Search Documents

By R. D. Hansen, R. R. Klimpel

This paper discusses the influence of frother type and dosage on recovery/selectivity in coal/sulfide mineral flotation as a function of particle size. It is shown that different frother structures exhibit quite different but consistent performance characteristics depending on the underlying particle size ranges involved as well as the dosage levels of both the frother and collector. The data presented on existing commercial frothers and some new special purpose experimental frothers is used to illustrate some general operator guidelines on proper frother selection and use.

Jan 1, 1987

By Alan Fricker, Bill Owers

Cyprus Gold NZ Ltd will be recovering residual cyanide from their CIT, operation in New Zealand. The process will use air to strip the cyanide from the acidified barren pulp. DSffi. Industrial Development, who were involved in the bench and pilot studies for Cyprus, have extended the concept to pregnant pulp. The stripping of pregnant pulp eliminates the substantial loss of cyanide through carbon catalysed oxidation during the adsorption stage. A 50% increase in cyanide recovery was obtained from an extensive laboratory investigation. The presence of a cyanide recovery circuit enables leaching to be conducted, without detriment, at pHs at least as low as 9, with consequential 50% reductions in the consumption of lime and sulphuric acid. There should be a small reduction in carbon consumption, and a significant improvement in the quality of the final effiuent, at least in terms of cyanide, cyanates, copper, zinc and sulphur. A small but significant increase in gold recovery can be expected too. There is a net economic advantage of NZ$1.20/tonne of ore by stripping pregnant rather than barren pulp.

Jan 1, 1990

By G. F. Revey

Most commercial explosives contain from 70% to 94% (by weight) ammonium nitrate. When some of the explosives end up in shot rock and ore, through either spillage or incomplete detonation, ammonia and nitrates can leach into the ground water. In recent years, state and federal regulators have applied more stringent water-quality standards, particularly at new mines and development projects. When mining conditions permit, bulk ANFO, a mixture of ammonium nitrate and fuel oil, is the explosive of choice. ANFO is less costly than other explosives but it dissolves readily in water. Several case histories in the United States and Canada show a clear connection between uncontrolled losses of bulk explosives and high nitrate levels in mine effluents. Mining companies have tried several approaches to reduce ammonia and nitrate levels in groundwater. These approaches range from controlling explosive losses to treating the mine effluents. In this paper, controlling explosive losses is addressed For both packaged and bulk explosives, guidelines to limit losses during storage, handling and use are described in detail.

Jan 1, 1997

Lingering effects of the 1990 oil shock that included overbuilding and corporate and individual financial distress caused the Gross Domestic Product to fall slightly to $5.67 billion (US billion = l09). With 254 million people - 697,000 in mining and petroleum - the US has more than 100 million dwelling units and 190 million licensed motor vehicles. New private housing starts fell 15% to one million units. New car production fell 11 % to 5.4 million units. Truck and bus production fell 8% to 3.4 million units. The inflation rate was 3%, while the prime rate of interest was 8.5%. The Producer Price Index (1982 = 100) changed as follows: -fuels and related products and power down 1% to 8l, • metals and metal products down 2% to 120, • chemicals and allied products up 2% to 126, and • non-metallic mineral products up to 2% to 117. Energy Imports of crude and refined petroleum, costing $50 billion, fell 5% to 2.8 billion bbl. Domestic petroleum production rose 1% to 3.6 billion bbl. Petroleum supplied about 39% of US energy, natural gas 24% and coal 22%. The National Energy Strategy was announced in February 1991. Its purpose is to encourage domestic production of fossil fuels and nuclear and renewable energy and to stimulate efficiencies in use. Congress continued to debate the strategy and took no action. Coal production fell 3% to 902 Mt (994 million st). About 60% of that came from surface operations. Seventy-eight percent of the total was used to generate electricity and 3% was coked.

Jan 1, 1992

By Richard Jr. Ray, David Johnston, Phil Blankenship

Injection of inert gases to combat mine fires has been practiced in various parts of the world for a long time. Of late, nitrogen has become the preferred inert gas for control of mine fires and safe salvage of longwall equipment as compared to carbon dioxide or fuel gases produced from burning of fuel. In India, carbon dioxide has been used for fire fighting in a number of mines during the 1960s and 1970s. More recently inert gas produced from burning of fuel oil in surface plants has been used in controlling the atmosphere in fire areas in two mines. In yet other cases, liquid nitrogen has either been poured directly into fire areas in liquid form or injected in gaseous form to keep the fire in check. Nitrogen produced in liquid form in an oxygen plant is more costly than nitrogen produced from PSA (pressure swing adsorption) based plants. A PSA-based plant has been installed in one of the Indian mines in 1986 and more are in the offing. This paper reviews the application of various inert gases in Indian mines and discusses the likely trend of inert gas application in Indian mines in the future.

Jan 1, 1989

By William H. Dresher

The crust of the earth, together with its seas and its atmosphere, is the source of all of mankind's primary wealth. Indeed, most people think of precious metals and stones when they think of wealth mined from the earth, but the value of the material and energy goods derived from the earth far exceed the value of the precious metals and gem stones. Thus, it is obvious that all minerals which we mine from the ground represent new wealth--the copper, clay, or petroleum we mine just as much as the gold or silver. More and more, wealth is defined in terms of utility-not in terms of an arbitrarily established monetary value. The recent action of the OPEC nations in controlling the flow of petroleum has clearly demonstrated this to the petroleum-importing nations! There is developing in the United States, as well as in many other nations of the world, a concern for the future availability of many mineral-derived raw materials and of mineral fuels. Ore grades are diminishing, concern for the environment has placed restraints on commercial development of some mineral deposits and the processing facilities necessary to exploit them, and countries upon which we have relied for major mineral materials have become increasingly nationalistic, causing uncertainties in future supply and causing an increasingly alarming deficit in our nation's balance in trade.

Jan 1, 1980

By Edwin H. Bentzen

Talc, as a mineral, is rather widespread, but as an ore sultable for mining, it is rather limited. Materials sold as "talc" range from the impeccable white material from Italy to a gray-green-bluish material from Virginia. Some uses of the material called "talc" seem to be determined by the color of the material, some by the chemistry of the material, and some by the particle size of the ground material. But, there seems to be some overlapping of criteria used to judge the acceptability of a raw material. So then, any producer of talc material that is not a consumer of this raw material is faced with the age-old problems: "what do I call the stuff, and to whom should I try to sell it?" The answer to the first part is easy: if you want a high price, call it "talc"; if you want a low price, call it "soapstone". This may seem like a very simplified answer, but it is apparent that some of the products sold as "talc" have more than a minor amount of impurities in them; whereas, if they were called "soapstone", these same products would probably get a lower price.

Jan 1, 1973

By W. K. Summers

During the past few years monitoring systems have been installed to measure the effects of environmental changes on the ground-water resource. The design of a monitoring system depends upon the designer's perception of how the environmental factors merge with his perception of the ground-water flow system. The validity and representativeness of measurements made during a monitoring program depend upon the validicy of the designer's perceptions and concepts. To optimize the design of a ground- water monitoring program the designer should make preliminary measurements to confirm his assumptions.

Jan 1, 1985

By G. Almgren

With the exception of sublevel caving, the most common method of underground mining in Sweden is the "cut-and-fill" method. It is normally used for mining non-ferrous metals , and' is used extensively in the complex sulfide ore mines of the Boliden Company in north and central Sweden as well as the mines of the STORA and Vieille Montagne Companies in central Sweden. All in all, the cut-and-fill method is used in 13 of Sweden's 45 mines. As the mines are relatively small, the volume of ore mined by this method represents only about 5 % of the total ore production in Sweden. The commercial value, however, is much large than this percentage would imply. The production volumes and grades of some typical mines are shown in Table I. As seen, when rated internationally, the grades are comparatively low. The prices are set according to ?international metal prices? as dictated by the London stock exchange, and in lieu of governmental support, rational management methods are critical in order to achieve satisfactory profit.

Jan 1, 1975

By F. G. Loper

Simulation as a mathematical technique is not new. However, recent increases in digital computer speeds and the ease of programming with languages such as Fortran have centered a good deal of attention around simulation in the last few years, Many sophistications of the method have been developed during this time. However, the ability to simulate mathematically still hinges on the ability to ignore unimportant details which would complicate the mathematics and make simulation impractical, Thus, with this attitude in mind, it becomes very easy to design a pseudo- simulator which will predict average conditions very well, but can not truly allow a detailed study of the system being simulated. Most simulations fall into this category, along with the case mentioned here. This paper is not intended to be a critical treatise of the simulator used to study a particular mining system. Instead, it will be used to illustrate the aspects of simulator development. The steps in the development of any simulator are described, along with same detail of the phosphate mine simulator itself.

Jan 1, 1966

By John T. Awald

The efficiency of search for porphyry copper and molybdenum deposits can be greatly increased. A model exploration system is here presented to show how geologic literature data and field surveys can be aided by modern statistical and computer methods. Assuming that major ore deposits occur in clusters, it is possible to evaluate rapidly large areas at modest cost and with minimum investment risk. An example of the success of these methods is given. Clusters of mine density and metal production covering the State of Nevada were plotted and machine contoured. Selection of a 47,300 square-mile area on the Nevada-California border was made. Within this area, detailed analyses were performed, and a 3000 square-mile site was picked for subsequent field examination. To initiate efficiently the field work, 81 stream sediment geochemical samples were collected and analyzed for copper, zinc, and molybdenum. These data established local variance and necessary statistical controls. Following this, a total of 151 geochemical samples were used to survey the 3000 square-mile area. Computer contouring of results directed attention to specific target areas for detailed geologic analysis, property acquisition and drilling. A total of 22 copper-zinc and molybdenum anomalies were identified. Four of these were recommended for further exploration. To date, two have been acquired and drilled and preliminary ore reserve and financial analysis have been made on one. The estimated cost and time for the regional exploration phases leading to these targets were thirty man-weeks and $16,000.

Jan 1, 1973

By Aaron Jones, Guy Reed, Russell Frith

"In 2017, one of the international authorities on coal bursts, Dr. Chris Mark, published a paper entitled “Coal Bursts that Occur during Development: A Rock Mechanics Enigma,” in which several relevant technical issues were identified, the most pertinent being:i.whilst development coal bursts are commonly associated with geological faults, understanding which specific faults result in burst-prone development mining conditions and why, remains undefined.ii.conventional wisdom in relation to strong roof and floor geology of the coal seam might be limiting, based on certain burst examples in Colorado.iii. development coal bursts can occur without the local ground stresses being substantially elevated from their in situ levels.This paper outlines what is considered to be a credible, first-principles, mechanistic explanation for these three current development coal burst conundrums by reference to early published coal testing work examining the significance of a lack of “constraint” to coal stability and an understanding of how very specific structural geology and other geological features can logically cause this to occur in situ, albeit on a statistically very rare basis. This basic model is examined by reference to published information pertaining to the development coal-burst that occurred at the Austar Coal Mine in New South Wales, Australia, in 2014 and from the Sunnyside District in Utah, USA.The “cause and effect” model for development coal bursts presented also offers a meaningful explanation for the statistical improbability for what are nonetheless potentially highly-destructive events, being able to explain the statistical rarity being just as important to the credibility of the model as explaining the local conditions associated with burst events.The model could also form the basis for a robust, risk-based approach utilising a “hierarchy of controls” to the operational management of the development coal burst threat. Specifically, these include the use of pre-mining predictions for likely burst-prone and non-burst-prone areas, the use of the mine layout to avoid or at least minimise mining within burst-prone areas if appropriate, and finally the development of an operational Trigger Action Response Plan that reduces the likelihood of inadvertent roadway development into a burst-prone area without suitable safety controls already being in place."

Jan 1, 2019

By J. A. Wallace

U. S. Steel's coal mining research activities are directed toward providing new or improved hardware and techniques to increase productivity or reduce cost. Because more than 80 percent of U. S. Steel's coal production is obtained from continuous miner sections, most of our research efforts are focused upon that mining system. Current and historical time study data show that our continuous miners only operate about 30 percent of the available face time. This limited equipment utilization is the result of the delays or interferences imposed by the non-coal-cutting phases of the continuous mining cycle. The most time consuming of these delays are: waiting-on-roof-support, tramming between alternate work locations, waiting-on-haulage-capacity, and in some mines waiting for excessive methane concentrations to clear. Because waiting on roof support is our most time consuming delay, several programs are underway simultaneously to address this problem. In one of these we are developing a patented microprocessor-based control method and apparatus to improve roof drilling performance. This increase is attained by using the microprocessor to adjust electrohydraulic valves which control drill thrust and rotation speed. The microprocessor is designed to continuously search for an optimum combination of thrust and drill rpm to maximize penetration rate at all times.

Jan 1, 1979

By Richard H. Olson

Talc deposits in the Precambrian of southwestern Montana (Beaverhead and Madison Counties) are unique within the U. S. A. in that large bodies of tremolite-free talc can be open-pit mined. All known deposits are in pre-Beltian dolomite units. The origin is suspected to be metasomatic, with the siliceous component having been contributed by an intrusive Precambrian granite gneiss. Precambrian deformation was extreme and is characterized by multiple periods of tight isoclinal folding and the flowage of less competent rocks, rather than by faulting. Post- Precambrian folding has been relatively negligible; the characteristic Laramide structure is block-faulting developed along northwest-southeast trends. The talc is thought to have been formed in Precambrian time; the high-angle block-faults probably have no significance with regard to the formation of the talc, but do tend to complicate mining operations. Tremolite-free talc ore bodies with horizontal widths of more than 200 feet, vertical depths of several hundreds of feet, and strike-lengths of as much as one-half mile are known in the Ruby Range and the Gravelly Range. Where dolomite is interbedded with tremolite-free talc in the Gravelly Range, the scale of this relationship permits the use of conventional open-pit mining methods with subsequent upgrading by hand-sorting techniques. Underground mining has been used in the past, but all current Montana talc-mining operations are on the surface. The hand-sorted ore, some of which is shipped overseas, is finely ground or micronized in roller mills and fluid-energy mills. The products are distributed both nationwide and abroad.

Jan 1, 1975

By Adolf U. Honkala

Dundee Cement Company was incorporated in 1958. The equity capital for the venture was supplied by a Swiss firm called Holderbank Financier and a group of its principals. Holderbank Financier, a holding company, is a direct outgrowth of Holderbank Cement Company, a company founded in 1912 by the father of Dr Hans Gygi who is the president of Dundee Cement Company and a member of the Board of Holderbank Financier. From one plant in 1912 located in Zurich, Switzerland, Holderbank grew to its present size of 32 plants in 17 countries, having a capacity of 90 million barrels of cement per year. Dundee Cement Company constructed its first cement plant near the little town of Dundee, Michigan. This site was selected because there is an abundance of limestone and clay of the correct chemical composition for cement manufacture and the deposit was advantageously located near the large population centers of Detroit, Toledo, Cleveland, and Chicago. Construction of the 5. 5 million barrel, two kiln, plant was completed and the plant started up in the fall of 1959. After a year or two of the usual problems in a new plant and the expected difficulty of breaking into a nearly saturated market, Dundee began to prosper.

Jan 1, 1970

By William R. Nash

The scope of work for the fast track construction of the Weeks Island Replacement Facility, Weeks Island, Louisiana included the design and construction of two salt mines. Mine #1 - An interim underground mining level consisting of a 975 m (3200 ft) incline and 3520 m of 5.5 m x 7.3 m (11560 ft of 18 ft x 24 ft) drill and blast excavation; raise boring; core drilling; roadheader excavation; complete bulk material handling facilities utilizing an existing production shaft. Mine #2 - Simultaneous with the interim mine construction a new one million ton per year underground salt mine was constructed consisting of: two 5.5 m diameter x 381 m (18 ft diameter x 1250 ft) deep shafts; 76450 cu m (100,000 cu yd) of drill and blast bottom excavation; surface and undergound bulk material handling systems (conveyors, skip loaders, shaft equipment, hoisting); ground freezing for water control for both the production and service shafts; the design of the first underground doublewall slipform installation of a dynamic bitumen shaft lining system; the emergency grouting of both the existing production shaft and the interim mining level in the salt dome; 227 mt x 64 m (250 ton x 210 ft) high structural steel production headframe; 2.2 MW (3000 hp) double drum mine hoist; service shaft headframe; and service buildings.

Jan 1, 1987

By Wilhelm J. Kogelmann

The quest for U.S. energy independence will result in a major increase in underground mining operations. It will necessitate the rapid excavation of development drifts, entries and slopes to exploit underground deposits of energy resources such as coal, uranium and oil shale. Most of this development work will be done in soft and medium hard rock up to an unconfined compressive strength of approximately 20, 000 psi. OBSTACLES TO RAPID TUNNEL EXCAVATION Labor In the U. S. coal mining industry, the underground productivity in tons per man-day declined from 15. 61 in 1969 to 11. 00 in 1973 which is a startling 30% decline. While productivity declines, the cost of labor and supplies continues to rise. Ralph E. Bailey of Consolidation Coal Company recently stated four reasons for the decline of productivity: A shortage of experienced miners, enactment of the Federal Coal Mine Health and Safety Act effective April 1970, major changes in union work rules in 1968, and a deterioration in the attitude of the work force (1). Because there is already a great shortage of skilled miners, the situation will get worse when large new mines for oil shale, coal and uranium open in sparsely populated areas in the Western United States. Only the large scale use of easy to operate tunneling machines can increase productivity and lower the cost of excavation.

Jan 1, 1974

By George H. K. Schenck

It seems appropriate to review the history of mechanization of our underground coal mines at this time when many favorable flags are flying for this industry. It is a reasonable hope that such a review may stimulate thinking as to the directions that new technological developments are apt to take and in which members of the Society of Mining Engineers are destined to play important roles. Discussion of the relative importance of the various changes that have taken place since the advent of electric power provides the starting point. It is in the economic factors utilized that we find conditions which permit more efficient utilization of the capital committed to the industry. Concepts rather than specific items are emphasized in the following discussion because once the value of a concept, such as mechanical conveyors, is established, it then spawns many variations which are not significantly different. The shift from animate to inanimate energy has been the most important change in the modern industrial scene, including coal mining. Although introduced into coal mines for some purposes early in the period of general electrification, the coal industry adopted mechanical power relatively slowly, and 1944 was the first year in which a majority of deep-mined coal was mechanically loaded.

Jan 1, 1968

By B. C. Bhowmick, B. B. Dhar

Central system of ventilation, adopted almost universally in coal mines of India and elsewhere in the world, has often proved deficent in providing a cost effective solution to the acute ventilation problems of remote workings in many mines. Loss of air due to leakage through a number of stoppings, doors etc. and accumulation of heat and moisture by intake air on its way to a working through long and circuitous route are the main unavoidable reasons for low efficiency of the system, sluggish and oppressive ventilation of workings. Multi-zonal ventilation system using large diameter bore holes for feeding fresh air in the mine close to a working has been proposed as a viable economic alternative. The method promises to provide congenial environment at working faces without resorting to air conditioning or use of booster fan. Optimum location and diameter of bore holes as well as general design procedure have been dealt in the paper. Finally, the technical as well as economic advantages of the method over the conventional design have been highlighted with the help of a case study where ventilation system of an extensive shallow mine in Central India has been redesigned according to the old and the new concepts. The methodology is general enough for adoption elsewhere in other mines under similar circumstances.

Jan 1, 1993

By L. Kulik

Sustainability of lignite mining in the Rhenish lignite mining area is ensured by a preceding study of the overall project, with the involvement of all those affected. The supporting holistic consideration of the various sustainability elements is essential for a later balancing of the several ecological, economic and social concerns. In what follows, a brief overview of the Rhenish lignite mining area is given as introduction to the focus of this report, which is on sustainability, starting with the approval procedure under regional planning law incl. opencast mine planning, and extending to concrete on-the-spot implementation, taking the Garzweiler II follow-up mine as example. To illustrate the issues involved, an account is given of some selected sustainability elements.

Jan 1, 2005