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By D. S. Dinsmoor

Boron, estimated to comprise about 0.001 percent of the earth's crust (Fleischer 10), as an element is never found free in nature, although its compounds are found in many localities. the borates are the most important. Sassolite (B(OH)3) and boracite (Mg6C12B1406), non-borates, are-of-minor importance. The crystal structures of most natural borates are still unknown. A classification based solely on the ratio of boron to the total number of cations has been devised (Palache 28). This classification divides the borates into four, sub-groups; anhydrous borates, hydrated borates, borates containing hydroxyl or halogen and compound borates. Only four or five minerals of the hydrated borates group have ever been used commercially. In more recent years, the sodium borates have comprised all but a 'small fraction of all borates used. Borax, the hydrated borate compound, is the most important of all boron compounds. It has been used so long and so often that the layman often confuses borax and boron and, applies the terms synonymously.

Jan 1, 1958

By C. J. Johnson, C. J. Bise

Abstract - As the US coal industry moves into the next century, it is becoming more apparent that the effective application of new technology is the only way it can remain competitive in the energy marketplace. Examples of this emphasis are with us today in such diverse areas as face- ventilation and excavation-equipment applications. The focus of this new technology is directed toward improvements in health and safety, cost control, and productivity. Room-and-pillar mining accounts for approximately 68% of the nation's underground coal production; this percentage is not expected to decrease markedly in the near future. As such, this paper analyzes the impacts of the changing techno- logical climate on future room-and-pillar operations by comparing a base-case section (current) to three scenarios incorporating new or emerging technology. A microcomputer-based comparative analysis will reflect the changes in section production and costs.

Jan 1, 1990

By J. R. Evans

In order to patent an industrial mineral placer mining claim, it must incorporate an economic deposit. Each ten acre parcel is evaluated for its mineral -in -character nature. Nonmineral -in -character parcels cannot be patented. Economic concerns include: claim locations, dummy locators, common variety nature, "excess reserves," and environmental constraints. Also, geologic and mineralogic studies, sampling and testing procedures are vital. Mining, milling, processing cost, and taxes must be evaluated. Product marketability analysis is necessary before starting any cash flow or discounted cash flow study. Valid data is essential to evaluate an economic industrial mineral deposit.

Jan 1, 1997

By J. M. Ekenes, C. A. Caro

"New approaches that increase hydrometallurgical recovery from refractory minerals in below mill cutoff -grade sulfide copper ore can add significant value, improve profitability and increase ore reserves. This paper describes the development and implementation of an engineered heap (EH) approach to leaching low-grade, chalcopyritebearing ore at Freeport-McMoRan’s mine in Morenci, AZ. The technical evolution of the engineered heap concept is described together with the challenges and benefits following implementation. Introduction The Morenci ore deposit, located in eastern Arizona, has been mined for copper for 140 years. Mineralization in the Morenci district consists of sulfides and oxides. To process these ores, Morenci operates concentrator and leaching circuits. Leaching accounts for two-thirds of the copper produced in Morenci. More than one-half of this leaching-derived copper production comes from run-of-mine (ROM) stockpiles. The largest category of material moved in Morenci is destined for ROM stockpiles and waste dumps. Materials that are not economic to mill or leach are designated “waste.” However, this designation can change based on improvements in extraction technology and commodity prices. Chalcopyrite does not leach well due to its refractory nature. For predominant chalcopyrite mineralized ore, copper recovery during a typical leaching cycle may be as low as 5%. For this reason, chalcopyritedominant ores below mill cutoff grade have historically been classified as waste. By incorporating advanced leaching technology to improve metal recovery from previously leach-resistant ore types such as chalcopyrite, the Morenci Mine has been able to reclassify substantial amounts of this “waste” to “ore.” Process chemistry Chalcopyrite copper extraction is temperature, oxygen and ferric dependent. The temperature is achieved primarily by pyrite oxidation (Eq. (1)) and secondarily by oxidation of chalcopyrite itself (Eq. (2)). The regeneration of ferric in solution can be enhanced by providing the appropriate acid and oxygen levels according to Eq. (3). In the absence of microorganisms, this reaction is very slow."

Jan 1, 2015

By R. A. Cummings

From before the turn of the century until as recently as the 1950s, relatively shallow coal reserves near the margins of the Illinois Basin were extracted by room- and pillar methods. Subsequent development has, in many cases, extended onto ground with high subsidence potential. The same state of affairs exists in many other historical coal mining districts, as well as in Illinois. Pit subsidence in Illinois is particularly common in the towns of Streator, Carterville, and Herrin, although there are others. Pit subsidence is characterized by distinct circular or oval depressions and normally is associated with shallow mining and thick soil relative to the thickness of rock.

Jan 1, 1985

By Robert L. Sundeen, Richard V. Wenberg

INTRODUCTION Early rock-bolting practice usually consisted of ran¬domly installing bolts, using hand-held drilling equip¬ment such as air-leg mounted sinkers or stopers. As bolting technology evolved, the practice of installing uniform bolt patterns was developed, utilizing random bolt installation as required within the uniform pattern. The uniform rock-bolting technique, when used as the principal method of rock support, requires drills and jumbos designed specifically for rock bolting. This equipment is similar to conventional face drilling machines, except that the jumbos can orient the drills to obtain any necessary bolting angle; often, this means bolts may be installed at or near perpendicular to the centerline of the drift or stope opening. Fig. I shows a typical rubber-tired rock-bolting jumbo of the type commonly used in drifts and room-and-pillar mining. Modern rock-bolting jumbos are capable of drilling the required holes, inserting rockbolts, and torquing them to proper levels. Jumbos also are available for use with resin-anchored bolts. Probably the most unusual of this type utilizes a rotating bolt turret that carries the rock drill, resin charging unit, and the bolt in a single mechanism. Once the turret is loaded with the resin and bolt, further manual effort is not re¬quired. Drilling and bolt placement are accomplished by the operator from a station remote from the bolt site. Fig. 2 shows this turret device. Roof-bolting jumbos are available mounted on rail, crawler, or rubber-tired chassis. Various types of rock drills are used. Depending upon the type of rock, these may include rotary, percussion, or rotary-percussion drills. Fig. 3 shows a typical rail-mounted jumbo. CONDITIONS INFLUENCING APPLICATION General Rock Conditions Rock-bolting generally is applicable in moderately hard to hard rock. No particular type of rock is ex-

Jan 1, 1982

By Brig M. Moudgil

It was reported earlier that francolite and dolomite from the South Florida deposits cannot be selectively floated using conventional conditioning with sodium oleate as the collector. However, dolomite could be separated from francolite if the minerals were first conditioned at pH 10 followed by reconditioning at a lower pH. An optimum separation was achieved at a reconditioning pH below 4.5. Reconditioning pH and collector concentration were determined to exert a major influence on the selectivity. Flotation, adsorption and transmission infrared spectroscopic results are presented to elucidate the mechanisms underlying the observed selectivity.

Jan 1, 1984

By L. Cheng

Almost all modern cutting bits use a cemented tungsten carbide tip to provide adequate hit life against wear. Laboratory tests by the US Bureau of Mines have indicated that the number of strikes for ignition increased by a factor of three with a new non-rotating bit impacting a sandstone block when the clearance angle was increased by 10°, and that carbide-tipped bits allowed more strikes before ignition than steel-tipped bits by a factor of 7 to 10. Recent field tests in an operating coal mine indicate a dramatic reduction in the frequency of frictional ignitions and improvement in hit life by using a mushroom-shaped hit cap and a larger initial clearance angle. The latter was achieved by increasing the hit attack angle. Improved hit performance through selection of the grade of tungsten-carbide is a com¬promise between fracture resistance and wear resistance. A large clearance angle should he maintained by various techniques, such as a variable attack angle holder, or a reusable hit that can he reground.

Jan 1, 1990

By John Nadolski

Intensive hydrologic monitoring of the Powder river basin has been on-going since the early 1970's. Data were used in environ- mental assessments and for determination of hydrologic consequences associated with coal mining activities. For most coal mine operators, data collection has continued in this baseline mode with little or no statistical analysis of the data and with no statistical procedure established to detect changes in groundwater quality. For the past four years Powder River Coal Company has studied several statistical techniques to analyze groundwater quality. Three objectives were pursued: 1) to determine the baseline water quality for key aquifers; 2) to determine which wells could be deleted from the monitoring program without reducing monitoring effectiveness; and 3) to define a statistical test to determine water quality changes. Knowledge of the regional geo-hydrologic system was combined with an analysis of the water quality monitoring in order to identify homogeneous aquifer zones. All wells within an aquifer zone were treated as one population, and a t-test was used to determine the minimum number of samples needed to define the water quality for each aquifer zone. Results indicate that the data for each aquifer zone were nor- mally distributed and that groundwater quality could be defined using a fairly small number of samples. Because of the minimum sample size test, groundwater quality sampling was reduced by between 75 and 85 percent.

Jan 1, 1989

By J. W. Merks

At mineral processing plants the accuracy and precision characteristics of assays in mill feed, tailings and concentrate largely determine the reliability of the metallurgical balance. The accuracy of measurements is ensured by selecting effective sampling methods and efficient sample preparation procedures, and by effecting each phase without introducing a systematic error while the precision of measurements is determined by the sampling regime. Sampling systems and components, sampling methods and regimes, and sample preparation procedures will be reviewed. Different techniques to determine variance components for sampling, preparation and analysis, and to detect systematic errors in assays at mineral processing plants, will be discussed.

Jan 1, 1986

By Marshall D. Himes

The Pima mine, 39,000 ton per day copper mine, is located 17 miles south of Tucson, Arizona. The mine is in a sequence of Paelozoic and Mesozoic sediments striking east-northeast and dipping southeasterly intruded by a Tertiary quartz monzonite porphyry. The Paleozoic Permian(?) dolo¬mites, limestones, and sandstones have been altered to talc-silicate skarn, marble and quartzite. The overlying Mesozoic Triassic(?) clastic sediments have undergone some recrystallization and hydro¬thermal alteration. The clastic metasediments are divided into three distinct lithologic units, lithic arenite, arkose, and inter¬bedded and overlying black argillite. Three types of hydrothermal alteration in the clastic rocks are propylitic alteration (epidote, chlorite and quartz, with or without sericite), quartz-sericite alteration, and potassic alteration (K-feldspar and quartz, with or without sericite and chlorite). The porphyry has undergone potassic alteration. Dominant structures are an east-west post mineral fault in the western part of the pit, and strong low angle faulting and shearing which truncates the ore body at depth. Two joint sets, one parallel to bedding and the other at right angles to bedding are prominent in the mine. Faulting is in two dominant directions, one striking northwest, dipping northeast and the other striking northeast, dipping northwest. Mineralization is predominantly disseminated pyrite and chalcopyrite, and molybdenite-quartz veinlets. There are lens important amounts of magnetite, hematite, sphalerite, galena, tennantite and bornite. Mineralization is believed to be both structurally and chemically controlled.

Jan 1, 1972

By Ryan Dr.

In December 1988 Phelps dodge corporation brought an underground gold mine into production in the republic of Botswana. The mineralization is associated with steeply dipping shear zones in Archean greenstones of the Tati Schist Belt. The gold is intimately associated with sulfides and is refractory in nature. The deposit is being exploited by underhand open stoping methods. Vertical and inclined shafts are used to hoist the ore to surface where it is treated by conventional crushing, milling and flotation, followed by fluid bed roasting with CIP elution and carbon regeneration. Adjacent deposits are being explored with a view to increasing production. Legal and taxation aspects of operating in Botswana are discussed.

Jan 1, 1989

By Norman K. Olson

Hard-rock phosphate was formerly the chief source of all phosphate in Florida. Its mining began as early as 1883 or 1884, reached a peak level in 1907 and ceased in 1966. Production began and ended in the Dunnellon area (Marion County). Nearly all the hard-rock was exported because its P205 value per unit weight is generally more concentrated than that of other phosphate rock. Maximum production, achieved in 1907, was greater than 600,000 tons; the total value for that year was more than $4,000,000. The Florida hard-rock phosphate, considered to be of middle Miocene to early Pliocene age, has an intermittent narrow, linear northwest-southeast trend. The Ocala uplift controls the phosphate distribution for more than 200 miles. Other known, isolated hard-rock areas appear to be related to minor folds on the Ocala uplift. The hard-rock phosphate deposits are a heterogeneous mass of sedimentary fluorapatite, chert and quartz with textures ranging in size from clay to boulder, and in thickness from 0 to 40 feet. Phosphate compounds, principally fertilizers, have been in oversupply since before 1968, but by the middle 1970's some experts forecast a supply-demand balance. A brighter future for exploitation of Florida hard-rock phosphate depends upon one or more of these factors: 1) depletion of present premium grades (74 percent BPL and above) of land-pebble; 2) cheaper electric power from nuclear generators for profitable electric furnace operation; 3) supply and price of sulfur; 4) manageable rail-water transportation costs; 5) development of less costly mining and separation methods; and 6) minimum competition from high-grade foreign phosphate.

Jan 1, 1972

During the past year a number of significant advances in geostatistics have been published. These were presented at the 13th APCOM Symposium in Clausthal, Germany and at a NATO Advanced Study Institute on Geostatistics in Rome, Italy. Of greatest importance is the work that has been done in establishing methods which correctly predict the cutoff grade-tonnage curves, and the average grade of ore-tonnage curves for deposits in which ore and waste are intermingled. Grade-tonnage curves based on estimates made from widely spaced exploration data have been found to underestimate the grade of ore and overestimate the tonnage present. This problem has been remedied by the calculation of conditional probability distributions for the unknown grade of a block. Another advance has been made in the field of geostatistical estimation for deposits in which a trend is present. Previously a technique known as universal kriging has been used, which involves much subjective judgement as to the trend fitted. A new technique, generalized increments, allows computer estimation of such deposits with much less subjective judgement. Computational efficiency of geostatistical methods has continued to improve to a point where a geostatistical estimate can be obtained for little more than the cost of any other computerized method.

Jan 1, 1976

By Gürkan Bacak

Study area is located on the NorthWestern of Yatagan-Yenikoy and placed in the units of the crystaline Menderes massif of Eagen, Turkey. Stratigraphically gneissic, migmatitic and metagranitic rocks are found at the base. Garnet schists, phyllitic rocks lie unconfirmitelly upon the basement rocks. Permian aged marbles can be observed as diferrent sized lenses within the schists. Triassic, Jurassic and Cretaceous aged gray colored dolomites and pure crystaline calcite bearing marbles lie upon the Permian aged schists. Neogen series, mainly composed of conglomerates, claystones, marl and limestones unconformly cover the other basement series, mentioned above. Pure calcite bearing marble occurances are found at 2 locations in the study area. These are known as Berber Quarry and Kavuk Quarry. Samples numbered as N7, N8, NA from the Berber Quarry, mineralogically composed of Calcite (97-99%)+iron oxide (1-3%) and chemically contain CaCO3 (97,98%), Fe2O3 (0.5-1%), SiO2 (0.025%) N9 and N10, sampled from the Kavuk Quarry-mineralogically composed of Calcite (94,95%)+iron oxide (2-3%)+albite-Quartz (1-2%) and chemically contain CaCO3 (92-93%), SiO2 1.49%, Fe2O3 0.42%. Especially in plastic and paint sector albite and quartz are unwilling minerals due to their hardness. Approximatelly 1/20 of the study area (87.500 km2) contains industrial calcite occurances. Moreover about 100 billion Tons geological, 1.86 billion tons runable (possible) calcite reserve calculated. It can be expected the calcite quality will be increased with depth. During the running stage of the quarries over burden removel and hand sorting processes will positive affect of the quality.

Jan 1, 2005

By M. Boucraut

After stating the advantages of the magnetic roasting technique as applied to iron ores, the authors report on technological research by I R S I D * in the field of magnetic roasting in fluid-bed furnaces This investigation was conducted first on an experimental two stage fluid-bed furnace which processed permanently 100-200 kg/h of ore, then on a three stage fluid-bed furnace with 1-2 t/h working capacity and at last on a 250 t/day pilot furnace The specific features of the IRSID process comprise - on the one hand, using special burners in the roasting reactor thereby ensuring a high production rate of the furnace - on the other hand, using a heat-exchanger where the preheating and cooling stages of fluidized ore are associated, so as to allow an efficient and simple cooling of both roasted ore and waste gases flowing out of the roasting reactor, thereby supplying heat to the crude ore and combustion air for the reactor burners Starting in 1965 the operation of the 250 t/day pilot plant at the Bazailles mine gave IRSID the opportunity of improving the conveying appliances and adapting them to the process, while perfectly confirming the metallurgical results obtained under ideal laboratory conditions

Jan 1, 1968

By H. R. Coles

Test work conducted in the 6.4 and 10.52 m Aerofall Mills at the Iron Ore Company of Canada Carol Project showed that the conventionally used ?deflector?-type liners which form the basic principle of Aerofall Mill grinding did not necessarily provide the best grinding performance. A new design, using low profile liners incorporating radial ribs of a proper height, actually improved the mill throughput in the order of 9 to 20% without sacrificing grinding efficiency. In addition, the new design reduced liner weight and scrap losses, which resulted in a reduction of liner consumption by 25%. It provided better protection to the mill shell and reduced the overall maintenance cost for the mill

Jan 1, 1980

By G. V. Henderson

Limestone and Dolomite quarries located near Salto-De-Pirapora, Arroia Grande Gaucho, Conde Francisco and Candioita probably represent the closest, major sources of high quality lime and cement grade carbonate rocks to the major population center of Sao Paulo Brazil. The nearest major city to most of the limestone - dolomite sources is Sorocaba and Palma. All of the mining properties visited during this study are located in the state of Rio Grande Do Sul at approximately -32 degrees south latitude and -52 degrees west longitude, southwest of the major port city of Porto Alegre.

Jan 1, 1981

By Harold J. Bennett

The Minerals Availability Program is a Bureau of Mines Program to systematically measure and classify identified worldwide nonfuel mineral resources according to their respective extraction technology, economics, and commercial availability. The program is designed to identify, collect, compile, and evaluate information on worldwide active mines as well as on developed and explored mineral deposits, and on mineral processing plants. Objectives are to classify domestic and foreign resources, to identify by cost evaluations resources that are reserves, and to prepare analyses of the availability of these resources for 34 commodities and secondary minerals. Availability analyses consider such factors as geographic location, the type of producible material, the technology and time required to produce a marketable product, and the productive capacity and unit cost for each deposit. These factors, reflected in the aggregated tabular and graphical data in the study for each commodity, are developed for consideration in the formulation of both domestic and foreign mineral policy. To date, the data have been collected for the 34 commodities and the availability analyses are in various stages of completion; expected first cycle completion date for all 34 is early 1986. Raw and aggregated data are available to the public in the form of computer-generated listings, tapes, and maps as well as in published reports. Also, systems developed to assist in performing the engineering and economic c analyses, including the computerized economic evaluation program (MINSIM) and the cost estimating system (CES), are available.

Jan 1, 1984

By S. J. Porter, M. T. McRae

The new tunnel at Genting Sempah is part of a privately funded infrastructure projectthat involves duplicating the existing highway extending from the Gombok Toll Plaza near Kuala Lumpur to Karak, in Malaysia. The 60 km long tollway includes an 800 m long, two-lane highway tunnel with excavated dimensions of 10.5 m wide by 8 m high. The majority of the tunnel extends through slightly to moderately weathered, moderately to highly jointed quartz porphyry. Excavation of the tunnel was performed using drill and blast methods and the primary tunnel support consists of rock dowels and shotcrete except for short sections adjacent to the portals where steel sets were utilized. A portion of the tunnel encountered sheared and altered material that was successfully supported using rock dowels and shotcrete. The final lining for the tunnel consists of mesh and fiber reinforced shotcrete. The flexible nature of the primary support and shotcrete final lining resulted in considerable cost savings and expedient construction methods.

Jan 1, 1997