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By K. J. Stanaway

Major world ilmenite and rutile accumulations reveal similar regional geology and Proterozoic age deeper crustal source rocks. During crustal collision titanium crystallizes as ilmenite and rutile at buried sites of high pressure and temperature rock metamorphism. Hydrothermal activity can convert titanium minerals to rutile, but titanium migration and enrichment seem only local. Many melts crystallize rocks with iron-titanium oxides in solid solution, but titanium enrichment at economic scale takes place in basic intrusive melts often associated with anorthosites and charnokite. Sedimentary placer enrichments have formed since the Proterozoic with water-resistant ilmenite, and rutile segregating by gravity from quartz sands deposited from flowing water. Placers have residual, alluvial, strand and shallow marine variants. Time, organic acids, and sand permeability play lead roles in the leaching of iron from ilmenite during weathering and diagenesis.

Jan 1, 2005

By Eung Ha Cho, Wendi Li

Wet desulfurization of Pittsburgh No. 8 coal and Illinois No. 6 coal were conducted with sodium hypochlorite in the laboratory. Pittsburgh No. 8 coal was leached by hypochlorite at high pHs in one step only. The hypochlorite concentration varied from 0.2 to 0.6 molar; sodium hydroxide concentration, from 0.2 to 0.8 molar; and temperature was at the levels of 80 and 90°C. The desulfurization of Illinois No. 6 coal was conducted in three consecutive steps of pretreatment in concentrated ammonia at room temperature, leaching with hypochlorite at room temperature and hydrolysis in sodium hydroxide solution at 90°C. In the leaching step, hypochlorite concentration varied from 0.2 to 0.8 molar. The desulfurization method of Pittsburgh No. 8 coal was found to reduce mainly pyritic sulfur. More than 70% of pyritic sulfur removal was achieved at the optimum conditions of 0.4 molar hypochlorite, 0.4 molar sodium hydroxide and 90°C. The desulfurization method for Illinois No. 6 coal was capable of reducing significant amounts of organic sulfur. The removal of organic sulfur achieved a 37.8% reduction at the optimum operation of leaching at 0.4 molar hypochlorite and room temperature followed by hydrolysis at 0.3 molar sodium hydroxide and 90°C. The chlorine content in the coal produced by the chlorination during leaching was kept below the threshold value of 0.3% at the optimum conditions of the desulfurization method for each coal.

Jan 1, 2005

By Jozef F. Zurawski

Increasingly new interceptors or new Combined Sewer Overflow (CSO) projects require connections to existing tunnels. More often than not, the existing facilities are old, in poor or questionable conditions, without proper construction records or as-built drawings. Many cannot be easily inspected unless major construction effort provides flow by-pass for safe access. This paper provides general guidelines on how to approach the problem of assessing the condition of old tunnels, how to plan and design the connection with limited physical assessment, how to develop the scope of work for the bid documents and how to provide geotechnical guidelines and designs for the bid documents.

Jan 1, 2008

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

The Mine Safety and Health Administration (MSHA) conducted a respirable dust survey to evaluate the effectiveness of a water curtain utilized for dust control on continuous miner sections. The purpose of this survey was to determine if the water curtain was effective in reducing respirable dust concentrations, since several mines currently use water curtains to control miners? respirable dust exposures. The survey was conducted on a supersection of an underground coal mine, which utilized two continuous miners on the same split of air. Each continuous miner alternated taking a cut so that both continuous miners would not operate at the same time. The underground coal mine is located in Knox County, Indiana. The water curtain evaluated in this survey was located in the last open crosscut between the intake side continuous miner and the return side continuous miner. When the intake side continuous miner cuts coal, its exhaust air would be used to ventilate the return side of the section. The intent of the water curtain was to reduce the intake air respirable dust concentration (generated by the intake side continuous miner) before the air stream ventilated the return side of the section. To determine the effectiveness of the water curtain in reducing respirable dust concentrations, respirable dust sampling pumps were placed on both the intake side and the return side of the water curtain. Additional respirable dust sampling pumps were placed farther downstream from the water curtain to monitor dust levels downstream of the water curtain, but in an area where respirable dust would not be created by anything other than the intake side continuous miner or additional section air. The water curtain and the respirable dust sampling pumps were operated only when the intake side continuous miner was cutting coal. The samples were analyzed for respirable dust and quartz content. The water curtain showed minimal effect in controlling respirable dust and respirable quartz dust, but the reduction was so negligible that this survey could not quantify the reduction. The measured reductions are within the accuracy of the sampling equipment.

Jan 1, 2009

Soil erosion is strongly related to soil hydraulic properties. Understanding how surface coal mining impacts those properties is important in developing effective management practices to control erosion during reclamation. Soils from undisturbed areas, roughly graded mine spoil, replaced topsoil before seeding, and revegetated areas at the Rosebud Mine in Eastern Montana were evaluated to determine impacts on soil hydraulic properties. Field and laboratory studies were conducted to determine soil hydraulic properties, including particle-size distribution, organic matter content, and saturated hydraulic conductivity. WEPP simulations and risk analyses were performed on the soil hydraulic property data to determine the impacts of changes on soil erosion. The hydraulic properties of the soils in each representative area have significant differences due to the mining and reclamation practices at the mine. WEPP simulations show that the potential for soil erosion increases due to mining activities disturbing the soil. WEPP simulations also indicate that the potential for erosion may return to pre-mining levels over time with effective revegetation practices.

Feb 27, 2013

By L. Tercero Espinoza, F. Marscheider-Weidemann, C. Gandenberger

"A reliable supply of non-energy raw materials is a precondition for the functioning of the European economy. In line with its importance, the issue of raw materials supply has become more prominent in the past years, especially owing to turbulent raw material markets. However, these turbulences are not due to depletion of the geological resources but to a missmatch of (expected) supply and (expected) demand, with several interacting factors influencing the markets both from the supply as well as from the demand side. A recent evaluation, published in June 2010 within the framework of the EU Raw Materials Initiative, sought to bring together these two sides of raw material markets and asked the question "which raw materials are critical for the EU?" Herein we present the methodology used by the Ad-hoc Working Group on Defining Critical Raw Materials and the results obtained, complemented by results from the study "Raw Materials for Emerging Technologies"."

Jan 1, 2011

By Allen W. Hatheway, John A. Albritton, Lloyd B. Underwood

Missouri River Division (FORD), U.S. Army Corps of Engineers (COE), has completed (October 1982) a study for the U.S. Air Force Ballistic Missile Office, in which desireable and needed changes in contracting methods for underground construction were identified. Due to the importance of geotechnical considerations in such construction, a good number of the resulting recommendations relate to geotechnical considerations. Corps contracts have traditionally served as models for contract documentation by public agencies and in private enterprise. Several standard features of present-day contracting methods were Corps innovations. Corps officials are generally in agreement with the recommendations of the Better Contracting reports published by the U.S. National Research Council (NAS/NRC), through its U.S. National Committee on Tunneling Technology (USNCTT). However, the findings of the 1982 MRD study indicate that additional changes are warranted for underground construction contracting methods; changes that deal specifically with site geological conditions, both known and to be reasonably anticipated, as well as with their associated impacts on construction. The 1982 MRD report identifies the need for nine specific improvements in geotechnical aspects of contracting; improvements based on recognition of geological conditions.

Jan 1, 1983

By Beth Robinson

This first of two articles on the Second Mexican Mining Rail Excursion describes some of the more casual experiences participants enjoyed on last fall’s rail tour of major Mexican mining operations. In this article, Beth Robinson, a graduate student at Colorado School of Mines, describes trip organizers, participants, and some of the unique events occurring during the two-week excursion. Next month, part two of the series will highlight various Mexican mines and plants.

Jan 1, 1982

By D. Küster, G. Franken, P. Schütte, J. Vasters

The CTC (Certified Trading Chains) mineral certification system has been piloted in Rwanda since late 2008. CTC project implementation is jointly driven by the Federal Institute for Geosciences and Natural Resources (BGR) and the Rwanda Geology and Mines Authority (OGMR), in cooperation with other national stakeholders. Five Rwandan mineral producers participate in the CTC project with their flagship mining concessions. Based on independent third-party audits, CTC certifies supply chain due diligence measures of these companies engaged in the artisanal mining sector through on-the-ground assessments of mining conditions, transparency, as well as mineral origin and traceability. The CTC system thus allows responsible mineral producers and their clients to verifiably demonstrate supply chain due diligence and good governance in conflict-affected and high-risk areas.

Jan 1, 2011

By S. Addie

In the early 1990’s the British Columbia (Canada) mineral industry frequently discussed the need to participate in, and compromise with, public environmental interests in order to ascertain long-term stability. However, as the decade progressed the mineral industry withdrew from almost all meaningful public participation. As government protected areas policy in the past year has illuminated, there is a continued need for long-term land access stability. This paper historically analyses the public engagement policies of the British Columbian mineral industry while it participated in long-term consensus-based multi-stakeholder land-use planning processes. From this analysis the paper recommends that the mineral industry reengage the public and institute a new working relationship with environmental advocacy groups so as to ensure British Columbia becomes the most sustainable mineral producing jurisdiction in the world.

Jan 1, 2011

By D. R. Dolinar

The fall of small pieces of rock between roof bolts causes over 80 pct of the ground fall injuries in underground coal mines. Roof screen, if installed on the bolting cycle, can significantly reduce the number of these injuries. As the surface of the roof fails, the screen will have to retain the broken rock without failing or excessive deformation. Welded wire screen is the most common type of screen material used for roof surface control in underground coal mines. The load-deformation characteristics and the load capacity of welded wire screen were evaluated in the laboratory in a specially built test frame. In the frame, the square screen sections were held in place by bolts and bearing plates at the four corners while a center load was applied to the screen. The parameters evaluated included the wire gauge and configuration, the bearing plate loads and bolt spacing. The wire gauge of the tested screen was 4, 6, 8, 9 and 10. Maximum screen capacities for both load and displacement were developed for each of the wire gauge sizes along with the screen stiffness. This information can be used for screen selection and for the evaluation and determination of screen performance. DISCLAIMER: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

By B. Gigas, M. Preston, M. Giralico

Optimized mixer settler designs will now handle total flows of over 6,000 m3/hr.Computational Fluid Dynamics (CFD) is a timely and predictable tool for design development. Lightnin has the capability of using numerical analysis methodology to evaluate flow patterns and phase separation. CFD can show performance differences between changes, in mix tanks, in settler geometry, and in liquid depth, against variable flow rates. Understanding the differences allows the development of optimized designs. This paper focuses on the major design components of the mixer settler and how technological advances will lead to further improvements, when designing for today’s largest flow plants.

Jan 1, 2004

By A. Mayton, W. Porter, A. O’Brien

In 2004, management at Unimin’s Gleason, TN operation began implementing ergonomic interventions specifically targeted to reduce risk of musculoskeletal injuries (MSIs). Together with corporate and site management, Unimin identified work site hazards and began to modify work practices/equipment. Some interventions were relatively simple and were implemented immediately. Others, like improvements to a mobile shredder, were more complex but were eventually resolved through a participatory approach with employees, management, manufacturers and NIOSH. This paper discusses ergonomic interventions that were successfully implemented using a bottom-up approach to reducing the risk of injury.

Jan 1, 2007

The safety of personnel is the most important matter during a mine fire. However, there is not enough research on a case when a fire occurs near a shaft and the behavior of the fire gas is not well understood. Therefore, a series of experimental study using a scaled ventilation circuit model was carried out. The behavior of ventilation air during a mine fire near a shaft was investigated. The model consists of two vertical shafts, three horizontal ducts connecting the shafts and an exhaust fan from the shaft bottom. The cross section of the shaft and duct is a square of 200×200mm. The height of the shafts is 3400mm. The length of the ducts is 1540mm. The lower duct is set at the same level as the shaft bottom. The middle and upper duct are set at 750mm and 1760mm above the shaft bottom respectively. The airflow rates through the ducts can be adjusted by regulators installed in each duct. The behavior of the fire gas was measured by anemometer, thermometer, and visualized using laser light .The air was ventilated downward in both shafts before the initiation of the fire. Some amount of fire gas of high temperature rose upward gradually along the shaft wall regardless of the downward ventilation after the initiation of the fire. Then the direction of main ventilation air suddenly reversed upward in the shaft. The direction of ventilation reversed in many places in the model and the fire gas reached even the part not anticipated.

Jan 1, 2009

By Russell Barr, Robert E. Cook

As most mining companies are taking advantage of the high market prices for base metals such as steel, copper and zinc, numerous challenges still face them. While demand is strong from countries like China and the United States, demand is still mixed in Europe. This leads to the question of how long these high prices and overall high global demand will last. The tremendous market prices of most precious and base metals have enabled many companies to pay down a significant amount of debt accrued during acquisition and capital expenditure phases. Additionally, mining companies have been able to internally fund and engage in large projects to address future growth, (Less, 2006), thus maximizing the performance of the existing asset base, driving maintenance costs down, and improving and empowering the work-force (Mining Journal, 2006). Market prices and general efficiency gains have addressed these issues to some extent. However, critical issues still face operating managers in the mineral pro-cessing side of the industry. Energy prices, for example, continue to have a negative impact on cash costs for producing an ounce of gold or ton of a given base metal (Cummins, 2003).

Jan 1, 2007

Introduction The Homestake Mining Co. has always been big on gold. After 108 years in the business, the company and its principal product are almost synonymous. The relationship continues. On Sept. 28, 1985, Homestake held formal dedication ceremonies for its newest gold mine - McLaughlin. The McLaughlin open-pit operation is located in northern California, some 113 km (70 miles) northeast of San Francisco. It lies near the boundaries of three counties - Napa, Yolo, and Lake - and a portion of its facilities are located in each. McLaughlin was originally the site of the Manhattan mercury mine that produced nearly 80,000 flasks of the quicksilver from the 1860s to 1978. At the September dedication, Homestake renamed the mine in honor of the late Donald H. McLaughlin. McLaughlin was with Homestake for nearly 60 years. He rose from exploration geologist to his ultimate positions of chief executive officer, director, chairman of the board of directors, chairman emeritus, and chairman of the executive committee. The discovery of the McLaughlin deposit occurred in 1978, the last year of operation for the Manhattan mine. Homestake geologists used a newly developed model and found surface gold at the mine site. That same year, Homestake signed an agreement with the property owner and began a two-and-a-half year exploration program. An initial discovery announcement of 31.1 t (1 million oz) of gold was made in 1980. In 1981, this was revised to 93.3 t (3 million oz), or 18 Mt (20 million st) of ore grading 5.2 g/t (0.152 oz per st). Expected mine life is 20 years. Construction began in September 1983, following the issuance of stage one permits. Start-up of operations took place in early 1985 and the first gold-silver dore bar was poured on March 4. Since then, more than 540 kt (600,000 st) of ore has been milled, producing about 1.6 t (50,000 oz) of gold. Of special interest at McLaughlin is the use of three autoclaves for gold extraction. According to Homestake, this is a first. The autoclaves are designed for a 90% gold recovery rate. Early results have proven yields at this rate and higher. Geology The McLaughlin deposit is about 1.5 km (5000 ft) long. It occurs as a wedge-shape, narrowing to a verti-

Jan 1, 1986

By Amanda Elioff

Success of the Gold Line Eastside Extension rail tunnels in Los Angeles has prompted Metro?s planning for two new rail lines to include underground alternatives. The Westside Extension Transit Corridor alternatives include up to 17 miles of subway to be constructed in soft ground. The routes will require construction in Los Angeles? ?Potential Methane Zone,? not considered for subway construction until recently. Slurry face TBMs will likely be specified. The Regional Connector, through the downtown area, includes one underground alternative with 1.7 miles of tunnel as well as three underground stations in soft ground and rock. Challenges will include tunnel and station construction under narrow streets. This paper will describe the alternatives, planning, geologic conditions and tunneling concepts for both planning studies.

By J. K. Lemley

The human element in large measure dictates success in contracting relationships. Because of our professional backgrounds, we view contracts primarily as either engineers, contractors or owners. A beneficial contractual environment--one in which decisions, risks and benefits are shared--demands equal consideration of all three points of view. Most of the older cities in the United States, for example, suffer from bad contracts--generalized, patched-together documents that represent an accumulation of modifications originally written to compensate for specific situations that have occurred over the years. Because such documents lack coherence, they often present conflicting instructions which lead to defensive, ultimately destructive attitudes among the parties involved in the day-to-day administration of the project. Good contract development begins with a strong central philosophy to which the details of the contract can be related. First, the owner should establish a comprehensive philosophy in which risks between the parties are identified. Following this, a specific contract document can be written to satisfy this established philosophy. The contrast between two opposed contractual situations, NYC Water Tunnel Number Three and the Seabrook Nuclear Power Plant Cooling Water Tunnels, illustrates how comprehensive, well-written contracts--contracts which share both risks and benefits--provide the basis for achieving quality construction that will reward engineer, contractor and owner.

Jan 1, 1983

By N. Aouad

Dump truck operators are exposed to whole-body vibration (WBV) levels that exceed the International Standard Organization (ISO) 2631-1. The WBV level measured by RMS acceleration value, for operator comfort, and long-term health and safety is under 0.315 m/s2 by these standards. However, fundamental research by Frimpong and Aouad (2009, 2012) and field experimental study by Kumar (1999) have shown that operators are exposed to extreme WBV levels exposing them to injuries and musculoskeletal diseases in the long-term. These extreme WBV values in the vertical direction are equal to 3.56 m/s2, 1.12 m/s2 and 0.87 m/s2 for the operator?s seat, lower-back and cervical regions, respectively. This paper will outline current research to solve these problems. Keywords: WBV, Truck Vibrations, MSC.ADAMS, Virtual Prototyping

Feb 27, 2013