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By Mirko Martini, Marcelo Benaglia, Andrea Codalli

Riachuelo Lot 3 forms part of a sanitation programme being implemented in Argentina to relieve the Riachuelo river basin from its current contamination. The programme, by far the most important in its kind in the country during the last decades, will expand the sewage capacity of Buenos Aires and will benefit an area of 4.3 millions inhabitants by intercepting a number of waste water discharges and conveying them to a new treatment plant prior to final discharge into the Rio de la Plata. The project foresees amongst other works the construction of an onshore 48 m deep shaft at the outlet of the treatment plant plus a 4,3 m inner diameter outfall tunnel of 12 km length. The last 1.5 km of the alignment is fitted with 34 vertical risers jacked from inside the tunnel to allow the discharge and dilution of the treated effluent into the Rio de la Plata. This paper describes the peculiarities and challenges, both in terms of design and in terms of construction, of the outfall tunnel, which was entirely bored under the Rio de la Plata using a 5.2 m cut diameter Tunnel Boring Machine (TBM). On one hand, the tunnel segmental lining was designed to work in tension during the system flow rate peaks while on the other the tunnel excavation faced a variety of complex conditions, such as crossing water bearing permeable soft ground formations and advancing at face pressures in excess of 3,5 bars for the entire route.

Jun 13, 2021

By Robert C. Freas

Genesis 1:28 "And God blessed them and God said he fruitful and multiply and replenish the earth and subdue it and have dominion over it." Genesis 2:15 "And the Lord God made man and put him in the garden to dress it and keep it." Depending on one's perspective, these two verses from the Book of Genesis either complement one another or are in conflict. I believe that they are complementary. What they imply is that where there is privilege, there is responsibility. Privilege comes from the fact that the Lord created the heavens and the earth and he placed man on the earth to have dominion over it. The responsibility that accrues to us comes when the Lord also said that we are accountable for how we handle that which he has given us. The very nature of our responsibilities in resource utilization or, more appropriately, resource management, has changed over time as the nation's needs and priorities have changed. Thus, I have attempted to examine, from a historical perspective, how natural resource policy has evolved, where we are now and what may lie ahead.

Jan 1, 1995

By D. R. Hanson, H. Lawson

In this study, NIOSH researchers conducted a machine learning analysis to examine whether a model could be constructed to assess the probability of dynamic failure occurrence based on geochemical and petrographic data. Random forest, cluster analysis and dimension reduction were all applied. The objective of dimensionality reduction was to explore patterns and groupings in the data and search for relations between compositional parameters. Cluster analyses were performed to determine if an algorithm could find clusters with given class memberships and to what extent misclassifications of dynamic failure status occurred. A random forest analysis performed on data from the Pennsylvania Coal Sample Databank cross-referenced with accident data from the Mine Safety and Health Administration (MSHA) determined that 7 parameters of the 18 examined exerted the most influence on results. Cluster analysis on data after dimensionality reduction resulted in a hierarchal clustering algorithm finding four clusters, with one relatively distinct dynamic failure cluster, and three clusters consisting mostly of control group members but with a small number of dynamic failure members.

Feb 1, 2023

By H. G. Stephenson, D. Castendyk

Open pit anthracite mining at the Canmore Creek Mines, Canmore, Alberta, south of Banff National Park, resulted in several pit lakes by the early 1970’s. To enable future mining opportunities in the Rocky Mountains, operators decided to reclaim the site into a non-polluting landscape which would provide a memorable outdoor experience for residents and visitors alike, and would preserve wildlife habitat. Reclamation began with the stabilization and revegetation of spoil piles adjacent to Canmore Creek, and the backfilling and revegetation of Canmore Creek Mines No. 1 and 2 to create “Salamander Pond.” The company dammed the outlet of an open pit at Canmore Creek Mine No. 3 to raise the water level and create Quarry Lake. Reclamation concluded in 1980 when the Town of Canmore took ownership. Quarry Lake is now the centerpiece of 293-acre Quarry Lake Heritage Park, a popular destination for swimming, hiking, and fishing, visited by about 400 people on summer days. The Alberta Environment Conservation Authority described this as “The best mine reclamation in Western Canada.” Quarry Lake is an exceptional example of walk-away, pit lake closure, where the mining company created a valued post-mining asset and was released from future liabilities. INTRODUCTION One of the most important environmental issues associated with contemporary open pit mining is the closure of mine pit lakes, and the perpetual legacy these lakes can potentially generate. Ideally, successful pit lake closure includes the following: (i) the water quality within the pit lake, plus surface water and groundwater discharging from the pit lake, meets pre-mining, or other acceptable water quality conditions of the receiving environment, (ii) the termination of all active treatment processes, (iii) the return of the pit lake to the government for long-term care and maintenance, (iv) the release of the mining company from all future liabilities associated with the pit lake, (v) the return the environmental bond to the mining company, and (vi) the reuse of the pit lake for some post-closure, beneficial purpose. The achievement of these goals is known as “walk away, pit lake closure.” Peer-reviewed, publications of successful walk away, pit lake closure provide mining companies the ability to address public concerns regarding the safety of pit lakes which commonly occur during the permitting, operations, and closure phases of mining. To date, most published work on walk away, pit lake closure work has occurred in the coal mining sector in Germany and Australia (McCullough et al., 2009; Jones and McCullough, 2011; Kumar et al., 2013; Schultz et al., 2013). However, in North America, examples of walk away, pit lake closure are not widely discussed in the literature despite there being excellent examples from the coal mining sector in Alberta, Canada (e.g. Pleasure Island, Black Diamond, East Pit, Sphynx, Robb, Lovette, Siltstone, and Sterling), and from the iron mining sector in Minnesota in the United States (e.g. Portsmouth Lake, see MNDNR, 2018). Although seldom included in discussions of pit lakes from the metal and coal mining sectors, the aggregate and fabricated-stone mining sectors also produce pit lakes, and there are numerous examples throughout North America where these pit lakes have been successfully closed and transformed into post-mining resources. The difficulty of finding these good examples in the literature makes it challenging for companies to respond to public and regulatory questions regarding pit lake closure and reuse. As such, there is a pressing need document the motivations and approaches used in examples of successful, walk away, pit lake closure in North America so that the mining industry at large can learn from these examples and can better address public concerns.

Jan 1, 2019

By U. S. Geological Survey Staff

"In 2017, the total estimated value of nonfuel mineral production in the United States increased by 6 percent from 2016 (Table 1). The value of metals produced domestically increased by 12 percent and the value of industrial minerals produced domestically increased by 3 percent. Some metal commodity values (cobalt, magnesium metal and palladium) increased by more than 35 percent in 2017 from 2016 owing to higher prices.Some U.S. metal mines and processing facilities remained idle in 2017, including three primary aluminum smelters in Indiana, Missouri and Washington; a titanium sponge facility in Utah and a byproduct vanadium production facility in Utah. In contrast, new gold mines opened in late 2016 and 2017 in Nevada and South Carolina, respectively, and iron ore mines in Michigan and Minnesota restarted or operated for the full year. In addition, increased oil and natural gas drilling activity led to increased production of some industrial mineral commodities that are used for oil and gas drilling. Production of some industrial minerals, especially those used in infrastructure and residential construction, remained essentially unchanged in 2017, a reflection of the limited growth in construction activity. The production of some metals, including iron and steel, aluminum and other nonferrous metals and nonmetallic mineral products increased. Overall, mining activity trended upward as the result of increases in coal mining, oil and gas extraction and metal mining (Table 2).Discussion of mine production is commonly segmented according to the type of materials produced within the broad categories of metals and industrial minerals (also known as nonmetallic minerals). Industrial minerals can be further subdivided as construction aggregates and other industrial minerals. Metals tend to have higher unit values but very low production quantities compared with those of industrial minerals, such as crushed stone or construction sand and gravel, which have higher production quantities but are lower-valued materials. Therefore, for discussion and analysis of the performance of the nonfuel minerals industry, the value of production is used rather than the tonnage produced. Tonnages of natural aggregates are orders of magnitude larger than those for most other mineral commodities, thus making direct comparisons based on weight meaningless (Fig. 1)."

Jan 5, 2018

By Tomás Vergara, Marcelo Vergara, Alonso Pereira, Fernando Concha, María V. Gutiérrez, Fernando Betancourt

Filtration of copper concentrates in the mining industry is carried out in cycles, mainly cake formation, expression, and blowing. Each of these cycles depends on the solid (mineralogy, porosity, particle size distribution), water, and air (density, viscosity, permeability, and relative permeability) properties that define the performance in each cycle. The fundamental phenomenon in cake formation and expression is a one-phase flow (water) through a porous bed of solid particles (the cake), while in blowing it is a two-phase flow (water and air) through the cake. Sometimes, due to a change in the properties of the mineral, a filtration plant is unable to maintain the capacity at the specified humidity. One alternative to solve this problem is to heat the air during the blowing cycle, which in turn heats the water in the cake, this process significantly decreases the water viscosity and only marginally increases the air viscosity. In this work, this strategy was studied at a laboratory scale. The results show a significant decrease in the blowing time as the temperature of the air was increased.

May 24, 2022

By J. B. Griffiths

Clearly there is a tremendous need for assistance in Eastern Europe since most industries must undergo major restructuring. The new governments face many dilemmas, the first task being to establish an order of priorities to deal with the numerous problems at hand. Issues such as the standard of living take low priority compared with market economy and ecological problems. The concept of a Comecon market is now virtually non-existent and trade in roubles ceased from 1991. From this time onwards countries were obliged to trade using free market prices. Governments must also avoid the economic mistakes of countries such as Poland with its high devaluation and lack of economic control and, if possible, contain inflation and unemployment. The privatization of Eastern European enterprises raises considerable difficulties, particularly for large corporations, employing anywhere from 50-100,000 people, which played a major role in the national economy. Whichever method is selected, however, still has to overcome the problem of lack of capital and evaluating the national property. For example, earnings represent only a small percentage of the value of these national industries and thus cannot convert to private ownership without foreign capital investment, either direct or as joint venture capital.

Jan 1, 1992

By C. M. Goodall

Solids and liquid phase residence time distribution data is reported for a laboratory column flotation cell. The effects of various physical flotation parameters on residence time distributions are reported and analyzed. A plug flow model with recycle is proposed for the froth phase and a tanks in series model for the pulp. By comparison of two and three phase residence time -distribution data it has been shown that the use of liquid residence time distribution data to predict the residence time distribution of the solids in a column is not valid.

Jan 1, 1990

By L. S. Gertsch, M. Z. Abu Bakar

The research presented here is part of a project to quantify the differences in the mechanical excavatability of rocks in dry and water-saturated conditions. A series of full-scale laboratory linear rock cutting tests were carried out with a long-bladed single disc cutter on dry and water-saturated sandstone blocks. The muck collected from the cutting tests was analyzed to establish a link with the specific energy (SE) of the operation. The coarseness index (CI), a non-dimensional parameter, was found to be a useful indicator of the relative efficiency of the cutting operation. An inverse relationship of the form SE = k CI-n was observed between SE and CI. The power n of the relationship for both dry and saturated rock was much lower than found in previous studies. The exponent n is believed to be dependent on the strength of the rock and the cutter type used. Although the average CI was lower for saturated rock than for dry rock, at the same time, saturated rock cutting was found to be less energy-intensive (in terms of SE) than dry rock cutting. Moderate correlation exists between the production rate or yield and the SE of the cutting operation for both dry and saturated rock, which can provide some useful information about the field production rate, discounting the effect of discontinuities in the rock mass.

Jan 1, 2012

By Hillary W. St. Clair

In a previous report 1/the author showed that the essential information from particle size analyses of grinding mill products can be represented by three or four parameters derived from the first four moments of the particle size data. These parameters may be used in gamma or beta distribution functions to estimate the weight fraction in any given size range. Moment analysis was used to study the progressive changes that take place in particle size distribution when a homogeneous isotropic mineral such as quartz is reduced in size by impact crushing. 2/ This report briefly reviews the essential features of moment analysis and describes extension of this method to size reduction by ball mill grinding.

Jan 1, 1972

By M. R. Yalamanchili

Recently, noequilbrium electrokinetic measurements using laser-Doppler electrophoresis were reported by Miller et al. (1992) for alkali halides and the sign of their surface charge thus determined. These results are generally as expected from simplified lattice ion hydration theory with KCI, under normal circumstances, being the most significant exception. In this regard, lattice defects (F centers and oxygen imperfections) have been found to influence the surface charge of KCI and its electrophoretic mobility. In particular, the presence of oxygen defect states in the crystal lattice has been found to be responsible for KCI's unexpected behavior. The concentration of oxygen defect states in KCI, as characterized by UV/Vis absorption, was varied in order to study their influence on the electrokinetic behavior and subsequently on the flotation response of KCl. At low oxygen contents « 60 ppm) KCI is positively charged as expected from lattice ion hydration theory. However, typically, KCI contains substantial oxygen (>300 ppm) sufficient to impart a negative surface charge which accounts for the selective flotation of KCI from NaCl by hetero-coagulation with oppositely charged alkyl amine hydrochloride collector colloids.

Jan 1, 1994

By T. Good

Twin roll sizers are neither compactly designed machines nor are they configured to accommodate underground mobility; in fact, twin roll sizers leave room for improvement in many aspects of the design. The DRC1200 capitalizes on the weaknesses of these machines to make a more productive, easily maintained, and compact twin roll sizer than current market offerings. These strides were made through the inception of the Hard Rock Extraction System (HRXS), which requires a mobile sizer as part of the system. After use of a third party sizer on the HRXS, potential improvements were evident. These improvements include improved structural design to reduce overall footprint and an optimized design to reduce operating cost.

Feb 23, 2014

By D. Van Orden, Y. Kamiya, R. Lee, E. Ilgren

Crocidolite is a well-known causative agent for mesothelioma. However, studies have shown that the pathogenicity of the fiber from different mines varies considerably and it has been postulated the parameter that appears most likely to account for this variation is fiber width although this has never been formally confirmed. To date, crocidolite appears to be the only asbestos mineral for which an epidemiological study comparing the risk of mesothelioma in a population exposed to ‘thin’ fibers with another exposed to ‘thick’ fibers of the same species may be carried out. Finnish anthophyllite, South African amosite, and African Transvaal crocidolite can also be classified as thick fibers, and there is a paucity of mesotheliomas in populations exposed to them compared to those exposed to thin Cape crocidolite. No thin occurrences of these minerals are known. Our previous study looked at crocidolite from several sources. The present study considers the amphibole anthophyllite found in many places in the world. This mineral, regardless of source, does not show the same variation in fiber width found with crocidolite from different areas. All anthophyllite fibers that have been mined may be classified as thick and populations exposed show very low levels of mesothelioma. We suggest the most likely explanation is related to the fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By R. E. Vivas

Goldcorp is one of the largest gold producers in the world with projects in South, Central and North America. Goldcorp?s flagship operation is Peñasquito, a world-class, poly-metallic deposit that started production in 2010 which is one of the largest mines in Mexico. Since the early stages of the project, Goldcorp has used the most advanced technologies available to maximize its value. However, the implementation of optimum mine plans has been challenging to put into practice. This is due to the fact that the mine operation involves more complexity than the plans usually reflect. This challenge is an industry wide issue that presents opportunities for improvement. This technical session discusses the mine planning methodologies and procedures used to connect long, medium and short term planning strategies in order to bridge the gap and produce optimum mine plans that can be practically implemented in the field.

Feb 23, 2014

By J. Tavares

It is no mystery why the mining industry has such lofty safety standards. In dealing with Mother Nature and gravity, the combination of the two can create significant hazards from high wall and tunnel collapses to huge landslides. The loss of production from a major disruption could be enormous. The price tag on the loss of human life is immeasurable. The evolution of geotechnical instruments and software has been ongoing for years. But the biggest innovations have occurred during the era of cell modems, internet, and wireless networks, allowing for real time data and alarms to be delivered globally anywhere and anytime to one?s computer, laptop and smartphone. Yet in some ways you can thank the urban construction projects for developing much of the technology in use by today?s mines. Due to the density of population and the billions in dollars of structures and infrastructure in cities throughout the US and the world, urban projects have faced intense scrutiny for years. Out of this scrutiny was born the necessity of real time automated monitoring of instrumentation and sensors, a defence against catastrophic failures, and real time early warning systems through alarms that can and do saves lives. It is also possible to identify areas of concern with subsequent remediation prior to failure.

Feb 23, 2014

By J. A. Ober

"In 2016, the estimated value of total nonfuel mineral production in the United States was $74.6 billion, a slight increase from the revised total of $73.4 billion in 2015 (Table 1). Increased construction activity spurred increased production of industrial minerals, especially those used in infrastructure and residential construction. Although starting the year relatively low, prices for several metals, especially for some of the precious metals, began to trend upward. Decreased production of most metals produced in the United States, however, contributed to an overall decline in the value of metal production.Several U.S. metal mines and processing facilities were idled or closed permanently in 2016, including iron ore mines in Michigan and Minnesota; three primary aluminum smelters in Indiana, Missouri and Washington; one secondary zinc smelter in North Carolina; a titanium sponge facility in Utah and titanium mineral operations in Virginia. In addition, in May, the weekly average rig count for oil and gas drilling reached its lowest level since the 1940s when that measurement was first recorded. The reduced drilling activity resulted in decreased production of some industrial mineral products used in the drilling sector. Trends in mineral-related sectors of the domestic economy declined or held steady, except in the manufacturing of nonmetallic mineral products and nonferrous metals excluding aluminum, which increased. Overall, mining trended downward as the result of significant declines in coal mining, oil and gas extraction and metal mining (Table 2). Discussion of mine production is frequently segmented according to the type of materials produced within the broad categories of metals and industrial minerals (also known as nonmetallic minerals). Industrial minerals can be further subdivided as construction aggregates and other industrial minerals. Metals tend to have higher unit values but very low production quantities compared with those of industrial minerals, which have higher production quantities but are lower-valued materials, such as crushed stone or construction sand and gravel. Therefore, for discussion and analysis of the performance of the nonfuel minerals industry, the value of production is used rather than the tonnage produced. Tonnages of construction aggregates are orders of magnitude larger than those for most other mineral commodities thus making direct compar"

Jan 5, 2017

By Randall D. Peterson

Strip mining with draglines and other surface equipment has traditionally been the method of choice for mining shallow deposits. This is particularly true for soft deposits that require little or no blasting. High rates of productivity and low operating costs have set this standard. However, these methods can be improved. Strip mining methods are batch processes and difficult to accommodate in processing. Moreover, they are encumbered with overburden removal, reclamation expense, and human inefficiencies. This paper describes the invention of a novel shallow earth mining technique called the Softwall Mining Method. Softwall Mining is an adaptation of longwall mining for loose earth conditions. The method was specifically invented for recovering phosphatic clay ore from beds in North Central Florida, but is likely to be suitable for a number of other minerals as well. Potential deposits for which the method may be well suited include placers, disseminated deposits in soft host rocks, bauxite, soft coals and lignite deposits, and other deposits where overburden will subside readily and where the ore can be hydraulically broken and slurried. Unit operating cost advantages are expected over the current dragline systems used. The Softwall mining advantages are its high rates of productivity, control and automation of the mining process, reduction of dilution and waste, and elimination of the majority of stripping and reclamation.

Jan 1, 1998

By R. A. Allwes

In-plane bending and torsion tests were conducted on full-scale masonry walls to evaluate three post-reinforcement designs. The designs were developed to minimize longwall mine subsidence damage to existing residential masonry foundations. The bending tests show that vertical and horizontal post tensioned tendons significantly increase the resistance of a masonry wall' to in-plane bending. The torsion tests reveal that post tensioned tendons increase a masonry wall's limit of deformation but do not increase its torsional stiffness. The torsion tests also show that the masonry units minimally contribute to the torsional stiffness of a masonry wall.

Jan 1, 1995

By K. Neumann

"INTRODUCTION For many automation and safety tasks in open cut and underground scenarios it is crucial to have highly reliable distance measurements at hand. These measurements can for instance be used to obtain the exact position of a machine in one-, two- or even three dimensions. Research and development has shown interest in the ultra-wide-band technology (UWB) in recent years. While for this technology short range, high speed data transfer is the current main research focus, the technology can also be used for highly accurate ranging applications. Due to the use of a very wide frequency band, it is robust against disturbances of many types (e.g. EMC, rain, dust etc.) and is therefore attractive for the use in mining applications. The wide frequency band also offers benefits for ranging applications. Especially in environments with strong multipath problems such as in underground mines it is possible to focus on the dominant signal propagation path, thus increasing the reliability of the measurements. [1] State-of-the-art UWB ranging equipment claims precision within the range of a couple of centimeters and working ranges of more than hundred meters. At the Institute for Mining and Metallurgical Machinery (IMR) at RWTH Aachen University in Germany a modern UWB system was examined in several laboratory and real life tests to examine the feasibility of UWB bases ranging equipment in mining applications. UWB TECHNOLOGY The term ultra-wide-band denotes radio systems that use an ultra-wide frequency band. A common definition for UWB radio systems is that it needs to work on a frequency bandwidth of more than 500 MHz or a bandwidth equal to 20% or more of the center frequency [1]. Due to the ultra-wide frequency bandwidth UWB systems overlap the frequency spectrum of narrow band radio technologies like Wi-Fi, Bluetooth and other mobile communication systems which use a defined carrier frequency onto which information is modulated on (e.g. by using frequency or phase modulation). In order to not conflict with these other radio applications, it needs to be ascertained that the transmission power of a UWB system on a given frequency is so low that narrow band systems are not affected by it. As opposed to this only a small fraction of the UWB system’s bandwidth is affected by the narrow band system. The unaffected remaining bandwidth is sufficient to reconstruct the original signal, even if additional noise is present. Figure 1 shows the power spectral densities of popular radio standards [6], [7], [8]. A significant driver of research and development of UWB systems has been wireless high bandwidth communication. Using an ultra-wide frequency band is highly desirable here, as the channel capacity is dependent on the bandwidth. So far systems have been realized especially for short distances (e.g. wireless USB or Wireless HDMI) but beyond that, communication systems for long distances (several kilometers) are possible [2]. Advances in semiconductor technology led to a reduction in power dissipation of such systems. This enabled higher integration levels which in turn facilitated smaller solution sizes for space constrained applications [3]. Nowadays, UWB is also used for high-precision ranging applications [4], [5]."

Jan 1, 2015

By S. G. Sawyer

The Pittsburgh Safety and Health Technology Center (PSHTC) of the Mine Safety and Health Administration (MSHA) provides engineering and scientific support to the inspectorate personnel of MSHA. One of the Center's myriad roles is to assist in the investigation of mining accidents, especially those involving fatalities. Center personnel utilize forensics to help uncover the causes of accidents and to make technical recommendations on the prevention of future similar mishaps. To exemplify a typical forensic investigation, this paper documents the methodology used in determining the reasons for a boat sinking, which resulted in a double fatality on a mine company pond.

Jan 1, 1997