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By George S. Rice

GROUND movement and subsidence is an important matter from several points of view and it is regrettable that more papers have not been written on this subject in the past year. Damage may be done to surface buildings or to the higher workings of a mine, and a study of the subject gives valuable in- formation on hanging-wall or roof control. The latter objective is strikingly shown in a recent paper presented by Jack Spaulding on Oct. 21, 1937, before the Institution of Mining and Metallurgy, of Great Britain, entitled "Theory and Practice of Ground Control in the Kolar Gold Field, India." All may not agree with some of his theories that were deduced from studies of the many violent rock bursts at depths of 5000 to 7000 ft., but the data obtained are of great value. His theories of symmetrical ring stresses and symmetrical domes which are pictured as perfect are rather hard to understand as such uniformity is un- likely in view of the irregularities in the formation due to folds and fractures of various kinds. All will agree in principle with this idea of domal effects, which have been observed in many countries, but they are generally irregular.

Jan 1, 1938

By O. F. Kammerer, W. E. Miller, D. H. Gurinsky, J. Sadofsky, J. R. Weeks

Zirconium and titanium inhibit solution mass transfer of steels by liquid bismuth, mercury, and lead. It is shown that in bismuth and mercury, these adsorb on the surface of the steels and subsequently react with nitrogen and possibly carbon from the steels to form inert, adherent surface layers of ZrN, TiN, or TiN + Tic. Data are presented which describe the condition under which thase deposits form. These inhibitors decrease the solution rate of iron into bismuth, and require a higher supersaturation for precipitation of iron from bismuth. USE of the low-melting heavy metals (bismuth, lead, mercury, and their alloys) as coolants has been limited because solution mass transfer of steels occurs in these liquids; i. e., iron dissolves in the hot sections of the heat transfer circuit and deposits in the colder sections. The rate of solution of iron and the temperature coefficient of solubility are sufficiently great to cause complete or partial stoppage by the deposition in the coldest section of a closed circuit in finite time, even though the actual solubilities are extremely low. In the development of the mercury vapor turbine by the General Electric Co., Nerad and his associates1 discovered that the addition of as little as 1 ppm Ti or Zr to magnesium-deoxidized mercury reduced the mass transfer of ferrous alloys by mercury to a negligible amount. Reid2 reported that titanium was detected chemically on the surface of steels contacted with this mercury alloy in amounts varying from 2.0 to 2.6 mg per sq in., the greatest amount being found in the hottest portion of the circuit. Reid stated that the titanium forms the intermetallic compound Fe2Ti by reaction with iron on the surface of the steels. This compound was presumed to be highly insoluble in mercury. More recently, El-gert and Egan3 have reported a greater than 100-fold reduction in the rate of mass transfer of a 5 pet Cr steel by liquid bismuth upon the addition of titanium (in excess of 50 ppm) and magnesium (350 ppm) in the liquid metal, during experiments performed in thermal convection loops* over the temperature differential 700° to 615° C. Also, Shep-ard and his associates' have reported that the addition of titanium to liquid bismuth and Pb-Bi eutec-tic produced a marked decrease in the rates of solution of both iron and chromium from type 410 steel capsules under static conditions. This inhibiting effect increased with repeated reuse of the capsules. Tests performed in this laboratory under carefully controlled conditions have shown that the addition of zirconium and magnesium, or titanium and magnesium, to liquid bismuth or lead greatly reduces the rate of mass transfer of chromium alloy steels and carbon steels in thermal convection loops with a maximum temperature of 550°C.5-9 The present paper will review the data obtained to date at this laboratory on the behavior of iron and steels in contact with liquid bismuth alloys containing titanium or zirconium, and will attempt to explain the role of the above additives in reducing solution mass transfer. Reaction between the Zirconium or Titanium Dissolved In Liquid Bismuth and an Iron or Steel Surface Reaction between Zirconium Dissolved in Bismuth and the Surface of Pure Iron-—A small pure iron crucible (analyzed by the supplier to contain 0.8 ppm N was contacted with bismuth containing approximately 0.1 pet Mg and varying amounts of a radioactive zirconium tracer. The crucible was then inverted at the temperature of contact. The thin residual layer of adherent bismuth was dissolved in cold, concentrated nitric acid. The crucible surface and the solidified bismuth were then analyzed for radioactive zirconium. An analysis of the activity loss on the crucible surface and the weight loss of the crucible during the nitric acid treatment showed that the acid treatment removed the zirconium that had originally been dissolved in the adherent bismuth, but not any zirconium that may have reacted with the crucible surface. The crucible was then pickled in warm aqua regia to remove all surface activity, hydrogen-fired at 600°C, and recontacted with a new liquid alloy. The results of the experiments contacted 1 hr at 450°C show, Fig. 1, a Langmuir-type adsorption with an adsorption free energy of approximately 17 keal per g atom Zr.5 This deposit was estimated to contain 1 atom of zirconium for each 7 to 8 iron atoms on the crucible surface, assuming a surface roughness factor of the pickled crucibles to be five. Increasing the temperature to 520°C caused consi-

Jan 1, 1959

By Herbert H. Kellogg

IN 1930, Taggart, Taylor and Knoll1found that addition of various electrolytes to suspensions of ground minerals resulted in the stopping or starting of Brownian movement of the suspended particles. On the basis of the many new facts found, they rejected the "classical "[t] theory of Brownian movement and proposed an "ionization" theory. This new theory was further supported in later publications by Taggart.3,4 The acceptance of the ionization theory by men in the field of flotation may be judged by the mention given this theory in Gaudin's "Principles of Mineral Dressing,"5 Wark's "Principles of Flotation,"6 as well as in a recent paper by Fitt, Thomas and Taggart.7 The proponents of the ionization theory have gone further than the mere statement of the new theory. A parallelism between the Brownian movement of mineral particles and their behavior in flotation was reported.1,3,4 Likewise, the correlation between flocculation-dispersion of mineral particles and the Brownian movement of these particles has been investigated.7 Bankoff15 has suggested that "slime-coating" can also be directly correlated with the Brownian movement of the slime particles. In each of the instances mentioned it is the ionization theory of Brownian movement that has been used to "explain" the correlations that were found. The essential conflict between the kinetic theory and the ionization theory can be understood best by a brief description of each. The kinetic theory* proposes that Brownian movement is caused by the impacts of liquid molecules against the solid particles. At any instant of time, the molecular impacts on all sides of the solid particle will not balance, and the particle will receive a push in some direction. According to this theory, all particles suspended in a liquid are in Brownian movement. However, if the particle is very large, the impacts on all sides will very nearly balance and the motion will not be noticeable. Another factor, besides the size of the particle, that affects the magnitude of the Brownian movement is the viscosity of the liquid-the greater the viscosity, the less the displacement of particles by Brownian movement. This theory has been verified experimentally by measurement of the velocity of Brownian movement, and by measurement of the compacting of suspensoid particles under the influence of gravity.2 The originators of the ionization theory found that the addition of various electrolytes to slime pulps caused cessation or commencement of Brownian movement, depending upon the chemical nature of the particle and the electrolyte. The Brownian movement of quartz particles was observed to stop upon the addition of certain electrolytes, where the conditions of the experiment prevented flocculation

Jan 1, 1945

By J. Robert Van Peli

IT was a strange but highly fruitful marriage-that union of hardy explorers, seeking the rich treasures of copper in the Lake Superior wilderness, with Boston's aristocracy of brains, capital, and enterprise. This historic wedlock, which has continued happily to the present day, was the means by which the wealth of Lake Superior's copper was won for the use and benefit of an expanding America. One branch of this family tree, the western branch, begins with prehistoric Indian miners, embraces the early French explorers of the Upper Lakes, and finally includes the British and American pioneers who reduced the vague rumors of copper to known fact and actually began the mining of copper in the wilderness. The other branch, the New England line, begins

Jan 1, 1948

By Frank F. Poland

TEE purpose of this paper-is to describe a new process for the refining of secondary copper-base metals and a specially designed high-temperature electric-resistor furnace used in the process for the distillation of zinc from these metals. The process was used for the conversion of nickel silver to cupronickel and to recover the zinc content in metallic form. It also proved applicable and economical for the treatment of scrap brass for separating and reclaiming the copper and zinc. The relatively large furnace developed for the distillation of zinc is described in detail, for it made economically possible the direct recovery of metallic zinc from scrap brass, which is a new step in the processing of such material. Considerable interest has been shown in the utilization of the distillation furnace for other metallurgical processes, where it is of advantage to operate in a controlled neutral or reducing atmosphere, or to avoid having the processed metal in contact with refractories other than carbon, or to operate at temperatures between 3000 and 4000°F. PURPOSE OF DEVELOPMENT It was recognized early in the war effort that nickel would become a critical metal, therefore all nickel stock and alloys containing relatively high percentages of nickel were frozen immediately. Among these alloys were considerable quantities of various grades of nickel silver, an alloy containing copper, nickel, zinc, and in some grades lead, also minor amounts of iron, manganese and other constituents. At the time there was no existing plant or process to eliminate the zinc, lead, and minor constituents so as to convert this metal to cupronickel, one of the important alloys needed by the U. S. Navy for condenser parts. Therefore the Bureau of Industrial Conservation of the War Production Board requested the executives of the leading nonferrous metal companies to have their metallurgical staffs study the problem of converting this metal to cupronickel conforming to U. S. Navy Specification 44T40. The composition specified therein is as follows: nickel, 29 to 32 per cent; zinc, 1.00; iron, 0.00 to 0.60; lead, 0.05; tin, 1.20; manganese, 0.00 to 1.00; total of other elements (maximum), 0.50; copper, remainder. The problem in converting these alloys to cupronickel was the elimination of zinc, lead, iron, manganese, and other elements without appreciable loss of nickel to slags or other by-products. Revere Copper and Brass Incorporated, through its Research and Development Department, undertook to solve this problem. A Government-owned plant was built at Rome, N. Y., and there the con- version was successfully made.

Jan 1, 1946

By Arnold K. Reese

It is not the purpose of the writer to set forth in these notes anything new or surprising in blast-furnace practice, but simply to lay before the Institute the somewhat unusual results obtained during a period of six consecutive months, ending April 30, 1896, at the Dover furnace of the Penn Iron and Coal Co., and to give, with these results, the conditions under which they were obtained, and all figures pertaining to that period. This plant was entirely rebuilt, on thoroughly modern and improved plans, in the spring of 1895, by Frank C. Roberts & Co., of Philadelphia.

Jan 1, 1898

By G. J. Ballmer

Drilling and blasting 12-in. blastholes started about the middle of 1946 and has worked out so well that about one half of the blasting, formerly done with 9-in. holes, is now done with 12-in. holes. In most of this work the harder benches were chosen for the 12-in. size because these were the areas where the greatest difficulty was encountered in thorough fragmentation. At the start of this experimental work a 42-T Bucyrus- Erie churn drill was available whereas all other blasthole drilling was being done with 29-T rigs. The large drill was first equipped with a standard 9-in. string of tools but it could not drill quite as fast as the 29-T drills. How- ever, when the weight of the string was increased about 700 lb, or to a total weight of about 3500 lb, it was found that the 42-T exceeded the drilling speed of the 29-T by about 25 per cent. When a 12-in. bit was substituted for the 9-in. bit the 42-T rig again dropped behind the drill- ing rate of the 29-T rigs. At this stage of the experiment the 42-T was using a 12-in. bit with detachable points and the total weight of the string of tools was about 3800 lb. It took longer to change the drill points than it did the regulation bit and this accounted for some of the slower drilling rate. When a heavier stem and standard construction 12-in. bits were used it was found that the 42-T could drill a 12-in. hole slightly faster than a 29-T could drill a 9-in. hole even in the hardest rock in the pit.

Jan 1, 1949

By A. M. Gaudin

CHANGES in industrial practice, in plant design, and in research methods which are so clearly to be seen on every hand, have affected the mineral industry as well as others. In particular, ore dressing has passed through a revolution in practice brought about by the introduction of flotation and other quasi-chemical methods, until it has ceased to be solely the mechanical preparation of ores. In fact, the term "ore dressing" itself is obsolescent, and "mineral dressing" has been growing in popularity. This assures adequate recognition of the fact that mineral substances other than ores, e.g. coals, clays, and cement rock, are treated by the same general methods. As a result of these industrial changes it was felt that a complete rearrangement of the curriculum and laboratories at the Massachusetts Institute of Technology would be ad-vantageous. Such a rearrangement would allow instruction and research to proceed in wider accord with industrial evolution and the needs of our times.

Jan 1, 1942

By I. C. White, G. H. Ashley, J. A. Bownocker

Among the rich mineral deposits of the great Appalachian field, the Pittsburgh coal bed stands pre-eminent. Other coal beds may cover a wider area, or extend with greater persistence, but none surpasses the Pittsburgh seam in economic importance and value. It was well named by Rogers, and his able assistants of the First Geological Survey of Pennsylvania, in honor of the city to whose industrial growth and supremacy it has contributed so much. Whether or not the prophetic eye of that able geologist ever comprehended fully the part which this coal bed was to play in the future history of the city that gave it a name we do not know; but certain it is that the 7 ft. of fossil fuel, which, in Rogers' time, circled in a long black band around the hills and, overlooking the site of Pittsburgh from an elevation of 400 ft. above the water of the Allegheny and Monongahela, extended up the latter stream in an unbroken sheet for a distance of 200 miles, has been the most potent factor in that wonderful modern growth that has made the Pittsburgh district the manufacturing center of America, and that bids fair to continue until it shall surpass every other district in the world, even if it does not now hold such primacy.' The Pittsburgh coal bed stands today as probably the largest contributor of wealth of any single mineral deposit in the world. If it is not, what other deposit is? It has contributed to Pennsylvania alone more than 2,500,000,000 tons of high-grade coal worth nearly $4,000,000,000; since 1910, it has added more than $2,500,000,000 to the value of Pennsylvania's mineral output. In 1920, this bed2 contributed 127,227,000 tons of coal as follows: Pennsylvania, Pittsburgh district........................ 38,245,000 Connellsville district................................. 34,095,000 Weatmoreland-Ligonier district........................ 16,107,000 88,447,000 West Virginia, Fairmont district........................ 15,571,000 West Virginia-Ohio, Panhandle No. 8 district............. 21,128,000 Maryland-Potomac (Est. one-third of production)......... 2,081,000 38,780,000 Total........................................... 127,227,000

Jan 1, 1927

By Robert Glass Cleland

[Incorporated under the laws of the State of New York OFFICE, 41) WALL STREET, NEW YORK 5, N. Y. Authorized4,000,000 shares $150,000,000.00 Outstanding-5,071,260 shares 126,781,500.00]

Jan 1, 1952

C. N. FEnner, New York City (communication to the Secretary) : A possible explanation of some of the' phenomena of amalgamation cited by Mr. Bayliss and others has occurred to me. We know that if, to a quantity of mercury, gold and silver are added until a putty-like paste is formed, and if this mass is spread on a flat surface and pressure is applied, a more fluid portion of the mercury will be squeezed out from the rest, carrying gold and silver with it. The proportion of gold to silver will depend, I think, upon various causes and conditions—the relative chemical affinity which gold and silver have for mercury; the amount of pressure used; the presence of other metals:

Jan 1, 1898

By William Gilman

IN the past five years, and without much fanfare, Turkey has emerged as a significant figure in the world mining picture. This has been accomplished by a five-year plan now in its last year. A second five-year plan is already under way, ahead of schedule. It will concentrate even more than the first in developing Turkish mines in order to increase present exports of coal, chrome ore, and copper, and to develop new mineral exports as well. To be fully understand the republicic?s mining program should be considered as something more than merely tapping rich resources in the East along the Aegean Sea, in the North among the mountains descending to the Black Sea, and in the West at the foot of the Taurus Mountains. It should also be viewed in the light of a strong nationalist policy with many aspects of state socialism. Turkey declares frankly that all mineral re- sources belong to the nation and all exploitation should be by the state for the twin purpose of modernizing the state and securing foreign exchange for the state by exports. Accordingly, the principal mines are state-operated and a few lesser enterprises, although not state-owned, have at least been put in the hands of Turkish capital.

Jan 1, 1938

By J. H. Nead

The experiments herein described were undertaken with a view to investigating thoroughly the influence of carbon on the tensile and impact physical properties of carbon steel. The original comprehensive plan included investigation of a series of steels with varying carbon contents over a wide range of heat treatments. These were to be studied as to their static tensile qualities, and also their resistance to shock as measured by the Charpy impact bending test. A thorough metallographic examination was likewise included in the schedule. The Charpy tests and the metallographic examination have not been completed to date, and are accordingly withheld for another report. All heat treatments, however, have been made, and the static tensile tests have been completed. A description of the procedure of the experiment and the results thus far obtained are therefore reported herein. Conclusions No attempt is made to draw general conclusions from these experiments, but the curves and the data are submitted as being of general importance and wide applicability. Composition of Materials An attempt was made to secure steels increasing in carbon by increments of 0.1 per cent. from 0.1 per cent. up to 0.8 per cent., and from that composition to 1.6 per cent. by increments of 0.2 per cent. Actually, however, steels of the composition given in Table I were procured, and as the carbon contents were arranged sufficiently well so that satisfactory curves could be drawn showing the relation between carbon content and other properties, these steels were used in the experiments.

Jan 1, 1916

By Francis A. Thomson

DO the curricula of our mineral technology schools prepare their graduates to meet properly the full range of their responsibilities in after life? An unequivocal "no" could be returned to this question, because training and experience in professional work are quite as important as adequate college preparation. Furthermore, a had curriculum with a splendid corps of men doing the teaching and a competent body of students doing the learning will produce a better result than an ideal curriculum in the hands of unqualified teachers and poorly prepared students.

Jan 1, 1937

By Haydn H. Murray, Sam H. Patterson

The term clay is somewhat ambiguous unless specifically defined, because it is used in three ways: (1) as a diverse group of fine-grained minerals, (2) as a rock term, and (3) as a particle-size term. Actually, most persons using the term clay realize that it has several meanings, and in most instances they define it. As a rock term, clay is difficult to define because of the wide variety of materials that compose it; therefore, the definition must be general. Clay is a natural earthy, fine-grained material composed largely of a group of crystalline minerals known as the clay minerals. These minerals are hydrous silicates composed mainly of silica, alumina, and water. Several of these minerals also contain appreciable quantities of iron, alkalies, and alkaline earths. Many definitions state that a clay is plastic when wet. Most clay materials do have this property, but some clays are not plastic; for example, halloysite and flint clay. As a particle-size term, clay is used for the category that includes the smallest particles. The maximum-size particles in the clay-size grade are defined differently on various grade scales. Soil investigators and mineralogists generally use 2 micrometers as the maximum size, whereas the widely used scale by Wentworth (1922) defines clay as material finer than approximately 4 micrometers. Some authorities find it convenient to use the term clay for any fine-grained, natural, earthy, argillaceous material (Grim, 1968). When used this way, the term includes clay, shale, or argillite, and some argillaceous soils. Even though no standard definition of the term clay is accepted by geologists, agronomists, engineers, and others, the term is generally understood by those who use it. Clay is an abundant natural raw material, and it has an amazing variety of uses and properties which will be discussed in this chapter. Clays rank among the leading industrial minerals in both tonnages produced and total value. Their importance is indicated in Table 1, which lists the 1978, 1979, and 1980 production and values according to the US Bureau of Mines (Ampian, 1980). Statistical data summarizing world production of kaolin, bentonite, and fuller's earth are compiled by the US Bureau of Mines (Ampian and Polk, 1981). The total world bentonite production in 1980 was 6,625,204 st of which the United States produced 4,184,619 st. The total fuller's earth produced in the world in 1980 was 1,952,600 st of which 1,534,000 st was produced in the United States. The total world kaolin production in 1980 was estimated at 22,971,000 st. Approximately 13 million tons of this total was produced in two countries, the United States and the United Kingdom. World production data on ball clay, fire clay, and miscellaneous clays are not available. As industrial minerals, clays are a complex group that consists of several mineral commodities, each having somewhat different mineralogy, geologic occurrence, technology, and uses. In this chapter these commodities are organized as follows: (1) bentonite and fuller's earth; (2) kaolin, ball clay, halloysite, and refractory clays; and (3) miscellaneous clay and shale. Bentonite and fuller's earth are grouped together because they are closely interrelated. Though bentonite is a term based on mineral composition and fuller's earth is a term based on use, the two are virtually inseparable, because much, but by no means all, clay sold as

Jan 1, 1983

By L. W. Blau

THE entrance of geophysics and geochemistry into petroleum engineering may be viewed with apprehension by some engineers. They may not remember the time when "practical oil men" opposed the invasion of engineers into the field of petroleum production. By their excellent contributions they established themselves. In the popular mind, engis veers are practical men whereas physicists and chemists are suspected of being theoretical. It will be best to annihilate this misconception right now at the beginning of a closer relationship between petroleum engineers. geophysicists, and geochemists.

Jan 1, 1943

By Robert S. Williams

On several occasions, when 60-40 brass is first obtained in the beta condition by quenching at about 825" C. and is then reheated, the writers have noticed that reerystallization will take place in the form of twin crystals at the grain boundaries of the original beta crystals. It was, therefore, thought that interesting results would be obtained if this twinning process was studied further, especially as to the temperature at which it first occurs. The material used in the investigation was a bar of extruded muntz metal, 1/2 in. in diameter, and of the following composition: Copper, 60.21 per cent.; zinc, 39.73 per cent.; lead, trace; iron, trace; tin, nil. Specimens 1 in. in length were sawed from this bar and a hole was drilled into the side of each specimen until it reached the center, and the tip of a platinum-platinum rhodium thermocouple was inserted. A small Hoskins' resistance-type electric furnace was used for heating the specimens. The specimens were first heated at 840' C. for 2 hr. and then quenched ' in cold water, in order to get the material entirely in the beta state. In every case, in the reheating process, the furnace was brought to the desired temperature before the specimen was introduced. The time occupied in preheating was from 20 to 30 min. By sawing back 1/4 in. on each side of the hole, two parts were obtained from each specimen and duplicate observations were possible. The specimens were held at the reheating temperatures for periods of 15 min., 30 min., 1, 2, and 4 hr. All specimens were etched with a freshly prepared mixture of equal volumes of concentrated NH4IOH and H2O2.

Jan 1, 1924

By S. J. CRAIGHEAD

IN 1912 the United States Smelting Refining and Mining Company made a large investment in a number of coal properties in Utah and in 1915 a subsidiary, the United States Fuel Co., was organized to take over these properties. Operations started in 1916 and the Company soon became, and remains, one of the major coal producers of the State. It now produces approximately one million tons of coal annually, which is about 22 per cent of Utah's output. The U. S. Fuel Co. owns large reserves of good coal and is in a position to expand operations with the industrial growth now taking place in the West. Traveling through the Western States, one is struck by numerous advertising signs portraying the picture of jovial Old King Cole of nursery rhyme fame. His rotund figure and beaming countenance are the symbols of Utah King Coal, the product of the King mine of U. S. Fuel Co. King Coal is a by-word of quality coal throughout all the Western States.

Jan 1, 1948

By W. Gundaker, F. C. Schwerer

Natural chromium-bearing spinels (chromites), which are used as refractory materials in basic steelmaking, are the only commercially important chromium ore and are also encountered as difficult-to-separate contaminants in ore deposits of potential economic value. Techniques for characterization and separation of ore materials frequently are dependent on the magnetic properties of the constituent minerals. An experimental program was initiated to explore the effects of temperature and of simple mechanical and thermal treatments on the static magnetic properties of several ore-grade natural chromites. Studies of the temperature dependence of the magnetic properties showed that the natural chromites, which are dilute in the magnetic ions Fe and Cr, order magnetically only at cryogenic temperatures. However, mechanical treatment in the form of crushing produces a magnetic component that is ordered at room temperature and that is of sufficient strength to alter magnetic-separation characteristics. The additional magnetic component apparently is associated with surface structures which develop during crushing and disappear after heating to above about 500°C. Preliminary studies indicate that this surface structure enhances the susceptibility of the chromite grain surfaces to gas reactions at moderate temperatures.

Jan 1, 1976

By W. B. Boggs, J. N. Anderson

An account of the operation of the Noranda smelter covering the period from December, 1927, when the smelter started, until December, 1929, was given in a paper published by the Canadian Institute of Mining and Metallurgy early in 1930.' The object of the present paper is to review matters of interest in the original paper and to describe the present construction and operation of the smelter, with particular reference to the reverberatory-furnace practice. The Noranda smelter was built by Noranda Mines, Ltd., from the designs of A. E. Wheeler, consulting metallurgist of New York, for the reduction of ores and concentrates from the Horne mine and to treat, on a custom basis, ores and concentrates from other mines in the Rouyn district. The smelter is at Noranda, about 330 miles directly north of Toronto. Construction work was started in June, 1926, and copper was first produced in December, 1927. The smelter was built throughout as two duplicate units, each with a rated capacity of 500 tons of ore per day. Operations were started with one unit and after several months it was found that one unit alone could smelt 1000 tons of ore a day. At that time there was only one hoisting shaft, No. 3, and its hoisting capacity and the capacity of the original crushing plant were insufficient to supply ore for the two units at the increased tonnage. Accordingly No. 4 shaft was sunk and a new crushing plant provided to handle the ore hoisted there. Operating two units at capacity also required the installation of two more converters to treat the additional quantity of matte produced. This work was completed in the latter part of November, 1929, and since then both smelter units have been operating continuously. In 1928, a mill to treat 500 tons a day of concentrating ore was completed. Since then the concentrator capacity has been increased twice, and at present 2000 tons a day of ore are being concentrated. The layout of the surface plant of the mine, concentrator and smelter is shown in Fig. 1 and the general plan in Fig. 2. The smelter is shown in more detail in Fig. 3. The original hoisting shaft, No. 3, is now used only for handling men, supplies and waste rock, and the original crushing

Jan 1, 1934