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By William R. Yernberg

The combined 76th Annual Minnesota Section of SME meeting and 64th Annual University of Minnesota Mining Symposium were held April 8and 9, 2003, in Duluth, MN. This year’s theme was “Stakeholders, Partners in Change.” The meeting included four keynote speakers, technical presentations and a tradeshow. Engineers, executives, mining managers and suppliers from throughout the United States and eastern Canada attended the meeting. Reflecting the theme of the meeting, all agreed that the mine owners, the government, the community and the employees are all “stakeholders.” They must be “partners in change” for the iron ore mining industry to survive in the region. Compared with past meetings, where improved technology was the primary focus, this year the focus was on the dramatic restructuring of the entire industry. As noted by several of the speakers, “This time, the change is not in technology.”

Jan 1, 2003

By J. C. Johnson

Underhand mining with cemented mill tailings for backfill has proven to be a safe and effective alternative to conventional overhand mining for rockburst prone mines. The ability of the cemented sandfill to survive a rockburst shock wave without failing has been observed at mines in the Coeur d?Alene Mining District many times in the last twenty years. To better understand the dynamic loading of this commonly used support material the National Institute for Occupational Safety and Health (NIOSH) performed laboratory experiments using a split Hopkinson Pressure Bar (SHPB) to quantify the maximum stress and energy absorption of cemented mill tailings from the Galena mine. Cylindrically shaped cemented backfill specimens aged 28 days were placed in the split Hopkinson pressure bar testing apparatus and a dynamic load was applied. The measured peak dynamic compressive strength of the cemented sandfill was 10.6 MPa (1540 psi) and is approximately twice the static unconfined compressive strength (UCS) of 5.5 MPa (800 psi). These test data showed about 95% of the initial energy was reflected away from the backfill and only 5% of the energy was absorbed. This may help to explain why backfilled stopes could withstand seismic events up to 3.5 Richter magnitude (Ml). When a compressive rockburst wave impacts a stope a large amount of the stress and energy is reflected away. The reflected wave is a tensile wave which creates tensile cracks and spalling in the entire wall of the stope. The backfill supports the damaged wall rock and holds it in place. Some of the stress and energy of the rockburst is transmitted into the backfill and because the backfill is being dynamically loaded it has a strength that is twice its static value and absorbs a substantial amount of rockburst energy. Although mining in deep underground mines is an extremely hazardous occupation, the use of underhand mining with cemented backfill for static and dynamic ground control increases the safety of the workers.

May 1, 2007

"Mineral separation by exploiting the differences in mineral or metal specific gravities (sg) has been used since antiquity. In the modern era, this is most commonly seen in the recovery of gold by the use of centrifugal concentrators and the separation of coal (low sg) from waste rock (high sg) using heavy media cyclones and jigs. Other metals, notably oxides of tin and tungsten, are successfully recovered using some combination of jigs, spirals and shaking tables. However, many conventional gravity separation systems are limited to fairly coarse (>1 mm) to medium (>100 micron) particle separations due to the limitations of the gravitational separation forces in conventional equipment.Many of the high specific gravity minerals of interest are friable (e.g. cassiterite, wolframite, etc.) and excessive fines are generated in the grinding/comminution circuits which cannot be recovered with conventional equipment and may be lost directly to the tailings stream. Recent developments in centrifugal gravity separation equipment specifically designed for fine or ultra-fine particle separation and recovery have resulted in heavy mineral particle recoveries as fine as 10-20 microns. Ongoing research work has also identified the benefit of closed-circuit, multi-stage gravity recovery circuits using some combination of centrifugal concentrators and conventional equipment (tables, spirals, flotation, etc.) which can substantially increase overall plant recovery and final concentrate grade.This paper will provide details of the evolution of non-fluidized bed gravity concentrators for high sg mineral recoveries, correlate laboratory scale development work with plant results to confirm scale-up, and show how recent flowsheet developments have contributed to significantly improved plant performance.IntroductionGravity concentration is one of the oldest and most cost effective metal and/or mineral recovery systems, ranging from the classic hand panning of alluvial gold, through to the large scale production of a wide range of metals and minerals, including gold, silver, PGMs, black sands, coal and iron oxides. Conventional gravity recovery systems, comprised of some combination of sluices, spirals, jigs and shaking tables have limited application in fine particle (i.e. <100 microns) recovery, or where there are limited differences in particle specific gravities (sg), e.g. the separation of high sg, high value metal oxides (e.g. those of tin, tantalum or tungsten), from medium sg, lower value metal sulfides such as pyrite and pyrrhotite. These unit operations tend to have limited capacity, and while double and triple turn spirals and multi-deck tables have been developed, extensive floor space is often required in order to process the tonnages incorporated in the modern mineral processing plant."

Jan 1, 2017

The objective in control blasting is to reduce overbreak to control the final pit wall slope, shaft, drift, ditch, bench, etc. to the final planned excavation limit.

Jan 1, 1990

By Suk han Jang

This paper describes the tower foundation design and construction experience for the 345kV Youngheung marine transmission line, which has been in commercial operation in Korea since July, 2004. This transmission line was designed and constructed to meet the rapidly increasing power demands of metropolitan areas and supply stable, bulk electric power from the Yonghung thermal power plant into metropolitan areas. This transmission line passes over the west sea, Lake Sihwa and over land. In order to successfully complete this project, and to safely support the tower during severe maritime conditions, several types of tower foundation such as Pad and Chimney foundation, Pier (Cylindrical) foundation, R.C.D foundation, Jacket pile foundation and Steel pipe pile + concrete mat foundation were developed and used. As the world?s first and longest marine transmission line, the 345kV Yonghung marine transmission line operates successfully, thanks to several high-tech civil engineering technologies and KEPCO?s accumulated experience.

Jan 1, 2007

By S. Y. Tan

As continual complementary metal?oxide?semiconductor (CMOS) scaling requirements, metal gate/high-k dielectric/Si gate stacks are expected to replace poly-Si/SiO2/Si gate stacks in the future CMOS sub-45 nm technology node. Hafnium based oxide is a promising candidate to replace SiO2 as a gate dielectric, due to its much higher dielectric constant (high-k) and stability. The key challenges of successfully adopting the high-k dielectric/Si gate stack into advanced CMOS technology mostly come from the interfacial properties. The origins of the electrical and physical characteristics of the dielectric oxide/bulk interface were studied in detail. The leakage current density-voltage (J-V) and capacitance-voltage (C-V) measurement techniques were employed to study the dielectric oxide/Si interface. The effects of the post-deposition annealing (PDA) treatment on the interface charges of dielectric oxides were studied. We found that the PDA can effectively reduce the trapping density and leakage current, and eliminate hysteresis in the C?V curves. Besides, the changes in chemical bonding features at HfO2/Si, HfSiO/Si and HfSiON/Si interfaces due to PDA treatment were evaluated by XPS measurements. The XPS analysis provides a better interpretation of the electrical outcomes. As a result, both HfSiO and HfSiON films have exhibited superior performance in terms of thermal stability and electrical characteristics.

Jan 1, 2010

By Ludovic Charpentier

Production of metallic wires directly from liquid jets would avoid drawbacks of extrusion (space needed, damaging, cost?) and enable recycling. But liquid jets tend to break, due to capillary instabilities, unless a solid layer (coating or start of solidification) surrounds it. We recently developed a process to produce tin wires, cooled by water flow parallel to the jet. Superficial oxidization of tin produces a glass coating around the jet. Studies showed the length of wires increased when increasing speed of tin jets, and that water average speed should be the closest possible to the jet one to have smooth fibers. Producing 1 mm diameter wires is possible. The length of wires is limited by the experimental setup, which does not provide possibilities to coil the wire. Most of other metals do not generate glass-like oxides. The lack of coatings makes it necessary to reduce the capillary instabilities to obtain fibers.

Jan 1, 2006

By D. Kruse

Top down constructed large diameter (up to 90 m [300 ft]) shaft design and constructability issues present an interesting suite of challenges and opportunities highlighted in this paper. The study covers 2D and 3D finite element models used to: analyze various failure modes, evaluate the shaft liner and internal structures? response to seismic loading, assist in segment design, and assess final structural design tradeoffs. Efforts to achieve economic advantage over conventional heavy civil practices have prompted innovative solutions for ring and segment design, ring build assembly, and annulus backfill grouting. Intended for soft ground conditions, relationships between soil parameters and structure design are also explored.

Jan 1, 2011

This paper presents a virtual prototype for the stress analysis of cable shovel components based on combination of flexible and rigid body approach. The general mechanical system of the cable shovel is modeled as a multi-body system with rigid and flexible bodies. The relevant theories applied for the dynamic model are described in terms of Lagrangian multi-body dynamics and finite element method. A virtual prototype of the cable shovel is built in the Automatic Dynamic Analysis Mechanical System (ADAMS) environment, which allows visualizing the motion of general mechanical system and analyzing the dynamic stress of structural components of the cable shovel. An example is given to perform dynamic stress of durability analysis for the boom and handle. Attention of this study is devoted to the mechanisms of damage of the cable shovel and also the critical high stress areas. Keywords: Cable shovel, Von Mises stress, Virtual prototype simulation, Stress virtualization.

Jan 1, 2009

By A. Broussaud, J. D. McKay

Benefits analysis of adaptive Expert control systems operating at plants in Africa and the United States are presented. Proper statistical tools and techniques are discussed. Technical and practical pitfalls of strategy comparison are also presented and illustrated with from published data. Advantages and disadvantages of a “Pay for Performance” approach to a project are reviewed.

Jan 1, 2001

By Carl-John Grävare

This paper deals with some of the systems and equipment that are being developed and/or are in use in Scandinavia. The main subject is the development of loading tests on the piles using monitoring equipment. This paper also describes ground improvement using lime-cement columns, expander body piles and steel core piles.

Jan 1, 2000

The selection of the best comminution circuit for the preparation of concentration feed is a compromise based on economics, energy efficiency, labour costs, steel consumption, availability and other factors specific to each case. It is postulated that the selection must be a choice of one of the eight basic comminution circuits which can be divided into two basic groups, (1) autogenous or semi-autogenous primary mills with or without a secondary grinding stage and (2) fine crushing usually in cone crushers followed by a rod mill-ball mill circuit or a single stage ball mill circuit. The accuracy of selection may be improved by pilot plant and laboratory tests which are described in this paper. For (1) above, testing includes media competency tests with standard impact crushing, grindability and abrasion tests followed by pilot plant tests. For (2) above, bench scale crushability, grindability and abrasion testing is available. It is suggested that, through these tests, it should be possible to eliminate all but one in each group of basic comminution circuits. Then engineering and economic studies should lead to the best comminution circuit for the specific requirement.

Jan 1, 1984

By B. Tripp

Utah produces a wide variety of industrial rock and mineral commodities, valued in 2005 at a record $758 million (21 percent of the total non-fuel mineral production of Utah). Major commodities produced in 2005 include salts (halite, potash, and magnesium salts), Portland cement, sand and gravel, carbonates (lime, limestone, and dolomite), phosphate, crushed stone, clays, lightweight aggregate (expanded shale and perlite), gypsum, silica, sulfur and sulfuric acid, and building stone. Commodities produced in smaller amounts include diatomite, pumice, gemstones, ornamental stone, fluorspar, and mineral and fossil specimens. Utah is in a period of rapid growth in industrial rock and mineral production; however, some commodities have grown faster than others. The robust western economy has stimulated production of construction-related commodities like sand and gravel, Portland cement raw materials, lime, and building stone, resulting in exploration for raw materials, development of new quarries, and expansion of existing plants

Jan 1, 2007

By Lonie W. M

The rapid development of the Australian steel industry over the past twenty years has greatly increased the demand for coking coal from the collieries owned by the Broken Hill Proprietary Co. Ltd. and Australian Iron &amp; Steel Ltd. This in turn has called for an intensive and continuous programme of colliery expansion and new colliery development, along with the reorganization and modernization of existing collieries.This paper presents a general description of the factors involved and the techniques used in planning modern colliery development for the steel industry.PRELIMINARY GEOLOGICAL INVESTIGATIONSIn any colliery development, preliminary geological investigations require a detailed and practical knowledge of the geology and characteristics of the coal-field as a whole. In the early stages of the investigations, probably the most valuable information is obtained from outside the particular area under review, rather than within it, and unless the geology of the coal-field is understood, the projection of the known information into the unknown area cannot be carried out with certainty.Because development of the coal seams from the outcrops has been an apparently simple matter and not subject to the risks involved in deep mine development, the geology of the New South Wales. coal-fields has not received the attention that major mineral resources warrant.Only the most accessible regions of the coal measures have been generally prospected, while the potential areas remain...

Jan 1, 1957

By H. Takamoto, M. Ichinose

"The basic objectives of mine roadways are to provide sufficient cross sections in order to meet the needs of accommodation of equipment, transport, personnel travel and ventilation. However, many roadways become damaged to the extent of needing maintenance, generally dinting, and in some cases requiring re-ripping. The damaging of a roadway is a result of several factors including geological properties of surrounding strata, method of roadway formation, support systems and so on. Among these factors, strata conditions play important effects on the stability of roadways and other mining activities. Weak rocks cause excessive roadway closures, and water softens some rocks and worsens the closure problem. In Indonesia, over 250 Mt of coal is now produced from almost surface mines. In the near future, some coal must be mined from underground. Unfortunately, the mechanical properties of coal measures rocks are not so good to open underground mines. In this paper, a scientific discussion on the effect of water on the stability of roadways is given on the basis of results obtained by means of in-situ investigation and laboratory tests both in Japan and Indonesia."

Jan 1, 2011

By Charlie Brumbaugh

Antarctica with its diverse conditions such as severe cold, high winds, rock and ice structure and limited explosives available posed many obstacles. This paper will give an overall view of the methods used to overcome these obstacles on a daily basis on the highest, driest, coldest continent on earth.

Jan 1, 2000

By L. F. Albert

The paper describes solutions given to foundation problems during the reconstruction of a power plant set on fire, located adjacent to several still Working Units. After a detailed site and laboratory investigation, it was decided that it could be possible to include within the new foundations the preexisting cast in situ driven piles with enlarged base 50 cm in diameter and let them work with new 41 cm driven, cast in situ piles without enlarged base. Demolition of existing caps was carried out with expansive mortar in order to avoid any possible damage to piles, whose actual conditions were checked by several load tests. New piles were designed to support service load by shaft resistance, in order to limit total and differential settlement. When piles had to be driven adjacent to nearby structures, measurements of peak soil particles velocity were carried out while driving piles at decreasing distance from critical locations. By preboring most of the upper clay layer it was possible to reduce within safe limits for structures the induced vibrations.

Jan 1, 1989

By Hookings H. J

UNDER a contract relating to the sale of a Broken Hill concentrate, the differentiation between granular and slime concentrate is determined by the proportion of the material which will pass a 200-mesh (I.M.M. standard) screen, and this has led to considerable attention being devoted to the question of laboratory sizing tests with screens of this order.It was found that many of the screens turned out by the makers during the war, and also since its termination, did not conform with the I.M.M. specifications as closely as some supplied in pre-war days. A perfect screen is hardly to be expected, but when the above contract was framed the parties anticipated that, by special care being taken during manufacture, a screen at least as good as the best pre-war screens would be available. This, however, has not proved to be the case, and the large irregularities in screens recently supplied render them useless for sizing determinations under the contract. The makers were approached through the Institution of Mining and Metallurgy, London, with the view of obtaining a few screens conforming as closely as possible to the 200-mesh I.M.M. standard, and in response to a request twelve pieces of screen were...

Jan 1, 1922

By Ahmad Ghahreman, Lin Li

Silver and cupric ions have been proven to play the roles of catalysts to promote the oxidation kinetics of chalcopyrite in acid solution. In this study, the interaction between silver ions and cupric ions during ferric leaching of chalcopyrite in sulfuric acid solution has been investigated. The electrochemical study by Tafel analysis showed a significant boost of dissolution rate for chalcopyrite dissolution in Fe3+- Cu2+ containing sulfuric acid solution after Ag+ was added in the solution. For 10 ppm Ag addition, the dissolution rate of chalcopyrite increased to 7.94 ×10-6 A/cm2 from 3.2 ×10-7 A/cm2, when Ag+ was absent. On the other hand, the effect of Cu2+ on the dissolution of chalcopyrite in Fe3+-Ag+ containing sulfuric acid solution was not obvious from electrochemical measurements. The chalcopyrite leaching tests in different acid solutions showed that silver addition had an obvious catalytic effect on promoting chalcopyrite dissolution. Comparing the leaching rates of chalcopyrite leached in Fe3+ containing, Fe3+-Ag+ containing, Fe3+-Cu2+ containing and Fe3+-Cu2+-Ag+ containing sulfuric acid solutions, it was found in Ag+-Fe3+-Cu2+ containing sulfuric acid solution, the leaching rate was highest among all the aqueous acid systems. Further leaching tests suggested that with increase of the Ag+ concentration from 0 to 20 ppm, the leaching rate of chalcopyrite in Ag+-Fe3+-Cu2+ containing sulfuric acid solution also increased and reached 57.62% with 20 ppm Ag+ addition after 24 h. INTRODUCTION Chalcopyrite is the most important copper mineral in copper hydrometallurgy and it accounts for nearly 80% of the universal copper resource (Olvera, Rebolledo, Mora, Dixon, & Asselin, 2018). The hydrometallurgy of chalcopyrite has been intensively studied with emphasis on solving the slow dissolution kinetics of chalcopyrite in acid environment. A variety of aqueous systems, such as sulfate (Hiroyoshi, Miki, Hirajima, & Tsunekawa, 2001), chlorides (Liu, Chen, & Yang, 2017), and ammonia (Hua et al., 2018) have been studied to improve copper leaching. From another perspective, chalcopyrite leaching studies have indicated that the mechanism of chalcopyrite dissolution in acid solution is essentially electrochemical (Li, Kawashima, Li, Chandra, & Gerson, 2013). Therefore, extensive studies have recently been carried out to explain the dissolution kinetics of chalcopyrite in different media by various electrochemical techniques.

Jan 1, 2019

By D. L. King, C. D. Rubert, R. W. Christy, B. A. Schepman

R. W. Christy (Manager of Sales, Sanitary Engineering Equipment, Link-Belt Co.) and C.D. Rubert (Barrett, Haentjens & Co.) — Messrs. King and Schepman have presented an excellent paper which outlines the general practice in the design of thickener mechanisms. Lifting devices, controls, special applications and underflow pumping arrangements have been reviewed in detail. Pumping arrangements were illustrated which eliminate the need for an expensive tunnel beneath the thickener floor. Most of those illustrated have the common feature of a relatively long underflow suction line extending from the hopper floor to the pump located on the bridge at the periphery of the tank. The authors limit these arrangements to comparatively dilute or thin slurrys. It is implied that dense and coarse concentrates, which are difficult to pump, cannot be handled unless a tunnel is constructed. Fig. 1 shows an underflow pump arrangement which negates the need for a tunnel but which permits the operator to convey a heavy dense slurry. The pump is mounted directly on the fixed hoist platform and the impeller is located at the base of the steel center column. Priming water is not needed. The column

Jan 1, 1963