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By Lawrence M. Brennan

Early in 1971 the Peabody Design and Preparation group began engineering on a preparation plant which was to process eight mil- lion tons per year of raw coal. For the first five or six years this product was to be furnished 50% from surface mining operations and roughly 50% from underground operations. By early 1980, 1008 of the production was to come from underground mines. Because of the large annual commitment from Randolph Preparation Plant, it was essential that the plant operate with minimum down-time. As usual, capital costs were to be kept at a minimum. Before we discuss the details of design, it would be best to discuss the overall picture. Underground production to be pro- cessed through Randolph Preparation Plant was to be delivered by means of one mile overland conveyor from Baldwin #1 Underground Mine to the plant. Surface Mine production was to be delivered by means of 100-ton haulage units dumping in a 1,000-ton capacity hopper. Because of the changing production rates in both the underground and surface mines as well as the great difference in size consist, it was decided that it would be necessary to divorce the plant as much as possible from production. For this reason, twin 6,500-ton raw coal silos were constructed to separate the two coals as well as allow blending. The preparation plant itself, was to be designed to Operate two shifts per day, five days per week, at an average rate Of 2,200 tons per hour with a maximum rate of 2600 to 2800 tons per hour. Coal was to be delivered to our customers by means of rail haulage at both unit train rates and plant process rates. The surface mined coal, after discharging into the 1,000-ton R.O.M. hopper, is fed by means of two 72" wide reciprocating feeders onto a 72" wide steel cable belt. The steel cabled conveyor discharges the R.O.M. coal onto a fixed grizzly, scalping out a percent of the 6 x 0 coal. The balance is fed to a 12' x 27' Rotary Breaker. The material passing through 6" round hole screens is added to the 6" x 0" from the scalping screen. The 6" x 0" is conveyed to the top of one of the 6500 ton silos designated for surface coal. Material that is not broken to pass the 6" breaker screen is discharged to a bin and disposed of with plant refuse.

Jan 1, 1976

By John Kuyt, Zili Li, Michael Mooney, Michele Mangione

"INTRODUCTIONTwin bored tunnels are commonly used for a variety of road and tunnel projects throughout the world. A major component of these twin tunnel projects is the construction of connecting cross passages that provide emergency access between tunnels and space for tunnel service equipment. Cross passages can present significant geotechnical risk and technical challenges to a project – support systems must be considered for redistributing loads around the mainline tunnel openings and supporting new loading resulting from excavation activities. Additionally, cross passages pose risks to construction schedule and cost because of their sequencing at the end of construction, so mitigation of schedule overruns can be critical. By observing field instrumentation data records from completed projects, a betterunderstanding of the force development in each temporary structure can be achieved with indication of which structures are the most critical to support ground loads.This paper discusses the data obtained during the Brisbane Airport Link construction project, a road tunnel located in Brisbane, Australia. Strain gauge instrumentation data from the precast segmental lining and propped opening steel sets is presented with relation to the construction sequence and local geology. Interpretations and conclusions based on the observed trends are proposed, with several key mechanisms affecting the loading and unloading identified.Brisbane Airport Link Project OverviewThe Brisbane Airport Link project in Brisbane, Australia, connects central Brisbane to the airport located northeast of the downtown with over 7km of twin-bore road tunnels, two lanes each, with several caverns, interchanges, and access ramps constructed along the alignment to connect to other key routes in the city. The project was executed under a Public-Private Partnership (P3) scheme, funded and operated by the consortium BrisConnections. The main contractors were a joint venture of John Holland and Theiss, while the design was carried out by Arup and Parsons Brinckerhoff.Construction of the tunnels was conducted using a combination of 17 roadheaders and two 12.5m double-shield Herrenknecht TBMs [1]. The TBMs were used in EPB-type closed mode for the initial portion of their drive, starting at the northeast end of the alignment. Tunneling started in soft ground, weathered rock, and mixed face conditions initially, progressing to competent sedimentary rocks as the drive continued. Support was accomplished using a 12.1 m diameter steel fiber reinforced concrete (SFRC) segmental lining installed behind the TBMs in a 9 segments + 1 key arrangement. The innovative design of these segments is detailed in the paper by Harding and Francis [2]. Ancillary roads and underground interchange caverns were constructed by sequential excavation techniques using roadheaders, accounting for nearly half of the total underground excavations."

Jan 1, 2016

By R. A. Williams

Surface and electrochemical techniques have been used to describe the surface chemistry of ferrosilicon powders, as a function of pH and electrochemical potential, for conditions typical of operating DHS plants. The practical consequences on the likely corrosion behaviour and associated electro- kinetic particle-particle interactions (which affect stability to sedimentation) in the suspension, are discussed.

Jan 1, 1987

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

By Lj. Obradovic

The aim of this paper is to study the feasibility of copper and gold recovery from the old flotation tailing dam at Bor, Serbia. Laboratory leaching experiments were carried out using a composite sample taken by drilling from 16 - 40 m depth. Different oxidation agents as FeCl3, Fe2(SO4)3 and H2O2 were used. An H2SO4 solution with a pH less than 3 was used for leaching. The influence of a number of parameters on the recovery of both elements as temperature, pH, duration of leaching and concentration of oxidation agents was also studied.

Jan 1, 2006

By Ronald R. H. Cohen, Margaret W. Staub

Two pilot scale bioreactors designed to treat acid mine drainage primarily using sulfate reducing bacteria were constructed underground at the Eagle Mine Superfund site in Minturn Colorado. The project was designed to test th applicability of microbiological treatment on water with high metals concentration and to test the process in an underground environment. Objectives were, 1) to compare metal removal, pH increase, and sulfate reduction in a single stage reactor with a double stage reactor of equal volume at varying flow rates; 2) to determine where within the substrate treatment occurs· and 3) to examine volume versus surface ara as a design parameter for optimizing metal removal processes. Results from the reactors showed that the single stage reactor and double stage reactor performed equally well for the removal of Cd, Cu, Pb, Fe, Mn, and Zn. pH increased above 6.5 in both reactors. Greater than 97% of metals were removed within the first ten inches of substrate. Volume proved to be a more useful parameter for determining removal rates than area. Using volume as a design parameter rather than surface area enables PMDT systems to be constructed as packed columns rather than broad wetlands, Thus, space requirements are significantly reduced.

Jan 1, 1993

By J. Lovering, H. Wilhelm, P. Siewert

Introduction The Afton property is located 290 km (180 miles) by air east-northeast from Vancouver and 14 km (8.7 miles) west of Kamloops, a city of 60,000 people, in south central British Columbia, Canada. The mine is adjacent to the Trans-Canada Highway at an elevation of 670 m (2198 ft) above sea level. The ore body is a porphyry copper deposit that has undergone supergene alteration. The major economic minerals in the supergene zone are native copper and chalcocite with chalcopyrite and bornite in the hypergene areas. The grade is 1% with an overall copper distribution - 70% native, 25% chalcocite, and 5% chalcopyrite with bornite and covellite. The ore also contains important but variable amounts of gold and silver. The mill was designed to treat 6350 t/d (7000 stpd). Semiautogenous grinding was selected to minimize capital cost and because of the expected high clay content of the ore, which would have caused problems in a conventional crushing and screening plant. Test work indicated that a recovery of 87% was possible in a circuit incorporating both flotation and gravity separation. Flowsheet Run-of-mine ore is crushed in a 1.06 x 1.65-m (3.5 x 5.4-ft) Allis Chalmers gyratory crusher set at 228.6 mm (9 in.), closed side setting. The surge pocket, below the crusher, is emptied by a Hydrastroke feeder onto number one conveyor, which discharges onto a 180,000-t (198,416-st) coarse ore stockpile. Six Hydrastroke feeders on two conveyors withdraw the crushed material from the bottom of the pile. These two conveyors, in turn, discharge onto the belt feeding the semiautogenous mill. The live storage in the stockpile is approximately 22,000 t (24,250 st), sufficient for three days' mill feed. Primary grinding is accomplished in an 8.5-m (28-ft) diam by 3.7-m (12-ft) long Koppers (Hardinge Cascade) mill (Fig. 1) containing a 10% ball charge and driven by a 4000-kW dc variable speed motor. The mill dis¬charge is pumped by a 10 x 12 G.I.W. pump to a 1.22 x 4.88-m (4 x 16-ft) stationary screen sloped at 20°. Screen oversize returns to the semiautogenous mill (SAM), and the undersize flows by gravity to the ball mill discharge pump box. Secondary grinding is performed in a 5-m (16.4-ft) diam by 8.84-m (29-ft) Koppers overflow ball mill driven by a 3430-kW synchronous motor through an air clutch. The mill is in closed circuit with a Krebs Cyclopac containing 10 635-mm (25-in.) cyclones and the cyclone overflow, at 35% solids and 65% to 70% -200 mesh, is flotation feed. In order to limit the buildup of native copper, circulating in the secondary grinding circuit, a portion of the underflow from the cyclones is processed in a circuit containing screens, cyclones, and shaking tables to produce a finished metallic copper concentrate. Primary mill variable speed drive The overall waste to ore ratio at Afton was 4.5:1. The mining was to be done with only three shovels, which meant that it was highly unlikely that more than one of them would be in ore at any one time. The resulting inability to blend the mill feed made it impossible to prevent wide swings in the grade and grindability. The variable speed do drive motor installed on the semiautogenous mill was selected because of the extreme variability of the Afton ore body. This variability has persisted throughout the lifetime of the mine. There are times, however, when due to ore conditions, the mill is operated at full speed (78% of critical) for extended periods of several shifts duration. There are other times when the mill speed may be changed several times in a 12-hour shift due to changing ore conditions. When ore is processed that contains a fairly large proportion of fine native copper, the primary mill speed and, consequently, the tonnage may be reduced to improve the secondary grind and to maintain an acceptable grind and recovery. High clay ores require less mill speed and more dilute grinding densities. In the latter case, the slower primary mill speed also helps to minimize damage to the mill liners. Approximately 57% of the time the mill operates between 90% and 100% of full speed or between 71% and 78% of critical. The variable speed is also used for inching during mill relines.

Jan 1, 1987

By Howard J. Haselhuhn

The effectiveness of selective flocculation and dispersion processes for the concentration of hematite ore are strongly dependent on the ionic content of the process water. It has been noticed that magnesium ions are more detrimental to iron recoveries during gravity separation and flotation processes than calcium. This phenomenon was studied by measuring the zeta potential of hematite ore at various concentrations of sodium, magnesium, calcium, strontium and barium at a pH of 11. Results show that zeta potential inverts from negative to positive at concentrations as low as 0.16 mM of magnesium ions in the solution. It takes a significantly higher concentration (1.25 mM) of calcium ions to achieve the same effect. This difference is attributed to the ability of magnesium ions to adsorb to all surface hydroxyl groups, whereas calcium, due to its larger size, can only adsorb to every third hydroxyl group. This hypothesis was confirmed by results similar to those seen with calcium when this test was repeated with strontium and barium ions. The tendency for calcium ions to adsorb to every third surface hydroxyl group causes higher concentrations of calcium to be less detrimental to hematite concentration processes than magnesium.

May 1, 2012

By C. Pace, D. Darlington, A. Montera, C. Lingren

"A phosphate beneficiation plant in Utah is using isotope-based Prompt Gamma Neutron Activation Analysis (PGNAA) technology to analyze the entire slurry streams of the incoming feed and final product in order to adjust the flotation circuits in near real time and optimize the plant output. The plant has gained greatly improved visibility/control and has reduced product variability for improved profitability and product quality. This paper takes a look at the economics as well as application details and the difference this technology provides in a phosphate application. SIMPLOT PHOSPHATES INTRODUCTION Simplot’s Vernal, Utah Phosphate Mine and Mill are located in the northeast corner of the state in the Uinta Mountains along US Highway 191, eleven miles north of the town of Vernal. The phosphoric acid and fertilizer plant fed by the Vernal mine is located 94 miles Northeast of Simplot Phosphates in Rock Springs, WY.At the Vernal plant, loader and shovel mining to 85 Ton capacity trucks is done at an annual rate of 3.8 Million tons of ore. Run of mine ore is crushed in a mineral sizer to minus 14 inch diameter at the rate 11,500 tons a day and transported to the SAG Mill’s 130,000 ton surge stockpile by overland belt. ORE RESERVES The ore is a Phosphoria Formation of sedimentary rock type dating to the Permian Age. The ore body rests over a 25 mile area on Weber Sandstone from the Pennsylvania and Permian geologic period. Layers of Phosphate Rock can vary in thickness from 0.3 up to 2.1 feet, alternating with layers of Mudstone. The eastern edge of the ore’s body Panel “G” runs 16 feet deep with a feed grade of 21.5% P205 with lower MgO diluents of less than 2.79%."

Jan 1, 2016

By K. R. Price, M. Gauna

Jim Walter Resources No. 4 mine produces coal through retreat longwall mining at 610 to 670 m (2000 to 2200 ft) of depth. A three entry, total yield pillar, longwall development experimental region was established for three adjacent longwall panels utilizing 6.1 m (20 ft) wide gate section pillars. Presently, the first longwall panel is completed with roadway deformational behavior monitored for a ground control assessment of the mining system. Data illustrate that the total yield pillar gate section design at No. 4 mine is presently comparable to gate section designs having large equal size chain pillars. Ground conditions will continue to be monitored during the mining of subsequent longwall panels in order to determine the ground control implications from multiple panel extraction.

Jan 1, 1986

By R. M. Smailer

Detailed description of the development of the FIOR process1 and, subsequently, other technical papers relating to the operation and start up of the FIOR plant2,3 are available in the technical literature. The Fluidized Iron Ore Reduction (FIOR) process plant constructed in the Matanzas region of Venezuela represents the first commercial application of this technology. The FIOR process was developed by Exxon Company during the 1950's and 1960's; and the facility in Venezuela was designed and constructed by Davy McKee with the plant start up in 1976. While there is a minority government ownership in the company, FIOR de Venezuela operates as a private sector company with the majority of the ownership being private capital.

Jan 1, 1981

By Andrew P. Gize

The analytical approaches used to solve a specific problem are dependent upon the information required, coupled with limitations imposed by available facilities, costs, and time. The organic matter associated with ore deposits has the potential to yield information for two problems. Information can be obtained to provide guidelines for prospecting, and, secondly, to solve genetic problems. A major potential of organic matter in providing prospecting guides lies in the high thermal sensitivity of organic matter in sediments which are metamorphosed at grades lower than greenschist facies. The organic matter can then be used to map thermal anomalies potentially associated with mineralization. The analytical approach is to determine the thermal maturity of the total organic matter, or of specific fractions, using techniques which are relatively quick and inexpensive. Consideration of genetic models (for example, reduction, complexing, involvement of oil field brines) generally requires more specific information than the overall thermal maturity of the organic matter, necessitating infor¬mation on molecular composition and structure. The facilities, time, and cost of this information are greater than for mapping thermal anomalies. The analytical techniques discussed include elemental analyses, spectroscopy (infra-red, visible and ultra-violet), Fourier Transform infra-red, nuclear magnetic resonance, extraction, pyrolysis techniques, chromatography and mass spectrometry.

Jan 1, 2013

By Kostas Fytas

Canada still remains today a strong resource nation with a huge geological potential. Canada ranks among the top five leading countries in the production of 15 major minerals. Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mining Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage production. It is estimated that across Canada there are a few thousand abandoned mine sites as a result of the last fifty years of mining. Most of these sites are acid producing presenting a serious threat to the environment. It has been estimated that the cost of stabilizing and reclaiming these sites across Canada will be over $5 billion over the next twenty years. Current practices for decommissioning acid producing sites are water covers (flooding), dry covers, revegetation and treatment of the acid effluents. This paper presents the technical and legal issues of mine closure and reclamation in Canada. The methods used in the revegetation of acid producing mine sites is also presented This paper also reviews the financial guarantee requirements for mine closure by the provincial legislations in Canada. A case study of stabilizing and reclaiming a sulphide tailings area in the Sudbury region is presented. It illustrates the challenges facing the Canadian Government and the mining companies in restoring and revegetating the closed and abandoned mine sites across Canada.

Jan 1, 2002

By S. K. Kawatra, S. Valluri

With increased CO2 emissions from steel and coal industry, there is great opportunity to capture CO2 and utilize the captured CO2 for economic advantage. The primary goal is to develop energy-efficient processes that reductively couple CO2, an abundant and renewable carbon source, for the production of value-added chemicals such as methanol, ethanol, and oxalic acid. These chemicals can be used elsewhere in the refining process or sold as valuable by-products. Geological sequestration, in comparison, has no economic return. Current CO2 utilization research at Michigan Technological University focuses on electrochemical reduction of CO2. Electrochemical reduction of CO2 to hydrocarbons and other chemicals is a complex multistep reaction with adsorbed intermediates. The exact reaction mechanisms leading to various products are not clear from the literature to date and will likely change over the range of conditions like pH, electrode potential, electrolyte medium, catalyst, etc. This paper will present different ideas and their viability to utilize CO2 as a feedstock to produce several value-added compounds. INTRODUCTION Carbon dioxide (CO2) emissions into the atmosphere will need to be drastically reduced to curb the various undesirable effects of climate change. The large contribution in total CO2 emission originates from coal or natural gas power plants, and a considerable amount from steel plants. Average CO2 emissions in the US from steel industry is 2.9t CO2/t steel (Global CCS Institute 2013). Capturing the available CO2 from the steel and coal industries for economic advantage is a win-win situation for the industry. This technology is not only important scientifically but is also vital for a sustainable future. The various ongoing investigations can be categorized as biochemical, thermochemical, photochemical, and electrochemical approaches. Among these, the electrochemical method shows the most promise as an efficient form of CO2 conversion technology, because of its many advantages like high reactivity under ambient conditions and good extensibility from small- to large-scale processes1 BACKGROUND Extensive research has been done on the chemistry of transforming carbon dioxide into more useful products. Methods are known to convert carbon dioxide into a wide variety of substances, including methanol, isobutanol, carbohydrates, methane, carbonates, urea, formic acid, oxalic acid, carbon monoxide, epoxides, formaldehyde, and so on. Several of these (carbohydrates, formaldehyde, isobutanol etc.) are primarily results from biological processes. The rest are results of strong reduction reactions or electrolytic reduction. In short, electrolytic reduction can be used to form methane, methanol, formic acid, oxalic acid, carbon monoxide from carbon dioxide2. CO2 reduces at the cathode in an electrolysis cell. These processes have the general form of generating the carbon dioxide anion radical (2⋅−) and allowing it to react with itself or the electrolyte3. Catalysts can be added to influence the formation of the anion radical or to suppress side reactions3. The electrolyte, catalyst, voltage, electrode material and CO2 content are all known to effect the reaction pathway. Table 1 shows the overall reactions and energy requirements for electrochemical conversion of CO2 to chemicals

Jan 1, 2019

By P. M. Fozzard

The Chaucha porphyry copper/molybdenum deposit was discovered by a United Nations team of geologists working with a ?counter- part" team of staff of the Ecuadorian government's General Directorate of Geology and Mines (DDGM) in July 1968. The exploration program formed the latter part of phase I work plan of a two-phased exploration project financed by the United Nations Development Programme and initiated in late 1964. The author was a team geologist during the period 1965-1967 and subsequently project manager for the period 1968-1972. The Chaucha property lies some 10 km (6 miles) east of the north- south-running western boundary of what was known as Operation Area No. 5. This area of some 10 500 km2(4050 sq miles) is a square truncated to the southeast and centered on the city of Cuenca, the major provincial capital (Azuay Province) of southern Ecuador. The eastern half of the exploration area is dominated by the Cretaceous- Tertiary sedimentary valley (basin) of Cuenca (Caar-Azuay) and its related drainage area. The western half, in which Chaucha lies, is dominated by the high Cordillera Occidental volcanic plateau and the western erosional valleys of the Andes draining to the Pacific. The valley that dominates the eastern part of the area [I500 m (4920 ft) above sea level] is transected by the Pan-American Highway. Because of increased agricultural activity associated with the Cuenca Valley, the area is reasonably well covered by a road network of varying quality. The high western area up to 4000 m (13,120 ft) in altitude is largely barren and completely inaccessible by vehicle. The geological reconnaissance map of the region is shown in Fig. 1.

Jan 1, 1991

By P. H. Lu, M. J. DeMarco, J. R. Koehler

Beginning in late 1985 and continuing through 1987, US Bureau of Mines personnel investigated longwall chain pillar and entry design in two and three-entry gateroad systems at a deep underground coal mine in central Utah. To evaluate their respective stability characteristics, four chain pillars and two longwall panels within the two separate entry systems were instrumented with Bureau hydraulic borehole pressure cells to continuously monitor vertical and horizontal pillar and panel stresses through adjacent panel retreat. In addition, supplemental entry closure information was obtained from sites located in the vicinity of the instrumented pillars. The findings presented in this report demonstrate the practicality of evaluating mine pillar stability using in situ methods and support three significant conclusions regarding ground control aspects of the investigated two-entry system: (1) Total areal entry loading was considerably less for the two-entry system, as opposed to the three-entry system, (2) a smaller percentage of opened ground in the two-entry system contributed to a marked reduction in rooffalls, and (3) lower areal loading in the two-entry system suggests improved ground conditions when mining the underlying seam.

Jan 1, 1987

By N. Edmonson

An examination of the statistics of the world phosphate fertilizer industry since 1980 reveals an increasing tendency for fertilizer manufacturing activity to concentrate in phosphate rock mining areas. The economic justification for this resource-oriented strategy is clear. The choice between shipping phosphate rock, a comparatively low-value product, and shipping more valuable finished fertilizers will always be resolved in favor of the latter if cost considerations control the decision. The historical existence of substantial phosphate fertilizer manufacturing capacity oriented toward fertilizer-consuming activities and dependent on imported phosphate rock shows that narrow cost considerations have not always determined the industry's location. One is entitled to ask what conditions have changed to precipitate the observed relocations, and how permanent these changes are. These questions are the subject of this investigation.

Jan 1, 1995

By W. K. Tolley

The U.S. Bureau of Mines (USBM) is currently investigating the electrochemistry of mineral flotation. A significant need in this area is greater reliability of sensors. The USBM is testing electrolytic methods to clean and condition redox-sensing electrodes to improve the reliability and extend the service life of these instruments in the harsh physical and chemical environment of mineral processing slurries. A novel method for removing scale from fouled electrodes has been developed that includes anodic polarization to 1.2 V versus the Ag/AgCl reference potential, followed by brief potentiodynamic conditioning. Laboratory results show that this technique removes calcarious deposits from gold sensing electrodes and returns the electrode to useful service within approximately 10 min. Mechanical abrasion to remove the scale is thereby avoided.

Jan 1, 1994

By J. L. Chakravatti

The movement of air from the surface, through the workings and then back to the surface, is the most important consideration in the ventilation design. The purpose of mine ventilation is seen as the maintenance of acceptable atmospheric environments wherever men work or travel underground; and acceptability is related to the risk of harmful biological responses associated with exposure to atmospheric environments in mines. In mine ventilation, a design engineer often has to contend with a number of problems not experienced to the same degree in other industrial situations; i.e. the vast extent of many workings - offering continuously moving work locations; the difficulty of predicting. inflows of contaminants to the airways which contain the micro-environment; and especially, the effect of mining activity within the duct system (e.g. mine roadways) carrying the airflow. Mining of uranium does not differ, in many respects, from the mining of other metals; the ore must be drilled, blasted and transported from the mine. Underground mining proceeds by the continous development and advancement of a network of passages and rooms or stopes from which ore is excavated. As in most mines, rock conditions and ore grades in uranium deposits very from area to area and between different mines. 1 In uranium mining, in addition to eliminating noxious gases from blasting, diesel equipment exhaust, and the control of dust, it is also necessary to dilute and remove radon, the gaseous element in the uranium chain and its decay products. Long term epidemiologic studies of United States uranium miners and that of miners in Czechoslovakia have confirmed that there is an association between excessive ex¬posure to radon daughters and an increased risk of lung cancer. The common practices for controlling these airborne contaminants are: (1) the circulation of large volumes of fresh air from surface to dilute these contaminants to a permissible concentration, and (2) the sealing of worked-out areas to prevent ingress of radon into ventilating air. 2 The sealing of worked-out areas can be easily and effectively accomplished, but the contaminants intro¬duced from the workings may raise the concentrations in the airways despite a good ventilation system and use of the maximum available amount of fresh air. The ventilating air can be strategically filtered to reduce dust and radon daughters to acceptable levels, and reused prior to final discharge. This strategy properly applied, will decrease the air colume requirements in certain marginal areas of the mine and thereby avoid an overall increase in the mine airflow. This is particularly advantageous in the cold climates of Canada, where the incoming fresh air must be heated in the winter months to a comfortable temperature, Thus, an economical and technically feasible air filtration system, strategically placed, can improve the underground mining environment and reduce the overall cost of ventilating the mines. In addition to affording flexibilty to the venti¬lation system, a potential saving of $1,500/m3/s/year would be realized if air is successfully cleaned and reused when compared with the conventional methods of generating an air current. 3 Denison is justly proud of its achievements in the air filtration technology development. This paper limits itself to an examination of the radiation control aspect of the air filtration strategy.

Jan 1, 1980

By Leslie Thompson, Randy Hiebert, Marietta Canty

A paper is presented in which an innovative biological process is described for the treatment of cyanide-, metals-, and nitrate-contaminated mine process water. The technology is capable of detoxifying cyanide and nitrate and immobilizing metals in wastewater from agitation cyanide leaching as well as heap leaching. A pilot-scale demonstration is described in which a pilot plant was constructed to detoxify cyanide and immobilize several metals from a mine process wastestream at a mine in Nevada. The demonstration was performed jointly under the Mine Waste Technology Program (MWTP), which is funded by the U.S. Environmental Protection Agency (EPA) and is jointly administered by the U.S. Department of Energy's (DOE) Western Environmental Technology Office (WETO) and the Superfund Innovative Technology Evaluation (SITE) Demonstration Program under Interagency Agreement Number DW89938513-01-0. MSE Technology Applications, Inc. (MSE) located in Butte, Montana, was the contractor responsible for conducting the project, and Pintail Systems Inc. of Aurora, Colorado, was the technology provider. The pilot-scale unit was field tested at the Echo Bay McCoy/Cove Mine southwest of Battle Mountain, Nevada. The biotreatment process was con­sidered to be very successful in detoxifying cyanide from the mine process water. The process was also determined to be very effective in removing metals. The pH was consistently neutral­ized and nitrates were successfully removed in the mine process water. As a result of conducting these pilot-scale tests, the biotreatment process was concluded to offer an innovative, cost­effective alternative for the treatment of mining wastewaters.

Jan 1, 1998