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By Ioannis Nicolaou

This paper demonstrates the method of approach for the optimization of such filters. This does not only incorporate the proven and simple recently developed equations for the calculation of the solids throughput, the residual moisture and gas throughput, but also introduces equations for the calculation of the specific product costs for both vacuum and hyperbaric filtration under consideration of the influences exerted by the filter compressor and a possible thermal drying. An easy-to-use method is offered which incorporates a special graphic representation concerning the plotting of the target parameters in dependence of the pressure difference with which the optimal process pressure difference can be established, independent of the specific cake permeability or product fineness. Finally, the optimization method is exemplarily demonstrated for a concrete application.

Jan 1, 1995

By A. A. Kornyshev, M. Burstein, S. T. Hall

The surface "roughness" of mineral particles has long been known to influence the fundamental process of particle-bubble attachment and other subprocesses in froth flotation. The physical nature of the surface of fine mineral particles can be analysed by determining their fractal geometry. A number of techniques are available to measure the fractal properties of mineral particles, these include gas adsorption, mercury porosimetry, neutron or X- ray scattering and image analysis. From the resultant Richardson plots or their Fourier-space analogs, the fractal dimension of flotation feed and product samples can be determined. Textural characteristics of particles have an influence on the stability of 3-phase flotation froths and the selectivity of recovery in the froth. Decrease of the equilibrium froth height for particles of higher fractal dimensions was experimentally established. The induction time of quartz particles of different fractal geometry has also been studied.

Jan 1, 1995

By Ronald S. Conti, Harry Dobroski

Re1iabl e monitoring a1ong an underground mine belt line is of great concern because of combustibles, electrical apparatus, and friction. Belt entries are strategically located where a fire can have rapid and disastrous consequences. This paper reviews conventional distributed temperature sensing systems based on resistive, thermistor, and thermocouple effects. These are shown to provide limited benefits. A new system tested by the U.S. Bureau of Mines based on fiber optics and time domain reflectrometry, promises much better temperature and spatial resolution, faster response, inexpensive cable, longer distance, and comprehensive data analysis. Test results in a small, controlled, in-mine fire are given.

Jan 1, 1992

By S. Helgen, C. Byrns, A. Davis

The 4000 acre historic Robinson Mining District outside Ely, Nevada hosts a continuum of oxidelsulfide waste rock dumps of different ages. In an effort to develop a paradigm to explain past, existing, and future conditions at the site profiles of oxygen, pH, temperature, and specific conductivity were collected from various waste rock dumps using a hand-driven soil gas probe and a down-hole sampling device. The resulting data are useful in interpreting the fate and manner of pyrite oxidation within the dumps and in identifying waste rock dumps that may require remedial measures compared to those that require only minimal action prior to closure.

Jan 1, 2000

By C. D. Elifrits, N. B. Aughenbaugh

Laboratory tests of samples of fine- grained, argellaceous rocks, commonly referred to as shales, have shown that various changes in their moisture content can be correlated with loss of strength. This reaction to a change of in situ conditions at abandoned mine sites when combined with the field relationships at locations where the predominant overburden material is fine-grained, argellaceous, and fractured provides a predictive tool for engineers dealing with subsidence problems. Such a tool should enable engineers to recognize areas that are prone to be affected by surface disturbing subsidence features.

Jan 1, 1987

By R. M. Wheeler

For years the blasting industry has recognized eight milliseconds as the minimum delay time interval required between charges in order for them to be considered to fire independently of each other. However, computer analyses of seismic recordings made of several surface mine blasts reveals that this time interval may not always be sufficient for adequate vibration separation to occur. In some situations a combination of short delay periods and low frequency vibrations can result in waveform reinforcement. Various analyses of seismic recordings obtained from single hole detonations can be used to predict delay intervals that may enhance or reduce blast vibration effects.

Jan 1, 1987

By R. Mira, S. Rosa, P. Souza

This paper shows the historical data, local geology and mineralization, the mining methods applied, current production,, the planning staff, the resources of hardware and software available and the computer methods used. The activities are described starting with the driving of ramps/research levels, their dimensional parameters and positioning, driving of production sublevels with the same parameters plus those concerned with the stability of the rock mass during the development and the mining itself. Then, the detailing of the ore body is described together with the stopes planning, the openings stability analysis, and the drilling patterns and explosive types are discussed.

Jan 1, 1998

By Richard Lovat

INTRODUCTION Soft ground tunnels may be above the ground water table or they may be subaqueous. The ground may be clays, silts, sands, gravels, glacial deposits, boulder tills, and any of these in any combination. Because of the relatively low strength and deformability of soils, difficulties often arise in soft ground tunnelling. These soil characteristics and resultant tunnelling difficulties, have had a direct influence on the development of "Lovat" Tunnel Boring Machines. We have been required to recognize and adapt to unusual ground conditions and to follow through with design, fabrication, and field maintenance to ensure dependable, trouble-free operation. The basic "Lovat" machine is a fully shielded, wheel-type with the cuttinghead driven by a monorace type bearing with gear drive incorporated in the bearing. Mechanical innovations have been added to the basic machine which complement the resources of manpower, equipment, and materials available to the contractor for a specific operation. FULL FACE SUPPORT The installation of hydraulically operated closure doors or flood control doors, at the cuttinghead, is one of the early "Lovat" technical innovations. Flood control doors provide full face support in running or flowing ground. In water bearing sands and silts the excavated material can

Jan 1, 1981

By J. C. Harrison

When Exploraciones Eldorado, S.A. de C.V. finished their first phase of reverse circulation drilling at their La Trinidad property in Sinaloa, Mexico they began immediately with permitting and engineering activities. The first phase of drilling lasted four months and ended in April, 1994. The second phase of drilling ran from May through September of 1994. From May through December, 1994, Exploraciones Eldorado performed the permitting and engineering work for their La Trinidad heap leach mine. The mining permit was submitted to the regulatory agencies in February of 1995 and the first draft of the feasibility study finished one month later. The report outlines the permitting and engineering activities that took place during the second half of 1994.

Jan 1, 1996

By B. Pregerson, M. Gaft, J. Rabinowitz

The main phosphate minerals, apatite and francolite, are characterized by intensive selective photoluminescence, connected with impurities of Eu2+, Ce3+, V4+, Mn2+ and (UO22+ ). The non-uniform distribution of phosphate minerals in lumps makes photoluminescence sorting possible. As result, an intermediate product is recovered which is enriched by P205 and has relatively small amounts of chert, dolomite, calcite, fluorite, etc. In the case of Zin Phosphate Plant coarse rejects, for example, it is possible to separate a product enriched by francolite, practically free of chert and with a lowered calcite content. This material is suitable for flotation, with a potential 6-7 % increase yield of concentrate.

Jan 1, 1993

By A. Pradakar, J. G. Groppo, J. W. Leonard

All coal transportation systems from the coal face to the final point of use would become more productive if additional tonnages, obtained through improvements to bulk density, could be placed in fixed volume containers such as scoops, shuttle cards, trucks, barges and ships, as well as conveyors. This paper reviews previously reported work where the treatment of coals with small amounts of mining chemicals (0.12 to 0.28 kg/t or 0.25 to 0.56 lbs/st) during lavoratory testing was show to increase loaded coal bulk density by about 15%. The latest bulk density enhancement findings to develop from ongoing research involving underlying chemical and physical theory together with the added use of simple mechanical excitation are discussed.

Jan 1, 1995

By Stefan Gerl, Werner Stahl

Steam pressure filtration combines mechanical and thermal processes in one filtration device. Steam condensation at the cold layers of the filter cake, build a condensation front, which even removes the capillary water from the porous filter cake. Depending on the choice of parameters it is possible to achieve a very low residual moisture content. The influence of the parameters on the dewatering results was systematically examined on a bench-scale apparatus. This paper explains the physical fundamentals, the influence of the cake dewatering parameters, and one possible method of applying the process to a disk filter device as well.

Jan 1, 1995

By Myles P. Reilly, Randall A. Snowdon, John Temporal, O&apos

The paper describes studies made at the Transport and Road Research Laboratory, UK, of the mechanical cutting characteristics using disc cutters, of rocks with compressive strengths up to 340 MPa. These studies have been performed in both the single pass mode, where interactive breakout occurs between adjacent grooves on every pass of the tool, and the multiple pass mode, where several passes may be required to cause breakout. In addition, experiments to determine the effect on cutting performance of the hydraulic stiffness of tunnelling machines are described. The results of these tests are analysed and discussed in the context of the design of full-face tunnelling machines.

Jan 1, 1983

By D. Greene

The close integration of mine planning and mine operation continues to be the goal of mine operators. Depending upon the complexity, size and sophistication of the mine, limited success has been achieved in this area. Despite tremendous strides in the development of computer-aided mine planning, digital plans must usually be converted to error-prone paper maps and physical ground surveys for actual excavation and reclamation. However, advances in global positioning systems (GPSs), operator displays and mobile computers now enable equipment operators to work directly from on-board digital plans. A computer-aided earthmoving system (CAES) offers reduced survey costs, faster field transition time and improved excavation accuracy, coupled with faster, more informed decision making regarding key mining operations.

Jan 1, 2000

By Yongping Hu, Dianchen Cai, Congya Zhang

China is a rich in stromite mineral resource. Unfortunately, the resource is very difficult to separate by using conventional flotation method because stromite and gangue minerals are very fine disseminated, the average size of them is about 10 µm or below, and the content of clay minerals such as illite is 19% or even more. In this paper, the aggregation floatation behavior of ultrafine (-10 µm) stromite, illite, ablbite and quartz using anion collector were studied. The result show that, Oxidized paraffin (O.P) is a good collector and has better selectivity for stromite particles flotation. The salted sodium silicate depressed illite gangues minerals effectively. The separation of mineral mixtures was carried on successfully at one stage flotation by the technique. The mechanism of O.P. and salted sodium silicate were studied and discussed by using IR and Zeta- potential measurements.

Jan 1, 1995

By T. E. Garnar

Heavy mineral mining has been a small, but important Florida industry over the past sixty years. Early geologic history of each deposit is similar up to point of deposition in alluvium, deltaic sediments, or along shorelines. Later geological development through reworking and concentration is different for each deposit. The Trail Ridge deposit was formed by reworking Citronelle sediments of the Lake Wales ridge. Post depositional leaching of iron from ilmenite makes Trail Ridge an important source of titanium minerals for TiO2 pigment manufacture. Research leading to the separation and sale of by-product heavy minerals from Florida deposits has been important in maximizing profitability. Advances in mineral dressing technology will lead to future mining of lower grade reserves. Future needs for heavy minerals seem certain to expand, with increased activity in exploration and development of mining operations.

Jan 1, 1972

By J. J. Gusek, T. C. Richmond, R. W. Reisinger

A high-altitude (9,500-ft [2,900-m]) historic underground copper mine in Wyoming discharges neutral but copper-laden water into a pristine creek. Under a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) deferral agreement, the Wyoming Abandoned Mine Land Program performed site characterization and treatment studies in preparation for reclamation of the site. An integral part of the project included addressing the needs of a variety of interested and affected parties, including property owners, local populations, government agencies, and the media. This paper discusses an overall approach and specific methods employed to enlist public support for the project as well as some of the successes and failures experienced.

Jan 1, 2004

By Marcelino Cortina

It is known that underground bituminous coal mining in the Central Asturian Coal Basin (North of Spain) is a complicated task, due basically to the difficult geological conditions: thin and steep Seams with many faults and other disturbances. Therefore, it is not easy to decide what is the most suitable mining method for each of the seams, and problems in making the correct decision are encountered frequently. Because selections in the past have been inadequate an Expert System, ASTURLABOR;hulla, has been designed and will be developed' to provide accurate advice in the mining method selection process. The paper describes the major features of this Expert System and outlines the ASTURLABOR general project, which includes five other mining Expert Systems to complement ASTURLABOR-hulla.

Jan 1, 1989

By Armando Z. Remacre

The purpose of this paper is to attest the effectiveness of conditional simulation technique's for determining the principal pre-mining control parameters during mine planning. These parameters include: determining the selective mining unit size, the optimum pre-mining grid spacing and the number of mining faces to be used. The research work was developed in an iron ore deposit located in the Minas Gerais State, Brazil. Phosphorus was considered the master control variable for the research work. This paper provides the structural analysis (variography) , a description of the steps the were taken for setting up the numerical model, the kriging studies which were applied to the numerical model and the final optimum grid spacing, block size and number of mining faces.

Jan 1, 1992

By G. Brofas

The reforestation potential of bauxite mining spoils by seeding was examined on this research work. The experimental plot was established on the location Strofi Koukouvista 5, Ghiona Mountain. The experiment consists of 3 species (Pinus nigra, Robinia pseudoacacia, and Spartium junceum) with 4 sowing treatments and 2 sowing seasons (autumn and spring). The treatments were: (1) broadcasting; (2) broadcasting and soil cultivation; (3) broadcasting with straw mulching and straw binding with asphalt emulsion; (4) broadcasting with soil cultivation, straw mulching and straw binding with asphalt emulsion. Third year results show that spring is better than autumn as a sowing season. Only the Spartium junceum species were found to germinate and survive in autumn. The results are better for all the species on the spring seeding. The most effective treatments for Robinia pseudoacacia and Pinus nigra are 3 and 4 while for the Spartium junceum even simple broadcasting shows good results although the best ones are achieved with treatments 2, 3 and 4. The paper?s findings show that reforestation by sowing could be effective for some species but further experimentation with other species is recommended. Concerning Robinia pseudoacacia, testing of different seed preparation treatments is needed in order to maximize the germination of seeds.

Jan 1, 2002