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By S. R. Noble, F. R. Harris, E. T. C. Spooner

"The Logtung deposit discovered in 1976, is an example of large tonnage (162 million tonnes), low grade (0.13% WO3 and 0.052% MoS;) W(scheelite)-Mo mineralization related to multiple felsic intrusions. Because mineralization is predominantly fracture-controlled (> 95 %) rather than disseminated, Log tung is not a skarn deposit. Metamorphism of the Logtung country rocks (interbedded calcareous shale and graphitic quartizite) to a series of competent reaction skarns (quartz-diopside-garnet calc-silicate, biotite quartzite and wollastonite-vesuvianite calc-silicate) clearly precedes W-Mo mineralization. Hence mineralization was related to permeability created by hydraulic fracturing and not replacement processes.Logtung shows a theme of several phases of mineralization (4) related to multiple intrusions (>2) which is similar to that of the Climax and Urad-Henderson Mo systems. The earliest quartzmolybdoscheelite vein system, which consists of a typical ""porphyrystyle"" crackle-breccia of thin (0.5 mm to 4 mm) quartz-garnetdiopside- molybdoscheelite veins, is related to a high Si02 (approx. 76%), seriate-porphyritic monzogranite stock (approx. 2 km by 0.5 to 1 km) of Cretaceous age (118 ±2 Ma [2u]; Stewart, 1983). Later quartz-pyrite scheelite (fluorite-KINa-feldspars-molybdenite) veins, with prominent green, hornblende-bearing alteration selvages, and quartz-molybdenite (-pyrite-jluorite-scheelite) veins are related to a quartz-feldspar-spessartine-rich garnet porphyritic felsic dike complex approximately 500 m across. Both intrusive phases have anomalously high Wand Mo concentrations of about 100 ppm and 50 ppm respectively, which Stewart (1983) attributes to a primary enrichment. The final stage of mineralization consists of a prominent 4.5 km by 1 km zone of 1 em to 1 m wide polymetallic sheeted veins centred on the felsic dike complex. The system is zoned from quartz scheelite-molybdenite-pyrite-blue-green beryl-jluoritebismuthinite veins in the core to Pb-Zn-Ag veins with abundant arsenopyrite and minor Sn (approx. 0.1%) in the northeast. The focus of recurrent intrusive and hydrothermal activity was located above a flank or nose of the monzogranite stock.The distribution of WO3 and MoS2 grades within the approximately 750 m (across) by 300m (evaluation depth) mineralized zone is a result of the variable superimposition of the four separate vein systems each with different W:Mo ratios. Well-defined Wand Mo ore, shells such as those at Climax, Henderson and Mt. Emmons did not develop at Logtung. The upper surface of the mineralized zone, as shown by the 0.03% MoS2 contour defines an elongate dome with an apical region approximately coincident with the felsic dike complex. Hydrothermal alteration occurs as well-defined vein selvages, and not as pervasive zones.The Logtung deposit shows many similarities to porphyry Mo deposits in the western Cordillera and may be identified as a porphyry W(scheelite)-Mo deposit, with a W:·Mo ratio of 3.3:1. The principal reasons are: (1) mineralization is spatially associated with porphyritic granitic intrusions and (2) much of the scheelite and molybdenite occurs in typical ""porphyry-style"" vein stockworks"

Jan 1, 1995

By Jr. Hazen

Relationships that may exist between assays and sample interval lengths when using unequal sample intervals in mine sampling have been investigated as part of the larger research problem of adapting statistical methods to the analysis of weighted average grades. The theoretical relationship between the amount of difference in the weighted and unweighted average grade of ore and the size of the correlation coefficient between assay value and sample interval length was found to be linear. Numerous examples of actual field sample and assay data, which have been obtained by using unequal sample intervals, are documented, and the differences between weighted and unweighted average grades of ore and the correlation coefficients between assays and sample interval lengths have been computed and plotted on graphs. Differences between these actual field data and the expected theoretical linear relationship are examined. It is hypothesized that the use of unequal sample intervals in mine sampling is, in fact, stratified sampling in a statistical context. The sampler establishes stratification by selecting unequal sample intervals on the basis of differences in lithology, changes in rock type, characteristics of mineralization, or differences in metal content. Statistically} methods currently used in mine sampling, involving unequal sample intervals, fail to consider differences in the inherent variances in grade of ore within the various strata established by using unequal sample intervals. Consequently the strata are sampled with different precision. This difference in precision of sampling between strata may account for much of the deviation between the plotted points representing actual field sampling data and the theoretical linear relationship between the amount of the difference between weighted and unweighted average grade of ore and the size of correlation coefficient between assays and sample interval lengths.

Jan 1, 1966

By Edwards A. B

Re-opening of the old Proprietary mine has provided new exposures of the system of uralite dolerite dykes observed in 19110 by the Geological Sub-Committee of the Scientific Society of Broken Hill. The newly exposed dykes have been invaded and replaced by the massive ore, with development of manganese garnet and biotite adjacent to the sulphides. A similarly altered dyke in massive ore has been encountered in the North Broken Hill mine.The textures of the unaltered portions of these dykes indicate that they have not been affected by the intense regional metamorphism that has recrystallized the other rocks of the area. Moreover, in mineral composition and textures, in chemical composition, and in cross-cutting relations, they are so similar to the uralite dolerites of the district which post-date the folding and metamorphism of the Broken Hill area, that they must be regarded as typical members of this suite of post-metamorphic dykes.The invasion and replacement of the dykes by the massive sulphide ore, and their metasomatic alteration adjacent to the invading sulphides, establishes that the lode was formed after the dykes were intruded, so that the high temperature features of the ore cannot be attributed to metamorphism and recrystallization, but are primary features of high temperature hydrothermal deposition.INTRODUCTIONTwo cross dykes are recorded on the plan of the 300-ft. level of the Broken Hill lode accompanying the report on the geology of the Broken Hill lode published by the Geological Sub-Committee of the former Scientific Society of Broken Hill (1910). One dyke occurs in Block 12, and the other in Block 13, and both were stated to consist of a dark basic amphibole rock, called diorite for convenience. The more southerly dyke was traced from some distance out in the footwall, and even through the lode, by means of occasionalpatches of it still existing in the ore, in a direction...

Jan 1, 1956

By S. D. Thompson

Conveyor belt haulage has become the preferred mainline transport method in under-ground coal mining, especially for multi-unit mines. Optimum designs for belts (width and speed) and surge bins (placement, capacity, and discharge rate) are necessary for minimizing haulage cost. Two computer simulation models, CMaCS and BELTSIM, available for optimizing these designs are compared. These comparison include: modeling, input data requirements, statistical flexibility, accuracy of simulated loading, and execution time.

Jan 1, 1989

By W. K. Cunningham, Edwin A. Gee

"INTRODUCTION This paper is one of many reporting on various aspects of the Bureau of Mines program during World War II directed toward alleviation of shortages in certain critical minerals some of these papers are published as technical papers information circulars, and reports of investigations, of the Bureau of Mines or in technical journals.The investigation described in this report was begun as part of the Bureau, of Mines program to develop acid processes for the extraction of alumina from low-grade bauxites and clays. A domestic shortage of high-grade bauxite suitable for treatment by the Bayer process became acute as a result of World War II; and intensive search for a practical acid process using lower-grade alumina-bearing raw materials was therefore warranted.A survey of the various methods for extraction of alumina from clay has been presented in an early Bureau of Mines publication. 4/ The principal barrier to the successful operation of an acid process has been the difficulty experienced in developing a suitable commercial method for purifying the crude aluminum salts after the clay extraction is complete. Iron salts are the foremost contamination influence. A review of the more prominent procedures that have been proposed for separating iron and aluminum salts can be found in the well-known text on aluminum by Edwards, Frary, and Jeffries. 5/The majority of acid processes to extract alumina from clay employ sulfuric acid as the leaching agent, and the purification is thus reduced to the separation of iron and aluminum, sulfates."

Feb 1, 1948

By Michael S. Moats, Daniel Kim, Shijie Wang

"The behavior and deportment of lead, arsenic, antimony and bismuth are critical in producing high quality cathode by copper electrorefining. A critical review of research related to these elements is presented along with a comparison to industrial data, where appropriate. These elements exist predominantly in the anode as complex oxides along die grain boundaries. Upon dissolution, Group 15 elements report both to the electrolyte and slimes while lead essentially enters the slimes. The deportment of the Group 15 elements appears to be influenced by several chemical interactions which are discussed. The effect of these elements on floating slimes and anode passivation is reviewed. Under normal electrorefining conditions, lead, antimony and bismuth are thought to enter the cathode through the encapsulation of slime particles. The literature indicates that arsenic enters the cathode predominately by electrolyte entrainment. Finally, areas for future research regarding these elements are presented.IntroductionControlling lead, arsenic, antimony and bismuth is critically important for the production of high quality cathode in copper electrorefining. The reasons for this are twofold. First, ASTM Grade 1 Cathode specifications [1] for these elements are low, as listed in Table 1. Second, they can affect the efficiency of the electrorefining process (e.g., through passivation, current efficiency, slime processing)."

Jan 1, 2012

By Mostafa O. El-Bealy

"To estimate the interdendritic cracking tendency in casting processes, a new model for interdendritic cracking criteria has been proposed. The model combines a concept of the alloying element effect on the interdendritic strain generation and therefore on the susceptibility of interdendritic cracking phenomena. A susceptibility of interdendritic cracking is modeled by using El-Bealy's interdendritic cracking susceptibility function ""BJCSF' and the opening displacement between the dendrites ""EIA "". These concepts are modeled based on the previous experimental observations and ElBealy' approach. The model is implemented numerically for a one-dimensional model problem with some similarities to the casting of steel. The variation of some key parameters that are known to influence the frequency and severity of the interdendritic cracking is then studied.I. INTRODUCTIONInterdendritic cracking ""hot tearing"" commonly encountered in both ferrous and nonferrous castings (1,2]. It is generally believed that interdendritic cracks start to nucleate and develop in the interdendritic strain region within the mushy zone [l-5]. The interdendritic strain region is then definitely coherent, but continuous films of liquid still exit (4,5]. This distinguishes interdendritic cracks from cold cracks forming during the casting process after complete solidification (6,7].Much effort has been put into the understanding of the interdendritic cracking phenomena, and several theories have been proposed. Fellini [8] stated that interdendritic crack ""hot tear"" will result if the material is subjected to too high of accumulated strain within so called vulnerable part of the solidification interval. Kinosita et. al. [9] and Campbell (10] also emphasized the role of tensile stresses in the forming of interdendritic cracks. Most interdendritic cracks criteria simply consider the size of solidification interval, stating that solidification range is associated with a lager interdendritic cracking susceptibility than a short range. Clyne and Davies (11] formulated a more refined such criteria based upon the time spent in different regimes of the solidification interval. They defined a vulnerable region in which thin continuous films of interdendritic liquid exist, and the permeability is low. When thermal strains are induced in this region, the film is not able to sustain the stresses, and an interdendritic crack will form."

Jan 1, 2001

By D. T. McMurray

INTRODUCTION Shabanie mine, situated some 180 km east of Bula¬wayo, has been a producer of chrysotile asbestos for more than 50 years. The ore bodies occur in serpentinized dunite, which overlies talc-carbonate schist. A zone of relatively competent rock of varying thickness occurs between the schist and the ore bodies, which are gen¬erally less competent. The hanging wall of the ore bodies is economic, and the hanging-wall serpentine carries a variable subeconomic amount of fiber. It is important to note that, in general, the ore body competence is less than that of the foot and hanging-wall formations. Historical After surface operations ceased, cut-and-fill stoping was used to win ore from underground; this was success¬ful until the increasingly stoped-out area caused insta¬bility in the stope pillars and back. Consequently, dur¬ing the early 1950s, a gradual change to cave-mining methods was made, the ore being won by hand lashing in drawpoints, situated in the basement of the stope blocks, and passed through orepasses under gravity to the haulage level some 13 m below. About this time, interest was focused on the sub¬level caving method in use in Swedish iron ore mines: it was felt that it might be applied economically to the Shabanie ore bodies. Accordingly, in 1958, an experi¬mental stope block was laid out in which sublevel inter¬vals and extraction tunnel spacing were 9 m. The tun¬nels (ring drilling drives) were oriented on strike-in contrast to the Swedish system, in which crosscuts that retreat from hanging to footwall are used. The advantages of the method were quickly appre¬ciated by the operating personnel and, despite the in¬evitable teething troubles pertaining to the introduction of any new mining method, it was not long before sub¬level caving was providing a high proportion of the mill feed. The disadvantages also became apparent at an early stage, however, and, from that time to the present, continuing modifications have been made to mining lay¬outs in an effort to improve ore recovery. GENERAL DESCRIPTION OF METHOD The mine is served by a vertical hoisting shaft, in which two skips, a man cage and a service cage, provide adequate capacity for production requirements. The rock hoist is a Ward Leonard control hoist, in which two electric motors drive a common gearbox. The man winder is driven by an a-c motor. Several auxiliary shafts provide secondary egress and intake and return ventilation. Main haulage levels are above (Fig. I a and b). Blasthole fan patterns are drilled by drifters of 100 mm bore, drilling 41-mm holes; when a sufficient strike length has been drilled, a slot is cut in the upper¬most sublevel and the rings are broken into the slot. Initially, a limited tonnage is drawn, since it is essential to ensure that the hanging wall caves behind the retreat¬ing stope face. Once this has been established, maxi¬mum tonnage can be drawn, as described later in this chapter, under the heading "Draw Control." The broken rock is loaded by 0.14 and 0.20-m3 load¬ers into cocopans (rocker-dumping type of tipping truck), which are hand trammed to orepasses, discharg¬ing on the haulage where 11-t electric trolley locomo¬tives haul 3.95-m3 Granby cars to the main shaft bins. As is evident from Fig. 1, the layout is simple, the block is brought rapidly into production, there is a high degree of selectivity and flexibility, and the result is a low-cost high-productivity mining method. DEVELOPMENT Main haulages are developed at 3.2 x 3.2 m, and once the service winze connections have been completed the development of the sublevels is undertaken. The footwall drives are cut first, to obtain access to the block. These ends are of the standard section, 2.4 x 2.8 m, and from them crosscuts at intervals of 70 m are driven through the ore body to the hanging wall. These crosscuts are used to supplement the geo¬logical information previously obtained from diamond core drilling, and they provide additional and more de¬tailed data on fiber percentages and lengths, structural features, and other relevant criteria which are used to build up the geological assessment of the area and to classify it in terms of the geomechanics rock classification (Laubscher and Taylor, 1977). The crosscuts also allow the necessary orepasses to be sited conveniently so that tramming distances from the loading points are not excessive. Development Drilling Once the skeleton development has been completed, the extraction headings are developed at 2.4 x 2.4 m as shown in Fig. 1. Standard development practice is to use crews of a machine operator and his helper, equipped with air-leg mounted jackhammers, to drill rounds of 1.8 m with integral tungsten carbide tipped drill steel. The round drilled is a normal drag round, as shown in Fig. 2, but considerable attention is paid to the drilling of the perimeter holes to use effectively the

Jan 1, 1982

By Bill Shand

"Placer Dome - Campbell Mine is a gold mine located at Balmertown in the Red Lake District of North Western Ontario. During the last 50 years, the mine has produced over ten million ounces of gold.A change in ball mill grinding media was made in August 1998 from 1.5” diameter forged balls to 1.5” diameter, 18% chrome balls. This was done to reduce grinding media consumption and to potentially help flotation performance.A marked ball test done in September-October 1999 showed that, of the alloys tested, 18% chrome was the optimum for the ore at Campbell Mine. The test showed that consumption of chrome balls should be 3 times less than forged balls.In December 1999, the ball size was increased from 1.5” to 2” in an effort to reduce the amount of oversize rock discharging from the ball mill. This change in size was successful.Grinding media consumption for the ball mill decreased 73% from 1.20 kg/tonne before the use of chrome balls to 0.327 kg/tonne after the use of chrome balls. This clearly indicates that, for the ore at Campbell Mine, there is significant savings in grinding media by using chrome.Grinding ball costs were reduced by 59% from $O.88/tonne of ore milled to $0.36/tonne of ore milled representing a saving of $298,000 per year. This also clearly indicates that using chrome balls is a benefit at Campbell Mine.Test work to show that chrome grinding media is beneficial to flotation has been inconclusive so far but is still ongoing.No tests have been done to see if there would be a benefit with an even higher chrome percentage in the grinding media. Test work in this area is also planned for the future"

Jan 1, 2001

The Bureau of Mines has successfully used sulfur hexafluoride (SF6) as a tracer gas to measure mine air flows under conditions where conventional methods have failed. SF6 was employed experimentally to measure accurately recirculation of return into intake air caused by leakage through an old stoped area, to check for potential leakage from an adjacent mine, to trace 10,000 cfm of "lost" air from an intake airway, and to measure transit air time through uranium mines. It proved useful as a means of accurately measuring airflow volumes in airways of large cross section and very low flow velocity, and in determining the recirculation resulting from underground cooling plants.

Jan 1, 1974

By J. R. Donald

"Project development has been increasingly formalized in the past decade, with most organizations having extensive and descriptive deliverables documents and processes to govern the stage gate progress of capital projects. Although this has improved the general governance of capital project development and execution, it has perhaps not led to improved business success. This paper identifies specific challenges associated with developing complex projects with multiple stakeholder interests over the long timeframe of the project life cycle. The paper outlines these challenges and suggests management approaches and aspects of project development where increased focus is required to achieve improved business outcomes."

Jan 1, 2015

Not many accounts of mining methods or labor conditions in the mines in early days can be found; all that have seemed to be authentic have been included in the preceding chapters. In practically every field opened before 18.10 the first coal was recovered by quarrying, or strip mining, the operations, of course, being by hand and on a very small scale; new places were opened as soon as mining became difficult or expensive. Where it became necessary to drift into the hillsides, the first coal was taken out by sleds, and later by small wagons, the power being supplied by the miner, often assisted by dogs. Wooden rails then came into use with small cars running on them. These cars were very small, usually holding only a few bushels; in the Belleville, Illinois field as late as 1863 cars having capacities of 10, 12, 14 and some as large as 30 bushels were in use. It was not until late in the 1830's that horses or mules came into use for haulage purposes in the Pittsburgh region, although some had been used in the Richmond, Virginia field at an earlier date. Coal was usually undercut by hand and wedged down, until explosives came into general use, and in nearly every field the coal was forked into the cars, the fine coal, or slack, being left in the mine. Hours worked were very long, but few records remain to show what they were at different places and times; there was undoubtedly a great variation between districts and mines. Roy stated a miner could often produce 5 or 6 tons in a day of 8 or 9 hours in a 5 or 6 foot seam, but in another seam possibly could mine only 3 1/2 to 4 tons. He estimated an average day's work in a four foot seam at about 3 1/2 tons.1 In a strike in the Belleville field in 1863 it was found that an average skilled miner in the field could probably produce 4 to 5 tons a day.2 This was only the coarse coal loaded and did not include slack. In 1873, a coal undercutting machine was tried at a mine about two miles from Brazil, Indiana, said to be the first coal machine ever invented in the United States. It was run by a 5 H.P. steam engine (later to be changed to compressed air), and consisted of an iron rim, four feet in diameter with movable steel teeth placed about one foot apart. The rim

Jan 1, 1942

By Max Hebgen

I. Natural Features of State Affecting Power Development .. 792 II. Early Developments. 1. Big Hole Plant................. 792 2. Canyon Feny Plant............... 793 3. Madison Plant No. 1............... 593 4. Black Eagle Plant................ 795 III. Later Developments. 1. Madison River System .............. 795 2. Missouri River System.............. 797 3. Great Falls System............... 797 4. Missoula River Development............ 797 5. Big Fork Development.............. 802 $ IV. Present Capacity of Power Developments....... 802 V. Transmission System...............: . 802 VI. Character of Load. 1. Lighting and Small Power Uses........... 804 2. Street Railways ................ 804 3. Mining................... 804 4. Railroads.................... 808 5. Irrigation................... 810 VII. Operation of System................. 812 VIII. Increase in Use of Power............... 811 IX. New Power Developments............... 814 X. Undeveloped Powers................. 815 It is estimated that the total stationary power now used in the United States. steam. water and gas. is probably over 30.000.000 h. p. The total developed water power is about 6.000.000 h. p. The water power in the United States now economically capable of development probably exceeds 25.000.000 h. p. The total developed and undeveloped power is

Jan 1, 1914

By V. K. Risinggård, M. Sparta

We report on the development of a finite-element method model for a pilot furnace for the production of manganese alloys. The model is a multiphysics model that addresses material flow, electrical conditions, heat transfer, and physical and chemical transformations. It is capable of studying both quasi-steady and transient states in time-dependent simulations. The model includes common charge materials and fluxes and can simulate production of both ferromanganese and silicomanganese alloys with acid and basic slags, as well as changing charge compositions. The model output provides access to the material distribution in the furnace during furnace runs, temperature profiles, current paths, energy balances, and alloy and slag production rates and compositions.

Apr 16, 2024

By Norihiro Murayama

Syntheses of zeolitic materials were carried out from coal fly ash by alkali hydrothermal treatment as part of the reuse and recycle technologies of coal ash, For the obtained zeolites, the cation exchange capacity and acid resistance, which are very important in the practical use of cation exchanger in aqueous solution, are investigated during this stufY, The cation exchange amounts of the NaP, CaP and K-CHA zeolites are measured for various cations such as K+, Na +, NH4+ Ca2+, Mg2+, Pb2+, Cd2+ and so on. The change in crystallization degree are researched as a function of pH. The simultaneous removal ability of NH4+ and PO43- in solution is examined for an example of the water purification with CaP zeolite. From these results, the characteristic and its mechanism of cation exchange are clarified for the various zeolitic materials obtained from coal fly ash.

Jan 1, 2003

By I. H. Van Horn

IN the development of the incandescent electric lamp one aim of the investigators has been to establish the fundamentals of lamp design, so that the performance of any new lamp may be accurately predicted. The study of the temperature relations in lamps has done much toward establishing these fundamentals. Fig. 1 gives the typical FIG. 1.-ARRANGEMENT OF PARTS IN MAZDA B AND MAZDA C LAMPS. arrangement of the lamp parts in both the Mazda B (vacuum) and Mazda C (gas-filled) lamps. The outstanding differences are the filament form and the bulb shape. The ideal lamp is one in which the filament operates at a uniform temperature throughout its length. In practice, it is necessary to disturb this uniformity by the introduction of supports and terminals. The amount of cooling at the supports and terminals affects the over-all efficiency of the filament as a light producer. The life of the lamp is ordinarily proportional to the maximum and not to the average filament temperature. The Holborn-Kurlbaum type of optical pyrometer has

Jan 9, 1919

By H. D. Pallister

A review of? reports and literature on the pyrite deposits at Pyriton, Ala., indicated that a large tonnage of pyrite, some of which contained a small amount of copper, had been mined and shipped to fertilizer plants throughout the South. The information contained in this literature tended to demonstrate that the ore occurred in separate lenses of greater or less extent and of varying thickness and richness in pyrite as well as in copper. The outcrop being parallel with the Atlantic Coastline Railroad and just south of it makes the deposits readily accessible for shipment. Slopes could be sunk as they were in the past in the ore body if it were of sufficient grade and thickness, and the ore could be hoisted up the slope and milled close to the slope mouth with an ample supply of water from Talladega Creek, which follows the outcrop closely.

Jan 1, 1949

By Breno Totti Maia

In the present paper, a new energy balance equation was developed, considering the slag phase, in order to define the effects of jet penetration and determine a new value for the factor K. The factor K measure the resistance to momentum transference between exit nozzle and metallic bath. The experiments were performed based on the same conditions of the article used as a comparison. The results showed the same behavior between the experiments and it was possible to determine a new value for the factor K, which changed from the unit order for the metal phase system to hundredths order for the metal and slag phase systems. These results are considered unprecedented.

Aug 17, 2017

By Barnabas Bryan

During the boom period of 1928 and 1929, several oil companies took advantage of high security prices to sell stocks, thereby securing money for the company very cheaply. Few if any of those companies realized that the money received was not at all cheap in view of the fact that it was for investment in fixed assets at inflated prices. Suppose a company borrowed twenty millions of dollars to expand its marketing facilities during the boom. It diluted its capital and acquired fixed property which could not earn its interest requirements during the following deflation and therefore consumed income from other company activities. The company also had to stand the deflation in the capital value of all the property it bought. Since the mistaken expansion during the boom accelerated the decline in net income during deflation, the financial position of the company was harmed in proportion to the amount of that expansion. Thus the company was unable to get money to buy fixed assets in the depression when all property is cheap. The same condition holds for the company that sold common stock for the purpose of developing potential production in a newly discovered oil field. Regardless of what the ultimate value of the new field may be, potential production does not increase the net income of the company. The difficulty of meeting the enlarged dividend requirements due to the increased number of shares outstanding impairs the financial position of the company during deflation in some relation to the probability of decreased dividends. This company also is not in a position to expand during the depression when properties and companies can be bought for a fraction of their real value. Expansion of fixed assets during boom times has been the ruin of many otherwise good companies. Some of those which most extensively bought property during the post-war boom have not yet recovered. A number of cases could be cited in sugar, leather, fertilizer and wool. This does not seem to be governed by the quality of the property bought, for examination shows the assets to have been of individual high quality in many cases. When recovery is long deferred it is likely to be true, as in sugar or textiles, that the industry has a large "potential" capacity for overproduction.

Jan 1, 1931

By P. M. Pettit

Hydrologic investigations at Gold Quarry began in 1989 and continued through 1991. Hydro-stratigraphic units include Tertiary sedimentary rocks, Paleozoic siltstones and carbonates. These units display complex and variable aquifer parameters as a function of faulting and hydrothermal alteration, creating compartmentalized hydrologic domains. Testing has included step-tests, spinner production logs and constant discharge tests. Two Three-Dimensional Finite Element Models have been developed, one for optimizing the pit dewatering system and the second for predicting regional impacts of dewatering. Aquifer testing and long term pumping have been used to calibrate both Finite Element Models.

Jan 1, 1992