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By Denholm WT

The main objective of the experimental study was to investigate the dissolution kinetics of various forms of carbon under iron bath converting or smelting-reduction conditions, i.e., particulate, free moving carbon in contact with a turbulent iron melt. Iron/carbon melts were contained in cast magnesia-lined silicon carbide crucibles heated by a medium frequency induction furnace. The melts were stirred by injecting nitrogen through 2 mm I.D. alumina lances submerged to a depth of 50 mm in the 100 mm deep baths. Particulate carbon in the form of graphite, brown coal char and petroleum coke, were dropped directly onto the turbulent bath. The dissolution rates of the various carbon types were monitored by taking periodic bath samples for subsequent carbon analyses. The effect of carbon particle size (1-6.25 mm), the degree of bath turbulence (nitrogen stirring rates of 0-20 litres/min), and bath temperature (1300-1500¦C) were assessed. The analysis of the results was complicated by particle buoyancy effects, but it was established that the dissolution rates of the three carbon types investigated were similar, and increased linearly with increases in the gas stirring power inputs. Particle size had relatively little effect on the dissolution rates.

Jan 1, 1984

By Robert B. Hopler

Explosives research and development has historically been motivated by coal mining. Whether to solve safety problems or to improve productivity and cost, the result has been the same: better explosives products and initiation systems. Today, this process continues at an accelerated pace due to the tools presently available to the explosives and mining industries. Background Explosives have been used in coal mining since the industry's earliest days. Black powder, introduced into metal mining in 1627, undoubtedly was introduced into coal as soon as a need to replace pick work was apparent. Until the invention of the safety fuse by William Bickford in 1832, the only initiation methods available were the straw, quill and miner's squib. Disastrous explosions underground in England brought about studies on their possible causes (Atkinson, 1886). The studies showed that, while explosives contributed to the accidents, the real villain was coal dust, since that was the agent that transmitted the disaster throughout the mine workings. To improve underground safety, research was applied in an attempt to make explosives that could be safely fired in a methane air atmosphere. The Prussian government was apparently the first to establish a testing station for coal mine explosives. This occurred in 1885 (Guttmann, 1909).

Jan 1, 1993

We have been exploring for minerals in Australia for over 100 years and our methods are constantly improving - but why do we pros- pect? Is the effort justified? Obviously the main motive is economic gain. It is now and always has been but conditions are changing rapidly. Once it was the prospector who could cash the nugget. Then it was the syndicate, the small company, an amalgamation of small companies, the large company, the corporation; the multinational corporation - where do we go from there? Early there was personal satisfaction and excitement in out-door activity which gave scope for individual energy, hope and in some cases reward. There still remains the satisfaction, either individual or corporate that a mineral discovery creates new wealth and makes a contribution to the nation's well being. Parallel with developments has always been the growth of restraints on exploration, frequently out of phase with the current mineral developments - miners' rights, licences, titles, royalties, mining laws and regulations, taxation etc. As the operations have become more complex so the restraints have become more confining until it is now very necessary to question whether the chances of economic gain justify the risk and responsibility of mounting costly mineral exploration leading-to extensive capital development.

Jan 1, 1974

By Alan Quiroga

Nestled between Meridian Park and Howard University in the heart of Washington, D.C., the historic block between 14th, V and W streets North- west featured several original struc- tures, many of them dating to the 1800s. During its rich history, this square block has been home to a variety of different organizations including automobile showrooms and repair businesses, a parking garage, various industrial warehouses, and, in recent years, the headquarters of the renowned D.C. nonprofit Martha's Table. The revitalization of the buildings in this block also known as the Collection 14 project involved the transformation of aging and historical structures into a new multi-use development. The redevelopment project was distinguished by the retention of period street-facing building facades (to the extent possible) to preserve the character and culture of the historic neighborhood while revitalizing the block with some modern construction elements. The complexity of the project and difficult subsurface conditions required specialized and extensive sheeting, shoring and underpinning work to be performed. This project had many parties involved, including: • • • • Owner: Madison Investments Owner's representative: Compass Design & Development General contractor: McCullough Construction Civil engineer: Vika Capitol Structural engineer: Ehlert Bryan Architect: Perkins Eastman DC Geotechnical engineer: GEI Consultants Sheeting and shoring contractor: Steele Foundation

Aug 1, 2023

By J S. Kuszmaul

"A computational model of rock blasting is being developed to examine the blasting problems associated with in situ oil shale processing. This model, however, will also be useful as a design tool for the traditional problems in rock blasting. The model includes fundamental treatment of both shock-wave propagation and the accumulation of brittle fracture in the rock. As a result, the model accurately predicts the degree and extent of fracturing as functions of design parameters. The model has proven useful for making parametric studies and for evaluation of alternate blast designs. This paper demonstrates the use of the numerical model to simulate the fracturing induced by the detonation of a vertical explosive column near a bench. The fracturing induced by three differentexplosives indicate that (in the chosen geometry) the most efficient breakage is done by a column of ammonium nitrate and fuel oil mixture (ANFO) used with a toe charge of aluminized ANFO. There was too much unfractured rock left when ANFO was used alone; aluminized ANFO used for the entire explosive column caused excessive fracturing. A final case involves ANFO used alone to fracture a different rock type. This case points out that in a different rock type, the ANFO will not leave excessive unfractured rock."

Jan 1, 1987

J. E. JOHNSON, JR., New York.-It seems to me that it ought to be somebody's job to tie these notch tests with the reversed-stress tests, because the thing that causes failures in structures, in a great majority of cases, is where the material is stressed repeatedly up somewhere near the elastic limit, and the repetition of that stress seems to bring about what I suppose you may call a growth of crystals and that eventually develops into a break. It seems to me that it would be of the greatest value if there could be a coordination of the results of a shock test of some kind with the reversed-stress test, so that we could be sure that a material that had shock-test resistance would have reversed-stress resistance. H. F. MOORE,* Urbana, Ill.-The question raised by the speaker concerning the correlation of results from impact tests of notched bars with the results of repeated-stress tests is a very complicated one. Impact on a specimen sends energy into the specimen, and if the specimen absorbs this energy without fracturing there must be developed both stress and elongation. A notch in the specimen allows but little elongation to take place before rupture, and develops the ductility of the

Jan 5, 1919

By Graham E. Rawlings

Geotechnical investigations for underground projects are subject to a variety of constraints, including factors such as accessibility, geological complexity, thickness of oberburden and finance. As a result, the extent of geological data available for route selection and assessment of underground design and construction problems may vary between wide limits. It is essential that the data collected, the degree to which it is representative, and the confidence with which the problems can be anticipated, should be reflected in the type of contract set up and the way in which the contract documents are written. The paper addresses the methods by which investigations can be focussed to make suitable overall ground assessments for feasibility level studies. Subsequent investigations can then be objectively directed toward obtaining data on specific geotechnlcal problems or aspects which impact tunnel, cavern and shaft design and construction. The extent of investigations at the preliminary and design engineering stages must be closely related to the geotechnlcal surveillance and control during excavation. Fixed-price contracts necessitate a secure geotechnical data base prior to bidding, and the provision of that to the tenderers. By contrast, 'design-as-you-go' contracts minimize the geotechnical information needed before construction, yet require immediate assessment of the excavated ground for determination of support requirements and payment category.

Jan 1, 1983

On Feb. 16, 1948, the Board of Directors of AIME authorized the publishing of "Technical Notes" in METALS TECHNOLOGY. The purpose is to provide prompt publication of very short items of the following general types: I. Results of short investigations which do not warrant a paper. 2. The conclusions of extensive investigations of insufficient general interest to justify a regular paper. 3. Conclusions arising in the course of an investigation, which, because of interest to others in the field, the author wishes to present prior to completion of the investigation. 4. Pertinent factual comment (not mere argument) on the subject matter of previous "Notes." Such Notes will be subject to the approval of the Auxiliary and AIME Publications Committees, but can be handled more promptly than regular papers because they need not be referred to readers. The recommended maxi- mum length is 500 words; notes in excess of 1,000 words will not be considered for this type of publication. A graph or photograph may be included as part of the note when particularly illustrative. As with regular papers, contributions to the new section should be submitted to the Secretary of the AIME. Please furnish two copies each complete with illustrations.

Jan 1, 1948

Marketing of mineral products has not yet succumbed to the degree of pre- dictability and exactitude that is fam- iliar to the engineer or metallurgist in pursuing their profession. Whilst the Great Market of the world economy dic- tates circumstances for the sale of min- eral products, there are more than just buyers and sellers in the determination of the revenue received by the producer. For the engineer or metallurgist he will be required to gain an understanding of these participants and of the peculiar languages of the market place. This will be only one of his tasks in learn- ing to communicate with society, as his responsibilities increase as he climbs the ladder of success. There is un- doubtedly a need for better statistical information so that producers and sell- ers can make an appropriate and earlier response to market conditions. There is in addition, a need for more aggressive concern by raw material producers for the development and promotion of better end use of their products. Undoubtedly the marketing of mineral products will be more influenced by the direct involv- ment of government agencies than has been the case in the past. Whilst that 1. Director - Marketing & Finance, North Broken Hill Limited.

Jan 1, 1975

By Y Hansen, J Petrie

Life Cycle Assessment (LCA) is increasingly being used as a decision-support tool within mining and minerals processing and metals production. However, a number of initiatives have highlighted the current limitations of LCA to accurately reflect the environmental performance of minerals and metals. These programs include:the Mining, Minerals and Sustainable development project (Stewart, 2001); the United Nations Environment Programmme/Society for Environmental Toxicology and Chemistry (UNEP/SETAC) workshop on LCA and metals (NRCan, 2002); the UNEP SETAC Life Cycle Initiative; and the review of the existing ISO 14 040 set of environmental management standards. Together, these initiatives highlighted concerns relating to the ability of LCA to engage with and support metals recycling, to adequately reflect the impacts associated with products from a multi-product orebody, the ability to adequately reflect the toxicity potential of metals in the natural environment and the fact that resource depletion focuses on mining (and not consumption) as the depleting activity in the life cycle of a metal. Additional impact categories to be included in LCA were also suggested. In this paper we demonstrate how existing initiatives are addressing LCA limitations. Finally we present the state of the art in Life Cycle Impact Assessment (LCIA) for two impact categories:resource depletion; and impacted land footprint for solid wastes.

Jan 1, 2004

By C. A. Wert

THE change in mechanical properties accompanying quench aging of carbon in a iron has been known for a number of years. Since the amount of carbon involved is rather small, however, no measurements could be made to correlate the property change with the state of precipitation of the carbide. Indeed, until a few years ago it was not plain which property might be used to indicate the state of the progress of precipitation. Some years ago the internal friction of solid solutions of carbon in a iron was demonstrated, and the use of this phenomenon to ascertain the amount of carbon in solid solution at any given time was developed. Shortly afterward the author made a number of measurements in which changes in electrical resistance, thermoelectric emf, and hardness were determined simultaneously with the internal friction (and hence with the precipitation) ? A little later Dijkstra and Wert measured the change in magnetic coercive force accompanying aging.' The present work was undertaken to inquire into the changes in yield strength accompanying aging. The work was done on specimens made of Puron. These specimens were 0.05 in. in diam and about 6 in. long. Though specimens of this small size are not ideal for yield strength measurements, such specimens are desirable for internal friction meas-

Jan 1, 1952

By Keith Whiting

The Van Stone zinc-lead mine is located in northeastern Washing- ton in Stevens County. It is about 24 km (15 miles) south of the Canadian border and 48 km (30 miles) west of the Idaho line. The deposits occur in late Cambrian age limestones and dolomites of the Metaline Formation. The bedding controls the trend of the zones containing the lenses of zinc-lead mineralization. The Van Stone property and vicinity is almost entirely covered with glacial drift averaging perhaps 6 m (20 ft) in thickness. Outcrops are very sparse. Outcropping gossan with zinc mineralization was first discovered by George Van Stone in 19 13, in what is now known as the South Ore Zone. Only minor trenching was done at that time. The property was idle until the mid- 1920s when Hecla Mining Co. drove several short adits and performed minor diamond drilling. In 1938, Willow Creek Mines of Nevada Inc. acquired the Van Stone plus adjacent parcels and commenced drilling on the known South Ore Zone. In the course of an expanded drilling program, the nonoutcropping North Ore Zone was discovered and was drilled out along a N30°E strike for about 305 m (1000 ft), beyond which point no mineralization was intersected.

Jan 1, 1991

On Feb. 16, 1948, the Board of Directors of AIME authorized the publishing of "Technical Notes" in METALS TECHNOLOGY. The purpose is to provide prompt publication of very shod items of the following general types: I. Results of short investigations which do not warrant a paper. 2. The conclusions of extensive investigations of insufficient general interest to justify a regular paper. 3. Conclusions arising in the course of an investigation, which, because of interest to others in the field, the author wishes to present prior to completion of the investigation. 4. Pertinent factual comment (not mere argument) on the subject matter of previous ''Notes." Such Notes will be subject to the approval of the Auxiliary and AIME Publications Committees, but can be handled more promptly than regular papers because they need not be referred to readers. 'The recommended maximum length is 500 words; notes in excess of 1,000 words will not be considered for this type of publication. A graph or photograph may be included as part of the note when particularly illustrative. As with regular papers, contributions to the new section should be submitted to the Secretary of the AIME. Please furnish two copies each complete with illustrations.

Jan 1, 1948

On Feb. 16, 1948, the Board of Directors of NME authorized the publishing of "Technical Notes" in METALS TECHNOLOGY. The purpose is to provide prompt publication of very short items of the following general types: I. Results of short investigations which do not warrant a paper. 2. The conclusions of extensive investigations of insufficient general interest to justify a regular paper. 3. Conclusions arising in the course of an investigation, which, because of interest to others in the field, the author wishes to present prior to completion of the investigation. 4. Pertinent factual comment (not mere argument) on the subject matter of previous "Notes." Such Notes will be subject to the approval of the Auxiliary and AIME Publications Committees, but can be handled more promptly than regular papers because they need not be referred to readers. The recommended maxi- mum length is 500 words; notes in excess of 1,000 words will not be considered for this type of publication. A graph or photograph may be included as part of the note when particularly illustrative. As with regular papers, contributions to the new section should be submitted to the Secretary of the AIME. Please furnish two copies each complete with illustrations.

Jan 1, 1948

By Ümit Yasar Onder, Tevfik Prof. Dr. Güyagüler

This paper describes the results of an investigation done to determine thermal properties and heat emission of coal measure rocks in Karadon district of Zonguldak Coal Colliery. In Karadon District, depth of working level is about -600 m where the heat problem arises. In the near future, workings will be at deeper levels and working conditions will be more difficult due to high heat emission. At the beginning of the paper the importance of wall rock heat emission in underground mine have been explained and then the amount of heat emission to the ventilating air has been calculated. It has been found out that the strata is the main source of heat in the mine. Therefore, geothermal gradient of the region has also been determined simply by measuring the virgin rock temperatures in different levels of the mine. All other data directly related with heat emission from different sources has been collected and has been analyzed by using a special computer package. As a conclusion, total heat and moisture content in ventilating air and heat balance has been determined for Karadon Coal Mine. In addition, some recommendations and suggestions have been made for the future works when the mine workings go to the deeper levels.

Jan 1, 1995

By M. G. Ayat

Engineers in the field of coal preparation are continually striving to increase the efficiency of various circuits used in preparation plants. Undoubtedly, one of the important factors concerning the processing efficiency of a coal preparation plant is improved analyses and control of the processing equipment. The necessary link between the performance criteria of a circuit may be provided through on-line determination of various parameters. Currently, there are a certain number of on-line instruments developed for measurement of ash content of coal (Watt and Sowerby, 1983; Kawatra, 1976; Fauth et al., 1984; Lyman and Chester, 1980), moisture content (Hall et al., 1969), and sulfur content (Stewart et al., 1974). In the case of coal separatory units, these parameters are often directly related to the quality of the product. In other words, the extent of misplacement of refuse in the product, or vice versa, would indicate the performance characteristics of any particular coal washing equipment. Partition curves are therefore established to predict the performance of coal cleaning operations. Conventional sampling and testing is currently the major tool with which partition curves are produced and the performance efficiency of the operation is assessed. While conventional analysis techniques are accurate, they are slow and time-consuming.

Jan 1, 1987

By A. T. Tye

WHEN the roughing tables operated in 1923 were abandoned, all the coarse iron pyrite for-merly removed by the tables had to be ground to flotation size, which caused an increased power con-sumption of 2 kw.-hr. per ton. Recently, by increasing the tonnage, this has been reduced to a total of 16.6 kw.-hr. per ton. The cost of repairs has been slightly reduced by using an alkaline circuit instead of the acid mine water used in 1923. Other economies from elim-inating roughing tables and the finishing tables have more than compensated for the extra grinding and the total costs have remained practically the same, until the first part of 1927, when, with increased tonnage, the total cost has decreased to 72 cents and the repair cost to 9 cents. In 1923, with a combined gravity and bulk flotation flowsheet, the grade of concentrate was only 4.38 per cent copper. With preferential flotation this has in-creased to over 17 per cent copper. The tailing has decreased from 0.29 per cent -copper to 0.18 per cent. The copper recovery, instead of decreasing; as might be expected, has increased from 87.4 per cent to, 91.5 per cent. The silver recovery has also increased from 88

Jan 8, 1927

Ever since A Decade of Digital Computing in the Minerals Industry was published in 1969, mining men have expressed the need for an additional reference on computer methods. It was felt such a volume should spell out the "how to" of computer applications in the solution of their problems. Computers in the minerals industry will be 20 years old when the 1979 SME Fall Meeting and the 16th International Symposium on the Application of Computers and Operations Research in the Mineral Industry (APCOM) take place jointly in Tucson, AZ. On such an occasion it was thought appropriate to publish an anniversary volume which reviewed current practices and projected what might prevail as computer methods for the future. Thus was born the idea to publish Computer Methods for the 80's. The first planning meeting for this volume took place in Las Vegas, NV, during the 1976 annual meeting of the American Institute of Mining, Metallurgical, and Petroleum Engineers. It quickly became evident that no single computer method existed to solve most mining problems; rather, mining computer methods are generally tailored to fit unique geologic, mining, and organizational conditions. Hence a format which included both the theory and practice for each of the computer applications was adopted for this volume.

Jan 1, 1979

F. C. LANGENBERGW.*at 8ertoivn,M ass. (written cliscussiont).-I am inclined to the view that the change in physical properties encountered in the material with which the authors are working is due to the relief of internal strains. The statement, on page 1.098 of their paper, calling attention to the fact that this phenomenon disappeared when the material was rolled into 1 7/8 -in. square billets is of particular interest. It is certain that the internal strains set lip by cooling in a small billet of this size would be much less than those produced in a billet having a larger cross-section cooling under the same conditions. The statement that the physical properties of a given test bar were materially changed by standing has been brought to my attention in connection with the testing of gun forgings. I have made a number of observations on forgings produced at Watertown Arsenal to ascertain whether any change in ductility was produced by the aging of the test specimens. The results were always negative, but this can be explained by the fact that ii gun forging is generally a forging that has been quenched and subsequently drawn at a relatively high temperature.

Jan 10, 1919

US Tin Mission To Study Costs in Far East A move to obtain adequate supplies of tin at prices the United States is willing to pay was initiated when the interagency tin mission left for the Far East. The Mission, which includes representatives of the Reconstruction Finance Corporation, State Department, Defense Minerals Procurement Agency and the Bureau of Mines will go to Indonesia and Malaya. The primary purpose of the mission, according to officials, will be to study tin production costs, not to negotiate for the purchase of tin. The mission will be prepared to enter into negotiations, if the Far Eastern producers are amenable. The United States withdrew as a large-scale buyer of tin some months ago in protest against what it considered exorbitant prices being charged in the Singapore market. Subsequent attempts to negotiate for a steady tin supply at what this country considers reasonable prices have been unavailing. The U. S. is prepared to enter into a two or three year contract with the price of tin somewhere between $1.00 to $1.12 per lb. The decision to abstain from the market has not yet put a squeeze on U. S. supplies. Substantial quantities of tin still are coming in from Malaya under an old contract.

Jan 12, 1951