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By B. T. Lu, J. L. Luo, T. Yu, C. W. Chen

In this paper, the synergism in erosion-corrosion process occurring in oil sand wastewater transportation caused by the interaction of mechanical and electrochemical factors was experimentally investigated. The erosion-corrosion tests were conducted with A1045 steel in synthetic slurries comprising tap water and silica sand. The material loss due to corrosion-enhanced erosion was assessed with the chemo-mechanical model developed by the authors recently. The results indicate that the material loss produced by corrosion-enhanced erosion at the open circuit potential can be formulated as a linear function of logarithm of corrosion current density. The wastage caused by the erosion-enhanced corrosion was analyzed based on the concept of non-equilibrium thermodynamics. The material loss induced by the erosion-enhanced corrosion is approximately a linear function of overall erosion rate measured in synthetic slurries, indicating that erosion-enhanced corrosion could be reduced by adopting surface strengthening techniques to improve the resistance to the plastic deformation in surface layer.

Jan 1, 2004

By Karl A. H iggins, James P. Racine

"Displacement Cast-in-Place (DCIP) piles are not a common deep foundation type in the Washington, DC Metro Area market. As a result, less regional data is available for these foundations compared to other alternate deep foundation types. Displacement cast-in-place piles (DCIP) differ from traditional Auger Cast-In-Place (ACIP) piles in that the pile annulus is formed by pushing a partially-flighted, auger bit to depth via a large mandrel. The auger bit includes a displacing body near the bottom of the tooling. Therefore, little to no spoils are generated during installation and the soil around the annulus is largely densified in-place due to the displacing body being slightly larger than the mandrel it is attached to.Due to this densification, one would expect that the theoretical DCIP capacities (compression or tension) would be greater than an ACIP pile (assuming a pile of similar length and diameter). After 20 static load tests and the installation of over 6,000+ piles on the MGM National Harbor Casino Project, the differences in pile support characteristics between DCIP and ACIP piles of same size and depth was small. The performance of both pile types depended on the density and type of soil within the bearing stratum. In some early cases of DCIP use, the performance exceeded expectations and appeared to be more in line (or better) than typical capacities obtained from driven displacement piles. Other times, the tip elevations could not be achieved or were so difficult to achieve that installation delays occurred and/or significant additional engineering effort was required to address piles short of their requirement embedment.This paper will discuss the limitations of DCIP pile installation in dense Coastal Plain soils and will present the lessons learned during this project. The paper will also compare the DCIP pile type to both conventional ACIP and driven displacement piles utilizing regional and site-specific load test and installation data."

Jan 1, 2017

By A. Sainato, S. J. Kravits, G. L. Finfinger

This Bureau of Mines report describes and compares the procedures, capital investments, and operating costs of rotary and in-hole motor drilling techniques used to drain methane gas from the Pittsburgh Coal- bed in an underground mine located in southwestern Pennsylvania. A timestudy was conducted during the drilling of each of two boreholes, and the data were collated to serve as a base for comparing drilling procedures and operating costs. Findings indicate that drilling with an in-hole motor offers four advantages over rotary drilling; namely, an increase in drilling productivity, fewer worker-hours required, ease of maintaining vertical and horizontal bit trajectory, and less expensive drilling cost per foot of borehole.

Jan 1, 1985

By J. A. Herbst, D. W. Fuerstenau

This paper examines the zero order production phenomenon in the context of the size discretized batch grinding model. A restrictive interrelationship between the selection and breakage parameters of the model, which is mathematically sufficient to ensure zero order behavior, is delineated. Based on this interrelationship, a scheme is developed for predicting the values of the selection and breakage parameters for all size fractions from a minimum of experimental data. To test this scheme, dolomite was ground in a laboratory batch ball mill. Successful simulation of the comminution behavior of this system was achieved using the batch grinding model with the parameter values obtained from the proposed scheme. Historically, a preponderance of comminution research has centered on attempts to relate breakage energy to the performance of comminution machines. Concomitantly, grinding data were interpreted almost exclusively in terms of inherently empirical energy-size reduction relationships1-3 or "laws of comminution"4- 6 which were based on highly oversimplified descriptions of the fracture process. In some instances, these relationships provide a crude basis for the correlation of experimental data, but, invariably, this approach is inadequate for meaningful process simulation. The control and optimum design of comminution circuits require a mathematical model capable of depicting the size reduction behavior of every size fraction for grinding conditions of technological importance. Energy-size relationships do not provide this detailed information. For example, an energy-size analysis for batch ball-milled dolomite has recently been completed in the authors' laboratories.7 This analysis provided a satisfactory correlation between the hypothetical size modulus, which characterizes only the finer portion of the size distribution, and the input energy. However, this relation did not constitute an adequate description of the complete system. In general, one of two distinct viewpoints toward simulation has been adopted in recent comminution research. The first approach focuses on the fracture of single mineral specimens, with the essential aim of representing the over-all process in terms of the breakage characteristics of individual particles and the characteristics of the stress field which the particles experience within the particular size reduction device. As illustrated by Harris's review,' the actual incorporation of single-specimen fracture information into a description of the behavior of a multiparticle comminution system has seldom been attempted. The only model to accomplish this incorporation was the one developed by Schönert.8 The Schonert model treats single-passage grinding machines in terms of a distribution of effective loads acting on a particle, a distribution of required particle breakage energies, and the breakage product distribution. However, the use of single-particle fracture behavior to derive models of the size reduction process is at present limited to machines in which the particle residence time is approximately equal to the time required to apply stress. As a result, Schönert's analysis cannot be used to advantage to simulate the complex environment which prevails within a tumbling mill. For multiple-passage systems a second approach to the description of comminution processes has been more fruitful. This approach entails the formulation of a mathematical model which is phenomenological in nature in that it lumps together the entire spectrum of stress-application events which prevail in a system under a given set of operating conditions. The appropriately defined average of these individual events is then considered to characterize the over-all breakage properties of the device. Thus, to analyze the performance of a tumbling mill, the manner in which the particles of a particular size (or size fraction) are stressed need not be distinguished. Instead, a single parameter is assumed to represent the resistance of that size to fracture, given the average grinding environment which exists in the mill. The isolation of such a parameter and a related set of quantities, which constitute the breakage product size distribution for the average event in this size fraction, allows the formulation of physically meaningful descriptive equations capable of yielding precise and detailed information for simulation.

Jan 1, 1969

By L. J. Murphy

The production of crude oil in the United States is exceeding consumption by one-quarter million barrels per day and, with the possibilities of West Texas, this condition of overproduction, unless controlled, is likely to continue for some time. The resulting low price of oil has caused the operator to observe closely his lease operating costs. The installation of more efficient and reliable machinery has followed and it can well be said that the art of producing oil is on the threshold of a new era. In this advancement electricity has played a leading part. This paper covers only the problem of electricity as applied to lease operation and does not consider other phases of the industry, such as drilling and pipe-line pumping, in which electric power has been utilized economically. In considering electrification of pumping wells, the first question the operator asks is whether or not his costs will be reduced and the second question is whether or not the production will be increased. The third question, although in effect it is closely allied to the first, is the cost of power. The last question can be answered only after a thorough analysis of operating conditions and a study of the power rates prevailing in the particular field under consideration. Within the past few years, the power companies have realized the desirability of a steady 24-hr, pumping load, have made their rates for oil-field service particularly attractive, and in general have shown splendid cooperation in assisting the oil companies in the satisfactory application of electric power to their leases. When everything is taken into consideration, the first cost is practically the same for electric drive as for gas engines when pumping on the beam with individual motors. This cost, at prevailing prices, should aver-age approximately $2200 to $2400 per installation when using 15 to 35-hp., two-speed pumping equipment, including motor and control, countershaft, motor house, belt, installation charges, and a prorated portion of the cost of transmission lines and transformers for serving a number of wells. Since there is practically no difference in the cost of the two installations, it is evident that electricity, to justify its consideration, must have a lower operating cost or produce more oil.

Jan 1, 1928

By Nam-Il Um

Bottom ash contains several ferrous materials (ferrous metals, Fe3O4, Fe2O3, FeS, etc.). In particular, ferrous metals contain heavy metal because Ni and Cr are chemically attracted to iron. Likewise, Cu is used to coat Ni and Cr metals as polish or to prevent corrosion. In this study, an Fe3O4-Fe2O3 double layer (similar to pure Fe) was found to have been formed in ferrous metal during air-annealing in an incinerator (1000°C). A strong thermal shock such as one that occurs during the water-cooling of bottom ash results in the breakdown of this oxidation layer, facilitating the degradation of ferrous metals and formation of corrosion products. Therefore, Fe-ion (heavy metal) oxides may be formed on ferrous metals and may be separated from bottom ash via magnetic separation. This study sought to investigate the separation ratio of heavy metals as magnetic separation and mineralogical formation of Fe-ion (heavy metal).

Jan 1, 2006

By M. A. von Below, I. C. Robinson

A mineral economic analysis of South Africa's mineral-beneficiation industry, comprising both economic theory and case studies, suggests that the domestic market has proved to be a more effective vehicle for promoting the establishment of advanced beneficiation projects than the availability of domestic raw materials. Although the domestic market plays an important role in the promotion of beneficiation by providing a secure outlet for sales, its most vital role is in the development of technological and marketing know-how that may give South African beneficiated products the competitive advantage required to penetrate export markets. The real wealth of a country lies primarily in the skills of its people rather than in its natural resources, and the domestic market plays a pivotal role in the development of these skills.

Jan 1, 1990

By D. Haraguchi, S. Izawa, C. Tokoro, S. Owada

"Arsenic is widely known as a toxic element for humans, animals and plants. Because of more stringent wastewater standards not only in Japan but also around the world, research for appropriate and efficient treatment method for arsenic is becoming increasingly important. Coprecipitation or adsorption process using ferrihydrite is widely implemented for dilute As(V) removal from wastewater. In this study, the sorption mechanism of dilute As(V) with ferrihydrite in coprecipitation or adsorption process was investigated. To accomplish this, we conducted batch experiments of coprecipitation or adsorption and compared these results for sorption isotherm and zeta potential. These experimental results showed that sorption mechanism in coprecipitation process depends on the initial As/Fe molar ratio; simple twodimensional adsorption onto the surface of ferrihydrite when the initial As/Fe molar ratio was < 0.4, and some three-dimensional uptake with ferrihydrite when it was = 0.4. We also evaluated the sorption mechanim by analysis of X-ray diffraction (XRD) and X-ray Absorption Fine Structure (XAFS). XRD or XAFS spectra showed that surface precipitation of amorphous ferric arsenate was formed when the initial as/Fe molar ratio was = 0.4, beyond the thermodynamic bulk precipitation range for ferric arsenate.INTRODUCTIONArsenic is toxic to animals, including humans, and long-term exposure to arsenic via drinkingwater causes cancer of the skin, lungs, urinary bladder, and kidneys, as well as other effects on the skin such as changes in pigmentation and thickening (Ghosha et al., 2008). Elevated levels of arsenic are often present in the environment as a result of the weathering and dissolution of minerals as well as in response to numerous anthropogenic sources including the discharge of mine wastes, coal fly ash and the use of pesticides that contain arsenic (Nriagu, 1994; Singh et al., 2007). Indeed, the potential for arsenic exposure affects many people, as evidenced by several million people in Bangladesh and India being at risk of exposure via drinking water obtained from contaminated groundwater sources (Ahmed, 2001).Acid mine drainage (AMD) containing arsenic is a global environmental problem (Dold, 2008; Liang and Thomson, 2008) that also affects Japan, which has many abandoned or closed mines that have been generating AMD for the last few decades (Masuda et al., 2008). Several such facilities in Japan produce AMD containing dilute concentrations of arsenic that exceed Japanese effluent standards (0.1 mg/dm3) (METI, 2006). For example, AMD from the abandoned Horobetsu sulfur mine, the largest AMD source in Japan, contains approximately 10 mg/dm3 arsenic."

Jan 1, 2012

By C. V. Millikan

New developments in air-gas lift practices in the Mid-Continent area since our Pall meeting in Fort Worth have done much to increase the efficiency of installations, and thus bring within economic limit of air-gas lift many wells which could not have been flowed profitably before. After the gas-lift had so thoroughly demonstrated its value in the Seminole field, its use spread to other areas and many installations were made of which the economy could be questioned. In the Seminole area, when production began to decline it was necessary either to increase the efficiency of the air or gas-lift or to put the wells on the pump, and pumping was not a process of lifting oil to which any operator looked forward with confidence. These conditions have resulted in the development of many practices which increase the efficiency and permit wells to be flowed with air or gas which earlier could not have been flowed economically, and wells which have been flowing to continue to a lower rate of production. The practices which have come into more common usage in the Mid-Continent area recently are mostly revivals of and improvements on practices which have been known in air-lift work for several years. Many arc peculiar to the individual well on which they are used. Intermittent Flowing Some interesting results are being obtained in Seminole and other districts by intermittent injection of gas. Gas is introduced during per-iods iods of 3 to 5 min. at a rate considerably over that necessary to acquire the production at a steady rate of injection, and is then cut off for a period of 3 to 15 min. Two to five wells are run from the same group of conlpressors. The total volume of gas required is sometimes reduced as much as one-third of that required when it is introduced at a constant rate, without changing the amount of oil production. The maximum pressure required is usually higher, but the average equal to or lower than that required for constant rate of flow. The effect on the wells is usually an irregular rate of flowing which may cause inconvenience where recycling is practiced. It would seem that this increase in efficiency is due to less slippage when the gas is introduced intermittently than when it is intro-

Jan 1, 1928

IN general in making such powders, all kinds of gravel, tuff, washed river silt, and similar earths whose grain is fine and lean by nature are good for this operation of casting, either by themselves or in mixture because they are disposed to receive the metals well on account of a certain dryness which they possess. Many kinds are also compounded by means of art. Of these, I shall proceed to tell of all those that experience [119] has taught me to recognize as good. But first I desire that we return to speak of the natural ones because they are real earths and can always be had wherever one may be, and in the necessary quantity. They please me greatly because they are easy to reduce on account of their disposition. A loam is made from these and mixed by beating with wool-cloth cut- tings, spent wash ashes, and horse dung. This is made into cakes and dried. These are then put to bake in a furnace or in some other way and, in fact, are baked very well. Then it is pounded and sifted with a fine sieve, or it is ground in a potter&apos;s color mill, or by hand on a porphyry with water, to the fineness that the craftsman desires, or as fine as he can make it. When it has been ground it is again drained free from water and dried out with fire. Then as much magistery of salt is taken as will moisten it. It is dried and pounded again and passed through a sieve. When it has been made as desired in this way it is moistened again before use with water, urine, or vinegar just enough so that it holds together when it is squeezed in the fist. Then, when it has been brought to this point, it is moulded as you will hear. Powders are also made of crushed brick, tripoli, vine ashes, tiles, and glazed drainpipes, or burned emery, calcined tin, straw, and of burned paper and horse dung as well as of young ram&apos;s-horn ashes and many other things. The goodness of all these depends on three things; namely, on receiving the metal well, on being so fine as to be almost impalpable, and on their being made .with a magistery that renders them hard and strong when they are dry. In addition to these powders I have used another when I needed it, and it has succeeded well every time I made it. To make this. I have taken I two parts of pumice and one of iron scale and ground them on the por-

Jan 1, 1942

By William J. Gregg

Mechanical testing results on oriented Devonian gas shale core throughout the Appalachian basin show a preferred fracture direction perpendicular to bedding. The preferred direction is generally parallel to the Allegheny Front, but is only coincidentally parallel with in-situ stresses in some areas of the basin. The strength of the preferred orientation of induced fractures decreases with distance from the Front. It is suggested that strain related to Paleozoic deformation is responsible for this mechanical fabric and thus the direction of induced fractures in laboratory tests may not be of use as indicators of in-situ stress orientations as previously suggested.

Jan 1, 1986

By Mark R. Stanton

Geochemical and mineralogical analyses of 46 samples from six drill cores in the Mayday mine pile near Silverton, Colorado, demonstrate wide variability in trace metal contents with spatial location. This variability results from the original geochemical composition of mined rocks, mixing of ore and non- ore rocks during emplacement of the pile, and weathering since rocks were placed in the pile. Weathering reactions are controlled by factors such as pile thickness (depth), water availability, microbial activity, and mineral dissolution and formation kinetics. These factors result in variable redistributions of trace metals from primary (ore) to secondary (weathering products) minerals within each core.

Jan 1, 2000

By D. Gaboury

Most hydrothermal gold deposits contain quartz with fluid inclusions that record composition and temperature of the mineralizing event. Quartz has strong chemical and mechanical resistances to weathering and abrasion. Hence, quartz fragments occurring on weathered surfaces or in till cover have the potential to be used for gold exploration as far as we know what is the signification of the volatile content of the fluid inclusions for gold mineralization. In this perspective, fluid inclusions were analyzed in pure quartz by solid-probe mass spectrometry from gold deposits hosted in the Archean Abitibi (Canada) and Paleoproterozoic Birimian (Western Africa) belts. This approach provides the relative abundance of volatiles from families of fluid inclusions decrepitating at specific temperatures (Td). Fluids in gold deposits are aqueous-dominated with CO2 and minor H2S in accordance with their fundamental role as gold-ligands (H2S) and for pH-buffering (CO2) of the gold-bisulfide solubility. However, there is no correlation between CO2 and H2S contents of fluid inclusions with the gold grade of the samples. This suggests that trapped fluids represent a marginal portion of the fluid history recorded by the veins. However, in barren quartz veins away from known mineralization CO2 or H2S are commonly absent. Wide ranges in H2O Td from 250 to 450°C and CO2-H2O Td offsets are common, indicating phase separation. The content of other volatiles seems to be more dependent on the geological setting. Helium content may suggest proximity to a crustal-rooted fault, a critical parameter for gold mineralization. Methane and especially C2H6 appear to be indicative of fluid buffering by organic-rich material such as graphitic-shale. These rocks may provide an important primary gold reservoir from sedimentary metal-rich pyrite. Nitrogen-bearing fluids may be related to a magmatic component but can also be derived from organic-rich sedimentary rocks. For gold exploration, quartz containing CO2- H2S-bearing fluid inclusions and having H2O-CO2-Td offsets within 250 - 450°C has strong vectoring potential.

Jan 1, 2011

By J. F. Whelan, B. D. Marshall, Z. E. Peterman, J. B. Paces, L. A. Neymark

Observations of calcite and opal in cavities in the unsaturated zone at Yucca Mountain indicate that: 1) seeps are not regularly spaced in underground workings and not all fractures sustain flow, 2) many cavities represent sites of seepage that have remained stable for millions of years, 3) typically there is no evidence (such as dripstone) for seepage dripping into cavities from their ceilings, and 4) seepage is not likely to be greater than about 1 liter of water per year (per 5-m-long drift) based on calcite abundances observed in the ESF. This estimate of seepage is significantly lower than that used for performance assessment.

Jan 1, 2000

By John E. Anderson, Charles A. III Cravotta, Eleanora I. Robbins, E. Terrance Slonecker, Gordon L. Nord

Remote sensing is being tested for its ability to identify the severity of impact on streams that are subjected to contaminated mine drainage (CMD) in the Southern Anthracite Coalfield of Pennsylvania. Airborne digital multispectral video images of acidic and near-neutral CMD are being compared with field spectra, water chemistry, mineralogy, and microbiology. Spectral differences in the visible region of the electromagnetic spectrum are caused by the presence of schwertmannite in the acidic precipitates and ferrihydrite in the near- neutral precipitates. The acidic CMD averages 1,500 mg/L sulfate and has bacteria coated with schwertmannite; the near-neutral CMD averages 87 mg/L sulfate and has bacteria coated with ferrihydrite.

Jan 1, 2000

By K. J. Powers

The Mine Accident, Injury, Illness and Employment Database at the Mine Safety and Health Administration&apos;s Health and Safety Analysis Center is a computerized system that stores accident, injury, illness and employment data about all coal and metal/nonmetal mines in the United States. The paper discusses the system for collecting, storing, analyzing, and reporting this information and how these data are used in the ongoing effort to increase the health and safety in this nation&apos;s mines.

Jan 1, 1983

By J H. Baker, P G. Beadle, J P. O&apos, Brien

In 1974 a preliminary study of the refractories industry in theRepublic of Indonesia was completed by Crown Lynn Consultants, a subsidiary of Cerarnco Ltd., on behalf of the Indonesian and New Zealand Governments. As a result of recommendations arising from that study the two Governments commissioned, in 1976, as a Bilateral Assistance project, an investigation into the potential of the refractories industry in Indonesia. Ceramco Ltd., was retained to carry out the study on behalf of the New Zealand Government. The Directorate-General of Chemical Industries, Directorate of Silicate Industries administered the project on behalf of the Indonesian Government. Indonesian counterparts to the New Zealand study team were provided by the Directorate of Silicate Industries.

Jan 1, 1978

By C. C. Clark, P. W. Patton, B. M. Stewart

Handling materials in underground mines continues to be a major safety problem. To help reduce materials-handling injuries, researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are investigating those materials-handling tasks in underground mines that appear to generate a high number of injuries. Data from the Mine Safety and Health Administration for the years 1989-1999 were studied to find out if there were any trends in materials-handling accidents and if so, to determine what tasks were involved and the sources of injuries. Several underground coal and metal mines were visited to document innovative materials-handling technologies. Considerations for safety training and mechanization needs for continued reduction in materials-handling injuries are described.

Jan 1, 2002

By Tim Neil, O&apos

The coming years should see moderate growth in the US coal industry. That growth may come at the expense of the oil and natural gas industries. Conoco pegs coal growth at 2% a year, until the year 2000. During that same period, Conoco projects only 0.5% annual oil growth and "a flat or negative trendline" for natural gas. This is compounded by the fact that coal has a delivered cost per Btu that is only half as much as it is for natural gas and only a third as much as it is for oil. So said Ralph Bailey to many of the 2600 attending the opening session of the American Mining Congress Coal Convention, May 12-15, in Pittsburgh, PA. Bailey is chairman of the AMC. He is also chairman of Conoco. While coal&apos;s projected growth is not spectacular, "it is in fact almost an assured growth," Bailey said. Weak oil and gas prices will likely prevent faster growth for US coal. Most of coal&apos;s increased demand will come from the electric utility industry and expanded steam coal exports. Conoco&apos;s study projects that domestic coal demand will be strengthened in the 1990s. By then, the present surge of nuclear power plant constuction will be over. And there will be a lack of acceptably priced, large-scale generation alternatives for utilities. "It is not likely that any electric utility is going to be ordering new nuclear reactors," Bailey said. "And as oil and gas supplies become scarcer and more costly, it is only logical that coal is going to fill the gap." At the same time, Bailey believes the US coal industry must find ways to lower its costs. He said cost excesses can be found in "regulatory overkill, labor, and simply bad habits" hidden by years of high inflation. "Those costs have now been laid bare, because we are going through a pe¬riod of disinflation. We have to put our house in order, particularly if we are going to compete in world markets." Bailey also touched on coal research. "The industry certainly accepts the fact that we must find a way to burn coal as cleanly as possible. A lot of work in that regard is going on. I expect there will be some significant break-throughs." Bailey said the coal industry is being squeezed this year. Last year, coal customers accumulated inventories in anticipation of a major coal strike that never materialized. Now, many utility customers are working down these inventories. So they are not taking deliveries on their coal contracts. But coal use is up in 1985, compared with 1984, Bailey said. So increased coal use, along with supply drawdown, should strengthen the coal market before the year is out, he said. After Bailey&apos;s presentation, some 100 speakers addressed policy and technical topics at 15 sessions during the four-day meeting. It was the first time since 1977 that the AMC Coal Convention has been held in Pittsburgh. And this year&apos;s attendance was up 40% from the last AMC Coal Convention held two years ago in St. Louis, MO. This year&apos;s registrants included 228 companies, 225 manufacturers, and 106 associated members. The only negative was the David Lawrence Convention Center. It was less than ideal. By turns, meeting rooms were too small, too cramped, or too far from one another. The session on longwall mining was so crowded that the doors were propped open so conference delegates could peer in. A concurrent manufacturers&apos; forum session needed 50 more chairs to accommodate those wanting to attend. However, on to summaries of some of the presentations. Coal transportation and export Since Congress approved the 1980 Staggers Rail Act, railroad rates for hauling coal have not been excessive. In fact, rail rates for coal have increased less than 0.5% a year, in real terms, since 1980. Moreover, the market oriented principles written into Staggers are contributing to the improved financial and operational health of the nation&apos;s railroads. But no railroad is earning excessive profits. That is the gist of a coal transportation study being completed by the US Department of Energy. William Vaughan is DOE&apos;s assistant secretary for fossil energy. He affirmed the thrust of the upcoming report. Vaughan did allow that Interstate Commerce Commission (ICC) regulations on rate reasonableness could permit the railroads to exploit their monopoly power on captive shippers. Luncheon comments later made by Don Hodel confirmed Vaughan&apos;s comments on railroad rate justification. Hodel is Secretary of the

Jan 7, 1985

By M. Kuyumcu

With annual production of almost 3.5 million metric tonnes of K20, former East Germany (GDR) was the world?s third-largest producer of potash, ranking behind only the Soviet Union and Canada. More than 80 % of production was intended for export to earn urgently needed hard currency. For this reason, beginning in the 1970s, East Germany began to mine unprofitable hard-salt sources and carnallitite fields, which are geomechanically problematic. In the course of restructuring from a centrally planned to a market economy after German reunification, only two of the nine existing potash mines were classified as economically viable for privatization. All six potash mines in the South Harz Region were closed between 1991 and 1993. The orderly safekeeping of these potash and other decommissioned ore mines and the rededication of mining areas were assigned in 1992 to a German state-owned company GVV founded especially for this purpose. Elaboration in the present documentation covers the local necessity of the type and extent of filling and safeguarding measures. As a result of the remedial measures taken, it was possible to prevent the collapse of cavities and damage to surface facilities. This documentation describes the safeguarding successes to date, with appreciable reduction and stabilization of surface settlement and with significant lessening of seismic events. Also presented are concepts updated to the state of the art for safeguarding of numerous potash mining shafts for long-term effectiveness in separation of the workings and watercourse levels in the cap rock. In the course of 100 years of production, six mining dumps resulted with a total volume of approximately 170 million m3. They consist of up to 95 % of water-soluble salts. Every year, precipitation dissolves up to 500,000 tonnes of this salt, which enters as a highly concentrated solution into watercourses and ground water. Explanation follows of measures for minimization of environmental pollution by covering of dumps and controlled drainage of alkaline solutions from the dumps. Finally, presentation is made of the results of the successful work until now by GVV for reuse of decommissioned mining sites with settlement of new companies for creation of additional jobs and for revitalization of the monostructured South Harz Potash Mining Region.

Aug 1, 2013