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By Jon K. Ahlness

The Bureau of Mines investigated technologies for testing the integrity of in situ leach mining wells, as required by environmental regulations. To test for leaks, inflatable packers were used to seal the well casing. Laboratory testing determined that the packers could contain a casing pressure up to 50 to 60 psi (345 to 414 kPa) less than the packer inflation pressure. Single-and double-packer configurations were successfully field-tested in 32 wells ranging from 500 to 530 ft (153 to 162 m) in depth. A rigid pipeline and a hoist truck were used to run the packers in and out of the wells for the double-packer tests, which averaged 2-1/4 h each. In an effort to decrease the time of the rigid-pipe double-packer test. a self-contained trailer-mounted test system was designed and built. It utilizes a winch and steel cable to run the packers in and out of the well and high-pressure nylon tubing for packer inflation. This system was successfully field-tested in eight wells averaging 650 ft (198 m) in depth and resulted in a time savings of 13 pct and an operator-hour reduction of 42 pct.

Jan 1, 1985

By C. K. Eilerts

Knowledge of the phase relations of the fluids that exist in the porous spaces of rocks constituting natural petroleum reservoirs and of the behavior of these fluids under various field conditions of operation is essential to the conservation of petroleum and natural gas and to their efficient recovery. The problem of determining whether these fluids are in the liquid or gaseous state and of recognizing the transitions that may take place as the material in the reservoir is subjected to different conditions of pressure and temperature confronts many producers today, especially in certain fields. The subject has grown rapidly in importance since the discovery of and production from deeper reservoirs that have correspondingly higher pressures and temperatures as compared with shallower

Jan 1, 1938

The Mining Foundation of the Southwest (MFSW), located in Tucson, AZ, will hold its 16th annual American Mining Hall of Fame Awards Banquet Saturday, Dec. 5,1998. The Hall of Fame recognizes outstanding contributions to the mining industry by selected individuals and industry partners. Each year, one living award recipient and up to two mining history honorees are chosen by the , Hall of Fame Committee and the Board of Governors of the Mining Foundation. In 1989, the Mining Foundation initiated a Medal of Merit to recognize outstanding individual, technical and professional contributions to the mineral industry. In 1995, an award was created to recognize contributions made by companies and organizations in partnership with the mining industry. This year's inductee, guest of honor and featured speaker will be Charles G. Preble, president and chief executive officer of Southern Peru Copper Corp. He is being recognized for outstanding performance as an executive of an American company operating under difficult circumstances in a foreign country. The Hall of Fame will induct H. Myles Jacob, former chairman and CEO of Inspiration Copper Co., for innovation and farsightedness in matters pivotal to the cop- per industry of his time. In addition, John Cromwell Lincoln, former president and chairman of Bagdad Mining Co., will be inducted for his outstanding contributions to the American mining industry. These contributions include metallurgical research and development of the Bagdad Mine as well as pioneering innovation in the electrical industry. Medals of Merit will be awarded to David N. Skillings, editor and publisher of Skillings Mining Re- view, for his dedication and support of mining interests. J. Ruben Velasco Rodriguez will also receive a Medal of Merit. He is economic geologist, professor and former secretary of the board of directors and secretary general of Compania Minera de Cananea. His medal is for fostering excellent relations between Mexico and the , United States in mining geology and management and for advancing the professional development of others in the field of earth science. An Industry Partnership Award will be presented to Stephen Bechtel and the Bechtel Corp. in recognition of Bechtel's 100th anniversary and the company's outstanding service to the mining industry. The banquet will be held at the The Westin LaPaloma in Tucson beginning with cocktails at 6:30 p.m. Tickets are available from Clare A. Roscoe, manager, Mining Foundation of the Southwest 520-577-7519, fax 520-577-7073.

Jan 1, 1998

By Michael Kynett, Francke Walberg, Richard Millet, Khaled Chowdhury, Mary Perlea

"Cutoff walls are the most common seepage improvement measure for levee flood control projects throughout California’s Central Valley. Cutoff walls are widely used because they can be implemented within an existing right of way in either heavily urbanized areas with limited access, or in high-value crop agricultural areas. The most commonly used seepage cutoff wall types are soil-bentonite (SB), soilcement- bentonite (SCB), and cement-bentonite (CB). Contract values for cutoff wall rehabilitation projects in the Central Valley range from several millions of dollars to hundreds of millions of dollars, and play a significant role in the reduction of flood risk in urban and rural areas. However, recentlycompleted construction of several levee improvement projects has shown limitations and inconsistencies among the commonly used technical specifications for construction of seepage cutoff walls. These limitations were evaluated by practicing engineers involved in different stages of cutoff wall design and construction. This paper describes the specification areas that typically generate design and construction issues. Recommended improvements to specifications are suggested to address these issues. The paper’s topics include: the applicability of the different types of cutoff wall materials and construction methods, quality control testing requirements, backfill gradation requirements, mixing procedures, and settlement criteria for backfill.INTRODUCTIONFlood control projects on the Sacramento and San Joaquin rivers in the Central Valley region of Northern California consist of a large system of reservoirs, bypasses, and levees. The thousands of miles of levees within the system were largely constructed and raised by local entities as need arose; this construction occurred prior to the development of modern design and construction techniques. The majority of these levees were initially constructed to protect land for agricultural development; however, a significant portion of these areas have become or will soon be urbanized. This urbanization has historically occurred in locations right up to the levee footprint. This expedient form of historical levee construction, when combined with adverse riverine geomorphology, urban development, and productive agricultural regions, has led to a levee systems with severe seepage performance issues in a real-estate-constrained setting."

Jan 1, 2015

By David R. Winfield

I would like to thank you for spending the time with me today to review the FLIR PathFindIR thermal imaging camera system: It is truly an innovative safety system that has the added benefit of offering increased efficiency Our company the Winsted Group, specializes in mobile video systems that are fully customizable to address standard and unique operational requirements in a variety of industries from heavy equipment cameras to police and military digital recording systems, high end video camera systems are a hallmark of Winsted?s product line. The use of thermal imaging camera systems to enhance mobile safety is a relatively new concept as it relates to their use in both transportation and heavy equipment operation. This technology, like so many before it, has been adopted for civilian use from its military roots. The identification of enemy combatants through their heat signature has given our troops a decisive edge in military operations in total darkness Likewise, the ability to discern people and objects that give off heat is a significant step forward in collision and accident avoidance. The PathFindIR camera system that I am demonstrating today is so advanced that it cannot be exported outside of continental North America without a US government approved export license I would like to commence my presentation with a short video clip that discusses the technology associated with the FLIR PathFindIR Thermal Imaging camera systems. The video demonstrates the operational effectiveness of thermal imaging camera systems installed on a vehicle operating on the roadway at night, of course there are definite parallels to use in a mining environment, primarily the fact that lighting is limited and the chance for vision limiting dust is ever present. We are, of course more concerned with personnel safety in our mines than encountering wildlife on the roadside. From the same perspective, the transport driver is just as concerned with encountering a stalled vehicle as our mine truck operators are with other mine traffic.

Feb 1, 2008

By K. Premlall, R. M. Dire, H. Bissett, D. Delport

Tungsten carbide is a fine grey powder. It can be formed into shapes by compacting with the addition of a binder. Spherical particles are generally preferred in additive manufacturing as they pack together more efficiently than non-spherical particles, promoting a uniform powder bed density, better flowability, and elimination of internal cavities and fractures, resulting in a better quality of final product. The particle shape of powders can be transformed into spherical through the process of spheroidization. However, due to its high melting point, tungsten carbide could be difficult to spheroidize. Tungsten carbide was spheroidized using an inductively coupled radio frequency plasma at various plate powers between 9 and 15 kW. The influence of additional H2 in the sheath gas on the chemical composition of the tungsten carbide product was also investigated by means of XRD, which indicated that WC is converted to W2C at higher H2 concentrations. Optical analysis of SEM micrographs indicated that the spheroidization ratio increased with increased plasma energy.

Apr 1, 2021

By Michael V. Wolski, Ryan O. McCarter, Kenneth A. Johnson

"The Central Subway is Phase 2 of the San Francisco Municipal Transportation Agency’s (SFMTA) Third Street Light Rail project and will extend the existing Phase 1 initial operating segment from its current connection to the Embarcadero line at Fourth and King streets along Fourth Street to Market Street, under the Bay Area Rapid Transit (BART) and Muni Metro tunnels and then north beneath Stockton Street to Chinatown (Fig. 1).Total new track to be constructed as part of the Phase 2 work consists of approximately 734 m (2,410 ft) of surface track and 2,636 m (8,650 ft) of tunnels. The tunnels were constructed as twin, singletrack bores by two tunnel boring machines (TBMs) (Johnson, 2014) moving north from the southern end of the launch box under the I 80 freeway between Bryant and Harrison streets. North of Chinatown Station the TBMs continued another approximately 683 m (2,240 ft) to a retrieval shaft near Columbus Ave. at Washington Square. The project also includes five cross passages to connect the two tunnels, and three underground stations (the Yerba Buena/ Moscone Station, Union Square/Market Street Station and Chinatown Station.)Excavation of the twin tunnels was performed with two TBMs, with both TBMs driving northward from the launch box. TBM excavation was performed such that the location of the machines was staggered to separate the active excavation faces by a minimum of 91 m (300 ft) between headings. This minimum separation was maintained until the first TBM arrived at the retrieval shaft plug, at which time the separation requirement was relaxed.Excavation began with the “southbound” (SB) tunnel which will ultimately accommodate the southbound TBM light rail trains followed by the second TBM in the “northbound” (NB) tunnel. With the completion of the drives in June 2014, cross passage excavation then began and was completed in April 2015. Overall, construction of the Central Subway tunnels was a success considering the nature and complexity of the project. Additional details of the completion of the Central Subway tunnels are presented in another paper from the RETC 2015 conference (Leong et al., 2015)."

Jan 1, 2015

Reduce dust exposure of longwall shearer operators by keeping them upwind of the primary cutting drum. Approach Use a different coal cutting sequence by cutting from headgate-to-tailgate, making the cleanup pass from tail-gate-to-headgate. How It Works The cutting action of the shearer drum is usually the primary source of respirable dust at longwall shearer faces. Dust exposure of the shearer operator is deter-mined by his position relative to the lead drum, which is normally in the raised position taking a full sump. On long-wall faces where the cut pass is taken from tail-to-head, against the primary airflow, the shearer operators must remain at their controls, on the return-air-side of the primary dust source, to maintain proper control. A simple method to lower shearer operators' dust exposures is to extract the primary coal from head-to-tail, thus positioning the operators up-wind of the lead cutting drum. The bottom coal is then cut, and the floor cleaned by the trailing drum during the tail-to-head cleanup pass. This sequence places the primary dust source, the cutting action of the shearer drums, on the return-air side of both shearer operators, except when cutting out at the longwall headgate.

Jan 1, 1984

By D. D. Ndenguma

This investigation compares the results from an experimental and numerical study of air flow in a scaled-down underground coal mine model. This was done in order to determine if numerical analysis can be relied upon when searching for ventilation solutions to control high concentration of coal dust and methane gas in underground coal mines. Steady state analyses were used to identify flow patterns and recirculation regions within the mining section while transient state analyses were used to determine the time taken to extract the initial air from the model. The agreement between the experimental and numerical results indicates that numerical modelling is useful in this regard. The study went further to devise a method of determining the optimum position of the jet fan that is responsible for mine-gas dilution at different stages of mining.

Jan 1, 2014

By Tonkin D. A

Poor performance in the several stages of the magnetite recovery circuit, coupled with poor desliming through inefficient and over- loaded desliming screens, led to excessive magnetite consumption. An accurate and reliable sampling programme was established covering all outlets of the plant. Emphasis was placed on frequency of increments in an endeavour to detect extreme conditions of short duration. Systematic checking of the entry points to these outlets than identified those sections of the recovery circuit at fault, namely magnetite recovery separators and the heavy media cyclone product rinsing screens. More product rinsing water was provided, and modifications to the rinsing screens improved the efficiency of these units. Consistency of operation through automatic control of level eliminated the sudden massive losses in the magnetic separators. Load on the recovery circuit was then reduced by improvements to the raw coal desliming screens. A 50 per cent reduction in magnetite consumption was achieved.

Jan 1, 1974

By Charles F. Hickey, Eric B. Kula

Thermomechanical treatments applied to the maraging steels include a) cold working in the austenitic condition at 650°F, followed by transformation to martensite and aging, b) cold working in the murtensitic condition and aging, and c) cold working in the aged condition with and without subsequent reaging. The strength increases in these steels are very small compared to the increases observed in conventional carbon and alloy steels. The changes that are observed are compatible with the strengthening mechanisms operative during thermomechanical treatment of conventional steels, however. Differences are caused by the absence of a carbide precipitate and the low work-hardening rate in both the solution-treated and the aged conditions. ThE 18 pct Ni maraging steels represent a class of steels which are finding great interest for high-strength applications.1~2 They are essentially carbon-free, and contain 7 to 9 pct Co, 3 to 5 pct Mo, and 0.2 to 0.8 pct Ti. Although austenitic at elevated temperatures, they can be air-cooled to room temperature to form a martensite, which because of the absence of carbon is relatively soft. On subsequent reheating age hardening occurs and strength levels of 250 to 300 ksi yield strength can be attained. These steels appear to be particularly suitable for studying the response to various thermome-chanical treatments for additional reasons other than the obvious one of attempting to improve their already attractive properties. Thermomechanical treatments can be defined as treatments whereby plastic deformation, generally below the recrystal-lization temperature, is introduced into the heat-treatment cycle of a steel in order to improve the properties. With an absence of intermediate transformation products on air cooling the maraging steels have good hardenability and hence can readily be cold-worked in the austenitic condition prior to transformation to martensite. Further, they can be worked in the martensitic condition prior to aging, and even can be deformed in the fully aged condition. Finally, it is of interest to compare their re- sponse to that of the more conventional alloy and carbon steels, where the role of carbides is important in the strength increase by thermomechani-cal treatments. The thermomechanical treatment of conventional steels has been the subject of a recent review.' I) MATERIALS AND PROCEDURE The steel used in this investigation was a commercially produced vacuum-melt heat, which had been rolled to 0.090 in. and mill-annealed. The composition of the alloy was as follows: 0.02 C, 0.08 Mn, 0.10 Si, 0.009 P, 0.009 S, 18.96 Ni, 7.34 Co, 5.04 Mo, 0.29 Ti, 0.05 Al, 0.004 B, 0.01 Zr, and 0.05 Ca. Unless otherwise stated the heat treatments used were the standai-d solution treatment at 1500°F for 1 hr, air cool, followed by a 900°F, 3 hr age. In this condition, the material exhibited 232 ksi yield strength and 239 ksi tensile strength. Mechanical properties were determined by Vicker's hardness measurement (20 kg) and by tensile tests on standard 1/2-in.-wide, 2-in.-gage-length sheet tensile specimens. Notch tensile tests were run using the 1-in.-wide NASA type, edge-notched specimen.4 Fracture-toughness determinations were made on 3-in.-wide, center-notched, fatigue-cracked specimens, following the recommendations of the ASTM Committee on Fracture-Toughness Testing.4 An electric-potential technique was used for measuring the crack size at the onset of rapid crack propagation5 which is necessary for calculations of Kc, the critical stress-intensity factor under plane-stress conditions. The critical stress-intensity factor under plane-strain conditions KI, was also calculated, using the stress at which the first observable crack growth occurred. 11) RESULTS A) Cold-Worked in the Austenitic Condition. The reported M, temperature for the 18 pct Ni maraging steel is about 310°F.1 Therefore, a temperature of 650°F was selected as suitable for rolling in the austenitic condition. Specimens were solution-treated at 1500°F for 1 hr, air-cooled to 650°F, and rolled varying percentages from 0 to 60 pct, at 20 pct reduction per pass. Tensile and hardness properties after aging at 900°F for 3 hr are shown in Fig. 1. The tensile strength increases from 253 to 271 ksi and the yield strength from 247 to 265 ksi as a result of a reduc-

Jan 1, 1964

By Helen D. Robinson

The seawalls that surround Ellis Island were constructed in the early 1900s and now show varying degrees of deterioration. An innovative approach to the structural repair of the seawalls was developed, which consisted of the use of micropiles for stabilization of vertical and horizontal seawall movements. The micropiles were installed through the existing seawalls and penetrated through a thick overburden, consisting of soft alluvial deposits and relatively hard glacial till, and were bonded into Manhattan Schist. Drilling of the micropiles often encountered timber and other obstructions. The selection of micropiles for stabilization of the seawalls offered significant advantages over other foundation systems and over alternative soil improvement techniques. They allowed drilling through a variety of materials without the need for significant retooling or changes to the drilling procedure. This reduced the impact of foundation construction on the sensitive historical landscape and structures, and prevented the need for significant foundation work from the water side of the seawalls. In addition, micropiles offered relatively high installation rates and flexibility to adapt to the varying conditions along the seawalls.

Jan 1, 2008

By R. Barany

Thermodynamic calculations pertaining to the minerals gibbsite, kaolinite, halloysite, and dickite have been hampered by the lack of adequate heat and free energy of formation data. Previous data for gibbsite were highly uncertain, and there were no data for the other three substances. By use of hydrofluoric acid solution calorimetry, the Bureau of Mines derived heat of formation values from the elements and from the oxides for the four substances, and the data were combined with known entropy values to obtain the corresponding free energies of formation. The results show that gibbsite and halloysite are thermodynamically unstable with respect to the oxides (a- alumina, a- quartz, and liquid water) at 298.15° K,, while kaolinite and dickite are only moderately stable (to about the same degree), The instability of halloysite, in comparison with kaolinite and dickite, results in a 60°-lower equilibrium decomposition temperature.

Jan 1, 1961

By Michael E. Ameel

The vibrated beam method of installing a vertical barrier wall is one of the least applied techniques, yet given certain site conditions and constraints, it is a cost-effective and proven method of controlling lateral groundwater flows. A recent full-scale application of this technique demonstrated its usefulness at an active manufacturing facility located in Northern Wisconsin. At this site, a 3,233 foot long cutoff wall was keyed into an underlying bedrock, which was located an average of 40 feet below the ground surface. Using a slag cement-clay based slurry, a 1E-7 cm/sec or less, nominal 4-inch wide cut-off wall was constructed using the vibrated beam method. Challenges included working around an active manufacturing facility with minimal access to the work area; installing the wall through a very dense glacial till; minimizing soil excavation volumes of potentially impacted soil; and, working around and adjacent to numerous active utility lines without impacting the facility operations. At utility locations, the vibrated beam wall was supplemented with a jet grout panel wall, without the need to bypass or otherwise interrupt any of the plant?s utilities. Quality control consisted of the monitoring and measuring of slurry parameters, survey control, and real-time monitoring and documentation of all critical barrier wall installation parameters. A vibration monitoring plan was also implemented to measure vibrations at utilities and adjacent facility structures. Proper equipment selection, significant up-front planning and close coordination with the facility resulted in a safe and successful project. The work was completed ahead of schedule during the 2009 construction season.

Jan 1, 2010

By Steve Custer, Tim Kahl, Sue Parker

"The primary objective of the Barrick Goldstrike expert system is to achieve the desired liberation size for the autoclave circuit while maximizing throughput. In addition, when downstream limitations (autoclave circuit or others) restrict the milling circuit tonnage the expert system further improves grinding product size. Since its implementation, the expert system has provided expected throughput improvements while improving or maintaining circuit performance.Barrick Goldstrike and MinnovEX Technologies Inc. teamed up to install an expert system to control Line I and I1 of the autoclave grinding circuits. The dissimilar equipments of the two grinding circuits coupled to different production objectives, skepticism among operators, and the variability of the ore types processed in each line challenged the implementation.To ensure implementation success, Barrick Goldstrike dedicated four administrators full time to the project. The system administrators included two metallurgists, a process control engineer and a mill trainer. As usual, the control room operators were the experts who provided the operational logic for the foundation of the control system. The administrators and all eleven of the control room operators signed off on acceptance of the system. Current online utilization is 95%.INTRODUCTIONThe grinding circuit for Barrick Goldstrike’s autoclave process consists of two SAG Mill Ball Mill lines. Line 1 grinding circuit is comprised of a 22 by 8 foot, 2500 horsepower Allis Chalmers (AC) variable speed SAG mill, followed by a 12.5 by 14 foot, 1250 horsepower AC ball mill, and a 13.5 by 18 foot, 1800 horsepower Dominion ball mill in parallel. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1352 Nordberg Omnicone crusher (4.5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The ball mill circuit is closed with 6 Krebs super D20 cyclones. Line 2 grinding circuit is comprised of a 24 by 12 foot 4000 horsepower Fuller variable speed SAG mill followed by a 16.5 by 30.5 foot 5000 horsepower Fuller ball mill. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1560 Nordberg Omnicone crusher (5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The line 2 ball mill circuit is closed with 12 Krebs super D20 cyclones. The underground Meikle ore is typically fed through Line 1. Achieving the desired product size is critical for successful processing of Meikle ore. Open pit Betze ore is fed to Line 1 when Meikle ore is unavailable. Line 2 processes Betze ore exclusively. Throughput is maximized when processing Betze ore as the product size is less critical. The products of these two circuits are combined as feed to the autoclave circuit. The ore types and the autoclave circuit demands determine the required grinding circuit product size and maximum combined mill feed tonnage."

Jan 1, 2001

By Robert A. Cummings, Madan M. Singh

In April 1984 a subsidence depression formed directly beneath a two-story frame residence, near Linton, IN, causing 2 ft of separation between the floor and walls, and damaging both the foundation and interior of the building. The Office of Surface Mining undertook the rehabilitation of the area under its emergency response program. This paper describes the investigation performed to determine the cause, severity, and extent of the problem. Abandoned mine workings were found approximately 55 to 60 ft below the house. Based on the findings, remedial measures were prescribed. An abatement program consisting of grouting the mine voids was recommended, and specifications prepared. These were implemented, and the area has been successfully stabilized.

Jan 1, 1986

By K. Oraee

Mining of copper ore and the related industries play an important role in Iran?s economy. Copper ore production in Iran accounts for 75% of the total production in the Middle East. All activities related to copper, that is, exploration, production, refinement etc are owned and managed by state owned companies. Decisions have been made to privatize all these activities. To assess the success of this privatization process, different components of the industry must be subject to economic analysis. In this paper, the cost estimation of all operations has been carried out. The total potential and attainable revenues have also been estimated using historical data available from the industry. Risk is a major factor in all mining activities and the copper industry of Iran has been subject to risk factors arising from many internal and external variables. These variables have been recognized and their effects evaluated. The effect of risk on the economic feasibility of the operations in the industry has also been analyzed.

Jan 1, 2011

By Julius Roth

Flyrock is the source of most of the injuries and property damage in a majority of blasting accidents in surface mines. A quantitative correlation between shot conditions and maximum flyrock range can be used to define a "blasting area" in which no personnel or equipment should be present during a shot. The approach used was to develop a model that correlates shot conditions and initial flyrock velocities and permits computation of flyrock range from ballistic trajectories. The Gurney formula for velocity of explosively-propelled plates or fragments was adapted to explosively-propelled flyrock from vertical rock faces or from bench tops. The modified Gurney formula was then "calibrated" with measured flyrock velocities from mining and explosives literature. Charts were then developed for possible field use which give maximum flyrock range as function of shot conditions. The model indicates that for flyrock from vertical faces, borehole diameter, minimum burden and height of explosive column define maximum flyrock range for a given explosive, shot in a given rock. For flyrock originating from bench tops, flyrock range appears to be controlled by the distance of the top of the explosive column to the borehole collar, by total explosive load per borehole and, to a lesser extent, by borehole diameter.

Jan 1, 1979

By L. V. Bell

"The gold deposits of the Caribou mine are representative of those of the Province of Nova Scotia as a whole. The ore shoots within the deposits, in common with those elsewhere within the Province, are associated usually with interruptions or irregularities in the broader and uniform fold structures. The structural factors localizing ore deposition as applied more specifically to the Caribou mine are demonstrated chiefly by the close relationship of the two principal ore shoots, known as the main orebody and the 'high-grade' vein, with a pitching drag fold developed in the southeast limb of the major northeast-southwest trending anticlinal fold or elongated dome that constitutes the primary structural feature of the Caribou gold district. It is of interest to note that the evidence indicates that this drag fold, in common with other folds subsidiary to the primary fold, formed as a result of movement similar in nature to that which caused the primary fold itself. Presumably, therefore, these folds are coincident in time.The property described here as the Caribou mine is an amalgamation of two adjacent properties formerly known as the Ross and the Nova Scotia Gold, but which since 1934 have been controlled and operated as a unit by The Consolidated Mining and Smelting Company of Canada, Limited. The Caribou mine is situated in the Caribou gold district about 45 miles to the northeast of the city of Halifax and about 6 miles to the north of the Moose River gold district.The history of mining at Caribou dates back to 1867. The first recorded gold production is for 1869. From 1869 to 1933 the gold produced from the mines of the Caribou district aggregated 47,249 oz. from 93,234 tons of ore treated. The grade of the ore on the basis of the gold actually recovered from the district would thus average 72 oz. gold a ton, which, as will be noted from the following, is precisely the grade of the ore treated from the Caribou mine during operations by The Consolidated Mining and Smelting Company. These operations commenced in September, 1934, and milling on a commercial basis was under way during 1938. Since that time production, apart from a short period in 1945 during which efforts were concentrated on development work, was continuous to early in 1947, when the mine closed down owing to exhaustion of the known orebodies. Gold produced from the Caribou mine by The Consolidated Mining and Smelting Company from September, 1934, to the close of 1946 aggregated 43,205 oz. from 90,754 tons of ore milled; the grade of ore treated averaged 0.50 oz. gold a ton. The indicated average grade of O.S oz. gold a ton for the ore of the Caribou district throughout its mining history ranks somewhat higher than the 0.37 oz. a ton average for the ore milled to date from the several gold districts throughout the Province as a whole according to the production statistics of the Provincial Department of Mines."

Jan 1, 1954

By K. C. Dean

During the investigation of the occurrence of manganese deposits in western United States, the Bureau of Mines collected 2-ton samples from three oxide manganese ores in the Columbia and Elberta Mining Districts, Tooelo and Juab Counties, Utah. To determine the amenability of these ores to standard ore-dressing methods: of concentration, extensive laboratory tests were made. The Wildcat property, one of those sampled, is 7 miles east of Fairfield, Tooele County, Utah. The ore is described as a replacement deposit and occurs along fracture and bedding planes of shale and limestone. Experimental work was done on a sample taken from a stockpile at the mouth of the shaft. The Wildcat manganese ore is intermediate in grade (25.7 percent manganese) and contains clay as the principal gangue constituent. A high-grade product was obtained with high recovery of Manganese by simple washing.

Jan 1, 1949