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By Robert J. Timko, Charles D. Taylor, Edward D. Thimons, Tom Mal

A test system was developed for measuring airflow in the National Institute for Occupational Safety and Health (NIOSH) ventilation gallery using a three-axis ultrasonic anemometer. The gallery was used to simulate face airflow conditions in underground mines having a blowing curtain. Airflow data collected at multiple sampling locations between the face and the end of the curtain were used to draw airflow profiles for different curtain setback distances, intake flow quantities and entry widths. In addition, methane was released at the face, measured at the sampling locations, and displayed as methane distribution in the area between the curtain and the face. Entry geometry had a significant effect on airflow patterns, and the flow patterns affected the distribution of methane in the entry. Flow measured at and parallel to the face was a good predictor of methane dilution and removal within two feet of the face.

By P Gunn, M Watts

The general goal of passive acid mine drainage (AMD) treatment is to reduce levels of acidity and metals to acceptable levels. Most treatment systems use either an oxidising or a reducing strategy. In oxidising systems, alkalinity is added along with dissolved oxygen; in reducing systems, dissolved oxygen is removed (if present) and then alkalinity is added. It is recommended that small-scale field trials be conducted as part of the methodology of selecting the best remediation strategy at AMD sites. Following successful field trials at the Sullivan Mine AMD, the Pike River Coal Company (PRCC) has shown foresight by using the same system to treat AMD generated as a result of taking a bulk sample of coal at the Pike River coal field. The system reduced acidity by 100 per cent, iron by 99 per cent, aluminium by 96 per cent, nickel by 95 per cent, manganese by 51 per cent and zinc by 99 per cent. The success of this field trial suggests that a system using a reducing strategy may be appropriate for the Pike River Adit AMD site.

Jan 1, 2005

Jan 1, 1994

By Stephen R. Grano, Jon Glatthaar, Philippe Steinier, Christopher J. Greet

"The importance of the oxygen content of sulphide mineral pulps in determining which reactions occur, and their subsequent influence on flotation behaviour is grossly underestimated in most operating concentrators. While pH is routinely monitored, Eh and dissolved oxygen measurements are obtained infrequently. However, dissolved oxygen measurements in conjunction with other pulp chemical parameters (i.e. pH, Eh, and EDTA extractable metal ion analysis), can provide valuable insight into where and what type of reactions are occurring within a circuit. Unfortunately, these readings yield “instantaneous” measurements of the pulp chemical parameters.What is needed is a means of establishing how reactive a pulp is, and how this reactivity changes as components of the system are manipulated. Oxygen demand provides an opportunity to do this. Several attempts at measuring the oxygen demand of a pulp have been made in the past with varying degrees of success. Most notable among these are Noranda and BOC Gases.Learning from these experiences, Magotteaux have developed the MagO2 ® demand vessel to measure the oxygen demand of mineral pulps. This paper described the apparatus, and through a case study on Broken Hill lead/zinc ore demonstrates how the MagO2 ® demand vessel is used.INTRODUCTIONThe role of oxygen in flotation is complex. While a considerable body of work exists demonstrating the strong involvement of oxygen in the interactions between sulphide minerals and collector (Gaudin and Finkelstein, 1965; Gaudin, 1974; Woods, 1984; Laajalehto, Nowak and Suoninen, 1993), the presence of oxygen can also affect the oxidation state of sulphide and non-sulphide minerals, which can impact on their flotation behaviour. Further, sulphide mineral oxidation is related to their oxygen demand (Spira and Rosenblum, 1994)."

Jan 1, 2004

By Richard J. Mainiero, James H. Rowland

When most people think of explosives transport they think of a hazardous operation. We all know that we aren’t allowed to transport explosives through tunnels and are discouraged from traveling through heavily populated areas. Popular opinion suggests that explosives transport is a very risky operation. The authors decided to look into this a little more thoroughly and found just the opposite to be true. While there have been some disastrous world-wide accidents involving the transport of industrial explosives, this is not the case in the U.S. Over the past 10 years, accidents related to the transport of explosives used in mining and construction have resulted in 5 major injuries, 11 minor injuries, and no fatalities. Explosives and ammonium nitrate (AN) transport outside the U.S. has not had such a good record; there have been 4 major explosives or AN transport accidents resulting in a total of more than 300 deaths. Most of these fatalities could have been prevented if the accident site had been evacuated once the explosive or AN cargo began burning. The safe history of explosives and AN transport in the U.S. is due to diligent efforts by government, labor, and industry. However, accidents will become more common and disastrous if we become complacent.

By Rayleen Riske

Why do we look for better reconciliation when times get tough? Why wait? Mine reconciliation should be a priority throughout the good times too. In fact, with good reconciliation, those good times are going to be even better and will help pave the way to success through those preventable bad times. Reconciliation throughout the entire mining value chain requires the capture, validation, and analysis of copious amounts of data. This task can be daunting for a team in a small mine, let alone reconciling across a suite of large mines. This paper will outline the different ways we can reconcile across the value chain, why we should reconcile over differing periods of time and how Snowden?s solution to proving reconciliation can be a simpler, reliable and transparent process. Snowden?s Reconcilor is proving to be a valuable tool on any mining scale, by capturing, validating, sorting and reporting data for timely decision making by the site geologist through to corporate management. By instigating vigorous reconciliation, you are setting your mine up for the future. Not only will you have the means to analyse your current processes and measures, but you will have the opportunity to identify and improve your mine?s performance from the resource model through to the final product.

May 1, 2010

By Mark A. Williams

Topography and geology greatly impact the decision of how to plan and operate a surface mine. To extract coal, five primary surface mrning methods are practiced in the United States. These include contour strip. mountamtop removal, area, modified area, and open pit mining methods. The first four approaches are commonly associated with coal mining while open pit techniques, although used in the mining of coal, are more commonly applied to the mining of hard rock, metals, and aggregates. Various sub-routines of the primary surface mining methods are likewrse applied rn the industry.

Jan 1, 1991

By A R. Penney

Since mining-induced seismicity first became apparent at the Beaconsfield Gold Mine in 2002, there has been an ongoing program of geotechnical investigations to understand the phenomenon and allow for the development of strategies to manage the risks it posed to personnel, the business and the community at large. Studies resulting from a seismically induced rockfall on Anzac Day 2006 have been extensive, and have advanced the understanding and management of seismicity at the mine. Enhancement of the mineÆs seismic array, implementation of extensive monitoring of ground behaviour, improved ground support and reinforcement design, and ongoing numerical modelling provide a technical framework for the management of seismicity. In addition, extensive involvement of the workforce in risk assessment and the development of standard work procedures (SWPs), has contributed to a æbest practiceÆ approach to manage seismic hazards at the mine.

Jan 1, 2008

The passage of chloroform vapour in a carrier of oxygen through two nickel sulphide ores heated to 380°C converted the nickel to the water soluble chloride form. In one ore the nickel (2·75 per cent) was presentas violarite ((Ni, Fe)3S4) whereas in the second it was present as pentlandite, ((Fe, Ni)9S8) (4·9 per cent Ni).A similar technique was utilized to convert nickel in nickeliferous laterites (1·6 per cent Ni) into a soluble chloride using town gas instead of oxygen as a carrier.With both techniques greater than 90 per cent extraction was achieved.

Jan 1, 1972

By William R. Yernberg

The Fifth International Heavy Minerals Conference (HMC) was held Oct. 16-19, 2005, at the Marriott Sawgrass Resort in Ponte Vedra, FL. With SME as sponsor, the 2005 conference marked the first time that the HMC was held in North America. The conference is held every two years and provides an important forum for professionals in the heavy minerals and related industries to meet and discuss issues related to heavy mineral exploration, mining, processing and marketing. Previous locations included Australia and South Africa. The conference consisted of technical presentations, field trips to heavy mineral operations, a trade show and social activities. It was appropriate that Ponte Vedra was selected as the location for the conference. Ponte Vedra, located on the Atlantic Coast 17 km (10 miles) southeast of Jacksonville, FL, is the birthplace of heavy minerals mining in North America. Ponte Vedra beaches were mined from 1916 to 1929 in what was then called Mineral City. Though Ponte Vedra is now a golf and beach resort, there are still four heavy mineral mines operating within an hour’s drive. Today the Ponte Vedra Country Club and Golf Course is situated in the center of the former mining site.

Jan 1, 2006

By R. R. Oder, R. E. Jamison, E. D. Brandner

This paper presents preliminary test results obtained with a 0.38 kg/s (3000 lb-hr) beta prototype MagMill™. In processing Upper Freeport coal the beta prototype recovered 82% of the weight of the feed and 91% of the heat content while reducing the potential emissions of sulfur, kgSO2/GJ(lbSO2/MBtu), by 61%. Pyritic sulfur in the MagMill™ product was reduced by 78% compared to that in the feed. For all runs, the mill product was controlled between 70 to 80% finer than 74 µ particle size. Recoveries of mercury, arsenic, and selenium ranged from 35 to 45% of that in the feed. Power draw was reduced by 26% and mill throughput was increased by 9% compared to the pulverizer operating with no magnetic separator attached.

Jan 1, 2000

By G Eastwood, C Joyce, P Ryan, G M. Johnston

Over the years, predictive techniques for Acid Mine Drainage (AMD) and the natural processes affecting acid generation have received considerable attention. Less emphasis has been placed on the sampling strategy and the integration of testwork results with the geological data base. The sampling strategy employed and the development of a geological model to determine the spatial distribution and volume of acid producing material are often crucial for developing cost-effective containment and mitigation measures. The geological model provides a link between the occurrence, timing, destination and placement of mined waste rock. Careful and accurate interrogation of a comprehensive geological database provides this linkage. The AMD testwork program at Cadia in NSW has been designed to identify the temporal selective handling requirements that will be required during operation. Sampling involved collection of representative combinations of all waste rock types identified within an extensive geological database. These samples were subjected to static, kinetic and accelerated weathering predictive tests. Preliminary results have been used to construct a waste block model for the deposit that identifies the quantity and distribution of acid producing material. Integration of the block model with the mine scheduling determines when the material will be mined.

Jan 1, 1996

By L. A. Roe

Magnetic separation of iron ores is one of the fastest-growing segments of the minerals beneficiation industry. The tonnage of taconite ores processed annually by magnetic separation will, in a few years, reach 100 million. Magnetic separation occupies an attractive position in the field of ore beneficiation. It is a simple yet effective method, used for some 150 years and steadily growing more important. This type of beneficiation orginated in 1792, when William Ful-larton was issued a British patent covering the separation of iron ore by magnetic attraction. What is magnetism, and why are some materials capable of being magnetized and others not The study involves many unknowns, and even a partial answer to these questions would be a dissertation in solid state physics and perhaps other fields of science. But the last two decades have revealed basic facts as to why certain materials are magnetic and what happens to them when they are magnetized. Some of the newer studies in solid state physics have developed a theory that can be applied to studies of magnetism. It is claimed that magnetism stems fundamentally from the spin of electrons in atoms that tend to go in pairs, spinning in opposite directions. The atom as a whole can act as a magnet only when there is an imbalance of electronic spin. Whenever an atom has an odd number of electrons, therefore, this imbalance exists. This neutralizing effect explains why a piece of material that contains atomic magnets is not necessarily magnetic. The physicists tell us that iron is composed of many small magnetized regions called domains, which consist individually of millions of atoms. The piece of iron becomes magnetized when an external force lines up these domains in the same direction. Fundamental data developed by physicists working in fields far removed from minerals beneficiation are now available for developing better magnetic separators for ore processing. More Data Needed on Magnetic Properties of Minerals: There is less information on magnetic properties of minerals than there is for certain aspects of magnetic separator design. When the data on magnetic properties is available, it is often directed toward the study of powders for tape recorders and other highly scientific endeavors that are of little use to the beneficiation engineer. W. R. Crane's table of tractive forces, published in 1902, is still a guide in the study of magnetic minerals. Bits of other information regarding electrostatic conductivity, dielectric constant values, and permeability of various minerals have also appeared but are of small practical value in magnetic separation of ore. It is extremely important to obtain pure mineral specimens for making investigations and to record results that may be of use in studies of magnetic processes. Reference to the large volume of data developed by those concerned with analysis and design of permanent magnets soon reveals that these people have extensively evaluated the effect of various impurities on magnetic properties. Much of the science of the ferrite industry is based upon spinel-type structures which are varied by substitution of selected elements or even subtraction of elements, leaving vacant sites in the space lattice. Magnetic separators are used to beneficiate a wide variety of industrial minerals. In this application the relatively large volumes of nonmagnetics are usually the commercial products. The amount of mag-

Jan 1, 1959

By Edwin Berry

THE consideration of the present value of a mine is of great importance when planning for the operation of a property,, and it is particularly so in the case of mines that have large ore reserves. At various times during the past 15 years, the writer has had occasion to make rather thorough studies of the subject, and has been greatly impressed by certain important points which these studies have brought out, points which, though they may be well known, are often lost track of in the rush to obtain low mining costs and high daily tonnage output. . It is the object of this paper to present briefly, and in a general way, some of these points, and especially those which have to do with the relationship which (1) ore reserves and plant capacity, (2) grade of ore mined, and (3) ore losses in mining, bear to the present value. Present value, sometimes called present worth or actuarial value, means the value today of the future earnings of an enterprise. Great industrial, manu-facturing or railroad enterprises, if properly handled, go on indefinitely and their value is directly dependent on their estimated annual earnings. Mines, or oil properties, on the other hand, have an earning capacity only until the ore or oil is exhausted, and their present value is dependent not only on their annual earnings but also on their life, which is the length of the period over which they can produce at a profit. A mine, or an oil property, is a "wasting asset," while an estab-lished manufacturing business is not, or should not be. In other words, the present value of a mining property. represents a sum of money on which there could be paid from operating profits a determined rate of interest, say 8 per cent., and in addition an amount which, if invested at compound interest as received, would at the end of the life of the mine pay back the present value. In his "Wealth and Income of the American People," Walter Renton Ingalls says: "The fundamental principle of mine valuation is the present worth of an annual dividend accruing during the period of years corresponding to the life of the mine."

Jan 7, 1922

By Dale S. Preece

"The computer program DMC (Distinct Motion Code) [Taylor and Preece, 1989a] was developed in 1988 and 1989 to predict the motion of rock following a conventional blast. DMC executes very efficiently on a CRAY type computer due to the high degree of vectorization and also due to the use of spherical elements [TayIor and Preece, 1989b]. Bulking mechanisms developed specifically for use with spherical elements include rotation-induced dilatation and aspect ratio > 1.0 [Preece and Taylor, 19901. Rotation-induced dilatation allows the radius of the sphere to expand as a function ofsphere rotation to simulate the interaction of corners and sides of blocky rocks. An aspect ratio > 1.0 is achieved by kinematically tieing spheres together."

Jan 1, 1991

By D. Malovichko

Seismic events and pillar failures observed in two platinum mines in the Rustenburg area, South Africa, were investigated. We studied the sources of approximately 300 largest seismic events recorded in 2009. Moment tensors of these events were estimated from amplitudes and polarities of P- and S-waves. The inverted mechanisms contain isotropic implosive components in many instances. Analyses of uncertainty of the moment tensor solutions confirmed the significance of the implosive component in general. Several documented cases of pillar failure were considered in detail. For each of these a seismic moment tensor was calculated from an elastic stress model assuming an instant removal of a failed pillar. The geometries and magnitudes of the theoretical seismic moment tensors are in agreement with the observed (i.e. inverted from seismic data). The results indicate that either pillar failure or fracturing in the proximity of the reef (within a fraction of the dominant wavelength of seismic waves) are responsible for a significant portion of the large events recorded in these mines.

Jan 1, 2012

By Tim Ross

Several shear failures were observed in Shaft #1 at the Mountain Coal Company, LLC, West Elk Mine, after mining longwall Panel 23, 1,100 ft to the east of Shaft #1. It was speculated that this shear damage could be related to differential ground movement caused by in situ stress relief from the ?stress shadow? of the caved zone above longwall Panel 23. A numerical study was conducted to assess the possibility of the shaft shear damage being caused by in situ stress relief and the potential for additional damage to Shaft #1 and two other nearby shafts, due to mining nearby longwall Panel 24. Three-dimensional (3D) models were built in FLAC3D to simulate past and future mining near shafts, the estimated local anisotropic and directional horizontal stresses, and the overlying variable surface topography. The numerical analyses indicated that stress relief due to mining Panel 23 caused the shear damage to Shaft #1and that additional damage to Shaft #1 and the other two shafts, would likely result from mining longwall Panel 24. Additional shear damage was documented in Shaft #1 when longwall Panel 24 was mined, confirming the results of the numerical analyses.

Jan 1, 2006

By B Murphy, A Uliana, P STrgio de Oliveira, G Ara·jo de Souza Franco, T Miettinen

Outotec has performed numerous research and development projects and various surveys in the study of reverse iron ore flotation. Over the past four years their TankCell-70 and TankCell-160 flotation cells at the Germano concentrator of Samarco in Brazil were extensively surveyed. These surveys have revealed some extreme operating conditions in reverse iron ore flotation and are the subject of this paper. Some of the findings include large variations in the content of solids in the various flotation stages. At the bottom of the cleaner cells, the content of solids by weight reached over 60 per cent, whereas at the bottom of the scavenger cell this was less than 50 per cent. Froth carry rates were also significantly different in the various flotation stages. In the case of coarse material, the scavenger cells operated at a froth carry rate of over 40 t/h.m2. With fine material, however, froth carry rates of less than 10 t/h.m2 were measured. High froth carry rates caused significant changes in the residence times at Samarco. In the rougher cells, the fifth cell had more than double the residence time of the first cell. This was even more pronounced with the scavenger cells, where the second cell had more than triple the residence time of the first cell. High froth carry rates also caused losses in iron recovery. As a consequence of such findings, it appears that different rules apply in the sizing of reverse flotation circuits compared to direct flotation circuits. Different operating parameters (mixing intensities and air flow rates) must also be used in the rougher, cleaner and scavenger cells in order to optimise the metallurgical performance. Outotec has also been working on a number of new technologies aimed at improving the metallurgical performance of iron ore reverse flotation circuits by increasing froth carry rate and decreasing fine iron entrainment.CITATION:Miettinen, T, Uliana, A, Ara·jo de Souza Franco, G, STrgio de Oliveira, P and Murphy, B, 2013. TankCell flotation at SamarcoÆs Germano concentrators, in Proceedings Iron Ore 2013 , pp 441-444 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Jeffrey K. Whyatt

The Crandall Canyon accident investigation included an interesting and unexplained observation by rescuers that the ?barrier rib had shifted northward as a unit, as much as 10 feet.? This is not the first mention of such a movement, although such reports are rare. Historical accounts describe unusual movement and displacement of intact coal, cribs and timbers. Two movements of particular interest are the creation of gaps above coal pillars and falling of standing support elements without apparent damage. A dynamic boundary element program was used to explore movements induced by slip on geologic features removed from the affected panel. While the resulting models are much too simple to fully replicate these observations, they do show that the types of phenomena observed are possible. They can also provide insight into the types of motions that ground support elements are subjected to during large bump events. This was demonstrated for the case of a large bump in a Book Cliffs coal mine. Seismic information suggested the source mechanism to be normal slip on a fault. A model of that source showed initial dilation of the panel followed by dynamic compression and rebound ? consistent with underground observations. The initial dilation is important as it may allow slender standing support to shift or fall.

Jan 1, 2009

By F. Qi, T. Frišcic, C. Mottillo

"One of the principal goals of modern industry is to minimize the environmental impact and increase the materials- and energy-efficiency of transforming raw materials into valuable products. This paper will highlight our latest laboratory-scale research in low-energy, low-solvent reactivity of metal oxides and their conversion into popular metal-organic frameworks (MOFs), zeolitic imidazolate frameworks (e.g. Basolite® Z1200 component ZIF-8), and metallodrugs (e.g. bismuth subsalicylate, active component of Pepto-Bismol®). Mechanochemical ion- and liquid-assisted grinding (ILAG) and ""accelerated aging"" techniques will be presented, along with novel low-energy and solvent-free approaches, inspired by geological weathering processes, for converting metal oxides into metal-organic materials. INTRODUCTIONThe development of environmentally-friendly processes, which would in the same time be more materials- and energy-efficient than the existing ones, is one of the central concerns of modern chemical research. In that sense, the focus of the chemist has been mainly on the preparation of carbon-based organic molecules and adaptation of traditional organic synthesis to the recently delineated ideals of Green Chemistry. However, there is a growing realization within the chemistry community that significant energy, materials, and ecology-related benefits can be achieved and, indeed, targeted in the transformations of materials that are typically associated with inorganic chemistry and minerals processing. The principal aim of this highlight contribution is to illustrate how, through the use of approaches associated with solventfree chemistry and mechanochemistry (James et al., 2012), one can develop a clean and efficient system of chemical and materials transformations involving oxide precursors that normally belong to the realm of inorganic chemistry and mineral processing. In particular, this contribution will provide an overview of the recently developed mechanochemical and solvent-free reactivity of metal oxides towards small organic molecules. These mechanochemical reactions, including the methods of liquid-assisted grinding (LAG, Frišcic & Jones, 2009) and ion- and liquid-assisted grinding (ILAG, Frišcic, 2010), have so far provided a radically different means to construct advanced metal-organic materials (e.g. porous metal-organic frameworks, [MOFs] or metallodrugs) by rehabilitating metal oxides as precursors, eliminating the use of bulk organic solvents, and avoiding the use of high temperatures."

Jan 1, 2012