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By N. S. Stoloff, R. G. Davis

It is concluded from an X-ray stztdy that the formation of the hcp Mg3Cd superlattice is a nuclea-tion and growth reaction. A two-phase, ordered-plus-disordered, region is observed between 153" nnd 141"C. A maximum in the flow stress is observed both at temperature and in quenched specimens within the two-phase region. The peak arises fro112 the extra energy required to create antiphase boundary upon cutting the ordered regions. Hardening during isothermal annealing in Mg3Cd has been shown to be similar to the domain hardening in Cu3Au-type alloys in that up to the maximum the structure is ordered domains growing into a short range ordered matrix. The hardening is due to a combination of short range order strengthening and the strengthening produced when antiphase boundary has to be created. In a recent study1 of the effect of long-range order upon the mechanical properties and deformation modes of hcp Mg3Cd a comparison was made be- tween quenched (disordered) and slow-cooled (fully ordered) specimens. The most striking observations were that the disordered alloy yields at a much higher stress than the ordered alloy, and that there is a change in slip mode from primarily (_0001) ba_sal slip in the disordered state to (0001), {1010}, {1122}, and {l011} slip in the ordered state. The main purpose of the present work is to extend these observations to determine whether MgsCd exhibits a peak in flow stress at an intermediate degree of order, or at a critical domain size, as do other orderedstems. However, disagreement exists about the Mg3Cd order transformation with respect to: 1) the location of the critical temperature for order, 165°C or 153"~,' and 2) how the degree of order varies with temperature. Welber et a1.5 concluded from specific heat measurements that the formation of Mg3Cd is a second-order reaction with the degree of order a continuous function of temperature, while Moore and Raynor concluded that it is neither a first-order reaction, with the degree of order a discontinuous function of temperature, nor a second-order reaction. Consequently it was considered necessary to undertake an X-ray investigation into the change in degree of order and structure in the

Jan 1, 1964

By J. R. Long, T. R. Graham, C. W. Matthews, R. S. Dean

IN a previous paper§ the authors reported on the mechanical properties of a 65 per cent copper, 10 per cent manganese, 25 per cent zinc alloy as compared with similarly processed cartridge brass. Additional investigations by these laboratories, on higher copper alloys, have demonstrated that at lower zinc concentrations even larger amounts of pure manganese may be added to copper-zinc alloys without exceeding the single-phase solid solution limits, and that similar increases in tensile strength, yield strength, and hardness may be obtained without excessive decreases in ductility. Several compositions in this range showed also a decided color change with increasing manganese. The normal "brassy" color was considerably lightened and reduced to a faint yellow cast at 15 per cent manganese. With higher manganese contents the alloys were essentially white and similar in appearance to the nickel-silver alloys. From this work it appeared that it would be desirable to determine more completely the properties of the wrought and annealed white alloys. Accordingly, a more detailed study was planned of an alloy having the composition 70 per cent copper, 20 per cent manganese, and 10 per cent zinc. This alloy remained single-phase throughout the working and annealing cycles of the preliminary tests and appeared to be about the strongest of the white single-phase alloys. The project included also an investigation of additional alloys, deviating from this composition by 5 per cent of each of the three components to evaluate the effects of variation in composition; also a study of the properties of the central alloy made with silicothermic manganese. MATERIAL PREPARATION Electrolytic manganese, wirebar copper, and electrolytic zinc were used for the preparation of the alloys. Representative analysis of the electrolytic manganese seldom exceeds 0.01 per cent iron, 0.02 per cent sulphur and 0.02 per cent lead, with no silicon or aluminum. A typical sample of the silicothermic manganese metal contained 2 per cent iron, 0.81 per cent silicon, 0.i6 per cent carbon, and 0.36 per cent aluminum. Melting and alloying were performed in a high-frequency furnace with magnesia crucibles. Melts were deoxidized with small aluminum additions and cast into 25-lb. slab ingots. Care was exercised in deoxidation to avoid excessive amounts of residual aluminum, which has been found to have significant effects on alloys in this system. All ingots were hot-rolled at 1200° to 1300°F. and then cold-rolled with intermediate anneal-

Jan 1, 1945

By H. R. Ogden, E. S. Bartlett, A. G. Imgram

Notched and unnotched tensile specimens of wrought and recrystallized, oxygmted and hydro-genated tantalum and columbium were tested over a range of temperatures selected to encompass the ductile-to-brittle transition. Increasing the oxygen content of tantalum and columbium increased their strength, and raised their ductility transition temperature, but did not cause a marked deterioration of notch properties below that of commercially pure material. The adverse effects of oxygen were more pronounced for recrystallized structures than for wrought material. The effects of hydrogen are complicated by strain aging or slow strain rate hydrogen embrittlement at -105°F. However, in general, hydrogen had only a minor effect an strength, but markedly increased the effective transition tem-terature and caused a deterioration of notch properties . BCC metals including the refractory metals in Groups Va and VIa (V, Cb, Ta and Cr, Mo, W) can be expected to undergo a ductile-to-brittle transition and exhibit brittle fractures at low temperatures.' Notch embrittlement is associated with this phenomenon, and can be a serious design problem. Table I compares the tensile transition behavior and notch sensitivity of commercially pure Group Va and VIa refractory metals. The Group VIa refractory metals have considerably higher transition temperatures, and become notch sensitive at higher temperatures, than do the Group Va refractory metals. In addition, the Group VIa refractory metals are sensitive to metallurgical structure. Recrystallized structures generally have higher transition temperatures than wrought material of the same composition. The relatively poor transition behavior of the recrystallized structures of these metals is generally attributed to the segregation of interstitial impurity atoms at grain boundaries. Pronounced sensitivity to structure is not evident with commercially pure Group Va refractory metals, however. Since these metals have higher solubilities for interstitial elements than do the Group VIa metals ,4 it can be expected that higher total interstitial concentrations are necessary to develop a comparable degree of grain boundary segregation and to produce a similar sensitivity of transition temperature to structure. Increasing only the concentration of interstitial atoms in solution would tend to increase the flow stress of a metal in relation to its cleavage fracture stress and thereby raise its transition temperature, but would not be expected to cause a marked sensitivity of transition temperature to structure. A research program has been conducted at the Battelle Memorial Institute to evaluate the effects of interstitial oxygen and hydrogen on the transition behavior and notch sensitivity of tantalum and columbium, and to evaluate the effects of structure on "contaminated" material. EXPERIMENTAL PROCEDURES Notched and unnotched tensile specimens of oxygenated and hydrogenated tantalum and columbium with both wrought and recrystallized structures were tested over a range of temperatures selected to encompass the ductile-to-brittle transition Oxygen levels selected for study in both tantalum and columbium were nominally 500 and 1000 ppm, whereas nominal hydrogen contents were 150 and 500 ppm in tantalum and 150 and 300 ppm in columbium. Oxygen and hydrogen additions were made directly to 6-in. lengths of 1/2-in.-diam electron beam melted wrought bar stock, in a Sieverts Apparatus. Subsequent high-temperature annealing was required for homogenization of the oxygenated material, but was not necessary in the case of hydrogenated stock. The oxygenated and hydrogenated bars were then swaged to 1/4-in.-diam rods. Tensile specimen blanks were cut from the 1/4-in.-diam rods and annealed to achieve stress-re-

Jan 1, 1963

By Granville S. Borden

MANY complaints have been filed by mine prospectors, explorers and producers about inequities in mining taxation. They have insisted upon improvement, and in the past 35 years there has been some progress. Many of the best taxation provisions made to date are those contained in the Revenue Act of 1951. Mining economics presents special problems, a fact even recognized by many textbooks. Certain provisions have been made to take care of mining taxation rights, but these have been made by Congressional act and do not represent basic, constitutional, guarantees. Despite special provision, in the form of depletion allowances, there remain injustices. The industry faces the problem of gaining adequate income tax allowances for exploration and development expenditures, operating losses, and bonus and subsidy payments. Problems in mine taxation arose soon after the adoption of the 16th Amendment. This amendment gave Congress the power to impose income taxes. Supreme Court decisions against a number of mining companies held that Congress, under its power to tax income, could tax net operating revenue before depletion allowance was deducted. The court also ruled that the right to deduct depletion is a matter of Congressional permission. There is no statute provision permitting mining stockholders to recover their investment out of dividends while the mine is being operated. The Supreme Court did not recognize that part of mining proceeds are actually amortization of the cost of mineral rights. Both these omissions stem from failure to recognize that by its very nature mining consumes its mineral rights and therefore that a part of gross proceeds are not income but recovery of capital. Suppose a Congress unfriendly to mining interests repeals the provisions that allow deductions for depletion. Under such a situation assume that a corporation buys a mineral deposit for $300,000. They mine the deposit and earn an operating profit of $500,000. At the current rates they would pay a Federal Income tax of in excess of $250,000. This venture results in a loss of $50,000 as shown in the table below. For the example given the absence of depletion provisions in income tax law would turn ore into waste rock, because the word "ore" connotes commercially mineable rock. [ ] In retrospect the conclusion is clear: If the Supreme Court had recognized that a part of mining proceeds represent in reality sales proceeds of mineral rights, then profits derived from such sales would have been taxed at the favorable long-term capital rates, instead of being taxed at the high normal, surtax and excess profits rates. It is a question whether percentage depletion allowances offset this tax situation. History The history of depletion allowances has been one of general improvement. The original act did not include depletion, but an allowance at the rate of 5 pct of gross proceeds was provided in 1913. The Acts of 1916 and 1917 allowed depletion upon cost of property, and in 1918 the law was further changed to permit depletion upon cost, or market value as of date of discovery. In 1932 metal, coal and sulphur properties were permitted to elect depletion in percentages of gross income, limited to 50 pct of net income, in lieu of cost depletion. Shortly thereafter the rule was changed and percentage depletion is now allowable in any case where it is higher than cost depletion. Since 1942 percentage depletion allowances have been extended to cover many nonmetals, and in 1951 the rate for coal mines was increased from 5 to 10 pct of gross income. It is interesting to note that these allowances have been retained, and even

Jan 1, 1952

By T. R. Ingraham

When aluminum sulfate was decomposed in an evacuated apparatus and the sample cooled, Q alumina was found. The thermodynamics of the decomposition reaction were resolved by measurements of the total pressure of SO3, SO2, and O2 generated over the sample at various temperatures. The results were correlated with other published data to calculate the rmges of thermodynamic stability of the various compounds involved. The thermal decomposition of aluminum sulfate was studied by Wijhler, Pluddeman, and Wöhler1 and by Warner and Ingraham.2 The results of both studies were critically reviewed by Kellogg,3 who observed that "each set of data shows considerable scatter and strong curvature on a plot of log pso3 vs 1/T".3 He agreed with Warner and Ingraham2 that both the discrepancy in the two sets of results and their curvature may arise from the indefinite properties of the particular form of A12O3 which is formed during the decomposition. While studying the thermal stability of other sulfate systems, we had noted the presence of nonequilibrium oxide properties in both the cobalt4 and manganese5 systems, but neither had shown any appreciable curvature on a logPSO, vs 1/T relationship, and the data from both systems agreed reasonably well with prior work. It therefore seemed reasonable to reexamine the technique which had been used in our earlier work on aluminum sulfate.2 The principal difference was that a tightly compacted pellet had been used for the earlier aluminum sulfate work, whereas a loose powder, contained in a platinum boat, was used for our work on other sulfate systems. In addition, a better technique had been developed for dehydrating the samples. From work done on the nickel system,6 we had become aware of the highly protective nature of some sulfate layers on their oxjdes, and hence of the necessity of providing a large surface area of P3e sample when equilibrium was to be attained in a reasonable time. That observation suggested that perhaps a steady state, rather than equilibrium, had been reached in the earlier work on aluminum sulfate. This paper reports a repetition of the experimental work with large, finely divided samples of anhydrous aluminum sulfate. APPARATUS AND PROCEDURE The apparatus used in the experimental work was described in earlier papers.2,7 The source material was Anachemia reagent-grade Al2(sO4)3 - 18H2O which was first partly dehydrated by heating at 400°C for 48 hr and then completely dehydrated by repeated baking of an aluminum sulfate-oleum slush to dryness at 450°C. ? Alas was prepared by decomposing some of the sulfate in a muffle furnace at 800° C overnight. Approximately equal amounts of the 7) alumina and aluminum sulfate were used in the experiments. The finely divided samples were handled under dry box conditions, and in addition some of the aluminum sulfate was decomposed in the apparatus while it was under vacuum, to ensure its complete dehydration prior to sealing the apparatus. The samples were heated to a series of constant temperatures on both increasing- and decreasing-tem-perature programs. Two to three days were required to obtain steady readings of the total decomposition pressure on an increasing-temperature program, and 5 to 6 days on a decreasing-temperature program. Three samples were examined on both programs. Within experimental error, the results for each sample and each program could not be distinguished.

Jan 1, 1969

By Frederik W. de Klerk

INTRODUCTION During the past 40 years, there has been in the United States of America and other industrialised Western countries a distinct displacement in the procurement of minerals from domestic sources towards an increased dependence on imported minerals. This was caused in part by one or each of the following: a lack of local supply of particular minerals, domestic source depletion or exhaustion and the relative ease and inexpensiveness of obtaining minerals from comparatively unexploited sources in underdeveloped and some developing countries, notably in the Middle East, South America, Southern Africa, and Australasia. Governments of the industrialised nations, concerned about the reliance of their economies on imported raw minerals examined both the degree of reliability and the extent of mineral resources in the countries and regions supplying the essential minerals. This brought a painful awareness of the vulnerability of industrialised countries as a result of the possible interruption of their mineral imports. In this regard, the United States of America may be quoted as a case in point: a report by a House of Representatives Subcommittee on Mines and Mining (Santini Subcommittee)1 revealed that the United States in 1980 was dependent on foreign sources for more than 50 per cent for 24 of the 32 minerals essential for national survival. The Subcommittee also acknowledged that although the United States may develop its own alternative energy sources, there are in many cases no substitutes for the strategic + minerals imported from foreign sources, from countries which are often unstable at best, hostile at worst. This resulted in various policy responses as well as contingency measures, amongst other, renewed emphasis on the utilisation of domestic mineral resources, an intensified search for substitutes of critical minerals and increased stockpiling programmes. Increased attention was devoted to analyses of the political and economic conditions prevailing in the regions from which strategic and other minerals are exported to the industrialised countries, and the formulation of policy measures vis-a-vis those regions. One region which attracted a considerable degree of attention has been Southern Africa, and in particular South Africa.2 The Santini Subcommittee affirmed that while the bulk of the minerals imported by the United States is supplied by a number of source countries, a host of critical[t] minerals vital to the well-being of that country (and this includes all the Western industrialised countries) originates from Southern Africa, a region, deservedly referred to as the "Persian Gulf of Minerals". Apart from the Republic of South Africa the mineral-rich countries concerned are Angola (diamonds, iron ore, oil), Botswana (diamonds, coal), South West Africa/Namibia (diamonds, uranium), Zambia (copper, cobalt), Zaire (industrial diamonds, copper, cobalt) and Zimbabwe (gold, nickel, chromium, asbestos). The Subcommittee however noted that, with the exception of cobalt, the greatest portion of the reserves of the critical minerals listed, lies within the borders of South Africa. SOUTH AFRICA A RELIABLE PURVEYOR OF MINERALS In view of the continual instability and political risk, along with the nationalisation of mineral industries in third world countries, importing industrialised nations have in recent years become more and more concerned about security of long-term supply, and have in consequence begun to diversify their mineral enquiries to areas where the following conditions prevail: • Long-standing record of consistency of supply; • An economic system of private enterprise; • Political stability; • A well integrated infrastructure, with a maintenance of transportation and development costs at realistic levels, and • Attractive investment opportunities, with security of the return of profits.

Jan 1, 1982

By Thomas L. Kesler

Lithium raw materials usable with present technology consist of pegmatite ore and shallow evaporite brine. Deposits of these materials occur in many parts of the world. Those advantageously located supply the present lithium industry. Less favorably located deposits will come into production as markets expand and present sources are depleted. In this discussion, materials listed as reserves include fully explored and partly explored deposits. For those closely drilled and assayed, the data provide measurements rather than estimates, and such reserve tonnages are "proved." For deposits partly explored, the data support reserve estimates of "probable" tonnages. Materials lacking exploratory data are classed as resources, and their "possible" tonnages are inferred mostly from indirect evidence and are essentially objectives for exploration. All figures for pegmatite ore apply to total materials in the ground.

Jan 3, 1978

By P. Nicholls

PATENT records show that the attempt to improve the burning of fuel by mixture or pretreatment with chemicals dates back to the early years of the last century. By 1845 English and French patents had included the specific beneficiations of elimination or reduction of smoke, soot and clinker; reduction of the ashes; elimination of sulphur fumes; increase of the rate of burning; increase of the time a given charge of fuel would last; and, in most patents, a saving of fuel. The earlier patents specified additions up to 80 lb. or more per ton of fuel, but after 1860 the quantity was seldom more than 4 lb. There is no record of the extent to which these patents were commercialized, but after 1874 many American patents were assigned to companies specializing in treatment of coal, so it is probable that the products were marketed on a considerable scale at least as early as that date. From 1900 on, many proprietary products were marketed under the general name of "fuel savers," the principal sales being in small packages for the use of householders; savings of from 10 to 40 per cent of the coal were promised. Starting with 1927, the use of proprietary or other mixtures of chemicals was extended to power plants and to treatment of coals at the mines, the claims of saving of fuel being subordinated to those of general improvement and, in particular, to reduction of clinkering. Such expectations are attractive and a number of companies experi-mented with or adopted the practice. There were reports of improved operation, but, apparently, few were confident enough that these improvements were due to the salts to publish the results of tests or their records of operation. There are no data on the yearly tonnage of coal treated but indirect reports suggest that it has been relatively large. Since its establishment in 1910, the U. S. Bureau of Mines has con-tinually received inquiries about these products. At the request of. other governmental departments it made tests in 1910, 1916 and 1930, using certain proprietary products applied according to the instructions of the vendors; these tests were made with eastern coals in domestic and

Jan 1, 1937

By James Aston

THE origin of wrought iron may be taken as coincident with the earliest record of ferrous products. The limitations of primitive methods of manufacture undoubtedly resulted in a material conforming to the general characteristics of what we now classify as wrought iron. Iron has been known from prehistoric times. It is frequently mentioned in Egyptian literature, and some samples in the British Museum are believed to date from 3733 B. C. Iron instruments, tools and weapons were used in Greece in 1400 B. C., and in Assyria and. Italy in 1100 B. C. History records their use in Central and Western Europe in 1000 B. C. And in Styria and Carinthia before the Christian era. The noted Pillar of Delhi is generally assumed to date from 400 A. D. The use of iron was general in Europe in the Roman Empire, and heat treatment of weapons and tools was then practiced. All of this early iron was the result of direct reduction from the ore. It serves to illustrate the ease with which the extraction may be effected, and to point out the well known principle that a malleable product of relatively high purity may be produced from high-grade iron ore at temperatures well below the fusion point of-the metal. The fact is also emphasized that there is no novelty in the seemingly ideal and constantly recurring attempts to effect direct reduction. Economic and engineering considerations have been dominant factors in dictating today's two-step practice in the manufacture of wrought iron and steel. Bear' in mind that all of this history antedated the blast furnace, and a knowledge and use of cast iron. It was only in attempts to get greater output by use of shaft-type furnaces, that cast iron was produced in Germany in the period 1300 to 1400 A. D. This was the result of longer contact with the carbon of the fuel, and higher temperatures in the furnace. This period marked the beginning of the existing two-stage operation, involving as the second step the refining of the. cast iron to a malleable product. For a time this was effected in small hearths not unlike a blacksmith's forge.

Jan 10, 1926

By H. Siebert, G. Raitt

With the advent of the Interstate Highway Pro- gram, many problems have been encountered in the application of highway design standards to topography, particularly rock cut design. A rigid application of slope ratios with little respect to rock type, dip, foliation, structure and height of cut face is a problem. Generally a slope ratio of ½ : 1 or 63º for shallow cuts and 1/3: 1 or 71º in deeper cuts are used in Connecticut. The deepest cut face constructed recently was greater than 185 ft. With cuts of this size, rock fall and stability become a problem, and a way to reduce the problem is to construct a stable face initially. A search of the literature indicates that adequate information on the construction of stable rock slopes is not available. A major highway contract was awarded in 1962 to Savin Brothers, Inc., in which line drilling on 6-in. centers was required in many portions of the contract where the cut was greater than 60 ft and one or more benches were to be constructed. From the start of the project many variations were attempted regarding slope hole spacing and distribution of explosives in the holes. Rock ranged from a competent granitic gneiss to an incompetent soft graphitic schist. Generally, the roadway alignment was roughly normal to the strike of the foliation having a dip of ± 60º. An important factor affecting construction of rock slopes was the existence of intersecting joints and faults. The spacing used in less competent rock was about one ft on center. Loading of holes was purposely varied. As competency of the rock increased, hole spacing was also increased. Thus, on a different project in similar rock, spacing was kept at 4 ft.

Jan 4, 1966

By H. Xi-Lum

Three rapid cold bonding production methods wing sponge iron powder as a binder for low temperature pellets have been successfully developed. These methods differ from ordinary bonding by the elimination of salt and other catalyzers, equipment corrosion and environmental pollution. Experiments show that these pellets have good metallurgical properties. A semi-industrial test has proven the laboratory results, with the continuous and stable production of metallic pellets. These methods replace traditional high temperature firing of oxidized pellets for direct reduction. As a result, the plant for oxidized pellets can be saved and substituted for grate in the grate-kiln system. Thus, 20% of the investment could be saved, and production cost may also be decreased because the production of cold bonding pellets does not need additional space.

Jan 1, 1984

By John F. Abel

The following quotation is from "Guidelines for evaluation of undergraduate curricula in geological engineering, mineral processing, and mining engineering" prepared by the Committee on Education of SME of AIME. "The objectives of the Engineers' Council for Professional Development (ECPD), as delineated in its constitution, are: (a) To promote and advance all phases of engineering education with a view to the promotion of the public welfare through the development of the better educated engineer and engineering technician." (Italics added.) The problem is that no one has as yet seriously developed a method of supplying engineering technicians. There were great hopes that the expansion of junior colleges would help satisfy this need. Sadly, they have not; and it appears they are unwilling or unable to supply the need for mineral engineering technologists. Apparently, the junior colleges cannot afford staff for such courses, even when the colleges are located in mining districts.

Jan 1, 1971

From the cold Pacific waters in June rolls a blanket of white clouds that tucks up around the mountains at around 8000 or 9000 ft. This is the way it happens in southern Peru and so the mining operations and daily living at Toquepala have an ethereal quality not often encountered. Besides looking down on the clouds from the brightly sunlit mountain tops, one can discern the trace of a different era in the brown barren mountain slopes. This trace is like a delicate net laid over the surface of the earth-a criss-crossing of innumerable trails that are so omnipresent, yet faint, that the local people have long since ceased to notice them. It is difficult at first to ask about them because no one understands what you are talking about. It finally comes out though, that the markings are indeed trails, but fossil trails made by animals in times when they were in abundance in a countryside that was green in some bygone century. In a way Toquepala is still pristine, it is the way the engineers planned it-from the ground up. There are no additions or expansions- those tackings-on that spoil the symmetry of design while increasing the profit. This does not deny that annual production has gone up over the years. Daily mill throughput has been increased from 30,000 to 42,000 tpd. Initial design of the concentrator was for 30,000 tpd but in 1964-65 milling capacity was increased to 36,000 tpd at a cost of $3 million.

Jan 11, 1969

The Lornex mine is located in the Highland Valley area of British Columbia, Canada, one of the most,promising districts of low-grade porphyry-type copper mineralization in the world; Lornex is operated by Rio Algom Mines, Limited, a member of the Rio Tinto Zinc Group of London. Exploration from 1965 to 1968 disclosed an ore body of 293 million tons with a grade of 0.43% copper and 0. 14% molybdenum; this led to the decision to construct a 38,000 tpd operation, and production commenced in the fall of 1972. The ore is open-pit mined with 15 cu yd (11 5 m3 shovels, which load 100- and 200 -ton trucks. These trucks dump directly into a 60 in. by 89 in. Allis -Chalmers gyratory from two sides of the 14 ft 6 in. (4.42 m) deep dump pocket and across splitters mounted on the pocket sides. The unlined pocket would hold 1,000 tons level full. The crushedore discharges into a 300-ton surge hopper equipped with an automatic sonic level indicator to prevent over -filling. A 96 in. by 23 ft (2.44 m by 7 m) apron feeder delivers the ore from the surge hopper to a 72 in. (1.83 m) transfer belt equipped with a tramp iron metal detector. The transfer belt discharges to a 60 in. (1. 52 m) conveyor which conveys the ore about 3,000 ft (914 m) to the 475,000 ton ore storage pile located near the concentrator. Four 48 in. (1.22 m) pan feeders transfer the ore to the mill feed conveyors, which in turn supply the two 32 ft by 15 ft (9. 75 m by 4. 57 m) semi-autogenous mills, which easily accept the 10 in. (254 mm) product of the crusher. Each semi- autogenous mill is followed by a secondary ball mill. The unusually large open side setting of the crusher accounts for its 6,300 tph maximum capacity. Concentrator capacity is now 48,000 tpd. Eccentric removal is eased by the design of the door to the crushed ore pocket, which has the cart rails mounted on its outer surface and is lowered to a horizontal position in the pocket by an electric winch. The top of the door rests on wear bar covered concrete piers in the pocket. Another feature is a chute through the floor at the crusher base that extends into the crushed ore pocket. Dust and spills of ore on that floor during crusher repairs are easily swept into the crushed ore pocket. This feature is also used at Bougainville and Palabora and has been added to others after operation has commenced. The design follows the concrete rectangular box concept with four main service and maintenance levels shown in the sectional drawings, although a third additional section has been added at the maintenance

Jan 1, 1978

By Clifford C. Hanninen, Allan H. Caverson

Within the past nine years a means for measuring the distance between mine roof and floor was developed at the White Pine mine which yields relevant information utilized in the mining operation. The technique known as "convergence" is an efficient, low cost way for obtaining large quantities of data for predicting roof falls, caving activity and overall mine stability. Since 1964 the activity of convergence measurements has expanded to become a production tool found in all sections of the mine. The program involves four types of activity: 1) monthly measurements in areas known to be active and in sample blocks scattered throughout the mine for a long-term stability study; 2) semi- monthly measurements along vital travel roads, belt drifts and compressor sites; 3) weekly measurements in areas where men are working; 4) daily measurements in pillar-recovery and caving operations.

Jan 5, 1973

IN the extra-mural service being built up by the Engineer-ing Societies Library as its finances permit, an occasional large total charge is incurred for exceptionally protracted services. A western steel company, for example; was charged the unusual fee of $500. They wanted complete informa-tion on transverse tests of steel, and asked the library to compile copies of all accessible records. Weeks -of search-ing and photoprinting produced three volumes of data. Two years afterward the company's chief engineer told the director of the library that the cost seemed high when the bill was paid but that the volumes had been in constant use. The information had been worth thousands of dollars. A client who wishes to pay no more than a moderate fee for services can state to what limit he is willing to go. Thus he may specify that he would like searches made on a particular subject but that he does not wish to exceed $5 or $30- for the information. The library is as willing to perform a small service as a large one.

Jan 3, 1928

FROM north to south activity is picking up through- out the Labrador Trough-already shown to be one of the world's great iron ore provinces. Center of current activity and interest lies in the mid-southern part of the trough as drills, equipment, and . . . money start to pour into the area near Mt. Wright and Wabush Lake. First major announcement in the area came early this spring when J&L and CCI outlined an estimated billion-ton deposit for "future" operations. Later impetus came from rumored railway for US Steel's Quebec Cartier projects in the Mt. Reed area slightly to the south. As this issue went to press US Steel's request for bids on railway and hydroelectric construction, plus IOCC's decision to step up the time- table on its program in the Wabush Lake area east of Mt. Wright, triggered a flurry of other announcements involving many of the top U. S. and Canadian iron ore firms. Do not look for most of these place names in the average atlas . . . they aren't there yet, but they soon will be.

Jan 6, 1958

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local. Sections should be recognized and stim¬ulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character, of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A . standing Committee on Local Section Appropriations, consisting of one past chairman of a Local Section, one member of the Institute's Executive Committee, and one member of the Finance Committee, shall be appointed by the President and shall pass upon requests for appropriations and authorize payments within bounds of the budget. The committee will be guided by the principles herein outlined, always having in mind the vital importance of healthy, active sections to the welfare of the Institute as a whole.

Jan 1, 1938

By E. V. Foran

The repressuring of oil-producing formations during the flush stage of production, although requiring primarily the same procedure as operations on formations where the gas pressure has been depleted, offers several advantages of major importance, the value of which has not heretofore been demonstrated. It is the purpose of this paper to present an account of some recent operations of this character and the economic effects on the properties where they were applied. The principal objective in all repressuring operations is to secure an effective diffusion of the input energy to all parts of the producing sand. If this can be accomplished, success is assured during the remainder of the life of the property; if not, it will be temporary only and will be followed by difficulties, .and the maximum possible recovery will not be obtained. During the past year in Texas, the Cook pool in Shackelford County, and the Turbeville pool in Archer County, while still in their flush stage of production, have been subjected to repressuring operations to observe their reaction to this process during the early stage of their productive periods. The repressuring operations carried on in each of these pools will be discussed separately in this paper in order to show peculiarities which were present in one pool but were not observed in the other. Turbeville Pool The Turbeville pool is in Archer County, about 30 rniles south of Wichita Falls. The productive sand varies in thickness from 10 to 30 ft., the average being about 16 ft. The depth of the sand varies from 1450 to 1530 ft. The developed productive area to date is approximately 200 acres, but the limits of the pool have not yet been proved. The sand varies considerably in different parts of the pool with respect to both porosity and permeability. The gravity of the oil varies from 39 to 41° A. P. I. There were some wells which flowed for a few days after completion but during 1927 all production was secured by pumping. The

Jan 1, 1928

By A. Bruce Matthews

Of the many opportunities in the mining industry to invest funds to improve operations, there is always some limit in every company as to how much can be spent each year for the acquisition of capital assets. Generally, there are many more opportunities for investment than funds to make the investments. As such, one of management's goals is to select the most profitable of all the opportunities available. Each opportunity must be carefully analyzed for its potential percentage rate of return. This percentage return or return on investment concept is an accepted financial yardstick of business profit- ability. For today's mining engineers, this problem resolves itself in the job of determining how to in- vest most productively the cash that is flowing from their operations so that it will multiply in value. There are four basic types of capital investments: Strategic investments, such as selecting a plant site, are those that affect virtually all long-run plans of a company. Change in a company's product line and expansion of company facilities are two other types of capital investments.

Jan 3, 1963