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By David M. Kjos

Large diameter autogenous and semi-autogenous grinding mills represent the primary thrust of the expanding grinding technology. In spite of initial difficulties, large autogenous and semi-autogenous mills have reached an acceptable level of technology which provides the mineral engineer with a reliable, low cost means of ore comminution. A successful milling installation begins during the design stage of the grinding mill and the plant it is to be installed in. This is particularly true in autogenous and semi-autogenous mills. Critical mill and plant design factors should be considered while the mill and installation are still only ?paper.? Various current liner designs will be discussed ranging from lifter bar/plate to integral types. Modes of operation such as "high-low" will be considered. Liner maintenance procedures ranging from laydown area in plant design, proper mill shutdown methods, to installation and bolt tightening complete the equation to yield optimum performance possible for any particular grinding application. The objective of this paper is to discuss trends in wear materials, designs and operating practices, and provide some guidelines for good practice as we move through the 1980's. We will put together concepts that relate to the designs, materials and applications so that higher performance can be obtained by the operator for his specific application. The concepts are shown as being in series because they are dependent on each other to achieve the desired performance.

Jan 1, 1985

By W. J. Adamson

Strategic Data Planning (SDP) is an emerging technique for the analysis and design of information systems. This paper describes the use of strategic data planning in the formulation of a complete integrated set of mining technical systems for the Koolan Island iron ore mine. Applications covered include hydrogeology, geology, mine planning, surveying, quality control, laboratory and mine production recording. Koolan Island is 13 kilometres long and 5.5 kilometres wide at its widest point. Its sole industry is an open pit iron ore mine of 3 million tonnes annual capacity, owned and operated by BHP Minerals. Some of the production is used by BHP Steel International, but most is exported. The orebody is steeply dipping and is mined bench by bench. Outturn grades for run-of-mine product are iron 66.5%, silica 3.0%, alumina 1.0%. Computer systems are run on Data General equipment, currently an MV10000. Computer applications, which are shared across mine sites, are developed and maintained by BHP Information Systems in BHP's Melbourne Office.

Jan 1, 1986

By John W. Antalovich

Normally I would like to begin a talk on photogrammetry by defining the word. However modern technology has changed the science so radically that it bears little resemblance to its original definition. Photogrammetry as defined is a science of taking accurate measurements from photography. Today's photogrammetrist, in addition to working with photography, finds himself working with magnetometers, infrared scanners, radiometers, holo¬graphy, lasers, side-looking radar, digital interfaces, computers and countless other modern space age concepts. The modern photogrammetrist is a pilot, photographer, lab technician, mathematician, geologist, programmer, engineer, physicist, and cartographer. His modern instrumentation and many spheres of activity all have a role in the environmental sciences. For example, the magne¬tometer which measures the earth's magnetic fields is used to locate the earth's ore deposits. The infrared scanner captures the heat emitted from the earth to detect ground waters and thermal pollutions. To elaborate on each of his many endeavors would take volumes rather than this short paper. I have elected therefore to discuss what I feel is his most important role in the environmental sciences - that of cartographer.

Jan 1, 1970

By S. R. Dismuke

Ore at the Magmont Mine in southeast Missouri is extracted by the room and pillar method on two and sometimes three horizons. In 1991, an innovative plan was formulated for recovery of high grade ore in pillars using cable bolts to accommodate spans of more than 27 m (90 ft). A test area was subsequently selected and a recovery plan developed. A cooperative rock mechanics study effort by COMINCO METALS, the U.S. Bureau of Mines and the University of Utah was later established. When initially opened in 1968, the planned production rate was about 1,000,000 tons per year. Due to declining reserves, the production rate was decreased to 630,000 tons per year in November 1992. Pillar recovery now accounts for approximately 40%-50% of the mined tonnage and plays a vital role in allowing Magmont to continue to operate.

Apr 13, 2011

By W. R. Reed, S. Klima, J. Driscoll, T. W. Beck

"Tests were conducted to determine properties of 4 foam agents for their potential use in longwall mining dust control. Foam has been tried in underground mining in the past for dust control and is currently being reconsidered for use in underground coal longwall operations in order to help those operations comply with MSHA’s lower coal mine respirable dust standard (1.5 mg/m3). Foams were generated using two different methods. One method used compressed air and water pressure to generate foam, while the other method used a low pressure air generated by a blower and water pressure using a NIOSH developed foam generator. Foam property tests comprising of a bottle shake test, foam expansion ratio, and water drainage were used to classify foams. The bottle shake tests determined that the lowest concentration of foam agent to be used was approximately 1.5%. Compressed air generated foams tended to have low expansion ratios (10-19) with high water drainage. Blower air generated foams had higher foam expansion ratios (30-60) with lower water drainage. Foams produced within these ranges of expansion ratios are stable and potentially suitable for dust control. The different foam agents produce foams with different material properties. Results of testing eliminated two foam agents for future testing because they had poor expansion ratios. The remaining two foam agents, while having different foam properties, seem to have properties adequate for dust control. These material property tests can be used to classify foams for their potential use in longwall mining dust control. INTRODUCTION About one-half of U.S. underground coal is produced by longwall mining. This technique allows for mining high volumes of coal, producing significant amounts of coal mine dust. This can lead to the overexposures to longwall miners and possibly occupational respiratory diseases black lung and silicosis, which have no cure and can be disabling or fatal. The only method to avoid these occupational illnesses is through elimination of exposure to respirable coal mine dust and crystalline silica (quartz). The current occupational exposure limit for respirable coal mine dust is 1.5 mg/m3 during each shift that a miner is exposed in the active workings of the mine or in mine facilities [1]. When respirable quartz is present, the mine must maintain an average concentration at or below 0.1 mg/m3. If the mine exceeds the 0.1 mg/m3 respirable quartz dust concentration, then the applicable respirable dust standard is reduced, calculated as 10 divided by the percent quartz present [2]. Respirable dust samples collected by U.S. Mine Safety and Health Administration inspectors for the five-year period from 2010 to 2014 found that 5.6% (53 of 943 respirable coal mine dust samples) of the longwall operators on the tailgate side exceeded the coal mine dust standard, and 4.3% (76 of 1768 samples) of the jacksetters exceeded the standard. If silica is present, the reduced standard is implemented, meaning that 11.4% (36 of 316 respirable coal mine samples analyzed for dust) of the jacksetters exceeded the reduced standard. Only 3.8% (18 of 478 samples) of the longwall operators on the tailgate side exceeded the reduced standard [3]. Had the 1.5 mg/m3 standard been in effect during this period, non-compliant samples would have been much higher. For example, over 15% of the samples collected at the tailgate shearer operator occupation exceeded the lower standard."

Jan 1, 2017

By Elwyn H. King, Thomas R. Kuesel

I. CONCEPT MARTA's Peachtree Center Station is being mined out of hard rock, directly beneath Atlanta's central business district, with minimal surface disruption during construction. Its cost is competitive with that of a conventional cut-and-cover alternative owing to its design concept, which utilizes the rock as a primary structural and architectural material. II. PLANNING The station was originally planned for cut-and-cover construction. However, Peachtree Street is unusually narrow for a main business street (generally 78 feet (24 m) between building lines) and cut-and-cover construction would therefore be very disruptive to surface traffic and severely restrict access to adjacent buildings, including Peachtree Center, Atlanta's showcase business/commercial complex. (See Fig. 1.) Tunneling had been considered, but was initially thought [ ]

Jan 1, 1979

By Manfred Hager

The ability of conveyor belts to transport large mass throughputs economically over previously unprepared ground has resulted in this system achieving great and extensive use. A significant component in this development is the conveyor belt itself. The development of high strength steel cord conveyor belts involves the optimising of splice design, the use of excellent rubber material especially in the splice, good craftsmanship during splice production and modern field vulcanisation equipment. The durability of a splice for belts of class St 3000 up to St 790 is expressed by the fatigue strength under dynamic stress. The results obtained with a test method and equipment developed by the University of Hannover indicate the present state of the art in this field. Belts of high nominal strength used on inclined long distance conveyors reach splice fatigue strengths of about 3000 N/mm. The design should only exploit approximately 50% of the fatigue strength determined in the tests as maximum operating stress. IMPORTANCE OF CONVEYOR BELT SYSTEMS The use of conveyor belt technology has expanded considerably over the last decades in the bulk goods transportation sector. Because of the favourable transport costs and the technology's adaptability to specific topographies, belt conveyors frequently represent the most economic solution. When flows of goods are large, as in German lignite mining operations, where masses of up to 40,000 t/h are given, it is the only technically feasible alternative. The use of belt conveyor systems allows the sensible distribution of the waste and the production of the coal (Hager, 1981). But this transportation alternative is also suitable when the masses involved are smaller. Whereas conveyor belts were only suitable for loose bulk goods up until a few years ago, today they are frequently also used for hard rock open cast mines, e.g. in the production of copper ore. Because of the favourable transport costs it is frequently still economic to use mobile crushers with a throughput of up to 10,000 t h 6 which breakdown the large blocks produced y explosives into transportable grain sizes. In many operations, trucks are only used to provide flexibility between the excavator and the crusher, i.e. over short routes, and the long, frequently steep, transport paths to the processing plant or to the spreader are undertaken by belt conveyors (Einenkel et al., 1992). The advantages of belt conveyors, i.e. to cope with large mass flows over inclines and down slopes of up to 1:4 have resulted in this system gaining very extensive use throughout the world. The conveyors can be installed over for the most part unprepared ground with suitable vertical radii, adapted to the locally available belt material. In the process individual conveyor belts with lengths of up to 15 km, and in the underground sector with lift heights of up to 1 km, have been built and operated. This great variety of application possibilities is complemented by a limited ability to pass through horizontal curves. This can be achieved with the help of design measures on the conveyor whilst bearing in mind the characteristics of the belt. STRESSING OF CONVEYOR BELTS IN DIFFERENT TYPES OF PLANT The advantage of conveyor belts compared with other systems is also to be found in the large available service-time window, i.e. the excellent reliability and the low costs of energy consumption and maintenance. It is in particular the reliability of a belt transport system which depends to a great degree on its main component, that is the belt - in all its different types and variations. For this reason, the belt is also given the greatest attention in the development of the individual components, because it is the belt which must be designed optimally with regard to various factors. The specific properties of the conveyor belt then assert a considerable influence on the design and sizing of most other components in a

Jan 1, 1993

By Dermot M. Winters, Brent T. Wahlquist, C. Y. Chen

The enactment of the Surface Mining Control and Reclamation Act (SMCRA) in August 1977 addressed subsidence resulting from underground mines, in addition to creating the requirements for reclamation of surface coal mines. Subsidence control regulations pursuant to SMCRA were initially promulgated in March 1979. Several revisions have since been made. In addition, due to court challenges some regulations have been remanded and others are still on appeal. In the meantime the Secretary has agreed to initiate rulemaking on some issues. It is yet to be determined how the prohibition of certain areas from surface coal mining operations under Section 522(e) of the Act applies to subsidence. This presentation discusses the status of the regulations and issues related to or affecting the subsidence regulations.

Jan 1, 1986

At present the feasibility of developing underground facilities for the storage of a number of products including toxic waste, oil, nuclear waste and low pressure gas is under investigation in e number of countries. A possible method of storage is in large excavations, Preliminary ventilation design work has identified that the climatic conditions encountered within these large excavations are a limiting ventilation pollutant within the ventilation system. This paper examines the design of a variety of sizes of excavation from a ventilation viewpoint. The main phases of an excavations lifetime can be divided into four main phases, these being construction, civil and mechanical fitting, storage, full and sealed. The paper details ventilation design options for the first two phases of e vaults lifetime, giving climatic simulations to assess the likely climatic conditions within the excavations for e number of facility depths. The options for climatic control are given and analyzed by means of climatic simulations techniques. l. INTRODUCTION The feasibility of developing underground facilities for the storage of a number of products is under investigation at present in a number of countries. This paper details a possible design for such a facility where the product is to be stored in large underground excavations. A facility layout has been designed with the aim of allowing concurrent construction and storage operations. Thus from a ventilation perspective the facility consists of two circuits , a construction ventilation circuit and a product ventilation circuit both of which are served by an intake and a return surface connection The construction and storage circuits are considered as independent of each other , any interaction in the form of leakage must be from the construction to the storage circuit. From the facility design a ventilation network was developed to assess the ventilation requirements of the facility. In analyzing the pollutant loads for the construction circuit two pollutants were recognised to be critical to the ventilation design , these being diesel exhaust fumes and heat end humidity. In this paper ventilation design options for the construction and civil and mechanical fitting phases of the excavations are analyzed by means of climatic simulation and options for climatic control within the vaults are outlined . 2. FACILITY DESIGN A schematic diagram of a facility design is illustrated in Figure 1. There would be two distinct ventilation circuits , one to service the construction operations and the second to serve the storage operations which occur concurrently with construction , the circuits are separated by ventilation bulkheads . Access to the facility for intake air is provided by two drifts, one to serve each circuit. Two shafts act as returns to surface. The facility consists of two distinct zones for the storage of two types of product. One type is to be stored in smell linear excavations. The second zone is for the storage of a second product in larger excavations. The maximum cross-sectional area and perimeter for the smell linear excavations are 456.25 m2 and 83.2 m, while for the larger excavations they are 440.1 m2 and 86.4 m. Excavation construction consists of three phases: 1. Initial pilot tunnel development between main intake and return to provide through flow ventilation. 2. Enlargement to produce the required finished cross-section. 3. Civil and mechanical engineering work to fit out the excavation ready for storage. It is proposed to excavate the excavations using drill and blest methods utilising diesel equipment. Spoil is to be transported to surface by a conveyor belt system. At any one time the maximum number of working places requiring ventilation will consist of ; 3 storage sites, 2 excavations under construction, 2 excavations undergoing civil and mechanical fitting. [ ]

Jan 1, 1993

By H. M. Breza

Recovery of phosphate concentrate has received increased attention as the existing mine and plant production capacity limitations of the Texasgulf Inc. Aurora, North Carolina Mine are reached. Improved mining techniques and mineral processing of waste streams offer a potential to increase overall phosphate production without major expansion of the Mining facility. Innovative processes have been or are being identified to maximize pit mining recovery and to minimize losses in waste streams, resulting in more effective use of the valuable phosphate natural resource. This paper will describe the various continuous recovery improvement programs being implemented to achieve this goal.

Jan 1, 1994

By Randall J. Essex

The Construction Institute of the American Society of Civil Engineers recently published the second edition of a 1997 publication on geotechnical baseline reports. The new publication, called Geotechnical Baseline Reports for Construction, Suggested Guidelines, represents a 2-year effort that adds three new chapters to the original publication, as well as capturing practitioner commentary through two industry workshop sessions. The paper will overview the contents of the new publication, particularly the three new chapters.

Jan 1, 2008

By Behrouz Tehrani

The size, complex issues, and requirements to construct large number of tunnels, for a single project, expeditiously, and without exceeding the overall project budget, a program Construction Management (CM) team is highly recommended to be selected early during design process to provide guidance/direction relative to contract packaging and scheduling. This paper is not focused on the project itself, however, the emphasis is on experiences gained from the project. Wishing that some of the strategies described in this paper will be of value to owners of underground project.

Jan 1, 2008

By J. O. Marsden

The Candelaria copper-gold mine is located approximately 25 km south and east of Copiapo in Region III, Chile. The original concentrator was designed to treat 28,000 t/d (30,800 stpd) of chalcopyrite-bearing ore through a circuit consisting of a single 11.0 m (36 ft) diameter SAG mill, two ball mills, conventional rougher and scavenger flotation, column cell cleaner flotation, and ceramic disc filtration. The plant was commissioned in August 1994 and quickly reached capacity and expected levels of metallurgical performance. In May 1996, a decision was made to double the capacity of the concentrator by the addition of a second line of equipment. The expanded facilities were commissioned in October 1997, less than 18 months after the decision to proceed, and well within the budget. The original concentrator facilities were replicated or duplicated as much as possible, however, a number of important equipment changes were made to take advantage of industry developments since the original concentrator was designed. These included the use of Eimco 120 m3 (4,200 ft3) cells for rougher and scavenger flotation and the installation of a Svedala VTM -800 Vertimill for regrinding. This paper describes the rationale behind these changes and explores the reasons for the success of the project.

Jan 1, 1999

By Roy A. Grancher

?The Horn of Plenty seems to have sprung a leak?.? anonymous For the first time in the Nation's peace-time history, shortages have become a way of life for the United States. Such words as scarce, tight, and critical are used in regard to supply, leading to priorities, allocations, and possible rationing as make-shift attempts to satisfy demand. Almost every day a new type of shortage appears in another product area that has traditionally been taken for granted as being in perpetual abundance. The range of coverage extends from basic commodities such as oil, chemicals, cement, steel, copper, cotton, etc., through to machine tools, motors, bearings, electronic components, etc. , to those finished outputs that satisfy our fundamental requirements for food, clothing and shelter. Signs of the times appear in cancelled airline flights, unfilled lines at gasoline stations, no available home freezers, lengthy delays in any furniture deliveries, or to that little old lady seen walking out of a local supermarket clutching her hoard of twenty rolls of toilet paper. What a sad commentary to have to make about our Land of Plenty, so long the envy of the World for its material wealth -- and today with its initials "U. S." seemingly standing for ?Unlimited Shortages.?

Jan 1, 1974

By Thomas F. Joyce

N L Industries, Inc., MacIntyre Development produces ilmenite and magnetite concentrates from its own open pit operation at Tahawus in New York's Adirondack Mountain region. The ilmenite concentrate is used within the company for the production of titanium dioxide pigments and the magnetite concentrate is sold to heavy media processors. Current production is from South Extension mine, loading by by six-yard Marion electric shovels into 85 ton Lectra Haul trucks. Bench heights are 44' and are drilled with a Robbins Rotary 9 7/8" diameter hole on 25' spacing for a yearly production of 3.4 million total tons of rock. The ore deposit occurs in veins dipping on the average at 40 degrees to the west. The ore body, which is divided into three zones, outcrops at surface and continues to depths of 800'. Zone 1 is a high grade band of thickness 150-200' with an Fe/Tio2 ratio of 2. Below this band is Zone 2, a low grade band of thickness 50-100' with an Fe/Tio2 ratio of 2 and beneath that seperated by a band of anorthosite is Zone 3, a high grade band of irregular thickness 50-450' with an Fe/Tio2 ratio of 1.6.

Jan 1, 1973

By J. Kennedy

Rare Earths: Understanding The United States complete failure of status and relevance in Rare Earth Oxides, Elements and Alloys. Although rare earth oxides are strategic and critical in their own right, elements and alloys are even more important for the development of "Green Technologies" and advanced weapons systems. America does not have an active domestic source of rare earth oxides. America does not have any Heavy Rare Earth Elemental or Alloy capabilities. The magnitude of this failure continues to become more apparent as the manufacture of REO based electronics and magnetic components moves eastward towards China. China has succeeded in outmaneuvering The United States and the world in its quest to control the Rare Earth Oxides, Elements and Alloys, and the many industries dependent upon REO. What can be done?

Jan 1, 2010

1. Theory of Wet Dust Suppression Techniques Wet dust suppression is the utilization of a liquid for the control, reduction or elimination of airborne dust, or the suppression of such dust at its source. Effective control involves: a. The confinement of the dust within the dust producing area by a curtain of moisture. b. The wetting of the dust by direct contact between the particles and droplets of moisture. c. The formation of agglomerates too heavy to remain airborne, by combining small dust particles with each other and with the droplets of liquid. From the standpoint of economy, availability and safety, water is the ideal fluid. From the standpoint of effectiveness, however, it leaves much to be desired. As a result, a tech¬nique has been devised in which very small percentages of specially formulated dust control compounds are blended with water to greatly enhance its dust suppression qualities. The terms "dust control compounds, wetting agents and surface active agents" are frequently used interchangeably. Although dust control compounds represent a specific type of wetting agent, a great many wetting agents are far from satisfactory for dust control. "Wetting Agents" is a broad category which covers such items as emulsifiers, solubilizers, detergents, foamers, penetrants, thickeners, etc. Dust control compounds, on the other hand, are carefully formulated blends in which one or more special surface active agents have been incorporated.

Jan 1, 1972

By J. Schoenbacher

Park City Municipal Corporation (PCMC), long before being recognized as an Olympic venue was known as one of the great American silver mining towns. During a century of active mining, the Park City mining district produced millions of ounces of silver in addition to a substantial amount of mine tailing waste. Since 1985 the City has been remediating these impacts with state and federal oversight. One particular challenging CERCLIS site, that was previously a historic mine tailings pond is known as Prospector Square Development (CERCLIS Listing Silver Creek Tailings UTD98051404). This site has been very challenging due to the metals that impact the shallow ground water that eventually drain into the Silver Creek Watershed. To address the water quality impairment the City and Missouri University of Science and Technology teamed up to investigate the feasibility of constructing a horizontal-flow wetland to treat this pollutant source. This effort began with the building of a pilot cell in June of 2004 and lead to the construction of a full scale horizontal-flow wetland in the fall of 2008. The design of the pilot and full scale biocell was based upon lab-scale research conducted by the Missouri University of Science and Technology. In October of 2008, the Prospector Drain effluent was introduced to the system and to date analytical results reveal that the biocell is treating the Prospector Drain outfall below the Silver Creek Total Maximum Daily Load (TMDL) endpoint goals for zinc .39 mg/L and cadmium .00075 mg/L. The water chemistry of the influent, that originates from the historic silver mine tailings pond, is impaired with zinc and cadmium and has low iron with a pH of roughly 6.5. The construction of this unit encountered many challenges related to constituent relations, regulatory scrutiny, constructability and start-up. Nonetheless, since implementation this unit is considered a success for improving water quality within the Silver Creek Watershed.

Jan 1, 2011

By P. Semberg, B. Bjorkman, C. Andersson

"In this study, the interaction between magnetite and the additive olivine was studied after oxidation as well as after isothermal reduction at temperatures in the 500º-1,300º C range. In the olivine sample, the forsteritic olivine particles react partly during the oxidation pretreatment to form magnesioferrite and vitreous silica along the particle corona. This breakdown of the olivine particles during oxidation liberates magnesium from the particles, which do not react until temperatures of above 1,150° C in reducing atmosphere. When the hematite in the sample is reduced, and when the temperature is high enough to allow solid-state diffusion at ~800º C, the magnesium of the magnesioferrite redistributes, so that the magnesium concentration approaches the same level throughout the iron oxide structure. For magnetite, this did not occur until 800° C. At 1,000° C, this magnesium reacts further with the silica in the glassy slag phase, which crystallizes into fayalitic olivine. At this temperature, the magnesium has diffused over distances of more than 600 µm from large olivine particles after 2 hrs reduction. From this point, the primary slag phase in the pellet, until melting, is solid fayalite. Upon reduction to metal, the metallization front concentrates the MgO in the remaining wustite, which can lead to MgO levels of up to 10 mole% locally. The melting point of the fayalite is raised from 1,145º C to a melting range of 1,238-1,264º C due to the MgO increase, as estimated based on phase diagrams, which were adapted to the pellets tested. Much of the olivine that remained unaltered in the oxidation process will be encapsulated by iron before the particles begin to dissolve in reducing conditions and, therefore, plays no role in the reduction before final melting of the particles occurs.IntroductionEnvironmental concerns have placed increasing pressure on the CO2-intensive iron and steel industries to further optimize operation toward higher productivity and more efficient use of reducing agents. At the same time, high demand for iron ore has caused new iron ores with lower grades and more complex chemistries to be taken into production. In Scandinavia, the main iron-bearing material is magnetite-based pellets with olivine, which allow operation with very low slag volumes and, hence, lower fuel rate ( Slagnes and Sundqvist Ökvist, 2008; Hallin et al., 1994). Both the MgO and SiO2 of the olivine, as well as the elements of the gangue of the ore, i.e., Si, Mg, Ca, Al and alkali, interact with the iron oxides to give the finished pellet product its final properties in the blast furnace. Tailoring the additive mix to be used for a certain iron ore for optimal product properties, therefore, requires detailed knowledge of the mechanisms by which these elements dissolve and react in the pellet."

Jan 1, 2015

By V. Svalbonas

The process of grinding mill quality assurance brings with it associated truths and myths. When the mill quality assurance process took its first great steps forward in the late 1970s and early 1980s, they were in response to the conditions existing, in our industry, at those times. In the late 1990s, we are faced with different conditions, and problems, and need fresh solutions. Yet the system developed for the early 1980s has produced no new approaches for the late 1990s, becoming instead more hardened and entrenched. This lack of development and actual resistance to research is now costing the industry significant amounts of money in late start-ups and useless scrap loss.

Jan 1, 1999