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By William G. Doepken

GENERAL DESCRIPTION The Henderson mine utilizes a highly mechanized, continuous panel-caving system to extract ore from a deep, massive, molybdenum deposit. The mine site, lo¬cated 80.5 km (50 miles) west of Denver, is situated at 3170 m (10,400 ft) above sea level in a steep valley on the eastern side of the Continental Divide. The mill site, located on the western side of the divide, is linked to the mine via a 15.5-km (9.6-mile) railroad tunnel. Mine production is scheduled to reach 27 215 t/ d (30,000 stpd) from the uppermost production level. This pro¬duction rate will have been reached within the four years following an intensive ten-year preproduction development program. A second production level, due to come on stream in later years, will expand production capabilities to 31 751 t/d (35,000 stpd). The mine, which employs approximately 2000, has blocked-out ore reserves of 220 Mt (242 million st) at an average grade of 0.42% MoS2. Geology The Henderson deposit is composed of two partially overlapping ore bodies that lie 1080 m (3600 ft) beneath the peak of Red Mountain. The ore bodies are entirely within a Tertiary rhyolite porphyry intrusive complex that has intruded Precambrian granite. The de¬posit is elliptical in plan with overall dimensions of 670 x 910 m (2200 x 3000 ft). In section it is arcuate with an average thickness of 185 m (600 ft). The top of the deposit is at an elevation of 2610 m (8700 ft) while the lower limits range from 2340 m (7800 ft) on the west to below 2100 m (7000 ft) on the east. The mineralization is relatively continuous in the ore bodies and consists of molybdenite and quartz in random to subrandom, intersecting, closely spaced veinlets. Cavability RQD (rock quality designation) * values measured from Henderson drill core and compared with the RQD values from the Climax and Urad block-cave mines in¬dicated that the Henderson ore would cave but with difficulty and that a high percentage of the cave ma¬terial would be blocky. Initial caving experience shows the Henderson ore caves easier and with greater frag¬mentation than was indicated by the RQD values. Pos¬sible reasons for this are: 1) The greater lithostatic load at the Henderson has a greater effect on caving and fragmentation than anticipated. 2) The relief of confining pressure due to caving action and brittleness of the rock is enhancing breakage. Mine Layout The Henderson mine layout was designed from its inception for a large-scale, rubber-tired, continuous panel-caving mining system. The ore body is vertically divided into three major mine levels (Fig. 1). The top¬most level (8100 level), which is 2469 m (8100 ft) above sea level, is the current mine production level. The intermediate or 7700 level, which is in the initial

Jan 1, 1982

By John D. Morgan

The U.S. economy annually needs over 4 billion tons of new mineral supplies. The value of domestically produced energy and processed materials of mineral origin exceeds $175 billion annually, but domestic production of both raw and processed minerals is not keeping pace with demand.

Jan 1, 1974

By E. Martinez

A heavy mineral sand sample was tested containing 13% heavy mineral consisting of rutile, zircon, and ilmenite. Eleven tests were run at a mill site with a Mineral Deposit Limited MG 4 spiral to determine the effect of the addition 0; magnets to the spiral compared to conventional gravity separation. Different magnet configurations and field strengths were tested. Optimum results were obtained with the spiral retrofitted with magnets. The heavy mineral content of the concentrate was increased from 55.5% in the control to 64.2% with the magnets. The 8.7% improvement in heavy mineral recovery was due not only to the weakly-magnetic ilmenite, but also to increased recoveries if the non-magnetic zircon and rutile. The increased recoveries were achieved with no loss of concentrate grade.

Jan 1, 1992

By Richard J. Robbins

Mechanical raise and tunnel boring are new techniques to most of the mining industry. Coal, salt and potash have been bored economically, but until recently boring machines were not designed specifically for rock boring in underground mining. The construction industry has led the field of rock boring since 1854 when the first tunnel boring machines built by James S. Robbins and Associates went to work at Oahe Dam, South Dakota. Since that time the company has built boring machines for tunneling through ground conditions varying from cohesionless soil to hard rock, and in diameters ranging from 7 feet to 36 feet 8 inches. It is natural that the construction industry got the jump on mining with the use of mechanical rock boring equipment. Mines have looked for the long range answer to problems of underground excavation and they have chosen proved and established techniques they expect to employ for the next ten or twenty years. The mine development was laid out to accommodate these techniques.

Jan 1, 1964

By Harley G. Pyles

Rotary Percussion drilling has shown great improvement over rotary drilling, when hard roof is encountered. In addition, Rotary Percussion drills have eliminated the need for air drills in many applications. Improved drilling rates have been achieved but roof bolting is still a bottleneck in many operations and the demand for further improvement will continue. Drilling rates beyond current performance is limited by the capabilities of existing drill steels and bits to resist increased horsepower input. The most apparent immediate solution to improved drilling is to increase the strength and rigidity of the drill steels. Drilling experience indicates that a l-1/2" diameter or 1-5/8" diameter hole can be drilled as rapidly or 'more rapidly than the standard 1-3/8" diameter hole. Greater torque and thrust capacities can be achieved through the use of larger O. D. and I. D, steels, however, this is only possible if the larger hole sizes can be made allowable. Large diameter anchorage shells can be made available at a slight extra cost.

Jan 1, 1965

By M. D. McInnis

The Jualin Gold Prospect is centered on Johnson Creek, approximately 40 air miles north-west of Juneau, Alaska. The property is on the southern end of the Kakuhan Range with Berners Bay immediately to the south and Lynn Canal to the west. The property is accessible directly by helicopter from Juneau or by float plane to the head of a 5.5 mile gravel road that begins on the north side of Berners Bay and terminates at the old workings of the Jualin Mine near the center of the property.

Jan 1, 1989

By Don C. White

Santa Rosa is a mid-Tertiary, volcanic-hosted, gold-silver deposit. Current proven and probable reserves are 8.9 Mt (9.8 million st) grading 1.5 g/t (0.044 oz/ st) gold, minable by open pit and amenable to heap leaching. It is the product of hydrothermal mineralization along an arcuate segment of a caldera collapse ring fault in a probable maar volcanic setting. This segment was later broken by radial faults. Gold at Santa Rosa occurs principally as electrum, finely disseminated through intermediate tuffs, and associated with pyrite. The nearby Alto de la Mina deposit displays stockwork silica-pyrite-gold in a tectonically and hydrothermally shattered andesite flow. Miocene epithermal mineralization was accompanied by central silicification and pyritization and more distal argillization. An andesite flow cap rock at Santa Rosa played a pivotal role as an upward permeability barrier. Highest gold grades and most intense alteration occur closest to the ring faults and immediately beneath the andesite flow. Supergene alteration effects on the gold distribution are minimal.

Jan 1, 1995

By Carrie Smith

The Society for Mining, Metallurgy & Exploration’s annual conference and expo, MINEXCHANGE 2026, will take place Feb. 22–25, 2026, at the Salt Palace Convention Center in Salt Lake City, UT. The event will foster a hub for innovation, technical exchange and policy discussion for the global mining industry. Over four days, attendees will take part in short courses, technical sessions, field trips and networking events that highlight the advancement of the mining industry. The conference’s keynote session, titled “Regaining America’s Mineral Dominance,” will start at 8:30 a.m. on Feb. 23 in the Grand Ballroom E–J. The speaker will address the sweeping policy actions now shaping the nation’s mineral future, following a series of executive orders issued by the Trump administration designed to bolster domestic mineral production and energy security. These directives, including Immediate Measures to Increase Domestic Mineral Production (EO 14241) and Establishing the National Energy Dominance Council (EO 14213), have set in motion a coordinated effort across the Departments of Interior, Energy, Defense and Commerce to enhance the United States’ position as a global leader in critical minerals. The invited speakers include Utah Governor Spencer J. Cox and Nate Foster, managing director of Rio Tinto Kennecott, who will examine how policy and industry are converging to meet surging demand for minerals essential to modern technology. Governor Cox is expected to highlight Utah’s long-standing role in American mining, from the early development of Kennecott Copper to its current position as a producer of 40 of the nation’s 50 identified critical minerals. Foster, meanwhile, will offer insights into Rio Tinto’s extensive operations in Utah, including the Kennecott Copper Mine — one of only two operating copper smelters in the United States — and the company’s ongoing efforts to build more resilient, sustainable supply chains. Rio Tinto’s work in critical mineral production, from copper and tellurium in Utah to new operations in Arizona, has made it a fundamental figure in the U.S. mineral economy. Projects such as the Resolution Copper development and the revival of Gunnison Copper using Rio Tinto’s innovative Nuton technology illustrate how private-sector leadership is driving sustainability in domestic mining. These advancements come at a critical moment for the industry, as copper prices remain near historic highs. The keynote session will emphasize that meeting future mineral demand will require a concerted effort between government, industry and technology partners to secure responsible, domestic production. Immediately following the keynote, the Robert E. Murray Innovation Award Lecture will start at 10 a.m. as part of the same session. Lucy England, managing director at FLSmidth, will present on “Sustainable Copper Mining Flowsheets and the MissionZero Mine.” England, who has spent more than 25 years in mineral processing and innovation, will discuss how FLSmidth’s MissionZero initiative aims to develop the world’s most efficient

Feb 1, 2026

By P. M. Soupios

There is an increasing requirement for geophysical surveys carried out during geotechnical investigations to provide direct information about rock quality or other geotechnical parameters. With the paucity of information to correlate geophysical results with actual rock properties, this is still difficult to achieve and additional research effort needs to be performed to address this issue. Nowadays, several researchers have been described detailed studies which designed specifically to investigate this matter. Generally, geophysical techniques which are used to estimate seismic velocities in the subsurface focus on the low strain levels that are not large enough to induce significant nonlinear, nonelastic stress-strain behavior (Luna and Jadi, 2000), which is normally evaluated when addressing liquefaction potential of soils in the shallow subsurface. Soil parameters relevant to seismic ground response (Rechtien, 1996) are density, relative density and void ratio, permeability, shear modulus, water saturation, soil fabric and stress history. Detailed characterization of elastic properties near a major construction site (e.g. a bridge) is useful for near field dynamic analysis of soil-structure interaction (SSI) effects. The coupled effect of the bridge foundation (piles, piers or abutments) and the soil immediately surrounding these substructure elements is essential for dynamic SSI analysis of these critical bridge structures. This paper presents a geophysical investigation performed along the under construction highway of Egnatia Odos, approximately 13 km west from the town of Xanthi in N. Greece. Twelve geotechnical boreholes, drilled at the maximum depth of 75 m, approximately located 20 m from the Nestos River. The objective of the survey was to obtain the high-resolution compressional and shear wave velocities of the shallow subsurface for computation of elastic engineering properties of the unconsolidated material interposed between the investigated boreholes. Joint interpretation of borehole logs and velocity images obtained by P- and S-wave traveltime inversions outlined shallow geological anomalies.

Jan 1, 2005

By D. L. Stevens

Following an in-depth scenario and strategic-planning exercise in 1997, Noranda's mine production goal was set at 500 kt/a (550,000 stpy) of both copper and zinc metal in five years. There had been no recent discoveries, reserves were shrinking and things had to be done differently and quickly. Change is now continual in Noranda's program. The following steps were taken: the exploration and business development groups were combined, teams were formed to search for and respond to opportunity; geologists were coached to become more business minded and engineers were coached to become more optimistic; the company went global; clear thresholds were set, marginal properties were farmed out and other properties were fast tracked; reconnaissance exploration was focussed where there was a clear competitive advantage; and Noranda became a "flexible" partner to juniors and seniors. Is it working? A number of successes, near successes and outright failures are discussed. The main result is a much higher rate of opportunity flux, which is essential for success in the mining industry.

Jan 1, 2000

By Richard E. Ray, George N. Aul, Fred Garcia, William P. Diamond

Increasing longwall panel dimensions, particularly face width in gassy coalbeds, may result in unexpected increases in methane emissions. To investigate this problem, continuous longwall face emission monitoring studies were conducted at two adjacent mines operating in the Pocahontas No. 3 Coalbed, where longwall faces were to be extended from 229 to 305 m (750 to 1,000 ft). It was predicted by regression analysis of methane emissions data from 229 m (750 ft) wide longwall faces that extending faces to 305 m (1,000 ft) would increase methane emission rates by only 7 percent (0.6 m3/min (20 cfm)), to 8.6 m3/min (304 cfm) at the VP-1 Mine. In contrast, it was predicted that extending faces at the VP-3 Mine could increase methane emissions by as much as 13 percent (1.8 m3/min (65 cfm)) to 16.1 m3/min (567 cfm). The geologic and mine design factors in¬fluencing the variation in face emissions between the two mines will be discussed.

Jan 1, 1997

By Malcolm Wills

Boddington Gold Mine commenced operation in 1987 with an initial production of 3.0 Mt/y at a grade of 3.5 git. Head grade has reduced over the life of the mine and the major response to the drop in grade has been to increase mining rates and increase plant throughput. A capital expansion was carried out in 1996 increasing the throughput to 6.0 Mt/y and since that date tonnage has been increased without major capital expenditure. BGM's current mill throughput is 8.77 Mt/y ( 1999). In 1999 the combined basement plant and direct leach plant processed 8,770,055 tonnes to produce 233,507 ozs or 7.262882 tonnes of gold at an average head grade of 0.83 git. With grades of 0.83 git, and gold price at record lows, $US251.95loz in August 1999 or $A393.67loz it has been necessary to make and maintain major cost savings to remain profitable. Boddington Gold Mine has achieved this by a number of steps including a productivity study by outside consultants.

Jan 1, 2000

By Keith Whiting

The Little Boulder Creek molybdenum deposit is in central Idaho, in the White Cloud Range about 3.2 km (2 miles) northeast of Castle Peak, the highest peak in the range. The elevation of the deposit is about 2591 m (8500 ft). The deposit is accessible only by helicopter or by a 12.9-km (8-mile) trail from the county road along the East Fork of the Salmon River. The nearest towns are Clayton [25.7 km (16 miles) northeast], Stanley [33.8 km (21 miles) northwest], and Ketchum [45 km (28 miles) south-southeast]. The principal known deposit at Little Boulder Creek is called the "North Zone." In this zone, the molybdenite occurs both in stock- work veinlets and disseminated through metamorphosed quartzite of Pennsylvanian age. Pyrite is ubiquitous, averaging perhaps 0.05%. Scheelite and/or powellite are present in trace amounts. An intrusive quartz monzonite stock, probably of Cretaceous age, bounds the deposit on the west. A steep fault which drops Tertiary age Challis volcanics into contact with the mineralization limits the deposit on the east.

Jan 1, 1991

By H. M. Ray

The discovery of the New Lead Belt in the mid-'50s began a search for mill design criteria that is continuously updated. The opportunity to design, construct, and operate four new mills in the span of 20 years provided fertile areas for new concepts. The central theme for design parameters encompassed simplicity, functional, and economic consideration. Ore characteristics for each plant remained relatively constant, providing stable criteria for grinding circuits. Bond index nominally 10-12. Flotation circuit parameters were based upon power application with 10-20% excess capacity built-in to protect recovery. Newer equipment exhibits greater power application efficiency lowering horsepower requirements per ton. Instrumentation was installed to stabilize circuits, protect equipment, and improve products. With ever increasing requirements of higher quality products, environmental considerations, and operating cost pressures, the upgrading of operating procedures is in a constant state of flux. Installation of more efficient equipment, chemical processing, or any other technique would be considered as feasible. Current practice is for St. Joe to design and engineer in-house its own plant design. The exception being detailing of structural steel. It is felt that familiarity with past design criteria serves as a valuable foundation to incorporate changes. Also, direct contact with operator provides specific data, and feedback for constructive criticism that is utilized for defining and correcting problems. The results are in reality an operator's plant with the benefit of advancing technology that meets the demands for improved products without sacrificing the economies of throughput or recovery.

Jan 1, 1977

By William J. Shampine

This map shows general trends of the chloride concentration of water in the upper part of the Floridan aquifer. Below this part of the aquifer, high chloride water can be found everywhere in the State. The accompanying cross section shows the depth to salty water across central Florida. In the center of Florida, fresh water may be found as deep as 2.000 feet, whereas, along the coast it may extend no deeper than about 200 feet. Chloride concentration in small local areas may deviate from the values represented on both the cross section and the main map. This map shows general trends of the chloride concentration of water in the upper part of the Floridan aquifer. Below this part of the aquifer, high chloride water can be found everywhere in the State. The accompanying cross section shows the depth to salty water across central Florida. In the center of Florida, fresh water may be found as deep as 2.000 feet, whereas, along the coast it may extend no deeper than about 200 feet. Chloride concentration in small local areas may deviate from the values represented on both the cross section and the main map.

Jan 1, 1966

By I. Weir-Jones

[Currently the cost of carrying out 'in situ' geotechnical investigation programmes or installing and operating monitoring systems at construction or mining sites is rising var." rapidly. This is primarily because of our ever increasing labour rates. As a result of this problem efforts are no,, being made develop techniques for the economical; collection of large quantities of geotechnical data relating, to such problems as done stability evaluation, the behaviour of underground openings, or 'in situ' testing procedures. The efforts to reduce the labour content. are particularly apparent in those procedures which have traditionally been manpower intensive e.g. 'in situ' permeability testing where an entire drilling crew and their associated eguipment have been on standby while testis has been carried out; or data collection in underground construction operations where much tine is typically wasted obtaining or maintaining access to instrument sites. In an attempt to illustrate one specialist consulting company's approach to the problem of reducing investigation costs, this rarer examines four recent developments in the field of geotechnical investigation and monitoring which have come about during the last two Years as a result of cur research and development programme. Although these techniques and devices have been developed for specific projects, they all have broad applications in the geotechnical field and they are indicative of the direction in which this company feels developments will take place.]

Jan 1, 1975

I am deeply honored and grateful to receive the prestigious Gaudin Award. Frankly, I find myself amazed to be included in the company of those outstanding individuals who have previously received this recognition. I am humbly honored to receive this award from an industrial research group. Gaudin was an internationally respected leader of mineral processing. His research contributions widely covered the whole spectrum of mineral processing science and technology, including comminution, size distribution, electrostatics, magnetics, thickening and, especially, the development of flotation theory and application. In his later career, he increased his emphasis on hydrometallurgical technology. In fact, one of his most notable practical contributions was in the development of leaching and ion exchange purification of uranium from low-grade ores. Gaudin catalyzed the trend in mineral processing toward engineering science for a better understanding of process mechanisms and kinetics. He said that those working in academic fields should have an underlying responsibility to the industry they represent. This imposed on him the objective of seeking out research areas that had some relevance to industry's problems. He said, "research without an audience cannot survive." Gaudin performed a most vital service, both in the areas of research in which he was actively involved and through his less-direct influence on current research by his many former students and their students in turn. Interestingly, Gaudin's strength has influenced Newmont Mining Corp. His favorite student was Plato Malozemoff. He had a long and distinguished career with Newmont, beginning as staff engineer in 1945, serving as Newmont's president for more than 30 years and as chairman of the company for 20 years. Newmont's greatest growth occurred during his leadership. Another one of Gaudin's graduate students from Montana School of Mines, Oscar F. Tangel, joined Newmont in 1967. He was a vice president of research and development until 1986. In their efforts, Newmont built a research group, developing the technologies of exploration, geophysics and metallurgy. The Newmont technical facility is named in honor of Malozamoff as "a leader in the development and implementation of new technologies." The mining industry is facing very difficult times, especially in the metals industry. Most metal prices have declined and are still not stable. Most domestic mining companies have largely done away with in-house research and development. Many are reluctant to invest in technology development for which there is not an immediate need. The metal mining industries are focusing on reducing operating costs to survive. Newmont is in the same situation. I appreciate that Newmont's management believes in the importance of research and technology and the impact technology has on the company's value. At Newmont, technology development involves working in the area of applied research. The connections from academic fundamental research to applied research and finally to process development and implementation are very important to develop a new technology. Fundamental research is our foundation, our guidance, giving us direction, providing the principal and mechanism and understanding why it works. Understanding the why will lead to further innovative development. Applied research needs to find the approach to reality, how it works, how to make it better and how to commercialize it. Process development and implementation needs a strong leadership, requires long-term commitment, makes improvements in practical engineering and finally develops an economically favorable process. Implementation is the most important stage in making research a reality. Each stage needs to give feedback to the other stages. Problems need to be understood and solved. Otherwise, the new technology will go nowhere. Simplicity of operation is a key of success in any plant. Necessity is the

Jan 1, 2002

By K. Kim, T. M. Yegulalp

A new explanation of the scale dependency of rock strength is presented based on the theory of extremes. A brief review of past work on specimen size and strength relationship is followed by an introduction to the fundamentals of the underlying theory of extremes and its relationship to the scale effect. It is shown that the weakest link theory is directly related to extremal statistics and that parameters of strength distributions of rock can be derived as a function of the specimen size. Three sets of Brazilian test data are used to demonstrate the use of this approach.

Jan 1, 1994

By H. Y. Yang, L. L. Tong

Semicontinuous-flow, multistage biooxidation experiments of a Chinese refractory, high-sulfur gold concentrate were conducted with different pulp densities for gold recovery. The maximum iron, sulfur and arsenic oxidation rates of 90.0, 88.8 and 96.4 percent, respectively, were obtained in the experiments with 5 percent pulp density. The highest gold and silver recoveries of 96.1 and 68.9 percent, respectively, were achieved by cyanidation. The negative effect of high pulp density on biooxidation was related to the decrease of free and adsorbed cell concentrations with increasing pulp density. The data of iron oxidation from the semicontinuous biooxidation experiments were best fitted by a shrinking core model in which the chemical reaction controlled the rate. The dissolution kinetics of sulfur and arsenic were therefore analyzed by a shrinking core model in which the internal diffusion controlled the bioleaching rates. For the quantitative description of biooxidation efficiency, two parameters — mass dissolution rate and volume dissolution rate — were proposed. In the first stage, the mass dissolution rates of minerals were negatively correlated while the volume dissolution rates were positively correlated with the actual pulp density. The iron and sulfur mass dissolution rates decreased with increasing actual pulp densities in the third and fourth stage, while linear increasing relationships between the volume dissolution rates of minerals and the actual pulp density were observed from the second to fourth stage. The highest mass dissolution rates of minerals were obtained in the first stage with 5 percent pulp density. The highest volume dissolution rates of minerals were obtained in the first stage with 15 percent pulp density. Compared to the volume dissolution rate, the mass dissolution rate was more intuitive to reflect the negative effect of high pulp density on biooxidation efficiency.

By G. P. JADAUN, ANINDYA PAIN, Aditya Rana, SAURAV RUKHAIYAR, N. K. Bhagat

This study compares three different techniques — decision tree, artificial neural network (ANN) and multivariate regression analysis (MVRA) — for predicting blast-induced ground vibrations in some Indian tunneling projects. The models’ performance was also compared with site-specific conventional predictor equations. A database consisting of 137 vibration records was randomly divided into training and testing sets for model generation. The results indicate that the decision tree is best suited to predicting vibrations. Furthermore, the decision tree suggests that the intensity of near-field ground vibrations is mainly affected by the total charge fired in a round, whereas the intensity of far-field vibrations is governed by maximum charge per delay and charge per hole.