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By Frank A. Jerabek

Pneumatic stowing was first introduced in longwall mining in the middle twenties. Since that time it has advanced through many stages of development, particularly abroad, which have greatly improved its efficiency and contributed to its growing use. Pneumatic stowing originated in coal mining but has also been adopted in metal mining. This paper discusses the techniques of pneumatic conveying of. stowing material and equipment and applications of pneumatic stowing.

Jan 1, 1966

By J. Brune

The disaster at the Upper Big Branch (UBB) mine 2010 has demonstrated the destructive violence of a coal dust explosion by killing 29 miners in the worst mining accident the United States has experienced in almost 40 years. This explosion brought to light that the United States mining industry must strengthen explosion prevention and explosion hazard detection practices. Recent legislation such as the Mine Improvement and New Emergency Response Act of 2006 (MINER Act) pushed the strengthening of explosion and disaster response and miner protection in addition to stricter regulations on the sealing of abandoned areas and on conveyor belt flame resistance. The focus of this new act was on how to respond to a disaster or explosion, yet not much improvement was made with respect to prevention explosion disasters. Researchers at the Colorado School of Mines have recently concluded extensive research into methane and coal dust explosion prevention practices and regulations as it may be applicable to underground mines in the United States. This research aims to forward more studies into the use and adoption of standards and procedures that have been utilized in countries with strong explosion prevention histories.

Feb 23, 2014

By Lana Alagha, Ashraf Alsafasfeh, Amal Al‑Hanaktah

As freshwater resources are becoming scarce, the use of seawater as replacement of fresh water is appealing in order to make mineral processing operations more sustainable. Since froth stability plays a critical role in determining the performance of flotation operations, there is an urgent need to study the effect of frother dosage and seawater on froth stability. In this study, flotation tests in seawater were conducted to examine the effect of frother’s dosage (MIBC) on the froth stability and flotation performance of low-grade phosphate ore. The stability of the froth layer was assessed by measuring the froth growth velocity and the froth maximum height at equilibrium. Results indicated that the best flotation performance was obtained at 75 g/ton of MIBC where ~ 90% of phosphate minerals were recovered. At this recovery value, the concentrate grade was determined to be ~ 70%. Results from froth stability experiments showed that the stability of the froth layer increased by increasing MIBC dosage. At MIBC dosage of 75g/ton, the calculated values of dynamic froth stability and the froth height were ~ 0.4 cm/sec and 16 cm, respectively.

Jan 17, 2024

By Y. Topkaya, R. E. Johnson, B. R. Palmer, R. B. Bhappu, A. E. Clark, R. P. Bush, L. E. Schultze

The U.S. Bureau of Mines conducted copper exchange capacity (CuEC) tests for six common clays under simulated in situ leaching conditions. Regression equations were obtained from the data expressing the CuEC as a function of Cu concentration, pH, and temperature. Further testing resulted in regression equations expressing CuEC's of Na and Ca montmorillonites and attapulgite as a function of Cu concentration, pH, and the concentration of metal ions which compete with Cu for exchange sites. Using these equations, an analysis was made of the impact each clay could have on overall copper recovery. The results suggest that Ca and Na montmorillonite clays could have a major impact on Cu recovery and that attapulgite and illite clays could have a smaller, but still significant, impact. Kaolinite and ripidolite clays pose little threat to loss of copper from in situ leaching solutions. Copper losses are decreased by the presence of competing ions, and A1 and Mg have the largest impact of those ions normally present in Cu leaching solutions.

Jan 1, 1993

The National Mining Hall of Fame and Museum will hold its Ninth Annual Induction Banquet Sept. 8, 1996, at the Las Vegas Hilton Hotel. Six mining greats, two of them living, will be enshrined at the event. They will join 126 other mining legends previously honored by the hall of fame. The keynote speaker will be William Perry Pendley, president and chief legal officer of Mountain States Legal Foundation in Denver, CO. Jeffrey Zelms, president and chief executive officer of The Doe Run Co., will be master of ceremonies. Richard Swayne, regional director USA for Boart Longyear Co. of Salt Lake City, UT, will introduce the speakers. Thomas Falkie, president of Berwind Natural Resources Corp. and chairman of the Mining Hall of Fame’s board of governors, will enshrine the inductees.

Jan 1, 1996

By Allen J. Sobczak, Peter J. Peters

The five tunnel contracts of Milwaukee Northeast Side Relief Sewer System are about 80 percent complete. The tunnels are all excavated for 1.9 meter (6'-0") finish diameter sewers in a variable rock, mixed face, and glacial soil environment. Different contracts were let under two primary types of specifications, performance and prescriptive, which treated aspects of construction, such as primary ground support and groundwater control, differently. Interfacing of design and construction through field personnel allowed the needs of all parties to be met and resulted in savings in time and money to the Milwaukee Metropolitan Sewerage District (MMSD). Interfacing, cooperation and risk sharing allowed resolution of problems such as line and grade variations and potential differing site conditions. It also allowed the parties to pursue constructive changes to construction activities. Thus on one contract prescribed use of compressed air was eliminated, but migration of fines into the tunnels was stopped with filter fabric. Use of an expensive primary support system was dropped, but concern about deterioration of lagging was alleviated by use of special materials.

Jan 1, 1983

By Charles T. Holland

The tonnage produced on mechanized automated retreating longwall faces in the United States is growing rapidly. This time last year some 14 faces were operating, and in addition to that, three were known to be down looking towards revision or repairs before being placed back in service. These, it is believed, are now in service. It is estimated at the present time, therefore, that somewhere between 20 and 25 faces are being operated in the country. A survey made last year by the School of Mines, West Virginia University, indicated that longwall mining in general has been beset with a great many problems, some more serious than others. The problems that we propose to discuss here are those pertaining to roof and floor trouble in the tailgates. Longwalls are operating in this country at the present time under an overburden ranging from 200 feet to nearly 3000 feet. Main and tailgate entries are operating in panels of up to five each, with the width of the pillars between these entries varying from 20 to 50 feet. Face lengths are running from 270 feet to 670; actually a face 800 feet long should be possible. The most economical face is often spoken of as being around 450 feet.

Jan 1, 1969

By J. F. T. Agapito

Significant economic benefits can result when rock mechanics is applied within a practical framework and integrated within the other engineering functions of the mine organization. Such application and integration requires management support and understanding of rock mechanics as a practical tool to help attain high standards of safety, productivity and resource recovery. For such an approach, a long-term geotechnical program is needed in most operations to build an adequate data base and to ensure that design and ground control issues are handled in a cost-effective manner. Best usage of rock mechanics in mining occurs when management recognizes the application as a long-term investment, where time is needed to realize good returns. The need for this approach is due to the difficulty in accurately predicting ground conditions ahead of mining. The practical application of rock mechanics must follow an iterative process of design and verification based on site-specific experience to account for geologic and mining impacts. Ground conditions experienced during mining must be used to check the initial mine design and, if necessary, to provide a basis for design modification. Such a practical rock mechanics program includes comparative experience, in situ instrumentation and numerical modeling. The program begins with the geologic site investigation and continues throughout the life of the mine. It is an integral part of mine planning and operation.

Jan 1, 1991

By I. Iwasaki

The effects of autogenous grinding and conventional grinding on the floatabilities of copper-nickel sulfides were investigated as a part of a pilot-plant development project on the differential flotation of Duluth gabbro. At the same mesh-of-grind copper, nickel, and cobalt recoveries were higher and residual sulfur in the flotation tailings was lower with the autogenously-ground pulps. With the ball-mill-ground pulps the residual sulfur in the tailings could not be lowered to the level attained by the autogenously-ground pulps even at increased levels of the collector addition. From mineralogical examinations of concentrate and tailings samples, an electrochemical interaction between grinding media and sulfide minerals was thought to have a greater effect on sulfide mineral flotation behavior than the breakage characteristics of the ore samples in these two types of mills.

Jan 1, 1981

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

The ever-increasing power (and decreasing cost) of computers has opened up substantial oppor¬tunities for 'Vision'-based systems in both on-line and off-line control. This paper reviews image analysis applications in use at the Julius Kruttschnitt Mineral Research Centre (JKMRC) for: •blast and mill feed size monitoring; •AG/SAG mill model-based control; •mineral liberation; and •froth flotation control. The SPLIT™ image analysis system is being used to estimate muck pile and ROM feed sizings. AG/SAG mill feed sizing is being used in a dynamic model for mill control. A new generation mineral liberation analyzer has been developed with Philips Electron Optics. The Philips-JKMRC mineral liberation analyzer offers a substantial improvement in resolution and speed over previous developments. While on-line liberation control continues to be something of a pipe dream, measuring liberation "one shift behind" is now feasible. A robust instrument has been developed to measure flotation froth bubble size and velocity. The instrument also derives a parameter that allows different froth textures to be distinguished. The instrument has been used for on-line control in coal and sulfide flotation. For coal froth, an online ash estimate has been achieved at one site and is being tested at other sites. Overall, image analysis is finding many applications in mineral processing and control.

Jan 1, 2000

By Jake Coibion, Elmira Riahi, Dominic Reda, Walter Klary, Vojtech Gall

Progressive Design-Build is becoming a more common delivery method in the tunneling industry. This approach allows the Owner to select a design-builder primarily based on qualification instead of lowest price. The delivery method promotes flexibility and collaboration at all levels from the initial design stage through construction. Using the example of the Atlanta Airport Plane Train Tunnel West Extension, value-added risk management was added during the initial design phase with an independent reviewer. This paper presents the independent reviewer transitioning from constructability review in the very early stages of design to independent design verification to on-site supervision during construction.

Jun 13, 2023

By Larry Powell

Rend Lake is an Army Corps of Engineers reservoir located in Franklin and Jefferson Counties in south-central Illinois. The lake consists of 20,000 acres of water and 19,000 acres of public access land. The site attracts over two million visitors a year and is surrounded by campgrounds and other recreational facilities. The lake overlies the largest tonnage of low sulfur coal in the state. Coal is being removed beneath the lake from five mines operated by three coal companies. Currently high extraction mining operations are approaching low-lying, environmentally sensitive, and high-use recreational areas. Advanced planning to maximize coal extraction and minimize potential effects of subsidence requires the development of procedures to assess the impact of high-extraction mining on the land use of the area. The Bureau of Mines, the Corps of Engineers, and the coal companies have initiated research to assess the following proposed planning steps to ensure the maximum recovery of the coal resources while minimizing impacts to surface land use: 1) Establish a dialogue between the surface and mineral owners; 2) develop a geographic information system to aid in assessing existing land use and potential changes; 3) assess the potential effects of subsidence on drainage, wildlife habitats, and changes in land use prior to mining; 4) coordinate the mining displacements with surface activities to minimize disruption; and 5) develop appropriate mitigation plans before mining occurs.

Jan 1, 1986

By E. G. Hoover

In the mid-I 970s the rallying cry sent out by the aggregate trade associations to aggregate operators was to come to Washington and help design national legislation mandating reclamation of pits and quarries. This collective effort paid off in that aggregate operators were able to assist in the design of "livable" legislation; however, the coal mining industry took some very hard hits. A principal argument used by the aggregate industry was that relatively small parcels of land are impacted, the operations are located in or near urban areas to serve in the development of that immediate area, and are of many years duration; whereas, coal strip mines disturb many acres, are of short duration, and whose products may have world or nationwide utilization. Historically, developments in reclamation are tied closely to the regulatory systems that have been created to control environmental effects of mining. Since reclamation generally results in a cost incurred after the stone, sand and gravel has been mined and does not add to the inherent value of the mineral, there was little incentive in the past for mine operators to reclaim the land. In 1977, the Surface Mining Control and Reclamation Act (SMCRA) became the law for coal mine operators. The law states that, among other provisions, reclamation must "restore the land affected to a condition capable of supporting the uses which it was capable of supporting prior to any mining, or higher or better uses". It is of interest to note that years before the initiation of legislation leading to SMCRA twenty-eight states already had reclamation regulations that covered virtually all minerals. The scope of performance standards found in the state reclamation regulations included slope stabilization, grading, revegetation, neutralization of toxic materials, visual screening, waste disposal, control of drainage, and other sources of pollution and erosion. Environmental legislation and the consequent regulations came about because the public perceived that private industry did not properly value environmental quality and as a result the government became the policeman.

Jan 1, 1998

By J. C. Cawley, G. T. Homce

The U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) conducted a study of mining industry electrical injuries reported to the U.S. Mine Safety and Health Administration (MSHA) for the years 2000 to 2009. The findings of that study are detailed in this paper, and serve to characterize the circumstances surrounding electrical injuries and identify causal factors. The study included three tasks: 1) a direct review of mining industry occupational injury data compiled by MSHA, 2) interpretation of the narrative descriptions available for the injuries (from MSHA data) and 3) a separate examination of fatal electrical injuries. Eight-hundred sixty-five electrical injuries were reported during the 10-year period studied, with 39 of those being fatalities. This makes electrical injuries disproportionately fatal with respect to most other types of injuries in mining. Electrical injury rates were higher in coal mining than noncoal mining and, within the coal sector, rates were higher in underground operations than in surface operations. Of the 865 total cases, electrical and machine maintenance or repair activities were involved in 580 (69%), and electricians and mechanics were injured in 362 cases (42%). Of the 39 fatal electrical injuries, 27 (69%) involved electrical maintenance or repair work, and in 21 of these 27 cases, the failure to de-energize, lock-out and tag the circuit was the cause or a contributing factor. Also, contractor employees had a much greater chance of an electrical injury being fatal than did mine operator employees. The top three root causes for fatal electrical injuries were 1) no or inadequate lock-out and tagging, 2) failure of power system components and 3) contact of overhead electrical power lines by mobile equipment.

Jan 1, 2013

By Jean-Michel Rendu

In most mining operations, some degree of selectivity is applied. Whether one deals with surface or underground operation, ore zones, and waste zones are defined not only on the basis of the value of the ore contained, but also taking mining constraints into account. A number of computer techniques are presented which can be used to determine the optimum location of the footwall and hanging wall of ore zones intersected by drill holes. Minimum mining width and minimum internal waste width constraints are taken into account, as well as other economic constraints. The system is presented as an integral part of a larger manumatic ore reserve and mine planning system.

Jan 1, 1982

By William F. Stowasser

The United States has traditionally been the world's largest producer and net exporter of phosphate rock and related fertilizer products with the exception of rock exports from Morocco. In recent years, however, U.S. producers have faced increasing competition from operations in foreign countries, leaving the future position of the U.S. phosphate .industry as a leader in the world markets somewhat less certain. This paper will review the U.S. phosphate rock industry in relation to its known demonstrated reserves, its historical and present production and export levels, and its future mining potential. The paper will include an analysis of the availability of phosphate rock in the United States represented by cost-tonnage relationships. The U.S. phosphate rock industry has for decades provided raw materials at reasonable costs to the phosphate fertilizer industry, and the fertilizer products have been made available to both domestic and international markets. Natural soils normally contain low quantities of phosphorus, and cultivation exhausts the available phosphorus through the removal of harvested products. Yields diminish, and it becomes necessary to apply phosphorus to the soil in an amount at least sufficient to compensate for removal. Raising the level of phosphorus also permits nitrogen and potash fertilizer nutrients to be effective and sustain the high crop yields necessary to support increasing food demands. In only a few areas of the world are soils, climate, rainfall, and low-cost phosphate fertilizer available to assure high agricultural yields in successive years. One of these areas is the central United States and south central Canada. By contrast, in the Soviet Union, the weather conditions in farming areas frequently cause crops to either bake or drown in the field. To attempt to counter the effect of weather on production, the U.S.S.R. has increased use of fertilizer and equipment in recent years. The effect of fertilizer on various crops has been documented, and in all cases, improvements in yield and plant development were noted, as was the ability of fertilizer to mitigate the effects of unfavorable climatic conditions. Phosphate resources can be classified as either identified or undiscovered. In the identified classification, we are principally concerned with demonstrated phosphate resources, or those that have been measured or indicated. In the southeastern United States, the phosphate mining areas of Florida and the Carolinas have been explored and drilled extensively in attempts to locate new deposits. The exploration programs indicate that another Florida Bone Valley Formation or North Carolina Pamlico River Deposit is unlikely to be discovered in the southeastern U.S. coastal plain. Phosphate rock deposits of commercial interest in the western United States are located in Montana, western Wyoming, northern Utah, and southeastern Idaho. The deposits are in the Permian Phosphoria Formation with most of the mining activity occurring in Idaho. Although substantial demonstrated resources have been identified, recovery costs and the field's isolation from markets have restricted growth of the industry in the west. The phosphate rock deposits in Tennessee are well known, and it is estimated that about 29 million metric tons1 are potentially recoverable. Undiscovered deposits of brown rock in Tennessee would likely be quite small.

Jan 1, 1985

By James Lett

The role of pre-conditioning in a caving operation has multiple benefits, ranging from assisting with improved caveability, normalising fragmentation and improving draw point hang-up frequency. At Newcrest Mining’s Cadia Operations, both the Ridgeway Deeps block cave the Cadia East Panel Cave have utilised pre-conditioning using hydraulic fracturing. Seismic response data inside and outside the pre-conditioned volume show the benefit of treating the full caving block. Cadia East has further developed pre-conditioning to mitigate developing seismic hazards associated with major structures (fault-slip events) and managing mine-wide seismic hazards in new caving operations where the potential for large damaging seismic events exists due to high stresses and hard competent rockmasses. A case study reviewing the impact of pre-conditioning to mitigate seismic hazard associated with fault slip is presented. Cadia East operation undertook a targeted hydraulic fracturing program and reduced the overall number of large events as an example of the benefits of pre-conditioning. This paper will review the application of Hydraulic Fracturing at Cadia and discuss the geotechnical and seismological parameters of seismic events that occur within and outside of pre-conditioned rockmass volumes to demonstrate the benefits that Hydraulic Fracturing bring to future caving operations.

Apr 26, 2022

By J. G. Nalven

On July 1, 1999, most domestic metal mines will have to report releases of toxic chemicals into the environment for the first time as required by SARA Title 313. Some of these reportable releases will appear huge in relation to reports by other industries. The reasons for the potentially large reportable releases, special considerations for mining operations, and strategies for dealing with the reports are described. Data composited from experience with several mining companies is presented in the context of a typical gold mine.

Jan 1, 1999

By R. Mattos, E. Calcina, G. Quispe, S. S. Kanchibotla

During blasting, rock breaks and moves but standard grade control practices do not adjust ore waste boundaries to cater for blast movement. Rock movement resulting from blasts can result in mischaracterization of grade boundaries resulting in ore loss and dilution. Ore loss takes place when ore is mischaracterized as waste and sent to waste dumps, and dilution occurs when waste is mischaracterized as ore and sent for processing. Las Bambas operations of MMG Peru, realized the economic impact of blast movement on ore loss and dilution and adjust ore boundaries using limited blast movement measurements. This is a step in the right direction but has limitations for everyday application. This paper discusses the advantages of disadvantages of current blast monitoring techniques and introduces an operational tool to estimate polygon movements for different blast designs and confinement conditions. Blast movement estimates from this new tool have been compared against the estimates from the current tools for several production blasts and the results were quite promising.

Mar 2, 2022