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By R. H. Sergent

The interest in using halogens for extracting precious metals from ores has increased due to changes In ore characteristics, environmental concerns and regulations. The rediscovery of halogen leaching capability has been the topic of these and other writers1-30. Much work has been done on the performance of bromine, chlorine and iodine5-29. Of these, bromine and chlorine look most promising. Iodine is quite expensive and sometimes forms an Insoluble film on a precious metal surface22,23. Little experimental work has been published on the relative performance of bromine versus chlorine. The Pourbaix diagrams for the halide leach system (see Fig. 1-4) Indicates a significant stability advantage for bromine In forming complex ions with gold. This should result In greater extraction of gold under similar leach conditions and Is evaluated In this work. The regeneration of halogen from a spent leech solution is a critical requirement for an environmentally acceptable halogen leach process. Bromide can be oxidized In-situ to bromine ~ adding chlorine or ozone2,31. Bromide like chloride can be oxidized In an electrochemical cell to produce halogen on demand 13,15,17. Bromine clearly offers a number of possible regeneration pathways. This work strives to compare the relative ability of chlorine and bromine to extract gold from partially and fully oxidized ores. A commercially pressure oxidized sample was evaluated under a number of experimental conditions. The autoclave feed ore from the same mill was also evaluated after complete oxidation In a laboratory autoclave.

Jan 1, 1993

By Wm. O. Vanderburg

This report on the mining and milling of tungsten ores is the second part of a general study of the domestic tungsten industry. The first part, comprising general information on tungsten, has been printed as Bureau of Mines Information Circular 6821. The purpose of these papers is to increase efficiency in the mining, preparation, and utilization of the tungsten resources of the United States. The tungsten industry forms so small a part of the vast mining and metallurgical operations of the illation that private metallurgists have not had enough inducement to give special attention to the recovery of tungsten minerals from the ores, and many of the small companies are financially unable to undertake research work. A study of the milling of tungsten ores reveals that further improvement is possible, especially in the treatment of slimes. Recent experimental work by the Bureau shows that the flotation process is applicable to certain tungsten ores. The future of the tungsten industry it the United States depends to a great extent on utilization of the low-grade deposits of the contact-metamorphic type.

Jan 1, 1935

By A. L. Service

In 1965 the Western phosphate industry ranked third after Florida and Tennessee in total mine and marketable production of phosphate rock and phosphate rock products. It has become an important regional industry and, since the close of World War II, it has become important in the national phosphate economy. This report includes an evaluation of the trends and outlook for the Western phosphate industry through 1975 as part of the Bureau's program to determine the rate at which the Nation's mineral resources are being utilized. The first part of this report is concerned with the relationship between the Western phosphate industry and that of the United States and the world. It describes the principal phosphate deposits and discusses production, export, and import of phosphate rock and marketable products. The second part of the report is concerned with the Western phosphate industry and discusses trends and outlook through 1975. Projections for the utilization of phosphate rock, phosphate fertilizers, and elemental phosphorus have been developed and extended through 1975 in an effort to provide data and information pertaining to the rate of depletion of the Nation's phosphate resources.

Jan 1, 1967

By Lloyd Williams, James R. Boyle

The mining methods and practices used at the Young zinc mine, American Zinc Co. of Tennessee, have resulted in a low-cost, high-yield operation. Zinc ore (sphalerite) occurs in limes tone- dolomi te beds of the Kingsport Formation and is mined by modified room and pillar method. Utilizing trackless mining equipment which incorporates a high degree of flexibility, this operation has had a steady increase in productivity.

Nov 1, 1964

By R. E. Gray

[The purpose of the study is to investigate cases of subsidence over abandoned mined-out areas of the Pittsburgh Coal identified from published and unpublished sources and to determine through a consideration of the geology, topography, climate, mining activity, and evidence at ground surface, what mechanisms control subsidence .and under what circumstances it takes place. The study wan performed it two phases, the first to identify all documented incidents of subsidence in mined-out areas of the Pittsburgh coal Region; and the second, to study a particular portion of the region in detail, collecting pertinent data relative to the sites within, characterizing roil the nature of the subsidence and its economic consequences, and determining the applicability of the findings to other areas whore similar problems with the collapse of abandoned miner have been encountered.]

Jan 1, 1977

By W. W. Adams

Coal mining in the United States, had a somewhat higher death rate per million man-hours of exposure among the employees in 1937 than in 1933 to 1936. However, the rate in 1937 was lower and therefore more favorable than that in any year since 1921 but previous to 1933. The nonfatal injury record, which began in 1930, was lower and therefore better in 1937 than in any other year since 1930. Separate figures covering bituminous-coal mines in all States showed a lower fatality rate in 1937 than in any year since 1920 but before 1933, and a lower nonfatal injury rate than that of any year since 1930 except 1933 and 1936. Reports for anthracite mines in Pennsylvania revealed a better safety record for fatal accidents in 1937 than in any year since 1930 except 1933, 1934, and 1936 and a better record for nonfatal injuries than in any year since 1930 except 1933.

Jan 1, 1940

By K. E. Stanfield

[Asphalt ~~d road oil ar8 the principal products manufactured from Wyor.1in~ Ilblack oilo" \r,hich, beca.use of th?lir hig.~ E\.sphal t and hig} sulfur COi.1Jce~1t, .!?re difficult e':ld costly to refine into hi?;h-gra.de motor f 101s, burning oils. and lucri ants by presont mothods. Accordin~ly. the demand for truHle asphaltic renidl urn for the construction of roade aJ1.d other uses is 3. controlling factor in the quantity of crud~ oil prod ICed. The increasiilg -u.tilization of special aST>ha.lts as ine}""Pensive bonding, in-]

Jan 1, 1941

By David A. Summers

Coal is increasingly viewed as one of the major fuel resources of this country for the remainder of this century. The need to extract a greater percentage of the coal in a given seam, together with advantages of improved safety, indicates that longwall mining will become more widely used within this time frame. A novel method of mining coal on a longwall face, utilizing high pressure water jets, is herein described. The mining machine proposed will exploit the stress conditions which exist on a longwall panel in order to achieve the required productivity while at the same time reducing respirable dust and methane ignition hazards. The water jets will excavate only the boundary of the extracted seam section, and thus the energy requirement of the machine will be minimized. The action of the machine is similar to that of an existing coal plow, except in that the wedge teeth of the plow are replaced by oscillating high pressure water jets. The machine can, therefore, cut to the depth and at the speed of existing shearer units at equivalent power levels. The removal of impact stresses from the machine will reduce downtime required for maintenance and replacement of picks and lower the load on the haulage motor of the system. The ability of the machine to increase the depth of cut without an increase in horsepower will further improve productivity when transportation systems to remove the greater production are in operation.

Jan 1, 1974

By J. R. Thoenen

The enormous and constantly increasing demand for limestone to supply a multitude of uses is a remarkable feature of the mineral industries. As approximately 130,000,000 tons of limestone are produced annually, it is not surprising that deposits at or near the surface are gradually being exhausted and that less advantageous supplies are being worked. Quarries are becoming deeper and wider year by year, and in many places the volume of overburden that must be removed to allow open-pit work has increased alarmingly. Quarrymen are also gradually learning how expensive it is to sort and clean stone from a deposit overlain by poor material. As such conditions confront the limestone industry, the natural tendency is to seek some modification in method whereby the handicaps of increasing cost may be met and overcome. Operators, some of them unwillingly, have been forced to conclude that underground work in drifts and tunnels is the most logical solution of the problem. The unwillingness of some is largely due to unfamiliarity with mining and to the unfounded fear that costs must increase and dangers multiply when mining is undertaken.

Jan 1, 1926

Prof. A. Ledebur, Freiberg, Saxony :* Mr. Sauveur has presented and enriched with original observations a valuable summary of the theories advanced hitherto concerning the hardening of steel; but in one particular, it seems to me, his statements call for correction. He says:

Jan 1, 1898

By Laurance L. Oden

The Bureau of Mines is developing melting data for binary combinations of the alkaline earth fluorides and yttria to facilitate the formulation of slag compositions. The present report deals with the SrF2-Y2O3 system for which liquidus and solidus temperatures and solid solubilities were determined. The information is presented as the phase diagram. The phase diagram was constructed from information obtained by ceramogra¬phy, X-ray diffraction, thermal analysis, and electron probe microanalysis of small specimens encapsulated in platinum-20 percent rhodium or molybdenum ampoules. The data indicate a simple eutectic system with limited terminal solid solubilities. The eutectic temperature is 1,457°±5° C, and the eutectic composition is 4±1 mole-pct Y203. Strontium fluoride containing up to 2 wt-pct 0 2 was studied to determine the effects of oxygen contamination. Oxygen levels in excess of 0.2 wt-pct resulted in eutectic formation between SrF2 and SrO. The eutectic composition is between 0.2 and 0.7 wt-pct 02, and the eutectic temperature is 1,447°±5° C. No intermediate oxyfluoride phases were detected.

Jan 1, 1974

By Hugh M. Wolfin

This Information Circular is an abstract of a manuscript which was completed in June 1933, by Mr. Hugh M. Wolflin, formerly of the U. S. Bur eau of Mines. This abstract has been prepared by Charles Will Wright for presentation at the February meeting of the American Institute of Mining and Metallurgical Engineers in New York. It has been necessary to omit many of the details and most of the cost data and tables, as well as the illustrations in the original manuscript. As the use of airplanes in mining developments is making such progress and as a publication on this subject to be of greatest value should include the most recent information, it is unfortunate that, due to a lack of printing funds, it has not been possible to publish this manuscript. The purposes of Mr. Wolflin's paper are: (1) To describe briefly what has been accomplished in some outstanding examples by the use of aircraft in the mining and petroleum industries, (2) To record costs, (3) To present available information and suggestions to assist in solving future air-transportation problems in the industries under consideration.

Jan 1, 1934

Successful evaluation and exploitation of resources and reserves relies on the collection of high quality sample data. The quality of the sample data must be maintained through the application of a robust quality assurance and quality control (QAQC) program, including documentation of sampling procedures, training of sampling personnel and the regular monitoring of control samples. However, the application of QAQC programs in the minerals industry is often poor and the purpose misunderstood. It is all too common to have good quality control data collected, but no analysis work carried out until after drilling is completed. In a lengthy drill program, this can lead to problems not being discovered and corrected as they happen. Moreover, rectifying problems afterwards will be costly in terms of time and money, if not impossible. The consequences of poor quality sample data are many and include such effects as over- or underestimation of block grades, misclassification of ore and waste, and lower confidence in the resource/reserve models. The purpose of this paper is to highlight, using case studies, the importance of good QAQC practices to monitor the quality of sampling and laboratory sample preparation and analysis.

Mar 1, 2010

By Trevor R. Ellis

"The valuation of mineral properties in the U.S. is only partially regulated. The regulations which have jurisdiction or impact appear to have such mainly as a consequence of unintended fallout, since the regulations were designed for other purposes. Court case history can also be important. The combined results are a mixture of bad and good, with important lessons to be learned.Since 1981, the Securities and Exchange Commission has prohibited U.S. listed companies from reporting quantitative estimates of mineralization and the value of mineralization, other than proven and probable reserves. This results in the minerals appraiser (valuator) working with a shortage of data in his everyday work, both on the subject property and in sales analysis.Between 1989 and 1995, all 50 states and essentially all Federal agencies adopted the Uniform Standards of Professional Appraisal Practice (USPAP) for real property appraisals (valuations). The major national appraisal societies also require their members to abide by USPAP. A significant portion of minerals appraisals must now follow these standards. This paper will discuss the content of USPAP. It provides a very good framework for the valuation of a minerals property or a mine, both as real property and as a business. However, the credentialing standards for real property appraisers are now prohibitive for minerals appraisers."

Jan 1, 2003

By Richard H. Mote, W. C. Schroeder

The endlessly changing pattern of mineral supply and demand offers opportunity to the alert and can bring disaster to the unwary. The discovery of ore bodies, the invention of extractive processes, the provision of new transport facilities, the political stabilization of underdeveloped areas, and many other changes can increase supply dramatically. Such new outpourings of mineral wealth from ore bodies bring fortunes to their developers, and consumers frequently find their competitive positions decidedly improved by new and cheap sources of supply. On the other hand, operators of marginal properties can find competition from newly opened high-grade mines intolerable. Consumers that have depended on the products of nearby, high-cost mines may find new, remote, low-cost supplies advantageous only to their competitors. The invention of new prospecting methods can have spectacular effects. Shortly after World War I the discovery rate of petroleum pools began to decline. The leading prospecting technique of that day, the projection downward of surface reflections of geologic structure, was proving less rewarding. Prophets foretold an oil shortage in the near future. But at that very moment scientists were perfecting the application of seismic waves to reveal underground oil-bearing geologic structures. As these geophysical methods were put into commercial use the whole outlook changed-the problem of the 1930's became how to cope with the surplus from discovery, not how to meet the ever rising demand. Many lead mines were being abandoned as unprofitable about this same time because the penalties charged by smelters for the zinc in the ores and concentrates more than counterbalanced the payments for lead and silver. Then selective flotation (at the time called differential flotation) appeared,

Jan 1, 1959

By Kenneth L. Driggs

The 1988 shift in primary smelting facilities from low grade matte (35%) reverberatory furnaces to high grade matte (63%) flash smelting heavily impacted a very stable and successful converter operation. Low matte grade converter campaigns averaged 36,000 short tons of copper and revert production/consumption was in balance. The conversion to high matte grades necessitated oxygen enrichment of converter blast and revisions in operating practices. After two years of operational development, campaign life has risen to over 40,000 short tons and revert production/consumption is again in balance.

Jan 1, 1991

By Edward W. Parker

(Toronto Meeting, July, 1907.) NOTE.-The material from which this paper has been prepared was collected for the U. S. Geological Survey Bulletin, Contributions to Economic Geology, 1906, and appears also, though in somewhat more extended form without illustrations, in that publication. ALTHOUGH the briquetting of coals and lignites has been carried on for many years in Europe, and has reached a particularly high state of development in France, Belgium, and Germany, it has made comparatively little progress in the United States. The causes for the backwardness of the United States in this regard are several, and first among them has been the abundant supply of cheap raw fuel with which the manufactured article has to compete. With our millions of acres of coal-productive territory, from which the product can in most cases be cheaply extracted, it has appeared in many districts more economical to waste the slack or culm, which con¬stitutes a considerable percentage -of the product, than to attempt to save it at the additional expense required for briquetting. It is for this reason that the view in all sections of the anthracite-region of Pennsylvania is marred by the unsightly culm-banks which encumber the ground, and that in some of the bituminous-districts one sees huge piles of unmarketable- slack allowed to burn up in order to get rid of them. When the coal is of a coking quality, or when the slack can be used for steaming-purposes, these losses are not sustained, but many thousands of tons of what might be converted into usable fuel have been wasted every year simply because of the increased expense involved in its preparation.

Sep 1, 1907

By Afshin Sadri

Acousto Ultrasonic-Echo (AU-E) is a technique developed to provide accurate measurements of the refractory lining wear in operating smelters based on the principles of stress wave propagation. The objective of the system is to provide feedback for the continuous optimization of the overall smelter operation. In some cases, the AU-E refractory lining measurements have allowed clients to extend their smelter campaigns and operate safely for several years beyond their planned reline schedule. In other cases, AU-E results inform clients of serious issues within their furnace allowing them to shut down their smelters ahead of predicted failures and possible disasters. This paper presents the results of several smelter AU-E inspections of the hearth and sidewall. These case studies demonstrate how the AU-E results were used to positively affect the smelter operation.

By B. Calver, D. J. M. Farnsworth

"As open-pit operations expanded at Pine Point, hydraulic aquifer evaluation was undertaken to establish the criteria necessary for the design of a feasible dewatering system.The extreme climate of this northern location dictated that the ore zone under extraction be rendered as dry as possible to minimize freezing effects. The design and implementation of such a system necessitated detailed hydraulic evaluation, and the problems that occurred are typical of those inherent in open-pit mining operations in northern areas.The paper describes the problem solution as approached from a mine engineering point of view, with particular reference to the practical aspects of operation and installation. The hydrological analysis used is simple and readily applicable to most open-pit dewatering problems."

Jan 1, 1969

By R. W. Van Dolah

An investigation was made of the distances over which sympathetic detonation of ammonium nitrate (AN) and ammonium nitrate-fuel oil (AN-FO) might be expected. Large-scale gap tests used two types of AN-FO donor charges in three sizes with AN, both at ambient and elevated temperatures, and AN-FO acceptor charges. Donor sizes were varied to test the validity of a scaling law commonly used in quantity distance tables. The up-and-down experimental design was chosen to determine the 50-percent initiation point efficiently. The acceptor charges were instrumented to indicate initiation and to determine detonation velocity. Other electronic techniques for measuring the rate of growth, stability of detonation, and detonation pressures were employed. Air shock and fragment velocities between charges were measured by electronic and photographic methods, and determination of side-on air-blast pressures and impulse duration were made for about half the shots. Separation distances between donor and acceptor were found to be larger than anticipated both for the AN and the AN-FO. With AN-FO acceptors and a 16-gage steel faced donor, one initiation occurred at a separation of 53 feet or nearly 16-charge diameters; with AN, initiation occurred at 4 to 5-1/2- charge diameters.

Jan 1, 1966