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By Garland Likins

The Texas Department of Transportation, now considering using Augered Cast-In-Place (ACIP) Piles (also known as Continuous-Flight-Auger or CFA Piles) in their foundations, awarded a research project to Professor Mike O'Neill at the University of Houston (UH) to study the advantages and potential difficulties with ACIP/CFA piles. ACIP/CFA piles were installed on three sites for UH; they had extra instrumentation and additional measurements by UH staff during installation which are beyond the scope of this paper. Independent visual logging of the pile was done by an experienced inspection firm. The main advantages of ACIP/CFA piles are their speed of installation and their economy. Potential savings are substantial. Disadvantages include an unknown structural condition of the shaft. Inspection is critical, but many simultaneous observations make accurate inspection difficult. Because of resulting uncertainty, many engineers have avoided ACIP/CFA piles in the past.

Jan 1, 1998

Develop a lightweight, portable device for use in mines for non-destructive testing of resin grouted roof bolt bond integrity. Approach A unique, intrinsically safe, electronic instrument has been developed that determines the holding quality of a fully grouted roof bolt by testing the integrity of the resin bond to both the bolt and to the surrounding rock. How It Works A measured pulse of energy Is sent Into the bolt by a piezoelectric transducer, and the instrument listens for reflected energy. Where the bolt is properly bonded, the energy passes from the bolt, through the resin, and out into the rock mass. Where proper bending does not exist, a portion of the energy Is reflected back along the bolt. The Instrument measures the reflected energy and compares it to the original pulse. The amount

Jan 1, 1982

By Bert S. Hall

"The purpose of this paper is to review the evidence at hand concerning the earliest centuries of cast iron in Europe, from roughly 1400 A.D. until the second half of the sixteenth century. For the most part it is concerned with the relationship between two technologies which emerged first in China and then later appear in Western lands, gunpowder weapons and iron founding. We should not assume, as I hope to show later in this discussion, that weapons constituted the only product for which the iron founder had any market, but it is clearly true that attempts to produce weapons constituted the most severe technical challenge for the early founder. Firearms appear for the first time in Europe in the 1320s and develop into significant weapons on the field of battle by the end of the century. Theirs is a complex history, subject neither to easy summary treatment nor to simplified models of development. I hope to be able, through the analysis of the evidence concerning cast iron, to show that one important strand in the fabric of gunpowder's history concerns the materials from which cannon could be made. This question is subject to a number of shades of meaning, because ""cannon"" can be made for many purposes under a profusion of different names, and under sharply varying conditions of use. As a result, the question of materials is frequently really a question of competing materials, and involves a complex set of factors, of which production costs and the ultimate safety of the user seem the most important. Judged in this manner cast iron was an important but unsatisfactory metal for weapons purposes until 1543, at which time English founders learned to make iron muzzle-loading cannon which could rival bronze ordnance in most important performance criteria, but which cost much less to produce. With that event, the history of cast iron and the history of weapons entered into the close relationship that persisted until the advent of rifled artillery made of steel in the middle of the nineteenth century."

Jan 1, 1999

By H. F. Yancey

A relatively large proportion of the coal produced 1n the State of Washington, especially in the coking coal areas is of fine size; hence washing by means or coal-washing tables to reduce the ash content is commonly practiced. For this reason the program of research in coal washing conducted jointly by the U. S. Bureau of Mines and the College of Mines, University of Washington, has given special attention to the mechanism or the separation of coal from its impurities as effected by the coal-washing table with the object of increasing its efficiency. Previous work has evaluated the role of stratification the influence of size, specific gravity and respective shapes of particles in the feed, and the affect of hindered-settling classification of the feed prior to tabling.

Jan 1, 1931

Kaiser Sees Bright Future for Jamaica Kaiser Aluminum Co. has a big stake in the British West Indies, the Island of Jamaica in particular. There, Kaiser is busy developing one of the most promising bauxite finds in recent years. The $12 million operation was officially opened in February. Facilities have a rating of an annual capacity of 2 million tons and will supply Kaiser plants with ore for years. The ore comes across the Gulf of Mexico, up the Mississippi to stockpiles at Baton Rouge. The stockpile at Baton Rouge would throw many an old river boat skipper for a loss. Where no mountain once existed now stands a man-made bluff of bauxite, known as Bauxite Peak.

Jan 6, 1953

By Talaat A. B. Lawendy, Guerry H. McClellan

Batch laboratory-scale flotation tests were conducted on some carbonate-containing sedimentary phosphate ores to obtain concentrates suitable for chemical processing. The phosphate samples tested contained both calcite and dolomite. The calcitic phosphate ore was from Israel and the dolomitic ores were from China, India, Egypt, and Pakistan. The phosphate sample from Pakistan also contained a significant amount of silica. Several flotation techniques that have been proposed for upgrading carbonate -containing phosphate ores and concentrates were tested. Two processes gave better results compared with the other processes tested: a modified IMC anionic process and a. phosphoric acid depression process. At the best flotation conditions tested, phosphate concentrates assaying 32.5%-36.5% P205, 44.0%-51.0% CaO, and 0.6%-1.0% MgO were obtained at 69%-76% overall P205 recoveries from run-of-mine (ROM) ores containing 16.0%-25.0% P205, 40.0%-52.0% CaO, and 1.0%-11.6% MgO.

Jan 1, 1993

By R. J. Heemstra

A continuous flowing paper electrophoresis cell was used to separate petroleum and petroleum extracts into characteristic patterns. The electrophoresis of Bachaquero, Lagunillas, Boscan, and Gibson petroleums in nitro-benzene and acetic acid-based electrolytes was investigated. The extent of separation in the patterns was studied by measuring the metal and porphyrin contents of the effluents. Qualitative separations were achieved in some systems, whereas either system demonstrated only a high degree of electrophoretic migration.

Jan 1, 1967

By Katherine Harding

This Bureau of Mines publication describes a practical approach to sampling that does not require elaborate statistical techniques. Simple steps are given for finding a cutoff point in the response from a repetitive survey. This procedure can be used to estimate the aggregate value of the characteristic being measured without waiting for a complete count from the survey. This is a useful technique when the reference periods are repeated at frequent intervals, such as monthly and quarterly, and when the statistical collecting agency is engaged in publishing timely data which must be accurate economic indicators.

Jan 1, 1971

By James C. Fowler

The use of ground-probing radar as a reflection mapping tool is gaining acceptance in subsurface investigations. This tool may be used to obtain near-surface information useful to geotechnical engineers. Along with the lightweight field equipment now available, radar is being used to obtain information that may impact the safety and production of mining, tunnelling, and excavating operations.

Jan 1, 1982

By N. J. Themelis

Autogenous grinding, broadly defined as the self-comminution of ore in a cylindrical tumbling mill without using auxiliary grinding media, was first applied in the early thirties in the so-called Hadsel mills (Figure 1) mainly used in gold mines on the U.S. West Coast. A number of these mills were built in sizes of 20 to 24 ft. in diameter and five-six feet in length but were later abandoned because of operating and maintenance problems. Further development of autogenous grinding led to the Hardinge wet grinding mill (Figure 2), the Aerofall dry grinding mill and others. A tabulation of all known autogenous and semi-autogenous installations around the world was sent recently to the authors by Hr. G. J. Kushner of the Koppers Mineral Processing Division. In the size range of 24 to 32-ft. in diameter, it lists a total of thirty mills used in the processing of copper ores. An additional 120 units are listed in the same size range for the processing of iron ores and other minerals. The largest mills in existence are 36-ft. dia X 15-ft. long mills in Minnesota, powered by 12,000 hp. motors and used in taconite beneficiation. It is indicative of the phenomenal growth of this technology that none of the above one hundred and fifty mills was in operation prior to 1964.

Jan 1, 1978

Provide an inexpensive, remote actuated, stench-gas system which reduces fire warning time to underground work locations. Approach A mine's pager phone hard-wire network is used to release stench gas from pressurized canisters located near working areas. The release is initiated by placing a coded message into a control phone at some central location. How It Works Currently, in most mines, the decision to release a warning stench gas is made by mine management after communication from the mine of a fire or similar potentially dangerous situation. Stench gas is then released into the ventilation air and/or compressed air lines for dissemination throughout the mine. This can result in significant delays in warning time. Often, surface personnel must travel to distant shafts, or other release points, wasting valuable time. Also, the time for ventilation air to circulate from the surface to working locations can be long and the effectiveness of compressed air as a stench transport agent depends on whether the compressed air is being used at the face. The Bureau of Mines, through a contract with MSA Research Corporation, has designed and tested a warning system which avoids these problems. The system consists of multiple, pressurized stench-gas canisters located under-ground in the mine-ventilation network so as to provide quick dissemination of the released stench gas to working areas. Each stench-gas canister is hard-wire connected to a nearby pager phone and from there to a control phone at the surface or at a central in-mine site. In the event of a mine emergency, the canisters are activitated to release stench gas by placing a coded message into the control phone. A low amperage Signal sent from the control phone to the receiver phone closes a relay, which activates a release mechanism on the canister.

Jan 1, 1984

By D Millette, F Gay

Surface tailings are finely ground waste materials produced in all mines after the mineral or metal has been removed from the metallurgical process. Current methods for disposal of tailings involve constructing dams, dumping into existing waterways, and depositing as backfill underground. Each method has its drawbacks in terms of cost, level of complexity, safety and environmental concerns. Backfilling is the process whereby waste material (generally metallurgical tailings, prepared aggregates or a combination) is placed from the surface back underground into open mine workings via conveyor belts, hydraulic or pneumatic pipes or gravity. In the backfill process common difficulties are expensive placement costs, equipment wear and the ability to meet early and long-term strength requirements. Traditional tailings transportation in pipes involves the use of water as the transport medium. Foam technology involves the introduction of micro-air bubbles that replace the water as the main transport medium. This air can be removed after placement if necessary, by the addition of a defoaming agent. This could produce an under-saturated stable cake. Foam technology has the potential to revolutionise surface tailings disposal and backfilling by providing a less expensive and environmentally safe alternative to those just described.

Jan 1, 2000

By Holbrook G. Botset

Experiments performed in this laboratory on the flow of gas-liquid mixtures through unconsolidated sands have been described and discussed in an earlier paper.4 In these earlier experiments a definite relationship was found between the liquid saturation of a sand and its permeability to the liquid or gas phase. Furthermore, the nature of the sand, the permeabilities of the sands over a range between 17 and 260 darcies, appeared to have a negligible effect upon the saturation-permeability relation. Likewise experiments indicated that the viscosity of the liquid, or the substitution of an immiscible liquid for the gas phase, had only a very slight effect on the permeability-saturation relation. This conclusion has since been definitely confirmed by the experiments of M. C. Leverett3 on the flow of oil and water through unconsolidated sands. The sands used by Leverett were of very low permeability (between 6.8 and 1.04 darcies), while the oil-water viscosity ratio varied between 90 and 0.057. Since the sands that constitute petroleum reservoirs are largely consolidated, although of widely varying degrees of consolidation, it was desirable to extend the experiments on gas-liquid mixtures to consolidated sand. In the study of consolidated sands additional variables are involved, but for the initial experiments the only new variable to be introduced was the cementing material. Experimental Procedure A comparatively limited assortment of sandstones was available for the selection of the experimental material. Of these, the Nichols buff sandstone appeared to be most suitable. It gives no visual evidence of any bedding planes, it has a firm structure, permitting easy handling, and its permeability is about 0.5 darcy. Its only disadvantage is the fact that it contains an appreciable amount of ferric oxide which, for experiments involving water, will hydrate and reduce the permeability. This

Jan 1, 1940

NEW MEMBERS The following list comprises the names of those persons Who became members during the period Dec. 10, 1914, to Jan. 10, 1915: Members AGUILAR-REVOREDO, J. F., Min. Engr -Casilla 146, Oruro, Bolivia. BAKER, JOHN M., Min. Engr Baker Mines Co., Cornucopia, Ore. BETTS, ROBERT M., Mgr Cornucopia Mines Co., Cornucopia, Ore. BILLINGS, THOMAS PARRY, Min. Engr., 404 Dooley Block, Salt Lake City, Utah. BLAIR, GEORGE SHEPPARD, Engr. and Assayer, Mariposa Min. & Mill. Co., Hornitos, Cal. BOLE, JOHN W., Supt ...Siskiyou Dredging Co., Fort Jones, Siskiyou Co., Cal. BOWMAN, REGINALD G., Statistician, International Smelting Co., 621 Kearns Bldg., Salt Lake City, Utah.

Jan 2, 1915

By G. Sauer

"More Skill is needed to avoid rather than to handle heavy ground loads." This finding, from a tunneling engineer of the nineteenth century, is still relevant today with all advanced sequential excavation and support methods available whether they are applied in the vertical or horizontal direction. Balanced contractual agreements and documents are important since they provide the spirit and climate at the site. This article aims to describe the means and measures for 'hand mined' shaft and tunnel support as they are available today. Some special construction elements and methods with a perspective in recent developments in order to avoid getting stuck in conservatism are presented as well. If we don't allow new methods, means and measures we may end up with the famous quote "Only women who have already proven they are able to give birth to a healthy baby are allowed to become pregnant!"

Jan 1, 2003

By Ali Ekrem Aritan

Exposure to hand-arm vibration (HAV) among the labor force in the mining industry can result in permanent vibration diseases such as behavioral disorders, visual impairment, osteoporosis, pain (mostly in the hands, wrists, and shoulders), circulatory system disorders, and malnutrition. In this study, the vibration exposure of excavator operators working regularly in 25 different natural stone quarries was measured. In addition, the relationship between vibration exposure and rock properties was investigated. Gloved and ungloved vibration measurements were performed and revealed that antivibration gloves reduce excavator operators’ vibration exposure by 7.10–25.95%. Samples from each quarry were characterized with rock mechanics tests. The correlations between the hand-arm vibration measurements and the natural stone physical–mechanical properties (uniaxial compressive strength, Shore hardness, Knoop hardness, apparent density and total porosity) were determined to be over 70%. One finding of the study was that the health risk in excavators cannot be reduced sufficiently by the sole use of antivibration gloves. Furthermore, the excavation of any rock with a Knoop hardness above 121 is associated with an 81% risk of HAV. To increase awareness of the danger of vibration exposure for natural stone miners, training programs should be provided, and technical and operational changes should be implemented.

By B. K. Mishra, A. Datta

Estimating the power draw of a ball mill is of great importance from both operational and control standpoints. There are many factors that affect the power draw, and its prediction is particularly difficult in an operating plant. The important factors that affect power draw are the mill dimensions and operating parameters. Although mill dimensions remain the same for any given mill, the operational factors, such as ball load, mill filling and mill speed, may vary. This makes the modeling effort extremely cumbersome. It is for this reason that an artificial neural network is considered for the development of a black-box-type model to predict power draw. In this work, a total of 48 sets of plant data are used. Using these data, a neural network is built and trained. The trained network is used to predict power that is found to be in good agreement with operating mill power for many situations. In addition, the results of simulations are also com- pared to those obtained from a discrete-element method- based power-draw model.

Jan 1, 2000

By Martin J. Gungl, J. Lyman MacInnis

None of the industry submissions could persuade the Canadian Tax Reform draftsmen that the rate of return has had as much bearing on investors' decisions to invest in Canada as the success records of Canadian ore findings. The goverment opted for the position that mining capital goes where the ore can be found. Many tax incentives which were available until the end of 1971 have been greatly reduced. However, it is still recognized that new ventures in exploration and development of natural resources deserve a break even if there is reduced recognition of the established and highly successful members of the industry unless they continue to search and develop. The latter will also get some breaks for processing beyond the prime metal stage.

Jan 7, 1972

By F. C. Bond

Since the Third Theory of Comminution was presented eight years ago (I) it has found increasing use in crushing and grinding problems. The practical utility of its wok index equation is quite generally acknowledged (2). However, its theoretical basis has been questioned in at least three technical articles (3) (4) ('). The purpose of this paper is to present experimental proof that it is scientifically correct. Particles under compressive stress are strained and deformed. They absorb strain energy, and when this locally exceeds the breaking strength, a crack tip forms. The surrounding strain energy flows to the crack tip, which rapidly extends and splits the rock, releasing the strain energy as heat. The initial energy flow causes additional crack tips in highly strained areas. If the compression is rapidly applied by impact, crack tips may form before the strain energy has reached equilibrium in the particle, thus decreasing the total work input required for breakage. The energy necessary to break is essentially the energy necessary to produce crack tips, since the energy necessary to extend the cracks to breakage is already present as strain energy in the deformed particles. After breakage nearly all of this energy appears as heat. The crack length cannot be measured directly. However, in particles of regular and similar shape the crack tip length is considered as equal to the crack depth, or crack extension necessary to break, so that the crack length equals the square root of one-half of the surface area. The Third Theory states that the useful work done in crushing and grinding is directly proportional to the total length of the new cracks formed. It can be confirmed by showing that a constant work input produces a constant length of new cracks when reducing the same material to different product sizes. This is done in the present paper on a wide variety of material. The constant work input was supplied by one revolution of the 12" x 12" laboratory ball mill used in making grindability tests by the Allis-Chalmers method (12) (13) The new crack lengths produced per mill revolution were measured from all available grindability test results at 28, 35, 48, 65, and 100 mesh on fifteen different ores, and were found to remain substantially constant for each ore at all mesh sizes. A new technique is used for the measurement of crack lengths. Size distribution plots of the mill feed and product are made by the Third Theory method (9) and the crack lengths are obtained from these plots by the procedure described in the present paper. The energy input required to produce a unit length is of fundamental importance in the size reduction of brittle solids. The crack length Cr is expressed in centimeters per cubic centimeter of solid material. It bears a definite relationship to the external surface area of the crushed or ground solid. A uniform particle shape must be assumed before the surface area and crack length can be evaluated. In this paper it is assumed that the relationship between the surface area and the particle volume of a particle d microns in diameter is the same as that of cube d microns on a side. The external surface areas of particles with a cubical breakage probably agree approximately with this rule, and correction factors can be applied when physical measurements of the surface areas are available for comparison. However, the assumption of equivalent cubes has been found satisfactory for most calculation purposes. Assuming equivalent cubes, one cubic centimeter of particles d microns in diameter will have a crack length Cr of v30.000/d centimeters, and a surface area of 60,000/d square centimeters. The specific crack length is thus equal to the square root of one-half the specific surface area. Where Sa is the surface area in square centimeters per gram and Sg is the specific gravity of the ground solid, then Cr = vSg . Sa/2 = 173.2/ vd (1)

Jan 1, 1961

By M. V. K. Reddy

A differential flotation process for recovery of molybdenite from chalcopyrite concentrates produced at Rakha Copper Concentrator, Bihar, India has been developed. The flowsheet is simple, and relatively inexpensive and yields a concentrate assaying not less than 45% Mo at a recovery of minimum 65%, starting from chalcopyrite concentrate assaying 0.4% Mo. The consumption of the main depressant used, sodium sulphide is not more than 25 kg/t of copper concentrate processed without steaming; and with steaming the consumption was brought dorm to less than 12 kg/t of concentrate. Further reduction is possible by optimization of steaming parameters. Based on laboratory experimental results, further tests were conducted on concentrator site and process design parameters were established for design of commercial plant.

Jan 1, 1982