Search Documents

By G. W. Murrie

A geologic study of the Mary Lee Group of coalbeds in the Black Warrior coal basin was undertaken to examine coal stratigraphy and determine regional trends and extent of the coalbeds. The area investigated encompasses 835 square miles in Jefferson, Walker, and Tuscaloosa Counties, Ala. More than 700 core logs were used to construct a structure map, coal, interval, and overburden isopachs, and cross sections. There is evidence that structure affected sedimentation. Coalbed isopachs indicate the Mary Lee Group was deposited in fluvial-deltaic and low-lying coastal plain environments. The Mary Lee coalbed is the only coalbed which is continuous throughout the area, commonly with two benches which have a combined thickness of 2 to 12 feet. The Mary Lee coalbed changes rank in the basin from high-through medium-to low-volatile coal. The methane gas potential of the Mary Lee Group coals is estimated to be greater than 1 trillion cubic feet. There is an excellent correlation between the orientation of surface cleats with those measured underground in the Mary Lee coalbed. The face cleats roughly parallel the axes of the area's folds and trend northeast-southwest.

Jan 1, 1976

By W. P. Diamond

Coalbeds exhibit a directional permeability, with the maximum permeability oriented parallel to the face cleat. Thus, the most efficient pattern of vertical degasification holes for a coalbed is dependent upon cleat orientation. Surface joints, infrared photolinears, and Ronchi grating photolinears were investigated as potential estimators of subsurface cleat orientation. Cleat orientations were measured in 18 mines, in the Pittsburgh coalbed in southwestern Pennsylvania and northern West Virginia to be used as a standard against which prediction techniques would be evaluated. Two cleat systems with a strong geographic segregation were measured in the study area: N 670 W -N 280 E (950 separation) for the north, and N 76° W -N 17° E (930 separation) for the south. Directional data obtained from the three techniques investigated yielded satisfactory regional predictions of cleat orientation. Analysis of surface joints was the only technique considered sufficiently reliable on a local basis. Prediction of cleat orientation is based on the pairing of the principal directional sets into all reasonable combinations of fundamental systems. The system or systems composed of the most dominant sets nearest to 90° separation are likely to be a reliable prediction of cleat orientation. The most dominant set of the system selected is likely to be the face cleat.

Jan 1, 1976

By Wayne R. Hopkins

Southern Arizona has one of the world's principal concentrations of copper ore bodies. Twenty miles south of Tucson, close to the Mexican border at Sahuarita in Pima County, is the Twin Buttes mine. In mid-1973, the Anaconda Company and American Metals Climax Incorporated (AMAX) established a 50-50 partnership to operate and expand the Twin Buttes property. Anamax Mining Company was established as the operating company for this joint venture. The production from the Twin Buttes mine is shared between the two partners who market independently. A major expansion of the Twin Buttes operation has included an accelerated stripping programrne for the pit, an expansion of the sulphide concentrator, the construction of an oxide leach plant and a 57 MW diesel generating power station. Part of this major expansion, the large tonnage oxide processing plant was brought on stream in 1975 and is now close to design capacity. The "mine to market gap" has been closed by producing high-purity copper cathodes at the mine site from oxide ore reserves. By using a hydrometallurgical process route, copper production is possible with negligible effects on the environment.

Jan 1, 1976

By R. P. King

Flotation plant simulation, a relatively recent methodology in mineral processing, is defined and corresponding uses are discussed. Typical simulation structures are compared. Current problem areas exist although these are not insurmountable. Following a brief state of the art discussion, the N. I. M. simulation program is reviewed. In general, digital plant simulation is expected to be of substantial benefit in the near future.

Jan 1, 1976

By Belcher C. B

A simple gravimetric procedure was developed for the rapid determination of carbon dioxide in coal mine roadway dust samples and the result is used for the subsequent calculation of incombustible matter contentaccording to the requirements of the Queensland Coal Mining Act. The carbon dioxide is determined through loss of mass by a semi-enclosed apparatus, following room-temper.ature hydrochloric acid attack on the sample.With a sample containing 36 per cent carbon dioxide, the achieved standard deviation (ls) of 0·3 per cent CO. is adequate for coal mine roadway dust analysis.This simple procedure enables relatively unskilled labour in mine laboratories, to analyze coal mine roadway dust samples in accordance with the Act. Some 50 analyses can be achieved per day compared with 8 by the Australian Standard Method for coal.

Jan 1, 1976

By S. R. Rao, J. Leja, K. S. Moon

A prolonged grinding of sulphide ores in steel mills appears harmful to flotation recovery and selectivity whenever xanthates are used as collectors. Particles finer than about 10µm show a pronounced decrease in floatability. A supposition was made that the cause of the reduction in floatability of ground sulphides is the presence of metallic iron abraded during grinding and deposited on the ground particles. Electro- chemical measurements were made of mixed potentials developed by different sulphide-mineral electrodes (galena, chalcopyrite, pyrite, marmatite, pyrrhotite) in xanthate solutions, without a direct con- tact or in contact with a metallic iron electrode. These measurements showed that without a galvanic contact between the sulphide and the iron, the values of mixed potentials were in the vicinity of the xanthate/dixanthogen redox potential. When contact with iron was established, the mixed potentials shifted towards the more negative reducing or cathodic values. The shift was greater the higher was the ratio of the surface areas: iron electrode to sulphide electrode. Further, the shift in mixed potentials was greater the more reducing were the conditions on the sulphide electrode. Chemical analysis of reaction products produced on the surfaces of sulphides and in the bulk solution showed that less thiosulphate was formed in all of the sulphide-xanthate systems and that more elemental sulphur was detectable on the pyrite and marmatite surfaces. Adsorption of xanthate parallels the amount of thiosulphate formed with which xanthate is exchanged by metathesis. If the supply of oxygen is limited, the demand for oxygen by the abraded metallic iron competes with that by the valuable sulphide, resulting ultimately in poorer hydrophobicity. If excessive amounts of pyrite or pyrrhotite are present as well, the conditions are so reducing that there is little adsorption of xanthate ions on the valuable sulphides to make them hydrophobic and floatable. The presence of increased quantities of sulphur on pyrite or marmatite is responsible for a non-selective flotation. Flotation tests on synthetic mixtures with and without metallic iron powder in the feed confirmed the above conclusions from electrochemical and chemical measurements.

Jan 1, 1976

The aim of this paper is to examine the problems confronting the planner, designer, constructor and management when rehabilitating the works associated with road building- and including quarry and borrow areas. The importance of further investigation into the many factors involved, including species, methods of planting and aftercare is stressed as is the need for trained personnel and the consequential availability of specialised training courses. Emphasis is placed upon the relevance of a rational and unemotional approach to rehabilitation with respect to the landscape and to the high degree of co-ordination and co-operation between all disciplines involved.

Jan 1, 1976

By D. W. Fuerstenau, S. Raghavan

This paper presents a brief summary of some of the thermo- dynamic aspects of flotation processes. Thermodynamic considerations that control interfacial and wetting behavior in mineral/water/air systems are discussed. Particular attention is given to the thermodynamics of collector adsorption.

Jan 1, 1976

By C. G. Palagi, S. S. Stillar

The C. E. Weed concentrator treats 51,000 tons per day of 0.5% to 0.7% copper ore received from the Berkeley Pit, the Continental East Pit and the Butte underground mines. Improved operating techniques and conversion from semi-autogenous secondary grinding to ball milling have increased tonnage from an original design of 42,000 tpd. Separate treatment of sands and slimes, with recovery of soluble copper from the slimes, has increased total copper recovery. Concentrator tailings are pumped 600 vertical feet and 20,000 horizontal feet for disposal.

Jan 1, 1976

By Han Kook-Nam, Lawson F

The recoveries of the three cobalt minerals in the Mount Cobalt deposit, cobaltite CoAsS, erythrite CO3(AS04)8H20, and new cobalt mineral with a composition approximating 2CoO.CaO.Fe203.2As205.11H2O were investigated using physical and surface-chemical processes.Over 80 per cent cobalt recovery was achieved by tabling a cobaltite-mineralized sample, while about 76 per cent cobalt recovery was obtained by dry feed magnetic separation of a sample containing erythrite and the new cobalt mineral. The resultant primary magnetic concentrate with a cobalt grade of 5.5 per cent, was able to be upgraded to 14.4 per cent cobalt by regrinding .and a further magnetic separation.Electrophoretic mobility - pH responses for each of the three cobalt minerals were found to be similar. Each mineral remained negative over the pH range 3 to 11 and was most negative at mildly alkaline pH values.Cobaltite was floated effectively with amyl and ethyl xanthate collectors under acidic conditions at collector concentrations of 10-2M to 10-5M. Erythrite showed a similar flotation response using 10-sM amyl xanthate. The practical application of these laboratory separations to an industrial process is suggested.

Jan 1, 1976

By Albert J. Shohet

The increasing scarcity of bentonite coupled with the potential of improved pellet strength have created a need for understanding the effects of thorough bentonite dispersion in taconite concentrate. It has been known for more than a decade that under certain conditions substantial savings of bentonite are realizable by using thorough mixing of bentonite as compared to poor mixing. Extensive work done by J. O. Zetterstrom l at the Univer¬sity of Minnesota indicated the effect of thorough bentonite mixing in a controlled laboratory testing. Commercial hardware was not available at the time Zetterstrom1 paper was published and not much work was done until R. L. Stone, J. M. Karpinsky2, did work with Muller mixing. Nabush 3 worked with the pugmill principle, and Hoogovens 4 and Robe River 5 used the fluidized bed principle. It was very hard to convince iron ore industries to improve the mixing of Bentonite and taconite for the following reasons: A. The initial capital investment for improved mixing equipment; B. The relatively low bentonite cost a few years back, which was not enough to justify new equip¬ment investment;

Jan 1, 1976

By J. C. Irvine

Meramec Mining Company is a joint venture by Bethlehem Steel Corp. and St. Joe Minerals Corp. which mines and pelletizes iron ore at the Pea Ridge Mine. The Pea Ridge property is located near Sullivan, Missouri, about 70 miles southwest of St. Louis. The orebody was delineated in the mid-1950's by St. Joe during a lead exploration program. The first test holes drilled on the Pea Ridge magnetic anomaly revealed the presence of a large magnetite deposit; further drilling in 1956 and 1957 confirmed that the orebody was mineable, Meramec Mining Co. was incorporated in 1957 and shaft sinking began late in the year. Production commenced in April 1964. The orebody is overlain by about 1300 feet of flat-bedded sediments. It is tabular, about 2600 feet long and up to 600 feet thick. It dips about 80° and is of unknown depth. The ore is mainly high grade magnetite with small zones of specular hematite. The wall rock is a Precambrian rhyolite porphyry. The mine was initially started with five major levels on 150 foot intervals. Crosscuts were driven across the orebody on 190 foot centers. Banks of scopes were mined between the crosscuts by a modified shrinkage stoping method. This was done by undercutting a 40 foot wide by 150 foot long block and blasting horizontal "lifts" drilled on 5 foot intervals. A 65 foot still was left between levels which contained the slushing drift, fingers, crown pillar, and adequate thickness for support. By 1971 a ?lattice? of pillars had been left and mining had progressed to the point that an orderly pillar recovery program was necessary.

Jan 1, 1976

By R. E. Mason

Shotcrete has been used for approximately 20 years to facilitate tunnel excavation through poor ground. Early examples of such usage in North America include the recuperation of the Granduc Mines access tunnel in Northern British Columbia, and similar work performed in the Carley V. Porter and Big Walker Tunnels in the United States. Mining companies such as Craigmont Mines in B.C. and Hecla Mines have used shotcrete in their workings for the past ten years. Shotcrete is now a widely utilized fool in the mining and tunnel construction industries in North America, but the accumulated experience is too limited for many to fully appreciate the capability of shotcrete to control ground movements and to understand the limitations of this tool. It is common, for instance, to use shotcrete to "bridge the gap" between rock bolt-supported and steel-rib supported ground and to avoid the use of shotcrete in water-bearing ground. Shotcrete can, and has been, used economically and practically under most severe ground conditions.

Jan 1, 1976

By Gordon H. Dechman

This report presents the concept, design, and testing of a sonic velocity monitoring system for the early detection of slope failure in open pit mines. The heart of the system is a device for producing reproducible sonic signals in rock. Because changes in the velocity of sound through rock near the top of the pit wall are a measure of extent and rate of fracturing of the rock, velocity histories obtained from periodic, automatic sonic velocity surveys provide positive information about developing slope instability.

Jan 1, 1976

By Henry N. Doyle

Basic procedures in the mining industry have changed only slightly over the centuries since metals and fossil fuels became an essential part of man's economic and cultural life. Mining techniques of the 20th century bear a close resemblance to those of the ancients: exploration, ore breakage and removal, hoisting, and processing. The great advances, however, have been in equipment and machinery of greater size and speed which allow greater efficiency in each of these operations, with a corresponding reduction in manpower requirements. Yesteryear production was measured in pounds per man-day; today a giant and complex, but highly efficient, continuous mining machine can remove as much as eight tons of material a minute from the coal face. If our energy and metal demands of the future are to be met, and at this time it can be assumed that coal will continue to supply a significant part of the energy demand, other dramatic and spectacular technologic advances must be accomplished. Along with mechanization, however, public policy will require the industry to place greater emphasis on health and safety protection, as has been well demonstrated by recent actions of Congress. Together, fossil fuels and metals formed the basis for the industrial revolution-coal to develop power and metals to transform power into useful energy. Strangely enough, however, the mining industry the world over has lagged behind the continuous social changes brought on by the industrial revolution, such as preventive health and industrial hygiene services, and other programs directed to the well-being of the worker. In some countries this resistance, to change may have led in part to the nationalization of the coal industry. Whether this disinclination to social change in the industry of the United States reflects managerial attitudes, inept labor leadership, government neglect, or economic relationship would be the subject of an interesting study. Doubtless the mores of miners and their resistance to change, as well as their geographic isolation from other industrial groups, may have had a strong influence on these factors. In every major coal mining country the accident rate in the coal industry is substantially higher than other industrial groups, and the cost of pneumoconiosis compensation in some countries is greater than the combined costs for all other occupational diseases from all other industries. The high social cost of occupational accidents and diseases may have been a factor in the closing of the industry in at least two countries. Despite diminishing manpower needs, the industry is faced with critical manpower shortages. Miners once reared their sons to be miners; now it appears that the opposite is true. This factor alone, however, does not explain an acute labor shortage in the industry. Traditionally, the industry drew much of

Jan 1, 1976

By Geoffrey G. Hunkin

This is a brief state of the art paper describing current (1975) Uranium recovery plant flowsheets, some notes on system selection, design philosophies, and materials of construction. The in-situ, or borehole solution mining, of Uranium is a process which has been developed over recent years to better match Uranium mining and milling technology with the size, shape, grade and territorial distribution of the remaining identified Uranium deposits of western United States. Solution mining recovery plants are pure hydrometallurgical units ideally suited to automation, modular design, and mobility. Similar to conventional Uranium mills, two basic flowsheets, one acid and one carbonate, are in use, but the predominance is reversed so that the majority of plants employ the alkaline carbonate flowsheet, All plants incorporate resin bead ion exchange Uranium recovery for both acid and alkaline circuits.

Jan 1, 1976

By Miles L. Silberman

Three major suites of igneous rocks were erupted in the Great Basin in middle and late Cenozoic time. The first, most likely, resulted from sub- duction of a Pacific plate (Farallon plate) beneath the North American plate, resulting in eruption of andesitic rocks in the northern Great Basin between 42 and 43 m.y. ago. Between 34 and 17 m.y. ago, igneous activity migrated to the southwest, largely as eruption of volumincus rhyolite-quartz latite ash-flow sheets, ending about 17 a.y. ago with the onset of crustal extension and north-south-trending Basin and Range (rift) faulting. The second volcanic suite erupted between 17 and 8 m.y. ago in the northern Great Basin; is mostly basaltic or bimodal basalt-rhyolite. The third volcanic suite consists of andesitic and rhyolitic lavas and some basalt erupted between about 22 to 6 m.y. ago in the western Great Basin along the northwest-trending Walker Lane fault zone. Hydrothermal ore deposits are associated with all suites of igneous rocks, but the largest production has come from mines associated with andesitic rocks of the third (western Great Basin) suite. The oldest (34 to 42 m.y.) andesitic rocks (first suite) of the northern Great Basin have produced some large deposits; slightly younger silicic rocks of this suite are mostly barren. Many small ore deposits are associated with the 17- to 8-m.y.-old basalts (second suite) of northern Nevada.

Jan 1, 1976

By Robert H. Hooff

The Vor-Siv Dewatering and Classifying Unit was developed by the Polish Coal Industry because of a need for a unit that would dewater and classify high volumes of solids in water slurry. To be practical, the unit needed to be relatively small in size, simple in design, involve low operating costs, and be able to give a dewatered product of less than 30% moisture. The answer to the above mentioned criteria was the Vortex Dewatering Sieve or, as we refer to it, the Vor-Siv. The original installation of the unit, as we know it today, began in 1963 when the Pols installed the unit in a full scale pilot application. By 1966, at least 30 of these units were installed throughout the Polish Coal Industry. This equipment was originally introduced in the United States in 1966 at the Fifth International Coal Preparation Meeting in Pittsburgh, Pennsylvania. The first installation in the United States was not achieved until 1970, when Mr. Fred Sachs of The Valley Camp Coal Company, Triadelphia, West Virginia, installed a Vor-Siv in a retrofit application. To date, there are 36 Vor-Sivs installed in this country and 29 in the process of being installed or delivered.

Jan 1, 1976

By J. R. Hunter

The present is rooted in the past. This is particularly true in the case of mining operations. Coal mining in the United Kingdom is considered an old Industry comprising today 246 Coal Mines many of which have worked coal reserves in their locality for over 100 years. More than half the current producing mines lie in the Yorkshire and Midlands coalfields. They are in the oldest age group and produce 70% of the Industry's output. Some 50% of the remaining U.K. workable reserves amounting to approximately 98,000 million tons are still available to these regions. Fig. 1 Over the past two decades a gradual erosion of demand for coal in the U.K. has virtually halved the Industry's capacity. The number of Mines has reduced by 53% during the past 10 years. Productivity has increased by some 42% mainly through improvements in the central coalfields which has enabled costs to remain broadly competitive with oil.

Jan 1, 1976

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

A. 4 Illustrative Simulations The capabilities of the program are demonstrated by simulating various evacuation cases in different situations for a particular mine. The mine selected for the illustrative simulations is the mine I C' , as described in Section 2, chosen particularly because of availability of mine characteristic data and mine evacuation results for test drills. These evacuation results can be used to verify validity of the predictions made by the program A.4 1 Mine Characteristics A schematic diagram of the mine is shown in Figure 19. The figure shows all the major shafts, drifts, raises and stopes of the mine in the form of a network. There are four hoists, Hoist No. 1 and Hoist No. 2 are assumed to be single drum hoists and Hoists Nos. 3 and 4 form part of a double drum hoist, with Hoist No. 4 being the main hoist (master hoist) The positions of the 133 miners, typically working in a day shift of the mine, are also shown in the figure. The miners are identified by a miner number, and their total number on each level is chosen from the data on the fire drill simulated as Case No. 1 in the illustrative simulations.

Jan 1, 1976