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By Rollie P. Dobyns

The K.M.A. reservoir was discovered to be oil bearing at a depth of 3,719 feet on March 11, 1931. Extensive development, however, was not begun immediately, because the discovery well had a low initial daily oil production, and market conditions for oil were unfavorable. Development of the field progressed slowly for the next 6.5 years. In the latter part of 1937, a wildcat well approximately 2 miles southwest of the discovery well was drilled on a magnetometer high and completed with an initial flowing production of 2,018 barrels of 430 A.P.I.-gravity oil in 12 hours. Rapid development of the southwestern part of the K.M.A. field was begun immediately and continued until over 700 wells were drilled and approximately 12,500 acres proved oil productive. Because of the large size of the entire K.M.A. field, this report is limited in scope to the southwestern part only, and the discussion that follows pertains to this area only. The closing date for production statistics is August 1, 1949. The K.M.A.? structure is a complex anticline having a maximum closure of 250 feet, and the K.M.A. formation is composed of sediments that grade from limestone through sandy lime and limy sand to sandstone with thin streaks of shale. Two "distinct members of the K.M.A. formation, zone I and zone II, are oil productive. Core analyses indicate the average porosity to be 16.5 percent for zone I and 16.1 percent for zone II. A relationship was established from core data, which showed the correlative permeabilities to be 42.1 millidarcys for zone I and 39.5 millidarcys for zone II, whereas the arithmetical averages of the permeabilities were 84 millidarcys for zone I and 216 millidarcys for zone II. Connate-water saturations were 17.5 percent for zone I and 20.0 percent for zone II. The porosity-saturation method, using a thickness-correction factor, was employed to calculate the volume of 168.1 million barrels of stock-tank oil initially in place in the reservoir. Analyses of the reservoir oil indicate that, although the initial reservoir pressure was 1,750 p.s.i., the original reservoir oil was saturated to only 1,300 p.s.i., at which pressure 1 barrel of stock-tank oil contained 525 cubic feet of ea~ in solution.

Jan 1, 1952

By Wallace W. Key

Mineral raw materials produced in California, other States, and foreign countries were purchased for consumption in quantities valued at over $60 million at 800 of the 1,200 chemical plants operating in California Fn 1960, according to questionnaires completed by company officials. These and other data received from mineral consumers, producers, dealers, and Government agencies formed the basis for this the first of a series of reports designed to present the intricate features and relationships controlling mineral raw material supply and demand in California industries. The results of this study indicated certain changes in use patterns of minerals in chemical manufacturing; a shift in requirements from metals to nonmetals, from inorganics to organics, from natural to synthetic materials, and from distant to local sources of supply.

Jan 1, 1965

By Benedicto Hadad Cintra

In an inflationary environment the need for reduced cost is a daily concern of all industries. The Du Pont do Brasil "Expanded Pattern" method has proven to be an extremely effective means of reducing costs in mining, quarrying and construction operations. Over the past years much emphasis was placed on rectangular drilling patterns where the burdens are less than the spacing. The Expanded Pattern method combining rectangular and staggered patterns, was implemented in 1971 in Brazil after extensive trials in close collaboration with numerous explosives users and Du Pont do Brasil Technical Services Engineers. The best multiple row spacing-to-burden ratio (S/B) was demonstrated to be in the 2 to 5 range and the effective spacing to burden ratio (Se/Be) was found to vary from 5 to 11. These ratios are for the interior of the blast pattern and do not hold true along the front row of holes. Geological rock properties, hole diameter and inclination, explosives energy and loading density, explosives characteristics, blast pattern geometry, bench height and delay patterns along with type and size of digging, hauling and crushing equipment must all be evaluated for each and every operation. The integration of these interrelated parameters, together with sound blasting practices are the basis for the Expanded Pattern method. Color slides and documented case histories will be presented.

Jan 1, 1985

Mine rehabilitation is a sustainability issue that has been revisited ad infinitum; however, the persistent lack of demonstrated on-the-ground performance and an increasingly intractable rehabilitation liability in Queensland continue to erode the credibility of the mining industry and regulatory bodies. For at least ten years the need to change the current, process-based approach to rehabilitation to an outcomes-based approach has been apparent. The ISO 14001 series temporarily diverted attention from this important point, however it would appear the limitations of an ISO 14001 approach are now more widely accepted. It is proposed that a successful outcomes-based approach cannot be achieved without meaningful community engagement. The apparently intractable nature of the rehabilitation issue will continue to generate conflict and criticism unless all stakeholders are encouraged to participate in the process of developing robust and practical outcomes for rehabilitation. Sharing the responsibility will ensure the best possible outcome. It is important to recognise the valuable resources inherent in community groups, many of whose committed volunteers have considerable expertise in relevant areas. Community groups should not be seen as adversaries but as allies in the process of solving problems that affect the wider community. Several projects that can be seen as test cases for the engagement of stakeholders exist, and in this paper the process of achieving multiple stakeholder engagement in the context of Environmentally Sustainable Development is discussed.

Jan 1, 2002

By A. B. Cecala

Enclosed cabs have been used for many years to isolate workers on mobile equipment in the mining industry for health and safety reasons. These enclosed cabs create a microenvironment for workers where they can be either more protected or more vulnerable to contaminants. Over the past decade, the National Institute for Occupational Safety and Health (NIOSH) has performed substantial research efforts to improve the air quality inside enclosed cabs of both underground and surface mobile mining equipment. In these efforts, NIOSH has partnered with mining companies, original equipment manufacturers (OEMs), and manufacturers of filtrations and pressurizations systems in a synergistic effort to reduce respirable dust and improve the air quality inside these enclosed cabs. Various field studies over this time have shown an array of results ranging from very minor to very significant reductions (protection factor: 3 ? 89) in respirable dust levels inside these enclosed cabs. In addition to and concurrent to the field work, NIOSH also performed a comprehensive laboratory study to evaluate all the factors involved in cab filtration and pressurization systems and identified those factors that were most significant for an effective system. From this comprehensive research effort, the key components for an effective filtration and pressurization system have been identified in an effort to provide the best air quality, thus minimizing the respirable dust exposure, to equipment operators inside of enclosed cabs of mobile mining equipment.

Feb 27, 2013

By K. Meyer

"The largest cost centres of the David Bell Mine concentrator are grinding, leaching and effluent treatment. Optimizing results during the 6th year of operation are listed below: o SAG mill slurry density control and operating strategies improved liner life and media consumption by 10 and 25%, respectively.o Poly-met liners clad the SAG mill except for the feed end. Lower noise levels and reduced mill downtime have resulted in an improved and more efficient workplace (time required for liner changes is 2 to 3%).o A comparative grinding media study using seven different marked media at the same time showed media wear rates range 120 to 198 mg/kWh and ball mill charge replacement frequencies of 8.3 to 13.1 per year, and that a meaningful wear test must include all media to be tested at the same time in the same mill. High quality carbon steel cylinders had the best economics.o Pre-aeration, using pure gaseous oxygen is accomplished in pipe reactors. Small bubble generators provide oxygen in the first three leach tanks. 1500 to 3000 kg of oxygen is consumed per day. Leach kinetics have improved and trends indicate increases in gold recovery of three to seven ounces per day at reduced costs. Effects of reduced cyanidation of accessory metals on the effluent treatment plant will be discussed in a separate paper."

Jan 1, 1991

By William L. Husk

Stockpiles have always been a necessary part of coal mining except, perhaps, when a person was mining only for the needs of his family from a seam on his home place or coal mined for the use of a small hamlet and carried to each man's house as it was mined. Then it may have been stockpiled at each man's place for several days or on the village common. Mining with this limited production required waste stockpiling. Stockpiling of the products of coal mining, both coal and waste material, has always been a necessity. Very little coal has ever been moved directly or immediately from the working face to the point of consumption and burned. It has always been expedient to stockpile the coal some- where and store the waste.

Jan 1, 1981

By John P. Powell

The increasing demands for petroleum and its products and the steadily increasing cost of discovering and developing new oil fields are factors that emphasize the importance of increasing the recovery of oil from known petroleum reserves. Water flooding is a valuable conservation measure, not only preventing premature abandonment of stripper leases but also reviving interest in many areas previously abandoned. The use of water flooding as a means for recovering additional oil from partly depleted oil-bearing formations was first tried in Oklahoma in 1931. Early water-flooding operations were confined to the area of shallow Bartlesville-sand formations in Nowata and Rogers Counties, where many of the projects were outstandingly successful. The results of these operations stimulated activities in other pools in Oklahoma, and by the end of 1949 water flooding had been tried in 25 of the 49 oil-producing counties in the State (fig. 1). Approximately 33 million barrels of oil, or 1,806 barrels per acre, had been recovered by December 31, 1949, from 18,221 productive acres included in the 162 active and abandoned projects in Oklahoma by injection of approximately 449 million barrels of water.

Jan 1, 1952

The United States has not begun commercial operations to tap its largest poten-tial sources of oil supply - oil shale and coal. The reason is that domestic petrol-eum has been plentiful in the past and liquid products probably could be produced from it at the lowest cost. In view of the ever-increasing need for petroleum in the United States, the critical international situation threatening foreign supplies, the growing demands for steel, and the heavy costs to industry of constantly discovering and developing new oil fields, it is believed that the prompt development of a synthetic fuel industry based on oil shale and coal is not only requisite to safeguard our oil supply but is an economically sound course for the foreseeable future. To neglect its development is to close our eyes and minds to our own resources at a time when they are needed critically. It also is apparent now that neither the Government nor industry would be taking any considerable economic risk in starting the initial plants, especially as measured against their potential value in meeting critical oil and chemical demands and in building a new industry in the West.

Jan 1, 1951

By A. Brown

This report details work performed and results obtained in a study of the water management aspects of oil shale mining and retorting in the Piceance Creek Basin. Three specific sites were investigated, and optimal water management systems for both conventional and in-situ extraction processes were generated. Water-related legal and environmental constraints on development were identified and the water management schemes were developed in compliance with these regulations. Limitations on shale oil production implied by limited water supplies were evaluated. Potential Basin-wide effects of development were evaluated using a computer model, and mitigation strategies were developed. Recommendations for additional investigation and analyses were presented.

Jan 1, 1977

By Robert S. Schechter

A minitest, consisting of an injection/production well and at least two observation wells designed to detect the arrival of injected fluid leached minerals, and nonideal flow, is considered in this report. The test goals are to determine the susceptibility of the host formation to uranium leaching, kinetic parameters to scale the process, and to facilitate site restoration. This report considers permeability and mineral heterogeneities and other oxidant-competing minerals. To circumvent these nonidealities, which obscure the results, methods of interpretation have been proposed and tested by a computer simulator. In complex cases, clear-cut methods of interpretation were not found; but in every case the design of a test most susceptible to interpretation has been considered. The minitest is operationally simple and can be completed in a short time. With the correct design and interpretation it can return information to evaluate economics, ensure satisfactory leachate performance, scale to larger operations, and to identify restoration problems.

Jan 1, 1983

By J. Bongarra

This report describes the development of the instructional design and content of a training program for shaft construction miners and supervisors. The recommended training approach is based on the results of a needs, task, and competency analysis of the jobs performed by conventional shaft sinking and raise drill personnel. Learning objectives were derived from the task analysis and the appropriate training delivery system was chosen using a selection technique which employed learning algorithms. The training described is aimed at improving the safety and efficiency of constructing shafts by new hire and experienced miners and supervisors. A self-paced, self-teaching, modular approach to training, using criterion-referenced tests was proposed. Recommendation was made to divide the training into three parts: Orientation and Safety; Task Instruction; and Practical Exercise. Training requirements for conventional shaft sinking and raise drilling were described. Training program content was detailed in the form of module and lesson design approaches. In addition, the report recommends a method for developing, implementing and validating the training program. The authors conclude that such an implementation would meet the major objectives of improving the safety and efficiency of shaft construction work operations.

Jan 1, 1979

By William G. Hedling

The operation of electric face equipment in underground coal mines has proven to be extremely hazardous to mining personnel, including equipment operators and others working in the vicinity of active equipment. Recent industrial engineering studies* of accidents and fatalities indicate that a major contributor to this hazardous situation is noncompliance with modern principles of human engineering, particularly lack of standardization of control configurations. Control configurations differ not only among different machine types, but also among the same machine types produced by different manufacturers. This lack of standardization can produce a high incidence of error in the operation of electric face equipment, thus creating a potential source of accidents. Other examples of non-compliance with human engineering principles are the widespread use of identical black, round control knobs (regardless of the function being performed), and the inappropriate location, spacing, and labeling of controls. Any or all of these factors may place the operator in a "negative transfer" situation, which means that control manipulations appropriate for one type of machine are different from (or even the reverse of) the control movements required to produce the same effect on other machine types. This situation increases the accident potential to the operator, as well as to others in the vicinity. Accident potential is further increased by circumstances which do not allow for large error tolerance-specifically, emergency procedures. Reports of accident statistics cite operator inexperience as a primary cause of most accidents involving underground electric face equipment. Several factors contribute to operator inexperience, including: 1. High personnel turnover 2. Employee absenteeism 3. Current union practice of bidding for jobs.

Jan 1, 1974

By F. Heivilin

If the past is the key to the future, we will have ?tough? times maintaining Industrial Mineral reserves we have and proving new reserves around our plants and in new locations. The tough times will come from resources being more difficult to find, more hoops to go thru to make them Proven or Probable reserves. As always, Industrial Minerals require competitive quality, location, and costs. Since in most cases the market has suppliers, you will have to take away customers from their present supplier. This may take years or not happen even with lower cost higher quality raw materials. To determine the finished cost for a new deposit you need to design, determine capital costs, and operating costs for a new plant . Stripping, mining, hauling, processing, and transportation costs are part of the equation. After satisfying that your costs are in line you will need to do production tests to make sure the process works on the ore. You may want to complete permitting before purchasing the property. If you are new in the business you will have to prove you can deliver the right quality, the right quantity, on time consistently year after year at lower cost to take away a customer. Without being in the market this will be hard. The cut off grades to enter a market may be much lower than sale indicates because a competitor often lowers the price to keep you out of the market. We have many more items to check before the new deposits can be put on reserves. Our old reserves will require drilling to check for new products and prove that they do not contain items that would make them unusable for our product line or cause permitting problems. Archeological checks, wetlands, more water discharge testing, county zoning, and endangered species are among many items that have been added to mine permits. There will be more. A 4-6 page mining permit becomes 30-300 pages and consists of 5-15 permits, any of which might be a fatal stumbling block. It is not guaranteed that we can mine what we have on reserves. We may fight and lose. Oil-Dri?s loss in Reno and LaPort?s in England are examples where permitting failed. The NOx, sulfur, and carbon problems are just starting. Dioxin is in the background requiring monitoring on food products to Europe. What other anions, cations, endangered species, and land types are going to be problems in the future are guesses now. What new products are we going to have to test for and cause out of balance reserves? If there are none we probably won?t be here. We are competing for land use with ?Endangered Species?, wetlands, farming, forestry, cities, roads, and hunting. We?ve mined the best quality, low overburden, easiest to mine and process raw materials. The price of land and taxes are increasing. Old royalties are 2-3 times the present acre value instead of 8-10 times the property value when leased. Land taxes are up. It was and is best that we get the land in Fee Simple Title. This isn?t always possible. However, plants are closing and people have overlooked, made mistakes in drilling or interpretation of deposits. These may be opportunities. China is eating up high quality ?Industrial Minerals ?which have caused prices to rise. We may need to change our cutoffs? in terms of smaller pit sizes and higher overburden ratios. This is money in the bank. Overburden ratios and other items increasing cutoff costs need to be rethought. Suddenly doubling cutoff ratios for overburden and decreasing pit sizes are good alternatives to looking elsewhere where we might not be able to mine for a number of reasons. The higher prices make them competitive, especially when a competitor goes out of business. However, our low overburden ratios and short hauls around our plants are not safe from new roads, condemnation by county or city governments (N. J.), zoning changes (Reno, FL., CA, and environmental regulation changes (Buffers GA, MS). New roads ?Interstates? can take reserves, increase hauling distances and reduce tons per load. Let?s combine the Refractories, fullers earth, and bentonite industries and use the last 40 years as a guide to the future looking for problems and opportunities. Some or most of the following will apply to other minerals. WHERE DO WE LOOK? First, on our own properties, those next to our properties and on properties near our competitor?s plants. Where the profit margin has increased, the distance from the plant and thickness of overburden we can use is increased. The thickness of clay is decreased. For new locations we pick the ideal location and look at deposits and closed or open operations in ever increasing distances away from that location. We need to be aware of: 1. Increased transportation costs a. Access to Roads -Backhauls b. Haul with doubles and triples c. Railroads - Loading on sidings - Ability to get switches - Cars/backhauls versus rates 2. Cost of building a new plant 3. Cost of infrastructure 4. Cost of repair or new equipment when purchasing an operating or shutdown plant. 5. Local, state, and federal mine and environmental permitting. When exploring around an established operation expect that property acquisition, drilling, mining, stripping, and hauling costs will be greater due to them having second, third, or even fourth the pick of the deposits. I found this in New Jersey looking for refractories and around Quincy, Florida looking for attapulgite. You may be able to get some better properties because the operating company has angered some land owners, their drillers missed the clay, or the property wasn?t available when they were actively exploring for reserves. You may have some product lines your

Jan 1, 2009

By Marc R. Laflèche, Suzanne Paradis, A. Shirley Péloquin, Harold L. Glbson, Robin Potvin, Pierre Verpaelst

"The Archean Blake River Group is best known from a central volcanic complex in Rouyn-Noranda. This volcano-tectonic depression, delimited by the Hunter Creek fault to the north and the Horne Creek fault to the south, is interpreted to be a cauldron approximately 20 km in diameter. Its western and eastern boundaries are the Flavrian Plutonand the D'Alembert shear zone respectively. The complex has an exposed stratigraphic thickness of 10.5 km. Two cycles, composed of andesitic units overlain by bimodal, andesite - rhyolite units, are observed in the area, and are, in turn, overlain by an andesitic unit interpreted to be the lower part of a third cycle.The southern sector of the Blake River Group, south of the central volcanic complex, is considered to be outside the limits of the cauldron, but partly contemporaneous with it. The maximum stratigraphic thickness exposed in this area is 4 .6 km. At least two cycles occur in this sector. The oldest unit, a pre-cauldron andesitic to basaltic unit, occurs only in the southern part of the sector. In the north, two partial andesite - bimodal cycles, interpreted as contemporaneous with the cauldron volcanism, are observed.The eastern sector of the Blake River Group, east of the central volcanic complex, apparently overlies the complex. Two units are observed in this sector: a lower bimodal unit and an uper andesitic unit. The bimodal unit is coupled with the uppermost andesitic unit of the central volcanic complex to form a cycle, and the andesitic unit is considered to be the uppermost unit of the Blake River Group. The total exposed stratigraphic thickness in the sector is 2.5 km.The western sector of the Blake River Group, north and west of the central volcanic complex, is interpreted as the lateral equivalent of the complex. Three andesite - bimodal cycles are exposed in this sector, giving a total stratigraphic thickness of9 .5 km. The two lower cycles correspond directly to the central volcanic complex cycles; this correlation is facilitated by two stratigraphic marker units observed on either side of the Hunter Creek fault: the Fish-roe rhyolite flow, east of the Flavrian pluton, and a spherulitic rhyolite lapilli-tuff, west of the Flavrian pluton.Many of the volcanogenic massive sulphide deposits found in the central volcanic complex are spatially and temporally associated with synvolcanic faults, and felsic domes and feeder dykes that are the sites of felsic volcanism in the bimodal units. However, these features also occur outside the central volcanic complex, and the similarities recognized in this work between the complex and the surrounding area suggest that such deposits need not be restricted to the central volcanic complex. The presence of volcanogenic massive sulphide deposits outside the complex confirms this."

Jan 1, 1990

By S. K. Murphy

A partial shaft pillar extraction project was embarked on at a mine in the West Wits mining region in South Africa. Prior to the extraction, a rock engineering assessment was conducted with the main objective being to establish which areas of the shaft pillar could be extracted without unduly affecting the stability of major infrastructure within the shaft pillar. Standard numerical modelling methods were used to conduct this assessment and several areas were identified for extraction. However, during the extraction process, it was found that the infrastructure was affected more than was originally predicted by linear elastic modelling. In addition to this, several large events resulted in far more large aftershocks than would normally be predicted. In order to gain an understanding of this phenomenon, seismic data was integrated with numerical modelling as follows: > The seismic data in the form of displacements was integrated in 3D space within the model to assess the effect of static stress changes associated with seismic activity > Data from large events was integrated onto specific structures, where displacements associated with large events were integrated onto the plane of structure in question. This paper describes the methodology and results obtained from each of the above processes and include insights into the mining process that were previously unfathomable using standard linear elastic numerical modelling. The way forward for this rock engineering assessment of partial shaft pillar extraction is also discussed.

Jan 1, 2012

By R. E. Cerullo

Many computer programs have been written which are capable of performing a least squares fit, both linear and nonlinear, to data gathered by the petroleum researcher. However, when the petroleum engineer tries to program methods of analysis he has used manually in the past, such as forecasting production by decline-curve analysis, more than a knowledge of the use of existing least squares programs becomes necessary. It is the intent of the authors to report the techniques used in the development of such a decline-curve program.

Jan 1, 1970

By M Sandy, P Bamford

The Challenger Gold deposit was discovered in 1995 by Dominion Mining Ltd in a remote western area of the Gawler Craton in South Australia. Mine development commenced in 2002 with initial production from an open pit supplemented by ore from a very small adjacent auxiliary pit. Development of the underground mine commenced in 2004. The orebody plunge of just less than 30 degrees requires careful attention to mine design. Production from the M1 orebody, with less than 800 ounces per vertical metre (ovm) and very limited æsurgeÆ capacity, requires careful scheduling and implementation to ensure continuity of ore feed for milling. Initial production results from underground stopes included more dilution than anticipated. The narrow, high-grade zones proved to have much more complex geometry than early interpretations had indicated. Greatly improved understanding of the mineralisation controls resulted in important changes being made to the underground mine design and method. Coupled with careful control of development and drilling and blasting practices, this resulted in an immediate reduction in dilution and high recoveries of the resource. The benefits of these changes flowed through in the 2005/06 financial year, resulting in a 150 per cent increase in gold production to 108 080 oz and a sharp reduction in cash operating costs to A$280/oz. This was followed in 2006/07 with production of 108 91 oz of gold at an operating cost of $309/oz and in 2007/08 with 109 326 oz of gold at $367/oz. Production to June 2008 has been mainly from the M1 orebody, with the lowest stoping to date on the 580 m Level (615 m below surface) above development mining on the 520 Level. The rate of vertical advance of mining this orebody has averaged 150 vertical metres per year. The increased current combined JORC compliant resource and reserve position of over one million ounces, now includes the M2 and M3 orebodies with a current total average gold inventory up to 1400 - 1500 ovm. Exploration has intersected other shoots and all shoots are open at depth. The adjacent M2 and M3 orebodies are being developed for stoping. The narrow width of these zones from 1 m up to 4 m will require continued focus on ore zone definition, accurate development and careful drill and blast practice. In addition, to minimise cost increases in the current period of rapidly escalating labour, equipment, consumables and energy costs, high productivities will need to be maintained to allow the established rapid mining advance to continue at low unit costs.

Jan 1, 2008

By Don Stevens

The Denali Prospect (147° 08' 20" W, 63° 08' 50" N) is located on the south flank of the Alaska Range in the Clearwater Mountains in south central Alaska. (See Figure 1). The mineralization was discovered in 1963 and surface explora¬tion began the following summer. Surface trenching and diamond drilling were used to locate and sample the mineralized zones. In 1969, an adit totalling approximately 1400 feet was completed. In 1970, a -15% grade decline approximately 1800 feet long was completed. Further diamond drilling was done along with both underground programs. Although much work remains to be done to properly evaluate the prospect, results from all the work to date are quite encouraging. This paper will consider the geology of the prospect and the surrounding area, some- aspects of the geochemistry of the sulfides, and the origin of the sulfide deposits. This paper includes data from this writer's Ph. D. dissertation, "Geology and Geochemistry of the Denali Prospect, Clearwater Mountains Alaska" from the University of Alaska and subsequent work.

Jan 1, 1972

By J. S. Browning

Laboratory and pilot-plant tests of spodumene-beryl pegmatites of the Kings Mountain, N. C., area resulted in development of a new and improved method by the Bureau of Mines for separating and recovering spodumene, mica, and beryl. The process was successfully applied to other domestic pegmatites and a spodumene flotation-plant tailing containing about 0.5 percent beryl. The method comprised soap flotation of the spodumene, using combinations of sodium fluoride and lignin sulfonate as conditioning agents to recover 80 to 85 percent of the contained lithia in concentrates assaying over 6 percent Li20. About 80 percent or more of the beryl was retarded in the spodumene tailing. The beryl subsequently was activated, floated, and cleaned in a secondary circuit to yield beryl concentrates containing 6 to 7 percent BeO. The tests also demonstrated that a good recovery of high-grade mica could be produced.

Jan 1, 1961