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By Robert E. Thurmond

With modern exploration techniques, it seems likely that an increasing number of the orebodies to be found in the future will be under alluvial fans or valley fill. As a result, a larger proportion of open pit mines will be confronted with the necessity for removal of substantial quantities of alluvial overburden; whereas in the past, for the most part, the open pit mine operator has dealt mainly with hard rock. If this proves to be the case, methods, equipment, and costs for alluvium stripping will become an increasingly important factor in open pit mine planning. Several operations are now faced with this situation, and various methods and equipment are used. At Pima Mining Company's operation the stripping ratio is in the range of 6/1 Well over half of the stripping volume is alluvium. The alluvium is removed almost entirely by carryalls hauling direct to a waste dump. Some removal has been accomplished by shovel and truck operation; more will be done by this means in the future. At American Smelting and Refining Company's neighboring .Mission Mine, nearly all alluvium removal is by large shovels and, trucks. U. S. Borax's Boron operation is accomplishing alluvium removal with carryalls but has been investigating other methods and equipment. The various operations in the Gas Hills Uranium District in Wyoming are stripping mainly with carryalls, although some small draglines are employed. The M. A. Hanna Company in the Mesabi Range employs large draglines and conveyor systems for removal of glacial fill. Nchanga Consolidated Copper Mines in Northern Rhodesia strips overburden with a large excavating wheel and conveyor system. There are no doubt other open pit operations with which the writer is not familiar, that are handling large quantities of alluvial overburden.

Jan 1, 1963

By James S. Browning

The Mineral Resources Institute of The University of Alabama conducted research on the removal of sulfur from coal using a combination of gravity concentration and flotation methods. The research utilized the gravity and centrifugal force capabilities of the Humphreys spiral to remove part of the pyritic sulfur and ash. Flotation of the Humphreys spiral coal concentrate removed additional sulfur and ash to yield products that conform to Federal air quality standards for sulfur oxide emissions. The clean coal products recovered by the combined process contained 7.7 to 8.0 percent ash, 0.12 to 0.16 percent pyritic sulfur, and 0.78 to 0.96 percent total sulfur. Pyritic sulfur rejection by the process was about 95 percent. In addition to obtaining good recoveries of high quality coal the tests demonstrated that the pyrite in the wastes could be isolated as enriched flotation products by the combined gravity - flotation apporach. Pyrite concentrates analyzing 25 to 33 percent sulfur were recovered. Potential benefits of the pyrite flotation step are recovery of a product of possible market value and the elimination of the pyrite from the waste ash which could be a potential acid water problem when impounded.

Jan 1, 1981

By D. E. Walsh

Over a period of seven years (1989-1996) the Mineral Industry Research Laboratory (MIRL) University of Alaska Fairbanks, has investigated the effects of temperature, residence time, and particle size on the degree of low-rank coal (LRC) upgrading for a non-evaporative, hydrothermal drying process, also known as hot water drying (HWD). Three Alaskan LRCs were used in this study: Usibelli coal (Seam No.4) from the Nenana Coal Field, Little Tonzona coal from near McGrath, and Beluga coal from the Beluga-Yentna field on the west side of Cook Inlet. Replicated, factorial tests were conducted. Experimental results indicate that most of the low-rank coal upgrading via HWD occurs rapidly within the first 10-20 minutes of residence time. Thereafter, the upgrading process slows down and over 100 minutes of additional residence time are required to produce similar percentage increases in coal properties to those achieved in the first 10-20 minutes. The properties of the hot water dried products were very sensitive to process temperature. Calorific value, carbon and oxygen contents, equilibrium moisture levels and Hardgrove grindabilities all appear to change linearly with temperature within the 275" C to 325" C range.

Jan 1, 1997

By Adil Jamali, Taufiq Hidayat, Imam Santoso, Zulfiadi Zulhan, Indah Suryani

The study investigates the segregation of iron and titanium in iron sand concentrate pellets reduced using coal under an isothermal-temperature gradient profile. The results show that metallic iron migrates to the surface while titanium and other oxides move to the center of the pellet. The study provides insights into the reduction process and the behavior of iron and titanium during heat treatment.

Mar 2, 2022

By M. H. Bolu

Since undergoing a major mill expansion in 1979, Canada Tungsten Mining Corporation Limited has successfully operated a somewhat unconventional rod mill/rod mill grinding circuit at its mill in Tungsten, N.W.T., Canada. The concentrator employs two rod mills in series, of unmatched size and horsepower, for production of feed to a gravity (tabling) circuit. Cyclones and screens are closed circuited with the secondary rod mill. Outlined in this paper are the rationale behind, and consequences of operation of this unusual grinding and classification configuration.

Jan 1, 1984

By Michael L. Clar

Reclamation of surface mined lands has two basic objectives: (1) the elimination or abatement of undesirable environmental conditions, and (2) the restoration of mined land to its former or more productive uses. This paper addresses some of the planning concepts and site factors that influence the selection of suitable land uses for surface mined lands. Three planning concepts included in the discussion are: (1) mine land planning, (2) comprehensive land use planning, and (3) environmental site planning. The site factors that will influence the selection of an appropriate land use have been grouped into three categories: (1) legal, (2) geographic, and (3) natural. The natural factors are further subdivided into three groupings: geomorphology, soils, and climate.

Jan 1, 1981

By E. H. Kurt

INTRODUCTION The simplest way to drill a hole into rock is to strike a steel chisel or drill bit with a hammer. Early miners used this elementary hand technique so successfully in "single jacking" and "double jacking" that the first mechanical rock-drill designers sought to duplicate it. However, in the early developments, the designers were forced to retreat to a construction known as the "piston drill," wherein the entire drilling element is tied to the piston and reciprocates with it. It took nearly 50 years to devise a method of divorcing the two elements and to achieve the original hammer principle used in hand drilling. The Mont Cenis tunnel, drilled through the French Alps in 1861, usually is considered the birthplace of the mechanical rock drill. The Hoosac tunnel in Massa¬chusetts was drilled at about the same time, and the success of these two ventures paved the way for innova¬tions that produced the Burleigh, Ingersoll, Sergeant, and Waugh piston drills between 1870 and the turn of the century. In 1897, George Leyner of Colorado introduced what has been considered the most significant development in rock-drill history. He devised the hollow drill steel for water flushing; when combined with his free-piston hammer drill, this became the first lightweight and dust¬free underground machine. In addition, Leyner's drills introduced improvements such as automatic rifle-bar rotation of the drill steel and chuck, automatic lubrica¬tion, and an enclosed throttle control. During the 1920s and 1930s, automatic feeds, centralizers, sliding cones, and the automatic water back head were developed, laying the groundwork for all pneumatic underground drills currently in use. Since these pioneering efforts, rock-drill development has been concerned primarily with refining the designs and improving the metallurgy to make faster, lighter, and more dependable machines. Fig. 1 illustrates the progress in drilling speed during the first 125 years of rock-drill development; that progress is a credit to the persistence and inventiveness of the designers in the rock-drilling industry. ROCK-DRILL CLASSIFICATIONS To meet the variety of conditions encountered in rock drilling, several distinct types of drills have been de¬veloped. In general, rock drills may be classified as either hand-held or mounted, with the hand-held ma¬chines including the jackhammer or sinker, the jackdrill or jackleg, and the stoper. The mounted drills are com¬monly known as "drifters." Table 1 shows that each type of drill is available in several sizes from different manufacturers. Fig. 2 illustrates a typical rock drill, showing the principal components. The jackhammer or sinker, shown in Fig. 3, is used primarily for general mine utility work such as drilling anchor holes (short vertical holes to bolt or anchor machinery), pin holes (short, usually horizontal holes to fasten sheaves, etc. to side walls), popholes (for blasting large boulders), and similar applications. They also are used for shaft sinking. Jackhammers are classified ac¬cording to weight, and they range from 7 to 30 kg (15 to 65 lb). The rock drill originally known as a jackleg was made by clamping a pneumatic cylinder or leg to a jack¬hammer, both to support the weight of the machine and to feed the tool forward in horizontal or uphole work. The more modern jackdrill refined this concept to make the hinged pivot for the leg integral with the drill cylinder and to group all drill and leg controls in the drill back head for convenience. Fig. 4 illustrates a typical jackdrill. Jackdrills are classified according to cylinder bore size, ranging from 60 to 83 mm (2.375 to 3.25 in.). Because of their light weight and versatility, jack drills are very effective in small drifts, small tunnel head¬ings, and stoping. The larger machines are applied to hardrock formations and in applications where drilling speed is a primary consideration. In soft formations or

Jan 1, 1982

By J. Rao Mokka

Extensive exploration has resulted in delineation of a massive sulfide district on the north flank of the east-central Alaska range. The district covers approximately 400 square miles and contains numerous stratiform; transported and some replacement type sulfide deposits ranging in size from less than 1 million tons to 20 million tons. Five types of ores were sampled for the study. Mineralogical analysis revealed that the minerals are too fine grained for conventional grinding and beneficiation. Hydrometallurgical studies were con-ducted using ferric chloride as a lixiviant. Ore microscopic studies as well as electron microprobe analyses of minerals in the raw samples and leach residues explained the low recoveries for certain elements as well as sources of impurities that need to be eliminated from the process streams.

Jan 1, 1991

By J. S. Hall

The performance of a full-scale balling drum circuit is well known to fluctuate, and is difficult to control. The fluctuations stem from causes that are not readily quantifiable. Results from plant tests show that surging of the recycle tonnage is dependent, inter alia, on the method of bentonite addition, small variations in drum or cutter bar speed and the method of drum water addition. This paper presents detailed observations from experiments on full-scale drum circuits, including preliminary results of a computer measurement and control scheme. Size distributions measured at points along an industrial drum are presented, together with the results of a mathematical model fitted to one plant data set. Model predictions are also included emphasizing the importance of screen performance on circuit stability.

Jan 1, 1983

By M. A. Georgiana

The Emerald Mine No. 1, located in southwestern Pennsylvania is presently owned and operated by Cyprus Minerals of Englewood, Colorado. High volatile bituminous coal is produced from the Pittsburgh No. 8 seam by both longwall and continuous mining methods. The coal is then mechanically cleaned on site utilizing a combination of heavy media separation and froth flotation methods prior to shipment to both the metallurgical and steam coal markets. The Emerald Mine is presently producing 2.8 million raw tons per year, while liberating approximately 6.5 million ft per day of methane. In light of the methane liberation rate, ventilation requirements have been significant and have always received utmost priority and consideration. Figure 1 shows the locations of the current and proposed shafts. Emerald utilizes two Joy (Model M120-58-880) axial vane fans on shafts No. 1, No. 2R, No. 3R. (one operational, one stand-by) The use of computer simulation of various ventilation networks was initially employed during the design stages (1975-1977) and has been utilized through the present. Obviously, the initial planning, under the ownership of Lykes Resources, was strictly theoretical. All the quantities were proposed and the resistances were based on prior simulations of other mines and mathematical formulas. However, once the mine was moderately developed, actual values were recorded and utilized. This procedure consists of: a) layout pressure and quantity points b) measure all air quantities where an air course splits

Jan 1, 1986

By J. W. Gunnett

Abstract. The Surface Mining Control and Reclamation Act of 1977 (PL-95-87), Section 522, establishes requirements for state regulatory authorities to designate lands unsuitable for all or certain types of surface coal mining. Any party having an interest in an area that may be affected can petition for it to be designated unsuitable for mining. Section 522 could present major obstacles to the mining industry by typing up an area in an endless round of petitions. The program under development for Kentucky is examined and analyzed as an example for determining the hidden impacts of Section 522.

Jan 1, 1980

By William G. Wilson

In the U.S. today a number of tentative synthetic fuel plants have been sited by a number of major corporations. Each of these for a number of reasons have deferred construction. The only synthetic fuel plants under active development are those being built with the Energy Research and Development Administration (ERDA) under the authority of the Non-nuclear Energy Research and Development Act of 1974 (Public Law 93-577). Under this Act in joint sponsorship with industry, a series of coal conversion pilot and demonstration plants are being built to produce environmentally acceptable fuels from high sulfur coals. Before entering into a discussion of the factors associated with the siting of the ERDA coal conversion program, the difference between a pilot plant and a demonstration plant should be explained. The terms pilot plant and demonstration plant iridicate a size of plant rahter than technology. A pilot plant will vary from an "add-on" to an existing facility to an independent unit. Demonstration plants are a wholly independent, self contained plants, capable of independent operation to demonstrate the environmenta1, economic, and technica1 feasibility of a technology. These plants are from one-third to one-tenth the scale of a commercial operation and often described as plus 1000 tons per day of coal consumption. Their purpose is stated in the Act (Section 6, (3)(E),) "to accelerate the commercial demonstration of technologies for producing syncrude and liquid petroleum products from coal: Provided. That the Administrator shall invite and consider proposals from potential participants based upon Federal assistants and participation through guaranteed prices or purchase of the products .... " In site selection and plant design it has been suggested that special interest groups should be allowed to dictate the site and specify the design. Under the present program the industrial partner who is contributing 50 percent

Jan 1, 1977

To generate a most profitable ultimate pit limit is generally the first step in mine design. This paper presents a new graph theory oriented, optimum ultimate pit limit design algorithm which will maximize the total undiscounted net profit. This algorithm performs much better than the well known Lerchs-Grossmann algorithm, in terms of the reduction in computation time and computer memory requirements. This algorithm operates on many directed trees in a graph, where each vertex in a tree represents a block in the mine model. The formation of each directed tree is based more on the ore-waste support concept than the geometry constraints alone. The general procedures of the algorithm, programming considerations and two case study results are discussed in the paper.

Jan 1, 1990

By J. Boldy

The discovery of the Delbridge massive sulphide deposit in the Noranda district of Quebec resulted from an appreciation of the significance of a mercury leakage halo as a litho-chemical pathfinder to blind ore, coupled to its location relative to a geologically inferred ore-bearing horizon within complex volcanic stratigraphy. Systematic sampling of micro-fractures present in outcrops delineated a diagnostic anomaly, drawing attention to an area considered prospective for buried ore. The massive sulphide deposit was subsequently found to be blind and topped at the 110 metre level.

Jan 1, 1984

By M. E. Rossi, J. A. Bassan, J. B. Novillo

Sampling and geological models are the basis of recoverable resources models. They are pillars of mineral resources and reserves estimation, and what geostatistical methods for grade estimation should rely upon. The resource model is best estimated if geostatistical methods make good use of sound geologic models. Data collection from the original drill holes, including field procedures and the quality assurance and quality control (QA/QC) of those samples are pillar one of a resource model. The second pillar of the model is the good use of the logged geological information, resulting robust geological interpretations, and the corresponding three-dimensional models of those interpretations. These models are partly subjective and mostly conditioned by the quality of logging and the geologist’s experience. They are also conditioned by the quality of the three-dimensional models built, regardless of the modeling method employed, traditional or implicit. Grade estimation is more commonly done by applying some geostatistical method and using the two basic sources of information, data and geologic model. Multiple stages are involved in this process, and in all of them there are uncertainties and risks that have to be dealt with. Knowledge, understanding, interpretation, and management of the model’s fundamentals are critical, given that they directly affect its accuracy and predictive quality. The mitigation of related risks allows for the creation of opportunities, generating value and reducing the project’s uncertainty. This paper discusses some of the key variables, uncertainties, and risks involved in the resource modeling process, illustrating with specific examples; discusses possible risk mitigation alternatives, and proposes best practices to avoid or mitigate those uncertainties. Emphasis is placed on taking advantage of technological advances without ignoring fundamentals. INTRODUCTION In the area of mineral resource estimation, one alarming trend that these authors have observed in the past 20 years or so is that the care and diligence in checking the work as it progresses has generally diminished. This is, perhaps, an unintended consequence of the availability of new technologies and tools that attempt simplify and speed up the work involved. This has led to a more casual attitude towards checks and balances that have to be in place at any given stage of the process before proceeding to subsequent stages, as best practices dictate. To some extent, some of these aspects are covered in international standards for resource estimates reporting (JORC, 2012; CIM, 2010). But these are broad, and do not specifically recommend best practices to a level of detail that would have an impact on certain aspects of the process. There are numerous references in the geology and mining journals and conferences that discuss the consequences of poor recoverable resource models (Baker and Giacomo, 1998; Vaughan, 1997).

Jan 1, 2019

By Calvin L. Stevenson

The probability of a particle passing through a maze is predictable and consistent. This principle may be utilized to effect a particle size separation of materials by presenting a physical maze to a stream of material that will allow the fine particles to pass, while deflecting the coarse particles. A maze is effective even though all apertures encountered are many times larger than the particles being separated. By designing a machine that allows the probability parameters to be controlled and varied without changing physical dimensions, probability sizing becomes a useful tool for the separation of granular materials.

Jan 1, 1967

By Paul F. Ph. D. Ziemkiewicz, Courtney D. Black

According to the American Coal Ash Association, 105 million tons of coal combustion products (CCP) were produced by the power generating utilities in 1997. Of that total, 1.68 million tons were used in mining applications (ACAA, 1997). Results have ranged from the environmentally beneficial to neutral and, in some cases, detrimental. Twenty years ago coal ashes: bottom and fly ashes constituted nearly all CCPs. With the shift to new emission control technologies at power plants, however, large volumes of new products are being generated. Many do not lend themselves to traditional ash applications such as cement formulation. Many CCP disposal sites are not documented with reliable pre and post application monitoring. In this report we discuss types of CCP, their relevant characteristics and the mining environment. We have attempted to identify a range of documented applications and to draw conclusions about their environmental effects including benefits and adverse impacts.

Jan 1, 2000

By George M. Hamilton

The gas producer actually dates back far beyond the period from which we first find recorded data. A partial production of producer gas can take place in any type of solid fuel grate equipment, such as a boiler, or even a fireplace if a sufficiently deep fuel bed is provided. Those of us who have watched a coal fire burning in the hearth, have no doubt noticed at times, the gases liberated by the heat burning on or near the surface of the fuel bed. So far as we know, the first gas producer was built by Bischof in Germany in 1839, followed by Ebelman in France in 1840, and Ekman of Sweden in 1845. The first large industrial development in the use of gas producers was When the two Siemens brothers of Germany patented their first combined gas producer and regenerative furnace in 1861, thus opening up the field for the use of raw, crude producer gas in heavy furnace work. In the years 1879-1881 J, E, Dowson, of England developed a producer gas cooling and cleaning plant, which extended the scope of application of producer gas to make possible its use in small furnaces and gas engines.

Jan 1, 1961

By R. P. King

The MODSIM mineral processing plant simulator is used to find optimal combinations of target separation specific gravities in a typical modem coal washing plant. A plant that is set up with these optimal targets can deliver up to 10% more yield at the same ash content as the same plant set up with separation targets chosen by conventional methods. MODSIM is the only simulator currently available that can simulate the liberation of pyrite and other mineral matter during open-and closed-circuit grinding operations. The simulator can therefore be used to assess the benefits of grinding operations in the flowsheet.

Jan 1, 1997

By R. E. Doerr

The successful technical demonstration of coarse coal slurry transportation at Consolidation Coal Company's Loveridge Mine in West Virginia suggests that it is now appropriate to seriously consider this technology in other applications, especially the transport of ' coal in surface mining. Early examination indicates that coarse coal slurry transport may be highly competitive with existing haulage systems, depending on a number of factors. These factors are not yet completely defined, but certainly will include production rates, coal physical and chemical properties, terrain, soil conditions, climate, water availability and quality, availability of skilled labor and other economic considerations impacting the existing haulage systems.

Jan 1, 1983