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By Terry Mudder

Long-term anaerobic biochemical treatment for draindown of residual solutions is a cost-effective way to close a heap-leach pad. This article presents a laboratory evaluation of anaerobic biochemical treatment of cyanide heap-leach pad solutions. The traditional approach to heap-leach pad closure is to rinse the pads with multiple pore volumes of fresh or recycled treated water. The effluent from an initial rinse is often treated and recirculated until the solutions passed through the heap meet the appropriate numeric and narrative water quality standards. Column rinsing tests are completed during project planning to determine the number of pore volumes of fresh or recycled treated water required to rinse the pad to meet long-term closure requirements. A traditional closure plan generally includes provisions to sample the rinse effluent and rinsed solids (the Meteoric Water Mobility, Procedure or USEPA 1312) to verify that chemical requirements are being met.

Jan 1, 1995

By K. O. Bennington

Cancrinite is one eonstituentof "red muds," a high-volume waste product of alumina production by the Bayer process. The Bureau of Mines determined the thermochemical properties of cancrinite as part of a program to provide such data for minerals of industrial importance. Cancrinite [Na7.68(A16Si6024)(N03)1.68 (H2O)4.1] was synthesized by reacting aluminum silicate gel with a solution of NaOH and NaN03, and the composition was determined by chemical analysis, differential scanning calorimetry, and thermogravimetric analysis. The heat of solution was determined by hydrofluoric acid solution calorimetry. The standard enthalpy of formation at 298.15 K, ?Hf°298, is ?Hf°298 = -3,487.97 ±2.6 kcal/mol, and the standard enthalpy of formation from the oxides and NaN03, ?H°298, is ?H°298 = -215.20 ±l.8 kcal/mol.

Jan 1, 1983

By ALFRED KAUFFMAN

NO matter what position we hold, workman, foreman, superintendent, manager, president, or what not, let us fail to give or to make good products, then see how quickly we'll be called to account for- our work by the buying public. The waves of progress taught us that millions were wasted in unnecessary strikes-we also learned that many losses were due to neglect on the part of manufacturers to give the same consideration and attention to the human element of their factory as they gave to their machinery. The employees learned also that the employer was their agent who found purchasers for the product of their labor. So between the two we learned that many years of labor were needed in order for a worker to recover his wasted savings, or for the manu¬facturer to replenish his loss. Treat 'em rough, and tell 'em nothing, was not very far from the true relationship between management and employees in manufacturing plants in the early days. Today just exactly the opposite views are held by executives whose function is the handling of employees. Men today want to know what it is all about. They are intelligent enough to comprehend the facts, and to use them constructively, and it is good business to give them the information.

Jan 1, 1929

By G. S. Austin

The St. Cloud Mining Company extracts clinoptilolite about 6.5 km south of Winston, Sierra County, New Mexico. Production is about 18,000 mt/year. Natural zeolites are good adsorbents for positively charged solutes such as ammonium. St. Cloud’s production is used in animal hygiene, animal feed, environmental mitigation, air and water filtration, and other applications. By a simple chemical treatment with a surfactant, zeolites can also be modified to adsorb negatively charged solutes such as nitrate and arsentate, and neutral organics such as solvents and fuel components. These surfactant-modified zeolites are used in treating groundwater contamination, stormwater runoff, and solvent vapors from painting operations.

Jan 1, 2002

By Walter W. Kaufman

The braking performance of underground, rubber-tired, coal mining vehicles is evaluated. Surveys of mining equipment and braking manufacturers and underground stopping tests are discussed as they relate to this evaluation. Stopping performance recommendations are proposed.

Jan 1, 1977

By F. W. Wood

The use of consumable.-electrode arc melting as a production technology is growing. One advantageous feature of this process is that it avoids ingot contamination by soluble crucible materials by employing a chilled metal crucible. Because the thermal balance under these conditions is rather delicate and does not necessarily provide a favorable environment for solidification, catastrophic imbalances can occur. The effectiveness and mechanistic roles of various factors are mostly unknown, and more intelligent insight regarding the distribution of temperature and heat is needed. Experience has provided several pertinent observations, some of which are quite superficial. The most meaningful data have resulted from studies of molten pool shapes and sizes and from measurements of heat flow through crucible walls. Overall experience, intuitively interpreted and supplemented, is sufficient nevertheless as a basis for a boundary-value treatment of the problem. A mathematical analysis based on a separation of variables, using conventional differential equation methods, provides a useful solution. For a cylindrical ingot, the temperature varies as a Bessel function of an argument proportional to the radius and as an exponential function of longitudinal position. Trial calculations using the problem solution seem to verify the general correctness of the result as compared with experience. The role and nature of solution parameters are also clarified, though not entirely resolved. It is revealed that the barrier to heat flow at the ingot-crucible surface has a prominent influence. Utility of the model embodied in the problem solution is readily demonstrated by considering a variety of contemporary questions about arc melting, and it is hoped that utility can be enhanced by improvement of the model.

Jan 1, 1968

By Robert H. Ridgway

This paper presents the results of the second in the series of annual canvasses on the consumption of ferrous scrap and pig iron in the United States, inaugurated in 1935 by the Bureau of Mines and published in Report of Investigations 3329. The study was undertaken in response to requests from trade organizations and others for detailed statistics on this phase of the iron and steel industry. Thus, for the first time, producers, buyers, sellers, and consumers of iron and steel scrap have had an accurate statistical picture of this important raw material As originally contemplated, the study was to be continued on an annual basis, but, owing to budgetary limitations for the fiscal year 1937-38, the Bureau may be unable to conduct the canvass for 1937.

Jan 1, 1937

By Jacques Magnaudet, Julie Cranga, Didier Huin, Pascal Gardin

"With the aim of controlling steel grade in steelmaking reactors, IRSID and IMFT are developing a numerical description of the evolution of bubbles in the vicinity of a liquid steel/ slag interface. The objective is to identify the main parameters affecting the hydrodynamics of the various phases. The goals of the present paper are:• To describe the numerical technique developed to predict the multi phase flow including bubbles, liquid metal and slag layer.• To analyze the influence of the absolute pressure on the bursting of bubbles in a RH degasser. Validation is given by comparison with results available in the literature. The major point concerns the distinct behaviors observed whether the pressure is low or high.• To study the influence of the properties of the slag layer (thickness, viscosity and interfacial tension) on the entrainment of liquid metal in the wake of the bubble and on the nature of the projections from the bath surface.IntroductionMost of secondary steelmaking processes use gas stirring for homogenization, removal of nonmetallic inclusions or decarburization under reduced pressure. The bursting of gas bubbles at the metal or slag layer surface produces a beneficial ejection of metal droplets in the low pressure atmosphere, provided that there is no violent projection, which may have detrimental effects on the process.Our objective is to develop a numerical tool to study the phenomena occurring in the vicinity of the bath surface, in particular bubble bursting under reduced pressure and entrainment of metal in the slag layer. In this paper we report the first conclusions of our study. In the first section we describe the numerical model used to describe the three-phase flow and the expansion of the gas bubbles under the effect of the ferrostatic pressure. The second section is devoted to the study of pressure effects on bubble rise and bursting. The third section reports some computational results about the rise of a gas bubble through the interface between the two liquids."

Jan 1, 2001

By James S. Grichar

Interest in mergers in the nonfuel mineral industry developed when 5 were listed among the 50 highest valued mergers in the United States in 1981. This report presents a Bureau of Mines study of trends in merger activity from 1960 to 1979 and explores motives for mergers in the nonfuel mining and mineral industry. The objective was to determine precedent for or a trend toward the 1981 acceleration in merger activity and to examine certain financial motives for non fuel mineral mergers. Data indicate that the relative value of non fuel mineral mergers has grown since 1972 although the number of mergers has remained proportionate to historical trends for all mergers. Since 1974, the assets acquired in "large," nonfuel mineral firm mergers, those of $10 million or more, have comprised at least 93 pct of assets acquired. More nonfuel mineral firm mergers involved mineral companies as the acquiring firm than vice versa but mining and minerals firms acquired were of higher value than nonmining firms. A major motivation for mergers involving large mineral firms was the acquisition of assets at less than replacement costs. Univariate statistical testing, a methodology chosen for its applicability to the data, confirms this hypothesis while rejecting other financial motives. The remainder of the work is devoted to a discussion of suggested areas for future study.

Jan 1, 1984

By S Thomas, S Ricketts, R Hassell

Northern Star Resources (NSR) operates several operations utilising narrow vein stoping operations in the Kundana area. Stope dilution performance is variable across these operations, with unplanned dilution reducing individual stope economic viability, increasing risk to personnel and machinery operating in and around the stope and delaying the overall stoping sequence. Technical investigations were undertaken to objectively understand the variables which had the largest impact on stope performance and then use the findings to help develop mining strategies to reduce dilution. A stope reconciliation process was developed to compile key stope performance information such as stope design parameters, geotechnical and drill and blast factors. These were compared against the measured dilution. Production targets necessitated a high turnover of stopes in the operations, and hence a requirement for an expeditious process and mine design software with automated tools. The output of these results, together with numerical variables from geological, geotechnical and drill and blast data were analysed via multivariate regression. The analysis identified the factors with the greatest influence over stope dilution, and a forecast model was consequently created. Confidence was gained in the model when the subsequent stopes performed in line with prediction. Different drill and blast designs were subsequently trialled and found to reduce dilution. The model was then updated with the new practices, facilitating further regression analysis to identify revised key controlling factors. The subsequent production results however, displayed a poor correlation with the prediction from the revised model. Inconsistencies in drill and blast designs and execution were identified as key factors in the dilution performance. This was an important finding as the correct implementation of the design is critical and this has become a key focus for future stoping. Overall the technique presents an objective process to identify causal factors of stope dilution resulting in improved economic metrics for stope production. The process will be applied to other similar Northern Star operations.

Mar 15, 2021

By C. H. Bloomster

This study estimated (1) radon and radon daughter emissions from underground uranium mines; (2) the reduction in radon that would be released to the surface by using control techniques such as bulkheads, sealants, backfilling, and positive pressure ventilation; (3) the cost for radon and radon daughter removal from total exhaust air; and (4) total radon and radon daughter discharge for lower occupational exposure limits. For 13 large underground uranium mines, estimated yearly radon emissions from each mine ranged from 900 to 3,400 Ci. The estimated age of air emitted from the mines ranged from 11 to 37 min. Potential radon removal methods for the total mine exhaust were evaluated. The cost of these methods was prohibitive. Diurnal and seasonal changes may affect radon emission over short periods of time, but do not affect the total emissions over the long run. Radon and radon daughter emissions would be little changed by increased ventilation requirements needed to achieve lower occupational exposure limits. The concentrations in the exhaust would be lower, but the total release would be the same

Jan 1, 1984

By R. W. Fountain, J. Chipman

THE solubility of nitrogen in iron and steel has been of considerable interest due to the role of nitrogen in strain-aging and in quench-aging. It is generally considered that quench-aging is the result of precipitation of carbide and nitride particles from supersaturated solid solution, while strain-aging results from the segregation of carbon and nitrogen atoms to dislocations.1-9 The rate of strain-aging is controlled primarily by the amount of carbon and nitrogen in solution and the temperature. In experiments on strain-aging of pure iron with only carbon or nitrogen as impurities, Fast" has shown that even after 40 hr at 50°C carbon did not give any strain-aging while

Jan 1, 1959

By Adrian Dance

The Antamina orebody is a geologically complex, polymetallic skarn located in the Peruvian Andes. A range of copper and copper-zinc ores are campaigned separately through the concentrator producing copper and zinc concentrates as well as lead and molybdenum by-products. Ore type classification at Antamina is based on chemical assays; geological or lithological variations are not considered. Consequently, each ore type demonstrates a wide range of concentrator performance. Antamina is currently implementing a system to track ore movements from the shovel face to the concentrator. Relatively sophisticated models of the ROM and coarse ore stockpiles ahead of the mill will be used to account for the variable delay between mining and milling. One of the numerous benefits of ore tracking is the ability to directly associate the measured concentrator performance with a physical location in the orebody. Using existing mine planning software, three-dimensional models can be created of such performance measures as metal recovery, concentrate quality, operating cost and reagent consumption. Such a database of information allows the true value of different ore sources to be determined. The value of an ore source is conventionally measured as metal content (individual or combined ?equivalent?) with a cut-off grade applied to indicate some base level operating cost. However, the true value of an ore source should include dynamic factors like haulage cost, reagent use, smelter penalties and even prevailing metal prices. If an ore source is considered from all perspectives rather than simply its potential to deliver value, the concept of ?ore? becomes more flexible. Any ore source that reveals itself to be unprofitable can be eliminated from the mine plan or possibly blended with others to improve its value. The ability to predict mill performance ? and thereby profitability ? is a powerful tool. In an operation such as Antamina, where managing ore sources, campaigns and the delivery of a variety of concentrates in a narrow timeline to customers is a daily challenge, prediction is the key to success and improved efficiency.

May 1, 2003

By John Wise

Significant movement to an existing slurry wall which serves as a retaining wall on 'O' Street in Southeast Washington, D.C. initiated the Department of Public Works for the District of Columbia to invite specialty contractors to propose a rehabilitation and stabilization for the failed slurry wall. Nicholson Construction Company proposed and was awarded a contract for the construction of an anchored precast lagging and soldier pile wall to be located approximately 4 feet in front of the existing structure with granular fill placed between the new and existing walls. Stabilization of the existing slurry wall also included drilling horizontal weep holes and demolishing the failed panels down to the existing ground surface. A new and improved drainage system was also constructed to increase the amount of water directed toward the existing storm sewer system running along 'O' Street. This paper provides a detailed account of these construction activities.

Jan 1, 2003

By Gray Mullins

This paper presents experimental results from a study to assess the interface bond between a cast-in-place concrete seal slab and prestressed concrete piles in cofferdams. Three different seal slab placement conditions - fresh water, salt water and bentonite slurry - were evaluated and the results compared against controls where no fluid had to be displaced by the concrete. Normal pile surfaces were investigated. Additionally, the situation of ?soil caked? piles was also investigated. Both model and full-scale tests were conducted. In the model tests, twenty eight 15 cm square prestressed sections were used with the embedment depth varied between d-2d, where d is the width of the pile. In the full-scale tests, 16 specimens were tested. The prestressed piles were 36 cm square with the embedment varied between 0.5d-2d. Four of the sixteen piles were cast with embedded gages located at the top, middle and bottom of the interface region. The results showed that loads were transferred to the piles over an effective area, not the entire embedded depth. Significant bond stresses developed even for the worst placement condition. Recommendations are made for revising current values in specifications.

Jan 1, 2013

By Dhananjaya Senapati, E. V. S. Uma Maheswar, C. R. Ray

Carbothermic process of Ferro Silicon production is primarily a slag-less process. However, slag formation is observed in the regular operation as experienced by almost all the Ferro Silicon Producers in different pro-portions. The problem of slagging in the furnaces may be due to: a)Variation in the input burden charge material quality b)Fluctuations in the Carbon balance and/or c)Fluctuations in the Electrode penetrations The problem will be more severe in nature with the increase of the size of the furnace. The operation performance of the furnace gets badly affected if the slag formed in the furnace is not removed from the bath in time and to the maximum extent possible. It is, therefore, very essential to know the characteristics of the slag formed in the Ferro Silicon Furnaces, besides eliminating the very cause of formation itself; and to find the routes of draining of the same from the furnace bath effectively. This paper envisages the effects of using the LIME STONE in the Ferro Silicon Burden in stabilizing the 48MVA Furnace for improved performance and better consistency. Quality fluctuations in the available Raw Materials are compared with that of the requirements for the Ferro Silicon production. The furnace operational data is compared for 12 months period each for the period corresponding to the before and after usage of lime stone in the burden and found encouraging results in the performance. Implications of use of Lime Stone in the burden on the quality of the output alloy are also studied.

Jan 1, 2007

"While control of dust-related diseases, the objective of the Generic Mineral Technology Center for Respirable Dust, is of prime importance from the human standpoint it is also essential to the economic well-being of the mining industry (FIGURE 23). Although significant progress has been made, the problem continues to be a major concern to the mining community. An increasing global demand for coal and other minerals means that production and the number of miners employed is on the rise. Therefore, the importance of this research to the mining industry cannot be overemphasized.The five areas of dust research are 1) control of dust generation, 2) dilution, dispersion and collection of dust in mine airways, 3) characterization of dust particles, 4) interaction of dust and lungs, 5) relationship of mine environment, geology, and seam characteristics to dust generation and mobility. Some experimental projects where the research is conducted almost exclusively in the laboratory may still rely on industry for imput. No industrial resources are necessary to the research of the non-experimental projects, for example computer modeling .The remaining research is classified as experimental and these projects do require interaction with industry in varying degrees. Periodic trips to mining sites in Western Pennsylvania, Southern Ohio, and West Virginia are necessary to record measurements or collect samples. Or companies may provide needed samples or equipment to the university for use in the laboratory. On several projects interaction is limited to advice or information supplied to the researcher by industry personnel."

Aug 31, 1989

By R. Tyreman, G. Ritson

"The Red Lake Mine is situated in Balmer Township, Red Lake area in northwestern Ontario. It is an underground mine that has been in production since 1948. The property was originally known as the Dickensen Mine and was shut down in 1996.A feasibility study was carried out in 1998 and it was determined that a new mill should be constructed with a throughput rate of 600 stpd. The life-of-mine average gold grade was projected to be 1.35 oz/t with gold predominantly associated with arsenopyrite and pyrite. Metallurgical testwork indicated that the optimal flowsheet for gold recovery would include an autoclave for oxidation with a carbon circuit for adsorption. To limit capital cost and establish cashflow, the mill was constructed without an autoclave. The recovery by gravity and cyanidation was projected to be 83%. A flotation plant was constructed at the tail end of the circuit to recover the additional gold associated with sulphides from the leach circuit tailings. This material is being stockpiled onsite for future oxidation treatment.Detailed engineering was started in early 1999 and the first gold was poured in August 2000. One feature of the project was the use of Contact Lake equipment from Cameco’s Contact Lake project. The entire mill was purchased and equipment re-used where possible. The capital cost for the process facilities was C$3 1.5 million."

Jan 1, 2001

By R. F. Frantz, T. P. McNulty

The upper-level mineralization of the din Buttes, Arizona copper orebody consists primarily of dilute copper silicate impregnation in fault clay and throughout the altered limestone hostrock. Cuprite and native copper are minor with true chrysocolla rare. Owing to the high calcium carbonate and to the hydrogen ion exchange capacity of the clays, acid leaching would be economical only with cheap acid available. Leaching of the silicate copper with reagents other than sulfuric acid is slow and incomplete unless the ore is first heated to disorder the mineralized grains and to reduce partially the contained copper. Following heat treatment, 70 to 90 percent of the nonsulfide copper can be dissolved in aqueous anrmonium carbonate. Recovery of a pregnant solution by counter-current decantation is effective provided ammonium carbonate solution is added to the washing stages in order to oppose adsorption of dissolved copper by clays in the residue. Thermal stripping of the pregnant solution permits recovery of ammonia and carbon dioxide while precipitating copper either as oxide or carbonate. The research program was carried from batch tests through continuous miniplant operation to a five-month campaign in a 20 TPD continuous pilot plant. Pilot plant results, the relationships among key varibles, and a detailed flowsheet are given.

Jan 1, 1973

To find solutions for common safety problems encountered in the handling of trailing cables, based on observations at many different surface mining operations. Approach Practices in handling trailing cables were Investigated through personal visits to over 40 mines, supplemented by visits to cable manufacturers and cable repair service companies. The most effective solutions to the safety problems en-countered were noted and are described In the project final report. Examples are given in this Technology News. Accident Experience Most cable-related injuries occur as a result of workers lifting, pulling, tripping, or being struck by the cable. The Table gives the frequency of occurrence for injuries reported during a recent 3 1/2 year period.

Jan 1, 1982