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Previous work has shown that significant, free milling gold values exist in the Ryan Lode ore. This project used pilot scale equipment to estimate the percentage of gold recoverable by gravity methods from the circulating load of a conventional, closed-circuit, grinding mill. The pilot scale flowsheet employed three stages of gravity concentration, hydraulic classification and batch grinding to simulate a full scale milling circuit. 172 kg (379 lbs) of Ryan Lode ore were processed, having a head grade of 4.8 g/metric ton (0.14 oz/ton). Results showed that simple gravity methods are capable of recovering 45-50% of the gold values in a concentrate grading in excess of 3430 g/metric ton (100 oz/ton). Of the remaining gold values reporting to the classifier overflow solids (80% passing 70 microns, 3.1 g/metric ton (0.09 oz/ton)) 89% were recovered from 48 hour bottle roll tests.

Jan 1, 1995

By M. E. Poad

In 1986, a cooperative effort by the Homestake Mining company, the U.S. Bureau of Mines and the University of Utah was initiated to determine shaft stability while recovering high grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Six years have elapsed and, despite some initial concern during the first lifts, it appears that the bulk of the original reserve will be safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modelling to mine measurements and observations contributed substantially to the operational success of the project.

Jan 1, 1994

By D. W. Alberter

I consider it a great pleasure and distinction to be invited to appear before your organization to discuss our experiences with a comparatively new system of what is known as a "Full Dimension" extensible conveyor system. One of these systems has been operating in our Diamond Smokeless Mine, Boltz, Pennsylvania, since 1959 servicing a continuous mining machines For those of you who are not familiar with this method of transportation, I would like to offer an explanation.

Jan 1, 1962

By J. Killian, S. Cox

Many questions exist within the geotechnical industry as to the applicability of Strength Reduction Factor (SRF) values to the design acceptance criteria (DAC) of mining operations. There are many factors that contribute to changes in the SRF estimate, some of which are numerical (e.g. dilation angle) and some of which are geometric (e.g. model grid size)[1]. Numerous studies have confirmed equivalent values of SRF and FOS are found for soil slopes of limited height as presented in, [2] and [3]. However, significant deviation of the SRF value was observed for highly cohesive materials (rock slopes) of heights typically encountered in mining, [4]. This paper builds on the work presented in [4], providing a more rigorous examination of the modeling parameters that control the SRF estimate. The failure mechanism assumed for this study was a simple circular shear surface in a uniform material. Both LEM and numerical methods are suited well for analysis of this failure mechanism. A parametric study was completed to evaluate and test the relationships of key numerical variables that affect the estimated value of the SRF using Itasca’s Fast Lagrangian Analysis of Continua (FLACTM) software. The effect of groundwater has been tested and may be significant but is not presented as part of this body of work for brevity and simplicity of presentation.

Mar 2, 2022

By W. M. Hart

The remote face loading and entry convergence monitoring systems, employed at some of the Cyprus Amax's underground coal mines, have been able to continuously record changes in face shield resistance across and entry convergence ahead of the longwall face at any moment during longwall mining. The instrumental data obtained from these systems plus in-situ observations during the mining operation can help us better understand the mechanism of overburden strata movement above a longwall face and verify the effectiveness of the current face and entry supports. This paper describes the functions of both the face and entry monitoring systems, and discusses our findings and the issues related to successful ground control for longwall mining.

Jan 1, 1996

By P. T. Bissert, T. J. Lutz, J. A. Yonkey, G. T. Homce

"The National Institute for Occupational Safety and Health (NIOSH) has been researching refuge alternatives (RAs) since 2007. Refuge alternatives typically have built-in pressure relief valves (PRVs) to prevent the unit from reaching unsafe pressures. The Mine Safety and Health Administration (MSHA) requires that the PRVs vent the chamber at a maximum pressure of 1.25 kPa (0.18 psi, 5.0 in. H2O), or as specified by the manufacturer. To facilitate PRV testing, an instrumented benchtop test fixture was developed using an off-the-shelf centrifugal blower and ductwork. Relief pressures and flow characteristics were measured for three units: a modified PVC check valve, an off-the-shelf brass/cast iron butterfly check valve, and a commercially available valve that was designed specifically for one manufacturer’s steel pre-fabricated RA and has been adapted for use in built-in-place (BIP) RAs located at one mine. PRVs used in tent style RAs were not investigated. The units were tested with different modifications and configurations in order to check compliance with 30 CFR regulations. BACKGROUND The Mine Improvement and New Emergency Response Act of 2006 (Miner Act) (1) was enacted in the wake of three mine explosions/fires that claimed 19 lives that year. Intended to help improve underground coal mine accident preparedness, the MINER Act includes provisions that target mine safety issues in areas such as emergency response planning, adoption of new technology, training and education, and mine safety standards enforcement. Section 13 of the MINER Act specifically directed the National Institute for Occupational Safety and Health (NIOSH) to provide for research into the effectiveness and viability of refuge alternatives (RAs) for underground coal mines, and the Department of Labor to act on the results of such research as appropriate. These mandates culminated in the 2009 adoption of changes to 30 CFR mining health and safety regulations, requiring underground coal mines to provide mine emergency RAs and associated components, to provide a life-sustaining environment for persons trapped underground. Such RAs can be either self-contained mobile units or built-in-place (BIP) facilities. The regulatory changes also include provisions establishing requirements for the Mine Safety and Health Administration (MSHA) approval of RAs and their components, and among these provisions are numerous criteria for providing a safe breathable atmosphere under positive pressure within the RAs. One specific criterion for maintaining a safe RA atmosphere requires the inclusion of an air pressure relief valve that will activate at a maximum of 1.25 kPa (specified as 0.18 psi, or approximately 5.0 in H2O), or at a pressure as specified by the RA manufacturer, above mine atmospheric pressure in the RA (2)."

Jan 1, 2016

By M. A. Reinsel

New technology for removal of nitrate from low-temperature waters has been developed. Typical results from the first operational-scale system (operating at a metal mine in Montana since January 1996) are over 90 percent nitrate removal at a flow rate of 130 gpm and a water temperature of 12°C. The system also operated successfully at flow rates as high as 300 gpm and water temperatures as low as 2°C. The ABC is advantageous because it is: a) cost-effective to design, construct and operate, and b) effective at cold water temperatures. The system can be designed for a variety of flows, nitrate concentrations, water temperatures and water qualities.

Jan 1, 1998

By J. B. Mitchell

Comminution methods for base metal and precious metal ores have had considerable attention from mine operators, equipment suppliers and design engineers for many years and much of their work has been well reported. This interest derives from a healthy concern with the costs of comminution, often the largest single cost factor in ore dressing of hard ores. Many imaginative innovations have resulted. One notices a trend toward autogenous and semi-autogenous methods, combined with a trend toward very large equipment. Unfortunately, there has been less obvious cost incentive to experiment with softer ores. This is unfortunate because the consequences of inappropriate comminution methods can have an important effect on overall economics by influencing down stream processing and salability of final products. This paper concerns some of the factors to be considered in the selection of comminution methods for potash ores, and gives some specific examples to illustrate some of the principles involved.

Jan 1, 1969

By Douglas F. Crickmer

Pocahontas Land Corporation, a wholly-owned subsidiary of Norfolk and western Railway Company, owns a 100,000-acre block of coal lands in Martin, Johnson, Pike, Floyd and Lawrence Counties, Kentucky. These holdings were largely acquired in three major purchases between the years 1942 and 1959. The area is undeveloped and constitutes a part of the coal reserve for future mining. This block, which is principally in Martin County, lies in a triangle formed by the Levisa and Tug Forks of Big Sandy River on the sides with Dewey Dam at its base and the Town of Louisa at the apex. The topography'is typical of eastern Kentucky and consists of steep hills rising from 500 to 800 feet above creek level. There is little level ground in the area. As a matter of fact, some roads are on the creek bottoms with what little bottom land is available in the hollows being utilized for small-scale farming. The steep hills are marked by three separate massive sandstone formations which form cliffs ranging from 40 to 100 feet in height.

Jan 1, 1964

By M. R. Paterson

Operational and economic factors tend to favor the application of continuous processes in preference to batch processes in the majority of mineral processing applications. In this paper, the requirement for a Continuous Elution Process is established and the development of a large-scale pilot plant is described. It is based on a Continuous Elution apparatus which has a number of special features. These are the subject of various patent applications. The apparatus is suitable for adaptation to the AARL, Zadra and other methods of elution. The performance of the Atmospheric Continuous Elution System (ACE) is concluded to have significant advantages over the batch process.

Jan 1, 1986

By L. Yuan, C. Brown, N. Rayyan, J. Soles, T. H. Dubaniewicz

As lithium-ion batteries (LIBs) become more prevalent in the mining industry, new hazards of battery fire and explosion are emerging. Efforts must be taken to ensure that workers are safe from these new hazards, such as batteries undergoing thermal runaway in underground areas that may have explosive methane-air mixtures. Researchers at the National Institute for Occupational Safety and Health (NIOSH) investigated overpressures generated within a sealed battery enclosure filled with an explosive methane-air mixture and a single cell lithium-ion battery driven into thermal runaway using an accelerating rate calorimeter (ARC). For both iron phosphate (LFP) and nickel manganese cobalt (NMC) lithium-ion cells, the explosion overpressures remained unchanged with varying percentages of methane concentration in the atmosphere surrounding the cell. It’s likely that the gases released from the battery undergoing thermal runaway caused an inert atmosphere within the sealed canister. The results from this study will help mining equipment manufacturers develop proper measures to keep miners safe while working with lithium-ion batteries in underground gassy mines

Mar 2, 2022

By F. C. Bond

History The breaking and shaping of rock was one of man's earliest occupations. In the Paleolithic Age long before the dawn of history, arrow¬smiths and the makers of stone axes, hammers, knives, scrapers, spears, and borers were highly respected members of society. In early historical times stones for building blocks, roads, and city walls were shaped by slaves and convicts, who also did most of the mining. However, great artists erected beautiful stone sculptures, while gifted architects planned imposing temples and monuments. Until well into the 19th century nearly all rock was broken laboriously by hand. The small rock required by John MacAdam for his macadamized roads in England in the 1820s was produced by women and boys seated alongside the roadside with hand hammers and legs wrapped with rags. Eli Whitney Blake, a nephew of the Eli Whitney who invented the cotton gin, developed the first successful jaw crusher before 1870. The gyratory conical crusher soon followed. Comparative tests established its large capacity advantage over the jaw crusher, as well as its greater cost for a given feed size. Both types have been in use for more than 100 years. Crushing rolls appeared before 1900. Thomas A. Edison made very large diameter rolls which were excessively long; they failed because of shaft deflection. Various types of disk crushers and edge runner rolls appeared about this time. The older methods of reducing rock were adaptations of other processes. The stamp battery of dropping weights effected crushing by simulating heavy hammer blows; the much earlier arrastre, in which heavy stones were dragged in a circular path over the ore by animal power, came from the prehistoric method of grinding grain between two rubbing stones, while the jaw crusher was adapted from simple squeezing devices. But the tumbling grinding mill was not just an adaptation; it was an invention, because it required thinking on a somewhat higher order-there was no prototype. Its nearest antecedents were probably the small closed tumbling drums used in England more than a century ago for cleaning and polishing small iron castings. The date of the first tumbling mill actually used to grind rock is unknown, but it was later than the American Civil War (1861¬1865). It was almost certainly a closed or batch mill in which rock was placed and rotated until it reached the desired particle size. It could have been operated either wet or dry. The first published refer¬ence to such a batch mill was one introduced by Alsing in England (1870) for the grinding of calcined flints for pottery work.21 There are several rather indefinite reports of grinding mills in the early 1890s, including an overflow ball mill in the Helena and Livingstone reduction plant in Montana which may have been the first of its kind. 11 Many of the first mills, which were called tube mills, used hard rock both as grinding media and as mill lining. The rock used was preferably stone from the Normandy and Danish beaches, when it could be imported. This remarkable siliceous stone was already widely used for grist mills throughout America, and its resistance to wear was greatly respected. The decade of the 1890s saw the development of tumbling mills with continuous feed and discharge and their extension into different industrial uses. By 1895 some experience had been accumulated. Iron grinding balls were being tested and the proper speed of rotation was being determined. The Clark Patent tube mill was featured in an E. P. Allis bulletin of 1890, which may have been the first published description of a tube mill. More than 1,000 Gates tube mills had been built by Allis-Chalmers before 1913. Many of these were used in gold mining, espe¬cially in South Africa. The 5 x 22-ft size was particularly favored for grinding portland cement; the use of tumbling mills in the manufac¬ture of cement began about 1900. A great deal of attention was paid to the mill lining. Metal was then relatively expensive, and the general approach was to trap some of the rock grinding media into mill lining pockets. This rock would then absorb the wear and protect the metal lining. In the first ten years of the 20th century there were several different types of pocketed liners, with different manufacturers advancing the superior claims of their patented arrangements. The Osborne liner, developed in South Africa, was probably the most successful. 21 Another item which attracted much attention was size classifica¬tion within the mill and in ancillary equipment attached to the mill and rotating with it. The Krupp type, with interior screens protected inside the mill lining, was developed quite early in Germany, possibly before 1890. The Dorr reciprocating rake classifier (1907) had not yet been invented, and many strange and impractical screening and classifying devices were proposed. In these unsatisfactory machines the two separate processes of size reduction and classification were combined into one operation. It was many years before recognition came that a machine is most efficient when it is designed for one specific purpose. There was much industrial wastage before the opera¬tions of grinding and classification were finally separated. After 1900 the grinding of portland cement raw material and of cement clinker required large numbers of tumbling mills. Most of the raw material was then ground dry. This was also the heyday of gold mining. The old stamp mills that were used in great numbers for grinding gold ore did not grind sufficiently fine to liberate all of the gold, and the new tube mills were installed following the stamps. After 1910 larger diameter tum¬bling mills with larger grinding media were developed. These could receive the finely crushed ore directly, and the inefficient stamp batter¬ies were gradually eliminated. The Rand in South Africa was the greatest gold producer, treating immense quantities of rather low-grade but consistently free milling gold ore. The first tumbling mills, or tube mills, went into operation there in 1904. They were so successful that within a few years no new stamp batteries were installed in the district, even though old ones continued to pound away until after 1950.3 The early tube mills on the Rand all employed Normandy or Danish pebbles, which had to be imported at considerable expense. Their reported wear was as low as 4 lb per ton ground. 4 Many of the mills were lined with the same tough Danish stone cemented into place, while others used the pocketed steel Osborne liner. It was in 1907 on the Rand that an important test was made using hard native ore for grinding media in place of the expensive imported pebbles. 3 This ore, called banket, did not wear as well as the renowned Danish pebbles, but the cost per ton of grinding was definitely reduced. Many of the tube mills on the Rand were soon grinding with native ore. This was the beginning of the development now called autogenous grinding, in which the ore grinds itself. This is treated under a separate heading. See Subsection 3C, Chapter 4. Gold mining was important in America also, and its grinding history follows that of the Rand. Danish pebbles were replaced by native ore in Santa Gertrudis, Mexico, in 1913, 4 and in Consolidated Gold Fields, Nevada, in 1914. 5 Other properties followed suit. However, it gradually became apparent that the capacity of a given mill could be almost doubled if rock grinding media were re¬placed by cast iron or steel grinding balls. In order to increase plant grinding capacity many rock media mills were converted to iron grind¬ing media in the second decade of the present century. In some mills the motor size was doubled; other mills were cut in two and another motor was provided for the second half. Grinding mills began to assume a more modern appearance. Crushing rolls were formerly much used following crushing in jaw or gyratory crushers and preceding grinding in ball mills. How¬ever, the roll surfaces wore rapidly, and skilled maintenance was required to obtain even wear. Rod mills could take feed of the same crusher product size and reduce it finer. The first rod mill was con¬structed by Mine and Smelter Supply Co. and was tested in Canada

Jan 1, 1985

By D. R. East

Recent experiences within certain sectors of the international mining industry suggest an underestimation of the environmental risk associated with the design of mine waste management facilities. These experiences show that the technical and managerial challenge of responsible mine waste management is not always fully appreciated. Unfortunately, the image of the mining industry's environmental performance is negatively impacted by a relatively few number of failures. This negative view overrides the many positive contributions made by the majority of mining companies. The fact that these failures continue to occur to this day in both developed and developing countries is indeed remarkable, and indicates a degree of risk-taking approaching unacceptable levels. The design requirements for tailing storage facilities are, in many cases, more demanding than those of conventional water dams, because seepage of fluids which contain dissolved metals may pose a greater threat than the mere loss of water.

Jan 1, 1999

By Irvine G. Reilly

Results of a preliminary study of the ammoniacal leaching of covellite (CuS) in an aqueous oxidizing system in the presence of a non-miscible organic sulfur solvent are described. Up to 60% of the sulfur can be recovered from the solvent as elemental sulfur 1 while achieving high degrees of solubilization of the mineral. The effects of temperature, particle size, oxygen pressure, ammonia concentration and ammonium ion concentration on the degree of sulfur recovery were investigated. Maximum recoveries were achieved at moderate temperatures and in well-buffered systems, with a large excess ammonia concentration. Oxygen pressure and particle size were found to have little effect on fractional recovery of sulfur. A simple empirical model based on electrochemical theory correlating the effects of some of the parameters cont-rolling the degree of sulfur recovery is presented. The results of this work also confirm that in any proposed reaction mechanism for the oxidative ammoniacal leaching of copper sulfides, the primary oxidation product of the sulfide ion in elemental sulfur.

Jan 1, 1978

By R. E. Coleman

Infrared spectroscopy, employing the internal reflection method in conjunction with solvent extraction techniques, was used to study surface reactions between aqueous potassium ethyl xanthate and both sphalerite and precipitated zinc sulfide each activated with aqueous copper sulfate. It was determined that reactions occurring on the sphalerite and zinc sulfide surfaces produce the reaction products ethyl dixanthogen and cuprous ethyl xanthate, some of which are ad¬sorbed on the mineral surfaces. According to infrared spectra showing the reaction to form these compounds, the ratio of cuprous ethyl xanthate to ethyl dixanthogen adsorbed is directly related to pH of the flotation solution.

Jan 1, 1967

The Penetrating Cone Fracture (PCF) technology 1 is a new method of rock excavation developed by Sunburst Excavation, Inc. of Denver, Colorado. PCF is a rock excavation method which employs tensile breakage mechanisms under controlled conditions to enable the continuous excavation of rock?in underground and some surface applications. The technology has developed rapidly over the last two years to the point where it is now being prepared for commercial application in the mining and civil construction industries. The initial commercial application of PCF will be undertaken at the Perseverance Nickel Mine of Western Mining Corporation Limited in Western Australia beginning in May, 1994.

Jan 1, 1994

By T. L. Dobecki

Numerous seismic techniques have proven to be important and cost effective aids to both coal exploration and nine planning. Projects conducted by Sandia in recent years have sham seismic refraction is a valuable tool for determining overburden properties while high resolution, 2-0 and 3-D seismic reflection surveys are the primary means of napping coal seam distribution, structure, and continuity. Further, seismic methods utilizing existing boreholes (e.g. downhole, crosshole and guided wave) provide detailed measures of overburden/interburden modulus variation, seam continuity, and calibration for other seismic surveys. Examples include mapping faults of 2-10 m threw in seams 3-15 m thick at depths of 80-300m.

Jan 1, 1982

By W. F. McDermott

One of the major improvements in ore grinding economics in North America has been the introduction of autogenous grinding. The history of this has been well documented in previous AIME presentations and in the literature. Pickands Mather & Co. has been very active in the development of autogenous grinding since 1957. This early work led to the application of autogenous grinding to the Wabush Mines ore in 1965, with the installation of 6-24 ft. diameter by 8 ft. long - 1,750 HP mills. Development work recently completed in 1971 on another ore has led to the decision to install 5-36 ft. diameter by 15 ft. long - 12,000 HP mills when this project goes ahead. Between these two decisions lies a tremendous amount of research, development, and application of autogenous grinding to a variety of ores. The Pickands Mather Metallurgical and Research Laboratory in Hibbing, Minnesota has tested, in its pilot plant facility, ores from 9 different deposits. Some of these deposits have as much difference within their own ore types as there is between the various deposits. Therefore, it is safe to say that over 20 different ore types have been tested and flowsheets developed for commercial applications. Of the 9 projects, 3 are in operation. These are Wabush Mines in Labrador, Canada, (1) Savage River Mines in Tasmania, (2) and The Griffith Mine in Red Lake, Ontario, Canada. (3) Pilot plant work has encompassed over 300 individual tests. These tests were carried out in mills that were 5-1/2, 8, and 12 ft. in diameter. Grinding power requirements for the primary autogenous milling has varied from 2 to 30 KWH/Lt of crude ore.

Jan 1, 1972

By J. C. Cawley

Improvements in today's maintenance practices are mandatory as more complex and productive machines evolve in the mining industry. By keeping machine reliability high, through improved maintenance procedures, overall mining costs can be reduced. The Bureau of Mines is investigating diagnostic maintenance systems for underground mining machinery. A hydraulic expert diagnostic system and an electric motor predictive diagnostic system have been designed and installed on a Joy 16CM continuous miner. An electrical diagnostic system has been designed and installed on a Joy 14CM continuous miner. Each system is functionally described and the relative merits of expert diagnostic systems versus algorithmic diagnostic systems are discussed.

Jan 1, 1991

By E. Watkins, R. Kimutis, H. Dougherty

Gas wells have often intersected mining resources, but unconventional shale well drilling has more recently challenged mines to balance the risk of interaction due to higher pressures and larger quantities of gas. Full extraction mining, such as the longwall method, induces ground movement that may influence the casings if wells are drilled within the mining area. The possibility of a casing shear would lead to the risk of unplanned gas migration into the mine. This has the potential to quickly overcome the ventilation system and reach the explosive range which, if ignited, can have catastrophic consequences on the health and safety of underground workers. The utilization of network software to model mine ventilation is a common practice in the mining industry and can assist with a well breach scenario. This work focuses on a well breach in between two longwall panels after second panel mining with gas entering primarily through the gobs of the adjacent longwall panels. Applying the network software Ventsim, a gob zone and ventilation network were created to better understand the distribution of gas within the mine and the limitations and effectiveness of a ventilation system. The model shows both a transient flow simulation and steady state concentrations throughout the mine ventilation system. Using a standard Pittsburgh coal seam longwall ventilation scheme, we find that the system can dilute a significant inflow of up to 700 cfm of methane.

Mar 2, 2022