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By Alvin F. Kroll

BUNKER Hill & Sullivan Mining & Concentrating Co. has three major sources of ore at present: high grade square-set ore, low grade caving ore, and low grade reclaimed washed jig tailing. These three ores constitute the feed to the 3000-tpd concentrator that produces lead-silver, zinc, and pyrite concentrates. Each ore has different characteristics of grindability, mineral particle size, composition, and content, but all are amenable to the same mill circuit and reagents. The gangue is primarily quartzite. The Bunker Hill concentrator is now using a coarse primary grind followed by a regrind of sand fractions of lead rougher tailing, lead middling, and lead cleaner tailing, and further regrind of sand fractions of zinc middling and zinc cleaner tailing. This is done in order to recover all valuable minerals at the largest size possible. The tendency to overgrind the ore particles, which are more easily ground than the gangue particles, is thereby reduced-lessening their loss in the flotation tailings. The coarse primary grind and regrind method has the advantages of: providing more selective grinding, minimizing sliming, giving a cleaner lead-zinc separation, and reducing mill requirements for reagents and water. Improved lead-zinc separation raises overall recovery and also increases lead and zinc recovery in the respective concentrates by keeping middling particles out of concentrate and tailing.

Jan 6, 1954

By Waldemar Lindgren

Fifteen years ago, in his presidential address before the Washington Academy of Sciences,' Alfred H. Brooks said: "Applied geology can only maintain its present high position by continuing the researches which advance the knowledge of basic principles. Future progress in applied geology depends on progress in pure geology. Early in 1927, Dr. David White, then chairman of the Division of Geology and Geography of the National Research Council, appointed a committee "On the Processes of Ore Deposition," which was the first recognition by the Council of this branch of applied geology. This committee will not be able to solve the many complex problems involved; it can only clear the way, survey the field, state the problems and encourage systematic research. This short paper aims to outline and to analyze the present status of this kind of geological research, to ascertain the quality of the work and to suggest lines that might profitably be followed. Increasing Demand for Geologists Economic geology, or the art of geology, could develop only after the principles of geology and mineralogy had been established. Before that time it was merely a collection of trade rules accompanied by more or less wild speculations. Thus we observe the beginnings of economic geology in the period 1770-1820. Soon afterwards, the State Surveys were established in this country, with the realization that the natural resources should be investigated and described. Geology was hardly yet equal to the task of scientific research in relationships and genesis, however, and there followed a period of discouragement and stagnation. In the meanwhile, pure geology had again registered progress, and, based on its principles and also on the rapid mining development in the Cordilleran region, the present phase of the study of ore deposits began to take form. Raphael Pumpelly, S. F. Emmons and G. F. Becker were among the pioneers in this movement. The United States Geological Survey was organized. Ore deposits were scientifically described and studied along lines of structure and mineralogy; theories of genesis were advanced, not always permanent but based on sound induction.

Jan 1, 1928

By Harvey S. Chase

During the recent great depression in iron, little has been done in the magnetic separation of iron-ores; and previous to the present decade the art was in its infancy, so that there were few, if any, successful separators on the market, and but scanty practical data could be obtained as to the industry itself. Moreover, the recent development of the great Mesabi Bessemer beds, coincident with the intense depression in business, has discouraged active attempts to solve the problems presented in the crushing and separation of the refractory magnetites of the South. Experiments have been carried on, however, upon a practical scale in separating these ores magnetically, at the well-known Cranberry mines, in Mitchell county, N. C., with results which are encouraging. The magnetites of the Blue Ridge, in the South, have been known, and the soft ores of the region have been used in Catalan forges, since very early times. The original settlements in East Tennessee were made along the Watauga river by Daniel Boone, William Bean, John Sevier, and other stalwart pioneers; and this valley lies parallel with the " Cranberry " lead, which is undoubtedly the most celebrated and the most extensive deposit of workable magnetic ore in the Southern States. This lead I have personally traced along the outcrop, be-

Jan 1, 1896

Jan 1, 1891

By Harry R. Cedergren

Properly designed drainage systems can be of great benefit to many kinds of Civil Engineering works, including embankments, and often are the most economical way to protect such works from the damaging effects of water. To function properly, drains must be able to remove water without also removing soil or becoming clogged with soil or erodible rocks. The first criterion to be used in designing drainage systems, called the filter criterion, can prevent all such problems (erosion and clogging) when properly fulfilled in design and construction. The second requirement of drains is that they must be capable of removing all of the incoming water without the build-up of large amounts of head that can damage the protected works. To insure this kind of perfomance, the discharge capabilities of drains should always be verified by appropriate hydraulic and seepage calculations. This paper describes these two basic drain design criteria and also gives examples of application of seepage principles to the evaluation of the potential benefits of drains and to the design of drains for mine waste embankments.

Jan 1, 1985

By M. D. Voegele, C. Fairhurst

INTRODUCTION A computer study of excavation support loads in tunnels and other excavations in discontinuous rock masses was undertaken with the distinct element method introduced by Cundall (1971). In the distinct element method the rock mass is modeled as a composition of individual blocks of rock defined by the joint planes. Normal and shear deformation laws are ascribed to the joint surfaces; the blocks of rock themselves are considered to be rigid. The particular version of the program utilized in this study ran a mini computer and used inter, active techniques for the input of geometrical data such as joint orientation and spacing and subsequent display of rock mass deformation and other data. Two major aspects of the behavior of excavations in jointed rock masses are examined in this paper: i) the behavior of unsupported excavations in rock masses with varying joint configuration, joint properties and in situ stress fields; and ii) the modification of the behavior of similar excavations when support is provided. In the latter case the excavation behavior was examined through the use of ground reaction curves. THE DISTINCT ELEMENT METHOD The Distinct Element method introduced by Cundall (1971) is a computer based analysis that simulates the behavior of a system of discrete, semi-rigid rock blocks. Block interactions are governed by realistic friction and stiffness laws; each block may undergo unlimited displacement and rotation while progressive failure is modeled.

Jan 1, 1982

By F.L. Preshidge

R. B. RATHBUN,* Salt Lake City, Utah (written discussion?).¬While the engineer should carefully weigh the merits of the various types of equipment, he must bear in mind that the object of his plant is the recovery of suspended solids, and a thing is unimportant except as it contributes to this end, other engineering principles being duly considered. The controversy regarding the use of synchronous motor-driven rectifiers by which the power for the treater is taken directly from the mains of the local power system, rather than the motor-generator rectifier giving each treater unit its own isolated electrical system, has led many to think that on the type of rectifier depends the success of .the plant. It is in fact a relatively unimportant part of the plant and represents a very small fraction of the investment; the recoveries in dust and fume are practically the same in each case. One large smelting concern has adopted the motor-generator type for all of its plants after years of experience with the synchronous-motor type. Its reasons are practically the same as those set down by Mr. Eschholz for his preference. Given more in detail they are: 1. An independent electric system prevents outside power-line conditions, like voltage fluctuations, from interfering with the operation of the Cottrell plant and eliminates the possibility of the Cottrell plant causing trouble for the power company. The latter, while not very

Jan 12, 1918

By R. J. Wysor

Discussion of the paper of R. J. WYSOR, presented at the New York meeting, February, 1916, and printed in Bulletin No. 106, October, 1915, pp. 2161 to 2170. LEONARD WALDO, New York, N. Y.-Will Mr. Wysor kindly give us more information as to the pyrometers used and the temperature measurement? R. J. WYSOR, So. Bethlehem, Pa.-We used standard Bristol pyrometers with bare fire ends. These were standardized both before and after the tests with salt and pure aluminum. We also interchanged the pyrometers. J. W. RICHARDS, So. Bethlehem, Pa.-Did you attain any results which gave you approximately the value of the heat insulation at any of the furnaces? R. J. WYSOR.-In the first installation we were afraid to put in the insulation throughout the hot-blast main for the reasons mentioned in the paper, but we used the insulating brick in two 8-ft. sections in straight lengths of our hot-blast mains. Owing to the high conductivity of the steel shell, the temperatures which were taken on the outside were not representative of the two temperatures resulting from heat flow through the insulating brick. I believe that when a hot-blast main is insulated

Jan 5, 1916

By Earl H. Miller, Henry H. Bruhn

COMMERCIAL beds of sylvite ore were discovered by the Snowden & McSweeney Co. while drilling a wildcat oil well some 25 miles northeast of Carlsbad, N. NI., in 1925. After a preliminary core drilling program the U. S. Potash Co. sank a 1060-ft shaft within 4 miles of the original discovery. This shaft was in an isolated location in a sand desert area with only the roughest of dirt roads connecting it with the neigh- boring town of Carlsbad some 21 ½ miles west.

Jan 6, 1954

By J. Gordon Parr, G. R. Purdy

The phase boundaries of "TiNi" have been accurately determined by high-tewperature X-ray diffraction and metallo-graphic techniques. The phase (centered at 51 pct Ni) has a restricted range of homogeneity at 500°C, and a much greater range at 800°C. "TiNi" in all alloys containing less than 51 pct Ni decomposes rapidly and reversibly at 36°C to form a previously unreported phase. ThE region of the titanium nickel system corresponding to the phase "TiNi" has been the subject of several investigations.1,2,4-7 Laves and wallbaum1 reported "TiNi" as a body-centered cubic (a2) Phase, and Duwez and Taylor2 determined its para- meter to be 2.986. Duwez and Taylor also reported that "TiNi" decomposed into "Ti2Ni" and "TiNi3" on prolonged heating at 650" and 800°C, which led McQuillan3 to suggest a sluggish eutectoid reaction between "TiNis" and "Ti2Ni". Margolin, Ence, and Nielsen,' working with higher purity alloys, found no evidence of this decomposition. They showed the "TiNi" phase region extending from 49 to 54 pct*

Jan 1, 1962

By H. E. Lee, P. C. Feddersen

Blast-fuRnace operation at the Bunker Hill smelter deviates somewhat from common practice. Under existing conditions it is economical to operate the furnaces at "forced" capacity. The furnace feed consists chiefly of sinter and averages close to 50 per cent lead. Experience in smelting such material favors a low charge column attended by smaller proportions of coke and a low blast pressure. Under such conditions the gain in furnace tonnage greatly overbalances the somewhat higher slag losses and increased percentage of material fumed Furnace Charge The ingredients for the blast-furnace feed are stored in a group of 24 charge bins (3600 cu. ft. capacity). Each bin has two discharge chutes. Beneath each chute is a steel weighing hopper, suspended from a Fairbanks scale. The several hoppers are kept filled with the exact amount of material required to complete a furnace charge. The weighed material is discharged into a standard-gauge, bottom-dump charge car containing two compartments, each of which holds a complete charge (approximately 1½ tons). It is hauled to the blast furnace by a 44011 electric trolley locomotive. The proportionate parts of the various constituents of a representative blast-furnace charge are shown in Table 1. Table 1.—Representative Blast-furnace Charge at Bunker Hill Smelter Material Pounds Sinter.................................................. 2500 Limerock............................................... 0- 50 Coke................................................. 250-300 Scrap iron.............................................. 0-25 Settler skulls.......................................... 75 Undried zinc-plant residue................................ 0-200 Siliceous ore............................................ 25 Baghouse dust.......................................... 0-50 By-product slag......................................... 100 A variable stock tonnage of zinc-plant residue and return by-products results in fluctuations in the percentages of these materials in the blastfurnace feed. Accompanying such variations are corresponding increases or decreases in the amounts of coke, limerock and scrap iron necessary to obtain good furnace operation and adequate reduction.

Jan 1, 1937

E. T. DUMBLE, Houston, Tex.-This paper is a continuation of one that was published by Mr. Garfias, I believe, in the Journal of Geology, 1912, in which he gave the results of his investigations in Mexico, showing that the basalt extrusions frequently did not come up as cones. but reached the surface as a small neck and then mushroomed out into a sill, penetrating the beds both in limestones and in shales. He has continued his investigations to show that as these basalt protrusions came up they forced the strata into a funnel shape at the top instead of throwing them out altogether. While this may be true concerning these particular beds, there are other places at which the basalt does appear clearly as cones and dories, and there the funnel structure does not exist. We know that the sills are there, because we find them in the wells. In one well that I know of. we found a 2-ft. sill of basalt at about 1600 ft. and oil below it at about 2100 ft.; others have gone through similar beds. We also know that there. are cones, because north of the Ranuco River one well struck basalt at about 800 ft. and continued in it for several hundred feet-did not pass through it at all. This paper of Mr. Garfias will give us considerable help in that oil field. W. E. WRATHER, Wichita Falls, Tex.-I would like to ask for information as to the temperatures of Mexican oils. I have heard a number of conflicting reports about the high temperatures of the water and oil, and the relationship between them.

Jan 1, 1918

By F. Weinberg

INTEREST is currently being directed toward grain boundary morphologies in zinc in terms of grain boundary facetingl and grain boundary energies.' Some years ago the present author attempted to measure grain boundary energies in 99.999 pct purity Zn as a function of boundary angle, using the standard procedure of measuring equilibrium angles of the boundary traces at triple points. This followed an investigation he carried out on preferential melting of |H (112) Fig. 1—Electron transmission micrograph of a stacking fault, grain boundary intersection in copper. GRAIN BOUNDARY STACKING FAULT Fig. 2—Schematic representation of the intersection of Fig. 1, indicating inclination angles 0 and trace angles $. specimens were prepared by the Bollman technique in an electrolyte of 70 pct methanol, 30 pct HNO3 main-tained at -30°C. The interfacial free energy of the high angle grain boundary and of the stacking fault is assumed to be thermodynamically equivalent to the corresponding in-terfacial tensions. In terms of the true dihedral angles & between the intersecting interfaces, the equilibrium of interfacial tensions in the direction parallel to the stacking fault yields: ysF = -ygb(cos F1+ cos ±cosF2) Here, ysF is the stacking fault free energy and ygb is the grain boundary free energy, assumed equal on both sides of the intersection. Forces acting normal to the grain boundary, of the form ??gb/?F,l are assumed negligible as the grain boundary remains straight for a considerable distance on either side of the intersection. The micrograph of Fig. 1 may actually consist of several closely spaced stacking faults on the same slip plane. The actual point of intersection between the grain boundary and the first stacking fault, and the equilibrium configuration of the intersection, should not be affected by the presence of the other faults, as

Jan 1, 1970

By W. V. Kotlensky, H. E. Martens

In an earlier communication, Ref. 1, the authors presented the tensile properties and the changes in crystal structure and microstructure for pyrolytic graphite tested at 2750°C. It was suggested that changes in the structure may have an effect on the tensile properties of this material. Accordingly, tensile tests were run on a series of specimens, from one block of pyrolytic graphite, some of which were hot-worked by being strained at 2750°C, others of which were tested in the as-deposited condition. According to the manufacturer, General Electric Co., the polycrystalline material was deposited at 2100°C on a substrate of synthetic graphite by decomposition of a dilute natural gas mixture. The as-deposited material had a density of approximately 2.19 g per cc, and as shown in Fig. 1 had a structure of medium size growth cones which were regenera-tively nucleated. All specimens had a gage section 0.75 in. long by 0.06 in. wide by 0.1 in. thick with the thickness direction perpendicular to the basal planes. The testing method and equipment used have been previously described, Ref. 2 and 3. For both the hot-working and the testing the load was applied parallel to the basal planes; a cross-head speed of 1.5 x l04 in, per sec was used. All heating was done in an atmosphere of bottled helium.

Jan 1, 1962

Jan 1, 1947

By Rudolf Kudlich

THE problem of eliminating the hazards of hoisting in mines has been with us since the industry passed its earliest stages, when coal and ore could be won from surface working and tunnels. At first, safety devices were introduced as means of decreasing the amount of labor necessary, to produce the mineral, or to increase the amount that could be obtained from a certain opening. For example, crude, ladders replaced winding footpaths or steps cut into the walls of the pit or shaft, decreasing the distance it was necessary to carry the product to the surface and eliminating, to some extent, the hazard introduced by the precarious footing afforded by such paths and steps. Later, instead of being carried from the pit on the backs of men, the product was hoisted in buckets or baskets on a rope passing over a pulley or around a windlass. Thus the capacity of the pit was considerably increased, and the hazard due to making many trips up and down the shaft was eliminated. From such beginnings accident prevention in mine hoisting advanced with the importance of the industry, until at present hoisting compares favorably with other branches of the mining industry with reference to safe practices. As in the other branches, this progress has been accomplished along two general lines-by legislation, rules, and education, and by the installation of safety devices. Though due credit must be given the former, it is not so satisfactory as the latter. Legislation, to be effective, requires a policing and inspection system to guarantee enforcement, such as we cannot hope to inaugurate. Rules may be satisfactory so long as the employer controls the labor market, and dismissal or some other form of discipline is an effective means of insuring obedience to the rules; but where labor demand is in excess of the supply, or where labor organizations are in control, such measures are not effective. An educational campaign will draw attention to hazards and may awaken a desire to avoid accidents by exercising the proper care.

Jan 2, 1922

By Percy Hopkins

KIRKLAND LAKE, the second most important gold area in Ontario, is situated in the north¬eastern part of the Province, 392 miles north of Toronto by railway. It is reached by a five-mile macadam road from Swastika, a village on the Temiska-ming & Northern Ontario Railway, 63 miles north of Cobalt. Gold, was first found at Kirkland Lake in 1911 by W. H. Wright. on claim No. 1830, now a part of the Wright-Hargreaves mine. In January, 1912, the metal associated with various tellurides was found by Harry Oakes and George Tough on the Tough-Oakes property 3/4 mile east of the lake. The shipping of hand-sorted, extremely high-grade ore, valued at $350 to $450 in gold per ton, from this property created great interest and resulted in numerous other discoveries. The early developments of the area, however, were much retarded on account of war conditions, labor troubles, and owing to the ore zone being largely under the bed of Kirkland Lake or in drift-covered depressions. It was not until early in 1918, when the Lake Shore Co. found its rich orebody under the bottom of Kirkland Lake, that the various ore deposits were believed to be more or less continuous along one main vein system. From that time most of the work in the area has been done along the "main vein" with gratifying results. Production began late in 1912, and up to the end of March, 1923, the five producing mines have yielded gold, with some silver, valued at $8,379,403. The production in 1922 was $2,162,548; that of 1923 should be over $3,000,000. The same general assemblage of rocks which occurs at. Kirkland Lake extends easterly for many miles to Larder Lake and beyond; hence there is a large area containing formations favorable for gold prospecting. In this general area numerous prospects are being operated, and among the most promising ones, may be mentioned the Argonaut, Crown Reserve and Asso-ciated Goldfields near Larder Lake. A 25-mile branch railway is now being constructed across the mineral area from Swastika to Larder Lake, passing through Kirkland Lake.

Jan 8, 1923

Discussion o f Papers. Meetings of the Institute offer opportunity for social acquaintance and exchange of ideas, for the--presentation of papers, and-for discussions. thereon ; also incidentally for viewing under especially favorable conditions mining operations and industrial establishments, and for hospitalities which demonstrate the brotherhood clue to kindred interests. Placing sociability prominent is not to be assumed as relegating other features of meetings to subordinate positions; but during about 40 years of membership in the Institute, the value of acquaintances formed (often ripening into close friendship), and the interchange of data, have frequently demonstrated that the social feature of meetings is of great and lasting value to the membership. Of a roll embracing 4,011 members, resident in all parts of our country, and scattered in various portions of the world, only a small fraction are able to attend meetings, even if the localities selected are alternately widely separated. Hence, the return which most members receive for their annual assessment of dues is limited to the publications issued, and the credit of being recognized as a. member of a great and worthy organization. The greater the value of the contents of our publication, the fuller the return which goes to members. While the Institute disavows responsibility for views or statements made ill papers which appear in its Transactions, the fact that these contributions, after passing proper censorship, are accepted by the Institute and spread before the world may properly be received by the writers as endorsements of their (the writers') ability to present a specific technical or industrial proposition worthy of being carefully read. But the mere presentation and publication of contributed papers falls short of fulfilling one important feature of our meetings. If the purpose is confined to having the writers' views, discoveries, theories, or methods published, this can be obtained through the technical or trade journals and magazines. The true value of a paper presented at a meeting of the Institute may often be gauged by the discussion which it encourages, although there are contributions of decided value which do not especially invite discussion. However, most Of the papers offered contain statements apt to encourage criticism or elaboration by others whose experience or knowledge, or both, assist in combating or endorsing statements made.

Jan 7, 1913

By M. D. Scott

A second generation tailings system, consisting of 8 km (5 mile) of large diameter 914- mm (36-in.) po1yethylene pipeline, the bulk of which was laid on a 0.2% grade, has been successfully operated by Lornex Mining Corp. for the past 2 yr. The system was designed to operate as a partial flow pipeline during average flows with the ability to pressurize itself and operate as a pressure pipeline under high flows, or clean itself out under sanding conditions. The system has exceeded design capacity and has had very little downtime. Polyethylene pipe was easily and inexpensively installed and has exhibited superior abrasion resistance characteristics.

Jan 1, 1978

By R. S. Barneyback

Not much more is known about concrete today than was known to the Romans. For all the research only better tools have resulted to measure the quality of the materials that go into it." In this paper "some of the materials for lightweight concrete and their characteristics are considered and effort is made to indicate their effect on the end result — a structure of lightweight concrete." Lightweight concrete had noble beginnings. It is believed that the first specification for lightweight concrete was written by the Roman Emperor Hadrian in the early years of his reign, 117-138 AD. Hadrian, was an engineer by trade and an Emperor by adoption. He took considerable interest in the structures sponsored during his reign, even to the point of working out the structural details and preparing working drawings for some of the more prominent works in the vicinity of Rome. In order to reduce the dead weight of the 140 ft diam dome of the Pantheon he specified that the lightweight structural concrete members supporting this concrete and tile composite dome were to be fabricated from a concrete containing pumice and scoria. Still standing after 18 centuries of abuse, this structure has been described as the master effort of a great structural genius, the ultimate achievement of Roman engineering skill.' The Romans were the first to employ many concrete techniques we think of as modem innovations. Some unnamed superintendent noted that when a carefully measured amount of pigs blood was measured into each batch of concrete during mixing, the concrete was more durable and exhibited much better resistance to freezing and thawing climates. He no doubt, attributed this success to the appeasement of one of the gods who in return provided protection for the building containing this sacrificial offering in its walls. It is known today that the blood-entrained air in the concrete tends to make mixtures more workable, resistant to moisture penetration and more resistant to frost damage.

Jan 1, 1964