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By Robert J. Garino

Around two-thirds of world silver mine production comes from mines where the majority of ex-mill revenue is obtained from other metals. In this talk I will illustrate the importance of this output of silver as a by-product of the mining of various base metals. I will also consider the impact of relative changes in base and precious metal prices on mill-head revenue, and therefore, on production decisions. During the latter half of 1982 improving silver prices encouraged re-openings at several base metal mines. Thus some production of lead, zinc and copper can be regarded as partly conditional on the prevailing silver price. Conversely, a good deal of silver production can be considered to be independent of the silver price and dependent on the production of some base metal. It is the degree to which the value of silver mined affects the revenues of nominally, base metal, producers that is the central concern of this presentation.

Jan 1, 1983

By L. Bloom

In 1996, lack of confidence in assaying methods and sample handling affected companies as diverse as Bre-X and Timbuktu. Both share prices and the ability to raise financing are impacted when the quality of assay data is suspect. Overseas projects are subject to enhanced scrutiny when local facilities are used that are unfamiliar to brokers, financing agencies and banks. Quality control systems can be -implemented but there are associated costs. These costs should reflect the risk to the mining company, investors and financiers and the size of the proposed investment. In this regard, assay control call is considered a form of insurance to enhance the value of an exploration or mining project.

Jan 1, 1997

By C. Van Landingham, A. Bailey, R. A. Schoof

A residential metals abatement program has been underway in Butte for more than 20 years. More than 1,350 yard and attic cleanups were completed by the end of 2018; most triggered by lead. While the focus is on remediation of residential soil and house dust, the program also includes a blood lead monitoring program with identification and abatement of additional sources of exposure for children with elevated blood lead levels (BLLs). As specified in the remediation program, studies are being conducted every 5 years to assess BLL data collected from Butte children. The first two studies have evaluated over 6,000 BLLs from 2003 through 2017 and evaluated trends over this time period, by Butte neighborhood, and as compared to areas outside of Butte. These studies showed that rates of elevated BLLs (i.e., those above 5 µg/dL) in Butte children have declined dramatically since 2002 but have been declining much more slowly since 2011. Improved rates of confirmation testing are needed to verify the rates of elevated BLLs. While the RMAP likely has contributed to these declines in BLLs the magnitude of impact cannot be quantified.

Mar 2, 2022

By D. S. Davies

Further development of the Nitric-Sulfuric Leach (NSL) process has led to an improved design of the leach and nitric acid recovery steps. NO produced in the leach step is reacted with oxygen, regenerating N02, which is sparged directly into the leach reactor. Leaching is simplified to two steps and the nitric acid plant is replaced with an oxidation recycle gas sys-tem. Laboratory work substantiated the concept and led to selection of operating conditions. The lab work also pointed to improved process control compared to use of nitric acid as the sole oxidant. Recovery of copper from purified pregnant liquor is modified to use air agitation electrowinning improving cathode quality and lowering tankhouse costs. Economic evaluation shows reduction of capital requirements from $2400/AT to $2000/AT in 1978 dollars for 50,000 TPY of copper production.

Jan 1, 1978

By M. Hepokoski, M. Klein, D. S. Yantek, L. Yan

Research by the U.S. National Institute for Occupational Safety and Health (NIOSH) has shown that heat/humidity buildup is a major concern within coal mine refuge alternatives. High temperature and humidity levels inside a refuge alternative may expose occupants to heat stress. Due to the safety risks associated with testing using human subjects, NIOSH partnered with ThermoAnalytics Inc. to create detailed thermal simulation models of refuge alternatives with human occupants. The objective of this effort was to predict a miner’s core temperature response and moisture loss in environments that may be encountered in a coal mine refuge alternative. These parameters were studied across a range of temperatures and relative humidity values to determine if the current 35 °C (95 °F) apparent temperature limit for refuge alternatives is reasonable. The results indicate that the apparent temperature limit is protective, provided that miners are supplied with sufficient water. The results also indicate that the body core temperature does not reach dangerous levels even at an apparent temperature of 54 °C (130 °F). However, the results show that moisture loss increases with apparent temperature. Therefore, if the apparent temperature limit were raised, the water provided in a refuge alternative would have to be increased to offset moisture loss.

Jan 1, 2017

By M. Hepokoski, M. Klein, D. S. Yantek, L. Yan

Research by the U.S. National Institute for Occupational Safety and Health (NIOSH) has shown that heat/humidity buildup is a major concern within coal mine refuge alternatives. High temperature and humidity levels inside a refuge alternative may expose occupants to heat stress. Due to the safety risks associated with testing using human subjects, NIOSH partnered with ThermoAnalytics Inc. to create detailed thermal simulation models of refuge alternatives with human occupants. The objective of this effort was to predict a miner’s core temperature response and moisture loss in environments that may be encountered in a coal mine refuge alternative. These parameters were studied across a range of temperatures and relative humidity values to determine if the current 35 °C (95 °F) apparent temperature limit for refuge alternatives is reasonable. The results indicate that the apparent temperature limit is protective, provided that miners are supplied with sufficient water. The results also indicate that the body core temperature does not reach dangerous levels even at an apparent temperature of 54 °C (130 °F). However, the results show that moisture loss increases with apparent temperature. Therefore, if the apparent temperature limit were raised, the water provided in a refuge alternative would have to be increased to offset moisture loss.

Jan 1, 2018

By Ross Goodman, Jesse Salai

The Ohio River Tunnel Project encountered multiple unexpected geotechnical challenges such as crown and invert instability due to the overstress condition affecting the strata above, below, and in the tunnel alignment during and after TBM excavation along with the potential for methane inflow. This paper showcases how the orientation of a tunnel alignment has a significant impact on how in-situ geological stress can impact the excavation of a tunnel from the contractor’s point of view and how geological features influence gas inflow to the alignment over time.

Jun 13, 2021

By Ibezim J. Anazia

Electrothermal production of elemental phosphorous (P4) generates substantial amounts of highly toxic phossy water and sludges. Because of their high phosphorous content and lack of reliable processing technology, large tonnages of these hazardous wastes have accumulated from current and past operations. To date, the sludges are stored in ponds or above ground in special containment vessels at various locations around the country. Two samples of electric furnace phosphorous sludge obtained from the Tennessee Valley Authority (TVA) in Muscle Shoals, Alabama and FMC Corporation in Pocatello, Idaho were investigated using physical separation techniques to recover the elemental phosphorous in the sludge and to render the residual material non-hazardous. The techniques tested include sizing, froth flotation and dispersed air oxidation. Flotation and sizing produced concentrates containing 69 -90% P4 with a recovery in the range of 60 -87%. Dispersed air oxidation of the fines and tailing products was effective in removal of an additional 10 -15% of the P4 in the sludge.

Jan 1, 1991

By Peter Zhang, I. BERK TULU, Morgan M. Sears, Heather Dougherty, Ted Klemetti, DYKE MARK VAN, Gabriel S. Esterhuizen

Ground falls in longwall gateroad entries remain a concern in modern longwall operations. The gateroads are subject to changing horizontal and vertical ground stress induced by longwall extraction. These stress changes can result in failure of the strata around an entry leading to large deformations of the entry roof, floor and ribs. The gateroad support systems are required to control the failed strata while maintaining safe access to the longwall face and unimpeded ventilation. This paper presents research conducted to better understand the stability issues in gateroad excavations and to develop procedures for evaluating support and layout alternatives for longwall gateroads. Using the results of a field-monitoring program and numerical model analysis of case histories, a conceptual model of gateroad support needs was developed. The conceptual model formed the basis for developing a set of equations that can be used to estimate likely roof sag and support loading for given roof geology and longwall-induced loading conditions. The developed equations were used to compare predicted gateroad stability to field study results, showing satisfactory agreement. The calculation procedures are used to demonstrate their application in assessing support alternatives at a case study mine. It is concluded that the developed analysis procedures provide realistic assessments of likely ground stability and can be used to evaluate alternative gateroad support systems at operating longwall mines.

By T. Harrison

Surface coal mines in West Virginia are receiving stringent NPDES discharge limits for total recoverable selenium. With limits in the low parts-per-billion range, selection and implementation of proper sample collection and analytical methods are imperative for quality assurance and control and for consistency in results. Given the typical oxidized form of selenium in the water, the low limits and the large and variable flow rates from the watersheds, end-of-pipe treatment is difficult and cost-prohibitive to implement. Discharge locations in the remote and steep terrain exacerbate the problem. To evaluate options for end-of-pipe treatment at a Patriot Coal Corporation surface mining operation in West Virginia, CH2M HILL performed wastewater characterization for a range of key constituents and selenium species at three outfalls for selection and preliminary sizing of appropriate treatment processes. A preliminary evaluation of base and wet-weather flows was done to understand flow variability considerations for discharges. A conceptual evaluation of technologies to treat selenium to permitted levels was conducted in con-junction with order-of-magnitude life-cycle cost estimates.

Jan 1, 2010

By C. J. Konya, A. Konya

"Presplitting is a form of blasting that when executed properly will create a smooth wall that will minimize secondary conditioning. In recent years, presplitting has become a popular technique to be used in both the mining and construction industry, however, presplitting fails on many occasions because of ‘geologic conditions’. This is typically because of improper explosive loads consisting of overloading and underloading blastholes. In this paper the authors introduce new factors such as a presplit factor which varies for different rock types, selection criteria for the spacing of presplits, the optimization of explosive load, as well as prediction methods for the environmental affects for the technique of Precision Presplitting. BACKGROUND Methods of controlled blasting in which a smooth, stable wall could be blasted have been an important consideration since blasting in mining and construction has begun. How can one use an explosive, with its massive energy and power, to break a non-homogenous rock without causing backbreak, poor walls, or deviations in the wall over large distances? The blasting industry has known for a long time that blasting ‘high benches’ would result in better walls and less backbreak. However, this was not a sufficiently controlled technique for critical projects, such as the Niagara Power Plant. This was one of the main challenges Hercules Powder faced when they began the project. In order to achieve this, they used a new tool in the explosive engineer’s toolkit, presplitting. The presplitting done on the Niagara Power Project utilized 1 ½” x 8” (38mm x 203mm) 40% gelatin dynamite in 2 ½” (63.5) diameter boreholes. This was done on multiple levels with benches between 12 feet to 52 feet (3.6m to 15.8m) with a total powder factor of 0.75 pounds/cubic yard (0.45 kg/m3). The spacing on these holes ranged between 18 inches to 24 inches (0.46m to 0.61m), center to center (Langfors & Kihlstrom, 1973). The strange aspect of this project was that this “lightly loaded” closely spaced row was fired before the production blast, yet this project produced some of the best walls seen at that time directly from blasting. In today’s blasting industry, presplitting is a more common way to produce smooth, stable high-walls for both the construction and the mining industry. Today, explosive loads for traditional presplitting is generally measured in pounds per foot (kilograms per meter) and typically ranges from 0.30 lb. /ft. to 0.5 lb. /ft. (0.45 kg/m to 0.75 kg/m). MECHANICS OF PRESPLITTING When analyzing a blasting process like the Niagara Project, many wonder how did that work when normally confining a charge would cause cratering and increased backbreak. Since then, presplitting mechanics have been studied extensively. It has been shown in many models that presplitting is not achieve through the collision of shockwave, but by gas pressure in the boreholes. In addition to models and finite element simulations, this has been proven full scale using Pyrodex, a propellant, to create a presplit plane with no shock wave present (Konya, Dean Barrett, & Smith Jr, Presplitting Granite Using Pyrodex, A Propellant, 1986)."

Jan 1, 2017

By Jack S. Watson, Rasika Nimkar, Robert M. Counce, Matthew Gordy, Patrick Zhang

Waste phosphatic clay presents a difficult disposal problem and a significant loss of P2O5. Recent developments make this study on the use of phosphatic clay as a feed material for H3PO4 production worthwhile. (a) New data from Florida Industrial and Phosphate Research Institute (FIPR) suggest that the Bclay^ waste can be effectively treated by improved solid separation coupled with flotation to produce feed material for recovering additional phosphate. (b) The use of BOLI Flowsheet^ provides capability to predict performance of aqueous-based processes for a range of possible operating conditions. Using the new FIPR data and BOLI Flowsheet^ enabled the design of a new process that can potentially extend the usefulness of current P2O5 ore deposits. Predictions using OLI Flowsheet were able to identify process conditions that effectively overcome the difficulty of high Mg content of phosphatic clay. Estimated manufacturing cost in the current study lead to valuation of the P2O5 content of the phosphatic clay recovered/utilized at 60 to 70% of that of the phosphate rock feed material currently used. Phosphatic clay should be considered as a valuable material that is currently given zero value. The new FIPR data and BOLI Flowsheet^ enables the design of a new process that can potentially extend the usefulness of current phosphate ore deposits by extending the fraction P2O5 of recovered

By Michael F. Gleason

In 1986, Gold Fields began negotiations with a large Nevada electrical power utility to supply power for its Chimney Creek Mine In northern Nevada. After the long negotiations reached an impass over various costs associated with the power line, a decision was made by Gold Fields to generate its own power. Self-generation is not uncommon overseas, but it is rare for any but very large or very small operations in the United States. Surprisingly, under certain conditions a mine can generate its own power profitably and Gold Fields has found that the associated operating and maintenance problems are minimal. The following report details what factors went into this decision and how it works. Hopefully, it can serve as a guideline for those who may find themselves in a similar position.

Jan 1, 1990

By W. T. Caneer

Uranium may be in short supply due to the predicted energy needs in the coming years. As a result of this a new surge of uranium exploration is underway. The refinement of numerous exploration techniques has accompanied this surge. One such technique is the monitoring of radon gas in surface soils and rocks as a guide to subsurface uranium deposits. The Colorado School of Mines Research Institute became involved in radon studies in 1967 on a project for the AEC. Since that time the Institute has conducted numerous radon surveys for a large number of companies which have been active in uranium exploration. The objective of this paper is to relate the techniques utilized by the Research Institute and the results of some of the studies performed. Most of the studies performed by the Research Institute were related to roll front, sandstone -type uranium deposits. However, we have performed radon studies in various other types of rock. For those who may not be familiar with the application of radon ?sniffing" in soils and rocks, a brief descriptive background should be given. The following question may be asked -- why use radon as a guide to uranium mineralization? Some of the answers to this question are as follows:

Jan 1, 1974

Automation and robotics are the keys to new intelligent autonomous mining systems which can remove operators from the hazardous and stressful mining environment and provide the tools for greater productivity. This pa-per presents the components necessary for a mining Intelligent Task Control System (ITCS) in dynamic unstructured mining environments. The proposed concept is applied to develop the ITCS for an autonomous excavator. The design and implementation of a fuzzy logic controller for an excavator that uses force/torque sensor feedback to complete excavation tasks is presented. Initial experimental results are also given.

Jan 1, 1994

Large deposits of eudialyte, a low grade zirconium bearing mineral, occur on the Southern Coast of Greenland in the Ilimaussaq intrusion. Various processes were tested in the laboratory to recover eudialyte from these ores, including flotation, leaching, gravity and magnetic separation. A combination of dry and wet magnetic separations has the advantage of simplicity and the least environmental impact for the location. This paper summarizes the results of laboratory testwork to develop a two-stage treatment process to recover the eudialyte by magnetic separation.

Jan 1, 1993

By M. S. Davis

The Tek Process can produce masonry products such as bricks, roof or wall tiles, and block from virtually any inorganic waste. In the process the aggregate raw materials, portland cement, water and common chemicals are first mixed together; then mechanically subjected to several thousand pound pressure per square inch. This causes a novel chemical reaction between the cement, chemicals and water; producing the "patented" Tek adhesive binder which holds the aggregate together in a stone-like mix. Simultaneously, the desired product shape is formed. The building modules can have strengths of 8000 p.s.i. (pounds per square inch) with completely sound aggregates utilizing air curing for a period of 28 days. With most aggregates, 3000 p.s.i. is achieved within 24 hours. Eventual strengths usually exceed 5000 p.s.i. with almost any raw material. Water absorption ranges from 5-7.5 percent. Both absorption and strength figures are superior to the most rigid of any and all A.S.T.M. specifications for the highest quality bricks. In most locations, the product (when brick shaped is called Tekbrik) can be produced significantly more economically than can comparable grades of clay or other bricks, be- cause almost any inorganic waste materials or pollutant can be used as a raw material. The process results in a lower manufacturing cost as compared to clay bricks; fuel cost to operate a clay kiln represents a substantial portion of the total cost. Capital expenditure for a Tek plant also is lower due to the large investment in clay kilns. Transportation savings also are important, clay brick factories must be very large because the kilns are uneconomical unless they are large. Most bricks are manufactured at the sites of clay deposits in relatively uninhabited areas. The cost of transportation to the job site represents a considerable percentage of the selling price.

Jan 1, 1974

By Randall Morris

After years of steadily declining employment and production, the U.S. coal industry is having a moment. In 2016, when Donald Trump was running for U.S. President, he cast a spotlight on coal mining in his campaign speeches, promising to end the “War on Coal.” Fast forward to 2025. On the first day of his second term, President Trump signed the National Energy Emergency Act, which emphasizes domestic energy production as a matter of national security and focuses on incentivizing domestic energy resources. Then on April 8, President Trump issued an executive order opening federal land to coal mining to reinvigorate “America’s beautiful clean coal industry.” As the nation seeks to identify reliable solutions to meet its ever-growing energy needs, the administration is going all in on proven, reliable and readily available natural resources, including coal. This means the coal industry is positioned to play a pivotal role in the administration’s stated energy policy, and highwall mining could be an integral factor in helping the industry optimize the extraction of ore to make the most of this moment. The White House noted in a statement that the United States’ “abundance of energy and natural resources … have historically powered our Nation’s economic prosperity” and vowed to remove regulations that have hindered developing these resources — regulations that resulted in job reductions and higher energy costs for U.S. consumers, while weakening national security. “There has been an increase in electricity prices in the United States of over 30 percent in the past four years,” said Rich Nolan, president and chief executive officer of the National Mining Association (NMA). “This administration wants to focus on that, inflation and on increasing electricity availability to help lower the price over time by incentivizing energy policy. Coal is definitely a high priority for this administration.” Part of the White House’s strategy is to facilitate investment in coal-fired plants. The shift comes at a time when the reliance of coal-powered energy plants has been waning. According to the U.S. Energy Information Administration, 7.5 GW of electrical capacity from coal-fired plants was retired in 2024, following the retirement of 22.3 GW of electric generating power the two years prior.

Jun 1, 2025

he leaching behavior of palladium in ammoniacal solutions has been investigated by using the rotating disk technique in an autoclave. The study included the effect of rotating speed, temperature, oxygen pressure, composition of ammoniacal solutions, and catalyst on the overall leaching rate. The dissolution of palladium in ammoniacal solutions was discussed in view of the thermodynamics and a kinetic model. Even though the potential-pH diagram suggests that palladium metal can dissolve in ammoniacal solutions at room temperature, it was found that the dissolution was too slow at temperatures below 100°C but was significantly improved at higher temperatures. It was also found that the rotating speed of palladium disk had no effect on the leaching rate. The apparent activation energy was found to be 69.7 kJ/mole. Based on the results obtained, it is concluded that the dissolution of palladium is controlled by chemical reaction.

Jan 1, 1997

By D. Marino

Over the last 20 years, the manufacturing sector of our country has been called upon to comply with ever core stringent environmental standards. The primary metals sector was particularly hard hit early on, to develop the technology, acquire the equipment, and implement the programs to eliminate or reduce the by-products of metal making. To this end, through a combination of technological innovation and extensive capital expenditures, the metals industry has met, and in many cases, exceeded the minimum standards. It is to this escalating cost - liability exposure issue - that Dereco has addressed itself. As we move into the decade of the 90's, the challenge facing the metals industry concerning the environment will be even more difficult than the previous decade. To focus in on one major aspect of legislated environmental regulations, the issue we will address today is; now that the by-products of metal production have been identified, accounted for and collected, how are they to be disposed of? During the course of this presentation, actual data will be presented from our 4 1/4 year on-site experience at J & L Specialty Products

Jan 1, 1992