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By E. Tulcanaza

The practical significance of the in situ grade variability is usually neglected. Although recognized, often times it is either ignored or just considered as a vague guideline in many of the decisions dealing with exploration, reserve estimation, and mine planning. This paper stresses the significance of grade variability for exploration and mining, and illustrates its liaison to the structural features of the ore deposits, as well as to the mining parameters used for mine extraction. Some geostatistical results obtained from a silver mine, tungsten mine, and copper mine in South America are discussed.

Jan 1, 1985

By S. Ito, Y. Watanabe

In the long range production planning at the Matsumine mine, a management target is to maintain a desired production rate and to keep fluctuations in copper and zinc grades within given allowable limits. A simulation model was developed to find, on a trial and error basis, how feasible and practical the target may be under certain constraints on the underground mining sequence. A number of simulation runs have been made to obtain the most suitable production rate for the long term. In this paper, an outline of the simulation model is described.

Jan 1, 1976

By O. W. Walvoord

Mill design of the past will not necessarily dictate mill design of the future. There have been many advances and changes in the last few decades, many of which have been extensive and remarkable. Almost certainly, there will be still greater changes in the near future. Minerals beneficiation, for example, as it relates to future mill design, is likely to experience the greatest progress. Gravity separation, though one of the older arts, is in a continuous state of refinement. Flotation, having celebrated its 50th anniversary in 1961, has yet to be surpassed in its contribution to the art of mineral dressing. Ion-exchange, too, will flourish.

Jan 1, 1971

By Frank Firmstone

Discussion of the paper of John B. Dilworth, presented at the Pittsburg meeting, March, 1910, and printed in Bulletin No. 35, November, 1909, pp. 1041 to 1043. FRANK FIRMSTONE, Easton, Pa. (communication to the Secretary*) :-Mr. Dilworth's formulas and tables are of course correct, and the extinction will occur as calculated, provided the money periodically set aside for sinking-fund be really invested. and the interest compounded as assumed in the calculation. Actually, in almost all cases, such funds are used "in the business," in which case, in addition to the periodical charges for principal of the fund, additional charges must be made at the end of each period to cover the interest and compound interest on previous charges. The periodical charge for sinking-fund thus becomes a varying and continually increasing one until the date of extinction. On many accounts it seems more natural and convenient to make the extinction by a fixed periodical charge under the legal rule for partial payments, namely, that each payment should apply first to the interest due at the date of payment;: and any remainder, after this is satisfied, be deducted from the principal before the interest for the next period is calculated. The formula below is convenient for such calculations S, Principal to be extinguished. Q, Periodical payment or charge for sinking-fund. B, Balance unpaid at date of nth payment, but before that payment is made. r, Rate of interest per period per cent. n, Number of payments or periods. Then, B=S(1+r)n-Q(1+ r)n-(1+r) Received July 27, 1910.

Apr 1, 1911

By Richard S. McCaffery

A Research on iron blast-furnace slags has been in progress since 1922 in the metallurgical department of the University of Wisconsin, supplemented by observations, tests and critical examination of operating records at 10 furnaces. From the data thus collected information has been put into forms suitable for use by furnace operators and is given in this report and the three accompanying papers.' In the viscosity results reported, it is estimated that temperatures were measured within 5" C. and that the viscosity determination of the particular slag investigated is accurate within ± 4 per cent. In the viscosity diagrams in the various papers, the equal viscosity lines were drawn in such a manner that in all cases they are located correctly with respect to the actual experimental results, but when determining a viscosity for a particular composition from the diagrams, the viscosity may. be slightly less accurate than the experimentally determined viscosity for the same slag, for the reason that the iso-vis lines interpolated between the experimental results may be shifted slightly without violation of the experimental data. The viscosity diagrams represent our judgment of their position under the above conditions, and we believe the relative accuracy of viscosity data taken from the diagrams is more than sufficient for any use to which the data may be put. Hundreds of samples of slags synthetically produced in the laboratory and of actual furnace slags have been studied in various ways. The ranges of compositions of slags used for viscosity measurements are: silica 25 to 55 per cent.; alumina 0 to 35 per cent.; lime 25 to 55 per cent.; magnesia 0 to 20 per cent. These measurements were made at temperatures of 1250°, 1300°, 1350°, 1400°, 1450°, 1500°, 1550°, 1600" and 1650" Centigrade. Descriptions of apparatus, methods used and statements of the problems investigated have been published in the papers listed in the bibliography beginning on page 120.

Jan 1, 1932

C. H. WILSON,* New York, N. Y. (written discussion?).-On page 2680, under the heading Junction Box and Zone Box, the authors say, with reference to the zone-box principle of connections between primary couple, compensator couple, and copper leads, which method in its appli-cation to a single couple is shown in Fig. 34, that if this principle is adopted for a multiple installation, so as to save compensating leads; a selective switch may be (and the inference is that it must be) inserted between the zone box and the different couples, putting the switch at an inconvenient point, or putting up with some complicated interlacing of connections.. Wilson-Maeulen Co. has employed the zone-box method extensively for several years and in none of the many multiple installa-tions has either of those alternatives been resorted to. Instead there has been used a method of wiring with the switch at the indicator and involv-ing no more complications than the junction-box method shown III

Jan 11, 1919

By H. L. James

THIS paper presents the results and analysis of field trials of various magnetic instruments over anomalies ranging from 20 to 5000 gammas of vertical intensity. The following instruments were used: Askania vertical magnetometer, Wolfson vertical magnetometer (model M-I), Hotchkiss Superdips (used both parallel to and normal to the magnetic meridian, with several settings of the "sigma" angle), Lake Superior dip needle, and the dipping circle for measurements of inclination. The change in inclination over the measured anomalies ranged up to 4°; this caused pronounced changes in sensitivity of the Hotchkiss Superdip oriented parallel to the magnetic meridian. The variable sensitivity not only gives apparent displacement of crests of anomalies, particularly at high sensitivities, but also makes the data difficult or impossible to use in preparation of iso-anomaly maps. This weakness in field performance of the Superdip is shown to be eliminated by orienting the instrument normal to the magnetic meridian and measuring vertical intensity only, which in the latitude of upper Michigan is equal to 97 pct of the total intensity. The dip needle is seen to be relatively ineffectual for location of anomalies of less than 400 gammas.

Jan 1, 1947

By H. C. Juvkam-Wold

The aquifer depressurization system uses a number of wells surrounding a mine shaft to reduce the aquifer pressure in the vicinity of the shaft. The effect of various parameters such as number of wells, wellbore diameter, time, and well location is discussed. It is concluded that, with a properly designed depressurization system, the aquifer pressure and the water inflow rate to the shaft may be reduced to less than 15% of their potential values in the absence of wells.

Jan 1, 1983

By James R. Garvey

Coal reserves of the United States are enormous. Considered on the basis of proven reserves, and compared with reserves of other fuels, coal constitutes 88% of the proven recoverable energy resources of the nation. That includes oil, natural gas, oil shale and uranium used in burner reactors. Considered on the basis of "ultimate recoverable reserves", that is, those resources which can be extracted with improved technology and at somewhat higher costs and including those resources of all fuels not yet found but believed to be waiting discovery, coal still accounts for 75 % of the national total. In the U.S. hydrocarbon economy about 76% of the total energy needs are supplied by petroleum and natural gas and about 20% by coal. Domestic resources of oil and gas are running dangerously low, and assuming a continued hydrocarbon economy, the 20% supplied by coal may increase dramatically. Nearly a quarter of the petroleum consumed in the U.S. is imported. Natural gas is in shorter supply than petroleum and the problems of its importation seem at least as difficult as those of oil.

Jan 6, 1972

By H. Colijn

Belt scales are frequently used in the mining industry because of the ability to handle large tonnages without interrupting the material flow, fitting easily into all types of bulk handling systems and being relatively inexpensive. Although manufacturers claim weighing accuracies better than Y2%, many operators experience, in practice, much larger errors and they have become apprehensive about the use of belt scales. However, in spite of these disappointing instances, a belt scale is one of the most valuable tools for process and inventory control. Since it is a measuring device, care should be given to the design and installation of belt scales. The basic components of a belt scale are: (1) conveyor belt, (2) scale suspension, (3) sensing device, (4) integrating and recording. The first component of this system is of great importance to the overall accuracy and has been thoroughly discussed in earlier papers. This paper will review primarily the various scale hardware designs currently available, and will be confined to the last three components of the system.

Jan 1, 1973

By William G. Schultz

Sylvite of Canada, a division of Hudson Bay Mining and Smelting Co., operates a new 8500-tpd potash mine ten miles northeast of Rocanville, Sask. This mine, employing less than 60 men in its underground maintenance, engineering, and production operations probably ranks as one of the most highly mechanized and automated mining operations in the world. Access to the flat lying potash bed is through two 16-ft-diam concrete and steel lined shafts 3300 ft deep. The backbone of the operation is two 258-ton, 1500-hp continuous mining machines capable of mining in excess of 700 tph per machine while employing extensible conveyors for haulage. This production capability is complemented by a completely automated haulage, storage, and hoisting system. Of the other unique features of this operation, the principal ones are that the mine was designed and developed by the people that are currently operating it and from the time the shafts were commissioned, the mine was completely developed, equipped, and brought to full production in less than six months.

Jan 1, 1974

Professor Somasundaran has given an excellent presentation of the numerous problems which remain to be solved before the selective aggregation of fine particulates is likely to see broad commercial application in the beneficiation of mineral fines. However it is useful, I think, to reiterate some of the major problem areas. The over-riding factor which has limited the development of selective aggregation techniques is that processes such as coagulation and flocculation tend to be inherently non-selective. Conditions which favor the aggregation of one kind of fine particles usually favor the aggregation of all kinds of particles. As Professor Somasundaran has pointed out, the state of aggregation of a fine-particle dispersion is primarily determined by the forces of interaction between the individual particles. In most systems, the dominant forces are: 1. van der Waals - London Dispersion forces between the particles themselves 2. electrical double layer forces 3. steric forces between adsorbed layers on the surfaces of the particles. The London Dispersion forces between like particles are always attractive, but for dissimilar particles dispersed in a fluid medium can, in some cases, lead to a net repulsion. Electrical double layer forces always lead to repulsion between like particles but can, again, cause either attraction or repulsion for dissimilar materials. The steric forces, which are by far the least understood of the three types, can also lead to attraction or repulsion depending on condi-

Jan 1, 1979

By W. Blaschke, E. Malysa

INTRODUCTION In recent years in Poland, a problem connected with the occurrence of a considerable amount of liberated galena grains in size fractions under 1mm has arisen in the zinc-lead processing area. Operating practices have included crushing of ore particles under 0.2 mm followed by flotation. Jigs were applied to separate the concentrates from size fractions under 10 mm and to prevent the galena overgrinding. However, the fractions being too wide, the jigs have not worked effectively, in spite of the great differences in specific gravities of galena, blende and gangue minerals. Fine galena grains move into light fractions in considerable amounts and hence are overground. Therefore, the flotation becomes difficult and galena is lost in its tailings. These losses could be avoided by introducing separation in the grinding and classification circuits. The amount of 0-1 mm fraction is great; therefore, the application of concentrating tables or other kinds of jigs is impossible from an economic point of view. Taking these factors into account, the possibility of application of pinched-sluices was investigated. These are simple devices without moving parts, they have a high output for the unit areas, and their water and energy consumptions are low. In this paper, the results of zinc-lead ores beneficiation in pinched-sluices are presented.

Jan 1, 1980

By M. W. Bartley, Hugh M. Roberts

SUBSTANTIAL deposits of Bessemer hematite have been found recently by drilling beneath Steep Rock Lake, Ontario, which is situated in the northern part of the Lake Superior Region. It will be practicable to divert the waters flowing into this lake and develop open pits on the upper part of two large ore bodies by damming off and pumping out the water in the part of the lake in which they occur. Ultimately, the bulk of the ore will be mined by underground methods. Owing to the generally massive nature of the rocks in the area, no underground flows of major consequence are anticipated after diversion of the lake. The Steep Rock deposits are attributed in origin to hydrothermal replacement. They were formed, for the most part, along an unconformable, brecciated contact between the Steep Rock limestone and an overlying younger volcanic series. The replacing solutions came in as igneous after-effects, following upon the intrusion of basic igneous rocks that invaded the hanging-wall volcanics. It is believed that this took place in a geological period roughly equivalent to late Middle Huronian, which was the period when the most extensive iron-bearing rocks of the Lake Superior Region were formed. Comparison is made with other deep-seated iron-ore bodies in the Lake Superior Region, the origins of which are ascribed in the discussion to hydrothermal replacement.

Jan 1, 1943

By John G. Koert, Koert D. Burnham, John G. Broughton

Wollastonite in Essex County, New York, occurs as a typical contact mineral in a series of rocks metamorphosed by anorthosite. Sole current use is in various types of electric welding fluxes. Its uniform lathlike shape suggests its use as a specialized filler. Introduction Wollastonite (CaSiO3) was first noted in the vicinity of Willsboro, Essex County, New York, about 1810 by Dr. William Meade, and described from the same locality in 1821 by Lardner Vanuxem.' Recent exploration and development indicate that the deposit is of adequate size for continued exploitation on a larger scale than the present operations. The only other known occurrence of like magnitude in this country is in Kern County, California.* Wollastonite has been reported from Michigan, Pennsylvania, and Lewis County, New York, but these are little more than mineral localities. Geology The Essex County wollastonite has been found outcropping at numerous separate localities in a belt of contact metamorphosed sediments, 1/4 mile wide, which begins 2 miles southwest of the village of Willsboro and trends N. 70" W. for approximately 6 miles (Fig. I). In this belt, the pre-Cambrian Grenville has been injected and partially replaced by the more liquid portions of an anorthositic magma. Bud-dington and Whitcomb3 have described the rock in this contact metamorphosed belt as "Mixed gneisses: Grenville mafic, pyroxenic and garnetiferous gneisses and skarns* with local nearly uniform garnet or pyroxene layers and with gabbroic anorthosite sheets. A few limestone layers." These rocks are underlain, presumably at no great depth, by gabbroic anorthosite gneiss, the typical Whiteface border facies of the Adirondack anorthosite massif. The occurrence of wollastonite in large quantities was discovered during the quarrying of the garnet-rich layer that overlies the wollastonite at one opening. Further prospecting revealed its presence elsewhere in the belt, overlain in most places by the garnet. Accurate tracing of the wollastonite is difficult, owing to the glacial cover and to the fact that the weathered surface of the mineral has a dark, dirty brown color, and that the wollastonite itself has been dissolved more or less completely along the outcrops. It has, however, been noted at 10 localities within the skarn belt in the first 2 1/2 miles from its southeastern end. It has not been found in the northern half of the belt and therefore may be limited to the southern half. At the Fox Hill quarry, which is the main opening, 150 ft. have been exposed, showing an aggregate thickness of 30 to 35 it. Of

Jan 1, 1948

By Koert D. Burnham, John G. Broughton, John G. Koert

Wollastonite in Essex County, New York, occurs as a typical contact mineral in a series of rocks metamorphosed by anorthosite. Sole current use is in various types of electric welding fluxes. Its uniform lathlike shape suggests its use as a specialized filler. Introduction Wollastonite (CaSiO3) was first noted in the vicinity of Willsboro, Essex County, New York, about 1810 by Dr. William Meade, and described from the same locality in 1821 by Lardner Vanuxem.' Recent exploration and development indicate that the deposit is of adequate size for continued exploitation on a larger scale than the present operations. The only other known occurrence of like magnitude in this country is in Kern County, California.* Wollastonite has been reported from Michigan, Pennsylvania, and Lewis County, New York, but these are little more than mineral localities. Geology The Essex County wollastonite has been found outcropping at numerous separate localities in a belt of contact metamorphosed sediments, 1/4 mile wide, which begins 2 miles southwest of the village of Willsboro and trends N. 70" W. for approximately 6 miles (Fig. I). In this belt, the pre-Cambrian Grenville has been injected and partially replaced by the more liquid portions of an anorthositic magma. Bud-dington and Whitcomb3 have described the rock in this contact metamorphosed belt as "Mixed gneisses: Grenville mafic, pyroxenic and garnetiferous gneisses and skarns* with local nearly uniform garnet or pyroxene layers and with gabbroic anorthosite sheets. A few limestone layers." These rocks are underlain, presumably at no great depth, by gabbroic anorthosite gneiss, the typical Whiteface border facies of the Adirondack anorthosite massif. The occurrence of wollastonite in large quantities was discovered during the quarrying of the garnet-rich layer that overlies the wollastonite at one opening. Further prospecting revealed its presence elsewhere in the belt, overlain in most places by the garnet. Accurate tracing of the wollastonite is difficult, owing to the glacial cover and to the fact that the weathered surface of the mineral has a dark, dirty brown color, and that the wollastonite itself has been dissolved more or less completely along the outcrops. It has, however, been noted at 10 localities within the skarn belt in the first 2 1/2 miles from its southeastern end. It has not been found in the northern half of the belt and therefore may be limited to the southern half. At the Fox Hill quarry, which is the main opening, 150 ft. have been exposed, showing an aggregate thickness of 30 to 35 it. Of

Jan 1, 1948

By A. B. Fly

Borehole mining combines the principles of hydraulic mining, slurry mucking and rotary drilling. The borehole is drilled with conventional equipment and is cased down to the top of the mining zone. The borehole mining tool is comprised of the kelly-swivel assembly, multiple drill-pipe sections, and the jet-pump barrel assembly as shown in Fig. 1. The kelly swivel is fitted with a bail to support the mining tool. The kelly drive bushing engages the rotary table to allow the rotation of the mining tool while it is being operated. The jet-pump barrel assembly is comprised of the sidewall jet nozzles, the jet-pump assembly, the suction screen, and the tricone rock bit. Clean fluid is pumped at high pressure through the kelly hose to the high-pressure swivel on the mining tool. The high-pressure pipe conducts the fluid down to the sidewall jet nozzles, the pump jet nozzle, and the tricone rock bit. The sidewall jet streams cut the formation and wash the cuttings down to the rock bit. High-pressure fluid issues from the water courses to clean the bit and to agitate the cuttings. Rotation of the mining tool causes the rock bit to grind any oversize material enough to permit its passage through the suction screen. High- pressure fluid issues from the pump jet nozzle to provide the lift needed to pump the slurry to the surface. The slurry is discharged into the settling pits where the cuttings are deposited and the clean fluid is returned to the suction of the high-pressure pump.

Jan 3, 1969

E. G. SPILSBURY, New York, N. Y.-I would like to ask Mr. Wemple what is the total loss in redistillation; not merely the weight of the lead removed, but also the loss clue to rehandling of a large amount of blue powder, and that clue to the final remelting in the tank furnace? LELAND E. WEMPLE.-The loss of zinc by redistillation, on the first operation, is approximately 5 per cent. This loss does not cover the lead

Jan 4, 1918

MIXED emotions were produced by the announcement that the buildup of weapons will be stretched out till mid-1954 instead of the previous 1953 deadline. Reason: government assistance programs will be tougher to get but there will be easement in materials allocations. Earlier in February, DPA had announced that tightening up on regulations governing rapid tax -amortization would become effective March 1. In the future, DPA will have to certify amortization contracts for all construction and permanent installations costing more than $100,000. This action was necessary according to DPA's James F. King, so that new industrial expansions already approved could be assessed in the light of the changing critical mineral picture. When DMPA inherited the backlog of government assistance, requests from DMA, it moved in fast. The results of DMPA's work is described in the article on p. 351 by James K. Richardson; The speed with which these requests were approved and the lengthening of the military program have made a reappraisal of the critical mineral list necessary. It looks as though the consumer industries will be getting more metal soon and, led by steel, there is an industry push toward the abandonment of CMP. Relaxing of materials controls appears imminent but discontinuing CMP is in the "let's talk this thing over" stage.

Jan 1, 1952

By C. G. Brennecke, R. T. Gallagher

This paper is the result of a research program entered into cooperatively by the General Reinsurance Corporation and Lehigh University in January 1944. The research program was instituted to find a more positive method to determine the presence of hazardous roof conditions in , mining operations. The co-authors, together with Mr. R. D. Currie, Engineer for the General Reinsurance Corporation, started working on the project in January 1944, first undertaking a library search; second, a preliminary study based on some existing equipment; third, the design of new and more suitable equipment; and finally, the field testing of equipment and methods. Purpose Any study of the accident statistics of mining operations will disclose the rather startling fact that approximately 50 to 60 per cent of all fatal underground accidents in the anthracite and bituminous mines are caused by falls of roof and coal, the metal and nonmetal mines showing only a slightly smaller percentage. Advancements in safety engineering have produced definite results in the decrease of accidents due to blasting, haulage, electricity, and explosions but no such decrease is shown in those caused by falls of roof, coal, or ore. Table Il,2 is a compilation of statistics as published by the United States Bureau of Mines, showing the percentages of fatal accidents caused

Jan 1, 1947