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By T. I. Nelson

Natural aggregates, primarily stone, sand and gravel, are recovered from widespread, naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size, and sold either loose or in concrete products to build roads, houses, buildings, and other structures. Smaller quantities are used in agriculture, cement manufacture, and industries employing chemical and metallurgical processes. The growth of cities, their buildings and the highways that connect them have created demand for enormous quantities of aggregates. The aggregates industry is the largest mining industry in the United States in terms of production by weight, volume and by number of active operations.

Jan 1, 2005

By Glen Frank, David R. Chapman

Determining the number of boulders and cobbles that will be encountered in the tunnel envelope is one of the most difficult problems confronting the geotechnical engineer in the design of tunnels in glacial terrain. This issue is very important to the contractor, both in determining what methods will be used to construct the facilities and the advance rate that can be achieved for the chosen construction methods. The cost of constructing tunnels by pressurized face tunneling techniques is very sensitive to accurate characterization of the very coarse fraction (large cobble and boulder sized clasts), and no standard method is current available for characterizing boulders and cobbles. Careful use of large diameter borings and the sampling and analytical techniques outlined in this paper can provide a means to answer this difficult question. By performing large diameter borings and carefully recording and sampling the cobbles and boulders encountered, an estimate for the amount of these materials present in the formations sampled can be provided. Using this method allows the designer to communicate the expected geologic conditions to the prospective bidders in a manner that is both definitive and defensible. This paper describes the method as it was used in conjunction with the design of a large diameter sewer tunnel in the Columbus, Ohio area.

Jan 1, 2005

By Don Painter, Nico Sutmoller, Lori M. K. Kahikina, Brian Dorwart

This paper will address the feasibility of using low-density cellular concrete (LDCC) for an annular fill application where project conditions required pumping the LDCC material for distances of up to 16,000 feet. These conditions occurred during construction of the Kaneohe-Kailua Sewer Tunnel in Oahu, Hawaii, between 2014 and 2018. Located on the island of Oahu, Hawaii, this 13-foot-diameter rock tunnel extends for approximately three miles from the Kaneohe Pre-Treatment Facility to the Kailua Regional Wastewater Treatment Plant. The tunnel was built to convey wastewater and provide temporary storage for peak wet weather flows entering the collection system, thereby reducing the potential for uncontrolled discharges. LDCC was chosen for this project partly due to its environmental benefits, which were essential for an application contiguous to the inland marine and coastal waters of the Pacific Ocean. In order to ensure optimal performance characteristics—compressive strength (with a requirement of 300 psi at 56 days), flowability, and light weight—were achieved, extensive testing of various LDCC products and mix designs was completed. The testing measured the initial set time of the LDCC as well as the compressive strength needed to reduce the quantity of grout lifts required for the project.

Jun 13, 2021

By S. Watkins, D. Apel, B. Gray, R. Moss

Currently, there are several techniques and technologies available which are used by mining industry in its attempts to remotely monitor the ground movements both at surface and underground mines. The currently available remote distance meters and distance change monitors mainly use phase change and time-of-flight techniques. The described monitor uses triangulation technique to track position of an optical spot projection and then image processing to measure mine wall movements. The system can be easily automated and poses no obstruction to mine traffic. The position of an off-normal laser spot will shift as the target wall moves. The described ground movement monitoring system has potential for superior accuracy and target monitoring can be made through air (gaseous) or other transparent media. The theoretical accuracy and range of this system depends solely on the resolution and focal length of the camera being used. The remote capabilities of the system make it uniquely suited to applications where monitoring is required in high-traffic, inaccessible, or unstable and dangerous areas of a mine.

Jan 1, 2007

"Foreword by Emily SarverAssistant professor, Mining and Minerals Engineering, Virginia Tech, Blacksburg, VAThe Mineral Processing Division hosted its fifth Student Poster Contest during the 2014 SME Annual Meeting and Exhibit in Salt Lake City, UT – and, by all accounts, it was a huge success! This year, the contest more than doubled in numbers of individual entries and schools represented. A total of 30 students participated, including 23 graduates and 7 undergraduates, representing 13 US and international institutions: Colorado School of Mines, Michigan Tech, Missouri University of Science and Technology, Montana Tech, New Mexico Tech, South Dakota School of Mines, University of Kentucky, University of Utah, Virginia Tech, West Virginia University, Autonomous University of Chihuahua (Mexico), UNAL Medellin (Colombia), University of British Columbia (Canada). In addition to constructing their posters, students submitted abstracts and gave short oral presentations highlighting their research. Based on tallied scores from all three components of the contest, the judging panel selected 1st, 2nd and 3rd place winners at the undergraduate and graduate levels, which were announced during the MPD Luncheon on February 26.In the undergraduate division, University of Utah’s Lucas Pich was awarded the 1st place prize for his poster “Solid-liquid mixing studies in lab-scale flotation tank using electrical resistance tomography.” His extended abstract is included in this issue of Minerals & Metallurgical Processing. Joshua Chidester, also of Utah, won 2nd place for his poster presenting “Evaluation of detectors for radiotracer RTD measurement by MCNP.” And Lucas Rojas-Mendoza, of UNAL Medellin, took 3rd place for his poster on “Preg-robbing in Colombian gold ores.”In the graduate division, 1st place went to Caelen Anderson, of the Colorado School of Mines, who also placed in this contest in 2012 and 2013! The 2nd and 3rd place prizes were awarded to Jacob McDonald and Joseph Halt, respectively, both of Michigan Tech. Extended abstracts describing the work of these up-and-coming researchers are also included in this issue.The 2014 Contest was chaired by Emily Sarver (Virginia Tech) and Lisa Schlink (Freeport-McMoran Copper and Gold, Inc.). Aaron Noble (West Virginia University), David Perkins (Derrick Corporation) and Derek Novotny (Eriez) graciously served on the judging panel this year.Special thanks are extended to all sponsors of the 2014 MPD Student Poster Contest, and to all student participants. Please watch for upcoming details on the 2015 Contest. We look forward to seeing you in Denver!"

Jan 1, 2015

By R. L. Guerguerian

Critical fasteners are described as they apply to the specification, manufacture, and assembly on large grinding mill bolted joints. The importance of adequate design methods, related joint diagrams and pivot analyses, and special emphasis on the quality of manufacturing and the tightening procedures in the field, are discussed; all in an effort to ensure high availability plant operation.

Jan 1, 2001

By Massimo Concilia, Remo Grandori, Paolo Nardone

Paul Y. – SELI Joint Venture had been contracted to build the longest section of the Strategic Sewage Disposal Scheme (SSDS) – Stage I. This involved two tunnels under urban and marine areas excavated by high performance hard rock open type TBMs operated from deep shafts. A specific ground treatment program was developed using advance probing and grouting to control water inflow into the excavations. The article describes: the technologies adopted, the experienced problems, the encountered productions and their interrelation with the water inflow amounts, the possible improvement in the technologies for the excavation of the future stages of the same project as well of any other project under similar conditions.

Jan 1, 2001

By G. C. Hall, B. E. Hobbs

Giant gold deposits are considered products of crustal-scale systems. Reduced fluids stored in mid to lower crustal reservoirs were discharged into mid to upper crustal sites of deposition. Elements of the architecture include crustal-scale structures, reduced packages of rock and regional seals. Gas-rich aqueous fluids were common but non-aqueous fluids may have been significant in the deeper parts of the systems. Fluid fluxes in over pressured domains were maintained by porosity waves. Abnormal heat input from the mantle may not be required once the systems were perturbed. Fluid-mixing and hypogene enrichment were probably the most significant precipitation processes.

Jan 1, 1999

By Y. V. Swamy, B. Bhoi, H. S. Ray

Low-grade manganese ores with low Mn/Fe ratios can he enriched through selective carbon reduction of iron oxide to magnetite followed by magnetic separation o f the magnetite. Thermogravimetric analysis (TGA) was used to assess the preferential isothermal reduction of pure M1702 and Fe2O3 using solid carbon. This was followed by reduction of a synthetic analogue of composition comparable to an actual low-grade ore (i.e., Sandur manganese ore, Sandur, India). The carbothermic reduction of the manganese ore converts the hematite and goethite minerals to magnetite (Fe3O4), with the magnetite then going into the magnetic, fraction. The resultant nonmagnetic ,fraction becomes depleted of iron with an enhanced manganese content. These results show that it is possible to reduce the iron from 22% to 5.85%, thus increasing the Mn/Fe ratio from 1.52 to 6.2 with a manganese recovery of about 50%. The recovery was, further improved by grinding the magnetic fraction to -75 µm.

Jan 1, 1999

By Richard A. Thomas, III JAMES H. ROWLAND, Liming Yuan

This paper presents the results of large-scale fire experiments on evaluating the performances of carbon monoxide (CO) and smoke sensors at low ventilation velocities. Experiments using three different combustibles — conveyor belt, coal and diesel fuel — were conducted in the experimental mine at the U.S. National Institute for Occupational Safety and Health (NIOSH) Bruceton Research Facility. A total of eight sensor stations were located downstream of the fire with each station containing sensors for CO, smoke, carbon dioxide (CO2 ), oxygen (O2 ), humidity, barometric pressure and temperature, as well as two airflow sensors. The airflow velocity ranged from 0.22 to 0.26 m/s (44 to 51 fpm) in the tests. The response times were recorded for the CO and smoke sensors at each sensor station when smoke and gaseous products of combustion from each burning combustible reached the station. The response times of the CO sensors were used to determine the appropriate sensor spacing in the belt entry with a low air velocity. The performance of the smoke sensor was found to be affected by the high humidity in the experiments. The results on proper selection of sensors and the determination of sensor spacing at a low ventilation velocity can be helpful for ensuring sufficient early fire warning for underground workers, thereby improving the health and safety of miners.

By George C. Hawley

Historically, mica usage has been low because of limited availability; as a by-product of many small processors, who have lacked motivation for extensive R & D. The discovery of a 30 million ton deposit of 85-90% pure phlogopite, when existing markets are only 300,000 tonnes annually, forced the search for large volume new markets. Increasing costs of energy, petrochemicals, plastics and glass fibers, and environmental constraints on asbestos usage, have led to new opportunities for mica as a reinforcing filler. Extensive research and developments; in beneficiating, processing and treating mica, has been necessary to satisfy these new markets.

Jan 1, 1981

By Mark J. Zdunczyk

"The term “aggregate” has a number of definitions depending primarily on the use of the material. Aggregate in some context is sand, gravel, crushed stone, slag or other material of mineral composition used in bituminous and portland cement concrete, mortar, plaster, railroad ballast, filter beds and a variety of other uses where aggregates can be utilized.Of the natural aggregates, crushed stone is widely used for most construction purposes. Crushed stone can be mined from a variety of rock types such as limestone, dolomite (dolostone), granites, and granitic type rocks, basalt, gabbro (trap rock), sandstones, schist, marble, gneiss, quartzite, rhyolite, as well as other rock types. The U.S. Geological Survey (USGS) breaks down the rocks by type sold as follows: limestone, dolomite, marble, calcareous marl, shell, granite, trap rock (basalt, diorite) sandstone/quartzite, slate, volcanic cinder and scoria and miscellaneous stone.In 2015, the USGS estimates that 1.32 Gt (1.45 billion st) of crushed stone were produced in the United States. The volume of crushed stone produced, and the numerous mines that produce it make the crushed stone industry the largest mining industry in the United States. The five leading states for production of crushed stone in 2015 were Texas, Pennsylvania, Missouri, Florida and Ohio. The size of the first two states certainly helps in output because of the large market area. The remaining states benefit from being able to barge along rivers to outside markets in adjoining states. Georgia producers rail large amounts of granitic aggregate to Florida and adjacent states devoid of crushed stone aggregate, especially skid resistant aggregate (aggregate used on the top course of asphalt roads)."

Jul 1, 2016

By S. G. Malghan

W.H. Moyer In reference to the section “Excess pyrite, ” the author discusses difficulties in separating chalcopyrite from pyrite. A technique does exist, and has been used commercially, for the flotation, separation, and recovery, if desired, of both chalcopyrite and pyrite. The method was described in Mining Engineering, March 1966, “An Improved Flotation Method for Cornwall Sulfides. ” While it was not used on a porphyry copper ore, it was used on a chalcopyrite - pyrite-containing ore and might well have application. Both sulfides, chalcopyrite and pyrite, were floated simultaneously using xanthate as a collector and MIBC frother to produce a cleaned sulfide product. This concentrate was then thickened and conditioned at high solids with aeration and lime to a pH above 12.0 for a period of 1.5 to 2 hr. A supplemental suppressant, such as cyanide, could be used if necessary to sharpen the subsequent separation; however, it was not required at Cornwall. The conditioned sulfides were floated with two stages of cleaning to produce a highgrade chalcopyrite froth product and a pyrite sink product barren in copper. The separation at Cornwall gave a 28.6q. Cu grade chalcopyrite product and a pyrite analyzing 0.0670 Cu. A desliming step on the raw ore initially used at Cornwall for a period of time was later discontinued. Advantages to be found in using a strong sulfide collector, such as a xanthate, is the rapid flotation it induces and, generally, an ability to float at a coarser grind. A following regrind circuit could be used to give maximum liberation and produce a clean sulfide concentration. The “differential” separation is concerned primarily with grade and with assuring a barren pyrite for maximum recovery.

Jan 11, 1986

By T. K. Bundtzen, C. B. Green

Exploration expenditures in Alaska last year amounted to $8.9 million. This was comparable to 1985's $9.1 million. Development expenditures dropped 29%, $24.3 million in 1986 vs. $34.1 million in 1985. The exploration industry is restructuring and stabilizing after the loss of major mineral firms during the last few years. These included Anaconda Minerals, Asarco, Hecla Mining, Enserch Exploration, Phillips Minerals Division, Exxon Minerals, Noranda Inc., General Crude, Mohawk Oil & Gas, Inspiration Development, Teton Exploration, and St. Joe Minerals Division. Some of these companies were mineral subsidiaries of oil companies and were either dissolved or redirected to programs outside of Alaska. However, recent entry exploration firms include Echo Bay Mines Ltd., Long Lac Minerals, and Exvenco. They are busy evaluating prospects and mineral developments in the southeastern panhandle. In the 1970s, about $254 million was spent on Alaska mineral exploration. Of this, about 5% ($12 million) was for nonmetallics and coal, about 26% was directed at precious metals ($66 million) mainly gold, and 69% ($175.3 million) for the base metals zinc, copper, molybdenum, tin, tungsten, and nickel. Since the early 1980s, trends have reversed. Of the nearly $196.3 million spent from 1981-1986, 48% has been for precious metals ($94.3 million) and 40% on nonmetallics and coal. In the last two years, nearly 70% of the Alaskan exploration dollar has been spent in search of precious metals. Three gold skarns were explored during the year - the Nixon Fork project in western Alaska (Battle Mountain Mining Co.), the Nebesna and Rambler lodes of the northern Wrangell Mountains (Nebesna Mining Partners), and the Zackley project near Paxson in southcentral Alaska (Nerco Minerals). Nearly 7.6 km (25,000 ft) of diamond and rotary drilling were conducted on these three properties. Aspen Exploration announced that significant gold mineralization was found under the Nome coastal plain in western Alaska. Meridian Minerals joint ventured with Resource Associates of Alaska, exploring precious metal

Jan 5, 1987

By Anthony Leddin, Gillian Dooley

This paper is concerned with mineral policy in Ireland and how it might be improved to encourage more exploration and investment in mining in the country. The approach is to first outline the main desirable characteristics of a comprehensive national mineral policy document. This aspirational document is then used to assess the current regulatory, legislative and fiscal frameworks for mining in Ireland. The analysis also contains a brief account of the history, structure and characteristics of the mining industry in Ireland. The main focus of the paper is to identify those aspects of the existing framework that erode Ireland’s attractiveness to mineral investment and to suggest policy improvements.

Jan 1, 2005

By C. Laughton

The Deep Underground Science and Engineering Laboratory (DUSEL) is to be constructed at the defunct Homestake Mine, in South Dakota. As a cornerstone of DUSEL?s research program, it is intended to conduct experiments into the fundamental nature of neutrino and proton particles. The experimental apparatus required to con-duct these experiments will be housed in large rock cavern(s) sited at depths of over a kilometer. As conceived, these cavern(s) are planned to have mined volumes of up to half a million cubic meters, and spans of approximately 50 meters. The paper will describe key end-user requirements, and outline the in situ rock conditions and mine site constraints that are likely to play determinant roles in identifying candidate sites and developing cost-effective design options(s).

By G. R. Giuliani

Hanna Mining Company's Groveland Mine is located in the Upper Peninsula of Michigan. The low grade iron ore deposit consists of a mixture of magnetite and hematite with chert, jasper, quartz and various iron silicates (1). The ore is beneficiated by magnetic separation and anionic flotation of the iron minerals with chemical depression of the silica. The magnetic concentrate makes up about 75% of the concentrate. The concentrate is pelletized at the rate of 2.0 million LTPY of pellet production. The concentrator facilities were started up in 1959 and the concentrate was marketed as sinter feed until 1963 when the concentrator was expanded and the pelletizing plant was added. The pellet plant now consists of regrinding, elutriation, filtering, balling and induration. The pellet machine is a straight grate which employs updraft drying and cooling and downdraft drying, preheat and firing. It is necessary to regrind the concentrate before pelletizing. The con-centrate is 60% passing 325 mesh, with a surface area of ±lOOO cm2/Gm, and must be ground to about 83% passing 325 mesh, 1600 cm2/Gm blaine surface area, for pelletizing. The energy for regrind has been reduced from 12.5 KW per LT to 8.80 KW ate of 2.0 million per LT. This was the result of changes made in the concentrator where originally a coarse spiral concentrate, instead of the magnetic concentrate which is screened on fine screens to reduce the coarse fraction and prevent overgrinding before flotation, was produced. Also in 1968 an additional concentrating line was added to the concentrator which employs more grinding power than the other three lines. The demand for a high iron grade and lower silica pellet resulted in the investigation of different schemes of upgrading the reground concentrate which had more iron values liberated during grinding for surface area. The reagentized material presented many problems, mainly in selectivity trying to flot the iron and with high reagent consumption having to dereagentize the concentrate for amine silica flotation, in the various flotation systems tried. Tests were then conducted with elutriation (2) which proved satisfactory by removing the lower specific gravity, fine gangue material from the heavier material with the

Jan 1, 1977

By William J. Douglas

Critical path modeling (CPM) has been used widely as a tool to manage large-scale projects having many activities which are conducted in series or parallel. The construction industry is a regular user of critical path modeling as a planning tool. In this context, the method is used to provide an orderly schedule for all activities to forecast delays, slippages, and problem areas and to identify critical activities where resources should be directed. It also identifies others which have slack time, and provides information on the degrees of freedom and flexibility available in completing the project. The purpose of applying critical path modeling to an underground mining system is not primarily for scheduling, but as an analysis tool. In observing underground mining systems, it Is clear that repeated sequences of activities must take place for mining to proceed efficiently. Some of these activities must be sequential, while others be carried out in parallel. The fundamental difference between critical path modeling applied to mining versus a large-scale construction project are: (1) The activities in a mining system are cyclic in nature. (2) The location of the activity varies, and the entire process is not thought of as co-located, as is the case in a construction project. Another important aspect of the network development for mining systems is the degree of detail that is desired. One can be concerned with very macroscopic networks which represent, for example, an entire mine life cycle. Networks representing this problem would be more closely analogous to those of a large construction project. On the other hand, one might be interested in evaluating alternative ways of developing a property or of mining in a given section. More detailed networks representing the section activities are necessary to evaluate system parameters and their impact on long-term production.

Jan 1, 1978

By A. D. Davis

Naturally occurring arsenic has been detected in water from inactive mines and several wells in the Keystone area of the Black Hills. Keystone City Well #4 showed a total arsenic concentration of 69 parts per billion (ppb) during pumping in 2004. The well is not used currently except for arsenic-removal research. Water also can be pumped from a mine shaft in the abandoned Keystone ? Columbia ? Bullion gold mines, whose interconnected workings flooded after mining ceased in the 1930s. This water has been considered for local supplies, although it would require treatment or blending because of arsenic concentrations. According to historical records, the Bullion Mine produced 100,000 pounds of white arsenic. An aquifer test on the mine workings was performed at a pumping rate of about 550 gallons per minute. The arsenic concentration in pumped water was 33 ppb. In addition to wells within Keystone, samples from the water supply at nearby Mount Rushmore National Memorial have shown arsenic concentrations greater than 10 ppb, the U.S. Environmental Protection Agency?s maximum contaminant level for arsenic in drinking water. Limestone-based technology for removal of arsenic from drinking water is an innovative and promising method that has been considered for treatment of water at Keystone. In batch testing with water from Keystone Well #4, limestone removed about 65% of arsenic from solution. A related problem of arsenic removal from drinking water involves disposal of the waste product, which is critical for commercial viability of removal technologies. Current research is investigating thermal stability of the waste in order to determine the potential for recycling of the material during manufacture of cement.

Jan 1, 2010

By W. S. Fyfe, G. Southam, T. J. Beveridge

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An invitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold(which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14%within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%)throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999