concen-trate was high in copper (34.715 and 36.525 per cent) and low in insoluble (13.20 and 11.61 per cent). The assay of the concentrate when the T. T. mixture was introduced into the ball mill was what might be termed low in copper (29.389 and 30.833 per cent). In one of these 'sets of tests (periods 8 to 11, third column) the insoluble was high, 16.81 per cent. The other run (peri-ods 12 to 15, fourth column) for some unknown reason shows a low insoluble, 12.72 per cent. With similar grinding the addition of potassium xan-thate to flotation produced a concentrate having 62.8 per cent -200 mesh, whereas with the potassium xanthate added to the ball mill the flotation concentrate was very coarse, only 36.4 per cent passing 200 mesh. The difference in the total assay of the concentrate is remarkable ; 35.847 per cent copper when the xanthate went to flotation and 30.44 per cent copper when the xanthate was added to the ball mill; insoluble, 10.94 per cent in the former instance, as 22.15 per cent in the latter.

Jan 8, 1927

By Edward R. Torak

The Ohio Coal Testing and Development Research Facility (OCTAD) was commissioned in 1992 by the Ohio Coal Development Office and the Ohio Power Company to support evolving process technologies that will lead to increased environ- mentally sound use of coal. OCTAD is equipped with advanced physical concentration devices and processes capable of beneficiating coal to levels beyond conventional practice. The first task of OCTAD operators was to test the cleanability of the Meigs Creek Seam Coal in advanced circuitry and compare the results to conventional cleaning levels. In testing the seams, OCTAD circuitry was configured to produce middlings on the coarse and intermediate size fractions. These middlings were subsequently crushed to a finer size (28M x 0) and subjected to cleaning in fine heavy-media cyclones and advanced froth flotation circuitry. Nearly thirty-six full-scale production runs at various operating conditions were completed during the campaign. The results of the test program are examined in this paper.

Jan 1, 1995

By R. Kent Comann

Introduction This article describes ways to maximize employment potential for those looking for a job in the minerals industry. Advice on the right way to prepare a resume is followed by tips on where and how to look for a job and ways to make the best of an interview. Information on current salaries is also included. RESUME NAME: Give home and college addresses and telephone numbers, ADDRESS: if still in school. Otherwise, give home address and TELEPHONE: telephone plus business telephone number. JOB OBJECTIVE: What do you want to do? EDUCATION: List degree(s), name of college(s), location(s), and date(s) degree(s) received or to be awarded. Do not list your high school but do include postgraduate education, training, or seminars. WORK EXPERIENCE: List your most recent experience first, and the rest in reverse chronological order. Include dates (month and year) and company names. First show the entire time spent with each employer, then list the various jobs (with dates and duties) you may have had with this employer. MILITARY SERVICE: List dates, branch of service, and duties. If you did not serve, delete this section. COLLEGE ACTIVITIES: Show organizations, sports, and offices held. Only list these if you are a graduating senior, otherwise delete this section. PERSONAL DATA: List age, marital status, height, weight (optional), foreign languages spoken, professional memberships, and health (if good or excellent, otherwise do not mention it in the resume). If you prefer a certain location and would not accept a job anywhere else, list the location desired. Otherwise, do not restrict yourself. Also list special skills, hobbies, or interests that will help sell you to the company. Be brief in this section and use good judgement as to what you say. REFERENCES: Furnished on request. Resume Guidelines There are some things to remember when preparing a resume. These include: • Limit your resume to one page, unless you have a lot of experience. Then it should be a maximum of two pages. • Use 8.5 x 11 plain bond paper, white or off-white. Stay away from colored paper, odd size paper, and cute resumes. They are counter-productive. • Make certain your resume is typed professionally. Be sure to check for spelling, grammar, and typographical errors. • Have your resume reproduced by copier or printing shop. Do not use carbon copies. • Keep your sentences and remarks short and punchy. Use action verbs. • Have a good layout that is easy to read, brief, and uncluttered. Allow some white space in your resume. There are also some things you should not do when preparing a resume. These include the following: • Do not include a photograph or mention your religion, race, or sex. • Do not leave gaps of time unaccounted for in your resume. • Do not include your college transcripts with your resume or list all the courses you took in college. • Do not list all the articles you have written. Only list one or two, if appropriate for, say, a research and development job. • Do not include reference letters with your resume. Any good, prospective employer will make telephone reference checks. • Do not use "Curriculum Vitae," use "Resume." • Do not include unnecessary data such as your social security number, passport number, or PE registration number. If you are a PE or EIT, be sure to mention that in your resume. Do not mention US citizenship or US work permit unless you have a foreign education or are not a native US citizen. • Do not include present salary or salary requirements. This will come out in the interview. • Do not use the word "I" in your resume or refer to yourself in the third person. • Do not lie, distort, exaggerate, or editorialize in your resume. • Do not have your resume prepared by an outside resume service. This is unnecessary, costly, and generally not effective.

Jan 2, 1985

By Porfirio Pinto Linares

El presente texto señala la paragénesis y zoneamiento en el yacimiento de Morococha. Dicho distrito está ubicado al este de Lima, cuyos principales productos minerales son el zinc, cobre, plata y plomo. Para dicho estudio geológico se empleó los valores de ensayos para el cobre, plata y zinc principalmente; en algunos casos, los valores para el plomo; de las vetas estudiadas. En el estudio de la paragénesis no se ha hecho un estudio completo al microscopio de la secuencia de los minerales de la veta. Se han aprovechado únicamente, las mejores exposiciones en el subsuelo que ofrecen evidencias excelentes para deducir las características principales de la paragénesis.

Mar 1, 1965

By Porfirio Pinto Linares

El presente texto señala la paragénesis y mineralización del distrito de Morococha. Dicho distrito está situado al Este de Lima, en el Perú central y sus principales productos minerales son el cobre, zinc, plomo, plata. Su mineralización está relacionada con el intrusivo del mismo nombre, encontrándose el centro más efectivo de la mineralización en el stock San Francisco, mientras que la paragénesis observada en las estructuras estudiadas es compatible con el zoneamiento existente; ya que las primeras capas depositadas son de cuarzo y pirita, siguiendo la esfalerita, enargita, calcopirita, tetrahedrita, esfalerita y galena; rellenando las cavidades se encuentran los carbonatos.

Mar 1, 1965

By Augusto Weberbauer

El presente texto revisa la geografía e hidrografía del Perú. El territorio peruano forma parte de dos sectores fundamentales del continente sudamericano: los Andes y las Llanuras Bajas del Oriente. Asimismo, nuestra geografía se divide en tres zonas, una occidental, otra media y otra oriental, denominándolas respectivamente: Costa, Sierra y Selva. Las llanuras y colinas de ambos lados, el del Océano Pacífico y el de Amazonía, pertenecen a la "Costa" y "Montaña" respectivamente, en las que se encuentran las partes inferiores de las zonas andinas. Dentro del sistema de los Andes tenemos : Los Andes del Titicaca y de las mesetas volcánicas, los Andes del Apurímac, los Andes del Alto Marañón, Los Andes del Chamaya. En el sector Occidental tenemos la cuenca de Titicaca y Cordilleras orientales y el Nudo de Vilcanota. De otro lado, dentro de las condiciones orográficas e hidrográficas se divide la Costa en cinco partes: de Arica a Pisco, Pisco a Trujillo, Trujillo a la Punta Pariñas, la Punta Pariñas a Tumbes y de Tumbes a Zarumilla.

Sep 1, 1974

La presente investigación revela aspectos sobre los métodos geoquímicos aplicados a la exploración de depósitos minerales, como las aplicaciones prácticas e indicaciones sobre de las diversas técnicas empleadas en el campo y y laboratorio. La exploración química de los depósitos minerales como método de prospección, comprende la investigación e interpretación de anomalías químicas relacionadas a la mineralización dentro de varias sustancias naturales como rocas, aguas y vegetación para así localizar depósitos minerales ocultos. La naturaleza de estas anomalías se divide en dos grupos: las anomalías primarias formadas durante el periodo de mineralización y las secundarias, formadas por la destrucción y dispersión del depósito metalífero durante el ciclo de intemperismo y erosión. Sin embargo, existen algunas anomalías de naturaleza "residual" o "vestigial", las cuales son descubiertas mediante el muestreo sistemático de rocas o de los suelos que de ellas derivan. A esto se suma, la dispersión de elementos en solución puede dar origen a muchas variedades de anomalías secundarias que tienen importancia en la exploración geoquímica como las dispersiones secundarias en las aguas de fuentes, pozos y aguas corrientes, en las cajas de cuerpos mineralizados; en coberturas de carácter no residual sobre y cerca de depósitos mineralizados y aquellas dispersiones secundarias en vegetales. Paralelamente a esta exploración geoquímica, tenemos otras métodos comom los técnicas colorimétricas, basadas en reactivos que indican cambios de color y los de análisis espectográfico, que complementan paulatinamente dicho proceso minerológico.

Jul 20, 1956

By César Fuentes

En 1961, el Banco Minero, la Sociedad de Minería y la Dirección de Minería, deciden efectuar un estudio de factibilidad de la instalación de una refinería de zinc en el país. En este sentido, el objeto del texto describe la evaluación de dicho planeamiento comprendido en tres procesos: El proceso electrolítico, overtpel y el imperial smelting. Asimismo, el trabajo refiere estudios adicionales como la ubicación, los recursos concentrados de zinc, abastecimiento de agua, mercado mundial de zinc y el mercado nacional de fertilizantes fosfatados. Para la realización de los análisis, se han incluido programas de producción y costos de operación. Finalmente, la valorización de la producción y de los concentrados se han efectuado según las cotizaciones promedio de los años 1958- 1962 de la Bolsa de Metales de Londres.

Aug 20, 1965

Jan 1, 1932