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By W. Julian Patron

TREATMENT of the breaker wash-water discharges to remove the suspended particles of finely divided material is usually most efficiently and economically accomplished in settling or thickening tanks. The purpose of these tanks is to separate the excess water from the solids by sedimentation whereby the solid particles suspended in the water are thickened by the force of gravity. The water overflowing these tanks is either reused for coal cleaning or discharged directly to the streams. The settled solids, which are in a relatively concentrated condition, forming a sludge or thick pulp, can be disposed of by pumping to a storage dam, by slushing into mine workings, by processing for recovery of coal, or filtering by vacuum or centrifugal means and discharging with the breaker refuse. The scope of this paper will be limited to the discussion of settling and thickening equipment, the factors that influence the settlement of solids, and a brief description of tests that can be made to determine the size of settling facilities required for any particular condition. The practical application of sedimentation to the treatment of coal falls into two groups, one of classification or hydro- separation, and the other of clarification and thickening. Classification may be employed to prepare a relatively low- grade fuel, which can be used as is or can be further processed separately. Clarification and thickening is employed where the primary objective is to recover a relatively dewatered solid and return a satisfactorily clear water to breaker or streams. When a stream of water flows across a tank, the time required for a particle to travel from the feed inlet to the overflow must be a little greater than that required for the finest particles or flocs in the feed to settle out of the stream. OPERATION AND TYPES OF SETTLING EQUIPMENT Theoretically, the liquid in a settling tank should rise at a more or less constant rate throughout the area of the tank Under these conditions the rising velocity of the water must be less than the settling rate of the finest particles if clarification is to be obtained. When classification of particles is to be made in the tank, the overflow velocity must be greater than the settling velocity of the particles that are to be removed with the tank overflow. The performance of a settling tank, then, depends on the settling rate of the solids and the current velocities in the tank. The oldest types of sedimentation employ intermittent types of settling tanks of any convenient shape. Means are provided for filling the tank with pulp and allowing it to settle until quiet, for moving the clean liquor and for removing the thickened sludge. The operation is necessarily intermittent but a sufficient number of tanks is employed so that a continuous flow of clear water is maintained. Continuous methods for the sedimentation of slurries were developed in the metallurgical industry. Cones from which settled solids were discharged by gravity

Jan 1, 1946

The earliest U. S. patent on a crushing machine was issued in 1830. The device incorporated the drop hammer principle later used in the famous stamp mill, whose history is so intimately linked with that of the golden age of American Mining. Eli Blake invented the first successful mechanical rock-breaker --the Blake jaw crusher--patented in 1858. The idea of his mechanical principle, the powerful-toggle linkage, was so sound that today the Blake -type jaw crusher is the standard by which all jaw crushers are judged. In 1881, Philetus Gates was granted a patent on a machine which included in its design all the essential features of the modern gyra tory crusher. For some years after these pioneer machines were developed, crushing requirements were quite simple. All underground mining and open-pit quarrying was done by hand with tonnages and rock sizes generally small. In the milling of precious metal ores, stamp mills were popular as the final reduction machine. The stamps were fed with an ore size readily produced by one break through small gyratory or jaw crushers. Even in large underground mining operations, there was no demand for large crushers; and increasing tonnage requirements were met by duplicating the small units. The Homestake gold mine in South Dakota was a good example, where in 19 15 twenty -two small Gates gyratory crushers were used to prepare the ore for the batteries of 2,500 stamps. Open pit mines and the introduction of the steam shovel created a demand for larger crushers, which led to the development of a gyratory with an 18 in. (457 mm) receiving opening. Up to this time, the jaw crusher had kept pace with the gyratory, both from the standpoint of receiving opening and capacity; but now the gyratory stepped into a 15-year lead with larger and larger sizes. This trend toward large primary crushers started just before the turn of the century, and in 1910 crushers with 48 in. (1.22 m) receiving openings were being built. About this time, the jaw crusher was revived in a great contribution to primary crushing by the introduction of the 84 in. by 60 in. (2. 13 by 1. 52 m) machine. This crusher was usually followed by a 24 in. (6 10 mm) opening gyratory crusher for secondary breakage, a system which reawakened the industry to the use of the jaw crusher as a primary breaker. It is interesting that although his machines never came into general use, Thomas A. Edison ranks as a pioneer in the development of the large primary breaker. Edis on reasoned that the recoverable electrical energy

Jan 1, 1978

By Robert Gilman Brown

The original power-plant of the Standard Company has been described* by Mr. T. H. Leggett, late president and manager of the company; but since the presentation of his paper considerable additions have been made, which will be found interesting because of the engineering features involved and of the attainment of a high degree of flexibility with the inflexible, two-wire, alternating system of electrical transmission. Although these additions have been completed during the last year, they constitute, to a large extent, only the carrying out of plans that belonged to the original conception of the installation. The regular operation of the water-power through the winter proved very difficult; there was a considerable length of ditch to be kept open, and, as the stream is small and any freezing night may stop the whole flow of water, there was the .additional trouble of having no reserve to draw upon. The rule for the winter is, that after a night of hard frost water begins to move in the canon before noon on all but the coldest days. To obviate the nuisance of the anchor-ice, and to make available all of the water, a dam of sufficient height to impound several days' run of water has been built across the canon, 3875 feet above the power-house, and provided with pressurepipe well below the surface. In place of the 1571 feet of pipeline from penstock to power-house, there has been substituted a line 3875 feet long to bring water direct from the dam. The dam is of logs, cribbed up in squares of about 12 feet, ballasted with earth and rock and sheathed on the water-face with 3-inch plank.

Jan 1, 1897

By George R. Gardner, Kenneth B. Ray

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 discharge 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 condition 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 considerable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, therefore 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 prepared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation. The first important work on the flocculation and clarification of coal slurry was done by Henry, who developed the Henry process and used it successfully in Belgian preparation plants. Soon after the initiation in Belgium, the process was introduced into England, where subsequent, investigation developed similar processes, which were successfully used in

Jan 1, 1939

By Jesse O. Betterton

Recently some experimental work was conducted by the author in connection with the direct leaching of certain zinc ores with sulfuric acid with the object of subsequently recovering the zinc by electrolysis. The ores contained relatively large quantities of soluble silica, making it necessary to evolve special methods for handling the silicate solutions resulting from a leach of the ore, and also for the final removal of the silica before electrolysis. The problem was complicated by the presence of vanadium in the ore, the commercial recovery of which was very desirable. This paper, however, deals only with the silica phase of the problem. The zinc in the ore occurs in the form of a silicate (hemimorphite) and, to a very small extent, as the phosphate (hopeite) and carbonate (calamine); the vanadium is found as descloizite and vanadinite but mainly as descloizite. The experimental work was done in a plant producing 50 lb. of zinc = daily, in which the complete cycle of operations, including the final electrodeposition of the zinc, was performed continuously for one year. Some of the conclusions given here are the result of the operations in -this plant; the others are from laboratory tests inaugurated both as a guide to the plant operations and, in certain cases especially, to determine the limits in question. The practice in the 50-lb. zinc plant was to direct leach the ore crushed to pass 40 mesh, with spent electrolyte from the cells containing approximately 3 per cent. zinc and 10 per cent. free acid. This resulted in an acid leach solution and an ore residue. The acid leach solution was ' subjected to a special treatment for subsequent removal of vanadium; then the silica and vanadium in solution were precipitated together and removed as a "silica residue" by pressing through an ordinary plate and frame press. The next step was to treat the filtrate from the silica residue with zinc dust as a final purification step before it went to

Jan 1, 1923

By H. S. Munroe

AN elaborate discussion under this heading formed a chapter in one of the reports made by Professor Raymond as Commissioner of Mining Statistics.* In a subsequent report- was printed a paper, by Mr. William Main, Jr., of Columbia, South Carolina, containing a theoretical investigation into the effect of the velocity of impact on the effective ditty of stamps. A visit to the Lake Superior copper region last summer suggested an inquiry into the relative efficiency and economy of the enormous steam stamps of the copper-mills, as compared with the results obtained with the cant and tappet stamps commonly used in the West. The atmospheric stamp used at the Phoenix Mill promised to add interest to the inquiry, as giving an example of unusually high speed, this stamp making 160 drops per minute. In introducing his subject Dr. Raymond makes the following remarks, which are quite apropos of the present investigation : "In considering the economical application of stamping machinery, we meet, at- the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such * Mineral Resources West of the Rocky Mountains, 1871, p. 380. †- Mineral Resources West of the Rocky Mountains,, 1873, p. 345.

Jan 1, 1881

By Linn Bradley, W. W. Strong, H. D. Egbert

Marked differences of opinion have been expressed by engineers interested in cleaning iron blast-furnace gases for use in hot-blast stoves and under boilers, in reference to the advantages of a hot-dry method over a cold-wet method. One point at issue involves the sensible heat energy in the moisture contained in the gas. Some advocates of the cold-wet methods claim that the condensation and resultant removal of the greater portion of this contained moisture by wet scrubbing, spraying or similar methods, results in a saving of some of this sensible heat energy, by reason of the fact that water vapor has a high capacity for sensible heat energy and may carry from the exit of a hot-blast stove, for example, more heat units than are sacrificed or lost when the gas is cleaned by this cold-wet method. Other advantages claimed for the latter method are: That gas burns more readily when it is free from moisture in any form; that because gas is made denser by cooling and removing the moisture it has a higher calorific value than hot gas carrying moisture; and that higher flame temperatures are obtained when the gas is cleaned by the cold-wet method. A search through the available literature fails to disclose any extensive calculations or records of conditions obtained in practice, bearing upon these phases of gas cleaning. This paper deals with these problems from the standpoint of the economy of using a gas of higher flame temperatures, of improved stove design, and of economy in the gas-cleaning department. Calculations have been made which show that by cleaning the gases by a cold-wet method the sensible heat energy of the blast-furnace gases is greatly reduced; and, in general, this loss of heat energy is far greater than that lost from the stoves or boilers due to the sensible heat capacity of the water vapor if carried away by the exit gases. By making use of the

Jan 1, 1917

By E. R. Hoskins

Results of a primary stress measurement investigation conducted on the 1100 copper ore body of the Mt. Isa mine, Mt. Isa, Queens., Australia, are presented in this chapter. The investigation started in September 1965, after discussion with the engineering staff at Mt. Isa, and consisted of both underground or in-situ tests at Mt. Isa and laboratory tests on Mt. Isa rocks and stress measurement techniques at the Australian National University in Canberra. Underground stress measurements were made in and adjacent to the 1100 copper ore body. The primary stress measurement site was in J 32 west crosscut on 14 Level. Approximate coordinates on the mine grid are 3000 north, 1650 east. The vertical depth below ground surface at this point is approximately 2180 ft. Some preliminary measurements were made in M 30 west crosscut on 13 Level, coordinates 3000 north, 2000 east, depth beneath the surface approximately 1990 ft. Additional flatjacks were installed on 11 Level in L 30 west crosscut, coordinates 3000 north, 2200 east, and depth beneath the surface approximately 1580 ft. All of the sites were in rock that from a mining engineering viewpoint must be considered extremely sound. The 13 and 14 Level crosscuts were approximately 14 ft on a side and nearly square and the 11 Level crosscut was approximately 10 ft on a side. All of the crosscuts had been standing open for several years and no artificial support of any type was necessary. Extraction openings hundreds of feet on a side have been made in this mine in similar rock and these have remained open also without additional support (see Davies 1 for a recent summary of mining techniques and conditions). The geology of the Mt. Isa mine has been most recently described by Bennett.2 Briefly, Mt. Isa is a silver-lead-zinc and copper mine in a series of Precambrian siltstones, shales, and bedded carbonates that strike north-

Jan 1, 1972

A preceding paragraph treats of the irregular manner in which ore deposits occur and the complex factors that control their distribution; the occurrence of metals in oreshoots in individual deposits is equally irregular, and the factors that control such segregation are equally complex. While the dimensions of oreshoots in individual deposits may not be foretold with any degree of accuracy, the occurrence of ore in shoots is not accidental, but is controlled by laws some of which are understood. Any one familiar with permutations and combinations who stops to consider the variety of factors that control ore deposition, and their varying relative importance, will admit that the science of economic geology must advance greatly before the occurrence of oreshoots may be predicted accurately in advance of exploration. The segregation of minerals in any oreshoot must be referred to some condition, or combination of conditions, local to the oreshoot as compared with the remainder of the deposit of low- grade or barren minerals. Among the localizing factors that have been recognized are, in filled fissures, the amount and distribution of open spaces available for ore deposition, and in replacement deposits, the degree of brecciation giving access to the replacing solutions; the intersection of veins with other veins, dikes, sheeted zones, or porous strata; the impounding of solutions by impervious strata; and the differing precipitative influences of enclosing rocks. A large proportion of important and well- defined oreshoots, especially in deposits of deep-seated origin, are not assignable to any of these factors. While a knowledge of the character of oreshoots in general is important, a knowledge of the behavior of the known oreshoots

Jan 1, 1932

By H. S. Munroe

As elaborate discussion under this heading formed a chapter in one of the reports made by Professor Raymond as Commissioner of Mining Statistics." In a subsequent report? was printed a paper., by Mr. William Main, Jr., of Columbia, South Carolina, containing a theoretical investigation into the effect of the velocity of impact on the effective ditty of stamps. A visit to the Lake Superior copper region last summer suggested an inquiry into the relative efficiency and economy of the enormous steam stamps of the copper-mills, as compared with the results obtained with the cam and tappet stamps commonly used in the West. The atmospheric stomp used at the Phoenix Mill promised to add interest to the inquiry, as giving an example of unusually high speed, this stamp making 160 drops per minute. In introducing his subject Dr. Raymond makes the following remarks, which are quite apropos of the present investigation: "In considering the economical application of stamping machinery, we meet, at the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one arid then another condition of working; but this is seldom possible for such

Jan 1, 1881

By A. J. M. Ross

Backfilling of stopes and other underground openings in the Homestake mine with sand tailings was undertaken primarily to reduce surface subsidence, which was wrecking much of the surface plant and a substantial part of the town, and to make possible maintenance of openings into the top of pillar stopes as mining progressed. The progress of this type of filling has been rapid and the results very satisfactory. Sand is now used in filling timbered stopes, shrinkage stopes, and abandoned drifts and crosscuts. A permanent pipe-line system for transporting sand tailings into the mine by gravity has been installed. The close filling of all stopes has resulted in important benefits other than the two major ones. The ore bodies in the Homestake mine occur as replacements in one distinctive layer of the metamorphosed pre-Cambrian sediments along a group of minor folds that together form a complex anticline that pitches at 35" to 40' to the southeast. The ore bodies are extraordinary for their magnitude. Widths of over 300 ft. have been mined and continuous ore has been followed for over 1200 ft. along the strike on some of the upper levels. Mining has been by shrinkage stoping with square-set mining of crowns and pillars. In the standard plan, shrinkage stopes 60 ft. in the direction of strike and the full width of the ore have been taken up to within 25 ft. of the level above. After filling, the crown has been mined by square-set methods, as have also the 40-ft. pillars between shrinkage stopes. In former days, when the supply of ore seemed inexhaustible, the mining of pillars was allowed to lag far behind because of the high cost. Many pillars were rather badly fractured on the level and in some places between levels. Coarse waste was used for backfilling all stopes, but in pillars it became increasingly difficult to maintain haulageways for the transportation of this fill over the top of the stopes as mining progressed. The cost of maintaining these crosscuts was excessive and in many pillars practically impossible. Therefore it became the practice to fill pillar stopes by tapping the back and sides of the stopes.

Jan 1, 1940

By Toshihisa Adachi, Shosei Serata, Shunsuke Sakurai

Many different methods of measuring the in-situ stress field have been developed in recent years. They are all based on the assumption of elasticity without allowing any viscoelastic deformation. By using the high resolution strain-measuring technique recently developed in the laboratory at Serata Geomechanics, many rocks were found to be viscoelastic. The viscoelasticity of rock media was found to be dependent upon the resolution of the strain measurement. The higher the resolution of the strain measurement, the greater number of rocks could be identified as viscoelastic. All rocks eventually exhibit viscoelastic deformation under high stresses relative to the strength of the material. Therefore, the conventional methods of elasticity become less reliable with increase of ground stress. In deep underground formations, even hard rocks become viscoelastic. At the same time, many ground formations near the surface are actually viscoelastic. A new method was developed in the laboratory to determine the in-situ stress field in viscoelastic rock media. Rocks in general exhibit a small amount of viscoelastic creep whenever mean stress and octahedral shearing stress are changed substantially from their initial states. Such changes take place around a borehole immediately following the drilling although they are short-lived. We developed a viscoelastic method of determining the in-situ stress field by relating the time-dependent behavior of the borehole with the tensor properties and stress field of the underground. In developing the viscoelastic relation, only isotropic and homogeneous

Jan 1, 1970

By P. H. Bohart

THe answer to the title question will be found by considering the ultimate influence of the petroleum engineers on industry and by considering the tools with which petroleum engineers must be equipped. Some 2000 to 3000 petroleum engineers are being absorbed by the industry yearly, indicating the magnitude of influence which they may exert on the industry. The petroleum industry is a highly technical one and it is inevitable that management be entrusted more and more to executives with technical training. The industry, therefore, expects the petroleum engineering schools to provide a broad basic training and a social and economic orientation which goes beyond merely supplying the minimum technical qualifications necessary to discharge responsibilities for a particular job. Because of the many branches of industry, emphasis must be placed on the Student's being trained in fundamentals, as well as grounded in other engineering branches, such as mechanical, civil and electrical engineering. The petroleum engineering graduate must know how to outline and organize the material for an engineering report and should be thoroughly grounded in English, both written and spoken. Even to the end that a five-year course may be required, they should receive instructions in auxiliary cultural and social science courses, industrial relations, and public speaking. Training in the method of approach to an engineering problem is something in which industry is deeply interested. A standard of ethics, a desire to arrive at the truth, and leadership training should be stressed. Introduction The basis of an an to any ques- tion concerning the petroleum engineering schools' responsibility to the industry will be found by considering the ultimate influence of the petroleum engineers on the industry and by considering also the tools with which petroleum engineers must be equipped in order to achieve success and happiness in the role in which their training, individual talents and choice of a profession ultimately will cast them. The problem must always be considered as it relates to a large group and not as it relates to a particular individual possessing strong natural talents and destined, by virtue of them, to pursue a certain course. The question implies that petroleum engineering schools have a responsibility, and indeed they do, not only to the industry but also to the students and even to the public. Because the responsibility is concentrated in a relatively few schools whose graduates are absorbed largely by the one industry, the responsibility is more apparent and the effect of failure to discharge the responsibility fully is more serious than the effect of similar failure on the part of schools supplying a smaller portion of the industry's intake of engineering graduates. This fact is especially true with respect to an industry such as the petroleum industry whose ratio of technical to nontechnical employees is relatively high and is increasing.

Jan 1, 1948

By Harry Perry

In the United States the state mining laws enacted in the late 1800s were the first laws to recognize that an employer had a responsibility to provide the employee a place to work that met at least some minimum safety standards. The coal mining industry was also the first major industry in the United States to be regulated in 1952 by federal safety laws, although federal inspectors had the right-of-entry as early as 1941. Within recent years, however, the Congress has enacted a number of federal safety regulations for a variety of industries, such as the Aviation Act (1958), National Traffic and Motor Vehicle Act (1966), National Gas Pipeline Act (1968), and Radiation Control for Health and Safety Act (1968). The fatality and injury experiences of the mining industry in the United States, while at a significantly higher rate than for industry as a whole, showed a continuous improvement until the last decade or two-at which time the rate leveled off. Although fatality and injury rates in foreign countries have been generally lower than in the United States, further improvement in those countries also has been difficult to achieve in recent years. It appears, therefore, that some major change in mining laws, combined with a radical improvement in mining technology and a more effective labor-management safety program, will be needed if further reductions are to be achieved in fatality and injury rates. At the same time, there is a growing awareness by society that an employee's place of work, where he spends nearly half of his waking hours, should be made as safe as possible. As increased consideration is given to means for achieving greater safety in all industrial situations, it is becoming apparent that more is required than merely providing physical safeguards on tools and machines. Rigorous, strictly enforced safety standards are useful, but more important is the desire of labor and management to make certain that industrial accidents are prevented. The pressure to achieve increased productivity, and thus receive higher wages, can be a significant deterrent to safe working practices. The temptation can be great to "take a chance" or "cut a corner" in order to speed up production. Public concern over all types of industrial safety in the United States was reflected by the introduction of a number of general occupational health and safety bills in Congress for the first time in 1968. While no legislation resulted, the hearings revealed that, although there were differences in how standards should be set and who should administer them, there was agreement on the need for adequate laws. Since the mining industry has been subject to safety standards longer than other industries, it is not surprising that advanced safety concepts for mining are being explored by the industry and the enforcing agencies. More complete and sophisticated accident reporting is being planned that will reveal the

Jan 1, 1976

Jan 1, 1945

By J. B. Hiskey

Heap leaching has in recent years been established as an important processing alternative for gold and silver. Currently, heap leaching accounts for about 25% of primary mine produced gold and 10% of primary silver. This paper reviews gold and silver heap leaching practice and surveys major operations in the United States.

Jan 1, 1984

By P. H. Dudley

IN giving a brief account of the experiments in progress to inquire into some of the facts in regard to "railway resistances," recently commenced upon the Lake Shore and Michigan Southern Railway, with the dynagraph (which is essentially an instrument recording upon paper the force required to draw a train, at all speeds, marking the time in short intervals, so that the force absorbed due to any

Jan 1, 1876

Jan 1, 1962

Jan 1, 1957

Executive ARTHUR S DWIGHT, Chairman B THAYER CHARLES F RAND P MATHEWSON J V W REYNDERS Membership WILLIAM H BASSETT, Chairman W Y WESTERVELT Vice-chairman P MATHEWSON H G MOULTON F T RUBIDGE Finance WALTER H ALDRIDGE, Chairman GEORGE D BARRON GALEN H CLEVENGER

Jan 1, 1923