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By J. A. Pagliero, R. T. Quiroz, S. H. Castro

Selected voltammograms in tetraborate buffer solutions in the presence of ethyl xanthate or isopropyl xanthate at pH 9.3, for chalcocite, covellite, chalcopyrite, and enargite mineral electrodes, are presented. The concept of critical Eh of dixanthogen condensation (Ehc) is introduced, and the line of Ehc is thermodynamically defined in plots of log [X i] vs Eh, for methyl, ethyl, propyl, and butyl xanthates. A reaction scheme of xanthate oxidation in four steps, involving the dixanthogen condensation step, is proposed. A first attempt to interpret mineral flotation from a more general point of view is made. The electrochemical mechanism of dixanthogen formation and condensation is considered as a particular case of a more general and relevant phenomenon, which is the decomposition of the collector giving hydrophobic colloidal forms, whose associative behavior in bulk solution and at the mineral/solution interface is governed by colloid chemistry.

Jan 1, 1989

By J. S. Carman

As with the slogans of Madison Avenue, catch words or phrases frequently become topical. Much is heard these days of the confrontation between governments of developing countries and international mining capital. In actual fact, sadly there are too few cases of anything as positive as confrontation because such an action at least signifies a dialogue which may begin badly but end up fruitfully. Instead we have in general a climate of indifference and fear with the mining companies of note marking off most of the developing world as being unsafe for investment. There is an unreal air to this damaging impasse. The common sense and objectivity which are prerequisites of positive action are lost in a swirling cloud of mythology, embraced largely by governments. Let us examine some of the dangerous misconceptions.

Jan 1, 1977

By Moenster J. A., M. J. Sankovitch

Doe Run's Buick Smelter was converted from a primary lead smelter to a secondary lead smelter in 1991. The recycling facility was designed to produce 60,000 tons of refined lead per year from 110,000 tons of spent starting-lighting-ignition (SLI) batteries and 10,000 tons of lead contained in drosses and scrap. Since commissioning, Buick's refined lead output has steadily increased to exceed 120,000 tons for 1999. The production gains have been the result of continuous process improvements, empowerment of the workforee, and development of additional scrap lead streams. The production gains were accomplished while setting industry standards for employee safety, reducing plant environmental emissions and employee blood leads, achieving ISO 9002 certification, and expanding product lines to meet customer requirements. This paper highlights Buick's major accomplishments through the 1990's.

Jan 1, 2000

By Stephen C. Tadolini

PC-Strand tendons, commonly referred to as cable bolts, have become a major rock reinforcement device for underground mining and civil applications. The most common configuration is a 1+6 strand, which designates a center king-wire, with six outer wires wound around it to form a 0.6-in (15-mm) diameter cable. The capacity of this tendon approaches 30 tons, but the performance is largely dependent on the anchorage medium and the ability of the system to transfer stresses back into the rock mass while reinforcing and suspending the immediate roof. Recent developments to improve the transfer mechanisms of the PCstrand via the anchorage medium by impregnating the individual wires with uniquely designed deformations have resulted in improved anchorage and subsequent cable bolt performance. This paper describes a series of laboratory tests used to develop the initial indentation patterns and numerical modeling simulations that were undertaken to refine and optimize the final designs. The new, indented PC-Strands, offered in both bright and properly galvanized, have been tested in the field and are being used effectively in two new cable bolt products. The results of the laboratory, computer modeling, field testing and in-situ installations provide a glance at the next generation of cable bolts. This suite of testing shows how they will improve the safety and serviceability of openings under adverse ground conditions.

Jan 1, 2012

By L. C. Graton

I. INTRODUCTION. The Relations of Scale in Geologic Work. MANY features of human accomplishment rest upon the possibility of representing natural objects on a scale of different magnitude from the actual one. Most drawings, for example, are of very different scale from that of the object depicted, and indeed are useful mainly on this account. More important than the question of mere convenience, however, is that of meeting the physical limitations of vision.1 Thus, a mural

Jan 5, 1913

Results are presented on the elution of gold cyanide and base-metal cyanide complexes from strongand weakbase resins. It is shown that thiocyanate anions, zinc cyanide anions, and thiourea in acid solution are effective eluants of strong-base resins, but that it is generally necessary for electrowinning to be incorporated in the elution cycle if fast rates of elution are to be achieved. Weakbase resins are eluted with sodium hydroxide solution, which is shown to be far simpler and far more effective than the elution of strong-base resins. The effects of parameters such as concentration of the eluant, temperature, and electrowinning efficiency on the rate of elution of the resins are examined.

Jan 1, 1984

By Q Liu, P D. Katsabanis

The energy output of crushed AN/FO, crushed AN/FO mixed with Aluminum (5%, 6.4% and 9.4% A1 by mass) and a commercial emulsion explosive has been measured using a detonation calorimeter. The charges had a diameter of 10 mm and were heavily confined by a 11 mm thick copper shell. In order to achieve stable detonation glass microballoons were used in the explosives so that the density of the AN/FO charges would be around 1.1 g/cc. The charges were detonated in vacuum and the detonation products were analyzed using gas chromatography. It was found that energy values were very close to calculated values obtained by ideal detonation codes.

Jan 1, 1993

By M. Timucin

High-temperature phase relations in the Pb-PbS system were established by the quenching of samples equilibrated in evacuated and sealed silica capsules. The liquid-miscibility gap seen in some previously published phase diagrams was not observed. The thermodynamic activities of PbS in liquid solutions of this system were derived at 1473 K from the isopiestic equilibration of samples belonging to this solution series with Cu2S-PbS melts of known PbS activities. The behaviour of Pb-PbS melts was found to be compatible with a subregular solution model. This model also made it possible to obtain an analytical liquidus for PbS that was in excelent agreement with the experimental determination.

Jan 1, 1988

By J Ralston, R Sedev, D Fornasiero

The foam behaviour of low molecular weight polypropylene glycols (PPG) was investigated as a function of concentration and molecular weight (190 - 2000 g mol-1). For each polypropylene glycol, foam stability increases with concentration and passes through a maximum, beyond which foamability is suppressed as the solubility limit of the glycol is exceeded and droplets of glycol form. Light scattering data as well as static and dynamic surface tension results provide the key information leading to these interpretations. A maximum in foamability was observed for the PPG molecules with increasing molecular weight (caused by a change in molecular conformation at the interface). This suppresses the Marangoni effect and leads to a decrease in foam stability.

Jan 1, 2005

By Robert Hopler

As a part of the depression and rectification work on the Port Morris branch of the Harlem Division of the New York Central & Hudson River Railroad, a short tunnel is being driven under St. Mary’s Park. The park is near 149th St. and St. Ann’s Ave., in the Borough of the Bronx, New York City.

Jan 1, 2006

By T. J. van der Walt

This paper proposes a new methodology to model ill- defined processing operations using neural nets (NN's). A process with many variables (large dimensionality) cannot be modelled adequately if limited process data are available. This problem of multi-dimensionality is addressed and an approach suggested to reduce the dimensionality using NN's. The result of this modelling methodology is a combined model of phenomenological expressions and NN's. The model can successfully be incorporated in a dynamic simulator of the process. A new approach to conduct modelling on the basis of continuous data collected directly from an industrial processing unit, is also proposed. The modelling methodology is applied to a typical processing operation, the resin-in-pulp (RIP) process.

Jan 1, 1992

By K. Hanumantha Rao, A. Nayak, . K. S. Narasimhan, S. N. Mahapatra

Selective flocculation studies carried out with iron ore tailings generated at Kudremukh iron ore plant indicate that a concentrate containing 63% iron can be obtained from the tailings containing 34% iron with around 60% recovery. This opens up the possibility of recovering most of the iron lost in the tailings generated at 2 kt/h (2200 stph) while processing 22 Mt (24 million st) ore per year. This would mean that the productivity could increase by around 50%. In these studies, it has been established that caustic degraded tapioca starch is a most effective agent for selective flocculation. While potato starch after caustic degradation can also be used, neither the parent starch nor the amylopectin compound is as effective.

Jan 1, 1986

By J. P. Nairn, C. M. McCulloch

More and more underground mining is being conducted using the long wall method. Likewise, many new surface mines use area or mountaintop removal methods. These methods can have a significant impact on surface and ground water resources. The overall study of the effects on surface and ground water from mining is referred to as the probable hydrologic consequences (PHC) determination of mining and reclamation. Collection and interpretation of information concerning ground water and surface water quality and quantity, as well as detailed geologic analysis, is required to adequately define the impacts of mining. This paper discusses the present day requirements and methodology of preparing a PHC for a large mining operation in the eastern coalfields.

Jan 1, 1997

By Riley S. J

The basic aim of mine planning is to design mine layouts and schedules that achieve optimisation of operations, minimum cost and maximum resource recovery. Successful accomplishment of this aim is facilitated by timely and comprehensive rehabilitation planning commencing at the pre-feasibility stage and continuing until the end of mining. Incorporation of a final landfomt design for waste rock dumps in a mine plan requires a prediction of surface stability, which may be achieved through erosion modelling. Erosion prediction models can be placed in two broad categories: soil loss prediction models eg USLE and CREAMS, and geomorphic models such as SIBERIA. A waste rock dump landform design based on selected slope form and grade and drainage systems should be developed as part of planning. A digital terrain model (DTM) of the landfonn should then be produced which can be modelled for long-term erosional stability using pre-determined parameter values. If acceptable standards of stability are not achieved, the landform should be redesigned and remodelled until the desired result is obtained. The planning process incorporating models requires knowledge of spoil or waste rock properties and model parameter values. This information is site specific and can be obtained from drill cores or costeans at the pre-mining stage and from spoil or waste rock during the mining stage. Realistic model parameter values are critical in post-mining landfonn design and can be obtained by several methods, including rainfall simulation, monitoring, geochemical analyses and grain size analysis.

Jan 1, 1994

?Energy-related systems: wind, solar, electric are typically materials intensive. As new technologies are widely deployed, significant quantities of the elements required to manufacture them will be needed. However, many of these unfamiliar elements are not presently mined, refined or traded in large quantities, and, as a result, their availability might be constrained by many complex factors. A shortage of these ?energy-critical elements? could significantly inhibit the adoption of otherwise game-changing energy technologies. This, in turn, would limit the competitiveness of the U.S. industries and the domestic scientific enterprises and, eventually, diminish the quality of life in the US.? -Energy Critical Elements: Securing Materials for Emerging Technologies?- American Physical Society, 2011.

Jan 1, 2012

A BRIEF account of the water-power potentialities of Tasmania is given, together with possible applications of the power commercially. A short history of the Waddamana development is then given, and the main works are described.WATER POWER POTENTIALITIESTasmania is an island of approximately 24,500 sq. miles area (exclusive of small islands). An area of 12,000 sq. miles is at an elevation of over 1000 ft. above sea-level, and of 2300 sq. miles at over 3000 ft. above sea-level. Average annual rainfall varies from' over 140 in. on West Coast to 20 in. on East Coast, and for the whole island averages 48.5 in. The total water-power available, based on conservative figures for run off and efficiency, is 6,000,000 b.h.p. Only a small percentage of this total will, under present conditions, and under likely conditions in the immediate future, be capable of being developed commercially.An extensive hydro-metric and water-power survey is at present being carried out in order to collect information concerning the most promising water-power schemes. Already 400,000 b.h.p. has been located in different proposals, and there is still a large area of very likely country along the West Coast which has not been investigated yet. Tasmania thus has very vast power potentialities, which, combined with good ports and communications and wonderful mineral and timber resources, should augur well for the establishment of the great key industries, particularly chemical and metallurgical.

Jan 1, 1923

By H. W. Gillett

UNLIKE most previous Howe lecturers, I had not the good fortune to be associated with Henry Marion Howe, nor to be directly one of his students. Yet, through his writings, he has been my teacher, as he has of all American metallurgists. Instructive as his writings are-I use the present tense because Howe thought so keenly and reasoned so surely, seeing clearly, as if by intuition, what was hazy to lesser minds, that his writings are still vital-it is not, those books and papers, nor even the minds he trained in his classes, that were his most outstanding service. It was the spirit of Howe in his: approach to the problems of metallurgy, his broad-mindedness and fair-ness, his recognition of the need for theories and hypotheses to explain metallurgical phenomena, his willingness to use them as servants, as well as his questioning attitude-his refusal to accept them as masters-that comprise his greatest service. This most thoroughly warrants the honor the Institute pays each year to his memory. These traits I so respect and honor in any man that I glory in this opportunity to do reverence to him in whom they were so notably united.

Jan 1, 1939

By James R. Boyle

The value of Alabama's nonfuel mineral production in 1980 was $328.6 million, a decrease of $7.8 million from 1979. Cement, crushed stone, lime, clays, and sand and gravel continued as the major commodities produced. Alabama led the Nation in the production of crushed marble; was second in bauxite; third in native asphalt, ferroalloys, kaolin, and oyster shell; fourth in dimension marble, masonry cement, and bentonite; and fifth in fire clay and lime. Alabama ranked in the top 20 States in total value of non-metallic minerals produced. Adverse economic conditions in the construction and metals industries impacted on the minerals industry in Alabama. Mineral producers supplying raw or finished materials to these industries experienced periodic reductions in sales during the year. Unit price increases did not keep up with inflation.

Jan 1, 1982

By Robert Hopler

RBH Note: in 1913 black powder was still dominant as a coal-mining explosive, but permissible explosives were making some slight headway. For example, in 1902 there were only 11,300 pounds of permissibles used in coal mining, but in 1913 the quantity was 21,801,285 pounds. However, there were 187,551,653 pounds of black powder used that year. It took many years before the use of black powder ended in coal mining. From the picture of the miner reparing his explosives it’s hard to tell what he’s using, but the fact that a wooden Du Pont powder box is shown, he’s probably not using black powder. That doesn’t mean he’s using a permissible, either, since that was not yet a requirement. It’s interesting that the miners have open flame cap lamps, and the miner is actually smoking a pipe while preparing his explosives.

Jan 1, 2014

By Christopher Tucker, Marcello Veiga

Social issues are increasingly recognized as significant inhibitors to mineral development projects. Increasingly social risk is being recognized as a key factor determining the success of a mineral investment. Groups opposed to a mine for social or political reasons often use environmental impacts, real or perceived, to prevent mine development. These risk factors depend largely on cultural perceptions of mining activities and must be understood as such in order to be appropriately managed. A first step to addressing social issues is inclusive, transparent and meaningful engagement of stakeholders. This process allows stakeholders to understand what the other parties value in order to collectively establish a common currency for development and the creation of mutual value. Expanding the scope of benefits and values a mine can bring is of increasing importance to mining companies who typically consult outside specialists remote from the mine site and late in the development timeline for this purpose. Training technical staff, engineers and geologists, who make initial and ongoing contact with local interests, in a holistic approach to mine development is crucial to successful and economic mineral development projects. Further extending this conversation to the general public, media governments and non-governmental organizations is a necessary step in developing a meaningful discourse on the benefit of mining activities.

Jan 1, 2014