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By E. S. Erickson, R. L. Stone

Introduction Evidence from blast furnace operations has indicated that using pellets with a higher ISO low temperature reducibility, a lower SiO2 content, and better resistance to low temperature degradation results in considerable coke savings and improved furnace operation. Although these benefits could not be directly related to reducibility differences alone, we believed there was sufficient evidence of the advantages in improved pellet reducibility to warrant laboratory investigation of ways and means to effect such improvements. It is well known that pellet reducibility can be significantly altered by changes in the basicity and the amount of non-iron oxide constituents. Past work (Friel and Erickson, 1980, 1982; Saeki et al., 1977; Thanning, 1974) has shown that with increased MgO contents, and at optimum CaO/S1O2 ratios, significant improvement in low temperature reducibility can be attained. The improved properties of such fluxed pellets have reportedly led to increased blast furnace efficiency and productivity (Saeki et al., 1977; Ilmoni, 1975). Less well known, however, is exactly what factors control reducibility in acid pellets. Because of this gap in knowledge, studies were undertaken of the factors affecting reducibility in acid pellets and to estimate their relative significances in modifying reduction behavior. This paper describes that part of our work done to determine the effect of bentonite on reduction behavior. Our approach was to first examine the effect of bentonite's presence on as pure an iron oxide as possible (i.e., a magnetite "superconcentrate" containing about 0.2% SiO2) so as to eliminate any gangue-binder interaction. The next step was to look at bentonite effects on concentrates with only limited amounts of gangue (containing about 1% SiO2), but of two different types, simple and complex silicates. Last, we

Jan 1, 1988

By J. F. Enrietto

It is shown that one cannot approximate the broad internal friction Peaks observed in the Fe-Mn-N system as the sum of a number of subsidiary Peaks and still vetain the concept of a single relaxation time. Furthermore, the approximation of manganese affectirg only nearest neighbor interstitial sites is shown to be incompatible with the experimental results. The results of this experiment show that the influence of manganese in the ferrite lattice extends over 3 to 4 atomic distances. NUMEROUS experiments have shown that the presence of relatively small amounts of substitutional alloying elements can profoundly affect the profile of the damping spectrum in the vicinity of the Snoek peak in bee metals.1-7 Dijkstra and Sladekl observed this phenomenon in Fe-Mn-N alloys where it appeared as a broadening and shifting of the Snoek peak to higher temperatures. The authors interpreted this as being the result of a superposition of two damping maxima—the normal Snoek peak, located at its usual position and having a normal half-width, and an interaction peak having a normal half-width, but occurring at a somewhat higher temperature. They prclposed that the interaction peak was caused by nitrogen atoms jumping from Fe-Mn sites to Fe-Fe sites, the Fe-Mn interstitial sites having one manganese and one iron atom as nearest neighbors, and the Fe-Fe sites having two iron atoms as nearest neighbors. They further suggested that the Fe-Mn sites had a lower energy than the normal Fe-Fe sites because of the presence of the adjacent manganese atoms. From the relative heights of the two postulated damping peaks, the dif-

Jan 1, 1962

By Richard G. Burdick

The Bureau of Mines', Denver Research Center has been conducting research for the past few years on the use of resistivity methods to locate abandoned mine workings. As this work has progressed, it is apparent that in some cases, in addition to detecting the old workings; stoping, precursive to surface subsidence has also been detected. This paper describes the Automated Resistivity method and discusses sites in Colorado. Wyoming. and Illinois where the subsidence phenomenon has been observed.

Jan 1, 1982

By M. J. Sapko

The Bureau of Mines conducted laboratory-scale flammability experiments to investigate the possible use of water spray systems for inerting or quenching mine-gas ignitions, such as those encountered at the working face of a coal mine. The inerting results for premixed methane-air-water mixtures indicated that water droplets of less than 10 µm tend to be as effective as the vapor. Water requirements for inerting such mixtures were much smaller than those for quenching the sustained flame propagation by the application of water sprays. The minimum water mass concentration for quenching methane-air flames increased linearly with increasing droplet diameter (surface weighted mean) and decreased with increasing spray temperature, whereas the droplet surface area required per unit volume was essentially constant for a given gas mixture composition. Data extrapolations indicated that a quenching system may be feasible for the longwall mining application.

Jan 1, 1977

By Ralph C. Flow

In Cleveland County, North Carolina, 1 ½ miles south of Kings Mountain, Foote Mineral Co. operates an open pit for the production of spodumene, feldspar, mica and commercial stone. Spodumene concentrate is sent to Foote Mineral's Sunbright, Va., plant and to other customers. Exton, Pa. and New Johnsonville, Tenn., plants produce lithium com- pounds sold to the oil industry for multipurpose lithium-base greases, to the metal industry as welding flux, to the air conditioning market and to the glass industry. Ceramic-grade spodumene, feldspar, and mica concentrates go to other processing companies from the Kings Mountain plant. Waste amphibolite is delivered to a neighboring quarry operation. Geology and exploration of the deposit have been described by T. L. Kesler, Chief Geologist of Foote Mineral Co., in the September 1961 MINING ENGINEERING. Measured ore reserves as published at that time were 20.7 million tons. The ore deposit consists of a series of lithium-bearing pegmatites enclosed in amphibolite and mica schist wall rocks. The general strike of the pegmatites is northerly, and in the southern part of the pit, they dip slightly towards the west. The largest body being mined has a fairly uniform thickness of about 200 ft. Other pegmatites in the pit area range from 20 to 100 ft in thickness. Minerals in the pegmatites are 20% spodumene, 32% quartz, 6% muscovite, 41 % feldspar and 1 % trace minerals.

Jan 10, 1962

By Arthur G. Strassburger

INTRODUCTION High in the Sierra Nevada Mountains of California, some 50 airline miles (80 km) northeast of Fresno, and near the John Muir Wilderness and Kings Canyon National Park, a large underground hydroelectric project is under construction. Pacific Gas & Electric (PG&E) Company's 1,125 MW Helms Pumped Storage Project exhibits a number of impressive statistics, unusual features, and other characteristics of interest to the tunneling or power plant designer and construction contractor. The most significant underground facilities include almost 20,000 ft (6,096 m) of 27-ft (8.2 m) diam concrete-lined pressure tunnel; 3,700 ft (1,128 m) of access tunnel; 1,600 ft (488 m) of steel-lined high-pressure conduit, 2 major underground chambers more than 1,000 ft (305 m) below ground; 3 deep vertical shafts, and one steep inclined shaft. Maximum static pressures within the conduits range from 200 ft (61 m) to 1,744 ft (532 m), with hydraulic transients that increase pressure to 2,500 ft (762 m). The purpose of these underground works is to provide 475,000 hp (354,350 KW) of water power to each of the 3 reversible pump-turbines, each connected to a 375 MW generator motor. The units, rated at 1,744 ft (532 m) maximum static head, are among the world's front-runners, considering the size-head combination. The Helms Project develops the existing power drop between two of PG&E's reservoirs, Courtright Lake and Lake Wishon. These reservoirs are retained by two concrete-faced rockfill dams completed in 1958, each storing approximately 125,000 acre ft (154 x 106 m3) of water. Although the project is intended to operate on a typical

Jan 1, 1981

By John A. Meech, J. G. Paterson

Activated carbon is a strong adsorbent for amyl xanthate, capable of removing from solution up to a quarter of its own weight in xanthate. In selective flotation system where depression is unstable, separation efficiency increases with activated carbon additions. The improvements observed are brought about by two mechanisms. First, by removing stripped and residual collector ions from solution, competition between depressant and xanthate is reduced and depression is stabilized. In addition, the texture of the froth phase at high pine oil concentrations is modified by activated carbon such that better drainage between the air bubbles takes place, alleviating the mechanical entrapment of depressed mineral particles. In treating a bulk copper/lead concentrate produced from GECO ore, selectively between galena and chalcopyrite is increased when activated carbon is used. Although the rate of flotation of galena is marginally lowered by activated carbon, a small extension in the duration of flotation allows the lead recovery to increase by 19% at the same recovery of copper. An addition rate of 0.75 kg/ton (1.5 lb/st) of bulk concentrate is suggested as optimum from this testwork. However, the actual level used in the mill is dependent upon the residual concentrations of collector and frother in the bulk concentrate pulp.

Jan 1, 1979

By Daryl R. Tweeton, Jerry R. Riding, Grant Buma, Frank J. Rosswog

In situ solution mining of uranium has environmental advantages over conventional mining. The leaching of uranium, however, alters the ground-water quality in the aquifer where the mining occurs. Currently, regulations require that the ground water be restored to approximately its original condition. This paper, a summary of a study funded by the Bureau of Mines, reviews the state of the art in restoring ground-water quality after in situ uranium leaching. Current restoration practices discussed include disposal of liquid wastes in deep disposal wells and evaporation ponds, producing from all wells during restoration, and recirculating water purified in surface plants. Methods for predicting the effectiveness and cost of current techniques are presented. Possible alternative techniques are also described. Two restoration operations are discussed.

Jan 1, 1979

By Frew J. A, Harris M. C, Manlapig E. V

The recovery achieved in a flotation process is a function of both the characteristics of the feed stream and the operating conditions within the flotation cell. In this paper, the flotation characteristics of the streams within the Red Dog le

Jan 1, 1997

By J. R. Hunter

Current trends in mining practices within the United Kingdom, with particular reference to longwall retreating systems in thick and steeply pitched coal seams at depth, are explained. Various successful mining layouts are considered with their associated machinery and operation, together with the future trends in mining practices to obtain higher outputs. Environmental difficulties are tabled and discussed, including strata control, methane emmision, and dust prevention, together with some modified systems and techniques to overcome them. The problems associated with developing and maintaining a continuance of longwall panels are outlined. The constraints on technical designs and output achievement imposed by noncommercial factors are also considered.

Jan 1, 1978

The granulites and related "dry" igneous rocks tend to be passed over during exploration for metals. Preliminary data show that high trace concentrations of Cu, Ni and other metals of economic interest are common in orthopyroxene and some of the other granulite minerals. During retrograde metamorphism of granulites, pyroxenes are converted to amphiboles or phyllosilicates, and significant quantities of metals are released and become available for incorporat- ion into new mineral phases, or may be transported elsewhere. S--rich scapolite is the normal scapolite of granulites. Its retrogression to secondary plagioclase provides much S which scavenges Cu, Ni, etc., from pyroxenes undergoing retrogression, thus producing ore-fluids. A full analysis of a scapolite with 5.10 per cent S03 is given. Beryl is unstable in granulites but the rare Be mineral taaffeite (Al4Pf (Be,Fe)O3) with 5,50 per cent BeO occurs in central Australia as a pale green Tabular mineral easily confused for chloritoid in hand-specimen. Metamorphic differentiation and mobilization of primary ore concentrations are major factors controlling their post-granulite attitude and grade.

Jan 1, 1969

By L. B. Pankratz

Low-temperature heat capacities, high-temperature enthalpy increments, and the enthalpy of formation at 298° K were determined calorimetrically for vanadium subnitride (VN0.465). The low-temperature investigation gave S°298.15 = 6.379 ±0.005 cal/deg mole, and a combustion calorimeter investiga¬tion provided ?Hf°298.15 = -31.80 ±0.60 kcal/mole. The two quantities were combined with the high-temperature data to give standard values of enthalpies of formation and free energies of formation above 298° K. These and related thermodynamic functions were tabulated to 1,800° K. Similar data are included in the range of 298° to 1,600° K for the mononitride, VN.

Jan 1, 1971

By Daniel García

La lixiviación acida es el proceso hidrometalúrgico más utilizado para la recuperación de cobre desde minerales oxidados, aplicando una disolución de ácido sulfúrico y agua para disolver los valores de cobre presentes en el mineral. La rentabilidad de esta operación va a estar determinada por el consumo de ácido sulfúrico y el grado de extracción del cobre. La U.M. Tacaza del Consorcio Minero CIEMSA, es un yacimiento de cobres secundarios, cuyo manto mineralizado expuesto, presenta una zona de oxidación – carbonatación, donde se aprecia malaquita, crisocola, azurita y limonitas. Los valores de cobre están entre 1.50 % a 2.25 % Cu.

Sep 1, 2017

By F. L. Wilke

Underground mining is a very complicated and complex industrial activity. The uncertain and, in most cases, the incomplete knowledge of the geological and mineralogical nature of the deposits can cause unforeseen difficulties. For a safe and uninterrupted operation, in addition to good planning and scheduling, reliable and up-to-date monitoring and control of all processes and conditions become necessary. Today, this is even more important in view of increasingly difficult working conditions, poorer grades, and more complex and expensive machinery. In short, large capital investment and higher risk of financial losses are involved in modern-day mining operations. Monitoring and control of the underground mining process has become a very complex and difficult task in itself. Many different systems are available, and the correct choice .is of utmost importance from both the economic and safety points of view. This chapter will deal with aspects of underground production monitoring and control. There are, however, many other areas of equal importance which are covered in an excellent manner in a hand- book by Olaf (1976) on monitoring and control of underground operations.

Jan 1, 1979

By R. S. Shoemaker

It is said that there is nothing new under the sun and this is certainly true about refractory gold Ores. Ores which have been refractory to treatment have been the bane of the Metallurgist's life ever since gold has been recognized as a metal valued for its indestructability, malleability and beauty. Webster's Dictionary defines "Refractory" as; "Resisting control or authority, stubborn, resistant to treatment or cure, unresponsive to stimuli, difficult to corrode or draw out," And gives as a synonym the word "unruly." I don't think any metallurgist would disagree with these definitions as they quite accurately describe refractory gold ores as we know them and I wouldn't be a bit surprised if many of you in this room today had applied far stonger language to your own refractory ores in the course of your metallurgical test programs. Pliny the elder put it very well when he wrote in 79 A.D., Gold is the first of man's follies, Silver the second." Perhaps Pliny was speaking of "unassayable gold" or "incipient gold." These are truly refrac tory ores which probably existed before Pliny's time and although many people have claimed to have solved their metallurgy the untold wealth that lies within them has never been bankable. On the other hand, Virgil is his Aenead, could very well have been speaking of refractory ores when he wrote; "Quid non mortalia pectora cogis, auri sacra fames!" which translates as, Accursed thirst for gold! What doest thou not compel mortals to do. Certainly, gold was extremely rare at that time because it had to be recovered by much labor from the then refractory ores and their refractoriness caused the early metallurgists (or alchemists if you will) to seek an easier way to produce it; thus the long and fruitless search for the "philosopher 's stone" which would aid in turn-

Jan 1, 1990

By Erickson M. E, Smith C. K, Carswell J. T

Thirteen holes totalling 3200m were surveyed using a downhole time domain Geonics EM37 system at the 830 metre level within the CSA Mine, Cobar, New South Wales, in order to search for blind, electrically conductive sulphides at some distance from exploration drillholes. A significant off-hole conductor was detected in only one drillhole.Geophysical modelling and interpretation of the survey results indicated that this off-hole conductor was caused by a sulphide lens 30 metres from the drillhole at a hole depth of 220 metres.

Jan 1, 1990

By Arthur L. Bishop

INTRODUCTION Purpose The in-situ leach method for uranium extraction is a relatively new and innovative method of uranium mining. In 1975, the first commercial in-situ facility began operation in south Texas. Since that time numerous other operations have been initiated as either pilot or commercial ventures. Considerable literature has been published that deals primarily with generalities of the process or environmental concerns. Several federal agencies have published documents which do not reflect the true operating or environmental nature of the in-situ leach method of uranium extraction. From an environmental standpoint, this is also evident in the promulgation of rules and regulations. Hence, the purpose of this paper is to present experience with an environmental concern--non- production zone excursions--such that the industry and the regulatory agencies will gain greater insight devoid of preconceived ideas and misconceptions. General Process Description In south Texas, in-situ leach mining is utilized to extract uranium from permeable sandstone ore deposits 61 to 213 meters (200 to 700 feet) below the surface. Uranium is present as an insoluble uranium oxide. In the in-situ or solution mining technique, anoxidizing lixiviant is injected into the formation through injection wells. The solution reacts with the insol uble carbonate complex. This soluble uranium complex is produced at recovery wells, each containing a submersible pump. During production there is a constant sweeping of lixiviant through the formation from the injection wells to the recovery wells. Injection and recovery wells can be arranged in any of a number of geometric patterns dependent upon ore body configuration, aquifer permeability, and operator preference. Submersible pumps in the recovery wells pump the uranium rich pregnant solution to the initial processing facility. Monitor wells surrcsund the pattern area and are screened in appropriate stratigraphic horizons (production and non-production zones) to detect any lixiviant migration that may occur (Fig. 1).

Jan 1, 1980

By David R. Lentz

At True Hill in southwestern New Brunswick, low-grade porphyry-style Bi-8n-Mo greisen mineralization is associated with the cupola of an epizonal granite porphyry (granite) that also exhibits three episodes of brecciation. The first episode of brecciation is an in situ, 8 m to 10 m wide transitional zone of net-veined to coarse-grained "blocky" endogranitic mesobreccia that is chloritized and greisenized and hosts weak disseminated minerali.zation. In a zone closer to the host rockgranite contact, angular fine- to coarse-grained endogranitic mesobreccia with greisenized matrix is superimposed on the earlier transitional breccia. The latest episode is fault-controlled and consists of quartz- and chalcedony-hosted sub-angular to rounded fine-grained "pebble" mesobreccias that crosscut and brecciate the other breccia types, as well as the adjacent altered metasedimentary country rocks. The first two episodes of brecciation are magmatic-hydrothermal in origin related to hydrofracturing of the granite carapace and are accompanied by greisenization and mineralization, whereas the post-mineralization, silica-hosted, "pebble" mesobreccias related to hydromagmatic, low-temperature fluid circulation and/or boiling along faults near the contact. These magrnatichydrothermal and hydromagrnatic mesobreccias are similar to those associated with W-Mo-Bi porphyry-greisen mineralization at the Mount Pleasant deposit.

Jan 1, 1994

By R. J. Marcotte, C. T. Eddy, R. J. Smith

THE objectives of the investigation herein reported were to determine: (I) the S-curves for certain selected cast steels, (2) whether or not the published S-curves for wrought steels are satisfactory for use on cast steels of similar composition, and (3) to prepare hardenability curves of the selected cast steels. In order to make the final comparisons between cast and wrought steel more completely tangible, it was deemed advisable not only to determine S-curves for the steels submitted in the cast condition but also to roll some of the cast-steel test bars and determine comparison S-curves on such wrought material. This procedure eliminates the composition variable and makes it possible to reveal the differences resulting from plastic deformation of the cast structure in addition to providing the comparison with published data on wrought steels. CAST STEELS The cast steels selected for the preparation of S-curves, or time-temperature transformation curves, were similar to S.A.E. series 1030, 2330, 4130 and 4330. Of these the 1030 was supplied by The Crucible Steel Casting Co., Cleveland, Ohio, and the other three by The Sawbrook Steel Castings Co., Lockland, Ohio. The steels were furnished in the as-cast condition. The manufacturers supplied the chemical analyses and the properties that could be obtained in the heat-treated condition-all of which is summarized in Table I. [ ] PROCEDURE The metallographic and dilatometric procedures and equipment were in general standard. The specific technique employed was described in a report of the Steel

Jan 1, 1945

By Reno H. Sales

EVERY mine manager, mine geologist, and every prospector in the field who appraises the future of mining properties does so on the basis of a theory of ore deposition whether he recognizes this fact or not. Wherever the ultimate value of a mine or prospect is dependent upon undeveloped ore, any estimate by an engineer or geologist necessarily involves a theory of origin of the deposit. In view of these facts the importance of a thorough understanding of the genesis of ore deposits cannot be overestimated. It well may be that the greatness of our country will depend upon finding reserves of natural resources as yet undiscovered. The genesis of ore deposits offers a fascinating field for study and investigation. This is attested by the large number of geologists who have written at length on the subject. For progress made toward a better understanding of ore genesis we owe much to Kemp, Lindgren, Ransome, Vogt, Emmons, Spurr, Graton, and a host of others. Within my own experience, I have attempted to apply in practice the various concepts and theories that have been advanced by these men.

Jan 5, 1954