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By Albert F. J. Bordeaux

The following general survey of the character and present condition of the silver-mines of Mexico, though not offered as a detailed treatise, has been prepared with care, is believed to be generally up-to-date, and is offered as a summary which may be found useful by mining engineers. For several centuries Mexico has ranked first anlong the silver-producing countries. It is now second as a copper-producer, and seventh as a gold-producer, with a fast-increasing output every year. The total amount of capital invested in its mining- and smelting-works exceeds $250,000,000, while the value of the yearly metallic production is $160,000,000. There are more than 20,000 recorded mining properties. The silver-mines of Mexico represent deposits of three principal classes: (1) veins and stock-works in eruptive rocks; (2) fissure-veins crossing the crystalline schists, granite, diorite, etc.; and (3) veins and replacement-deposits in limestone. The true fissure-veins in some districts contain (in value) vol. xxr1x.—22

Jan 1, 1909

By P. Seppanen

Cemented fill was first introduced at the Keretti mine in 1952, but entailed high cement costs, the need for stope preparation, slimes handling, clean-up and maintenance, increased mine dewatering, segregation of fill and long setting times. In the 1970s research began into the use of iron blast-furnace slag as a binding agent and by 1989 Pyhasalmi, Vihanti, Keretti, Vammala and Enonkoski had saved US $11 000 000 by using slag binders instead of cement. Viscaria in Sweden and Tara in Ireland also use slag as 90-100% of total binder, although their backfilling methods vary. The main area of interest in slag research is determining the activation methods for initiating the binding reactions; it is also important to achieve other characteristics such as resistance to corrosion by sulphuric ion. New backfilling techniques developed during the 1980s included the use of high-density cemented tailings fill at Vammala and porous cemented rockfill at Enonkoski and Viscaria. Future developments focus on concepts such as integration of mining and milling with backfilling and the achievement of total underground disposal of wastes

Dec 1, 1995

EXCEPT for the material, the same method that you used in alloying gold is used in alloying silver, but its alloy is fine copper. Just as the silver does in gold, so copper in silver diminishes and lowers its fineness and increases its quantity. If half the value is surpassed it is no longer called silver but copper containing silver, as I told you of gold. But in my opinion one could also say silver of 5,4, or 3 leghe or even of one. How- ever, these terms are of no importance for our purpose. It is enough that you suppose that the whole quantity of silver that you have is twelve parts. If you put one part of copper in h with the melt, you will say [74] that you have 11-lega silver and that it is in weight thirteen of the first parts† and so on, when you add two to ten and four to eight, always naming the quantity of the fine silver just as you did with the gold, either

Jan 1, 1942

The Commissioner of Education has issued a call for a public conference on business training for engineers and engineering training for students of business. This conference, national in scope and character fully representative of all interests, will be held in Washington, D. C. on June 23 and 24. Educational institutions, commercial organizations, and educational and engineering societies will be given an opportunity to state their views. Engineers, educators and business men will be invited to discuss the following major topics: Business Training for the Engineer; Engineering Training for Commercial Enterprises; Significance of the. War Experience for Engineering Education; Training of the Engineer for Foreign Projects. This conference has been called on behalf of the Conference Committee on Commercial Engineering. This Committee is composed of administrative professors in engineering and commerce from several of the large educational institutions and representatives from the American Institute of Mining and Metallurgical Engineers, Society for the Promotion of Engineering Education, The American Society of Civil Engineers, American Institute of Electrical Engineers, American Society .of Mechanical Engineers, and a committee f fifteen on Educational Preparation for Foreign Service.

Jan 6, 1919

The June General Meeting of the Institute was held in Kelvin House, Johannesburg, on 18th June, 1969, at 4.30 p.m. Mr J. K. E. Douglas (Vice-President) was in the Chair. There were also present fourteen Members, Messrs R. J. Adamson, F. P. Bath, D. M. Jamieson, D. G. Maxwell, Dr J. T. McIntyre, and Mr P. W. J. van Rensburg (Council Members), Messrs B. F. Berry, A. F. Lee, J. E. van Leeuwen, G. G. Nicolson, N. F. Peverett, Dr A. G. Raper, Messrs E. R. Rudolph and H. R. Reid. Five Associate Members, Messrs T. D. Brown, M. R. Fuller-Good, J. S. Freer, Dr P. R. Jochens and Mr D. A. Viljoen. One Graduate, Mr P. G. Mrkusic. Five Students, Messrs N. A. Barcza, J. A. Cruise, R. P. W. Henrard, D. I. Ossin and J. C. M. Wethmar. Nine Visitors, Messrs M. Badenhorst, N. J. Bovey, H. H. Herold, Dr H. J. S. Kriek, Messrs M. S. Rennie, B. B. Segal, S. Selmer-Olsen, O. A. W. Strydom and B. Yates. Secretary, Mr D. C. Visser. Total present: Thirty-six. MINUTES The Vice-President: "May we confirm the minutes of the Monthly General Meetings held on 24th March, 16th April and 21st May, 1969 as published in the Journal?" Agreed. MEMBERSHIP The Vice-President: "I have much pleasure in announcing that the names of the undermentioned candidates having been published in accordance with By-Law 5.2.2, Council has elected them to membership of the Institute in the following grades: Members: Wilfred Desmond Morgan, Abraham Kriek. Associate Members: Rodger Neville Hampson, Robert Richard Booth Lodge. Graduates: Beverley Hugh Waiters, Gwynne Hugh Johnston. Students: Colin Edward Alvery, Peter Marthinus Haikes, Charles Aubrey Husband, John Nowell Randell, Frederick Johannes Jacobus Blaauw, Johannes Andries Breytenbach, Peter Vos, Frederik Hendrik Coetzee, Petrus Nicolaas Jacobus Smit, Patrick Alien Boardman, Robert Nelson Guest. "May I welcome the newly elected members to the Institute." (Applause.) ELECTION OF SCRUTINEERS FOR THE 1969-70 BALLOT FOR COUNCIL The Vice-President: "In terms of By-Law 9.4, I now call for nominations for scrutineers for the 1969-70 ballot for CounciL" P. W. J. van Rensborg: "I wish to nominate Messrs R. C. J. Goode, V. C. Robinson, J. K. E. Douglas, P. Lambooy, D. G. Maxwell, H. Britten and H. Simon as scrutineers."

By Sharmil Markar M

Ballarat Goldfields Limited is currently re-opening the old workings of the East Ballarat Goldfield which contain an estimated 1800 ML of groundwater. The disposal of this 'minewater' was of concern: the minewater is of moderate salinity; increased salinity levels have interfered with agriculture and water use at a number of locations downstream from Ballarat. Extensive numerical studies indicated that treated minewater could be discharged into the Ballarat Creek system for dilution by sewage effluent and by surface runoff after rainfall events. An automatic real-time salinity management system has been developed to enable the disposal of saline minewater in this fashion. A desk top computer operates the system: discharge and salinity readings are taken automatically each hour and filed away; the maximum allowable rate of discharge of treated minewater is calculated; pumps are switched on and off. The system readily enables daily, weekly and monthly data reports together with floppy disks of 'raw' data to be prepared in formats suitable for direct submission to the Victorian Environmental Protection Authority.

Jan 1, 1990

"The QEMSCAN system is the third generation of automated mineral analysis systems that began with the QEM*SEM at CSIRO 30 years ago (Butcher et al. 2000). It is now a successful commercial instrument with 39 instruments in operation around the world. Back Scattered Electrons (BSE) and Energy Dispersive (EDS) X-Ray spectra are used to create digital mineral images with mineral identification occurring online. Low-count EDS spectra are used preferentially to BSE brightness, allowing minerals to be accurately identified by chemical composition. Individual minerals or groups of similar compositions are identified by comparison to a comprehensive mineral database incorporated into the QEMSCAN software. Optical mineralogy and Scanning Electron Microscopy is a metallurgists’ tool for determining the ore process mineralogy and delivering a better flowsheet. These techniques have limitations, provide limited information and sometimes fail to provide representative information. In contrast, QEMSCAN provides information on the nature and occurrence of all mineral species present plus the liberation characteristics, looking at thousands of particles in the sample presented. Some of the data presented includes:• Particle and grain sizes• Dominant mineral species• Particle shape• Calculated metal content• Density• Deportment of elements of interest between the mineral phases• Quantitative mineralogy• Mineral associations, locking and liberation• Textural relationships (particle images)It can also be used on concentrates, polished sections or drill core. This is a significant improvement in ore characterisation providing lithology, mineralogy, liberation, ore grade and porosity from a sample. Theoretical grade-recovery curves can be created to be mineralogically limited from QEMSCAN analysis which, when compared with metallurgical results, are valuable in evaluating whether liberation or chemical selectivity is driving flotation performance. A number of case study examples are given where the QEMSCAN had a significant bearing on future project development at an early stage of exploration and mine development."

Jan 1, 2012

In-pit crushing systems have been known in the mining industry for many decades. The question whether in-pit crushing is a viable option has often been asked. More than 200 mobile and semi mobile crushing systems have been installed worldwide at various locations and applications. Economic pressures have forced mine operators to reconsider the use of a conventional truck-shovel operation and have contributed enormously to the development of in-pit crushing and conveying systems. The in-pit crushing concepts have varying mobility capabilities. These range from fixed, stationary crushing plants to semi-mobile and fully mobile crushing plants. All these systems are operated in connection with a conveying system. In general in-pit crushing systems have technical and economical cost advantages over truck-shovel operation, particularly as mine capacities increase and mines become deeper. The integration of an in-pit crushing system represents a significant up-front capital investment and the mine is only able to depreciate the capital investment over a sufficient mine life including plant capacity to realise the benefit of the much lower operating cost.

Jan 1, 2003

FOR this Famous Mining Enterprise issue MINING ENGINEERING selected the company that started the zinc in dustry in the United States. The New Jersey Zinc Co. has been a supplier of zinc products to the nation's industries for more than 104 years. Its Horse Head trade mark is famous throughout the world.

Jan 12, 1953

By Nick O’Riordan, Kaitlyn L. Fleming, Michael Riemer, Youssef M. A. Hashash, Stephen McLandrich, Mohamad Jammoul, Pierre Gouvin, Andrew Yeskoo

"To accommodate urbanization, cities are developing more underground space as a means to house public transportation systems and other entities. Underground developments often require construction of deep excavations in an environment dense with infrastructure. The success of such a project is related to the amount of impact imposed on adjacent structures and economic activity; impact should be limited to insignificant amounts in order to mitigate damage and disruption. Thus, large-scale urban construction projects require extensive monitoring of ground movements and installed support performance to facilitate informed decisions for adjustment of construction activities and support design when necessary.In downtown San Francisco, a unique large-scale excavation in saturated soft soils was constructed for the Transbay Transit Center (TTC). Construction of the excavation began in April 2012 and was completed almost two years later in February 2014. To monitor ground and structure response to construction, the project team used an extensive instrumentation network that included automatic inclinometers, piezometers, strain gages and total stations paired with survey markers. Innovative imaging techniques developed a record of construction in order to relate measured deformations to construction activity.Transbay Transit CenterThe Transbay Transit Center (TTC) is being constructed as a modern day transportation hub in downtown San Francisco to replace the former Transbay Terminal. The project is located in the South of Market area, less than half a mile from the San Francisco Bay. The final center will connect eight counties in the Bay Area through 11 different transportation systems, some of which will be housed in the TTC including Caltrain, Golden Gate Transit and California High Speed Rail. The aboveground structure will consist of two levels for retail and a third level with a bus terminal beneath a rooftop garden. There will be two subgrade levels to serve as a lower concourse and the train platforms. This structure required construction of a deep excavation closely surrounded by buildings and roads in an area thriving with economic activity."

Jan 1, 2015

One-half fare return rate again available to members of the Institute and dependent members of their families. DON'T FORGET YOUR RAILROAD CERTIFICATE Over 300 members of the A. I. M. E. and dependent mem-bers of their families attending the last annual meeting se-cured return railroad tickets at half price by means of the railroad certificate, thereby saving several thousand dollars. DIRECTIONS 1. Be sure to obtain your railroad certificate when pur-chasing your railroad tickets for the meeting or you will lose money. 2. Purchase your tickets at regular one-way adult tariff fare between the dates specified for your territory in the accom-panying table. 3. Present your certificate for valida-tion at Institute headquarters in New York immediately after registration. Certificates will be validated on Feb. 21 and 22 between 9 a. m. and 5.30 p. in. 4. You must use your return half-rate tickets not later than Feb. 27. 5. Use the same route for both going and return trip. PLEASE REMEMBER THIS 1. Unless-250 certificates are validated at headquarters it will be impossible for anyone to secure the reduced rate. 2. Unless you secure a certificate you cannot take advantage. of the half-rate return fare, even if the necessary 250 certificates are validated.

Jan 2, 1928

By H. R. Peterson, G. J. Lipovetz, W. F. McDermott

One of the major improvements in ore grinding economics in North America has been the introduction of autogenous grinding. Pickands Mather & Co. has been active in the development of autogenous grinding since 1957. This early work led to the application of autogenous grinding to the Wabush mines ore in 1965, with the installation of six 24 ft diam by 8 ft long, 1750-hp mills. Development work recently completed in 1971 on another ore has led to the decision to install five 36 x 15-ft, 12,000-hp mills when this project goes ahead. Between these two decisions lies a tremendous amount of research, development and application of autogenous grinding to a variety of ores. The Pickands Mather Metallurgical and Research Laboratory in Hibbing, Minn., has tested ores from 9 different deposits in its pi- lot plant facility. Some of these deposits have as much difference within their own ore types as there is between the various deposits. Therefore, it is safe to say that over twenty different ore types have been tested and flowsheets developed for commercial applications. Of the nine projects, three are in operation. These are Wabush mines in Labrador, Canada,' Savage River mines in Tasmania,' and The Griffith mine in Red Lake, Ont., Canada.'

Jan 11, 1972

Discussion of the paper of George K. Burgess, J. J. Crowe, H. S. Rawdon, and R. G. Waltenberg, Finishing Temperatures and Properties of Rails. By Albert Sauveur, R. Trimble, William R. Webster, P. H. Dudley, George B. Waterhouse, M. H. Wickhorst, James Aston, E. F. Kenney, A. W. Gibbs, W. A. Aiken, and G. K. Burgess . . 767 Discussion of the paper of Albert Sauveur, Manganese Steel and the Allotropic Theory. By G. K. Burgess and J. E. Stead 787 Discussion of the paper of J. V. Emmons, The Surface Decarbonization of Tool Steel. By Albert Sauveur, Bradley Stoughton, E. G. Spilsbury, Oliver W. Storey, H. O. Hofman, and J. V..Emmons 790 Discussion of the paper of Richard H. Rice, Turbo Blowers for Blast-Furnace Blowing. By S. G. Valentine, W. McA. Johnson, L. Iversen, J. E. Johnson, Jr., Karl Nibecker, W. Trinks, Otto Banner, H. S. Braman, Arthur G. McKee, and Richard H. Rice . . . 794 Discussion of the paper of J. K. Furst, The Plant of the Duplex Process for Making Steel. By W. McA. Johnson, Arthur G. McKee, Henry D. Hubard, and Bradley Stoughton . . 810 Discussion of the paper of E. C. Harder, The Iron Industry in Brazil. By I. C. White and E. C. Harder 813

Jan 4, 1915

By A. F. Meger

REPRESENTED here are the ideas and varied experiences of many people in the Hanna Coal Co. who have helped develop, over a number of years, an efficient and flexible method for spraying con- trolled amounts of oil on coal. Since the George- town preparation plant began operations early in 1951, oil treatment of coal has received special attention. It is believed that oil treating will satisfy present customers and also attract new markets. The first step in developing the new method of oil spraying was the construction of a dust cabinet for testing 50-lb samples of treated coal with the available oil sprays on the market. Tests results were tabulated for both indoor and outdoor storage.

Jan 7, 1954

By Frederick Prime

TO an association like the one before which I read this paper, few questions can be more important and constantly recurring than the following, viz.: "What economy can be effected in the manufacture of American iron?" And it is the one with which I purpose to deal in this paper ; premising, however, that my object is merely to indicate the direction in which an answer should be sought for, rather than to give it myself. This subject may be divided into two parts, "Economy in the production of pig-iron," and "Economy in the manufacture of wrought-iron ;" but it is to the former alone that I shall confine myself this evening.

By T. N. Williamson

The art of drilling tunnels is still in its infancy, although it is 70 years since the first tunnel driver was put into operation. (It was used to drive 6000 ft of tunnel under the English Channel.) But during the next 60 years neither government agencies nor private enterprise could find much of a future in tunnel drivers. It was difficult to justify the heavy investments, labor was opposed to the machines, and there had been some spectacular failures. In the last ten years, however, there have been changes. Tunnel drivers are being tried with increasing frequency-in spite of the fact that a large number of them have had to be abandoned on site.

Jan 7, 1965

By R. Strandahl

As one of the largest private utilities globally, E.ON currently operates hard coal fired power stations in with a total installed capacity of some 20.000 MW: These thermal power plants consume domestic coals but are increasingly dependent on imported seaborne traded coal (in 2009 approx. 17 million t). Knowing that the company’s reputation and credibility depends in part on how E.ON lives up to the responsibilities along the entire energy value chain, E.ON takes a collaborative approach with the various suppliers. Hence, E.ON’s responsible policy also applies to the procurement of coal; the utility launched in 2009 a comprehensive Corporate Responsibility program with special focus on supply-chain audits. One of the first coal audits focussed on the Cerrejón coal mine in North Eastern Colombia. The authors will share the key learning’s and experience from the Colombian audit jointly conducted with an independent auditor and E.ON experts from the Corporate CR and E.ON Energy Trading.

Jan 1, 2011

By J. D. Koch

A 'project' is defined here as a process in which an idea is developed from its inception until either it is discarded or the product of the idea has been accepted by the ultimate user. The phases in a project, particularly the early phases, are examined, and project organization is described and contrasted with a functional line-management type of organization. Emphasis is placed on comprehensive definition, which is vitally important to the achievement of the goals of time, cost, and quality set for a project.

Jan 1, 1981

The South African Institute for Mining and Metallurgy celebrated its 95th anniversary with a banquet at The Carlton on Friday, 2nd June, 1989. This event was attended by 600 people, including the Presidents of AS&TS, constituent societies, and other kindred bodies, together with members and their guests. The guest speaker was Mr Muray Hofmeyr, Chairman of the Johannesburg Consolidated Investment Company Limited, who gave an interesting and thought-provoking talk entitled 'Will we still be the best in the year 2001'

Jan 1, 1989

By Thomas F. Stinson

Energy-producing states see severance taxes as attractive sources of increased revenues for otherwise tight budgets. Consumers in energy-poor states, however, protest that current rates are excessive and have moved to obtain a reduction. The US Supreme Court heard two cases questioning such taxes during its 1981 term, and Congress, in each of its last two sessions, has seriously considered measures placing a ceiling on severance tax rates. Although discussions usually focus on coal severance taxes levied by Montana and Wyoming, ramifications of changes in national policy are much larger, potentially affecting mineral taxes in all states. Severance taxes yield substantial revenues in some states, as illustrated in the accompanying table. In fiscal 1980, Texas collected more than $1.5 billion from such taxes, while Louisiana, Alaska, and Oklahoma collected $525 million, $507 million, and $436 million, respectively. Oil and natural gas production were the major items taxed. While the table shows only the 10 states with the largest severance tax collections, a total of 17 states had severance tax receipts exceeding $10 million in 1980. The enormous increases in severance tax revenue between 1970 and 1980 can be seen from the table by comparing columns A and B. For the 10 states shown, revenues increased from $650 million to $3.8 billion during that period, due to a combination of higher prices, increased production, and new or increased taxes. In most states, increases in prices and production were more evident than higher tax rates. Although the revenue increase is impressive, it understates the extent of changes occurring during the past decade. Since tax collections are shown for fiscal 1980, the full impact of the decontrol of domestic oil prices is not evident. Also, taxes on natural gas reflect controlled prices. When full de-control of natural gas occurs, significantly higher revenues can be expected in gas-producing states, even if tax rates, production, and world prices remain constant. These increases in severance tax revenues, coupled with further increases expected to accompany natural gas decontrol, have produced fears that a substantial transfer of income is taking place from residents of energy-poor states to those living in energy-rich areas. Others worry that increased severance tax revenues will be used to substitute for a substantial portion of state taxes that would have otherwise been collected from firms and individuals. The resulting improvements in tax climate, it is thought, may encourage firms and workers to migrate to energy-producing states. While these issues are often portrayed as pitting energy have-nots against the haves, such is not entirely the case. Much of the original impetus for limits on coal taxes came from Texas residents, the state collecting the most severance tax revenue. One way of gaining perspective on these concerns is by examining severance taxes per capita and as a percent of state tax collections (see columns C and D in the table). When this is done, Alaska, where 1980 taxes on oil and gas production totaled more than $1300 per capita (and 35% of all state tax collections), stands out as a special case. There, the state was able to eliminate some individual taxes, place revenues in a permanent trust fund, and consider offering a rebate of some previous income

Jan 4, 1982