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By C. R. Ince

The term "differential flotation" is used to denote a flotation operation in which separation is effected between two or more minerals of the same class; e. g., lead sulfide from zinc sulfide, pyrite from blende, chalco-pyrite from pyrite, chalcopyrite from blende. At present, so far as published work shows, there seem to be two theories as to the mechanics of differential flotation. The earlier and more generally accepted theory is that the so-called depressing agents alter the surface of one or more of the sulfides in the ore, either by chemical action or adsorption, so that it is no longer amenable to flotation, but that these depressed sulfides can be revived, after the unaffected sulfide has been floated, by reagents which react chemically with the altered surface and make it amenable to flotation. More recently, Professor Taggartl has advanced the theory that slime adsorption is an important factor in differential flotation. He believes that, with the proper use of a class of agents, which he calls dispersion agents and which include practically all the depressing agents, one can cause the slime to adsorb differentially on sulfide surfaces. A gangue-slime coated sulfide surface will act as a gangue particle and will not float. If, subsequently, an agent that will remove the gangue-slime coating is added, the sulfide again assumes its original surface and can be floated as an ordinary sulfide. This is the basis of the slime theory of differential flotation. Timber Butte mill at Butte, Mont., is a typical lead-zinc flotation concentrator. Neihart ore, chosen for investigation in this work, is one of the custom ores treated at that mill. Practice at Timber Butte mill in February, 1928, was as follows: A combined lead-zinc concentrate was first made using 0.2 Ib. per ton on the ore of potassium xanthate and 0.03 lb. per ton of Cleveland Cliffs oil after 1.5 lb. per ton of lime and 1 lb. per ton of calcium chloride has been added just before the ball mill. The concentrate was then thickened to 70 per cent. solids. Potassium cyanide to the amount of 0.3 lb. per ton and zinc sulfate in the quantity of 0.5 Ib. per ton were added to the thickened pulp and the whole

Jan 1, 1930

Micro-fine disseminated molybdenite was ground in a laboratory stirred mill using steel media and zirconium media respectively. The floatability of ground molybdenite and slurry chemistry was investigated. It was found that the total recovery of ground molybdenite using zirconium media was higher while the pH and Eh of the slurry are lower than that using steel media. When steel media was used, iron oxy-hydroxides had been generated coated on the surface of molybdenite, and decreased the floatability of molybdenite, especially of the -10µm particles. The iron and lead oxy-hydroxides was generated by the reaction between steel media with pyrite and galena associated with molybdenite. It was also found that changing the grinding media to inert can benefit the flotation of molybdenite. Keywords: stirred mill, grinding environment, floatability, micro-fine disseminated molybdenite, fine grinding

Sep 1, 2012

By Robert O. Davis, Phillip A. Abbott

The response of geologic materials subject to nuclear weapon effects is of considerable interest in the design of buried protective construction. Recently, more consideration has been given to placing such structures in rock rather than in soil. Although rock has the obvious advantages of high strength and low deformability, discontinuities such as joints and fault planes severely complicate any response analysis. Nevertheless, some knowledge of the effects of these discontinuities must be developed, even if that knowledge remains largely qualitative in nature. In this paper, we present a constitutive description of cracked rock subject to uniaxial shock loading. The constitutive equations are based on certain average response characteristics of a particular cracked rock model. Rather than attempt to represent each material discontinuity individually, we have incorporated the discontinuity effects into constitutive relationships for a continuous medium. The resulting equations are suitable for use in hydrodynamic computer codes presently used for ground motion calculations. APPROACH The continuum description which will be presented below is based on a detailed analysis of a particular cracked rock model. This model can be visualized as a sequence of plates (representing the intact rock) separated by gaps (representing the discontinuities). This so-called "plate-gap" model was first used by Thouvenin (1) in an effort to explain the behavior of porous materials at high

Jan 1, 1971

By C. C. Li

The D bolt is a new type of energy-absorbing rock support element recently developed in Nor-way. The D bolt is not only able to accommodate large rock deformations, but can also provide a load-bearing capacity as high as that of rebar bolts. Furthermore, the anchoring quality of the D bolt is similar to rebar bolts because of its multi-point anchoring design.

May 1, 2009

By Luis Alberto Medina

La característica principal de la composición de un cuerpo mineralizado es la heterogeneidad, dado que sus elementos no son iguales. En ese sentido, la prueba de heterogeneidad en el mineral de Cerro Verde, es una guía para la geología, mina, metalurgia y laboratorio químico, que busca optimizar los protocolos de muestreo y minimizar errores en las muestras tales como: Error Fundamental; Error de Segregación, generado por una muestra o submuestra cuando es cuarteada; Error de Extracción, generado por una muestra pequeña o insignificante colectada o tomada, y Error de Preparación, producido por la pérdida excesiva de finos. De acuerdo al estudio, el presente trabajo señala que la heterogeneidad de cobre total, cobre soluble en ácido y cobre soluble en cianuro, desarrollada para el mineral de Cerro Verde, es baja, lo que permite un manejo operacional sencillo para el muestreo con protocolos más simples, mientras que el parámetro más heterogéneo es el cobre soluble en cianuro y el protocolo podría ser afectado en el error fundamental.

Sep 13, 2001

By P. Somasundaran

Electrochemical properties of silicate minerals govern their behavior in processes such as flocculation and enhanced oil recovery that can occur at elevated temperatures. Knowledge of these properties as a function of temperature can be helpful in developing an under- standing of the role of these interfacial properties at non-ambient temperatures. Zeta potential of Sodium Kaolinite and quartz has been determined as a function of pH and temperature in this work. Both systems exhibited markedly different behavior at higher temperatures and also exhibited significant hysteresis. Results are examined in terms of possible dissolution of the minerals and surface reactions at different temperatures.

Jan 1, 1986

J. B. Cohen (AVCO Mfg. Co.)-The model presented by the authors is only one of several possible mechanisms for low-temperature aging. It is true that the motion of dislocations to the copper atoms, followed by diffusion along the dislocation lines, is one such mechanism. However, the details of such a process which would :result in copper-rich platelets on (100) planes in the f.c.c. matrix are not clear. Furthermore, there is at least one other mechanism that may be used to e.xplain the authors' results, so that the data do not clearly favor the Turnbull model. The zones may form by "normal" diffusion. The diffusion constants would be higher at room temperature than extrapolated data would suggest due to vacancies trapped in the specimens in the quench. The diffusivity would then be multiplied by the ratio of the number of vacancies present at the solution temperature to that present at room temperature. These vacancies could remain in the alloy specimen for long times at room temerature, due to interaction with the copper atoms. ' The activation energy for diffusion is smaller than that for bulk diffusion at elevated temperatures for it is only that for the motion of vacancies existing after the quench; after these are used up, the aging process effectively ceases. It is somewhat questionable if the laws governing transformation kinetics can be directly applied to changes in elastic moduli, especially in the case of aging where the structure and the composition of the zones may be changing during aging, If such laws are assumed, it is possible to explain the exponential factor of % with this vacancy model. It is probable that the structure of the zones and the matrix match only on (100) planes. Certainly the precipitates that form in this system after various aging treatments show orientation relationships similar to those of the zones. Strains on the edges of the zone may set up fields which do not allow the zone to grow in an edgewise manner. The exponent in the growth of a thin plate in a direction perpendicular to its face would be %. It may also be that copper atoms are attracted to dislocations. If this is the rate-controllin factor in the growth process Ifthisthen an exponent of % or % may arise. The writer would like to know if the authors have tried plotting l/a; proportional to as might be expected for "dislocation drainage." R. H. Doremus (General Electric Research Laboratory)—An important new method for following the growth of Guinier-Preston zones is presented in this paper, and I wish to congratulate the authors on their experiments. Their interpretation of the results, however, is doubtful in certain respects. To determine the exponent m in Eq. [4] the authors plotted -log at against t to various powers (their Fig. 6). The initial value of frequency used for these plots was found by extrapolating the data to zero time. In Fig. A the data from their Fig. 2 are plotted against a linear, rather than logarithmic, time scale. To obtain graphs similar to their Fig. 6 for these data one must use an initial frequency of about 52720; such a plot for m = % is shown in Fig. B. The straight line in Fig. B fits the data in an intermediate range only. The curve drawn in Fig. A was mapped from this line; comparison of

Jan 1, 1960

By Richard L. Ash

Less than optimum production in mining always results when poorly blasted material is provided at loading points. More often than not the cause is due to blasting founds that fail to fully control and utilize explosive energy. In many cases the problem exists because too few blasters understand how blastholes actually break rock and recognize that blasting is a three-dimensional process in designing their blasts. To better understand how blasts can be more effectively designed the two major rock breakage processes are described. In addition, the respective contributions of the borehole and detonation pressures are defined as are the specific roles of the several important blasting design variables. The concept of stiffness as an engineering principle and its significance in blasting design is introduced for explaining the breakup of rock. Basic guidelines for affecting control over fragmentation and side effects like over-break are offered.

Jan 1, 1975

By Yves Bellemare

Entre 1983 et 1997, l'exploitation de la pierre de taille au Québec a été marquée par l'émergence et la consolidation de plusieurs nouvelles variétés de granit, provenant exclusivement ou presque de la Province de Grenville. Le Québec demeure toujours le principal expéditeur canadien de granit dimensionnel, avec des expéditions annuelles représentant près de quatre-vingt-dix pour cent des expéditions totales canadiennes de granit brut et transformé. La production annuelle de granit brut oscille, depuis 1994, autour de cent mille tonnes métriques. Cette production a plus que doublé de 63 000 à 140 000 tonnes métriques entre 1981 et 1990, mais elle a connu une chute importante en 1991 (67 000 tonnes métriques); cependant depuis 1994, elle est en forte progression (Ménard, 1998). En 1983, le granit dimensionnel était extrait de plus de vingt-cinq carrières, dont les trois quarts se localisaient dans la Province géologique de Grenville. Comparativement, en 1997, le Québec comptait trente-sept carrières actives, dont trente-cinq dans le Grenville (Gaudreau et al., 1998). Cette concentration des carrières dans la Province de Grenville s'explique par la demande accrue de nouveaux produits au fil des ans et par le potentiel élevé de découvertes de nouvelles variétés dans cette Province géologique. L'accessibilité au territoire, toujours plus grande, a facilité la mise en production de carrières favorisant la diversification des produits. Le ministère des Ressources naturelles du Québec (MRNQ) a consacré depuis 1980, beaucoup d'efforts dans la recherche de nouveaux gisements et de nouvelles variétés. En plus des programmes de subvention destinés aux prospecteurs ou aux compagnies, le ministère a réalisé des campagnes d'inventaire de pierre de taille, de pierre concassée et de pierre d'enrochement pour en connaître le potentiel géologique et à orienter les recherches futures (Nantel, 1983; Nantel et Martignole, 1991; Bellemare, 1995a, b, c, d, e, f, 1997, 1998a and b; Bellemare et Petryk, 1996a, b, c and d). Cette étude donne un aperçu des différentes variétés de pierres extraites dans la Province de Grenville entre 1983 et 1997, les situe dans leur contexte géologique et en localise les principales régions productrices. Elle est une suite à l'article publiée par Nantel (1984).

Jan 1, 2001

By Nai-piu Tong, Huaren Dou, Sui-shun Poon, Leslie H. Swann

This paper mainly presents geotechnical aspects of a vehicular underpass that was built across under one of the busiest highway in Hong Kong. The underpass, in a section comprising an upper arch and invert slab, is approximately 6.2 m high at crown and 15 m wide at the base level with 40 m in length. The construction inevitably requires the underpass to be built using tunneling techniques to keep the overheadroad traffic uninterrupted. The paper will describe the design of temporary support for the tunnel excavation that was provided by an arch formed with horizontal pipes, which were installed using the pipe ramming method. The pipes arch was then supported by steel ribs founded on rock or mass concrete. Permanent lining design consideration was also discussed. Results of numerical modeling of the soil-structure interaction using the 2-D computer code FLAC will be presented. The predictions have been compared to the monitored results during construction, which indicates the prediction is in reasonable agreement with the measurement in the light of ground movement. The construction challenges will also be discussed in the paper.

Jan 1, 2003

The Dynamics and Thermodynamics of Absorbing Lithium of Ion Sieve Preparing Pollymetallic Nodules

Sep 13, 2010

By P. R. Dugan

The ultimate objectives and interest in removal of sulfur from high sulfur coal include: (a) reduction of the atmospheric load that con- tributes to the problem of acid precipitation; (b) reduction of ash which contributes to decreased energy transfer in boilers and the problem of ash disposal; and (c) alleviating the social and economic dislocations related to uneven geographical distribution of sulfur in coal reserves. The cost of sulfur removal in relation to the value of refined coal will govern the development of an emerging coal-refining industry. The value of refined lower sulfur coal will be influenced by the national commitment to the environment as well as economic considerations.

Jan 1, 1986

By D. J. Scarratt

Fisheries make a significant regional contribution to the economy of Canada. In the Atlantic Region, over 70 thousand workers depend on the primary or secondary fishing industry. Fisheries are vulnerable to pre-emption of space by other marine industries and to contamination by chemical discharges. Markets may be affected even by the threat that products may be tainted. Fish may be killed by drags and dredges, and their physiology and behaviour affected by suspended sediments are stirred up by mechanical devices. Virtually no evidence exists of adverse impacts £ran ocean mining on fisheries, but projections from other marine activities such as fishing itself, dredging and other marine discharges give reason for caution. Department of Fisheries and Oceans policy calls for review of ocean mining proposals to ensure adequate protection of fish stocks, fishing activities and fish habitat, and compensation for losses attributable to any industrial project. Adverse impacts can be minimized by careful attention to details of location, technology and timing, and to close co-operation and information exchange between industry and the regulatory agencies.

Jan 1, 1985

By Fred Beasley

METALLURGISTS have, in the past ten years, overcome many difficulties of high zinc in lead blast-furnace slags. This problem was brought to the front at the close of the late war, by the price obtained for lead and the high cost of labor, fuel, and flux. The Port Pirie plant of the Broken Hill Associated Smelters, Australia, early in 1919 had increased the zinc oxide in its blast-furnace slags from 13.5 to 20 per cent., at the same time reducing the iron oxide in the slag from 33.5 to 25.6 per cent. These results were obtained by the following proceduret the addition of granulated slag to the roaster charge, 10 to 12 per cent., improved conditions of the crushing and mixing and roasting of the constituents of the sinter. By experiments and improve-ments the practice at this plant has developed a normal slag that carries 22 per cent. zinc oxide, and at times runs as high as 33 per cent. zinc oxide, with only slight furnace trouble. The granulated slag is used not, only as a diluent to the sulfur in the roaster charge, but also on account of its value as a slag-forming material and on account of the physical properties it imparts to the finished sinter. The ore is mixed with flux and given a double roast. All the first roasting is by sintering with the Dwight & Lloyd machines. The final roasting is performed partly by Dwight & Lloyd machines and partly by H. & H. pots. The charge to the blast furnaces consists chiefly of the final sinter, slag shells, siliceous and non-bearing sulfur, lead ores. High blast and ore columns are the practice. The greatest care is taken to obtain in the final sinter as low a sulfur content as possible.

Jan 2, 1925

By James C. Puckett

The mining industry finds itself in the middle, between the need to increase production of our energy resources and the necessity of minimizing the environmental impact. Using the recent past as a guide, the mine planning engineer's function will continue to increase as further coal quality constraints are made upon the production staff. The engineer will need to make use of all available tools in order to provide timely answers to the complex "what if" questions that arise. This need to consider many alternatives is bringing about a rapidly increasing acceptance and utilization of the computer. In the areas of data handling, mineralization modeling, and production simulation, the computer is an effective tool for the mine planning engineer. Described herein is a coal data storage and analysis system developed to provide timely answers to the "what if" questions for an operating strip coal mine in Montana. The characteristics of a computerized coal data base and coal quality planning system are outlined in this chapter. The system has been developed for use at a particular coal mine; however, it has applicability to coal mines in general. Fig. 1 is a flow chart showing the functional relationships of the system. There are three main file types: the drill-hole data base, the boundary file, and the zone file. The purposes for which each file is organized are illustrated on the flow chart.

Jan 1, 1979

By Kimura. E.

Continuous estimation of phosphorus content of molten copper is required to produce phosphorus deoxidized copper in a continuous casting operation. The phosphorus content of molten copper was related to its electric resistivity, which was measured by the four-probed technique with a specially-shaped cell. In a laboratory scale, the linear relationship between the above factors was confirmed in the temperature range of 1083OC through 1200°C. The phosphorus concentration range measured was from 40 to 500 ppm. The phosphorus content was monitored successfully by measuring the electric resistivity of the molten copper in the distributor of a continuous caster in an industrial scale.

Jan 1, 1992

By Bernard A. Grand, Gary A. Almeraris

This project involves the reconstruction of a 1,100 ft. long by 75 ft. wide segment of an existing 4 to 5 track subway under Northern Boulevard in the Borough of Queens in New York City. The project includes widening the existing subway to permit the construction of new inbound and outbound subway (T1 and T2) ramps adjacent to and under existing operating tracks. The plan of the project is shown in Fig. 1. Existing tall buildings along the job site and a contaminated groundwater plume under an adjacent rail yard required construction of slurry concrete walls along the east and west construction limits. Groundwater cutoff across the north and south construction limits of the subway was achieved by jet grout walls built across the subway invert slab between existing track and third rails. The work involved dewatering the construction site to a depth of about 50 ft. below street grade. This is a four year project and includes extensive work to maintain and protect subway and vehicular traffic of over half a million commuters a day through the work area. The project cost was $160,000,000.

Jan 1, 1999

Smoky Valley Mining Company, Round Mountain, Nevada, was the pioneer operation designed for large scale heap leaching of crushed gold ores. It is located in the Big Smoky Valley which stretches 160 km (100 miles) through central Nevada west of the Toiyabe Mountain Range. Gold was first-discovered at Round Mountain, 88 km (55 miles) north of Tonopah, in 1905; and mining in the area included placer operations, which ran from 1946 to about 1960. Smoky Valley Mining Company is a partnership of Felmont Oil Co., Case-Pomeroy & Co., and Copper Range Co., with the latter being wholly owned by Louisiana Land and Exploration Co. In 1969, an option on the Round Mountain property was acquired by Copper Range, and during 1974 a decision was reached to proceed with mine development and plant construction. Ore reserves were reported at 10,537,000 mt (1 1,617,000 st) of 2.09 g per mt (0. 061 oz per ton) gold using a cut- off grade of 0.69 g (0.02 oz). Silver content was approximately 2.4 g per mt (0.07 oz per ton) and the waste to ore ratio was about 1: 1. By the end of 1976 heap leaching was in operation. The ore is a rhyolite tuff, sometimes described as a gold porphyry with highly abrasive qualities but which does not break down into slimes upon contact .with cyanide solutions. Gold is unevenly distributed through the ore but as a whole it is in a very finely divided state. Climatic conditions are extreme in central Nevada. Summers are hot and dry while winters are windy and cold with subfreezing temperatures. Elevation of the property is about 1,920 m (6,300 ft). Precipitation averages 203 mm (8 in.) per year. Until February of 1980, leaching was continued until the temperature reached minus 2ºC (28º F), and about 10 months leaching was the average. Water for the operation is drawn from the Toiyabe Mountains through a 13. 7 km (8. 5 mile) pipeline, originally installed in 1915, or from wells in the valley bottom. The plant requires make-up water at the rate of about 1,500 liters per min (400 gpm). On a schedule of three shifts, seven days per week, the daily output at Round Mountain amounts ,to 12, 700 mt (14, 000 st) consisting of 6,350 mt (7,000 st) each of ore and waste. Ore is hauled with a fleet of 45 mt (50 st) trucks and dumped into the 1,0.70 by 1,650 mm (42 by 65 in. ) gyratory primary crusher located near the pit. The primary

Jan 1, 1981

Gold has been known and mined in Australia for over 150 years. It occurs and is mined in all States and the Northern Territory. In the past 30 years approximately 8300 t of gold has been mined and gold exports have contributed over $106 billion to the Australian economy. In the first three quarters of the Australian financial year 2006 - 07 (ending 30 June 2007) gold exports were valued at $7.3 billion, which was 13 per cent of the value of all minerals exported and five per cent of AustraliaÆs total goods and services exports over the period. Clearly gold has been and remains a very important component of the Australian economy.

Jan 1, 2007

By E. H. Rose

From the more distant members and some not so distant, the plaint is often heard that they cannot justify the expense and time required to attend the AIME Annual Meeting. Almost invariably, the reason given takes this form: "I just don't see that I would get enough out of it." Often the would-be clincher is added: "Besides, the meat of it all comes out in print anyway." Not long ago, a group of us who have seldom missed a meeting in recent years fell to discussing this phenomenon, and found ourselves in emphatic agreement that anyone holding such a belief indicates by his first remark that he does not know how to attend a convention, and by his second, proves it. He is, by and large, the man who has never been there, and of him, there are many.

Jan 1, 1949