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By Alex Harrison, Steve Kasper

Various countries around the world have testing and manufacturing standards in place for steel cord belting. These standards are very comprehensive in what they allow the end user to specify, however, their practical significance in terms of belt life is more difficult to quantify. Such testing standards will be briefly reviewed in this paper in relation to the implication for end user expectancy. Since there is no US standard of manufacture, the end user is left with writing their own specifications. In addition, such standards do not address the effect on belt life of manufacturing faults, such as cord plane buckles, or lateral cord movement. Some new technology used to test steel cord belting will be described as an aid to both manufacturer and end user. Specific end user related issues addressed on this paper are: Tracking and belt quality Cord plane irregularities and performance Cord size and belt life Cord fatigue and testing

Jan 1, 1993

By J. Pflieger

The International Iron and Steel Institute (IISI - http://www.worldsteel.org) has initiated the development of a comprehensive freely-available, internet-delivered package of highly interactive e-learning resources for undergraduate students and steel industry employees. The resulting e-learning environment (http://www.steeluniversity.org) creates a ?one-stop? shop covering all aspects of steelmaking, steel products and applications, the underlying scientific and engineering principles, industrial and academic collaboration, as well as environmental and sustainability issues relevant to the steel industry. The module entitled ?Sustainability, Steel and the Environment? of the steeluniversity.org provides interactive e-learning resources on the following topics - Sustainability. - Principles of Life Cycle Thinking. - Environmental Life Cycle Assessment. - Application of Life Cycle Assessment. The aim of this particular module is to enable the learner to identify relevant environmental parameters over the life cycle of steel products as well as to learn about the resulting environmental effects and impacts. Furthermore he/she will be enabled to explain the basic idea of Life Cycle Thinking and Life Cycle Assessment (LCA) in terms of Goal and Scope definition, System Modelling, Life Cycle Inventory (LCI), Life Cycle Impact Assessment (LCIA) and Interpretation. In addition, the learner can explore selected LCA scenarios facing the steel industry and its customers in the automotive and construction sectors.

Jan 1, 2007

By P. E. Wingrove

The Kayford, Boone and Nicholas Division of Bethlehem Mines Corporation operates a modern coal preparation plant in Van, West Virginia. Since the start-up of the Van Plant in 1976 until the summer of 1980, the refuse handling system proved to be a costly maintenance problem and a material handling bottleneck. During the 1980 two-week miner's vacation the original system, which included two screw conveyors and a drag conveyor, was replaced by an installation utilizing two Flexowall steep angle belt conveyors. This paper describes the technical and economic analysis that led to the new installation and reviews its first year operating performance. The Van facility is a heavy media plant designed to handle 127 mm x 0 raw metallurgical quality coal from the Powellton seam at a maximum feed rate of 590 TPH (metric tons per hour). Depending on mining conditions, the clean coal recovery rate averages between 50 and 65%. The plant is set up with three types of cleaning circuits. Coarse material (127 mm x 12 mm) is cleaned in heavy media baths. Intermediate size material (12 mm x .5 mm) is cleaned in heavy media cyclones. Fine coal (.5 mm x 0) is cleaned in a hydrocyclone1 froth flotation circuit.

Jan 1, 1981

By Raj K. Singhal

Canada produces close to 42 million tonnes of coal per annum of which some 38 million tonnes is produced by surface mining methods. The two Western Canadian provinces, Alberta and British Columbia, produce 31 million tonnes of coal by surface mining. These two provinces provide the bulk of the metallurgical coal for export. The geological conditions in the Western provinces particularly in the mountain region are complex. The coals are friable and the seams are steeply inclined, sheared, intensely folded and faulted. There may be as many as 15 to 20 coal seams present with true thickness ranging from 2.5 m to over 8 m. This paper reviews the surface mining methods used to extract such seams. The difficulties associated with steep seam and multiple seam mining of friable coal resulting in lower coal recovery, high dilution and the problem of cleaning fine coal in the wash plant have been highlighted.

Jan 1, 1984

By K. C. Vories, C. D. Elifrits, F. F. Haston

The required reclamation of land disturbed by surface coal mining often results in the creation of some oversteepened slopes that are prone to rapid erosion and sediment production. This natural activity on such slopes is not desirable nor allowed under current regulations. Experience has shown that novel approaches must be devised to address the problem. Research conducted on field sites in Missouri has indicated that construction, during the reclamation and grading processes, of a man-made drainage system will control the erosion. The drainage system must replicate or exceed the natural system in terms of drainage density and channel frequency. Basic design considerations are summarized in this paper, and field results are shown.

Jan 1, 1987

By C. D. Elifrits

The required reclamation of land disturbed by surface coal mining often results in the creation of some over steepened slopes which are prone to rapid erosion and sediment production. This natural activity on such slopes is not desirable nor allowed under current regulations. Experience has indicated that novel approaches must be devised to address the problem. Research conducted on field sites in Missouri has indicated that construction, during the reclamation and grading processes, of a man-made drainage system will control the erosion. The drainage system must replicate or exceed the natural system in terms of drainage density and channel frequency. Basic design considerations will be summarized in this paper and field results shown.

Jan 1, 1986

By Karin Bäppler

Hydropower produces almost two-thirds of the world’s renewable electricity generation and delivers a major contribution on the ambition of the Paris Agreement and Sustainable Development Goals (SDG) with a range of benefits to society and environment. These include clean and flexible generation and storage in addition to reduced dependence on fossil fuels and avoidance of pollutants. The Limberg III PSP is one of the European projects that addresses the implementation of the UN SDGs. The challenge of the project is the construction of a 770 m long pressure shaft to be excavated with a TBM at an inclination of 42°.

Jun 13, 2023

By J. Mattern

Performance monitoring, operational practices and ongoing collection of geologic data in open pit slopes all provide valuable information for quantifying potential steepening of subsequent slopes. Mining at the Goldstrike open pit has been ongoing since the early 1980’s, with its share of slope instabilities. In areas where slopes have remained stable, consideration has been made for potential slope steepening of final walls. With the proper available equipment, steepening of bench face angles via pre-split blasting is not an uncommon method for steepening of inter-ramp slope angles. As an alternative at Goldstrike, the commonly used Modified Ritchie Criteria for empirical catch bench width has been adjusted resulting in quantified, rock specific formulas for bench width and rock fall berm placement. The result is an inter-ramp slope angle increase of 2 degrees on a 300m high slope, without the necessary purchases and procedural changes that would be required for pre-split drilling and blasting. The result has shown significant net benefits through reduction in mined waste tons and an increase in gold reserves. Location The Goldstrike open pit is located on the Carlin Trend gold belt in northeastern Nevada USA (Figure 1). The mine has produced over 43 million ounces (1.2M kg) of gold during the past 30 years. Engineering Geology Stratigraphy Figure 2 is a stratigraphic section of the rocks in the Goldstrike open pit. Quaternary alluvium and Miocene materials typically are poorly indurated stiff soils and are not present in all locations. Bedrock units consist of siltstones, mudstones, sandstones and cherts. From top down the major units exposed in the open pit are the Vinini Formation, the Rodeo Creek Unit, and the Popovich Formation. In general, rock mass strength increases with depth.

Jan 1, 2019

By Peter V. Avotins

During last year's AIME meeting in New Orleans, Deepak Malhotra and I were discussing some of the topics that would be presented in this Symposium. It seemed appropriate that along with papers on specific reagent and flocculant types, we should address research management aspects of new product development. This development is a long, arduous task that requires a significant technical and fiscal commitment by the chemical company and potential users. A flow chart depicting the research process is shown in Figure 1. The sequence of events are plotted on an undefined time line. Our experience has shown that it takes 3-5 years to complete a typical reagent development project. A new project starts with an idea of how to do something better. The ideas range from relatively simple product modifications to opportunities created by technological change. An example of this is the use of flocculants in tailings operations to close the water recycle loop. The change was brought about by the need to conserve water and comply with environmental statutes. The result was the development and wide-spread use of synthetic polymers to help in solid-liquid separation. More recently the ups and downs of oil prices have led to development of coal water slurries as an alternative to fuel oil. The slurries contain high levels of chemicals (up to 3%) to insure proper stability and burn characteristics. There are technical changes under way right now that may lead to ideas for other new products. One exciting source of new technology is the ability to manipulate genetic material of microbes to select for specific capabilities. This has evolved by leaps and bounds over the past 5 years. Biologically assisted leaching and removal of wastewater impurities are two possible end uses. I'm sure that there are many others. The ideas can originate anywhere and are often half-baked at first, but to lead to new products they must be refined to provide project definition and eventually a research plan. A chemical ,development project cannot be started without approval to commit the company's resources. The internal selling job is often very difficult. The company must see clear financial benefits in order to launch efforts that may not pay off for many years. It is critical to project the total market, profitability, eventual market share, and timing of introduction of the new product. There is much uncertainty in this and the research manager is often skating on thin ice to retain his credibility. Once we obtain support from upper management, the research team is assembled to start the project. The teams generally consist of organic chemists, research metallurgists, and technicians. They have access to analytical scientists and technicians for surface and analytical chemistry. The projects are often augmented by help from university staff and consultants. This is particularly true where there is a need to develop fundamental understanding of the technology in addition to synthesis of chemicals. The project now proceeds along two lines. First, there is an emphasis on understanding the prior art. Extensive literature and patent searches are undertaken to provide research leads and to keep from "reinventing the wheel" and infringing on someone else's patent. The scientists and technologists are qualified to conduct computer-assisted library searches. This process usually uncovers 80-90% of the relevant information. The remainder is very much harder to get and requires the help of professional library search staff with scientific backgrounds. Along with literature searching, the team begins synthesis of new compounds. These are screened by use of techniques such as microflotation or filtration in a Buchner funnel. The scientists are looking for the direction of response as they modify structural features . Inevitably, a large number of candidates reach the next stage, a laboratory bench test. At this point it is possible to set up a research plan and use project management techniques to monitor progress. The bench tests are conducted in larger equipment, usually requiring 100-1000 grams of test substrate. Typical laboratory flotation tests are run in Denver or Wemco cells.

Jan 1, 1986

By P. D. Chamberlain, R. M. Nadkarni, D. J. Kinneberg

Introduction The relationship between precious metal miners and gold refiners has been uneasy over the years. Reasons for this uneasiness and lack of trust include technical factors, economics of scale, and cultural differences. Technical factors take two forms. First, concentrates, precipitates, and sponge produced at the mine site are notoriously difficult to sample. A nonrepresentative sample can be the cause of misunderstanding and distrust. Dote, however, is relatively homogeneous and can be correctly sampled and analyzed with greater reliability. Second, the technology and chemistry of fine gold and silver production is complex and quite different from dote production. Most mining companies are content not to be involved with additional processing steps. From the standpoint of process economies, it is easy to see why miners and refiners are separate groups. Mine location is dictated by the natural occurrence of ore bodies. Heavy capital investment requirements for infrastructure in remote locations usually limits companies to produce the first marketable product from a mine. Beyond that point, the economies of scale and large capital investments for refineries generally dictate that the outputs of several mines be combined to feed a single refinery. The refin¬ing process is so complex that refineries are generally built in larger cities with a skilled labor pool. Therefore, only the largest mines can afford to refine their own output. Lastly, there are cultural differences between the miner and the refiner. The miner, particularly the small gold miner, is by definition a risk taker in a risky business. Refineries, on the other hand, have historically been operated under legal or implied monopolies approved by the government. The government is interested in owning gold, either for currency reasons or because many national mints are major users of gold coins. It is not surprising, then, to find that miners may regard refiners as part of an unresponsive government bureaucracy or, worse, as "city slickers." It is easy for the two groups to distrust each other with these different backgrounds. The interface between miner and refiner does exist and affects nearly all precious metal mining companies and most refineries. This paper discusses the technical and economic aspects of the interface. It points out how both parties can improve the relationship. Technical interface Precious metals selectively dissolve to produce a pregnant solution. They are then recovered from solution by zinc precipitation (Merrill-Crowe process) or by absorption onto activated carbon. This is followed by stripping and electrowinning. At this point, the mining company must decide whether to ship precipitates (or sponge) to refiners or to produce a dote. Some factors the company must consider are the ability to sample precipitates, concentrates or sponge, security of storage, and production rates. An important factor is the incremental cost (capital and operating) of converting precipitates or sponge into dote at the mine. Generally, mines prefer to melt precipitates or sponge to dote to avoid prob¬lems associated with sampling them. There are three types of fur¬naces used by mining operators to melt precipitates to dote. The first and most widely used is a sil¬icon carbide crucible heated ex¬ternally with a gaseous liquid fuel. The crucible is easy to use and slag can be skimmed before pouring dote. This simple system is capable of handling 1 t/a (32,000 oz per year) gold. It could cost as little as $20,000. More complex systems could cost up to $200,000. The second type of furnace is the gas- or propane-fired rever¬beratory furnace. This is usually used only by large-scale opera¬tors in the silver business. Precip¬itates in reverberatory furnaces come in direct contact with the flame. The large volumes of flue gas can carry significant amounts of dust and fume that must be re¬moved from the gas before dis¬charging it to the atmosphere. In the days when the Rand re¬finery in South Africa used reverberatory furnaces, the silver leaving the furnace in the form of vapor and fume was estimated at 2.2% of the total silver charged to the furnace. The gold in the gases was about 0.03% of the gold charged. Most of this silver and gold was recovered in the exhaust gas scrubber system. These scrub¬ber systems can be more costly than the furnace itself.

Jan 10, 1986

By M. D. Lawton

Anglo-Rouyn Mines Limited, managed by Rio Algom Mines Limited is a subsidiary of the British-based Rio Tinto-Zinc Corporation Limited. This mining operation is situated in Northern Saskatchewan, 250 miles north of Saskatoon and represents the first base-metal mine of any importance served by this relatively new mining province. The outcrop of Copper-bearing Chalcopyrite was first discovered by prospectors in 1915, but was not mined until 1965 due to the absence of any form of road into the area prior to this latter date. The mine, mill and concentrator were designed to handle 900 tons per day of comparatively hard, abrasive ore containing chalcopyrite with traces of gold and silver. The flow sheet, Figure 1, is, we believe, elementary, designed with low cost in mind and utilises much old equipment from closed¬-down mines. Due to some difficulty in attaining the designed grinding capacity, changes were made in the crusher circuit. This, unfortunately, lowered the crushing rate too much. A series of changes have taken place to re-establish the original crusher capacity of better than 100 tons per hour. In the quest for a better recovery certain modifications have been tested in the concentrator circuit. These steps are discussed in minor detail.

Jan 1, 1970

By T. Kretschmer, F. Villwock

Conveyor systems are an essential part of many material movements in all conceivable areas of application. They are used to transport goods in raw materials extraction, agriculture, and even articles for daily use. In the process, not only distances of several kilometers but also differences in altitude of several hundred meters are bridged. The layout of the conveyor usually follows the topography at the respective installation site. Particularly in the case of large height differences, safety devices must be provided to prevent uncontrolled movement. Backstops can take over this task in predominantly ascending overland conveyors and are used either as a primary or as a secondary safety system in conjunction with a service brake. They are always used when the system comes to an unplanned standstill, whether due to a power failure, an emergency stop or a defect. When designing backstops, it must be ensured in any case that all conceivable circumstances are taken into account so that failure is ruled out without the product being unnecessarily large in size. Various safety factors are applied, some of which are even prescribed by authorities. One example is the Australian standard on machine safety for bulk material belt conveyors (AS/NZS 4024). This stipulates a redundant acceleration safety device that can absorb at least 150% of the maximum load. ALTRA Industrial Motion with its sister companies Marland and Stieber manufacture backstops for a wide range of applications. With more than 85 years of business activity in freewheeling and backstop applications, they are among the most known and experienced companies and provide a great know-how.

Mar 2, 2022

By E. Steiakakis

This paper presents in detail the procedures followed and the results obtained in order to determine the stiffness parameters of the calcareous marls found in the lignite mines in Ptolemais, Northern Greece. Triaxial tests were performed on representative samples of the inner burden marl and the marl which underlies the lignite bearing series of the region. The tests were conducted under drained conditions, with controlled loading (including an unloading-reloading loop), while the axial strain was measured externally as well as with displacement transducers mounted directly on the specimen (Hall Effect sensors). The geotechnical parameters obtained (i.e., cohesion, angle of friction, stiffness modulus, stress-strain relationship), were subsequently used for simulating the triaxial testing with the Plaxis finite element software. Simulation results are in good agreement with the experimental results. The resulting material model can then be applied to modeling the mobility that is expressed during the excavation of the open pit mines.

Jan 1, 2005

By Gregg J. Hodges

The Stillwater Mining Co. is a partnership of The Pittsburg & Midway Coal Mining Co. and Manville Corp. The Stillwater Mine, located near Nye, MT, is the Western Hemisphere’s only primary platinum-palladium deposit. The mine began production of flotation concentrates in March 1987. In the fall of 1987, an integrated pilot plant testing campaign of electric furnace smelting and oxygen-blown converting confirmed the feasibility of further upgrading to semi-refined matte, or “white metal.” In the summer of 1990, the production smelter was brought on line. The record of the discovery and development of the Stillwater deposit, mine and concentrator has been summarized in several articles (White, 1987; Kennedy, 1987; and Hodges and Clifford, 1988). Similarly, the pilot campaign to test the feasibility of treating the flotation concentrates in an integrated smelting plant has been described (Hodges and Clifford, 1988; Matousek, et al., 1989; and Matousek and Whellock, 1990).

Jan 1, 1991

By D. J. Turk

Stillwater Mining Company’s, Nye Operation has been producing PGM concentrate since 1987.Several expansions have allowed for increasing capacity from the initial rate of 500 tons per day, to its present capacity of 3,000 tons per day. The expansions were performed with minimal impact upon production and maximum utilization of the existing equipment. The latest expansion incorporates a 6’ X 18’ SAG mill, 13’ X 20’ Ball mill, pebble crusher, rougher flotation cells, 1250 Hp tertiary grinding mill, middling and scavenger flotation cells, and cleaner column flotation cells. This paper will describe the concentrator flow sheet, and controls for improved concentrator performance.

Jan 1, 2000

By Gregg J. Hodges

The Stillwater pt-pd mine and flotation mill are located about 130 km (80 miles) southwest of Billings in Stillwater county, M6ntana~ The pt-pd ore zone stretches about 43 km (27 miles), but varies in thickness from 0 to 6 meters (0 to 20 feet, but generally 3-6 feet) and dips 55-90,degrees from horizontal. The ore is hosted in basic, layered igneous rocks containing about 1% sulfide minerals which include chalcopyrite, pentlandite, pyrrhotite, and minor pyrite. The pt-Pd minerals are intimately associated with these sulfide minerals and are found as precious metal sulfides, tellurides, bismuthnides, and arsenides as well as native Pt metal. Approximately 90 different precious metal minerals have been found, but about 80% of the pd is in solid solution in the pentlandite. The ore assays about 0.1% Cu, 0.1% Ni, 6.2 g Pt/tonne (0.18 Troy ounce Pt/short ton (opt)), 21.3 g Pd/tonne (0.62 opt Pd), 0.21 g Au/tonne (0.006 opt Au), and 0.21 g Rh/tonne (0.006 opt Rh). The ratio of pd to Pt in the Stillwater ore and concentrates is about 3.5.

Jan 1, 1988

By Harold G. Arthur

INTRODUCTION Stillwater Tunnel construction is scheduled to start in the spring of 1973. The tunnel will be the site of an extensive program in rapid excavation research. This paper presents a progress report regarding our plans and relates the tentative decisions which have been made on how to carry out the research effort. The details are subject to revision as more input is obtained from other Government agencies interested in tunnel construction and from experts in industry and educational institutions. The objective of the research program is to bring about faster, less costly tunnel construction. This objective will be pursued through the development, improvement, and evaluation of various construction systems and investigative techniques. The need for this kind of program was recognized by the National Research Council, in its authoritative report "Rapid Excavation - Significance, Needs, Opportunities." (1) The Council advocated a federally funded $200 million, 10-year program to help meet the $69 billion market it expects in underground excavation between 1970 and 1990. The significance of tunnel construction to Reclamation is made clear by statistics of its tunneling experience and outlook. Reclamation has constructed 174 water conveyance tunnels totaling over 190 miles, Six tunnels are presently under construction which have a combined length of about 27 miles. There are on the books nine authorized, but unfunded tunnel projects totaling another 70 miles in length. Many more miles of tunnels are included in programs in various stages of investigation.

Jan 1, 1997

Stillwater Mining Company (SMC) has an extensive history with tunnel boring machines (TBM) at the Stillwater and East Boulder underground PGM mines in Montana. The most recent TBM used is for the Blitz Project, where a 5.5m (18ft) diameter main beam unit, commissioned in Q3 2012, is being utilized to drive a 6,975m (22,500 ft) ventilation and haulage level East of the Stillwater Mine for the Blitz expansion project. The assembly/commissioning of the TBM, institution of the planned diamond drilling program, application of ground control systems, and the current tunneling metrics will be covered.

Feb 23, 2014

By K. Vanbroekhoven

An industrial site near the centre of a historical town in Flanders is characterized by chromium(VI) contamination of the groundwater. Since the potential for natural attenuation was not sufficient to control the groundwater plume as observed from different analyses like pH, Eh, soil oxidation and reduction capacity, the feasibility of site remediation based on in-situ bioprecipitation of chromium was examined in lab microcosm studies. By creating reducing conditions by addition of a carbon source in the groundwater, chromium(VI) can be biologically reduced to chromium(III), which can form an insoluble precipitate of chromium(III) hydroxide. Microcosms contained contaminated groundwater and aquifer samples that were collected and manipulated under anaerobic conditions. Three different carbon sources were screened for their effectiveness: molasses from sugar beet production, molasses form starch production (protamylasses) based on potato juice and lactate. The different concentrations of sugar molasses were used to determine the optimal conditions. A range of parameters was monitored at regular time intervals for a period of six months such as chromium(VI) and chromium(III), DOC, methane, pH, Eh. A rapid conversion of chromium(VI) to chromium(III) was observed for all conditions tested. However, extensive removal of chromium from the groundwater by precipitation was only achieved for a limited number of conditions. In general, lactate was found to be the most effective carbon source, slightly better than the lowest concentration of sugar molasses that was tested, which itself was more effective than molasses based on potato. Higher concentrations of molasses, although causing a steeper decline in redox potential, resulted in less effective Cr removal. Typically, the fermentation of molasses results in acidification and this drop in pH may hinder the formation of insoluble chromium(III)hydroxides. It may also be possible that certain components of the molasses form soluble complexes with chromium(III). For lactate, no significant drop in pH was observed. Following the laboratory microcosm tests, the stability of the chromium precipitates was examined by performing a sequential extraction on the microcosm materials. These were performed under redox conditions which were similar to the ones observed in the field. Since the outcome of these tests was positive, a pilot scale test was implemented in the field in April 2005. Two different substrates, the cheap waste product sugar molasses and lactate are being injected creating two different impact zones and typical parameters are monitored. Frequent re-injections were important to maintain reduced conditions and are carried out three-weekly up to now. To study the stability of precipitates formed, mesocosm socks containing aquifer material were installed in the monitoring wells and harvested at regular intervals. Results of this pilot test will be presented and compared to the laboratory results. Based on the success of this field test, a full scale process will be designed and implemented as remediation strategy.

Jan 1, 2006

By J. Partyka

Fumes produced during blasting operations in underground mines are defined in this paper by an equivalent contaminant source. The primary goal is to establish a method which would allow all those parameters not measured directly to be determined reliably from field data. The parameters to be identified are the diffusion coefficient , and the position and size of an equivalent source. The diffusion-value is computed from the peak concentrations taken by two monitors located in the drift. The first monitor is placed close to where blasting pollutants join the main stream, while a second monitors is moved downstream a some distance from the first point. The position and size of the dust source and the total amount of dust produced during blasting are determined from the data recorded by only one monitor.

Jan 1, 1991