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By Sumit Kumar Hota, Asadi Srinivasa Reddy, Ashok Kumar, Ashish Agrawal, Surajit Sinha, Chandra Sekhar, Tanay Ray

In the current operational facility, due to the absence of pellet pot facility, a novel technique is developed wherein the pellets with different chemistries prepared in the laboratory are fired in an induration machine by placing them inside the Inconel baskets. In the present work, an attempt is made to optimize the pellet chemistry by developing 2 different flux pellets, viz., low basicity (B2: CaO/ SiO2 = 0.3) pellets and high basicity (B2 = 0.9) pellets, and further the effects of basicity on pellet properties, viz., cold compressive strength, porosity, swelling index, reducibility index, and softening and melting temperature, are studied. It has been found through the multiple operational trials that increasing the basicity of pellets from 0.3 to 0.9 results into improving the pellet strength, reducibility and softening and melting characteristics. Moreover, it is observed that the swelling index of pellets is reduced by adding 2% MgO to both low and high basicity pellets that could be attributed to the formation of high melting point slag in pellets. The operational trial has resulted into producing pellets that exhibit a combination of desired mechanical strength, improved swelling, and reducibility index and possess better softening–melting behavior among all the chemistries studied.

May 24, 2022

A significant technological development is discussed for the processing of certain problem power plant flyashes which contain a high water soluble mineral content and which are known to yield inferior flyash based brick. This development is based on the addition of hydrochloric acid to the flyash-bottom ash-sodium silicate blends used for the production of flyash based structures. Favorable changes are evident in (1) sodium silicate consumption, where often approximately one-half of the amount used for making brick from normal flyash is required; (2) processing costs; and (3) strength and appearance of the resulting freshly formed green and fired structural products. In some high cost instances-(above the cost of 30 dollars or less per thousand brick estimated for normal flyashes) hydrochloric acid additions can replace or reduce other costly additives required with problem flyashes to result in a savings of as much as nine dollars per thousand brick. These developments offer promising possibilities for utilizing problem flyashes as well as flyashes which may come into contact with water soluble, sulfur as a result of the eventual application of certain experimental air pollution control processes.

Jan 1, 1968

By J. Kern, M. Cain, T. Torries

Until recently, the generation of electricity was regulated in all states and the value of generation assets in a regulatory environment for ad valorem taxation were based largely on the book value of the plant plus the rate of return on capital allowed by the state regulatory agency. This method of appraising utility generation assets is inappropriate in a competitive environment because past capital expenditures are not relevant in a competitive environment. However, it is not clear what valuation methods are appropriate after restructuring. This paper identifies key problems and advantages of other appraisal methodologies and makes comments on various valuation and taxation methods.

Jan 1, 2001

By K. Ward

The Environmental Protection Agency (EPA) is beginning to provide compliance assistance visits to various industries, including mining, for Emergency Planning and Community Right-to-Know Act (EPCRA) compliance. The EPA inspectors may consist of a multi-media team deployed to review systems and procedures for EPCRA Sections 302, 304, 311, and 312. The Team’s focus may include emergency response plans, training programs, qualifications of personnel, and release notification protocols. This presentation takes a look at the EPCRA compliance challenges faced by Arizona copper mining and processing facilities.

Jan 1, 2001

By N. O. Lotter

The reliability of a set of flotation results is key to minimizing project risk either at concentrator commissioning, or at the point of implementing an improvement to an existing concentrator operation. High-Confidence Flotation Testing was developed for this purpose, and is part of the list of technologies of various scales used by Xstrata Process Support (XPS) in addressing these projects. The methodology is based on two principles: one, to ensure that the ore sample is representative and has been well-blended and subsampled; two, to perform the flotation tests in sufficient numbers of replicates with appropriate quality controls, so as to improve the reproducibility of the test data. Across ten years of practice and continuous improvement with this methodology at Xstrata Process Support, Sudbury, several improvements to this method and complementary connections into sampling and quantitative mineralogy have been developed. Two case studies are reviewed. These show the capability of this system in both optimizing an existing concentrator operation and in serving a new mine scenario. Further work to improve the efficiency of this procedure has been identified.

Jan 1, 2009

By R. D. Peterson

As underground mine operations expand, the ventilation systems supporting them become complex. Complexity increases with periodic ventilation changes. New diagonal connections require a rebalance of resistance to maintain airflow in affected splits in the system. Incidents of mine fires and explosions have occurred in U.S. coal mines when diagonal connections resulting from ventilation changes have resulted in changing airflow directions. MSHA regulations prohibit the reversal of airflow and poor ventilation practice in general, but regulations cannot stipulate or recommend proactive preventative measures because every situation is different. This paper discusses the phenomenon of diagonal branches and recommends practical precautionary measures that can be taken to prevent airflow reversal in planned ventilation changes.

Jan 1, 2012

By Bruce Congleton

One year ago this month, we in Central Florida witnessed the beginning of a most exciting and glamorous attraction. After three years of construction and anticipation, Walt Disney World opened its gates near Orlando and during its first year of operation received a flood of over 10 million visitors---half of all who came to Florida last year! The side effects of this newest addition to Florida have been phenomenal. Traffic on heavy days has been backed up for 30 miles from the amusement park along a major interstate highway. Hotels and motels have been jammed packed for months, and reservations are still difficult to make. Gasoline stations, restaurants and souvenir shops are doing a booming business. Everywhere you look as you ride the highways of Central Florida you see the signs of growth. New hotels spring up almost overnight. Golf courses galore. New housing projects and apartments sprawl where orange groves used to be. New roads criss-cross areas which were once deserted. There seems to be no end to the steady influx of tourists and new residents to the Sunshine State. And it's mainly because that we are the Sunshine State that they come. Air and water pollution is and has been at a minimum in Florida. Pollution and emissions are fighting words among some groups dedicated to preserving the bountiful environment we share in Florida. Little wonder then that some of these people display concern when they learn that just 50 miles from the entrance to the Magic Kingdom of Disney, phosphate draglines strip away thousands of acres of land each year to extract one of our nation's most precious

Jan 1, 1972

By J. J. Gusek, T. C. Richmond, R. W. Reisinger

A high-altitude (9,500-ft [2,900-m]) historic underground copper mine in Wyoming discharges neutral but copper-laden water into a pristine creek. Under a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) deferral agreement, the Wyoming Abandoned Mine Land Program performed site characterization and treatment studies in preparation for reclamation of the site. An integral part of the project included addressing the needs of a variety of interested and affected parties, including property owners, local populations, government agencies, and the media. This paper discusses an overall approach and specific methods employed to enlist public support for the project as well as some of the successes and failures experienced.

Jan 1, 2004

By Lee W. Abramson

Performing risk analyses on tunnel projects has become common place and on many projects it is required from an owner or regulatory perspective. After the project is planned, designed and constructed, the data concerning identified risks, assumptions, costs, probabilities and mitigations is generally long forgotten and buried in some file somewhere. A study was performed comparing predicted risks versus actual events on several recently constructed tunnel projects. Probabilities and costs for selectively common risks on tunnel projects have been studied and re-evaluated. Conclusions are presented that can guide future projects and the veracity of the tunnel risk analyses performed.

By V. Kecojevic

Environmental and economic costs related to equipment fuel consumption and carbon dioxide (CO2) emission present a substantial challenge to the mining industry. Haul trucks are an integral part of the overall surface mining system and they consume a significant quantity of fuel. Consequently, they produce a significant amount of CO2. The objective of this research is to (i) establish a mathematical relationship among a truck?s fuel consumption, power and engine load factors and (ii) determine the amount of a truck?s CO2 emission and the associated cost that may arise from potential CO2 legislation. In order to achieve these objectives, the authors have considered original equipment manufacturer (OEM) haul trucks, which are commonly used in surface mining operations. The research presented here may be used by mining professionals to help determine the cost and environmental burden of the trucks? application and efficiently manage energy consumption.

Jan 1, 2010

By Jimmy Thompson

The Santa Clara Valley Transportation Authority is designing the Silicon Valley Rapid Transit Project in San Jose, California. The project includes 6.9 km (4.3 miles) of twin-bored tunnels to be constructed through downtown San Jose using two earth pressure balance machines (EPBMs). This paper begins with a project description and update of the project status followed by a description of the relationship between anticipated ground conditions and EPBM requirements. Topics addressed include soil conditioning, abrasion resistance, annulus grouting, face pressure estimation, additional pressure control devices and control measures to limit over-excavation and settlement.

Jan 1, 2008

By Byron T. Darnton

Gravity concentration at the Pegasus Gold/Montana Tunnels Mine, near Helena, MT, began in June 1991 when a coarse-gold-scalping circuit was commissioned. It processes a small portion of the ball-mill circulating load to reduce the risk of gold particles that are too coarse to float from advancing to flotation. The circuit also cost-effectively enhances overall gold recovery and payable gold ounces. This gravity circuit has been a major success. Since the circuit was commissioned, throughput has increased 30%. Several modifications and improvements were made during the last three years that allowed the gravity circuit to keep pace with the higher tonnage. The overall approach to gravity concentration at Montana Tunnels has always been to optimize production rather than maximize the gold ounces produced. This philosophy has now yielded a circuit expansion and relocation project. It will allow for an estimated 50% increase in gravity gold production, while significantly reducing the unit costs of production.

Jan 1, 1995

By A. L. Martikainen

In fluctuating airflow, continuous air velocity recording is the most reliable method of air velocity measurement. It allows for fast recognition of changes and the calculation of long-term averages. Also, it enables the mine operator to identify when the airflow has decreased to a point requiring action. Using ultrasonic anemometers provides an accurate option for continuous air velocity monitoring. This paper provides information about the effect of common obstructions in underground mining on air velocity readings. Stationary and moving obstructions are used to represent workers and equipment that would cause discrepancies in measured airflow. Also, it is important to know how large of a sample size is required to ensure reasonable accuracy of results. Statistical analysis is used to evaluate the required sample size. The sampling procedure is further studied by comparing two different sample rates. The results show that obstructions provide noticeable differences in air velocity measurements. Also, movement of obstructions can be recognized from changes in results. Surprisingly small sample sizes provide reliable air velocity information. Standard sample rates are found to be suitable for the underground environment.

Jan 1, 2011

By Bruce Geller

The 2004 Prospectors and Developers Association of Canada (PDAC) conference contained an air of optimism and excitement that has not been seen since 1997. Many segments of the mining industry are alive and well. This is largely a reflection of improved metal prices, themselves due to the strong euro and improvements in Asian economies. Those factors offset higher oil prices, a weaker U.S. dollar and concerns about the Middle East. This report is an overview of the conference. It is supplemented by an examination of conference handouts, abstracts and a few complete papers that are on the PDAC’s Web site www.pdac.ca. Sixty PDAC 2004 abstracts are available at the same site, along with 15 complete papers in PDF format. The conference was held March 7-10 in Toronto, Ontario. It was attended by a record 9,200 delegates from 85 countries. About 8,000 people from 74 countries attended the 2003 conference.

Jan 1, 2004

The only significant iron ore deposit in Hungary could be found in Rudabánya. The mine was closed in 1986. The area of Rudabánya was always the home of heavy mining activity. In former times, mainly silver and other non -ferrous metals were excavated.

Jan 1, 2011

By Werner Burger

The last decade has witnessed a rapid development and application of slurry and EPB type tunnel boring machines. Both soft ground types are able to excavate tunnels in unstable ground conditions below the water table with positive face support. The most significant component of the excavation process is the cutterhead and tool con-figuration were the excavation and face support meets the geological challenge. The TBM downstream processes cannot take place unless the cutterhead and tools effectively do their job. This paper will review the current state of the art design for both slurry and EPB cutterheads and highlight both common as well as geological specific design features.

Jan 1, 2007

By J. F. Oyler

One of the most important applications of material handling engineering technology occurs in iron ore pelletizing plants. Although the total installed value of material handling systems in such plants, as well as in many other modern process plants, is a relatively small percentage of the value of the plants (5 to 10% perhaps), their significance is considerable. Indeed this significance equals that of the more expensive process equipment in the plant, since the failure of any component of any system causes, shutdown of the entire plant. It is because of this increased consequence of failure that design criteria for process plants are more conservative than for conventional material handling applications. A second unique characteristic of material handling technology applied to process plants in general is the variety of materials being handled and the wide range of problems this variety presents. One extreme encountered is the stickiness of filter cake. Here the entire design effort is aimed at keeping the material flowing through transfer points and preventing it from building up on components. Another extreme is the conveying of fired pellets - hard spheres with a very flat angle of repose and abrasive characteristics severe enough to make conventional wear plate materials impractical.

Jan 1, 1976

By P. D. Lafleur

A concerted effort to determine the quantities and effects of trace elements in the environment requires the application of a number of different analytical techniques in the same or in different laboratories. The interpretation of analytical data is often difficult because of differing results between analysts or even by the same analyst at different times. Standard Reference Materials (SRM), which are certified for their trace element content and are in a matrix similar to the one of interest, can greatly increase the accuracy of analysis and the reproducibility between laboratories. The United States National Bureau of Standards (NBS) has developed a number of SRMs applicable to the determination of trace elements in environmental materials. Two of these, SRM-1571, Orchard Leaves, and SRM-1577. Bovine Liver, are excellent for biological tissue analyses. Several new standards are of value for fossil-fuel analyses. These are: SRM-1632. Trace Elements in Coal; SM-1633, Trace Elements in Fly Ash; SM-1634, Trace Elements in Residual Fuel Oil: and SRM-1635, Trace Elements in Gasoline. In cooperation with the US Environmental Protection Agency, the NBS has recently concluded an interlaboratory comparison involving analyses by more than 60 laboratories on these fossil-fuel materials. The resulu of this intercomparison and the broad range experience with the biological materials will be presented showing both intratechnique and intertechnique variations, and the sensitivities and comparisons with the values certified by NBS.

Jan 1, 1975

By Dave Ragland

The SDSU tunnel and underground station are the first of these type facilities to be constructed by the Metropolitan Transit Development Board. Because there is no previous experience, and because tunneling activities are associated with some risk, he MTDB has undertaken a very proactive and wide reaching program to identify and control risks during construction. Finally, because the tunneling activity and underground station is on the San Diego State University, MTDB is working closely with their staff to identify construction impacts and mitigation’s, and thus ensure a quality project for both agencies.

Jan 1, 2001

By John A. Cordes, Thomas F. Torries

INTRODUCTION Nonfuel mineral markets have always tended to be volatile due to the cyclical nature of demand and the difficulty of fine-tuning capacity and output levels. Experiences over the past two decades, however, have been especially perverse. This short volume attempts to provide insights into this era and some guidance for the future. The papers are linked together by their focus on issues of productive capacity. At the same time, they provide a useful description, explanation and evaluation of the industry's evolution and its implications for the near-term. The regnant pessimism of the 1980s was very much alive during the early months of 1987 when the theme of this symposium was formalized. Indices of real metal prices had only inched-up from all-time lows in 1986. The hemorrhage of corporate red-ink was still a powerful memory. Frustration with the apparent inability of closures and reduced capacity utilization to re-establish market balance was strong. To the more pessimistic, the industry appeared destined to a quarter century of persistent excess capacity and nonremunerative prices. The conditions to support this pessimism were readily apparent. Economic literature tells us that surplus capacity is a complex, usually unexpected and often long-lived phenomenon caused by the interaction of at least three factors. The first is a rising capital-intensity of production. The second is the presence of aggressive new entrants whose capacity additions are typically (1) trade- dedicated because local market absorption is low; (2) cost-competitive for natural or policy-support reasons; (3) heavily burdened by debt-repayment obligations; and (4) viewed as important sources of employment, regional development and foreign exchange. The third, and often decisive, factor is an unanticipated decline or stagnation in demand growth for the sector's output. The first two factors combine to increase competitive pressures and to raise the actual or perceived cost of idle capacity. Market rigidity reduces responsiveness to price signals and distorts the burden of adjustment. Demand atrophy exacerbates these pressures especially on unprotected producers in the higher quadrants of the global supply function. In the mid-1980s, evidence of the existence of all these factors were easy to cite. Culprits were often identified. Claims for protection, global sharing of adjustment burdens, and imposition of disincentives to new capacity regardless of inherent economic status were co-dominant themes with the buzz-words of "competitiveness" and "level playing fields." This, notwithstanding the suggestions of the same economic literature that excess capacity persists longest when interventionist remedies permit it to continue. Today, only eighteen months later, the mood is decidedly more buoyant and most analysts are cautiously optimistic about the next few years. Many informed analysts have concluded that the excess capacity of the recent past has disappeared. For the present, the marketplace seems to have restored a balance between supply and demand. That the adjustment took five or six years longer than anticipated attests to the dramatic structural changes which have characterized the industry. The implications of these changes for the future are unclear. Were the macroeconomic shocks, coupled with industry transitions, so extraordinary in magnitude and timing that experiences were unique? If so, the next years may hold more stable and cautious times for the industry. Alternatively, is the inherently volatile metals industry facing a future of cycles equally perverse in terms of amplitude and duration due to economic uncertainities and inflexible industry response capabilities?

Jan 1, 1989