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By V. D. Hanson

When maintenance of a plant or operation is under discussion immediately three "M's", all in short supply, are brought to mind - money, men and markets. This paper will present what currently is being done at our plants and its effect on the 3 "M's". Examination of coal realization figures (F.O.B. Mine) from 1945 to the present reveals the fact that open and free competition can and will meet market conditions. The industry, without benefit of advantages afforded tax and transportation wise to oil and gas, remains the backbone of the energy market of United States. Figure No. 1 shows the realization figures from 1945 through 1962 compared to the hourly earnings. Note that through 1945 to 1948 F.O.B. prices increased $1.93 per ton while hourly earnings increased $.66 per hour. Since 1948 (with the ex¬ception of 1957) F.O.B. prices have declined $.45/ton, while hourly earnings have increased $1.23 per hour. Basically the maintenance men possibly represent the highest increment rate in the overall hourly earning.

Jan 1, 1963

By G. G. O. O. Uwadiale, M. A. U. Nwoke

The recovery of iron from low-grade (31.6% Fe) Muro iron ore was investigated using reverse anionic flotation of quartz. Tests were performed to investigate the effect of pH, the effects of using distilled vs. tap water as the flotation medium and the effects of using cassava starch vs. dextrin for the depression of iron minerals. The optimum results were obtained around pH 10 and 11, and cassava starch was superior to dextrin in depressing iron oxides. Investigations at pH 11 using cassava starch and distilled water resulted in a concentrate grade of 69.4% Fe with a recovery of 84.4% Fe. Under the same conditions, the use o f dextrin produced a concentrate grade q f 65.9% Fe with a recovery of 78.6% Fe. Investigations at pH 10 using cassava starch and distilled water resulted in a concentrate grade of 60.2% Fe with a recovery of 83.9% Fe, and under these conditions the use of dextrin produced a concentrate grade of 56.1 % Fe with a recovery of 81.5% Fe. Flotation studies conducted at pH 11 using tap water and cassava starch resulted in a concentrate grade of 70.4% Fe with a recovery of 92.7% Fe. This demonstrated the superiority of tap water over distilled water in the reverse anionic flotation process. Investigating the effect of calcium ions on the activation and flotation of quartz with oleic acid revealed that a calcium ion concentration of 50 to 100 ppm was optimum.

Jan 1, 1996

By T. C. Eisele

The use of column flotation was considered for the ?reverse flotation? of iron ore, where the gangue (quartz) was recovered in the froth product. This use of the froth for carrying the gangue mineral rather than carrying the valuable concentrate significantly changes the operational requirements of the column. The objective of this work was to determine which of several column flotation technologies would be most suitable for this type of flotation operation. Studies were carried out using both the Jameson column and the Deister column. Comparative results are presented that show the capabilities of both column types in this application relative to conventional Wemco flotation cells. Columns were demonstrated to have grade-recovery performance superior to what could be achieved with conventional cells. Two-stage flotation with the columns could produce a concentrate that was up to 70.2% Fe at 87.5% iron recovery, compared to 70.4% Fe at only 77.7% iron recovery for four stages of flotation in conventional cells. It was shown to be particularly important to operate the columns to recover a maximum of the quartz gangue into the froth. It was noted that there are often problems in scale-up of laboratory columns to plant scale, because the increase in height and the decrease in the ratio of height to diameter at the larger scale allows more axial mixing and bubble coalescence, both of which degrade the column performance. Horizontal baffling was shown to improve column performance by reducing axial mixing and breaking up large bubbles, and so the use of such baffles in the reverse flotation application was investigated.

Jan 1, 2007

By Robert B. Gordon

The Reverse Curve Tunnel Project was located in Glenwood Canyon, Colorado approximately twelve (12) miles east of Glenwood Springs. The Project was one of many being constructed over a period of time by the State of Colorado, Department of Highways to improve Interstate 70 to four lanes as it travels thru the environmentally sensitive Glenwood Canyon. The Project consisted of excavating and concreting a tunnel approximately five hundred fifty (550) feet long, forty two (42) feet wide, and thirty two (32) feet high. The designer was Parsons, Brinkerhoff, Quade and Douglas, with geotechnical consultation provided by Woodward Clyde. CONSTRUCTION CHALLENGES There were several significant construction challenges presented primarily by the physical location of the Project. In this study each problem will be discussed, as well as how it was overcome by construction methods and/or design requirements. Portal Excavation - One of the most difficult areas of work on the Project consisted of excavation and stabilizing the East and West Portal rock prior to tunnel excavation. The Reverse Curve Tunnel passes through a sheer walled cliff face which is approximately two hundred fifty (250) feet high. Geologically the cliff consists of primarily sedimentary deposits with open, weathered joints and vertical faulting. Before the tunnel excavation could begin, a narrow sliver cut had to be excavated and rock

Jan 1, 1989

By Xinyang Yu

The flotation of diaspore, kaolinite, pyrophyllite, illite and the diaspore-kaolinite mixture were studied with a new cationic organosilicon quaternary ammonium collector entitled QAS222. The acting mechanism of the collector with the four minerals was analyzed by Zeta potential measurement and FT-IR spectrum analysis. The results indicate that the QAS222 was effective in the reverse flotation of the diaspore-bauxite mixture of different Al2O3 -to-SiO2 mass ratios (A/S ratio) at an optimum pulp pH of 11. The potentials of the four minerals increased when they were conditioned in the QAS222 solution; however, the potentials of the three aluminosilicate minerals increased faster than that of the diaspore, especially at pH>9. Furthermore, they were positive in a wide pH range, indicating that QAS222 has a strong adsorption on the surface of the aluminosilicate minerals and thus that these minerals can be floated. The FT-IR spectra analysis further indicates that, besides electrostatic adsorp-tions, formation of the hydrogen bond and ammonium absorptions, chemical adsorptions occur between QAS222 and the aluminosilicate minerals, which allow for the QAS222 to be strongly adsorbed on the aluminosilicate minerals. However, these reactions between QAS222 and diaspore at pulp pH=11 are weaker than those of the aluminosilicate minerals. Thus, surface adsorptions cannot be formed effectively, resulting in reduced floatability.

Jan 1, 2010

By M. Prasad, A. K. Majumder, T. C. Rao

The depletion of high-grade phosphate ores is bringing about a search for a suitable, economically viable technique that con process the abundant low-grade phosphate reserves. About 75% to 80% of the world's low-grade phosphate reserves are associated with carbonate gangue that is not amenable to treatment by the simple techniques of physical separation. The processing of sedimentary dolomitic/calcareousphosphate ore has numerous problems, including similar surface properties of the carbonate and phosphate. Two-stage reverse anionic flotation of carbonates (dolomite/calcite) has appeared to be a promising separation technique ,for the removal of carbonates from sedimentary rock phosphate. In reverse fatty-acid anionic flotation, the depression of phosphate mineral with orthophosphoric acid produces satisfactory results for calcareous as well as dolomitic phosphate ores from several locations of sedimentary origin.

Jan 1, 2000

By D. Bradbury

Sufco coal mine, a subsidiary of Arch Western Bituminous Group, recently purchased a reverse osmosis (RO) system. The systems intent was to remove impurities in the water being mixed with the hydraulic oil to maintain the viability of critical longwall hydraulic systems and to prevent degradation. This project not only ensured hydraulic components from corrosion, but also revealed a cost savings by reducing the percentage of hydraulic oil mixed with the RO water. SUFCO WATER TREATMENT HISTORY Sufco coal mine has been in operation for approximately 70 years. Old works extend up to 15 miles one way, not including adjacent mined out longwall panels. Due to the geologic conditions and strata, water treatment has been as simple as putting water in at a high point of a mined out area and recovering it at a low point to discharge. Doing this reduces the total suspended solids (TSS) to less than 25 parts per million (ppm) and the total dissolved solids (TDS) less than 1,200 ppm which complies with Sufco?s water discharge permit. Even though the requirements for the permit were met, the water is still corrosive in nature. A portion of this water is piped back into the fireline (makeup) water system. It is then boosted to pressures of up to 500 psi to support mining sections, belt systems, equipment, fire fighting systems and the longwall.

Jan 1, 2011

By Chris Howell

PotashCorp?s Aurora phosphate mine, in Beaufort County, NC, operates four low pressure boilers and four high pressure boilers to meet its process steam requirements. Maintaining these boilers is critical to meeting production demands. Processing phosphate ore into phosphoric acid requires large amounts of sulfuric acid and steam. Ore is mined from the phosphate deposit with large bucket excavators after 9 to 30 m (30 to 100 ft) of overburden is removed. The phosphate ore is mixed with water to make a slurry that is pumped to the mill. Elemental sulfur is burned in the presence of air to make sulfuric acid. This process is highly exothermic and boilers produce steam while cooling the process. The phosphate ore is reacted with sulfuric acid and the resulting products are refined into different grades of phosphoric acid for fertilizers, feed stock and food additives. Plant operators at the mine were challenged with boiler feed water that was high in silica and other contaminants. As a result, boiler operations were experiencing difficult, labor-intensive operations and equipment deterioration. This resulted in higher operating costs and diminished processing performance. The facility was operating an aged boiler feedwater pretreatment system that included warm lime softening followed by pressure filtration and a cation/anion/mixed bed demineralizer system. The demineralizer required frequent regeneration and chemical usage was high and costs were difficult to predict. Depressurized well water (DPW water), used for plant utility water and boiler makeup, is very high in silica, in the range of 60-70 ppm. Silica can form scale at pressures below 600 psig. Above 600 psig, silica starts to volatize, carrying over with steam to potentially form deposits on downstream equipment and processes. Mine officials decided to upgrade the boiler feedwater pretreatment system to a state-of-the-art reverse osmosis (RO) membrane system. This new system, which started up in March 2009, has improved operating performance and reduced water consumption and overall operating expenditures.

Jan 1, 2011

By V. Rajaram

A mine fire or roof collapse may necessitate the reversal of main fans to isolate the fire or provide an escapeway. Hence, to assist the mine operator in estimating the flow and pressure during reversal, Engineers International Inc. conducted a laboratory and field study of the reverse performance characteristics of main mine fans. Laboratory tests were performed using a 2.4-m (96-in.) diam vane axial fan to establish the forward and reverse performance characteristics under controlled conditions. Subse¬quently, a field test was conducted in a Colorado oil shale mine during which two 2-m (79-in.) diam fans were reversed. The data obtained indicate that reverse performance characteristics depend on the blade angle and the hub-to-tip ratio. The quantity in the reverse mode ranged from 30% to 65% less than in the forward mode, and the static pressure was directly proportional to the square of the quantity.

Jan 1, 1987

By V. Rajaram

A mine fire or roof collapse may necessitate the reversal of main fans to isolate the fire or provide an escapeway. Hence, to assist the mine operator in estimating the flow and pressure during reversal, Engineers International, Inc. conducted a laboratory and field study of the reverse performance characteristics of main mine fans. Laboratory tests were performed using a 96-inch (2.4 m) diameter vane axial fan to establish the forward and reverse performance characteristics under controlled conditions. Subsequently, a field test was conducted in a Colorado oil shale mine during which two 79-inch (2 m) diameter fans were reversed. The data obtained indicate that reverse performance characteristics are dependent upon the blade angle and the hub to tip ratio. The quantity in the reverse mode ranged from 30 to 65% less than in the forward mode, and the static pressure was directly proportional to the square of the quantity.

Jan 1, 1985

By P. R. Taylor

This work is concerned with the extraction of refractory metals using an electro-reduction process, in which a molten oxide melt, instead of halide, is used as the electrolyte. The process may provide an alternative method of producing refractory metals from their ores through use of a reverse-polarity direct current (DC) plasma arc heating process. In such a process, the plasma torch itself acts as an anode, and resulting liquid or solid product metals work as a cathode, whereas the molten oxide melt plays the role of an electron transfer layer. The focus of this study is: the electro-reduction of scheelite; vanadium pentoxide; and chromite. For the vanadium pentoxide, the proposed melt is mainly composed of CaO-V2O5/Li2O-B2O3-V2O5or FeO-CaO-SiO2-V2O5-Li2O with the addition of other alkali and alkaline metal oxides. In the case of scheelite ore, the SiO2-CaO-Li2O-WO3system is used as melt and metal aluminum or nickel could be used as a collecting media. As for the reduction of chromite ore, SiO2-CaO-Cr2O3-Li2O system with trace amount of CaF2is used as the melt. As a demonstration, chromium was successfully produced at a laboratory scale through the plasma driven electro-reduction process. One of the studied slags had a composition of 13.8% CaO; 4.9%CaF2; 36.4% Cr2O3; 6.9% Li2O; and 38.0% SiO2. Two observations are significant in this laboratory scale study. The first one was that the amount of Cr2O3and FeO, which were predominantly electronic conductors in the oxide melt, greatly affected the conducting mechanism of the melt. With high concentration of Cr2O3and FeO in the melt, the current efficiency was fairly low. In this case, chromium was found to be barely reduced because of electronic conducting mechanism. For example, with initial slag of 60% Cr2O3, no chromium was found reduced. With low concentration of Cr2O3and FeO in the studied melt, typically no more than 30% Cr2O3, it was observed that chromium was readily reduced due to the dominant ionic conducting mechanism. The second observation was that the addition of SiO2tothe melt helped to make the oxide melt more ionic, which was apparently desirable to the molten oxide electrolysis. However, high content of silica had a negative effect on the fluidity of the melt. This was resolved by adding trace amounts of CaF2to the melt. Therefore, by judicious selection of oxide melt, refractory metal oxides might be dissolved into it and yet the melt itself retains the required ionicity. A reverse-polarity DC plasma driven molten oxide electrolysis may prove to be a viable alternative route for the extractive metallurgy of refractory metals.

Jan 1, 2003

In bump-prone coal mines, roof and rib support is subject to dynamic as well as static loading. Although less frequently encountered, the dynamic loading component can result in violent coal expulsions into openings seriously threatening the safety of workers. Dynamic support systems that have been increasingly implemented in many deep hard rock mines for dynamic failure containment have not yet found their adaptation to deep coal mines at desired levels. This paper examines the potential use of some of these dynamic support systems in deep coal mining, particularly in the western United States. Fundamental principles of dynamic loading are reviewed in the context of their application to dynamic failure mechanisms in coal mines. Potential benefits and applicability of the suitable hard rock dynamic support systems are discussed in relation to coal bump mitigation. The resulting insight provides a starting point for development of dynamic support elements for bump prone conditions in deep coal mines.

Jan 1, 2009

By Charles L. Kimbell

Introduction Despite the focus on the so-called "high-tech" and service components of the economy, the minerals industry in 1987 continued to provide the world the overwhelmingly dominant share of the total raw material supply for all manufacturing operations. And, in the form of fertilizers and other soil treatment materials, minerals also supplied indispensable raw materials to ensure continued high production of the agricultural and forestry sectors of the world's economy. Moreover, the role of minerals as a source of construction raw materials was essential to that sector. On the basis of preliminary and partial statistics on world output of crude mineral commodities, 1987 appears to have been a year of further recovery from the recessional years of 1981-1983. The value of world crude mineral industry production (all mineral commodities including fuels) apparently advanced about 5% to nearly $1.1 trillion in terms of constant 1983 dollars.' That is significantly above the recently revised 1986 level of nearly $1.05 trillion, but still considerably below the record-to-date high of $1.27 trillion set in 1980, as shown in Table 1. That growth in value took place despite relatively flat world oil prices - oil being the most important component of the aggregate, as it has been for decades. There is insufficient information available to assess the total value of processed mineral commodities (refined metals, refined oil, manufactured fertilizers and the like). But a figure of $2.6 trillion (constant 1983 dollars) would be a quite conservative estimate for those materials derived only from primary or newly mined materials. And an additional, as-yet-unestimated increment should be added for processed materials derived from secondary raw materials - scrap and other reclaimed substances. From a world trade viewpoint, minerals and mineral products dominate in terms of tonnage. For example, in 1985, on a weight basis, mineral commodities including fuels constituted more than 58% of all goods moving through the Suez Canal and 53% of all goods passing through the Panama Canal. These waterways cannot accommodate giant tankers and ore carriers. So an even larger share of total oceanic trade is composed of minerals and mineral products. Yet, in terms of value, the share of the total accounted for by these industrial essentials is much lower than that accounted for by other commodities, most notably sophisticated high-tech equipment and other goods with a relatively high per-pound value. Worldwide data on the value of mineral export trade for 1987 is so incomplete at this writing that it is impossible to assess that actual level. Indeed, the compilation of similar available data for 1986 covers only the exports of nations with developed market economies. In 1985, these countries accounted for only 67% of total world exports of all goods. They accounted for only 41% of world exports of major mineral commodities: crude nonmetals; metal ores, concentrates, and scrap; mineral fuels; nonferrous metals excluding gold; and iron and steel. For these developed-market-economy countries, the value of exports of these major mineral commodities declined by more than 10% between 1985 and 1986. Most of the shortfall came as a result of a 26% drop in the value of fuels exports. If these patterns of

Jan 7, 1988

By Charles L. Kimbell

The year 1988 for the minerals indus¬try was one of favorable worldwide economic conditions for continued, rationally constrained growth. There was continued improvement in relations between market economy nations and the Soviet Union and China. The "shooting war" between Iran and Iraq ended. Soviet troops withdrew from Afghanistan. And conditions were generally favorable for economic growth in developed market economy countries. These favorable conditions were darkened only somewhat by the continuing foreign debt crises discernible in some major mineral producing developing market economy countries. However, there were situations developing that became major headlines in the late spring - situations that may have pronounced effects in 1989. The most significant event is the muddled situation in China. There is a good chance of worsening international relations and consequent restraint of development projects that could prove beneficial to China and her international partners. Of only slightly lesser evident significance was the death of Ruhollah Khomeini in Iran. This could lead to a variety of paths for the new Iranian leaders. Continued outbreaks of ethnic unrest in the Soviet Union clearly presented problems to the Gorbachev regime. This unrest has raised questions of how far the doctrines of "glasnost" and "peristroika" would be extended, including extensions into the minerals field. Another area of unrest is Panama with its tainted election and the Western Hemisphere's obvious dissatisfaction with the Noreiga regime. While not a direct threat to any major mineral industry enterprise, the political situation certainly presents a potential threat to the Panama Canal. That threat would have considerable impact on world

Jan 1, 1989

By Charles L. Kimbell

In 1989, worldwide total mineral industry activity registered advances from 1988. The advances may not have been as noteworthy as in 1988, but they can be regarded as a worthy theme for this article. The momentous political events throughout the centrally planned economy world had only a modest impact on actual 1989 industry performance. But these events have such potential for worldwide changes in economic activity in future years that they dwarf the actual happenings of 1989 in the minerals industry. Perhaps most significant factor here is the rapidity with which these changes have occurred. The end of World War II saw the almost immediate division of the world into major economic blocs. Since then, mineral industry activities and other industrial operations have been governed, to a considerable extent, by this partitioning. The developed market economy nations have operated as a group, the centrally planned economy states as another group. And these two groups essentially have vied for recognition in mineral industry operations in the developing economy states of Asia, Africa, and Latin America. The boundaries of these country blocs were fixed in the late 1940s and early 1950s. They were not markedly altered in the ensuing 40 years. We have seen the establishment of the Organization of Petroleum Exporting Countries, the continued Arab-Israeli confrontations in the Near East, the upheavals surrounding the rise of Moslem Fundamentalism in Iran, and the establishment of Soviet-oriented governments in Cuba and Nicaragua. These events have had notable effects on the world economy. But they have done little to change the pattern of market economy states functioning as a competitive bloc with the centrally-planned economy countries.

Jan 1, 1990

By B. C. Darst

Intensive efforts to develop potash use in agricultural production were begun in the US 50 years ago. Early growth was rapid and continued well into the 1960s. Many soils were inherently low in K, so crop responses to fertilization were often dramatic. Deficiency symptoms were common. Per-acre use has continued to increase in recent years, but annual growth rates have slowed. Soil buildup has occurred in some areas. Poor economics in the 1980s have been difficult to overcome. Efforts are now well under way to develop potential markets around the world.

Jan 1, 1987

By W. J. Wuest, M. J. DeMarco

The US Bureau of Mines (USBM) recently developed a rock-mass classification system for evaluating the structural competency of bedded roof strata. The system is called the coal-mine roof rating (CMRR), When compiled with the companion Lotus 1-2-3 spreadsheet, CMRR data are a useful tool with applications to longwall gate-road pillar design, safety-hazard mapping and artificial roof-support analysis. This paper gives a review of some applications under actual conditions found in current US mining operations.

Jan 1, 1997

By S. Saeb, C. Francke

Introduction Although mining in one form or another has existed for millennia, the use of numerical methods for mine design is a relatively recent development. The basic physics that control the behavior of rock or soil have been known for centuries, but it wasn’t until the last half of the twentieth century that analytical methods that could accurately predict the behavior of a large, irregular rock mass were developed. Before the advent of modern computers combined with differential and integral analytical methods, numerical methods available to mining engineers were limited to closed form solutions for simple excavation geometries. Today, mine-scale three-dimensional stress analyses can be performed on a relatively inexpensive personal computer. Many of the recent advances in rock mechanics modeling are the result of research funded as part of nuclear waste repositories around the world. The large scale exacting performance requirements of waste repositories are frequently very different from traditional rock mechanics projects. These facilities are designed and built under tighter control and scrutiny because of the potential hazards they present to the public. Therefore, a great deal of research towards advancing rock mechanics and numerical modeling resulted from these projects. Much of the repository research is applicable to commercial mines. The advances in modeling programs have been paralleled by advances in computer equipment. Today, a moderately equipped personal computer can handle most mine geomechanical modeling projects in a reasonable period of time. While the learning curve varies, an engineer with modeling experience can develop a medium sized model in a few days. The relatively low investment cost of geomechanical modeling today makes it accessible to most mining operations. The benefits of a solid geomechanical modeling program include reduced operating costs, improved safety, and reduced design costs.

Jan 1, 2007

By Shibo Zheng, Zhengxing Gu, Zhizhong Gao

In recent years, beneficiation tests were conducted on high dolomite phosphate samples from Florida by the authors from China Lianyungang Design and Research Institute (CLDRI). The research results indicated that flotation is the most effective process for recovering phosphate from Florida high dolomitic pebble. Other operations like scrubbing, desliming and selective grinding might work to some extent, but they could only be applied as supplementary approaches in some cases. Heavy media separation and calcination-digestion technologies are hard to produce satisfactory performance. This paper presents the results of both lab scale and pilot plant tests on Florida high dolomite phosphate pebble using the fine particle flotation technology developed by CLDRI. Some discussions are made on the concerns of Florida phosphate industry and further research.

Jan 1, 2002

By William B. Schmidt

In July of 1974 a study team comprised of the authors was formed by the Department of the Interior. It was supported in part by funding from the National Science Foundation. The purpose of this study group was to visit coal mines and research and manufacturing facilities in England and Germany, to review the status of mining in these countries, and to identify mining technology which might have application to U. S. mining conditions. The duration of the visit was 18 days. The first week of the trip was spent in England. Time does not permit a complete recitation of the team's impressions but a few of the more interesting technologic developments will be discussed. These fall into the following categories- High Speed Development Ground Support Chainless Haulage and Face Conveyors Nucleonic Steering of Shearers Miscellaneous

Jan 1, 1975