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By A. S. Kane

According to the 1966 Bureau of Mines Mineral Year Book only three states reported production of lignite in that year. These state: were North Dakota, Montana, and South Dakota; although it is known that there is production of lignite in Texas, California and, perhaps, Arkansas. In the year 1966 North Dakota produced 3,543,000 tons of lignite, Montana produced 328,000 tons of lignite, and South Dakota produced 10,000 tons of lignite. In view of the fact that North Dakota produces approximately 95 per cent of all the lignite reported in the United States, in discussing lignite mining, my remarks will be confined to lignite mining as conducted in North Dakota and will be confined to the production of lignite by stripping methods, as this is the predominate method used today. The first lignite mining in Worth Dakota, undoubtedly, was done by people settling in the western part of the state where wood was scarce and where lignite is exposed in the banks of creeks and ravines. The first production records were kept in 1884 and indicate that 35,000 tons of lignite were mined that year. The growth of the lignite industry has been very slow during the intervening period, but in 1966 production started to increase, and it is now indicated that production in the next few years may approach 6,000,000 tons per year. Ninety-seven per cent of the lignite produced in the lignite area of the Midwest is utilized in the generation of electric power, and it is anticipated that this use will predominate during the next two decades.

Jan 1, 1968

By Todd S. Webster, Matthew J. Pierce, Brad D. Krumel

With the Working Shafts and Starter Tunnel under way, it became apparent this 4.7-mile, 19-foot diameter wet weather tunnel was going to live up to its name. The shaft’s pre-excavation grouting was completed, and ground water inflows were slowing project progress. As the tunnel drive was approaching 50% complete a cooperative effort was underway between the owner, engineer, and contractor to raise the base of the Retrieval Shaft by 65 feet to avoid ground water infiltration construction challenges. The tunnel alignment needed to be raised in kind. The project was behind schedule and rethinking the cast-in-place adit work was next on the agenda due to the very wet environment in the tunnel. The race was on to finish the project within the owner’s time constraints while completing multiple redesign aspects of the tunnel alignment and associated adit construction. This paper will evaluate original design criteria and actual in-route design modifications and change management to meet the owner’s just-in-time schedule needs.

Dec 1, 2022

By David M. Rubio

The Ortiz Mine is an open pit-heap leach gold operation in central New Mexico processing about 3,100 tonnes (3,400 short tons) per day. It is the initial mining property in the United States developed by Gold Fields Mining Corporation, a subsidiary of Consolidated Gold Fields, PLC. This paper discusses the evolution of the present mining and ore control procedures as adaptions to the characteristics of both the rock being mined and the orebody, and with respect to the fact that mining is done by a contractor.

Jan 1, 1984

By K. L. Wiley

In-situ leaching, initiated in 1986 at San manual, was economically developed in 1989. The primary reason for this lag time between startup and viable production was the time required for technical development. The technical development pursued comprised detailed design, development, and implementation of in-situ well construction methods, formulation of suitable well pattern arrays, and the development of extensive hydrogeologic and geochemical knowledge of the mineral deposit. Since 1989, the in-situ leaching program has become a viable and cost effective method to extract copper from the supergene mineralized zone of the San Manuel deposit. The in-situ leaching methods that are currently utilized have been progressively expanded and continually developed and will became the cornerstone of copper production from the San Manuel oxide mineral deposit. This paper presents an overview of the supergene hydrogeology, current design techniques, drilling methods and well completion, pump determination and setting, solution management, and future plans for the increased extraction of copper by in-situ leaching methods at the San Manuel mine.

Jan 1, 1993

By Bruce C. Trent

In order to effectively model subsidence caused by underground openings, a two-dimensional computer code has been developed which couples near- and far-field response. The near-field is simulated by a discrete element block code and a finite difference code represents the continuum region in the far-field. The explicit equations allow rapid and inexpensive solutions to geometries which may lead to subsidence. Two sample problems are presented which illustrate the important features of the code.

Jan 1, 1979

By Ralf Plinninger, Pafos Busch, Richard Gradnik

This paper presents the details of the Bad Bergzabern tunnel project. This tunnel is the main part of the B427 federal road bypass, intended to improve the regional traffic infrastructure and to reduce the traffic load in the historic city centre of the health resort Bad Bergzabern. Located in the south-western part of Germany, the project area is situated at the eastern margin of the so-called Palatinate Forest, a low mountain region of mainly triassic sediments with a complex and variable geological history. The German federal government, represented by the office of mobility of Rhineland- Palatinate, awarded the contract to BeMo Tunnelling, a specialized Tunnelling company with a long history of innovation and success in NATM tunnelling. The contract includes the construction of two separate tubes with a length of approximately 1,44 km (0.9 mi)—the road (main) tunnel with a cross section of 101 m2 (1,090 sq ft) and a parallel rescue tunnel with a cross section of ca. 23 m2 (250 sq ft.) Both are connected by six cross passages. Tunnels and cross passages are excavated according to the principles of the New Austrian Tunnelling Method (NATM). Due to BeMo Tunnelling’s technical expertise and capabilities, the project team was able to engineer a speed-up concept that saves money and time for the construction team and client. This paper presents the innovative approach BeMo Tunnelling made to optimize the execution of the tunnelling works and the challenges the project team is facing with regard to a complicated geological situation, countermeasures against an increasing effect of climate change and volatile prices for construction materials.

Jun 13, 2023

By William Gleason

"Sluggish prices for commodities and a glut of oversupply of many commodities did not stop the world’s largest mining equipment makers from showing off their latest and greatest machines and technology starting with the world’s largest equipment trade show, bauma 2016 in Munich, Germany.From April 8-14, an estimated 580,000 visitors from 200 countries visited the show that featured 3,423 exhibitors from 58 countries. While primarily a show for construction equipment, the mining footprint has grown over the years. Among the largest exhibits was that of Liebherr, which brought more than 100 products, had an outdoor exhibition stand, a stand for the components division and a career stand under the motto “Be Part of Something Bigger.” One of the biggest aspects of the exhibit was its mining products where the company staged the first-ever professional table tennis match in the 130 m3 (170 cu yd) dump body of the T 264 mining truck. The top German players Timo Boll and Patrick Franziska with their trainer Jörg Robkopf faced Austria’s singles world champion from 2003, Werner Schlager, and the reigning Team Europe champions Chen Weixing and Stefan Fegerl.“Bauma 2016 was an absolute success for Liebherr. With this year’s appearance we were once again able to show our innovative strength, performance and technological diversity to a very large and international audience from the industry. We conducted interesting discussions with numerous customers and partners from various countries and discussed new projects,” said Stefan Heissler, Member of the board of directors of the Liebherr Group.Likewise, Caterpillar, the world’s largest maker of construction and mining equipment had a large presence at the show with more than 60 products and 12,000 m2 (129,000 sq ft)of exhibit space. Among the iconic yellow mining equipment that was on display was the 6015B hydraulic mining shovel."

Jun 1, 2016

By P. Eger, D. Green

"The Soudan Mine was Minnesota’s first iron mine, operating from 1882 to 1962. The mine was donated to the State of Minnesota in 1963 and became a state park in 1965. The mine discharge contains elevated copper and cobalt concentrations and has been treated with an ion-exchange-resin-based system since 2009. The system includes flow equalization tanks, bag and cartridge filters, a carbon tank and two commercial ion exchange tanks. Although effective, the system’s high cost, inefficient removal of suspended material and substantial maintenance have been ongoing and troublesome issues.In November 2012, we initiated a pilot test using a peat-based sorption media. This media is produced from raw reed-sedge peat through a patented, low-temperature carbonization process that produces a hardened granular sorption material. The granules are uniform, have high hydraulic conductivity and maintain the high metal affinity of natural peat.Mine water was pumped through the peat-based sorption media without any pretreatment. Copper input concentrations typically ranged from 30 to 60 µg/L but increased to a high of 364 µg/L in the summer of 2013. Since startup, more than 60 million L (16 million gal or 32,000 bed volumes) have been treated, with average removal rates of 75 percent for particulate copper and 60 percent for dissolved copper. Backwash is required at about 4,000 bed volumes, but with a combination of air sparging and high-flow backwash, the suspended material is removedfrom the media.One tank of the peat-based sorption media was found to remove copper similarly to the first four components of the existing system. By reducing size and complexity, reductions in operation and maintenance costs are possible. A comparison of the estimated costs indicate that replacing the four initial components with the single media tank has the potential to reduce annual operating costs by more than half from around $163,000 to $70,000."

Jan 1, 2015

By Raphael Victor

The construction and modification of tunnels brings a requirement for precise measurement of convergence and divergence to safeguard the structure, maintain safety and provide the assurance needed to maintain efficient progress. Established methods include manual measurement using tape extensometers and automated methods using photogrammetry and automated total stations. Drawbacks include the need for frequent access, power supply, cabling, and cost. The paper describes how the development of reliable optical displacement sensors (ODS) has changed the landscape. ODS sensors are connected to a long-range wireless mesh communications network via a solar-powered gateway outside the tunnel, with data instantly transmitted to the internet. A sensor and its reflector target can be installed in 20 minutes and is maintenance free for a decade. Tunnel movement is measured to sub-millimeter precision with repeatability of ±0.15 mm. Integration of a triaxial tilt sensor allows slope distance to be converted to horizontal and vertical changes and allows rotational movement to be determined. Applications include new-build and long-term structural health monitoring. Case studies will be given, including the refurbishment of rail tunnels in Spain where the ODS measured movement during track lowering in a situation where no other automated system was considered viable.

Jun 13, 2023

By J. C. Motz

With ore grades continually decreasing and finer mill feed requirements, it becomes increasingly important to have the capability to handle the larger tonnages economically. With the 10 ft. Standard capable of reducing 1,633 metric tons per hour (1,800 short tons per hour) to 80 percent passing 50 MM (2 inches) and the 10 ft. Short Head following to produce a mill feed of all minus 12 MM (1/2 inch) at a rate of 608 metric tons per hour (670 short tons per hour), we feel significant savings will be realized in installation and operating costs. The largest concentration of cost in the secondary and tertiary crushing stations is the building itself that houses the process equipment. An example of the savings to be attained can be seen from an examination of a 40,820 metric ton (45,000 short ton) per day crushing plant. A total of nine 7 ft. Symons Cone crushers is used to generate 12 MM (1/2 inch) ball mill feed. The average center distance between units is 6.1 M (20 feet) and allowing a 6.1 M (20 feet) nominal distance from the centerline to the wails, the building becomes 61 M (200 feet) long. For this production rate, four 10 ft. Symons Cone crushers would be required. With the 10 ft. crushing plant requiring a center distance spacing of 7.6 M (25 feet), the building length totals approximately 38 M (125 feet). Construction costs vary depending on location, but a reduction in building length from 61 M (200 feet) to 38 M (125 feet) will result in estimated savings of between $2,500,000 and S4,000,000. While the 10 ft. Symons Cone has been involved in a number of feasibility studies for some time, the Process Machinery Division of Rexnord commenced detail design work on the 10 ft. Cone crusher in 1972. For comparison purposes, the 10 ft. and 7 ft. capacities are given in Table 1.

Jan 1, 1978

By Horry Parker Jr, Jason Gillespie, Justin Kolster, Stephen O’Connell

Construction of the 5,932-ft Reedy River Basin Sewer Tunnel in Greenville, SC was marked by a critical transition from drill-and-blast mining in mixed-face conditions to TBM excavation with limited rock coverage. In this paper, we discuss the geological, geotechnical, and risk management considerations for transitioning to TBM operations in variably weathered gneissic bedrock. After construction of an unexpected 230-ft starter tunnel due to differing site conditions, the 11-ft diameter TBM was successfully launched in December 2019 without significant ground support issues. This project highlights the effectiveness of extensive rock probing to fully characterize bedrock topography prior to the TBM launch.

Jun 13, 2021

By Francisco A. Fonseca

The Carajás Hills are in Brazil's Eastern Amazon, between the Araguaia and Xingu rivers, and parallels 5° and 7° Latitude South. A location map is given in Fig. 1. It is an area of low mountains (maximum altitude 900 meters), covered by the Amazon rain forest. Annual average temperature is 25°C, ranging from 31°C (maximum) to 19°C (minimum). Annual rainfall averages 2,000mm. Although it rains throughout the whole year, heavy rains occur from December through March. At the beginning of the 20's, Brazilian explorationists made brief geological descriptions of the area. Due to the thick soil, scarce fresh rock outcrops and the tropical forest covering a completely unpopulated area, detailed geological studies were difficult and reconnaissance expeditions were limited to the river margins.

Jan 1, 1982

By F. L. Jackson

When using perlite as an insulation, it is important to determine the requirements for different applications as this influences the processing of the perlite. In cryogenic applications, perlite properties of low density and fine particle size are desirable, while Loose fill insulation applications require similar properties and water repellency. However, in perlite insulating concrete applications, a coarser particle, of higher density, is required to provide improved compression strength. The essential properties of perlite including, particle size, density and surface treatment are discussed in relation to the various insulation applications. Also typical mineral processing and manufacturing techniques are reviewed

Jan 1, 1983

By J. K. Wilmshurst

Absorption, emission and reflection techniques for the study of [molten] inorganic materials at high temperatures have been critically examined. In general, the reflection technique is the most satisfactory for tine study of pure materials, while the absorption, and possibly also the emission techniques, may be useful for studies of certain dilute solutions. In the present investigation infrared emission spectra for sodium nitrate and silver chloride were obtained together with absorption spectra derived from reflectivity data by the method of Robinson and Price for sodium nitrate, silver chloride, lithium and potassium fluoride and their 1:2, 1:1 and 2:1 mixtures and for solutions of zirconium tetrafluoride in lithium-potassium fluoride (1:1) and sodium-potassium fluoride (1:1). It is concluded that vibrational spectroscopy cannot give unambiguous information concerning the existence of complex ions in fused salt, mixtures.

Jan 1, 1963

By Paul H. Johnson

Chemical mining may be defined as the in-place extraction of metal values from ores located within the confines of a mine (that is, broken or fractured ore, stope fill, caved material, or ores in permeable zones) or ores located in dumps, prepared ore heaps, or tailing ponds. The term solution mining has, in general, been used to mean the in-place dissolution of water-soluble mineral salts with leach solutions. Chemical mining is presently in its embryonic stage. Basic research needs to be done to understand the influence of physical and chemical factors in chemical mining, and applied research needs to be done on both a small and a large scale to develop practical techniques of field practice. The areas of research include the following: (1) Leaching chemistry, the influence of physical, chemical, and biological factors in in-place leaching (2) Hydrodynamics of chemical mining systems (3) The development of new, as well as old, leaching agents for use under chemical mining leach conditions (4) The development of new means of contacting fine and coarse materials (with solutions) under static leach conditions (5) The development of new processes for generating and regenerating chemical mining leach solutions (6) The development of metal recovery processes

Jan 1, 1969

This paper presents the results of an experimental study undertaken to demonstrate the feasibility of using silica sand as a grinding media in stirred ball mills for ultra-fine coal grinding. Laboratory batch as well as bench scale continuous tests indicate that the use of silica sand can reduce the energy consumption by 50% and more over its steel media counter-part. Moreover, this approach has been found to eliminate the disadvantages observed with grinding using steel media such as high replacement cost, contamination of coal through media wear, greater degree of coal oxidation due to higher slurry temperature and greater level of noise dissipation. Additionally, coal-sand attrition system reduces the manpower time required which is often spent towards cleaning and storing of steel media in inert atmosphere to avoid rust and corrosion problems.

Jan 1, 1991

By E. Hasanbas

Vibrating screens and crushers are the workhorses of material sizing. Unfortunately their natural frequency is often in the range of typical supporting structures, thereby making installations prone to vibration problems. Much of the available literature regarding the support of vibrating screens is fairly confusing and outdated. This paper presents the results of utilizing accelerometers and finite element software in the analysis and design of supports for vibrating equipment. It contains data from field studies of vibrating screen and crusher installations, design of new and repair of existing supporting structures, and the correlation between field data and finite element time history analyses. Finally, the paper summarizes a method for analyzing and designing structures subjected to vibratory loads and predicting their behavior.

Feb 23, 2014

By Patrick G. Hatcher

Studies of sedimentary humic acids by nuclear magnetic resonance (NMR), stable isotopes, and elemental analysis show they are derived by oxidative degradation of complex plant macromolecules that are insoluble in aqueous or organic solvents. The mechanism by which humic acids originate is fundamental to our understanding of the role of organic matter in ore deposition, because these substances can complex and mobilize a number of metal ions. The organic matter associated with uranium ores of the San Juan Basin, New Mexico and Carlin-type disseminated gold deposits of Nevada has certain organic geochemical characteristics that suggest an origin from humic acids.

Jan 1, 2013

By K. Heatwole, D. Shier, A. Davis, J. Kidder, S. Sunkavalli

"Acid rock drainage (ARD) is produced when sulfides are exposed to oxygen and water. Oxidation reactions typically result in a depression of pH and leaching of solutes and metals. Many oxidation models have been developed based on oxygen diffusion, but in environments with high permeability, other transport processes (i.e., convection and advection) can play an important role. Multiple sulfide mineral phases with differing oxidation rates should also be incorporated. WROC, a finite-difference model, was developed to account for these factors in predicting ARD. The program includes sulfide mineral oxidation using a shrinking core mechanism, heat transfer by conduction, heat of reaction and oxygen transport by diffusion and advection. The model was validated using data from the literature. After validation, the WROC model was used to simulate several different waste rock scenarios, including different forms of sulfide mineralization and the effect of implementing a waste rock cover. The results demonstrate that including specific sulfide mineral phases can have a significant effect on oxidation and that implementation of a cover can also aid in reducing waste rock oxidation.IntroductionAcid rock drainage (ARD) is a notable environmental concern in areas where rock or other material with acid generation potential is disturbed. ARD is defined as drainage that occurs as a result of sulfide oxidation in rock exposed to air and water. ARD is characterized by low pH, elevated metals concentration (especially aluminum, iron and manganese), sulfate and high total dissolved solids. The low-pH water that results from acid generation is capable of solubilizing heavy metals contained within the rock. The principal sulfide mineral in mine wastes is pyrite (FeS2). Pyrite oxidation is complex and can involve chemical and biological reactions. Oxidation of pyrite by atmospheric oxygen produces one mole of Fe2+, two moles of SO4 2- and two moles of H+ for every mole of pyrite oxidized, as described by Eq. (1)."

Jan 1, 2015

The Sage Mill Project w approved by Santa Fe Pacific Gold Corporation's Board of Directors in October 1994. The Sage Mill Project included a pressure oxidation plant designed and constructed to process refractory carbonaceous ore using fine grinding/autoclaving technology developed specifically to treat Twin Creeks ore. The project was constructed in two phases. The first phase was put into operation on May 5, 1997, just hours before the transfer of ownership to Newmont Gold Company occurred. The second phase started in October 1997. This paper reviews schedule, costs, scope changes, and methodology used on the project that spanned almost five years from project definition through commercial operation.

Jan 1, 1999