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By S. Ripke

Between 2002 and 2004, the performance of a six million ton per year iron ore beneficiation plant dropped significantly. In a classic case of “who done it,” was it the mine, the concentrator, an ore change, or something else? While average annual final product grade decreased 8% (indicated by an increase in silicate gangue from 2.76% to 2.99%), the weight recovery also decreased by 8% (from 37.92% to 34.79%). This represents a loss of 832,000 tons of iron ore worth about $16 million for the two year period! The concentrator had been optimized to produce a high grade wet concentrate as feed to the dry side of the plant. But, did optimizing an individual unit operation’s grade give the best overall plant performance? In this paper, the investigation and solution to this mystery will be revealed.

Jan 1, 2007

Coal bursts are one of the least understood yet the most critical hazards in underground coal mines. The ground motions induced by seismic events can trigger unstable failure of coal and rock mass and degrade the surroundings of an excavation. Therefore, the characteristics of ground motions should be fully investigated for an improved burst risk management. This paper analyzes ground motion features of a longwall panel from a typical underground burst-prone coal mine in China. The results showed that most of the ground motions on roadways were hardly initiate coal bursts due to insignificant energy input to the damage. The intensity of ground motions in near-field zone were nearly 20 times higher than those in far-field zone. The strongest vibration on roadway was induced by a coal burst with energy of 28,600 kJ, which can cause ground motion of 0.77 m/s and equivalent dynamic stress of 14.69 MPa. The findings of this paper can improve the assessment of seismic risks and its management.

Jan 7, 2020

By Manuel Arnáiz, Pedro R. Sola, Rogelio Baudot, Manuel Herrera, Carlos S. Oteo

The aim of this paper is to describe and analyze the ground treatment performed between January and May 2002 in order to increase safety during excavation and reduce instability problems along 180 m of tunnel, during the construction works associated with line 10 extension to the Madrid Metro. The tunnel was excavated using the traditional Madrid Method and in the section considered in this paper layers of sand were detected around the tunnel crown area with a significant presence of water, the in?ow of which needed to be controlled with a minimum impact on the surrounding environment.

Jan 1, 2003

By Carlos Henrique Turolla Maia, Ulrich Maidl, Marc Comulada, Julio Claudio Di Dio Pierri

"Pure sands are typically the domain of slurry shields due to their high permeability and their granular characteristics. However, the Earth Pressure Balanced (EPB) shield machine technology has advanced in recent years with improved conditioning agents and shield machines that are equipped with slurry injection facilities and alternative mucking methods. These new so-called hybrid EPB machines have steadily increased the range of application of the EPB technology. The contribution discusses the capacities and operational features of hybrid EPB vs. slurry shield technology in pure sands. At the example of the Metro Line 4 in Rio de Janeiro (Brazil), the contribution shows that hybrid EPB tunneling in pure sands is possible and it is compared with a state-of-the-art slurry shield project as the KASIG project in Karlsruhe (Germany). Furthermore, the control of the support pressure by means of foam conditioning and slurry injection in conjunction with a close, real-time monitoring of machine parameters is discussed. INTRODUCTION Slurry shield and EPB technologies have both undergone significant developments in recent years, leading to the use of parts of one technology in the other and even to completely hybrid systems. Also the ranges of application (see recommendations by DAUB (DAUB 2010)) of both technologies have been shifted far beyond their original limits and are largely overlapping by now. Nevertheless, the basic principles of face support remain unchanged. Exploiting the possibilities of process data analysis (Maidl 2014), the interactions between the ground and the shield machine are a matter of research and have been intensely investigated. PRINCIPLES AND CALCULATION OF FACE SUPPORT PRESSURE Figure 1 shows the principles of two approaches for the determination of required support pressures: kinematic methods and numerical methods. Kinematic methods that are employed for the assessment of face stability only consider the situation in front of the TBM. The required face support force is determined by means of an assumed failure wedge that would form in ultimate limit state. Based on the ground properties, the vertical surcharge and the self-weight is transformed into a horizontal force along a virtual sliding surface. This horizontal force is to be balanced by the face support. The calculation results are amended by respective partial safety factors for water and earth pressure and the method-specific support pressure fluctuations are added."

Jan 1, 2016

By R. L. Wolfrom, R. Hogg, S. Chander

A gravimetric method for measuring rates of capillary rise in powders was explored. Methods to improve reproducibility and consistency of the results were investigated. In particular, the effects of particle size and packing uniformity were addressed. Studies of the wetting behavior of both spherical glass beads and irregularly shaped synthetic graphite particles by various organic liquids were carried out. Standardized procedures for bed preparation are described. The applicability of the Washburn equation for surface energy evaluation in such systems is discussed.

Jan 1, 2002

By D. Hopkins, D. Türler, R. D. Giauque, W. B. Davis, M. Karaca

In a highly collaborative research and development project with mining and university partners, sensors and data-analysis tools are being developed for rock-mass characterization and real-time measurement of mineral content. Determining mineralogy prior to mucking in an open-pit mine is important for routing the material to the appropriate processing stream. A possible alternative to lab assay of dust and cuttings obtained from drill holes is continuous on-line sampling and real-time x-ray fluorescence (XRF) spectroscopy. Results presented demonstrate that statistical analyses combined with XRF data can be employed to identify minerals and, possibly, different rock types. The objective is to create a detailed three-dimensional mineralogical map in real time that would improve downstream process efficiency.

Jan 1, 2002

By D. He

In China, the total reserves of vanadium, reported as V2O5, in stone coal is 118 Mt (130 million st). Recovering vanadium from such a large resource is very important to China?s vanadium industry. The technology now being used to recover vanadium from stone coal has the following two problems in the leaching process: a low recovery of vanadium and high acid consumption. To resolve these problems, a new leaching technology is proposed. The effects of factors such as H2SO4 concentration, liquid-solid ratio, temperature and time, and the types and additions of additives were studied. By adding 1.5% (by weight) CaF2 and leaching the roasted residue of stone coal with 5.4% (by weight) sulfuric acid at 90°C for 12 hours at a liquid-solid ratio of 2 mL/g, the leaching degree of vanadium reached 83.10%. This proposed leaching technology gives a feasible alternative for the processing of roasting residue of stone coal and can be applied in the comprehensive utilization of stone coal ores in China.

Jan 1, 2008

By S. D. Bearden

Color enhances expression and communication in all physical objects experienced in life. Pigments provide color and in some applications have a specific additional function. Natural iron oxides are widely distributed throughout the world but only a few deposits are sufficiently pure and possess acceptable color and brightness properties to merit their processing into pigment form. Ochre, the common name for goethite ore, is the best and most under used material in the buff colored pigment market. The geological occurrence of ochre in the basal Shady Formation of the Cartersville Mining District (Georgia) is described. Exploration, processing, and product applications of New Riverside Ochre Company, Inc. are discussed. An overview of the worldwide pigment market is presented with emphasis placed upon the North American activity in iron oxide production and application. The purpose of this paper is to increase the awareness of ochre and its potential market in the colored iron oxide pigment industry, encourage research on the origin of ochre deposits, and stimulate interest in new applications of this unique substance.

Feb 27, 2013

By G. Mei

"This study explores froth flotation and selective flocculation methods to recycle waste phosphors containing several rare earth elements, namely, yttrium (Y), europium (Eu), cerium (Ce) and terbium (Tb). The effects of the presence or absence of collector and of flocculant and their dosages, as well as the pH, were investigated. Reverse flotation resulted in concentrates with grade of 27.03 percent and recovery rate of 71.36 percent, while flocculation resulted in concentrates with grade of 31.43 percent and recovery rate of 91.28 percent. The flotation and flocculation behaviors were further analyzed by X-ray diffraction analysis, zeta potential measurements, particle size distribution and other methods. The successful separation of rare earth minerals by flotation was attributed to the selective adsorption of the collector onto quartz, making it particularly recoverable by reverse flotation so as to be separated from the valuable materials. The analysis of the particle aggregation process indicated that its better flocculation performance was due to the selective adsorption of flocculants onto the unwanted materials, enlarging the flocculant sizes by forming aggregations and facilitating the separation of rare earth minerals from waste materials based on different settling rates. IntroductionBecause waste phosphors pose the problems of heavy environmental burden and high risk to human health (Hu and Cheng, 2012) as a result of containing heavy metals such as mercury and manganese (He et al., 2006; Lucas and Emery, 2006), they have received added attention as urban mining resources for extracting rare earth elements (REEs) like yttrium (Y), europium (Eu), cerium (Ce) and terbium (Tb).At present, chemical processes such as acid leaching, alkali fusion, roasting and extraction are the primary methods for recovering REEs from waste phosphors (De Michelis et al., 2011; Li et al., 2012; Li, 2010). With these strategies, phosphors can be effectively decomposed and their REEs extracted. After the removal of impurities, the REEs can be efficiently precipitated by adding an H2C2O4 solution (Porob et al., 2012). Although relatively high recovery rates are achieved, those processes entail high energy consumption and can cause severe environmental pollution."

Jan 1, 2017

By Ray Brainard, Adriana Ventimiglia, Amanda Kerr

Preliminary design is underway for a new Southern Nevada Water Authority (SNWA) project that will ensure one of America’s most reliable water systems by providing continued, reliable water service to existing and future customers. The Horizon Lateral is a $1.6 billion water transmission pipeline that includes 7–10 miles of 108-inch finished diameter rock and soft-ground tunnels. The tunnels will traverse volcanic rock in or around the McCullough Mountain Range and the surrounding alluvial basin. The tunneling community will find relevance in hearing about this critical infrastructure project from a leading wholesale water utility owner with a proven track record for on-time, collaborative projects.

Dec 1, 2022

By A. C. T. Bigg, Y. Kocak, N. K. Bodur

The Gumuskoy silver mine, owned by the Etibank, in the province of Kutahya, Turkey, has been operating since 1987 with primary, secondary and tertiary crushers, and two parallel single stage ball mill circuits. Continuing problems with crushing and feeding of the ore to the ball mills, because of the moisture retaining and sticky nature of the ore, prompted an investigation into the possibility of converting the grinding circuit to an autogenous or semiautogenous grinding circuit. This would remove the bottleneck associated with the secondary and tertiary crushing. At the same time the target feedrate is to be raised from 140 t/h to 175 t/h. This paper demonstrates the response of five ore types, and blends of ore types in an onsite pilot plant test program, and also suggests how the variations can be handled in a SAG mill/ball mill circuit incorporating just one of the present ball mills.

Jan 1, 2000

By Michael Amick, G. Swan, R. Hill, C. Pritchard

Falconbridge, a major base metal producer in the Sudbury Basin of Ontario, identified a need to find a safe and cost effective replacement for welded-wire mesh used to support loose ground during underground nickel mining. Falconbridge took a methodical approach to the concept of a spray-on liner as a screen replacement proving the strength characteristics of the liner as a safe, cost effective, and suitable method of supporting ground. Compact, hydraulic mixing and spraying equipment have been developed and are in use at the Fraser mine. The Tekflex material has been approved as a wire-mesh replacement and has been in use since November1998.

Jan 1, 2000

By K. E. Kolm, W. H. Langer

Developing natural aggregate resources (sand, gravel, and stone) creates environmental impacts. A systems analysis method has been designed to characterize the components of the environmental system, identify potential impacts to those systems, and evaluate the extent of those impacts. The step-wise method consists of problem definition, data collection, preliminary conceptualization and characterization, additional data collection, data analysis, and refinement. The method requires analyzes of various systems making up the environment, including land surface, geomorphic, subsurface, and groundwater systems. After system characterization is complete, the method focuses on identifying and evaluating potential environmental impacts to determine acceptable mining strategies.

Jan 1, 2001

By Harry D. Lewis

Gilsonite is a lustrous black material that can be easily crushed into a chocolate-colored powder. It is a solid but relatively soft, lightweight hydrocarbon that visually resembles the volcanic glass obsidian. It was once thought to be a type of coal, but because it is thermoplastic it melts rather than bums. Gilsonite is found in commercial quantities only in the Uinta Basin of eastern Utah and western Colorado, where it forms vertical, nearly parallel veins of varying depth, width, and length. Gilsonite from different veins has different properties, most notably variations in softening point and solubility. These differences result in its use in a variety of industrial applications. Gilsonite's earliest commercial uses were in varnishes, buggy paints, and beer vat linings. Eventually it came to be used in more than 160 products ranging from inks to explosives. It is exported from the United States to most industrialized countries throughout the world. Today, due to competition from synthetics and other hydrocarbon products, its use has narrowed to several specific industries. Although sold mostly as a commodity, current research is focused on applications for gilsonite as a value added product. Historical Overview The discovery of gold in California and the dawn of the mining era in Nevada, Colorado, and Utah around 1850 brought a wave of prospectors to the western United States. One of those pioneers, Samuel H. Gilson, is generally credited with a major role in the discovery of gilsonite. The material now known as gilsonite was discovered several times from the late 1860s through the mid-1880s. It was William P. Blake who, after receiving samples of the material, wrote a paper in 1885 describing "a new variety of asphaltum from the Uinta Mountains." He termed the material uintaite. Although Sam Gilson was not the first to discover the mineral, he was an-inventor who used gilsonite in products that he patented. It was his conviction that the substance was of great value, which caused some to refer to it as gilsonite. The term Gilsonite became the registered trademark of the American Gilsonite Co., and it continues to be in use today. When the first company was formed to mine this substance in 1886 it was named the Gilsonite Manufacturing Co. This firm acquired many gilsonite mining claims and marketed a varnish made from the material. It was the unusual properties of gilsonite varnish that attracted the attention of Adolphus Busch of the Anheuser-Busch Brewing Co. In 1889 Anheuser-Busch bought out Gilson's interests and formed the Gilson Asphaltum Co. Busch had been importing asphalt from Sicily for use in lining beer barrels and saw gilsonite as being more readily available and cheaper. Although gilsonite did not work well in this application, Busch did acquire a large number of mining claims in the Uinta Basin. In 1903 the parent firm of Gilson Asphaltum financed the building of an 85-km railroad from near Grand Junction, CO, to Dragon, UT, to haul gilsonite ore to market. Underground mining was initially centered near Dragon and then later at Bonanza, UT, as different veins were mined. The railway was abandoned in 1937 in favor of truck transportation. In 1938 Gilson Asphaltum changed its name to Barber Asphalt Co., the predecessor of Barber Oil Corp. In 1946 Barber Oil teamed with Standard Oil of California to form a partnership, American Gilsonite Co., which today has its operational headquarters at Bonanza, UT. Barber Oil investigated many new uses for gilsonite, including the making of petroleum derivatives such as gasoline. This work led to the construction of a 116-km pipeline to carry slurried gilsonite to a refinery in Colorado for the production of gasoline, fuel oil, and coke. Pipeline operations began in 1957 but stopped when the economics of competing with petroleum became unfavorable, and the refinery was sold in 1973. In 1981 Standard Oil (later Chevron) became the sole owner of American Gilsonite and remained so until 1991, when it sold its interest to Stratford Enterprises Co. of Tulsa, OK. The companies have since been merged and now operate under the name American Gilsonite Co. with headquarters in Salt Lake City, UT. American Gilsonite continues to be the world's largest miner and supplier of the mineral. The American Asphalt Association was formed in 1902 by former stockholders in Gilson Asphaltum. This company mined various gilsonite claims until it was dissolved in 1953 and its properties were sold to American Gilsonite and Gordon S. Ziegler and Associates. The Utah Gilsonite Co. was established in 1920 and mined several claims until 1952, when its holdings were sold to Gordon Ziegler. Several other gilsonite mining ventures have been pursued in Utah, although they were significantly smaller in scale than those described above. There are currently three companies which mine gilsonite resin in Utah. They are American Gilsonite Co., Ziegler Chemical & Mineral Corp., and Lexco.

Jan 1, 1994

By B. K. Blashich

In responding to mine fires and explosions, accurate and timely analysis of the mine atmosphere is critical in making decisions regarding firefighting, mine rescue and mine recovery operations. For many years instantaneous analyses were available to rescue workers using handheld or portable gas detection equipment, including infrared, electrochemical, or catalytic measuring devices for a limited number of specific gases such as oxygen, methane, carbon monoxide and carbon dioxide. Instantaneous sensing technology is not available for all gases, such as nitrogen and hydrocarbons, found in a mine fire atmosphere and cross-sensitivity can be a problem with this technology. For these reasons, air samples are collected for injection into a gas chromatograph for a complete and accurate analysis for all gases including oxygen, nitrogen, methane, carbon monoxide and carbon dioxide, as well as ?fire gases? such as hydrogen, ethylene, ethane, and acetylene. This method requires additional time for transporting the samples to the laboratory near the mine, as well as an instrument operator to inject the samples for analysis. The use of a portable micro gas chromatograph with a continuous and automatic injection system has been implemented by the Mine Safety and Health Administration (MSHA) during mine recovery operations. The device directly samples the mine atmosphere from an underground location every twelve minutes and automatically analyzes the samples for all of the mine fire gases. The portable unit utilizes micro technology and the operating software has been modified to perform the calculation of sample results in and Excel® spreadsheet without user interaction. This paper describes the micro gas chromatograph system and its use at a recent mine recovery operation. The automated remote operation of the micro gas chromatograph has been shown to be a good alternative to infrared and electrochemical sensors used for mine atmosphere analysis.

Jan 1, 2009

By M. Martins

This work presents and discusses the influence of the surface tension (gLV) of methanol/water mixtures on the flotation response of apatite versus gangue minerals conditioned with flotation reagents (75 g/t cornstarch and 100 g/t Berol 867) at pH 10.6. Berol 867 is a collector composed of sodium alkyl sarcosinate plus nonionic surfactant. The highest Schulz efficiency of separation (recovery of apatite minus recovery of gangue) was achieved at ?51.0 mN/m. The critical surface tension of wettability (gC) of apatite was found to occur at 34.7 mN/m when determined by means of gamma flotation experiments, and it was 33.9 mN/m when determined by Zisman?s approach.

Jan 1, 2009

By Faruk Oksuz, Clay Haynes, Miguel Sanchez, Patrick Finn, Roger J. Maurer

The Milwaukee Metropolitan Sewerage District’s (MMSD)’s challenges of basement flooding and wet weather sewer overflows are being creatively addressed with the Northwest Side Relief Sewer tunnel. The $132 million, 20-foot diameter, and37,740 feet long conveyance and storage tunnel excavation in dolomite at depths reaching 165 feet below ground surface has been successfully completed within13 months in April 2004. This paper includes Owner’s perspective on the overall project, and the design and construction details by the Designer and the Contractor. The project contract documents included a comprehensive Geotechnical Data Report and the Geotechnical Baseline Report.

Jan 1, 2005

By M. Radwan, S. Shimada, S. Z. El-Tawil, K. A. El-Barawy, Y. Miyamoto

This study presents the results of synthesizing monolithic siliconoxynitride, Si2N2O, ceramic from a mixture composed of reclaimed silicon and natural desert sand by using the nitriding combustion synthesis method. Single-phase Si2N2O powder was prepared by the combustion of a mixture composed of silicon and pulverized sand in 3 MPa nitrogen gas. The combustion reaction completed in 2 min and the combustion temperature reached 1577°C.The as-synthesized Si2N2O powder is agglomerate of fine particles with sizes < 5 µm and has various morphologies; rod-like and irregular crystals, irregular kinking, hollow crystals and grown pseudo-hexagonal prismatic crystals. Porous Si2N2O compacts (24.5–47.1% porosities) were fabricated from the synthesized Si2N2O powder at different calcia-alumina additives (5–20 wt%) by normal sintering at 1500°C for 1 hr in N2atmosphere.They showed superior oxidation-resistance at high temperatures up to 1500°C in an oxidizing atmosphere of Ar/O2/H2O(70/20/10 kPa).Near-full dense Si2N2O compacts were also successfully fabricated from the synthesized Si2N2O powder with 5 wt% oxide additives by using the spark plasma sintering at 1600°C.DenseSi2N2O had good mechanical properties (18.7 GPa Vickers hardness, 3.3 MPa.m1/2fracture toughness and 363 MPa strength) and excellent chemical and oxidation resistance.

Jan 1, 2004

By J. D. Morgan

In the first half of the year, lessening of cold war tensions was welcome. But Iraq&apos;s invasion of Kuwait in the second half led to the Persian Gulf War in January and February 1991. This caused an oil shock that dampened the economy. So the US gross national product rose only 0.9% to $5,463 billion (US billion = 109). The buildup of military forces in the Persian Gulf area focused greater attention not only on petroleum but also on other strategic materials. The Department of Defense continued to review stockpile goals and to upgrade several mineral materials. In addition, the Bureau of Mines continued to maintain the standby Emergency Minerals Administration. The Defense Production Act, which authorizes priorities, alloca¬tions and supply expansion, lapsed on Oct. 20. So the Selective Service Act of 1967 became the authority for assuring that orders of the armed forces and defense atomic-energy programs were given priority treatment. Consumer demand strongly affects mining worldwide. US citizens carry significant debt, and large stocks of housing and consumer goods are already in place. Some 250 million persons have 188 million licensed motor vehicles and 100 million dwelling units. Consequently, new car production fell 11 %, to 6.1 million units. Truck and bus production fell 8%, to 3.7 million units and new private housing starts fell 13% to 1.2 million units.

Jan 1, 1991

By H. Lowers, B. Van Gosen

The Iron Hill (Powderhorn) carbonatite complex is a 31 km2 alkalic intrusion located about 35 km south-southwest of Gunnison, Colorado. The intrusion has been well studied and described because of its classic petrology and architecture of a carbonatite-alkalic complex. The complex is also noteworthy because it contains enrichments of titanium, rare earth elements, thorium, niobium (columbium), vanadium, and deposits of vermiculite and nepheline syenite. In particular, the complex is thought to host the largest titanium and niobium resources in the United States, although neither has been developed. It may be economic to extract multiple resources from this complex with a well coordinated mine and mill plan.

Jan 1, 2007