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By Albert Sauveur

Floris Osmond, Honorary Member of the American Institute of Mining Engineers, born in Paris, March 10, 1849, died at Saint-Leu near that city, June 18, 1912. Taken suddenly ill with congestion of the brain while on his way from Paris to his home, he reached it in time to write on the typewriter his last wishes, one of which was that no biographical notice of his life should be published. Holding Osmond's memory sacred, as those who have known him will, is it our duty to conform with his desire ? Shall no mention be made in our Transactions of the beautiful life and great achievements of one of our most honored members? Is it not, on the contrary, incumbent upon us to disregard Osmond's instruction in this matter and to place on record our admiration for the nobility of his life, for his talents and for the importance of his work, that younger men may be inspired by it with a desire to be guided by worthy motives in the path of unselfish pursuits ? I cannot feel that in following this course I am disloyal to Osmond's memory and I am strengthened in this belief by the opinion of men of high honor whom I have consulted before undertaking the writing of this obituary notice. One of them, Professor Henry M. Howe, justifies my decision better than I could do it myself when he writes : " Let us look frankly at the matter. Here we have a most extraordinary life, a life of rare beauty and power of inspiration to the rest of mankind. In my opinion we should not deprive mankind of the stimulating influence of the example of M. Osmond simply because he shrank from publicity. Our young men see every day how greed and vulgar push succeed, and with what material rewards they are crowned. They see too rarely the more valuable crown which comes to self devotion. A permanent and public recognition of the beautiful qualities of Osmond's life cannot fail to appeal to the imagination of young men and to help to deflect them toward leading a noble rather than a sordid life. Therefore I feel that the Revue de Métallurgie and other bodies owe it to the public to give prominence to his career by means of biographical notices."

Jan 1, 1914

By Thomas W. Dawson

THE H. C. Frick Coke Co. has used belt conveyers for handling coal for the last eighteen years but, until recently, only for small tonnage and over short distances. The first installations were outside the mines for distributing coal to various parts of plants. A belt conveyer was put in service at Colonial No. 4 Mine in November, 1906, to carry coal from the main hoisting shaft to a storage bin serving two blocks of beehive ovens on the other side of the valley; it was in constant service until the Colonial No. 4 ovens were abandoned less than a year ago. This conveyor was in an overhead gallery that spanned our sidings and yard tracks and the main line of the Pennsylvania Railroad. It was a crude installation, from the viewpoint of present conveyor engineering practice. It had no mechanical feeding device, the coal simply ran through a gate in the side of a bin on to the belt; but one belt on this conveyor lasted eleven years. This conveyor is about 300 ft. long center, to center of pulleys. It operated at a speed of 250 ft. per min. and carried about 400 tons per day. On this basis, the belt life of eleven years means that not over a million and a quarter tons were carried by the belt. While this is not a large tonnage, the cost per ton was much less than by any previous method in use for supplying coal to ovens located at a distance from the main shaft. The next belt conveyor was installed at Bridgeport Mine in 1907. It carried about the same daily tonnage as the first, delivering from the hoisting shaft to a coke-oven bin. Very few data were kept on this conveyor. It also operated until the coke ovens at the plant were put out of blast and the coal taken to the Clairton byproduct plant by river. In 1916, work was started to equip the Bridgeport, Palmer, Gates, and Ronco mines to load their entire output on, the river for transportation to the Clairton byproduct plant, which was then being built. These mines were all operating at that time and had a large area of coal available for river shipment. The Monongahela Railroad was located between the hoisting shaft and the river at each of these plants and,, therefore, had to be crossed at each location to deliver coal to the river.

Jan 6, 1925

By F. C. Sturges

For some time mining engineers have been interested in the possibility of using small diameter shafts, sunk by core drilling, as aids to ventilation and as emergency escapeways. The possibilities are interesting to contemplate, but new methods involve unknowns, and interest tends to remain passive until these unknowns are, solved. Recently we have completed two 36-in. diam core drilled shafts, and wish to make the data on these available to the industry. Both shafts were drilled for the McLain Fire Brick Co., one at its Buckeye mine and the other at its Colonial mine. Both mines are in the fireclay underlying the Lower Kittanning coal. Both mines have been in operation for a number of years and have required expensive maintenance work on return airways. It was decided that considerable savings could be effected by short-circuiting the air to the surface through small shafts. It was also realized that these holes, located near the present workings, would be of added value as emergency escapeways. Originally, 48-in. diam shafts were considered, but actual computations showed 36-in. diam shafts were more than ample at both mines. The shaft at the Buckeye mine is 240 ft deep, and that at the Colonial mine 258 ft deep. Both holes were started in the lower part of the Conemaugh formation and penetrated Conemaugh and Allegheny strata. The holes were started through the unconsolidated materials overlying bedrock by constructing a concrete collar with a wall thickness of 8 in. Then the shafts were drilled by the shot-core drill method. An annular groove was cut in the rock by the abrading action of chilled steel shot run under the shoe of the core barrel. The drilling was done in stages, the core barrel drilling the groove for a certain distance depending on conditions encountered, and then the cores broken off and taken out in sections. The core barrel had a 36-in. o.d. and the finished diameter of the shaft measured almost 37 in. The major questions that could not be answered until the completion of the first shaft were, (I) how much ground water would be encountered, how would it hinder the drilling, and how difficult would it be to seal off, and, (2) how would the walls of the hole stand up. The holes of course could .be cased or lined, but that is considerable added expense in any shaft.

Jan 1, 1949

By F. L. Bosqui

Discussion of the paper of F.* L. Bosqui, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 101, May, 1915, pp. 997 to 1033. SIDNEY J. JENNINGS, New York, N. Y.-I notice Mr. Bosqui says that zinc dust can be used profitably. I had occasion recently to try to ship some zinc deist to South Africa, owing to the. high price of zinc in the last six or eight months and the difficulty in getting zinc sheets We were informed that the steamship companies in England refused to accept zinc dust for shipment through the tropics on the score that it was an explosive mixture. C. W. MERRILL, San Francisco, Cal.-In the early days zinc dust was packed in wooden casks. The steamers at that time were very chary of transporting it. It was put on the deck in the wooden casks, and if the zinc dust got wet it exploded. Since that time we have used hermetically sealed cases, in which case there is no risk whatever in its transportation.. This rule of the steamship companies is perhaps another sample of their ultra-conservativeness. HENNEN JENNINGS, Washington, D. C.-Unfortunately, I have not yet read Mr. Bosqui's paper, but believing it might interest you to know something of the beginning of the cyanide process on the Rand, I will speak briefly as to my own knowledge and experience of the early initiation of this process in South Africa. I took the position of consulting engineer of H., Eckstein, the parent firm of H. Eckstein & Co., and a branch of the firm of Wernher, Belt ,C Co., at Johannesburg, in December, 1889, and at that time the Robinson Co. managed by them was the premier company of the fields. Up to this date plate amalgamation and catchment of a small percentage of concentrates by blankets, and in a few instances Frue vanners, were the main gold-saving devices used and had obtained an extraction' of only about 65 per cent of the gold contents of the ore. Also at that time the orebodies were seen to be changing from oxidized deposits to pyritic at varying depths from 50 ft. to 300 ft. below the surface, and uneasiness was felt as to future recovery. The deepest exploitation at any of the mines was not much below 300 ft.

Jan 12, 1915

Jan 1, 1904

By C. E. Schwab

A lead-zinc orebody, in fairly strong quartzite and with a dip of 35" to 60°, is block-caved by use of scrams in a stair-step pattern up the ore footwall. Scram linings to handle coarse muck and permit the use of folding scrapers are developed by the use of end-grain wooden blocks to reduce maintenance and keep operating cost to a minimum. THE Bunker Hill mine, since its discovery in 1885, has steadily produced a high grade of lead-silver-zinc ore. By the end of 1952 over 21,000,000 tons of this high-grade ore had been produced by square-set mining, and reserves in the mine continue to be very satisfactory both as to quantity and grade. For many years prior to 1941, mine production and mill capacity had been 1200 tons of feed per day. Closely adjacent to the mill, and stored behind dikes, coarse jig tailings had been impounded during the time preceding the advent of fine grinding and selective flotation. When manpower became short in 1941 and sink-and-float preconcentration was proved successful, mill capacity was increased to 1800 tons per day to treat these jig tailings economically. By 1946, because the supply of jig tailings was limited, underground exploration was started to discover and prove ore reserves of low-grade material which could be mined by an appropriate bulk mining method. During the years of square-set mining many possible areas of low-grade mineralization had been observed. One chosen for the first exploration work was sufficiently remote from active mining areas so that subsidence, if an ore-body were proved, would cause no problem. Also, old adits and workings were still open and in good enough condition so that exploration in the mineralized zone could be started with a minimum of preparatory work. In 1948 an orebody was proved of sufficient tonnage, of a grade about 2 pct Zn, 0.5 oz Ag, and 1.0 pct Pb. It was decided to use block-caving, the only appropriate mining method by which this grade of ore could be economically recovered. Exploration for additional reserves in other areas of the mine is continuing, but ultimate results are not known at this time. With more sink-and-float capacity, larger ball mills, and more flotation machines, mill capacity was increased to 3000 tons per day, permitting the mining of ore in the square-set area at a maximum rate not usually achieved, because of the scarcity of labor. Increased mill capacity also permits block caving and the mining of jig tailings at variable rates to keep mill feed up to 3000 tons per day. Fortunately the three types of feed are amenable to the same mill circuit and reagents for recovery of Pb and Zn. For example, during the first 10 months of 1952 square sets produced 827 tons per day, block-caving 1421 tons per day, and jig tailings 643 tons per day, an average daily production of 2891 tons for all three products. Exploration had proved the existence of an ore-body 1000 ft long and 165 ft wide in horizontal section, see Fig. 1. Company engineers were concerned only with the vertical extension, about 300 ft, from an old level to the surface. Much of this almost outcropped, Fig. 2. The ore lies in the hanging wall of a major fault of the Bunker Hill mine, standing at 65" in one end of the zone and separated from the fault by a wedge of waste, see Fig. 3. This wedge pinches out near the center of the zone, at which point the ore dips 45", lying nearly on the fault, Fig. 4. The remaining portion lies on the fault and conforms to the fault dip of 35", Fig. 5. Open-pit mining for the top of the ore was considered, but since the ore zone dipped into and under the mountains, adverse waste-to-ore ratios precluded use of this method. The ore occurs in massive quartzite of sufficient strength to support untimbered drifts, crosscuts, and raises. Zones of weakness in the quartzite are bedding, jointing, and small faults or slips. The mineralization, which occurs as small stringers of sphalerite and galena as well as pyrite, creates another line of weakness. The mineral veins or veinlets in themselves are high-grade. Their size and regularity and the amount of barren quartzite by which they are separated determined the limits of mineable ore, which are all assay limits except for the one determined by the major fault. Block 1 Without any background of caving in this type of quartzite, engineers selected the first block on the very steep end of the zone. Compelling reasons prompted this decision. The steep portion of the ore in Block 1 was of the lowest grade, so that if difficulties were encountered no very valuable ore would be lost, while the experience gained might be applied in mining the remaining blocks. A block 200x200 ft was laid out, with four scrams spaced 50 ft apart for drawing and placed at a right angle to the strike. Finger raises were placed in a 25-ft interval grid pattern, with flat undercutting done by crosscuts at the undercut level 25 ft above

Jan 1, 1954

By Waldemar F. Dietrich

Mineral fillers are relatively inert chemically under the conditions of use but have physical properties* that modify those of the materials in which they are incorporated. The mineral fillers considered in this article are asbestos, barite, clays, diatomite, crushed limestone, limestone whiting and lime, mica, silica, talc and soapstone, and pyrophyllite. Slate and stone, other than limestone and its derivatives, are excluded because, even though used in large quantities, they are exceptionally low-cost materials generally produced close to the area where they are used.

Jan 8, 1959

By W. Hurst, A. F. van Everdingen

A distillate-bearing sand complex is often made up of sand stringers of different permeabilities. In order to take into account the influence of the different permeabilities, "parallel flow" is defined, and this concept is used to compute the recovery efficiency of recycling such a sand complex. In the first approximation the position of the wells with respect to one another is not considered. In order to compute the effect on the recovery efficiency of the position of the wells, the area of a field is considered to be made up of rectangles; each rectangle containing one input well in the center and two producers located symmetrically with respect to the input well. Formulas are given from which to obtain the pressure and streamlines in a steady-state flow. A method is devised to compute rapidly the successive positions of the dry gas front. If the field is irregular in shape, pressure and streamlines can be obtained by a potentio-metric electrical model study. By using the concept of "parallel flow" and the results obtained by mathematical analysis or by electrical model study for a homogeneous formation, the effects of different permeabilities and of the location of the wells can be established. From these studies it is apparent that the efficiency of recycling can be profoundly influenced by differences in permeability among the various parallel strata. Introduction With the discovery of an increasing number of gas-distillate fields in the Gulf Coast, engineers have had occasion to give more thought to the performance of these reservoirs, as evidenced by the literature published in recent years. In the majority of studies published so far the formations are considered to consist of uniform, homogeneous sand. In this paper the authors wish to bring out the effect of variations in the permeability of the formations on the over-all recovery efficiency of wet gas in cycling operations. The importance of the permeability profile is clearly indicated by the fact that in gas cycling, highly permeable stringers in an otherwise tight sand can allow complete displacement of wet by dry gas in these stringers long before the wet gas in the tight portions of the sand is displaced. This by-passing will be reflected by a reduction in the condensate content of the production sooner than can be anticipated from a mathematical analysis or an electrical model study on uniform sands. Electrical model studies or mathematical analyses cannot take into consideration the manifold variations of permeability within the reservoir. Experimental as well as analytical difficulties make it necessary to consider the prototype for either of these studies as a perfectly uniform sand. Mathematical analyses are applicable only when a reservoir can be divided into units of simple geometrical form, of uniform thickness throughout. Electric model studies are capable of giving information on reservoirs of any shape or thickness, but it is essential that the sand be considered homogeneous, so that three-dimensional flow can take place. The method of approach in the following

Jan 1, 1946

By W. Hurst, A. F. van Everdingen

A distillate-bearing sand complex is often made up of sand stringers of different permeabilities. In order to take into account the influence of the different permeabilities, "parallel flow" is defined, and this concept is used to compute the recovery efficiency of recycling such a sand complex. In the first approximation the position of the wells with respect to one another is not considered. In order to compute the effect on the recovery efficiency of the position of the wells, the area of a field is considered to be made up of rectangles; each rectangle containing one input well in the center and two producers located symmetrically with respect to the input well. Formulas are given from which to obtain the pressure and streamlines in a steady-state flow. A method is devised to compute rapidly the successive positions of the dry gas front. If the field is irregular in shape, pressure and streamlines can be obtained by a potentio-metric electrical model study. By using the concept of "parallel flow" and the results obtained by mathematical analysis or by electrical model study for a homogeneous formation, the effects of different permeabilities and of the location of the wells can be established. From these studies it is apparent that the efficiency of recycling can be profoundly influenced by differences in permeability among the various parallel strata. Introduction With the discovery of an increasing number of gas-distillate fields in the Gulf Coast, engineers have had occasion to give more thought to the performance of these reservoirs, as evidenced by the literature published in recent years. In the majority of studies published so far the formations are considered to consist of uniform, homogeneous sand. In this paper the authors wish to bring out the effect of variations in the permeability of the formations on the over-all recovery efficiency of wet gas in cycling operations. The importance of the permeability profile is clearly indicated by the fact that in gas cycling, highly permeable stringers in an otherwise tight sand can allow complete displacement of wet by dry gas in these stringers long before the wet gas in the tight portions of the sand is displaced. This by-passing will be reflected by a reduction in the condensate content of the production sooner than can be anticipated from a mathematical analysis or an electrical model study on uniform sands. Electrical model studies or mathematical analyses cannot take into consideration the manifold variations of permeability within the reservoir. Experimental as well as analytical difficulties make it necessary to consider the prototype for either of these studies as a perfectly uniform sand. Mathematical analyses are applicable only when a reservoir can be divided into units of simple geometrical form, of uniform thickness throughout. Electric model studies are capable of giving information on reservoirs of any shape or thickness, but it is essential that the sand be considered homogeneous, so that three-dimensional flow can take place. The method of approach in the following

Jan 1, 1946

By William A. Hustrulid

INTRODUCTION Prior to the mid-1970's, the U.S. Radioactive Waste Disposal Program was focused on salt deposits as the geologic medium of choice, almost to the exclusion of other rock types. These efforts are illustrated by the Project Salt Vault experiment in a salt mine at Lyons, Kansas, in 1965-1967 followed by attempts to locate a repository site in central Kansas. Preliminary evaluation of other geologic media led, in 1978, to the GAIN (Geotechnical Assessment and Instrumentation Needs for Nuclear Waste Isolation in Crystalline and Argillaceous Rocks) Symposium held at the University of California (Berkeley), for the purpose of preparing a state-of-the-art document together with research needs for some of the other possible rock types. Because possible sites had not been selected, nor would they be for some time, the primary emphasis was for research and development focused on generic rocks and generic sites. A basic ground rule at that time was that the host rock formation should provide the primary containment for the waste. Also, the U.S. Nuclear Regulatory Commission (NRC) was just drafting the proposed rules regarding site suitability so that this input was not available. The collection of baseline data, conduction of some critical experiments both in the laboratory and field, and the performance of scoping studies were deemed needed. Such work was indeed undertaken; and to date, a great deal of information has been compiled and much has been learned regarding the characteristics of rock masses, rock behavior

Jan 1, 1984

By L. W. McKeehan, W. C. Elmore

The magnetic powder method, long used for roughly mapping magnetic fields, has recently been refined1, "or investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter2 first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators:' have used Bitter's original technique, with slight modifications, to study the variation of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement ill the powder technique which led us to the discovery of a new effect throwing considerable light on the magnetic secondary structure of alpha iron4 and of nickel5 single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure. Specimens The following list describes the specimens used in the present investigation. Designation Description A1 Silicon ferrite furnished to us by Dr. W. E. Ruder, of the General Electric Co., for which lie gave the following typical analysis: C, 0.05; P, 0.038; S, 0.026; Mn, 0.15; Si, 3.24. Disk, 0.60 cm. diameter, about 0.05 cm. thick. By X-ray analysis angles between disk normal and [100] 75o, [0101 76" [00l] 21o. A2 Same as A1 except: diameter 0.75 cm. A, Same as A1 except: diameter 0.68 cm.

Jan 1, 1936

By L. W. McKeehan, W. C. Elmore

The magnetic powder method, long used for roughly mapping magnetic fields, has recently been refined1, "or investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter2 first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators:' have used Bitter's original technique, with slight modifications, to study the variation of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement ill the powder technique which led us to the discovery of a new effect throwing considerable light on the magnetic secondary structure of alpha iron4 and of nickel5 single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure. Specimens The following list describes the specimens used in the present investigation. Designation Description A1 Silicon ferrite furnished to us by Dr. W. E. Ruder, of the General Electric Co., for which lie gave the following typical analysis: C, 0.05; P, 0.038; S, 0.026; Mn, 0.15; Si, 3.24. Disk, 0.60 cm. diameter, about 0.05 cm. thick. By X-ray analysis angles between disk normal and [100] 75o, [0101 76" [00l] 21o. A2 Same as A1 except: diameter 0.75 cm. A, Same as A1 except: diameter 0.68 cm.

Jan 1, 1936

By K. V. S. Sastry

INTRODUCTION Flotation is by far the most important unit operation of mineral processing. Most of the common base metals are produced from flotation concentrates of metal sulfides. Flotation is proving to be a valuable process for producing non-metallic minerals such as ceramic oxides, silicates, clays and phosphate fertilizers. All these fltation separations are carried out on materials which are predominantly in the 10 to 100 micronssize range. The present practice of flotation circuits for the production of large tonnages of metallic and non-metallic mineral concentrates is fairly well understood, developed, and standardized. Two kinds of problems are encountered (1, 2) with fine particles smaller than 10 microns. First is the interference of the fine particles with the flotation of the coarser particles and the second is the poor flotation behavior of fine particles. In general, these problems are handled either by eliminating, minimizing, or ignoring the fines in the flotation circuit feed. In recent years, however, a considerable number of experimental and theoretical studies have been carried out to understand the flotation behavior of fine particulates. This literature is summarized in four review papers (2-5). Application of the conventional flotation techniques for the separation of mineral fines is known to be uneconomical, and to present several scientific and technological problems (1-5). The objective of this presentation is to examine the flotation behavior of fine particles in terms of their physical-chemical properties and to review the potential techniques of fine particle flotation. Specific reference to the problem areas and research needs will also be included in the discussion.

Jan 1, 1979

By C. W. Purington, H. B. C. Nitze

The Kotchkar mining-district, known as the Kotchkar System, is situated in the Orenburg government, in Eastern Russia, in the great plateau- or steppe-country immediately adjacent to the eastern slopes of the Ural mountains. Its longer dimension is north and south about 27 miles, while in the widest (northern) portion the distance across is 22 miles. The district lies 40 miles southwest of Miass, a station of the Trans-Siberian railway, and half-way between this village and that of Troitsk. It contains also the not inconsiderable settlements of Kotchkar and Eosobrodskoit., the last a Kossak town. So far as explored, the district is known to contain from 300 to 400 auriferous veins. ? Although the topography is generally of an exceedingly flat character, the country is traversed by several small rivulets running from west to east, and flowing into the Sanarka and Kamenka rivers. Since 1844 placers have been worked in the district, but it was not until 1867 that veins were discovered, and these have been worked only since the impoverishment of the alluvial deposits. The deposit with which this paper especially deals is known as the Ouspensky mine, one of twelve owned by MM. de Zelenkoff & Cie., five of which are situated in the Kotchkar System. An opportunity of visiting this mine was afforded the writers, in eonnection with an excursion of the VII. session of the International Geological Congress; held in Russia during the summer of 1897. The mine is reached by a 40-mile '(troika" journey from the railway station of Bichkil, itself

Jan 1, 1899

By W. F. Guenther

The usual hand-operated drilling outfit consists of a 4-in. post-hole auger with 3/4,-in. pipe for drill stem, in 4-ft lengths, with a turning handle fitted to a top pipe T. The auxiliary tools are: a chisel-bit drill made from 3/4 or 7/8-in. tool steel welded to a 4-ft length of 3/4-in, pipe, so that the regular pipe string can be used; also a churn or "mule foot" made from 3-in. pipe, slotted on one side, belled to a 4-in. tempered cutting edge on the bottom, all welded to a 3/4-in. coupling by a yoke. Other tools required are pipe wrenches and cleanout tools made from old auto springs (Fig I). A 4 1/2 or 5-in. collar welded to a plate is often used to protect the mouth of the drill hole. In general the auger is used in the typical clay overburden and brown phosphate matrix, which is relatively soft. The churn or "mule foot1' is used in hard pan, lump phosphate or cherty ground. The drill is used for breaking flint, often found loose in the overburden. The drill with the chisel bit is used for trimming sides of the hole, sounding for lime bottom and breaking through hard lumps. Holes have been drilled to a depth of 80 ft, but the limit of efficient operation is about 50 ft. In deep holes it is necessary to unscrew the string in 20-ft lengths, to

Jan 1, 1948

By W. F. Guenther

The usual hand-operated drilling outfit consists of a 4-in. post-hole auger with 3/4,-in. pipe for drill stem, in 4-ft lengths, with a turning handle fitted to a top pipe T. The auxiliary tools are: a chisel-bit drill made from 3/4 or 7/8-in. tool steel welded to a 4-ft length of 3/4-in, pipe, so that the regular pipe string can be used; also a churn or "mule foot" made from 3-in. pipe, slotted on one side, belled to a 4-in. tempered cutting edge on the bottom, all welded to a 3/4-in. coupling by a yoke. Other tools required are pipe wrenches and cleanout tools made from old auto springs (Fig I). A 4 1/2 or 5-in. collar welded to a plate is often used to protect the mouth of the drill hole. In general the auger is used in the typical clay overburden and brown phosphate matrix, which is relatively soft. The churn or "mule foot1' is used in hard pan, lump phosphate or cherty ground. The drill is used for breaking flint, often found loose in the overburden. The drill with the chisel bit is used for trimming sides of the hole, sounding for lime bottom and breaking through hard lumps. Holes have been drilled to a depth of 80 ft, but the limit of efficient operation is about 50 ft. In deep holes it is necessary to unscrew the string in 20-ft lengths, to

Jan 1, 1948

By J. H. Anderson, G. A. Parks, B. K. Jindal

Both temperature and humidity are important variables in electrical separations. By independent control of temperature and water vapor pressure, it is shown that charge depends primarily upon relative humidity, not on temperature or water pressure alone. All the effects of temperature changes other than modification of humidity are apparently small. However, humidity control can be achieved through manipulation of the more tractable variable, temperature. Both temperature and humidity are important variables in electrical separations. Some of their effects have been described in general by Fraas1,2 and by Ralston.3 The influence of temperature and humidity may be considered a problem in industrial separations because humidity, especially, is not normally controlled, hence leads to unpredicted quality control problems. The problem is significant whether the separation is based on conductivity differences or on contact electrification. There is no doubt that water adsorbs from humid atmospheres onto mineral surfaces resulting in conductivity changes.'-8 An empirical relationship between conductivity and humidity is1.4-6,8 where a and b are constants peculiar to the substrate, and s and h are the conductivity and relative humidity respectively. Some authors have taken advantage of differences in a and b among minerals to make or propose electrodynamic separations in which h is the key control variable. Fraasl,2 reported that the charge developed on quartz and feldspar through contact with aluminum is sensitive to humidity, as illustrated schematically in Fig. 1. Lawver9 found that the charge developed by quartz on contact with several materials was tem-

Jan 1, 1967

By John F. Allan

This paper does not pretend to advance any facts or improvements not known to many members of the Institute, but is intended merely to give a few practical hints on preliminary tests, and to call attention to a possible enlarged field for the cyanide process in the treatment of some silver-ores, which merits investigation. Broadly considered, the choice of a process for the treatment of silver-ores in Mexico is confined to the following alternatives: (1) Concentration for treatment by smelting; (2) milling and pan-amalgamation; (3) the patio and Ortega process; [4) chloridizing roast and lixiviation; (5) chloridizing roast and cyaniding; and (6) cyaniding of the crude ore. These methods of treatment may also be combined, and cyaniding or concentration, or both, may be introduced, at what-ever stage it is found to be most advantageous. The characteristics of the ore (especially its gold-content) and local conditions, such as distance from railway, cost of fuel, amount of water available, vary so much that it is impossible to make general comparisons between the different processes, either as to extraction or cost. Concentration and subsequent smelting may be made very expensive by long-distance transportation of concentrates; pan-amalgamation is undoubtedly expensive; and the patio process is barred when the ore contains appreciable amounts of gold, by reason of its poor extraction of that metal; yet there are many ores for which each of these processes is especially adapted, and the expense of treatment is compensated by the results obtained.

Jan 1, 1905

By Frederick Laist

Introduction IN a leaching process, having obtained the copper in solution, the choice of the precipitation method is influenced y the following factors: 1. Availability of precipitant. 2. Adaptability to the leaching process. 3. Final product desired. 4. Regeneration of leaching solutions. 5. Fouling of solutions. There are three general classes of precipitation methods: 1. The use of iron, scrap or sponge. 2. Electrolytic deposition. 3. The use of some gas or reagent y which the copper is obtained, usually in the form of an intermediate precipitate which requires further treatment. For example, the precipitation of the copper as Cu2Cl2 from chloride solutions, with SO2 gas. The use of iron is adapted to almost any process. It has the great advantage of extreme simplicity, and the recovery of the copper and any values present in a highly concentrated, easily treatable form. The disadvantages are the cost in isolated places, the uncertainty of the scrap-iron market, and the fouling of the leaching solutions. The latter is a serious factor, When a reagent such as salt is used in them, which makes necessary their re-use. Where applicable, electrolytic deposition is very attractive. The copper is obtained in a form directly marketable, there is a regeneration of acid amid no fouling of solutions. Unfortunately, chloride solutions do not lend themselves to electrolysis. An entirely satisfactory anode material has not yet been discovered, although magnetite, apart from being rather brittle, seems to answer the requirements fairly Well.

Jan 7, 1914

By W. P. Heineken, A. T. Child

This paper presents the results of a series of experiments made in the metallurgical laboratory of Columbia University, New Pork City. The object of the investigation was to determine, as far as possible, the changes in micro-structure and physical properties caused by short periods of heat-treatment and the longer malleable cast-iron process. It was proposed to do this by means of micro-photographs, heating- and cooling-curves, and tensile tests after the various heat-treatments. I. Micro-Constituents of Iron and Steel. The list of the micro-constituents of iron and steel has grown till now it includes seven different substances, called ferrite, cementite, pearlite,* martensite, austenite, sorbite and troosite. Only the first five of these are mentioned in this paper, to facilitate the understanding of which, the following brief definitions are given: 1. Ferrite (named by Prof. Howe) is, chemically, iron free from carbon. It is the softest of the constituents, and is not colored by etching, except when long-continued. Under the microscope it is easily determined by its regular polygonal etructure; or, if structureless, as in malleable cast-iron, by the ease with which it is scratched. Ferrite appears in mild steel in small amount, in grey cast-iron, and in malleable cast-iron. 2. Cementite (also named by Prof. Howe) is now generally conceded to have the formula Fe3C. It is the hardest of the micro-constituents, having the hardness indicated by 7 of the mineralogical scale; and hence it is always left in relief after

Jan 1, 1901