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By R. Q. Phillips

INTRODUCTION Since Canada commenced sulphur exports in the early 1960's, the volume of exports has grown steadily and by 1984 Canadian sulphur accounted for 45% of internationally traded sulphur. In 1984 a total of 7.6 million tonnes of Canadian sulphur was shipped to offshore markets and the U.S.A. Total shipments, including domestic sales, were 8.3 million tonnes. With a production of some 5.6 million tonnes, inventory was drawn down by nearly 3 million tonnes in order to keep pace with demand. Since 1979, world consumption has exceeded total world production and Canadian sulphur inventory has played a truly crucial role in balancing world supply and demand. Consequently, by the end of 1984 the Canadian inventory, which stood at 21 million tonnes in 1978, had been almost halved to 12 million tonnes. This inventory, however, is still by far the largest in the world and will continue to play a vital role in the world supply until expected depletion around 1990. Canada is the world's second largest producer of sulphur following the U.S.A.. The Current production level of between 5 and 6 million tonnes per annum is forecast to be maintained to 1990 with only a marginal fall in that production level in the following decade to the year 2000. This will ensure that Canada retains its position as one of the largest producers and most important suppliers of sulphur in the world market well into the future. CANADA AS WORLD SUPPLIER OF SULPHUR Since Canada commenced sulphur exports in the early 19601s, exports have grown steadily. (Figure 1) The rate of growth accelerated in recent years and in 1984 a total of 7.6 million tonnes was sold for export, compared to 3.0 million tonnes in 1975 and less than 1 million tonnes in 1964. World trade in sulphur also increased during this period, from 11 million tonnes in 1975 to 17.0 million tonnes in 1984 (Figure 2). Most of this increase in volume was accounted for by Canada and Poland. As a result, the importance of Canada as world supplier expanded from 28% in 1975 to 45% in 1984. The markets for Canadian sulphur can be divided into two broad categories, i.e., solid and liquid (Figure 3). The solid market is the largest, taking about 70% of Canadian output, virtually all of which is sold offshore. The U.S.A. and the Canadian domestic market take about 20% and 10% respectively, in liquid form. In 1984, (figure 4) total Canadian sulphur sales exceeded 8 million tonnes with offshore export sales at a record 5.8 million tonnes and sales to the U.S. of 1.8 million tonnes. Domestic sales accounted for only 0.7 million tonnes. The general trend for offshore export sales has been upward whereas there has been relative stability in domestic sales. The exceptional growth in offshore sales in the 1970's necessitated considerable capital investments by the industry in order to establish a logistics system capable of handling increasing offshore tonnages. Over 50 sulphur plants are currently operating in Alberta and British Columbia. Some of these are connected by rail, (Figure 5) the balance being generally connected by road. There are currently fourteen of the larger rail-connected plants designated as export plants, and these are equipped with sulphur forming facilities. The long distances between these plants and tidewater terminals in Vancouver is a very significant factor in complex logistics of Canadian offshore sulphur exports (Figure 6). Alberta and B.C. plants are located an average of 1,400 kilometers from tidewater.

Jan 1, 1986

By H. Knorre, A. Griffiths, J. Loroesch

Introduction Hydrogen peroxide is known to the mining industry as a powerful oxidant. able to attack and to destroy cyanide, the most important leaching reagent (Knorre and Griffiths, 1984; Griffiths, 1988; Griffiths, 1988). [ ] The most recent development, however, is the use of H2O2 as an oxidant in the cyanidation of precious metals. This application may appear to be a contradiction to the above mentioned detoxification process. This can, indeed, be the case if certain conditions are not considered carefully. Degussa has developed a new process to enable the application of H2O, in this field without having any detrimental effect on the cyanide. The incentive to seek an oxygen supplier like H2O2 instead of air was the fact that one of the most important conditions for the fast dissolution of gold is the presence of physically dissolved oxygen in the pulp (Kydryk and Kellog, 1954; Warstell, 1987). [ ] Complete gold recovery within a reasonable leaching time may only be achieved if the pulp is saturated with dissolved oxygen. Gold losses in leach operations mainly occur due to the following reasons: In some cases, the saturation of oxygen in the pulp cannot be achieved by aeration due to the difficulty to transfer oxygen from the gaseous into the liquid phase. This happens, for example, in pulps with a high viscosity. In such cases, even violent aeration only results in a low concentration of dissolved oxygen in the pulp. In any case, the starting phase of leaching requires the highest amount of oxygen. Therefore, it is especially important to raise the dissolved oxygen level to saturation in the starting phase. Peroxide assisted leach process (PAL) The intention of the process is to introduce oxygen in a liquid form. As a result of intensive research work, it could be shown that hydrogen peroxide can be used as a source of oxygen in the leaching of gold ores. To avoid side reactions, the following conditions must be applied: Hydrogen peroxide must be diluted before it is added to the pulp. The dosage of H2O, must be properly regulated based on the oxygen level of the pulp. An important part of the continuous O, control is a special oxygen electrode, which resists the extremely abrasive action of the pulp.

Jan 1, 1990

By J. L. Whitlock

A mutant strain of Pseudomonas paucimobilis is utilized to effectively degrade and or remove 90-98% of cyanide, thiocyanate, toxic heavy metals and ammonia from a cyanidation mill process and mine discharge maximum of 21,000 m3/d (5.5 MGD). Homestake Mining Company?s biological wastewater treatment plant has been in full scale operation for over 2 years at the Homestake Mine in Lead, South Dakota.

Jan 1, 1987

By Raj K. Singhal

Canada produces close to 42 million tonnes of coal per annum of which some 38 million tonnes is produced by surface mining methods. The two Western Canadian provinces, Alberta and British Columbia, produce 31 million tonnes of coal by surface mining. These two provinces provide the bulk of the metallurgical coal for export. The geological conditions in the Western provinces particularly in the mountain region are complex. The coals are friable and the seams are steeply inclined, sheared, intensely folded and faulted. There may be as many as 15 to 20 coal seams present with true thickness ranging from 2.5 m to over 8 m. This paper reviews the surface mining methods used to extract such seams. The difficulties associated with steep seam and multiple seam mining of friable coal resulting in lower coal recovery, high dilution and the problem of cleaning fine coal in the wash plant have been highlighted.

Jan 1, 1984

If it had not been for the almost unbelievable adventures that came before and after, the last ten months of 19 15 would have been exciting enough for anyone. As it was they were a cheerful interlude. I spent most of the time on our Warren operations catching up on a lot of underground work and visiting Ajo every few weeks to see if my Chuquicamata visit might help solve the New Cornelia problem. While the difficulties were finally solved, at times they seemed almost hopeless. About all I could do to help was to make sure that the ore sent to the pilot plants represented the average ore that must be treated in the final 5000 tpd mill. Dr. Ricketts and John Greenway worked tirelessly with the best consulting advice they could obtain. Credit for the final success was due chiefly to their efforts. Since our old group had given up its "Merry Widow" home in Warren, a few of us got rooms in the company-built Cole Building over the Warren grocery store. This included Jim Lewis, Roy Mitchell, Steve Landon, Paul Stevens, and Hubert d'Autremont who came from Duluth to join our legal staff. Later we rented a small house two blocks from the Calumet and Arizona office. With the now flourishing country club only a 10-min walk away, and an electric car running to it every half hour or so, we were able to give parties in return for the hospitality of our friends. One of the most pleasant episodes came by luck a few days after I got back from Chile. Chester Congdon, a leading director in Calumet and Arizona, with his wife and their daughters, Elizabeth and Helen, spent a couple of days at the Greenway house before making an auto- mobile trip across the desert from Tucson to Ajo. At the same time I arranged to examine the small but rich Bush and Baxter copper mine a few miles from Tucson. At a party in Warren we found we would all be staying at the Santa Rita Hotel in Tucson, and I took my South

Jan 1, 1976

By W. D. Hausel

The Wyoming Province is an Archean craton which underlies portions of Idaho, Montana, Nevada, Utah, and much of Wyoming. The cratonic block consists of Archean age granite-gneiss with interspersed greenstone belts and related supracrustal terranes exposed in the cores of several Laramide uplifts. Resources found in the Province and in the adjacent accreted Proterozoic terrane include banded iron formation, Au, Pt, Pd, W, Sn, Cr, Ni, Zn, Cu, and diamonds. The Province shows many similarities to the mineral-rich cratons of the Canadian shield, the Rhodesian and Transvaal cratons of southern Africa, and the Pilbara and Yilgarn blocks of Western Australia, where much of the world's precious and strategic metal and gemstone resources are located.

Jan 1, 1991

By Murat Erdemoğlu, Turan Uysal, Thierno Saidou Barry, Mustafa Birinci

The rapid development of the global alumina and aluminum industry is straight coupled with the demands and the needs of these materials. Nowadays, the only well-known accessible resources to produce alumina and aluminum are bauxite ores. But bauxite ores are limited, and the remaining exploitable reserves do not have high contents in alumina. In countries where there is little or no bauxite reserves or where the recovery of existing bauxite ores to produce alumina with the Bayer process are not economic, alternative resources for alumina have been explored. The most attractive resources for replacing bauxites are aluminosilicate clay minerals and coal fly ash. The important processes developed for the recovery of alumina from these sources are acid leaching and alkaline leaching processes. The acid leaching is known as the most efficient in which thermal and mechanical activation are included for improving the performance of the process. The objective of this review is to give a comprehensive insight on the production of the alumina from thermally or mechanically activated clays and coal fly ash by hydrochloric, sulfuric, and nitric acid leaching processes.

By R. L. Michalowski

The operation of mobile mining equipment near the crest of stockpiles and wastedumps is a potentially hazardous practice which often results in localized slope failures. A limit plasticity approach to determine the total admissible weight for moving loads near slope crests is presented. A three-dimensional analysis provides an upper bound solution to the load that can be applied to the top of the slope (dump point), and it also provides the critical distances of the load from the slope crests. The analysis accounts for the inertial forces generated by the deceleration of a moving load (e.g., a dump truck), and it also includes the drag resistance of the front wheels if the brakes are engaged. The results can be utilized to determine the safe operating distances for mobile equipment from the slope edge. This presentation will discuss the application of limit plasticity to the development of the local three-dimensional collapse mechanism. An example with realistic parameters also will be presented.

Jan 1, 1991

By L. J. Buter, D. J. Collins

Introduction FMC's Paradise Peak gold mine was discovered by staff geologists in July 1983. Located south of Gabbs, in western Nevada, the deposit contains about 11 Mt (12 million st) of ore grading at 3.6 g/t (0.105 oz per st) of gold and 129 g/t (3.75 oz per st) silver. It is estimated that the ore contains 34 t (1.1 million oz) of recoverable gold and 933 t (30 million oz) of recoverable silver. The 3.6 kt/d (4000 stpd) mill began operation April 14, 1986, just 18 months after Davy McKee completed a feasibility study and construction, and two-and-a-months ahead of schedule. It also came in about 10% under budget at a cost of about $100 million. Crushing Run-of-mine ore is delivered from the mine in 45-t (50-st) haul trucks to a 272-kt (300,000-st) capacity open air stockpile. Ore is reclaimed using 5 m3 (7 cu yd) front-end loaders that feed a 91-t (100-st) hopper equipped with a 610- x 610-mm (24- x 24-in.) grizzly. A 1.4- x 11-m (54-in. x 35-ft) apron feeder delivers ore from the hopper by way of a vibrating grizzly screen with 127 mm (5 in.) openings to a 1- x 1.3-m (43- x 51-in.) Rexnord jaw crusher. Crushed material is conveyed to a 1.8- x 4-m (6- x 14-ft) Link Belt vibrating screen equipped with a 50-mm (2-in.) manganese grizzly bar deck. Screen oversize is fed to a 1.7/0.6-m (5.5 ft) Rexnord standard cone crusher. Product from this crusher joins the -50 mm (-2 in.) screen undersize and is conveyed to a 136-t (150-st) surge bin. Three hydraulically driven belt feeders deliver ore from the ore bin to three 2 x 6 m (7 x 20 ft) Link Belt single-deck tertiary screens fitted with 6 x 25 mm (0.25 x 1 in.) slotted polyethylene screens. Screen undersize - -6 mm (-0.25 in.) rock - is conveyed to a 3.6-kt (4000-st) ore storage bin. Screen oversize is delivered by way of a conveyor to a 91-t (100-st) surge bin. From this bin, two belt feeders feed ore to two 1.7 m (66 in.) Rexnord Gyradisc crushers, which are in closed circuit with the tertiary screens. Design features include magnetic protection for tramp iron removal and sloping floors and pump sumps for ease of clean up. Dust scrubbers keep the working environment clean and in compliance with state dust emission regulations. Grinding Two 1 x 4.5 m (3.5 x 15 ft) belt feeders deliver ore from the fine ore bin to a conveyor belt that feeds it to the 5 x 7 m (16 x 22 ft) Allis-Chalmers ball mill. The conveyor belt is equipped with a Merrick weightometer. This controls feed rate to the ball mill by speed control on the hydraulic motors driving the feeders. The 2.6 MW (3500 hp) powered mill grinds 3.6 kt/a (4000 stpd) to an average grind of 85% -75 µm (-200 mesh). The mill is in closed circuit with four 660 mm (26 in.) Krebs cyclones. Three of these are normally in operation while one is a standby. Warman pumps feed the cyclones through a cyclone distribution manifold. The cyclone underflow returns to the ball mill, which has a 300% average circulating load. Mill discharge pH is 11, and that is obtained through pebble lime addition to the feed belt. Cyclone overflow is sampled using a Heath & Sherwood two-stage sampler. It then flows to a 27-m-diam (90-ft-diam) Eimco thickener. Thickener overflow is returned to the grinding circuit, while underflow at 50% solids is pumped to the leaching circuit. Grinding-circuit design features include a steeply sloped floor for ease of clean up, an open area over the pumps for maintenance accessibility, and a ball hopper with a self discharge bottom to speed ball addition. Other features include a mill liner handler and an air clutch that connects the mill motor to the mill.

Jan 12, 1986

By Thomas B. Borak, Keith J. Schiager, Janet A. Johnson

OBJECTIVES OF RADIATION MONITORING Monitoring is a tool used in the practice of radiation protection. The primary reasons for monitoring are to reduce radiation exposures to levels that are as low as reasonably achievable and to assure that no individual receives a dose exceeding the maximum individual dose limit. The documentation of radiation doses for legal, medical, or epidemiological reasons is a subordinate function of any monitoring program. The investment in radiation monitoring programs should be guided by four criteria: (1) the detection and avoidance of unnecessary exposures, (2) the magnitude of potential health risks, (3) the determination of combined doses and risks with adequate confidence, and (4) the verification of compliance with established limits. FIRST CRITERION: DOSE REDUCTION - DETECT AND CORRECT UNNECESSARY EXPOSURES The system of dose limitation advocated by the International Commission on Radiological Protection (ICRP, 1977), and subscribed to in a broad sense by various regulatory agencies, is comprised of three essential ingredients: (1) [justification] of any practice that produces radiation doses by some commensurate net benefit, (2) [optimization] of radiation control measures by reducing doses to levels that are as low as reasonably achievable, and (3) [limitation] of individual doses to preclude inequities and [moldistribution] of risks. All too often, only the third criterion - the limitation of individual doses to prescribed regulatory limits - is explicitly addressed in everyday radiation protection programs. The emphasis of most exposure control and monitoring efforts appears to be directed toward limiting and documenting individual doses that might approach the legal limit. The first two criteria, i.e. justification and optimization, should contribute to a rationale for allocating monitoring efforts. When applied to individuals, these criteria mean the detection and elimination of unnecessary exposures. This should be a high priority of any monitoring program. Measurements should be directed toward detecting inoperative or ineffective control measures, whether or not there is a risk of exceeding the individual dose limits. The ICRP recommends a procedure that can be used effectively to reduce unnecessary exposures. A n investigation level should be established at an exposure rate substantially lower than the regulatory limit, e.g. 30% of the limit (ICRP 26, 1977, p.33). Measurements obtained during routine monitoring that exceed the investigation level are evaluated with respect to cause and potential reduction. To be effective, the evaluation results should be formally recorded and conveyed both to management and to the workers involved. Although the investigation level recommended by the ICRP is based on a fixed exposure rate or derived air concentration, an equally effective evaluation program may be based on the investigation of a percentage of all measurements. For example, one might investigate the highest 5% or a random selection of all measurements. In any case, the objective is to detect and correct situations that are producing unnecessary exposures. SECOND CRITERION: MONITOR IN PROPORTION TO THE MAGNITUDE OF RISK The ICRP criteria apply generally to all radiation exposures. However, a second priority for monitoring programs should be established on the basis of the nature of the exposures and the magnitude of the health risks involved. Current practices in radiation protection are based on dose limits to specific organs and assessment of individual exposure pathways, with little consideration of the combined doses from various pathways. Although the intent of the ICRP recommendations was to limit the total dose to each critical organ, combined doses from external and internal sources are rarely determined. The recent recommendations of the ICRP (Publ. 26, 1977) are based on the limitation of total health risk from occupational radiation exposures. Implementation of this concept would necessarily require the measurement, calculation and summation of doses and concomitant risks to all organs of the body from all exposure pathways. The U.S. Environmental Protection Agency has taken the first step toward translating the ICRP recommendations into regulations. The proposed recommendations for Federal Radiation Protection Guidance for Occupational Exposures (USEPA, 1981) include provisions for summing the risk-weighted organ doses to determine compliance with an effective whole-body dose equivalent limit. Whether or not the proposed guidance is modified before final adoption, it seems clear that some version of dose summation and combined risk limitation will be included in future regulations. With this

Jan 1, 1981

By Juan P. Camus, Sergio G. Jarpa

INTRODUCTION Chuquicamata mine is a large copper open pit located in the north of Chile. It has been in production for more than 80 years and now is in the later stages of its life with declining grades and increasing haul distances. As any old mine with long established organizations and procedures, it has faced one of the most difficult managerial problems: to conduct changes. Since 1994, the new management team has been devoted to a modernization pro- gram focused mainly in restructuring business operations. downsizing the labor force and introducing a mine planning pro- cess consistent with the company's goal. The explicit identification of the latter issue has been made because of the management’s conviction about the importance of it in the profitability of the business. The mine planning process at Chuquicamata mine has evolved from an old manual technique towards a modern computarized system, however the fundamental aspects and the procedures involved in this process have been the same. For in- stance, the cutoff grades policy has not changed during the last said 20 years, regardless of the changes to grade distribution, commodity prices, plant capacities, etc. To review and rethink this process, the strategy was to work with a small group of inside engineers and the management in order to interact with several mining consulting firms. The idea was to open a discussion about the fundamental principles used in the mine planning activities and, at the same time, to explore new ideas to improve the operating practices that have been followed for a long time. Thus, the goal of this paper is to present the mine planning approach that was the result of this work and the improvements that were obtained. THE CHUQUICAMATA MINE The Chuquicamata division is one of the five operations of Codelco and is currently devoted to operating the Chuquicamata mine; a copper open pit, concentrator, smelting and refining complex. It also operates Mina Sur which consists of an open pit mine, a leaching-solvent extraction and electrowinning process. There is also a dump leaching and a Sx-Ew plant for treating the low grade suifide ore (under the cutoff grade) from the Chuquicamata mine. Prior to reviewing the mine planning process, capacities for the Chuquicamata sulfide line were 640 000 tpd of run of mine material, 160 000 tpd of ore and 4 200 tpd of concentrate. This meant a total annual movement of around 230 Mt in the mine and a treatment of 57 Mt in the concentrator with a stripping ratio of approximately 3: 1. The old exploitation strategy consisted of an "open scheme", which means that all benches must have a berm with enough space to allow the traffic of large haulage trucks. This fact implied working with a great flexibility, but the consequences were flat slope angles. One of the reasons for using this operating practice in short term planning was that the grade consistency from the pit has always been a controversial variable. Schedules were designed to meet grade targets accurately and they were modified immediately when deviations become apparent. This reality led to working with a great deal of independent pushbacks and it required flexibility in the traffic system. The cutoff grade policy has been the same for a long time and the figure was 0.5 %CUT either for sulfide or oxide ore. This was the reason why a balance was produced between the mine and the concentrator. The mine is operated principally with benches of 26 m but in the upper part of the pit there are benches of 24 and 30 m. The main production equipment is shovels of 28 and 34 yd3 along with trucks of 200 and 240 st. Regarding the crushing facilities, there are two main systems located inside the pit and an old one in the periphery, close to a stockpile and near the concentrator. In the north part of the pit there is a crusher for waste material and in the north-east area is located the ore crusher facility. Both restrict a significant area of the pit and the mine sequence is considering to move the ore crusher again to the south-east sector where it used to be located. Relating to the waste crusher, the idea is to move it up to a bench near the surface in order to use the same conveyor belt and, at the same time, liberate an important sector. THE MINE PLANNING PROCESS The objective of the mine planning process is to develop a mine plan for the life of the deposit, in harmony and consistent with the company's goal. It includes the origin and destiny of tonnages and grades from the mine(s), along with the necessary resources to carry out this plan such as: fleet requirement, consumable goods, manpower, etc. From the financial point of view, it means to establish the cash flow for each time period of the mine life. That is. the revenue, capital investment and operating cost associated with each period of the plan. The fundamental principles involved in the mine planning pro- cess have been a controversial issue for a long time. One of the reasons for these divergent views could be produced by the difficulty of modeling a complete extraction policy for a geological re- source. This particular problem has to deal with several decision variables that are time dependent. So far, there is no mathematical formulation for managing such a problem, and the approach to solve it is based on a circular analysis combined with certain heuristic tools. So, a global model rather than a formula, requires a clear understanding of mine operations as well as economic theory and its application to a non-renewable resource. In order to manage this complex problem, the mine planning process can be conveniently split off in three stages which are conceptual, feasibility and operational planning. The characteristics of each stage are basically the timeliness in which they are developed and the kind and number of variables involved. Thus, conceptual planning is devoted to the definition of key variables like: the size of the operation, mining method, extraction se-

Jan 1, 1996

By Jack O?Hearn

A liquid and solid waste management plan for an operating uranium ore processing mill was developed to efficiently and effectively dispose of existing solid wastes and related, affected surface and ground water resources. The goal of this management plan was to achieve satisfactory clean up of these existing wastes ad their by-products as well as to prevent similar situations from occurring in the future. An existing, modern system of synthetically lined tailings ponds, constructed after many years of mill operations, now provides an approved site for the disposal and containment of waste streams currently generated by the mill. This system was thought to be readily adaptable to serve as a key element of the waste management plan. The potential presence of extra capacity in these ponds could eliminate or reduce expenditures for new facilities required solely for proper management of liquid and solid wastes generated by operations prior to construction of the modern tailings ponds as well as for a range of anticipated future operations.

Jan 1, 1984

By Katherine Hynard, Colin Eustace

Development quarterly mine plans is generally time-consuming and requires consideration for many operational constraints and competing objectives. With lengthy turnaround times, there is often limited opportunity to adjust the quarterly plan details to account for differences between actual state of the mine operation at the time of execution and expected state at the time that the plan was developed. Actual mining task completion times can vary significantly from the expected task completion times, due to many factors. In the absence of revision to account for differences between the planned and actual state, resource allocations and mining sequences, embodied in the quarterly mine plan may no longer be the best approach at the time of execution to achieve an efficient mining operation. Simulation and optimisation tools can be used to support rapid refinements for development and execution of weekly mine plans. When initialized with an operations data feed to establish the actual state of the mine operation, optimisation models can be used to facilitate both automation and revision of the quarterly plan to produce a weekly or daily plan for execution. This approach can remove much of the manual burden of revision if the existing quarterly plan no longer represents the best approach to meeting production objectives. Following initialisation with mining actuals, simulation models can provide a representation of the range of likely mine operations outcomes. The models can be used to accelerate the planning process by providing visibility of future performance and identifying likely operational issues. They can also be used to test the robustness of the plan with respect to performance variability and response to disturbances. Following identification of issues, simulation models can also be used for evaluating mitigation measures, through automated testing of alternative plans. Integration of mine data feeds with simulation and optimisation tools enables automated optimal responses to variations between the quarterly mine plan and actuals to be tested prior to release of and execution plan and implementation. The use of simulation and optimisation in weekly mine planning will be discussed in this paper with reference to surface mining examples.

Jun 25, 2023

By Joao B. Cardoso

This paper describes a two-stage reverse flotation method developed at the Mineral Resources Institute (MRII, University of Alabama, for Kerr-McGee Corporation (KMC), to separate the trona (Na2CO3 ? NaHCO3 ? 2H2O) from a saline deposit containing halite, borax, minor salts, and water insoluble materials. In the first stage, trona is depressed with Quebracho, and the insoluble gangue is floated with fatty acid. In the second stage, trona is floated with cresylic acid. The flotation concentrates contained better than 90% trona with insolubles ranging between 1 and 2%. Although the trona recoveries were low, optimization and middlings recycled in a continuous circuit could substantially increase the value.

Jan 1, 1989

By William A. Prosser, Kyle R. Ott, Philip Rice

"INTRODUCTION The existing Baltimore and Potomac (B&P) Tunnel accommodates Amtrak (National Railroad Passenger Corporation) and MARC (Maryland Rail Corporation) service between Baltimore, MD and Washington, DC and occasional local freight service. The Baltimore and Potomac Tunnel Replacement Project proposes new tunnel construction through Baltimore, Maryland along the Northeast Corridor (NEC) that maintains connections to Baltimore Pennsylvania Station. After the Replacement Project is constructed and operational, the disposition of the existing tunnel must be determined. The tunnel could be abandoned; however, considering its location in a congested downtown, alternative uses have been considered to take advantage of this unique piece of infrastructure by repurposing it. Alternative uses for the existing 140-year-old B&P Tunnel may end up being cost effective and should be considered, as the tunnel can be made accessible to construction crews for extended periods of time that will allow for efficient work activities unlike when it is fully operational. Possible alternatives include conversion for non-rail use, rehabilitation, or complete modernization for continued rail traffic. The following paper describes the four potential fates of the conceptual designs for the existing B&P Tunnel. The four concepts include: • No Build – rehabilitate to keep the tunnel operational. • Abandonment – complete or partial sealing of the tunnel. • Adaptive Re-Use –repurpose the tunnel with sustainable building practice. • Full Rehabilitation and Modernization – bring to current fire-life safety aspects. Of the four concepts, only the no build addresses maintaining the tunnel while it is under traffic. The remaining fates address the existing tunnel after the new tunnel is operational and railroad traffic has been diverted to it. Development of these conceptual designs were provided in a concept design study (Parsons Brinckerhoff/Parsons, 2015) that supports the National Environmental Policy Act (NEPA) review process for the Project, which includes evaluation of possible alternative uses of the existing B&P Tunnel."

Jan 1, 2016

By L. G. Wilson

In our comparison of California and Turkish colemanites, we should first place the discussion in context. In order to exclude technical considerations, which are not germane to this paper, we must make the manifest and basic observation that if colemanite were not acceptable for the production of glass products it would not be used, and we would not be interested in this comparison at all. Suffice it to say that the colemanites, being calcium borates, provide a necessary flux in glass manu¬facture, together with the requisite degree of physical strength and chemical durability which can be achieved only by the use in glass of a. flux substanti¬ally free from alkali; so the sodium borates are automatically excluded from the production of textile fibers. Thus we have today under consideration only California colemanite, Turkish cole mite, and, because it provides a degree of competition to both, ABA, or anhy¬drous boric acid, which, although it is a refined intermediate and of much higher cost, it is also of a much higher degree of purity, and its characteristics can easily be modified to produce a desired end product, so we must include it in any consideration of high quality borates. [Calcim Borate Pentahydrate] Colemanite is a [calcium pentahydrate,] with the formula Ca2B6011.5H20. It has a theoretical B203 content of 50.8%.

Jan 1, 1973

By P. D. Georgescu

Gold, like no other metal, has a fascinating and special place in the world. It is used in a range of every day applications essential to modern life. Gold has long been considered the most precious metal in the world. Gold is used mainly for making jewellery as well as for dentistry, adornments on building and artistic expression. For thousands of years it has been used as an ornament of kings, a currency and standard for global currencies, and more recently, in a wide range of electronic devices and medical applications. Gold?s many unique properties have secured in a central role in history and human development. Today, more often than not, gold is extracted from ores. It occurs in vein and alluvial deposits and is often separated from rocks and other minerals by mining and processing operations. Some of these processes cause environmental concern (cyanidation, amalgamation, roasting). Besides primary gold ore resources, a series of secondary resources can be taken into account and processed for gold and silver recovery. There are two main types of waste produced. The first type is process waste, which includes tailing consisting of processing residues and waste rock. The other type is refuse from other different processes and recyclable materials. Among other secondary resources and/or by-products containing precious metals, which have been studied some processes and technologies with low ecological impact are presented in this paper. Heaps and tailing ponds resulted from gold-bearing ore exploitation and processing, refractory gold-bearing pyrite concentrates, slag resulted from electrolytic slime melting, gold-bearing chlorous slime are taken into account. In order to establish environmental friendly technologies for precious metals recovery from these secondary resources, laboratory experiments have been carried out on a pilot scale and in some cases on semi-industrial scale by applying specific technological processes, namely hydro-gravitational concentration, bio-oxidation, non-ionizing electromagnetic radiation (microwaves), solubilization without utilizing cyanide and gold recovery by ion-exchange resin. This paper presents the research results, technological principles as well as the possibilities of applying combined processes in order to treat different secondary gold-bearing resources.

Jan 1, 2006

By E. M. Frizzell

It is unlikely that improvement in truck efficiency and capacity can fully offset the effects of inflation, fuel cost/shortages, and increasing haul distances as in the past. Therefore, investigations of haulage systems less sensitive to these problems are warranted. Thus, this Bureau of Mines contract research study on alternative continuous haulage systems was prepared. This study identifies the physical, economic, and technological parameters in the application of continuous haulage systems with special attention to under pit slope conveyors and skip hoisting systems. The evaluation data were gathered from extensive literature searches, European/North American mine visits, and industry comments. The study concludes that continuous underground haulage is a viable method within the proper geometric configurations.

Jan 1, 1979

By SME SME

List of 43rd ICGCM 2024 ORGANIZING COMMITTEE

Jun 25, 2024

By Roussos Dimitrakopoulos, Liam Findlay

Semimobile in-pit crushing and conveying (IPCC) systems can help reduce truck haulage in openpit mines by bringing the crusher closer to the excavation areas. Optimizing a production schedule with semimobile IPCC requires integrating extraction sequence, destination policy, crusher relocation, conveyor layout and truck fleet investment decisions. A mining complex with multiple mines and IPCC systems should be optimized simultaneously to find an optimal schedule for the entire value chain. An integrated stochastic optimization framework is proposed to produce long-term production schedules for mining complexes using multiple semimobile IPCC systems. The optimization model has flexibility to select the crusher locations and conveyor routes from anywhere inside the pits. The framework uses simulated orebody realizations to consider multielement grade uncertainty and manage associated risk. A hybrid metaheuristic solution approach based on simulated annealing and evolutionary algorithms is implemented. The method is demonstrated using an iron ore mining complex

Nov 1, 2024