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By E. Northcott, I. M. LeBaron

Before describing the electrostatic processing of feldspar, it might be well to review some of the basic definitions and terminology of feldspars. The feldspar minerals constitute a group of alumino-silicates of potassium, sodium, and calcium. Barium feldspar sometimes occurs naturally but is very rare. Hardness varies between 6 and 6.5 and specific gravity between 2.5 and 2.8. Color is generally white or pale shades of red, yellow, or green. The approximate chemical composition of the principal feldspars is given in Table I. The albite (sodium aluminum silicate) and an-

Jan 1, 1959

By K. Morsi

The interest in spark plasma sintering has been growing considerable over the past few years. This has been brought about by the unique advantages of the process, which include reduced sintering temperatures and times and the production of materials with unique microstructures and properties. Despite its current reputation as an outstanding process that has solved major problems such as nano-powder consolidation, it has so far been largely limited to the manufacture of simple shapes, due to its inherent geometric configuration. In this paper we present preliminary results on spark plasma "extrusion" that can allow the production of extended geometries via electric-current processing. Preliminary results on the processing and microstructure of spark plasma extruded aluminum are discussed.

Jan 1, 2009

By Tim Hughes, Steve Gannon, Jennifer Abols

"In the past year, two very innovative gold ore processing plants have been designed, built and commissioned by Gekko Systems Pty Ltd. The first plant in Vietnam utilizes conventional crushing and ball milling followed by gravity concentration (Inline Pressure Jig (IPJ) and Falcon concentrator), flotation, intensive leaching (GFIL), the first industrial scale use of AuRIX®1001 ion exchange resin and a cyanide destruction circuit. The second plant, in Australia, uses a 3 stage crushing circuit to crush the gold ore to minus 1mm, followed by gravity concentration utilising a rougher, scavenger, cleaner circuit of IPJ’s and a Falcon concentrator. A direct smeltable gold concentrate is produced as well as a lower grade concentrate for future intensive leaching or sale. Both plants were designed and built within very tight time frames and budgetary constraints. The experience gained during the plants’ design, commissioning and operation are discussed.INTRODUCTIONGekko Systems (Gekko) is a leader in the development of innovative technology for gravity recovery and intensive cyanidation. It provides low cost and metallurgically optimal solutions for its customers. It has also led the trend away from whole ore cyanidation (CIP/CIL) towards gravity/intensive cyanidation (GIL) and gravity/flotation/intensive cyanidation (GFIL) plants. These types of plants offer low capital costs, low environmental impact and maximum return to investors (Rob J Longley et al, 2002). Key to this type of flowsheet is the application of a continuous concentrate unit, such as the InLine Pressure Jig (IPJ), which is designed to produce high gold gravity recoveries at a coarse grind (Sandy Gray, 2003). When combined with other gravity devices, and/or flotation, and intensive cyanidation, using the Gekko InLine Leach Reactor (ILR), very high overall recoveries can be achieved.In 2004, Gekko launched a new range of products called Gekko Modular Systems. The idea was to provide off the shelf, complete solutions for the separation and recovery of complex and free gold as well as the pre-concentration of diamonds. A series of modules were designed that incorporated Gekko manufactured as well as outsourced equipment. Gekko now offers modules ranging from feeding and conveying to crushing, gravity recovery, flotation, intensive cyanidation, refining and detox (see Figure 1)."

Jan 1, 2007

In spite of a global economy that continues to seesaw and a U.S. Congress that is at odds with the president and themselves, cities around the world are still spending billions on their infrastructure. And that bodes well for the underground construction and tunneling industry and the professionals who work in it. In June, 1,405 of those professionals gathered in San Francisco, CA for the Rapid Excavation and Tunneling Conference (RETC). In addition to the first rate technical programming, attendees were able to see first-hand the latest in tunneling technology from 127 exhibitors who occupied 152 booths. Two short courses preceded the conference and two field trips were offered following the conference.

Jan 1, 2011

By Leonello Sciacca

Deepening of harbours has become a priority, necessary to the ongoing operation of the wharves in the face of deeper draft merchant vessels and cruise ships. It is now standard practice in many areas to provide for harbours to be dredged to significant depths below mean sea level, in the order of 12.00 m (39 ft) for existing berths and 15.00 m (49 ft) for new wharf construction. The Ravenna Port Authority initiated a project to deepen the harbour bottom at selected wharves to a depth of 12.00 m (39 ft). In preference to reconstruction of the wharves with longer and heavier sheet piling or other equally disruptive reconstruction, they identified the structural reinforcement of the existing wharves by means of deep underwater tie rods as a possible alternative cost-effective solution. Having defined the design concept, effort was concentrated on developing the required technology. A technique, already in use for the installation of tie rods by means of robotics, was identified as potentially suitable for underwater use. It was decided to carry out the fine tuning and the evolution of the technology for a marine environment of the robot unit and of the related remote control software that controls the installation of the tie rods. An experimental test site was set up to refine the drilling, installation, grouting, monitoring and testing of underwater tie rods. The purpose was to confirm the feasibility of the proposed solution and the reliability of these tie rods for use in the reinforcement and construction of wharves. The paper also discusses the theoretical and experimental study of underwater tie rods dealing with the theoretical analysis of the interaction between tie rod and soil, aimed at identifying the correlation between the forces of applied traction and the corresponding measured elongations. A series of tests were carried out with positive results, both at the operating load of 300 kN (67 kips) and at the nominal maximum load of 630 kN (142 kips). The tests were carried out on seven tie rods, of which three were installed at a depth of 5.00 m (16 ft), principally to test the reliability of the operating and remote control systems in the presence of a significant hydrostatic pressure, and four were placed at a depth of 8.00 m (26 ft) to check the load bearing capability of the tie rods positioned at the depth called for by the current project.

Jan 1, 2011

By Brian Fulcher

In April 1997, Kiewit/Parsons Brinckerhoff (K/PB) completed the 7,600-m (25,000-ft) primary access tunnel for the Yucca Mountain, NV proposed high-level nuclear waste site. K/PB then began boring an exploratory east-west cross drift tunnel at the site. The 2,681-m (8,796-linear ft)East-West Cross Drift Tunnel was excavated through volcanic tuffs having zones of incompetent rock using a rebuilt Robbins 5-m (16.4-ft)hard-rock tunnel boring machine(TBM) with a special arrangement of supporting equipment. This portion of the Yucca Mountain project was completed in eight months.

Jan 1, 2000

By M. J. Ferrante

The preparation and subsequent reduction of vanadium trichloride was investigated as a process for the production of high-purity vanadium metal. Chlorine was reacted with vanadium oxide in the presence of carbon to vanadium tetrachloride. The contaminant vanadium oxytrichloride was also formed and later converted to tetrachloride by reaction with chlorine in the presence of activated charcoal. Vanadium tetrachloride was stirred continuously during thermal dissociation to vanadium trichloride powder from which volatile contaminants were removed by distillation. The vanadium trichloride powder was reduced to vanadium sponge by controlled feeding of the trichloride into molten magnesium. Excess reductant and byproduct salt were removed from the vanadium sponge by high-vacuum distillation. Batches as large as 6.5 kilograms of sponge metal were prepared at an average reaction efficiency of 98 percent. Vanadium sponge after consolidation by arc-melting contained 820 to 11330 ppm of interstitial impurities and had a hardness between Rockwell B 40 and 70, This metal exhibited excellent workability at room temperature. The purification of impure vanadium metal by electron-beam melting resulted in lowering interstitial impurities from 1,890 to 504 ppm and hardness from Rockwell B 87 to 28.

Jan 1, 1968

By Raymond W. Henn

The 30th annual short course ?Grouting Fundamentals and Current Practice? was held at the Colorado School of Mines, June 22-26, 2009. The field demonstration portion of the course was conducted June 25, at Hayward Baker, Inc.?s yard in Broomfield, CO. The full-scale field demonstration annually presents many different types of drilling equipment being operated as well as various grouting methods being performed under different field conditions. As part of the field demonstration, the class is shown the proportioning, mixing, testing and injection of various cement grout mixes into sand columns under controlled and measured conditions. These sand column demonstrations have been conducted under controlled and measured conditions each year since 1999 as part of the short course. The sand column demonstrations were conducted prior to 1999, but with less quality control and minimal record keeping of the proportioning, mixing, testing, injection pressures and the final permeation results. The goal of the sand column demonstration is to show the students the effect of the water cement ratio and the use of admixture as well as the fineness of the cement, portland versus ultrafine, used has on the engineering properties of the grout and the grout?s vertical permeation through the sand. Test results for the demonstrations conducted in 1999 and for two separate demonstrations, one at the grout course and one at Geo Denver, conducted in 2000 were published in the 2001 proceedings of the Rapid Excavation and Tunneling Conference (RETC) (Henn et al. 2001). The test results for the 2002 and the 2003 demonstrations were published in the 2005 proceeding of the RETC (Henn et al. 2005).

Jan 1, 2009

This paper gives an overview of the difficulties associated with determining the strength of hard rock pillars. Although a number of pillar design tools are available, pillar collapses still occur. Recent examples of large scale pillar collapses in South Africa were caused by weak partings which traversed the pillars. Currently two different methods to determine the strength of pillars are used namely, empirical equations derived from the back analyses of failed and stable cases and numerical modelling tools with an appropriate failure criteria. Both techniques have their limitations and additional work is required to obtain a better understanding of pillar strength. Empirical methods are popular and easy to use, but care should be exercise that the results are not extrapolated beyond the range of the data which were used to derive them. An example is the Hedley and Grant formula (derived for the Canadian uranium mines) that has been used for many years in the South African platinum and chrome mines (albeit with some adaptation of the K-value) to design the pillar layouts. Very few collapses have nevertheless been reported and it might even be too conservative an assumption of pillar strength in these mines. As an alternative, some engineers strongly advocate the use of numerical techniques to determine pillar strength. A close examination unfortunately reveals that these techniques also rely on many flawed assumptions. An area where numerical modelling is invaluable, however, is to study specific pillar failure mechanisms, such as the influence of weak partings on pillar strength. In conclusion, it appears that neither empirical techniques nor numerical modelling currently provide a solid basis to conduct pillar design. It is therefore recommended that both these techniques be utilised when confronted with a pillar design to obtain the best possible insight into the problem.

Nov 25, 2010

By T. A. Sullivan

The processing of sweated aluminum electronic scrap was investigated to develop methods for recovering the aluminum and concentrating the other metals, including copper, lead, gold, and silver, into a product that can be separated by known methods. Two molten-salt electrorefining processes were developed and tested. The first process utilized a three-layer refining cell with a BaCI2-NaF-AIF3 electrolyte, which operated at 750° to 850° C. The second process used an all-chloride electrolyte of NaCI-KCI-AICI3 at 750° to 800° C, with separate anode and cathode compartments. High-quality aluminum was recovered that averaged 99.8-percent pure in the three-layer cell and 99.6-percent pure in the compartment cell. Over 94 percent of the aluminum was recovered with cathode current efficiencies of approximately 90 percent in both methods. The copper, lead, tin, silver, gold, and other metals were concentrated threefold in an anode product. Separation of lead and part of the tin by liquation from this product seemed feasible. The anode product was smelted to prepare a 96-percent copper bullion that contained 690 ounces of silver and 65 ounces of gold per ton, with 98 percent recovery of these values.

Jan 1, 1972

By F. Calizaya

The Western Mining Training and Translation Center is a consortium of four universities devoted to developing educational and training projects to reduce the incidence/accident rates in the mining industry. The center consists of Missouri University of Science and Technology, Montana Tech, the Colorado School of Mines and the University of Utah. It is fully funded by the National Institute for Occupational Safety and Health (NIOSH). The center manages 15 educational projects and one translation project. Hazard Identification and Risk Assessment (HIRA) for Small Mines is an educational project managed by the University of Utah. The objectives of this project are to identify critical mine hazards, assess risks; outline procedures to reduce accident/incident rates in small mines in the western United States and to train mine workers and super-visors on HIRA in each participating mine. To accomplish these objectives, the HIRA personnel visited 15 small mines in Utah, Colorado, Nevada and California. At these mines, most operators were employing independent contractors to perform several tasks ranging from drilling, blasting and mucking of rock at the work site to hauling ore to a processing plant. The operation of diesel-powered equipment was one of the major tasks performed by the contractors. This article presents three case studies in which contract workers performed a number of tasks with no reportable incidents but did so unsafely. It also highlights the training received by most contractors, the constraints imposed upon them and the safety hazards to which they are exposed most frequently.

Jan 1, 2008

By Christophe Bragard, Brett Robinson

This paper reflects the challenges encountered during the construction of the light rail tunnels under Boyle Heights, in Los Angeles, California. Equipped with two state-of-the-art EPB TBMs, the construction team undertook the mining of twin bored tunnels in the Los Angeles alluvium. The gassy underground conditions dictated many aspects of the design of the tunnels, as well as the tools and means used for their construction. This paper will detail the challenges encountered during construction, as well as the means, methods and logistics used on the project. Discussion includes: EPB TBM machines with some very unique/specific features; complex assembly sequence due to limited shaft access; final precast concrete liner with double gaskets; NATM cross passage excavation in soft ground and below the water table; compensation grouting; mucking shaft arrangement.

Jan 1, 2007

By J Mercuri, S Dunford, P Rothman, E Bartsch, J Snyder, D Newton, R Maron, D Cirulis

The purpose of a mineral comminution circuit with a ball mill running in closed-loop with a hydrocyclone classification cluster is to feed the downstream process with the target particle size. Maintaining the optimal particle size in the flotation feed can significantly improve plant cash flow. In particular, reducing the amount of coarse material is often a major challenge. Existing instrumentation to provide particle size measurement is considered standard equipment in most modern concentrator plants. However, availability is often very low, mainly owing to high maintenance requirements of the analyser and associated sampling system.CiDRA Minerals Processing has developed two novel and robust technologies that address this challenge by providing high reliability and very low maintenance systems for on-line measurement of coarse material in the overflow of individual hydrocyclones. The first system is non-invasive and measures pebbles and rocks greater than 6 mm. This paper focuses on the second system, which is a ruggedized wetted sensor design with no moving parts and provides a real-time trend of the desired target grind size parameter, such as percentage above 150 micron.Both systems have simple robust designs and measure in the primary overflow stream of the individual hydrocyclone. Individual hydrocyclone measurement enables identification of poor performing hydrocyclones in addition to providing a representative measurement of the whole hydrocyclone cluster. The systems do not require sampling and associated sample transfer piping circuits that are prone to plugging, thus avoiding high maintenance requirements.The wetted sensor will be described in detail along with its implementation in a robust control scheme in a major copper concentrator in North America. Plant data shows very high availability, achieved with very low maintenance, has enabled improved process control, thereby maintaining throughput and ball mill target power while reducing grind size.CITATION:Cirulis, D, Dunford, S, Snyder, J, Bartsch, E, Rothman, P, Maron, R, Newton, D, O’Keefe, C and Mercuri, J, 2015. Process optimisation using real-time tracking of coarse material in individual cyclone overflow streams, in Proceedings MetPlant 2015, pp 93–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Evangelos Petrakis, Kostas Komnitsas

This study investigates the evolution of dimensional properties of grinding products, namely, the mass, the surface area, the length, and the number of particle distributions with the energy input in a ball mill. The size analysis of the mill products enables the calculation of the mass distribution of each material at predetermined size classes and then the determination of the other dimensional properties by taking into consideration the geometry of the particles. Based on the distribution of dimensional properties, an effort was made to determine whether the grinding products are fractal in nature. The effect of material type and grinding conditions on the relationship between the dimensional properties and the specific energy input was also investigated. Special importance was assigned to the study of the specific surface area and the surface area production rate, both during the initial grinding stages and at higher energy levels. The determination of the surface area production rate allows the identification of the grinding limit and the maximum specific surface area which could theoretically be achieved. This approach has as ultimate objective the maximization of energy efficiency and subsequently the minimization of the high grinding cost.

By W Dodson, S Dogramaci

Isotopes and hydrochemistry were used to define groundwater flow systems and better understand the hydrogeological setting of the Karijini National Park, which is in the Central Pilbara region adjacent to the Marandoo iron ore mine. Based on the stable isotope composition of the water samples, the data can be divided into two main groups. Groundwater is characterised by depleted dD and d18O, suggesting no significant evaporation effect. Surface water on the other hand is more enriched in dD and d18O due to evaporation. The relatively high concentration of Cl- compared to rainfall and depleted dD and d18O values of groundwater indicate that recharge of the aquifers is occurring during intense rainfall events when rapid infiltration occurs. Evapotranspiration then acts to concentrate ionic species prior to recharge. Relationships between the major ion concentration and catchment area, surficial Tertiary cover and distance between recharge and discharge were identified. The results show that these catchment variables combine to determine unique water chemistry for each sub catchment in Karijini National Park. The TDS concentration of the groundwater in the Marra Mamba Iron Formation that hosts the Marandoo ore body is higher than most of the water bodies surrounding the mining area suggesting significant modification or different recharge mechanisms to that of the Karijini groundwater.

Jan 1, 2009

By Scott A. Walker, Frank L. Rollo

"The San Francisco Museum of Modern Art (SFMOMA) in downtown metropolitan San Francisco, California, is supported on a mat foundation. Although the mat foundation of the original museum was designed to accommodate a future expansion, the plans for expansion that developed in 2010 required a larger footprint to accommodate the new space requirements of the museum. The new, larger expansion was designed by lead architect Snohetta. It will be a tall 12-story, steel-framed building occupying an area that was once the eastern part of the existing museum as well as two adjacent and newly acquired parcels.As designed, the expansion includes a 30-foot-deep excavation which is surrounded by adjacent buildings and improvements. Because of variable subsurface conditions at the site, geotechnical challenges included mitigating anticipated differential settlement between the existing and new foundations, preventing overstressing of the existing mat foundation, controlling groundwater to prevent settlement of surrounding improvements, and providing temporary support of adjacent structures during excavation for the new basement.To address several of the geotechnical challenges, soil-cement mixed (SMX) ground improvement was recommended by Treadwell & Rollo. However, during contract negotiations and construction, the specialty contractor proposed using jet grouting as an alternative technique for ground improvement. The jet grouting approach was accepted in principal, but when implemented was only marginally successful. Accordingly, the contractor eventually installed SMX panels using a Cutter Soil Mixing (CSM) machine. Because the CSM machine was a late arrival during construction, the contractor was not able to take advantage of the ground-improvement technique to install many of the shoring elements that we had originally recommended (such as the cut-off shoring wall). In the end, SMX panels were installed as ground-improvement beneath the new mat foundation to (1) reduce the potential for liquefaction in clean sand below the groundwater by providing increased rigidity to the soil, (2) reduce the potential for disturbing a weak underlying marsh deposit during construction, and (3) transfer vertical building loads to a layer of underlying dense sand.This paper also discusses the quality control and quality assurance programs that were implemented to check that the ground-improvement techniques used were thorough and complete and provided the required strength to transfer the new foundation loads to the underlying strata."

Jan 1, 2014

The method of investigation was to study the distribution of ore in great detail, to make a thorough structural study of the lode and the mine area, and then to compare the results of the two studies. Such a comparison usually reveals a very close relationship between geological structure and ore distribution, and can often lead to important conclusions which would not be reached in the ordinary working of a mine.The Triton mine lies 30 miles E.N.E. of Cue, or 380 miles N.W. of Kalgoorlie, in typical pre-Cambrian rocks, consisting of gTeenstone lavas and tuft's, interbedded with slates and some sediments, and intruded by granite and porphyry. Fig. 1 (at end of paper) is a longitudinal section of the mine and shows that the workings consist of the main North Emu and the smaller South Emu, separated by a distance of about 1 of a mile. Both orebodies occur on the same lode, which strikes north and south and dips practically vertically. On the same line, and of 1/2 a mile and a mile respectively to the north of the North Emu, are the small Rand and North Rand workings, where a big width of lode material has proved to be very low grade. In the North Emu the lode width averages 12 to 15 feet; it is seldom less than 5 feet and in places reaches 30 feet. In the South Emu the lode is wide, but only portion of it is payable.The lode is a mineralised bed occurring between massive lava flows on the east and a mixed series of tuft's and thin lava flows on the west. The lode material is hard, fine grained, and dark coloured, and generally has a faint banding which is believed to indicate a tuft'aceous origin of the original lode rock. Microscopic examination shows that the original lode rock has undergone considerable albitisation;' there has also been considerable formation of biotite which gives the lode material a characteristic sheen. The mineralisation consists of abundant fine pyrite, which is auriferous, and a lesser development of pyrrhotite which is, however, barren of gold.THE OREBODIES AND THEIR CHARACTERISTICSThe distribution of ore is best studied from gold contours, as these reveal features that cannot be detected in an ordinary assay section. Gold contours (see Fig. 3) are developed' by plotting the width and grade of all development and stoping assays throughout the mine on a longitudinal projection, representing each sample by a coloured dot according to a suitably chosen range of assay values, and then outlining areas of similarly coloured dots (see H. J. C. Conolly, Econ. Geol., April, 1936). Both width and grade must be taken into account and the simplest method of gold contouring is to use dwt.lft. values, but difficulties arise here with big widths of low grade and small widths of high grade ore. To choose an extreme case, 30 ft. of 2 dwts. and 2 ft. of 30 dwts. both equal 60 dwts.lft., and would therefore be given the same value in dwt.lft. contouring...

Jan 1, 1943

By J. S. Coats, G. E. Patts, N. Hughes

Conventional sampling methods are known to suffer from the variable loss of fine gold by elutriation. Freeze sampling yields representative and quantitative data that, when combined with information on the sedimentology of gravel-bed rivers, may facilitate the development of improved dispersion models for source detection. It is suggested that freeze sampling may have particular application to the orientation stage of a large gold exploration survey

Jan 1, 1991

By J. G. Donaldson

Optimum conditions are given for chloridizing pyrite, marcasite, chalcopyrite, arsenopyrite, stibnite, and covellite with chlorine gas. The formation of metal chlorides is affected by the time and temperature of chloridizing, and by particle size of the sample. Chloridizing data also are given for chemically precipitated antimony (III) sulfide and copper (II) sulfide.

Jan 1, 1962

By Brian Stump, David Anderson, D. Craig Pearson, Robert Martin

Mining explosions designed to move, bulk or fracture rock are often composed of a number of explosions arranged in a complex spatial and temporal pattern. The effects of the explosions are strongly dependent upon the design and implementation of this blasting pattern. This paper describes the collection, combination and visual display of multiple types of data from these explosions for the purposes of understanding the relationships between the blast design, implementation, and observations. Data sets consist of three-component ground motion, acoustic, video and high speed film, three-dimensional topography, geological and geophysical properties, design blast pattern and timing, and velocity of detonation in the explosive for individual borehole detonation times. The explosions studied include simple single-fired contained explosions, ones designed to bulk and fracture rocks and those that cast material.

Jan 1, 2000