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By Y. Topkaya, Lloyd Petrie, Dianne Marozas, R. E. Johnson, Steven Paulson, J. H. Canterford, B. R. Palmer, R. B. Bhappu, Lorin Redden

This paper describes a fundamental approach to in situ leach mining (ISLM) lixiviant development which emphasizes leaching selectivity through detailed characterization of mineral-solution interfacial chemistry and post-leach geochemistry. This experimentation and modeling approach consists of: (1) petrographic identification of reactive ore and gangue minerals; (2) determination of leaching kinetics of individual minerals through batch leaching tests; (3) evaluation of bulk solution geochemistry through column leaching tests; and (4) ISLM simulation of element species transport and geochemistry through core leaching tests. Recent results confirm good leaching selectivity for manganese, but reveal post- leach precipitation and permeability loss during core leaching experiments.

Jan 1, 1993

By J. A. Brierley, C. L. Brierley, K. A. Prisbrey, R. W. Bartlett, J. G. Harrington

Bacterial oxidation of gold-encapsulating sulfide minerals in low-grade refractory ores was investigated over a period of one year. Crushed ore samples were held in wet, bacteria-inoculated, aerated columns. Sulfide mineral oxidation data were correlated with subsequent gold cyanide extractabilities. Experimental results for both sulfide conversion and gold extraction were compared with a biooxidation kinetics model that incorporates rock size, mineral grain size, and heterogeneous pyrite reaction kinetics. Using the model, extrapolations were made over three years for biooxidation of ore in large stockpiles. Ferric ion (oxidant) diffusion in the solution-filled pores of the rock matrix does not control the biooxidation kinetics of ore crushed to -25 mm.

Jan 1, 1993

By S. C. Sun

Very little information is available concerning the magnetic properties of minerals and only recently has there been any attempt to correlate magnetic susceptibility with varying chemical composition1. The work described here covers a study of the relationship and chemical composition of both the rutile and sphene types of titanium minerals. The relationship between the magnetic susceptibility of three selected mineral specimens and the applied field strength is also presented. Experimental: The equipment and procedures used in this in- vestigation for crushing and cleaning the mineral specimens and for determining the magnetic susceptibilities were the same as that employed by Spokes and Mitchell1. The particle size of-the measured specimens was limited to 270/325 mesh.

Jan 1, 1959

By A. S. Kastrinos

There are many concepts of preventative maintenance. The basic objective of all maintenance organization, however, is the efficient (accomplishment and control of all) inspection, repair, overhaul, material and preventative maintenance functions necessary to maintain facilities and equipment in a condition that will meet operating requirements at a level consistent with low costs and high availability. To formulate a preventative maintenance program requires sound judgment and the ability to apply in a practical manner a system that meets Plant operation requirements, based upon organization, experience, conditions, design and historical data. A maintenance program must be divided into to categories consisting of: 1. Scheduled tasks to be accomplished at planned intervals. The objective of these tasks is to maintain reliability and prevent as much as possible abnormal failures. 2. Non-scheduled tasks that result from periodic reports and which can be scheduled to fit in conveniently with other routine work. The non-scheduled work items may include long-range preparation for lenghty shutdowns requiring Engineering and Shop services.

Jan 1, 1975

By R. V. Ramani, J. Qin

During the mining process, the in-situ material is broken into different size ranges, from very large pieces to very fine particles. Some of the fine particles become airborne. In underground coal mining, airborne respirable dust is associated with health and safety of the miners. The amount and size distributions of airborne dust are important parameters to effective dust control measures. The design of underground mine experiments, including sampling procedures and sample analyses methods to determine these parameters are presented in this paper. A total of fifteen continuous miner cuts were sampled. The amount of dust generated during the cutting process and the relationship between total and respirable airborne dust concentrations and amounts are examined. The amount of respirable dust airborne is on the average only 0.016% of the respirable dust generated. On the average, 61% of the total airborne dust measured is in the respirable size range. The amount of respirable airborne is on the average 36% of the respirable size fraction in the total airborne dust. For equal proportion of rock and coal material cut, rock contributes about twice as much fines (=0.22 mm) as coal. Additional fundamental research is necessary to further the understanding of the airborne propensity of respirable dusts in mine atmospheres.

Jan 1, 1989

By J. L. González-Chávez, A. Ballester, M. L. Blázquez, F. González

In recent years, the bioleaching of sulfidic raw materials has been of great interest. However, the application of this biotechnology is now very limited for many different complex reasons. The mechanism of the chemical and electrochemical reactions taking part in the process is not well understood. The application of electrochemical techniques is useful in its elucidation. Among the common sulfides, galena has been studied very little with respect to its behavior during bioleaching. Therefore, the electrochemical evolution of massive electrodes of lead sulfide in the presence and absence of' a mixed culture of mesophilic microorganisms was investi¬gated by the application of potentiometry, anodic and ca¬thodic polarization and cyclic voltammetry. The agitation rate, the use of pH control and the composition of the nutrient mediums did not have any significant affects on the oxidation of galena. However, the temperature (25 'to 45 °C), the scan rate (4 to 100 mV/s) and the acid used to adjust the pH were significant variables that influenced sulfide oxidation. There¬fore, the peak (600 to 1,000 mV) corresponding to the oxida¬tion of sulfide ions from the mineral was only detected in the presence of a complexing anion of lead. In the presence of bacteria, the peaks corresponding to galena oxidation de¬creased and, at the same time, new peaks appeared both during the oxidation at -300 mV and during the reduction of the mineral surface at 150 and -300 mV. These signals were more important when the attack time increased. The rest potential of bioleached mineral increased with an increase in leaching time, which was related to the electrochemical transformation of the galena surface.

Jan 1, 2000

By S. S. Churchill

Introduction Amidst the apparent chaos of the final push to complete a major construction project, a small group of specialists works with great intensity. Armed with yellow "in test" and green "turned over to operations" tags, these startup engineers follow detailed preoperational test procedures to confirm that a plant is ready to operate. They follow a test schedule designed to complete individual process system in the order they will be needed by operations. After extensive preliminary testing, the startup engineers begin the truly exciting part of their work - initial operations. The thrill of engaging the clutch for the first time on a 10,000 horsepower grinding mill makes all the long hours worthwhile. Preoperational testing and startup are of critical importance to the success of a project. No other aspect of a construction project allows such opportunities for success or failure, and no other aspect is so critically influenced by careful planning. At Bechtel, the tasks of preoperational testing and startup are among the responsibilities of the Mine and Plant Operations group. The Preoperational Testing Process Preoperational testing is the transition phase between constructon and startup on a new plant. It includes the preparation of detailed test schedules and procedures. The schedules are used to coordinate construction completion activities, so that systems are available for startup and operations in a rational sequence. The procedures form the basis for performing the testing and documenting its completion. Tests include instrument calibration, wire insulation tests, wire termination verification, mechanical alignments and inspections, and system cleaning and flushing. Where possible, the systems are then operated on water and their performance recorded. Normally, either the construction contractor or a team of specialists has the responsibility to perform preoperational testing. Witnesses to the testing may be owner operations and maintenance personnel, engineers from the design firm, or specialists assigned to the project who provide assistance and guidance to the contractor in addition to witnesing the work.

Jan 1, 1986

By Randal J. Barnes

There are many methods available for the estimation of geologic parameters (Popoff, 1966; Barnes, 1980). In the last decade a new and relatively sophisticated technique using statistical theory has emerged: geostatistical kriging (David, 1977; Journal and Huijbregts, 1978; Rendu, 1978). An interesting property of geostatistical estimation is that when a geologic parameter is estimated for a given volume, not only is the estimate generated but an associated measure of certainty is produced as well. This statistical measure of estimation confidence is called the estimation variance. While the concept of an estimation variance is universally considered to be a good idea, mining engineers and geologists do not currently have the tools to incorporate it into their planning and quantitative analysis. This paper attempts to develop and present some of the necessary tools required to incorporate estimation uncertainty into mine planning. Geologic uncertainty is portrayed as an economic business risk. This risk is objectively characterized, and-the associated cost is quantified. Geologic delineation sampling is viewed in this light as an economic commodity with an associated cost and value. A coal mine planning example is used as a focus in this presentation. The data used is real, though it has been modified to maintain data security and project anonymity.

Jan 1, 1986

By Michael J. Howes

The nature of business in a free enterprise system is to maximise the return on an investment i.e. to maximise the wealth of the shareholders. This is normally achieved within constraints dictated by many agencies, one of which is the health and welfare of the employees. In the mining industry considerable effort has been expended in improvements in this field, however, the major problem still confronting the practicing ventilation or environmental engineer is the determination of what standards he should design for, which satisfy both the economic and health requirement s. Normally the basic health requirements are satisfied by the minimum standards defined in regulations and codes of practice. These are, however, based on an acceptance of a certain risk or lower production potential. A prime function of the ventilation engineer is therefore to financially justify and implement improvements to both standards and systems. The main purpose of this paper is to examine the basis and techniques of providing this financial justification. Changes in existing methods to achieve the same standards but at lower costs are also covered.

Jan 1, 1980

By T. R. Ellis

The author attempted to concurrently apply the US Uniform Standards of Professional Appraisal Practice (USPAP) and the Australian VALMIN Code to a complex mineral property appraisal assignment and previously to some modest assignments. This led the author into many severe difficulties. These difficulties included the high standards needed in the work of others and information and statements required from the client under the VALMIN Code. The exercises highlighted many positive features of both sets of standards. However, the author concluded that, without modification, VALMIN is incompatible with USPAP and the US regulatory environ¬ment. The author found that VALMIN violates US legal decisions regarding real property appraisal due to its requirement to include many items of business value. The US Securities and Exchange Commission's prohibition on reporting quantitative resource estimates proved to be a severe problem under VALMIN. Some VALMIN requirements could not be met due to the extent and quality of documents specified. Implications and thoughts regarding the development of a set of US minerals appraisal standards are discussed. Management considerations for complex mineral-property appraisal assignments are also presented.

Jan 1, 2000

By Robin B. Steven

Rio Tinto's Kennecott Bingham Canyon Mine is one of the largest open pit copper mines in the world. In 1988 they completed a $400 million project using a conveying system to transfer the ore from an in-pit crusher to the concentrator. The longest conveyor, C-6, was 17,352ft long and ran in a tunnel through the mountain-side to the concentrator. The belt was removed after 14+ years after carrying 700 million tons of 10 minus ore. The paper discusses the original G6 belt's performance and new splicing methods used to achieve a 60% dynamic splice efficiency on the replacement belt.

Jan 1, 2004

By L. Sletmoen, P. Rocque, E. DeSouza

Plans for achieving planned production rates at the Red Lake Mine High Grade Ore Zone required that the mine ventilation system be upgraded. Time constraints required that only a site assessment of the mine ventilation system be performed followed by recommendations for providing adequate ventilation conditions at the production zone. This paper describes the engineering assessment, design and commissioning of the ventilation system upgrade for achieving increased flows at the high grade ore zone. The work was successfully achieved with minimal capital expenditures and disruption to the mining cycle.

Jan 1, 2003

By Vighnesh Chandurkar, Peter Moser, Michael Hitch, Michael Tost, Susanne Feiel

"From 1998-2002 the world's leading mining and metals companies developed the Global Mining Initiative (GMI) to understand their industry's role in the transition to sustainable development and to ensure its long-term contribution to sustainable development (SD). Since then, the industry has come a long way: For example, operational safety and health have improved significantly, environmental management systems and impact assessments have become the norm, community relations have been established, many mining companies report annually on their contributions to SD and the International Council on Mining and Metals (ICMM) has taken on the recommendations of the GMI as an industry association. However, since the GMI the concept of sustainable development has been evolving from a rather generic and loose definition (“weak sustainability”), to an absolute and strict definition of sustainability, based on the boundaries of our planet (“strong sustainability”). Similarly, other concepts such as corporate social responsibility (CSR) have evolved and even deviated from their initial intentions. This paper presents results from a literature review looking at how far this transition has moved from a scientific debate towards becoming mainstream. Furthermore, it explores, by using qualitative comparison analysis, if the current efforts of the large mining companies are still sufficient or if the industry is again at risk of falling behind societal expectations and hence should once again come together - for a GMI 2.0 - in order to update its approach. We conclude that the mining industry, whilst in a “weak sustainability” position and behind the peer group on climate change and natural capital considerations, is aligned with current societal expectations, expressed through the Sustainable Development Goals, and therefore there is no need for a GMI 2.0 at present."

Jan 1, 2017

By J. A. Hrabik

The feasibility of mining deep phosphate deposits by a borehole mining system was compared with mining by proven conventional techniques. An economic comparison of the borehole mining system with conventional dragline and bucket wheel excavator mining systems was completed at various mining depths and production rates. Hypothetical phosphate deposits, with various overburden thicknesses and reserve tonnages, were defined. Geologic conditions necessary for the application of the borehole system were identified. Discounted cash flow analyses based on derived capital and operating costs were used to generate rates of return and product prices. Borehole mining was found to be more economical where overburden thickness was 46 m (150 ft) or greater. However, at 15- and 30-m (50- and 100-ft) thicknesses, conventional surface mining was more economical. Overburden thickness has a great effect on the economic feasibility of the conventional mining systems but less effect on the economics of borehole mining. Economies of scale are only realized in conventional mining, since larger equipment is used to achieve greater production, whereas increased production from borehole mining is achieved using additional equipment units. A comparison of the environmental effects of borehole and conventional surface mining systems showed that borehole mining is environmentally more desirable.

Jan 1, 1987

By C. G. Anderson

In some parts of the world, silver chloride occurs naturally in deposits of cerargyrite (1) (i.e. horn silver). In other cases, silver chloride is produced and exploited for its well- known photographic or electrochemical properties. In this case, it is a valuable commodity needing no further refinement. However, silver chloride is frequently encountered in precious metals refining. In most cases, it is a by-product that occurs in small amounts. For example, it is a common occurrence in gold refining when using the Miller and Wohlwill refining processes or when parting fire assay beads. As such, the mode of reduction to elemental silver is of little impact on the overall refining economics. Thus, a variety of reduction methods are employed all enjoying varying degrees of popularity (2). On the other hand, silver chloride serves as a key intermediate in the production of fine silver by nitrogen species catalyzed acid pressure leaching of refractory silver concentrates. This has most recently been practiced at the Sunshine Mining & Refining plant located in Kellogg, Idaho. Thus, efficient methods of reduction, precipitation and materials handling on an industrial scale are of the utmost importance. In this presentation, the evolution of these methods will be detailed.

Jan 1, 1997

By Dr. Richard F. Coon, James D. Mavis

Risks and abatements associated with preliminary reconnaissance, plugging and filling, and maintenance of perched mine water pool are examined. This case history showed that the initial appeal of portal plugging was replaced by concern over potential environmental hazards when details of implementation were investigated.

Jan 1, 1992

By Lynn B. Hales, Randy A. Ynchausti

Expert supervisory control strategies have been used for many years to improve operating revenues in comminution circuits. Typical improvements in capacity range from four to eight percent. Several case studies of results will be presented as well as a general discussion of the technologies used to achieve the improvements. Crushing. SAG milling and ball milling circuits will be discussed.

Jan 1, 1997

By Y. G. Zhang

Interactive Dynamic Optimization Method (IDOM) will be presented in this paper. IDOM combines inventory theory, dynamic programming, computer simulation and interactive technique to formulate a production schedule for open-pit mines. This new method has been successfully used in metal mines of China for years.

Jan 1, 1986

By G. R. Brunskill

The molybdenite flotation plant at the Magma Copper Co. San Manuel concentrator has been in operation since 1956. In January of 1980, the plant was converted from a hydrogen peroxide-ferrocyanide process to the current sodium cyanide-sodium hydro- sulfide process. This paper is an operational review of Magma Copper Co.'s molybdenite recovery circuit, column cell flotation experience, and use of on-stream X-ray fluorescence analysis.

Jan 1, 1987

By William J. Francart, Gary J. Wirth

Fire detection capability in conveyor belt entries of coal mines has advanced considerably since the passage of the Federal Coal Mine Health and Safety Act. The advances in instrument technology and computer based monitoring have provided better fire detection than ever introduced in the industry. This paper discusses recent belt conveyor fires and detections in mines utilizing CO Monitoring Systems. Data from investigative reports is presented on belt entry fires from 1991 to the present.

Jan 1, 1993