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By S. Chander

The results of an investigation to characterize the chalcopyrite/solution interface are presented. Several techniques including galvanostatic and steady state polarization, cyclic voltammetry and impedance spectroscopy were used. The results show that the dissolution of chalcopyrite is incongruent. Initially, at low potentials(<O.34V), iron species are released which give rise to the growth of an iron-deficient sulfide (IDS) layer. The dissolved iron might reprecipitate as a hydroxide layer depending on solution composition. Continued oxidation involves diffusion of species through the product layer. At higher potentials (>O.48V) further oxidation leads to dissolution of copper and sulfur species with a resultant breakdown of the IDS layer. The changes in properties of surface coatings resulting from various electrochemical treatments are discussed.

Jan 1, 1991

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"Duluth & Iron Range Railroad. The Duluth & Iron Range Railroad was built from Two Harbors to the Vermilion range at Tower, a distance of 67.6 miles, in 1884, and extended to Ely, twenty-one miles east of Tower, in 1888. It was built into Duluth in 1886, and branches were extended from its main line to the Mesabi mines in 1892 and 1893. The original grades on this road are very steep, going north, and in the thirteen miles from Two Harbors to Highland there is a rise of 1,150 feet. A new line between these points has been built with an increase of three miles in distance and with maximum grades of 1 per cent. Duluth, Missabe & Northern Railway. The Duluth, Mis¬sabe & Northern Railway was constructed from Stony Brook to Mountain Iron, a distance of 48.62 miles, in 1892. The Biwabik branch from Iron Junction to Biwabik, a distance of 15.54 miles, was constructed in 1892. The Superior branch from Wolf to Hibbing, a distance of 16.06 miles, was co11structed in 1893. The Alborn branch from Coleraine Junction to Coleraine, a distance of 53 miles, was constructed in 1906. The total main line mileage is 242 miles, of which 82 miles from Duluth to Hibbing is double tracked"

Jan 1, 1920

By J. W. Gunnett

Abstract. The Surface Mining Control and Reclamation Act of 1977 (PL-95-87), Section 522, establishes requirements for state regulatory authorities to designate lands unsuitable for all or certain types of surface coal mining. Any party having an interest in an area that may be affected can petition for it to be designated unsuitable for mining. Section 522 could present major obstacles to the mining industry by typing up an area in an endless round of petitions. The program under development for Kentucky is examined and analyzed as an example for determining the hidden impacts of Section 522.

Jan 1, 1980

By C. Flores

The most common experimental approach of studying one variable at a time while holding all others constant is extremely inefficient. Use of statistical methods enables engineers and scientists to obtain meaningful information with the fewest experiments, reducing cost and wasted effort. In particular, the Taguchi method can be more efficient than traditional full factorial experiment designs, as it can study more variables with fewer nuts, and it is more robust against process "noise." Taguchi designs are also simple to formulate and the results can be analyzed by simple PC spreadsheets. The role and benefits of using the Taguchi method in experiments to develop and optimize processes is discussed.

Jan 1, 1998

By S. K. Nicol

The results of column flotation tests conducted on a bulk sample of ultrafines discarded from the fine coal desliming cyclones at the Riverside coal preparation plant of Theiss Dampier Mitsui Coal Limited are presented. A 9% ash concentrate was obtained from a 51% ash ultrafine feed at 75-80% recovery of combustibles in a single stage of column flotation. From this result it is predicted that installation of column flotation at Riverside would lead to the annual recovery of additional coal worth $US5.1M. The operating conditions for coal and copper column flotation are compared and some differences which may result in a variation in column design are noted.

Jan 1, 1987

By Ben W. Burdett

Since the late 19701s, the use of microcomputers in the minerals industry has grown to the point where today they can be found in virtually every plant within the industry. Their use in every aspect of instrumentation and control has increased the ease of operation and control of every phase of mineral processing. Their incorporation in sensors, transmitters, indicators, and controllers in addition to their use in distributed control and computer systems has provided operators with more timely accurate information than they have ever had before. This has led to an increase in the operator&apos;s effectiveness and an improvement in overall productivity. The ultimate aim of plant control is to maximize recovery in the mineral processing operation, and the microcomputer has spawned many tools that are now making this goal attainable. This paper discusses individual use of microcomputers in the areas previously mentioned as well as their collective use in overall control systems. The incorporation of local control systems in total plant control including the communication of information throughout all levels of plant management is also discussed. Finally the role the microcomputer is playing in today&apos;s plants is illustrated with numerous references to current examples.

Jan 1, 1985

By G. Kemp Williams, Peter H. Dohms, Barry A. Hillman, Laurie A. Williams

Introduction In 1969, the US devalued the dollar. This action, over the ensuing four years, resulted in the deregulation of the price of gold. It also resulted in the rebirth of the US gold mining industry. The extreme inflation of the 1970s led to a dramatic increase in the price of precious metals. Consequently an increased interest in the exploration for and mining of gold has occurred. The enthusiasm began among the few existing producers who had survived on marginal profits during a prolonged period of fixed prices and constantly rising costs. Then came the newcomers. They saw the opportunity to enter an industry that historically had been characterized by small operations with low capital costs. It was not until the late 1970s that large mining companies recognized that investment in gold projects could generate cash flows that previously were associated only with world class deposits. Today, gold mining has tremendous appeal for the entire mining community, despite the dramatic price drop from 1980-81 levels. There are even major firms with no mining experience attempting to gain a foothold. But how easy is it to enter the US gold mining industry? What are the basic factors that influence the economics, and what are they likely to be for the remainder of the decade? How has the industry changed, and what is the composition of the active companies? An examination of the industry will help to answer these questions. US Gold Mining History The current gold rush is actually the fifth in the 208-year history of the US. The first recorded commercial mining of gold occurred in the Southeast in 1799. It produced from small, yet relatively rich placer deposits. The famous California gold rush of 1848 placed the US as a major producer with 62.2 t (2 million oz) of output by 1850. More than 93.3 t (3 million oz) was mined by 1853, equivalent to 63% of world production. But the richest placers were soon depleted. By the end of the Civil War, annual production had declined to well below 62.2 t (2 million oz). The government then relaxed prices and the industry again began to recover. The 1870-80s saw the great mines of the California Mother Lode and Grass Valley brought into production. This was followed by development of Nevada&apos;s Comstock, which later became one of the world&apos;s largest producers. Discovery of gold at Cripple Creek in 1892, coupled with technological advances in the use of large dredges in the California placers, resulted in significant production increases. And, with the expansion of the Homestake mine at Lead, SD, in 1898, US output again surpassed the 93.3-t (3 million-oz) level. By 1905, produc¬tion climbed to 124.4 t (4 million oz) with the addition of the Alaskan deposits, new output at Goldfields, NV, and the introduction of the cyanidation process. During World War I, the government forced the shutdown of gold mines. By 1920, total production had dropped to little more than 62.2 t (2 million oz). Many mines remained closed until the Great Depression. This, combined with the devaluation of the US dollar in 1934, resulted in a gold price increase to about $1.13/g ($35 per oz). Then began the fourth gold rush. By 1937, output had again surpassed 124.4 t (4 million oz). This was due to an increase in primary production and new byproduct production from base metal operations. Unlike the previous period of growth, however, this period was short-lived. The imposition of Executive Order L-208 in 1942 once again forced the shutdown of most mines. At the end of World War II, cumulative US gold production had

Jan 12, 1984

By W. J. Dolinar, S. P. Sandoval

The US Bureau of Mines (USBM) implemented the Fe2+/ Fe3+-SO2 anode reaction in a Cu-electrowinning cell with full-size electrodes. Electrowinning was conducted using industrial electrolyte at 258 A/ m2 (24 A/ft2) and 40°C. Manifold injection of electrolyte provided circulation between the electrodes. Five-day operation using an optimized manifold gave an average cell voltage of 0.94 V at 89% current efficiency, which amounted to an energy savings of 2.82 MJ/kg (0.355 kW-hr/lb), compared to conventional electrowinning. Acid milling 5was completely eliminated, and the SO2 concentration 23 cm (9 in.) above the cell averaged 0.06 ppm.

Jan 1, 1996

By Ehsan Alavi, Sanjeer Yogendran, Savreet Singh

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto extends approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. This project includes the installation of five intake shafts connected by 10.5 km of 6.3 m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20 m in diameter and 52 m deep), significant volumes of free phase oil and hydrocarbons were encountered. Due to the heavy inflows of the contaminants, excavation was stopped at the transition depth. The initial support of excavation needed to be redesigned, shaft had to be backfilled with CDF and installation of deeper secant piles are in progress to cut off contaminants. This paper outlines the initial plan for excavation as well as the design changes to the plan. The current status of the shaft excavation and lessons learned will be discussed.

Jun 13, 2021

By William F. Stowasser

The organization and operations of the information gathering system, and examples of the products prepared for the commodity phosphate rock by the Division of Nonmetallic Minerals, U.S. Bureau of Mines, are used to describe the Bureau&apos;s commodity program. Selected examples from publications about phosphate rock are used to illustrate the program. The Commodity Divisions reporting to the Office of the Assistant Director-¬Metals, Minerals and Materials, have the responsibility in the Bureau of Mines to maintain commodity records, understand the present supply and demand status of the commodity, and forecast future supply, demand, and problems. Within the Divisions, commodity specialists have the broad charter of acquiring as much information about a commodity as is necessary to characterize its history, current status, and future. This information and understanding are the base for the development of mineral policies. To accomplish these objectives, the commodity specialists acquire data and information about each commodity and produce a number of standard publications each year. In addition, as circumstances dictate, each specialist will prepare or participate in the preparation of special documents for specific purposes or problems associated with his commodity. In the preparation of reports and publi¬cations, he may communicate with industrial organizations and other Government agencies.

Jan 1, 1975

By G. C. Allen

Selective flocculation is used for the purification of clay minerals. Here we present data from a surface spectroscopic investigation into the polyacrylamides mediated selective flocculation of kaolin from an impure matrix. Use of X-ray photoelectron spectroscopy (XPS) was shown to offer a useful approach for investigating the observed selective separations. In particular, a new small area XPS technique was used to characterize, in situ, the differential competitive, f1occulant adsorption onto mixed kaolin/gangue systems.

Jan 1, 1998

By David E. Thompson, Daniel J. Dobbels

INTRODUCTION The planning process for projects requiring construction of tunnels in urban environments can be highly complex and involves interaction with professionals of many disciplines. Typically the initial step in the planning process is to establish basic design criteria for the tunnel or tunnel system consistent with its intended purpose. Such criteria might include acceptable tunnel geometry, minimum and maximum slope or other associated criteria. Ideally, once the basic criteria have been established, the next step in the process might include establishing technically feasible horizontal and vertical alignment and shaft siting alternatives and developing "ball park" construction and operational cost estimates for the alternatives. Comparisons can then be made regarding the relative technical and economic merits of the alternatives and the most favorable alignment(s) are selected for further study or preliminary design. Typically the last and perhaps the most important task that is conducted during the planning stage includes identifying issues and potential problems to be addressed during the design and construction stages of the project. Many issues warrant consideration during the planning phase of a tunneling project. For the purposes of this paper, these issues can be divided into two broad categories: technical and non-technical. Important technical issues include, among others, general design criteria, geotechnical and geoenvironmental issues, and constructibility issues. Important non-technical issues include, among others, right-of-way and easement related considerations, project scheduling constraints, both short and long term environmental impacts and overall cost/benefit aspects of the project. With respect to influence on the planning process, these two groups of issues often cannot be separated completely. For urban tunneling projects, however, it is most often the case that the non-technical

Jan 1, 1991

By Y. C. Lo

This paper presents the development of ultrasonic grinding technology for material and mineral processing. The principles underlying this new technology, as well as their implementation in two laboratory scale devices are described in detail. Ultrasonic grinding experiment results are discussed with respect to operating variables and the achieved product sizes. Special attention has been given to the electrical energy consumption of the grinder, and an attempt to compare its efficiency with tumbling mills has been made. A mechanical system capable of measuring the specific grinding energy is also described.

Jan 1, 1991

By Jr. Gambrell

For more cost effective strata control, a fundamental understanding of the behavior of the support system is needed. To assist in this understanding for shield supports, behavior of a four-leg shield design used on a soft floor in an operating longwall system is presented. The shield was constructed having a split base and a split caving shield. Attention is focused on other-than-normal loading on the canopy and its effect on deformation of the lemniscate links. Examples of the typical bending and twisting deformations are given. Schematics of the canopy, caving shield, and lemniscates showing important forces and moments are presented. Approximate minimum values of the forces and moments are calculated. The need for use of more inclusive three-dimensional design techniques is demonstrated.

Jan 1, 1990

By M. Kaya

This paper presents an experimental method to determine the degree of gangue entrainment in mechanical flotation cells and proposes new and inexpensive methods to lessen it. The applicability of froth washing and vibration was studied in laboratory, pilot plant, and plant scales. The effect of wash water on metallurgical performance was tested with various streams from the Falconbridge Strathcona mill at laboratory, pilot, and plant scales, with the 2nd cleaner at the Eastmaque Kirkland Lake mill, and with the 2nd and 3rd zinc and 3rd and 4th copper cleaners at Les Mines Selbaie mill. It was found that gangue recovery was closely related to water recovery in all systems. Wash water at an optimum superficial rate from 0.03 to 0.07 cm/s reduced entrainment by anywhere from 30X to 70X. Wash water can be further assisted by mechanical and ultrasonic vibration of the froth. A further rejection of 10 to 20X becomes possible. As a result of this work, a number of plants in Canada and in the United States have evaluated and/or are now using froth washing.

Jan 1, 1990

By K. F. Unrug

Fractures of sedimentary rocks in the vicinity of the outcrop are commonly encountered around the world. Mine highwalls and numerous highway cuts give excellent views for detailed study of surface fractures. This paper gives an explanation of the origin of fractures as well as characterization of the distribution and extent of joint system with reference to lithologic composition of the rocks. Practical implications of the joint system affecting mine operations are described. Among the subjects discussed are: discontinuous deformation as an effect of surface subsidence, stability of mine portals and near outcrop underground operations, and stability of highwalls, when using highwall miners and strip operations. Some design procedures are recommended that can minimize the problems encountered in mining areas with intense joint systems.

Jan 1, 1994

By Lawrence Tsang, Conrad Ng, Tim Leung, Peter Poon

"The Mined Tunnel is part of the Central-Wan Chai Bypass and Island Eastern Corridor Link (CWB), which is a strategic road along the northshore of Hong Kong Island targeted to alleviate the heavy traffic congestion. The objective of this paper is to review the performance of construction of a 160m long Mined Tunnel with a trinocular cross-section area of 460m3 and a combined span of about 50m underneath the southern approach ramp of the existing Cross Harbour Tunnel (CHT) by sequential excavation method (SEM) in hard rock. Mechanical excavation of tunnel by adopting the New Austrian Tunnelling Method (NATM), together with the application of NGI Q-system allows observational approach and optimization of temporary rock support design. Furthermore, the good performance of optimized rock support and the stability of CHT are confirmed through instrumentation monitoring review. This paper also discusses the selection of different tunnel plant and equipment to achieve the planned rates of tunnelling by mechanical excavation in competent granitic rock. INTRODUCTION The works of the CWB mainly comprise construction of 4.5km dual three-lane trunk road, of which a 3.7km section is a tunnel connecting Rumsey Street Flyover in Central to Island Eastern Corridor at North Point (see Figure 1). The Mined Tunnel runs from the ex-Public Cargo Working Area (ex-PCWA), underneath the existing CHT, and through the Causeway Bay Typhoon Shelter. The Mined Tunnel passes at an oblique angle beneath the southern portal of CHT over a length of some 50m. CHT is the primary sensitive receiver of this project and is utilized with a daily throughput of about 120,000 vehicles that far exceeds the design capacity of 78,000 vehicles per day. Hence it is necessary to choose the most appropriate tunnelling method to preserve the structural integrity of the CHT. Other sensitive receivers in the vicinity include structures to the north of the Mined Tunnel, the Royal Hong Kong Yacht Club (RHKYC); and to the south of the Mined Tunnel, the Police Officers’ Club (POC)."

Jan 1, 2016

By M. S. Klima

A 25-mm diameter dense-medium cyclone was tested to investigate the effects of geometry and operating conditions on cyclone performance when processing -150 I&apos;m coal. The emphasis was on examining those variables (e.g., flow rate and inlet velocity) which impact the separation kinetics (specifically the number of g&apos;s and the mean retention time) and the occurrence of apparent bypass. Apparent bypass, indicated by partition curve "tails", results from the short circuiting of the feed coal to one or both of the product streams and represents a loss and/or contamination of the clean coal. This paper presents the results for this series of tests.

Jan 1, 1993

By T. Stack, C. Roos, M. Drake, P. Conrad

"This paper presents the evaluation Montana Tech completed for the Western Energy Company Rosebud Mine relating to the benefits of survey data collected using novel technologies over traditional methods for topographic surveys. These technologies include Unmanned Aircraft Systems (UAS), photogrammetry, and laser scanning/LIDAR. Utilizing these technologies, large areas such as reclamation areas and cast blasts can be surveyed in a timely manner for use by the mining operation. The areas that were evaluated were the improvements in the safety of employees and the time required to collect data. In addition, there is also a potential cost savings for the operation, all while not affecting the accuracy of the data that is collected. PROJECT BACKGROUND Accurate topographic survey data is critical to successful surface mining operations. It is used for mine planning and design as well as permit compliance. Currently, employees typically collect survey data using GPS equipment or total stations. These methods can be dangerous, as they require employees to work near large operating mobile equipment, edge of high walls, and on piles of stacked steep-sloped loose material. Aerial and satellite photographs, performed by a contractor, can be used to obtain some of this information, but it is expensive and may not be attainable during overcast conditions. Montana Tech, along with the Rosebud Mine, conducted research on the accuracy, cost, and other benefits of survey data collected using novel technologies. Some of the methods studied include, but are not limited to, Unmanned Aerial Systems (UAS) or Vehicles (UAV), photogrammetry, and laser scanning. These methods were evaluated to determine if these technologies provide mining companies with a safer, cost effective, and accurate method to collect data for surface mining operations. The project scope was to evaluate various surveying techniques to determine which techniques would be applicable for the Rosebud Mine and complete a trade-off study comparing the new techniques with currently used methods. The trade-off study included an analysis of the technological differences between the methods, safety and legal considerations for the new techniques, operational limits, and the costs associated with each technique. Working with the Rosebud Mine team, techniques were selected for field trial and accuracy comparison. This paper presents a literature review of applicable technical papers and a summary of the Federal Aviation Administration regulations for UAS, followed by a study comparing conventional GPS topographic surveys with UAS based systems and laser scanning systems. The comparison of the various methods was broken into the following four categories: operator safety analysis, time comparison, survey accuracy, and cost analysis. After all of these portions of comparison were completed a recommendation was provided based on the evaluation that was performed."

Jan 1, 2017

By M. S. Enders

The McDonald deposit is a volcanic-hosted epithermal gold resource that is estimated to contain 251,000 kg of gold in 375 Mt of ore at an average grade of 0.7 g/t gold. Phelps Dodge exploration geologists, working for the Seven-Up Pete Joint Venture, discovered the deposit in 1989. By the end of 1992, 494 drill holes for over 113,000 m of drilling, bulk sampling, soil geochemistry, geophysics, metallurgical testing, engineering, and environmental studies had been completed to support feasibility studies. The discovery of McDonald required vision, persistence, and commitment of everyone from the geologist on the drill rig to the senior management of the company.

Jan 1, 1995