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Michigan State Department of Conservation, Lansing, Mich The Department of Conservation has two divisions issuing publications which should be listed in this directory. Geological Survey Division. R. A Smith, State Geologist Land Economic Survey Division L R Schoenmann, Head. A price list of publications of either division will be sent upon request to that division Geological Survey Division.-Citizens of Michigan may obtain publications of this Division on payment of forwarding charges Prices to others for available publications are given below: Vol 5 (1881-1884): Pt 1, Geological report of the Upper Peninsula of Michigan, by L L Hubbard, pt 2, Geology of Lower Michigan with reference to deep borings, by A C Lane, $125. Annual Report for 1908. Pt b, Geological section of Michigan, by A C. Lane and A E Seaman, 50 cents. Publication No 5, The Late Glacial and Post Glacial Uplift of the Michigan Basin, and earthquakes in Michigan, by W. H

Jan 1, 1933

By Louis A. Panek

INTRODUCTION AND SUMMARY With respect to the geomechanics aspects, the primary technical objectives in mining by an undercut-cave method are to achieve a controlled, sustained caving of the mineral body and to remove the fragmented ore with a minimum of dilution from surrounding unmineralized rock, while maintaining stability or control of the rock structure around the access openings. The structurally ideal ore body probably does not exist. If the rock mass is so weak as to cave on a short span, it may tend to be too sticky for easy drawing and handling, or create special problems in regard to support of the access openings. If the ore is strong, caving may be difficult and the caved fragments may be of such a large size as to require special equipment for transferring the ore from the caved zone. Given enough time and money to generate data and conduct trials, engineering and ingenuity can devise an appropriate combination of mine layout, sequence of extraction, and mechanical equipment to achieve a technically successful caving extraction operation to meet the foregoing requirements in many types of deposits. The large capital investment involved, however, reduces the freedom to make major changes once the mine development is well under- way, and the penalties for failure to accurately anticipate operating conditions militate against selecting any but the most obvious candidates for mining by an undercut-cave method. The demonstrated capability to extract large, deep, economically marginal deposits by this low-cost, high-volume method of mining provides an incentive to develop a rationale for predicting the cavability and stability characteristics of a deposit prior to mining, so that the undercut-cave method may be extended to a much wider range of mineral deposit characteristics. The ultimate goal is to establish as explicitly as possible the quantitative interrelationships between the measured rock-mass characteristics, the caving span, the size distribution of caved ore fragments, and the sizes and locations of stable access openings. Lacking an understanding of these relation- ships, a designer may readily change some factor in the wrong direction (e.g., excessively reduce the distance between the extraction level and the undercut to increase the convenience of operations for the undercutting crew, increasing the frequency of repairs to the extraction-level support system) or create unnecessary problems elsewhere in the system by introducing a design change that can achieve only minimal improvement in the factor of direct interest (e.g., unnecessarily complicate the ore-transfer system by changing the orientations of the openings, with- out succeeding in the objective of improving the ground support conditions). Although successful predesign is the prime objective, subsequent modifications in mine lay- out and sequence of extraction operations are inevitable. In developing the modified solution, systematic experimentation based on an understanding of the underlying structural relationships, coupled with monitoring measurements of selected diagnostic structural-behavior parameters, can achieve an acceptable solution in a minimum number of steps, which is far superior to the typical operational trial-and-error approach, in view of the cost of implementing each successive change. Since a drill-core sample of ore rock from a successful undercut-cave operation may exhibit a uniaxial crushing strength in excess of 100 MPa, the caving of such a rock mass is now commonly believed to be ascribable to the presence of discontinuities such as joints or fractures throughout the ore body. An essential part of the present investigation was therefore to characterize the natural discontinuities at each of the test sites by measuring their attitudes and spacings. The term "fracture" is used herein in a general sense to include any planar discontinuity without implication as to its suggested mode of origin. Most, but not all, of the fractures are properly termed joints. As a point of departure we may consider the possibility that the rock mass is transected by three families of joints, each family possessing a distinct orientation, such that parallelepipeds of intact rock are delineated by the jointing. Even if cementation is absent between adjoining parallelepipeds, the undercutting of the rock mass will not necessarily initiate sustained caving--owing to the all-around confinement, an arch may tend to stabilize over the undercut unless prevented from doing so by the failures of key blocks of intact rock. Thus, although the jointing can be assumed to weaken the rock mass, creating preferred directions of

Jan 1, 1981

YEAR OF ELECTION 1913 FRANK DAWSON ADAMS Montreal, Canada 1921 WILLIAM CUTHBERT BLACKETT Sacnston, Durham, England 1920 HENRY STURGIS DRINKER Merlon Station, Pa 1921 FERDINAND FOCH Paris, France 1922 FEDERICO GIOLITTI Torino, Ttaly 1888 HATON DE LA GOUPILLIERE Paris, France 1906 SIR ROBERT A HADFIELD London, England 1921 FRANK WILLIAM HARBORD London, England 1921 HEINRICH O HOFMAN Cambridge, Mass 1917 HERBERT HOOVER Stanford University, Cal 1919 ROBERT W HUNT Chicago, ILL 1915 JAMES' FURMAN KEMP New York, N Y 1905 HENRI LECHATELIER Paris, France 1921 C MCDERMID London, England 1913 EZEQUIEL ORDONEZ Mexico City, Mexico 1909 ALEXANDRE POURCEL Paris, France 1911 ROBERT H RICHARDS Boston, Mass 1906 JOHN E STEAD Middlesbrough, England 1907 CHARLES D WALCOTT Washington, D C

Jan 1, 1923

By Albert G. Zima

According to recently puhlished statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year. Were it not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed. Today, however, through the application of scientific drilling methods and the adaptation of modern equipment and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet. Drill Tools Modern rotary drilling tools are the product of ingenious design and careful selection and adaptation of materials used in their construction. They must withstand terrific abrasion and, because of their compactness, must be designed to resist exceedingly high unit stresses. In bits, core drills and reamers, the bodies are made of either forged or cast alloy steels, heat-treated to develop a combination of high strength and toughness. To provide sufficient strength to the threaded portions and to protect the threads from distortion or damage, the box or pin sections of the tools are hardened to approximately 310 to 330 Brine11 hardness number. Drill and reamer cutters are generally of the movable type; i.e., serrated cones, cylinders or disks, which can readily be replaced when

Jan 1, 1935

By Albert G. Zima

According to recently puhlished statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year. Were it not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed. Today, however, through the application of scientific drilling methods and the adaptation of modern equipment and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet. Drill Tools Modern rotary drilling tools are the product of ingenious design and careful selection and adaptation of materials used in their construction. They must withstand terrific abrasion and, because of their compactness, must be designed to resist exceedingly high unit stresses. In bits, core drills and reamers, the bodies are made of either forged or cast alloy steels, heat-treated to develop a combination of high strength and toughness. To provide sufficient strength to the threaded portions and to protect the threads from distortion or damage, the box or pin sections of the tools are hardened to approximately 310 to 330 Brine11 hardness number. Drill and reamer cutters are generally of the movable type; i.e., serrated cones, cylinders or disks, which can readily be replaced when

Jan 1, 1935

By G. L. Oldright

THE metallurgist is familiar with the rapid development of concentration -by flotation and smelting in the reverberatory in recent years, brought 'about chiefly by the exhaustion of' bodies of .rich, coarse, direct smelting ore. Geologically speaking, in many porphyry-copper districts, the richer contact or replace let deposits surrounding 'the main ore-forming igneous intrusion have been exhausted, and it is necessary to beneficiate the copper minerals disseminated throughout the mass of the intrusion itself. The organization of great companies to treat such low- grade ores on a large scale and the practices resulting from the necessity for an economic method of treatment 'are among the most prominent metallurgical developments of the past decade. It is interesting to note the effect of the present trend of practice on the inter-relationship of the concentrator and smelter, on the constituents of the smelter charge, and on smelting in general.

Jan 1, 1925

E. A. H. Tays, San Blas, Sinaloa, Mex. (communication to the Secretary*):—The results obtained by Messrs. Hofman and Hayward in their experiments, proving that a low percentage of copper sulphate with a variable percentage of salt, depending on the ore, gives the best results, confirm practical mill-work which I did in 1895. I have none of my notes, taken at the time, to refer to, so have to rely solely on memory, which precludes the conciseness that is alway desirable. In 1894 I took charge of the plant of the San Rafael Company, near Chinipas, Chihuahua, Mex., which at that time was treating a very refractory ore carrying about $15 in gold and from 20 to 25 oz. of silver per ton, the bullion being about 300 fine in gold. The silver in the ore was in the form of a sulphide. Although carrying an average of 0.75 oz. of gold per ton, free gold could rarely be seen by panning, but upon roasting a sample of the ore the gold became visible at once—a result which was discovered by chance and used to advantage later. In order to utilize the old mill to the best advantage, it was decided to use pan-amalgamation after roasting. The roasting, done in a lime-kiln, was similar to the ordinary " burning " operation. The roasted ore was trammed to the mill-bins and crushed by 10 stamps to pass a 30-mesh screen. The pulp was de-watered and fed to four 1-ton pans. My recollection is that upon starting the mill-work, the charge contained 1.5 lb. of copper sulphate and 5 per cent. of salt per ton. From the start the extraction was unsatisfactory and the loss of quicksilver was very large. Experiments were then carried out on a working scale. First, the quantity of copper sulphate was increased 4 oz. at a time; then it was reduced

Jan 1, 1910

By H. S. Rankin, E. C. Houston

OLIVINE is considered a valuable potential source of metallic magnesium in the chloride electrolytic process. Treatment of olivine with hydrochloric acid can be carried out under conditions that prevent the formation of gelatinous silicic acid, which would inhibit the reaction by forming a covering around the ore particles. It is our hypothesis that the formation of gelatinous silicic acid is avoided by the dehydrating action of the magnesium chloride, which takes up water to form a series of hydrates and leaves the silicic acid in granular condition. Leaching serves to separate the magnesium chloride from the silicic acid and unattacked ore, which can be treated with fresh acid in successive steps until extraction is essentially complete. The leach solution can be purified by the addition of caustic magnesia and the precipitated impurities removed by decantation or filtration. The resulting magnesium chloride contains: Fe, less than 0.001 per cent; Mn, 0.012 per cent; Ni, none. Chlorinationt of olivine has two major defects: (I) a large part of the chlorine goes to form silicon and iron chlorides, (2) the anhydrous magnesium chloride is held by absorption in the finely divided silica. SUPPLY It is well known that olivine, a silicate of magnesium and iron, is present in large amounts in several localities in the United States. The largest deposits occur in the southeast and on the Pacific Coast.1 The southeastern deposits were surveyed by Lewis2 in 1896 and by Hunter3 in the period 1933-1940. It is estimated that high-grade olivine, conveniently located with regard to transportation and power, is present in excess of 230 million tons above local drainage level in western North Carolina and north Georgia. PREVIOUS TECHNICAL WORK In the past few years, olivine has attracted considerable attention in the refractory field. In the chemical processing industry, however, it has long been thought axiomatic that the cost of processing silicates is an economic barrier to their utilization, especially where more reactive minerals, such as carbonates, oxides or salts, are available. This attitude is not entirely justified in connection with olivine. Unlike most silicates, olivine is readily attacked by acids, chlorine and other reagents without resorting to fusion to break down the silicate structure. Olivine has been suggested as a raw material for making epsom salt by roasting with pyrites.4 Other processes include acid treatments and digestion with calcium chloride.6 Recently a small plant was built near Webster, N. C., for making epsom salt from olivine by treatment with sulphuric acid. This plant is now in commercial operation, producing approximately two tons per day. Olivine is also receiving attention from the fertilizer industry as an inexpensive source of soluble magnesium.

Jan 1, 1942

By A. B. Calhoun

These mines, which belong to the Burma Corporation, Ltd., formerly a London company now incorporated in Rangoon, Burma, are situated in the semi-independent state of Tawng-Peng, one of the small divisions comprising the northern Shan states and erroneously known as part of Upper Burma. Bawdwin is approximately 23' 6' N. latitude and 97" 20' E. longitude, 450 miles north of Rangoon, 169 miles northcast of Mandalay and 50 miles south and west of the Province of Yunnan, China (see Fig. 1). Although the mines were worked by the Chinese during the Ming Dynasty, 1412 A. D., the most extensive operations took place between 1796 and 1851, when the mines contributed largely to the silver market of China. During the reign of Tung Chik, 1868 A. D., they were abandoned partly because of the Mohammedan rebellion in Yunnan, which made life and property insecure, but largely because of the difficulty of operating the mines on account of water and poor ventilation. Since that time practically nothing was done, although the Burmese kings are said to have made several sporadic attempts to work the mines, until 1891 when Europeans were attracted by the great slag dumps (assaying about 40 per cent. lead) which the Chinese had left after extracting the silver. After a railroad and smelter had been built and 200,000 to 300,000 tons of slag smelted for lead, exploration work was started and old workings cleaned out in order to locate the remnants of the orebody that it was supposed the Chinese had left. After two years of most discouraging work, the remains of a large orebody was discovered by the Dead Chinaman Tunnel or what is the 171-ft., or No. 2 level adit. From then on the development was rapid and today the Chinaman is considered one of

Jan 1, 1923

By A. B. Calhoun

These mines, which belong to the Burma Corporation, Ltd., formerly a London company now incorporated in Rangoon, Burma, are situated in the semi-independent state of Tawng-Peng, one of the small divisions comprising the northern Shan states and erroneously known as part of Upper Burma. Bawdwin is approximately 23' 6' N. latitude and 97" 20' E. longitude, 450 miles north of Rangoon, 169 miles northcast of Mandalay and 50 miles south and west of the Province of Yunnan, China (see Fig. 1). Although the mines were worked by the Chinese during the Ming Dynasty, 1412 A. D., the most extensive operations took place between 1796 and 1851, when the mines contributed largely to the silver market of China. During the reign of Tung Chik, 1868 A. D., they were abandoned partly because of the Mohammedan rebellion in Yunnan, which made life and property insecure, but largely because of the difficulty of operating the mines on account of water and poor ventilation. Since that time practically nothing was done, although the Burmese kings are said to have made several sporadic attempts to work the mines, until 1891 when Europeans were attracted by the great slag dumps (assaying about 40 per cent. lead) which the Chinese had left after extracting the silver. After a railroad and smelter had been built and 200,000 to 300,000 tons of slag smelted for lead, exploration work was started and old workings cleaned out in order to locate the remnants of the orebody that it was supposed the Chinese had left. After two years of most discouraging work, the remains of a large orebody was discovered by the Dead Chinaman Tunnel or what is the 171-ft., or No. 2 level adit. From then on the development was rapid and today the Chinaman is considered one of

Jan 1, 1923

By L. D. Muller, C. P. Sayles

When minerals are mined in arid or semiarid areas where water is at a premium, dry processing is a natural route to take for concentrating or classifying the values. Until recently though, dry processing technique were limited by the lack of suitable equipment. With the advent of the pneumatic pinched sluice at Warren Spring Laboratory, Stevenage, Hertfordshire, England, a new tool emerged to fill this gap and it has the potential of providing industry with a high output concentrator or preconcentrator for dry natural ores and secondary materials. The pneumatic pinched sluice gives every indication of fulfilling these requirements with the added advantage that with homogeneous materials-such as crushed limestone or quartzose sands-it may alternatively operate as a high throughput dry classifier or sizing device. An industrial version of the equipment is now being manufactured by Dryflow Separators Ltd., as sole licensee for the National Re- search Development Corporation.

Jan 1, 1971

By S. W. Miller

During the examination of welds made in steel by the oxy-acetylene and electric-arc processes, the writer has met with some unusual structures, which he has not encountered elsewhere. They seem to be quite closely associated with the welding methods used, and characteristic of them, and would seem to be worth noting, especially as the references to them in the literature are few, and their explanation not clear or complete. An introductory word or two about fusion welding may not be out of place. The oxy-acetylene process is based on the great and very local heat generated by the burning of acetylene in the presence of commercially pure oxygen, the two gases being thoroughly mixed before combustion. The theoretical temperature is somewhat under 4000" C, but on account of various losses, the actual maximum temperature is probably about 3000" C.' The electric-arc process, using a metal electrode, which is also the filling rod, generates a still higher and more local temperature. The actual temperature of the positive crater of the carbon arc is given as 3500" C.2 NO figures have been found for the temperature of the arc using a metal electrode, but it would probably not be very different from that of the carbon arc, and probably higher than that of the bxy-acetylene flame. The greater localization of the electric arc is due to the fact that it is not surrounded by a large envelope flame, as well as to its higher temperature; while the oxy-acetylene white cone, or welding flame, in which the carbon of the acetylene is burned to CO, is surrounded and preceded by a long envelope flame, itself of quite high temperature, in which the CO is burned to GO2, and the hydrogen of the acetylene to H2O. This flame spreads around and over the pieces being welded, heating them to a further distance from the weld than does the electric arc.

Jan 1, 1918

By E. C. Houston, H. S. Rankin

Olivine is considered a valuable potential source of metallic magnesium in the chloride electrolytic process. Treatment of olivine with hydrochloric acid can be carried out under conditions that prevent the formation of gelatinous silicic acid, which would inhibit the reaction by forming a covering around the ore particles. It is our hypothesis that the formation of gelatinous silicic acid is avoided by the dehydrating action of the magnesium chloride, which takes up water to form a series of hydrates and leaves the silicic acid in granular condition. Leaching serves to separate the magnesium chloride from the silicic acid and unattacked ore, which can be treated with fresh acid in successive steps until extraction is essentially complete. The leach solution can be i purified by the addition of caustic magnesia and the precipitated impurities removed by decantation or filtration. The resulting magnesium chloride contains: Fe, less than 0.001 Per cent; Mn, 0.012 ; per cent; Ni, none. Chlorination† of olivine has two major defects: (1) a large part of the chlorine goes to form silicon and iron chlorides, (2) the anhydrous magnesium chloride is held by absorption in the finely divided silica. SupplY It is well known that olivine, a silicate of magnesium and iron, is present in large amounts in several localities in the United States. The largest deposits occur in the southeast and on the Pacific Coast.' The southeastern deposits were surveyed by Lewis2 in 1896 and by Hunter3 in the period 1933-1940 It is estimated that high-grade olivine, conveniently located with regard to transportation and power, is present in excess of 230 million tons above local drainage level in western North Carolina and north Georgia. Previous Technical Work In the past few years, olivine has attracted considerable attention in the refractory field. In the chemical processing industry, however, it has long been thought axiomatic that the cost of processing silicates is an economic barrier to their utilization, especially where more reactive minerals, such as carbonates, oxides or salts, are available. This attitude is not entirely justified in connection with olivine. unlike most silicates, olivine is readily attacked by acids, chlorine and other reagents without resorting to fusion to break down the silicate structure. Olivine has been suggested as a raw material for making epsom salt by roasting with pyrites.4 Other processes include acid treatment6 and digestion with calcium chloride.6 Recently a small plant was built near Webster, N. C., for making epsom salt from olivine by treatment with sulphuric acid. This plant is now in commercial operation, producing approximately two tons per day. Olivine is also receiving attention from the fertilizer industry as an inexpensive source of soluble magnesium.

Jan 1, 1942

By H. S. Rankin, E. C. Houston

Olivine is considered a valuable potential source of metallic magnesium in the chloride electrolytic process. Treatment of olivine with hydrochloric acid can be carried out under conditions that prevent the formation of gelatinous silicic acid, which would inhibit the reaction by forming a covering around the ore particles. It is our hypothesis that the formation of gelatinous silicic acid is avoided by the dehydrating action of the magnesium chloride, which takes up water to form a series of hydrates and leaves the silicic acid in granular condition. Leaching serves to separate the magnesium chloride from the silicic acid and unattacked ore, which can be treated with fresh acid in successive steps until extraction is essentially complete. The leach solution can be i purified by the addition of caustic magnesia and the precipitated impurities removed by decantation or filtration. The resulting magnesium chloride contains: Fe, less than 0.001 Per cent; Mn, 0.012 ; per cent; Ni, none. Chlorination† of olivine has two major defects: (1) a large part of the chlorine goes to form silicon and iron chlorides, (2) the anhydrous magnesium chloride is held by absorption in the finely divided silica. SupplY It is well known that olivine, a silicate of magnesium and iron, is present in large amounts in several localities in the United States. The largest deposits occur in the southeast and on the Pacific Coast.' The southeastern deposits were surveyed by Lewis2 in 1896 and by Hunter3 in the period 1933-1940 It is estimated that high-grade olivine, conveniently located with regard to transportation and power, is present in excess of 230 million tons above local drainage level in western North Carolina and north Georgia. Previous Technical Work In the past few years, olivine has attracted considerable attention in the refractory field. In the chemical processing industry, however, it has long been thought axiomatic that the cost of processing silicates is an economic barrier to their utilization, especially where more reactive minerals, such as carbonates, oxides or salts, are available. This attitude is not entirely justified in connection with olivine. unlike most silicates, olivine is readily attacked by acids, chlorine and other reagents without resorting to fusion to break down the silicate structure. Olivine has been suggested as a raw material for making epsom salt by roasting with pyrites.4 Other processes include acid treatment6 and digestion with calcium chloride.6 Recently a small plant was built near Webster, N. C., for making epsom salt from olivine by treatment with sulphuric acid. This plant is now in commercial operation, producing approximately two tons per day. Olivine is also receiving attention from the fertilizer industry as an inexpensive source of soluble magnesium.

Jan 1, 1942

By Beall, John V.

THIS is not simply the story of how a water filled shaft was developed into a million-ton- a-year producing mine in the space of four critical years, although it is reason enough for telling it, but it is also the saga of an engineering achievement in which knowledge nurtured by years of experience in coal and ore mines was blended together and the best from each type of mining selected. The entire system of mining was detailed on maps by the mining engineering department before the shaft was unwatered, and subsequent development followed these plans nearly to perfection. The selection of machinery was particularly critical as it was necessary to push production from only a few headings in the early stages of development and metal mine machinery was being used in a coal panel-system of mining. At the start of World War I1 the demand for iron ore to supply Woodward blast furnaces, and rapid exhaustion of the main source of Wood- ward ore, No. 3 Red Ore mine, necessitated speedy opening of the Pyne mine. The mine is three miles southwest of Bessemer and is responsible for 80 pct of Woodward ore, the rest coming from the Songo mine. The Woodward Iron Co. is one of the old producers of the Birmingham district. S. H. Woodward, an iron-master of Wheeling, overheard two Union soldiers conversing about ore and coal lands in Alabama, which lead to the acquisition of the first ore lands of the Woodward Co. in 1869. Development was not begun until after the death of S. H. Woodward; his two sons, W. H. Woodward and J. H. Woodward, formed the Woodward Iron Co. in 1881 and purchased a tract of land midway between the ore vein on the southeast and the coal field on the northeast about 12 miles southeast of Birmingham for the

Jan 1, 1950

By William H. Spice

Drilling activities in South Central Texas for the year 1945 continued the steady increase over the past two years, while new fields discovered for the year included four new gas fields and one field extension. In the 30 counties included in this area, which comprises district No. 1, Oil and Gas Division, Railroad Commission of Texas, 141 exploratory wells were completed, compared with 61 drilled in 1944 and 29 drilled in 1943. Of these 141 tests, 55 were field well and 86 were wildcats; 38 were completed as oil wells, S as gas and gas-distillate producers, and 95 were abandoned as dry. Atascosa and McMullen Counties were the most active in the district, accounting for 73 of the wells drilled.

Jan 1, 1946

By Hans Lundberg, Basil T. Wilson, H. Steuart Scott

FOR the benefit of those readers who may not be in close touch with present practices in the geophysical prospecting for ore, brief reference will fiat be made to the advantages and shortcomings of the methods to be discussed. Magnetic and electric methods are generally accepted as the most useful for ore prospecting. By magnetic methods, magnetic intensities that are not normal may be recorded and outlined. From these can he located concentrations of such highly magnetic minerals as magnetite or pyrrhotite, which sometimes occur in such large masses that they are of economic value in themselves. More often. however, these magnetic min¬erals are associated with others, such as copper, zinc, lead, gold, and silver, which, if existing in sufficient concentration and quantity, may constitute valuable ore bodies. It is therefore only when pyrrhotite and magnetite are present in these bodies that the magnetic method can be used to indicate their presence.

Jan 1, 1945

By G. K. Engelhart

A multi-stage counterflow process developed in Germany preheats dry pulverized portland cement raw materials held in suspension in rotary kiln waste gases. Capacity of the first kiln installed for this purpose in the United States has been increased from 860 to 1500 bbl per day, with fuel reductions from 1,100,000 Btu to 650,000 or 700,000 Btu per bbl. Sixty percent of total waste gas is used. As full use of the gas stream is approached, additional kiln production and fuel economy may be expected. EFFECTIVE use of rotary kiln waste gases to preheat dry pulverized materials has been demonstrated in full-scale operation at the Allentown Portland Cement Co. plant, Evansville, Pa. Pulverized raw materials are preheated in suspension in the gas stream in a multi-stage counterflow process which draws the gases through a series of cyclone collectors. Upon entering the first cyclone stage the material, continuously delivered and suspended in the gas stream, is successively collected and re-suspended until it discharges through the kiln feed pipe. Gas and material contact time is thus prolonged, providing a high degree of heat recuperation with a very low temperature differential between gas and material at the final stage. The suspension preheater, developed by Klock-ner-Humboldt-Deutz AG of Cologne, Germany, was first installed at the Norddeutsche Huette plant, Oslebshausen, Germany. Similar preheaters are now in operation at three other German cement plants. The first American installation, at the Allentown Portland Cement Co. plant, was designed and manufactured by Fuller Co. of Catasauqua, Pa., Humboldt's licensee for the United States, Canada, and Mexico. Design of this installation is essentially the same as the German original, but provision was made for varying the method to adapt the process to specific objectives of American portland cement production. Differences between German and American cement clinker production practices are directly related to differences in three primary production cost items: fuel, labor, and power. Because fuel costs are high in Germany and elsewhere in Europe, thermal efficiency has been the first objective of European cement producers and manufacturers of rotary kilns. The Germans have developed such recuperative equipment as the present suspension preheater, the Miag calcinator, and the Lepol kiln, the invention of 0. G. Lellep. In North America labor is the principal cost item, although rising fuel costs are of growing concern. High clinker production is therefore of first importance. Recent installations of longer dry process cement kilns have been disappointing, failing to make satisfactory reductions in exit gas temperatures when production is held at an acceptable level. The Humboldt suspension preheater satisfies both

Jan 1, 1955

By J. L. Jernegan

IN this paper I propose to give a short and, I must confess, a rather incomplete description, as regards many details, of the process used in Chicago, Ill., for smelting the argentiferous ores of the far West, and shall confine myself in this description, principally, to the process used at the Chicago Silver Smelting and Refining Company's Works, known as the Balbach process, as all the other smelting works in that city follow the same method, with the exception of one, which has the Cordurié, process for the desilverization of argentiferous lead. In all, there are five silver smelting and refining works in and near the city of Chicago. The Chicago Silver Smelting and Refining Company's Works are situated at the little station of South Lynne, about seven miles south from Chicago. The plant at these works consists of one horizontal steam-engine, principally used for running the ore pulverizer, four reverberatory smelting-furnaces, connected by horizontal flues with a common chimney 85 feet high, three lead-softening furnaces, one so-called zinc or mixing furnace, one separating furnace or liquation hearth, one lead-refining furnace, three zinc distillation retorts, one English cupellation furnace, supplied with blast by a No. 3 Sturtevant blower, which is run by a small steam-engine having a vertical tubular boiler, and an assay office, in which there are two wind-furnaces of the ordinary construction, and also a small muffle furnace. The assay office is supplied with all the necessary apparatus and reagents for fire assaying. There are also a superintendent's office, various store-rooms for coke and charcoal, and for the preparation of fire-clay, etc. Recently a small slag hearth (Krummofen) with one tuyere, has been put up for the purpose of working over such slags as assay too high in silver and lead to be thrown away, of which there are large amounts. The principal ore worked while I was in the employ of the company was that of the well known Emma mine in Utah, and also small quantities of Colorado ore. The character of the Emma ore is well known to most members of the Institute. In consists principally of ferruginous mixtures of carbonate and oxide of lead, oxide

Jan 1, 1874

Insoluble slimes are present in nearly all sylvinite ore bodies and must be removed prior to potash flotation because they adsorb excessive amounts of potash flotation reagents and cause low potash recoveries and grades. The problems associated with insoluble slimes will become more pronounced as high grade-low insol potash ores are depleted and lower grade ores containing high insols are processed. The most common commercial practice for insoluble slimes removal is mechanical desliming (hydroclassification); however, most of these desliming circuits were designed to treat sylvinite ores containing less than 4 percent insoluble slimes. As Mr. Banks mentioned in his presentation, higher insoluble slimes concentrations (>4 pct) in the mill feed overtax the mechanical desliming circuit and result in excessive brine and potash losses. Increasing the capacity of the circuit would require redesigning of the entire potash circuit and additional costly equipment. Because of mineralization and liberation properties of the high insols sylvinite deposits, the expansion of the desliming circuit may not economically maintain high potash grades and recoveries. Selective flocculation-flotation is an excellent alternative for removing insoluble slimes from potash ores. Cominco's ore, containing 4.5 to 8 percent insoluble slimes, is particularly amenable to the slimes flotation process, probably because of the absence of expanding-type clays such as montmorillonite. The overall potash recovery of 86 percent and low slime flocculant and collector dosages of 0.03 to 0.04 pound reagent per ton of feed is good evidence of the success of the process. If appreciable montmorillonite were present, the metallurgy would not be as favorable and reagent consumptions would increase significantly.

Jan 1, 1979