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By Duk-Won Park

Ground water has been a problem in underground mines (Anon., 1981; Aughenbough, 1973; Stansbury, 1981). Water migrates from water-bearing formations and surface water bodies such as lakes, ponds or creeks into the underground workings through fractures and cracks. As a result, under- ground workings become plagued with the necessity of having the water pumped out in large quantities. Underground workings become flooded when unexpected amounts of water flow into the openings, especially when mines use pillar extraction or longwall mining methods. It is difficult to detect water bodies above the coal mine roof before water problems take place. The resistivity method was used as a method for detecting water saturated rock layers and bodies of water above the roof of a coal mine in northern West Virginia, where the multiple seam mining method was being used.

Jan 1, 1983

By Adrian C. Dorenfeld

The lesser developed countries (LDC's) may be classified into two categories: 1) oil producers, and 2) non-oil producers. The non-oil producing LDC's, as a class, are at present in very difficult financial straits. (1) Since the quadrupling of world market crude oil prices in 1972, an ever greater share of the LDC's export earnings have gone to pay for oil imports, in-stead of national reinvestment. The LDC's inter-national debts--much of it to pay for oil--have soared to record levels, with consequent limits for future credits. (1) Again, this inhibits future national investments, and there does not seem to be an end to the future increase of Organization of Petroleum Exporting Countries (OPEC) prices. Indeed, some of the economic difficulties in some metal markets--particularly the imbalance of production vs. markets for copper, can be traced indirectly to the OPEC cartels' heavy-handed impact on copper producing LDC's which must produce copper at any price to meet their oil bills. (2) Among the major oil importing LDC's are the Philippines and South Korea. 50th nations have substantial cement industries. The South Korean industry is geared for major export markets in the Far East. Both nations have ambitious plans for economic growth in order to accommodate burgeoning populations with ever increasing expectations for high standards of living. These plans had some success, more or less, until the high OPEC oil cartel charges had to be borne. Now, in common with all oil-deficit areas, the Philippines and South Korea are seeking lower cost sources of energy. Both countries have coal deposits. In the case of the Philippines, the reserves are in scattered, relatively small deposits. Most of the coal deposits are faulted, folded and, in general present formidable production problems for limited reserves. Nonetheless production has been on the order of about 70,000 to 150,000 tons per year in the last 30 years. Prior productions (1920-1941) varied between 9,000 Co 150,000 tons per year. (13)

Jan 1, 1978

By G. H. Friedrich

The distribution of mercury in soils, rocks, and ore was studied in three areas of the Pachuca-Real del Monte District: (1) An area north of the town of Pachuca where ore veins have been found at or near the surface. The mercury content of soil samples taken near the vein zones is far above the background value. The highest value was 1900 ppb (parts per billion) mercury in a soil sample above Veta Vizcaina; the background is about 50 ppb Hg. (2) In the area north of the town of Real del Monte where only a few of the veins are known to crop-out. Regardless of exposure, soils collected over veins show anomalous mercury values ranging from 250 ppb to 1900 ppb. (3) In an area south of the town of Real del Monte. Here, although vein outcrops are lacking, mineralization is known at a depth of about 120 m. All soil samples taken at 50 m. intervals along an east-west traverse contain anomalous amounts of mercury, with peaks corresponding with the known location of the veins.

Jan 1, 1965

By PDF

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

Jan 1, 1995

By E Mutaz, M Bahaaddini, D J. Williams, M Serati

The contribution of the mining industry to the global economy has reached (and gone beyond) $1,800 billion in recent years that necessitates (more than before) the need to ensure workability, viability, health, and safety of mine sites and workers to meet the ever-increasing global demand for mineral resources. Amongst the many challenges facing the excavation industries, rockburst and spalling failures in deep mines in hard and brittle rock formations are yet happening that are still deemed as unsolved problems. During unconfined compressive testing of brittle rocks, microcracks initiate at approximately 0.3–0.5 of the peak strength (which is commonly known as the Crack Initiation stress level) mainly in the direction of the major principal stress, then grow unstably and coalesce to form macro fractures at approximately 0.7–0.8 of the peak load at a so-called Crack Damage stress threshold. From a stress-strain perspective, the crack damage stress threshold () is associated with the reversal point of the volumetric strain, which is also proved to be strongly affected by the intermediate principal stress. This paper extends the previous studies on the impact of true triaxial loading conditions on the CD stress level in high porosity rocks, and introduce a new Crack Mode-Changing Stress (CMCS) defined as the minimum principal stress required to change rock fracturing from splitting to a sliding failure mode. A large number of experiments on sandstone specimens were carried out at different true triaxial loading conditions and the effect of principal stresses on the CI and CD as well as CMCS were studied. The results show that not only the intermediate principal stress, but also the minor principal stress can significantly affect the CD and CMCS thresholds.

Apr 26, 2022

By T. Carageorgos

The removal of arsenic from process streams as ferric arsenate compounds is being practised by mining industries. Therefore, the solubility and stability of these solids is of considerable importance to the mining plants that have to keep the environment free from pollutants. There is some information on the solubility of the ferric arsenate compounds, mainly on scorodite, obtained from synthetic solution. However, there is not so much work on ferric arsenate compounds formed at high temperatures (175 - 230°C) during the leaching process. In the present work, the solubility of the ferric arsenate compounds formed during acidic pressure oxidation of arsenopyrite is presented. The results of the solubility tests showed that the ferric arsenate compounds formed at high temperatures (200 - 230°C) and high pressures (1034 - 1551 kPa 0,) released arsenic into solution in amounts less than 1.2 ppm and iron in amounts no higher than 1.0 ppm. So, they seem to be potential compounds for arsenic and iron disposal.

Jan 1, 1998

By M. Leroux, S. R. Rao, J. Kim, V. Gervais, J. A. Finch, G. Labonté, N. Macminn, M. Ounpuu

Collectorless flotation of sulphide minerals from Lyon Lake ore (Mattabi Mines Ltd.) has been studied both in the laboratory and plant. Among the four major minerals chalcopyrite showed the greatest response to collectorless flotation, followed by galena. Flotation of sphalerite and pyrite was minimal. Collectorless flotation was influenced by pulp potential and pH. Experiments using different gas compositions showed collectorless flotation was promoted when the pulp potentials were greater than about 0 mV (SCE). The study of the effect of depressants showed that SO2 at pH < 8.0 depresses both galena and chalcopyrite but at pH 9.5 flotation of chalcopyrite recovers. Use of NaCN preferentially depressed chalcopyrite compared to galena. Preliminary results from plant tests at Mattabi Mines Ltd. confirm that collectorless flotation occurs and that it is preferential for chalcopyrite and to a lesser extent galena. Practical implications of collectorless flotation in plant practice are discussed. A critical factor will be silver recovery.

Jan 1, 1989

By K. N. Han, M. C. Fuerstenau, T. B. Onlin

A mathematical model describing the concentration profile of fine particles in the axial direction in liquid fluidized beds has been developed for the removal of fine particles. A forward finite differentiation technique has been used to solve a continuity equation with a source term to predict the concentration profile and, hence the recovery as a function of time. With the aid of experimental results obtained using a fluidized bed of 3-cm diam, dimensionless parameters were identified. These parameters were used to predict the concentration profile of fine particles in fluidized beds of larger sizes. Four different sizes of fluidized beds, namely, 1.3, 3.0, 4.0, and 7.5 cm in diam, were used in this investigation. The amounts of bed particles used included 4, 8, 16, 24, 59, and 120 g, and the size of bed particles were 48x100, 100x150 and 150x200 mesh.

Jan 1, 1987

By Jean-François Boucher, Ernest K. Yanful, Mei Lin Shelp, Lionel J. J. Catalan

Shallow water covers for preventing acid production in tailings are based on the principle of minimizing oxygen availability. Resuspension of material from the tailings bed may result in increased oxidation and metal releases since dissolved oxygen is at near saturation levels in the water cover. Resuspension can be caused by waves and currents strong enough to mobilize the surface of the tailings bed. Tailings resuspension was measured with sediment traps in the Upper Cell of the Heath Steele site near Mirarnichi, New Brunswick Canada. Although significant amounts of resuspended tailings were collected in all traps, analysis of resuspended solids and bed tailings suggests that for the observed wind conditions resuspension did not occur at locations where the water cover depth was greater or equal to 1.0 m. Currents were likely responsible for the transport of resuspended tailings from shallower areas to locations where the water cover was deeper than 1.0 m.

Jan 1, 2000

By G. S. Dobby

Particle collection is considered to occur by particle collision with the bubble followed by the particle sliding over the bubble during which attachment may occur. Collision is quantified by a collision efficiency, EC. The existing model for EC is extended by including particle inertia. Attachment is quantified by an attachment efficiency, EA calculated as the fraction of particles which reside on the bubble for a time greater than the induction time. These calculations use recent data on the liquid velocity distribution over the upper half of rigid spheres. Collection efficiency, EK is given by EK = EC ? EA. Detachment is not considered. The mode is examined and shown to agree with much experimental data. For example the maximum observed in recovery vs particle size (d) can be explained as E increases with increasing d , while EA decreases. The decrease in selectivity at fine sizes is in accord with the model result that for dp < 5µm, EA ? 100% (i.e. EK ? EC) almost regardless of induction time. A decrease in bubble size does increase EK but does not improve selectivity. A high particle density (> 5g/cm3) is shown to cause a sharp peak in recovery vs size and a decreased maximum size of floatability. Finally, the possible effects of bubble and particle concentration are explored.

Jan 1, 1985

By M. Misra, J. Nanor

The removal and stability of arsenic over a wide pH range (3.0-10.0) from synthetic solutions and industrial waste effluents (including mining waste tailing slurry) can be accomplished with addition of impure lanthanum chloride alone or in conjunction with ferric sulfate. The long term stability of these correspond­ing precipitated compounds is critical from the disposal stand­point. In this paper test results of this new process for arsenic removal and stabilization from the above mentioned systems are presented. Also, precipitated arsenic compounds (lanthanum arsenate, lanthanum-ferric arsenate, ferric-lanthanum arsenate and ferric arsenate) from synthetic solutions have been charac­terized. The characterization technique used was XRD. XRD patterns which shows that the lanthanum arsenate and lan­thanum-ferric arsenate formed in acidic and alkaline pH at room temperature are crystalline. On the contrary, ferric arsenate and ferric-lanthanum arsenate compounds formed under the same conditions as lanthanum arsenate were amorphous.

Jan 1, 1998

The Bureau of Mines, U.S. Department of Interior, is currently investigating strata interactions associated with the mining of multiple coalbeds. Strata interactions due to subsidence are a result of undermining. This study involves underground investigations at a mine where room and pillar panels are actively being developed through an area of the Sewickley Coalbed which was subsided by undermining of the Pittsburgh Coalbed. Research to date indicates that undermining had little effect on upper mine pillar stability, but had a more severe effect on the development and maintenance of entries. Roof-to-floor measurements recorded over four times more convergence in entries developed over gob as compared with entries developed over support pillars in the lower mine. Consequently, this has led to major roof falls in the active panels, resulting in considerable production delays and supplemental roof support costs.

Jan 1, 1985

By W. A. McKinney

In conventional dump leaching of porphyry mine strip wastes, many years are required to extract up to 20 percent of the copper from the contained sulfide minerals. Furthermore, none of the molybdenum, gold, or silver in the strip wastes is recovered by current leaching practices. Because mineralization occurs predominately along fracture planes, breaking of the rock during mining operations liberates and concentrates some of the metal values in the fines. Research shows that upgraded fines can be screened from mine wastes and froth floated for early recovery of copper, molybdenum, gold, and silver. For example, screening a dump sample assaying 0.35 percent copper as chalcopyrite removed about 20 percent of the copper as minus 1/4-inch material that analyzed 0.6 percent copper. About 35 percent of the molybdenum and 20 percent of the gold and silver also reported in the fines. Crushing the mine dump sample to minus 3 inch before screening increased the distribution of copper and molybdenum in the minus 1/4-inch screen fraction to 28 and 50 percent, respectively. Similar results were obtained by screening fines from two other large samples of mine waste dump materials. Flotation studies established that the enriched minus 1/4-inch fines from the three dump samples could be effectively concentrated. Comparative testing revealed that the combination of froth flotation of fines and acid-ferric sulfate leaching of the coarser fraction enabled doubling the recovery of copper over direct leaching of the samples. In addition, significant amounts of molybdenum, gold, arid silver were recovered by flotation.

Jan 1, 1970

By M. I. Dobrynina

At the beginning of the 80-s the first diamond pipe in the East-European platform was discovered in the North of the Russian Federation on the White Sea Winter coast. During several years while studying this unique area data on kimberlites and country rocks petrophysical characteristics have been collected. Considerable experience in geophysical methods when searching and exploring diamonds was accumulated, and various methods of geophysical data interpretation were used. It has been established from the analysis of geophysical data that diamond-bearing kimberlites are located in the most ancient and the most stable block of the East-European craton.

Jan 1, 1995

By J. D. Miller

Physical separation of bitumen from low-grade Utah tar sand deposits containing a relatively high viscosity bitumen phase (Sunnyside and Tar Sand Triangle deposits) has been accomplished by traditional size reduction and froth flotation techniques. At appropriate experimental conditions more than 90 percent of the bitumen can be recovered in a concentrate, containing more than 20 weight percent bitumen, which should be a suitable feed material for subsequent hot water or thermal processing. The efficiency of bitumen recovery depends on the extent of size reduction, promoter and dispersant addition. Rejection of greater than 60 percent of the sand at ambient temperature and ease of water removal from the concentrate make such a process strategy both energy and cost effective. The energy required to achieve effective separation by the ambient temperature process is significantly less than the energy required for the recently developed hot water process. The flotation behavior of the tar sand has been analysed with respect to flotation pH, contact angle measurements and the apparent iso- electric point of the bitumen. The best flotation response at pH 7.8 to 9.0 can be correlated with the maximum in contact angle developed between the air bubble and bitumen surface and with the apparent iso-electric point of the bitumen (-pH 8.0).

Jan 1, 1981

By Shawn T. Sorrell

Phillips Coal Company (PCC) submitted the first surface mine permit application under the Office of Surface &lining approved regulatory program of the State of Louisiana. This application for the Oxbow Lignite Surface Mine which is located approximately 64 kilometers (40 miles) southeast of Shreveport, Louisiana was submitted in March 1981. The State of Louisiana Office of Conservation, Surface Mining Division, assigned this application number LSM-1, indicating it is the first one submitted in Louisiana history. The permit area for the Oxbow Mine encompasses 6,251 hectares (15,627 acres). Of this total permit area, 5,862 hectares (14,656 acres) were classified by soil type as prime farmland by the U.S. Soil Conservation Service (SCS). Prime farmland acreage in the permit area became a major central issue in our early planning stages and throughout the permitting process of the Oxbow Mine, due to the magnitude of acreage involved.

Jan 1, 1982

By S. F. Diehl

Suites of monomineralic sulfide and carbonate minerals, as well as mine-waste composite samples, were analyzed using chemical and microanalytical techniques to understand behavior and bioavailability of mine waste elements such as Cu, Fe, Pb, or Zn. Petrographic, scanning electron microscopy (SEM), and laser-ablation inductively-coupled mass spectrometry (LA-ICP-MS) studies of mineralogical residence sites of trace elements are important because trace elements affect the chemical and physical behavior of minerals. Leachate solutions show that chalcopyrite, bornite, azurite, malachite, and galena are host to the trace elements Ag, Al, As, Cd, Co, Cr, Mn, Ni, Pb, and Zn. SEM studies reveal whether these trace elements occur within mineral inclusions or are substituted within lattice structures. SEM analysis reveals mineral phases not identified by X-ray diffraction (XRD), such as inclusions of sphalerite and cobaltite(?) within chalcopyrite.

Jan 1, 2010

By D. M. Thayer

Laboratory and pilot plant investigations have indicated that copper recoveries of 50% can be achieved with fine grinding and flotation of a copper reverberatory furnace slag, Microscopic and microprobe studies indicate that the recoverable copper is in the form of matte, chalcocite, and metallic copper; the percentage of copper in particles appearing to be copper-free was from 0.23 - 0.54%.

Jan 1, 1969

By D. R. Bomberger

An automatic microscope has been developed to .measure the size and populations of macerals and minerals in fine coal particles. Differentiations are made on the basis of reflectance. This study is concerned with the size distribution of pyrite inclusions. Most fine coal cleaning processes do not remove pyrite as completely as a straight density separation. Consideration of the pyrite size distribution is suggested as a more accurate method of predicting sulfur reduction by a cleaning process. Analyses of float-sink results and Deister Table operation in terms of pyrite particle sizes are made. Other potential applications of automatic microscopy are also discussed.

Jan 1, 1963

By Edward T. Koch

With the dramatic increase in world demand for basic raw materials, open pit mining is proceeding at an unprecedented rate. A viable demand is the ever tempting Siren&apos;s song for increased production or new facilities. When the Siren&apos;s lure is viewed against the panorama of today&apos;s world economic milieu the concomitant Scylla and Charybdis are seen in the form of high capital cost and high operating cost. If the economic realities of present day open pit mining are to show a proper return on investment, a clear and penetrating eye must be cast upon the area of mine planning. This paper deals with the problem of overburden removal. In almost every open pit mining operation overburden removal is a significant part of the capital cost and operating cost of the total operation. This paper deals with a new and unique method to affect economical overburden removal. Well known to all are the parameters surrounding draglines, shovels, and bucket wheel excavators. All of these machines require a reasonably stable soil to support them and the shovel and bucket wheel excavator require a reasonably stable bank in which to operate. Their reliability, portability and rate of production per dollar of invested capital are good.

Jan 1, 1975