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By Cristina Echavarría

MAIN POINTS ? The region: opportunities and limitations ? Overview of main issues emerging from MMSD in South America ? Who comprises the local community? ? What are the main challenges? ? Some suggestions for companies to improve their contribution to local sustainable development of mineral rich localities THE REGIONAL CONTEXT 1. The region is a producer of minerals contributing over 20% to world metal production. It consumes only 8% 2. Significant diversity of national contexts-both between countries and within countries 3. Variable but predominant need for strengthening of government and community institutions and governance, especially at the local level 4. Dearth of baseline information for decision making 5. Sustained social spending during early 90?s as a consequence of economic recovery and fiscal policy, produced important advances in education and health 6. Despite government efforts in most countries poverty continues growing 7. Highly inequitable distribution of wealth persists

May 1, 2002

The Forestry Reclamation Approach (FRA) specifies that the upper 1.22 m of material on the reclaimed surface should be left as uncompacted as possible to facilitate tree root growth. One of the main concerns about applying the FRA to steep slopes is that the upper 1.22 m of material could cause the reclaimed slopes to be unstable. Successful application of FRA on flat and rolling surfaces precipitated this investigation. Details of a field investigation conducted at a steep-slope mine are available in an earlier publication (Kumar and Sweigard, 2011). A total of 70 survey monuments were driven into the slope in a regular pattern to monitor slope movement. Quarterly surveys of the monuments were done to quantify any type of mass movement either horizontally or vertically. The methodology proposed for slope movement was verified using numerical models. Analytical models based on limit equilibrium technique and numerical models based on the finite element method were developed for slope stability analysis. The limit equilibrium analysis was done using Geo-Slope software following the Simplified Bishop Method. The finite element (FEM) numerical model was developed using the Plaxis computer program following the strength reduction technique. Two kinds of slope stability analysis were performed: first with the top 1.22 m of loose material and second without top loose material. Finally, the field investigation results were compared with stability analysis results. Both of these approaches showed that application of the FRA on steep slopes is not causing any significant instability problems that would not exist otherwise for overly steepened slopes. Keywords: Forestry reclamation approach, steep slope, slope movement, factor of safety

Feb 27, 2013

By A. F. Neil, A. S. Bahaj, P. Watkins, P. M. Hyslop, C. E. Kirby, P. A. B. James

The results of initial work indicate that for 3 of the 5 quarry sands bioleaching reduces the iron oxide content to a commercially acceptable 0.035 wt% Fe20 3, although the time taken to achieve this is 14-22 days against a target leach time of 7 day. Subsequent work has identified strains of Aspergillus niger that are more efficient at producing the array of complexing agents for iron and is yielding excellent and rapid reductions in Fe levels. Potentially, bioleaching offers a more environmentally friendly and energy-efficient process for the removal of Fe from glass-making sands than conventional routes but the production of organic acids by fermentation must be achievable with low-cost substrates such as sugar-beet molasses and lactose permeates for bioleaching to offer a commercially viable alternative to treatment with hot mineral acids. Silica sands usually contain three groups of Fe minerals: iron oxyhydroxides, which comprise crystalline types such as goethite and limonite tending to occur as thin, discontinuous coatings and in cracks and crevices on the surface of the quartz; the assemblage of heavy trace minerals, which include ilmenite, rutile, leucoxene, chromite and haematite, commonly present at levels of 0.1 wt% or less as discrete grains or sometimes cemented to the quartz; and clay minerals cemented in pits on the surface of the quartz and in association with weathered, discrete feldspars. The response of the assemblage of iron minerals to short periods of exposure to hot inorganic acids is broadly related to which group they belong to, those that form coatings being accessible to acid and tending to react rapidly whereas the trace minerals are usually resistant and react very slowly, if at all, and the clays are probably digested. The note reports on a preliminary study of the use of microorganisms to develop an alternative clean technology that will give results comparable to those achievable with hot inorganic mineral acids but with more environmentally acceptable procedures. Various fungi and bacteria produce organic acids when grown in certain media. When these acids come into contact with Fe-stained sand grains the iron is removed as soluble complexes. Several strains of Aspergillus niger have been found to produce organic acids from sugar, predominantly citric, gluconic and oxalic acids, their relative yields depending on cultivation medium and conditions. Sand samples were prepared from five quarries in the UK: Levenseat, Lothian; Redhill, Surrey; King's Lynn, Norfolk; Chelford, Cheshire; and Oakamoor, Staffordshire; ranging in iron oxide content from 0.035 to 0.153 wt% Fe203

Jun 18, 1905

THE first session of this meeting was held Tuesday evening, in the chamber of the Common Council, the President, Mr. David Thomas, in the chair. Mayor Carroll, of Troy, gave a cordial welcome to the Institute, which was responded to, on behalf of the Institute, by the first Vice-President, Mr. R. W. Raymond. The Council reported the names proposed for membership with recommendation for election. The following named gentlemen were duly elected: Anthony, J., . .Williamstown, Pa. Babcock, George, . . .Troy, N. Y. Blake, Theo. A., . . . . . . Sa n Francisco, Cal. Blossom, T. M., . . . . . . New Pork. Boalt, James A., . . .San Francisco, Cal. Bowman, Amos, . . . . San Francisco, Cal. Chester, Prof. A. H., . .Clinton, N. Y. Dewey, C., . Pittsfield, Mass. Dock, Gilliard, . Shamokin, Pa. Emerson, O. D., . .New York. Endres, John J., . .Pittsburgh, Pa. Firmstone, Frank, . Easton, Pa. Fowle, W. B., . Philadelphia, Pa. Frazier, Prof. B. W., . . .Bethlehem, Pa. Gardner, George A., . New Pork. Goodyear, Watson A., . .6an Francisco, C al. Griswold, Chester, . Troy, N. P. Griswold, J. A.,* . . .Troy, N. Y. Hague, J. D., . . .San Francisco, Cal. Hahn, 0. H., . .Eureka, Nev. Harkness, T. C., . . . . . . Wilkes-Barre, Pa Harris, Samuel, . . .Hudson, N . Y. Henry, &. T., . Oxford, N. J. Holley, A. L., . .Brooklyn, N. Y. Howe, H. W., . . .Troy, N. Y. Hunt, Dr. T. Sterry, . Boston, Mass. Jannet, J., . Troy, N. Y. Knapp, John A., . .New Pork. Laughlin, Henry A., . . .Pittsburgh, Pa.

By Marianne Snedeker

In January we published a questionnaire asking about the content of MINING ENGINEERING and about your interests. At the same time we hired an outside firm, READEX Inc., of St. Paul, MN, to send the same questionnaire to a sampling of about 1000 US members, selected on an nth name basis, so that we could have some preliminary numbers for the Annual Meeting in February. READEX sent us the final results of its survey in March. At that time, 525 responses of the 992 surveys sent out had been returned, for a 52.9% response, an extraordinarily high return for a low-key (no incentive for return) random sampling. On May 7, we cut off on tabulating returns from the magazine so that we could report the results to you in this issue. At that time, we had 594 questionnaires returned. Our 594 and READEX's 525 (we have assumed that relatively few people returned both), represent a 1119 return, about 3.5% of the approximately 32,000 who received the January issue of ME. About ME Through responses to the questionnaire, we were hoping to learn more about you, your interests, and how the magazine could better serve you. Those of you who responded, told us something positive-you look at or read the magazine. Of the 1119 respondents, 1068 or 95.4% indicated that they had read or looked through the November and/or December issues. Those of you who refer to the magazine once are 466 or 42.6%. Those of you who refer to the magazine two or three times are 559 or 51.1%. Those of you who refer to the magazine four or more times are 68 or 6.2%. How much time do you spend reading the magazine? Of those responding to this question: 186 spent up to 1/2 hr 16.6% 590 spent up to 1 hr 52.7% 292 spent 1-2 hr 26.1% 51 spent more than 2 hr 4.6% In an informal survey among our staff, we determined that most people spend 1/2 to 1 hr reading magazines to which they subscribe at home. Does that match your experience? Many of you, 764 or 69.4%, clip your magazine for further reference. Also, many of you, 513 or 64.2%, do not pass your copy on to another reader, indicating perhaps that you are clipping it or receiving the magazine at home. Those magazines that are passed on reach: 2 people - 159 - 20.0% 3-5 people - 95 - 11.9% 5 or more - 31 - 3.9% Answers to what portions of the magazine you find useful indicated that the top three were Industry News, feature articles, and Technical Papers; see Table 1. The "other" category included advertising-display, classified, and employment-Coming Events, product information, Washington Survey, new books, the reader service card, and Engineering Fundamentals. Of those responding, 797 or 75.3% indicated a preference for dual notation of SI (metric) with English units; 228 or 21.5% preferred all SI units; while 34 or 3.2% preferred SI with dual notation of other metric units. Based on the preliminary numbers reported by READEX for this question, the MINING ENGINEERING Committee in February voted to return to a policy of dual notation. This decision has been implemented. We asked for your appraisal of the technical level of the magazine. Of those responding, 78 or 7.4% indicated it is too technical, 147 or 13.8% indicated it is not technical enough, and 836 or 78.8% judged it to have the correct tech¬nical level. In response to the question about whether you like to read an occasional feature that is not technically oriented, 32 said no, but an overwhelming 97% (1024) said yes. Of the specific topics, 785 like history, 558 political or socioeconomic articles, 440 career development, and 373 human interest. Other topics suggested included new disciplines, mineral resources of the world by

Jan 6, 1982

By H. F. Yancey, E. Zane

"INTRODUCTION The term ""friability"" as applied to coal may be defined as the physical property of coal which expresses its tendency to become reduced in size during handling as a result of such external forces as impact and attrition. Thus friability is a quantitative concept and property, and hence can only be defined in relative terms or in terms of measurement. Methods of measurement are difficult to formulate and apply because coal is anything but homogeneous in physical structure and chemical constitution. aMoreover, friability itself is a composite property obviously dependent upon a group of other specific characteristics such as cleavage, fracture, tenacity, hardness, and elasticity, which vary from coal to coal with change in rank and even between individual coals of the same rank. These characteristics affect the friability values of different coals to varying degrees, but this fact does not impair the usefulness of and the need for friability measurements.The amount of breakage or degradation in size that a coal suffers in mining, preparation, and subsequent handling depends upon its inherent friability and the severity of the handling treatment which it receives from the time it is taken from the bed until it reaches the consumer. The value of the coal to the producer and jobber depends in large measure upon these same factors--friability and severity of treatment—because the larger sizes still command a premium in the ordinary market. Although much has been accomplished by the coal-producing industry in minimizing the breakage of coal in mining and preparation, it is apparent that additional reductions in breakage must await further improvements in design of coal-handling equipment. Such improvements will result from more intensive investigations of the extent of breakage or degradation in size occasioned by specific mining and handling operations and the development and application of standardized methods of evaluating friability.The work described in this report was undertaken to assist in the development of standard methods for evaluating the friability of coal. Specifically, the work deals with a Comparison of the various methods previously proposed for estimating the friability of coal and coal products. This same objective is now being sought at a number of other institutions, both in the United States and Canada, by a committee of the American Society for Testing Materials. It is believed that by providing additional information concerning a property of coal pertinent to its increased usefulness, the work described will supplement and increase the useful of the data which long have been, and still are being, furnished by the bureau of Mines on the composition of coals of the United States."

Jun 1, 1933

By Renato Macciotta

The argillaceous formation known as the Opalinus Clay is host to the Mont Terri Underground Research Laboratory. The URL was developed to investigate the hydrogeological, geochemical and geotechnical properties of the formation. Underground excavations at the site are characterized by non-elastic and time-dependent deformations. Excavations trending perpendicular to the strike of the bedding presented relatively minor deformations, however, tunnels parallel to the strike of the bedding showed much larger non-elastic deformations. This paper presents an analysis of the measured response of a tunnel trending parallel to the strike of the bedding in Opalinus Clay. The measured convergence is compared to tunnel experience in weak rocks to assess the tunnel stability.

Jun 1, 2012

By Chen Xia, G. Deschenes, Wan-Tai Yen

"Ammonium thiosulphate is a potential replacement for the cyanide in gold leaching. However, the high reagent consumption hinders its practical applications. In order to reduce the thiosulphate consumption, chemical additives were used. The gold leaching tests were conducted on a sulphide copper-bearing gold ore with 0.3M thiosulphate, 0.03M copper sulphate and 3M ammonium hydroxide solution at 44% solids and pH 10.2. Sulphate, sulphite, amino acid and chelating agents were initially used as additives. It was found that chelating agents (EDTA and NTA) could reduce the thiosulphate consumption from 30 kg/t to 17.8 kg/t with some increase of gold extraction. The improvement from other additives was not significant. Other approaches were also attempted to reduce thiosulphate consumption with some success. The thiosulphate consumption could be reduced to about 17 kg/t by reducing copper sulphate concentration fiom 0.03M to 0.0015M; adding 0.04M of EDTA; replacing copper sulphate with 0.001M of nickel sulphate. The increase of pulp density fkom 44% to 60% solids could reduce the thiosulphate consumption to 17 kg/t as well. Limiting the dissolved oxygen content by sparging nitrogen reduced the thiosulphate consumption further to 10 kg/t. It could be concluded that the regulations of copper and oxygen supply in the lixiviant were the keys to reduce the reagent consumption.INTRODUCTIONCyanidation, as the predominant gold leaching method, has been used in mining industry for more than a century. The low reagent requirement and the high performance are the reasons for its great success. However, cyanidation cannot deal with ores containing large amount of copper, nickel, arsenic and zinc minerals. This type of ore may consume more reagents and result in a poor gold extraction. On the other hand, the carbonaceous materials may preg-rob the gold from pregnant solution and make cyanidation a problem leaching method. Further more, the high toxicity of cyanide represents another challenge to modern gold mines. In the beginning of the year 2000, an environmental disaster caused by an accidental spill in Yugoslavia was broadcasted world-widely (Gurevitch 2000). Gold mine operators are facing higher social pressures and increasing costs on environmental protections. The usage of cyanide in mining industry has been banned in some countries and locations such as Czech Republic, Japan, Turkey, California, Colorado, Wisconsin and Montana States. Thus, a non-cyanide lixiviant is required."

Jan 1, 2002

Presiding-Thomas R. Young, President, Wyoming Fuel Company, Lakewood, Colorado. Mark Gillaspie, Vice President, San Marco Pipeline Company, Houston Natural Gas Company, Houston, Texas, presented a very interesting film-"Invocation in Coal Transportation-Black Mesa Coal Slurry Pipeline." (See index for printed text of Mark Gillaspie's remarks) * * * Kaye Kuhlmann, President of Citizens for Total Energy, San Jose, California, presented a paper-"Grass Roots Support for Energy Policy." (See index for printed text of Mrs. Kuhlmann's paper.) Mrs. Kuhlmann is President of Citizens for Total Energy, an International volunteer grassroots organization with the purpose of educating the public on energy alternatives. CITE strongly advocates responsible citizen participation in the establishment of energy policy.

Jan 1, 1980

By F. Harold Weber

On July 13, 1967 the San Bernardino County Planning Commission approved publicly a request by American Smelting and Refining Company for a zone variance to conduct a silver mining and milling operation in the Calico district, southern California, Coincidentally, on July 14 the U.S. Treasury halted its sales of silver, and the U.S. free market price quoted rose immediately from $1.30 to $1.77 per ounce. In its request to the commission Asarco stated that about 13,500 to 15,000 tons of rock would be moved daily by surface mining, including 7,000 tons of ore. The ore would be crushed to minus three-quarters inches and the silver recovered "by a chemical process." The grade of the ore was not given, but the company said that it might also recover barite as a byproduct, The operation would employ 150-160 people. Additional activity in the district includes exploration programs by Superior Oil Company and Calico Silver Mines, Ltd. History and production: In retrospect, as the price of silver began to rise in 1961 from 91 cents an ounce, and as Asarco began its exploration program in late 1964, a new era for an old bonanza silver district would seem to have begun. The Calico district has been mined for silver only on a very, very small scale since 1882 to 1896, when an estimated $12 to $20 million (perhaps 15 to 20 million troy ounces) of that metal was produced from the 50-odd mines of the district and vicinity. These mines include the Silver King, Oriental, Waterloo, Garfield, Odessa and Waterman (which is about 8 miles west of the district). Much smaller-valued amounts of barite, gold, lead, and copper also have been produced from the ore deposits of the district; and from 1884 to 1907 the region yielded about $9 million worth of borate minerals.

Jan 1, 1967

By Stewart A. Silling, Dale S. Preece

The two key results of rock blasting are fragmentation and movement of geomaterials. Movement/flow of the blasted rock is often referred to as heave. Modeling the movement of full scale blasting is now possible with 3D distinct element models and parallel processing.

Jan 1, 2016

The Australian mining industry is at an interesting stage in its development. Of the large number of mining companies in Australia, some are still solely domestic in their focus, others have made their first tentative forays offshore, and others are global players of significance in tile world industry.   It is not long ago that the entire industry was almost exclusively domestic in its focus. Very few companies before the early 1980s had ventured offshore, and those that did so were considered quite risque. The initial moves were made mainly by large companies who could afford to lose the funds expended in getting started in a range of offshore locations.   Almost all offshore jurisdictions were considered to be high risk compared to the safety of home - I recall the extreme difficulty I encountered in the mid 1980s in endeavouring to persuade a Board to joint venture into an attractive gold opportunity in South East Asia.   One of the problems inhibiting the offshore development of the Australian mining industry was that some mining companies had had unfortunate experiences offshore. Others had heard of those who had had unfortunate experiences offshore and, as such, 'offshore' gained a bad name and the more risk averse boards and. management of the time simply put the whole idea into the 'too hard' basket.

Jan 1, 1995

By W. C. Burnett

The land phosphate deposits of the U.S. southeastern coastal plain have long been a major factor in the world trade of phosphate rock (Fig. 1). As recently as 1979, deposits of North Carolina and Florida alone accounted for about 33 percent of the entire world's phosphate exports. This situation is changing, however. World production increased by ~9 %, yet the U.S. share was down to ~28% in 1984. A complex interaction of economic and political factors combined with increasing costs of raw materials, production, and transportation have led to this systematic erosion of the U.S. market share. Changing land-use patterns within the southeast, environmental pressures, exhaustion of shallow high-grade resources in Central Florida, and the increased pressure from expanding low-cost production in other countries throughout the world account for much of the present difficulty in the U.S. phosphate industry. Considering this depressed environment -- what are the prospects for development of offshore resources? A summary of new research on offshore phosphorite within the U.S. Exclusive Economic. Zone (EEZ), as well as an attempt to place possible development of these resources within the current economic setting, is the purpose of this presentation. We will emphasize work in progress on a major offshore deposit along the U.S. Atlantic Margin as well as new research on Pacific Ocean occurrences of phosphorite on seamounts and insular slopes within U.S. waters.

Jan 1, 1986

By S. G. Beattie, N. Mojtabai

A study was carried out which aimed to: determine the effects of blasting on excavation perimeters and nearby slopes; establish a low-cost blast monitoring and field observation programme to determine peak particle velocities and blast damage; and to develop criteria for observable blast damage that are based on the peak particle velocity. Full-scale production blasts in a large open pit copper mine were monitored and studied to develop damage criteria for various rock types. Better blast designs can be achieved by correlating the results of blast monitoring with field observations of damage at the pit walls and on benches. Back-break and damage are related to blast-induced ground vibration. Peak particle velocity is accepted as a reliable measure for the prediction of ground vibration levels. Empirical models for the estimation of rock damage can be developed and used for blast design. The models are used to determine the zones of damage within the rock face. Rock damage models can also be used to design trim shots to achieve further reduction of back-break in more critical areas

Apr 1, 1996

By C. Rutter, S. Nelson

"Climax Molybdenum Company’s Henderson Mine, owned by Freeport McMoRan Inc., is a panel caving molybdenum mine located 69 km west of Denver, Colorado. The mine utilizes long interconnected ore passes as part of the ore flow system. Knowing the approximate level of ore in these ore passes is beneficial for preventing increased dust concentrations in various production areas, as well as scheduling truck loading operations. Level monitoring has been achieved by using a strain gauge placed on the steel structure of the truck chute, an amplifier and a Programmable Logic Controller. This paper explains the concepts and limitations associated with using strain gauges for ore pass monitoring as well as applying proactive dust prevention and level monitoring interfaces. INTRODUCTION The Henderson Mine, located 69 km west of Denver, Colorado, is an underground molybdenum mine which uses a panel caving process to produce 18,000 tonnes per day currently. This process involves dumping ore down a series of interconnected ore passes leading to truck chutes. Trucks use these chutes to load ore and deliver this ore to an underground crusher. If ore is pulled below the lowest intercept of these ore passes, a ventilation pressure imbalance occurs which generates a large amount of dust on the levels where ore is being loaded into the tops of the ore pass. When a dust event occurs, work must be stopped until the dust settles. Once the dust settles the ore passes must be filled significantly before trucks can start pulling from the corresponding chute. This downtime and unplanned work due to dust can be avoided if the approximate ore pass levels are known. Strain gauges have been installed and tested on a truck chute at the Henderson Mine and the results of these tests have led to a series of concepts in using strain gauges to monitor ore pass levels. This paper explores these concepts and corresponding limitations and explains how the application of ore pass monitoring can be achieved with the use of strain gauges. Ore Pass and Ventilation Pressure Imbalance Overview At the Henderson Mine, there are typically two or four ore passes in different drifts that combine into one bin to create an ore pass complex as shown in Figure 1. When the level of ore is at or below the 7210 intercept (I82W), four drifts have a ventilation connection to each other and the 7655 exhaust level. A “piston effect” is created each time a bucket of muck is dumped down the ore pass. Figure 2 illustrates this phenomenon: as the loader in 621 dumps a bucket down the ore pass, the muck pushes the air in the ore pass down the 82A leg and back up the 82B leg which generates a large amount of dust. The bin regulators on 7655 cannot be opened enough to allow for this surge of air to be relieved onto the exhaust level and the dust ends up exhausting into the 625 and 627 drifts."

Jan 1, 2018

By William M. Boorstein, Robert D. Pehlke

The rates of solution (of hydrogen in liquid pure iron and in several liquid binary iron alloys were meas-ured using a constant volume technique. The rates of absorption and desorption were found to be equal un-der all experimental conditions. increasing concen-trations of S, Si, or Te decrease the rate of hydrogen uptake but additions of Al, B, Cr, Cu, or Ni have no measurable effect up to concentrations normally en-countered in steelmaking practice. No relation ship was found between the effect of an alloying element on the equilibrium solubility of hydrogen in liquid iron and its effect on the solution rate constant. Mathe-rnatical analysis of the data indicates that under the present experimental conditions the rate of reaction of hydrogen with liquid iron is controlled by transport of gas solute atoms in the metal phase. Comparison of the present resuts with data on nitrogen taken un der similar conditions establishes that the hydrody-nurnic conditions which exist near the surface of a metal bath are best approximated mathematically by a surface renewal model for the case of rapid in-ductive stirring and by a boundary layer model for more quiescent melts. HYDROGEN has long been recognized as being a detrimental constituent in steel. If dissolved in the molten metal in excess of its solid solubility, hydro-gen can be evolved during solidification and cause bleeding or porosity in ingots and castings. In the solid metal, lesser amounts play a definite role in causing other defects such as hairline cracks, blisters, and embrittlement. For significant refinements to be made in metallurgical procedures designed to control or eliminate hydrogen from liquid iron or steel dur-ing processing, available equilibrium solubility data must be supplemented with reliable fundamental in-formation pertaining to the kinetic factors involved in the transfer of hydrogen to or from the metal. The scarcity of such information in the literature prompted the present investigation. PREVIOUS RESEARCH Whereas much of the existing data on the solution kinetics of gases such as nitrogen were obtained during the course of thermodynamic investigations, the solu-tion rate of hydrogen has been found too rapid to be accurately determined by conventional solubility meas-urement techniques. Consequently, little work on hy-drogen solution kinetics has been reported in the lit-erature. Carney, Chipman, and crant1 attempted to study the rate of solution and evolution of hydrogen from liquid iron by employing a newly devised sampling method. Although no significant quantitative data could be obtained, it was observed that the rate of solution was approximately equal to the rate of evolution of hy-drogen from the melt. Karnaukov and Morozov2 stud-ied the rate of absorption and Knuppel and Oeters3 the rate of desorption of hydrogen from molten iron by measuring pressure changes with time in a constant volume system. Karnaukov and Morozov determined the hydrogen pressures over their inductively stirred melts with the aid of a McLeod gage and therefore, were forced to work at pressures not in excess of 40 mm of Hg. Their experimental data conformed to a mathematical correlation based on diffusion control: and the rate coefficients calculated on this basis were shown to be independent of the initial absorption pres-sure. These authors reported the solution rate of hy-drogen to be eight-to-ten times higher than they had found for nitrogen in a previous study. They also re-ported that under identical conditions, hydrogen dis-solves somewhat more slowly in iron-columbium alloys than in pure iron. Knuppel and Oeters found that the desorption of hydrogen from pure iron at 1600°C was controlled in all cases investigated by diffusion in the metal bath as long as bubble formation was sup-pressed. This was substantiated by Levin, Kurochkin, and umrikhin4 who studied the kinetics of hydrogen evolution from liquid (technical) iron while applying a vacuum. Salter5 measured the rate of hydrogen ab-sorbed by iron buttons, arc-melted by direct current, as a function of hydrogen partial pressure in a hy-drogen-argon atmosphere. A carrier gas technique was used for analysis of the hydrogen absorbed. The initial rate of absorption was found to increase di-rectly with the square root of the partial pressure of hydrogen. EXPERIMENTAL METHOD Because of the rapid uptake and evolution of hydro-gen by iron-base melts, a constant volume technique was devised in order to obtain meaningful kinetic data over the entire course of the solution process. Apparatus. A schematic view of the experimental apparatus is given in Fig. 1. The hydrogen-liquid iron reaction system consisted of a gas storage bulb con-nected to a meltcontaining reaction chamber through a normally-closed solenoid valve. The gas storage bulb, an inverted 250 ml round-bottomed Pyrex flask was joined to the inlet port of the solenoid valve by a glass-to-metal seal. A more detailed illustration of the reaction chamber is shown in Fig. 2. The design of the Vycor reaction bulb was essentially that de-scribed by Weinstein and Elliott6 with the exception of a shorter, larger diameter gas inlet for this kinetic study. In position, the reaction bulb was closely by an eight-turn coil of water-cooled copper tubing which, when energized by a 400-kc oscillator, provided the inductive heating source. The walls of the bulb were maintained relatively cool by circulating cold water along their outer surface, thus preventing

Jan 1, 1970

By S. F. Shaw

The Sierra Mojada mining district is situated in western Coahuila, about 8 km. east of the Chihuahua state line, and about one-half way from the northern to the southern extremity of the state. It is at the terminus of the Mexican Northern R. R., 125 km. northeast of Escal6n, Chihuahua; also about, 240 km. due west of Monclova, Coahuila. The altitude is approximately 1500 m. above sea level. The Sierra Mojada valley is about 10 km. long, from east to west, with a width of 1 to 2 km. It is approached from the east through the Puerto del Oro, where the Mexican Northern R. R. enters the valley; the slope from west to east is gentle. The Sierra Mojada, of which about 300 m. is an almost vertical wall, bounds the valley on the south side; on the north side, the slope to the crest of Sierra Planchada is more gradual, rising only 200 or 300 m. above the valley. Water is relatively scarce in the district, and there are no running streams. The rainy season, usually beginning at the middle of June, lasts through July, and occasionally into August or September. In some years the rains fail entirely. The slope of the ground is such that nearly all the water immediately runs off. The arroyos along the flanks of the mountains are not very deep, but in heavy rains, sometimes approaching cloudbursts, a tremendous volume of water rushes down them, carrying large boulders. A certain amount of seepage collects in the agglomerate, lying below the conglomerate, and is retained in the local fractures. Some shallow wells have been sunk in this agglomerate, and one well over 150 m. deep was sunk on the Volcan ranch, supplying about 76 1. (20 gal.) per min. A considerable supply of water is collected in large earth reservoirs in and below the town of Esmeralda. In ordinary years this supply will last until January or February, after which the Volcan well has to be depended on until the next rainy season. Vegetation is scarce, aside from scanty scrub oak and other brush in the mountains, and a few mezquite, locust, pepper, and cottonwood trees

Jan 1, 1923

By S. F. Shaw

The Sierra Mojada mining district is situated in western Coahuila, about 8 km. east of the Chihuahua state line, and about one-half way from the northern to the southern extremity of the state. It is at the terminus of the Mexican Northern R. R., 125 km. northeast of Escal6n, Chihuahua; also about, 240 km. due west of Monclova, Coahuila. The altitude is approximately 1500 m. above sea level. The Sierra Mojada valley is about 10 km. long, from east to west, with a width of 1 to 2 km. It is approached from the east through the Puerto del Oro, where the Mexican Northern R. R. enters the valley; the slope from west to east is gentle. The Sierra Mojada, of which about 300 m. is an almost vertical wall, bounds the valley on the south side; on the north side, the slope to the crest of Sierra Planchada is more gradual, rising only 200 or 300 m. above the valley. Water is relatively scarce in the district, and there are no running streams. The rainy season, usually beginning at the middle of June, lasts through July, and occasionally into August or September. In some years the rains fail entirely. The slope of the ground is such that nearly all the water immediately runs off. The arroyos along the flanks of the mountains are not very deep, but in heavy rains, sometimes approaching cloudbursts, a tremendous volume of water rushes down them, carrying large boulders. A certain amount of seepage collects in the agglomerate, lying below the conglomerate, and is retained in the local fractures. Some shallow wells have been sunk in this agglomerate, and one well over 150 m. deep was sunk on the Volcan ranch, supplying about 76 1. (20 gal.) per min. A considerable supply of water is collected in large earth reservoirs in and below the town of Esmeralda. In ordinary years this supply will last until January or February, after which the Volcan well has to be depended on until the next rainy season. Vegetation is scarce, aside from scanty scrub oak and other brush in the mountains, and a few mezquite, locust, pepper, and cottonwood trees

Jan 1, 1923

By W Potma, C Brauhart, S Halley, S Urbisinov, A Scogings

Truly integrated, quantitative, 3D GEOmetallurgical (or mineral system) characterisation, classification and 3D modelling should provide a cradle to grave unifying link across the exploration and mining value chain. All too often, spatially representative (quantitative) characterisation and modelling of a mineral system is delayed until feasibility stage, incurring a significant opportunity cost. The application of robust GEOmet characterisation methods early in the project lifecycle (at exploration stage) improves ground selection, exploration, and Mineral Resource estimation outcomes, long before there is a need for metallurgical test work. The value of this early provision of quantitative 3D mineralogy models is compounded at project feasibility stage, and continues to accrue over the entire project lifecycle, delivering cost savings, improved decision making and early warning of issues and opportunities.CITATION: Potma, W, Halley, S, Scogings, A, Urbisinov, S and Brauhart, C, 2018. Putting the ‘GEO’ back in front of GEOmetallurgy: importance of early implementation of quantitative mineral system characterisation, classification and modelling, in Proceedings Complex Orebodies Conference 2018, pp 55–57 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

A. A. CENTER*—This paper reminds me of the beginning of the work of the Electrolytic Zinc Company of Australasia. Early work for this Company, as some of you may know, was done at the Bully Hill Plant in California. After working there for some time Herbert Gepp, now Sir Herbert, came to the Anaconda Co. plants in Montana where I met him. He spent some months there, in fact almost a year if I remember rightly. That was when we were breaking in the new electrolytic zinc plant at Great Falls, Montana. From there he went back to Australia and started in on the plant there. I believe they had an original plant of about 20 tons per day of cathode zinc. We heard from them for some time, until they were able to go along on their own, and they have done very well ever since as you have heard. Their practice, (the flow sheet, the leaching practice), has been quite different as reported in the paper and apparently they are still following that practice to some extent. While the earliest work on selective flotation was done down in Australia, the big companies there, strange to say, were far behind the American companies in taking it up; and it is only in comparatively recent years they have gone to the alkaline circuit and dropped out thereby more of their iron and lead. The zinc plant now is up to a capacity of 100,000 tons a year and I believe that may be notched up to about 105,000. T. H. WELDON*—I would like to ask

Jan 1, 1950