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By K. J. Reid, I. Iwasaki, T. Sabelin

Introduction Occurrences of platinum group minerals (PGM) in mafic and ultramafic rocks in association with Cu-Ni mineralization are well known. Yet for the Duluth Complex, a large body of dominantly mafic igneous rocks in northeastern Minnesota with significant Cu-Ni mineralization (Bonnichsen, 1972; Boucher, 1975; Watowich, 1978; Weiblen and Morey, 1980), little has been published concerning its platinum group element (PGE) contents and mineralogy. In a previous study of massive sulfide rock, sperrylite (PtAs2) was found in nickel arsenide and recovery of arsenide minerals by flotation has been investigated (Iwasaki et al., 1986; Ryan and Weiblen, 1984). Recently, an announcement was made of the discovery of significant quantities of platinum and palladium [peak assay values of 9 g/t (0.27 oz per st)] in an interval of a drill core with disseminated sulfide mineralization 16 km (10 miles) southeast of Ely, MN (Anon, 1985; Sabelin, 1985). This paper describes PGM from the Pt-Pd-enriched zone and evaluates their potential for concentration. Geologic setting The Pt-Pd zone occurs in the South Kawishiwi in¬trusion near its basal contact at 734 to 737 m (2408 to 2418 ft) depth. The South Kawishiwi is one of several minor mafic intrusions that constitute the western margin of the Duluth Complex near Ely, MN (Fig. 1). It is com¬prised of a 70.1- to 350.5-m (230- to 1150-ft) thick sul¬fide-bearing basal unit of troctolite with minor amounts of anorthosite, norite, picrite, and oxide layers overlain by a troctolite unit with interlayered anorthosite (Bonnichsen et al., 1980; Foose, 1984; and Foose and Weiblen, 1986). The basal unit, in which the Pt-Pd zone is found, is markedly heterogeneous in rock type, lacking any coherent internal stratigraphy, and shows evidence of both pre- and post-consolidation faulting (Foose and Weiblen, 1986). Geochemistry Chemical analyses were made on 0.3-m (1-ft) intervals of crushed drill core material (1/4 core, BX size) at 731.5 to 740.7 m (2400 to 2430 ft) depth and the results are presented in Fig. 2. The analytical techniques used were atomic absorption spectrometry for silver, chromium, copper, and nickel; a coulometric titration method for sulfur; and a combined fire assay-DC plasma technique for gold, palladium, and platinum. Figure 2 shows the significant enrichment of platinum and palladium at 734 to 737 m (2408 to 2418 ft) depth; it corresponds to a stratigraphic interval rich in oxide minerals. Average values for platinum and palladium contents over the 3-m (10-ft) interval are 2520 and 2580 ppb, respectively, or 5.1 g/t (0.15 oz per st) platinum plus palladium. Platinum plus palladium contents from individual 0.3-m (1-ft) intervals are as high as 9120 ppb or 9.1 g/t (0.27 oz per st) and average 7.4 g/t (0.22 oz per st) in a 1.5-m (5-ft) interval in the richest part of the zone. The Pt-to-Pd ratio is nearly 1:1 over the entire 9.1-m (30-ft) interval and the platinum and palladium correlate closely with chromium, which ranges from 1.9% to 5.3%. Copper, nickel, and sulfur contents for the drill core interval are also given in Fig. 2. In¬terestingly, the Pt-Pd high corresponds to a depletion in copper, nickel, and sulfur. Mineralogy of the Pt-Pd zone The Pt-Pd zone occurs within an oxide-rich zone or layer that consists essentially of oxide minerals, plagioclase, and olivine. The oxides may constitute as

Jan 1, 1987

By Liuming Wu, Willis Forsling

The complexation of Alizarin Red S (ARS) at the surface of hydrous fluorapatite particles has been investigated at 25.0 C by means of potentiometric titrations, adsorption experiments in 0.1 M NaCI ionic medium, and Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFT) studies. A chemical model describing the reaction at the aqueous mineral surface has been established under equilibrium conditions according to the reaction [== -CaOH2 + HA2 - « _ =PO CaA2 - z + H30&apos;; to (int.) = -5.61 ± 0.02 3 a =PO- logBs-1110(int.) ( ) within the range 8.40 <_ -log[H ] <_ 9.80.] Experimental data were evaluated using the computer program FITEQL on the basis of a constant capacitance model for the electric double layer. The surface complex structure, has been proposed to involve the quinoid and alpha phenolic oxygens of ARS coordinated to the calcium sites on the fluorapatite surface.

Jan 1, 1993

By George H. Davis

The Caribou sulfide deposit near Bathurst, New Brunswick (Figure 1) is illustrative of one variety of strata-bound sulfide deposits. It consists of numerous near-vertical sulfide lenses which are concordant to the foliation and lithologic layering of low-grade metamorphic host rocks. Pyrite is the chief mineral in these lenses, but appreciable quantities of sphalerite, chalcopyrite, and galena are also present. Rocks in the Caribou mine area belong to the Tetagouche Group of Ordovician age. They consist chiefly of (1) quartz-sericite and quartz- sericite- feldspar schists, (2) greenschists, and (3) slate and phyllite. The trends of these steeply dipping rocks define the trace of a tight, steeply plunging fold structure, the Caribou fold (Figure 2). This fold plunges approximately 750 to the north-northwest; its axial plane strikes N.20°E. and dips steeply westward. Sulfide lenses of the Caribou deposit are associated spatially with the Caribou fold. The deposit is located in the fold along the contact between quartz-sericite and quartz-sericite-feldspar schists on the hanging wall and quartz-chlorite-sericite phyllites and graphitic schist on the footwall (Figure 3). Genesis of the Caribou deposit is ambiguous because its strata-bound form suggests syngenetic sulfide deposition, whereas its location within a fold suggests structurally controlled epigenetic mineralization. Acceptability of a particular genetic model rests on establishing the time of mineralization relative to deposition, deformation, and metamorphism of the associated rocks. To establish the timing for Caribou mineralization, the deformational histories of rock and sulfide, respectively, were compared. Epigenetic and syngenetic models can be tested against this interpreted structural history of the Caribou deposit.

Jan 1, 1971

By Douglas W. Barr

If some of you have been through the long hot summer in the southwest, you may find it refreshing to turn your thoughts to the wintertime problems of mineral processing in the northern climates. The purpose of this paper is to point out some of the ways in which heat is gained or lost in the tailing basin operation and the problems that can result if too much heat is lost.

Jan 1, 1980

By John W. Leonard

The typical tunnel boring machine in use on today&apos;s tunnel project uses 15&apos;2-inch diameter cutters at a nominal load of 45 kips per cutter. The cutterhead rotates at a speed of 120 over D revolutions per minute where D is the cutterhead diameter in feet. The typical machine operates about 50 percent of the time. Delivery of a new machine takes 12 to 15 months. The TBM is a specialized tool and not applicable to all jobs. There is a range of job conditions that limit the economic use of a TBM. The machine should provide a thrust per cutter at least twice the compressive strength of rock in psi and up to three times the rock strength is required if in "granitic rocks." The rock strength in psi must be at least three times the cover above the tunnel in feet or the machine may stick. For example, 2,500 feet of cover requires at least 7,500 psi rock to avoid problems. When the RQD&apos;s over a significant distance of the project are less than 50, the TBM becomes support-bound. When a large percentage of the time is spent waiting while the ground is supported, the TBM cannot perform well (See Figure 1). This problem increased inversely with tunnel diameter. We are finding that increasing the RPM&apos;s does not significantly increase progress. The increased RPM results in a substantial decrease in cutter penetration. The explanation for this decrease appears to be vibration, cutterhead drag, or lack of stiffness in the cutterhead (See Figure 2).

Jan 1, 1981

By Gordon A. Gross

Banded siliceous manganese-iron bearing sediments recognized as distinctive facies of Algoma type iron-formation constitute low grade resources of manganese in many countries. Manganiferous facies associated with oxide and carbonate facies of iron-formation have iron to manganese ratios ranging from 0.2 to 2 and commonly about one. Manganiferous facies up to 30 meters thick occurring separately or with other iron-formation facies are associated with cherts, carbonates, shales, turbidites, tuffs and lavas. Primary cherty manganiferous facies and their gondite metamorphic equivalents represent significant manganese resources and are protores for higher grade deposits derived by secondary enrichment processes.

Jan 1, 1982

By Martin C. Kuhn

The use of tritium in manufacturing and its subsequent loss to the local environment in Tucson, Arizona resulted in a great debate relative to the physiological effects of low level radiation. This paper reviews some of the facts of the release and attempts to quantify the degree of hazard encountered by the local community. Some of the difficulties in assessing the true degree of absorbed dose and the assumptions necessary for calculation purposes are presented.

Jan 1, 1981

By Behzad Khorshidi

"The ultimate objectives of the post-tensioned strands are to connect the precast segments into a ring and provide pre-stress in the tunnel circumference. The method involves inserting the strand through the preliminary embedded duct in the precast concrete segments and then tensioning the strand by jack and fastening it. The post-tensioned strand eliminates the necessity of bolt connections between the segments and may reduce the labor cost and increase speed of lining construction. Pre-stressing of the segmental lining reduces the steel reinforcement or fiber volume in precast segments and/or thickness of the precast segments which would result in reducing the manufacturing cost of them. Pre-stressing would reduce cracking and increase water tightness, and would provide smooth intrados due to eliminated bolt joints and pockets in the tunnel lining. Pre-stressing would increase resistance to internal pressures as well. Further, this system could work very well structurally in tunnels with squeezing rock or tunnels with high seismic loadings. INTRODUCTION OF THE METHODPost-tensioning is commonly used in the construction of bridges, large buildings, nuclear power stations, and water tanks but its utilization in tunnels is still in its infancy.The precast pre-stressed concrete segmental lining can be used for shield tunnels. It provides a reinforced lining ring by the following construction stages and as shown in Figure 1:1) Segments to be assembled by TBM to complete a full ring2) Steel strand to be inserted through embedded duct (sheath) within the segments3) The strand to be tensioned by Jack after anchorage of the other end4) The strand to be fastened after reaching required tension load5) The horizontal strands (if necessary) to be installed, tensioned and fastened6) The recesses and gap between strand and duct to be filled by groutingFurther, Figure 2 shows an unbonded post-tensioning strand model; Figure 3 shows an anchor sample (Xanchor); Figure 4 shows a duct (sheath) and anchor within reinforcement; Figure 5 depicts the posttensioning of a strand by jack; and Figure 6 is an image of the Midorigaoka Trunk line tunnel in Sagamihara, Japan which was constructed using this system."

Jan 1, 2016

By Howard L. Hartman

The federal government&apos;s declining role in funding research has created a critical dollar gap for university departments of mining engineering. Industry is not unaffected by the drought: not only is research lagging, but hard- pressed universities are going to the private sector for funding. This paper&apos;s thesis is not that mining companies should shower universities with philanthropy, but that a quid pro quo ought to be exacted: a research partnership should be contracted on a pay-as-you-go basis. A model exists at The University of Alabama (albeit not in mining) that may lend itself to adoption by our industry.

Jan 1, 1984

By Armando Correa de Araujo

Cationic flotation of quartz is currently utilized for the concentration of iron ores and for the cleaning of phosphate concentrates. The present work deals with depression of quartz in the presence of aluminum ions during cationic flotation. It was established-that aluminum ions depress the flotation of quartz with an amine, especially under neutral and very slightly alkaline conditions. Studies of adsorption of Al ions on the quartz surface as a function of pH correlated with depression of this mineral with an amine as collector. The presence of Al ions also enhanced the depressant action of corn starch on quartz The sodium salt of ethylenediaminotetra-acetic(EDTA) was found to be an effective complexing agent to supress the depression caused by aluminum ions.

Jan 1, 1984

By Jon C. Yingling

Lean manufacturing, pioneered by Toyota, has been credited with the most significant improvements in production efficiency and product quality since the transformation from craft manufacturing to mass production in the early 20th century. It represents a comprehensive philosophy for structuring, operation, control, and management of production systems that is believed to have wide applicability. This paper outlines major lean manufacturing principles and discusses their potential for application in the mining industry.

Jan 1, 1999

The Newmont Boddington Orebody (NBO) is a large, diffuse Au/Cu orebody in Western Australias South-West corner with approximately 20Moz Au in current Reserves. The current sulphide Resource is reported after calculation with the non-linear estimation technique Uniform Conditioning to account for the mining selectivity being smaller than the average drillhole spacing. Simulation of Au grade is also run over the entire orebody reviewing risk and uncertainty. There are differences in results from the two methods. These have been investigated and the lessons learned of the influencing parameters and effect of technique alone, are helpful for applications to other orebodies.

Jan 1, 2010

By Siyu Song, Yanhong Wang, Guohua Gu, Linbo Huang

In this study, the effect of cations, Na+ and Mg2+, in saline water on copper flotation in the presence of calcium bentonite was investigated. It was found that as the concentration of NaCl was increased, the copper recovery initially decreased and then increased to above 99%, while the copper grade initially increased and then decreased. In contrast, as the concentration ofMgCl2 was increased, the copper recovery continuously increased, while the copper grade continuously decreased. The variation of copper recovery and grade was mainly attributed to the synergistic effect of pulp rheology and flotation solution chemistry. The underpinning mechanisms are the compressing electrical double layer and ion-exchange interaction between saline water and bentonite, which occur at the same time. Using salinewater slightly affected the pulp rheologywith a decrease in copper recovery at low NaCl concentration. Increasing the concentration of cations in saline water might even facilitate the flowing out of exchangeable cations, especially divalent cations, from the interlayer space of bentonite to the solution, resulting in the decrease of copper grade at high salt concentration.

Sep 10, 2020

By Dennis C. Martin

Assessment of the potential for mining induced subsidence and determination of ultimate design requirements for a mining operation should be based on a number of assessment approaches. Although the rock mechanics engineer has a variety of limit equilibrium and numerical modeling tools available for assessment and prediction of subsidence effects, empirical approaches based on precedent experience provide a powerful tool for calibration/verification of analytical models and prediction of subsidence. Three separate analyses approaches have been applied to the assessment of potential subsidence for a proposed block caving mine in eastern Canada. The investigations have included an assessment of documented historical information from previous block cave mining at the site, deterministic analyses using limit equilibrium approaches to assess kinematically possible failure mechanisms, and three-dimensional numerical modeling techniques. Analyses results have been used and compared with precedent experience and documentation of subsidence behavior from previous mining to optimize the subsidence predictions for the proposed mine.

Jan 1, 1998

By J. Noll, D. Yantek, B. Kendall, J. A. Organiscak

"A self-tramming remotely controlled mobile Dry Scrubber (DS) was developed by J. H. Fletcher and Co. under a contract with the National Institute for Occupational Safety and Health’s Office of Mine Safety and Health Research (NIOSH OMSHR) to reduce exposure of miners to airborne dust. NIOSH OMSHR laboratory testing showed that the DS averaged greater than 95% dust removal efficiency with the disposable filters and averaged 88% and 90%, respectively, for the optional washable filters in their pre-washed and post-washed test conditions. Although the washable filters could be reused, washing them generated personal and downstream respirable dust concentrations of 1.2 and 8.3 mg/m3, respectively, for a 10-minute washing period. The DS’s velocity pressure regulated variable frequency drive (VFD) fan maintained a relatively consistent airflow near the targeted 1.43 and 4.25 m3/s (3000 and 9000 ft3/min) airflow rates during most of the laboratory dust testing until reaching its maximum 60 Hz fan motor frequency or horsepower rating at 2610 Pa (10.5 in. w.g.) of filter differential pressure and 3.97 m3/s (8420 ft3/min) of scrubber airflow quantity. Laboratory sound level measurements of the DS also showed that the outlet side of the scrubber was noisier and the loaded filters increased sound levels as compared to clean filters at the same airflow quantities. With loaded filters the scrubber reached a 90 dB(A) sound level at 2.83 m3/s (6000 ft3/min) of scrubber airflow, indicating that miners should not be overexposed in relation to MSHA’s permissible exposure level (PEL) of 90 dB(A) at or below this airflow quantity (1). The DS’s washable filters were not used during field testing because of their lower respirable dust removal efficiency and the airborne dust generated from filter washing. Field testing the DS with the disposable filters at two underground coal mine sections showed that it can clean a portion of the section return air and provide about a 50% dust reduction at the face area downstream of the continuous miner (CM) operation. INTRODUCTION Coal mine worker overexposure to coal and quartz dust continues to be a problem at underground coal mining operations in the U.S. The U.S. Mine Safety and Health Administration (MSHA) recently changed the standard for coal mine worker respirable dust exposure from 2.0 mg/m3 average during an eight-hour shift to 1.5 mg/m3 average over the actual working shift, effective as of August 1, 2016 (1). If more than 0.1 mg/m3 quartz mass is found in the coal mine worker dust sample, the applicable respirable dust standard is further reduced to the quotient of 10 divided by the percentage of the quartz in the sample (1). Over 90% of the mechanized mining units operating in U.S. underground coal mines are continuous mining machines (2). MSHA inspector dust samples from 2009 to 2012 showed that 3.7% of continuous miner operators exceeded the 2.0 mg/m3 dust standard, while 8.8% of these dust samples exceeded the new 1.5 mg/m3 dust standard and 9.7% of these samples exceeded the reduced quartz standard (3). Additionally, roof bolter dust samples at these mechanized mining units during this same period have exceeded the 2.0 mg/m3, 1.5 mg/m3, and reduced quartz levels at 1.1%, 3.7%, and 10.6%, respectively (3)."

Jan 1, 2016

By Jorge Amaya, Nelson Morales Varela, Francisco Saavedra, Gonzalo Nelis, René Gómez

Precedence constraints are broadly used in mathematical models and algorithms for mine planning to model, for example, slope angles in open pit operations or connectivity in underground mines. Unfortunately, these constraints do not capture relevant geometrical aspects for the design of the mine like minimum bottom space of pits or smoothness of the economic envelope in block caves. In this work, we present different approaches that utilize precedence constraints generating economic envelops that are more suitable for design purposes. The numerical experiences show that the proposed techniques produce high value envelops with better geometrical properties and that the methods proposed can be computed efficiently.

Jun 25, 2023

By R. P. Fischer

Traditionally, molybdenum and vanadium have been used chiefly as alloy metals in steel. They impart similar characteristics to most steels, and to some extent one can be substituted for the other. In the United States during the 1950&apos;s the production of steel increased about 5 percent, and the reported consumption of both of these alloy metals in steel increased some 40 percent. In Europe during the 1950&apos;s the production of steel in¬creased nearly 100 percent. Data on the actual consumption of these alloy metals in European steels are not available, but production and trade records show that the European supplies of molybdenum increased about 150 percent and those of vanadium about 350 percent during the 1950&apos;s. If most of the molybdenum supplies in Europe are being added to steel, as seems likely, then the European steel industry has nearly caught up with the United State in the rate of consumption of molybdenum in steel. The vanadium supplies, on the other hand, are puzzling--unless Europe is adding mach more vanadium to steel than is done in the United States, it seems reasonable to assume that other uses are consuming moderately large quantities of this metal or that appreciable amounts of it are being transshipped from Europe. To the extent that a changing volume of supply signifies a changing pattern of use, the increased demand for molybdenum and vanadium in Europe should be of interest to domestic producers and consumers of these metals.

Jan 1, 1964

By J. Andrew McGlenn, Brian McInnes, Bruce Downing, Murray Gant

The Second Narrows Water Supply Tunnel crossing beneath Burrard Inlet is an important component of the Greater Vancouver Water District’s plans to increase seismic resilience and meet increasing water demands. The project included the 110-meterdeep (350 ft) South TBM Receival Shaft, one of the deepest shafts to date in the sedimentary rock unit underlying much of Metro Vancouver. The shaft encountered varied sedimentary rock types, including fractured rock, with accompanying high groundwater inflows. This paper discusses the design and construction challenges associated with this shaft and the necessary means to complete the shaft in time for TBM arrival.

Jun 13, 2023

By I. E. Odom

The physiocemical properties and industrial uses of the clay mineral montmorillonite are reviewed. Montmorillonite is the most abundant species of the smectite clay mineral group and is the predominant mineral composing bentonite deposits. The crystal structure, chemical composition, exchangeable ion type, and small crystal size are responsible for several unique properties, including a large chemically active surface area, a high cation exchange capacity and interlamellar surfaces having unsual hydration characteristics. The type of exchangeable ion Na, Ca and/or Mg has a major influence on industrial and chemical uses of montmorillonite because of their hydration characteristcs. Natural occurrences of Na montmorillonite in commercial quantities are geographically limited, but Ca-Mg montmorillonite deposits are known world wide. Foundry, well drilling, pelletizing and civil engineering constitute the major uses of montmorillonite, but the total array of uses of montmorillonite exceeds that of any other mineral.

Jan 1, 1986

By M. J. Virnig

A flowsheet for the recovery of nickel and cobalt from laterite ores has been developed which involves acid leaching followed by hydroxide precipitation of the metal values and then releaching of the hydroxide cake with ammonia. Investigations of the chemistry of extraction of nickel by LIX® 84-1 and a developmental reagent, XI-84-IT, along with the physical properties of the organic phases are described. Based on these investigations, suggestions with regard to design of a solvent extraction plant and operating conditions are made.

Jan 1, 1999