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By Thomas E. Green

A combined solvent extract ion-spectrophotometric method for the determination of as little as 1 ppm of copper in tungsten metal or tungstic oxide has been developed and evaluated. Metallic samples are converted to tungstic oxide by treatment with hydrofluoric and nitric acids. The oxide is then dissolved in sodium hydroxide, and the copper is extracted as the colored neocuproine complex. Total elapsed time for the analysis is approximately 1-1/2 days; however, actual working time for a group of six or eight determinations is less than 4 hours. Precision at the 2-ppm level is better than 0.1 ppm.

Jan 1, 1963

By N. M. Langdon

It is now about, two years since we began wing concentrates from Port Henry magnetic-ores in the blast-furnaces of Witherbee, Sherman & Co. During this time we have had the usual ups and downs incident to blast-furnace practice, and have used the concentrates in

Jan 1, 1892

By Paul C. Miclea

With the growing urban population and the concern for traffic congestion and pollution (emissions control), public transportation is becoming more and more attractive to both city dwellers and managers. To gain access to the central area of the city, the sub- way remains the most viable alternative, despite its higher cost when compared to above ground or elevated transportation systems. There are relatively few regulations and criteria for subway ventilation, particularly when compared with mine ventilation. The main document that provides guidance and general recommendations for subway ventilation and environmental control is the Sub- way Environmental Design Handbook, published in 1976 (2nd edition) by the U.S. Department of Transportation, Office of Re- search and Development. Many of the subway systems in existence today have been designed and built with ventilation features adequate for normal train operation, but their design does not consider stringent criteria for such emergency conditions as a train fire in a tunnel. The National Fire Protection Association's Standard for Fixed Guideway Transit Systems known as NFPA 130 as well as the ASHRAE Handbook - HVAC Applications (1995) provide specific design and operation requirements for subway ventilation systems. Some of the existing, old subways are upgrading their ventilation systems to comply with the new regulations. The ability of a particular ventilation system design to provide adequate ventilation during normal and emergency conditions can be evaluated using computer modeling and simulation techniques. A train fire will cause a sudden change in the tunnel ventilation pattern by adding an unsteady and fast-growing source of heat. The hot air and gasses created by a fire will tend to flow uphill, possibly against the normal flow, producing a 'backlayering effect." To prevent this effect from happening, enough ventilation must be provided and the governing criterion to establish the required airflow is called 'Critical Velocity." Several software packages are available for special applications on tunnel and station ventilation as well as to model the spread of smoke and heat in case of a major tunnel fire, using Computational Fluid Dynamics. This paper presents the current issues in subway ventilation, as shared by the public transit community around the world, together with modern alternative design concepts vis-à-vis the more stringent emerging Fire-Life Safety criteria. Examples of recent studies and ventilation systems design are provided.

Jan 1, 1997

IN dealing with this subject the intention is not to write a detailed description of the various methods in vogue on the Kalgoorlie field, but rather to give a brief outline of three of the methods which are most universally in force, and from which, ultimately, a few comparisons may be drawn. The three methods which the writer proposes embodying in this article are known as "The Rill," "The Flatback," and "The Shrinkage." For comparative purposes each method will be applied to a block of ore 500 feet in length, and opened up by levels 200 feet apart."The Rin" System. It is necessary in this system, for facilitating mullocking, to make connections between levels by rising and winzing at about every 100 feet or 150 feet along the orebody. After the leading stope is beaten off for the full length ofthe drive, the level is timbered. Single stulls are put in up to a width of fourteen feet. If the span is too great for stulls, set timbers or saddleback stuUs are used. Stulls are lagged over with 4-in gimlet poles, and wooden chutes are built at intervals of 50-feet. Ore passes are cribbed up through the filling directly above each chute, and are constructed of 7-in. round timber or 9 in x 3 in square timber, the passes measuring 4 ft x 4 ft in the clear.Occasionally a double pass may be carried up, one side serving as a travelling way. Stoping is commenced off the winzes, and rills are gradually formed, one on either end of each winze. The rills are generally at an angle of 37° off the horizontal, this allowing for the boring...

Jan 1, 1909

By Roger E. Scholl

Data on off-site low-rise building damage from underground nuclear testing at the Nevada Test Site (NTS) of the United States Atomic Energy Commission (AEC) [The AEC has been called the United States Energy Research ant Development Administration (ERDA) since 1975, but because the data presented here were gathered between 1966 and 1970, the AEC rather than ERDA is referred to in this paper.] are available for seven large tests in the period from 1966 to 1970. The data, while sparse, provide an adequate sample for the investigation of motion-damage relationships. Damage in the study is statistically described in terms of the incidence of damage complaints, the incidence of buildings damaged, and damage cost. Using 5%damped response spectrum acceleration amplitude to characterize ground motion, the plotted data fit reasonably well with previous motion-damage relationships established from extensive data available from the 1969 RULISON underground nuclear explosion (UNE) experiment conducted in western Colorado.

Jan 1, 1976

By H. M. Morse

During the year of 1940, wildcat wells were drilled in 32 counties of Mississippi; 85 wells in all. These were scattered over the state from the most northern county to the southern counties and from the Mississippi River on the west to the Alabama line on the east. Yazoo County, with 19, received the largest number. The average depth of all the wells was 5333 ft. The shallowest well completed as a dry hole was in Yalobusha County, aban-doned at 1392 ft. in the Selma. The deepest well drilled was in Scott County, abandoned at 10,365 ft. in the Lower Cretaceous Paluxy. G. C. Grasty drilled the Kentucky Lumber Company No. I well, sec. 7, T. 10 S., R. 10 E., Itawamba County, to a depth of 3530 ft. and bottomed his hole in the Ordivician. Tinsley Oil Field.—In the Tinsley oil field 104 wells were completed as producers during 1940. Five producing sands have been logged with a total average thickness of I57 ft. of oil sand. One of these sands is in the Selma, three in the Eutaw, and one in the Tuscaloosa. Vaughan-Pickens Field.—The Vaughan-

Jan 1, 1941

By Walter D. Holland

This instructors guide is intended for use in a course which teaches metal and non-metal mine inspectors to perform surveys for inhalation contaminants in above ground metal and nonmetal mine work areas. The handbook entitled "Handbook for Surveys of Inhalation Contaminants in Above Ground Metal and Nonmetal Mining and Processing Work Areas? is used as a manual during the course. The manual contains a survey check list, rules for determining if sampling is required, a list of most frequently encountered contaminants, a list of candidate contaminants and their sampling conditions, and a description of control procedures and devices. There are several experiments in this guidebook which the trainees perform to acquaint them with the sampling systems.

Jan 1, 2011

By C. Froger

Since its creation in 1950, the Centre d'Etudes et Recherches des Charbonnages de France at Verneuil-en-Halatte (Oise) has been conducting many investigations concerned with airborne dust measurements, particularly in underground mines. The work has resulted in the development, a few years ago, of a new process of dust sampling, whereby the airborne dust particles are collected by a rotary filter of polyurethane foam rotating at high speed within 8 housing.

Jan 1, 1973

By F. F. Aplan, S. Chander, A. R. Alaboyun

Several aspects of the capture of hydrophobic dust particles by droplets in sprays have been studied. The particle capture depends on several sub-processes involving collision, adhesion and engulfment. The collision events between dust particles and a single droplet were observed with a high speed motion analysis system to determine the influence of a surfactant on the capture process. In the adhesive process it was observed that the dust particles are collected at the surface of the water droplet to produce a rigid film at high dust loadings. In the presence of the surfactant, however, the particles were engulfed inside the droplet keeping a fresh surface on the droplet available for capture of more particles. A theoretical analysis is presented to take into account the role of contact angle on the penetration of particles into droplets. A significant increase in collection efficiency was observed with decrease in droplet size.

Jan 1, 1991

By T. T. Chen, J. L. Jambor, J. E. Dutrizac

A reconnaissance study of the neutralization potential of 30 diverse minerals, 28 of which are silicates and aluminosilicates, has shown that most of these minerals contribute minimally to the neutralization potential (NP) in standard static tests. Feldspars in particular give low NP values and would not be expected to attenuate the acidity to any significant extent in acid rock drainage settings. The BET-determined surface areas of the minerals vary considerably, and the large surface areas of some of the pulverized samples have clearly affected the NP values even though the standard static-test protocol was used for the preparation of the samples. The low NP values of most silicates and aluminosilicates are in general agreement with the laboratory-determined slow dissolution rates for these minerals. The results suggest that, in the prediction of whether rocks will be acid-producing, the most realistic measure is that of the carbonate content. In mine wastes from metalliferous ore deposits, the contribution to the NP by the non-carbonate gangue assemblage is unlikely to be more than a token amount until well after the establishment of an acid rock drainage situation.

Jan 1, 2000

By J. H. Gwynne

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Jan 1, 1962

By C Gunther

The term metamorphism as commonly used means any change in a rock in either form or composition, from whatever cause. By metasomatism, according to Lindgren, is meant a metamorphism that involves a change in the chemical composition of a rock by the addition or subtraction of substance. Certain types of metamorphism are due to the action of mineralizing solutions, and are closely connected with ore deposition; they form, therefore, valuable guides in the exploration for ore-deposits. Other types of metamorphism are due to regional processes, and are not connected with ore deposition. By dynamo-regional metamorphism is meant a primary alteration of rocks over large areas under conditions of pressure, flow- age, and heat. This process produces schists and gneisses from either sediments or igneous rocks. It is thought that there is little migration of minerals or of elements in dynamo-regional metamorphism, and that the changes are due chiefly to recrysallization and rearrangement of original minerals in bands with their major axes oriented normal to the direction of greatest pressure. Under these conditions limestones are commonly altered to marble, and sandstones to quartzite, basic igneous rocks to greenstone or serpentine, while rocks of normal or acid com- position commonly yield the usual types of schist or gneiss. Dynamo-regional metamorphism, extending over large areas, has no connection with mineralizing processes, and is, therefore, no guide to ore deposits; while this process has certain features, such as characteristic mineral associations, in common with contact metamorphism, the results of the two processes may usually be distinguished without difficulty.

Jan 1, 1932

By A. Koursaris, Y. Turan

The object of this study was to investigate the i1Jfluence of nitrogen on the structure and properties of AISI 310S steel. Experimental ingots of the steel with nitrogen contents of up to 0,525 per cent by weight were prepared, hot-rolled, and tested after various treatments. The rollability of the material was adequate. The yield strength, tensile strength, hardness, and fatigue properties of the new alloys improved with increasing nitrogen content. The impact properties improved slightly. Empirical equations were developed for the calculation of the yield and tensile strengths, as well as the difference between these two properties, with increasing nitrogen content.

Jan 1, 1995

By E. R. Borcherdt

METHODS and equipment are subject to study in the Butte district at all times in order that advantage may be taken of any new developments that might serve to increase efficiency and lower costs. Detailed time studies of each operation involved in the entire mining process have been of invaluable assistance in analyzing the individual operation for possible improvement. In other words, the fact that a practice has been in vogue for many years does not exempt it from change provided an easier and cheaper method can be found. EXPLORATION Ore occurs in the Butte district in such manner that structures must be drifted on, no matter how small or unimportant they appear when intersected by a crosscut. Parallel structures also add to the crosscut requirements. This prospecting work, which formerly was done entirely by drifting and crosscutting, is now being supplemented by diamond drilling, to aid in greatly decreasing the amount of waste. In long-shot prospecting, or in second or third class prospecting, where the chances of developing commercial ore are not very great, diamond drilling is of particular value. In prospecting where chances of encountering commercial ore are certain or where crosscuts can be used later for haulage or ventilation, drilling obviously is not applicable. Improvement in drilling machines and bits has contributed greatly to the present success of diamond drilling. STOPING For many years square-set filled sloping was the principal mining method used in the Butte district. Later timbered and untimbered rill stopes were used, also some horizontal cut-and-fill sloping where both ore and walls were particularly strong. Because of the amount of timber required for square-set stoping, and the relatively low production per scope unit, experiments with horizontal cut-and-fill scopes were begun in ore bodies of which many had fairly weak walls. It was felt that increase in the speed of the stoping operation, followed closely by filling, to avoid weight being produced by permitting ore and walls to remain insufficiently supported over comparatively long periods, would maintain the walls and backs in safe condition without the use of timber and without ore dilution from wall slough. Cycles of drilling, scraping ore, and filling were devised, which have materially increased stope production and decreased timber consumption, so that both stope labor and supply costs were lowered appreciably without materially affecting grade control. In the larger mines of the district, where wide veins favor this stoping method, half of the total production is now being mined by horizontal cut-and-fill stopes (Fig. I). The increase of the filling rate demanded by the increased stoping rate was the greatest obstacle encountered in the accelerated stoping operations. Finally this problem was solved by replacing the time-honored method of transferring filling waste by small cars, which were hoisted or lowered in the auxiliary shaft, by a transfer

Jan 1, 1941

By J. Golamnejad

This paper attempts to model long-term production scheduling problems by chance constrained binary integer programming in a stochastic environment. This stochastic model is set up to account for ore block grade uncertainty. The probability distribution function of grade in each block is used as a stochastic input to the optimization model. This distribution function in each block should be determined using a Geostatistical Simulation approach. The deterministic equivalents of these chance constraints are then achieved, which are in the form of nonlinear in binary variables. A confidence level at which it is desired that the uncertain constraints holds, is specified in each scheduling period. Rather than the previous risk-based model, this formulation will yield schedules with a high chance of achieving planned production targets while maximizes the expectation of net present value and minimizing the variance function simultaneously. Using this method, the grade uncertainty is integrated explicitly into the optimization process.

Jan 1, 2006

By R. H. Richards

IN nearly all ore-dressing operations it is a common practice to discharge mixtures of fine ore and water through spigots; for example, from classifier pockets, from jig hutches, from settling tanks, etc. As a, general rule it is desirable to regulate the composition, i.e., the ratio of water to sand, of such discharged products; and this can usually be done by varying the size of the orifice or spigot through which the material is discharged. Thus it is that problems similar to the following are frequently encountered: With a given quantity of solids per unit time, of a given specific gravity, to be discharged with water under a given head, and with a given ratio of water to solid, what must be the size of the spigot opening? If the spigot is to be open continuously, there are, aside from its form, but three factors governing the rate at which it will discharge a mixture of sand and water, namely: the head of water above the spigot; the area of the spigot opening; and the viscosity of the material to be discharged. The term viscosity, as used here, means the ratio of the volume of pure water that will flow through a given orifice under a given head in a given time to the volume of the material under consideration that will flow through the same orifice in the same time under the same conditions. While the actual viscosity of water containing sand in suspension is not increased by the presence of the sand, nevertheless the volume-rate at which such a mixture will flow through an orifice is less than that at which pure water will flow, by reason of the friction of the particles of sand against each other and against the sides of the orifice. In other words, the flow is retarded as it would be by increased viscosity; and therefore, for the purpose in view, we may speak of the viscosity of a mixture of ore grains and water as defined above. The head of water above the spigot is generally fixed by the form and design of the classifier or tank to which the spigot is attached. So, with the head known, in order to determine the size of the spigot required it is necessary to know the viscosity of the desired mixture, and the coefficient of discharge of

Jan 1, 1915

By Craw D

The Southern Alps in the South Island of New Zealand are currently rising rapidly as a consequence of continental collision along the Pacific-Australian plate boundary. Rapid uplift has resulted in a major thermal anomaly in the shallow crust beneath the alps. Alpine topography and associated intense precipitation, coupled with the thermal anomaly are responsible for vigorous combined topographic/convective circulation of water through the shallow crust.

Jan 1, 1995

By J. R. Dixon

Gold mining has been undertaken in South Africa for more than a century. A great proportion of that mining has been from the Witwatersrand Basin; a geological phenomenon that has few parallels throughout the world. It has produced some 47 000 tonnes of gold mainly from underground mines, many of which have been truly world class gold mines. The gold mines of the Witwatersrand Basin have dominated world gold production from their inception and their production has been one of the cornerstones of the development of South Africa as a whole. The mines have some very specific characteristics; their sheer size, the depth of extraction, the nature of the orebodies, and their labour-intensive methods. The mines have also been part of the Mining House concept-a concept unique to South Africa. South African production has declined from a maximum of 1000 tonnes in 1970 to 470 tonnes in 1997. This, as a percentage of western world production, has declined from a maximum of 79 per cent (in 1970) to 21 per cent of world production (in 1997). The nineties' have seen South Africa and its mining companies move onto the world stage and face the harsh realities of having to compete in all spheres of business with their aggressive counterparts principally in Australia, Canada and the USA. The fight is for investment funds with the owners looking for the best returns on their money. In his address Roger Dixon will examine the current situation in the gold mining industry and examine the competitiveness of the mines of the Witwatersrand Basin compared with their peers worldwide. He will also discuss some of the fundamental challenges facing South African gold mines in the areas of legislation, technology, industrial relations, and health and safety. The environment in which the mines operate has changed radically in recent years and their ability to respond to these challenges will determine their future existence.

Jan 1, 1998

By Peter N. Calder, Alan Bauer

The complexity of modem open pit load-haul-dump systems is described, and the need for realistic working models is pointed out. Both standard and probabilistic simulation procedures are discussed, probabilistic simulation being indicated as the more powerful and practical technique. Acquisition of the necessary pit operating data required for simulator construction and general modelling procedures are described. Finally, results from a typical open pit simulator are used to indicate the scope of the technique.

Jan 1, 2014

By S. Kahraman, K. Develi, E. Yasar

Four hydraulic top hammers, one pneumatic top hammer, and three down-the-hole drills were observed in several rock types at quarries and highway construction sites to measure the performance data. At the same time, drill cuttings from each drill hole were collected for the determination of the coarseness index (CI), which is the sum of cumulative weight percentages of a particular size-graded sample of debris, and for the determination of median particle size (MPS), which is defined as the particle for which the quantity of particles equals 50% of the total of the cumulative distribution. After the sieve analysis was carried out on the drill cuttings in the laboratory, CI values were calculated and MPS values were obtained from the plots of cumulative undersize vs particle size. The performance data of the drills, CI values, and MPS values were analyzed using the least square regression method. It was seen that strong linear relationships usually exist between penetration rates and CI values, and penetration rates and MPS values for both top hammer drills and down-the-hole drills. Penetration rates increase linearly when increasing the CI and MPS values.

Jan 1, 2004