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By Jack S. Watson, Rasika Nimkar, Robert M. Counce, Matthew Gordy, Patrick Zhang

Waste phosphatic clay presents a difficult disposal problem and a significant loss of P2O5. Recent developments make this study on the use of phosphatic clay as a feed material for H3PO4 production worthwhile. (a) New data from Florida Industrial and Phosphate Research Institute (FIPR) suggest that the Bclay^ waste can be effectively treated by improved solid separation coupled with flotation to produce feed material for recovering additional phosphate. (b) The use of BOLI Flowsheet^ provides capability to predict performance of aqueous-based processes for a range of possible operating conditions. Using the new FIPR data and BOLI Flowsheet^ enabled the design of a new process that can potentially extend the usefulness of current P2O5 ore deposits. Predictions using OLI Flowsheet were able to identify process conditions that effectively overcome the difficulty of high Mg content of phosphatic clay. Estimated manufacturing cost in the current study lead to valuation of the P2O5 content of the phosphatic clay recovered/utilized at 60 to 70% of that of the phosphate rock feed material currently used. Phosphatic clay should be considered as a valuable material that is currently given zero value. The new FIPR data and BOLI Flowsheet^ enables the design of a new process that can potentially extend the usefulness of current phosphate ore deposits by extending the fraction P2O5 of recovered

By George L. Wilhelm

Timber support of mine openings continues to be an effective system for ground support, due to its avail¬ability, flexibility, and ease of installation. Timber support of mine openings as a primary method to support loose rock has been replaced to a large extent by rockbolting and by filling systems. How¬ever, the many designs of square-set timber and varia¬tions of crib and stull support that have been developed to suit many stope configurations have proven reliable over many years of application. Integrated in modern excavation and stoping methods, timber remains an im¬portant ground support material for today's mines. ADVANTAGES AND DISADVANTAGES OF TIMBER SYSTEMS Timber, when used as a part of the total support system, is recognized for its unique support properties. More than a cover to prevent minor falls of ground, timber systems have been carefully designed to provide adequate support with sufficient compressive qualities to achieve a safe working environment in extremely diffi¬cult ground conditions. In some cases, a timber support method is designed to yield while retaining its protec¬tive support qualities. Little or no initial investment in equipment or plant is required for incorporating timber into the mining support system. Low cost cutoff saws and portable chain saws are sufficient equipment for effective use of dimen¬sioned (sawed) or round (stull) timber support. Until recently, small sawmills of various complexity were com¬mon at mine surface plants. Sawmills at the mine sites have generally been replaced by timber vendors' mills. Suppliers have been able to use efficient cutting and lumber handling methods to reduce the cost of mine timbers. Most suppliers will package dimensioned mine timber into bundles that are suitable for handling down mine shafts and on level conveyances. The principal disadvantage of timber as a support method is higher material cost and labor cost associated with its labor-intensive installation. Furthermore, stand¬ing timber reserves of mine quality wood are in short supply in some areas, and heavy competition exists for alternative uses of the timber supplies. Vendors are reluctant to supply large cross section dimension tim¬bers relatively free of defects. Some mine operations require 4.8-m (16-ft) lengths of firm timber over 0.09 m2 (144 sq in.) in section and these are difficult to obtain in large quantities. APPLICATION OF TIMBER FOR MINE SUPPORTS Timber used in mine support has been cut from many species of trees. A firm hardwood with physical properties similar to western Douglas fir has been pre¬ferred in the US. Other harder and softer woods, how¬ever, have been used when readily available or where the specific strength or crushing quality of the wood is a desired specification of the support system design. Hard¬ wood, commonly oak, has been used where maximum crushing resistance is required. Mahogany and fir are widely used for shaft guide timber. Normally, timber is used with its core axis parallel to the long axis of the timber dimension. However, in some cases, it is placed normal to its core in a "butt" log position, so as to provide maximum resistance to abrasion of the ore passage adjacent to the cut end of the block. By selective placement of timber block¬ing, controlled resistance to ground closure can be achieved which will prevent early failure of primary sup¬port members of the timber structure. Timber is widely used in modern mining operations as a construction member for chute-lip support. These designs are tailored to each operation to conform to the dimensions of the haulage equipment being used. As a construction material, wood requires none of the spe¬cial equipment necessary for placement of concrete or steel support. Placement of these alternate support ma¬terials requires carefully dimensioned and engineered excavation for their installation. Wood can be easily sawed to fit on location. The successful use of timber in heavy ground de¬pends on the careful and accurate placement of block¬ing and bracing to achieve the controlled yielding re¬sistance needed to support the mine opening. Similarly, frequency, size, and placement of top and bottom block¬ing stulls in flat-bedded deposits are carefully determined to provide adequate support at the mining face. Con¬trolled caving through failure of the stulls may be required as the scope retreats from the earlier mined-out sections. The support program must achieve both of these dimensionless qualities by specification of stull frequency and size. The utility of the square set-system of ground sup¬port and timber support is described in Chap. 2, re¬printed from US Bureau of Mines Information Circular 6691. Four examples of effective use of timber for support of stoping and other mine openings are pre¬sented in other chapters in this section. The Gilman mine's use of Mitchell slice stoping described in Chap. 3 is an early modification of the square-set mining system. This application proved reli¬able for heavy ground and overcame some of the dis¬advantages of conventional square-set timber. Chap. 4 describes the Burgin mine's use of timber with other reinforcement material. This combination of materials achieved high strength and control with yielding com¬ponent members necessary for heavy, squeezing ground. Chap. 5 describes the Bunker Hill mine's use of square¬set timber in a new configuration that provides an effi¬cient and safe support for stoping using small load¬haul-dump (LHD) mobile equipment. Chap. 6 describes some considerations in placing the widely used stull in bedded ore deposits. Finally, in Chap. 7, cost calcula¬tions for

Jan 1, 1982

By O. Kangal

Flame retardant materials can be incorporated or applied to products, including plastics and textiles, to increase their resistance to fire. Incorporating a flame retardant in combustible materials and plastics is a common procedure to reduce the risk of fires. Flame retardant applications include interior and exterior woods, structural steel columns, fabrics, open and closed cell foam, pressure treated wood, Formica and all types of fabrics for use in commercial applications as well as residential applications where their fire protection products can save lives and valuables. Huntite and hydromagnesite are amongst the most important flame retardant additives materials. Although various areas of the world have potential huntite and hydromagnesite deposits, their place in industry is not well known, and a detailed field search for their deposits has not yet been conducted. They are active during the starting phase of a fire, in that they prevent the spread of an inner or exterior source of ignition to the flame-retarded material, thereby, preventing, delaying or inhibiting the spread of a fire. Flame-retardants are, therefore, just one element among many in a concept for preventive fire safety. To obtain huntite and hydromagnesite concentrates that are more than 95% pure, which are used in flame retardant industry, flotation tests were conducted on low-quality huntite and hydromagnesite ores.

Jan 1, 2009

By J. Olsson

Introduction Stainless steel has by tradition been a common construction material for hydrometallurgy processes and the most common grades can be found amongst the ASTM 300-series, i.e. austenitic grades of type 304L, 316L and 317L. However, there are a number of new grades available today, which imply more cost effective solutions for those designing plants where good resistance to acids, containing the desired metal ions, often contaminated with chlorides and other halides, is the key issue. There are austenitic-ferritic or duplex grades having the same or even better corrosion resistance than the austenitic grades and approximately twice the strength, which enables design in thinner gauges, which in turn implies less weight and less cost. They have also excellent engineering properties, enabling fabrication of process equipment, machinery and different types of tanks. On top of that, they contain less nickel and molybdenum than their austenitic counterparts, which implies not only lower cost for alloying elements, but also a more stable price when considering the price fluctuations for these alloying elements during the last years. This paper describes briefly the family of duplex stainless steel and it presents a number of relevant corrosion tests where duplex grades have been compared with austenitic grades. The results have in several cases been verified by in-plant exposures in zinc and copper production plants. It also describes applications and experience of duplex grades within a variety of hydrometallurgy plants. Installations of highly alloyed austenitic grades will be described as well. The corrosion tests and service experience reported cover hydrometallurgical processes based on sulphuric acid.

Jan 1, 2007

By J. Kang

To obtain microbial cultures with the ability to efficiently leach copper ion from chalcopyrite, microbial samples from acid mine drainage sites were mixed and then subjected to mutation using sodium nitrite (NaNO2), diethyl sulfate (DES), ultraviolet light (UV) and their combinations. Mixed cultures with a much stronger ability to leach copper ion (identified as mixed cultures A, B, C, D and E) were obtained by screening on leaching media. Leaching tests showed that mixed culture E had the best leaching performance and increased the Cu2+ content by 120.5% in 20 days, compared to a control without mutation treatment. Mixed culture E grows well on Leathen leaching medium supplemented with Cu2+ (at a final concentration of 32 g/L), reaching 3.2 × 107 cells/L after 15 days, while the unmutated control culture cannot survive beyond 15 days, indicating that mixed culture E is more tolerant of high concentrations of Cu2+. In addition, continuous leaching by mixed culture E is very effective at a pulp density of 1%. These results suggest that it has the potential for industrial applications.

Jan 1, 2008

More than 410,000 visitors from 171 countries helped bauma ’04 set new attendance records at the world’s largest construction machinery and mining technology show. The show, held in Munich, Germany March 29-April 4, marked bauma’s 50th anniversary. At the last bauma show in 2001, attendance was about 406,000 people from 157 countries. At bauma ’04, international attendance increased to 31 percent from 27 percent in 2001. In addition to record-setting attendance, bauma ’04also attracted 2,801 exhibitors, up from 2,341 in 2001. Exhibitors came from the United States, Europe, China, Japan and the Middle East. Exhibitor space topped 500,000m2 (5.4 million sq ft), another record. And, for the first time, there were more foreign exhibitors than German exhibitors, show organizers said.

Jan 1, 2004

By O. A. Lima

Effective solids suspension is a necessary precondition for particle collection, and solids suspension is largely dependent on the hydrodynamics of the flotation cell. This study attempted to correlate the status of the suspension of apatite particles of different sizes in a Denver laboratory flotation cell versus the impeller rotational speed (N) adopted to operate the machine. The latter variable (N) influences the impeller capacity to lift the particles from the bottom of the tank and also to disperse them throughout the volume of the vessel. Such an impeller capacity can be characterized by the critical impeller speed for the accomplishment of solids off-bottom suspension (Nz) and also by the velocity of the radial water flow discharged by the impeller (U) divided by the particle terminal settling velocity (Us). This way, the status of the suspension of apatite particles inside the flotation cell can be characterized by one of three categories: ?segregation? (N/N2 < 0.60 and Us/U > 0.08); ?suspension? (0.60 = N/N2 < 1 and 0.06 < Us/U < 0.10); and ?dragging? (N/N2 = 1 and Us/U = 0.03). The range of impeller rotational speed (N), which was able to suspend the finest particles (Dp = 90 µm), was unable to suspend the coarsest particles (Dp = 254 µm). Conversely, the high value of N (N > 1,300 rpm), which is adequate to suspend the coarsest particles, may promote the entrainment of the finest particles to the froth layer.

Jan 1, 2009

By John A. Breslin

The year 2010 will mark the 100th anniversary of the beginning of the research efforts by the U.S. government to improve the health and safety of miners working in the United States. This research began in 1910 with the establishment of the U.S. Bureau of Mines (the Bureau) and it has continued during the past 10 decades, even after the closure of the Bureau in 1996. The research on safer mining technology, formerly done by the Bureau, has now been combined with National Institute for Occupational Safety and Health (NIOSH) studies of miners? health to form a unified federal research program to improve the health and safety of miners. This article describes this research and places some of the accomplishments into perspective with other activities in the U.S. Mine Safety and Health Time Line (insert).

Jan 1, 2010

By M. D. Ross

Complex combinations of technical, economical, safety and environmental factors are causing mining engineers everywhere to review their operations. Naturally, some of the traditional methods still have a large role to play because they are, in certain circumstances still adequate and are well understood. But, as circumstances change, a new approach is required. The combination of technical and economical reasons for introducing Long- wall mining in some seams in the United States is associated with strata control. Other reasons include simplifications and improvement of ventilation, reduced coal dust, more output from each unit and crew, increased percentage of recovery from each area of the coal deposit, and reduction of rock dusting. The innovations which transformed Longwall mining from a cyclic to a continuous mining system were the armored conveyor and power loading machines, but the crucial breakthrough for application to high production was the development of the powered roof support, which at once gave the system the advantages of mastery of strata control, increased rate of advance, significant reduction of manpower, and increased safety.

Jan 1, 1974

By Edward Hall Smith

The E1 Indio Mine is located in the Andes mountains about 180 kilometers East of La Serena, capital of the Fourth Region of Chile. It is reached by an international highway running up the Elqui Valley as far as Juntas from where the last 42 kilometers is on a road constructed by the Company. The plant is located at 3.900 meters above sea level among extremely rugged terrain with nearby mountains rising about 5.500 meters. Climatic conditions at these altitudes are severe with winter temperatures down to -20°C. Snow storms lasting several days and leaving up to two meters of snow have been experienced, while fierce winds are corm=.

Jan 1, 1984

By Z. Hyder, M. Karmis

Underground or In-situ Coal Gasification (UCG or UICG), though not a new concept, is now attracting considerable global attention as a viable process to provide a "clean" and economic fuel from coal. Applying improved UICG technology to gasify deep, thin, and low-grade coal seams could vastly increase the amount of exploitable reserves. However, it is imperative that further development of this technology is based on integrating UCG practices and potential environmental impacts with accepted sustainability frameworks and processes. This paper evaluates the potential of UCG to conform to frameworks such as MMSD (Mining, Minerals and Sustainable Development), Natural Step and Green Engineering, in order to define its "sustainable" potential. The paper also discusses the potential contributions of UCG to sustainability during its design, operation, closure, and post-closure phases.

Jan 1, 2011

By Leslie F. Ruppert

The US Geological Survey (USGS) is currently conducting a coal resource assessment of the coalbeds and zones that are projected to provide the bulk of the nation’s resources for the next few decades. The Pittsburgh and Upper Freeport coals are the first two beds in the northern and central Appalachian basin region to undergo fully digital coal assessments. The bed-specific assessments are being carried out in partnership with the state geologic surveys of West Virginia, Ohio, Pennsylvania and Maryland. Comprehensive stratigraphic and geochemical databases have been developed for both of the beds. The extent of the bed with mined areas, structure contour, isopach, and overburden thickness maps for the Pittsburgh coal bed have been released as USGS open-file reports.

Jan 1, 1999

By R. C. Burton

One of the major problems encountered with recirculatory breathing apparatus presently used by mine rescue teams is that the inspired air becomes uncomfortably, and often dangerously, hot. This is also true with self-rescuers. It is well known that man can tolerate very high dry-bulb temperatures if the wet-bulb temperature is low, but not vice- versa. The maximum tolerable, wet-bulb temperature is about 42 °C (108 °F). A continuously inhaled wet-bulb temperature above this value can cause irreversible damage to the throat and lung tissue, and wet-bulb temperatures close to it cause extreme discomfort (1) and seriously retard the capability of the man to perform useful work. A theoretical analysis, combined with experimental results, has shown that it is the carbon dioxide absorbent that is the major cause of high wet-bulb temperatures of the inspired air in the Siebe Gorman Proto 4, and in the Draeger BG 174 apparatus, both of which are used by rescue teams on South African mines (2). In the Proto 4 apparatus, the absorbent for the carbon dioxide is soda lime (calcium hydroxide). The German Draeger BG 174 also uses this absorbent but under arduous conditions such as in hot environments (50 °C, 122 °F), the use of an alkali absorbent cartridge is recommended which consists mainly of caustic soda (sodium hydroxide). Lithium hydroxide is used in some apparatus in the United States. It is clear that different absorbents will produce different quantities of heat and moisture for a given rate of absorption of carbon dioxide. The proportion of this heat and moisture which is transferred to the user depends upon how much can be removed from the recirculating air between the absorbent and the mouthpiece. This paper discusses the present methods of heat removal and describes the design and test results of a prototype evaporative cooler.

Jan 1, 1980

By D. H. Horswill

The Red Dog Mine is the world’s largest zinc mine. It is located 145 km (90 miles) north of the Arctic Circle in northwest Alaska on lands owned by the Inupiat Eskimo organization called the Northwest Alaskan Native Association (NANA) Development Corp. NANA acquired surface and subsurface title to this resource as part of its settlement lands under the Alaska Native Claims Settlement Act. In 1982, NANA entered into a lease agreement with Cominco. Cominco is an international mining company focused on zinc. It built and operates the Red Dog Mine. NANA’s principle objective in the development of the mine was to have it contribute to the development of sustainable communities within their traditional region. This meant creating job opportunities in a modern economy while preserving the traditional subsistence lifestyles. Preservation of their culture, language and traditions are as important to the NANA people today as they were in the past.

Jan 1, 2000

By J. D. Miller, C. L. Lin

Appropriate software and hardware necessary to adapt a x-ray CT analyzer for determination of coal washability has recently been developed and sucessfully tested for well characterized samples under laboratory conditions. Evaluation of the CT-based analyzer under simulated on-line conditions is also presented to verify the on-line capabilities of the newly developed x-ray CT analyzer for the control of coarse coal cleaning circuits. The investigation shows that the data obtained from CT washability analyses compare favorably with experimental sink-float data. Further, image frequency was considered to evaluate the CT-Based coal washability analyzer for simulated on-line conditions. Specifically the number of observations (image spacing) needed for accurate sampling and the total time required to perform the calculations for a representative data set were determined.

Jan 1, 2001

By D. Parks, A. Miller, M. McNinch, R. Jacksha

Each year, hundreds of mine workers are involved in machinery-related accidents. Many of these accidents involve inadequate or improper use of lockout/tagout (LOTO) procedures. To mitigate the occurrence of these accidents, new safety methods are needed to monitor access to hazardous areas around operating machinery, improve documentation/monitoring of maintenance that requires shutdown of the machinery, and prevent unexpected startup or movement during machine maintenance activities. The National Institute for Occupational Safety and Health (NIOSH) is currently researching the application of Internet of Things (IoT) technologies to provide intelligent machine monitoring as part of a comprehensive LOTO program. This paper introduces NIOSH’s two phase implementation of an IoT-based intelligent machine monitoring system. Phase one is the installation of a proof-of-concept system at a concrete batch plant, while phase two involves scaling up the system to include additional sensors, more detailed safety/performance metrics, proximity detection, and predictive failure analysis.

By Jamal Rostami, Ataollah Rahbar

"Uma Oya Multipurpose Development Project is under construction in Sri Lanka. This project involves 2 Rolled Concrete Core (RCC) Dams connected through a tunnel currently under construction by Drill and Blast method. The water is transferred from first diversion dam to the 2nd regulatory dam and from which, it will be transferred through a 14 km headrace tunnel to the top of a 650 m deep drop shaft that feeds the high pressure water to an underground powerhouse and turbine chamber for generation of 120 MW of electricity. The Headrace and Tailrace tunnels are being excavated by two 4.4 m diameter double shield TBMs. The headrace tunnel has already passed 5km milestone and is mined in hard rock, while the tailrace tunnel has been completed in rather weak and fractured ground. This paper will review the history of the project along with the geology of the site. The operation of TBM in headrace tunnel will be discussed in more detail, focusing on the challenges of excavating through very strong and abrasive quartzite and gneiss on this site, as well as reaches of tunnel in high inflow of water reaching 400 L/Sec. INTRODUCTION This paper aims to introduce the Uma Oya Multipurpose Development Project (UOMDP) as a hydro mechanical project in Sri Lanka, targeted generating hydro-electric power, transferring water for irrigation purposes and controlling seasonal devastating flood. This project lies in the south-eastern part of the central highland region of Sri Lanka (Figure 1). The main part of the project is located in the south-western part of the Badulla district in the province of Uva. The south-eastern end of the project site is in the central west of the Moneragala district (province of Uva). Bandarawela is the largest urban setting within the project area, located halfway between the upstream and the downstream ends of the planned hydropower plant and combination of dams, tunnels, and downstream facilities. The Multi-Purpose Project Of Uma Oya is planned to convey water from Uma Oya to Kirindi Oya Basin for hydroelectric energy generation includes Puhulpola RCC Dam on the Uma Oya river, Dyraaba RCC Dam on the Mahatotilla Oya river, a conveyance tunnel from Uma Oya to Mahatotilla Oya (L=3750m), a long feeder tunnel from Mahatotilla Oya to Kirindi Oya. The feeder (power) tunnel Lot consists of a headrace tunnel (L=15554m), the surge shaft (L=200m) and tank on the upstream of the vertical shaft, a vertical shaft with steel lining (L=650m), an underground powerhouse and a tailrace tunnel (L=3650m)."

Jan 1, 2016

By W. J. Mahoney

A good quality assurance program at a coal mine or power plant is accurate, timely and consistent. The quality analysis is accurate due to a complete sampling of the coal stream loaded into the unit train. The sample analysis is accurate because standardized testing procedures are applied. Once an analysis is completed, the results must be communicated to the electric utility in a timely manner. The electric utility needs the results to better manage the coal inventory at its power plants. A quality assurance program can also help a mine deliver a consistent product to a utility&apos;s power plants. The importance of accuracy, timeliness and consistency are based on major changes that are taking place in the electric utility industry.

Jan 1, 1994

In February 2001, Kalgoorlie Consolidated Gold Mines (KCGM) commissioned its first full-scale ultra fine grinding (UFG) plant to supplement existing roaster concentrate treatment capacity. This process involves the fine grinding of refractory pyritic concentrate to 10µm, followed by direct cyanide leaching for the recovery of gold. By this means gold is economically extracted from the concentrate without the need to first oxidise the host pyrite. This paper details the history of the project from initial laboratory testwork comparing possible treatment options, to current performance of the 12 tph plant. This includes the cost comparison of the major treatment options, the laboratory and pilot scale UFG performance, the UFG mill selection, cyanide leaching of UFG product, commissioning and plant performance to date.

Jan 1, 2002

By Marco D. Boscardin, Paul A. Roy, Kevin J. DiRocco, Andy J. Miller

The North Shore Connector Project for the Port Authority of Allegheny County involves TBM mining a pair of subway tunnels through soil and rock under the Allegheny River and a narrow city street. Along the tunnel alignment are a historic building on shallow foundations and modern buildings on deep foundations, one constructed directly over the alignment during the latter phases of design. This paper provides an overview of the general site conditions, and technical basis for excavation support and tunneling decisions. Deformation limits, ground improvement, monitoring and mitigation plans, geotechnical baseline report development, and risk management will also be discussed.

Jan 1, 2007