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By T. Dombrowski

Acid-activated montmorillonite is used worldwide as a catalyst and as a sorbent for the enhancement and purification of petroleum products as well as vegetable and animal-based fats. The solid-acid character of the activated montmorillonite is imparted by the manufacturing process, giving it unique properties that are exploited in these industries. Several international companies and a multitude of local clay producers are focusing on improving the efficiency of their standard and specialized products. This paper will describe the use of acid-activated montmorillonite in traditional sorbent applications, as a solid acid catalyst, and other new uses.

Jan 1, 1997

By C. C. Graham

In this paper, the problems which occurred on introduction of dense medium cyclone coal washing in Australia are reviewed together with the subsequent measures taken to obtain a satisfactory magnetite. Specification and testing of magnetite for exploration, quality control and in-plant check purposes is discussed. The disposition of Australian magnetite deposits in relation to the main coal producing areas is examined, and comments are made on the economics of mining, milling and beneficiating magnetite for coal preparation uses alone. Future trends in the Australian Coal Industry are predicted, and the need for a planned approach for the future is demons traced.

Jan 1, 1982

By Van E. Housman, Stephen D. Hoffman

The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), also known as "Superfund", requires a listing of sites that have known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the U.S. When EPA determines that a significant threat exists, it places the worst contaminated sites on the National Priorities List (NPL). CERCLA provides EPA broad authority to clean up hazardous sites that threaten human health and the environment. There are currently 52 sites on the NPL that were placed on the list because of high human health or environmental risk as a result of non-coal mineral extraction, beneficiation, or processing operations. This list covers mining sectors from aluminum to zinc. While some of these sites were abandoned, many are still operating. (There are additional mine sites that have been recently proposed to be included on the NPL that are not included in this paper.) EPA is continuing to develop a mining program to address human health and environmental threats from active non-coal mines. EPA has performed a comprehensive study to assess the waste management practices at all of the 52 mine sites on the NPL. In addition, EPA is continuing to collect information on the specific mining sectors (i.e., gold, copper) that represent many of the NPL mine sites. One of the goals of this effort is to attempt to identify the types of mining practices that lead to human health and environmental problems at the NPL mine site. EPA estimates that there are currently 500 to 1,000 active mines (not including placer operations). While some mining NPL sites began operations before the turn of the century, only a handful of the NPL mines entirely ceased operations prior to 1970. Of the 52 NPL sites studied by EPA, 12 are currently active. By definition, these mines represent current mining practices. Approximately 17 additional NPL mines that ceased operations between 1970 and 1990 represent some degree of current mining practices. Therefore, at best, less than half on the 52 NPL mine sites can be said to definitely represent past mining practices. Although some mining waste management practices have changed over time, the basic technology for extraction and beneficiation of mineral ores have remained fairly constant over the last fifty years. While the use of acid to leach copper dumps, the use of cyanide to leach gold in heaps, and the spread of solvent extraction techniques has changed some aspects of mining, the basic operation of removing ore from the ground and concentrating it through beneficiation has remained fundamentally the same as when most of the non-active

Jan 1, 1992

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"The history of Duluth commences with Daniel de Greysolon du Lhut, one of the explorers of the Upper Mississippi who came to the head of the lakes in the summer of 1679. Radisson and Groseillier, and Claude Allouez, a Jesuit priest, are supposed to have visited the head of the lakes, -but there is no authentic record previous to that of du Lhut.In 1792, the fur traders established a fort at Fond du Lac, fifteen miles up the St. Louis River from Lake Superior, but within the limits of the present city •of Duluth. In the early 50's, there were a few scattering settlers at Oneota and around the George Stuntz trading post on Minnesota point. In 1855-6, the settlement on Minnesota point was called Duluth, commemorating the name du Lhut, and organized as a town in 1857. The first board of trustees and town council consisted of -William Nettleton, J. B. Culver; Robert E. Jefferson, Grin W. Rice and William Old: In 1870, the city of Duluth was incorporated, and five years later a portion of the same territory was incorporated as the village of Duluth, and the two municipal corporations were still in existence on March 1, 1887, when the city and the village of Duluth were incorporated as the present city.The first saw mill in Duluth was erected in 1856-57, on the present site of the ship canal. It cut logs from a virgin forest at the upper end of Minnesota point.The first railroad was built to the head of the lakes in 1870. The charter for this road had been granted in 1861 to the Lake Superior and Mississippi Railroad Company, afterward called the St. Paul and Duluth, and which is now a part of the Northern Pacific Railroad."

Jan 1, 1920

By Myron W. Mellor

Much has been published concerning the subject of coal preparation as related to electric power generation however it is always a most vital topic for both utilities and coal producers, It also constitutes a field of study that is never finished since new concepts and changing demands continually require altered perspectives. One graphic illustration that has been used to emphasize the rapidity with which times are changing is the fact that during World War I, a station that consumed 1000 tons per day was looked upon as a large central station, while today some single generators require 1500 tons during the same period, For further emphasis, at that time a 20,000 horsepower turbo-generator was a mighty large machine; today, a unit of this size is planned for driving the boiler water feed pump required for a single large main unit. During the past ten years alone, electric utilities have more than doubled their percentage of coal consumed as compared to the total market. They now account for approximately 40% of the United States consumption and one-third of all production including export, Conversely, approximately 70% of all U. S. steam electric generation is by coal and this percentage is expected to increase. It is further predicted that utility consumption will increase from the current 160,000,000 tons per year to between 400 and 500 million tons in 1975 which is approximately equal to todays total production

Jan 1, 1959

By Kyle Amoroso, Aaron K. McCain

Frozen soil shoring has been used for decades in the tunneling industry to provide temporary support of excavation for shafts and cross-passage excavations. However, horizontal penetrations through the frozen soil can prove to be challenging. The key to creating a stable portal through frozen ground is managing and mitigating groundwater flow into the excavation through the annular space surrounding the drill stem or casing. This paper will review different approaches that have been successfully used to penetrate frozen soil shoring on multiple projects.

Jun 13, 2023

By A. Porvali, V. Agarwal, M. Lundström

Hydrometallurgical recovery of rare earth elements (REE) from NiMH battery waste can be performed using sulfuric acid leaching followed by selective precipitation as double salt (REENa(SO4)2•H2O) by adding Na2SO4 as a precipitating agent. The formed double salts can be treated further with NaOH solution to form REE hydroxides. This study focuses on metamodeling of a simulated flowsheet with design of experiments (DOE). Based on literature survey, a process flowsheet was developed using HSC Sim software. The created flowsheet focuses on circulation of solution containing Na+, K+, SO42- ions and impurities liberated in the NaOH treatment of double salt precipitate. The effect of seven parameters (P1-P7) on seven responses (R1-R7) were modeled using central composite design (CCD). INTRODUCTION Nickel metal hydride (NiMH) battery waste can be considered as an urban mineral due to the presence of valuable metals like: Ni, Co and rare earth elements (REE) (Larsson et al., 2013). In NiMH battery waste leaching experiments, sulfuric acid has often been employed as a lixiviant (Pietrelli et al., 2002,Zhang et al., 1999,Rodrigues and Mansur, 2010,Porvali et al., 2018). The key advantages of sulfuric acid are its stability and cost-effectiveness compared to other mineral acids such as HCl and HNO3. However, the usage of sulfuric acid in NiMH battery waste leaching poses simultaneous challenges and advantages. Limited REE solubility can be taken as benefit when recovering REEs double sulfates after solid-liquid separation. However, sodium and potassium hydroxide, present in electrolyte residues in the battery waste, can cause in-situ precipitation already during leaching due to limited solubility, thus decreasing the total REE recovery (Porvali et al., 2018). However, this problem can be circumvented by washing the electrolyte residues off the raw materials. Subsequently, the REEs may be precipitated in bulk as a mixed double salt out from the solution at very low pH with minimal co-precipitation of Ni and other metals. This relatively easy separation method can be extremely advantageous in the case of such a complex solution matrix with relatively high REE concentrations (conc.). Once REEs have been precipitated as double sulfates as per eq. (1) (Porvali et al., 2018), the resulting double salt precipitate lacks applications without further treatment. Direct thermal treatment would generate sulfur dioxide emissions and likely require high temperatures in order to transform double sulfates into REE oxides. Furthermore, the precipitate contains Na ions, which would need to be removed by chemical treatment from the calcined REE product. In the context of circularity of raw materials, it can be taken of a remarkable benefit if the sodium and sulfur present in the double salt could be reused instead of wasting them into the side streams. To that end, in this simulation study, the double salts are converted by dissolution and precipitation to hydroxides which are readily treatable, e.g. with total dissolution and solvent extraction, for further purification (Abreu and Morais, 2010):

Jan 1, 2019

By Ottmar Burghardt

Sintering of iron ore has undergone a dramatic development world-wide. Today, the annual world production amounts to approximately 600 million tons. At present, the sintering process in competition with pelletizing, seems to offer certain advantages inasmuch as it allows the use of solid fuels. Also, its charging behaviour in the blast furnace is, in general, considered as being better than that of pellets. This is true, in particular, for the charging behaviour and the gas permeability in relation to the grain size. Moreover, instead of charging limestone into the blast furnace, for instance, the basic components which are necessary for the burden materials can generally be supplied in a simpler and more cost-effective way by using basic sinter instead of basic pellets. While in sintering, with basicity rising to the range of 1.6 to 1.8 CaO : SiO2, the capacity increases and the sinter quality shows improvements in most of its characteristics, the pro¬duction of basic pellets generally requires a higher fuel rate, when compared to acid pellets, while production capacity decreases and some of the quality characteristics deteriorate.

Jan 1, 1982

By J. M. Link

A technique is presented for the economic selection of a slurry pipeline with the aid of a computer. Mathematical models for the flows of homogeneous slurries are utilized. Only the pipeline and its prime movers are considered. Slurry flow properties are first obtained from rheology and/or pipeline data measurements. A rheological model is then selected for the slurry. It must be emphasized that the accuracy of the method is greatly affected by the accuracy of the slurry flow-property data. Approximate cost parameters may be selected from data for plain and lined pipes, centrifugal and positive displacement pumps, motors and engines. Cost data for the purchase, operation and maintenance of slurry pipelines are also described. A total cost equation for the ownership and operation of a slurry pipeline system is then established. The complexity of the equation is a function of the rheological model selected to describe the slurry. The equation is solved with the aid of a computer for several combinations of pipeline diameters and throughputs to yield minimum total annual cost for the system. A mean velocity is then computed to give the required throughput. The velocity is constrained by an upper and lower bound. A high velocity is undesirable from an energy consumption viewpoint and if pipeline wear is possible. On the other hand, the velocity must exceed the deposition velocity for a heterogeneous suspension or the critical velocity for a homogeneous suspension. There is no guarantee that the velocity developed by this method will lie within the constraints applied, nor that the constraints are even known. This is particularly true for heterogeneous slurries. An important feature of the method is the ease with which the variables can be adjusted to measure the sensitivity of the total cost to the variables. The purpose of the sensitivity analysis is to identify those critical variables that. if changed, can considerably affect the total cost. Mathematically, individual variables are changed and the effect of such a change on the annual total cost is computed. But from a designer's point of view, individual components in the system are changed to study their effect on the annual total cost. A change in one component of the system may involve a change in one or more variables. For example, the replacement of a steel pipe by a smooth-lined pipe will change the pipewall roughness and wall thickness as well as purchase, operating, and maintenance costs.

Jan 1, 1974

You have been involved with research activities in froth flotation and size reduction. What do you think the future holds for these technologies? Froth flotation and size reduction are essential processing steps common to almost all current mineral-processing operations. The most significant recent advances in both of these technologies have been in the increased size of equipment and in some alternative machine designs, such as the column cells and the high-pressure roller mills. I believe that the next major area of improvement in size reduction will be at least partially driven by an improved awareness of controlling the conditions that influence the efficiency of particle breakage. This would include factors such as water-chemistry influences, the influence of fines from classification, chemical grinding additives and better rheology control. In froth flotation, significant changes are currently taking place in the plant use of frothers. Also, there will be an increasing number of new collector chemistries for certain types of flotation, such as with oxide minerals, oxidized mineral recovery in sulfide systems and improved selectivity with certain sulfide mineral systems. You have been active in implementing new engineering technology in industry. What do you think will be the technological future of mineral processing? Being involved in the invention and industrial implementation of new technology has been one of the most positive experiences of my career. I also have had the unique experience of working in the chemical and petroleum industries as well as in mineral processing. In my opinion, the future of mineral processing will be an exciting, wonderful work area in which to be involved. The development of new technology in minerals processing offers a special challenge compared, for example, to that of chemistry or chemical engineering. In successful industrial innovation involving minerals, having a sound theory is not enough. Instead, what is required is a valid blend of a good idea, meaningful laboratory characterization and, most key, the experience necessary to adjust the plant in such a way to incorporate the idea. The complexity of engineering systems that contain solids, liquids and gases, as well as highly variable natural mineral properties, means that nothing new comes easily. In some cases, it has been difficult to explain how processes practiced in industry for decades actually work, in terms of physical and chemical fundamentals. On the other hand, when a new idea is successfully implemented, the economic and professional returns can be very rewarding. I know of no more challenging field of engineering than minerals processing. What is your view of the future of the minerals industry in general? The need for minerals, metals and coal will be with us for decades to come. In many aspects, the minerals industry became global much earlier than some of the other industrial sectors that are currently experiencing globalization. I believe that fair international competition is beneficial to the users of minerals, metals and coals and to those involved in producing such materials. The key word here for a global economy to work is "fair." So the various playing fields involved such as finance, profit return, regulation and labor should be relatively level for all the players involved. Competition is an amazing driving force for innovation. This has been true in the minerals industry during the last few decades. The mining industry is producing more at less cost per unit than ever before in our history. I anticipate that this trend will continue as long as the global political situation remains relatively stable.

Jan 1, 1997

By John A. Dunn

The history of underground coal mining has developed through the years from a manual digging and loading process to the highly mechanized pro- cess that it is today through the use of electric power. Mine power systems have closely followed the continued pattern of improvement and mechanization, through necessity and the application of technological advances, At the beginning electric power used in coal mines was confined to haulage. Since d-c power was better suited to traction drives, mine power systems naturally developed using direct current. During this development, a number of street railway systems were in service, using 550 volts, and it was natural that mine trolley systems went in at 550 volts. As machines for mining operations developed and the number of operating mines increased, a safety hazard developed through the use of 550 volts. Most regulating agencies opposed the use of 550 volts, and after a time the maximum voltage permitted was limited to 300 volts hot line to ground. Up until this time most mines had operated with one central generating station, which served utilization power to the whole mine. Power demands were not very great and transmission losses were within reasonable limits.

Jan 1, 1964

By D. A. Shock

Utilizing the technology developed for oil well stimulation by hydrofracing, a disposal system which permanently fixes the waste has been proven. Large quantities of radioactive waste can be processed by a single well system making this method an attractive method for permanent radioactive waste disposal. The system depends on locating a relatively thick formation of impermeable, but easily fracturable rock such as a shale, creating a horizontal fracture, pumping the waste into the fracture in a form which will subsequently solidify and seal the fracture from the well system. The paper presents the theoretical considerations from creating and extending horizontal fractures and how these considerations were used in designing a waste disposal system which is now operating.

Jan 1, 1964

By J. S. Lewis

Beneficiation and physical and chemical processing of non-terrestrial materials borrow strongly from terrestrial experience, but also involve the necessity of handling literally un-Earthly feedstocks, reagents, and environmental conditions. The present state of scientific and engineering understanding of the processing of non-terrestrial minerals, gases and hydrocarbons is reviewed with the production of rocket propellants, life-support fluids, structural metals, and refractories as the goal.

Jan 1, 1992

By Saied S. Navid, Michael A. Piepenburg, Richard F. Escandon, Robert C. Lindsay

INTRODUCTION Phase I of the Los Angeles Metro Rail Project, known as MOS-1 (Minimum Operable Segment-1), is the first phase of the 27 km± (17 mi) subway starter line. MOS-1 is currently under construction and involves approximately 6.4 km (4.4 mi) of subway, five stations, yards and shops routed through the downtown area of Los Angeles. The project will form the initial heavy rail backbone of a more extensive light and heavy rail transit system planned for the greater Los Angeles area in the future. Construction Contract A-171 is one of 4 tunnel contracts within MOS-1 and involves construction of twin tunnels running from the downtown metropolitan area west to MacArthur Park. The heavily populated and developed downtown area, potentially gassy ground conditions, and the possibility of undocumented abandoned oil wells in seismically active southern California made the design and construction of Contract A-171 a uniquely interesting project. This paper summarizes the construction history to date (December, 1988) including design geotechnical considerations, tunnel support design, as-built geologic conditions, shield tunneling performance through soft ground, and ground response. The findings presented herein may aid in the design and construction

Jan 1, 1989

By Adam Saylor, Travis A. Shoemaker, Steve Miller

Lidar scanning has become an increasingly popular tool for documenting underground excavations; however, high costs of traditional mechanical electrical lidar hardware, software, and training have limited the frequency at which lidar scans can be performed. Additionally, traditional scanning can be time consuming because multiple scan positions are necessary. With Apple’s incorporation of low-cost mobile solidstate lidar on select smartphones and tablets, lidar is becoming more tractable for everyday construction documentation similar to construction photo collection with smartphones. Here, we describe benefits of mobile solid-state lidar and describe several practical applications for use in underground construction, such as documenting the working face, over-blast, and geologic features of tunnels.

Jun 13, 2023

By B. D. Hong

The Coal supply and demand review arrived too late to appear in the May issue. In 1991, the US coal industry produced 902 Mt (994 million st) of coal, according to preliminary data compiled by the Energy Information Administration (EIA) (Table 1). This amount was 32 Mt (35 million st) less than the record 933.5 Mt (1 billion st) produced in 1990. Most of the decrease in coal production occurred east of the Mississippi River. The substantial stock buildup that stimulated production in 1990 was not repeated in 1991. In addition, coal consumption by electric utilities and coke plants dropped by about 1.8 Mt and 4.5 Mt (2 million and 5 million st), respectively. Moreover, a higher level of coal exports failed to bolster the 1991 production. Production Surface mines accounted for about 59% of the 902 Mt (994 million st) of coal produced in 1991. Underground mines produced for 41%. More than one-fourth of the total coal output was from federal and Indian coal leases. Production of all ranks of coal, except subbituminous, declined in 1991. Bituminous coal is produced mainly in the East. It totaled an estimated 590 Mt (651 million st), a 6% decrease. Production of subbituminous coal, mostly in the West, rose 3% to a record 228 Mt (252 million st). Lignite output was from Texas and North Dakota. It decreased by 1 % to 79 Mt (87 million st). Anthracite production, all from eastern Pennsylvania, fell by 17% to 2.7 Mt (3 million st).

Jan 1, 1992

By Rainer Antretter

While respirable crystalline silica (RCS) dust that arises in industrial production mostly emanates from point sources and can be well mitigated, the extraction of dust is much more difficult in underground construction, since locally generated dust spreads widely. Analysis of dust measurements shows that RCS values are difficult to predict, and effective dedusting systems are required to comply with permissible exposure limits (PEL) in breathed air. Dedusting systems are effective near the tunnel face, while dedusting of working areas away from the tunnel face is difficult or even impossible. In general, there is little temporal influence on the tunnelling work—except for drill and blast excavation—which makes it necessary to remove the deduster and ductwork from the face area. Concurrent work in the tunnel is affected by the backflowing air mass of ventilation and therefore the quality of this air mass must be considered. The use of personal protective equipment (PPE), e.g., dust filter masks, is considered the least-desirable safety measure available. However, for certain individual operations in the tunnelling process, the use of PPE cannot be avoided, especially if other technical mitigation measures are not possible. In tunnels with small cross sections for example, dedusting systems often cannot be accommodated and PPE must be used instead. This raises the question of whether the use of PPE can be avoided by designing appropriate excavation cross sections and allowing for the implementation of technically engineered mitigation measures. The paper highlights problems with dedusting measures and shows possible ways to achieve OSHA compliance.

Jun 13, 2021

By A. D. Davis

Environmental impacts from acidic mine drainage are growing national concerns that are particularly acute in the headwaters of the Rocky Mountain region. In the Black Hills of South Dakota, approximately one thousand mines are inactive or abandoned, most of them in the headwaters of major drainages. This paper examines the Bear Butte Creek basin, a heavily mineralized watershed with significant historical mining impacts and a surface gold mine permitted in 1997. The watershed loses its surface discharge to swallow holes in the karstic Madison Limestone. The integrity of the aquatic ecosystem was monitored with a suite of site-specific bio-indicators. Stream surveys covered the entire reach of Bear Butte Creek from near its headwaters to the swallow holes in the Madison aquifer. Data from the stream surveys, water-quality sampling, and bio-indicator surveys clearly showed that water-quality impacts are limited mainly to Strawberry Creek and to the area of Bear Butte Creek near and downstream of the town of Galena.

Jan 1, 1999

By S. W. Mao

Hydrologic and economic criteria figure in many obvious ways in water resources development, but they are rarely linked quantitatively, and most of the applications are pertinent only to the case-in-point. In the preparation of the Regional Plan for the massive program of ground water development in the Punjab, situations have arisen where the choice among two or more alternatives was made by analyzing the economic implications of critical hydrologic parameters. Two of these situations which are of more-or-less general interest are described herein. The first involves basic development policy -- whether ground water development should be based on the demand of the economy, or the conservation concept of safe-yield. The analysis demonstrated that mining of ground water is clearly indicated for areas where alternative supplies are unavailable. The second problem involves integrating hydrologic data into an economic model to determine optimum well design, From an analysis of all pertinent factors, a simple nomograph was derived which can be used to determine well specifications on-site during construction. The nomograph can be modified for use in any alluvial terrain.

Jan 1, 1967

By Eugene C. Spilker

Cross country belt conveyors are becoming the preferred method of bulk material handling in the industrial complex. Installed cost, maintenance, reliability, simplicity and operating expense enhance this choice, especially when faced with rising cost and questionable availability of liquid fuels. Conveyor flights are getting longer, faster, and higher in capacity, and are being installed in rugged terrain. Rights of way are often difficult to obtain. All these considerations lead up to design aspects well beyond those for in-plant conveyors. This paper points out some of the aspects that lead to the successful design of a cross country belt conveyor system.

Jan 1, 1980