Search Documents

The ready solubility of gold in dilute aqueous solutions of the cyanides of the alkalies or alkaline earths provides a convenient method for the separation of the precious metal -from the large surplus of associated materia1. The finely ground ore is pulped with a weak solution of cyanide, agitated to dissolve the gold, filtered and washed. The lowgrade filtrate is then clarified and the gold precipitated by some electronegative agent, the most usual being finely divided zinc or zinc dust. The slight precipitate is collectedon some form of filter coated with a filter aid, the filter cake being then known as "gold slime".A typical analysis of this slime is given in Table 1.

Jan 1, 1956

By A. E. Kehew

Earth resistivity surveys using the Wenner electrode configuration were made in unmined areas and reclaimed spoils at three surface lignite mines in western North Dakota. The study sites were the Center, Indian Head, and Falkirk Mines. Automatic interpretation of the curves was accomplished with the method of Zohdy and Bisdorf (1975). Overburden materials become more homogeneous with respect to resistivity during the mining and reclamation process. The spoils curves show localized hetero-geneities probably related to discontinuous moisture content variations in the spoils. Consistent resistivity differences in spoils occur between mines with over-burdens of different mineralogic compositions. Groundwater chemical composition in terms of total-dissolved-solids (TDS) is inversely correlated (r=-0.61) with apparent resistivity at the 80-foot spacing from a survey centered at a piezometer screened near the base of the spoils. Better inverse correlation is probably pre-vented by high variability in TDS within the spoils groundwater. A useful predictive relationship may be the plot of mean apparent resistivity at the 80-foot spacing for ar. entire mine against mean TDS for all wells in spoils at that mine. Data from more mines are needed to test the hypothesis.

Jan 1, 1982

This paper discusses the social and economic impact of mining, and in particular goldmining, on New Zealand. The range of topics covered and their complexity has confined us in this paper to highlighting the main points of concern û a detailed report is under preparation. A major problem in undertaking this study was the lack of hard data on important environmental, economic and social issues and if there is to be effective planning in the area of natural resource use this situation must be rectified. The following conclusions were drawn: Goldmining was very important in shaping New Zealand's early social and economic development, providing wealth, employment and impetus for social change.Foreign investment and technology has been an essential element in New ZealandÆs economic development.Mining is a small industry at present by this must not be allowed to obscure its potential to broaden New Zealand's economic base and provide foreign exchange.With modern methods, development of mineral resources and environmental protection are not incompatible but certain unique and irreplaceable areas must be preserved.There are problems in evaluating mining and other projects because different groups hold different values, and arguments often hinge on the valuation of costs and benefits rather than the technical aspects of the analysis.Mineral exploration is a high risk business and the potential returns must be sufficient to attract capital if New Zealand's mineral resources are to be developed.A resurgence of goldmining will clearly have obvious benefits for Waihi but the local community must plan carefully for their future. New Zealand will also gain valuable foreign exchange required for higher levels of economic activity.

Jan 1, 1981

By Jorge Díaz A

El presente texto revisa los métodos utilizados en las minas de tajo de abierto como son la perforación, disparo y seguridad y así mejorar los standars y el rendimiento futuro en la industria minera. Respecto al primer método empleado, se analizan los factores que afectan el rendimiento de brocas y cómo dicho factores varían, impidiendo la adaptación de prácticas universales de perforación. Asu vez, estos mismos permiten seleccionar el tipo de broca adecuado y mejorar el máximo rendimiento del mismo. En cuanto la voladura y los explosivos, se revisan las variables fundamentales que ejercen una influencia sobre el resultado de un disparo y así realizar un estudio comparativo de los agentes explosivos en uso, tratando de interpretar el mecanismo de la explosión y a la vez aplicarlo a las diferentes formaciones presentes en Cerro. Finalmente, se describe la organización del sistema de seguridad y las obligaciones de este comité en la industria minera.

Aug 20, 1965

By William J. Krisko

This contract final report summarizes the design, fabrication and testing of canopy air curtain devices under Bureau of Mines Contract H0232067. The canopy air curtain device is designed to reduce the level of respirable dust exposure to a continuous mining machine operator while having a minimum effect on operator safety, mobility and comfort and being compatible with mining equipment. This contract was devoted to the development of a device which utilizes an invisible curtain of air to envelope a mining machine operator's breathing zone with filtered air to provide respiratory protection. Various concepts were evaluated by means of laboratory tests. One concept was selected and was tested on various mining machines at underground sites by means of MSA personal samplers. The canopy air curtain was found to be effective. The percent reductions over the ambient dust concentrations were about 30 to 75 percent depending on the amount of time the operator spent under the air curtain. At one test site, the device enabled the mining machine to operate within compliance. Donaldson Company is presently working on the commercial production of the device.

Jan 1, 1975

By F. R. Hensel

The present paper describes a number of experiments with fine silver, coin silver, silver-cadmium oxide and silver-nickei-copper compacts, prepared by powder metallurgical methods. The test data are of a preliminary nature, since most of the work was exploratory. Fine Silver Eject of Compacting Pressure on Hardness and Density during Cold and Hot Pressing The cold-welding properties of silver have received considerable attention and the welding characteristics are functions of such variables as: cleanliness of metal particles (impurities and adsorbed gases), chemical nobility of particles, plasticity and hardness, particle assortment, particle shape, particle porosity, apparent density, temperature, pressure, time, recrystalliza-tion characteristics. Chemical nobility, plasticity and low temperature of recrystallization after work-hardening are responsible for the excellent low-temperature bonding properties of silver. Several series of compacts were pressed at pressures of 5, 10, 20, 30, 40, 50, 60 70 and 80 tons per square inch, at temperatures of 32°C. (room temperature), l00°, 2000, 300°, 400°, and 450°C. Silver powder of minus 325-mesh, produced by displacing silver from a nitrate solution by means of copper, was used. The density was calcuiated from accurately measured and weighed compacts. The hardness was measured on the Rockwell F scale. The investigation shows that an increase in pressure promotes a higher density and hardness regardless of pressing temperature, up to a temperature of 400° C. The pressure-density curves at various pressing temperatures are shown in Fig. I, the pressure-hardness curves at various pressing temperatures, in Fig. z. The greatest increase in both hardness and density was obtained in the pressure range of 5 to 20 tons per square inch. A compact from each series was annealed at 300°C. in air, for various lengths of time. The hardness values after annealing are shown in Table I. A minimum hardness was obtained after one hour of annealing. No change in density occurred during annealing. The maximum density was obtained at 80 tons per sq. in., and at this pressure the hardness is equal to that of hard-drawn wrought

Jan 1, 1945

By Erdal Ünal

The computer program introduced in this paper is based on design guidelines developed for selection of support systems used in mine roadways. The support types considered include rock bolts as well as rigid and yieldable steel arches. Using the computer program, the design engineer can select the type, pattern and specifications of the support systems suitable for various roof conditions. The concepts utilized, assumptions made, support selection criteria and description of the computer program, developed for the PC, are included.

Jan 1, 1989

By James F. Kemp

Jan 1, 1914

By C. M. McKinney

This report contains Bureau of Mines routine analyses of 492 samples of crude petroleum from 470 United States oilfields, each of which produced 2,500 barrels a day or more during at least 1 of the years 1946-56. The fields are listed alphabetically by State and field names in table 1, with information on the geographical and geological sources of the samples. Table 2 summarizes the general characteristics of the crude oils and analytical and computed data determined from the analyses. A previous report 4 contains similar analyses of 283 important United States oilfields; some of them are repeated in this report. Many fields for which analyses previously were published are represented by new analyses, which include data not previously reported. Refractive index nu and specific dispersion, ng minus nD divided by the density, for some of the distillate fractions are included in the analyses of 316 of the crude-oil samples. This is the first Bureau of Mines report on analysis of crude oils to contain such data, and their use in calculating hydrocarbon-type composition of the fractions is explained.

Jan 1, 1957

For the third successive year it appears that demand for platinum will exceed supplies of newly-mined metal, forecasts Johnson Matthey in its "Platinum 1987 Interim Review." Based on data available at the end of August 1987, Johnson Matthey estimates that western world demand for platinum could exceed 93t (3 million oz) for the first time ever in 1987. Given a likely increase in demand of 4.3t to around 94t (140,000 oz to around 3.02 million oz), up by about 5% over 1986, there would be a 1.8- to 2.2-t (60,000- to 70,000-oz) shortfall in 1987 supply. South African mines enjoying undisrupted production last year after strikes affected Impala's output in 1986. The rate of increases in western world supplies, though, has probably not kept pace with the growth in demand. A downturn in US demand for platinum was counterbalanced by substantially increased purchases from Japanese and Western European consumers of the metal. Total imports of platinum into Japan in 1987 may have reached a record level of 45t (1.45 million oz). The largest source of demand for platinum remains its use in autocatalysts US and Japanese auto manufacturers reduced their platinum purchases in the wake of falling car production. Therefore, a small decline in overall 1987 sales of perhaps 780 kt (25,000 oz) was expected in 1987. Western European demand, however, rose strongly as a result of increased output. The spread of exhaust emission control regulations has sharply boosted the number of cars equipped with three-way catalysts containing platinum and rhodium. Western European auto makers probably needed 5.6t (180,000 oz) of platinum last year, a 50% increase over 1986. The jewelry industry, the second largest user of platinum, increased its offtake of platinum in 1987. Japan, the key to the jewelry industry's consumption of platinum, could absorb 24.8 to 26.4 (800,000 to 850,000 oz) in 1987, compared with 23t (740,000 oz) in 1986. Platinum has wide and diverse applications in industry. Other major users are the chemical, glass, electronics and petroleum industries. They were expected to increase their aggregate demand by about 1.8t (60,000 oz), or 11% in 1987. Investment demand for small platinum bars and coins of up to 311g (10 oz) dropped back in relatively inhospitable conditions. This, after rapid increases in recent years and a surge in US demand in 1986. However, Japanese investors purchasing bars weighing 500g or 1 kg (16 to 32 oz), and considered more speculative, recovered last year. Over the first eight months of 1987, platinum performed strongly on the open market with average prices well up from 1986 in dollar terms. But the increase was less marked where measured in sterling or yen. Platinum ad¬vanced by $3.70/g ($115 per oz) between Jan. 1 and mid-September with the average price having been surpassed only in the heady days of 1980. Johnson Matthey believes that supply and demand appear likely to keep more or less in step on a gently rising path. The recent open market volatility will continue with prices fluctuating widely over short periods. Writing in mid-September, and basing its view on the tangible evidence of platinum's price fall since the review was written, the company's assessment of price prospects is unchanged. Demand for platinum remains strong all-round. In October, imports of platinum into Japan were exceptionally high. And in the US and Japan there was a marked resurgence of demand from private investors. Although market sentiment may have been influenced in part by the news of several potential new platinum mines in South Africa, the full effects of these prospects on supply, even if they were all to materialize, would not be felt before the early-mid 1990s, Johnson Matthey said. According to the review, no radical change in platinum supplies is discernible in the near-term. Incremental growth from South Africa can be expected as the major producers continue to make the most of their existing resources. The Soviet Union may be keener to sell than it appeared earlier in 1987, especially if prices hold up, but a substantial increase is improbable. Canadian supplies are not capable of much variation from present levels. The palladium-rich Stillwater mine will make a modest contribution. Referring to the investment market, Johnson Matthey concluded that despite this year's reduction in sales of small-denomination investment products, platinum does appear to have established itself with private investors. Bearing in mind how business multiplied in comparatively unfavorable conditions before 1986, it is reasonable to look for a resumption of growth once the climate improves.

Jan 2, 1988

By Bujtor G. J, McMahon D. W

This guide to the understanding of ore reserve estimation is the revised version of a report with a similar title circulated within the CRA Limited (CRA) group of companies in mid-1980. It is the principal result to date of an Ore Reserve Study commissioned by CRA in late 1977.This guide to the understanding of ore reserve estimationis the revised version of a report with a similar titlecirculated within the CRA Limited (CRA) group ofcompanies in mid-1980. It is the principal result to dateof an Ore Reserve Study commissioned by CRA in late1977.The study was prompted by two ore reserve situations.The Zinc Corporation and New Broken Hill Consolidated,Broken Hill, had reached the point of havingto find a replacement 'for their traditional ore reserveprocedure and Mary Kathleen had to admit publicly thatore reserve predictions would not be realized. Thesewere not however the only problems to be looked at. Asmentioned more fully later, other ore reserve situationswere known, or were met during the study, in copper,gold and nickel as well, where poor realization: expectationratios had ranged from embarrassing to disastrous.These made it clear that ore reserve estimation had to belooked at afresh.The fresh look has resulted in a broadening of theconcept of ore reserve estimation from its traditionalpurely computational basis to an approach embracingall the many things that can affect expectation andrealization as essential factors. Hence this guiderepresents a gathering together of what has been learnedand what should be known to all those concerned withore reserves in any of its diverse aspects.The study has been marked"by a number of changesof thinking. At first the aspects that appeared to requireattention were two; recognition that an ore reserve statementwas an estimate, not a precise calculation; and asearch for im improved estimation procedure adapted tolow grade ores with narrow economic margins. Threeyears later the view was that the need was to incorporateinto ore reserve estimation all relevant aspects of theproposed mining operation from choice of a samplingmethod to sales contract specifications.This study is thought to be unique in being frankabout weaknesses in ore reserve estimation and intreating failures not as natural disasters (like drought orflood, which have to be endured) but as potentiallyavoidable. It has led to three principal conclusions.

Jan 1, 1982

By Daniel G. DiCanio

This report describes a computer-based model for estimating the tangible costs of injuries and deaths from work-related accidents in underground coal mines. The study undertook to identify and quantify the elements of accident costs, including field visits to coal mines, insurance carriers, and public agencies. The mathematical models developed for each tangible element of accident cost are presented in Volume I of the report. A listing of the computer programs which comprise the model and instructions for using the programs are presented in Volume II. Statistical distributions of mining family characteristics, data on 95 miners killed in underground accidents, and other basic data used to develop the model are presented in Volume III. Application of the model to a data base of 9,286 accidents which occured in underground bituminous coal mines during 1974 yielded a total of $56,900,000 in tangible costs to industry, mining families, and public agencies. Loss of income to the families of miners injured or killed in these accidents accounted for 47 percent of the total.

Jan 1, 1976

By W. D. Mcmillan

Kaolin, or china clay, is the term applied to a group of hydrous aluminum silicates. Because of its purity, light color, and refractory properties, kaolin is used extensively in the manufacture of high-grade ceramic wares and as a filler by the rubber and paper industries. Although there are numerous pottery and enamelware plants in Texas, and large rubber and paper industries; all of the kaolin used in these plants is from other States, There are two known occurrences of kaolin in Texas, namely, the Leakey deposit in Real County and the several deposits of the Medley district in southern Jeff Davis County. An investigation of the Mueller kaolin deposit in the Medley district was undertaken by the Bureau of Mines. Following an examination of this deposit by W. D. McMillan, engineer in charge of the Texas field office of the Bureau of Mines, a proposal was made to investigate the deposit by diamond core drilling.

Jan 1, 1949

By J. Thompson

Paper written on project work carried out in partial fulfilment of B. Eng (Mining Engineering) degree A study into the stability of strike gullies at TauTona mine was to be carried out. In reaching the conclusions to follow, a three-stage process was followed. ?A literature study as well as discussions with management and workers alike to gain their inputs and perceptions. ?An ESH Department survey into the history of transgression from proper mine standard in TauTona strike gullies. Unfortunately records were found to be scarce and obscure and the importance of better inter-departmental recordings cannot be stressed enough. ?An underground survey of 11 pre-selected gullies distributed in both the UCL and LCL reef horizons. This stage is to carry the greatest weight in the points to be brought forward in this report. The process highlighted and ranked the following areas as the most critical role players in the deterioration of strike gullies: ?Poor blasting practice ?Sub-standard siding depth and lead-lags ?Split sets ?Off line gully development ?Adverse geological features. The following has been suggested to the mine to help reduce strike gully instability. ?Where possible, maintain lead-lags below 7 m?else increase the siding depth to suit. ?Decrease the gully width standard to 1.2 m (especially in ?high risk areas?). ?Discourage drillers from drilling side holes in gully face blast pattern. This will allow for time in which tendon support can be kept up to date. ?Ensure split sets are installed 1 m behind the gully face so as to prevent opening up of fractures. ?Utilize the centre split set in the 1:2:1 pattern to maintain the proper gully line. ?When adverse conditions prevail, it is necessary to apply a special support plan not only to the panel face, but also (just as importantly) to the gully as well. Shotcreting of the gully hanging is a suitable long-term consideration for providing the additional a real coverage needed. List of Abbreviations [CL Carbon Leader M/O Mine Overseer UCL Upper Carbon Leader FOG Fall of Ground LCL Lower Carbon Leader H/W Hanging Wall ERR Energy Release Rate F/W Foot Wall WDL Western Deep Levels ESH Environmental Safety and Health ]

Jan 1, 2002

By Dennis McLaughin

This report contains a description of the contract activities performed by ENSCO, Inc. under contract No. H0178069. The purpose of this project was to enhance the Bureau of Mine?s Cableless Electronic Survey System use to aid in the drilling of long (approx. 2000 feet) boreholes in coal. This drilling is performed as part of the methane drainage program. The system that was ultimately developed was field tested 2nd demonstrated in actual in-mine drilling activities. The significance of this system as compared to previous drill survey systems is the fact that it surveys without having to be inserted and removed for each survey point. It is so designed that it can withstand the shock and vibration experience by the drill string during drilling. This means an increased productivity is now possible in that drill operators can determine drill bit positioning in a near real-time environment.

Jan 1, 1981

An incremental analysis based stope design optimization method was developed at Exodus, an underground project located 30 miles north of Carlin, Nevada. Traditional underground stope design methods, by manually drawing stope shapes, are typically very time-consuming and lacking of consistency and accuracy. For quick reserve calculation and economic analysis, a new method named '3D Incremental Analysis based Stope Optimization' was created for mine wide stope designs at Exodus. With this unique but practical method, multiple options of mine designs were completed within a short period time, which allowed us to select the optimal cutoff grade and best stope design option for the project.

Jan 1, 2012

By N. A. Eilertsen

Mining operations were in progress at the Shawangunk mine near Summitville, Sullivan County, N. Y. as early as 1843 and again as late as 1918. Difficulty in effecting mechanical separation of sphalerite and galena was the primary reason for abandonment by various operators. The Bureau of Mines investigated this mine by diamond drilling, sampling, and performing beneficiation tests. The investigation included the construction of 1.25 miles of access road and the completion of 6,526 feet of core drilling in 24 holes. In addition, 151 samples were taken in the mine. The investigation proved an extension of ore contiguous to the old mine workings and resulted in the discovery of another ore shoot at depth. The ore occurs as fissure filling in a fault zone and contains concentrations of zinc and lead sulfides with minor dissemination of chalcopyrite in a quartz gangue. Metallurgical tests indicate that the ore can be concentrated by selective flotation.

Jan 1, 1950

By David R. Peterson

This report presents a deep ocean mining operational simulation which is capable of describing the response of the bottom collection unit to specified mining ship maneuvers and the corresponding operation of the mining ship maneuvering system. Bathymetry, obstacles, collector and pipe dynamics and ship maneuvering capabilities are included in the simulation. The simulation is capable of evaluating the technical requirements and operating costs for specified mine plans, Results are useful in assessing mine size requirements and provide operating 'cost 'estimates useful as inputs to deep ocean mining economic feasibility assessments, The simulation is used to determine the consequences of obstacles to mining system operations in terms of impact on mine size requirements and reduced production arising from obstacle avoidance maneuvers of a towed (unsteered) collector.

Jan 1, 1979

In-pit crushing and conveying (IPCC) is being increasingly considered as an alternative to traditional truck-shovel mining methods. The move towards IPCC is driven by a number of factors including the potential to reduce greenhouse gas emissions, the availability of skilled labour and the need to increase extraction rates to levels that present significant challenges to traditional methods.When considering the relative performance of IPCC and truck-shovel methods, the outcome can be inadvertently impacted by either the use of different simulation approaches, or techniques that do not adequately model the processes in sufficient detail.A simulation approach is proposed that models both IPCC and truck-shovel using the same software platform and is capable of functioning at a wide range of resolutions from life-of-mine scale through to second-by-second asset tracking level. The simulation framework also holds models of processing equipment and hence the mining simulations can be extended to gauge the impact on downstream plant.The approach, known as mine-process operational simulation (MPOS), can be tailored to the level of information available and hence the type of study required, ie order of magnitude, prefeasibility, feasibility, or detailed design.Using information from block models and a range of detailed equipment and process models, MPOS can span major system discontinuities, typified by the mine-plant interface, to allow the estimation of final mine and plant product specifications.

Dec 6, 2010

By Robert Leach

THIS paper gives a brief summary of the process of manufacture of sterling silver, and some of its more important physical properties, as observed in commercial production of rolled sheet and wire. Although papers have been published by Turner and Smith,1 Rose,2 Sperry3 and Jordan,4 there are few technical data available, and unfortunately the time allowed for the preparation of this paper has not been sufficient to make it as comprehensive as the title might indicate. ANALYSIS OF STERLING SILVER Fine or pure silver is too soft for coinage and the manufacture of articles in which strength and resistance to wear are desired. From the earliest times of which we have record, copper has been the metal generally used to harden silver. Analyses of coins and silver articles from ancient tombs show varying amounts of copper, and old Roman silver objects in the British Museum have approximately the same analysis as our sterling. The first authentic record of the establishment of a standard alloy is during the reign of Henry II in England. During the twelfth and thirteenth centuries, the people in the Eastern Provinces of Germany had a reputation for the standard and purity of their silver coinage, and it is said that Henry II employed some of these Easterlings, as they were called, to improve and standardize the English coinage, which had become debased. The peculiar standard adopted is probably accounted for by the system of weights used. A troy pound contains

Jan 1, 1928