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By R. L. Virta

Common clay is a natural, fine-grained material composed of hydrous aluminum silicates. Shale is a laminated sedimentary rock that is formed by the consolidation of clay, mud or silt. Production About 150 companies produced common clay and shale in 41 states. In states not reporting production, common clay and shale probably was mined and sold for construction applications by companies not participating in the U.S. Geological Survey (USGS) canvass of producers. Domestic production in 2005 was estimated to be 24.8 Mt (27.3 million st) valued at $176 million. This was based on a preliminary survey of the common clay and shale industry. The leading producer states, in decreasing order by tonnage, were North Carolina, Texas, Alabama, Georgia and Ohio.

Jan 1, 2006

By William R. Yernberg

The Society of Economic Geologists (SEG) held its biennial conference May 14 through 16, 2006, in Keystone, CO. SEG is an international organization with about 3,500 individual members with interests in economic geology. The 2006 SEG conference theme was “Wealth creation in the minerals industry — integrating science, business and education.” The conference exceeded expectations with 705 participants, including 102 students, from 44 countries. The conference featured 30 oral presentations, 24 professional posters and more than 70 student posters. The conference also included a trade show with 50 vendors, numerous field trips, workshops and social activities.

Jan 1, 2006

By T. Tafi

The Ute-Ulay project area is located approximately five miles west of Lake City, in Hinsdale County, Colorado. The Ute-Ulay Mine site is approximately one mile east of the project area. The elevation of the site is 9,200 feet and is adjacent to Henson Creek (Figure 1) [ ] The Ute-Ulay Mining complex is an inactive gold, silver, and zinc mining/milling operation, that operated from the 1880?s until the 1970?s, and sporadically into the late 1990?s. The mining complex comprises several levels of underground mines, a flotation mill, and an abandoned town site. Due to the narrow, steep sided canyon, milled tailings were pumped upstream one mile in a sluice box to a wider section of the canyon, and deposited into five tailings impoundments and one berm located between the impoundments. An estimated 9,000 cubic yards (yd3) of fine grained tailings were located in the impoundments adjacent to the creek. The Ute-Ulay project area consisted of the mill tailings impoundments located upstream from the historic mine.

Jan 1, 2011

By Phil Pennington, D. Jack Adams, G. Ward Wilson, Virginia T. McLemore, Luiza Aline F Gutierrez, Rodney Shields, Steven Lockwood, Samuel Tachie-Menson

Microorganisms are directly or indirectly involved in many chemical alterations and in the decomposition of minerals required for their growth. Microbial dissolution of sulfide minerals under acidic conditions can produce over 1,000 times more Acid Rock Drainage (ARD) than chemical action alone. Microbial actions can cause precipitation of minerals, adsorption or release of metals, and formation/destruction of organic-metallic complexes. Soluble minerals can serve as oxidizing substrates, electron donors/acceptors in redox reactions, and can be directly involved in cell metabolism. Microorganisms and microbial oxidation-reduction reactions and their contribution to mineral mobilization and stabilization will be discussed.

Jan 1, 2005

By John Mitchell, Mark K. Jorgensen

Newmont Mining’s Ahafo Mine is located in Ghana approximately 300 km (190 miles) northwest of the capital city of Accra in the Brong-Ahafo region. The nearest city is Sunyani, located 45 km (28 miles) to the north. The Ahafo Mine will process ore from seven major pits that extend along a 40-km (25-mile) strike. Four pits are in the south and three pits are in the north. The resource is currently stated at 373 t (12 million oz). But it still has the potential for growth both from new discoveries and the development of underground operations.

Jan 1, 2007

By R. Owen, T. Canty, C. Marks

The industrial vision system provides on-line 2D particle size analysis for aggregate slurries in both the overflow and underflow of hydrocyclones. This paper covers required vision system features allowing CCD cameras to function in the harsh environment of a mine milling area. The study conducted demonstrates the system’s capacity to obtain particle size distributions for controlling hydrocyclonic separators. The particle size distribution is obtained within seconds and immediately updated to allow for process adjustments. Results are then provided as a graphical computer generated display or output as a 4-20mA current loop for process control. The primary use of the vision system is in classifying particles in cyclone overflows which are often a few microns in size. Typical size information for actual mine slurry samples are presented and possible control schemes discussed.

Jan 1, 2002

By Laszlo Toth

A feeder is used to control the gravity flow of bulk solids from storage areas, like a bin or a stockpile. For this type of application, it is important to select a proper drive that can fulfill all of the demands put on it. High starting torque capacity, variable speed and the ability to handle frequent starts and stops are some of the demands that the drive must be able to meet. The following is a comparison of the most common type of drives used today for feeder applications. When a feeder is started, the breakaway torque may reach as high as200% of the running torque. The accelerating torque usually is set to protect the carrying element of the feeder, like the belt for the belt feeder and the carrying chain of the apron feeder (Fig. 1).

Jan 1, 2003

By S. E. Phillipson

The Late Miocene San Cristobal Ag-Zn-Pb deposit represents syngenetic and epigenetic mineralization with low- and high-sulfidation characteristics. Geology is characterized by barren dacitic ring fracture domes, mineralized resurgent rhyodacite domes, strongly altered and mineralized tuffaceous lacustrine sedimentary rocks, and an extensive crystal-lithic tuff debris apron. The ore body is hosted by intra-cauldron sedimentary rocks and breccias. Fluid inclusions suggest that silver, lead, and zinc were transported as chloride complexes and precipitated by cooling in veins from <5 wt. % NaCl eq. fluids at 170°-215° C. Silver associated with resurgent rhyodacite was transported as a chloride complex and precipitated by increased H2S activity or increased fluid pH.

Jan 1, 2001

By William R. Yernberg

The 2002 Arizona Conference was held Dec. 8 and 9, 2002, at the Doubletree Hotel at Reid Park in Tucson. The annual conference is organized by the Arizona Conference Board of Directors, which represents SME sections in Arizona and adjacent areas. The conference provides an opportunity for individuals and corporations associated with mining in the region to get together once each year to discuss the status of the industry. The meeting featured a keynote address, a distinguished lecture and about 30 technical papers. As was the case at the 2001 meeting, the economy, the price of copper and foreign competition continue to be the hot topics of discussion among the attendees. The domestic copper industry still faces challenges due to low copper prices dictated by the world market and because of a weakened domestic economy. There continues to be concern about the Arizona region’s copper industry in light of the mergers, downsizing and shutdowns that have occurred during the past several years.

Jan 1, 2003

By J. Barrett

State-of-the-art wireless communication and location-tracking technologies will dramatically change the face of mine worker safety. The MineTracer System developed by a Liberty Lake Washington company is a broad capability wireless sensor network based on a new breed of technologies known as wireless mesh systems. In this paper, R&D Manager Jim Barrett summarizes the balance of engineering tradeoffs that result in a system that (1) performs well, (2) is survivable against many types of mine accidents, (3) operates for many hours post-accident on battery power, (4) meets stringent MSHA requirements for intrinsic safety, and (5) is economically affordable for the mines.

Jan 1, 2009

By A. Mahmoudkhani

Primary cementing is the process of placing cement in the annulus between the casing and the formations exposed to the wellbore. Portland cement was first used in 1903 in the Lopoc Field in California for well cementing. Since then, the major objective of primary cementing has always been to provide zonal isolation in oil, gas and water wells, i.e. to exclude fluid(s) in one zone from another zone in the well. To achieve this objective a hydraulic seal must be created between the casing and cement and between the cement and the formations, while at the same time preventing fluid channels in the cement sheath. This requirement makes primary cementing the most important operation performed on a well. Without complete isolation in the wellbore, the well may never reach its full producing potential. The industry knowledge on cements relies heavily on empirical data, but the chemistry, physics and structure of cement are not fully understood yet. The strength of concrete can be increased essentially by reducing its porosity through optimizing the size distribution of its components and filling the residual porosity of the hydrated cement phase with inorganic fillers. This approach has successfully utilized in different ways and several technologies for placing high performance oil and gas well cements have been developed over the last few decades. There are reasons to believe that the next source of improvement will lie in the fine-tuning of the hydrates themselves and of the different parameters that drive short (ionic?covalent bonding) and long (ionic correlation) interactions.

Jan 1, 2012

By R. Schulz, K. King

Concentrating Line 6 just went down again. The control room operator checks the graphic display. Only one piece of equipment shows an alarm. Clicking on the ball mill icon, he discovers the culprit was the low flow lube switch. The flow looks okay now, but it is the third time this week the switch has stopped the line. Maintenance is called, the switch replaced and the line is up running again. Sending the right person to the right spot immediately can save hundreds of hours of downtime every year. This paper discusses the principles behind implementing smart First-Out Fault Detection to dramatically reduce equipment downtime in new, or existing control system architectures. Methodologies are presented to maximize the system benefits, while minimizing development costs. Case histories are presented for a number of successful implementations in mineral processing plants.

Jan 1, 2001

By H. H. Murray

Recently developed clay deposits that will impact regional and world markets are described. These deposits, their location, geology, and physical properties are delineated. Kaolins from the State of Para in Brazil and from Ukraine; bentonites from Argentina and India; and palygorskite and sepiolite from China are world class deposits that when processed using modem technology will produce excellent products. Other deposits that may affect regional markets are kaolins from China, Australia and Indonesia; bentonites from Georgia (formerly USSR) and China; and palygorskite from India and Ukraine. New ball clay deposits that will affect regional markets are in China and Indonesia.

Jan 1, 1999

By J. Bleeck, G. Mahrt

INTRODUCTION Many excellent papers have been written and presented regarding agricultural lime and the subject has been covered extensively in books concerning soil science, fertilizing, limestone, etc. We felt challenged to construct a paper that wouldn’t merely be a repetition of past presentations. Therefore, we chose to begin with factors having the most impact on plant growth realizing that the audience is likely to be relatively unfamiliar with this subject. So, we decided to dig deep into the roots of soil and plant growth science in order to better understand the significant role of limestone in this important area. The soil with the higher plants growing upon it forms an open and dynamic ecosystem in which there is flux of energy and material (heat, light, water, nutrients, mineral and organic matter, organisms). Plants root in the soil and then take up oxygen for root respiration, yielding energy for nutrient uptake, water for turgescence and transpiration and use in photosynthesis and the mineral nutrients needed for the synthesis of organic matter. Above the ground the plant takes in light energy and heat using them in photosynthesis to assimilate atmospheric CO2. Photosynthesis is the basic life process of creation. However, we will look at the root room where soil, water, air, and heat economy and the supply of nutrients determine soil fertility and the important role lime plays here. Location is the primary point to be considered when discussing agriculture (climate and soil); secondly, the dynamic and mobility of the minerals (plant nutrients) in the soil; and thirdly the conversion of organic substances into humus. And then there is a great deal of water involved in the growing process. In order to produce 1 kg of dry plant substance, 300 to 800 kg of water must be pumped through the plant and is then lost by transpiration. Cereals, vegetables, and sugar beets consume between 400 to 500 kg of water during the growing process and long-growing crops, such as alfalfa and clover, can consume 600 to 800 kg of water per kg of finished product. Without water, a plant cannot grow. (Reference 1)

Jan 1, 2006

By Alex Naudts

Pre-excavation grouting is a predictable and reliable technique performed to prevent or minimize settlement in advance of, or during the tunneling operation. It safeguards the infrastructure above the tunnel alignment. Cement based suspension grouts and sodium silicate based grouts are frequently injected to consolidate and strengthen the formation and create a reinforced canopy above the tunnel trajectory. Grouting is typically performed through permeation and permeation in conjunction with hydrofracturing. Multiple injection passes through steel sleeve pipes are ideal, since they create an effective forespiling system to facilitate tunneling without causing unacceptable settlement, even with minimal overburden thickness. Ten pre-excavation grouting projects performed in the North America are discussed in this paper.

Jan 1, 2008

By Gerald G. Griswold, Allan G. Provost

INTRODUCTION The Norad Expansion Project was located 10 miles southwest of Colorado Springs, Colorado, within Cheyenne Mountain. The expansion areas to be excavated would be adjacent to the existing underground Norad complex, which would remain in operation during the work on the expansion. The original complex had been constructed approximately eight years earlier and had been in full operation for approximately five years. Phase I, Excavation was awarded the Tiro Construction Corporation, a subsidiary of Harrison Western Corporation, Denver, Colorado, in the fall of 1970. Notice to Proceed was given to Tiro on 28 December 1970. The project owner was the U. S. Air Force, design was performed by the U. S. Corps of Engineers, Omaha District, who would also serve as the construction agency. [ ]

Jan 1, 1979

By K. A. Larsen, J. L. Ariail, C. M. LaRosa

This article discusses the evolution of U.S. laws and policies towards environmental remediation at mine lands over the last 20years, the opportunities that these changes present for reuse, and the remaining challenges associated with community capacity for effective reuse planning and implementation. Emerging initiatives by the U.S. Environmental Protection Agency and Department of Interior for addressing these challenges are discussed.

Jan 1, 2004

By Yoshinori Iwasaki, Shosei Serata, Yutaka Mochida

A new comprehensive insitu instrumentation technique named this RCC Method has been developed for rapid assessment and improvement of the structural stability of underground openings. When applied to tunnel construction, the degree of present and prospective safety of underground openings can be determined in quantitative terms within 10 to 20 minutes of microcreep observation. When applied to mining, roofs and floors can be stabilized by controlling the stress conditions. This stress control method has eliminated the need for intensive roof bolting and extensive floor renewal in all cases where it was applied. Use of this technique is illustrated by field examples from the Seikan Undersea Tunnel of Japan and deep potash mining in Canada. NEW INSTRUMENTATION TECHNIQUE: THE RCC METHOD Failure problems in underground excavation usually arise in weak non-elastic grounds where conventional rock mechanics theories of elasticity are not only useless but also misleading. Presently, discontinuity planes in the ground are being considered a factor in assessing these failure problems, and while this development is interesting academically, it is not of much use in actual excavation work, where it is nearly impossible to identify and quantize all existing planes of discontinuity. Even if such an extraordinary task could be accomplished at an underground excavation site, effective use of the data would be difficult and impractical for rapid excavation work, with the possible exception of rare cases of ideally elastic ground.

Jan 1, 1976

China’s vibrant economic growth is built on coal, the source of two thirds of the country’s electricity. Over 95 percent of China’s coal is mined underground with the average mining depth at 410 m and in-creasing at 10 m per year; today, the deepest Chinese coal mines have exceeded 1,000 m. With increasing mining depths, there are greater challenges including increased methane emissions and spontaneous combustion. According to the government, nearly half of China’s coal mines are classified as gassy (with specific gas content at least 10 m3/mt). Coalbed methane (CBM) is a clean energy source. However, only a small percentage of the methane is captured, and the rest is vented directly to the atmosphere. This paper describes China’s CBM resource, its production and utilization.

Jan 1, 2006

By Shaoxian Song, Ling Xia, Hongqiang Li, Yubiao Li, Yunliang Zhao, Shaobing Xie

Since human daily demands for fresh water have been increased significantly, the supply of fresh water for the mining industry, especially froth flotation, should be considerably reduced. In addition, stricter environmental standards have been implemented in many countries to reduce the risks due to the disposal of wastewater, many flotation operators have to seek more efficient ways to utilize the limited fresh water sources. Recycling water with high concentrations of impurities is a normal strategy for most of the mineral processing plants; however, water quality should be carefully considered to guarantee a smooth flotation process. Recently, the application of seawater in flotation has attracted much attention due to its availability and abundance rather than fresh water. However, the influencing mechanisms due to the application of seawater in flotation have not been fully understood especially the reactions between mineral particles and bubbles in the presence of high concentrations of cations and anions. This would impede the application of alternatives to fresh water in the flotation. Therefore, this paper reviews the current water sources and the technologies for water recycling in the flotation process. Specifically, the life cycle of water in flotation was proposed. In addition, the strategies including high pulp density flotation as well as the most promising alternatives to fresh water have been discussed in details, with the related mechanisms being demonstrated.