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By L. E. Young

MUCH has been said and written on this subject and probably little new can be said. However, the point of view of the operating company changes from time to time, and more stress may be laid upon a subject today than was done some years ago, and it is with this changing point of view that the following observations are presented: The writer wishes to limit the discussion to views of a company mining bituminous coal, particularly to what the production department expects of the college grad¬uate. In an editorial in MINING AND METALLURGY for February, 1929, entitled "Is. Mining Engineering Passing?" it is stated that: It is not by accident that mining engineering courses have been general rather than special and form even today the only general engineering courses widely offered and followed by engineering students.'* * * even in this age of specialization, the mining engineers remain a body characterized particularly by broad knowledge.

Jan 1, 1929

By C. A. Stetefeldt

FoR the convenience of those who do not care to enter into the details of this long essay, I begin with a summary of the most important results it presents. The extraction of silver by the lixiviation-process from ores which have been subjected to a chloridizing-roasting, is based upon the fact that silver chloride is easily soluble in solutions of sodium or calcium hyposulphite, and that silver is precipitated from such solutions by an alkaline sulphide, with regeneration of the hyposulphite salts. In case the ore contains lead a large portion of the latter is and dissolved, lead sulphate being soluble in hyposulphite solutions. If, at the same time, copper is present, the sulphides precipitated from the solution, contain silver, copper, and lead, a combination of metals not desirable for subsequent treatment. Mr. E. H. Russell, of Park City, Utah, is the inventor and the patentee in the United States and several foreign countries of a new lixiviation-process, based upon the chemical facts discussed in this paper. Mr. Russell has discovered that lead can be completely separated from a sodium hyposulphite solution, as lead carbonate, by sodium carbonate or purified soda-ash, without precipitating any copper or silver. After decanting the solution from the lead carbonate, silver and copper are obtained from it in the usual way. This method of separating lead prohibits the use of calcium poly-sulphide as a precipitant for the sulphides, because any calcium entering the regenerated lixiviationsolution would also be precipitated as a carbonate with the lead by soda-ash. Hence, a sodium sulphide must be employed. A full investigation has demonstrated that this is by no means detrimental. Sodium sulphide and hyposulphite are more advantageously used in the lixiviation-process than the corresponding calcium-salts. Another defect in the lixiviation-process consisted in the necessity of a very perfect chlorination of the silver in the ore, because silver in

Jan 1, 1885

By E. A. Holbrook

IN view of what has happened in - the past three years, it seems incredible that industrial corporations continue to write to engineering and mines schools for "promising members of the graduating class," or, indeed, that they even send representatives to the colleges to interview engineering graduates. Certainly, by this time, every company should be aware of the fact that recent engineering graduates are almost nonexistent and the number is not likely to increase within the next several years. At the February, 1945, annual meeting of the Local Section delegates of the A.I.M.E. in New York, W. B. Plank, professor of mining engineering at Lafayette College, summarized well the situation of the colleges by titling his talk "The Lost Generation of Engineers."

Jan 1, 1945

By Ernest N. Patty

WHEN an Alaskan prospector makes a new mineral discovery he stakes out his claims and then starts prospecting for a near-by landing field. This may be a convenient lake but more often it is a gravel bar along a river, where, by cutting off some brush and throwing the larger rocks to one side and then tying a flour sack to a pole, he may decoy some intrepid aviator into testing it gingerly with the wheels of his plane. It was only a few years ago that .the fence around the baseball park at Fairbanks, Alaska, was taken down so that planes could get in and out of the ball park without ripping off boards. Today the grandstand is lost among the modern hangars which line one side of a modern and busy airport. Planes come and go all during the day, and in summer, when there is no darkness, the night stillness is frequently broken by the hum of a motor overhead. Fairbanks is the hub of interior Alaska and from that hub airplanes radiate in all directions to mining camps large and small. An air industry of comparable size is based at the town of Anchorage, and in fact there are but few towns of more than 200 population in the Territory that do not have one or more planes based there.

Jan 1, 1937

By Earle C. Waite

THE Industrial Minerals Division this year held no individual sessions of its own except the business meeting Tuesday afternoon. One session was held jointly with the Society of Economic Geologists, one with the Milling Methods Committee, and two with the Society of Economic Geologists and the Mining Geology Committee. At all of these meetings the attendance was better than usual and the Tuesday afternoon session, with nearly 400 present, probably set a new record for the Division. Joint sessions seem extremely popular when papers of mutual interest are presented. On Monday afternoon, mica was the predominating subject. The North Carolina mines provided most of the information presented, although the discussion brought out similarities with the New England mines. B. C. Burgess particularly stressed the fact that with the existing curtailment of mica from India it is necessary to get the most mica in the shortest time from the mines in this country. He said that the Colonial Mica Corp. hopes to have 1000 mines operating in the near future. This seems a great number, but when one considers that these mines employ from 3 to 28 men, mostly nearer the low figure, the output of each mine is relatively small. Although the price of mica is from six to ten times the prewar price, the yield of 8 to 150 lb. of mica per ton of raw ore does not provide high returns to the producer.

Jan 1, 1943

By Joseph R. Hatch

When compared to average shale composition, average coal is enriched in sulfur and selenium, has similar amounts of arsenic, beryllium, lead, antimony and molybdenum, and is depleted in at least 26 other elements. Within a coalfield, or region, some coals are enriched (10X average shale) in silver, arsenic, cadmium, cobalt, germanium, molybdenum, nickel, lead, selenium, uranium, and zinc. Important factors controlling element distributions in coal include geochemical conditions (primarily pH) in the peat swamp, composition and depositional environment of coal roof rocks, thermal maturity (rank), nature and intensity of any epigenetic mineralization, composition of ground waters that come in contact with the coal, and degree of weathering.

Jan 1, 1983

By J. C. Uy, T. E. Davidson, A. P. Lee

The effects of hydrostatic pressures to 26 kbars on the micro structure of poly crystalline Cd, Zn, Bi, Sn, Zr, Mg, Cu, and Fe were examined. Pressure-induced microscopic plastic flow in the form of boundary migration, slip, multiple slip, or twinning has been observed either singly or in combination in cadmium, zinc, bismuth, and tin. No deformation was observed in zirconium, magnesium, copper, and iron. The occurrence of such deformation, in terms of its intensity and initiation pressure, relates directly to the degree of anisotropy in the linear compressibility. Pressure cycling does not significantly affect the residual tensile properties of a zinc alloy which exhibits pressure-induced deformation similar to that of Pure zinc. CLASSICAL elastic theory predicts that a superim-posed hydrostatic pressure will not induce shear stresses in an ideal material. Thus, in the case of homogeneous and isotropic materials plastic flow will not occur as a result of pressure exposure, regardless of the magnitude of the pressure, unless some form of phase transformation or permanent density change takes place. However, real materials, such as metals, often vary considerably from the condition of homogeneity and isotropy. For this reason, Vu and johannin' examined and observed hydrostatic pressure-induced microscopic deformation in polycrystalline cadmium and, zinc, but not in aluminum, to pressures of 9 kbars and indicated that its occurrence is related to anisotropy in the linear compressibility. In addition, Davidson and omaan' have reported pressure-induced deformation in polycrystalline bismuth below the 1-11 transformation pressure. It becomes apparent then that under certain conditions hydrostatic pressure can induce localized internal shear stresses in some metals of sufficient magnitude to cause plastic flow. In this work, eight pure single-phase metals of different lattice structures and degrees of elastic anisotropy were examined after pressure exposures of up to 26 kbars in order to establish the conditions under which such deformation occurs and the type of deformation as a function of pressure. The effects of pressure cycling on the mechanical proper-

Jan 1, 1965

By F. Julius Fohs

CENTRALLY located with relation to the largest iron- and steel-producing districts of the United States, the fluorspar-deposits of Kentucky possess increasing interest and importance. As typical of the numerous fluorspar-mines of Kentucky and Illinois, I have selected for description the Memphis., because it and others of its immediate group exhibit the conditions characteristic of all. I. THE MEMPHIS MINE. This mine lies 5 miles NW. of Marion, in Crittenden county, Kentucky, a station on the Chicago and Nashville division of the Illinois Central R. R. For the first mile and a half out of Marion we see only Birdsville or Middle Chester sandstones of Mississippian age. Then we cross a fault of some 350 ft. displacement, and the Ste. Genevieve oolite sets in. Beyond the fault, oolite is the predominant rock, except that the bills to the north have a capping of Cypress or lowest Chester sandstone, 80 ft. below which is an outcrop of from 6 to 10 ft. of Ste. Genevieve (Rosiclare) sandstone. Occasional sink-holes are noticed, and as the mines are approached evidence of faulting is again seen.. A line of crude head-frames and open-cut dumps, extending for more than a quarter of a mile, marks the Klondike vein. The open-cuts are from 15 to 20 ft. deep, and in most of them, from the surface down, was found the reddish gravel which is really fluorspar-some of it white or purple and crystal-clear (if the red clay is washed off), and some carrying iron and silica, and stained by waters from the decaying limestone walls. In one of these cuts, at a depth of 20 ft., white and purplish honey-combed fluorspar was found, in which the larger cavities are due to limestone and calcite leaching, and the minute ones to the leaching of zinc-blende.

Apr 1, 1909

By S. S. Hsieh, J. R. Lehr

Bench scale beneficiation studies were made on Idaho dolomitic phosphate rock using the TVA carbonate flotation process. The process used diphosphonic acid as a phosphate mineral depressant and fatty acid as a carbonate mineral collector. Silica was subsequently rejected as float using an amine collector, with phosphate product recovered as the sink fraction. Two samples of prepared flotation feed from commercial operation were used. One contained 21% P205 and 3.2% MgO. The other contained 26% P205 and 1.8% MgO. The results indicate that concentrates containing 31% to 33% P205 and 1% or less MgO can be obtained, with about 80% P205 recovery.

Jan 1, 1986

By Robert F. Mehl

THE mechanical behavior of metals and alloys is presumably conditioned by two factors; namely, the crystalline symmetry and the interatomic forces. Considerable attention has been given to the first of these factors through the recent advances in X-ray technique. It is the purpose of the present paper to call attention to the importance of the second of these factors, to point out promising methods of investigation, and to present some pertinent data. Plastic deformation takes place by slip along atomic planes.1 This slip may be inhibited in a number of ways: by the interatomic forces of cohesion which bind the atoms rigidly in a lattice structure, which in pure metals is usually of high symmetry; by lattice distortion caused by solid solution formation or by mechanical strain; by the intercrystalline boundaries where slip is restrained, probably by the non-registration of the atom planes in adjacent crystallites;2 and by the presence of small hard particles which serve to "key" the slip along the atom planes.3 In pure metals, and perhaps also in solid solutions, the atom planes of easiest slip are those exhibiting the greatest density of atomic population and the greatest interplanar distance4 and apparently can now be predicted from the analysis of the lattices. Concerning the interatomic forces, which resist this slip by holding the atoms firmly together, little is known. Most textbooks on physical metallurgy, following the work of Bottone,5 correlate the hardness of the pure metals with the atomic volume,

Jan 1, 1928

By L. C. Morganroth

Magnesites are of two general classes - massive and crystalline.

Jan 1, 1915

By Sherwin F. Kelly

THE present lull in engineering activities presents an advantageous moment for inquiring into the position now occupied by geophysics in its various fields of application. The recent over-expansion in all lines of work resulted in an uncritical employment of these methods of exploration which was bound to have its harmful reaction. The pendulum has now swung back, producing a decidedly hypercritical attitude toward the new science that had been recently welcomed so joyfully as the panacea for prospecting troubles. The severe retrenchment in exploration has forced upon us a period of waiting and, it is to be hoped, of profitable contemplation. This can well be employed in trying to pass a reasoned judgment on what position geophysics should occupy in the new geological exploration programs that will inevitably ac- company the looked-for industrial recovery.

Jan 1, 1931

By L. Bombardieri, H. F. Mills

Iron King mine, producing gold-silver-lead-zinc-ore, is 10 miles east of Prescott, Ariz. At present the 1806 level is being developed. The echelon pat tern of ore deposit continues at depth but is less pronounced, and the orebody is now more or less continuous over 2600 ft of strike length, with widths 5 ft to as high as 26 ft where overlapping of lenses occurs in one section of the mine. Better continuity of ore at depth has encouraged systematic mining and improved plant facilities to offset higher operating costs. With favorable persistence of ore at depth, the three-compartment No. 6 hoisting shaft appeared inadequate to handle increased tonnage from greater depths, and in 1952, a four-compartment steel and concrete shaft was started. This is now at a depth of 1906 ft, and shaft pockets and loading cartridges are being installed on the 1806 level. Ore from the new shaft, hoisted in 5 ½ -ton Jeto bottom dump skips, is dumped into a 500-ton shaft bin, from which it is fed to a 16x30-in. gyratory crusher and conveyed 415 ft through an undersurface concrete gallery to the secondary crusher and conveying system supplying the 900-ton mill. Lead, zinc, and pyrite concentrates are floated, and the flotation tailings are cyanided after desliming. Waste from the new shaft is dumped into a 250-ton surge bin, fed from this bin to a 24-in. conveyor, and discharged into the glory hole above the block cave. The new shaft is served by a double-drum 400-hp hoist used for ore and waste; the No. 6 shaft conveys men and material.

Jul 1, 1956

By Donald Barton

THE theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A =KRM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical dis¬cussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass. GRAVITY AND LEVEL SURFACES Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration. In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm./sec.2) and less commonly merely as centimeter-gram-second units (C. G. S.). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. . In most cases, it is very nearly, but not quite, per¬pendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as "the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it com¬monly is very nearly, but not quite, a straight line.

Jan 1, 1928

By AIME AIME

EVEN though most of the program of the joint meeting at Easton, Pa., on Oct. 30 to Nov. 1. was devoted to the interests of combustion engineers rather than to coal-mining engineers, nevertheless the A.I.M.E. Coal Division was well represented, with 83, or close to one third of those in attendance giving this as their affiliation. The fuels division of the American Society of Mechanical Engineers had 108 representatives, and an equal number reported no society affiliation. Added to the men's total registration was that of some twenty ladies so the total attendance was in the neighborhood of 325, exceeding that of the last two joint meetings, at Birmingham and Columbus, and equaling the 1938 crowd at Chicago.

Jan 1, 1941

By Raymond D. Sloan

Retaining third place in crude-oil production among the nation's oil-producing states, Oklahoma's output in 1942 totaled 137,792,000 bbl., a decline of 9.4 per cent from the previous year's total of 152,117,000 bbl. Production declined from an average of 403,000 bbl. daily in January 1942 to an average of 355,000 bbl. during December, a reduction of 48,000 bbl. daily (11.9 per cent) during the year. At the end of 1942 it would appear inevitable that the downward trend in production will continue in 1953 unless halted in the immediate future by greater than normal discoveries and development. To Jan. I, 1943, Oklahoma has produced 5,067,013,000 bbl. oil crude oil. Development and Exploration Development dropped abruptly in 1942, reflecting the lack of any sizable discoveries and the effect of the provisions of Federal Well Spacing Order M-68, which became effective in December 1941. In all, 1210 wells were drilled in 1942. This represents a decrease of 42.7 per cent from the 1941 total of 2110. Of the total wells completed, 553 (45.7 per cent) were oil wells with an average initial production of 443 bbl.; 102 (8.4 per cent) were gas wells with an average initial of 3,359,000 cu. ft.; and 555 (45.9 per cent) were dry. Although the number of completions declined sharply, the total of 320 wildcats completed (26.4 per cent of all wells) repre-sents a decrease of only 2.7 per cent from the previous year's figure of 329. Of the wildcats drilled, 44 (13.8 per cent) were oil wells, 13 (4.0 per cent) were gas wells, and 263 (82.2 per cent) were recorded as failures. Reconditioning of wells throughout the state resulted in a total recompletion of 355 wells. Of these, 234 were oil wells with a combined initial production of 96,808 bbl., 32 were gas wells with a total initial of 381,488,000 cu. ft., and 89 were abandoned. None of the 26 pools found in 1942 has developed into a major discovery. The Pauls Valley pool, Garvin County, is the most outstanding. Since its discovery in April, 14 wells with an average initial of 1898 bbl. have produced 803,000 bbl. of 42' gravity oil from the Bromide zone. Development in this pool is believed to be almost completed. Other of the more important discoveries are the East Watchorn pool, Pawnee County; Guthrie Townsite and West Navina, Logan County; Brooksville and Macomb, Pottawatomie County, and the Liberty and Northeast Lucien discoveries in Noble county. The East Watchorn pool, at the close of the year, had 14 completed oil wells with an average initial of 989 bbl. from the Wilcox sand at 3930 it.; Guthrie Townsite, one well with an initial of 840 bbl. from dolomite at 5600 It.; West Navina, six wells with an average initial of 284 bbl. in the Lay ton sand at 5050 ft., Brooksville, eight wells in the Hunton at 4800 ft. with an average initial 01 355 bbl.; Macomb, one well with an initial of 160 bbl. in the IIunton at 4700 ft.; the Liberty pool, one well with an initial of 1268 bbl. in the second Wilcox at 4500 ft., and two wells in the Tonkawa sand at 2500 ft., with an average initial of 230 bbl. In the Northeast Lucien pool, four wells were completed in the Wilcox at 5380 ft. for an average initial of 1164 bbl., and one well was completed in the Viola lime at 5255 ft. for an initial of 55 barrels.

Jan 1, 1943

By Raymond D. Sloan

Retaining third place in crude-oil production among the nation's oil-producing states, Oklahoma's output in 1942 totaled 137,792,000 bbl., a decline of 9.4 per cent from the previous year's total of 152,117,000 bbl. Production declined from an average of 403,000 bbl. daily in January 1942 to an average of 355,000 bbl. during December, a reduction of 48,000 bbl. daily (11.9 per cent) during the year. At the end of 1942 it would appear inevitable that the downward trend in production will continue in 1953 unless halted in the immediate future by greater than normal discoveries and development. To Jan. I, 1943, Oklahoma has produced 5,067,013,000 bbl. oil crude oil. Development and Exploration Development dropped abruptly in 1942, reflecting the lack of any sizable discoveries and the effect of the provisions of Federal Well Spacing Order M-68, which became effective in December 1941. In all, 1210 wells were drilled in 1942. This represents a decrease of 42.7 per cent from the 1941 total of 2110. Of the total wells completed, 553 (45.7 per cent) were oil wells with an average initial production of 443 bbl.; 102 (8.4 per cent) were gas wells with an average initial of 3,359,000 cu. ft.; and 555 (45.9 per cent) were dry. Although the number of completions declined sharply, the total of 320 wildcats completed (26.4 per cent of all wells) repre-sents a decrease of only 2.7 per cent from the previous year's figure of 329. Of the wildcats drilled, 44 (13.8 per cent) were oil wells, 13 (4.0 per cent) were gas wells, and 263 (82.2 per cent) were recorded as failures. Reconditioning of wells throughout the state resulted in a total recompletion of 355 wells. Of these, 234 were oil wells with a combined initial production of 96,808 bbl., 32 were gas wells with a total initial of 381,488,000 cu. ft., and 89 were abandoned. None of the 26 pools found in 1942 has developed into a major discovery. The Pauls Valley pool, Garvin County, is the most outstanding. Since its discovery in April, 14 wells with an average initial of 1898 bbl. have produced 803,000 bbl. of 42' gravity oil from the Bromide zone. Development in this pool is believed to be almost completed. Other of the more important discoveries are the East Watchorn pool, Pawnee County; Guthrie Townsite and West Navina, Logan County; Brooksville and Macomb, Pottawatomie County, and the Liberty and Northeast Lucien discoveries in Noble county. The East Watchorn pool, at the close of the year, had 14 completed oil wells with an average initial of 989 bbl. from the Wilcox sand at 3930 it.; Guthrie Townsite, one well with an initial of 840 bbl. from dolomite at 5600 It.; West Navina, six wells with an average initial of 284 bbl. in the Lay ton sand at 5050 ft., Brooksville, eight wells in the Hunton at 4800 ft. with an average initial 01 355 bbl.; Macomb, one well with an initial of 160 bbl. in the IIunton at 4700 ft.; the Liberty pool, one well with an initial of 1268 bbl. in the second Wilcox at 4500 ft., and two wells in the Tonkawa sand at 2500 ft., with an average initial of 230 bbl. In the Northeast Lucien pool, four wells were completed in the Wilcox at 5380 ft. for an average initial of 1164 bbl., and one well was completed in the Viola lime at 5255 ft. for an initial of 55 barrels.

Jan 1, 1943

By John V. Beall

Early this year at the University of Arizona in Tucson, a survey was made of student opinion about the minerals industry. Over 100 of the three page questionnaires were completed and these were analyzed by the following categories: 40 Mining Engineering students, 20 Geological Engineering with 2 Geophysical Engineering students, 15 Geology students, 7 Metallurgical Engineering, 26 Underclassmen, 29 Graduate students and a composite of 84 total students. Not all of the results of the survey were predictable. After graduation there is a strong preference toward going to work in the mineral industries. The next most popular options, but trailing the first choice greatly, was graduate work or employment in another industry. A smattering of other choices were for teaching, government or research. None checked the box for drop out.

Jan 1, 1971

By Allan D. Taylor

INTRODUCTION From the designer's view, the installation starts with the first definition of the orebody, and progresses through a long and complex development. The design is affected not only by the characteristics of the ore, but by all of the personalities and events of the project during its development. The following discussion attempts to touch on the most important aspects which define the context in which the designer must work in apply the do's and don'ts. That context is the basis of the viewpoint. WHAT CAN GO WRONG The Project Is Going Over Budget This is a common and serious concern to the plant designer. The Project Falls Behind Schedule Another common and disturbing condition with which the plant designer must cope. Some Equipment Fails to Perform This can be due to either faulty equipment or operating deficiencies. It can be the result of a wide variety of causes, but the designer will be an interested party in the search for the cause and the cure. The Plant Isn't Flexible Enough Sometimes a plant will handle some or even most of the ore satisfactorily but is unable to treat another type properly. This can be a significant problem. An example might be a case where low capacity of a cyclone feed pump makes it impossible to accompany an increase in grinding mill throughput with a corresponding increase in dilution water. This could lead to an increase in cyclone feed density, and a loss in product grade or a limit on the plant capacity. Spillage And Cleanup Are Excessive This is one of the most common and annoying defects in metallurgical plants, and one for which the designer can rarely delegate blame. Maintenance Is Excessive Another common complaint in new plants, and also one for which the dedesigner must accept most of the responsibility.

Jan 1, 1982

By Charles A. Stetefeldt

This treatise is the sequel of a paper on "Russell's Improved Process for the Lixiviation of Silver-ores," etc., read at the Chicago meeting, in May, 1884, and published in the Transactions, vol. xiii., page 47. The facts it presents are principally compiled from Mr. Russell's notes on his practical experience gained in various places where the Russell process has been introduced. For a complete understanding of this paper a perusal of my former one is desirable, as can be seen from the frequent references here made to it. All silver-ores that do not carry a large percentage of lead or copper can be treated by Russell's process with success and economy. I do not mean to create the impression that from ores containing considerable quantities of lead and copper a high percentage of the silver cannot be extracted by this process. Such ores, however, will, in many localities, be reduced to better advantage by smelting. In case lead-bearing silver-ores are suitable for concentration, it may be profitable to concentrate the ore by Krom's dry system, obtaining a smelting-product high in lead, and to lixiviate the tailings and the dust. This plan has been adopted in a mill recently erected in Cortez District, Nevada. The dry system of concentration deserves the preference because it delivers the tailings and the dust in a condition ready for chloridizing-roasting. In wet concentration the drying of the tail ings would be expensive, and there would be a considerable loss of silver in slimes. Oxidized ores, containing silver chloride and lead minerals, may be lixiviated after crushing, and the tailings may be concentrated for lead. In this case wet concentration would be most suitable. This has been done at the Old Telegraph Mine, Utah. I would give, however, the preference to dry concentration in all cases which, of course, requires that concentration should precede lixiviation. The Russell process is also adapted to the treatment of tailings resulting from ores which have been worked either by the old

Jan 1, 1887