Search Documents

By Philip A. Mattson

INTRODUCTION Engineers involved with rock mechanics know the importance of discontinuities within a rock mass and their effect on its behavior when subjected to loads from structures or construction excavation activities. Various geophysical tools have been developed to provide comparative information on subsurface conditions, such as electrical resistivity, assorted seismic test methods, acoustic tests, etc. While these investigative means have proved invaluable in numerous situations, especially those where site alternatives are being evaluated, they shed little light on the difficult problem of quantifying the rock strength. For that purpose, a laboratory test program of samples obtained in the field is usually undertaken, often in conjunction with a variety of in-situ tests. While standard samples provide sufficient information on the rock properties, questions on the macro-structure of joints, faults, fissures, and their infillings often go unanswered. Presently, attempts are being made to incorporate into rock sampling technology new techniques which are directed towards providing better information on the incidense and orientation of discontinuities. One such device incorporates a scribe knife within the core barrel which scores the sample lengthwise as it is cored. The orientation of the scribe is known, thereby relating the bedding, planes, fractures, etc. to a spatial framework. A second approach, called the Integral Sampling Method, is the subject of this paper. Stated briefly, this method utilizes a grout injection to bond fractured rock to a steel reinforcing bar at the center of the coring. The bar is intended to act as a

Jan 1, 1979

By V. N. Burnhart

After eight years of testing and development, the E. J. Longyear Co. has adapted the wire- line core barrel to small diameter drillholes. Field performance indicates that the apparatus for the BX hole will be an important supplement to the conventional techniques used in the diamond core drilling industry. Higher core recovery, faster drilling progress, and reduced diamond costs will provide substantial savings to the user of coring equipment. The wire-line principle is not new, having been successfully applied to the large-diameter holes of the petroleum industry. But scaling the practices of core recovery in oil well drilling down to the small BX hole presented a number of problems. The technique, difficult even for large holes, was complicated by the exacting limitations of the small diameter in which durable and foolproof mechanisms would be required to operate. Since the maximum benefits could be realized from this sys- tem in holes 1000 ft and deeper or in holes in badly fractured ground, the drill string would have to be able to withstand heavy stresses. Most vital to the success of the idea was the development of a positive latching mechanism to assure proper positioning of the inner tube of the core barrel when the tube is dropped into place. Lastly, little was to be gained from the wire-line method without diamond bits that would give optimum penetration rates and a long service life in the drillhole.

Jun 1, 1955

By Andrew Button

INTRODUCTION This review deals with the controls exerted by unconformities on the stratigraphic and areal distribution of gold (and uranium) in Precambrian conglomerates. The relations described are drawn mainly from Precambrian basins in southern Africa, particularly the Witwatersrand Basin. The mining industry of South Africa started in earnest with the discovery of diamonds in 1866. Gold was first discovered in 1870, and in March of 1886, two out-of-luck prospectors stumbled across what was to become the world's greatest goldfield, in the vicinity of Johannesburg. George Harrison and George Walker sold their claims for a pittance and were heard of no more. The Witwatersrand goldfield has been in continuous operation since that time, some 150 mines having operated at one time or another. Deep mining technology developed here has allowed operations to proceed to depths approaching 13,000 feet. The Witwatersrand has produced some 55% of all the gold ever mined, and currently produces 60% of the world's supply, some 650,000 kg Au per year. To 1971, the Witwatersrand had produced some $32 billion of gold and $2 billion of uranium (when average prices were less than $35/oz. for Au and $10/lb. for U308). At present prices, the annual Witwatersrand production of close to 700,000 kg would be worth about $10 billion. Uranium was discovered in the Witwatersrand in 1923. In the $15-30/lb. bracket, the basin contains a reasonably assured plus

Jan 1, 1983

By J. P. Manning

UNQUESTIONABLY, the outstanding feature of the piping for the sulphide plant is the large amount which had to be done in almost every size from instrument tubing to 84 in. OD pipe. In this article the piping will be considered under the main headings of Yard Piping and Building Piping. Tables I and II give data concerning the individual systems. In the case of yard piping the figures pertaining to lengths and weights are approximately correct; those for building piping are given only for the concentrator and smelter buildings where the amounts were the most extensive. Yard Piping The installation specifications for yard piping called for all sizes larger than 12 in. to have welded joints made with outside welding rings. This type of joint was selected over butt-welded joints because less time would be needed for lining up, damaged pipe ends would be less of a problem, and deflections up to 6° per joint could be made when necessary. These advantages were thought to outweigh the disadvantage of the greater amount of welding required. Yard piping in sizes of 3 to 12 in. was specified to have butt-welded joints made with inside welding rings which were intended to facilitate lining up and keep welding material out of the lines. Screwed connections were specified for sizes under 3 in. No protective coatings or wrappings were required on pipe to be buried because of the dry climate at Chuquicamata.

Jan 1, 1952

By N. A. D. Parlee, I. D. Shah

THIS communication reports the results of some work done on the effect of gold, palladium, and platinum on the liquid-gas-solid equilibrium in the Ag-O system,1,2 see Fig. 1. Recently several investigators3, 4, 5 have reported the effects of gold, palladium, platinum, and copper on the solubility of oxygen in liquid silver. This communication represents only a portion of the work done here on the solubility of oxygen in liquid silver and liquid Ag-Au, Ag-Pd, and Ag-Pt alloyss—the greater part having already been reprted. The apparatus, materials, and procedures used were similar to those of earlier work.' l The main precautions observed in obtaining these freezing points at constant temperature and PO2 = 1 atm were as follows: 1) The points were approached very slowly from higher temperatures. 2) In the very near vicinity of the L-G-S equilibrium point precautions were taken to see that the melt was in equilibrium with oxygen at one atm. Equilibrium was considered to have been attained when no more absorption of oxygen was observed in the last 15 min at a fixed temperature. 3) In the case of these alloys, the freezing point of the melt at 1 atm of oxygen and the equilibrium amount of oxygen absorbed by the liquid "infinitesimally" above this point were determined by lowering the temperature in very, very small steps, equilibrating at

Jan 1, 1969

By M. A. S. Martins, H. Medeiros, B. Y. B. Dos Santos

This paper contains the geometallurgical studies, performed for Mineração Rio do Norte bauxites, applied to a selected area belonging to Plateau Saracá III, referring to an exploitation period of one year and three months, approximately. It is worth mentioning that Mineração Rio do Norte has the biggest bauxite operation in Brazil producing 8,500,000 tons of concentrate per year. The studies included wide investigations directed to the final objective of establishing a precise mining and production planning, based on the different behavior of the distinct bauxite ores, when submitted to industrial processes. Geometallurgy can be defined as the study of the regionalization (space distribution) of the metallurgical variables of a mineral deposit. This study involves and integrates all process engineering, geology, geostatistics and mining planning, among others. The development and application of the geometallugical studies to Mineração Rio do Norte were motivated by several reasons and necessities, among them: 1. Improving the forecast of the amount of concentrate (metallurgical mass yield) produced; 2. Improving the equipment operational efficiency, providing a more homogeneous feed; 3. Conducting a more precise material balance that permits a better daily, monthly and yearly production control; 4. Improving the forecasts for the final products generated by each ore type; 5. Obtaining better knowledge of the behavior of several ore types, submitted to the different process unit operations; 6. Promoting adequate ore blending, producing an homogeneous feed during mining operation.

Jan 1, 1998

By Guy Chevalier

QCM?s pellet plant, located in Port-Cartier, Quebec, produces up to 8.6 million tons of iron ore pellets annually. Four different types are produced: three for blast furnace operations and one for direct reduction furnaces. The paper presents the scientific approach that led to the installation of new process equipment to improve the reducibility of direct reduction pellets (DR pellet). The findings, the equipment selection and some post start-up modifications are presented. This low silica DR pellet is used in Midrex and HyL shaft furnaces. A good DR pellet has to meet strict chemical, physical and metallurgical specifications. An important metallurgical property is its ability to release oxygen when exposed to reducing gases. Considering that the market for DR pellets is expanding and being aware that reducibility is critical for our clients, a program to improve the latter was undertaken. Test work showed that one factor which has a negative effect on reducibility is the proportion of particles larger than 75 microns. Knowing that the best way to reduce the amount of coarse particles was to close our open grinding circuits, we began evaluating the most suitable classification equipment applicable to our process operations. We settled on hydro-classifiers based on their very sharp cut and their low operating costs. In light of the hydro-classifiers performance it was also decided to replace the hydro-cyclones of an already closed circuit.

May 1, 2003

By E. E. Russell Tratman

The use of dynamite in cold weather is attended with some difficulty, owing to the freezing of the material and its consequeut liability to fail to explode when the fuse is fired. With proper methods and care the dynamite can be thawed with reasonable safety, but numerous accidents occur (more than get reported in the public press), due to carelessness in the operation and to the treacherous nature of the material, or a combination of both conditions. Dynamite will stand treatment at one time which at another time will result in explosion. An expert on explosives says that the most dangerous means of thawing cartridges are ingeniously devised by ignorant laborers; baking, boiling and toasting being favorite methods, while at a stone-quarry, in one instance, an apparatus was arranged for steaming the cartridges over a pot of boiling water. In this latter case the nitro-glycerine leaked through the canvas cover and settled on the bottom of the pot, with the result that an explosion occurred, the water acting as a tamping to the charge. The fact that small quantities of explosives containing nitroglycerine will burn quietly and without explosion if ignited by direct contact with a flame, has led to the dangerously mistaken reasoning that merely heating the explosive can produce no ill effect. If . a dynamite cartridge is ignited or placed in a fire it will probably burn harmlessly away, but if placed on a stove or in an oven and

Jan 1, 1893

By John A. L. Dr. Campbell, James W. Haskew, F. Hoy Lee, Elliott P. Dr. Doane

Emissions of particulates, unburned hydrocarbons, nitrogen oxides (NO[ ]) and carbon monoxide (CO) from diesel engines are of concern in mines, particularly underground mines. All these undesirable products except NOx are the result of incomplete combustion in the cylinders. Various approaches to achieving more complete combustion in diesel engines have included different fuel compositions, use of catalysts, fuel additives, engine modifications, and oxygen-enriched intake air. The present study shows that injecting minute quantities of primarily platinum group metal catalysts into the intake air of a Deutz/MWM D916-6 mine diesel engine substantially reduces emissions in the exhaust. The catalyst injection system, which was developed by National Fuelsaver Corporation (Robin. 1981), transfers catalyst compounds in solution to a stream of air bubbles by a process called Bubble Fractionation (Lemlich et al.. 1966, 1968. 1970). The amounts are so minute that concentrations in the engine exhaust should be well below OSHA/NIOSH Time Weighted Average (TWA) exposure limits at steady state, a fact that was confirmed by analysis of collected particulates in the exhaust. When the catalyst injection was used along with a pleated paper filter to remove exhaust particulates, the filter operating life was shortened greatly. Therefore, this system is not recommended for use on diesel engines equipped with a water scrubber and a filter. It does offer a practical and relatively economical way of reducing exhaust emissions from other diesel engines, such as those in outby mine service

Jan 1, 1995

By John Suman

DURING the past few years the taking of cores in drilling with rotary equipment has been perfected to a remarkable degree in the Gulf Coast fields of Texas and Louisiana. Taking of cores is becoming quite a common thing, especially in the newer fields, and drillers are becoming expert in this work. The writer has seen cores 5 to 8 ft. long taken with great ease in wells as deep as 4500 ft. Coring is doing much to remove the prejudice which so many petroleum engineers seem to have against .the use of rotary drilling equipment for exploratory work. Some operators .are now claiming that when used with a reasonable amount of coring the rotary system is even more satis-factory than cable tools for exploring in certain territory. A case has recently been pointed out in the South Electra field of North Texas, where producing oil sands, passed over by cable-tool drillers, are being brought in with rotary equipment. It seems that in this particular territory the sands are rather thin. Cable-tool drilling was carried on for the most part in a wet hole and the red mud encountered in drilling caved into the hole very badly, so that the cuttings showed mostly red mud and the driller, thinking that the sand did not amount to anything, carried his water string through the sand. The later .operators, drilling into the sand with rotary equipment and coring it, found that it was well worth testing.

Jan 10, 1922

Fluid inclusions and sulfur isotopic compositions were studied in a possible extension of the Toyoha polymetallic vein deposit. The objective of this work was to gain a better understanding of the ore depositional conditions, sources of ore constituents, and distribution of mineralizing fluid in the region. Fluid inclusions in sphalerite and quartz show that most homogenization temperatures range between 190¦ and 290¦C. Most salinities range from 0.0 to 3.4 wt per cent NaCl equiv. Sulfur isotopic compositions of ore minerals (pyrite, sphalerite and galena), determined by a conventional technique, range between 1.3 and 7.7 per mil. The mineralizing fluids were characterized by relatively low and various temperatures and low to moderate salinities compared to those at the southeast region of the main ore bodies (Izumo and Shinano veins) where rare elements such as tin, tungsten and indium occurred. Obtained temperatures and salinities were attributed to the mixing of hydrothermal fluids with groundwater. Sulfur isotopic data suggest sulfide sulfur was of magmatic origin. Isotopic temperatures, estimated from the isotopic fractionation factor between sphalerite and coexisting galena, are between 195¦ and 322¦C. The temperatures are only consistent with fluid inclusion homogenization temperatures in sphalerite or coexisting quartz when sphalerite was a honey-yellow coarse crystal lacking conspicuous colored growth bands. This suggests the detailed classification of mineral pairs growth textures will be necessary for precise in situ measurements to obtain reasonable eothermometric results.

Jan 1, 2002

By M. D. Voegele, C. Fairhurst

INTRODUCTION A computer study of excavation support loads in tunnels and other excavations in discontinuous rock masses was undertaken with the distinct element method introduced by Cundall (1971). In the distinct element method the rock mass is modeled as a composition of individual blocks of rock defined by the joint planes. Normal and shear deformation laws are ascribed to the joint surfaces; the blocks of rock themselves are considered to be rigid. The particular version of the program utilized in this study ran a mini computer and used inter, active techniques for the input of geometrical data such as joint orientation and spacing and subsequent display of rock mass deformation and other data. Two major aspects of the behavior of excavations in jointed rock masses are examined in this paper: i) the behavior of unsupported excavations in rock masses with varying joint configuration, joint properties and in situ stress fields; and ii) the modification of the behavior of similar excavations when support is provided. In the latter case the excavation behavior was examined through the use of ground reaction curves. THE DISTINCT ELEMENT METHOD The Distinct Element method introduced by Cundall (1971) is a computer based analysis that simulates the behavior of a system of discrete, semi-rigid rock blocks. Block interactions are governed by realistic friction and stiffness laws; each block may undergo unlimited displacement and rotation while progressive failure is modeled.

Jan 1, 1982

By Severn P. Brown

Search for ore continued at a feverish pace-as can be attested to by anyone who has tried to arrange for extensive diamond drilling. The stakes are high, and so is the cost as was indicated by Selco Exploration Ltd. when they announced discovery of base metal sulfides at Uchi Lake in northwestern Ontario. It was apparently their first commercial find after 15 years of exploration at a cost of more than $10 million. For the first time in many, many years the big exploration news has come from east of the Mississippi River. In January, the New Jersey Zinc Co., in an unusually worded press release, stated that they had made a major zinc discovery of 13-50 million tons of ore averaging 5-10% Zn. New Jersey's holdings are said to embrace 500 sq mi. The ore was discovered in eastern Tennessee in the upper part of the Knox dolomite of early Ordovician age. Reportedly the mineralization is at depths of 900 to 2000 ft. Currently about 20 diamond drills are working the area for New Jersey. At least nine other major companies are prospecting the region, which now includes parts of Kentucky. Five hundred thousand acres are said to be under lease. Greatest activity is clustered around Carthage, Tenn. In Missouri, the St. Joseph Lead Co. announced plans to develop a new mine in the Brushy Creek area of the "New Lead Belt." copper and zinc concentrates will be by-products.

Jan 1, 1970

By E. J. Quinn, M. F. Fogler

In a recent paper, Rawdon and Mutchlerl gave some exceptionally interesting results on the Brinell and scratch hardness of severely cold-worked metals. In their work, they found that, on continued cold rolling, the metal hardened up to a particular point and then reversed and became softer; this was true for both Brinell and scratch hardness values. The generally reported behavior2 of metals, with respect to Brinell tests on cold-worked material, is that the metals harden up to a certain point and then, on further cold rolling, no change in Brinell hardness occurs. Jeffries and Archer3 state that there is little difference between the scratch hardness of annealed and cold-worked metals; the work of Faust and Tammann4 also indicated no difference between the hardness of annealed and cold-worked copper. Rawdon and Mutchler found, when they plotted the reduction ratio (initial thickness divided by thickness after rolling) against the hardness value for the cold-rolled material, that the hardness number increased up to a reduction ratio of about 3 and then decreased and became even smaller than that for the annealed metal. This behavior was reported for both scratch and Brinell hardness; Figs. 1 and 2 show their results for Brinell hardness on the metals for which they published data. This is an exceptionally interesting phenomenon, if it occurs under all conditions of rolling, and would have an important bearing on the practice of cold

Jan 1, 1925

Karl L. Fetters moves to the front of the AIME organization this month as the 1964 President of the Institute. He will take the chair vacated by outgoing President Roger V. Pierce at the Annual Meeting in New York, already well-rehearsed in his forthcoming duties after a year of preparation as AIME President-Elect. Dr. Fetters is highly qualified for his new responsibilities on both the administrative and professional level. For the past five years, he has been vice president for research and development at The Youngstown Sheet and Tube Co. in Ohio, where he has achieved wide recognition as an out- standing metallurgist and executive. A native of Alliance, Ohio, he obtained his early education in the public schools of his home town and displayed a singular precocity when he launched his professional career as a chemist for the Morgan Engineering Co. at the age of 16. His new career, however, was soon set aside in favor of four years of higher education at the Carnegie Institute of Technology, whence he emerged in 1931 with a bachelor's degree in metallurgical engineering. Surprisingly, and perhaps owing to the employment stringencies of the Depression years, the first job his new qualifications earned him was that of stationary engineer at the Cunningham Sanitarium in Cleveland. After two years of ministering to the mechanical ailments of this institution, Dr. Fetters relinquished his post for a more suitable one in the field of metallurgy.

Jan 2, 1964

By Kent W. Pilz

Wet dust suppression can be achieved by 1) confinement of the dust within the dust producing area with a curtain of moisture, 2) wetting of the dust by direct contact between the particles and droplets of moisture or 3) the formation of agglomerates too heavy to remain airborne, or too heavy to become airborne, by combining small dust particles with each other and with the droplets of liquid. From the standpoint of economy, availability and safety, water is the ideal fluid; however, it is not as effective for dust suppression as when small percentages of specially formulated dust control compounds are blended with it. Performance of dust control com pounds is related to surface active agents and surface activity. In all liquids there is an attractive force between molecules which varies inversely as the sixth power of the distance between molecules. Thus, in the liquid phase where molecules are crowded together, the intermolecular forces are powerful; whereas in the liquid-vapor phase where the molecules are relatively far apart, these forces diminish rapidly. In the body of a fluid there is an uneven distribution of forces resulting in an inward pull called surface tension. The force which keeps two surfaces apart or causes them to coalesce is termed interfacial tension. Fluids of high surface tension exhibit poor wetting, spreading and penetrating qualities. Water has the unusually high surface tension of 72.75 dynes per cm at 20°C.

Jan 7, 1972

By Marvin Barnes

The Sacaton mine is a relatively new open¬pit copper mine owned by Asarco, Inc., which has been in production only a few years. The mineral deposits consist of two ore zones; a western, near-surface zone minable by open-pit methods, and a deeper eastern zone which will have to be mined underground, probably by block caving. The copper deposits are related to small quartz monzonite intrusives implaced into Precambrian granites. Both rock types act as hosts for the copper mineralization, which has been secondarily enriched sufficiently to constitute ore. In the western zone the enriched supergene chalcocite has been subjected to postenrichment oxidation processes with partial destruction of the chalcocite blanket. The deeper eastern chalcocite zone has not been as severely affected by later supergene processes. Several mineralogical populations are represented in the total copper deposit. Leached capping overlies the chalcocite enriched zone, and in the western ore body there is a very irregular interface between the leached and enriched zone, which is complicated by oxide copper minerals irregularly distributed. Primary lower-grade chalcopyrite mineralization occurs below the enriched zone. When mining commenced near the top of the enriched zone, considerable difficulty was encountered in correlating the actual grade of ore in place with the estimated grade of the mining blocks. The mineralogical complexity and fairly wide spacing of diamond drilling made reliable grade estimation of individual ore blocks a difficult procedure.

Jan 1, 1979

By K. A. Kiselev, V. I. Zelentsov, V. P. Nebera

INTRODUCTION Most works on flotation of ions and precipitates from solutions have been summarized recently (1-3). Flotation is more desirable than thickening or centrifuging because of higher recovery, productivity, simplicity of apparatus and better economics in general. Electrolytic flotation that utilizes gases is more favorable than other flotation processes because of the following: higher dispersity of gas bubbles, low coalescence of the bubbles, possibility of gradual regulation of the dispersity and other parameters of flotation (4-5). Flotation from solutions is mostly based on the use of alkaline reagents as precipitants (5). Flotation from acid solutions is less common. We used multicomponent solutions with more than 2-3 components, unlike previous research methods. Acidic flotation allows recirculation of solutions to previous operations such as leaching, etc. REAGENTS FOR PRECIPITATION Electroflotation was studied over a wide range of pH with the addition of ferrocyanide, oxyquinoline, hydroxide and carbonate precipitants. In recent works (1,2,6,7) on flotation of Ni, Cu, Zn from alkaline solutions, mostly ferrocyanides were applied. Our choice was oxyquinoline because of the following: 8-oxyquinoline is a nonspecific reagent for many metals, it is readily soluble in acids and alkalis, oxyquinolates of the studied metals are in soluble compounds, the reagent works over a wide range of pH, it is widely available, oxyquinolate precipitates are stable when exposed to air, are readily floatable, and are easily converted to oxides of the metals by sintering.

Jan 1, 1980

By Chin J. Chang

Powder metallurgy (P/M) technique is known for its capability of producing near-net-shape parts. Its specific characteristics have resulted in low cost and eliminated of many secondary machining. However, more and more P/M parts do require additional operations to fulfil their complex geometric features and surface roughness. Many of the machining factors that influence the machinability of cast and wrought steel parts, such as cutting speed, feedrate, coolant, tool geometry and shape, are also considered in the machining of P/M components. The special feature in P/M structure is the porosity that can decrease the machinability and shorten the tool life. Different variables have been considered in the machinability of P/M materials. Densities and the free machining additive manganese sulphide (MnS), are the two main factors of material composition, which dominate the P/M machining performance. Machining process is the main method that generates the desired working surface of machining components. This paper will discuss the metallurgical structure of the powder metallurgy components, their physical properties and possible issues when encountering machining operation. Turning operation has been tested in this investigation to show the relationship between the cutting speed, federate, cutting forces and chip formation. This investigation also discusses how the free machining additive, manganese sulphide, affects the P/M structure and machinability in order to understand how the metallurgical structure can affect the machining operation and, how to obtain the optimised surface results.

May 1, 2001

By M. Rudman, L. Pullum, L. J. W. Graham

Centrifugal pumps are the workhorse of hydraulic conveying systems but their performance is derated when viscous non-Newtonian fluids, such as pastes and/or coarse solids are present. The reduced performance for purely viscous Newtonian fluids may be calculated using techniques such as the Hydraulic Institute method, but similar deration for non-Newtonian fluids is not so easy to apply. As part of the AMIRA P599 project investigating high concentration suspension pumping, centrifugal pump tests were systematically conducted on a wide range of non-Newtonian coarse particle suspensions. Suspension sup to 38% v/v of coarse particles with mean diameters in the range of 1.1 < d50< 3.4 mm suspended in carrier fluids with dynamic yield stresses of 0 < t?< 17.2 Pa and shear thinning indices in the range 0.35 < n< 0.79 were examined. Techniques such as the Hydraulic Institute de-ration method require a characteristic shear rate to be assigned before application with a non-Newtonian fluid, and a method based on pump geometry, fluid rheology and flow rate is proposed. This method predicts the dramatic characteristic reduction in head at low flow rates that is often observed and explains why larger pumps are relatively insensitive to this form of head deration. Head deration due to the presence of coarse particles in non-Newtonian carrier fluids is seen to follow similar trends to that of Newtonian suspensions and often dominates the total deration procedure.

Jan 1, 2007