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By M. J. Fairweather, J. R. Egan, W. A. Meekel

Cominco Metals, in cooperation with two Canadian Universities and the Government of Canada, is developing applications for column flotation in the treatment of lead and zinc ores. Plant scale results at Polaris and pilot plant studies of Sullivan, Pine Point and Red Dog ores show column flotation to have significant advantages over conventional mechanical flotation for lead and zinc cleaning. Results from these ongoing studies are discussed in relation to ore texture, mineral recovery, impurity behaviour, scale-up and control.

Jan 1, 1988

Researchers from the National Institute for Occupational Safety and Health (NIOSH) are developing a coal pillar rib rating (CPRR) technique to measure the integrity of coal ribs. The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs. The CPRR utilizes four parameters: rib homogeneity, bedding condition, face cleat orientation with respect to entry direction, and rib height. All these parameters are measurable in the field. A rib data collecting procedure and a simple sheet to calculate the CPRR were developed.

Jan 7, 2020

By C. E. Brechtel

Bench cut-and-fill stopes with heights between 85 and 105 ft are being excavated in the lower levels of the B-NEATH Zone. Estimates of pillar strength and pillar loading indicated a high probability of pillar failure. Some changes in mining practice were made to minimize impacts of pillar failure and a rock mechanics instrumentation program was employed to monitor stability during mining of the first stopes. Limited pillar failure, in the form of destressing, was observed in the initial stopes; however, global stability during mining was good. Instrumentation data indicated that predictions of pillar strength and stress were quite close to field results.

Jan 1, 1989

The dissolution kinetics of cobalt in iodine/iodide solutions was investigated using a rotating disc technique. Variables studied here included temperature, rotating speed, concentration of lixiviants, and pH of the solution. The overall dissolution reaction was found to be limited by mass transfer of tri-iodide through the diffusion boundary layer with Arrhenius activation energy of less than 16.2 kJ/mol (4 kcal/mol) over the temperature range, 2-42°C. The pH of the solution had little effect as long as the pH of the solution was less than 8. However, when the pH of the solution became greater than 8, the dissolution rate decreased dramatically due to passivation. The rate of dissolution was in good agreement with the dissolution model developed by the authors earlier.

Jan 1, 1994

By D. Malhotra

Metallurgists are continuously striving to improve recovery. But optimization of profits and/or revenue dictates that recovery can be sacrificed at the expense of throughput. However, recently there has been significant interest in the concept of retreatment of tailings to enhance recovery and hence revenue while maintaining high throughput. The authors discuss the technical and economic factors that need to be considered in evaluation of the feasibility of retreatment of tailings including the potential feed streams (i.e., rougher tailings, cleaner tailings, etc.) and processing options (i.e., physical beneficiation, chemical processing, etc.). A case study for base metals is discussed.

Jan 1, 1994

By David N. Hedges

This paper discusses the actual recovery and installation of a longwall in a bituminous coal mine in Western Pennsylvania. The coal bed mined is in the Lower Freeport seam which averages 42 inches (1.07m) in height locally. Drainage from the mine is approximately 3.5 million gallons of water per day (13.25 million liters per day). This water deteriorates the mines predominately fire clay bottom making it extremely difficult to move equipment. Support removal is accomplished by pulling the 6 ton (5443 kg) shields out under their own hydraulic power and transporting them by track over four miles (6437m) co the next longwall panel. This paper also discusses the changes that will be made to aid in the succeeding longwall recoveries and installations.

Jan 1, 1984

By D. McSwain-Santos

Soda ash is the trade name for sodium carbonate, a chemical refined from the mineral trona or naturally occurring sodium carbonate-bearing brines (both referred to as natural soda ash) or manufactured from one of several chemical processes (referred to as synthetic soda ash). It is an essential raw material in glass, chemicals, detergents and other important industrial products. Production U.S. soda ash production during 2004 increased to10.9 million Mt (12 million st). Five companies comprised the domestic soda ash industry. Four were in Wyoming operating five plants. One was in California with one plant.

Jan 1, 2005

By Taghi Sherizadeh, Paul Brooks, Dogukan Guner, Samuel Nowak

Large excavations are well known to result in rock mass deformations which can present challenging situations for mine personnel. Most of the currently available ground movement monitoring devices fail to adequately provide mine operators with highly accurate and meaningful insights into rock mass deformation or displacement. The use of distributed fiber optic sensors (DFOS) in industries such as oil and gas and civil engineering has shown the potential of these sensors to deliver real-time, highly accurate, and long-range distributed strain measurements with great success. However, the use of these sensors in underground mining is limited to a few case studies.

By Gerald M. Ellis

ntroduction As the gold mining industry continues to develop in the Dominican Republic and Haiti, more deposits will undoubtedly be discovered that will be amenable to development. The Pueblo Viejo gold mine is currently in operation in the Dominican Republic. It has become an important component of that country's economy. Pueblo Viejo output is important to the government as a foreign currency earner. It is also said to be among the world's more successful gold mines. But, while Pueblo Viejo is successful, no other major gold discoveries have been made in recent years. Therefore, alluvial deposits of gold have caught the attention of geologists on the Island of Hispaniola. In the past four years, exploration and investigation of alluvial deposits have been initiated in both the Dominican Republic and Haiti. This type of activity is expected to continue over the next few years. Alluvial gold mining is rudimentary gold washing, done mostly by farmers. It is an old tradition, dating back at least 100 years, and is done by small, independent, or community farming villages in the mountains and plains of the Dominican Republic. Investigations in the DR Recently, alluvial gold investigations have been undertaken in well known locations of the Dominican Republic. One is in the Villa Altagracia area. Here, the terraces and gravels of the Haina River basin were examined, test-pitted, and assayed by Minera Altagracia, a local Dominican mining group. Results led to a new investigation by the state-owned Rosario Dominicana (RD), the company that mines the gold at Pueblo Viejo. Rosario tested areas previously investigated by Minera Altagracia. RD could not define the type of concentration that could justify an industrial-scale type of exploitation. The Haina River placers are located in the flats and valleys of Central Dominican Republic. They are classified as small-scale type of operations where local cooperatives can do the traditional gold washing. It is not now considered a dredgable project for a mining company. The next alluvial gold investigation was undertaken by the Dominican Department of Mines and others in an area of some 700 km2 (270 sq miles) in the northeast near Miches. Farmers have been washing gold in streams and excavating pits in various areas, particularly La Mina and have made a living. Government geologists panned several hundred streams and river tributaries. They also washed material from deep excavations. The results, however, were negative insofar as locating alluvial gold concentrations suitable for large-scale or industrial-scale exploitation. The most favorable locations were the terraces along the Jayán and Cuarón Rivers in the area of Miches. But the grade od concentration is poor. Actually, only traces of gold were found in these

Jan 8, 1986

By Fred W. Shultz

In the past we have been somewhat harrassed by the terms "'quality control" and "process control". This is especially true where the industry is dependent upon the chemical analysis of their product which in turn informs them how, well they have been controlling the process. The information which they have received, in most cases, is of an historical nature rather than of current value. The word "control" is to have more significance in future operations. This is particularly true in the metals industry. As the industry continues to process lower grade ores, and processing costs continue to rise, they must obtain more information faster to exercise "control" to its fullest extent.

Jan 1, 1963

By D. R. Wilburn

This summary of international mineral exploration activities for the year 2007 draws upon available information from industry, literature and U.S. Geological Survey (USGS) specialists. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry and presents analysis of the mineral industry based upon these data. Two types of information are reported and analyzed in this annual review of international exploration for the year 2007: 1) budgetary statistics expressed in U.S. nominal dollars provided by Metals Economics Group (MEG) of Halifax, Nova Scotia, and 2) information on regional and site-specific exploration activities that took place in 2007 and compiled by the USGS.

Jan 1, 2008

By J. A. Siekmeier

The thickness of the laminated beam modeled in this study is based on bridging potential and TDR measurements. The laminated beam stiffness is based on the effective stiffness of an equivalent transformed section. The maximum deflection of this near-surface laminated beam is compared with the maximum measured surface subsidence. The spreadsheet provides a rational technique to graphically display the character of the overburden and potentially allows prediction of a subsidence factor based on boring logs and the proposed mine plan. The U.S. Department of the Interior, Bureau of Mines (Bureau), utilizes a commercially available computer spreadsheet program in combination with a modified version of Bieniawski's Rock Mass Rating (RMR) system to characterize the geology overlying high extraction coal mines. The spreadsheet program calculates a RMR for each bed based on the lithology, thickness, and engineering properties, which are determined from boring logs and laboratory tests. Once the RMR is calculated the spreadsheet has two major functions. First, the spreadsheet calculates values used to graphically represent the character of each individual bed in the overburden. It calculates an in situ deformation modulus using an empirical rela¬tionship between the modulus and the RMR and then uses this effective modulus along with additional parameters that are based on mine geometry to calculate the bending stiffness and bridging potential for each bed. Second, the spreadsheet creates a transformed section that allows groups of beds to be modeled as an elastic beam. It then calculates a bridging potential for the entire rock mass. The bridging potential of the rock mass is a single value that takes into account both the geology of the overburden and the geometry of the mine. It seems reasonable that there would be a strong correlation between the bridging potential, the overburden response to high extraction mining, and the subsidence ratio. The results presented in this paper focus on the relationship between the bridging potential of individual beds and the deformation measured using Time Domain Reflectometry (TOR). Subsurface displacements measured over seven high extraction coal mines in southern Illinois were correlated with the bed stiffness and bridging potential profiles. Based on these correlations it was evident that the process of caving and subsidence over these high extraction mines involved momentary bridging by individual beds or groups of beds and the ultimate development of a laminated beam near the surface.

Jan 1, 1986

Many of the deeper ore reserves in current gold operations as well as new gold deposits consist of refractory ore types. As process development for these mineralizations remains time-consuming and costly, minimization of exploratory testwork and the early identification of feasible process routes is critical. Since most of the processing parameters are related to the mineralogy of the ore (Marsden & House, 1992), thorough mineralogical analyses during exploration and development phases have become a technical and economical requirement. The determination of mineralogy-related processing parameters and especially the gold mineralogy is even more important for these ore types because refractory gold ores consist of many transitions from partially leachable to totally refractory. In addition to sulfide and gangue encapsulation, various other refractory conditions may exist. Together with accessory mineralogical detriments (e.g., alteration/ slimes, reagent consumers, scale formation, mineral preg robbing) they may complicate process selection and hamper optimal plant operation.

Jan 1, 1993

By S. Dessureault, Z. Gavelan

As globalization continues, sustainability and social responsibility has become essential in foreign mining investment. However this global trend and the increasing acceptability toward the globalization process, viability and sustainability are not always achieved. Viability and sustainability of mineral projects is dependant on the social and political environment of the region where the mining venture is located and is based on the interaction between the mining entrepreneurs, national-local government representatives, communities, grass-roots groups and independent civil organizations. These are the organizations, which play the acting roles on the viability of mining projects and are the main source of socio-political risks for the project. Throughout the decision-making process to invest in a mineral project, socio-political risks are quantified using a set of measurable variables. Nevertheless, these risk measures should be dependent on specific industries. Two mineral projects, even in the same mining district, may have significantly different political risk profiles based on their own socio-political variables. This paper describes a methodology that takes into account local social and political variables in defining a project-specific’s political risk profile. This contrasts with more typical political risk measures that focus on the country’s overall risk profile. Mining operations must operate on a local scale necessitating the development measure that considers more local variables.

Jan 1, 2004

By Dr. Peter J. Conroy

The current study is part of the U.S. Department of Energy's (DOE) on-going subsidence research program. The long-term objective of the DOE program is to develop analytical methods of subsidence prediction applicable over a broad range of geologic and mining conditions encountered in the United States. The DOE currently has several contracts in progress to develop a sound data base that can be used in the development of predictive models. Dames & Moore is currently under contract to the DOE to collect and analyze detailed subsidence and hydrologic data from a coal mine employing longwall mining methods in the Eastern Coal Province. Work under Contract No. DE-AC22-80PC 30335 began in October of 1980 and will continue through September of 1984. This paper summarizes the work that has been completed through September of 1981 and presents the results that have been achieved during this period. Technical difficulties encountered during both the installation and monitoring phases are discussed, and recommendations for future work are presented.

Jan 1, 1982

By R. K. Singhal

The underground coal mining systems have kept pace with the developments that have occurred in other types of mining industry. A diversified group of machines with high horsepower motors, built-in microprocessor technology and with numerous options to satisfy the miners need in a varying geological environment are now available. A brief review of this existing technology and its likely status within the next 21 years is presented. Discussed also are some of the on-going advanced developments in electronic mechanization, remote control and automation together with mine wide data monitoring and management systems and facilities to process and transmit data to remote computerized stations.

Jan 1, 1989

By D. W. Fuerstenau

One of the more energy-efficient methods for size reduction, namely particle-bed comminution under high compressive loads, was employed to grind eight minerals and ores, using up to 250 MPa pressure. A new approach based on the self-preserving character of the ground product size distributions and a linear energy-reduction ratio relationship is proposed for analyzing this mode of size reduction. The grind ability of the material when comminuted in a particle bed is about one-half that of the single-particle crushing mode, which is in agreement with previous estimates of the relative efficiencies of energy utilization based on direct measurements of surface area produced. The loss of efficiency may be attributed to energy dissipation by particle interaction phenomena in compressed beds.

Jan 1, 1993

By Ibrahim S. Balbaa, J. Terry Strack, James G. Hopkins

A microwave system for continuously reactivating carbon, used in gold processing, has been demonstrated at a gold mine in Ontario, Canada. The pilot unit produced reactivated carbon at a rate of 12 kg/h. Comparisons with the mine's existing reacti­vation kiln indicate that microwave reactivation technology has several clear advantages over conventional regeneration kilns. Upon completion of the original study, the microwave reacti­vation technology was further developed. An advanced rotary type microwave system that can be scaled up to reactivate car­bon at a rate of 120 kg/hr was designed and smaller pilot-scale equipment was commissioned and tested. Under an agreement with OHT, Harper International Corporation will manufacture, supply, and market the new technology. In addition to carbon reactivation, the rotary microwave system can be used in many other heating applications such as ore treatment, ceramic pro­cessing, and cleaning of minerals.

Jan 1, 1998

"With a longstanding reputation for engineering expertise, Weir Minerals continually develops solutions and technology to better serve the mining industry. Recognizing that throatbush wear rate has a major impact on the overall efficiency of slurry pumps, Weir Minerals has developed superior rotating and axial adjustment technology.In many applications, the pump’s throatbush is the component that has the shortest life compared to the impeller and liners, with considerable variability.Adjusting the gap between the throatbush and the impeller front shroud reduces hydraulic recirculation in the pump. This prevents localized wear on the throatbush, improves hydraulic efficiency and lowers the total ownership cost for the operator. To avoid impacting the plant’s production, these adjustments are often performed while the pump is operating. However, this can have safety implications for individuals working at the front of the pump unit.“Manually adjusting an alloy throatbush on a large pump requires several people and is laborintensive. It requires mechanical tools to adjust the four pusher bolts, one at a time, in order to reduce the gap between the throatbush and impeller. We wanted to find a safer and quicker way to extend the wear life of the pump with regular adjustments, which led us to development of this technology,” said Marcus Lane, global product manager for centrifugal pumps for Weir Minerals.“Our automated throatbush adjustment solutions are available for pumps fitted with either rubber or alloy throatbushes on Warman slurry pumps used in the most arduous applications, and have been designed with our customers’ safety and pump operation in mind. By mechanizing the adjustment procedure, personnel are removed from the line of fire, and the accuracy of axial movement is increased,” said Ron Bourgeois, director of slurry pumping technology group for Weir Minerals."

Mar 1, 2019

By Nikhil Dhawan, SHAILA MIR

Consumer preference for ever-higher laptop performance coupled with laptops’ declining lifespans make them a significant contributor to electronic waste. An in-depth evaluation of elemental composition and distribution is important for determining metal recovery potential and sustainable recovery processes. In this work, the characterization of individual components of laptops is studied for the systematic identification of important elements and for streamlined and structured recycling, to reduce processing steps and improve economics. A process flowsheet highlighting various recycling routes by targeting metals and various components is also proposed.