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By J. Murray Riddell, Arthur E. Anderson, Grover J. Holt

Out of the depths of each business cycle we emerge with a stimulus for greater efficiency and a realization of progress in industrial technique. The recent years have not been an exception to this rule, and in retrospect we sense that significant advances have been made in mining practices on the Mesabi Range, with emphasis on speed of production and economy of operation. A survey of such changes does not reveal anything that is fundamentally or basically new, but it is apparent that ideas and machines that have found wide application in industry elsewhere, with necessary modifications, are being put to productive use in mining iron ore. Innovations in transporting and conveying ore from the open pits stand out with greatest prominence, so that, in the main, it will be with these features that this paper will treat, in the review of progress made to this date. The late years have witnessed the development of small deposits for open-pit operation, the cleaning up of pits nearing exhaustion, and in two large operations the approach to the limit for haulage by steam locomotives, owing to grades, making it necessary to recover the ore in slopes, track benches and below the power-shovel limit by a milling and scram operation. For several years small standard-type dump trucks have been used in clean-up or scram operations within the pits, but during the season of 1936 the first effort was made to use heavy truck haulage in the transportation of stripping and iron ore. The new units in use today vary from 15 to 20 tons in capacity, and are equipped with powerful gasoline or Diesel engines and supplemented by trailers or wagons on rubber or crawler treads. The Diesel engine finds favor with most operators because of fuel economy. These units develop upward of 125 hp. in the 15-ton trucks. The speed of these trucks varies from 2 miles per hour in Pow gear to 35 in high gear. The transmission affords 12 speeds forward and 3 speeds in reverse.

Jan 1, 1940

By C. Kremer Bain

DURING the past several years of diamond drilling in Washington County, Mo., the St. Joseph Lead Co. has discovered a concentration of commercial lead-zinc ore at four different points within an area of 36 square miles. The largest and to date the most promising group of these orebodies is located in the Indian Creek area. It was considered to be of sufficient value to warrant development. The Indian Creek area is in the center of the northern half of Washington County, 11 miles northwest of Potosi, Mo., the county seat. The location is readily accessible from Potosi by car or truck over the all-weather Missouri State Highway No. 114. The topography is one of rolling relief, varying from an elevation of 700 ft above sea level on Mineral Fork and Indian Creek to a maximum of 1176 ft at High Point Tower. It is divided in equal halves between the drainage to Mineral Fork and to Indian Creek. The shaft site at 1060 elevation is on the divide between the two drainage areas. The Indian Creek side is rough and heavily wooded, with only a few cultivated clearings. The slopes to Mineral Fork are more gentle and rounded, with much of the area cleared for farm land. Most of the surface is covered with Potosi and Eminence formations, which show little evidence of any structure. Ore structure was worked out by extensive diamond core drilling, with holes varying in depth from about 700 to 1300 ft. As of Oct. 1, 1950, 218 prospect holes had been drilled within the 36-square mile area. The ore is disseminated galena with considerable accompanying sphalerite in the Bonne Terre forma-tion in the shape of irregular blanket-type deposits. The main controlling structural feature of the outlined mineral zone is a buried pre-Cambrian rhy-olite-porphyry ridge extending partly through the Bonne Terre formation, which laps against the por phyry and also covers it. The mineralized zone parallels and forms an irregular halo around the porphyry ridge and is concentrated in the Bonne Terre formation where the La Motte sandstone is cut out by the porphyry ridge. This is a very common mineral occurrence in the southeastern Missouri lead belt district. The La Motte sandstone, which normally underlies the Bonne Terre formation, is thus cut out entirely. In this area the Bonne Terre is usually about 275 to 320 ft thick, the La Motte varying in thickness from zero up to 400 ft. Commercial concentrations of ore are indicated at several places, the most notable being at the shaft site where an orebody at least 4000 ft long with widths of 500 to 600 ft has been outlined. The total thickness of mineralized rock reaches 150 ft in some holes, although total ore thickness runs from 8 ft to about 60 ft, often in more than one layer. Preliminary Planning Ore reserves as outlined lend themselves to open-stope mining with trackless haulage and mobile loading machines and drilling equipment. This type of equipment has proved to be very efficient during recent years in the company's lead belt operations. After a study of bids for shaft sinking and an estimation of comparative costs, it was decided that the shaft would be sunk by St. Joseph Lead Co. personnel using company equipment. Since the plant site is about 26 miles from the company's nearest lead belt operations, it was necessary to plan a complete surface plant, including mill, shops, office, change room, and warehousing facilities. Immediately following the filing of an application for a certificate of necessity, a headframe was selected for which detailed drawings were already available. The order was placed for fabrication so that it could be delivered and erected in time to serve for sinking the shaft. This eliminated the expense of a temporary headframe. Drilling was started on two churn drill holes near shaft location, and two 1000-gpm deep well pumps

Jan 1, 1954

By R. F. Shurtz

R. Duval (Mining Engineer, Ancien eleve de PEcole Polytechnique, Paris, France) I do not agree with the Eq. 3, reading: m =1/100- [(0.214x30.4) + (0.7B6 x0.00)] =6.5pct CaO If 0.214 and0.786 were proportions by weight, the equation would represent the well known mixtures law of the conventional arithmetics and 6. 5 pct CaO would be the correct average content. But it is not the case as the author states: "In samples consisting of single grains of mineral, those grains must, as already mentioned, be either of dolomite or magnesite. Since 78.6 pct of the deposit consists of magnesite and 21.4 pct of dolomite (excluding for present purpose the presence of other minerals), for any single grains picked at random the probability will be 0.214 that is it dolomite and0.786 that is it magnesite. In 1000 such samples the expected numbers of dolomite and mapesite grains will be 214 and 786 respectively." 0.214 and 0.786 would be proportions by weigbt under the necessary condition that all grains of dole mite and magnesite should have an identical weight. Obviously it is not the case, as the specific gravities are not the same for mapesite and dolomite and the volumes of the grains are different. Furthermore, because of these differences the conditions for a random sampling are not fulfilled and we are not authorized to state that the probabilities are, respectively, 0.214 and 0.786. The author however makes a simple application of Eq. 1: M = 1/n— ? fi x i . n Should we deduce that this relation is wrohg? Not at all, but when applying Eq. 1 you must not overlook what it actually. means. Eq. 1 gives a definition of the arithmetic mean of a total of n observed values Xi and nothing else. But the average conteht of a deposit has not the same significance. It is the ratio between the weight of concerned mineral in the deposit and the total weight of the deposit. As from 1000 particles the 214 of dolomite and the 786 of magnesite have not the same weight, the two definitions do not concur, and when applying Eq. 1 the result is an arithmetic mean of figures which has no connection with what is named average contentof a deposit. The situation is similar to the calculation of an average velocity. If a car travels a first mile over at 30 miles per hr and a second mile over at 60 miles per hr, when applying formula 1 you find as average velocity for the 2 miles: 30+60 ------- - 45 miles per hour. Many people calculate in this way and they do not realize that a mistake is involved. In fact the definition of he average velocity for the 2 miles is the quotient of the distance of 2 miles by the time (in hours) necessary for 2 miles travel, i.e.: 2 ---------- = 40 miles per hr. 1 + 1 30 60 In other words, the average volocity wanted is not the arithmetic but the harmonic average of the two velocities. The above mentioned bias in the calculation of the average contents of deposits is frequent, even in the assessments made by experienced engineers and is independant of what is named the sampling error. In order to supress the bias and to be able to use Eq. 1, you must apply a correction. An example on the subject can be found in an article by Duval et al. in the January 1955 issue of the ''Annales des Mines" (French), page 19. R. F. Schurtz (Author's Reply) Mr. Duval's position is quite correct. The proportions shown for dolomite and magnesite., respectively, of 0.214 and 0.786 are, in fact, proportions by weight uncorrected for specific gravity. In our day to day operation of producing magnesite from these mines at a very substantial rate, we do not normally make corrections for the difference between the specific gravity of dolomite and that of magnesite. If these corrections are made in Eq. 3 as shown in my article, then the numbers of grains turn out to be in proportions of 0.226 dolomite and 0.774 mapesite instead of the values actually shown in the equation. For the purposes of our work, and in view of the inherently low accuracy of the data, this correction was not deemed worthwhile making.

Jan 1, 1961

By John M. Kelly

New Mexico produced 31,913,816 bbl. of oil in 1942, the lowest annual production since 1936, and dropped one place to rank eighth among oil-producing states. This production decreased 7,838,052 bbl., or 19.71 per cent, from the 1941 figure is the result of transportation difficulties caused by the dislocation of tanker sailings to east coast ports. The average per-well allowable in New Mexico on Jan. I, 1942, was 43 bbl. and at the end of the year was 38 bbl. Allocations as set by the New Mexico Oil Conservation Commission followed the recommendations of the Petroleum Administrator for War. After setting the daily outlet, however, the average daily pipe-line runs were 87,545 bbl.—11.06 per cent short of these allocations. Production for Lea County was 26,812,949 bbl., Eddy County 4,624,578 bbl., northwestern New Mexico 473,609 bbl., Chaves County 2,680 barrels. Drilling activity for New Mexico in 1942 was approximately 84 per cent of that in 1941 with 339 completions. Of these completions 254 were oil wells, II gas wells, and 74 dry holes. Proven fields accounted for 55 of the dry holes and 19 were wildcats. Three new oil fields and one new gas field were discovered as the result of wildcat drilling. Extensions were made to one oil field and one gas field. By the close of the year, the New Mexico Oil Conservation Commission had designated 59 areas as proven for oil and/or gas. Southeastern New Mexico Lea County Monument was again the largest producing field in the state, with 5,729,336 bbl.; Eunice was next, with 5,217,965; Vacuum produced 3,295,624 and Hobbs 2,973,488. The Hobbs field has the largest accumulated production, which at the close of 1942 totaled 100,381,417 bbl. The 100-million-barrel mark for Hobbs focused attention on the fact that this is the first field in the state to attain this figure, and also that, as Hobbs has been under continuous proration since July 1930, or approximately the entire life of the field, this 100-million-barrel recovery was obtained with 86 per cent of the wells in the pool still flowing and having a drop in bottom-hole pressure of only 3.5 Ib. per million barrels recovered. Hobbs stands out as perhaps the best regulated major oil field in the world. Two new oil fields were discovered in Lca County, the most inlportant being the area designated as East Lusk, consisting of the south 4 tiers of Sections in T. 19 S., R. 32 E. The discovery well was drilled in the SW. SW. 1/4 of sec. 21, T. 19 S., R. 32 E., by Culbertson and Irwin, Inc., and others. It was completed at a total depth of 2751 ft. in the Seven Rivers formation of Permian age. The initial potential of the well was 237 bbl. per day on pump. The oil produced has a gravity of 24.10 A.P.I., with sulphur content of 0.9 per cent. This oil has an asphaltic base and because

Jan 1, 1943

By G. S. Scott

In the course of the investigation into the causes, behavior, and control of mine fires, which the Bureau of Mines is now conducting, some attention was given to the subject of spontaneous heating. It is self-evident that the temperature of a pile of broken coal will rice if the rate of generation of heat exceeds the rate of brat dissipation and will fall if the opposite is the case. Factors that affect the rate of generation of heat are:

Jan 1, 1941

This paper has peen translated from the Russian by the United States Bureau of Mines and is issued as one of a series of circulars dealing with mining methods and costs in connection with a general study of this subject sponsored by the bureau. The paper presents some interesting features in connection with the methods employed in Russia and describes certain variations in standard methods which might conceivably be applied to a limited extent in this country.

Jan 1, 1930

By J Law, S Jahanshahi, R Holmes

Iron ore is AustraliaÆs largest commodity export and is vitally important to AustraliaÆs current and future prosperity. However, while major expansions are currently in progress to satisfy demand, the industry is also undergoing major transformations. Reserves of traditional high-grade Brockman ores that have underpinned the Australian iron ore industry since its inception are slowly being depleted and alternative ore types such as Marra Mamba bedded iron deposits, Yandi and Pannawonica channel iron deposits and magnetite deposits are now being developed. However, the impurity levels in some of these alternative ores are higher and they require blending and/or upgrading as well as an advanced knowledge of their downstream processing characteristics to facilitate cost-effective utilisation by overseas customers. The research challenge is to use advanced techniques for mineral exploration, ore characterisation, mineral beneficiation, agglomeration and sustainable processing to identify and develop innovative and breakthrough options for locating, unlocking and enhancing the value of AustraliaÆs iron ore resources. Furthermore, to sustain the steel industry and hence secure the demand for iron ore, there is a growing need to enhance the environmental and business performance of the industry through reductions in wastes and emissions. Therefore, cost-effective breakthrough and enabling technologies that massively cut waste generation, CO2 emissions and water consumption are also being developed. These include the use of renewable fuels and reductants, waste heat recovery and conversion of by-product slag into a saleable substitute for Portland cement. A number of examples of recent developments in the above areas are provided in this paper.CITATION:Holmes, R, Jahanshahi, S and Law, J, 2013. Research and innovation for the iron ore to carbon steel value chain, in Proceedings Iron Ore 2013 , pp 3-6 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By D. Harrington

A uniform hoisting-signal code for mines hoisting from more than one level, if adopted by all mining States, would be beneficial to employees and owners alike and should largely reduce the number of hoisting accidents. Misunderstood hoisting signals cause many shaft accidents involving injuries to men, damage to equipment, and loss of production from the resultant delay. Many of the metal-mining States have adopted codes for hoisting that are effective within the borders of that State but usually entirely different from the signal code, if any, in use in an adjoining State. For many years safety engineers have recognized this lack of uniformity as a distinct hazard, but a uniform code has never been adopted by the States or by the mining industry in those States that have not incorporated signal codes in their mining laws or mining regulations.

Jan 1, 1944

By Earle S. Burnett

This report outlines the experimental procedures for using a Burnett apparatus to obtain compressibility coefficients for multiphase, multicomponent fluid mixtures. The conventional Burnett method is described briefly whereby multiphase compressibility data can be obtained by first determining the compressibility factor, Z, as an isothermal function of pressure alone. Then starting at conditions of temperature and pressure where Z is known, the fluid is cooled at constant volume to some lower temperature at which the resulting pressure is measured, and a corresponding value of Z is obtained from a fundamental relationship between compressibility factors, pressures, and temperatures at constant volume. The isochoric treatment of the fluid, extended to still lower temperatures and along other isochors, eventually results in compressibility determinations for the whole two-phase system thus covered experimentally.

Jan 1, 1963

By Maurus Seet Hong Hua

Introduction Coal has always been China's predominant energy resource. The country ranks among the three richest countries in coal reserves in the world, next to the US and the Soviet Union. According to China's Ministry of Coal Industry (MCI), coal accounted for about 72% of the total national energy consumption. Despite efforts to increase the output of oil and hydropower, coal is predicted to remain dominant on the energy scene by increasing its share to 77% by the turn of the century. To match the rapid growth in the agricultural and industrial sectors, MCI has targeted the coal industry to double coal output from 600 Mt/a (660 million stpy) in 1981 to 1.2 Gt/a (1.3 billion stpy) by the year 2000. How is this goal to be achieved? According to MCI, it will be accomplished by: • building new underground and surface mines with a total output of 400 Mt/a (440 million stpy); • increasing the output of existing state-controlled mines from the present 344 Mt/a (368 million stpy) to 400 Mt/a (440 million stpy); and • developing and increasing the output of small, local mines run by province, county, and production brigade from the present 276 Mt/a (304 million stpy) to 400 Mt/a (440 million stpy). Building new underground and surface mines New underground coal mines will be developed in areas where the coal industry has already made headway and infrastructures currently exist. This is to optimize hardpressed capital spending on investment. Ten existing coal production bases were selected in nine different provinces that met these requirements. The underground mines scheduled to be constructed in stages at he existing coal production bases will have a total output of 200 Mt/a (220 million stpy) by the end of the century. Regarding surface mines, four mines in the Inner Mongolia Autonomous Region and one in Shanxi province have been earmarked for construction during the same period. By the year 2000, these surface mines are expected to produce 200 Mt/a (220 million stpy). Foreign equipment, machinery, and surface mine stripping technology were all involved in different degrees in the development of the five new surface mines. Some have signed joint venture agreements. Occidental Petroleum Corp. is in a joint venture with China in developing Ping-shou's 15 Mt/a (16.5 million stpy) Antaibao No. 1 open-pit. The Shentou power station, situated nearby, is anticipated to consume 3.2 Mt/a (3.5 million stpy) of the coal it produces. Some is designated for export. Increasing output There are 554 state-controlled mines that have been in operation since before 1980. They produce 344 Mt/a (379 million stpy). To increase capacity, MCI has laid out some guidelines. • Coal prospecting near existing mines must be given top priority and intensified so that workable reserves can be increased. This would lengthen the mines' useful life. • Many mines and slopes that were constructed during the 1950s are very small and densely populated. These small mines and slopes are generally very short along the strike. As a result, coal faces and levels require frequent

Jan 3, 1986

By D. Imeson, T. Grammatikopoulos, G. Pearse, M. Aghamirian, C. Mohns

"Spodumene mineral is a source of lithium for lithium ion batteries. Thus, the production of a spodumene concentrate with an approximate grade of 6% Li2O is targeted. Traditionally, spodumene is concentrated by froth flotation using fatty acid as the collector. Amine collector can also be used to float mica ahead of spodumene as required or feldspar from the spodumene tailings. Slimes have a negative effect on spodumene flotation and they are commonly separated by scrubbing and de-sliming prior to spodumene flotation. The main losses in spodumene flotation typically occur in cyclone overflow, scrubbing slimes, spodumene flotation tailings and mica concentrate. In recent years, dense media separation (DMS) is the main concentrating process in Australian spodumene operations. In these operations, DMS is efficient at generating coarse grain concentrates and rejecting large portions of silicate gangue, thereby directly reducing the milling cost. The ore should be crushed to 3/8” or coarser while further crushing is possibly necessary on the middling particles to scalp further spodumene. The DMS feed should be classified to remove fines (typically -0.5 mm particles). The final middlings and undersize fractions could then be processed by flotation. The main requirement in DMS operations is to have good spodumene liberation at relatively large grain size. This paper reviews the most significant DMS and flotation parameters in spodumene beneficiation. The treatments of different minerals in the spodumene ore are also addressed.INTRODUCTION A number of laboratory/pilot plant programs have been recently conducted at the SGS Lakefield site, sponsored by different clients. The main objective has been to develop a process flowsheet to generate a spodumene concentrate containing 6.0% or higher Li2O (~75% spodumene) suitable for producing lithium carbonate by a hydrometallurgical process. Depending on spodumene liberation size, dense media separation (DMS) can be an attractive option to produce a final high grade concentrate and to reduce the mass to be treated in the flotation circuit. In such a case, crushing would typically be performed in stages, with DMS separation to recover a spodumene concentrate and reject gangue minerals following each stage. DMS middlings and -0.5 mm fines can be processed by flotation to further recover spodumene. In the flotation process, coarse stage grinding minimizes the grinding cost and formation of slimes. In the majority of cases, a grind size (K80) of approximately 200 microns is sufficient for flotation. After primary grinding, mica, if present in an appreciable amount, should be floated to minimize interference with spodumene flotation. Desliming after scrubbing and high density conditioning are the key process operations prior to spodumene flotation. Spodumene can then be floated from silicate gangue minerals with a fatty acid or a mixture of fatty acid and petroleum sulfonate at slightly alkaline pH. Subsequently, feldspars can then be floated from the spodumene tailings."

Jan 1, 2012

By A. F. Neil, A. S. Bahaj, P. Watkins, P. M. Hyslop, C. E. Kirby, P. A. B. James

The results of initial work indicate that for 3 of the 5 quarry sands bioleaching reduces the iron oxide content to a commercially acceptable 0.035 wt% Fe20 3, although the time taken to achieve this is 14-22 days against a target leach time of 7 day. Subsequent work has identified strains of Aspergillus niger that are more efficient at producing the array of complexing agents for iron and is yielding excellent and rapid reductions in Fe levels. Potentially, bioleaching offers a more environmentally friendly and energy-efficient process for the removal of Fe from glass-making sands than conventional routes but the production of organic acids by fermentation must be achievable with low-cost substrates such as sugar-beet molasses and lactose permeates for bioleaching to offer a commercially viable alternative to treatment with hot mineral acids. Silica sands usually contain three groups of Fe minerals: iron oxyhydroxides, which comprise crystalline types such as goethite and limonite tending to occur as thin, discontinuous coatings and in cracks and crevices on the surface of the quartz; the assemblage of heavy trace minerals, which include ilmenite, rutile, leucoxene, chromite and haematite, commonly present at levels of 0.1 wt% or less as discrete grains or sometimes cemented to the quartz; and clay minerals cemented in pits on the surface of the quartz and in association with weathered, discrete feldspars. The response of the assemblage of iron minerals to short periods of exposure to hot inorganic acids is broadly related to which group they belong to, those that form coatings being accessible to acid and tending to react rapidly whereas the trace minerals are usually resistant and react very slowly, if at all, and the clays are probably digested. The note reports on a preliminary study of the use of microorganisms to develop an alternative clean technology that will give results comparable to those achievable with hot inorganic mineral acids but with more environmentally acceptable procedures. Various fungi and bacteria produce organic acids when grown in certain media. When these acids come into contact with Fe-stained sand grains the iron is removed as soluble complexes. Several strains of Aspergillus niger have been found to produce organic acids from sugar, predominantly citric, gluconic and oxalic acids, their relative yields depending on cultivation medium and conditions. Sand samples were prepared from five quarries in the UK: Levenseat, Lothian; Redhill, Surrey; King's Lynn, Norfolk; Chelford, Cheshire; and Oakamoor, Staffordshire; ranging in iron oxide content from 0.035 to 0.153 wt% Fe203

Jun 18, 1905

By V. P. Bystrov

Vanyukov process has been developed and investigated in Russia over the last 25 years. It has been established that various kind of material could be treated in Vanyukov process. The results of the pilot plant trials as well as industrial experience are presented in this paper.

Jan 1, 1993

By Joseph D. McClung, L. G. Austin

INTRODUCTION Run-of-mine (ROM) coal generally falls into two major groups, that from underground mining (continuous mining machines) and that from strip mining. Continuous miners produce a finer product and strip mining a coarser product that is crushed to produce the desired size. Further size reduction depends on the proposed use or uses for the coal. For example, for pulverized coal power plants as a rough general rule, the coal is ground or pulverized to 80% less than 200 mesh (0.075 mrn) before it is blown into the boiler furnace as a coal-air suspension. For solvent-refined coal processes, the desired size is about <30 mesh ( <0.60 mm) ; in fluidized bed uses, the coal is typically < in. ( < 1.6 mm); for Lurgi pressure gasifiers, the desired size is 1-2 1/2 in. (25-63 mm). Coal preparation plants typically work with a coarse size fraction of 6x1 1/4 in. (15Ox32mm). It seems probable that the next decades will see much wider application of coal cleaning before use and that the stages of crushing and pulverization from ROM coal to end use will be integrated with coal cleaning processes. Since different cleaning processes work better with different ranges of coal size and the degree of cleaning possible is inti-

Jan 1, 1979

By Ming’an Wei, Qifu Duan, Jianmin Wu, Lusheng Zhou, HMR Group Limited / HMR Technology Canada Ltd., Wenjian Wu

"The development and industrial applications of magnetic liners have been around for decades. A Swedish company Skega first introduced rubber magnetic liners, and then followed by the Chinese invention of metal magnetic liners. Traditionally, both liners were used in secondary ball mills and regrind ball mills for industrial applications, especially for ores containing magnetic materials. Mostly steel balls or equivalent forged steel balls, usually below 60 mm in diameter, were used as grinding media. With the development of mineral resources over the years, SAG mills and larger ball mills have become the dominating components for comminution circuit design. Due to the development of larger diameter ball mills and thus larger ball charge diameter (up to 80mm) especially in non-ferrous metal mining operations, the application of magnetic liners have been very limited. Based on “Magnetism theory” and the development of new materials, the HMR Group Limited has been conducting researches on examining the structures of magnetic liners, associated materials and magnetic circuits which led to the invention of the Nano Alloy Steel Magnetic Liner (NSML). Recently, NSML had a successful application in a 5.5 m diameter × 6.5 m ball mill at the Erdenet Copper Mine in Mongolia. The NSML successfully handled a ball size up of to 80 mm, while achieving a service life of nearly 24 months, which is almost 3 times wear life of the original manganese steel liners.INTRODUCTIONDuring the development and utilization of mineral resources, mineral processing is an indispensably operation. The effective separation of various useful minerals depends on sufficient monomer dissociation of minerals in the ores. The crushing and grinding operation is prior operation of mineral processing. Ball mills are used in different concentrators. As the main consumption parts of mill, liners have been studied constantly. As a new kind of liners, magnetic liners besides can meet the requirement of production, and also have characteristics with maintenance-free, saving energy and increasing efficiency. So the magnetic liners are worth to be spread and applied world widely."

Jan 1, 2016

By Jasper L. Stuckey

PYROPHYLLITE, first identified as soapstone,&apos; later as agalmatolite,2 and finally as pyrophyl-lite, has been known to occur in North Carolina for more than 130 years and has been produced intermittently in commercial amounts for the past 100 years. Pyrophyllite mining, however, has become a major industry in North Carolina only during the past 25 years. North Carolina and California are the chief producing states. Current annual production averages 125,000 tons, of which slightly more than 90 pct comes from North Carolina. Distribution and Geologic Setting: All known pyrophyllite deposits in North Carolina are associated with rocks of the Carolina Slate Belt,&apos; which is composed of a vast series of metamorphosed volcanic and sedimentary materials, occurring as two zones extending in a northeast-southwest direction across the state. The larger of these zones, lying in the central Piedmont region, varies from 8 to 50 miles wide. The smaller zone lies along the eastern edge of the Piedmont region and is partly covered by coastal plain sediments. The rocks in both zones consist of a great volcanic-sedimentary series, composed of air-laid and water-laid tuffs and breccias, lava flows, and slates. On the basis of composition, they may be classed into three groups: 1) tuffs, breccias, and lava flows of acid or rhyolitic composition; 2) tuffs, breccias, and lava flows of a basic or andesitic composition; and 3) water-laid slates composed of fine grained materials derived chiefly from the acid tuffs and breccias and

Jan 1, 1959

By R. M. Kear

Strategic and tactical planning are both required in the mining industry but have completely different objectives and require different environments. If these are not fully understood, then the best value for a mining operation may not be realized. This paper examines the differences in these approaches and how they interface in the mining environment. The objectives, content, skills required and the implied management issues for these two components are examined with the hope that this will assist management and the planning teams in defining their respective roles and expectations. The opinions are those of the author based on his experience on several mining operations and projects.

Jan 1, 2006

By Philip Thompson

Many new evaluation tools have been developed since the early 1990’s to aid the minerals processing test engineer. The areas of comminution, gravity concentration, flotation, and process mineralogy have received particular attention. This paper will describe new laboratory procedures in the areas of SAG mill testing, gravity concentration, and flotation testing. Computer assisted mineralogical examination equipment, new generations of mass balancing programs, and simulation programs will also be discussed.

Sep 12, 2005

By Klaus-Dieter Beck

RAG American Coal Holding, Inc. affiliates operate two longwall mines in the Pittsburg seam in Pennsylvania, the Cumberland mine and the Emerald mine. A unique situation in longwall operation occurred at these mines as the mining activities reached the property boundary between the two mines. The retreat direction in the longwall panel in Cumberland mine is West-to-East while in Emerald mine, it is East-to-West. This unique condition required an adequate design for barrier pillar between the two mines to minimizing the mutual effects of longwall retreat when both longwall faces met and an adequate roof control plan for gateroads. Field studies that involved mainly roof-to-floor convergence monitoring were conducted to assess the effectiveness of the employed barrier pillar in isolating the mutual effect of longwall retreat. Three-dimensional finite element numerical modeling was used to evaluate the gateroad roof and pillar stability. The modeling was conducted such that it duplicated the actual mining process as realistically as possible. The modeling results predicted that the employed barrier pillar and the roof control plan would ensure stable gateroad systems in both mines during and after the two longwall faces met. The prediction was confirmed because mining operations in the two longwall panels were completed without any noticeable ground control problems.

Jan 1, 2004

By D. H. Zellers

Since its inception the United States Bureau of Mines has fostered the development of portable mine lamps. Although there is still much to be desired with respect to illumination in coal and metal mines and the replacement of open lights has been slow the Bureau has been given credit for assisting materially in the development and introduction of the safe and efficient portable mine-lighting equipment available today. Much of the work conducted by the electrical section of the Bureau entails approval tests of various types of electrical equipment, including lamps; to be used in atmospheres that may contain methane or coal dust in explosive proportion. If a can lamp meets the requirements-for safety, efficiency, and adequacy, as published in Schedule 6B,4 it is approved and is generally known as a "permissible" lamp. The terms "approved" and &apos;"permissible&apos; often are used interchangeably. The manufacturer must put an approval plate on each approved lamp, showing it has mot the schedule requirements. The approval plate is not a guarantee that the lamp is safe. However, if the lamp, once in service, has not had any parts changed or improperly assembled or if carts that wear out or depreciate have been properly replaced it should still, be safe, efficient, and adequate for the service intended. Virtually all electric cap lamps in service today in the United States and a great many that have been sent to foreign countries bear the approval plate of the United States Bureau of Mines. Although many explosions have been attributed to open lights none has been charged against the permissible cap lamp. Nystagmus, a disease of the eye attributed to working under insufficient illumination, is practically unknown among; American miners, although it is quite prevalent among European miners.

Jan 1, 1935