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By Samuel Daniels

Aluminum-base alloys containing small amounts of copper and magnesium possess but ordinary physical properties as sand cast, but may be treated to give a remarkable range of tensile values and of Brinell hardness. The high-copper (4.5 per cent.) duralumins must be given a protracted treatment which in nature resembles the malleableizing of white cast iron; the low-copper (2.25 per cent.) duralumins develop an excellent combination of strength and ductility with a treatment which requires a maximum of 5 hr. to be completed. THE wrought alloys of aluminum with small amounts of copper and of magnesium have, with the development of the automotive and aircraft industries, sprung into prominence through the medium of duralumin; but the cast alloys remained in the background because their possibilities in the heat-treated condition were either not recognized or not fully investigated. In 1919, the Bureau of Standards published a preliminary survey1 of this field, which pointed out that, in general, the ultimate strength and the percentage of elongation of the alloys of aluminum with and without magnesium could be improved by so simple a treatment as heating to 932° F. (500° C.) for 2 hr., cooling in, air, and aging at room temperature for several days. British investigators, too, working with chill-cast material, found that " considerable improvement in the mechanical properties of copper-aluminum alloys' may be obtained from suitable heat treatment applied to castings."2 Jeffries and Gibson3 made the first contribution to the literature dealing exclusively with the heat treatment of sand-cast aluminum-base alloys, describing the effect of small additions or of combinations of copper, magnesium, and iron on the response to a short heat treatment comprising heating at 932° F. in a

Jan 7, 1924

By J. C. Jaeger, G. A. Wiebols, N. G. W. Cook

It is usual practice in engineering to design a stable structure by ensuring that the stresses in the elements of the structure are always less than their strength, which may be defined as the yield stress, the ultimate stress, or the fatigue stress, according to the type of the load. Such restrictive design is not practical in the design of underground excavations since the rock surrounding such structures is usually failed, but only occasionally does this give rise to instability of the structure. Thus, while the usual criterion for the design of a stable structure is certainly sufficient, it is not necessary for underground excavations. A proper understanding of the conditions necessary for stability is vital to the useful application of rock mechanics knowledge to the design of underground structures. Most tests on the properties and strength of brittle rocks are disrupted at or near maximum load by the rapid release into the specimen of energy stored in the resilience of the testing machine. This is in contrast with a phenomenon, which may be observed frequently, where the rock immediately surrounding an excavation is both failed and subject to stress. By postulating a complete stress-strain curve for rock, it can be shown that failure is unstable or stable, depending upon whether the stress-strain curve of the rock lies inside or outside the stress-strain characteristics of the applied stress. Stability is, therefore, a function of the stiffness of the system applying the stress relative to that of the failing rock. Many workers have established that the strength of rock specimens under a lateral hydrostatic confining stress varies linearly with confining stress, in a way which may be expressed by the equation CT=Co+K[o]3

Jan 1, 1972

By William Fink

ALUMINUM forms not only binary compounds with most of the metallic elements but also forms many ternary or more complex constituents. Several of those occurring in the more important alloy systems have been identified under the microscope and the action of various etching reagents has, been carefully studied.' The determination of the structure and composition of these complex constituents is a matter of some difficulty and little information is available. X-ray crystal analysis offers a promising method for the study of such constituents. First, and of considerable importance, is the possibility of recognizing the presence of a given constituent by means more positive than microscopic observation. Evidence can also be obtained concerning the nature and composition of the constituent in question and ultimately it should be possible, at least in some cases, to describe the structure including the relative locations of the various atoms. In this paper some results of an uncompleted study of the constituents of the aluminum-iron-silicon system are given and the methods employed are described. Inasmuch as iron and silicon are the chief impurities in aluminum, the constitutional relations of this system are of fundamental importance in the metallurgy of pure aluminum and its alloys; the system has been studied by several investigators and the more important contributions have been reviewed recently.2 Fig. 1 shows the structure of the aluminum-rich alloys after prolonged annealing at 560° C., in accord with one of the most recent investigations.3 The ternary alloys examined in the course of the present investigation were all annealed at 550° or 560° C.; in fact, some of the specimens were the identical ones used by Dix and Heath, who kindly supplied them for this work. Since the results

Jan 1, 1930

The explosion of a charge in a drillhole sets the surrounding rock mass into vibrating stress wave motion. Except in the immediate vicinity of the drillhole, the dynamic stresses associated with this motion do damage only to pre-existing joints, cracks, or other weak planes, not to the rock material in between these. The joints are weak in tension, therefore the damage occurs as a result of tensile stresses. The initial damage process in the rock mass that ultimately breaks loose in front of the hole is similar to that in the remaining rock behind the drillhole. Recorded or calculated values of the vibration velocity and frequency contain a wealth of information about the combination of stress and strain that causes the damage. This paper outlines a new technique by which the peak strain energy derived from measured or calculated vibration velocity records is used to determine the local fragment size distribution. It combines two previously known and well tested techniques, namely the Holmberg-Persson calculation of the peak vibration velocity generated by an extended charge and King's calculations of the fragment size distribution as a function of the strain energy in rock crushing. Both of these calculations are based on experimental data and have been tested and found to agree well with actual conditions in their respective fields. Holmberg-Persson's calculated peak vibration velocities have been used successfully to predict and control damage to the remaining rock in cautious blasting, while King's calculation successfully describes the comminution of rock in mechanical crushing. Preliminary predictions of fragmentation in two types of rock blasting, a large hole open pit mining blast and a tunnel round, indicate that the new technique for fragmentation prediction has the potential for predicting fragment size distributions within the rock removed by the Blast.

Jan 1, 1995

CHUQUICAMATA, as the Chile Copper Company's mine is known, has the largest developed deposit of copper ore in the world. Indeed, it is improbable that its equal will ever be found. The Union Miniére du Haut Katanga, operating in the Belgian Congo, may some day surpass Chuquicamata in the total amount of copper produced; or one of the companies developing the rich copper region of Northern Rhodesia may ultimately outdo it. But in each instance, the ore will come from a group of mines separated by 80 miles or more; whereas the deposit at Chuquicamata is one vast integral mass containing as a minimum probably 1,000,000,000 tons of ore, averaging better than 8.5 per cent copper, and as a maximum-well, most any reasonable figure might err on the low side. Utah Copper approaches Chuquicamata more nearly than any other in tonnage of exploitable ore; but Utah's ore is less than half as rich. The figure for the aggregate copper content of the reasonably assured ore at Chuquicamata is breath-taking at 50,000,000,000 pounds. Other distinctions has Chuquicamata: It was the first of the Porphyry Coppers to use leaching as the method of treating the ore; its plant cost for producing is lower than that of any of the others, only Braden and Utah being close rivals; and it was worked for its copper long before any of the others. According to an authentic article published in Ingeniería Internacional (May, v 1982) the Incas smelted copper ores from Chuquicamata prior to 1536. Diego de ALnagro, to whom Charles V, King of Spain, generously allotted a one-fourth portion of South America lying south of Cuzco, the Inca metropolis, made an expedition into Chile in 1534. Better known to history, perhaps, is Pizarro, who was awarded the area immediately north, and who proceeded

Jan 1, 1933

By K. A. Pauly

Compressed air has been and is still very extensively used in connection with mining-operations, but its application in the past has been almost entirely confined to supplying power to underground machinery. Its introduction was due to the difficulty of taking care of the steam which is exhausted underground, rather than to any advantage in efficiency to be gained by its use. The ease with which electric power may be carried to the remotest parts of the mine and the high efficiency of the electric motor have long been appreciated by mine-operators, and electric power is now extensively used underground in the more recent developments, while many of the compressed-air engines in the older workings are being rapidly replaced by electric motors. Recently, however, it has been suggested to use compressed air for driving the large shaft-hoists, the air for the engines being supplied by electrically-driven compressors, and an installation of this character is being erected at Butte, Mont. It is the object of this paper to compare the compressed-air system of hoisting with the various electrical systems, from the stand-points of first-cost and cost of operation. However, before entering into a discussion of the various systems, it will be well to consider briefly the conditions affecting the choice of a system of hoisting in which electricity is the ultimate source of power. The power required by a mine-hoist is extremely intermittent and fluctuates between very wide limits, the all-day average consumption of power not exceeding from 5 to 15 per cent. of the maximum demand during hoisting. The cost of supplying power for such a fluctuating load is necessarily higher than that for supplying an equal amount of

Jan 1, 1912

By E. V. Daveler

The milling plant of the Alaska-Gastineau Mining Co. is located at the town of Thane, Alaska, on Gastineau Channel, 4 mi. south of Juneau and directly across the channel from the Ready Bullion mine of the Treadwell mines on Douglas Island. Previous to the organization of the Alaska-Gastineau Mining Co., in 1912, the milling was done at the stamp mill of the Alaska Perseverance Co. located at the mine in Silver Bow Basin. But the contemplated increase in production made it necessary to locate the mill on Gastineau Channel, as not enough water was available at the mine during the winter months, nor was there room for taking care of the large tonnage of tailings that would ultimately be discarded from the mill. Character of Ore The gold and silver values occur in quartz lenses associated with pyrrhotite, galena, arsenical pyrites, and zinc blende. These lenses occur in large bodies of slate, schist, and metagabbro, which also carry some valuable metallic contents. With the essential low cost of mining, it was necessary to mine large bodies of low-grade material containing the high-grade streaks. Of the minerals, pyrrhotite, the magnetic sulfide of iron, is predominant, and galena is the next sulfide present in quantity. The gold occurs free and coarse and associated with the iron sulfide in its finer state. The silver occurs with the lead or is alloyed with the gold. A chemical analysis of the ore shows Silver............ 0.10 oz. Magnesia......... 0.4 per cent. Silica............. 59.7percent. Sulfur............ 1.2 per cent. Iron.............. 5.2 per cent. Lead............. 0.1 per cent. Alumina.......... 21.4percent. Zinc............. 0.2percent.. Lime............. 5.0 per cent. Experimental Work Investigations at the old Perseverance stamp mill had developed the following points: Roughing concentration following stamping gives a fair recovery.

Jan 1, 1920

By G. C. Gester

With the exception of exploration geological work that is being prosecuted in various parts of the mainland of Arabia, the only new developments in Arabia during 1934 were on Bahrein Island, which is in the southwestern portion of the Persian Gulf, approximately 25 miles from the mainland of Arabia. Here the Standard Oil Co. of California, through its wholly owned subsidiary, The Bahrein Petroleum Co., Limited, has continued to carry on a systematic drilling campaign and has constructed camps, pipe line and marine loading facilities. During 1934 eight wells have been completed at depths ranging from 2058 to 2253 ft. These wells have shown average initial productions ranging from 1500 to 5000 bbl., with one, No. 15, estimated as being capable of flowing as much as 11,000 bbl. per day. The oil is asphaltic in character and has a gravity range of from 32' to 34' A.P.I. The locating of all new wells has followed a plan of orderly development, with the ultimate object of obtaining efficiency of operation and maximum production. The wells are taking a penetration of 200 to 250 ft. of the lower or so-called Main productive zone. The upper oil zone, which is cased off, includes 300 to 400 ft. of alternating limestones, clays and shales and carries a heavier oil under lower pressures. The Main zone is similar lithologically to the upper zone. Micro-fauna collected from cores have shown that the oil occurs in formations of lower Eocene and Cretaceous age. Development to date has not progressed sufficiently so that either the maximum thickness of the oil-bearing horizons or the limits of the field can be determined. Something over 10,000 acres has been proven to date. Among other developments leading toward the marketing of oil from Bahrein during 1934 was the construction of a marine loading terminal. This included the laying of over 3 miles of 12-in. submarine pipe line from the small island of Sitra out into the harbor, terminating in 50 ft. of water; also the laying of more than 10 miles of gathering lines from the producing area to the terminal. Three crude oil working tanks with floating roofs were erected on Sitra Island, having a capacity of 250,000 bbl. A pumping plant was provided having a capacity of 5700 bbl. of oil per hour. This is housed in a dustproof building, as rather severe

Jan 1, 1935

By B. Mienie, J. F. Morrison, C. H. Wyndham, M. J. Martinson, N. B. Strydom

Contribution to discussion M. J. Martinson (Associate Member)*: Application of the simple selection test mentioned in the penultimate paragraph of the paper (reference to a more detailed description of the test would not have been inappropriate) should assist South African mining engineers to make more efficient and possibly more humane use of available labour. The authors mention that the test 'is in use in the gold mining industry', and it would be interesting to know the extent of this usage in terms either of number of mines or as a percentage of the total number of labourers employed on 'heavy' tasks. The paper would have been of greater interest had the authors attempted to relate their findings to the statistics of labour usage in gold mines, members of the Chamber, and to the 'heavy' tasks in particular. On this the authors confine themselves in their Introduction to the somewhat ambiguous statement that 'A relatively high proportion of the 360,000 Bantu mine labourers are employed underground on manual tasks'. To appreciate the practical significance of the authors' work one needs a detailed breakdown of the underground labour force by occupations, together with estimates of quantities such as: (a) total stope and development tonnages moved manually per shift: by shovelling by shovel/tram by tramming together with distances and any other relevant data; (b) theoretical energy expenditures required to accomplish (a); (c) actual energy expenditures required to a accomplish (a); (d) energy theoretically available to accomplish (a) based on 50 per cent of the total maximum oxygen intakes of the labour force allocated to these tasks. Analyses of this sort on an industry basis might demarcate the more promising areas for detailed investigation. Stress is often laid on the need for increased mechanisation to increase stope productivity, but it may be questioned if enough is known about the characteristics, performance and potential of our underground labour force to warrant blind acceptance of stope mechanization as the industry's panacea. Provided that health and safety are not compromised, the ultimate yardstick for assessing any form of stoping is profitability; obviously the industry must investigate very thoroughly any form of mechanization which might reasonably be expected to increase profitability, but it should also be remembered that a radical overhaul of existing systems-which have after all evolved by trial and error over the past 75

Jan 11, 1968

The Malvern Hills coal project is now in an advanced stage of development with the stripping of overburden from above former underground workings in which a 3 m seam of subbituminous C coal with very low ash and sulphur was previously mined. The main seam dips at 45¦ to the south-east, along with other adjacent potentially recoverable thinner seams, and the strike extent of past coal mining in the Malvern Hills approaches 10 km with most extraction by underground methods. Overburden and interburden is predominantly weak mudstone, with only very minor sandstone, whilst a 1 - 2 m thick veneer of Last Glaciation loess covers the area. The coal product from the present mine site will supply the local industrial market, with production planned to peak at about 20 000 tpa. Settling pond design has been based on several different approaches, including an estimate of likely inflows from the contributing catchment of about 5 ha under predicted storms having a ten year recurrence interval. A pond of about 1000 m2 in area has been constructed with its invert in mudstone bedrock, and soil slopes have been lined with lime-stabilised clayey loess silt incorporating a gravel armour layer. The pond outflow takes place via a 2 m high 1.8 m diameter concrete dewatering tower, with a skimmer arrangement to lower the pond by approximately 500 mm between storm events. The overflow water discharges to the main stream above a natural wetland, which will act as a secondary polishing pond, and this is to be enhanced in conjunction with the neighbouring forestry company. Discharge consents specify turbidity and pH as the controlling criteria, and both will be monitored at the settling pond discharge point as well as at the entry to the main stream. Investigations to date indicate that the pH of water exiting from previous underground workings is in the range 6.8 to 7.2, and that acidic drainage will not be an issue with this mine site. No dispersive clays have been identified in assessing the overburden and batter materials, although erosion during storm events is expected and all drains will ultimately be routed through the main settling pond to ensure adequate control of runoff-generated sediment. Reestablishment of vegetation on cut and fill batters remains a priority, and ongoing monitoring will ensure satisfactory long-term performance of the pond system.

Jan 1, 2003

By Christopher Mark, Anthony T. Iannacchione

Falls of ground continue to be one of the most serious causes of injury to U.S. miners. Of the 256 fatal injuries that occurred in mining between 1996 and 1998, 59 (23%) were caused by falls of ground (Table 23.1). Falls of ground affect some sectors of the mining industry more severely than others. For instance, nearly 40% of the 98 coal mine fatalities between 1996 and 1998 were caused by falls of ground. Underground miners are at much greater risk than surface miners. Nearly half (45 out of 101) of underground mine fatalities were attributed to roof, rib, and face falls, while only 6% of the 155 surface fatalities were caused by falls of highwalls or slopes. The goal of this chapter is to provide guidance to safety professionals tasked with preventing ground fall injuries. This chapter combines an analysis of the Mine Safety and Health Administration's (MS HA) accident and injury data with a survey of industry "best practices" to safeguard miners from ground falls. Ultimately, this approach can help to form the basis of a sound, proactive ground control program for the mining industry. SOURCES OF DATA All the injury data examined in this study were derived from MSHA's fatal investigation reports and the MSHA accident database. Because falls of ground often result in serious injury, MSHA "Fatalgrams" and fatal investigation reports provide a useful snapshot of ground control issues in the mining industry. These reports are available to the public (on the M FHA Web site at www.msha.gov). Fatalgrams, are one-page summaries that are usually published within a month of an accident. They contain very basic information about the accident with a graphic and a short section on relevant best practices. Fatal investigation reports are the official accident investigation reports filed by MSHA personnel. These reports contain general information about the mine, a, description of the accident, physical factors involved in the accident, a conclusion, and enforcement actions, Enforcement actions typically identify citations and discuss violations to the Federal Mining Law. MSHA also maintains comprehensive statistical data on the mining industry's accident and injury record. The law requires that mines file a report on every reportable accident that occurs, containing information on the accident's location, severity, classification, activity, and nature of injury A short narrative is generally included as well. Accident reports can be searched by many of the above fields.

By P Stoker

The need for quality assurance and quality control (QA/QC) in the sampling and assaying of minerals is fundamental to the reliability and confidence of a mineral resource estimate, reserve estimate and possibly profitability of a mine. In spite of this, QA/QC practices in the mining industry are commonly applied poorly, or misunderstood. As New Leaders, we should aim to correct the poor practices and become fully informed on appropriate procedures. This paper uses worked examples that show the usefulness and importance of best practice QA/QC procedures. Fundamentals of reviewing the performance of the laboratory by examining the results of client inserted standard reference material (standards), blank material and duplicate samples are discussed. To do this, three examples from Australian data sets have been used. For each example, simple and efficient plotting techniques are suggested with subsequent evaluations of each plot. The first case study compares the results of internal standards from a laboratory with blind standards (where the expected value is unknown to the laboratory) submitted by the client. It was demonstrated over time that the laboratory was unintentionally analysing the internal standards in a different manner to the remainder of the sample batch. In this example, not understanding the cause of a high negative laboratory bias could have led to poor understanding of the depositÆs grade and in the extreme a proposed mining operation may have reached operational stage with a subeconomic grade. The second case study discusses the quality of blank material submitted by a mining operation to monitor cross-contamination within the laboratory. The blank material contained background levels of the element under investigation. This created uncertainty in the assay results, which could have led to the need for additional assays and drilling programs. Finally, the third case study demonstrates the use of the relative paired differences (RPD) technique to cross-validate the results from duplicates and repeat analyses from two laboratories. The three examples given show either laboratory or operational error. If left undetected, each example could have had serious implications for the mineral resource estimate and ultimately, the mining operation. These examples are not isolated occurrences; poor QA/QC practices are an industry wide problem exacerbated by rapid staff turnover and increased contractor positions on-site. New Leaders must be equipped with a thorough grounding in QA/QC best practices to improve its application and confidence in the results of sample analysis.

Jan 1, 2009

By Joseph Fernandez, Luminita Calin

INTRODUCTION The Tunnel and Reservoir Plan (TARP), commonly known as the Deep Tunnel Project, is the daring and unique concept developed by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) as a two-phase solution to the problem of waterway pollution and basement flooding due to sewer system backups created by the combined sewer over-flows (CSOs). Phase I, primarily for pollution control, includes the tunnels, shafts, connecting sewers and structures. These Phase I facilities intercept, during wet weather events, the CSOs within the MWRDGC TARP service area. The tunnels and shafts provide temporary storage of the CSOs for subsequent treatment at Water Reclamation Plants (WRP) before discharging into waterways. Ultimately, upon completion of Phase II, the tunnels, located from 45 m(150 ft) to 100 m (330 ft) below ground, will convey the CSOs to reservoirs for storage until WRP capacity is available. Phase II, which includes the reservoirs, pumping facilities, additional tunnels and shafts, has been planned to serve a dual purpose. The reservoirs provide storage of excess flows during wet weather events, those beyond the WRP capacity. Following the wet weather events, the stored flows can be conveyed, at controlled rates, to the WRPs for full treatment. These excess flows previously would have resulted in both overflows into the waterways and eventually backups in the local sewer systems. The storage capacity of the reservoirs also will promote the full utilization of the conveyance capacity of the tunnels and shafts, which in turn results in optimizing the conveyance capacity of the existing sewer systems. Therefore pollution control is further enhanced by allowing for capture of a greater volume of CSOs and greatly minimizing backups in the local sewer systems. The TARP project consists of four systems: O’Hare, Mainstream, Des Plaines, and Calumet, covering a total area of 971 km2 (375 mi2) and serving the City of Chicago and 51neighboring communities as shown in Figure1. With only two contracts left before completion of the Phase I tunnels, the 12.7km (7.9mi) Torrence Avenue leg, to be awarded in 1997, and the 12.4km (7.7mi) Little Calumet leg unfunded as of yet, both part of the Calumet System, the pollution control phase of the project is now 86% complete (Table 1).

Jan 1, 1997

By J. M. Lovejoy

Tests are described that show that back pressure on flowing wells is a waste rather than a conservation of natural forces. Stop-cocking, however, gives encouraging results. VARIOUS estimates have been made as to the percentage of oil left in a field after the wells have become so small that it is no longer practical to produce them. Engineers have given the matter much study and can substantiate their figures by data taken from fields from the Appalachians to California. The average oil sand has a porosity of about 20 per cent., which gives a capacity per acre-foot of approximately 1500 bbl. The sand thickness in Oklahoma pools averages 20 ft. With 20 per cent. porosity and a 20-ft. sand thickness, the capacity per acre is 30,000 bbl., yet these pools will seldom yield more than 5000 bbl. to the acre. These figures support the theory that at least 50 per cent. of the oil remains in a sand after all known methods to recover it have been used. Certainly we can never recover all the oil, unless in years to come oil becomes so rare and yet so necessary that the price will justify sinking shafts into the abandoned fields and regular mining methods of drifting and stoping. However, with improved methods of production and conservation of the natural agencies of expulsion, we should be able to increase recovery. It is with this in mind that this paper, relating to the effect of back pressure on wells, is presented. Except in the fields where production is caused by hydrostatic pressure, the chief agency for getting, oil out of the sand into the hole is the gas that occurs with the oil. After the pressure has declined, probably gravity also is a factor, but not an important one. With a given amount of oil in a sand and a given amount of gas occurring with the oil, the ratio of gas volume per barrel of oil is the key to the ultimate recovery from that sand. Our efforts should be along lines that will, lower this ratio and make the gas, the agency given us by nature, do its work better and yield more of the oil, of which it is a part.

Jan 1, 1924

By J. Roth

"While not taking issue with the general thesis expressed in Dr. Ridge's analysis of the role of genetic concepts versus observational data in ore exploration (Ridge, 1983), the criticism could be offered that the author tends to slight the importance of conceptual (i.e. theoretical) models in mineral exploration.As a general rule, observational data in science lacks significance and utility without a theoretical construct to organize those observations. Theory in turn dictates what observations are made-and which ones are judged important. Thus, for example, prior to the elaboration-and acceptance- of the current model for volcanogenic base metal deposits, the structural aspect s of these deposits were most closely observed and studied by explorationists. The nature of the enclosing rocks and any attendant alteration was given minimal attention, and certainly didn't figure prominently as an exploration guide.Similarly, the importance of alteration features to exploration for porphyry copper-molybdenum deposits was only perceived when a theoretical model was developed to account for these aspects. Indeed, many of these porphyry copper deposits were regarded as epigenetic vein deposits by geologists of an earlier era observing and examining on a different physical scale-and with a different theoretical bias.In constructing and evaluating such conceptual models, explorationists primarily rely on observation data and proximate associations; speculative thoughts as to ultimate provenance or crustal evolution clearly play a subordinate role, as Dr. Ridge argues. This, however, should not obscure the fact that concepts and theories do indeed exert a major influence in mineral exploration."

Jan 1, 1983

MODERN mining is based on drilling--everything else stems from that. U. S. and Canadian mining companies and suppliers of mining equipment are constantly seeking new techniques and tools for increased drilling efficiency. Ultimate goal is increased bit-against-rock time. Just how important their efforts are can be seen through a legitimate extension of available statistics. In Canada some 70 million ft of drilling per year is required. While the number of feet actually drilled in the U. S. is unknown, it is possible to compare U. S. and Canadian mineral production, excluding oil and coal. In the U. S. mineral value was $4200 million and across the border $836 million. Taking into account the number of drilled feet required to produce Canada's total, the U. S. total would be 365 million ft in 1953. A saving of 14 per ft would reduce over- all metal and nonmetal mining costs some $3.65 million per year. This does not take into account other indirect savings. Methods have changed and there have been structural and metallurgical advances in blasthole practice in the last ten years. The Editors of MINING ENGINEERING in the articles on the following pages present the most significant innovations coupled with results in the field. Environment plays an important role in selection of materials and equipment -but while unanimity does not exist throughout the industry in reference to drilling problems, a definite trend is evident. For the story of that trend read the articles on the following pages.

Jan 9, 1954

By E. M. Wise

THE properties required of gold alloys for jewelry are not well standardized, due in part to problems peculiar to certain branches of the jewelry industry, in part to the individual preference of the fabricator and to his willingness to cope with certain difficulties in manufacture, which arise with the use of certain alloys. GENERAL REQUIREMENTS In general, the properties desired may be classed as follows: 1. Color should conform to the dictates of good taste and smart style. 2. Corrosion resistance and tarnish resistance should be good. This is to a considerable extent determined by the carat. Resistance to such corrosive agents as mercuric chloride as well as certain depilatories is unreasonable to expect and difficult to meet. 3. Strength and hardness must be adequate to maintain the delicate contours of finely modeled jewelry. 4. Wear resistance must be great enough to resist abnormal wear, such as is encountered by a wedding ring in a lifetime of wear. 5. Ductility must be sufficient to permit the fabrication of drawn shells, tubes and difficult shapes. Material having a yield point of not less than 60,000 lb. per sq. in., an ultimate strength of 100,000 lb. per sq. in., and an elongation of 40 per cent. is desirable. 6. Melting point should be between 800° and 1200° C.

Jan 1, 1928

Following the preparation of tantalum oxide and carbide (1) an investigation of the details relating to the production of tantalum metal powder was planned. From the literature (2) it was evident that tantalum could be produced either by reduction of potassium tantalum fluoride with an alkali metal or by electrolysis of a fused salt mixture containing a tantalum compound. The latter method appeared to be the more suitable and, as there was considerable divergence of opinion in the literature as to the nature of the reactions involved, it was decided to study the electrolytic process. The ultimate aim in any case was to produce tantalum pOWder for use in an investigation of the problems relating to the preparation of consolidated tantalum.FACTORS GOVERNING ELECTROLYSISAfter a few preliminary exploratory electrolyses several factors which needed amplification were revealed. These will be mentioned before the details of the electrolysis experiments are given.COMPOSITION OF THE BATHWithout the knowledge gained in the preliminary experiments it would be thought that the best material for the bath would be that one which underwent electrolytic decomposition. Consider what at first appeared the most likely - namely - potassium tantalum fluoride. The melting point of K2TaF7 was determined to be 630°C with volatilization and decomposition taking place at that temperature so that it would not have been very satisfactory.

Jan 1, 1946

By Richard Downs, Stephen P. Burke

The oxidation of pyritic sulphur associated with coal is important for the following reasons: 1. It is the predominant cause for the formation of acid mine drainage issuing from bituminous coal seams. This drainage pollutes the streams in coal regions, making the water unfit for industrial purposes and causing the disappearance of fish and wild life. As a consequence the movement of industry and especially recreational industry, so important to the population of these areas as an alternative means of livelihood, is impeded. 2. It is instrumental in effecting a series of reactions, which bring about the degradation and ultimately result in the spontaneous combustion of bituminous coal in storage. 3. It contributes to the breaking and shattering of the coal structure and is one of the causes of roof falls and floor lifts in mines. 4. It is the primary cause of the many nuisances associated with gob piles and the refuse of cleaning plants. 5. Its proper control and application might possibly be employed in the preparation of coal to reduce the inorganic sulphur content. The research that has been conducted on the oxidation of the various forms of iron sulphides is extensive and the literature voluminous. Nevertheless, few efforts have been made to determine experimentally and with some precision the mechanism of the reaction under the conditions of its occurrence in bituminous coal mines. It has generally been accepted that the oxidation of pyritic sulphur proceeds according to the reaction 2FeS2 + 2H2O + 7O2 ? 2FeSO4 + 2H2SO4 [1] The ferrous sulphate in the drainage streams is further oxidized by air to produce ferric hydroxide and more acid. Yet the literature fails to disclose any pertinent investigation on the mechanism of this reaction. The present contribution is concerned primarily with this aspect of the problem and while the work to be reported is not yet complete, it has yielded results from which interesting and significant conclusions may be drawn.

Jan 1, 1938

By D. L. Katz

In the management of oil properties, it is always desirable to know the future behavior of oil wells and oil reservoirs. Some estimation of the quantity of oil and gas that will be produced must be made as a basis for decisions on possible returns on investments in lifting equipment, drilling of additional wells, and other operating expenditures. In new or wildcat areas, operating expenditures are considered highly speculative, but in the completion of partly drilled and the operation of producing fields it is good business to remove as much speculation as possible. An accurate knowledge of oil and gas reserves in such cases would solve many management problems. The term "oil reserves" usually signifies the future ultimate recovery without specifying the method of production. Thus with changing methods and innovations in the production industry, reserves of any definite reservoir may be increased by increasing the portion of oil recovered. The usual reserve estimates are made by comparisons of well and formation characteristics, by using a percentage recovery on the oil content of the formation volume using porosity data, by extending production curves on non-prorated wells, or by extending bottom-hole pressure-production curves. The most reliable method would appear to be one that would estimate the initial quantity of oil and gas present and then obtain percentage recovery values for various productive methods and formations from experience. It is the purpose of this paper to describe a method of estimating the initial quantity of oil and gas present in a reservoir. The method is based on field operating data and the properties of crude oil-gas mixtures. The principles involved, the data required, the assumptions necessary, and an example of the method will be given. The method is entirely independent of sand volumes and formation porosities. Principles of Method The method of estimating the initial quantity of oil and gas present is based upon the premise that the volume occupied by oil and gas in the reservoir is constant and that a mixture of crude oil and gas will behave in

Jan 1, 1936