Search Documents

By M. E. Tyrrell, Alan H. Goode

The application of a simple, two-dimensional computer technique for evaluating rock burst potential in cut-and-fill stopes was investigated. The principal purpose of the study was to compare the effectiveness of high-modulus fill and destressing as aids in the control of rock bursts. Two conclusions that are probably of general applicability are drawn. First, high-modulus fill is ineffective as a means of increasing the mine stiffness and acts to control rock bursts only if it supports enough load to reduce substantially the stresses on the unmined vein material. Second, destressing is most effective if it is performed when the vein material is near the point of failure.

Jan 1, 1975

By A. K. Andersen

One of the prime examples of the versatility of the MARCONAFLO system, which is a body of technology comprising the means to handle, store, load, transport, discharge and reclaim mineral commodities in slurry form, is the direct application of this process to leaching ores. The initial approach was to provide a much improved materials handling system for the transport of copper ores; however, an extensive development program, inclusive of prototype and pilot plant tests, has established that a new leaching concept is possible with this system. Data are presented from the leaching operation of a 25 TPD pilot plant utilizing a copper-oxide ore, mainly chrysocolla. This pilot plant was designed to incorporate true countercurrent flow where the ore is actually in motion, as contrary to vat leaching operations, and the ore being successfully leached is fine crushed ore (3/8-inch x o), contrary to agitation leach circuits. Extractions in excess of 85% of the soluble values are common with only 15 hours of retention time in the MARCONAFLO leaching system.

Jan 1, 1975

By A. J. Lynch, N. W. Johnson, D. J. McKee

The behavior of nonsulfide gangue in chalcopyrite flotation circuits has been investigated. Plant and laboratory tests were conducted on five different ores. Linear relationships between the recovery rates of free nonsulfide gangue and water were observed. From pilot plant tests, there was evidence that the linear relationship was actually a linear approximation to a parabolic relationship. There was evidence that free nonsulfide gangue is transported from the pulp to the froth in the water and that the gangue is subjected to hydraulic classification in the froth column. A classification matrix has been proposed to define this behavior. This matrix is suitable for inclusion in a mathematical model of the process.

Jan 1, 1975

By H. G. Hammon

Uranium miners have been shown to develop lung cancer in direct proportion to the time of exposure in the mine and the concentration of radioactivity (cumulative working level).1 Radon gas is continually evolved from the uranium ore, but because of its shoe half-life, 3.82 days, it is soon decomposed into particulate daughter products, which along with the dust in the mine, become deposited in the miners' lungs. At present, massive ventilation is the only effective method of reducing the radioactivity concentration in the mines. However, the Bureau of Mines is evaluating the possibility of using coatings on the mine wall that will have sufficiently low permeability to radon that the gas will decompose into the particulate daughter products before it can permeate the coating. Permanently trapped in the coating, the daughter products would be prevented from dispersing in the mine atmosphere. Lawrence Livermore Laboratory was asked to aid in this investigation. The direct determination of radon permeability is more difficult than that of the other noble gases because of the short half-life of the gas and radioactive contamination of the apparatus. We felt that it should be possible to estimate radon permeation coefficients from other noble gas permeation coefficients. It was noted that the log of the diffusion constants for helium, neon, argon, and krypton, as reported by Meares2,3 plotted to a straight line-against the square of-the gas molecularddia meter. The log of the permeation coefficients also plotted to a straight line against the square of the gas molecular diameter. Thus, by determining the permeation coefficients of such gases as argon and krypton through various films and coatings, it appeared likely that radon permeation coefficients could be estimated. In addition we felt it should be possible to find some relationship between polymer structure and he noble gas permeation coefficient that would aid in the selection of coatings materials as radon barriers.

Jan 1, 1975

By H. N. Mills

The glass industry is a major user of many industrial minerals in the manufacture of its product. It is the intent of this chapter to: (1) acquaint the reader with the glass industry by including a few production statistics, and then (2) cover the various aspects of the major raw materials used to make glass. Some of the items covered are: type of materials, their function in glass, their composition, cost, and the relative quantity used in glass vs. totals produced. In addition, a discussion of glass raw material specifications, some byproduct materials used in glassmaking, and comments on future prospects related to the environment, technology, and growth are included. The matter of glass compositions, properties, and batches is considered beyond the scope of this chapter which deals only with raw materials. For more details on the particular minerals and rocks, the reader is referred to the commodity chapters in this book.

Jan 1, 1975

By R. D. Saltsman

Under contract with the Federal Bureau of Mines, Bituminous Coal Research, Inc., performed a statistical study to find less expensive and time-consuming methods of monitoring the noncombustible content of coal mine dust. Calculations based on thermodynamic considerations verified the reasonableness of Federal rock-dusting requirements. The results of extensive sampling in southwestern Pennsylvania mines indicated that, at the 95-percent confidence level, the present system of sampling at 200-foot intervals may be replaced by sampling at 500-foot intervals, and that a 1-inch scoop floor sampler may replace the standard 6-inch scoop for floor sampling. Further field testing is recommended.

Jan 1, 1975

By Thuli AJ

Copper concentrate from Bougainville's copper mine located on the west slope of the Crown Prince Range on Bougainville island, is pumped 27 km to the filter and drying plant at Anewa Bay for preparation and storage prior to shipment to overseas customers. Prior to shipment the thickened concentrate slurry is passed through a test loop to check that its consistency and pH are acceptable for transportation through the main pipe line. The Bougainville pipe line is unique since it is the world's first copper concentrate system. where slurry is pumped an appreciable distance against a high head,

Jan 1, 1975

By Fred N. Kissell

Experimental work by the Bureau of Mines indicates that when a coalbed is degassed by boreholes, the flow of methane may actually increase with time. This phenomenon appears to be the result of a relative-permeability effect; that is, the coalbed permeability to the gas increases sharply with decreasing water saturation. This report reviews the background of experimental evidence indicating a relative-permeability effect, and presents the results of a computer simulation of two-phase flow in coal.

Jan 1, 1975

By K. C. McMahon

This report is the result of the engineering efforts performed by the Mining Equipment Operations of FMC to develop methods of automating a continuous miner. This work was done as part of modification number three of the contract for the development of a miner/bolter system. As the demand for energy places an ever-increasing pressure on the coal mining industry to produce more coal, methods for underground mining which will increase productivity with a con-current increase in safety are being actively sought. Removing the machine operator from his station on the continuous miner and placing him at a safer location behind the machine while retaining his control functions via an umbilical cable or a radio link was an important first step. However, the problems of poor visibility, no control "feel", and the judgmental problems of controlling the sump distance and the shear limits have not been conducive to the productivity increase that is desired.

Jan 1, 1975

By James W. Shaffer

Aluminum is the most abundant metallic element of the earth's crust and is a constituent of nearly every type of rock (Clark, 1924, p. 13). The sources of aluminum and aluminous material most commonly used by modern industry are the bauxitic raw materials consisting of bauxite, bauxitic clay, and aluminous laterites. These are mixtures of hydrated aluminum oxide minerals and mineral impurities. End Uses Bauxite is used as an aluminum ore and in the manufacture of refractory products, aluminous chemicals, and abrasives. Other raw materials are used for aluminum ores, but their use is minor compared to bauxite. Refractory products made from bauxite are synthetic mullite, high-alumina fire bricks, castables, monoliths, cements, and ramming mixes used by the iron, steel, and cement industries. Chemicals made from bauxite are aluminum sulfate and sodium aluminate for water treatment and aluminum chloride used in refining crude petroleum. Among the abrasive products made from bauxite are coated abrasives, sharpening stones, and grinding wheels. Special grades of bauxite are used in the decolorization and clarification of raw sugar and lubricating oils. Bauxite has been used for road surfacing but mainly because other material was not more readily available. Perhaps the oldest use of bauxite and aluminous laterite is for a building stone. Ancient temples and more recent structures in India have been made from these and some varieties are suitable for decorative stone. Geology Mineralogy and Properties – Bauxite is a mineral raw material composed principally of one or more hydrated aluminum oxide minerals and impurities of silica, iron oxide, titania and elements in minor or trace amounts. The hydrated aluminum oxide minerals are gibbsite, boehmite and diaspore. Corundum is not included as a bauxite mineral although it does occur in some bauxite deposits. Boehmite and diaspore are both alumina mono-hydrates and have essentially the same composition, but diaspore has a greater hardness and a higher specific gravity because of a more tightly bonded and compacted atomic structure. Gibbsite is an alumina trihydrate mineral. Properties of bauxite minerals are shown in [Table 1].

Jan 1, 1975

By Donald A. Brobst

The minerals barite (BaSO4 barium sulfate) and witherite (BaCO3 barium carbonate) are the chief commercial sources of the element barium and its compounds whose many uses are nearly hidden among the technical complexities of modern industrial processes and products. Barite, the major ore mineral, is extremely vital to the petroleum industry which in 1973 consumed at least 80% of the world's produc¬tion of 4.4 million tons as a major ingredient of the heavy fluid, called mud, that is circulated in rotary drilling of oil and gas wells. The re¬maining 20% of the barite production was consumed chiefly in the manufacture of barium chemicals and glass and as a pigment, filler, and extender. Barite occurs throughout much of the world and is available from three major geologic types of deposits-vein and cavity fill¬ing, residual, and bedded-in sufficient quantity at competitive prices to meet current demands. The world's demand for barite is expected to increase, and geologic circumstances are favor¬able for the discovery of new deposits of com¬mercial value. Witherite is much less common and abun¬dant than barite, although it is more desirable in many ways as a raw material for the pro¬duction of barium chemicals. The United States has not produced witherite since about 1950; England is currently the chief producer of witherite. End Uses Most of the world's barite production since 1926 has been used as a weighting agent for the muds circulated in rotary drilling of oil and gas wells. The muds fundamentally are mixtures of water, clay, and barite in different proportions that vary according to local reservoir condi¬tions. Muds with a specific gravity as great as 2.5 are used. The mud is pumped down the hollow drill stem, passes through the bit at the bottom of the hole, and rises to the surface in the space between the drill stem and the wall of the hole. In the course of this circulation the drill bit is cooled, cuttings are removed, the drill stem is lubricated, the walls of the hole are sealed, and the hydrostatic head of the column of weighted fluid helps to confine high oil and gas pressures. The latter feature aids in prevention of gushers, thus reducing both environmental pollution and waste of oil and gas resources as well as conserving the natural reservoir pressure for greater production and rate of recovery of the products contained in the rocks. Barite is particularly well suited for drilling mud because it is clean, easy to handle, soft (nonabrasive), heavy, virtually inert chemi¬cally, and relatively inexpensive compared to many other available heavy materials. Barite is used in the manufacture of glass in continuous tanks. The addition of barite ho¬mogenizes the melt and gives greater brilliance and clarity to the finished glass. Ground barite, both unbleached and bleached by sulfuric acid, is a common industrial filler, extender, and weighting agent. The rubber in¬dustry is a major consumer of barite as a filler. Barite also is added to bristolboard, heavy printing paper, playing cards, rope finishes, brake linings, clutch facings, plastics, and li¬noleum, to name but a few uses. Bleached barite has long been an extender in white lead paint because of its weight. The low index of refraction of barite, however, makes its ability to cover marks poorer than some other sub¬stances, but its low capacity for absorption of oil is a good feature. Off-color or unbleached barite can be used as a filler in colored paints. In the construction industry, some lump barite is used in concrete aggregate to weight down pipelines buried in marshy areas and to shield nuclear reactors. Because barite absorbs gamma radiation well, its use reduces the amount of expensive lead shielding otherwise

Jan 1, 1975

HISTORY Up until the late 1880's the mining industry acquired a considerable proportion of its capital needs from domestic sources. Exchanges were established wherever major new fields were opened and Ballarat, Bendigo, Charters Towers, Coolgardie, Kalgoorlie and Silverton all boasted active trading in mining shares. For much of the first half of this century there was only modest developments in the mining industry and its capital require- ments were correspondingly lower. RECENT EXPERIENCE The new mines of the sixties were, in many cases, characterised by their remote situation and their output of bulk commodities such as iron ore., coal and bauxite. Infra- structure costs were particularly high and the level of capital expenditure was of previously unheard of proportions.

Jan 1, 1975

By R. V. Ramani, C. B. Manula, A. Owili-Eger

That a close analogy exists between the flow of air in mines and the flow of current in electrical networks- has been known for a long time. The laws that have been used to solve series and parallel electrical circuits have been used to solve for the equivalent resistance in mine ventilation problems. Kirchhoff's current and voltage laws have also been adopted in solving mine ventilation network problems. It will be best to define a few terms here regarding networks, and with reference to Figure 1, these definitions can be elucidated. Figure 1 can be represented by the network in Figure 2 without losing any essential details. 1. A junction is a point where two or more airways meet. 2. The segment of a roadway connecting any two junctions is known as a branch. 3. A mesh is a closed path through the network. In the above network, B, C, D and F are the junctions, CF and CD are two of the branches and CFDC is a mesh. Kirchhoff's current law states that the sum of currents entering a junction. Applying this law to the junctions in the ventilation network, one obtains for junctions C and F, the following relationships: JUNCTION C: Q1 = Q4 + Q3 (1) JUNCTION F: Q2 + Q3 = Q5 (2) Similar relationships can be drawn for other junctions. Kirchhoff's voltage law states that in any complete electric circuit, the algebraic sum of the emf's must equal the algebraic sum of the voltage drops. In mine ventilation, the square law (Atkinson's

Jan 1, 1975

By R. G. Schaal

The Magma Mine at Superior, Arizona had an unimpressive beginning as a. worked out silver mine that was purchased in 1910 for $130,000 and then incorporated into the Magma Copper Company which has been continuously mining the deposit since 1915. Copper is the principal metal produced. However, zinc, gold, silver and iron have also contributed to the total metal product. Prior to 1973, the production rate of 1500 tons per day was maintained by hoisting 4 and 5 ton pay-loads at speeds up to 1100 FPM through four small hoisting shafts. The hoists used included 8' and 7' diameter double drum, double clutched doc. and a.c. motor driven geared units built as early as 1917. One old timer that did yoeman's service for many years was an 8' Bollen Pulley with a.c. geared drive that utilized an endless rope system with mechanical grip and release mechanism built into the pulley's throat. Primary power for all of these old production hoists was 25 Hertz. Exploration that was completed in 1967 developed a reserve of 10 Million tons of 5 per cent copper which was sufficient to justify new capital expenditures for enlargement of productive facilities to 3300 tons per day. To reach the new reserves a 22' I.D. concrete lined vertical shaft was sunk to an initial depth of 48431. A 12 ½ diameter adit was bored from the mill side of the mountain to intercept the shaft at a point about 1100' below the collar. This 9200' long adit provides the right-of-way for the mine to mill railway and egress for heavy supplies from rail head as well as a conduit for potable water, electric power, compressed air and mine drainage. Mine operating levels begin 3582' below collar and thereafter have been cut at 100' vertical intervals. Skip loading stations have been installed 4282' and 46821 below collar with an in-shaft skip dump station located 800' below collar. This provides for 4500 tons of storage above the mine to mill train loading station located 1100' below collar. Ore and waste are moved horizontally from stope chutes and drift headings by rail haulage to transfer raises which channel all material to the two mentioned skip loading stations. The 22' diameter shaft crossection is arranged with the two skip compartments on the south side separated from the manway and utility compartments by the cage compartment. The cage counterweight operates in a portion of the southwest quadrant of the shaft. The hoisting plant consists of two conventional Nordberg double drum, single clutch, geared, d.c. motor driven units that are identical except for the drives and automatic controls. The drums are 15' diameter x 105" face with LeBus grooving for 2-1/8" diameter wire rope wound in three layers. Mechanical design emp1o::ed is the same as has been used for the past twenty- five years. One drum is attached to the main shaft by 2 large bolted integral shaft flenge. The loose drum is engaged by a 4-arm positive tooth clutch meshing with radially cut teeth of the clutch ring which is bolted to the drum. The drums are one-piece steel plate weldments having a finished weight of 60 tons each and are mounted upon a 36" diameter shaft that also weighs 60 tons. With the addition of brake rings, clutch, bull gear and rope, the total dead weight adds up to nearly 250 tons that is supported by just three double row spherical roller pillow block bearings. There is no bearing between the drums. All pinion shafts as veil as all head sheave journals are supported in the same type of antifriction bearings.

Jan 1, 1975

By C F. Argo

In the past several years the "Kelly Bar", an innovative device, which incorporates borehole d-rifling and explosives loading into a single detail, has come under scrutiny and criticism. The practical aspects of the Kelly Bar procedure is not questioned, and the system has been highly successful in expediting the loading of explosives in difficult and unstable formations. There have been a number of accidents indirectly associated with Kelly Bar loading and the point in question has become one of safety rather than mechanical feasibility.

Jan 1, 1975

To the layman or the casual in- vestor, the critical problems in the mining industry appear to rest on the questions of finding and developing an orebody. The high cost of finding a major orebody suggests that the search is the only matter of real concern. However, the resulting operations which hopefully will provide a profit- able return, depend very heavily on the quality of the servicing that the particular industry receives. Once the mining venture has been established with the necessary plant, equipment and infrastructure, the routine servicing becomes an important function of the operations.

Jan 1, 1975

By Willis GM

The matte-metal-equilibria in the system Pb-Cu-S have been studied at temperatures between 720 and 920¦C by direct sampling and D.T.A. methods. These results are compared with those of other workers. The applications of such data to a continuous copper drossing process, and to a number of other metallurgical processes are discussed.

Jan 1, 1975

By W. E. Lamont

The Federal Bureau of Mines, in cooperation with phosphate companies in the Florida land-pebble area, made a comprehensive study of the waste clays, or "phosphate slimes," produced in the mining of phosphate rock in Florida. These slimes represent a significant ecological problem and a major deterrent to effective land recovery in the phosphate-mining areas. Physical, chemical, and mineralogical studies were made of slime samples submitted by 15 of the 16 plants in Florida in an effort to identify factors that prevent successful consolidation of the slimes and subsequent recovery of the mined lands. Results of these studies indicated that the clay mineral attapulgite, a hydrated magnesium silicate, was primarily responsible for the very poor settling characteristics of the slimes, and that the quantity of attapulgite in the slimes effectively controlled the settling rate, pulp density of terminal solids, viscosity, percent solids of filter cake, and flocculant requirements.

Jan 1, 1975

By Joseph Moses Botbol

The disposition of world mineral resources is such that a vital need exists for both the most efficient development of existing resources and the rapid disclosure of as-yet undiscovered resources. The technological developments described in this report are directed primarily toward the acceleration and increased efficiency of mineral-resource exploration program. In the past decade the use of computers in the mineral industry has grown exponentially. Most computer applications in mineral exploration are designed to be implemented either before or after data collection. Few, if any, computer applications are designed to be used during the collection of data. One major reason for the lack of development of computer applications in this area is that comunications links do not exist between computing systems and the remote areas that host mineral-deposit exploration programs.

Jan 1, 1975

McLeod: Without getting into the argument as to how well we can know our resource levels specifically in the immediate short term, I would like to make one or two points about the future, and perhaps try and persuade people that they are not really facing a doomsday. It is fair to say that over the last few years the rate at which we have increased our resources has far exceeded the rate at which we have used them, and this is likely to continue for quite a few years yet. As people are now looking for a substitute for petroleum, later on we will be looking for a substitute for coal, should the position get serious. After all man is pretty versatile, has plenty of initiative-and makes allowances for experience. It has been demonstrated here by the way people are looking at use of low quality coals and better use of the coals that are available. It would be fair to say that what now we regard as economically submarginal deposits will, by the time we need them, become economic. I think that there is quite a lot in front of us in exploration and finding new reserves. I would like to have comment from yourself sir, because I recall reading a report of a meeting, here in Wollongong I think it was, in which you addressed the local branch on the future of coal in Australia, and you said that the coal basins of Australia had been well explored and there was not much chance of new discoveries. Since that time we have seen some thousands of millions of tonnes turned up in the Galilee Basin of Queensland, we have seen five hundred million tonnes turned up in Lake Phillipson in South Australia. Do your previous comments still apply? I would like to hear from some of the exploration people, who are operating on an Australia-wide basis, as to how they regard our chances of discovering significant new deposits and significant extensions of known deposits. H,artnell: Mr. McLeod has asked me to comment on what he has just said. I think that the important thing is that our knowledge of the main coal basins in Eastern Australia is increasing in detail but for the most part the extent of coal basins is not being increased in respect of their superficial areas. There are additions but they are not substantially changing our expectation of what the main coal basins will be. I believe that our task is essentially to intensify our knowledge of the main coal basins that we know about. This is important for example for the various reasons that Mr. Roach was talking about, that is the problem of surface alienation, jeopardising the chance of recovery when you go to underground operations. My approach to this whole problem is predicated on the belief that coal has a special destiny to perform in the next fifty years. I believe that it is going to take up to fifty years and maybe a little longer before the enormously demanding technology for nuclear power recovery is in fact achieved. When it is achieved the supply of energy to the world will be enormous, much beyond what we have ever even dreamed about. The mind boggles at what the people of the middle of next century, of two thousand and fifty, will command in the way of physical resources. It is going to be, I believe, tremendous, but the technology involved is very demanding. I mentioned to Mr. McLeod the other day that according to the information that I got in November last, 60% of the nuclear power stations in the United States were out of action, by automatic cut offs because of safety requirements. The technology of breeder reactors seems each year to be a bit further off. In the meantime coal I am sure is going to be called on to supply power directly to fluidised bed and other technologies for power generation. It is going to be called upon in the near future, I believe, to supply liquid fuel on a vast scale and the only thing in my view that we should be thinking about is whether the coal producing countries of the world will succeed in producing as much coal as is going to be demanded. I believe the real challenge to the coal mining industries of the world is that they may fail to do what is going to be demanded of them. This is a challenge I believe to mining technology. I think that we should be working deliberately and energetically finding ways and means where underground recoveries, instead of averaging 50%, can average 50% plus, plus, plus, and this is the first requirement. We should be spending many millions every year, here and overseas, on increasing our means of winning coal because every tonne of coal that is alienated and left irrecoverable in the earth is going to weaken the capacity of the coal mining industry to fulfil, what I believe to be its destiny in the next 50 years.

Jan 1, 1975