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By M. Ge

Pattison Mine is a small sandstone mine located in Iowa. The sandstones produced by the mine are not common construction and aggregate materials. The stones are used to produce a special type of sand for hydraulic fracturing, a critical technique for recovering tight gas and shale gas. These sandstones are very different from the minerals and rocks which have been studied extensively in mining. On the one hand, they are brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, they are friable, possessing extremely low, and in most cases zero cohesion. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for the mine operators. In order to resolve these problems, a research program was set up by the mine and Missouri University of Science and Technology. This paper discusses the preliminary results of this investigation.

Jan 1, 2012

By George A. Savanick

The objective of this paper is to review advances in the art of borehole (slurry) mining made by the Bureau of Mines. The introduction gives historical and general background information on borehole mining. The borehole mining concept is defined and justified in terms of economics, health and safety, the environment, and resource conservation. This is followed by a description of the design of a prototype borehole mining tool (BMT) developed by the Bureau of Mines. Included are design drawings and performance specifications. The next section describes the application of the BMT in the extraction of metallurgical coal from steeply pitching seams near Wilkeson, Wash., during 1975-76. The field test showed that the BMT produced coal at the rate of 8 tons per hour (tph) (7,272 kg/hr) from a depth of 88 feet (26.8 m) and was effective in producing coal as far as 15 feet (4.6 m) from the center of the borehole. The data are used as a basis for an economic analysis of borehole coal mining and for the suggestions for the design of a second-generation borehole coal mining tool. The following section describes Bureau efforts in applying borehole mining to the extraction of uraniferous sandstone at Rocky Mountain Energy Corp.'s Nine-Mile Lake site, Natrona County, Wyo. BMT design changes appropriate to uranium mining are described along with production, reliability, and reclamation data taken during 1977-73. The field test revealed that the BMT produced 900 tons (81.8x105 g) of uraniferous sand at an average race of 8 tph (7,272 kg/hr) from a depth of 75 (22.8 m) to 90 (27.4 m) feet and created a cavity 25 feet (7.6 m) in radius. These data are used as the basis for an economic analysis of borehole mining of shallow uraniferous sandstones. Reclamation data included will be the results of backfilling experiments conducted at Nine-Mile Lake during 1978. The most significant of these data were that backfill was emplaced at the rate of 16 tph (14.5x103 kg/hr) and that 90 percent of the material extracted from a cavity can be backfilled.

Jan 1, 1979

By F. Warnaars

Historically, this area produced gold and silver from many well-known vein deposits, like Tayoltita, Topia, and San Jose de Gracia. Modern exploration identified three categories of deposits: 1) low grade porphyry golds in shallow level dacite porphyries; 2) batholith-related deposits; and 3) those formed in volcanic sequences of Late Cretaceous to Late Tertiary. At least four porphyry golds have been identified, of which Metates is best known. These are formed by and within daciteporphyries, associated hydrothermal breccias and sometimes within surrounding meta sediments. Their ages are from mid-Cretaceous to Early Tertiary. Precious metal deposits associated with batholiths occur as veins, contact haloes in meta sediments or volcanics, skarns, tectonic breccias, hydrothermal tourmaline breccias, dacite dikes or as disseminated or stockwork deposits such as La Fortuna.Several new gold discoveries were made in older EarlyTertiary Volcanic Sequences and in the younger Tertiary volcanics within prominent structures exceeding 3 to 5 km in lengths. Some of these are open-pittable but most have to be mined by underground methods.

Jan 1, 1999

By Y. V. Swamy, B. Bhoi, H. S. Ray

Low-grade manganese ores with low Mn/Fe ratios can he enriched through selective carbon reduction of iron oxide to magnetite followed by magnetic separation o f the magnetite. Thermogravimetric analysis (TGA) was used to assess the preferential isothermal reduction of pure M1702 and Fe2O3 using solid carbon. This was followed by reduction of a synthetic analogue of composition comparable to an actual low-grade ore (i.e., Sandur manganese ore, Sandur, India). The carbothermic reduction of the manganese ore converts the hematite and goethite minerals to magnetite (Fe3O4), with the magnetite then going into the magnetic, fraction. The resultant nonmagnetic ,fraction becomes depleted of iron with an enhanced manganese content. These results show that it is possible to reduce the iron from 22% to 5.85%, thus increasing the Mn/Fe ratio from 1.52 to 6.2 with a manganese recovery of about 50%. The recovery was, further improved by grinding the magnetic fraction to -75 µm.

Jan 1, 1999

By Sahendra Ram, Ashok Kumar, Rakesh Kumar, AMIT KUMAR SINGH, Dheeraj Kumar, Arun Kumar Singh, Rajendra Singh

This article offers an examination of a retreat mining method conducted at the Pinoura Mine in India from 2010 to 2017. The method is atypical for coal mines of India’s coalfields. The method executes depillaring in a single pass and does not require the formation of galleries and support installation in splits, thus, reducing the cycle time. A variety of observations are discussed throughout this work and emphasis is placed on field measurements and depillaring under weak roof (RMR = 40–45). This paper discusses design techniques, specifically the estimation of the snook (remnant pillar) size, and important practical observations after the fact. The execution of this method was eventually conducted in eleven panels.

Aug 4, 2020

By T. R. Ellis

The vast majority of valuations produced for mineral properties using the net present value method provide an estimate of Investment Value or Use Value. Such an estimate can be a long way from the price that the property would sell at if placed on the market. Indicators from the market need to be used to validate or modify the net present value calculation. The comparable sales and replacement cost approaches used in the appraisal of urban buildings generally fail us in the appraisal of mineral properties. Other methods of sales analysis are introduced. Guidelines for what a minerals appraisal report should contain are presented.

Jan 1, 2000

By David D. DiPonio, John DiPonio, Roger Van Omen

The greatest opportunity to attain the most favorable prices for underground construction projects occurs during the competitive bidding period. The Owner, Engineer, and Contractor need to have a thorough understanding of the project’s design concept, how it is going to be built, and what it is going to cost. This paper presents the opinions of three engineering professionals who are well established in their sectors of heavy civil underground public works construction. This paper will outline and summarize the considerations that the three principal contracting parties of Owner, Engineer, and Contractor need to make to obtain good price quotes at the time of bids.

Jan 1, 2005

By C. J. Hall

I would like to congratulate Professor Gershon on an idea that is obviously valuable and is certainly new to me. It has, however, to be further developed, in that one can get fallacious results by limiting oneself to positional weights. In the example problem, the positional weight of one block was 8.6 (the 8.0 value in the paper was incorrect) for 36 units in the cone, for a mean block value of 0.239. The positional weight of the second block was 4.4 for 15 units, for a mean block value of 0.293. Surely one would expect the second block to be rated higher. Additionally, the time value of money adjustment cannot be determined by depth, because the time that a block is mined is determined by the mining sequence, not depth. Figure 1 shows a slightly altered version of Professor Gershon's pit. The overall value of the pit is the same, as are the total values under each of his blocks. The values in the right-hand cone have been reversed top to bottom, and the values in the rest of the pit adjusted to keep the central cone total unchanged. All values have been multiplied by 10. Figure 2 shows the sequence of mining, at three blocks per year, for Professor Gershon's pit, and Fig. 3, the sequence for a pit under the other block. Table 1 shows the value and discounted value (15%) of Professor Gershon's pit, and Table 2 shows similar values for the second pit. It is apparent that the second pit schedule is more valuable than the first.

Jan 1, 1988

By Earl L. Rau

At the present time, whether an electric utility uses high-sulfur coal is largely determined by geographical location, clean air legislation, and the age of the power plant. Acid rain legislation may well be the new force to change the use of high-sulfur coal. A number of coal papers were presented at the SME Fall Meeting in St. Louis, MO, Sept. 1986. These papers discussed high-sulfur coal in relation to its economics, trends and prospects, value of cleaned coal, and coal-cleaning technology. The Clean Air Act of 1970 required the reduction of SO, emissions from most stationary electric-generating plant to 0.5 kg (1.2 lbs) SO2, per million Btu of heat input. It was possible for many plants to utilize lower-sulfur coal or a mixture of high-sulfur and low-sulfur coal to meet this emission requirement. This 1970 act greatly increased the use of low-sulfur western coal. The 1978 amendment to the Clean Air Act required all new plants to use Flue Gas Desulfurization (FGD) to meet a requirement of 70% reduction of potential SO2 emissions to 0.3 kg (0.6 lb) SO2 per million Btu of heat input. With the requirement to use FGD, there was little or no demand for low-sulfur western coal in new eastern power plants. If' new acid rain legislation is enacted, it likely will require sizeable reductions in SO2, emissions by existing coal users. There might then be a shift to greater use of low-sulfur coals. The low-sulfur coals could come from either western or eastern mines or from cleaned eastern coals. Economics will dictate the approach older power plants will take to meet new regulationsuse FGD or low-sulfur coal. Coal use for electric power generation has changed from 1970 to 1985. Table 1, (Land, preprint 86-333) shows the change. The table shows that in 1985, US utilities used about 255 Mt (280 million st) of high-sulfur coal. Some 45 to 54 Mt (50 to 60 million st) of high-sulfur coal is being used in plants equipped with FGD and most of this use is in eastern states. This leaves 200 to 209 Mt/a (220 to 230 million st) of high-sulfur coal being used without FGD treatment. These plants are at risk if acid rain legislation is passed. Most of these plants are in the east and are more difficult to supply with low-sulfur coal. Estimates range from $20 to $30 billion capital investment and from $5 to $9 billion dollars per year operating costs to reduce SO2, emissions from those old medium-to-high-sulfur coal-burning plants. G. W. Land, (preprint 86-333), also presents tables relating to power generating costs and coal types. The author's tables are extracted from Land's tables IV and V. Table 2 here presents costs for a new plant. This includes the impact of different heat rates, fuel costs, fuel qualities, operating and maintenance costs, labor costs, and waste disposal costs. Table 3 compares estimated costs to retrofit an older plant with a limestone scrubber versus switching the same plant to low-sulfur eastern or western coal. Costs of switching include upgrading the electrostatic precipitator and - with western coal - costs of derating. Bhagwat, (preprint 86-325), details the trends in high-sulfur coal markets from 1974 to 1984. He also gives some prospects for high-sulfur coal markets, 1984 to 1994. The prospect depends mostly on whether acid rain legislation is enacted. By 1994, if New Source Performance Standards (NSPS) continue to be applied, high-sulfur coal demand from six mid-west and eastern states is expected to increase by 27 Mt (30 million st). • L. A. Khan and J. W. Baxter, (preprint 86-373), discuss several coal cleaning technologies such as froth flotation of fines, bulk oil separation and oil agglomeration, oil agglomeration/flotation, and air-floc flotation. ? (Space limitations preclude listing references. A complete list is available from the author.)

Jan 1, 1987

By Marcelo de Oliveira, Antoine Allanore, Dennis P. Chen, Davide Ciceri

Potassium fertilizers (potash) are mined in a handful of countries in the Northern Hemisphere. Potash is either expensive or unavailable to the farmers of the Southern Hemisphere. Alkaline alteration of K-feldspar rock (ultrapotassic syenite) in autoclave in the presence of Ca2+ generates a mixture of K-bearing calcium-aluminum-silicate-hydrate (C-A-S-H) minerals that potentially can be used as an alternative local fertilizer. This work investigates the effect of processing temperature (200 °C, 220 °C, and 230 °C) and time (from 0.5 to 3.0 h) on pH, mineralogy, and elemental availability of the C-A-S-H mineral mixture. Increasing temperature results in an increased conversion of K-feldspar and increased content of both the mineral tobermorite (Ca5Si6O16(OH)2·4H2O) and amorphous phase in the resulting C-A-S-H mixture; increasing time results in an increased conversion of α-dicalcium silicate hydrate into tobermorite. The amount of K leached from the mixture is relatively constant across all processing conditions. Hydrothermal alteration in autoclave of K-feldspar-bearing rocks such as ultrapotassic syenite permits the synthesis of a potential potassium fertilizer which alkalinity and mineralogy can be tailored according to soil requirements.

May 22, 2020

By B. Cousins

Flotation reagents are critical to the optimum performance of flotation circuits. How a flotation reagent performs within the first few cells of a flotation train is a key indicator of how well it will perform throughout the entire circuit. A method to compare reagent performance was recently developed by Ashland Water Technologies. The procedure involves collecting a timed sample of concentrate from each cell and then measuring the volume of the settled solids. An estimate of the percentage of concentrate collected from each cell can then be mathematically determined, providing an understanding of the recovery changes in each cell. Data from trials at a coal flotation circuit are used to demonstrate the method's validity.

Feb 27, 2013

By Meng Li, Hao Nie, Weitian Ding, Mamdouh Omran, Ying Li, Yao Ge, Yaowei Yu, Abourehab Hammam, Lei Zan

This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H2 atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H2 is more efficient thanwith CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H2 gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H2 atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H2 atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion.

Sep 29, 2020

By D. B. Spears

The sillimanite group includes the aluminosilicate minerals sillimanite, kyanite and and alusite, all of which have the same chemical composition (Al2SiO5). This discussion also includes the closely related mineral, mullite(about Al6Si3O15), which, although rare in nature, is produced artificially for industrial use. All of the minerals in this group have a low coefficient of thermal expansion and high corrosion resistance. This makes them desirable for refractory applications, especially in the steel and foundry industries. Other uses include electrical insulators, abrasives and household ceramic products. The minerals in the sillimanite group decompose with an irreversible expansion at temperatures between 1,300° C and 1,600° C (2,372° F and 2,912° F). Sillimanite and and alusite have relatively small expansion on decomposition (4 percent to 6 percent) and, therefore, can be used as aggregates in refractory products. Kyanite’s expansion on decomposition is large (18 percent). So it is sometimes used to balance shrinkage of other materials such as clays in refractory mixtures. For applications requiring high-temperature volume stability, mullite is more desirable. As an additive, mullite improves resistance to creep and corrosion, and imparts thermal and electrical insulating properties.

Jan 1, 2005

By H. Kinilakodi

The authors previously had developed a methodology that combines injury and citation measures into an overall mine safety performance evaluation tool, called the Safe Performance Index (SPI). It can be easily adopted by mine operators to monitor trends in their injury and citation experiences as a risk assessment method. In this paper, six normalized safety measures and the SPI are used to evaluate the risk that existed at mines in the two years preceding the occurrence of a fatality. The percentage of mines is given for which the risk was high or where trends of some of the safety measures indicated moderate risk. In 50% of the mines, this mine safety performance tracking method could have been helpful to the companies, state agency, or MSHA in recognizing and addressing emerging problems with actions that may have been able to prevent high-risk conditions, the fatality, and/or other serious injuries. The approach would have given scrutiny to the risk for mines that encompassed 74% of the fatalities during 2007-2010.

Jan 1, 2012

Man’s search beneath the earth for minerals has always required light, and the devices used to provide illumination have been both innovative and unusual —from stone vessels holding fat and a wick of grass or fiber to a shower of sparks produced by a thin steel disc. While the date when lamps were first used in mines is unknown, Greek and Roman records from 3000 BC definitely mention their use in underground mines. Early Remans most likely used a lamp similar to the one depicted at right. Over the ages, various types of devicives and methods of illumination have been tried and used. One interesting scheme for underground light was to reflect sunlight down the shaft and along drifts using mirrors or other reflective materials. Bunches of resinous wood were also used for underground lighting in many parts of England. In the mid-18th century, the speding mill was developed in England. It worked by rapidly turning a thin steel disc against a flint, causing a shower of sparks to appear. The light produced was uncertain, highly variable, and unsafe in gaseous environments. In Europe, an open pan-type hanging oil lamp was developed and used in some operations in the 1700s. This type of lamp had one opening for a wick and a second opening for refilling the oil reservoir. The lamps were embellished with goad luck charms – a good luck rooster was used in many parts of Europe while a frog and “gluck-auf” were used in Germany. These lamps were introduced in Mexican mines, and a few have found their way into the southwest US. By 1850, a small wick lamp known as the lard-oil lamp, which resembled a tea pot, was invented in Scotland. These lamps were fueled with grease from a packing house –lard, bacon grease, or tallow. Whale oil was also used. Many improvements were made on these lamps, such as the use of windshields and the attachment of miners’ candle-holdm to support the lamp. While these lamps were handy and inexpensive to operate, they were dangerous because their large flame could ignite support timbers or other flammable materials. Miners from the United Kingdom brought this type of lamp into the US. Domestic producers of oil wick lamps were primarily located in Hazleton, PA; What Cheer, IA; Pittsburgh, PA; and Frostburg, IN. The first patent for an oil wick lamp was granted to W. Seybold of McKeesport, PA. Incidentally, these lamps were advertised in a 1903 Sears-Roebuck catalog for 10 cents apiece. Oil wick

Jan 7, 1980

By J. R. Kunkel, V. Lishnevsky

At mine sites, the operational and required storage volumes of solution and water storage ponds and reservoirs are usually calculated based upon a water-balance approach. Many climatological variables including precipitation, air temperature, solar radiation, pan evaporation and relative humidity along with operating parameters, are used in the water-balance model. The water-balance model often seeks to find a “critical period” of wet or dry climatological sequences which result in a “maximum” pond storage volume or water demand. The problem with this approach is that the designer usually does not know when the project will come on line in relation to the historical record. To avoid this pitfall, we use a more robust approach. In the more robust method, the water-balance calculations begin in each year of the historic climatological record. This method results in the same number of water-balance runs (or realizations) as the number of years of climatological record. Results of this type of analysis guarantee that the critical period or maximum required pond volume will be found if it is assumed that the historical climatological record repeats itself or if a synthetic time series is used. In addition, this method permits calculation of the likelihood (probability) that a given pond volume will be equaled or exceeded in any given month of the operational life of the facility. In this paper, the results of the sizing of a heap leach pad solution pond are presented along with the probabilities of a given solution pond size being equaled or exceeded based on the robust water-balance approach.

Jan 1, 2002

By R. Hedin, M. Dunn

The Pennsylvania Department of Environmental Protection (US EPA 319 program) provided funding to aid a public-private effort in the installation of an environmentally-friendly system to treat abandoned mine drainage at Jennings Environmental Education Center (Pennsylvania Department of Conservation and Natural Resources). Through this cooperative effort among state and federal agencies, mining, excavation, and environmental companies, college and home school students, Girl Scouts, and volunteers, a successful multi-component passive system, readily accessible for upgrades and public education/research activities, was built. 90 people were directly involved in construction of this award-winning system and about 1000 people annually benefit from the educational opportunities.

Jan 1, 2002

By S. Mishra, C. Shon, D. Saylak

Only 40% of fly ash generated by the power plants in US are recycled and used for commercial applications. Of these, the high lime, Class C ash had been preferred. Systematic laboratory and field-scale studies have shown that, by including calcium chloride in the mix design of stabilization of roadbed materials, both Class C and Class F fly ashes can be effectively utilized. Test data reveal that the addition of calcium chloride to the system accelerates its curing rate, thereby increasing early strength and long term durability of the constructed road. For road construction, a preblended Class F fly ash–CaCl2 system tends to be more forgiving than the Class C fly ash–CaCl2 system. The former system produces more durable roads. The role of calcium chloride as an accelerator in these systems is discussed along with a mathematical model developed for fly ash- CaCl2 stabilized roadbed systems.

Jan 1, 2007

By Weiguo Xie, MARK LAPUTKA

The pyrometallurgical industry plays a vital role in producing metals for our modern life. With growing demand of metals and declining grade of mineable ore, innovations become critical for many mining companies. It is necessary to conduct a review of recent improvements to the pyrometallurgical industry on analytical measurement techniques, process and equipment improvements, and computer-based modeling/simulations. Many of those innovations tend to be applied to wider metals, and not be restricted by a specific metal. Therefore, we tried to cover the wide applications of many improvements to wider range of metals to reflect this trend. The challenge of a lack of robust measurement techniques under high-temperature conditions within a furnace hinders optimization of a pyrometallurgical process. Some future opportunities in the pyrometallurgical industry on analytical measurement techniques, computer modeling, and processes and equipment have also been outlined and discussed.

Jan 26, 2021

By Charles A. Gargano

The current state of the mass transit industry in America will be examined. How and why this important urban activity shifted entirely, or almost entirely, from the private sector to the public sector. Who pays for transit? For day to day operating costs? For capital investment? The prospects for transit's future will be the next major issue addressed. In a word, they are rather good. Over the past decade there have been major new transit investments made in Atlanta, Baltimore, Washington, D.C. and Miami, as well as constant re-investment in such cities as New York, Boston, Philadelphia and Chicago. While the current administration has put a temporary halt on the initiation of any major new rail transit projects using Federal funds, there are several mechanisms localities have for using other resources for such projects. These will be explored.

Jan 1, 1983