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By M. J. Raffaldi, L. A. Sandbak, K. K. Dehn, S. N. Warren, J. B. Seymour

"Confidence in the design and stability of an undercut cemented rockfill (CRF) span requires a thorough understanding of its emplaced material properties. The unconfined compressive strength (UCS) of cast 6×12-inch QA/QC cylinders is typically used as an index test to track the performance of a backfill plant. However, these strengths need to be adjusted for oversize aggregate removal and sample size effects if used to estimate the emplaced UCS. UCS testing of 6×12, 12×24, and 18×36-inch cast CRF cylinders was used to quantify the relationship between readily available 6×12-inch QA/QC strength data and the emplaced UCS. Test results indicate that the UCS of 18×36-inch cylinders is roughly 40% of the 6×12-inch UCS for similarly compacted samples. Mine QA/QC data indicate that the UCS of CRF is highly dependent on the degree of compaction as measured by bulk density. Based on these results, knowledge of the emplaced CRF density compared to 6×12-inch QA/QC density is also necessary to estimate the emplaced UCS. The scale effect reported in this study is more pronounced, compared to current understanding of backfill properties discussed in the literature, and underscores the need for further site-specific testing. INTRODUCTION The National Institute for Occupational Safety and Health (NIOSH) Spokane Mining Research Division (SRMD), in cooperation with Barrick Gold Corporation, is conducting research with the goal of determining a relationship between 6-inch QA/QC cylinder strengths and the in-place strength of cemented rockfill (CRF). CRF cylinders with dimensions (diameter × length) of 6×12, 12×24, and 18×36 inches were cast onsite at the Turquoise Ridge Joint Venture (TRJV) and Cortez Hills Underground (CHUG) mines using CRF mixed at the mines’ respective batch plants. UCS tests were performed after 28 days of curing to estimate the size correction factor for each mine’s CRF. This paper presents an overview of the mix designs, sample collections, testing methods, test results, and an estimate of the UCS size correction factor for CRF at these mines. BACKGROUND Underhand cut and fill mining methods utilizing cemented backfill are common in underground metal mines in the United States. These methods are advantageous for controlling weak or highly stressed rock mass conditions by creating an engineered material that can be placed in openings, forming a beam that provides a safe, stable back for the next undercut. Increased use of underhand methods in the last 30 years has greatly improved safety in many cut-and-fill mines. However, with the continual push for more efficient and cost effective mining, there is a need to thoroughly understand the geotechnical properties of cemented backfill to assist in designing safe, stable openings while optimizing costs and production schedules."

Jan 1, 2018

By T. McNulty

The author was privileged to find employment as a uranium mill chemist for The Anaconda Company while working his way through school in the mid-1950s. He then served Anaconda in various technical and management positions until 1980. This paper describes the prevalent technologies employed by uranium producers, briefly describes various mines and mills in the U. S., and memorializes a few of the thousands of men and women who contributed to the U. S. Uranium Boom. Following isolation of uranium as an element by M. H. Klaproth in 1789, uses of uranium were confined primarily to pigments, glass coloring agents, and ceramic glazes. In 1896, Antoine Becquerel found that uranium is radioactive, releasing particles and energy as it decays. In 1898, Pierre and Marie Curie isolated radium from uranium and learned that it can be an effective treatment for some types of cancer. In 1939, it was discovered that the isotope U235 is fissionable1 . Up to this point, nearly all uranium production was from pitchblende concentrates made in Bohemia, Canada, and the Belgian Congo. In 1938, only about 5 percent (23.85 short tons) of global output was produced from ores of the carnotite mineral that were being mined in the U.S. By the early-1950s, physicists in many countries had begun to recognize the potential for nuclear chain reactions. Ernest Rutherford (UK), Frederick Soddy (UK), and Leo Szilard (US) explained transmutation of elements and formulated the principle of “atom splitting”. In 1934, Marie Curie’s daughter, Irène, and her husband, Frédéric Joliot, identified uranium as the most viable source for this new form of energy. The basic fission process was unraveled by German scientists in December 1938. After Hitler’s army seized the uranium deposits in Czechoslovakia, many feared that Germany would build the first nuclear weapon.

Mar 2, 2022

By Gordon Cook

American Electric Power Company (AEP operates 31 coal mines in three states, and some 26 electric generating stations (19 coal-fired) located in the Ohio River Basin. Normally the system burns over 36,071,600 tonnes (40,000,000 tons) of coal and generates in excess of 3.6 X 1018 J (100 billion kwh) of electricity per year. In 1975, AEP, in response to the progressively more stringent air quality requirements of the clean air act, acquired large low-sulfur reserves in Carbon County, Utah (Figure 1. Location Map). Price River Coal Company (PRCC) is the operator OF this multi-seam complex, which is part of the Book Cliffs coalfield at an elevation exceeding 1,829 m (6,000 ft.). The topography is mountainous and divided by numerous canyons. Flat areas are at a premium (Figure 2. Castle Gate Area). Modern high production longwall mining takes in some top and bottom waste, and in this particular operation, it amounts to about 14% of the ROM tonnage.

Jan 1, 1983

By Calvin R. Davis

The bucket elevator is probably the oldest known form of conveyor. Its history can be traced back to the days of Babylon where wicker baskets lined with a natural pitch and fastened to ropes operating over wooden sheaves turned by slaves, were used for the elevating of water into irrigation ditches. It is not unnatural for the bucket elevator to be the first in history, for even today engineers and designers recognize that well designed, correctly applied bucket elevators offer unequaled advantages over other bulk material elevating methods. The bucket elevator's vertical design saves valuable floor space. It provides flexibility of machinery layout with lowest initial capital expenditure, which is its principal advantage. While the advantages of the bucket elevator have long been recognized, there has been a tendency to lean away from its use because of high maintenance without reliability. CHAIN Belt Company found that the bucket elevator, if correctly applied, can be built to be as dependable and reliable as any other piece of machinery in today's modern processing plants. It is not difficult to understand why the bucket elevator is looked upon sometimes as a necessary evil in the material handling system. Very little has been published or written about the specific use or application of bucket elevators other than in manufacturers catalogs. Most of today's elevator application was set forth at the turn of the century by Hetzel (1). There have been many improvements made in the manufacturing techniques of elevator components, improvements in material selections, all which can be used to improve today's bucket elevator. To best understand the improvements which have taken place recently in the design and application of bucket elevators, an understanding of basic elevator principles is desirable. In general, it can be said that bucket elevators are classified into two basic types : (1) centrifugal discharge and (2) continuous. Elevators in use today are either of the centrifugal discharge type or the continuous type, or a combination of both in special applications.

Jan 1, 1958

By Will B. Jamison

The most serious safety problems encountered in U. S. underground coal mines today are related to the roof bolting operation. Also, roof bolting is usually the operation which limits coal production of the section. The purpose of my paper is to review some of the research, developments, and new ideas related to roof bolting. Many of these ideas have originated at. coal mines or with manufacturers. Most of the research on fundamental improvements has been funded by, and is a part of, the excellent and broad plans of the Bureau of Mines.

Jan 1, 1977

By Marcie A. Greenberg

The Fence Lake Project is located in the Salt Lake coal field, an extension of the San Juan Basin. Geologic formations exposed in the Project area range in age from late Cretaceous to Quaternary. Coal is encountered in the Moreno Hill Formation (upper Cretaceous). Salt River Project (SRP) followed the basic textbook approach for the exploration, regional appraisal, detailed reconnaissance, detailed surface appraisal and three dimensional sampling (physical exploration). SRP is exploring this property as a potential fuel source for the Coronado Generating Station. Therefore, for the physical exploration stage, the quality sampling program was designed from a utility company viewpoint to determine possible impacts to the Station. Exploration drilling was completed in spring, 1982; September, 1982, and summer, 1984. Engineering, environmental, and land acquisition studies were added in the Summer, 1984 Program to more closely evaluate the potential Fence Lake Project coal supply option for the Coronado Generating Station. Studies, including drilling, are ongoing-at this time.

Jan 1, 1984

By Aimee A. Woolsey

Enterprise Unmanned Traffic Management is a holistic system concept evolving from technological developments in radio frequency where dynamic tracking can be added into current and emerging platforms. This is done through inexpensive RF sensors capable of real-time and cooperative, non-GPS tracking enabling digital visualization of assets, including unmanned aerial systems (UAS). The RF sensors are low size, weight, and power (SWaP), creating efficiencies in energy and material consumption while transmitting positions in real-time and at long ranges. Multiple UAS and other unmanned vehicles can be visualized for risk mitigation in operations,

Oct 17, 2022

By R. V. Ramani

Minerals, together with agricultural and forestry products, are the primary source of wealth produced in the United States. Although the production of minerals requires only a small fraction of the state's total land surface, as compared with either agriculture or forestry (Table 1), mining activities generally are much more disruptive to the land surface, and rehabilitation is more complex and costly. The past 10 to 15 years have witnessed a sharp increase in mineral exploration and mining, particularly coal mining, which has brought with it an increase in conflict over land use and an increase in negotiations for purposes of mineral prospecting and mining. The general increase in the production and consumption of coal and the particular increase in the percentage of coal extracted by surface mining methods coupled with a growing nationwide environmental consciousness have created increased public concern and in some cases outrage over mining activities. Although there is ample evidence to indicate that it is possible to plan for and design mining activities in such a way that they are compatible with other activities and can thus be made a part of a sequential land-use plan, there is a general lack of knowledge regarding the importance of mining as the provider of basic and essential raw materials to supply society's constantly expanding and increasing mineral needs. This lack of knowledge extends to such matters as land and mineral rights negotiations, the character of mineral deposits and minerals, mineral economics, and land-use planning.

Jan 1, 1977

By Alan Boughey

The world's largest grinding mill operates at the Cadia Hill Mine in Australia. Svedala Industries supplied the 12.2-m- (40-ft-) diam, 20-MW Cadia gearless, semiautogenous grinding mill (SAG). This was a leap of more than 40% above the largest operating SAG mill. This article reviews the significant items involved in the development, design, manufacture, installation and operation of this mill. Description of the Cadia project The Cadia Hill Mine is located 25 km (15 miles) southwest of Orange, in the Central Tablelands of New South Wales, Australia. The mining lease covers about 3,100 hm2 (7,660 acres) of the Cadia Valley. The Cadia deposit is a large, homogeneous, low-grade, porphyry-type, gold-copper resource. Current reserves stand at 202 Mt (222 million st), grading 0.73 g/t (0.02 oz/st) gold and 0.17% copper. They contain 146.2 t (4.7 million oz) of gold and 347 Kt (382,500 st) of copper. The operation consists of openpit mining and ore processing to produce gold bullion and a gold/copper concentrate. The operation processes 17 Mt/a (19 millon stpy) of ore to produce 91 kt/a (100,300 stpy) of concentrate and 9.1 t/a (293,000 oz/year) of gold. The plant operates two 12-hour shifts a day and had a targeted availability of 94%. The plant facilities include a copper concentrator, o water supply system, an openpit mine, tailings pipeline and dam, and a concentrate pipeline and dewatering facility located in Blayney, about 35 km (22 miles) from the concentrator. Significant features of the process plant include o primary crusher and stockpile, a reclaim conveyor system feeding, the Cadia SAG mill (Figs. 1 and 2) and two 6.7-m- (22-ft-) diam ball mills (Fig. 3). A portion of the gold is extracted in a gravity circuit. The balance is extracted with the copper in the flotation section of the plant. Concentrate is thickened and piped about 35 km (22 miles) to the filter plant and rail loadout facility located in Blayney. Tailings are pumped to a tailings dam and process water is reclaimed from the tailings dam. The water system is designed to control and capture available runoff from local creeks, and to store these waters in dams and weirs. In addition, a major portion of the water for the process plant is treated effluent from the city of Orange and a smaller portion from Blayney Mill selection. The low-grade ore posed a dilemma for Cadia. To achieve a satisfactory economic operation, large-scale processing was required. The selection of the mills, equal to the largest designed and operated at the time, gave a plant configuration consisting of two 11.1- x 5.8-m (36- x 19-ft) SAG mills and three 6.1- x 9.1-m (20 x 30-ft) ball mills. This configuration did not provide the most satisfactory economic model for the project. A review of the single line configuration indicated that a significant reduction in the overall capital cost of the plant could be achieved by increasing the size of the mills and reducing the quantity. Increasing the size of the mills,

Jan 1, 2001

By Carrie Smith

The Society for Mining, Metallurgy & Exploration’s annual conference and expo, MINEXCHANGE 2026, will take place Feb. 22–25, 2026, at the Salt Palace Convention Center in Salt Lake City, UT. The event will foster a hub for innovation, technical exchange and policy discussion for the global mining industry. Over four days, attendees will take part in short courses, technical sessions, field trips and networking events that highlight the advancement of the mining industry. The conference’s keynote session, titled “Regaining America’s Mineral Dominance,” will start at 8:30 a.m. on Feb. 23 in the Grand Ballroom E–J. The speaker will address the sweeping policy actions now shaping the nation’s mineral future, following a series of executive orders issued by the Trump administration designed to bolster domestic mineral production and energy security. These directives, including Immediate Measures to Increase Domestic Mineral Production (EO 14241) and Establishing the National Energy Dominance Council (EO 14213), have set in motion a coordinated effort across the Departments of Interior, Energy, Defense and Commerce to enhance the United States’ position as a global leader in critical minerals. The invited speakers include Utah Governor Spencer J. Cox and Nate Foster, managing director of Rio Tinto Kennecott, who will examine how policy and industry are converging to meet surging demand for minerals essential to modern technology. Governor Cox is expected to highlight Utah’s long-standing role in American mining, from the early development of Kennecott Copper to its current position as a producer of 40 of the nation’s 50 identified critical minerals. Foster, meanwhile, will offer insights into Rio Tinto’s extensive operations in Utah, including the Kennecott Copper Mine — one of only two operating copper smelters in the United States — and the company’s ongoing efforts to build more resilient, sustainable supply chains. Rio Tinto’s work in critical mineral production, from copper and tellurium in Utah to new operations in Arizona, has made it a fundamental figure in the U.S. mineral economy. Projects such as the Resolution Copper development and the revival of Gunnison Copper using Rio Tinto’s innovative Nuton technology illustrate how private-sector leadership is driving sustainability in domestic mining. These advancements come at a critical moment for the industry, as copper prices remain near historic highs. The keynote session will emphasize that meeting future mineral demand will require a concerted effort between government, industry and technology partners to secure responsible, domestic production. Immediately following the keynote, the Robert E. Murray Innovation Award Lecture will start at 10 a.m. as part of the same session. Lucy England, managing director at FLSmidth, will present on “Sustainable Copper Mining Flowsheets and the MissionZero Mine.” England, who has spent more than 25 years in mineral processing and innovation, will discuss how FLSmidth’s MissionZero initiative aims to develop the world’s most efficient

Feb 1, 2026

By Henry E. Swanson

In the early 1960's the Company, then named the United States Smelting Refining and Mining Company, was drilling the Continental ore body located near Fierro, New Mexico. Reserves of underground ore of sufficient quantity were indicated to build a mill. At the same time some ore from the Continental No. 1 mine was being milled at the Company's Bullfrog Mill, formerly a lead-zinc mill. The copper ore in comparison to the lead-zinc ores was very hard, abrasive, and heavy. These factors pointed out the possibility and attractiveness of autogenous grinding. While prior to this some study had been given to autogenous grinding, no large scale tests had been made. Such a program was carried out and from the pilot plant data the following was established: 1. Grinding of the ore by autogenous means could be accomplished. 2. This could be done in one stage; however, not at a satisfactory tonnage throughput rate. Thus, the use of a secondary unit has been employed. 3. Grinding in the secondary unit could be done by pebbles generated in the primary unit. This resulted in the scheme whereby the ore would be ground 100% autogenously. 4. Liberation of the copper minerals was excellent so that good recovery at a satisfactory concentrate grade would be obtainable.

Jan 1, 1976

By A. M. Whiting

Competition for coal producers and their primary customers has constantly increased during recent years. The effects of the Clean Air Act Amendments of 1990 on the electric utility industry, coupled with the normal complexities of coal production, quality control, transportation and contracting techniques have spurred both buyers and sellers to increase their level of sophistication. This paper will review the basic aspects of the U.S. coal business and explore the commercial approaches which have proven to be most successful.

Jan 1, 1994

By L. L. Chasko, D. W. Alexander

Researchers from the National Institute for Occupational Safety and Health’s Office of Mine Safety and Health Research conducted an assessment of the effects that ground control mesh might have on rock and float coal dust distribution in a coal mine. The increased use of mesh to control roof and rib spall introduces additional elevated surfaces on which rock or coal dust can collect. It is possible to increase the potential for dust explosion propagation if any float coal dust is not adequately inerted. In addition, the mesh may interfere with the collection of representative dust samples when using the pan-and-brush sampling method developed by the U.S. Bureau of Mines and used by the Mine Safety and Health Administration for band sampling. This study estimates the additional coal or rock dust that could accumulate on mesh and develops a means to collect representative dust samples from meshed entries.

Jan 1, 2014

By C. E. Golson

Modern concrete technology emphasizes the basic qualities required of an acceptable aggregate: it must be clean, sound, homogeneous, and of a size gradation resulting in a concrete of the desired physical qualities at a minimum cost. In the case of coarse aggregates, crushing, scrubbing, and screening will usually provide the required material, although beneficiation is often necessary in order to eliminate unsound or deleterious fractions. Beneficiation is also applicable to fine aggregates,( but the processes most often employed are washing, classification, and dewatering.

Jan 1, 1959

By Martino Scialpi, Miriam Piemontese, Claudio Cimiotti, Matt Kendall, Nicholas Karlin, Roberto Schuerch

The Los Angeles, California JWPCP effluent outfall tunnel will transport secondary-treated effluent from the Joint Water Pollution Control Plant in Carson to the White Point Manifold. Upon completion, through ground conditions ranging from soils to hard rock, the tunnel will be approx. 7 miles (11 km) long with a finished internal diameter of 18-ft (5.5 m). This paper will present the Tunneling Condition Assessment Report (TCAR) and Tunnel Operation Plan (TOP) developed prior to construction, as well as the actual TBM performances achieved along the northern portion of the alignment in soft ground, shallow cover, and beneath a densely urbanized area.

Jun 23, 2024

By J. L. Coburn

The Huari-Huari ore body is located in Southern Bolivia, at an elevation of approximately 3,800 meters above sea level. The ore is a complex massive sulfide, slightly marmatitic sphalerite, in a fault fissure filled hypo- thermal vein in Paleozoic shales and quartzite-altered sandstone. The sphalerite has common associations with pyrite and quartz and is frequently intricately intergrown with stannite, chalcopyrite, and pyrrhotite. The sphalerite also contains numerous inclusions of pyrite, marcasite, galena, boulangerite, jamesonite, quartz, arsenopyrite, and cassiterite. A research program was undertaken to develop a flowsheet for the recovery of separate silver, zinc, and tin concentrates by selective flotation. Based on this experimental work and subsequent flowsheet development, engineering and construction of a 500 metric ton per day concentrator was undertaken. This paper describes the process that was developed for the Huari-Huari ore and the unique aspects of the Huari-Huari concentrator.

Jan 1, 1977

By J. Noll, A. Miller, J. Volkwein, C. Pritchard

Hecla Limited, Magee Scientific and the U.S. National Institute for Occupational Safety and Health (NIOSH) combined efforts to evaluate an in situ air filtration system for use in an underground mine environment. The purpose of the collaboration was to determine the efficacy of such a technology for reducing the concentration of airborne diesel particulate matter (DPM), with the aim of improving air quality in underground hardrock mines. A secondary goal was to evaluate the use of an aethalometer as a means of real-time measurement of black carbon as a surrogate for DPM. The evaluation included measuring the DPM-capture efficiency of the filter when it was preloaded with dust. Toward this end, rock dust was introduced at the filter inlet to create a dust layer on the filter surface, with the intent of providing improved capture of the much smaller DPM particles. The filtration efficiency for DPM was assessed by comparing measurements of DPM taken at the inlet and outlet of the system, using both realtime and time-weighted-average approaches. The real-time measurements were performed with a Model AE33 aethalometer, and filter samples analyzed by the NIOSH 5040 method were used to assess the effects of the system on time-weighted-average concentrations of total carbon. Results showed a reduction in DPM concentrations in the range of 82 to 89 percent. While the calculated efficiencies based on the two different measurement methods were similar, the DPM levels reported by the aethalometer were higher, possibly due to differences in the performance of the size selectors used for the two methods: impactors versus cyclones. More research is required to develop a robust correlation between the two methods to support the use of the aethalometer in future mining applications. The advantages of the aethalometer are that it can measure and record DPM levels for weeks at a time and can be directly connected to a mine monitoring system, potentially at multiple locations. Ideally, such data can be used to initiate the startup of the filtration system should DPM concentrations reach an action level. This work demonstrated that in situ filtration systems, modified to collect DPM and coupled with real-time monitoring, show promise in reducing DPM concentrations in the mine environment.

Mar 1, 2017

By Olav K1omstad1ien

The lean, but extensive iron ore deposits of the Dunderland Valley north of Mo i Rana, Norway, is the raw material for the Rana Mines which is a division of the state owned steel mill A/S Norsk Jernverk. Activities for the exploitation of the orebodies were commenced in 1902 by the English Dunderland Iron Ore Company. During its operating period the company constructed a total of two large scale concentrating plants. The activities were strongly marked by technical problems and labor disputes. Thus actual production was limited to the years 1904-1908, 1928-1931 and 1937-1939. During these periods a total of 1.9 million tons of crude ore was mined and 0.6 million tons of concentrates produced for export. The present plant commenced operations in late fall of 1964. Up to and including 1976 about 26.6 million tons of crude have been put through the concentrating plant and about 10.7 million tons of concentrate produced.

Jan 1, 1978

By Duane A. Smith

Introduction From the days of the Spanish in the eighteenth century, Colorado's San Juan mining district has attracted miners and public interest. The Spanish left behind names - San Juans, La Plata, Animas, legends of lost mines, and the remains of a few scattered mining operations. They came, but did not stay. Again in 1860-61, as a spinoff of the Pike's Peak gold rush, prospectors climbed the mountains and descended into the canyons searching for gold. They found some, not enough to convince them to remain and confront the isolation, often hostile environment and the Utes, who rightfully felt this to be their home. Not until the 1870s did miners come to stay. In their wake little camps grew in the high valleys and squeezed into narrow canyons. Nowhere else in Colorado were there more rugged mountains, a higher average elevation, nor a climate that one old Swede said was "three months of mighty late fall and nine months of winter." The San Juans proved eventually to be a mineral treasure chest. At the moment, however, the prospectors sought gold. Then they discovered silver deposits and the first rush was on. It got started just in time to be completely overcome by the Leadville excitement. At Leadville, investors almost fell over themselves to buy claims and stock in the hopes of becoming another millionaire like Leadville's own Horace Tabor. The San Juaners could only look from the sidelines and speculate how it might have been had fate been kinder. Fate was seldom kind, as these pioneers quickly discovered. From the mid-1870s on, the San Juaners wrestled with some major problems. And the fate of their district rode in the balance. The problems they faced were similar to those of other Colorado districts, compounded by their geographic isolation. Every mining district needed the best transportation system available, experienced investors combined with sound investment, and mineral reserves to develop. The San Juans offered the last in abundance. It was hoped the first two would appear. Railroads - much needed transportation link Nothing was more desired than railroad connections, the penultimate nineteenth century form of transportation. Colorado's own, the Denver & Rio Grande, resolved the issue with its mountain-hugging narrow gauge. As early as the mid-1870s, the D&RG dreamed of tapping this potentially lucrative market in southwestern Colorado. A national economic depression and then the Leadville silver excitement prevented immediate construction. Not until 1879-80 did survey crews start work.

Jan 2, 1988

By Y. V. Vasylchuk

An algorithm is presented for optimizing the classification of surface mine material subject to excavating constraints. High-resolution, expected-profit models are optimized to classification maps subject to site-specific excavating constraints. This optimization problem defies traditional closed-form analytical solutions. A practical heuristic algorithm quickly determines the optimum final destination for material subject to realistic selectivity constraints. The expected profit could be calculated from an estimated model if the value calculations are all linear; otherwise, simulation could be used. In both cases, a single expected profit for all destinations on a high-resolution grid is the starting point for dig limits optimization. Maximizing expected profit in a risk-neutral manner is correct given the repeated nature of grade-control decisions over relatively short timeframes.