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By Thomas N. Walthier

Exploration is the systematically financed and technically oriented search for mineral wealth. Almost all established mining companies have an exploration department. The size of a company's search varies over the years as the company's profits, or the corporate philosophy change. While the established mining companies have exploration departments, they are also alert to acquiring discoveries made by others -- especially by prospectors and small companies without the resources to develop their find. The emphasis in some large companies stresses self-generated discoveries while others rely heavily on acquisitions; again, over the years the emphasis may alternate. In the last analysis, essentially all new mineral wealth was found through someone's exploration effort. Before we discuss how exploration is financed, it will be informative to analyze how discoveries have been made and by whom. Recently, the author conducted a survey of randomly selected major mining companies to answer these questions. Most companies responded and many went to considerable effort to give complete and detailed answers. I thank all for their help and cooperation. The questionnaire is attached as Appendix I. Appendix II is a list of the 400 companies that replied in a complete enough manner and format to be analyzed here. The results of the questionnaire are given in Table 1. Over 57% of the new orebodies acquired by 40 major mining companies during the past quarter of a century were generated

Jan 1, 1977

By Lynn B. Hales

The Supervisory Computer System at Cities Service copper mine and concentrator at Miami, Arizona was installed at Pinto Valley in the spring of 1975. Design and specification [l] of the digital system was initiated jointly by key plant personnel at Pinto Valley and staff of Cities Service Research and Development Company. The Pinto Valley digital system [2] may be classified as a supervisory control system of hierarchical design. There are three fully independent satellite computers which retrieve and reduce the raw plant data from each of the three main operating areas - the primary crushing plant, the fine crushing plant, and the grinding and flotation plant. While the three satellite computers are core resident systems, the master computer is a disc-based operating system which also interfaces with a computer controlled on-stream x-ray analyzer system. Figure 1 illustrates the basic system configuration [3]. The software systems required to support a large system are quite diverse and vary greatly in function. The philosophy followed in dividing the software into three categories was designed to: 1) fully utilize existing process knowledge of technical staff; 2) delegate certain software tasks to outside sources already skilled and trained in software development; and 3) maintain final control over the design and operation of each system.

Jan 1, 1976

By William Gleason

"There are signs that the commodity downturn that has battered the mining industry for the past five years is beginning to ease up. As the dust begins to settle and mining companies begin to take stock of the battle, Newmont Mining Corp. will be one that is standing strong with just a few scrapes and bruises thanks in large part to the leadership of president and chief executive officer Gary Goldberg and his right hand man and chief operating officer, Chris Robison.As he closes in on retirement (for a second time) Robison, a third-generation miner from Nevada, took time to speak with Mining Engineering about a 33-year career in which, among other things, he is credited with not just helping Newmont survive the turbulent times but with steering the company to a safer, more productive and more profitable heading.“I think we did it better than anyone else,” Robison said when asked how the company fared during the past five years. “We didn’t talk about it a lot, we just put together a strategy and we delivered.”What Newmont, the world’s second-largest gold mining company by production, delivered since Robison took the position of chief operating officer in 2013 are improvements in costs, porduction, projects and safety.Operating under the mantra of “live within your means,” Robison was pulled out of retirement from Rio Tinto and into a challenging situation at Newmont. The price of gold was in a nose dive from a high of nearly $58/g ($1,800/oz) and heading to levels closer to $38.60/g ($1,200 oz).“Newmont is a big ship that can’t be turned, but has to be steered,” said Robison. “We recognized that we had to set a new course. The direction the ship was going was great for $1,600 to $1,800/oz gold but we were chasing ounces.”Like the rest of the gold mining sector before the falling gold prices, Newmont was focused on volume and was looking for gold wherever it could be found. The slogan at Newmont in 2011 was “7 million ounces a year by 2017.”When Robison came on board it was a different reality.“We had to begin focusing on value over volume as the cornerstone of Newmont going forward,” he said."

Aug 1, 2016

By W. Fletcher

Startup of a new plant is a very interesting time. It generally is also a very demanding and often frustrating period. Startup problems can become serious ii they impede the early achievement of full plant production. Raw materials are wasted, manpower is unproductive, field modifications can be extremely expensive and market commitments may not be met. This paper outlines a well proven and highly successful approach to eliminating many of the problems and frustrations often experienced in plant startup. The procedures and methods summarized in the following paragraphs have been developed over a period of 25 years during which some 90 plants were started up.

Jan 1, 1981

By V. E. Housman

EPA's Mining Waste Section within the Office of Solid Waste is continuing to collect and analyze information on mining waste management practices. Starting in 1991, the Mining Waste Section has continued to conduct site visits and prepare case study reports on the waste generation and management practices of operating mines. In choosing sites to study, a reasonable attempt was made to provide diversity in mining commodity types, geographic regions, geology, climate, and environment. To date, EPA has visited the following mines: Asarco Troy (copper) in Montana, Newmont Rain in Nevada (gold), Cyprus Thompson Creek (molybdenum) in Idaho, LTV Steel (iron) in Minnesota, Phelps Dodge Morenci (copper) in Arizona, Doe Run Fletcher (lead) in Missouri, Brewer (gold) in South Carolina, IMC Four Corners (phosphate) .in Florida, Pennzoil Culberson (sulfur) in Texas, Nerco Cripple Creek (gold) in Colorado, Copper Range White Pine (copper) in Michigan, Magma San Manuel (copper) in Arizona, Colosseum (gold) in California, and several gold placer mines in Alaska, including the Valdez Creek Mine. EPA has prepared a case study report on each facility. The mine operators were provided an opportunity to comment on their respective site visit report and their comments have been included in' each respective report. These site visit reports have in turn been incorporated into technical resource documents which provide a detailed description of each mining sector. EPA is currently reviewing the technical resource documents and plans to release the documents in the Spring of 1994.

Jan 1, 1994

By Robert J. Wright

The purpose of this paper is to propose a classification of uranium deposits that is believed to be well suited to the needs of uranium exploration and resource assessment. By way of background some observations are offered about mineral exploration in general, and uranium in particular. Attention is first given to the we of models in mineral exploration. Some general principles of mineral deposit classification, the basis for model formulation, are then considered. Finally, the uranium classification is presented.

Jan 1, 1979

By D. R. Wilburn

This summary of international mineral exploration activities for 2012 draws upon information from industry sources, published 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 analyses of exploration activities performed by the mineral industry. Three sources of information are reported and analyzed in this annual review of international exploration for 2012: 1) budgetary statistics expressed in U.S. nominal dollars provided by SNL Metals Economics Group (MEG) of Halifax, Nova Scotia; 2) regional and site-specific exploration activities that took place in 2012 as compiled by the USGS and 3) regional events including economic, social and political conditions that affected exploration activities, which were derived from published sources and unpublished discussions with USGS and industry specialists.

May 1, 2013

By Dapeng Zhang, Brij Moudgil, Shibo Zheng, Chunhui Feng, Wenyi Song, Wending Xiao, Patrick Zhang

Separation of dolomite from phosphate is the most challenging problem in phosphate mineral processing. Over 50% of the future phosphate reserve in Florida contains too much dolomite to process using the current industry practice. The current phosphoric acid production practice requires less than 1% MgO in the phosphate concentrate as the feed material. The Florida Industrial and Phosphate (FIPR) Institute has collaborated with worldwide experts in the field to address this issue. As a result, the industry is now offered three feasible options. Option 1 offers three methods for reducing MgO content in the concentrate from the Crago process, including adding a dolomite depressant in the rougher flotation step, dolomite flotation of the cleaner concentrate, and scrubbing the cleaner concentrate in quartz sand. These methods could reduce MgO content in the final concentrate by 20–40%. Option 2 involves crushing and grinding of high-dolomite phosphate pebbles followed by dolomite flotation at slightly acidic pH using a new collector that does not require phosphoric acid as a phosphate depressant, achieving a final concentrate analyzing less than 0.9% MgO at about 87% P2O5 recovery. Option 3 is a gravity separation technique using an innovative separation jig, and its full potential remains to be demonstrated.

By D. A. Norrgran

The term "secondary recovery" has recently brought on a new meaning in view of the depletion of natural resources, energy conservation, plant optimization, and the environmental consciousness that has led to hazardous waste management, recycling, and secondary processing. Many secondary recovery processes are being developed applying mineral processing technology. Gravity separation, magnetic separation, and flotation have all emerged as implicit methods for recovering residual values from various process streams and hazardous constituents from waste streams. Recently, a technique for concentrating metallics has been successfully reintroduced. Although the concept of the eddy-current separator was developed over a century ago, (Patent 400317 issued to Thomas Edison on March 26, 1889) it was not until this last decade that it gained prominent acceptance. The evolution of permanent magnets has provided a cost effective alternative for the generation of high intensity magnetic fields. High energy permanent magnets have substantially reduced the capital and operating costs over the electromagnetic circuits employed in antecedent eddy-current separators. Specifically, in recent years, the strength of permanent magnets has increased several fold with neodymiun-boron-iron rare earth magnets now providing an energy product of 35 million gauss-oersted. Figure 1 shows the evolution in the strength of permanent magnets. The development of these rare earth magnets has led to the design of circuits possessing a magnetic force an order of magnitude greater than that of conventional permanent magnetic circuits.

Jan 1, 1991

By M. A. Boucher

The purpose of my presentation is threefold: a) to make you aware of what is available in Canada in terms of refractory minerals. b) indicate the mineral deposits that have potential for development. c) show the advantages of Canada as a supplier of electrical energy necessary for the production of electrofused minerals. Canada is a producer of natural refractory minerals, electrofused minerals, and synthetic refractory minerals. Several deposits also have good potential for development. The natural refractory minerals produced in Canada are shown in Table 1. The major minerals by decreasing order of importance in terms of tonnage and values are: dolomite, graphite and magnesite.

Jan 1, 1992

By C. Frenzel

Tunnel boring machines (TBM) utilize disc cutters as the primary means for excavating hard rock. Depending on rock excavatability and rock abrasivity disc cutters can exhibit significant wear. A detailed analysis has been carried out to characterize failure modes and wear patterns of disc cutters. The relationship between rock properties, op-eration of the TBM, and failure modes of cutting tools is clearly high-lighted. On that basis a prediction tool for disc cutter consumption has been developed that allows to estimate not only gross cutter life, but accounts for cutterhead design, premature cutter changes, and disc cutter repair costs.

Jan 1, 2011

By CASSANDRA L. HOEBBEL, Emily J. Haas, MARGARET E. RYAN

Researchers examined datasets from two separate studies that measured common demographic variables but different safety performance outcome variables. Of specific interest was how types of experience might relate to workers’ preparedness to effectively mitigate or respond to both routine and nonroutine risk in the mining industry. The results suggest that individual factors such as length of job, industry, and mine experience are predictive of routine safety performance — as measured by self-reported proactive and compliant safety behaviors — and/or nonroutine safety performance — as measured by perceived competence in self-escape knowledge, skills and abilities (KSAs) — in significant and sometimes unexpected ways.

By A. B. Cecala, G. W. Klinowski

Introduction The US Bureau of Mines has designed and evaluated total mill ventilation systems (TMVS) at two mineral-processing operations. Both systems have proven proficient at cost-effectively reducing respirable dust levels throughout the mills. An 11.8-m3/sec (25,000-cfm) system installed at a clay-processing mill provided about 10 air changes per hour (acph). This system reduced respirable dust concentrations by about 40% throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 23.6 and 47.2 m3/sec (50,000 and 100,000 cfm) of ventilation to the mill building, corresponding to 17 and 34 acph. Average millwide respirable dust reductions were 36% and 64%, respectively. This work was done to determine general guidelines and design criteria for operations that may be interested in implementing TMVS. TMVS should be designed to draw clean make-up air in near the base of the mill. This air provides general purging and may clear some dust-laden areas throughout the mill structure. It is discharged at or near the top of the structure. Without the TMVS, dust can exit the building through open doors, windows, etc. and contaminate outside plant workers. This dust can also be recirculated back into the mill building causing additional contamination problems. TMVS is not a stand-alone system. It is a supplemental technique to assist other localized dust control systems (Mody et al., 1987). Testing Total mill ventilation systems were evaluated at two processing operations. For both tests, the primary goal was to determine the reduction in respirable dust throughout the structure. Test site No. 1. The first evaluation was performed at a clay-crushing and screening mill in New York. The mill's base dimensions were 39.6 x 9.8 m (130 x 32 ft), giving a volumetric capacity of 4250 m3 (150,000 cu ft). The TMVS was designed to provide 12 m3/sec (25,430 cfm) of ventilation air to the mill, representing about 10 acph. This was accomplished by three 4 m3/sec (8475 cfm) roof-powered exhaustors that were evenly spaced across the roof. Three wall louvers provided inlets for make-up air at the mill's base. Two evaluations were performed at this mill. The first occurred for two days in December when outside air temperatures ranged from -12.2° to 4.4° C (10° to 40° F). Temperatures with the wind chill factor dropped as low as -34° to -40° C (-29 to -40° F) during the early morning. The second evaluation was in April when outside air temperatures ranged between 10° to 26.7° C (50° to 80° F). These two evaluations verified the effectiveness of TMVS in lowering respirable-dust concentrations throughout the mill. Gravimetric-sampler respirable-dust concentrations in December ranged from 0.22 to 2.39 mg/m3 under normal conditions, compared to 0.13 to 1.55 mg/m3 with TMVS. In April, respirable dust concentrations ranged from 0.29 to 4.84 mg/m3 under normal conditions compared to 0.21 to 2.37 mg/m3 with the system on. TMVS also increased visibility throughout the mill building. Dust reductions for gravimetric and RAM-I instruments are listed in Table 1. Each value was determined by comparing the average concentration for the entire day of testing for normal and TMVS values. The mean/standard deviation values for gravimetric and RAM-1 results were 42.5/17.6 and 37.1/16.8, respectively.

Jan 1, 1996

By Yashar Pourrahimian, Magreth S. Dotto

Fragmentation by blasting is a critical process in hard rock mining. The blasting process and outcomes are highly influenced by rock mass properties and their response to higher stresses and loading rates. Each rock mass is unique, but some features affect the blast energy similarly, leading to similar outcomes. Having analyzed these features and their influence on blast results, they can be incorporated into the blast design to achieve better outcomes. This paper presents a numerical model validated by a case study from the actual mine blasts that studied the effect of rock mass properties on explosive energy production, attenuations, and overall blast outcomes. The results show that when the model parameters are calibrated based on real data, they can be used to simulate the fragmentation process and therefore be used to aid blast design.

Jun 25, 2023

By John J. Peregoy, James E. Downes

INTRODUCTION The U.S. Department of Energy's Waste Isolation Pilot Plant (WIPP) is being constructed to provide permanent storage of radioactive TRU waste materials emanating from military weapons production. These wastes are contaminated with radioactive elements heavier than uranium, thus the name trans-(or beyond) uranic (Uranium wastes). The WIPP site, which is located 26 miles east of Carlsbad, New Mexico, was chosen thru a selection process after the National Academy of Sciences recommended salt deposits as a promising host strata for the storage of radioactive wastes. Throughout the United States numerous DOE facilities have produced and stored defense-generated TRU wastes. Once WIPP becomes operational in the fall of 1989, all sites may ship directly to this repository. A companion project has developed special shipping containers (TRUPACT) for safe transport of materials to WIPP. The WIPP facility is currently composed of surface buildings, three shafts, and underground storage and experimental rooms and tunnels. Frontier-Kemper Constructors, Inc. (FKCI) has nearly completed the construction of the fourth shaft, an intake shaft, to provide additional ventilation to the underground workings. PLANNED SHAFT EXCAVATION METHOD Full-face raise boring ( upreaming ) was the allowable method selected by Frontier-Kemper Constructors for the excavation of the shaft. After arrival of an oil-field type rotary drill rig in December 1987, a 9 inch diameter pilot hole was drilled from the surface to the mine level, a depth of approximately 2145 feet.

Jan 1, 1989

By Donald Bishko

Zoning is the legal means by which land use can be controlled. Although zoning laws have historically been quick to prevent quarrying, one is hard pressed to find zoning ordinances which specifically state that land should be used (or held in reserve) for quarrying and prevent other uses such as recreation, housing, etc. This situation is especially true when the mineral to be quarried has a low intrinsic value such as sand, gravel, and crushed stone. The chance of a gold mine surviving urban sprawl is probably considerably greater than that of a sand and gravel pit, even though it is possible that the dollar value of the sand and gravel' would exceed that of the gold mine. The research reported herein was concerned with two major topics: to delineate the real costs associated with the non-protection of our construction aggregate resources (growth minerals) and to develop a computer simulation model which would aid planners in making economically sound decisions. This paper describes the problems faced by the mineral aggregate industry and discusses the role of computer simulation in planning problems. It briefly describes a simulation model which has been developed and previously reported12 and discusses the results of a pilot study conducted on the Tri-City area (Albany, Schenectady, and Troy, New York). 3

Jan 1, 1970

By John J. Stetler

The Companhia Vale do Rio Doce in Brazil operates one of the most extensive systems in the world for the mining, transportation, processing, pelletizing and shipping of high grade hematite iron ore and pellets. Current shipping of unbeneficiated, sized, high grade ore from its ports at Tubarão and Vitória is now at the rate of 17,500,000 metric tons annually. An increase in this annual rate is now under study. Using the technology and facilities of Lurgi (1) and Arthur G. McKee company CVRD undertook a program to process and pelletize two types of fines - "Blue Dust" and ?Itabira Fines?. Blue Dust is a high grade fine ore which was bypassed while mining the direct shipping ores and which, also, exists as a very large ore body called the Conceição Mine. Itabira Fines is a lower grade of fine ore which is comprised of in-situ fines and, also fines which are generated in sizing the direct shipping ores for a rigid specification market.

Jan 1, 1970

By B. Berhe, R. D. Lawrence, J. Hinzer

"The fortunes of mining companies and their implied value are tied to cycles - both economic and commodity – within which they operate. Hence the determination of appropriate future metal prices is one of the most critical factors faced by mineral valuators especially for advanced projects. Price, and hence revenue, is usually the most sensitive input to the valuation model. Empirical studies of past forecasts show that the success rate for commodity price forecasting is very poor. This paper explores various approaches and comments on their strengths and weaknesses. We conclude that careful evaluation of long-term metal prices is a key element and is hardly a luxury that can be left to simple averages or rules of thumb. INTRODUCTION Discounted Cash Flow (""DCF"") analysis, is well suited for the valuation of advanced mineral development assets, for which there are identified mineral resources and some form of economic assessment (Pre-Feasibility or Feasibility Study). The DCF method is also the most commonly used method for determining value for such assets. It provides a means of relating the magnitude of expected future cash flows from profits (or losses) to the magnitude of the initial cash flow (investment) needed for capital expenditures to purchase or to develop an asset for commercial production. The method proves useful in making investment decisions as it allows for the quantification of the Net Present Value (“NPV”), as well as the Internal Rate of Return (IRR) and Payback Period on initial investment capital. Valuation by its very nature is a forward-looking exercise. The DCF method attempts to estimate the NPV of expected future cash flows, by selecting factors that will likely affect future cash flow based on informed analysis. One of the most critical and sensitive factors is the determination of appropriate future commodity prices. “The variables that have the greatest impact on a DCF evaluation are the reserves, the metal prices, and the discount rate.”1 The determination of future commodity prices for valuation purpose or during M&A negotiations is a hotly contested issue. There are a number of analysts, institutions and specialized commercial data suppliers that provide both short and long-term commodities price forecasts. Also, the use of an aggregated mean for all available forecasts, or consensus forecasted prices for valuation purposes is not uncommon. The methods used in making forecasts for each forecaster may vary and in many cases may not be publically disclosed. Nonetheless, the aggregated mean of all forecasted commodity prices of reputed institutions is usually taken to “represent the market’s view of likely future commodity prices.”"

Jan 1, 2016

By Isabel F. Barton, MarkD. Barton, Christian A. Rathkopf

Molybdenite is the world’s principal source of rhenium (Re), a critical element in multiple high-tech applications. However, the Re contents in molybdenite vary by orders of magnitude on scales ranging from single grains to whole deposits. In order to better understand the systematics of this variation and what geochemical factors control molybdenite Re concentration, and hence overall Re resources, we examine global patterns in molybdenite Re contents through a compilation of > 3000 measurements of Re in molybdenite from > 700 mainly ore-bearing moderate- to high-temperature hydrothermal systems of different types. Our results are similar to but expand on those of earlier studies. Rhenium concentration in molybdenite has a lognormal distribution and varies systematically with type of geologic system, intrusive lithology, and Mo grade. The lowest-Re molybdenite occurs in greisens (geometric mean 1 ppm ± a multiplicative standard deviation of 9), quartz vein-hosted W-Sn deposits (2 ± 5 ppm), unmineralized granites and granodiorites (12 ± 8 ppm), intrusion-related deposits (24 ± 8 ppm), and porphyry W-Sn deposits (16 ± 11 ppm). Rhenium is most enriched in molybdenites from volcanic sublimates (23,800 ± 5 ppm), with skarn Fe and Au (560 ± 5 ppm and 540 ± 3 ppm respectively) and porphyry Cu and Cu-Au deposits next (470 ± 4 and 430 ± 7 ppm respectively). Among porphyries, skarns, and quartz vein-hosted deposits, Re is most highly concentrated in molybdenites from Cu and Au systems and its concentration decreases systematically through Cu-Mo, Mo, Sn, and W deposits. In nearly all cases, molybdenites from systems associated with intermediate igneous rocks contain more Re than molybdenites from systems of the same type with more felsic rock associations. The disparity between Re contents of molybdenite in felsic and intermediate systems is largest for porphyries, quartz vein-hosted, and skarn deposits and is near zero for subeconomic or barren granite and granodiorite Mo systems; felsic intrusion-related deposits have slightly higher molybdenite Re than their equivalents associated with intermediate intrusions. In most systems, molybdenite Re content does not correlate with metal grade, but may have an inverse correlation with Au grade in intrusion-related deposits (based on a small number of data points) and does exhibit a strong inverse correlation with deposit Mo grade. Dilution of Re through larger amounts (higher deposit grades) of molybdenite explains about 40% of this correlation, but the relative enrichment of Re in molybdenite from low-Mo deposits must also reflect some selective enrichment of Re/Mo in porphyry Cu systems compared to porphyry Mo systems. We found no evidence for secular increase or other systematic temporal variation in molybdenite Re content. The data regarding the use of molybdenite Re content as a proxy for mantle influence are ambiguous. Nearly all observed empirical correlations can be traced back to differences in redox state and sulfide concentration, the two geochemical factors identified here and by previous experimental work as the controlling influences on Re mobility under hydrothermal conditions. Hydrothermal systems with reducing conditions (W- and Sn-rich) tend to have low molybdenite Re even though compiled whole-rock data indicate that their source rocks have as much or more Re as those of more oxidized systems (e.g., Cu-rich). Vapor-phase exsolution, crustal assimilation, and mixing with external fluids may all enrich molybdenite Re concentrations in individual deposits and deposit types, but their extent and importance in overall hydrothermal concentration of Re is uncertain. Thus, it appears that the available molybdenite Re resource in an ore deposit largely depends on how the deposit’s redox and sulfidation conditions have varied over time and space during the timespan of hydrothermal activity. Oxidized, high-sulfide conditions tend to concentrate Re in molybdenite, whereas reducing conditions tend to leave Re dispersed at low concentrations in the bulk rock.

By Wiston Rocher

The Minera Ojos Del Salado (MINOSAL) concentrator is located 20 km (12 miles) southeast of Copiapo, Chile. It processes copper ore provided by its Santos and Resguardo mines at a capacity of 4.2 kt/d (4620 stpd). In 1982, Phelps Dodge acquired the majority interest in MINOSAL to explore the property's potential. At that time, the concentrator plant was a small, antiquated installation with a capacity of 674 t/d (740 stpd). At the time of the pur¬chase, the majority of the ore was produced from the Santos and Resguardo mines, but custom ores of copper, silver and gold were also treated. The acquisition occurred at a crucial time in the copper business, since the price had fallen to nearly 50 cents/ lb. In 1985, Phelps Dodge purchased the outstanding interest in MINOSAL and acquired 100% of the property. Today, after numerous improvements and two expansions, the concentrator is a combination of old and new equipment. The regrind mills, for example, have been in service for about 50 years, while the ceramic concentrate filter represents the latest technology.

Jan 1, 1993