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By Fred C. Bond

IN crushing and grinding the larger particles are more exposed to the work input. They absorb most of the work and protect the smaller neighboring particles from destructive contact with the crushing surfaces or grinding media. The importance of this exposure differential upon the reduction efficiency and product size distribution has long been recognized. Unfortunately, there has heretofore been no direct method of evaluating it, and such indirect methods as observing the slope of the plotted product size distribution line have been used as an indication. In this presentation the Third Theory of Comminution' has been used, together with the exponential formula for size distribution, to evaluate the ex- posure ratio and exposure constant and to illustrate examples of their utility in crushing and grinding applications. The exposure ratio Er varies from zero to unity. It is zero when the product particles are all of one size, and it is unity when the work input has been equally distributed among all particle sizes. It can readily be found from screen analyses plotted according to the Third Theory. The exposure constant K is derived from the reciprocal of the exposure ratio Er. It permits more consistent predictions of size distributions and evaluation of many factors concerned in size reduction operations. The Third Theory1 states that the specific work input required for size reduction is inversely proportional to the square root of the product size less the work required to form the feed. When P represents the diameter in microns which 80 pct of the product passes, F is the size 80 pct of the feed passes, Wi

Jan 1, 1958

By Minoru Kawamura, Shinya Tanaka

In Japan, a cartridged emulsion explosive is generally used for tunneling. The workers are compelled to approach the face on charging the explosives into the drill hole with the tamping rod. Therefore, the workers are exposed to the risk of the disaster with the cave-in and the falling rock. The mechanization of the tunnel work has been advancing gradually. Especially, the development of the mechanization for charging work is desired in order to avoid the risk of disaster on workers. Recently, some charging machines such as the bulk emulsion explosives have been evaluated. However, a universal method has not been established yet, because the evaluated machines were not adequately suited from the point of the regulations and the consumption style of explosives.

Jan 1, 2008

By Alexander B. Morris

In a recent paper on the intermittent injection of gas in gas-lift operations as opposed to continuous injection, Morgan Walker presented a comparative table showing the effect on oil and gas production from the same wells under the two methods of operation.' This table carried a column showing the formational gas-oil ratios under each method, computed by deducting the volume of input gas from the volume of trap gas. During the entire spring and summer of 1928, the present writer had been engaged on some extensive test car tests of rich gas in Glenpool, seeking, primarily, for an explanation of the apparent loss of gasoline during the summer season between the field meters and the plant master meter. Tests at several of the field meters where the richest gas was obtained regularly failed to check with other tests on the same gas made farther along the line, and the difference was not made up by the quantity of drip gasoline collected between the points. In the course of these tests, the final outcome of which is immaterial to the present purpose, an attempt was made to construct a curve representing the relationship between gasoline content of the gas in gallons per thousand cubic feet and the shrinkage in the volume of gas treated as a result of removing the condensible fractions. Such a curve was made, expressed in units of gallons per thousand cubic feet on the abcissa and the ratio vapor volume to liquid volume on the ordinate. This curve is a rectangular hyperbola and shows that 3 gal. of gasoline taken from 1000 cu. ft. of raw gas as a vapor occupied much less space, per gallon, than did 1 gal. of gasoline taken from 1000 cu. ft. of another sample of gas. This is, in general, corroborated by converting to the same units the residue settlement curves prepared by the Tidal Oil Co. and by the Natural Gasoline Manufacturers Assn., though the three curves, when plotted together, occupy entirely different positions on the paper, as shown in Fig. 1. The bearing of all this on Mr. Walker's discussion of gas-lift is this: if the formational gas is to be computed by deducting the input gas from the trap gas, some correction must be made for the vapor volume

Jan 1, 1930

By L Gladysiewicz

This paper deals with the current situation in the mining industry in Poland. An overview of typical transport systems working in the different branches of mining is provided. The transport systems currently used in lignite mining, particularly in the Belchat=w mine û the largest brown coal mine in Poland, and those operating in copper mines are described in detail. New designs of belt conveyors used in underground hard coal and copper mining are presented.

Jan 1, 2003

By R. C. Rowe

DR. W. F. GRAY (Contributed discussion, presented at meeting by Mr. S. C. Mifilen): Mr. Rowe's suggestion that the Institute should organize itself to interpret the needs of the mining industry to federal and provincial mines departments should commend itself to our membership as sensible and practical, and as one which these public administrative bodies may welcome. One has to start with the premise that those who head the departments of mines in question have the welfare of the industry at heart. Also, it must be postulated that the technical viewpoint of our membership is necessarily free of political considerations. With these reservations, one ventures to state that both Mr. Rowe in his communication to the present session of the Institute, and Professor M. Y. Williams in his earlier communication to the Western Meeting, on The Geological Survey and Mining Development (1), voice the regret general among our membership at the abandonment of the honoured name, and to some extent of the status, of the Geological Survey of Canada. The writer, in 1932, devoted his Presidential Address to the Institute to an appreciation of the value to Canadian mining of the Geological Survey of Canada (2), affirming the desire of the Institute "that the work of the Survey shall be maintained at the highest pitch of efficiency the resources of our country will permit, because, to scrimp expenses on the Survey, is 'to save at the spigot and lose at the bunghole'." He believes that is still the opinion of the Institute, and, if contraction of the usefulness of the Survey is feared by our members at this time, it is incumbent upon the Institute, in fairness to those who direct our government, to say so in precise and explicit terms. Mr. Rowe puts the situation pithily when he writes: "We have reached a stage in our development where a stock-taking and co-ordination of existing knowledge and data is essential. This is a part of that basic function of Dominion mineral technical services which is national and not provincial in its scope".

Jan 1, 1939

By S. Norton

GEORGE C. FOOTS, Port Henry, N. Y. (written discussion).-The paper by Mr. Norton and Mr. LeFevre will bear the most careful consideration by all interested in the iron business, particularly in the East. There is much information contained therein which should be emphasized. The idea of handling iron-bearing rock in quantities comparable to the porphyry coppers does seem at first blush to be beyond the pale of commercial possibility. Yet, today in the Adirondack region 25 per cent.

Jan 4, 1917

To provide safer and more efficient mine operations by improving the operational performance of underground trolley line communication systems. Approach The dc trolley line provides a convenient means of In-mine communication since it can carry signals to each phone on the system whether the phones are in mine vehicles or in a fixed location such as that of a dispatcher. In many cases, however, the system does not perform satisfactorily. Short communication range, noise, and dead spots commonly interfere with effective communication. These problems are inherent with the trolley line, which was designed to transmit power and not communication Signals. As a power line, the trolley line is connected to rectifiers and feeds many loads such as motors, water pumps, track block lights, etc. Each of these devices represents a low impedance radio frequency (RF) shunt that seriously reduces carrier communication Signals. Performance is therefore often poor and can be improved only if the effects of the various shunts can be reduced. The Bureau of Mines has developed numerous methods applicable to either existing or planned phone systems which can improve communication range and reduce the shunting effects of the various loads.

Jan 1, 1983

By Philip A. Bucci

The Florida phosphate industry successfully uses froth flotation to concentrate phosphate in: the particle size range of approximately 28 to 150 mesh. However, as recently as 1965, coarse particles in the range of 14 to 28 mesh generally had not been beneficiated by conventional flotation methods at recoveries high enough to be considered adequate. It has been customary to upgrade this coarse material; by "agglomerate flotation" or "skin flotation" using belts, tables or spirals. While these devices have proved commercially effective, their capacities are much lower than those of froth flotation cells. To determine whether coarse phosphate material could be recovered successfully by froth flotation, Armour Agricultural Chemical Company began a series of pilot and plant tests; in April 1965. Objective of the tests was to compare over-all performance of a froth flotation cell design relatively new to the phosphate industry with results from the belt circuit at the Bartow, Fla., plant.

Jan 1, 1966

By Will H. Coghill

In this investigation, the low-grade red iron ores of Alabama were examined by the use of "heavy solutions."' Ores are generally ground preparatory to concentration and as long as the concentrators make suitable products the effectiveness of the grinding is likely to be unquestioned; but when suitable products are difficult to make, an investigation becomes imperative. In such a case a dissection of the ore might be made to find the cause of the trouble. Such a condition of unsuitable products exists in the low-grade red iron ores of Alabama. They are difficult to concentrate. To be sure it might be said that the concentration of iron ores is a new thing and that the ore-dressing methods are undeveloped, but a glance at the industry reveals an abundance of methods and devices for almost all imlaginable conditions. Concentrating machinery has not been tested in this investigation. When the properties of the ores have been gleaned, the machinery may be used more effectively. Alabama Low-grade Red Iron Ores The Bureau of Mines has undertaken by laboratory methods to select the best means of concentrating the low-grade iron ores of Alabama. These ores constitute the parts of the ore bed left by selective mining. If more of the ore bed could be included in the current output, the mining cost would be reduced and longer life of the district would be insured. This advantage would be reflected by added permanence of churches, homes, schools and every undertaking in the commonwealth. The red ores chosen for this study of effectiveness of grinding are too low in lime to meet the requirements of the blast furnace. If lime is

Jan 1, 1927

By Xianjun Lu

This paper presents gold occurrence investigations on the altered rock gold deposit from Jiaodong area of China, and comparisons of gold occurrence in the ore samples from different mining levels. According to the results, the chemical and mineral compositions of raw materials from different mining levels are quite similar. However, the relative content and grain size of gold minerals are quite different between the two mining levels of -130m~-340m and -550m~-650m. In the ore of upper mining levels of -130m~-340m, electrum is the dominant gold mineral and accounts for about 80% of the total gold minerals, while native gold is minor and accounts for about 20%. As for the ore of deep mining levels of -550m~-650m, the major gold mineral shifts to native gold which accounts for 67%, while the ratio of electrum drops to about 33%. Coarser gold grain size was observed in the upper mining level ore with a mean size of 33.05µm while the gold grain size was much finer in the ore of deep mining levels with a mean size of 22.85µm. Furthermore, the gold mineral associations also show different patterns between the upper mining level samples and the deep mining level samples. Of the three observed gold association types such as inclusion gold, fissure gold and interparticle gold, more inclusion gold was found in the ore of deep mining levels. The inclusion gold accounts for 62% in the ore of deep mining levels, while that in the ore of upper mining levels accounts for about 56%. Further study revealed that the dominant gold associated minerals are pyrite and sulphides and only a small amount of gold is associated with quartz and silicates. It was shown that the altered rock gold ore from Jiaodong area can be regarded as a free milling gold ore, but the processing parameters should be optimized for the ores in different mining levels according to the different gold occurrence. In addition, it was predicted that enhanced gold liberation is necessary for the ore in deep mining levels.

Sep 1, 2012

By B. Oraee

Tunnels as any other structures are affected by different loads and stresses. Generally, the loads on tunnels consist of both static and dynamic loads. These loads must both be considered in the tunnel design process. In this paper, the stability state of Jiroft water-transform tunnel is evaluated. Firstly, the in-situ stresses and then using Kirsch?s equations the induced stresses due to static loads in walls and crown of tunnel are calculated. Consequently, the strain caused by probable earthquake without considering the interaction between the concrete lining of tunnel and rock mass using seismic analysis is calculated based on free-field deformation. When the strain is determined, the simplified method of closed-form solution, Wang?s equations and Penzien?s equations are used to estimate the applied forces on the tunnel due to earthquake such as axial force and bending moment on a tunnel section taking into account the interaction of the tunnel concrete lining and rock mass. Results of this study show that the loads applied to the tunnel as a result of earthquake waves can be affect the stability of underground structures, especially long structures such as tunnels.

Jan 1, 2011

By Dwayne D. Tannant

Digital photogrammetry allows rapid, remote measurement of millions of points, thus providing an unprecedented amount of spatial information. Research is being conducted to explore practical applications of digital photogrammetry for monitoring, surveying and mapping in surface mines. The performance, accuracy and operational ease of digital photogrammetry are discussed and practical aspects of conducting digital photogrammetry surveys are reviewed. Case histories from coal, diamond and limestone mines are presented.

May 1, 2006

By H. N. Hickey

Wildcat drilling operations in Montana during 1933 did not yield any discoveries of oil or gas that were of major importance. There was comparatively little drilling in the older proven fields, as most of the interest was centered in the Cut Bank field, where 44 wells were completed. The total number of wells completed in the state during the year was 79, of which 62 were productive of either oil or gas.

Jan 1, 1934

By W. Z. Choi

In our previous work, a population balance model describing the simultaneous processes of size reduction and mineral liberation has been developed. The experimental verification of this model, however, has been limited to a binary mineral system containing only one composite particle class. When considering multiple classes of composite particles, the estimation of model parameters becomes much more difficult. In the present work, a procedure for estimating model parameters for a multiple composite class model has been developed. Emphasis is placed on the direct experimental determination of these parameters. The physical significance of the breakage rate function and the liberation function in characterizing the liberation process is also discussed.

Jan 1, 1987

By Winfried Rosenstock

AEBT has been available for a couple of years and is successfully applied in Australia. Up to now it was mainly used in coal surface mining at the Australian East- Coast. Presently, the proved results reach ~ 50 % reduction of Drilling & Blasting costs and a productivity increase of between 10 and 20 %. In 2003 it was for the first time used in surface metal-mining. The mine features for the time being an extremely difficult geological environment and had above to be carried out in the transition level waste/ore. Reductions of wall control, powder factor and vibrations were the main target.

Jan 1, 2004

Delay in classifying the war minerals claims geographically and by minerals' has resulted because a part of the claims is in the hands of the commission which is holding hearings at points easy of access from the mining districts. It was necessary for the commission to take many claims for use at these hearings. Twenty days will be allowed claimants to file typewritten or printed briefs based on the record made by the commission's findings. At the end of twenty days, the case will be finally submitted to the Secretary of the Interior. No new facts will be considered, those which have been submitted to the commission only being given consideration. The Attorney General has issued a decision whereby only such claimants as were directly requested by the government to start operations will receive consideration under the War Minerals Act.

Jan 9, 1919

By E. Bakhtavar

There are many near-surface deposits with considerable vertical extent that have the potential to be mined by a combined method of open-pit and underground methods. In this regard, there is often a point called ?transition depth? where a decision has to be made whether to continue deepening the pit or change to underground methods. Recently, optimization of the transition from open-pit to underground operation has become an important challenge in mining engineering. Optimally, to model the transition problem on the basis of maximization of the profit from open-pit and underground mining, (0-1) integer programming has been used. In this method, block economic values of open-pit and underground methods should be imported to the transition model. A hypothetical example is presented in order to assess the model in detail.

Jan 1, 2012

By G. S. Ospanova

The results of complex processing sulphide copper ore and advantages of recovery of copper by vat and heap leaching, sorption, cementation and electrolytic solutions processing and utilization of waste material after heap leaching of copper for production of building materials were investigated. The combined chemical solvents with the additives of oxidizing agents are developed at the KazNTU. The solvents are inorganic or organic chemical reagents, which form complexes of Cu, Au, Ag, Pt, Ni, Sr, Co etc. Recovery of non-ferrous metals from solutions and purification of industrial waste waters is carried out on the base of using new synthetic and natural sorbents (from local raw materials) which are able to bind ions in both cationic and anionic forms depending on type of ligands and external conditions. Optimum parameters of copper sorption were determined. The developed wasteless technologies of copper extraction from sulphide ores with usage of new non-toxic solvents and accessible sorbents with full recycling of water are tested in pilot scale heap leaching, and are recommended as the ecological, economical and practical alternative to traditional methods.

Jan 1, 2007

Minerals are a fundamental component of the Nation" material and economic base. Without a continuous supply of minerals to meet growing and changing needs, the basic character of our society would be very different. The importance of minerals to the United States was reemphasized by the Congress in I970 when it enacted the Mining and Minerals Policy Act, which stated that it is the continuing policy of the Federal Government in the national interest to foster and encourage private enterprise in (I) the development of economically sound and stable domestic mining, minerals, metal and mineral reclamation industries, (2) the orderly and economic development of domestic mineral resources, reserves, and reclamation of metals and minerals to help assure satisfaction of industrial, security and environmental needs, (3) mining, mineral, and metallurgical research, including the use and recycling of scrap to promote the wise and efficient use of our natural and reclaimable mineral recources, and (4) the study and development of methods for the disposal, control, and reclamation of mineral waste products, and the reclamation of mined land, so as to lessen any adverse impact of mineral extraction and processing upon the physical environment that may result from mining or mineral activities.,.

Jan 1, 1977

By P. Stark, B. S. Lement

ACCORDING to Hanemann1 the hardness of retained austenite in a 1.7 pct C steel is increased by subsequent tempering. He reported that the hardness of this constituent increases only slightly on tempering to 300°F, rises more rapidly above this temperature, and attains the same value as the tempered martensite present in steel at approximately 480°F. The variation of hardness of both retained austenite and martensite with tempering temperature as obtained by Hanemann1 is shown in Fig. 1. Hanemann attributes the increase in hardness of the retained austenite essentially to continued formation of fine needles of martensite on tempering. Although he did not explain the actual mechanism involved, work hardening of retained austenite by the plastic deformation associated with such martensite formation appeared to be a possibility. Recently Lement, Averbach, and Cohen2 reported the existence of subgrains, about l000Å in diameter, in retained austenite and suggested that they may be delineated by a subboundary carbide. This raised the possibility that carbide precipitation might be responsible for the hardening reported by Hanemann. In view of these conflicting possibilities, an investigation" was carried out on a high purity, Fe-C alloy containing 1.7 pct C in order to clarify the nature of the phenomenon involved in the reported hardening of retained austenite. This investigation involved correlation of changes in microhardness and microstructure of the austenite as a result of tempering. Microhardness tests were made with a Tukon tester using a 25 gram load and a Vickers diamond. It was found that two groups of austenite hardness values were obtained after tempering at a series of temperatures up to 450°F, which was the highest temperature at which retained austenite regions could be identified microscopically. One group represents a high hardness level which in-

Jan 1, 1955