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By Miquel Lamadrid, Changshow Sun, Chris Johnson

To reduce blasting overbreak and improve stope stability, several new blast designs were proposed for current and future stopes. Based on the analysis of the powder factor, and the extent of damage zone, the appropriate new blast design was selected. Excellent results were achieved from the new blast design. Comparing the new blast design with the old one, the largest of the overbreaks decreased more tan two times and average overbreak reduced more than two times. The new blast design is currently applied in all mining zones in Leeville underground mine.

Jan 1, 2008

To provide a means for mechanically separating and recovering nonferrous metals continuously from non-magnetic reject material produced at scrap automobile shredding facilities. Approach The Bureau of Mines developed a water elutriator system that separates metals from shredded scrap auto-mobiles based on differences in specific gravities. A premium-quality product, containing aluminum, magnesium, lead, zinc die cast, copper, copper alloys, and stainless steels, is obtained. How It Works Mixed nonmagnetic reject material currently being separated at automobile shred-ding facilities is introduced onto the top of an upwardly flowing vertical column of water. The water, overflowing a weir in the top of the vertical column, carries with it the floating, lightweight waste materials, mostly combustibles, while the heavier pieces sink through the rising water. Medium-density substances such as glass, rubber, and heavy plastics are carried off through a side port, located in the upper third of the column. The cleaned, mixed metal product sinks to the bottom and is continuously removed from the base of the column with a bucket elevator having perforated buckets. All three categories of material are removed from the system on separate wire mesh belt conveyors. Most of the water drains through the belts into a holding tank and, after settling, is recirculated back through the elutriator column. The purity and recovery of the metal product are influenced by two elutriator operating variables: the flow rate of water through the vertical column, and the height of the overflow weir at the top of the column.

Jan 1, 1983

By R. C. Ellman

Significant effects of in-the-mill drying on the pulverization of lignite have been demonstrated in an experimental impact-type pulverizer by tests in which the primary variable was temperature of the sweeping gas. Reduced power requirements and increased product fineness were observed as the extent of drying was increased. Pulverization with in-the-mill drying was studied in comparative tests made on lignites from five mine sources. All of the lignites responded in a similar manner; however, differences in the pulverizing characteristics of the individual lignites were significant. For one lignite, the electrical input to the pulverizer driving motor with minimum sweeping-gas temperature was 33.9 kw.-hr. per ton, decreasing to 14.0 kw.-hr. per ton with a sweeping-gas temperature of 658° F.; for another lignite, at comparable operating conditions, the electrical input decreased from 59.1 to 19.0 kw.-hr. per ton. In the first case, the product fineness increased with increasing temperature of sweeping gas from 65.2 to 79.2 percent through a 200-mesh sieve, and in the second case, from b2.7 to 86.9 percent through a 200-mesh sieve.

Jan 1, 1962

Jan 1, 1885

By A. M. Talbot

THERE is still considerable controversy as to the exact nature of the mechanism of the age-hardening process, in spite of the many experi-ments already performed. For this reason, a considerable number of typical systems should be examined in detail and their results correlated. Furthermore, the methods of studying the changes that take place during the progress of this phenomenon should be carefully scrutinized and the different methods applied to the same samples, preferably at the same time. The experiments described in this paper are presented to supply information on one age-hardening system and to show how the various methods of investigation compare in their indication of what has hap-pened. In brief, the progress of aging in magnesium alloys containing about 10 per cent by weight of aluminum at different temperatures was followed by measurements of hardness, electrical resistivity, dilation and lattice parameter, and by microscopic observation.

Jan 1, 1936

By Edmund Shaw

In the year just past there were produced in the United States about 170,000,000 tons of sand and gravel. Much of this was pit-run material used for gravelling roads and as railroad ballast on lines that did not carry heavy traffic. But more than half of it was marketed as washed and sized, or graded, material. The methods used for preparing sand and gravel for the market have long been used in ore dressing and, as in ore dressing, depend on differences in the specific gravity of two substances or in the size or weight of particles. But many changes in the design and operation of plants and machines have been necessary. In ore dressing, the concentrate is only a small part of the feed; in sand and gravel washing, it is much the larger part of the feed. In addition, such close work as is needed when concentrating a metallic ore is not needed when washing gravel; the ability to put through a large tonnage is more important, and sizing, which is only a preliminary process in ore dressing, is an end to be attained. Rock crushers are found in most sand and gravel plants and they are used to break up the larger pieces from the deposit (known as boulders and cobbles) which are removed by a scalping screen. The crusher discharge is usually sent back to the scalping screen, the perforations in this screen setting the maximum size of the finished product. Washing Washing is to prepare sand and gravel so that they may be used as aggregates in concrete and wall plaster and in various processes in which impurities would harm the product. At one end of the scale of washed materials may stand ordinary concrete sand, which in some states may contain as much as 3 per cent, of clay and still be used in highway concrete construction. At the other end will stand the silica sand used for making plate glass, which must be washed so clean that the impurities that can be removed by washing do not exceed a few hundredths of a per cent. The methods and machinery that would produce one of these

Jan 1, 1926

By William G. Fischer

Equations developed by an early researcher in subsidence, F. Martos of Budapest, Hungary, have been slightly modified to produce effective equations for predicting the time-dependent nature of Green River trona mine subsidence. Following the initial study, a survey was run to check the results twenty years after mining of the area had been completed. The final results were within a few centimeters of the value that had been projected. Mining conditions in the Green River area are ideal for this sort of study with trough type subsidence being the surface manifestation of high extraction underground room and pillar caving operations.

Jan 1, 1986

By Persifor Frazer

(Read at the Wilkes-Barre Meeting, May, 1877.) A CLASSIFICATION of natural objects is usually based either upon some fundamental and permanent attribute of the thing itself (as in the case of scientific classifications), or it embraces one or more generalizations convenient for use in ordinary life. Thus, it suffices for the statistician to, know that so many tons of fish are annually taken by our fishermen, and that they realize so many thousands of dollars, whereas to the student of natural history the anatomy, habits, and relationships of the animals are of chief interest, as settling their respective places in the scale of animate nature. Many different classifications of coals have been attempted, as one would naturally anticipate from the immense extent of the coal trade, and the different localities whence the supply was derived. The English divisions were prevalent up to the date of the publication of the last geological survey of the State, except so far as they were modified by local designations. Indeed, Rogers' classifications made very little alteration in the English nomenclature, as may be seen by comparing. the tables given below. To commence with the different kinds mentioned in Ure's Dictionary of Arts, Manufactures and Mines of 1845 " 1. Cubical Coal.-Black, shining, compact, moderately hard and easily frangible. Comes out in rectangular masses, of which the

Jan 1, 1878

Some important mineral fields are referred to in discussing the formation of placer deposits in Australia. Testing methods include boring hand, with percussion rigs; with auger and pit digging drills; and l by vibro drilling. Sampling errors are minimized by the use of correct techniques and equipment for boring, sampling, and sample dressing, A hypothetical set of data is used to demonstrate the final process of evaluation, and some relevant taxation provisions are discussed.

Jan 1, 1964

By Webster SS

This paper uses computer modelling tech- niques to compare and contrast anomaly patterns obtained with fluxgate (vertical field) and proton precession (total field) magnetometers at typical latitudes in northern and southern Australia. The use of these modelling tech- niques is suggested as an aid to magnetic interpretation and field examples are included from Tasmania and the Northern Territory.

Jan 1, 1975

By R. C. Buehl, J. P. Morris

ACTIVITY values for sulphur dissolved in liquid iron and slags as functions of composition and temperature are needed in applying thermodynamics to sulphur-control problems in iron- and ' steel-making. The purpose of this investigation was to determine the effect of carbon on the activity of sulphur in the metal phase. The method employed was the same as that used in an earlier investigation' concerning the effect of silicon on sulphur activity in liquid iron. A study was made of the conditions of equilibrium in the reaction between hydrogen gas and sulphur dissolved in iron-carbon alloys. The chemical equation for this reaction can be written as follows: S (in liquid Fe-C alloy) + H2 (gas) = H2S (gas). It was found that the activity coefficient of sulphur in liquid iron increases as the carbon content increases. At 2.3 pct carbon and 1600 °C, the activity coefficient of sulphur is twice its value in carbon-free iron, and at carbon saturation it is more than six times as great. The effect of temperature on sulphur activity was found to be small. Previous work on the reaction between hydrogen gas and sulphur dissolved in liquid iron has been reported by several investigators2,³,4 but only recently have studies been made of the effect of alloying elements. Silicon1 is known to have a pronounced influence on the activity of sulphur in iron, its effect being similar to that shown by carbon as described in the present report. Kitchener, Bockris, and Liber-man5 recently have published a preliminary report of their work on the effect of carbon on sulphur activity in iron. Their experiments were made at 1570°C and carbon saturation in the melt. Under these conditions they found that the activity coefficient of sulphur was approximately doubled by the presence of carbon. This is a much smaller effect than that found in the present work. Experimental Method: The apparatus and procedure were essentially the same as those used in the earlier investigation of the effect of silicon on sulphur activity.' Briefly, the method was as follows: A molten iron-carbon alloy was brought to equilibrium at constant temperature with a mixture of H2 and H2S of constant composition by bubbling the gas through the metal. Samples of the melt were

Jan 1, 1951

By Forrest T. Moyer

Injury experience in the mineral mining and processing industries during 1968 was slightly improved in the nonfatal-injury record but worse in the fatality record. The resulting frequency rate of all injuries was slightly better, whereas the injury-severity rate retrogressed appreciably from the figure for 1967. Overall operating activity, as measured by man-hours of worktime, was slightly higher in 1968. However, there were several major segments of the mineral industries in which activity was lower owing to reduced demand for mineral products and to several major work stoppages. These statistics comprise the injury and work experience of all personnel engaged in production, exploration, development, maintenance, repair, and force-account construction work, including supervisory and technical personnel, and working partners and owners at mineral-producing and mineral-processing establishments in the United States. Data concerning officeworkers are excluded except for the oil and gas industry for which such information is not separable. All injury rates and totals are calculated from data before rounding. The data for 1968 are preliminary except for the anthracite, coke, petroleum and natural gas, native asphalt, peat, and slag industries, which are final. The figures represent full coverage for all industries except oil and gas for which coverage is not complete, particularly with respect to small companies.

Jan 1, 1970

By Chang JF

This paper describes the advance in shaft sinking technique in terms of a vast complex of equipment in the last decade, and mainly recommends some ad- vanced technology and a vast complex of equipment, such as smooth blasting, la- ser guiding, shot-crete lining and rock- bolting, hanging bracket ring for drills, large-capacity wall grab, tipping device, storage bunker, and automobile haulage et.al., finaly, author in detail repre- sents some successful applications of advanced shaft sinking technique in some mines as an example.

Jan 1, 1987

By Walt Meglasson

The Kaiser Aluminum Company Smelter, one of several in the Pacific Northwest, was built in 1942 and operated by the Olin Company during World War II and then purchased by Kaiser Aluminum after the war. At its height, the facility employed over 350 workers and was capable of producing 73,000 tons of aluminum per year. It was closed in 2000 through a combination of rising electrical and labor costs, and the inability to compete with more up-to-date foreign facilities.

Jan 1, 2008

By Wasserman A. D

Methodological approaches and in- vestigation results are considered in the paper of heatmass transfer processes when harmful impurities are scattered and remo- ved from chamber-like workings, of the air distribution in complicated ventilation sys- tems and of chemical conversion of exha- ust gases in mine atmosphere when diesel equipment is operating. The results presented in the paper are the base for creation of the automatic design, control and regulation of the venti- lation processes.

Jan 1, 1988

By Weldon Li

Outline ?Introduction and Motivation ?Previous Research ?Details ?Findings ?Current Multi-Piece Mining Wheel Research ?Methodology ?Preliminary findings ?Current and Future Activities ?Summary and Closing Remarks

Oct 1, 2010

By Armando Diaz

Vedanta Resources plc is a London listed diversified metals and mining group. The group produces aluminium, copper, zinc, lead and iron; also commercial energy. In this sense, the paper show all the steps on how this expansion is going on, because is the beginning of the plan.

Sep 12, 2011

To THE BOARD OF DIRECTORS AND THE MEMBERS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS GENTLEMEN: Herewith are transmitted the joint report of the Treasurer and Finance Committee for 1935 and the reports for the same year of the Chairmen of the following Committees: Admissions, Membership, Papers and Publications, Library, MINING AND METALLURGY, and Rocky Mountain Income. . To these reports you are referred for details of the year's activities. Finances. : Income continues to increase the total for the year 1935, being $141,754 compared with $134,967 in 1934, and $121,689 in 1933, which was the lowest reached during the depression. The principal increases were $2000 in Current Dues; $2400 in Dues from New Members; $2000 for Advertising in the monthly magazine MINING AND METAL¬LURGY; and $1600 in Sales of Authors' Reprints and TRANSACTIONS volumes. Income from Dues in Arrears was $1000 less as a consequence of the fact that arrearages had been largely reduced during 1934, so that there were fewer from which to draw.

Jan 1, 1936

By Dale A. Didcoct

Through the combined efforts of the C. S. Bureau of Mines, the coal industry, and Burrell Construction and Supply Company, New Kensington, PA, a steel fiber reinforced concrete crib block to improve coal mine safety in the area of roof control has been developed and is currently in use commercially. The development objective was to improve health and safety conditions with a stiffer, stronger, nonflammable roof support at a competitive cost. During the time this method of roof control has been in use in the mining industry, it has proven to be both functionally and economically effective.

Jan 1, 1982

By E. T. Turkdogan, L. S. Darken, R. G. Olsson, H. A. Wriedt

Several aspects of the calcination of Michigan limestone were investigated: the rate of calcination of limestone spheres with diameters from 1.8 to 14 cm at temperatures from 800° to 1200°C by a thermogravimetric method; the temperature profile across limestone during calcination; the excess pressure developed in the interior of the stone during calcination; the pore surface area, pore volume, and effective gas diffusivity in burnt lime; and the microstructure of polished and fracture surfaces. It is found that, over a wide range of experimental conditions, the difference between the surface and center temperatures remains essentially unchanged during the latter half of calcination. From the rate of weight loss after about 50% calcination, the value 0.00126 cal per cm sec degree is found for the effective thermal conductivity of burnt lime. From the excess internal pressure measurements, i.e., 0.4 to 6 cm Hg at 800° to 1200°C, the permeability of burnt lime is estimated to be within the range 8 X 10-' to 5 X 10' sq cm. With increasing temperature and time of calcination, the pore structure of burnt lime coarsens as indicated by a decrease in the pore surface area, pore volume, and an increase in the average pore size. For the temperature range 600° to 835°C the ratio (effective gas diffusivity/molecular diffusivity) is about 0.18.

Jan 1, 1974