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By Jerry E. Olson

In 1984, the U.S. Bureau of Mines conducted a mineral survey of the Black Rock Desert Wilderness Study Area (WSA) (NV-020-620), which covers approximately 319,000 acres in Humboldt County, Nevada. About 90% of the WSA is underlain by Pleistocene desert playa sediments; the remainder is comprised of Jurassic-Triassic metamorphic rocks, a Cretaceous intrusive and Tertiary volcanic rocks. Most of the WSA is within a down-dropped fault block of the Basin and Range physiographic province. No mines or evidence of major exploration were identified within the WSA; but five claim blocks within or adjacent to the WSA and zones of anomalous character as defined by the Bureau of Land Management were examined. No mineral resources were identified, but anomalous gold, silver, and indicator element content of samples taken near Pinto Hot Springs indicate resources may exist. Lithium content of samples from near-surface sediments on the desert playa is too low for resources, out geologic conditions are favorable for higher concentrations at depth. Occurrences of zeolites are not considered to be of commercial interest. Approximately 27,000 acres are held under geothermal lease, and most of the WSA is of interest for oil and gas. No evaluation of these commodities was made by the Bureau of Mines

Jan 1, 1985

By E Acu±a, B Prosser, R Alvarez, K Wallace

This paper describes the ventilation analyses performed for the access tunnels at the New Level Mine project (NLMP) at CodelcoÆs El Teniente operation outside of Rancagua, Chile. This new mine is anticipated to reach a final production of between 137 and 180 kt/d. Production from the NLMP is scheduled to start in the year 2017. The main access tunnels (MAT) are approximately 9 km in length, with one for personnel and supply access and the second one for ore extraction through a conveyor system. These two tunnels are a critical component of the initial stage 1 development and will be constructed independently of the existing mine workings. The tunnels were originally designed to be constructed with two tunnel boring machines. However, later analyses changed the construction approach to a conventional drill and blast technique. Because the design included two mid-tunnel ramp-to-surface connections, conventional mining methods would allow for development of the tunnels with multiple working faces to achieve a more rapid schedule. This paper presents the initial baseline considered for the ventilation design and the optimisation methodology applied by Codelco to minimise the airflow and pressure requirements of the ventilation system. Modifications to the design resulted in the addition of strategic airways and raises that could provide a saving of approximately 1 MW, when compared to the original design.CITATION:Acu±a, E, Alvarez, R, Wallace, K and Prosser, B, 2013. Ventilation considerations for the new level mine project access tunnels, in Proceedings The Australian Mine Ventilation Conference , pp 203-206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By R. Bruce Tippin

because of the mineral's high monetary value and the spotty occurrence of free gold in the deposit. Setting up a plant sampling procedure by simply applying the usual statistical sampling theory was questionable. Two sampling concepts were considered in the sampling study: o a sufficient number of assays can be taken such that the average determined from these individual samples represents a known quantity of ore. o a sufficient weight of sample can be taken such that when assayed it represents a known quantity of ore. The test program included evaluation of sampling techniques, sample preparation and analytical methods. The overall sampling program is depicted in Figure 2.

Jan 1, 1985

By Ping Long, Bin Yang, Jian Wu, Xiumin Chen, Wenli Zhang

In this study, the analysis method of trace element in pure indium using glow discharge mass spectrometry (GD-MS) has been established by correcting the analysis result, which was obtained from non-standard quantitative method of GD-MS. The effect of instrument operating parameters, the resolution and isotopes and the pre-sputtering time on the determination results were investigated respectively. The optimized operating parameters of the instrument were obtained as follows: the discharge current was 37.5mA and discharge airflow was 475ml/min. Mass spectral interferences have been eliminated using selected resolution and isotope. The pre-sputtering time was 30 min. 4 trace elements in two pure samples were determined for 6 times. The RSD were less than 20%. The content of trace elements in indium samples was determined by GD-MS and Chemical Analysis Method of Indium which is tested by inductively coupled plasma atomic emission spectrometry, respectively. The results were consistent with each other.

Jan 1, 2016

By Dairo E. Chaverra, Carlos Argumedo‑Jimenez, Oscar J. Restrepo‑Baena

This paper presents the results obtained by processing a gold and silver telluride mineral concentrate from a mine in Colombia. An acid wash, also known as acidification, was carried out, followed by oxidation with nitric acid as a pretreatment. Cyanidations of the pretreatment residues were carried out and the results were compared with results from cyanidations of base materials. The removal of carbonates in the acidification, a tellurium extraction close to 90% during the pretreatment, and a 30% improvement in the gold recovery compared to the conventional process were achieved.

Nov 8, 2023

By Ronald D. Hill, Elmore C. Grim

Coal-haul and mine access roads are defined as any road constructed, improved or used by the operator (except public roads) that ends at the pit or bench. These roads constitute approximately 10% of the total area directly disturbed by the surface mining operation(l). In some cases, the land disturbed by haul roads exceeds the area included in the mining operation. Studies (2 and 3) of the U. S. Forest Service in eastern Kentucky show that typical contour mining roads exhibit poor alignment, excessive grades, insufficient strength and durability, and poor drainage. Mine roads in other Appalachian- States, particularly where contour mining is practiced, appear much the same as those in Kentucky. Access roads(4) were also found to be a large source of sediment. It is possible that of the sediment that finds its way into the streams as much (or even more) originates from the haul roads as from the mining operation. Most roads are built as cheaply as possible, and good road-building design and practice are ignored. Maintenance schedules are generally inadequate, and upon completion of mining, haul roads are usually abandoned, with little or no attempt made to bed them down(5 ) . Such roads deteriorate very rapidly (Figure 68). Area mining, which is practiced in flat to gently rolling terrain, presents fewer haul road related environmental problems. These roads through necessity are generally well engineered because of the heavy equipment using them, such as 240 ton (217 metric ton) haul trucks. They must have wide beds, good alignment, and adequate drainage to permit coal haulers to run at top speed during all seasons of the year. Excessive dust can be a public nuisance and a driving hazard, and it is hard on equipment. Calcium chloride and sodium chloride have proven to be effective materials for controlling dust. Two applications during the summer when the ground surface is moist at the rate of 1/2 pound per square yard (.26 kilograms per square meter) (3 1 have been suggested. Th4 most common procedure is to keep the roads wet by using water trucks. Sediment that reaches the streams can be traced to one or more of the following five basic phases of haul-road life:

Jan 1, 1974

By J. F. Childs

"INTRODUCTION Comprehensive overviews of the world-class talc deposits and related prospects in Montana were published by Olson (1976) and by Berg (1979). Both of these compilations include detailed descriptions and maps of the talc deposits and occurrences and were followed by a regional map and summary descriptions of the talc deposits published by Van Gosen et al. (1998). More recent publications, descriptions and field guides for some of the deposits include Underwood et al. (2014), Cerino et al. (2007), and Cerino (2002). The present paper focuses on some of the more recent ideas regarding talc formation that have developed since the publication of the earlier overviews. Olson (1976) reported that talc production from the deposits in southwestern Montana was over 200,000 tons in 1974 and that talc production had doubled between 1969 and 1974. The last year for which the U.S. Geological Survey published production records for talc by state was 1993. Production in Montana in 1993 was 350,000 tonnes (Virta, 1994). Remaining reserves are substantial at all three of the producing mines in the district. Minerals Technologies Inc., the parent company of Barretts Minerals Inc., stated in its 2014 annual report that it has reserves of 2,791,000 tons of talc. Imerys stated in its financial report for 2014 that it had 19,638,000 tons of proven and probable talc reserves at its North American mines. Although the Imerys reserves were not reported by individual mines or states, a large proportion of the total reserves would likely consist of the reserves at the Yellowstone mine, located south of Ennis, Montana. Talc mined in southwestern Montana is of high purity and is the quality used in a wide variety of applications including paints, ceramics, plastics, rubber, coatings, agriculture, cosmetics, and pharmaceuticals. GEOLOGIC SYNOPSES FOR MAJOR MINES AND COMMENTS ON REGIONAL DISTRIBUTION OF TALC OCCURRENCES The general geology of southwestern Montana is shown in Figure 1along with the locations of the three producing talc deposits in the area and the extent of pre-Belt marbles that host all of the talc mines and prospects. The term “pre-Belt” is used in the present paper because zircon and other radiometric data developed in recent years indicates that the metamorphic rocks that form the crystalline basement for the middle Proterozoic Belt basin in the Dillon Tectonic Block of southwestern Montana includes both Archean and Paleoproterozoic rocks (O’Neill et al., 1996; Foster et al., 2006; McDonald et al., 2012). An envelope or “corridor” has been superimposed on the geology in Figure 1 which encompasses all of the talc deposits that have a significant resource. This “talc corridor” will be discussed in later sections of this report. The more important talc deposits are discussed in this report section."

Jan 1, 2016

By R. E. Mitchell

Environmental Impact Assessment (EIA) is the accepted method for evaluating proposed mining and other industrial projects to obtain regulatory approval and to help companies plan for responsible development. Another evaluation system becoming increasingly more common for proposed projects is the Environmental, Social and Health Impact Assessment (ESHIA). An ESHIA differs from an EIA for its more comprehensive and inclusive approach to evaluate potential impacts on public health, and its ecosystem services approach to assessing biodiversity impacts. An ESHIA may also be required by certain lenders for financing major projects. Conducting an ESHIA for a proposed mining development is not without its challenges, with costs, scheduling, regulatory concordance and other constraints to be considered. This paper examines some benefits and challenges of ESHIAs and summarizes lessons learned using a case study approach.

Jan 1, 2012

By Charles W. Robinson

Si bien, durante un breve periodo la industria internacional del hierro ha experimentado diversos problemas dado el exceso de oferta en relación con la demanda. En este sentido, el objetivo del texto radica en estimular los grandes inversiones que se requieren para satisfacer la demanda futura del mineral de hierro. Para ello, se describe la historia de la comercialización internacional del hierro, las fases de desarrollo, las tendencias en el precio del mineral, el desarrollo industrial del hierro en Australia y las características especiales de la industria como: ausencia de normas para el producto, estrecho enlace entre técnico entre comprador y vendedor, falta de flexibilidad de la demanda mineral de hierro, dependencia de transporte de costo y la fórmulas de organización entre propietarios y administradores. Asimismo se revisan los avances en la industria mineral del hierro, como las factores que influyen en su producción

Nov 20, 1969

By Craig Ammar

JAMIE DAVIS: Our next speaker is Craig Ammar. He's director of equipment management for Cyprus Climax Metals Company. He has, prior to this assignment, been responsible for maintenance at Bagdad Copper, Cyprus' Miami smelter, and Thompson Creek. Like Jerry, he's very shy and retiring, and doesn't have any strong opinions about maintenance. INTRODUCTION CRAIG AMMAR: The ultimate goal behind implementing a proactive equipment management process is to provide capacity assurance and ultimately increase an organization's ability to generate revenue while reducing operating costs. Targeting such lofty objectives has brought many an organization to its knees, utilizing new maintenance techniques, concepts, and technology aimed at making our lives better and more organized. The root cause of such frustration generally stems from a lack of understanding or support for the fundamentals of implementing a proactive equipment management process. There are just two types of maintenance programs, reactive and proactive. It's an established fact that you need a little of both to run an effective equipment management process, obviously more of one (proactive) than the other. Here are some telltale signs that your equipment management process is in trouble: -Maintenance is performed as a knee jerk reaction when equipment fails. -Repeated and frequent equipment failures occur, with no focus on eliminating the root cause. -Sketchy, inconsistent, unclear preventive maintenance is performed or there is no support for the preventive maintenance process. -No predictive maintenance technology process is in place, or little support for predictive maintenance exists. -Less than 50 percent of your work is generated by the maintenance group resulting from inspections.

Jan 1, 1998

By Thomas L. Hurst, Joseph M. Hans

INTRODUCTION The former Shiprock uranium mill site is located in the community of Shiprock, New Mexico on a bench overlooking the San Juan River (Figure 1). Both Shiprock and the mill site are located on the Navajo Indian Reservation. The millsite was built on a 230 acre tract leased by Kerr-McGee Oil Industries Inc., and was operated from 1954 to 1963. The Vanadium Corporation of America and its successor, the Foote Mineral Company, operated the mill from 1963 to 1968. During its entire operation, 1.5 million tons of uranium ore was milled producing 3711 tons of U308 concentrate. The concentrate was sold to the former U.S. Atomic Energy Commission. During milling, the ore was crushed to less than 35 mesh and acid leached to remove the uranium. The [ ] uranium was removed from the leach solution by solvent extraction and the uranium-barren solution discharged into raffinate ponds for disposal by evaporation and seepage. The spent solids (tailings) were pulped with waste process fluids and water and discharged to form tailings piles. The piles (ponds or dams) were formed with earth starter dikes. The dike walls were then raised using the separated sand fraction of the tailings. The slime fraction of the tailings were discharged into the diked impoundment. Since only a small fraction (0.25 percent) of the ore was U308 by weight, most of the ore bulk ended up as wastes. The wastes contain nearly all of the uranium decay chain radionuclides present in the ore except uranium. The mill was shut down and partially dismantled before the lease expired in 1973, and the remainder of the mill and wastes reverted back to the Navajo Tribe which was the lessor. Portions of the millsite were then occupied by the Navajo Engineering and Construction Authority (NECA), a Tribal enterprise. In order to provide skilled personnel to operate earth moving equipment, a heavy equipment operator's training school was also established on the mill site and was administered and operated by NECA. The U.S. Public Health Service (PHS) and the Environmental Protection Agency (EPA) staff conducted radiation surveys at four inactive uranium millsites on the Navajo Reservation in April 1974. During the survey of the Shiprock millsite, it was noted that the training activities were degrading its radiological condition. Both the PHS and EPA staff recommended that the training activities be directed towards the decontamination of the millsite area and interim stabilization of the tailings piles. Preparation for the decontami-nation work commenced in April 1974. In order to facilitate the decontamination activities, the mill site and its contaminated environs were divided into major areas labeled A through F (Figure 2). Areas A, B, and C are defined as "perimeter" areas and contained surface contamination ranging from 5 to 30 cm deep. Area D defined the mill yard and contained contamination ranging from 0.6 to 5.5 m deep. Area E contained several raffinate ponds which were removed to line up the northwest boundary of the tailings pile and to move the contaminants away from the vicinity of the occupied on-site buildings. The contaminants in Area E ranged from 0.05 to 5.5 m in depth. Area F encompassed the ore storage yard. Contaminants in this area ranged from 0.18 to 1.2 m deep. Washes, however, had contamination exceeding 7.6 m deep.

Jan 1, 1981

By Dean Lindsay, Inna Dymov, Mariam Melashvili, Jim Smolik, Chris Fleming

"This paper presents results from the proposed cyanide detoxification circuit for Seabridge Gold’s KSM project. The proposed flowsheet uses a two-stage CCD (counter-current washing/decantation) circuit to transfer the flotation products CIL(carbon-in-leach) barren solution to a SART process (Sulphidization, Acidification, Recycling of precipitate, and Thickening of precipitate) to recover copper and free cyanide from the copper cyanide complex. The SART barren solution is then treated by an AVR process (Acidification, Volatilization of HCN gas, and Reneutralization) to concentrate the cyanide that was liberated in SART for recycling to leach. The washed CIL barren pulp (the CCD underflow) is treated with the SO2 /Air process to oxidize residual cyanide.The goal of this complex flowsheet is to recover and recycle as much cyanide as possible and produce a final effluent containing less than 0.5 mg/L copper and CNWAD at the lowest cost. The SO2/air process is capable of achieving low residual CNWAD (<1 mg/L) in the final product, but the persistence of aqueous copper above the target level has been detected in the treated solution in some instances. The expected high concentrations of copper and cyanide in the KSM CIL barren ( >200 mg/L each species) and the difficulties this might create for the SO2 /air process was a key factor in the decision to consider including the washing, SART and AVR steps in the project flowsheet.The target concentrations of CNWAD and Cu were readily achieved after aging the SO2 /air treated pulp, as would occur in a tailing or polishing pond. This suggests no additional treatment will be required to sustain low levels of these species in the final plant effluent."

Jan 1, 2015

By J. Kemeny, J. Lyons-Baral

"Point cloud technology is now an indispensable tool in geological and geotechnical data collection, interpretation and analysis. Open pit and underground mines of all sizes are regularly collecting point cloud data as Laser Scanning (LiDAR) and Photogrammetry surveying devices have finally become affordable and the workflows fast and efficient. Past challenges of large data processing and manipulation are gone with recent technological advancements in computer hardware and software. These innovations reduce file sizes, ease rendering requirements and allow for the implementation of real-time 3D viewers and surface meshing tools. With its ability to remotely (safely), rapidly and accurately extract large quantities of georeferenced and 3D-oriented data, point cloud technology provides numerous applications to the geomechanical field. The list of uses is continuously growing, so this paper specifically focuses on digital outcrop modeling and digital terrain engineering. INTRODUCTION Point Clouds The high-resolution and increasing availability of point cloud technology is rapidly improving open pit and underground mines’ investigation, interpretation and characterization of site geology and rock mass properties (Kemeny et al., 2015; Lyons-Baral, 2012). LiDAR and photogrammetry are common remote sensing methods employed to measure the coordinates of surfaces in three dimensions (3D), providing the X, Y and Z locations, and typically the reflective intensity and/or the visible three-band color of each point (Figure 1). LiDAR uses either a time-of-flight or phase-shift measurement of a laser beam reflected off targeted surfaces and received back into the device. Photogrammetry generates point clouds by merging multiple overlapping photographs and uses stereographic plotting to define the locations of object points in 3-D space. These methods can be deployed from airplanes, unpiloted aerial systems (UAS or drones), tripods, land vehicles, and even in a mobile backpack shown in Figure 2. RADAR, Total Station-Prism and other remote sensing systems also offer very precise “point clouds”, but this paper does not address these due to their higher cost and lower versatility and mobility. Technology In the past few years point cloud acquisition device prices have dropped significantly, devices have become lighter, smaller and easier to operate, and processing and utilizing the data has also become faster and easier. Device size improvements include mobile backpacks (Figure 2) and handheld mobile LiDAR (CISRO, 2014), allowing mobile scanning in tight spaces both above and below ground or inside and outside of man-made structures. Airborne data acquisition options have expanded dramatically with the spread of UAS technology as seen in Figure 3 (Hexagon Geosystems, 2015). Once UAS usage regulations are sorted out, these versatile machines will be everywhere, offering high resolution coordinate scans, imagery and other remote sensing. While backpacks and handhelds allow access to tight quarters, UAS permit rapid data capture from narrow to broad areas with multiple perspectives reducing data “shadows.”"

Jan 1, 2016

By Bronson Stringham

The close area! relationship of Cretaceous or later intrusive porphyries to larger hydrothermal deposits of Pb, Zn, Au, fig, Cu, Mo, Hg,, and U of similar age in the Basin Range Province, was statistically shown in a recent paper (Stringham1) During the past year this study has been expanded to cover p11 of the larger hydrothermal deposits of similar nature occurring in the entire western United States. The sandstone type uranium deposits of the Colorado Plateau and Wyoming have been excluded since considerable controversy exists regarding their origin. The close relationship between intrusives in general and hydrothermal ore deposits has long been-recognized, but the association involving intrusive porphyry only, was suggested in 1954 when Sales concluded that the formation of porphyry may be an intermediate stage of activity between the development of granitoid rock and certain types of copper deposits. However: he applied this concept to only a few copper deposits. The relationship appears to be true also for a great majority of the hydrothermal deposits of the other metals mentioned above of Cretaceous and later age, at least in the western United States. This situation then leads to the conclusion then when exploring for similar types of hydrothermal deposits of the metals considered one may feel reasonably sure that if an intrusive porphyry of considerable size is. not present he may be facing much greater risk of finding an ore body than if a prophyry were presents Since, there are many intrusive porphyritic rocks which do not seem to be associated with hydrothermal deposit, it is believed that some distinct value can come from the recognition of intrusive porphyry which might be barren as well as the intrusive prophyry which might be productive This paper deals with that problem.

Jan 1, 1960

By F. W. Gray

IN 1922, the writer communicated to the Institute a paper entitled The Development of the Coal Industry in Canada (1), which summarized the considerations set out in a series of papers (2) concerned with coal-mining in Canada which he had presented in 1920 and 1921. This paper contained a forecast by decades, commencing 1920, of Canadian coal production, importation, consumption, and exports, based on anticipated rate of population increase, and continuation of the gradual increase in the per capita rate of coal consumption in Canada that had taken place every year up to 1920. The following comparative statement brings our the differences between the forecast and actual experience:

Jan 1, 1936

By Vladimir Vigdergauz, Sergey Kondratiev

The paper reviews the existing criteria of the formation of particle-bubble aggregates during flotation. It is shown that predictions obtained by these criteria do not completely fit to the interaction between mineral particles and air bubbles. Experimental results of the studies into the influence exerted by molecular forms of collectors on the particle-bubble interaction are reported. Rate of dry spot expansion on the surface of pyrite with various combinations of chemically and physically adsorbed xanthate are examined. It is shown that molecular forms of collectors accelerate the rate of dry spot expansion on the mineral surface after the local rupture of the water film between particle and air bubble. The authors come to a conclusion that the molecular forms of collectors remove water from the interlayer between mineral particle and air bubble during their contact. Similarities of the proposed mechanism with the action of ion-molecular associates of fatty acids and amines are discussed. Reagents with high surface pressure and rate of spreading at the water-bubble interface are required for the effective interfacial dewatering. It is concluded that the value of surface pressure can serve as the criterion for efficiency of physically adsorbed reagents. The low surface pressure indicates weak collecting ability but high selectivity of the collector. Therefore, the presence of the molecular forms of collectors in the sorption layer is the necessary condition for formation of particle-bubble aggregates, and comparison of the surface tensions of collectors could be recommended as the estimation criterion of their flotation activity and selectivity.

Jan 1, 2014

By Charles A. Kumke

In June 1942 , ' the Bureau of Mines selected the Zonia copper mine , near Kirkland , Yavapai County , Arizona , as a property meriting investigation in connection with its search for supplies of strategic minerals for use in the war . The following month , representatives of the War Production . Board conferred with Bureau officials and requested that the property be explored with the object of determining the tonnage and grade of ore that could be brought into production quickly and mined cheaply by open-pit methods . The work wa's designed to verify information submitted by the owners in support of an application for a Government loan. It was essential that the investigations be completed promptly , so that operations might be planned and copper produced for war needs . The investigations called for surface trenching , diamond drilling , and check sampling of underground workings . Unable to purchase equipment for trenching without considerable delay , the Bureau saved time by borrowing most of the necessary items from the Golden Queen mine of the Gold Fields Development Co. at Mohave , Calif. This company , whose engineers had sampled some of the old trenches , had a tentative agreement with the owners to operate and manage the Zonia mine in event the loan was granted . Additional equipment was borrowed from two Governmental agencies . The exploratory work , completed in 16 weeks , was carried on 7 days a week .

Mar 1, 1947

By J. D. Miller, M. Misra

The processing strategy for the effective separation of bitumen from low grade (<l0 weight percent bitumen) Utah tar sands by a hot water process differs significantly from that used for the processing of high grade (> 10 weight percent bitumen) Utah tar sands. Excellent separations (coefficient of separation = 0.9) can be achieved for high grade Utah tar sands by intense hot water digestion followed by a modified froth flotation step. Such a technique is ineffective for low grade tar sands. In order to change the characteristics of the low grade tar sand an attempt was made to enrich the bitumen content of the feed to greater than 10 weight percent by recycle of bitumen concentrate to the digestion stage. However, the quality of the separation was not improved under these circumstances. Similarly feed enrichment by heat treating the low grade feed with recycled concentrate prior to digestion did not improve the separation. More successful separations of low grade Utah tar sands were finally achieved by modification of the viscosity of the low grade bitumen with controlled addition of diluent. These results of the hot water separation tests and variations in the quality of separation are interpreted in terms of the physical properties of the bitumen and the surface bonding forces operative at the bitumen-sand interface.

Jan 1, 1981

By Maurice Grieves

GC. Waterman Mr. Grieves&apos; paper on "Shaft Sinking Today--A Boring Business Tomorrow" in the Dec. 1981 issue of MINING ENGINEERING is an excellent description of recent improvements in speed and costs of shaft sinking. However, shaft boring techniques are not a recent development. In 1935-36, the Idaho Maryland Co. (gold), Grass Valley, CA, bored the vertical 1.5-m-diam Idaho No. 2 ventilation and supply shaft to a depth of 346 m. The equipment was designed and perfected by Branner Newsome and was, I believe, described in "Transactions." Pickands Mather later bored a 1.8-m-diam shaft to a depth of about 305 m using Newsome&apos;s design. The Idaho No. 2 shaft cut through hard gabbro, diabase dikes, soft serpentine, very incompetent ankeritized serpentine and a strong fault zone. The completed shaft did not require timber support; the fault zone was cemented. Equipment consisted of a rotating 1.5-m or 3-m core barrel with a slotted bottom which cut a 76-mm kerf. The cutting agent was chilled steel shot introduced into the slot as needed. The driving mechanism and core barrel were lowered into the shaft, the former secured to the wall and the inshaft "engineer" operated the motors which controlled core barrel rpm and advance. After an advance of 1.5-3 m the equipment was lifted out of the shaft, a half(?) stick of powder cut off the drilled core, and it was hoisted to the surface with a cable attached to an eye bolt at the tope of the core. A "shift" consisted of three men: hoistman, equipment operator (down the shaft), and a surface laborer. Advance was variable as equipment and techniques were perfected. Near the end of the job advance was, as I remember, 1.5-3 m per shift. Costs were, as I recall, about $115/m. Up to 4 m cores were lifted out in one piece and swung to the dump by a stiff leg derrick. The Newsome equipment was relatively inexpensive to build and operate and his method should be (more than?) competetive with the methods described by Grieves. W.E. Hawes The author, in mentioning the South African developments of the cactus grab, ignores the parallel development of the Cryderman mucker in this hemisphere. Perhaps a slightly longer history of blind hold drilling would have been in order. Blind shaft boring got a major boost at the Nevada Test Site, as part of the nuclear weapons development, when it was essential to be able to quickly assess depth for weapons testing. One of the early civilian attempts to utilize this technology occurred when Kerr McGee drilled the shaft at the Section 19 Mine at Ambrosia Lake, NM. This twin masted drill rig belonged to a subsidiary of Kerr McGee, not Shaft Drillers. This was a difficult hole, due to bentonitic shales that decomposed. Later advances in drilling fluids eliminated this problem. The Conoco project referred to is not entirely correct, and needs minor amplification: The depth of the development (not pilot) shaft drilled was 684 m, at a diameter of 3.05 m, with a 2.16 m ID hydratatic casing being installed to a depth of 669 m. Conoco Inc., not Challenger, executed the drilling, however Conoco did use Challenger Drilling Company&apos;s Rig 14-S. Rig 14-S is unique in that it is specifically designed for shaft drilling, rather than being an oil field rig used for this service. All work was planned and directed by Conoco personnel. Deviation of the aforementioned shaft from vertical was 31 cm. Two smaller shafts (pilot shafts) were drilled with the same rig. These smaller ones were drilled 1.8 m in diameter, to depth of 665 m and cased with .91-m-diam casing, to depth of 650 m to be used as pilot holes for 5.5 m diameter shafts. The total elapsed time for all drilling, casing, cementing, and rig moves was 50 weeks. The constraints mentioned of vertical accuracy, torque, wall collapse, rig set up time, lining time etc., pumping out, etc., may not be as serious as the author implies. First, vertical accuracy: The record achieved by Conoco indicates that with reasonable care, good accuracy can be obtained, primarily by having a fair amount of weight in tension, rather than on the drill bit. Second, the amount of torque that can be applied to the drill stem has been greatly increased by the introduction of larger diameter drill stems, such as the new Hughes rig uses. Third, risk of collapse of shaft walls is minimal with the proper mud program. Basically, the walls are supported by the weight of the mud and it is not removed until some type of casing is installed and grouted in. Here in the real challenge of blind drilling shafts to devise a more economical method of lining bored shafts than using steel casing. The remaining issues were minor at Conoco, provided adequate planning and scheduling takes place. An excellent paper, "Shaft Drilling--Crownpoint Project" by Hassell H. Hunter, presented at the Fifth Uranium Symposium in Albuquerque in Sept. 1981 contains details of this project. A combination of blind boring, with enlargement by either mechanical means (boring machine, or tunneling type shield) or slabbing down, with muck removal through a larger bored shaft would seem to be the future trend in shaft development. The economics, especially for wet conditions, favor this concept over conventional sinking, as has been demonstrated at Kerr McGee --Churchrock, UNC--Churchrock and Conoco at Crownpoint.

Jan 3, 1983

By Manis Kumar Jha, D. D. Pathak, Archana Kumari

Treatment of secondary/waste to recover rare earth metals (REMs) is gaining importance due to its increasing global demand, lack of availability of high grade natural resources and huge generation of secondaries. Present paper reports the critical review on available processes for recovery of REMs from secondaries viz. manufacturing scraps, e-waste, industrial residues such as red mud, fly ash, waste water, etc. Hydrometallurgical processes with combination of Beneficiation/ Pyro-/Electro techniques are discussed to recover REMs effectively. The recommended processes require less energy to deliver high purity yield which is one step towards green environment. Salient findings on various methods are reported with recommendations which will be helpful to researchers working in the area of REMs extraction.

Mar 1, 2018