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By M. I. Brittan

Cyanide leaching of two West African gold ores was studied in multiple laboratories to provide process-engineering data for plant design purposes. Unusually slow leach extraction kinetics were observed using routine cyanide leach test procedures with pregnant solution monitoring. Carbon-in-leach testing, however, showed normal rapid kinetic behavior, with the same ultimate gold extractions being reached in much shorter elapsed times. Kinetic curves based on washed solids assays also exhibited more typical leaching characteristics. The results bore all the hallmarks of some equilibrium inhibition of the leaching. It was surmised that ore gangue components were responsible for weakly adsorbing gold-cyanide complex reaction product, thereby holding up soluble gold in the solid phase. The term ?preg-borrowing? was coined to describe the reversible phenomenon and distinguish it from irreversible preg-robbing. The two ores investigated may represent an extreme form of a more general effect that in most instances might pass unnoticed. The effect can lead to misinterpretation of kinetic leach curve data and underestimation of calculated ore head grades.

Jan 1, 2008

By WL Wagner

This report presents a quality control approach to the derivation of strategies for monitoring a work environment; specifically, the environment in underground mines where diesel-powered equipment and blasting agents are used. The approach is presented as a series of 22 steps called the Monitoring Strategy Development Scheme. The scheme is an orderly method for selecting from a number of options a strategy or tactics to cost effectively meet the requirements of a chosen objective related to the monitoring of breathing zone air quality. The scheme provides a format to quantify many of the factors that influence the selection of on strategy or tactic over another, and to ensure that important considerations are not neglected. The premise that breathing zone air in work environment can be considered to be manufactured product and that, therefore, conventional quality control approaches are applicable, is introduced. Typical approaches to the quality control of manufactured products and how these approaches can be applied to the selection of monitoring strategies are discussed.

Jan 1, 1983

By D. A. Larson

The Bureau of Mines conducted basic experiments to study the process of crack propagation with a wedge indenter. The work was conducted under plane stress conditions in a hard, brittle limestone. The purpose of these experiments was to first gain an understanding of the basic crack propagation process under a sharp indenter, and second, to determine how the crack propagation process could be used to improve mechanical fragmentation systems. Three methods of rock fracture with the wedge indenter were investigated in this program. These were the confined indentation tests, the unconfined splitting tests, and the edge chipping tests. The confined indention tests represent worst case conditions for crack growth and formed the lower bound on fracture efficiency. The unconfined splitting tests represented best case conditions and fixed the upper bound of fracture efficiency. The edge chipping tests represented an idealized fragmentation process based exclusively upon the highly efficient fracture propagation process. Edge chipping achieved a specific energy of 25 in lb f/in3 compared to conventional drag cutters, which required a specific energy of at least 2,385 in·lb f/in3? Thus edge chipping is up to 100 times more efficient than conventional drag cutting. Because of these promising results, more work is planned with the fracture propagation process in three dimensions.

Jan 1, 1987

By T. C. Moore

This report describes the feasibility test of an electromagnetic method for locating boreholes, with or without casing, that have been drilled in conjunction with mining operations but whose location with respect to the tunnel is not precisely known. The first tests were conducted with the cooperation of the Kerr-McGee Corporation, Church Rock Mining Operations, New Mexico, in September 1977. These tests demonstrated that accuracies of better than ±5% of range and ±1° of bearing can be achieved with a simple system and setups. Subsequent tests, in January 1978, on a horizontally drilled pipe line river crossing application, by Titan Contractors of Sacramento, California, demonstrated that accuracies of better than one-half percent of range and a few tenths of one degree of bearing can be achieved by using refined techniques. The demonstration tests were done at ranges on the order of 100 to 200 feet but the method is capable of working at much greater distances.

Jan 1, 1978

By Timothy A. Clancy

To help reduce the Nation's dependence on imported chromite, the Bureau of Mines is conducting research on the use of dolomites as an alternate material. Dolomite is a plentiful domestic resource and offers certain advantages as a refractory raw material. A review of the literature has indicated that there are many sources of high-purity dolomite in this country and that European nations use a greater proportion of dolomite refractories, primarily in steelmaking, than the United States, The Bureau of Mines characterized 14 domestic dolomites as to chemistry, density, mineralogy, microstructure, and thermal behavior, to develop baseline data on their suitability as refractory raw materials.

Jan 1, 1983

By William P. Stroud

Chemical alteration of the compressive strength of sandstone has been investigated by the U.S. Bureau of Mines (USBM). Successful development of this technology would offer an attractive alternative to the methods now used for stress control in mines. Sandstone cores were stressed to failure under uniaxial compression at two different strain rates. Specimens saturated with either distilled or tap water showed an average 14% reduction in stress at failure compared with those dried in vacuum. Samples saturated with dilute solutions of aluminum chloride, hydrochloric acid, and polyethylene oxide showed no statistically significant difference in failure stress compared with those saturated with water. By contrast, compressive strength of the cores was increased some 7% by saturation with the nonpolar solvent carbon tetrachloride. No correlation was found between zeta potential and compressive strength.

Jan 1, 2010

By Corby G. Anderson

Antimony has been utilized by mankind for thousands of years. However, due to recent environmental concerns, antimony is often considered to be an impurity element, Since antimnoy is commonly found in precious metal refractory ore bodies, extraction is essential. The Sunshine Mine in Kellogg, Idaho has recovered antimony from its precious metal tetrahedrite deposits since the 1940's. A plant was initially constructed as a primary antimony source during World War II. This facility also decreased the downstream smelting penalty for the silver copper-lead concentrate and provided an industrial commodity from a potential environmental nuisance.' This paper describes the Sunshine antimony processing- facility. Specifically, the relevant process chemistries involved in concentrate leaching, metal electrowinning, and sodium antimonate production will be discussed. In addition, ongoing areas of research to improve unit operations and treatments implemented to meet environmental' discharge requirements will be covered.

Jan 1, 1992

By S Worden, A Lee Zhi Yi, E Sellers, G Corder, A Littleboy

The global shift towards decarbonisation is driving competition for the extraction of critical minerals such as nickel, lithium, and copper. To meet this demand, new mines are being developed while mines approaching closure are being reimagined as sites of potential resources. This reimagining challenges how mine closure is being conceptualised. In the conventional case, when a mine reaches the end of its economic life, it is closed or put into care and maintenance until it transitions to the next land use, such as agriculture, native ecosystem corridors, solar farms or integrated eco – precincts (Murphy et al, 2019; Holcombe, 2020) (the authors acknowledge that unplanned mine closures have left a devastating legacy of contamination, safety and cultural heritage impacts). Extracting minerals from closed or closing mines will extend mine life and, therefore, delay relinquishment and transition. In this context, innovative technologies are needed to make mining economically viable. In the first year of her doctoral research on improving stakeholder engagement in mine transitions, Lee Zhi Yi has coined the term ‘mine life extension technologies’ (MLETs) to describe a class of technological solutions that optimise extraction of resources after a mine reaches the end of its economic life. Examples of MLETs include agromining (van der Ent et al, 2015), in situ recovery (Robinson and Kuhar, 2018), and reprocessing or reuse of tailings (Gou, Zhou and Then, 2019). MLET extraction offers several benefits compared with conventional mining processes, such as waste remediation, value recovery of minerals, a smaller footprint and less environmental impacts (Sellers, Picorelli and Salmi, 2022). What requires further investigation is the consequences of MLET implementation to host communities or community perspectives towards the proposed technology and subsequent delays in transition.

Aug 2, 2023

By Zhang Libo, Peng Jinhui, Zhang Zhengfu, Fu Mengbi, Han Yamei

In this paper, results of a novel synthesis method of carbon-coated LiNi113Mn113Co11302 cathode material for lithium-ion battery are reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The structure, morphology and electrochemical performance of the bare and carbon-coated LiNi113Mn113Co11302 were characterized by X-ray diffraction, scanning electron microscopy and charge-discharge tests respectively. The L8(27) orthogonal experiments were carried out to optimize LiNi113Co113Mn1130z/C technological conditions. The conditions of the orthogonal experiments were that the glucose content were 1.5 % and 4 %, the holding time were 15min and 30min, the heating temperature were 400 °C and 500 °C and the solvent were H20 and CH3CH20H. The main experiment target include specific capacity at 0.1C and 0.2C, Capacity retention rate, medium voltage attenuation rate and The fifth discharge medium voltage. The data were analyzed by Minitab 14 statistics software. The results of analysis of variance indicated that the most influential factor was the glucose content despite of discharge rate. Secondly, the effect of the solvent was equivalent to the holding time.

Jan 1, 2013

By B. H. Clemmons, C. H. Schack

Extractive metallurgy techniques currently employed to recover silver from primary ores and secondary scrap were reviewed and evaluated to identify and delineate metallurgical problems whose resolution would increase the supply of silver from domestic materials. The survey revealed that practically all primary silver is recovered by froth flotation concentration of various types of ores, followed by smelting and refining of the separate lead, copper, and zinc concentrates. Silver losses during the complex processing are, with rare exception, inconsequential. Furthermore, any silver production gain from base metal ores, which contribute about two-thirds of the total primary silver, is directly dependent on improvement in the market for the base metals. Statistical data on new and old silver scrap are wholly inadequate to make reliable conclusions about scrap processing problems and the possibility of increasing the recovery of silver from the many forms of secondary silverbearing materials. The available information indicates (1) that efficient silver reclamation practices are employed by the larger users of silver, and (2) that recovery of additional secondary silver involves solution of problems of collection rather than of processing. Several possibilities exist for limited increases in silver production from primary ores by improvement in metallurgical practices. Specifically, research is needed to (1) solve the problem of recovering silver from the copper ores of the Copper Range district, Michigan; and (2) devise economically feasible methods for recovery of silver from presently marginal or submarginal ores that because of grade, location, and frequently complex nature cannot presently be exploited by conventional techniques.

Mar 1, 1965

By William H. Langer

The annual consumption of sand and gravel aggregate in 2006 in the Phoenix, AZ metropolitan area was about 76 Mt (84 million st) (USGS, 2009), or about 18 t (20 st) per capita. Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix are mined and processed to provide some of this aggregate to the greater Phoenix area. The Agua Fria drainage basin (Fig. 1) is characterized by rugged mountains with high elevations and steep stream gradients in the north, and by broad alluvial filled basins separated by elongated fault-block mountain ranges in the south. The Agua Fria River, the basin?s main drainage, flows south from Prescott, AZ and west of Phoenix to the Gila River. The Waddel Dam impounds Lake Pleasant and greatly limits the flow of the Agua Fria River south of the lake. The southern portion of the watershed, south of Lake Pleasant, opens out into a broad valley where the river flows through urban and agricultural lands to its confluence with the Gila River, a tributary of the Colorado River.

Jan 2, 2010

By Scott Turner

The monetary metals , gold and silver , have recently been the object of such general interest that the United States Bureau of Mines has received many inquiries regarding them . Though requests for technologic information have been numerous , they have been exceeded in number by those concerned with economic aspects of these metals . The nature of the latter communications indicates that the public is not generally aware that various Bureau publications are available which deal with the economic situation of gold and silver . For this reason , it is deemed advisable to present a brief résumé of the papers which are obtainable from the Bureau or the Superintendent of Documents , together with the text of three articles recently prepared by the Director , reprints of which are not otherwise available . The Bureau of Mines compiles figures showing mine production of gold and silver , by districts and States , and cooperates with the Bureau of the Mint in determining the total annual output in the United States as a whole . 3 It recently established an annual canvass to determine the consumption of silver in the arts and industries of the United States , and published an economic paper covering such use in 1928 and 1929 , followed by an information circular on silver consumption by industry during the 2 years subsequent . A 4-year record is thus provided for those interested in utilization of silver . The Bureau has also published summarizations of all available data upon world production since 1493 of gold and of silver . It has , furthermore , rendered available a compilation of production- data of silver mines of the world , and an analysis of it , showing the proportions of silver and other metals contained in all the ores from which silver is derived . " All of these papers are concerned solely with putting into readily usable form statistical data and other factual material ; they do not offer theories or express opinions upon controversial questions related to these metals . Three other recent papers concerned with gold and silver are presented below in order to put them in shape for distribution by the United States Bureau of Mines . All three of them are by the Director of the Bureau . It should be noted that these papers do not commit

Jul 1, 1933

By David L. Borusiewicz, M. Suri Surendra

"Abstract Helical piles have been used as anchors and for supporting lightly loaded structures as a method of underpinning, etc in the past. Recently, helical piles are being used to support new structures because of their simple installation process using relatively light and mobile equipment. This paper presents the results of evaluation and design performed for the temporary support of existing piers during a bridge rehabilitation project.INTRODUCTIONThe helical screw foundation was invented and patented by Alexander Mitchell in England in 1833. He installed screw piles to support lighthouses in the tidal basins of England. Many applications in the earlier years in the USA were in North Carolina and in Florida to support lighthouses (in coastal plain deposits). A lighthouse of similar foundation design is still in use at Key Biscayne, Florida.In the USA, the helical piles were reintroduced as foundation elements for electrical transmission towers. Helical piles were also used for anchoring guys of self supported towers and as tie-backs for excavation support systems. Typically, helical piles are being used for supporting lightly loaded buildings and for underpinning buildings undergoing distress as a means of remediation. The helical piles are not commonly used in the transportation industry.HELICAL PILESHelical pile is a segmented deep foundation system with helical bearing plates welded to a central steel shaft. Load is transferred from the shaft to the soil through these bearing plates. Central steel shafts are available in either a square shaft (Type SS) or a round shaft (Type RS). The Type SS series are available in 38 mm to 57 mm square sizes. The Type RS series are available in 73 mm to 114 mm diameter sizes. Type SS-RS combinations are also available for compression applications in soil conditions where dense/hard soils must be penetrated with softer/loose soils above the bearing strata.The leading segment consists of a shaft with one or more helical plates that are welded to the shaft. The plates vary in diameter from 203 mm to 355.5 mm and have a thickness of 9.5 mm or 13.7 mm. Typically the plate diameter increases from the bottom of the shaft upward. A helical bearing plate or helix is one pitch of a screw thread. All helices, regardless of their diameter, have a standard 76 mm pitch. Being a true helical shape, the helices do not auger into the soil but rather screw into it with minimal soil disturbance. Helical plates are generally spaced a distance of two to three times the diameter of the plate directly below in order for them to function independently as individual bearing elements. A typical detail of helical pile is shown on Figure 1."

Jan 1, 2014

By Stratton-Crawley R., G. E. Agar

"A study has been done of the scale-up of laboratory bench-scale flotation to continuous plant circuit performance. It was found that the impellor speed and the air flow rate influenced the results and in this case extreme values of these operating variables were required in order to reproduce the plant rougher results in the laboratory. Despite the experimental uncertainty introduced by these extreme values, it was demonstrated that the plant performance could be predicted and experimentally reproduced with bench-scale tests.IntroductionThe mineral processing industry relies heavily on batch flotation testwork to design flowsheets, evaluate reagent s and compare various types of ore. The batch tests are generally regarded as being directly comparable within themselves, but quite often they relate poorly or not at all to continuous circuits. Obviously this dilemma generates considerable uncertainty with wide-ranging ramifications. One of the manifestations of this unfortunate situation is the commonly expressed opinion that ""it may work that way in the laboratory, but it will never work that way in the plant"".In a previous publication, a method was described whereby the results of batch bench-scale tests could be used to simulate a locked cycle flotation test series. The work to be described here is a continuation of that investigation with an extension to the simulation of an actual plant circuit. It would have been preferable to progress from laboratory batch data to a continuous pilot plant and then finally to a full-scale plant operation. However, because that possibility did not present itself, an attempt will be made to show that the performance of an existing plant circuit can be successfully simulated from batch data. The success of the procedure can be judged by the agreement among the plant results, a locked cycle test and the predicted results based on batch tests."

Jan 1, 1982

By William J. Douglas

This document describes the development of a conventional mining equipment data base, and an approach for conducting industrial engineering studies of arbitrary mining systems employing network techniques. Data was acquired through underground time studies. Each member of a four-man field team was assigned to a specific machine during each shift for which observations were conducted. Using digital wrist watches and networks describing the man-machine interactions, all events occurring luring the course of each shift were recorded on cassette tapes. The tapes were transcribed, coded, keypunched, and validated using computerized editing techniques. The resulting data files were processed to provide statistics relating to activity durations and event frequencies. The results were used to evaluate operator, machine, and system performance for each section which was observed. Equipment, reliability, and maintainability analyses were conducted using the industrial engineering data files in conjunction with historical information collected at the mine site.

Jan 1, 1976

By P. R. Geoffoy, T. Koulomzine

"The discovery of the Mogador deposit concealed by 100 feet of overburden was the result of combined application of geological reasoning, ground geophysical surveys, studies of glacial float and extensive diamond drilling. The ground was acquired because it lay on the projected intersection of the Manville and Laflamme River faults. Systematic ground prospecting led to discovery of mineralized floats. A first unsuccessful exploration campaign lasted several years and consisted of 137 drill holes.In 1951 the boulder nests were reexamined and an associat'on of the mineralized float with boulders of a granodiorite, unknown in outcrops of the district, was established. Consequently, ground magnetic surveys were extended and re-interpreted, and a large anomaly interpreted as corresponding to a batholith was outlined. The existence of the batholith was immediately confirmed by drilling and the Mogador deposit discovered in third hole of new drilling programme in a zone of fractured volcanics paralleling southern contact of batholith.The Mogador deposit is a complex replacement of silicified volcanics by pyrite, pyrrhotite, sphalerite, chalcopyrite and galena carrying values in silver and gold. A total of 1,230,000 tons has been indicated, most of it now classified as fully developed proven ore."

Jan 1, 1960

By R. Craig Smith

This report presents the software documentation for PREY AL, a prefeasibility mineral property evaluation program developed by the U.S. Bureau of Mines on a Lotus 1-2-3 spreadsheet. It is presented in a step-by-step "user?s manual" format. Appendixes contain the technical assumptions, program default values, and a summary printout detailing capital and operating costs and cash-flow analysis.

Jan 1, 1992

By H. E. James

Much has been said and written about the need to reduce South Africa's dependence on gold. To compensate for the decline in the country's foreign-exchange earnings resulting from the phasing out of gold, which must inevitably occur at some future date, a far higher priority will have to be placed on the mining, beneficiation, and export of the 59 other mineral commodities produced in South Africa. The basic strategy of the mining and metallurgical industries should be to move from the traditional approach of establishing a resource base to the establishment of a market base; to turn from production orientation to market orientation; and to rely less on exploration and economies of scale and more on process innovation and product development. The enthusiasm, entrepreneurial spirit, and commitment of the leaders in the mining and metallurgical industry will clearly be of decisive importance in the establishment of new industries for the beneficiation and export of added-value mineral-based products. The State can make a significant contribution by the provision of a welldeveloped and efficient infrastructure, including rail and harbour facilities, communications and health services, roads, and of electricity and water supplies. In our search for a new development strategy for the beneficiation and export of South Africa's minerals, we need to recognize that no one nation has all the mineralresources that it needs. Commercial and strategic manipulation of mineral supplies should no longer be tolerated. The future of the human species lies in international cooperation and in a greater understanding of the limitations of the world we live in.

Jan 1, 1985

Reynolds Metals Company announced plans to increase its rate of production of primary aluminum by 17 thousand tons per year by the end of February. Other producers were expected to increase operating rates during the first quarter of 1976 (see table 10 pg. 29). CHROMIUM -Under the Trade Act of 1974, a petition was filed July 16, 1975, with the U.S. International Trade Commission (ITC) by the Tool and Stainless Steel Industry Committee for Import Relief and the United Steelworkers of America, AFL-CIO, for import relief for certain stainless and alloy tool steel products. The Commission determined on January 16, 1976, in a report to the President, that increased quantities of imports of stainless steel sheet and strip, plate, bar, and rod and alloy tool steel except ingots, blooms, billets, slabs, and sheet bars were a substantial cause of serious injury or threat thereof. The Commission recommended import quotas for the period 1976 through 1980. The President has 2 months in which to act, with his decision subject to a Congressional override.

Jan 1, 1976

The value of U.S. mineral raw material output reached a record $63.1 billion in 1975. This high exceeded the 1974 value of $55.2 billion by 14 percent. Among the three major mineral categories -fuels, metals, and nonmetals -only fuels showed an increase in value. Both the metal and nonmetal categories showed declines in value. The significance of this nearly $63 billion mineral output can be noted in the fact that it is the basis for the subsequent production of over $270 billion a year in energy and processed materials. Of the 78 individual mineral commodities included in these 1975 totals, only 17 registered gains in output, while 45 registered value increases, reflecting higher prices.

Jan 1, 1976