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By Denise A. Herzog

The U.S. Bureau of Mines conducted a study of cyanide leach technology used in Alaska's mineral industry from 1987 through 1990. Literature and cost data were obtained for mines in the contiguous United States, Canada, and Alaska that use cyanide to recover gold and silver. The data was compiled in an effort to evaluate the economics and conditions associated with cyanide use in Alaska. This report discusses heap leaching methodology and evaluates a "typical" heap leach operation in Nevada and compares the results of the Nevada operation to an analogous hypothetical mine in Interior Alaska. Five daily tonnage rates were analyzed for both the Nevada and the Alaska operations to evaluate the spectrum of economic possibilities. The discounted cash flow rate of return (DCFROR) for each production rate was then evaluated in terms of recoverable metal value (RMV). The Nevada RMV for each production rate was then compared with its Alaskan counterpart, and the results averaged. The Alaskan production costs are an average of 1.71 times greater than costs associated with mining in Nevada at a 0% DCFROR. At 15% DCFROR, costs in Alaska are 2.01 times greater than those in Nevada. Costs are higher in Alaska because of the shorter leaching season, increased labor and transportation costs, and heavier precipitation and vegetation.

Jan 1, 1991

Major activities of the Bureau of Mines Explosives Research Center during fiscal year 1965 (July 1, 1964, to June 30, 1965) are reviewed briefly. Part 1 summarizes significant accomplishments of the projects that were active during the report period. Part 2 presents short abstracts of the publications that appeared in the Bureau series and in other media during fiscal year 1965. Publications issued after June 30, 1965 are noted where pertinent in footnotes but are not abstracted.

Jan 1, 1966

By Edward W. Parker

THE agreement of September, 1922, between the anthracite operators and the United Mine Workers of America, which followed the 54.5 months strike during the summer of that year, contained the following provision : The parties unite in a recommendation to Congress that legislation be forthwith enacted creating a separate anthracite coal commission with authority to investigate and report promptly on every phase of the industry and the parties hereby ask the President to request the enactment by Congress of the recommended legislation. The continuance of production after Aug. 31, 1923, shall be upon such terms as the parties may agree-upon in the light of the report of the Commission.

Jan 1, 1924

By F. Wendling, R. C. Nascimento, S. S. Wendling

"The objective of this research is to study the quality of blast-furnace iron ore pellets with binary basicity 1 fired on a pilot scale using the two main firing processes that are presently in use in the world and comparing them. Currently, the great majority of pellet producers use the traveling grate process because of its higher production capacity. In this study, the physical and chemical qualities of the pellet feed, limestone, anthracite and bentonite were determined and the amount of additives for a blast furnace pellet with the defined basicity was calculated. The physical properties of the green and dried pellets were determined accordingly. Produced pellets, after being fired on a pilot scale using traveling grate and grate kiln, were subjected to chemical analysis and physical testing. No significant difference was observed in the metallurgical quality — that is, reducibility index (RI), reducing disintegration index (RDI) and swelling index (SWI) — of the pellets produced by both processes. However, a comparison of cold physical tests — tumble and cold compression strength — shows improved quality of the pellets fired using the grate kiln process.IntroductionThe development of human civilization owes much to iron and steel (Sun et al., 2015). Iron is the most used metal in the world, and it is the main component of steel, which is present in materials for structural engineering, automotive and general industrial applications (Liu et al., 2014). Increased global demand has led to a decrease in the resources of ore with high iron content (Zhang et al., 2015), and currently 95 percent of the iron ore in China needs processing before smelting as its iron (Fe) content is only about 30 percent on average (Liu et al., 2014).Pelletizing is a process to economically agglomerate iron ore pellet feed into pellet form. After balling, green pellets are conveyed to the final step of the manufacturing process (Pena, 1982). The process is a multifaceted one, involving high temperatures, air flow gas turbulence and complex equipment geometry (Larsson et al., 2009). The pellets are fed into blast furnaces, which are now predominantly used in the extraction of iron. Ore processing also requires physical separation, including crushing, grinding and water removal (Sun et al., 2015).The increase in steel consumption favors the exploitation of low-concentration ores and the production of pellets (Halt and Kawatra, 2014). Pellet quality is affected by various factors, such as their physical and chemical characteristics and their temperatures and residence times in the furnace (Halt, Silva and Kawatra, 2015). Different geological settings lead to a wide range of different minerals (Graça et al., 2015).This work aims to generate important information for the pellet industry in the area of physical and metallurgical qualities of the agglomerates obtained by two processes: traveling grate and grate kiln."

Jan 1, 2017

By M. C. Irani

This Bureau of Mines report tabulates methane emissions from U.S. bituminous coal mines with daily emission rates of at least 100,000 cfd according to States, counties, and coalbeds. Most of the methane emitted is from mines in the Appalachian States. Total daily emission in 1975 was 216.3 MMcfd, compared with 227.0 MMcfd in 1971 and 214.5 MMcfd in 1973. Thirty counties in nine States hid daily methane emissions of 1 MMcfd or more. These emitted 93 percent of the total methane. The highest emissions were from Monongalia County, W. Va., which accounted for 18.9 percent of the total. This was followed by Marion County, W. Va., 9.6 percent; Buchanan County, Va., 8.3 percent; Jefferson County, Ala., 6.1 percent; and Washington County, Pa., 5.9 percent. The Pittsburgh coalbed emitted 45.7 percent of the total methane, followed by the Pocahontas No. 3 coalbed with 12.9 percent. The report lists 196 mines, of which 60 had daily methane emissions of 1 MMcfd or more. Included in this compilation are the identification and thickness of the coalbed, methane emission, coal production and ventilation rates, number of drifts, shafts, and slopes used for ventilation purposes, shaft depth, age of mine, and gas-to-coal ratio.

Jan 1, 1977

By R. G. Knickerbocker, T. E. Evans, J. L. Morning, D. R. Torgeson, F. W. Wessel

"INTRODUCTION Pilot-plant studies on processes for converting low-grade domestic manganese ore to high-grade oxide or sulfide products by pyrometailurgical process was initiated at the Boulder City, Nev., Experiment Station in 1942. These investigations were given impetus by the possibility of a national shortage of ferro-grade manganese oxide for war needs.The manganese ore employed-in most of the pilot-plant smelting tests was from the manganosiderite-nodule deposits at Chamberlain, S. Dak. This deposit although low-grade, is extensive and represents, the largest reserve of manganese in continental United States. 6/ The Bureau of Mines has recently developed a Carryall mining-conical rolls treatment method that shows promise of making possible economic removal and subsequent beneficiation of the nodule-bearing shales. 7/ Smelting tests were made also on Artillery Peak, Ariz., mill concentrates in the productions of unrefined manganese matte for the steel The pilot-plant smelting program was based upon the fundamental fact that manganese, like copper, will sulfidize and become miscible with FeS. The matte this formed represents the initial smelting step in the pyrometallurgical treatment of the beneficiated ore. The concentrated nodules containing about. 18 percent manganese were smelted with varying amounts of pyrites and appropriate fluxes to produce Mns-FeS mattes containing 16 to 50 percent manganese. When the manganese and iron was completely sulfidized, the mattes contained 16 to 23 percent manganese. Reducing the pyrite resulted, of course, in the selective sulfidization of manganese and the production of a matte containing a correspondingly higher ratio of MnS to FeS. Complete sulfidization smelting produced slags of lower manganese content and hence resulted in higher manganese recoveries in the matte."

Sep 1, 1946

By Broggi Andrea

Condensates produced by SiO(g) and CO(g) have a crucial importance in silicon production. Condensation will follow the reactions 3 SiOðgÞ+COðgÞ→ 2 SiO2 + SiC and 2 SiO ðgÞ→Si+SiO2. Solid compounds generated during silicon production contain Si, SiO2 and SiC in different microstructures and amounts. In industrial systems, condensates limit the SiO(g) escape to the off-gas system. On the other hand, they can block the gas flowing from the high temperature zone, hence the necessity of studying an optimized condensation process. This review discusses SiO(g) condensation and its interaction with CO(g). The report gives an overview of the condensates found both at laboratory and at industrial scale. The two main compounds are the Si–SiO2 and the SiOx–SiC mixtures. The hypothesis on the mechanism of formation of SiC–SiOx condensates is presented through a wide selection of performed works. The advantages and disadvantages of the former experimental procedures are discussed.

By Thomas A. Gwynn

"A beautiful America will require the effort of government at every level, of business, and of private groups. Above all it will require the concern and action of individual citizens, alert to danger, determined to improve the quality of their surroundings, resisting blight, demanding and building beauty for themselves and their children." "Improvement of our environment" has become a cause much like "motherhood". The increased awareness of the public concerning this subject makes it most unpopular for anyone to be involved in anything that seemingly is detrimental to our environment. And this awarement goes far beyond our biggest pollution problem in America - the distribution of paper, abandoned automobiles, beer cans and other garbage by our enlightened society along every city, highway, trout stream, river and mountain in America. In fact, the greatest awarement comes because of the "sensational" reporting and writing in our various national communication media, wherein the same voting citizens who so generously distribute their refuse about the countryside are emotionally aroused and duped into transferring what is truly a national problem onto the shoulders of a few industries - notably and particularly the mineral extraction industry. Certainly mankind is more and more stumbling over his own garbage daily, a fact that is easier to sell a citizen of one of our large cities than a resident of the wide open spaces of the west. Yet even in the Rocky Mountain states, the "Land of Sky Blue Waters", the "Big Sky Country", and particularly in Salt Lake valley smog is not unknown. Pollution and littering have become problems that need to be faced squarely. In North Dakota alone it has been estimated that one section of farm land each year flows down the mighty Missouri and the greatest producer of sediment is now reported to be the highway department.

Jan 1, 1969

By William W. Edgerton

The California Department of Transportation (Caltrans), the Contra Costa Transportation Authority (CCTA), and the Alameda County Congestion Management Agency (Alameda CMA) are involved in a unique partnership on the planning and design of the fourth bore of the Caldecott Tunnel, located on State Route 24 in Alameda and Contra Costa counties. The project will add a two-lane bore north of the existing three bores. The project will alleviate traffic congestion in the non-peak direction. This paper provides background on the existing facility, summarizes the need for the new fourth bore, describes the proposed improvements, sets forth the approach for project delivery, and lists some of the challenges that are expected during construction.

Jan 1, 2008

By F. Magweregwede, S. Khan

Circular economy opportunities for the mining sector are presented in this paper. A literature review was undertaken, followed by qualitative data gathering through survey questionnaires and unstructured interviews, and stakeholder engagements through workshops. The circular economy opportunities were identified and categorised according to the three circular economy principles of designing out waste and pollution, keeping products and materials in use, and regenerating natural systems. Opportunities aligned with the first principle include increased ore extraction efficiency processes, water recovery and recycling, substitution of raw materials, technology and waste utilisation for carbon capture and biotechnology. The second principle includes opportunities such as zero waste-to-landfill strategies, repurposing of mine waste, re-mining of tailings, recycling metals and processing of residues, and urban mining of electronic waste. Opportunities aligned with the third principle include the adoption of renewable energy, green hydrogen production, repurposing of post mining landscapes, and eradication of alien invasive vegetation. Furthermore, the challenges of implementing circular economy in the mining sector are discussed. The current rate of waste generation from mining activities far exceeds the rate of reuse and repurposing. Recycling of large tyres and characterisation of hazardous electronic waste also pose challenges. The most implementable circular economy opportunities in the mining sector are those aligned with the second principle of keeping materials in use. The high impact opportunities aligned with the first principle of designing out waste and pollution, and the third principle of regenerating natural systems, are more difficult to implement as they require large investments.

Dec 15, 2025

By David J. Brown

Extensive deposits of bituminous, subbituminous, and lignite coals occur in the western United States (Figure 1). Over one trillion tons of identified resources have been located and inferred by geologists and more than 200 million tons of western coal are mined annually (1). In the future, production of western coals will increase significantly and approach national production levels of higher-rank eastern coals. Western coals will be utilized in new power plants as a replacement fuel for oil and gas and may be used in advanced technologies such as diesel engines or in direct-fired turbines. Since these applications require low-ash, low-sulfur coals, crushing to fine sizes and significant cleaning to remove minerals and sulfur will be required. Coal cleaning traditionally has been associated with reducing pyrite and other mineral matter from high-rank eastern coals. To date, insignificant quantities of western coals have been cleaned before utilization and limited data on their washability characteristics exist. Because of this lack of data, it is difficult to predict how these coals will react to standard washing techniques.

Jan 1, 1985

By John Berney-Ficklin

Large scale grinding mills can reduce both capital and operating costs for concentrators. These mills can be effectively used, but they must be free from design and manufacturing deficiencies if they are to reach their full potential and avoid costly downtime. This paper presents the evolution of today's complex grinding mill specifications and discusses the most important items to look for when buying new equipment. It emphasizes the need to monitor specification requirements during design and manufacture. It also discusses the growing trend to have grinding mills fabricated in overseas plants, and the importance of recognizing this when preparing specifications.

Jan 1, 1987

By S. L. R. Lenharo, H. Kahn, H. Born

Different ore types result from the irregular spatial distribution of the associated alkaline/carbonatite rocks and the zoned alteration profile within which apatite may have undergone reprecipitation. Different flotation responses are caused by their mineralogy, iron oxide impregnation and grain-size characteristics. Samples from seven deposits were crushed, screened and separated before being studied by chemical analysis, optical microscopy, X-ray diffraction, FTIR spectroscopy, cathodoluminescence and scanning electron microscopy. Two main apatite varieties with peculiar crystal morphology were identified: hydroxy-fluorapatite as the primary phase and carbonate-fluorapatite as the reprecipitated phase. The former occurs as prismatic or ovoid grains and the latter as polycrystalline aggregates or crusts on the primary grains; both are associated with iron oxide coatings (primary) or intergrowths (secondary). Microflotation tests showed variations in flotability for particular apatite associations as well as intensity of iron oxide coatings. The differences in flotation behaviour can be related to morphological properties and chemical substitution in the apatite structure

Aug 1, 1996

By G. S. Austin

Soil next to an abandoned smelter near Socorro, New Mexico, has the highest Pb concentration in the clay-size fraction, although this fraction accounted for only 1 to 3 wt. % of the soil. The depth of contamination was determined in areas relatively undisturbed since the smelter was abandoned about 98 years ago. Lead concentration drops to background levels below a depth of 3 inches. A mineralogical examination of the fine-size fraction of Pb-contaminated soils revealed an absence of crystalline Pb compounds. We conclude that Pb is present either as amorphous phases or adsorbed on the surfaces of soil particles. Yet, because of the alkalinity of the soil, the movement of Pb-bearing particles controls Pb mobility, not chemical transport in solution. Plant material from the site contained elevated Pb levels that increased as the amount of Pb in the soil increased. Of the types of material tested, rabbit bush showed the greatest increase of Pb levels. Lead levels were highest in rabbit bush roots, whereas levels in creosote were highest in foliage. Levels in cactus varied. The amount of Pb due to dust incorporated in plant tissue is almost negligible compared to the amount absorbed through the plant vascular system.

Jan 1, 1992

By C. F. Austin, J. K. Pringle

In view of the many large differences in structure and physical properties between metals, plastics, and most rock materials, a continuing experimental petrodynamics program has been established at the U. S. Naval Ordnance Test Station. Part of this program has been to test the concepts of scabbing and corner fracturing in a typical coarse-grained rock. The results of this experimental program have shown very interesting differences between the formation of fractures in rock and the formation of fractures in other materials such as metals and plastics which are often used as models for rock behavior studies. The gross behavior of coarse-grained brittle solids subjected to impulsive loading has undergone abundant empirical investigation by mining organizations and by mineral research agencies. However, the fundamental response of coarse-grained brittle solids to impulsive loading has received little detailed study in recent years. The various organizations and agencies interested in rock-like brittle materials have broadly applied the stress wave interaction concepts of the impulsive failure of metallic samples to the behavior of granular brittle materials 1,2,3,4,5,6 Using the metallic sample approach for stress wave induced fracturing, an understanding of the fracture behavior of brittle materials which perhaps is not always appropriate has been established in the open literature. An excellent summary of the metallic sample approach is provided by ref. 7 which summarizes the general beliefs prevalent at present regarding the impulsive behavior of brittle solids: "In the blasting process, rock breakage occurs primarily from tensile slabbing, beginning at a free face and proceeding back toward the explosive charge. The tensile waves formed by the reflection of incident compressive waves from two or more free faces will collide in the rock, resulting in large localized tensile stresses. Fractures formed by the interaction of these tensile stresses begin at the apex of the free face planes and progress back into the rock as shown...."

Jan 1, 1964

By J S. J van Deventer, D C. Shallcross

New developments are taking place in the recovery of gold from leached pulps that are based upon the adsorption of the metal cyanide species onto ion exchange resins. Despite the success of several resin-in-pulp pilot plant operations in the Western World and large-scale plants in the former Soviet Union, the process is yet to gain recognition as a viable alternative to the carbon-in-pulp process. An experimental research program has investigated the use of a variety of different types of resins for the recovery of gold, but to-date no resin studied has the desired properties of high selective loading capacity for gold cyanide and a simple inexpensive elution procedure. In addition very little is known concerning the physical strength of resins and their ability to resist shattering due to osmotic shock during cycles of adsorption and elution. The ability of ion exchange resins to enhance the leaching of refractory and re-adsorbing ores has not been investigated. This paper highlights the necessary factors that need to be addressed before commercialisation of ion exchange technology for gold extraction is feasible.

Jan 1, 1998

By Jacob Petersen, Jon J. Kellar, Samuel Kessinger, Kiran Green

Belle Fourche Shale was processed and characterized for use as a clay-based ceramic. The shale was wet sieved to produce particles that were ± 150 μm. X-ray diffraction (XRD) revealed that the -150 μm material was enriched in clay content compared to the unprocessed materials, whereas the oversize material was enriched in quartz compared to the undersize sample. Particle size analysis was performed on the—150 μm sample, which showed that the median particle size was around 10 μm. Scanning electron microscopic (SEM) analysis further confirmed the small plate size, which appeared to be primarily layered clay particles. Next, the -150 μm particles were rolled into a green body, dried at room temperature, and fired at 998°C. The fired piece was analyzed by XRD and contained 6 wt% hematite, 55% quartz, 19% microcline, and various other minor amounts of minerals. When fired at 1152 ℃, mullite was found with increasing hematite compared to the 998 ℃ firing. A multi-spectral analyzer was used to quantify the color change of the 998 ℃ fired (orange) to the 1152 ℃ fired (red) samples. Micro-computed tomography (Micro-CT) of the unfired body exhibited very few large pores, while the piece fired at 998°C also exhibited few and small pores, the overall porosity of the fired body increased. Microhardness data, obtained from the aforementioned samples, resulted in Vickers Hardness (HV1.0) values of 70.8 HV1.0 (998 ℃) and 485.7 HV1.0 (1152 ℃). Three-point bend testing was performed, giving an average strength of 23 MPa on pieces fired at 998 ℃. The average bending strength of the samples fired at 1152 ℃, was 55 MPa.

Sep 26, 2023

By A. Hynes, T. Skulski, D. Francis

The Archean volcano-sedimentary succession in the LG-3 area has undergone two phases of deformation and has been metamorphosed to upper greenschist and amphibolite facies. Marine, fine-grained sediments and mafic pyroclastics comprise the lowest observed stratigraphic unit. These sediments are overlain by a thick sequence of submarine basalts and minor basaltic andesite. The lavas are characterized by high Al/Al+Si, Ti values, low Mg numbers and flat REE profiles (lOx chondrite). A sedimentary prism of coarse elastics which was deposited close to an exposed plutonic highland, overlie the volcanics. Massive lavas of basaltic andesi te and associated volcano-sediments comprise the uppermost stratigraphic unit. These lavas are characterized by high Mg numbers, Ni, Cr, LREE (lOOx chondrite) but low Ti, Al/Al+Si and HRee. The supracrustal rocks were intruded by tonalites and tonalitic gneisses.

Jan 1, 1984

By Enrique Ibarra, Manuel J. Mendoza

"Abstract: This paper describes the current state-of-practice for the design of cast-in-place drilled shafts in granular soils under axial loading, addressing recent advances that take into account the surrounding soil grain size distribution and their behavior. The important role of the gravel content in the shaft response under axial loading is emphasized. Usual design approaches in Mexico are described, and the results of load tests from different sources are discussed. The analysis emphasizes the primary contribution of the lateral area of shafts to their axial bearing capacity, raising doubts regarding the common local idea of “point bearing shafts”. Finally, some lines of research are noted to permit advances in the important field of deep foundations. 1 INTRODUCTIONIn Mexico, cast-in-place drilled shaft foundations are widely used to support various structures in the west area of Mexico City, where alluvial and volcanic deposits predominate. Deep foundations are also used in modern construction works located in other major cities of Mexico. In fact, the use of drilled shafts for tall buildings and overpasses in the center of Guadalajara as well as in transportation works related to the Metro and roadways in Monterrey is well known. It is worth mentioning that these same structures have been applied in road bridges throughout the country.Procedures for pile construction in Mexico have been basically the same for the past 20 years (Paniagua et al., 2005); however, modern equipment has been incorporated into the construction industry, including innovations in sludge-drilling technology, control and the quality of the castings. In addition, novel and efficient procedures such as construction with continuous auger displacement piles have been implemented (Auger Cast in Place, ACP) and have begun to be used locally with success (Schmitter and Paulin, 2006).However, it can be argued that the technological developments that have resulted in more efficient construction procedures have not included a breakthrough in the full understanding of the phenomena or basic mechanisms of load transfer from piles to the surrounding subsoil and therefore in supported, tested and practical design methods. This is particularly true when seeking to determine the unit side shear strength of shafts drilled in granular media with gravels, where it has been observed that the commonly used calculations developed for sands underestimate the load-bearing capacity by frictionin a most important way. Due to the above reasons, it seemed appropriate to present in this paper a review of the current stateof- practice in Mexico for the design of cast-in-place drilled shafts, particularly in granular media, highlighting some recent advances and research that takes into account the grain size distribution and behavior of granular soil."

Jan 1, 2014

By John R. Hawley

"This paper is intended as a review of the progress that has been made in the Province of Ontario in the field of acid drainage waste treatment technology.Three years ago, at the Third Annual Meeting of the Canadian Mineral Processors, we presented a paper entitled ""The Problem of Acid Mine Drainage in Ontario"". At that time I was working for the Ontario Water Resources Commission. The paper turned out to be the very beginning of the Commission's acid mine drainage control program. In the intervening three years, the Ontario Water Resources Commission has been amalgamated with other government groups and has evolved into the present Ontario Ministry of the Environment. Today the Ministry is involved in running one of the most advanced acid mine waste control programs in the world.As a part of its mining program, the Ontario Ministry of the Environment has published three major reports which deal directly and specifically with the industrial waste disposal problems that may arise at a mining operation. In order of publication, these reports are as follows:(1) ""The Problem of Acid Mine Drainage in the Province of Ontario"".This 338-page report covers all aspects of the problem of acid mine drainage and includes detailed sections on acid flow detection, acid flow chemistry and acid flow treatment.(2) ""The Use, Characteristics and Toxicity of Mine-Mill Reagents in the Province of Ontario"".This report, 244 pages in length, gives the chemistry and toxicity of nearly all of the chemicals that find common use in the Canadian mining industry. Most of the toxicity figures quoted are the result of a comprehensive bioassay program that was initiated by the Ministry."

Jan 1, 1974