Search Documents

By M. Ge, C. Mborah

"The acoustic emission/microseismic monitoring (AE/MS) technique has widely been used in the mining environment for the monitoring of rock mass stability. A successful implementation of the method is hinged on being able to accurately determine the P- or S-wave arrival which is then used in the determination of the source of an event. Determination of the arrival phase is usually performed visually by a human expert. However, the mining environment is characterized by high noise levels and different noise types of varying intensities. Therefore, performing manual phase picking on time series data acquired from the AE/MS monitoring system can sometimes be tedious and time consuming if not impossible. In this paper, a proposal for improving manual P-wave phase arrival picks is discussed. The method involves the filtering of the AE/MS data using a stationary discrete wavelet transform (SDWT) method. After filtering, appropriate scales/levels of the multi-level decomposition process are then selected for further processing. The first step in the picking process after filtering, requires the computation of the signal power and the root mean square (RMS) using the signal amplitudes at each scale. The preliminary P-phase arrival time is picked using the results of the calculated power and RMS values respectively. The calculated RMS values are then superimposed on the calculated power values to determine the final arrival picks. If the arrival time picks obtained by both methods coincide or are within 5 to 10 sample points, the pick is considered reliable. The accuracy of the method was verified using AE/MS data from two datasets obtained from two separate underground mines. The results of the study showed that the picking method is reliable and robust. Based on the data studied, it can be concluded that the method will help reduce the time usually spent in processing AE/MS data from mines. INTRODUCTION A successful identification and location of the source of acoustic emission/microseismic (AE/MS) events is mainly dependent on the onset time of the P-wave phase. In many seismic networks, initial picks are performed by picking algorithms followed by manual picks by human experts. If the waveform signal-to-noise ratio (SNR) is low, the P-wave onset time picks by the human expert is generally reliable and accurate [1]. However, for waveforms with high SNR, picking of the P-wave onset could be a major challenge. Also, due to the volume of data acquired daily, manual processing could be stressful and time consuming [2]. These challenges continue to provide motivation for alternative means of providing reliable and efficient ways of improving manual phase picking. The AE/MS technique has been an intergral part of safety monitoring in mines [3] due to its capacity to identify zones of instability in a monitoring area. To obtain an accurate source of an AE/MS event however depends on the quality of the data used for P-wave phase picking [4, 5]. AE/MS data from mines are generally contaminated with excessive background noise generated by the different mining operations. The AE/MS signals of interest are mostly buried in background noise which makes it difficult to pick the P-wave phase arrivals [4]. Processing AE/MS data acquired in noisy environment remains a major challenge due to the weak nature of AE/MS signals [6]. As noted by [4] most of the data recorded in the mine environment are mainly due to events not related to AE/MS events of interest. The complexity of data in this type of environment makes the detection and picking of P-wave arrival by human experts a very difficult task."

Jan 1, 2017

By Gerald W. Elger

Research at the Albany Metallurgy Research Center has shown that high-purity rutile can be produced from relatively low-grade ilmenite obtained from a massive rock deposit. Ilmenite is first smelted in an electric-arc furnace to separate the iron and produce a slag enriched in titanium dioxide. Titania slag mixed with a phosphate flux is then oxidized to synthesize rutile and form a phosphate-glass matrix which contains the impurities. Attrition scrubbing the treated slag in dilute solutions of phosphoric or sulfuric acid liberates the rutile, which is concentrated by physical methods. Tests show that synthesized rutile containing 95 to 97 pct titania responds to chlorination at the same rate as natural rutile.

Jan 1, 1973

By J. P. Rider, T. W. Beck, J. A. Organiscak

"The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Mining Research Division (PMRD) has recently developed a series of models utilizing computational fluid dynamics (CFD) to study gas distribution around a continuous mining machine (CM) with various fan-powered flooded bed scrubber discharge configurations in an exhaust curtain working face. CFD models utilizing species transport model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The study illustrates the gas distribution in the slab (second) cut. The following scenarios are considered in this study: 100% of the discharge redirected back towards the face on the off-curtain side of the continuous miner; 100% of the discharge redirected back towards the face, but divided equally to both sides of the machine; and 15% of the discharge redirected toward the face on the off-curtain side of the machine, with 85% directed into the return. These models were compared to a model with a conventional scrubber discharge where air is directed away from the face into the return. The models were validated based on experimental data and accurately predicted sulfur hexafluoride (SF6) gas levels at four gas monitoring locations. One additional prediction model was simulated to consider a different scrubber discharge angle for the 100% redirected, equally divided case. This paper describes the validation of the models based on experimental data and the gas distribution results of the CFD models. INTRODUCTION To control methane gas and dust concentrations on continuous mining operations, it is important to provide sufficient quantity of fresh air from the end of tubing or curtain to the active face. In this region, operating machine-mounted water sprays and fan-powered, flooded bed scrubbers can significantly increase the amount of airflow reaching the face [1-3]. However, when an entry is large, especially in higher coal seams, the water spray configuration and the scrubber capacity may not be adequate to maintain sufficient forward airflow to confine the dust cloud to the face. Dust can roll back toward the machine operator as a result [4]. Currently, several coal mines having negligible gas emissions in higher coal seams (2.4 to 3.0 m [8 to 10ft.] thick) with exhaust tubing systems redirect the scrubber discharge back towards the face in an effort to improve dust collection. NIOSH studied the redirected scrubber exhaust techniques for dust and gas control in a full scale CM gallery to assess its potential for industry-wide application [5]. For a CM face, previous studies have concluded that the behavior of gas and respirable dust is a complex process. The distribution/dispersion and transport of gas and respirable dust after they are liberated at the face are governed mainly by their mass properties, the movement pattern of the ventilation air, and interactions with the mining machine and water droplets created by the external water spray systems used for dust control [6-10]. To understand these behaviors in a complex CM environment and to evaluate the effectiveness of various control techniques, numerical modeling has become a necessary supplement to laboratory experiments and field studies."

Jan 1, 2017

By N. D. Cristescu

The aim of the present paper is to show how a mathematical modeling of a creeping rock and that of an yieldable lining can allow us to obtain an optimization of the lining design and generally of the whole procedure and sequence of excavation-lining application. We follow the procedure presented by Cristescu (1989) Chap. 13, and Cristescu et al.(1987); for some other approaches see the literature mentioned, for instance, by Ladanyi and Gill (1988). We have in mind to describe the creep of the rock, i.e. the tendency of the tunnel to close in time, and to take into account that the lining itself may be deforming, i.e. possesses some rheological behavior. We start from the well known fact that "intelligent" lining, which are yielding to the pressure of the rock, may be much more successful in supporting creeping rocks than excessively strong, badly designed supports which are unable to resist to pressure of the rock, though these are oversized supports (too strong, too stiff, installed too early, etc.). In order to optimize the lining to be used for a certain rock, it is absolutely necessary to study in the laboratory the main mechanical properties of that specific rock and to formulate for it a reasonably simple mathematical model. Standard triaxial test results are quite enough to determine the model for the rock, combined with some creep tests which have to reveal the long-term behavior of rock (the so-called rheological model). What concerns the lining, we consider several kinds of linings existing today, for which a mathematical model was also formulated. One shows which is the interaction between the creeping rock? and the yielding lining and how can it be formulated in mathematical terms. Once written in mathematical terms, an optimization of the lining design and that of the excavation layout and support application sequence is possible. We will try to make the exposure as simple as possible, avoiding details and having in mind to give only a sketch of the problem, while the mathematical details could be worked out quite easy.

Jan 1, 1994

By Donald Whittaker

Severe climatic conditions in mines are normally associated with working at depth. More precisely, it is a matter of working in regions of high strata temperature, since, for example, some coal mines in the Ruhr have strata temperatures at 1000 m which are matched only at 3 times that depth in the South African gold mines. In Britain we are perhaps fortunate in encountering strata temperatures in our deeper coal mines some 10-15 K lower than at the same depth in the hot mines of the Ruhr. Nevertheless the problems of high temperatures and humidities in UK mining operations, which in the past have been confined to a few specific sites, have in recent years become more widespread, and there is every reason to suppose that the trend will continue. Clearly strata temperature is not the only .causative factor. Long ventilation circuits serving districts remote from the shaft must also play a part, while the heavy use of machinery and the rapid, rates of excavation of modern mining methods are obviously important. It is necessary to understand the mechanisms of all such factors, and to measure their magnitudes and fluctuations, if remedial measures are to be properly designed or predictions made which are accurate enough to be of use in ventilation planning. This paper presents the results of a long-term (and continuing) investigation carried out in several mines to measure the major sources of heat and moisture on longwall districts and trunk conveyor roadways. The variation with time of these sources is reported, and the resultant effect on the climate is considered. In their investigations of the heat exchanges occurring in a whole mine Oakes and Hinsley (1955-56)1 listed and estimated the magnitudes of a large number of heat sources. Some of these, namely autocompression of the air in the shaft, diesel engines and compressed air mains, do not apply to the present investigations, which refer to longwall districts with conveyor transport and no compressed air supply. Others, such as oxidation of coal and, desorption of methane, have not been taken into account in the measurements, but are discussed later. One other source, the importance of which was pointed out by Gracie and Matthews (1975)2, is the coal on the conveyor, a form of strata heat emission, but one which is strongly dependent on the rate of coal production. The heat emissions measured in the present investigations were the energy consumed by electrical machinery, the heat conducted from the strata and the heat lost by the conveyed coal. Most of the emitted heat was removed from the district by the ventilation air, and was measured by continuously recording the enthalpy of the air at fixed stations. The heat removed by service water, supplied for machine cooling and dust suppression, was also measured. Account was of course taken of the relatively minor changes in level around the districts, in terms of the potential energy gained or lost by the coal and by the ventilation air (autocompression).

Jan 1, 1980

By Richard J. Lundin

Literature research is an inexpensive, yet effective tool for the direct discovery of ore deposits. Case studies abundantly demonstrate that properties with viable mineralization and *proven reserves have been overlooked, forgotten. or ignored and can be rediscovered by inexpensive literature search techniques Areal studies s as WaIlaby Enterprises Mining District Data Base Program appear to be more effective than traditional commodity studies. The success of such studies depends on the inclusion of Mineral Clairant Questionnaire Data, Mineral Ownership Data, Field Examination Data and the continual updating of all information. Such studies are valuable for proposed or existing Wilderness Area Evaluations.

Jan 1, 1977

By D. W. Fuerstenau

The flotation behavior of quartz in the presence of alkyl ammonium acetates as a. function of alkyl chain length has been interpreted in terms of hemi-micelle formation at the solid-liquid interface. The van der Waals cohesive free energy that is responsible for hemi-micelle formation has been found from these results to be 1.02 kT per CH group. This 2 is in excellent agreement with literature values obtained from research on the properties of micelles in bulk systems.

Jan 1, 1964

By Andrew Allan

[The Thompson Creek Coal and Coke Corporation, a. mall company engaged in producing coal in the Rocky Mountains of Colorado, is currently engaged in a struggle of destiny to increase their production from inclined seam operation to compete with highly mechanized horizontal bed mines. This paper introduces some of the problems encountered it pitch seam mining as they apply to the convention, room and pillar system employed at the present time. Further described is the test work now being conducted to overcome these obstacles with an. attendant increase in productivity. Included in this test work is a mining machine designed especially for pitching seams, an automated longwall, and hydraulic mining of the latter compared with those of conventional work presently employed.]

Jan 1, 1965

By Karoly C. Kocsis, Kyle A. Scalise, Marcelo Bandeira Teixeira

Understanding the effects of various ventilation and climatic parameters on the work conditions and comfort in underground mines is critical for efficient ventilation system design and cost savings and to ensure the health and safety of mine workers. To understand the effects that the thermal damping effect (TDE) and the thermal flywheel effect (TFE) have on the ventilation system design and potential cooling system, this paper compares and analyzes the wet and dry-bulb temperatures at the bottom of an intake shaft using two modeling software packages, Ventsim™ and Climsim™. The comparison shows the consequences and importance of taking into account the TDE/TFE when predicting the climatic conditions in future underground mines, especially when deciding on whether a cooling system should be employed in order to provide adequate climatic conditions in the production stopes, dead-end development headings, and throughout the mine. Ventsim™is able to account for the TFE, while Climsim™does not. Both software packages have their uses and are used within the mining industry, but it is useful to understand their limitations and where the future of underground climatic modeling will lead.

Oct 9, 2020

By P. J. M. van Heteren

The flotation system is usually distinguished from other physical chemical systems by the importance of interactions at the solid-liquid and solid-gas interfaces. In recent years, numerous quantitative studies have been made of the distribution of common collectors between the solid and aqueous solution phase. Although in flotation the main emphasis is placed on the adsorption process, chemical reactions will also take place in the bulk solution phase, These side reactions are often undesirable and will contribute towards the complex behavior of many a flotation system In sulfide flotation, the precipitation of insoluble base metal xanthates is a well-known phenomenon although the conditions under which the precipitation reaction will proceed and the magnitude of the solubility products are not known with accuracy. A knowledge of the solubility of these xanthate salts will not only be of value in flotation research, but the mill operator might be interested in knowing whether precipitation of metal xanthate can be controlled or completely prevented in the flotation circuit thereby reducing reagent consumption, For these various reasons the solubility of lead, copper, zinc, and silver ethyl xanthate was determined. The experimental techniques and results will be discussed in this paper.

Jan 1, 1958

By A. Wright

Gold Fields Mining Corporation is presently evaluating gold mineralization beneath thick, wet alluvium at the Chimney Creek Project, Nevada. Contamination of reverse circulation samples has been visually apparent since drilling began in the area. Tests have shown that, while contamination can affect assays, reverse circulation holes appear to define mineralized zones almost as well as the diamond drill holes. To improve reverse circulation sample integrity several techniques were tried including a stiff-mud injection system but with limited success. Diamond core drilling continues to be used in conjunction with reverse circulation drilling to further delineate the mineralization.

Jan 1, 1991

By G. A. Plakhin, A. V. Luganov, V. A. Luganov, G. V. Gorbatenko

In order to extract gold from the complex sulphur-arsenic bear­ing raw materials and to remove arsenic and sulphur from the process in an ecologically safe form we have studied oxidizing roasting of highly arsenic gold bearing concentrates with soda, leaching of cinders, processing of the obtained solution and extraction of gold from the cake. There were processed concen­trates containing from 5 to 28% of arsenic, 12-20% of sulphur in the form of pyrite and arsenopyrite. The content of gold in the concentrates was 4-75 git. The roasting temperature was changed in the range of 773-l 173K, the consumption of calcined soda was 75-200% of stoichiometric necessarily for bonding of arsenic and sulphur into the water soluble compounds, the dura­tion of the process was varied in the range of 10-120 minutes. Under roasting in optimal conditions up to 97% of arsenic and 95% of sulphur go into water soluble compounds. The out­put of cake is 65-70% of the concentrates. The extraction of gold from the cake is higher than from the raw concentrates. The technology has been tested on a pilot plant scale

Jan 1, 1996

By Kathleen Kreiss, A. James Ruttenber

INTRODUCTION Early in the morning of July 16, 1979, there was a breach in the earthen retaining dam of a tailings pond at the United Nuclear Corporation's (UNC's) Church Rock uranium mill. The acidified liquid and tailings slurry spilled through the damaged portion of the retaining wall into an arroyo that is a tributary to the Rio Puerco river system. The Rio Puerco runs through Gallup, New Mexico, and eventually crosses the New Mexico-Arizona border (Fig. 1). On its way to Gallup, the Rio Puerco and its tributaries pass through land with a checkerboard pattern of ownership, with portions owned or leased by the Navajos, individuals, the Bureau of Land Management, and the State. In terms of tailings liquid volume (3.6 x 108L; 94 million gal), the UNC spill ranks as one of the largest. The mass of solids released in the slurry (10.0 x 105 kg; 1 100 tons) appears to be close to the median for accidents of this kind, however [U.S. Nuclear Regulatory Commission (NRC), 1979]. The UNC first opened its Church Rock uranium mill in 1977 on land adjacent to acreage belonging to the Navajo tribe. The mill, which is next to the UNC Church Rock mine, is located approximately 16 km (10 miles) northeast of Gallup, New Mexico (Fig. 1). Gallup, a town of 18 000 people, is the closest population center. The region surrounding the plant site is sparsely populated by Navajos, at a density of approximately 5.8 persons/km2 (15 persons/sq mile). The UNC mill and mines employ approximately 650 persons, and the adjacent Kerr-McGee uranium mine employs about 300. The UNC mill normally processes 3.2 x 106kg/day (3 500 tons/day) of uranium ore, depositing the acidified tailings slurry in a series of three earthen holding ponds. The tailings ponds are located east of the pipeline arroyo that feeds into the Rio Puerco approximately 2.4 km (1.5 miles) from the southernmost tailings dam. The liquid portion of the tailings slurry evaporates in the ponds; hence, under normal conditions, there is no surface flow from the holding ponds to the arroyo. Both runoff from the plant site after heavy rains and possible seepage from the tailings ponds may deliver radionuclides to the arroyo-river system, however. The dam across the southernmost tailings pond was considered to be in keeping with the state of the art. However, the New Mexico Environmental Improvement Division (NMEID) had warned UNC about dangers of locating the pond over a heterogeneous geological formation. The state Engineer's Office approved of the site only after UNC agreed to strict design criteria. Others have pointed to dangers of constructing earthen dams for impoundment of uranium mill tailings (Carter, 1978). Causes of the dam break were multiple: the UNC mill filled the tailings pond to a level that exceeded permit criteria; the tailings pond was lined improperly; the dam was constructed using clay that was compacted excessively, resulting in cracking and subsequent seepage; and the unstable substrate beneath the dam permitted differential settling. The UNC Church Rock mine has continuously released dewatering effluent into the pipeline arroyo at a rate of 88.3 L/sec (1 400 gal/min) since 1968. Before 1975 this effluent was not treated; after 1975 it received precipitation treatment for removal of Ra-226. Radionuclides are also released into the river system through the dewatering of the Kerr-McGee uranium mine 1.6 km (1.0 mile) north of the UNC mill. During usual mining operations, approximately 227 L/sec (3 600 gal/min) are released into the pipeline arroyo and subsequently into the Rio Puerco. The Kerr-McGee mine began continuous release of dewatering effluent in January 1972. In 1974 Kerr-McGee began Ra-226 precipitation treatment of its dewatering releases, but NMEID data indicate that treatment has often been incomplete. The effluent from both mines has been responsible for transforming the downstream portion of the Rio Puerco from a sporadically dry riverbed into a continuously flowing stream and has contributed to the current levels of background radiation along the river system (Table 1). This paper will summarize the postspill monitoring efforts and relate the assessment of this spill to the general question of evaluating the health effects of nuclear fuel-cycle wastes. The data pertaining to the measurement of radionuclides in the Church Rock environment and the radionuclide concentrations in animals will appear in forthcoming reports. CHURCH ROCK HEALTH EFFECTS ASSESSMENT APPROACH The initial health effects evaluation involved identifying the radionuclides that were released into the river system from the tailings pond. Table 1 lists the State of New Mexico maximum permissible radionuclide concentrations for liquids released to unrestricted areas, the typical tailings liquid concentrations, and postspill river water concentrations. The tailings liquid contained comparatively high levels of Th-230, Ra-226, Pb-210, and Po-210--all of which, according to postspill river water samples, had exceeded the state maximum permissible concentrations (MPC) at one time or another. After the radionuclides in the tailings were identified, pathways through which humans could be exposed were clarified. Environmental monitoring data were then used to quantify the important pathways of human exposure. Water samples were collected from the river, from test wells dug near

Jan 1, 1981

By M. M. Hajdasinki

A project's rates of return (RORs)1, be it the internal rates return (IRRs) or one of the many IRR surrogates, frequently needs to be approximated. The success and efficiency an ROR- approximation procedure depend on the quality the approximation-initiating parameters, such as bounds or seed values (guesses). The existing approximation procedures commonly use bounds and guesses suggested by intuition rather than supported by mathematical considerations. This paper presents three mathematically founded ROR-bounding and eleven ROR-guessing approaches and examines their suitability by using examples of typical project cash-flowpatterns (CFPs). The calculated bounds and guesses not only improve the approximation efficiency, but also allow the process of the ROR discovery to be automated, thereby making it more convenient and reliable.

Jan 1, 1999

By Paul L. Russell

Introduction As the US and world population increases, so does the problem of supplying expanding energy needs. Early requirements worldwide were mostly met by abundant forest vegetation. Man's large scale use of minerals-energy resources is a fairly recent development. It occurred only during the past 200 years. Coal was the first mineral fuel to be used extensively. It was not a large factor in US energy production until the beginning of the 19th century. Petroleum and natural gas use is about 125-years-old. Electricity generation by falling water is about a century old. Atomic energy is only about 30-years-old. Extensive use of it is still in the future. Solar energy is in its infancy. Other energy sources such as wind, peat, and geothermal energy are minor and primarily of local importance. There were three main features of the fuel supply picture during the past 125 years. By 1900 coal replaced wood as the principal energy source. Since 1900, oil and gas have captured many coal markets. And after the mid-1970s, there was a resurgence of coal usage. (Figs. 1 and 2). Wood Until the advent of mineral fuels for energy, the major global energy source was wood. But populations increased and became centered in towns and cities. The problem of a sufficient energy supply first developed as nearby, easily obtained wood was exhausted. This problem became more acute as industries such as shipbuilding, smelting, and pottery making, became more widespread. Results of wood use as an energy source and building material are starkly evident in areas of the world where civilization is oldest. Entire forests were consumed and have never been replaced. In the US, wood supplied 90% of all fuel requirements until about 1850; and more than 50% until after 1880. By 1900, wood still supplied 20% of all energy uses. In the mid-1970s, energy costs increased, due largely to the oil embargo. This increase resulted in an increased wood demand for domestic heating. While large quantities of wood were being used, its share of the total energy market was still less than 3%. By 1983, wood was becoming increasingly scarce and more costly near most large US cities. Wind Wind powered ocean vessels for many centuries. Sailing ships were still common in 1900. Windmills provided an early, cheap energy source and continue to be used today on farms. Design and development of windmills for electricity generation is being conducted. Interest in wind power is growing worldwide where availability of wind currents warrants the investment. Also, US regulation requires power companies to "buy back" electricity generated by windpower in excess of that used by the windmill owner. Coal By the 1600s, England was producing, 900 kt/a (1 million stpy) of coal for heating and other uses. The first coal-fired blast furnace for iron smelting was developed in 1621. Coke-making was developed in 1755, and Watt invented the steam engine in 1769. Illuminating gas made from coal was introduced in London in 1800. During this same 200-year period, France and Germany developed coal production, but on a smaller scale than England. US, bituminous coal was mined near Richmond, VA, as early as 1748. Major bituminous coal-producing states in the early period were Pennsylvania, Virginia, Ohio, Kentucky, Illinois, and Maryland. West Virginia replaced Virginia as a major producer, when that state was formed in 1863. As the US expanded west, new coal deposits were found and exploited. Indiana, Alabama, Tennessee, Iowa, Kansas, Missouri, Washington, Colorado, Wyoming, Arkansas, Oklahoma (Indian Territory), Montana, New Mexico, and Texas had significant coal mining operations by 1900. Today the eight major coal producing states are Kentucky, West Virginia, Pennsylvania, Illinois, Ohio, Virginia, Wyoming, and Montana. These states accounted for about 80% of all coal (lignite, bituminous, and anthracite) produced in the US during the past several years.

Jan 8, 1984

By E. F. Schnitzer, C. Lidstone, D. Cramer, P. J. Wampler

The River Island mining site is located at approximately river mile (RM) 15 on the Clackamas River, a large gravel-bed river in northwest Oregon. During major flooding in February 1996, rapid channel change occurred. The natural process of meander cutoff, slowed for several years by dike construction, was accelerated by erosion into gravel extraction ponds on the inside of a meander bend during the flood. In a matter of hours, the river cut off a meander and began flowing through a series of gravel pits located on the inside of the meander bend. The cutoff resulted in a reduction in reach length of approximately 1,100 m. Erosion by bed lowering, knick point retreat and lateral erosion of upstream river banks occurred quickly. Within two days of the peak flow, 3.5 hectares of land and 105,500 m3 of gravel were eroded from the river bank just above the cutoff location. Much of this gravel moved a short distance downstream into the excavation. Reach slope increased from 0.0022 to approximately 0.0035 in the cutoff reach. Between 1996 and 2003, the knick point from the meander cutoff has migrated 2,290 m upstream, resulting in increased bed load transport, incision, and local lowering of the water table. In 1993, prior to the meander cutoff, transects were surveyed in the River Island reach upstream of the cutoff location. Resurvey of these transects and aerial photo analysis indicates that 96% of the knick point migration occurred during the first winter following meander cutoff. Connection of the flowing river to the off-channel ponds has had minimal effect on water temperatures in the mainstem Clackamas River. It is likely that this minimal change in temperature will decrease as ponds are isolated from active river flow by gravel bar deposition. Fish net-ting in spring 2002, suggests that salmonid use of the pond in the spring is minimal. The most abundant native species netted were large-scale sucker and northern pikeminnow. The most abundant non-native species netted was brown bullhead. Early regulation by state and federal agencies did not adequately evaluate potential impacts to the river and the floodplain; nor did it evaluate future impacts related to geomorphic processes and sediment transport. New permit evaluation methods, currently implemented by both Oregon and Washington, incorporate 1) river dynamism through historic river migration analysis; 2) stability of human structures in light of river dynamics; and 3) sediment transport and its impact on channel stability and dynamics. The gravel pit capture at River Island highlights the potential risks of mining in an active secondary channel of a large gravel-bed river. Mining deeper than the depth of the adjacent channel, within the active migration zone, may increase off-site impacts. In locations where multiple gravel excavations are present within the meander zone, a comprehensive reclamation and restoration plan should be developed which provides long-term channel stability within the natural variability of the entire river reach.

Jan 1, 2006

By H. E. Rutherford

Monterey Coal Company has begun a geologic monitoring program in order to better understand our in-mine geologic conditions and to apply the knowledge gained to our mining operations. Two methods are used to collect information. The first is a monthly examination of conditions throughout the mine using a rapid mapping technique. The second is the detailed mapping of specific events encountered during mining such as faults and roof falls. The data gathered from both methods is correlated with operational statistics to create a geologic/production database. From the database, a monthly evaluation of mining conditions is made. Also, the database has proved useful in such areas as forecasting roof conditions and examining how faulting has affected mining operations.

Jan 1, 1984

By Haydn H. Murray

Since the advent of machine coated paper in the mid 1930's, the kaolin industry has had a remarkable growth, In 1935 the domestic production of kaolin was 500, 000 tons and in 1970 the estimated production was in excess of 3. 5 million tons. The process industries which use kaolin most extensively are paper, rubber, paint, ceramics, plastics, catalyst manufacturers, ink, and pharmaceutical. The paper industry is by far the largest consumer of kaolin using approximately 70 per cent of the total tonnage mined and beneficiated. Up until 1970 the major kaolin producers were able to expand rapidly enough to supply the demand but for the first time in thirty years the demand is expected to be in excess of mining and beneficiation capacity through at least 1975. The major reason for this is the expansion of coated paper production in Europe and Japan. Two areas supply the lion's share of kaolin for the world markets. These are the Cornwall area in extreme southwestern England and a limited area of Georgia and South Carolina in the southeastern U. S. The English kaolins are primary - (found in decomposed granite) whereas the Georgia-South Carolina kaolins are secondary - (found in lenticular, continuous beds in the Tuscaloosa formation of Cretaceous age. ) The English kaolins are mined by hydraulic methods whereas the Georgia-South Carolina kaolins are mined by dragline or shovel and benefidated by using a wet process for the majority of the production and/or a dry

Jan 1, 1971

By Milan Lipensky

This paper discusses the longwalling practices used at the San. Francisco Mine of Compania Minera Autlan in Mexico, in. the mining of a sedimentary, manganese deposit. Bethlehem. Steel Company is a part owner of this property. The San. Francisco Mine is located approximately 580 miles west of Mexico City, on the outskirts of the town of Autlan, in the State of Jalisco. The ore is shipped from the port of Manzanillo 120 miles southwest of Autlan. The mining method is a variation of the longwall retreat system, using friction. props that, until recently, had been used only in coal mining operations of Europe and the United States. However, due to the structure of the ore body and the modified longwall system that is practiced, there exists some unusual variations, such as: .1) friction props set by a mechanical two-step lifting device, 2) drilling and blasting, against the friction props, 3) a highly fractured and undulating, volcanic tuff roof; 4) displacement faults-up to 5 meters, and 5) a relatively stable, irregular floor.

Jan 1, 1964

By A. J. Basu

Computer assisted mine planning and design applications are routinely used by many Australian mining companies, However, the design process requires human expertise to recognize and evaluate the potential pitfalls. This paper introduces the application of a commercial optimization software (WHITTLE 4D) for strategic planning of an open pit mine in Western Australia. The authors present their experience in intelligent application of the optimization program while incorporating many technical and nontechnical obstacles. This paper provides some guidelines on how to apply the optimization software without loosing sight of practicalities. Moreover, this paper also shows how to build project evaluation guidelines for non-experts.

Jan 1, 1997