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By David LeCount Evans

Not only E. B. Mayo but also W. C. Lacy, who apparently urged the preparation of this analysis, is to be commended. Regional thinking of this type is needed to assure future success in the never-ending search for new mineralized and petroliferous districts. As is usually the case, here is a regional study that will be read by the mining geologist alone. It is ironic that several of the trends established in this study have suggested themselves in northern mid-continent, detailed, and regional studies. These, where established, have offered new keys to petroleum exploration and have provided a possible basis for unraveling a number of broad generalities. The oil geologists, active in Colorado, Kansas, and Oklahoma, would find much food for thought in Mr. Mayo's projections.

Jan 6, 1959

By Donald L. Anderson

Presence of hot water brought on by volcanic action nearby has severely complicated mining in the Limon gold mine in Nicaragua. Routine pumping problems have been multiplied and ventilation is a major problem. Enclosing rock is so hot that 20 pct of all power generated at the mine is consumed by forced ventilation. But hot water underground, however disagreeable and troublesome, may be handled and surmounted like any other difficulty if the estimated profit margin permits. Empresa Minera de Nicaragua's Limon mine is a 400-ton gold-silver producer located in western Nicaragua about 60 miles northwest of the capital city, Managua, and some 45 miles from the Nicaragua-Honduras border. Limon is situated in a low- lying district with a nearby chain of active and semi-active Tertiary volcanoes.

Jan 6, 1959

By Corale L. Brierley

An unidentified, high-temperature microbe, which oxidizes reduced sulfur and iron in an acid medium between 45° and 75°C, is studied to determine its ability to leach copper sulfide minerals and molybdenite. Copper is leached from low-grade ore as well as a chalcopyrite concentrate, and preliminary data indicate a tolerance of 1.0 gpl copper by the microbe. A molybdenite concentrate is also biogenically leached, and the microbe is able to continue growth when the soluble molybdenum concentration is 750 ppm. Molybdenum can not be biogenically extracted from waste material using the present technique. Direct observation using SEM illustrates colonial growth and developmental characteristics of the microbe on molybdenite fines. The organism responds to hexavalent molybdenum by reducing this metal to the pentavalent state in aerobic and nitrogen gas atmospheres.

Jan 1, 1974

By L. R. Flint, W. L. Freyberger, W. J. Howarth

W. L. Freyberger (Director, Institute of Mineral Research, Michigan Technological University, Houghton, Mich.)-The authors are to be complimented on their theoretical analysis of a column flotation process, and the comment I wish to make is not related to that analysis, but to the use of the word "countercurrent" to describe that process. Strictly speaking, the process the authors have described is countercurrent only in the sense of particle-bubble contact. That is, as solid particles and air bubbles pass through the column, the leanest flotation feed (the tailing) comes in contact with the greatest concentration of mineral-free bubbles. However, air bubbles alone do not comprise the complete extracting phase in a flotation system. A second component of this extracting phase is the collector, which is really the extractant inducing transfer of mat-

Jan 1, 1972

By A.A. Gustafson

In diamond or churn drilling for the prospecting of ore bodies, two products can be used for quantitative analyses; i.e., the core and the cuttings, or sludge. Some operators prefer an assay of core; others insist that the sludge be sent for analysis. Both must recover the sludge for check samples or for assays if there is no core recovery for any particular section of the diamond-drill hole. The Freeport Sulphur Co. found that numerous cumbersome sludge boxes or barrels were inconvenient and delayed drilling. The sludge settled slowly in the ordinary shallow, rectangular diamond-drill boxes and its total removal from the container was difficult, time-consuming and unsatisfactory; and sampling of deposits of which the metal contents are easily concentrated, as in ores containing cinnabar, gold and silver, is subject to error if the boxes are not thoroughly cleaned. Mr. Charles Ballard, dredge superintendent at Freeport's operation at Grande Ecaille, Louisiana, developed a portable cone while he was in charge of prospecting a mercury property near Tonopah, Nevada, in 1940. Ballard later improved the design while the settler was being used at a manganese property in New Mexico. The operation is based on the "free settling" of comminuted particles in a quiescent liquid. The ordinary sludge box discharges over a lip 8 to 12 in. wide and consequently the water has sufficient velocity so that the discharge water is never clear. The cone settler used by Free-port Sulphur Co. discharges over the entire circumference, which gives a discharge ltp of 9 ft. in the size of cone used at the cinnabar and manganese prospects. Consequently, the velocity of the discharge water is slow enough so that all fine material settles and the discharge water is clear. When the drilling of a sample interval is complete, the sludge can be drawn off by the time the driller is ready to cut another sample. Thus, only one cone is needed per drill. The cone has been used by Freeport successfully in churn-drilling a manganese deposit, in diamond-drilling a mercury deposit, and in diamond-drilling a deposit of ore containing tin, copper, gold and silver. The cone is greatly superior to the old methods of collecting sludge and is now used on all Freeport drilling campaigns in the western states, both for surface and underground drilling. Fig. I shows the important details of a cone designed for average operating conditions, 30 in. in diameter and 36 in. high. Abnormal conditions may require some revisions in design. Fig. 2 shows a working drawing. A hose or pipe larger than the one used to convey water from the pump to the swivel head of the string of rods is connected to the stuffing box at the collar of a diamond-drill hole, The usual T-connection is used. It is not necessary to use a stuffing box if the top of the cone can be placed lower than the collar of the hole. Then the return water and cuttings can be made to flow by gravity. This hose or pipe discharges the cuttings of the drill bit and the return

Jan 1, 1943

By A. A. Gustafson

IN diamond or churn drilling for the prospecting of ore bodies, two products can be used for quantitative analyses; i.e., the core and the cuttings, or sludge. Some operators prefer an assay of core; others insist that the sludge be sent for analysis. Both must recover the sludge for check samples or for assays if there is no core recovery for any particular section of the diamond-drill hole. The Freeport Sulphur Co. found that numerous cumbersome sludge boxes or barrels were inconvenient and delayed drilling. The sludge settled slowly in the ordinary shallow, rectangular diamond-drill boxes and its total removal from the container was difficult, time-consuming and unsatisfactory; and sampling of deposits of which the metal contents are easily concentrated, as in ores containing cinnabar, gold and silver, is subject to error if the boxes are not thoroughly cleaned. Mr. Charles Ballard, dredge superintendent at Freeport's operation at Grande Ecaille, Louisiana, developed a portable cone while he was in charge of prospecting a mercury property near Tonopah, Nevada, in 1040. Ballard later improved the design while the settler was being used at a manganese property in New Mexico. The operation is based on the "free settling" of comminuted particles in a quiescent liquid. The ordinary sludge box discharges over a lip 8 to 12 in. wide and consequently the water has sufficient velocity so that the discharge water is never clear. The cone settler used by Freeport Sulphur Co. discharges over the entire circumference, which gives a discharge lip of 9 ft. in the size of cone used at the cinnabar and manganese prospects. Consequently, the velocity of the discharge water is slow enough so that all fine material settles and the discharge water is clear. When the drilling of a sample interval is complete, the sludge can be drawn off by the time the driller is ready to cut another sample. Thus, only one cone is needed per drill. The cone has been used by Freeport successfully in churn-drilling a manganese deposit, in diamond-drilling a mercury deposit, and in diamond-drilling a deposit of ore containing tin, copper, gold and silver. The cone is greatly superior to the old methods of collecting sludge and is now used on all Freeport drilling campaigns in the western states, both for surface and underground drilling. Fig. I shows the important details of a cone designed for average operating conditions, 30 in. in diameter and 36 in. high. Abnormal conditions may require some revisions in design. Fig. 2 shows a working drawing. A hose or pipe larger than the one used to convey water from the pump to the swivel head of the string of rods is connected to the stuffing box at the collar of a diamond-drill hole. The usual T-connection is used. It is not necessary to use a stuffing box if the top of the cone can be placed lower than the collar of the hole. Then the return water and cuttings can be made to flow by gravity. This hose or pipe discharges the cuttings of the drill bit and the return

Jan 1, 1943

By A. A. Gustafson

In diamond or churn drilling for the prospecting of ore bodies, two products can be used for quantitative analyses; i.e., the core and the cuttings, or sludge. Some operators prefer an assay of core; others insist that the sludge be sent for analysis. Both must recover the sludge for check samples or for assays if there is no core recovery for any particular section of the diamond-drill hole. The Freeport Sulphur Co. found that numerous cumbersome sludge boxes or barrels were inconvenient and delayed drilling. The sludge settled slowly in the ordinary shallow, rectangular diamond-drill boxes and its total removal from the container was difficult, time-consuming and unsatisfactory; and sampling of deposits of which the metal contents are easily concentrated, as in ores containing cinnabar, gold and silver, is subject to error if the boxes are not thoroughly cleaned. Mr. Charles Ballard, dredge superintendent at Freeport's operation at Grande Ecaille, Louisiana, developed a portable cone while he was in charge of prospecting a mercury property near Tonopah, Nevada, in 1940. Ballard later improved the design while the settler was being used at a manganese property in New Mexico. The operation is based on the "free settling" of comminuted particles in a quiescent liquid. The ordinary sludge box discharges over a lip 8 to 12 in. wide and consequently the water has sufficient velocity so that the discharge water is never clear. The cone settler used by Free-port Sulphur Co. discharges over the entire circumference, which gives a discharge ltp of 9 ft. in the size of cone used at the cinnabar and manganese prospects. Consequently, the velocity of the discharge water is slow enough so that all fine material settles and the discharge water is clear. When the drilling of a sample interval is complete, the sludge can be drawn off by the time the driller is ready to cut another sample. Thus, only one cone is needed per drill. The cone has been used by Freeport successfully in churn-drilling a manganese deposit, in diamond-drilling a mercury deposit, and in diamond-drilling a deposit of ore containing tin, copper, gold and silver. The cone is greatly superior to the old methods of collecting sludge and is now used on all Freeport drilling campaigns in the western states, both for surface and underground drilling. Fig. I shows the important details of a cone designed for average operating conditions, 30 in. in diameter and 36 in. high. Abnormal conditions may require some revisions in design. Fig. 2 shows a working drawing. A hose or pipe larger than the one used to convey water from the pump to the swivel head of the string of rods is connected to the stuffing box at the collar of a diamond-drill hole, The usual T-connection is used. It is not necessary to use a stuffing box if the top of the cone can be placed lower than the collar of the hole. Then the return water and cuttings can be made to flow by gravity. This hose or pipe discharges the cuttings of the drill bit and the return

Jan 1, 1943

By David H. Browne, John F. Thompson

The literature dealing with the physical constants of nickel is so fragmentary and unrelated that a synopsis presents unusual difficulties. It is only within the last few years that investigators have understood the importance of placing on record not only the determinations they have made but also the composition, physical treatment, and past history of the material investigated. For this reason much of the earlier literature is valueless. Determinations have been made of the same physical constants on samples differing widely in origin, composition, and treatment, and the results differ widely among themselves. In the first place nickel is almost as flexible a term as steel. Its physical properties are widely influenced by its composition and treatment. It absorbs large quantities of gases and is exceedingly difficult to prepare in a state of chemical purity comparable to gold, silver, or copper. It is vitally affected by thermal and mechanical treatment. Hence in the following pages the recorded literature, where quoted, must be accepted with a certain reserve and used, as far as possible, as a check on later observations, in which these important factors are noted. In every case where new determinations are given, an attempt has been made to record all available information concerning the composition and treatment of the material used so that the data may serve as stepping-stones toward a wider knowledge of the properties of the metal. As this synopsis is an attempt by men of metallurgical training to do what should long before have been done by physicists, it is to be expected that certain errors may have crept in. Any corrections or suggestions

Jan 1, 1921

By C. S. Barrett

WhEN a collimated beam of protons or other energetic particles is scattered by a single crystal, the emerging particles produce patterns that contain much crystallographic information. Calculations of the trajectories of individual particles can predict with reasonable accuracy the complete pattern (which is related reciprocally to channeling, now studied in detail6) but the task is a lengthy one which has been completed for very few cases. A many-beam dynamic diffraction calculation of the patterns would be even more difficult and in some cases may be invalid. Because of these complexities, simple methods that will predict to a rough approximation the relative intensities of the lines in films of the back-scattering patterns of a given crystal are wanted. I have found a method which, although it is not a valid computation of intensities or of film darkening by either dynamic or kinematic diffraction principles or by trajectory calculations, nevertheless is found to be useful in practice. It has been tested on several crystal types,7 and is here tested on additional ones. The method consists in first calculating the structure factor F(hk1) for the (hkl) plane, of spacing d, by the familiar equation: where the summation extends over the atoms in the unit cell and fj is the atom scattering factor of the jth atom (using tables computed for electron diffraction, preferably those computed without exchange). Then the F values are squared and summed over all the orders, n, for which F2 has an appreciable value, giving a quantity: Finally, I, is expressed as a percentage of Ic for the

Jan 1, 1970

By Richard E. Chism

SAN DIMAS, in the State of Durango, Mexico, on the frontier of the State of Sinaloa, is the centre of an extensive and rich mining region, which has been exploited for over a hundred years; and the patio process for working silver ores has there attained the highest perfection of which it is capable. Local modifications have been engrafted upon the underlying principles of the process, but, as a whole, the San Dimas practice so fully illustrates its typical capabilities, that I have undertaken to describe its workings in the hope of lightening, to some degree, the labors of my professional brethren who may have occasion to visit Mexico." As is tolerably well known, the patio process, like all other systems of free amalgamation, is not successful with ores containing more than a trace of zinc or lead, the presence of zincblende being especially obnoxious. Iron and copper in small quantities are not particularly disadvantageous. The process succeeds very well with all sulphide ores which do not contain much more than a trace of arsenic and antimony, provided the tailings are concentrated, although, of course, it is best adapted for free milling ores. For suitable silver ores that contain small amounts of free gold the process is still a good one, but where the gold is combined with sulphurets, a considerable and even an excessive loss is inevitable. Hitherto the Mexicans have submitted to this loss, but, since the introduction of American mills, they are gradually abandoning the patio process in favor of the other. The San Dimas ores have a gangue of quartz and feldspar. They are composed principally of silver sulphides, with some chloride and

Jan 1, 1883

By George Gardner

THE application of wet cleaning processes for the beneficiation of bituminous coal has created in some localities a problem in the recovery and disposal of fine solids in the washery water. The maximum allowable concentration of these solids in the washery circuit that is consistent with satisfactory operation of the cleaning units remains a controversial point. It has, however, been generally recognized for a number of years that some degree of control should be exerted over the concentration of such material. Early methods of control involved intermittent or continuous dis-charge of a portion of the plant slurry into near-by streams or settling ponds, and this persisted even after the adoption of settling tanks or cones. The practice is not always economical, for two reasons: first, because of the waste of coal, and, second, because it is sometimes difficult and expensive to obtain an adequate supply of water. The latter condi-tion often is aggravated by chemical treatment of the make-up water that is necessary to prevent excessive corrosion of plant equipment. The modern approach to this problem has been the adoption of continuous thickening devices. However, because such equipment occupies consid-erable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, there-fore often the performance of such units is not altogether satisfactory. In recent years, European washeries have increased the rate of settling of the fine coal from the slurry by the addition of specially pre-pared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation.

Jan 1, 1939

By Frank R. Milliken

SCOPE THIS paper is a running commentary on metallurgical problems and developments, stressing ilmenite flotation, since the start of operations five years ago, at the mill of National Lead Company, Titanium Division, Maclntyre Development, Tahawus, New York. [ ] GENERAL In early 1941, when, world conditions threatened to cut off the supply of ilmenite (obtained largely from India) to this country, the National Lead Company started to develop and bring into production their Maclntyre Development. This operation supplied the bulk of the ilmenite used during the war period for the manufacture of the much needed titanium pigments. Maclntyre Development is at Tahawus, New York, on the headwaters of the Hudson River in the center of the scenic Adirondack Mountains. A general description of the operation was given in the Adirondack Issue of Mining and Metallurgy for November 1943. Operating tonnages and production have increased since 1943, however. Nearly 10,000 tons of ore and waste is broken and loaded daily in the open-pit mine. About half of this tonnage is ore, from which is produced nearly 800 tons of ilmenite concentrate and 1600 tons of magnetite concentrate daily. ORE-TYPES From an ore-dressing standpoint, there are five rather distinct ore types and two waste-rock types in the mine. The ore types are shown in Table 1. The anorthosite waste is a coarse-grained white rock, largely labradorite feldspar. The gabbro waste is generally finer grained, and contains, in addition to feldspar, 35 to 75 pct iron silicates such as hornblende, pyroxene, garnet and biotite. A minor mineral mineralogically, but important metallurgically, is apatite. A few calcite

Jan 1, 1947

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metaliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land the surface of which is suitable for agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar" method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years ago, has become valuable agricultural land dotted here and there with growing towns. Frequent references. will be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are equally applicable to all coal-mining states. Briefly stated, the question: is "Does the owner of the substrata or underlying mineral owe any duty of surface support to the owner of the superjacent strata or surface?" There is no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1927

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metaliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land the surface of which is suitable for agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar " method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years .ago, has become valuable agricultural land dotted here and there with growing towns. Frequent references will be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are equally applicable to all coal-mining states. Briefly stated, the question is "Does the owner of the substrata or underlying mineral, owe any duty of surface support to the owner of the superjacent strata or surface?" There is no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1927

By George Gardner

THE application of wet cleaning processes for the beneficiation of bituminous coal has created in some localities a problem in the recovery and disposal of fine solids in the washery water. The maximum allowable concentration of these solids in the washery circuit that is consistent with satisfactory operation of the cleaning units remains a controversial point. It has, however, been generally recognized for a number of years that some degree of control should be exerted over the concentration of such material. Early methods of control involved intermittent or continuous dis-charge of a portion of the plant slurry into near-by streams or settling ponds, and this persisted even after the adoption of settling tanks or cones. The practice is not always economical, for two reasons: first, because of the waste of coal, and, second, because it is sometimes difficult and expensive to obtain an adequate supply of water. The latter condi-tion often is aggravated by chemical treatment of the make-up water that is necessary to prevent excessive corrosion of plant equipment. The modern approach to this problem has been the adoption of continuous thickening devices. However, because such equipment occupies consid-erable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, there-fore often the performance of such units is not altogether satisfactory. In recent years, European washeries have increased the rate of settling of the fine coal from the slurry by the addition of specially pre-pared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation.

Jan 1, 1939

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metalliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land of which the surface is suitable for agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar" method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years ago has become valuable agricultural land dotted here and there with growing towns. Frequent references will be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are applicable to all coal-mining states. Briefly stated, the question is "Does the owner of the substrata or underlying mineral owe any duty of surface support to the owner of the superjacent strata or surface?" There is -no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1928

By M. Gensamer

THE PURPOSE OF THIS PAPER is to lay a foundation of elementary theory that might be useful in the discussions which it is hoped will be evoked during this Symposium. It is not my purpose to try to expound the details of the most complete theories as that would be impossible in the time at our disposal and, even if time were available, would probably be of less usefulness than a discussion of the principles underlying the advanced theoretical treatment. I shall try to discuss the fundamental bases for these advanced theories. There exists at the present time very much less need for a detailed description of complete theory than existed when this Symposium was being organized. The reason for this is that a series of papers by L. R. Underwood has been appearing in the magazine Sheet Metal Industries. It is understood that this series will he published soon in the form of a book. Dr. Underwood's articles are complete, critical and well written and it would be hopeless to try to do better in less space. The need, then, is for a brief treatment of basic theory. The objective of any theory of plastic forming- is to enable one to calculate the force and power requirements for the process, and where the deformation is not uniform, to calculate the distribution of strains- In the formed object. We need as the basis for the calculation the relationship between stress and strain in the metal, particularly for the combination of stresses imposed by the forming process. We need to know the stress-strain curve for some simple state of stress, and we need in addition some theory

Jan 1, 1948

By D. L. Katz

The critical phenomena have been studied during the past century but our knowledge of the critical temperatures and pressures of complex hydrocarbon mixtures still is very limited. The critical temperatures and pressures of pure substances have been examined in large num-bers,20 and in great detail.11,17 No experimental determinations of the critical phenomena have been reported on such complex hydrocarbon systems as a reservoir fluid. The critical temperature is defined by Taylor18 as follows: "there is some temperature for each gas above which the gas cannot be liquefied. This temperature is called the critical temperature." The critical pres-sure of a pure substance is the vapor pressure at the critical temperature. It should be noted that these definitions refer to a given substance in the pure state and do not mean that the pure substance cannot be liquefied in the presence of a second constituent. The normal procedure for obtaining the critical temperature of a substance is to heat it in a glass tube 1,20 under pressure until the meniscus between the liquid and vapor phase disappears, although other methods, especially for mixtures, have been used. 11,14 However, when considering oil and gas reservoirs, it is more enlightening to consider a critical phe-nomenon that occurs when a mixture of oil and gas are compressed at a reservoir temperature until the meniscus disappears because the two phases become equal in composition. This conception, along with erroneous applications of the definition of the critical phenomena of a pure substance to that pure substance when it is part of a complex mixture, has caused confusion even among persons familiar with the classical theories.

Jan 1, 1938

By John Dilworth

IN considering the valuation of industrial properties in general, and of developed coal properties in par-ticular, it is assumed as fundamental that they have but one true value regardless of the object for which they are appraised. As regards developed coal lands, this value is only very approximately indicated by the recent sale price of neighboring lands, for the reason that it is rarely possible to find a sale of a coal property sufficiently similar in essential mining conditions to the one under consideration to serve as a measure of its value; and if such a one is found there are frequently incidental conditions peculiar to this particular transaction which invalidate the use of the sale price as a measure of general values. The true measure of the value of a coal mining opera-tion is the amount and rate of earnings it will afford with intelligent and experienced management. Prac-tically all of the features of a property which are gen-erally recognized as affecting its value relate either to the cost of producing the coal, or to the price it will bring, and so are intimately associated with earnings. In practice it is customary to appraise those portions of a developed coal property which are produced -by the industry of man-mine plant, equipment, development, town, etc.-at their cost of replacement at prevailing prices of materials, machinery, and labor, with such deductions for age, condition, obsolescence, and lack of usefulness as conditions warrant. Surface is appraised at the estimated cost of similar land in the district. Coal value is the difference between the worth of the entire property; considered as an industrial unit and

Jan 9, 1927

By Frank R. Milliken

This paper is a running commentary on metallurgical problems and developments, stressing ilmenite flotation, since the start of operations five years ago, at the mill of National Lead Company, Titanium Division, MacIntyre Development, Tahawus, New York. In early 1941, when world conditions threatened to cut off the supply of ilmenite (obtained largely from India) to this country, the National Lead Company started to develop and bring into production their MacIntyre Development. This operation supplied the bulk of the ilmenite used during the war period for the manufacture of the much needed titanium pigments. MacIntyre Development is at Tahawus, New York, on the headwaters of the Hud- son River in the center of the scenic Adirondack Mountains. A general description of the operation was given in the Adirondack Issue of Mining and Metallurgy for November 1943. Operating tonnages and production have increased since 1943, however. Nearly 10,000 tons of.ore and waste is broken and loaded daily in the open-pit mine. About half of this tonnage is ore, from which is produced nearly 800 tons of ilmenite concentrate and 1600 tons of magnetite concentrate daily. Ore—types From an ore-dressing standpoint, there are five rather distinct ore types and two waste-rock types in the mine. The ore types are shown in Table I. The anorthosite waste is a coarse-grained white rock, largely labradorite feldspar. The gabbro waste is generally finer grained, and contains, in addition to feldspar, 35 to 75 pct iron silicates such as hornblende, in garnet and biotite. A minor mineral mineralogically, but important metallurgically, is apatite. A few calcite

Jan 1, 1949