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Rock mass classification is widely used throughout the underground mining industry—in both coal and hard-rock mines. It is used in all stages of the mining process, from site characterization to production operations. The goal of the International Workshop on Rock Mass Classification in Underground Mining was to provide a forum for leading practitioners of rock mass classification to come together and share their methods and experiences with the technique. The workshop was held in Vancouver, British Columbia, Canada, on May 31, 2007. It was co-chaired by Christopher Mark, Ph.D., P.E., National Institute for Occupational Safety and Health, Pittsburgh, PA, and Rimas Pakalnis, P.Eng., University of British Columbia, Vancouver, Canada. The proceedings of the workshop contain 16 invited papers from 9 countries, reflecting the international depth and breadth of current practice. Applications in both hard-rock and coal mining are well represented. Some of the topics that were addressed at the workshop include: • Major rock mass classification systems used in mining and their variants • Collection of input data through observation, rock testing, and geophysics • Design of mine layouts and rock support systems using classification • Estimation of rock mass strength and other input parameters for numerical models from classification • Applications in weak rock, raise boring, cavability assessment, and other special topics • Risk assessment using rock mass classification

Jan 5, 2007

By Mohammed Sakr

The use of helical piles as a deep foundation option has considerably increased in the recent years to support a variety of loads, from small loads for several applications such as residential housing, solar farms, utilities and retrofit projects, to large loads for many applications such as commercial, power transmission lines, oil facilities and industrial applications. Therefore, it is necessary to qualify and quantify their axial capacities and performance characteristics. This paper presents the first full-scale axial compression and tension (uplift) testing program executed on large capacity helical piles installed in cohesionless soils. A total of eleven pile load tests using either single or double-helix piles with shaft diameters that varied between 324 mm to 508 mm (12¾ in to 20 in) were carried out, including seven axial compression tests and four tension (uplift) tests. The results of the axial compressive and tensile pile load tests as well as field monitoring data of helical piles installed in dense sand are presented in this paper. Based on the results of this study it was found that helical piles have developed significant resistance to axial compressive loads up to about 2920 kN (656 kips) and tensile loads up to 2900 kN (652 kips).

Jan 1, 2011

By Steven J. Page, Wm. Randolph “Randy” Reed, John A. Organiscak

Researchers studying dust generation from blasthole drills developed a simple, quick fix that reduced respirable dust concentrations by more than 63% at the dump point. This device, which requires almost no maintenance, is small and inexpensive, and it will help operators maintain compliance to the dust standard. The thought process was that a reduction of respirable dust at any of the multiple sources on the drill, in this case the dust collector dump point, should reduce the total respirable dust generated by the drill. The U.S. Mine Safety & Health Administration (MSHA) has a coal respirable dust standard of 2 milligrams per cubic meter (mg/m3) for an 8-hour shift. MSHA and mine operators periodically collect personal dust samples to determine compliance with this dust standard. Drill operators have one of the highest exposure levels to respirable dust. This has been proven through many reviews of the MSHA dust sampling database. Prior to 1987, the highwall driller at surface coal mines had the most severe exposure to respirable silica dust, a trend that continues today based on MSHA's respirable dust sampling database. A review of the MSHA database for the years 1985 through 1992 shows that 81% of the respirable silica dust samples taken exceeded the permissible exposure limit for the highwall drill operator at surface coal mines. A more recent review of the MSHA database, for the years 1996 through 2000, shows that only 31% of the respirable silica dust samples taken exceeded the respirable silica dust limit for the highwall driller at surface coal mines. This suggests a substantial improvement in preventing the exposure of silica dust to the highwall drill operator. The drill operator, however, still tops the list of job occupations that have the highest exposure to respirable silica dust Respirable dust has been shown to be harmful to human health, especially when silica is present in the dust. It causes a disease known as silicosis, which can occur in three levels: chronic silicosis, which occurs after 10 years of exposure; accelerated silicosis, which occurs between 5 and 10 years of exposure; and acute silicosis, which can occur within a few weeks to five years of very high exposure to silica dust. Respirable dust consists of the dust particle size fraction whose median diameter is 4 micrometers (µm). The drilling machine generates high concentrations of respirable dust from several sources: drill table shroud leakage, dust leakage through the table bushing, dust discharge from the dust collector exhaust due to impaired filters, and dust entrained from the dust collector fines dumped onto the bench. The National Institute for Occupational Safety and Health's (NIOSH) Pittsburgh Research Lab (PRL) has been studying different methods to reduce respirable dust from these sources. During its testing, the institute identified a simple solution that reduces the amount of respirable dust generated at the collector dump point.

By F. Calizaya

This paper describes the basic requirements for the utilization of belt air to ventilate working sections at remote locations in relation to the main fans. It highlights the risks involved, potential problems, and the provisions that must be followed by mine operators for the safe use of belt air. The paper also presents a brief review of the current regulations, conveyor belting tests, atmospheric monitoring system requirements, and the experience gained by mine operators to utilize the belt entries to ventilate remote working sections or areas where mechanized equipment is being installed or removed. The paper concludes with a set of recommendations with respect to the utilization of belt air and the composition of belt material in under-ground coal mines.

Jan 1, 2008

By J. H. Rowland

The Mine Improvement and New Emergency Response Act of 2006 (MINER Act) amended the Federal Mine Safety and Health Act of 1977 to improve the safety of mines. The MINER Act established a Technical Study Panel (the Panel) to provide independent scientific and engineering review and recommendations with respect to the utilization of belt air and the composition and fire retardant materials in underground coal mining (1). Because frictional heating is a common cause of belt fires, the Panel recommended that the Mine Safety and Health Administration (MSHA) evaluate the drum friction test to determine if such a test would contribute to conveyor belt safety beyond that provided by the Belt Evaluation Laboratory Test (BELT). This paper compares the results of the drum friction test to results from the BELT and large-scale tests for six different conveyor belts. The results are used to evaluate the drum friction test as a method to determine the fire resistance of conveyor belts.

Jan 1, 2011

Vitrinite reflectance forms the basis of a study of coal rank variation in two areas of the Upper Hunter Valley, New South Wales, on the northern margin of the Sydney Basin. A selective analysis procedure, based on samples rom twenty-two boreholes, has resulted in a small range of reflectance values for each sample and consequently a high degree of significance for calculated mean values. The patterns of rank distribution derived from these data have facilitated an interpretation of the rclative timing of coalilication and deformation in each area.This study provides support for the suggestion by several authors that there were at least two periods of folding in the tJpper Hunter Valley. In the Hebden-Ravensworth area, minor folding took place after most of the coalilication was completed.To the west, in the region of the Muswellbrook Anticline, coalification occurred during or after the formation of this major structure. Tectonic instability during deposition of the Singleton Super-Group, in the region of the Hunter-Thrust on the basin margin, is evidenced by rank variation suggesting differential subsidence across this zone.

Jan 1, 1980

By B. Mishra, A. Staley, D. Kirkpatrick

The major waste product of the alkaline extraction of alumina from bauxite [Bayer Process] is known as red-mud. Approximately, a ton of red-mud is produced for every two tons of bauxite mined. The red-mud produced from Jamaican bauxite is rich in hematite, alumina and titanium oxide. It has been shown that over 90-wt. pct. alumina can be recovered from red-mud by soda-ash sintering and caustic leaching. Hematite can be carbothermically reduced with a degree of metallization of over 94 pct resulting in attempts for magnetic separation. These separations are desirable in the notion that there is no waste product generated from this type of processing and consequently an opportunity for complete utilization of the waste material. Conversely, the pre-separated material could be charged through the tuyeres in an iron blast furnace or smelted to produce pig iron. If smelted, the concentration of titanium oxide in the slag will be significantly high justifying its recovery by established acid-leach process. This paper describes the results of alumina recovery and the plans for titanium oxide recovery from red-mud. In addition, the situation of ongoing efforts in iron extraction, particularly, the method of magnetic separation of the reduced material. The problems associated with the use of reduced red-mud as an alternative to direct-reduced iron [DRI] has also been discussed. Critical assessment of the recovery sequence chosen for the products has been described based on economics.

Jan 1, 2001

To form a true picture of the early history of Queensland, we must think of white settlement advancing like an incoming tide, wave by wave; each wave lapping ahead a little further than the last. The credit for opening up the country belongs to a large number of pioneers, each of whom pushed out just a little further than his predecessors.Contrary to what one might expect, Rockhampton district was settled by overlanders from the south and not from the ocean side. When the Archers, the pioneers of the Rockhampton district, reached Gracemere in 1853, settlement had already made its way down the valley of the Dawson River; for it was from Leith Hay's station at Rannes (a few miles below Mount Morgan) that the Archers advanced northward into the unknown, to find the river that the explorer, Ludwig Leichhardt, had told them must enter the sea somewhere near the Tropic of Capricorn.The Archers travelled northward from Rannes up the valley of the Dee, coming out on the edge of the Razorback Range not very far from the point at which the Dawson Valley Highway drops over into Poison Creek. (Their diary records the bearings from a lookout point to various peaks around Rockhampton, and to-day, by plotting back from these peaks, we can determine the exact spot at which they descended on to the Fitzroy Flats.) We can be certain, then, that they must have been the first white men to set eyes on Mount Morgan; though to them it would have seemed to be nothing more than an insignificant hill...

Jan 1, 1939

By Gualberto Salas Torrelly

El avance tecnológico en los sistemas de iniciación en voladura abarca desde el sistema convencional (Mecha de Seguridad y Fulminantes hasta el sistema de iniciación electrónica, donde a través de un control de vibraciones se controla la energía liberada en un disparo, optimizando la fragmentación y disminuyendo el daño a las paredes del pit. En ese sentido, el sistema de iniciación con detonadores electrónicos, fija con claridad los conceptos de precisión, flexibilidad y seguridad. Por ello, el presente trabajo señala el uso de detonadores electrónicos por la Sociedad Minera Cerro Verde con la finalidad de evaluar sus resultados en seguridad, precisión, fragmentación, vibraciones, y control de daño a las paredes de la mina. Los resultados fueron óptimos -en tanto mejoró la fragmentación, el proceso de carguío y se incrementó el flujo en chancado primario.

Sep 12, 2005

By Carl-John Grävare

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

Jan 1, 2000

Owing to the number of chemical processes now in use for the separation of metals from their ores, and the consequent employment of chemicals at the mine, it is sometimes necessary to be able to produce them on the spot. This particularlyapplies to sulphuric acid which may be required for the manufacture of chlorine and of sulphate of copper, or for the treatment of'sulphides and other purposes. It can be made from brimstone for rather less than £3 per ton, but when delivered to any distance from the works, the cost of packages and other charges would amount to more than the value of the acid.I hope therefore, that to any of the members of the Institute who may find it necessary to make sulphuric acid for their own requirements an outline of the process, and some details of the plant etc may be useful, and perhaps lead to their devising improvements, mechanical or otherwise. Though acid can be made from pyrites in Europe for about 15/- per ton, it is probable that for most metaIIurgical purposes the quantity required. and the uncertainty as to how long it would be needed, would make it advisable to spend as little as possible on plant, and so use brimstone, though more expensive, I have therefore given no details of pyrites burning, which is very fully treated by Prof, Lunge in his work on " Sulphuric Acid and Alkali."

By L. Connolly, F. R. De Luca

"Rubber liners at Denison Mines Limited are used in 10 1/2x 24' low discharg0 pebble mills. These were originally 10 1/2 x 13 Dominion overflow type ball mills. Experience here shows that the wear of rubber and ni-hard lifters is approximately the same in the feed end half of the mill, while the wear of rubber lifters is much greater in the discharge half. The wear of rubber plates is considerably less than white iron in the feed end half of the Mill and slightly more in the discharge end half of the Mill. Rubber components are lighter to handle but their installation is time consuming. This leads to the conclusion that a combination of ni-hard lifters a~~ rubber plates is the most economical compromise in Denison's case, for the Mill. Rubber discharge grates are superior to steel grates, while steel feed end liners are superior to rubber.The Use of Rubber Mill Liners at Denison Mines LimitedGrinding is done in two identic0al circuits each consist-ing of one 10 1/2 x 14' Dominion overflow rod mill, two Dorr Oliver quadraplex rake type classifiers, two 10 1/2 x 24' Dominion low discharge grate pebble mills and ancillary pumps and conveyors for pebbles. There is one centrally located distributor box that receives the discharge of the 4 pebble mills and splits it out to the classifiers."

Jan 1, 1974

By Pieter de Waal

The use of valuable minerals is a necessity to maintain a modern society. Not only the iron, aluminium, coal and oil that are used in large quantities, but also the uranium, copper, vanadium, tungsten, antimony and many others play an essential role in the bigger picture of our modern civilisation. Minerals occur in a form and in places determined by a long history starting at the dawn of creation. Over billions of years the elements have combined in wondrous combinations and structures. They have been broken up by massive explosions, movements in the earth's crust and erosion by wind and water. They have been restructured and recreated in even more configurations by the application of heat and pressure, leached by and exposed to new chemical compounds. The result is that most valuable minerals are found in impure form and mixed up with other, less useful waste material. 2. Mineral Beneficiation The processes used for the purification and enhancement of an ore, to satisfy the needs of downstream applications, are collectively referred to as mineral beneficiation. Mineral Beneficiation starts in the mine where only that portion of the ore, that can be economically processed, is selectively extracted. It may also include ore blending, to ensure a more consistent feed to the following stage of valuable mineral recovery. The next stage in mineral beneficiation is the liberation of the valuable minerals from the gangue. This is achieved by blasting, crushing, milling and grinding down to an adequately fine grain size to facilitate good separation. Separation can be achieved by a variety of different techniques. ?Screening coarse from fine particles is an easy method if the valuable mineral is dominant in a certain screen fraction. ?Magnetic separators can differentiate minerals on the basis of their difference in magnetic susceptibility. ? Electrostatic separators differentiate on the basis of electrical conductivity. ? The differences in density are exploited in spirals and jigs. ? Particular surface properties provide a separation technique in flotation. ?The selective sorption properties of a collector medium are another option.

Jan 1, 2007

By M. Ahrens, J. Gonser

Gearless mill drives are a well established solution for grinding applications in the minerals and mining industries. The paper describes the functionality and technical features of such drive systems as well as their advantages compared to other drive solutions. Due to the variable speed operation the grinding process can be optimized for ores with varying grinding properties. This leads to significant optimization potential for the plant design as well as for its operation. Furthermore, energy and cost savings due to optimized operation, high system efficiency and high system availability are shown.

Jan 1, 2007

During the construction of storage caverns, and during their lifetime if the use to which they are put so requires, it is necessary to provide adequate ventilation to ensure the safety and comfort of the underground workforce. An analysis of likely contaminants during construction has indicated that where a large facility is situated in a rock mass of even moderate temperature climatic conditions are likely to be the limiting factor during most of the mining operation and atmospheric pollution when blasting is undertaken. Possible options for improvement are increased air flow, cooling of intake air and reduction of the heat source by altering the number and type of haulage units employed in the cavern. Local solutions are an alternative approach where heat problems are confined to a few specific locations

Aug 1, 1994

By W. P. Erasmus

This paper will focus on the use of the ?wet-mix? steel fibre re-in forced shotcrete as a permanent lining in deep shafts, assessing gold bearing reef. It will cover all aspects relating to the choice of this material covering the geological conditions through to the final quality control. All procedures are in line with ISO 9001,as JCI projects who manage the project, are an approved company therof.

Jan 1, 2001

By L. Yuan, A. C. Smith

To provide insights for the optimization of ventilation systems for U.S. underground coal mines facing both methane control and spontaneous combustion issues, a computational fluid dynamics (CFD) study was conducted to model the potential for spontaneous heating in longwall gob areas. A two longwall panel district using a bleeder ventilation system with a stationary longwall face was simulated. The permeability and porosity profiles for the longwall gob were generated from a geotechnical model and were used as inputs for the CFD modeling. In this study, the effect of methane emissions from the mined coal seam, including the longwall face and overlying rider seam reservoirs on the gob gas distribution was considered. The spontaneous heating is modeled as the low-temperature oxidation of coal in the gob using kinetic data obtained from previous laboratory-scale spontaneous-combustion studies. Unsteady state simulations were conducted, and the effects of the coal’s apparent activation energy and reaction surface area on the spontaneous heating process were also examined.1

By R. J. Visintainer, W. L. Whitlock

"Difficulties with the sizing and operation of centrifugal froth pumps are common and the underlying fluid dynamics are complex. Design and selection often relies on previous experience, offering unreliable guidance for novel applications or unexpected problems. The current paper describes a program of extensive laboratory testing on froth handling centrifugal pumps, covering a range of flows, heads, speeds, viscosity, air content and froth stability. Variations in impeller vane design and the effectiveness of an airlock venting apparatus were also examined. The program resulted in a better understanding of centrifugal froth pump dynamics and insight for the troubleshooting of field applications.INTRODUCTION The Challenge of Pumping Froth In pumping mineral processing froth, the handling of large quantities of air within the fluid is often unavoidable. Efforts to reduce the amount of air present at the pump suction, while always recommended for improving pump performance, may have limitations. Some strategies may also carry an economic penalty, such as unwanted process dilution (e.g. due to water spray or injection), or increased capital cost of equipment due to oversized pumps, sumps and/or piping. Froth pumping losses fall into several categories, as described below and represented graphically in Figure 1. • Density effects: Entrained air reduces the pressure created by the centrifugal pump in direct proportion to the reduction in bulk density. This is not a true “loss”, since the head produced by the pump (in meters of froth), may remain unaffected. However, the reduction in pressure often leads to a corresponding increase in pump speed required to drive the system, which itself leads to increased NPSH required by the pump (NPSHR). Furthermore, by adding a gas phase, the overall volumetric flowrate is increased, assuming a fixed quantity of de-aerated liquid being handled. This leads to increased suction velocity which further reduces the NPSH margin by simultaneously increasing pump NPSHR and decreasing system NPSH available at the pump suction (NPSHA). • Viscosity effects: Increased viscosity introduces an additional factor in some froth pumping applications, such as oil sands bitumen froth. Losses result from increased shear stress within the fluid flow, which increase with flowrate. Viscosity also facilitates the formation of airlock by reducing turbulence and allowing individual bubbles to coalesce more easily within the flow stream. Finally, it increases pump NPSHR by increasing local pressure drop in the vicinity of the vane inlet edges. • Airlock effects: Also known as air binding, it occurs when air or gas coalesces within the pump suction or impeller passages and begins to collect there, held by buoyancy forces within the rotating flow field. In essence, the liquid “floats upwards” towards the pump suction against the outward directed centrifugal forces. The airlock acts as a blockage, with corresponding reductions in flow, head and efficiency. NPSHR also increases, due to increased velocity and distorted streamlines in the flow circumventing the blockage."

Jan 1, 2012

By Surendra Kumar Biswal, Sachida Nanda Sahu, B. C. Meikap

The unutilized iron ore fines (IOF, − 10 mm, 45% to < 60% Fe(T)) left at various mine sites during blasting and processing are rich in goethetic-hematite associated with high clay and considered a potential iron ore resource. The variation of loss on ignition (LOI) from mines to mines is based on the goethite and clay mineral content. The clay containing below 45 μm is mostly brittle, causing beneficiation problems. The IOF has an LOI of 7.83%, with high silica (5.52%) and alumina (4.57%), and 57.17% of Fe(T) subjected to both conventional deep beneficiation (CDB) and magnetization roasting using high-ash non-coking coal to adopt the suitable upgradation process. The CDB and magnetization roasting concentrate has 62.61% and 67.58% Fe(T) with 64.69% and 85.19% yield, respectively. However, the presence of 6.40% LOI in CDB makes the ore challenging for pelletization. Characterization like X-ray diffraction(XRD), scanning electron microscope(SEM), and chemical analysis was used to assess the concentrate quality and potential industrial application.

Jun 4, 2022

By S. H. Ash

THE INVESTIGATION of barrier pillars in the Southern field is part of the comprehensive study of the mine water problem in the anthracite region of Pennsylvania by the Federal Bureau of Mines (1, 2, 5, 6, 7, 8, 9, 10, 11, 12, 15, 16, 18).4 Tim Southern field is in Carbon, Schuylkill, Dauphin, and Lebanon Counties, in eastern Pennsylvania; has an area of 200 square miles; is 70 miles long from Mauch Chunk on the east to the Susquehanna River on the west; and is 1 to 6 miles wide. In the Southern field are 37 underground water pools containing 37312 billion gallons of water (5). Most of these pools overflow to the surface because the barrier pillars controlling them are effective under existent, conditions. Abandonment of mines in the Southern field has resulted in the hooding of 34 percent of the field. The largest tonnage of reserves of anthracite lies in this field, where mining conditions are most difficult. Large reserves of anthra¬cite underlie the abandoned mine workings, and before a great part of these reserves can be developed and extracted, the abandoned workings must be unwatered and kept drained (5).

Jan 1, 1953