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By C. T. Thompson

"Rotary percussion" implies two types of energy, rotary and percussion. Into these categories fall rock' drills of varying sizes. The larger ones drill above 6" diameter holes; the medium size, 2 3/4" to 4 1/2" holes; and the smallest, 1 1/4" to 2" holes. Essentially, the larger holes are drilled with doom-the-hole drills using tri-cone bits. Percussion energy evolves from the drill piston and rotation power from the rotary table or overhead drive, using drill collars or pull down mechanism to preload the bit.

Jan 1, 1963

By Eugene E. Hively

The Tower Kill is a vertical "stirred" ball/pebble mill recently introduced in the Western Hemisphere. This device offers a significant power savings on wet fine grinding applications when compared to conventional tumbling mills. This paper describes the laboratory application of this mill wet grinding hydrated alumina to products of 50 percent passing 2 to 6 microns.

Jan 1, 1983

By Willaim A. Berg

Vegetative stabilization can help meet the esthetic objections and pollution problems posed by mine wastes. However, mine wastes are often unfavorable growth media and special treatments and techniques are needed for plant establishment and continued growth. The establishment of vegetation on mine wastes was the subject of many papers presented at the International Symposium on Ecology and Revegetation of Drastically Disturbed Areas held at Pennsylvania State University on August 3-16, 1969. This paper is a summary of those papers presented at the symposium that dealt with the nutritional and physical aspects of plant establishment on a variety of mine wastes. The synopsis presented is a combination of excerpts from the abstracts, notes on the oral presentations, and rough drafts of some of the papers. The papers will eventually be published in the symposium proceedings.

Jan 1, 1970

By C. F. Curry

In the early 1940's Humphreys Mining Company in Florida pioneered heavy mineral mining with a dredge in the United States, In 1948 Du Pont, in conjunction with Humphreys, opened their first of two mining operations recovering a titanium dioxide product in Florida. Later on in 1952 Du Pont opened their second plant, both of which used a cutterhead suction type of operation. This process is also used in heavy mineral mining in Australia and Africa. In 1957 ASARCO started prospecting in New Jersey. Test borings indicated a large deposit of ilmenite bearing heavy mineral sands had been deposited and concentrated in an area near Lakehurst in central New Jersey. Humphreys Mining Company was contacted about the possibility of mining the ASARCO New Jersey property in much the same way as Du Pont and themselves were doing in Florida. An extensive study was made to determine the economic feasibility of mining the ASARCO property. During this study, extensive test drilling and samples for a pilot plant were taken.

Jan 1, 1975

By Erhard M. Winkler

The rapid decay and disfiguring of stone monuments in urban and desert rural areas has challenged conservators to protect stone surfaces from premature decay. They attempt to halt the natural process of stone decay and possibly to restore the original strength lost mostly by chemical weathering and the loss of binding cement. Ageneral solution is not possible because the physical and chemical characteristics must be considered for different stone types. The failures of stone preservation and restoration are greater in number than the cures. The need for repair of stone decay goes back to evidence of Roman replacement of decaying stone. The presence of excess water in buildings has long been recognized. Moisture tends to enter masonry from air in humid climates, a most important but often underrated factor (Fig. 1) suggesting that sealing should be the answer. Undesirable staining and efflorescence result in accelerated scaling. Today, the great variety of chemicals available to the modem conservator for sealing. consolidating, or hardening stone fall into two very different categories: surface sealers and penetrating stone consolidants, or a combination of both. SEALERS Sealers develop a tight, impervious skin which prevents access of moisture. Surface sealing has saved monuments from decay by eliminating the access of atmospheric humidity. Pressure tends to develop behind the stone surface by moisture escape. Efflorescence, crystal growth action, and freezing can cause considerable spalling (Anderegg, 1949). Flaking results when moisture is trapped behind the sealed surface. Yellowing and blotchiness are also frequently observed. The following sealants are in common use today: linseed oil, paraffin, silicone, urethane, acrylate, and animal blood on stone and adobe. Extensive cracking and yellowing has resulted soon after application. In the past many such treatments have created more problems than cures: 1. Linseed oil and paraffin have been in use for centuries. Embrittlement and yellowing occur rapidly because these are readily attacked by solar ultraviolet radiation. 2. Animal blood as paint has temporarily waterproofed adobe mud and stone masonry. The origin of blood paint has a religious background rooted in the Phoenician and Hebrew cultures. Instant water soluble dried blood can substitute for fresh blood. Winkler (1956) described the history and technique of the use of blood. 3. Silicones have proven very effective and are long lasting. In contrast, acrylates, urethane, and styrene are generally rapidly attacked by UV radiation (Clark et al., 1975). Sealing of Different Rock Types Granitic rocks have a natural porosity traced to 4.5% contraction of quartz, during cooling of the parent magma, compared with only 2% contraction of all other minerals; protection against the hygric forces may require waterproofing of granite in some in- stances. The Egyptian granite obelisk in London is an example. Soon after its relocation from Egypt to London, Cleopatra's Needle was treated, in 1879, with a mixture of Damar resin and wax dissolved in clear petroleum spirit; surface scaling became evident after half a year of exposure to the humid London atmosphere. The treatment of the ancient granite monument from Egypt has denied access of high relative humidity (RH) in London to the trapped salts inherited from the Egyptian desert and has protected the monument from decay (Burgess and Schaffer, 1952). The sister obelisk set up in Central Park, New York City, has fared less favorably because similar treatment was done too late, only after the salts hydrated and hundreds of kilograms of scalings disfigured the obelisk surface (Winkler, 1980). Surface coating of other common stones may be needed. Crystalline marble absorbs moisture from high RH atmospheres: dilation may ensue when curtain panels bow as the moisture starts to expand during daily heating-cooling cycles. A good sealer may prevent the moisture influx provided that no moisture can enter from the inside of the building. Limestones, dolomites and all carbonate rocks are subject to dissolution attack by rainwater, especially in areas where acid rain prevails (Fig. 2). The interaction of sulfates in the atmosphere with the stone can be halted by waterproofing to avoid the formation of soft and more soluble gypsum. The stone surface attack can be diminished if nearly insoluble Ca-sulfite crusts can form, instead of Ca-sulfate. Replacement of fluorite or barium compounds at the stone surface acts as a hardener, rather than a sealant. Sandstones have generally high porosity and rapid water travel can occur along unexpected routes and from any direction. Any surface sealing may do more damage by scaling and bursting than if the stone is left without treatment. Sealing of sandstones is therefore not advised at any time. Testing the efficiency of sealants: Several authors discuss waterproofing materials, silicones, urethanes, acrylates and stearates, as to their water absorption, spreading rates of water on the treated surface, water vapor transmission, resistance to efflorescence, and general appearance (Clark et al., 1975). De Castro (1983) measured the angle of contact of a microdrop (0.004 cm3) on a stone surface as characteristic of the wettability. Laboratory tests and limited field performance are described by Heiman (1981). The crest of a Gothic sandstone arch, which was sealed with silicone,

Jan 1, 1994

By W. Swisterski, G. Romaniszyn, S. A. Lukasiewicz

The present paper analyzes the motion of a particle of material in a horizontaly rotating tumbling mill. The sliding of the particle under action of dynamic and friction forces and its free flight fall are analyzed. It was found that mechanism of free-fall occurs at supercritical rotations of the mill.

Jan 1, 1991

By W. W. Bristol

The Jerritt Canyon Joint Venture project is located approximately 50 miles (80 km) north of Elko. Nevada, U.S.A. and produces between 250 and 300 thousand ounces of gold annually. The Joint Venture is 70% owned by Independence Mining Company and 30% owned by Meridian Gold Company. Independence Mining Company is the operator. The Jerrin Canyon Joint Venture started operations in 1980 mining a series of open pit mines. Since the early 1990's, the discovery of deeper ores has required the joint venture to develop and mine a significant portion of its annual production utilizing underground mining methods. Underground production started with the West Generator Mine in 1993 followed by the Murray Mine in late 1994. Presently, two additional underground projects are being developed. Underground mining at Jerritt Canyon is budgeted to produce 128 thousand ounces in 1997. This paper documents the major transition/redevelopment of the Jerritt Canyon mining methods.

Jan 1, 1997

By M. J. Scoble

There is no straightforward and systematic method for adequately measuring blast damage in on-going mining operations. This paper considers various techniques available for the measurement of blast damage, making particular reference to recent underground hardrock mine studies. This paper concludes by indicating the importance of understanding and accounting for geology and emphasizes the need for a robust damage-audit procedure.

Jan 1, 1997

By H. O. Seigel

This is an introductory paper on a new method of prospecting for mineral deposits which has been developed by Scintrex Limited. The method, which we call Luminex, for luminescent mineral exploration, is based on time- resolved mineral luminescence created by an ultraviolet light source. It has the ability to detect and resolve a group of key minerals which are either ore minerals themselves, or more often, are accessory or pathfinder minerals for certain types of economic ore deposits. Fortunately, these minerals are commonly found at the earth's surface, even in areas of considerable weathering. The method extends the range of mineral deposits which are remotely detectable from the air to include those such as tungsten, tin, molybdenum, gold and bedded lead-zinc deposits and, is therefore, a natural supplement to our three classical methods of airborne geophysics.

Jan 1, 1983

By J. Andrew Leach, Robert T. Tape, Thomas G. Harper

A practical approach to elope stability design of heap leaches up to 90 m (300 ft) high is presented based on recent experiences with heaps throughout the Western U.S. Shear strength parameters for foundations, ore and liner systems are considered, with particular attention given to frictional contacts between geomembranes and clay or geotextiles. Stability of both ore and containment dikes is discussed including the effects of seismicity, staged dike construction, progressive heap development and in-heap solution levels. Design criteria and methods of analyses are presented along with techniques for improving stability.

Jan 1, 1987

By R. L. Unger

Restricted fields of vision are a common problem with underground mining equipment. Also, when lighting systems are provided, they may be positioned where they cause glare. This restricts the visibility around the machines even further. To help address these problems, the US Bureau of Mines has developed a PC-based software package to aid in the analysis of certain human engineering aspects of mining equipment design. The software is available for use by equipment manufacturers and mining companies for design work on new machines, as well as for evaluating proposed modifications to existing machines.

Jan 1, 1995

By J. Paraszczak

With regards to the cost and profitability of a mining operation, the performance of the equipment employed is one of the key issues. Cost and profitability depend on, among other factors, the reliability and availability of the equipment. In an attempt to reduce equipment downtime, it is indispensable to collect and analyze reliable data and information on failures and maintenance actions. This paper reviews common problems encountered in this respect, with particular emphasis on the lack of uniform terminology and methodology. Recommendations concerning the standardiztion of reliability and maintainability concepts and measures are given. Regarding the benefits that the latter may bring, the paper concludes with a proposal for an industry-wide initiative in this respect.

Jan 1, 2002

By D. H. Davidson

The basic principal in the ISL process involves the recovery of metal values by moving fluids through rock instead of moving rock. The process combines surface and sub-surface operations, with the economic performance controlled by four major factors; rates of fluid injection and production from wells; the rate of mineral solubilization; the volume of rock swept by the fluid; and the volume of solution processed through the system. This paper discusses various technical and economic parameters affecting these four factors and how they impact project costs.

Jan 1, 1985

By J. S. Stachulak

Installation of a computerized mine monitoring and control system in two planned construction phases began in 1983. Phase one consisted of providing a central monitoring station located on surface for monitoring underground CO detection in Frood Mine's heated area. The implementation of this project annualized labour savings of $200,000. The cost of installation of an early fire warning system was $100,000. There are several CO sensor monitoring carbon monoxide trends through mine heated areas. To obtain an early warning, it is not good enough to know that a fire has started, but it is also necessary to know where the fire is located.

Jan 1, 1989

By H. Polat, M. Polat, S. Chander

A high shear treatment step was observed to improve flotation of coal. The effect of high shear treatment (HST) was a strong function of coal rank, however. For the low rank coals the HST produced loose, open-structured agglomerates which decreased the entrapment of ash minerals. For the high rank coals, the high shear treatment promoted detachment of low-floating particles from the agglomerates that ordinarily formed in a flotation cell. The extent of agglomeration and detachment of particles from the agglomerates was a function of the amount of dodecane and coal rank. To obtain desired efficiency of separation ethylene-propylene oxide block co-polymers were used. The results showed that the HST-flotation technique increased the ash rejection considerably for both high and low rank coals, though the mechanisms were different.

Jan 1, 1995

By M. G. Karfakis, K. P. Chong

Determination of fracture toughness using the semi-circular specimen, the chevron edge notch round specimen, the short rod specimen and the cylindrical burst specimen, are critically reviewed. These methods, among all, are the most applicable for fracture toughness determination of rocks. They require minimum machining. Samples are small, and testing procedures are simple. They have a sound analytical basis and allow the fracture toughness to be determined without measurement of fracture length.

Jan 1, 1986

By W. C. Carter

In mid 1978 Inland Cement Industries Ltd. brought on-line their new one million megagram (Mg) per year cement plant at Tilbury Island, Delta, British Columbia. The Plant--Its Philosophy of Design The design of this plant began in 1974, at the beginning of the rapid rise in petroleum costs later referred to as the "energy crisis". The trend in fuel costs was clear, so one of the basic criteria for the selection of process equipment was high thermal efficiency. Throughout the process of selection of materials handling and process equipment, energy consumption was a factor in decisions. A second factor which influenced the design of the plant was its location on navigable water. The plant is designed to make maximum use of this means of transport to minimize transportation costs. All raw materials (and some fuel) are received by water, and a major portion of the cement and clinker is sent out by barge. Extensive modern dock and material handling facilities were provided to accomplish the shipping and receiving functions. A plant meeting stringent environmental regulations was the third major factor which formed the basis for design. To meet this requirement, all storage facilities had to be covered, 53 bag type dust collectors were applied throughout the plant, and materials handling equipment was designed to minimize dust and spillage.

Jan 1, 1979

By Fernando Concha, Arturo Barrientos

The flow in a hydrocyclone is divided into a boundary layer around the walls, an exterior inviscid flow and an air core in the center of the equipment. The boundary layer flow over the lateral walls is associated with the short circuit of particles to the underflow, while the boundary layer over the top of the hydrocyclone and the outer part of the vortex finder tube is related to the short circuit of particles to the overflow. Classification takes place in the exterior flow. The model can be validated with pilot or industrial data and simulates the performance of hydrocyclones in a wide range of design and operating variables.

Jan 1, 1992

By Jon C. Yingling

Techniques for optimization of mineral processing flowsheets are reviewed. Though not yet widely used in the minerals industry, approaches for chemical process optimization based on successive quadratic programming (SQP) algorithms may be employed to determine optimum unit design and control settings for a mineral processing flowsheet. Moreover, in certain mineral processing flowsheet applications, specialized techniques can be applied because of the nature of the system relations. These techniques offer advanta es in efficiency. Moreover, their capability exceeds that o f the SQP approaches since simultaneous optimization of circuit configuration and unit controls can be addressed.

Jan 1, 1990

By D. R. Nagaraj

Literally thousands of new flotation agents, both collectors and modifiers, have been proposed for sulfide and non-sulfide flotation over the past six decades since the beginning of the use of soluble surfactants in flotation. In stark contrast, the number of flotation agents used in practice is small. Xanthates and fatly acids, along with a few well-recognized modifiers, dominate the industry. Three major questions will then arise: a) are there truly specific needs in the industry that call for chemistries that are different from those used currently ? b) if yes, given the track record in the industry, what is the likelihood that such different chemistries will ever be used and to what extent ? and c) is more research into developing new chemistries necessary ? A critical assessment of flotation agents in general is made in this paper to provide answers to these questions and to identify the major factors that are responsible for the large disparity that exists between flotation reagent research and commercial usage.

Jan 1, 1994