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By Charles T. Ford

Limestone neutralization of acid mine drainage has been proposed and examined as a method of treatment. However, limestones differ greatly in composition and structure. The reactivity of 14 selected limestones was studied, both by chemical and physical properties and by relative effectiveness in neutralizing synthetic and actual mine waters, and several guidelines for the choice of limestones are given. The particle size should be at least as small as 74 microns and preferably smaller. The most effective limestones are most nearly pure calcium carbonate. Stones which have a relatively low calcium con- tent but which contain calcite and have a large surface area are also effective neutralizers. Magnesite and dolomitic limestones are much less reactive. Disadvantages in using even the most reactive lime- stones for neutralization are indicated.

Jan 1, 1974

A portable surface impedance meter has been tested extensively over a wide variety of geological formations both in Australia and elsewhere. It has proved a useful geophysical too] for relatively shallow mapping (i.e less than 100 metres depth) of faults, intrusions, dykes and conductive ore veins and can be used as a depth probe for overburden and glacial ice. Case studies involving coal seam mapping at Collide (Qld. Australia), galena ore vein location at Zeehan (Tas. Australia) and glacial ice probing on the Brewster Glacier (South Island, New Zealand) are detailed. The first results of a similar unit using a lower frequency with consequential increase in depth of penetration will be presented. The application of VLF measurements to monitor blasting in mines and in the location of earthquake epicentres will also he introduced.

Jan 1, 1987

By James J. Bryja, Thomas M. Barczak, Dennis R. Dolinar, Joe Bower, Thomas P. Mucha

Maintaining ground stability in the gate roads, particularly the tailgate, has always been critical to the success of longwall mining, both in terms of safety and productivity. Several new support technologies have been developed in recent years to replace conventional wood and concrete cribbing for secondary roof support. Since their performance characteristics are unique, the best practices that have been developed with conventional wood cribbing may not be applicable for these alternative support technologies. Therefore, with so many options to consider and the importance of achieving adequate ground control at minimal cost, the trial and error approach to longwall gate road support is no longer prudent. This paper discusses a design methodology for standing secondary tailgate supports. This design technique requires in-mine measurements of tailgate support loading and convergence to establish a tailgate ground, reaction behavior based on the support and strata interaction. The methodology uses the performance characteristics generated in the National Institute of Occupational Safety and Health (MOSH) Mine Roof Simulator (MRS) to match the stiffness and load characteristics of various supports to the measured ground reaction behavior. It can be used to determine the appropriate -- application of alternative roof support systems or to design in- mine trials such that a fair and equitable comparison of different support systems can be made. A case study if the methodology at a western Pennsylvania mine site is presented in the paper, including a comparison of four alternative support technologies to conventional wood and concrete cribbing historically used at this particular mine.

By M. E. Poad, Donald Ross, G. G. Wadell

Because of the "energy crisis" emphasis has been placed on bringing coal mines into full production faster. To accomplish this, more is involved than a rapid excavation system. Mine design should have the freedom within the law to customize as mining conditions dictate as long as the maximum safety of the miner is insured. A year ago, safety was the most prominent "social-human factor"--now, safety and energy self-sufficiency are primary to our national policy. The Single Entry research program as designed satisfies both. It investigates the hypothesis that a single-entry system, for longwall development, supported in the center by open cribs and divided by a fire-resistant partition, can be regarded as being equivalent to or better than a multi-entry system. This paper provides an explanation for the use and advantages of a single entry system in development for longwall mining, explains the problems anticipated with single entries and presents the research approach needed to evaluate and solve the problems. Under study are ground control, ventilation, fire and explosions, emergency procedures, and industrial hazards. Described are measurements data on crib and roof bolt loads as entry heading advances and longwall abutment load is superimposed, stress field determinations and preliminary structural analysis of the double and single entry, and methane liberation and ventilation records as entry advances. Some of the mine operation problems and waivers of mining laws will be discussed. This project is a complete system study having progressed approximately two years in a five-year program.

Jan 1, 1974

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

ANALYTICAL PRESSURE - VOLUME COMPUTATIONS FOR THE MINE PROTOTYPE A new coal mine is projected, with entrance by slope 1,500 feet long. Nine main entries will be standard for development, five as intake and four as return. One return shaft is planned near the slope bottom, and an intake shaft and portal are planned 5,000 feet north of the slope bottom. The slope will have an area of 150 square feet and a perimeter of 55 feet. A belt and supply track will be within the slope. The return shaft will be circular with a diameter of 18 feet and will be 500 feet deep with an escapeway. Two hundred feet of the shaft and 500 feet of the slope will be concrete lined. Select the fan to operate five units per shift and drive the 5,000 feet to a proposed new portal, using the slope for an intake. Two main splits are planned with the maximum of three units on any split. The amount of air desired at each unit is 25,000 c.f.m; a shop at the slope bottom will require 10,000 c.f.m. In the solution of this or any similar problem, the first step is to determine the resistance factors. CALCULATION OF R FACTORS Slope area = 150 sq. ft.; Perimeter = 55 feet; Length = 1,500 feet. The friction factor K must be established. Five hundred feet of the slope is smooth lined, moderately obstructed by belt; K = 35. The remaining 1000 feet is in sedimentary rock and moderately obstructed; K = 85.

Jan 1, 1975

By D. B. Dow

This report on methods employed for dehydrating oil-field emulsions, is the second of a series prepared as a result of a study of oil-field emulsions recently completed by the writer. The first paper2 dealt with the factors responsible for the formation of emulsions. A third paper will discuss the physical chemistry involved in the formation and resolution of such emulsions. In the early development of the oil fields of Pennsylvania, no emulsion troubles of any consequence were encountered, nor to any serious extent in the oil fields of other Eastern States: However, with the development of fields west of the Mississippi in Oklahoma, Kansas, Texas and California, where heavier oils of different characteristics were found, the problem of dealing with cut oil soon became of great importance.

Jan 1, 1925

By Howard R. Hume, Terry R. West, William R. Judd

One of the outcomes of a sector slope design in a large open pit in the western United States has been the scrutiny of the structural domain concept. These domains essentially define the area of influence of particular structural characteristics. In the present instance these structural characteristics are joint discontinuities. One of the major drawbacks of defining a domain is that unless large quantities of discontinuity data are available this process of definition is largely qualitative in nature. Viewed from a discontinuity analysis aspect the orientations of all the major joint sets at a given point are a concise descriptor of the structural geologic regime at that location. This is important to domain boundary definition, this in turn is extremely important for assigning which joint sets to use as input for slope stability analysis in a given discontinuity domain. An attempt has been made to develop a quantitative method for defining these discontinuity domains based on limited amounts of orientation data thereby reducing the subjectivity normally involved in such operations. Subjectivity is not always a problem if large quantities of joint orientation data are available, since the mean and variance of joint clusters always can be compared and then grouped to define these domains. However, even this method suffers from the problem that only a single joint set orientation can be considered at a time during the grouping process. On the other hand a discontinuity domain requires that all joint sets at a point be considered simultaneously to truly define the structural discontinuity character of that point. This provides a far more complete

Jan 1, 1982

By Ian Townsend

A prerequisite for good filter performance is that the total filter installation has been well designed. In this sense, the filtration testwork will provide scale-up data, and an insight into the relationship between operating parameters that may then be optimised, and used in the development of a control strategy. A good understanding of the filter’s operating principles will ensure correct selection and sizing of ancillaries, allowing in particular for the difference between instantaneous and average flow rates.

Sep 13, 2001

By A. E. Lehmberg

"IT IS KNOWN that some ores of sulphide type, such as pyrite, chalcopyrite, and bornite have an electrical conductivity comparable to that of metals, and accordingly much higher than the conductivity of any unmineralized rock. This physical property has long been used for the detection of orebodies of this kind by means of electrical measurements made at the surface of the ground.The present paper will deal with a new electromagnetic instrument for the investigation of subsurface conductors, which has been recently introduced into field practice and has already led to successful results in Canada.The principle of the instrument will be described. How it operates, and how the observations made can be interpreted will be explained. Field examples will •be shown to illustrate its application.Description of Instrument and of Operating TechniqueThe equipment (1) includes a low-frequency alternating current generator. The a.c. is supplied to a transmitter coil and generates a primary field which induces eddy currents in the ground, the intensity of which is proportional to the ground conductivity."

Jan 1, 1952

By N. B. Pundari

Proper selection of large walking draglines, based on sound engineering principles and field experience, has not kept pace with the large capital expenditures needed to buy these stripping machines. The use of large walking draglines for stripping overburden in US surface coal mines grows steadily, but equipment selection continues to pose problems. An improper size, model, make, or spoil reach selected for a particular stripping application results in additional, unnecessary coal production costs. Large walking draglines are being used to dig deeper tar sands at the Syncrude operations near Fort McMurray in Northern Alberta, Canada. This application is compared with typical deep digging operations and dragline use prevalent at typical US strip mines.

Jan 4, 1981

By I. B. Tulu, M. M. Sears

In 2015, 40 longwall mines provided nearly 60 percent of U.S. underground coal production. During this time, about 80 percent of ground-fall-related fatalities occurred in areas where the mine roof was supported. In an attempt to better understand the status quo of current longwall support practices in the United States, during a period between 2010 and 2017, researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) visited a sample of 25 longwall mines representing nearly 50 percent of the currently active longwall mines operating in all of the major U.S. longwall producing regions. The data presented here indicate that the types and amount of roof support being installed in modern U.S. longwall mines have reduced ground-fall accident and injury rates to levels never seen before. However, the complete elimination of unintended roof falls in U.S. longwall mines has remained elusive. The data in this paper can be used by mine operators and engineers to determine where their chosen type and density of roof support occur on the spectrum of observations contained in this database. Additionally, this data can be used to enhance, supplement and support additional research on longwall gateroad support systems. 

By Eugene S. Perry

The most outstanding event in oil and gas development in Montana during 1936 was the discovery of oil in the Baker-Glendive gas field, in the extreme eastern part of the state. Other notable achievements were small extensions in the Cut Bank oil field; continued favorable results of acidization in the Kevin-Sunburst oil field; and the discovery of oil and gas in commercial quantities about 20 miles southwest of Billings, on what is known as the Mosser dome. Several wildcat wells were drilled. For the coming year of 1937, it is anticipated that the main activities will be confined to drilling in or near known fields. During 1936 Montana had seven fields producing oil, but over 95 per cent of oil production came from four fields, which in order of importance are: Cut Bank, Kevin-Sunburst, Cat Creek and Pondera. Total production for the state was 5,850,893 bbl., which is 1,251,761 bbl. more than the total for 1935. Natural gas was produced and marketed from eight fields, most important being Cut Bank, Baker-Glendive, Kevin-Sunburst and Dry Creek. These four fields accounted for over 85 per cent of total state gas production, which is slightly greater than the 1935 production of nearly 18 billion cubic feet. Increase in gas consumption is due in part to increase in smelter operation. More detailed information pertaining to the various fields is given in Table 1. In the Baker-Glendive field a test 8186 ft. deep, 15 miles southeast of Baker, was completed by the Montana-Dakota Utilities Co. in 1936. The first gas-bearing sandstone (Judith Hiver horizon, Upper Cretaceous) was found at a depth of 528 ft., and a second sand at 1167 ft. Sandstones of the Dakota formation, in which occurred water, were found from 3724 to 3853 ft. White sandstone correlated with the Tensleep (Minnelusa) formation of Pennsylvanian age was found from 5631 to 5751 ft. deep. The lower 1900 ft. of the well (below 6278 ft.) was essentially in limestone and dolomite, and information on correlation of formations in this mass of sediments is not available at this time. The upper portion of this part of the well contained much anhydrite. Cherty and dolomitic limestone below 7000 ft. may be equivalent to limestones of the Madison formation. The thickness of strata beneath the Dakota formation was

Jan 1, 1937

By Vladyslav P. Yakubovsky, Boris I. Bondarenko, Valentin A. Noskov, Vladyslav M. Sokolov

"Each of Ukrainian producers of ferronickel, stainless steel and synthetic diamonds has the same basic problem with recycling their fine Ni-containing secondary materials. The conditions for generation of them along with the correspondent properties were investigated in details. The new approaches for their recycling have been proposed. They are based on application of some pyrometallurgical processes that are used in Ukraine. The proper equipment is also available. It has been shown that the dust from laterite calcining process of ferronickel production should be efficiently recycled by sintering. The stainless steel dust should be smelted after briquetting as a charge addition to the Ni-containing discarded batteries in the elaborated furnace. The sludge after synthetic diamonds production should be pelletized and processed by liquid cast iron with application of induction magnetodynamic forces in the specific furnace.IntroductionThe object of the investigation is recycling the Ni-containing secondary fines in a form of dust and sludge. There are several generators of the fines in Ukraine. Namely they are Pobuzhye Integrated Ferronickel Mill; Electrometallurgical Works “Dneprospetsstal” with stainless steel plant as well as Poltava Diamond Plant that produces synthetic hard materials. Their businesses are the largest in the Commonwealth of Independent States (CIS). However the status of handling with the fines is not perfect since the applied recycling technologies are low efficient. The landfilling option is often adopted for them. At the same in Ukraine there are some nontraditional pyrometallurgical recycling technologies and equipment that should be tried for application in smelting these secondary materials.Recycling the sludge of synthetic diamonds productionThe sludge of “Poltava diamond plant” from production of synthetic hard materials has a following chemical composition, %: iron oxide – 29.7; chromium oxide – 18.97; nickel – 4.27; manganese oxide – 15.2; sulphate – 3.85; natrium – 14.9. The content of moisture is 70-80%. The moisture quite quickly evaporates while keeping sludge out of doors. Sludge returns into the weak agglomerates. The sizing of the dried sludge particles presents the figures from 400 to 1000 µm. The moisture was extracted by sludge pressing. The content of the basic compounds of the moisture is, g/dm3: chromium oxide – 1.6; nickel – 0.001; manganese oxide – 0.002; lead – 0.005; sulphate – 13.6; natrium – 17.0."

Jan 1, 2008

By Donald L. Katz

THE Oklahoma City Wilcox sand, discovered on March 26, 1930, has produced 394 million barrels of crude oil and 819 billion cubic feet of natural gas as of July 1, 1941. The 100,000-bbl. wells, pressures of 2600 lb. per sq. in., and flows of "Wilcox" sand caused exciting moments in the early life of the field. Today the reservoir is substantially at atmospheric pressure and produces 75,000 bbl. of crude oil daily through 466 pumping wells. Early estimates of the initial crude-oil content of the "Wilcox" sand' indicated that about 600 million barrels of crude oil would remain after the pumping wells ceased to produce economically. The Oklahoma City Wilcox Secondary Recovery Association was organized in March 1939, to study the possibilities of recovering a portion of this oil. Only a very brief summary of the information available can be presented in a paper of this nature. Some simplification and generalizations are necessary to give the over-all picture in so short a space and statements made may not apply to a specific well or small area. Since the area under consideration by the Association is that north of the south line of section 22-11-3, some information will be presented for areas A, B, C, r, 2, 3 and part of 4 of Fig. 2, and some will be for the entire Wilcox zone west of the fault. This paper is essentially an abstract of an engineering report made by A. D. Small, B. T. Murphree, M. C. Sons and the author for the Oklahoma City. Wilcox Secondary Recovery Association on Sept. 5;.1940. Some information is taken from a report to the Association by C. V. Sidwell on March 1, 1940, and some data are from a recent report by A. D. Small. It gives a brief history of the Wilcox zone, estimates of the initial oil contents of the reservoir, present conditions in the reservoir, and probable results from several programs of "secondary recovery." HISTORY OF WILCOX ZONE The Wilcox sand lies on the flank of the general structure, as shown by cross section of Fig. 12.1 .4 and areal map of Fig. 2. The sand is of Ordivician age and is composed of well assorted, rounded' sand grains with no apparent cementing material. The loose texture of the sand is shown by the enormous quantities of sand production from the wells and from the soft cores. The productive sand varies from zero thickness on the east to 220 ft. maximum and to zero thickness on the west because of water. The development of the pool4 was dependent upon drilling restrictions within the city limits, which accounts for the spacing of drilling operations listed in Table I by years. In 1931, areas I through 7 of Fig. 2 were open for drilling with the exception of some west-edge properties, and all wells drilled before Feb. I, 1935, were in this portion of the field. Nearly all wells drilled from 1933 to 1937 were in areas A, B and C. Since 1939, the newly drilled wells have gradually enlarged the producing area toward the west in the northern portion.

Jan 1, 1941

Lower noise exposure levels for operators and cleanup personnel working in portable nonmetallic mineral crushing and screening plants.

Jan 1, 1983

By T. B. Counselman

PRobably the earliest concentration of iron ore in this country was carried on in the northeastern magnetite areas. Magnetic concentration was relatively simple and gave a concentrate that, after agglomeration, and in spite of beillg high in phosphorus hecause of the dry concentrating methods then in use, was satisfactory blast-furnace feed. Production from the northeastern magnetitc area languished after the discovery and development of the Lake Superior ores, where there was seemingly an unlimited tonnage of high-grade ore, first the Michigan ores, and subsequently the still larger deposits of Minnesota. For years only the higher grade, direct shipping ores of the Lake superior district were mined. Those of Michigan, and of the Vermilion Range in Minnesota, were hard ores and came principally from underground mines. The softer ores of the Mesabi came partly from underground mincs, but mostly from the enormous deposits that could be worked by open-pit methods. The costs of ore from these open-pit deposits, even with the high initial cost of stripping, were so low that the underground mines of the Mesabi could hardly compete. The so-called Old Range ores, of Michigan and of the Vermilion Range of Minnesota, were hard and lumpy, and opened UP the burden in the blast furnace, therefore making possible harder driving with greater output. Also, some of these Ores were of such grade and physical characteristics that they were suitable for charge ore in the open hearth. These ores, therefore, commanded a price premium. and could compete with the softer, finer, but cheaper, Mesabi ores. The big tonnage reserves, however, are on the Mesabi. and it is these big open-pit deposits that contitue- our stock pile of iron ore, from which we are drawing so heavily during this war period. On the western end of the Mesabi the ore was found to be high in silica, and not suitable as furnace feed. As early as 1902, attempts were made to concentrate this so-called wash ore and by 1910 the first washing plant was put into operation. The Process was very simple, consisting essentially of a sizing and washing operation, with scalping screens, logwashers and tables, which later were replaced by classificrs. Ore particles finer than I00 mesh were deliberately wasted, because these fines were undesirable in the furnace. Fortunately, these tailings were impounded, and already are being reworked. Before long some of the low-grade ores began to require more elaborate treatment than the simple washing operation and, tables having been discarded because of their low capacity, in favor of classifiers, jigs were next introduced. These were able to discard coarser pieces of tailing than classifiers. Jigs are in active use today, various improvements having been made in their design and application. Various other machines and methods of concentration have been tried from time to time, and have in turn been discarded for more improved processes., The latest and most important process that has been 38

Jan 1, 1944

By T. B. Counselman

PRobably the earliest concentration of iron ore in this country was carried on in the northeastern magnetite areas. Magnetic concentration was relatively simple and gave a concentrate that, after agglomeration, and in spite of beillg high in phosphorus hecause of the dry concentrating methods then in use, was satisfactory blast-furnace feed. Production from the northeastern magnetitc area languished after the discovery and development of the Lake Superior ores, where there was seemingly an unlimited tonnage of high-grade ore, first the Michigan ores, and subsequently the still larger deposits of Minnesota. For years only the higher grade, direct shipping ores of the Lake superior district were mined. Those of Michigan, and of the Vermilion Range in Minnesota, were hard ores and came principally from underground mines. The softer ores of the Mesabi came partly from underground mincs, but mostly from the enormous deposits that could be worked by open-pit methods. The costs of ore from these open-pit deposits, even with the high initial cost of stripping, were so low that the underground mines of the Mesabi could hardly compete. The so-called Old Range ores, of Michigan and of the Vermilion Range of Minnesota, were hard and lumpy, and opened UP the burden in the blast furnace, therefore making possible harder driving with greater output. Also, some of these Ores were of such grade and physical characteristics that they were suitable for charge ore in the open hearth. These ores, therefore, commanded a price premium. and could compete with the softer, finer, but cheaper, Mesabi ores. The big tonnage reserves, however, are on the Mesabi. and it is these big open-pit deposits that contitue- our stock pile of iron ore, from which we are drawing so heavily during this war period. On the western end of the Mesabi the ore was found to be high in silica, and not suitable as furnace feed. As early as 1902, attempts were made to concentrate this so-called wash ore and by 1910 the first washing plant was put into operation. The Process was very simple, consisting essentially of a sizing and washing operation, with scalping screens, logwashers and tables, which later were replaced by classificrs. Ore particles finer than I00 mesh were deliberately wasted, because these fines were undesirable in the furnace. Fortunately, these tailings were impounded, and already are being reworked. Before long some of the low-grade ores began to require more elaborate treatment than the simple washing operation and, tables having been discarded because of their low capacity, in favor of classifiers, jigs were next introduced. These were able to discard coarser pieces of tailing than classifiers. Jigs are in active use today, various improvements having been made in their design and application. Various other machines and methods of concentration have been tried from time to time, and have in turn been discarded for more improved processes., The latest and most important process that has been 38

Jan 1, 1944

By T. B. Counselman

PROBABLY the earliest concentration of iron ore in this country was carried on in the northeastern magnetite areas. Magnetic concentration was relatively simple and gave a concentrate that, after agglomeration, and in spite of being high in phosphorus because of the dry concentrating methods then in use, was satisfactory blast-furnace feed. Production from the northeastern magnetite area languished after the discovery and development of the Lake Superior ores, where there was seemingly an unlimited tonnage of high-grade ore, first the Michigan ores, and subsequently the still larger deposits of Minnesota. For years only the higher grade, direct shipping ores of the Lake Superior district were mined. Those of Michigan, and of the Vermilion Range in Minnesota, were hard ores and came principally from underground mines. The softer ores of the Mesabi came partly from underground mines, but mostly from the enormous deposits that could be worked by open-pit methods. The costs of ore from these open-pit deposits, even with the high initial cost of stripping, were so low that the underground mines of the Mesabi could hardly compete. The so-called Old Range ores, of Michigan and of the Vermilion Range of Minnesota, were hard and lumpy, and opened up the burden in the blast furnace, therefore making possible harder driving with greater output. Also, some of these ores were of such grade and physical characteristics that they were suitable for charge ore in the open hearth. These ores, therefore, commanded a price premium, and could compete with the softer, finer, but cheaper, Mesabi ores. The big tonnage reserves, however, are on the Mesabi, and it is these big open-pit deposits that constitute our stock pile of iron ore, from which we are drawing so heavily during this war period. On the western end of the Mesabi the ore was found to be high in silica, and not suitable as furnace feed. As early as 1902, attempts were made to concentrate this so-called wash ore and by 1910 the first washing plant was put into operation. The process was very simple, consisting essentially of a sizing and washing operation, with scalping screens, logwashers, and tables, which later were replaced by classifiers. Ore particles finer than 100 mesh were deliberately wasted, because these fines were undesirable in the furnace. Fortunately, these tailings were impounded, and already are being reworked. Before long some of the low-grade ores began to require more elaborate treatment than the simple washing operation and, tables having been discarded because of their low capacity, in favor of classifiers, jigs were next introduced. These were able to discard coarser pieces of tailing than classifiers. Jigs are in active use today, various improvements having been made in their design and application. Various other machines and methods of concentration have been tried from time to time, and have in turn been discarded for more improved processes. The latest and most important process that has been

Jan 1, 1943

By Raj Thamburaj, Li. Ping, Prakash C. Patnaik

"An effective prognosis system for aircraft engines may involve the application of a wide range of technologies and methodologies, which may include: - On-line, real-time and in-situ non-destructive inspection/detection/sensoring - Aircraft/engine instrumentation - Airborne data recording system - Advanced signal filtration - Data compression technologies - On-line engine health monitoring technologies - On-line engine component life usage monitoring technologies - Mission severity analysis algorithm based on life prediction and damage tolerance analysis models - Life assessment methodologies - Optimized repair/overhaul/maintenance planning - Optimization of mission assignment and homogeneous life usage - Web-enabled information delivery and sharing system - Decision making logistics This paper will demonstrate some efforts that Orenda has accomplished over the last decade in collaboration with the Institute for Aerospace Research of National Research Council Canada and the Department of National Defense. The presentation will focus on the following projects:"

Jan 1, 2004

By Norbert Patzelt

The high-pressure grinding roll was introduced about 10 years ago and has established itself in many applications. Most of these machines are used in grinding circuits in the cement industry. A few operate in conventional mineral-processing plants. Polysius has sold more than 350 Polycoms worldwide. An exception is diamond-ore processing in South Africa and Australia. This type of grinding system increases diamond liberation and reduces the capital costs for the downstream processing plant. There are several reasons why high-pressure grinding rolls have not been used more extensively in the mining industry: - The mining industry adheres to conventional grinding technology and regional preference for certain comminution circuits. - Design, scale-up and flowsheet assessment procedures are viewed as being immature and reduce confidence in the potential application of the technology. - Downstream process benefits are unproven on a plant scale.

Jan 1, 1995