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By Steve Kral

About 500 mineral-processing professionals from around the world gathered in San Francisco, CA in Oct. 22-27, 1995 for the XIX International Mineral Processing Congress (IMPC). Following the theme “Leading Mineral Processing into the 21st Century Through Advanced Technology,”186 speakers from 28 countries covered research and development activities and innovative processes. Subjects included comminution and simulation control, physical and chemical processing, flotation practices and fundamentals, precious metals processing and mineral waste and the environment.

Jan 1, 1996

By Matthew E. MacGregor, Hugh T. Kelly

I.H. 635 (LBJ Freeway) was constructed as a loop freeway around the city of Dallas in the late 1960s and early 1970s with a design capacity of 160,000 vehicles per day (vpd). Today’s facility is carrying over 270,000 vpd. To help mitigate community concerns with regard to right-of-way issues, noise, safety, and traffic disruption, the Texas Department of Transportation (TxDOT) is planning a number of significant improvements. The West Section improvements include the construction of managed HOV/Toll lanes. Within this 8-mile section, TxDOT is planning two mined tunnels(1.5 and 1.9 miles long) beneath the LBJ Freeway. The mined tunnels will connect to cut-and-cover box sections in both the east and west directions. This paper presents an overview of the project development from the design schematic, through the geotechnical investigations, into the current design stage. The project is being planned for implementation by use of a Comprehensive Development Agreement.

Jan 1, 2005

By Bradford F. Townsend, Colin R. Speers

INTRODUCTION This is the first in a series of papers addressing practical tunnel lining design. The format for this and future papers is to present a particular topic and support the presentation of the guidelines by the practical application of a case history. The primary intent is to provide guidelines for the geotechnical and structural design of tunnels where the tunnel size and/or ground conditions dictates that systematic support of the excavation is required following each increment of excavation. This method of tunneling is commonly referred to as Sequential Excavation and Support(SES) and is also commonly termed the New Austrian Tunneling Method (NATM) The authors developed the design guidelines from experience gained over the past two decades during the design and construction of several major railway, highway and water-transfer tunnel projects in Africa and Asia. During this time it has been possible to compare the performance of the as-constructed structures to the predicted performance as given by the design process. Excavation was typically carried out in widely varying ground conditions (weak-bedded rock, jointed hard rock, and soil-like poorly cemented rock with groundwater). It is therefore intended that the design guidelines could be applied, in general terms at least, to any tunnel excavated in any ground mass condition with any ground material type (hard rock, soft rock, bedded rock, soft ground, and soil) with or without ground water. This first paper is an introductory paper that defines the scope and a brief outline of the design issues that may be presented in detail in later papers. What is design? It may be thought of as any rational/verifiable/justifiable process whereby a concept is transformed into information that can be used to bring the concept to reality. In the case of a civil structure, design may be defined as that process, which is documented and can be audited, that determines information such as the shape (form) of the structure, the dimensions (size) of the structure, the thickness and strength of structural members that comprise the structure, etc. This information can be used to compute the time, money and resources required for

Jan 1, 2005

By William R. Yernberg

Caterpillar introduced 21 new products during Caterpillar Press Days ‘96, held in June at the company’s proving grounds near Tucson, AZ. The event, billed as the largest product introduction ever held by Caterpillar, was attended by press from around the world. Most of the new products were demonstrated at Caterpillar’s Tinaja Hills Training Center in the Sierrita Mountains south of Tucson. Under the scorching Sonora Desert sun, the press was treated to demonstrations of the new equipment. After a display of the equipment’s power and capabilities, the press was given an opportunity to operate the new models and, in some cases, compare them with the old.

Jan 1, 1996

Fluorspar was not mined in the United States during 2004, although a small amount of usable synthetic fluorspar (CaF2) was produced from industrial waste streams. The majority of fluorspar consumed in the United States came from imports or stockpiled material purchased from the National Defense Stockpile (NDS). In addition, consumption is supplemented by use of by-product fluorosilicic acid produced at phosphoric acid plants. In 2004, annual production of fluorosilicic acid was 50kt (55,000 st) or about 88 kt (97,000 st) of 92 percent fluorspar equivalent. In 2004, annual production of fluorosilicic acid was 50kt (55,000 st) or about 88 kt (97,000 st) of 92 percent fluorspar equivalent.

Jan 1, 2005

By R. L. Virta

Six companies mined fire clay in Missouri and Ohio during 2004. Production, based on a preliminary survey of the fire clay industry, was estimated to be 398 kt(438,700 st), valued at $9.81 million. This was slightly less than the production and value figures from 2003. Missouri was the leading producer state. It accounted for more than 70 percent of the U.S. production. Consumption Domestic producers sold or used fire clay primarily for refractory applications. This application accounted for 79 percent of the market. Refractory products made using fire clay include firebrick and block, grogs, high-alumina brick and specialties, refractory mortars and mixes, and saggers.

Jan 1, 2005

By Georgene Renner

At the beginning of the 1990s, Communism fell and signaled the end of the Cold War. The world rejoiced but also watched and waited to see how those countries would restructure themselves. The 1990 SME Annual Meeting was held at the Salt Palace Center in Salt Lake City, UT. The keynote session featured Alistair Frame, chairman of RTZ; Paul Queneau, professor of metallurgy at the University of Utah; and TS Ary, director of the U.S. Bureau of Mines. The SME Board of Directors voted to hire a Manager of Public Information and Education to be the GEM Program coordinator. This person was to collect and disseminate information that could be used by individual members and Local Sections to interface with government personnel and the general public.

Jan 1, 2007

By Harvey Parker

The International Tunnelling and Under-ground Space Association (ITA) is a nonprofit organization that represents all aspects of the tunneling and underground space industry worldwide. The United States has had a prominent role in ITA since its 1974 inception. ITA was formed as a result of a worldwide survey conducted in the early 1970s by the Organization for Economic Cooperation and Development (OECD). Bill Lucke was in charge of tunnels for the U.S. Federal Railroad Administration and was a member of the organizing committee that created ITA. He became a vice president of ITA. Jack Lemley served as President of ITA from 1983 to 1986. Dick Robbins was very active in ITA and served for many years both as a member of the Executive Council and as First Vice President. Harvey Parker has served as President of ITA for the last three years and will serve as Past President for the next three years. Moreover, there are many individuals and companies from the United States that have contributed significantly to the activities and the success of ITA. There have been several active Working Group Animateurs from the U.S. and there have been significant contributions from many individuals as well as companies from the U.S. Several engineers from the U.S. are currently serving ITA in a leadership role. The Underground Construction Association of SME (UCA of SME) is the official organization representing the U.S.. SME Executive. [ ] Director Dave Kanagy and UCA President Tom Peyton were instrumental in the U.S.?s role at ITA during the last few years. Peyton has been the official delegate to ITA. Henry Russell and Christian Ingerslev are both Animateurs of ITA working groups. This article will introduce ITA and its activities. A subsequent article will describe the ITA in more detail and will discuss the significant role the U.S. has played in the development and success of ITA.

Jan 1, 2007

By William R. Yernberg

The combined 80th Annual Minnesota Section of SME Meeting and 68th Annual University of Minnesota Mining Symposium was held April 17 and 18, 2007, in Duluth, MN. About 350 mining industry professionals attended the conference, including engineers, executives, mining managers and suppliers from the United States, Canada, Australia, Finland and Brazil. This year’s theme was “Consolidation – Growth – Technology.” The 80th Annual Minnesota Section of SME meeting included concurrent technical papers sessions, a keynote session that featured two distinguished speakers and a general managers session in which taconite mine operators provided updates on their operations. The Minnesota Section meeting also offered an SME short course titled “Control the Feed, Control the Mill.” More than 50 individuals at-tended the short course.

Jan 1, 2007

By Richard P. Stahura

During the next five years, there will be a trend toward performing belt cleaner maintenance while the conveyor is in operation. Most mines and industrial sites that use belt conveyors have an in-house safety rule that the belt must be stopped before maintenance work can be performed on any belt-cleaning device. This is a good rule. Most cleaning devices are positioned against the belt with hardware that requires the service technician to reach or climb into the chute to change the cleaning blades. But this simple rule becomes more complicated as production demands require higher conveyor availability and provide fewer conveyor outages. In many cases, today’s conveyors are expected to be available 98% to100% of the time.

Jan 1, 1996

By Gordon T. Clark, James R. Struthers, Celal Kirandag

INTRODUCTION Project Background The Washington State Department of Transportation (WSDOT) hired the Seattle office of Parsons Brinckerhoff to lead a team of consultants to produce an Environ-mental Impact Study and perform conceptual and preliminary engineering. The pur-pose of the Alaskan Way Viaduct and Seawall Replacement project is to replace the existing earthquake damaged and aging viaduct and sea wall, adjacent the downtown waterfront of Elliott Bay, with structures that have improved earthquake resistance and that maintain or improve mobility and accessibility for people and goods along the existing corridor. With an estimated replacement cost over $4 Billion and construction duration exceeding 8 years, it is one of the largest transportation design projects on the West Coast of the United States today. Seattle, Washington is a city of over 2 mil-lion people in the Northwest corner of the United States. Ever since the Klondike Gold Rush in 1897, Seattle has been considered a departure point to Alaska. Because of this, the street along the waterfront was named the Alaskan Way in 1930. Alaskan Way Viaduct and Seawall The Alaskan Way Viaduct (AWV) carries State Route 99 along the shoreline of Elliott Bay through downtown Seattle and is a vital part of Seattle’s highway system. The viaduct carries approximately 110,000 vehicles per day or 25% of all north-south traffic through Seattle (Figure 1). It is 3.4 km (2.1 mile) long with 3 lanes in each direction and was constructed of cast-in-place reinforced concrete between 1952 and 1956. The wear and tear of daily traffic, salty marine air, and several earthquakes have taken their toll on the facility. Studies in the mid-1990s provided early evidence that the viaduct was nearing the end of its useful life. The viaduct’s increasing age and vulnerability was apparent by crumbling and cracking concrete, exposed rebar, weakening column connections and deteriorating railings. In early 2001, a team of structural design and seismic experts began work to determine whether it was feasible and cost-effective to strengthen the viaduct by retro-fitting it. In the midst of this investigation, a 6.8 magnitude earthquake shook the Puget Sound region (the Nisqually Earthquake, located 56 km (35 miles) from Seattle and deep below the surface) caused moderate damage to the reinforced concrete structure. WSDOT closed the viaduct for inspection and repairs intermittently for several days over a period of several months.

Jan 1, 2007

By Vojtech Gall

Pre-support measures for urban tunneling have seen a substantial development in the recent past. Ground improvement techniques, pipe-arch and spiling methods now allow for non-disruptive tunneling at very shallow depths under sensitive structures, rail tracks and roadways. The paper presents experience gained on national and international projects built over the past decade that represent case histories and therefore may be used as guidance for the development of similar solutions for future tunneling projects at shallow depths. Reference projects include tunnels for the Washington, DC Metro, London Underground, Dulles Inter-national Airport, Busway tunnels in Boston and the Ft. Canning Tunnel in Singapore.

Jan 1, 2008

Editor’s note: As usual, the June issue features an industrial minerals review. And some thanks are in order. Thank you to the industrial minerals annual-review editor, to the technical committees chair and vice chairs and to the authors of the individual commodity profiles. Jim Norman of GeoTrans Inc. is the industrial minerals annual-review editor. William Langer, U.S. Geological Survey, is the chair of the SME industrial minerals technical committees and the vice chair of the technical committee for construction materials. Other technical committee vice chairs include: •Lucy McCartan, U.S. Geological Survey, agricultural minerals. •Steve Herron, Oglebay Norton Performance Minerals, ceramics and refractory materials. •Srinivas Veeramasuneni, U.S. Gypsum, chemical raw materials. •Ismail Yildirim, Imerys, fillers and pigments. •Charles Landis, BPM Minerals, sorbents, filters and process aids. •Ray Harris, Wyoming Geological Survey, specialty minerals. Their help makes possible this June industrial minerals issue. On behalf of the readers, the editors thank them

Jan 1, 2004

By G. E. S. Valadao, J. D. Miller, C. L. Lin

Filtration is an important solid liquid separation technology employed widely in the mineral processing industries. The effectiveness of the filtration operation can be influenced by numerous variables, related to the particulate phase, the slurry rheology and the equipment. The classical approach for analysis is based on Darcy's law. Knowledge of the cake poremicro structure and its correlation to macroscopic cake properties is required to model the filtration operation from a fundamental point of view. Since cake formation seems to occur randomly, a 3D Monte Carlo method was used to simulate cake formation. The configuration for simulation was a space with width of 500 m, length of 500 m and height of 4000 m. Size distributions of five different industrial products whose particle size distributions follow the Rosin Rammler distribution function were used. The particle shape was assumed to be spherical. The simulated cake structures were described in terms of volume porosity (volume of pore space per unit volume of cake) and surface porosity (area of pore space per unit area of a cross section). The results indicate: 1) it is possible to simulate 3D packing, which mimics cake structure, using the Monte Carlo method,2) segregation phenomena occurs during simulated cake formation, 3) the values of calculated porosity for simulated samples B, C, D, and E were lower than those determined for corresponding industrial products Br, Cr, Dr, and Er, and 4)some structures of simulated samples seem to correlate with laboratory leaf test data obtained for different products from plant operations.

Jan 1, 1999

By Paul C. Schmall

The link between artificial ground freezing and the mining industry stretches back more than 140 years, and across an ocean. Patented by the German scientist F.H. Poetsch in 1863, the technique is reported to have first been used circa 1862 in the coal mining valleys of South Wales. In the United States, the first ground freezing application, to a depth of 30 m (100 ft), occurred in 1888 for the Chapin Mine Co. in Iron Mountain, MO. In England in 1901, the Poetsch method was used for the first time to successfully sink two shafts through 24 to 27 m (80 to 90 ft) of wet sand and boulder clay at the Washington Glebe Colliery, near Sunderland. British mining engineer T.H. Cockin, in his 1905 Class-Book of Practical Coal-Mining, noted that, ?This method of sinking through thick beds of very wet quicksand has met with great success; it is one of the recognized methods of sinking on the Continent.? Mine shaft freezing soon became relatively common in Europe where the project could bear the cost of a major refrigeration plant construction. However, it was not until 1952 that the second North American ground freezing project was completed to facilitate the sinking of a 4.5-m- (15-ft-) diameter, 233-m- (765-ft-) deep shaft at a Potash Company of America (PCA) mine in Carlsbad, NM. Nowadays, ground freezing is used worldwide for both mining and civil applications. In small mine shafts of 3 to 6 m (10 to 20 ft) in diameter, excavations have been carried out to depths of more than 820 m (2,700 ft) within the protection of unbraced or unlined frozen walls. In fact, for deep mines, no better method has yet been established for sinking production shafts through deep, water-bearing ground. Major deposits of coal, potash and salt would still be inaccessible if not for artificial ground freezing. There are several advantages of ground freezing unique to the construction of shafts. Proper instrumentation can provide complete assurance of the integrity of the freeze to full depth prior to excavation. The frozen wall allows construction to be scheduled without evaluating the in-shaft time necessary to probe ahead, place additional sup-ports or deal with ground water. The freeze can be implemented perfectly through the soil/rock interface, which is often the most difficult geology in which to create a ground water cutoff by other methods. At increasing depths, any discontinuity

Jan 1, 2007

The Rasmussen Ridge phosphate mine is owned by Agrium CPO and operated by a unit of Washington Group International. The mine, located in southeastern Idaho, received the Idaho Inter-Agency Reclamation Award from the Idaho Department of Lands. The phosphate mine, located northeast of Soda Springs, was honored for “Excellence in Ongoing Operations, Soft Rock Mines over 75Acres.” Charles Ross is Agrium CPO’s plant manager. He said, “We are honored to receive this award. This recognizes the commitment and dedication of our employees toward the protection of the environment. I am really proud of the people that work at the mine.”

Jan 1, 2005

By Timothy D. Arnold

Barrick Gold’s Bullfrog underground mine, near Beatty, NV, was established as an after-thought to the main open pit. As open pit ore dwindles, the underground mining became increasingly more important as an ore source, and to the overall economics of the project. This situation is similar to many other mines. Today, there is a move towards underground mining in the United States. There are inherent problems in starting and operating underground mines in the shadow of any open-pit operation. Several attempts were made at the Bullfrog Mine for productive increases. Some were successful, while others were not.

Jan 1, 1996

By Yoshiaki Numata

It is a matter of importance to use the lower alkyl monoethers of propylene glycol (polyPGME) as a frother in sulfide mineral flotation, for their compounds are highly soluble in water and are surface active frothers to some extent. The purpose of this study is to clarify fundamental roles of frothers in sulfide mineral flotation by investigating the effects of polyPGME on the floatability of galena with xanthate and adsorption property those ethers at the liquid/air interface. Fundamental investigation on the flotation of sulfide minerals using o,o-dialkyl dithiophosphates has been carried out through galena floatability tests in the following two cases:(l)single use of dithiophosphate for sulfide mineral collection and (2) joint use of dithiophosphates for its collection.

Jan 1, 1991

By Steve Kral

The mining industry in Colorado faces the same problems the industry faces throughout the United States and the world — record low commodity prices and increasing regulatory and environmental restrictions that seemed designed to curtail mining activities. Despite those obstacles, the mining industry in Colorado still contributes about $8 billion annually to the state’s economy in the form of base and precious metals, industrial minerals, coal and associated service businesses and jobs. So the 300 attendees at the102nd National Western Mining Conference felt reason-ably positive about the industry in their state. The meeting is the Colorado Mining Association’s annual conference and was held at the Broadmoor Hotel in Colorado Springs in November. The theme was “Mining in the New Millennium — Achievement + Innovation = Survival.” Experts from Colorado’s mining industry and abroad discussed the challenges faced by the mining industry as it enters the new millennium. They offered insights into how the industry will operate during the early years of the 21st century and how it will survive low prices and increased regulatory restrictions.

Jan 1, 2000

By T. Arthur Palm, Stephen L. Bessinger

San Juan Coal Co. (SJCC) operates an underground coal mine near Farmington, NM. Continuous miners and a longwall produce 6.3 to 7.2 Mt/a (7 million to 8 million stpy). SJCC is owned and operated by BHP Billiton. The coal seam at SJCC has been shown to have a propensity for spontaneous combustion. As such, during the feasibility study for this project, it was elected to use a bleederless ventilation system on the longwall. Due to the combination of spontaneous combustion, methane liberation and, to a lesser extent, hydrogen sulfide, a typical wraparound ventilation system would not be appropriate. Three-entry gate roads are developed, and the longwall gob is sealed as mining progresses. SJCC uses a nitrogen injection system to continuously inertize the gob.

Jan 1, 2007