Search Documents

By Maurice Rey, H. Brevers

Through circumstances connected with the war, the senior author lost his records, therefore it has been impossible to include numerical data in this paper. The arsenical quicksilver ore investigated had been roasted, with poor metallurgical results. The vapor-tension temperature curves of mercury and arsenious trioxide are similar, and the arsenical compound hampers the coalescence of mercury drops in the condenser and is the cause of large stack losses. The ore was a gray limestone carrying small amounts of carbon and mineralized with cinnabar and two arsenic minerals, realgar (As2S2) and arsenopyrite (FeAsS). The proportion of realgar often exceeded that of cinnabar; the proportion of arsenopyrite was smaller. The grade of the ore varied between 0.8 and 4 per cent Hg. The problem was to make a high-grade mercury concentrate, as free from arsenic as possible. The water used throughout the testing was hard, having a pH of about 8. Flotation of Realgar Realgar showed a very strong tendency to float. It formed a film at the surface of the pulp and floated in abundance with only pine oil. Therefore an attempt was made to float the realgar before the cinnabar, but this was not very successful; the percentage of mercury in the realgar concentrate could never be brought below 2 or 3 per cent. Cinnabar slimed easily and floated with pine oil, so that some of it always accompanied the realgar. There was also the question of the cinnabar-arseno-pyrite separation. On further investigation it was found that realgar can be floated not only with pine oil but even better with a combination of hydrocarbons and pine oil. Washing the ore with ether revealed that it contained hydrocarbons, which helped to float the realgar. In this connection it belongs to the same class as carbon, sulphur and talc. It can be floated also with a xanthate, when activated by a heavy-metal salt. The conditions favoring the two types of flotation are opposed, as activation by a copper salt facilitates xanthate flotation (in fact, is even necessary to it), whereas it hinders pine oil and petroleum flotation. One type of flotation can be termed non-polar and the other polar, a distinction that has been stressed in a previous paper.' Depression of Realgar and Flotation of Cinnabar Many chemicals were tested in an attempt to float the cinnabar and depress the realgar. Finally starch rendered soluble with caustic soda was tried, also several grades of commercial soluble starch, and dextrin was found to be the best and the most convenient reagent. Several of these starch preparations have a strong flocculating effect on the pulp, which is a distinct disadvantage. Dextrin, with its low flocculating power, is excellent. It is noteworthy that starch preparations are also depressants for carbon and talc, so that the fact apparently has a general

Jan 1, 1943

By F. E. Cash

Much has been written concerning accidents in coal mines; the fact that accidents cost the employer and employee money is generally well known, but how much accidents actually cost is vague, even in the minds of many operators. Unquestionably there are hazards in coal mining, but many of them can be eliminated; and from the prevention of accidents there can be realized a material saving in dollars and cents as well as in human suffering. In presenting the frequency, severity, and cost of accidents in some Tennessee coal mines, it is hoped that other mines in Tennessee, as well as mines in other States, will by a comparison of the data with their own ex¬ perience be enabled eventually to reduce the number of' their accidents.

Dec 1, 1932

By M. Leroux, P. Lacombe, S. R. Rao, J. Y. Kim, J. A. Finch, G. Labonté, N. Macminn, M. Ounpuu

"Laboratory investigations on two complex ores, the A1 zone ore from Les Mines Selbaie and the Lyon Lake ore from Mattabi Mines Ltd. (Division of Noranda Minerals), have been carried out to determine some of the main variables in collectorless flotation. In particular, the effect of pulp potential (controlled by gas composition), conditioning time, pH and grinding media have been studied.Chalcopyrite showed the greatest response to collectorless flotation among the four major sulphide minerals present, followed by galena. Flotation of sphalerite was variable from minimal to important depending on the mineralogy and the pre-treatment performed. Appreciable silver recovery was achieved collectorlessly for the Lyon Lake ore while it could not be achieved for the A1 zone ore of Les Mines Selbaie. It appears that the difference between the two ores is related to silver's predominance as tetrahydrite in the Lyon Lake ore while it is as argentite and native silver in the A1 zone ore.The response of the ores to collectorless flotation is strongly dependent on the pulp potential, Ep, and pH. Using different gas compositions and different conditioning times it was found that collectorless flotation occurs when Ep is +195 to +295 mv (vs SHE). The actual on-set potential for collectorless flotation is dependent on the ore. A too high potential or prolonged oxidation leads to a decrease in selectivity. Some other factors were examined, notably the effect of pH and the type of grinding media on the selectivity achieved in the laboratory.Preliminary results from a plant trial at Mattabi Mines Ltd. confirmed that collectorless flotation occurs and that it is preferential for chalcopyrite and to a lesser extent galena. Collectorless flotation was not attempted at Les Mines Selbaie. However, examination of the distribution of collector between the different addition points in the copper circuit suggests that it may be present."

Jan 1, 1990

By Robert D. Hansen, Richard R. Klimpel

INTRODUCTION A very important factor in froth flotation is the use of surface-active chemicals to form a froth in which minerals or coals are retained, thus allowing for valuable component enrichment. In coal flotation reagents (frothers) specifically designed to provide an efficient froth are employed. It is this group of chemicals that will be the primary emphasis of this paper. Despite the importance of frothers, surprisingly little systematic scientific work has been performed with the goal of quantifying frother mechanisms and the influence of particles on froth stability. Based on direct experimental observations in both batch laboratory and continuous large-scale flotation cells, the use of a frother significantly increases first, the possibility of a particle- bubble contact, and second, the efficiency of sticking after such a contact. Thus, a major role of a frother is to significantly increase the rate of flotation. This rate modification by a surface-active agent occurs through several observable mechanisms including the formation of a froth of relatively consistent character (bubble size and bubble density) under a variety of operational conditions, an increase in the ability to disperse air in the flotation cell, a reduction in the rate of coalescence of individual bubbles in the cell, and a decrease in the rate of bubble rise to the pulp surface. It will not be the intention of this paper to exhaustively list all frother accomplishments related to research, development and use in coal flotation. Rather, the authors will attempt, based on their experience, to present a technology overview of the role of frothers in the chemistry of flotation as successfully practiced at the industrial level. A very useful framework for flotation is the concept suggested by Klimpel (1984, 1984a) of viewing flotation as a system consisting of three major components: chemistry, equipment and operating variables. This is illustrated in Figure 1. A major point of this figure is that flotation is a highly interactive system with many technical and economic combinations of component settings available to operators to achieve a given goal. Sometimes simultaneously changing various component settings will reinforce a particular attribute. Also various component settings can cancel or counteract each other if changes are not chosen wisely. Thus, coal flotation must be viewed by the plant operator as a complex system with the economic/technical optimization of a given flotation process being directly related to the operator's knowledge of how his particular flotation system behaves as a function of the major control variables he has at his disposal. Typical important component settings in coal flotation are collector dosage, frother type and dosage, air flow rate, feed rate, particle size, pulp density, and the surface oxidation conditions of the coal. Because of the above complexities, it is sometimes assumed (especially in laboratory studies) that the choice of frother type and dosage is not as crucial as some of the other factors such as collector type and dosage (e.g., Leja, 1982). Detailed plant level testing of all of the factors of Figure 1 performed in recent years, Klimpel (1980, 1980a, 1982, 1984, 1984a), Hansen (19861, Klimpel, Hansen and Meyer (1982), simply do not support this assumption. The above testing has shown rather clearly that certain frother chemical structures consistently exhibit predictable performance characteristics in both mineral and coal flotation. In addition, significant changes in both rate and recovery can be expected. In the remaining sections of this paper, the following topics will be covered: requirements of chemicals capable of use as frothers, types of chemicals used commercially as frothers, some general performance characteristics of existing commercial frothers, and recent work in developing new frother chemical structures.

Jan 1, 1986

By M. L. Torem, R. H. Rojas, A. G. Merma

"Fine particle recovery by conventional flotation processes is very low mainly due to the low probability of bubble/particle collision and adhesion. In order to solve the problem of low particle recovery, several flotation technologies have been developed to increase bubble/particle collision efficiency. Among these technologies, the electroflotation process stands out. This process has advantages in the generation of microbubbles (<100 µm) and in the production of different amounts of hydrogen and oxygen microbubbles. These advantages favorably influence the fine particle floatability, due to the greater probability of particle/bubble collision and adhesion. The electroflotation tests were conducted for a hematite/sodium oleate system in a Partridge-Smith modified electroflotation binary cell of 0.38 L usable volume. The sodium oleate concentration, particle size, pH and current density were evaluated. Satisfactory results in the recovery of hematite were found at pH values of 7, reaching hematite floatability of 99% and 90% with hydrogen and oxygen bubbles, respectively.INTRODUCTIONThe flotation recovery of fine and ultrafine particles is normally very low and is caused by several factors, among them, the low probability of collision and adhesion bubble-particle, the difficulty to overcome the energy barrier (entrainment and entrapment), low selectivity, surface oxidation and mineralogical changes (Schulze et al., 1989; Waters et al., 2008; Shahbazi et al., 2010). This problem can be overcome by decreasing the bubble size or by increasing the apparent particle size. However, it is worth noting that the use of small bubbles or micro bubbles also involves some disadvantages such as their low momentum resulting in a slower process comparing with conventional flotation. Electroflotation is an attractive alternative for treating fine particles with small bubbles less than 100 µm, generated by the electrolysis of water. Electroflotation is one of the variants of the flotation process, where the gaseous phase is produced by electrolysis of an aqueous solution, generating oxygen and hydrogen bubbles (Sarkar, 2010; Gupta and Ali, 2012). These smaller size bubbles allow the recovery of fine particles by increasing the collision efficiency. This process is versatile and competitive in relation to other techniques such as dissolved air flotation and dispersed air flotation because the electroflotation units are smaller, more compact and require less maintenance and less operating cost than other flotation units (Zouboulis and Matis, 1995,). In addition, the electroflotation process is a clean technique and provides results in a short time, requiring only the investment in the electroflotation cell construction stage and the choice of the electrodes (Ketkar et al., 1991; Sarkar et al., 2010; Sun et al., 2011). In this sense, this study assesses the effect of pH, particle size and sodium oleate concentration on electroflotation of hematite fines."

Jan 1, 2018

By Dale S. Preece

A Discrete element computer program named DMC @istinct Motion Code) has been developed for modeling rock blasting. This program employs explicit time integration and uses spherical or cylindrical elements which are represented as circles in 2-D. DMC calculations have been compared with measurements on bench blasts in the field with relatively good comparison. Structural rock mass characteristics have a significant impact on any blast and DMC has not, until now, included these effects. This paper discusses a recently added DMC capability for treating joints and bedding planes in bench blast simulations.

Jan 1, 1995

By H. Clare Horwood

"Fractures and fracture zones containing veins and stringers of auriferous quartz in a quartz porphyry dyke are the principal structural features at the Howey and Hasaga gold mines. The 'break' containing the dyke was produced by a force from the northwest, the fractures in the dyke by compressive stress from the west.Both mines are in the north-central part of Heyson township, in the Red Lake area. They lie close to the southeastern side of the Dome granite stock. The Howey mine exhausted its ore reserves and ceased operations in November 1941. The Hasaga mine is producing at the present time (June, 1946).Mineralization was first discovered in the dyke in 1925 by the Howey brothers. Lorne Howey's discovery, which became the Howey mine, came into production in April, 1930; Ray Howey's find, which is now the Hasaga mine, started production in November, 1938.The total production from the Howey mine was 421,324 oz. gold and 144,253 oz. silver from 5,158,376 tons of ore hoisted ( 4,319,331 tons milled) during its 11 years of operation.The total production from the Hasaga mine from November, 1938, to December 31, 1945, was 124,434 oz. gold and 51,009 oz. silver from a total of 901,098 tons hoisted (721,361 tons milled).GENERAL GEOLOGYThe porphyry dyke containing the orebodies at the Howey and Hasaga mines lies a short distance southeast of the contact of a granite-granodiorite mass known as the Dome stock. The dyke fills a fracture trending N.65°E. in a tongue of Keewatin volcanic breccia that extends in a rather irregular manner into an elongate intrusive stock of dioritic rock known as the Howey diorite. The accompanying table presents the geological succession."

Jan 1, 1954

Within CRLÆs lifetime there have been a number of products that have proceeded through their life cycles. In each case market forces and technological advances have forced the cessation of the product. The company has then had to develop alternative outlets for its copper. Sometimes it has produced a similar product to fill the same market. In other cases the extra copper is sold as cathode. Today, CRL produces no semi-fabricated copper products and all cathode is sold. More recently, CRL has ventured into the sale of technology and manufacture of cathode motherplates. This area, whilst it is not what had been a traditional area of core business, has been found to be profitable.

Jan 1, 1998

By Jasper L. Stuckey

PYROPHYLLITE, first identified as soapstone,1 later as agalmatolite,2 and finally as pyrophyllite,3 has been known to occur in North Carolina for more than 130 years and has been produced intermittently in commercial amounts for the past 100 years. Pyrophyllite mining, however, has become a major industry in North Carolina only during the past 25 years. North Carolina and California are the chief producing states. Current annual production averages 125,000 tons, of which slightly more than 90 pct comes from North Carolina. Distribution and Geologic Setting: All known pyrophyllite deposits in North Carolina are associated with rocks of the Carolina Slate Belt,4 which is composed of a vast series of metamorphosed volcanic and sedimentary materials, occurring as two zones extending in a northeast-southwest direction across the state. The larger of these zones, lying in the central Piedmont region, varies from 8 to 50 miles wide. The smaller zone lies along the eastern edge of the Piedmont region and is partly covered by coastal plain sediments.

Jan 1, 1958

By Shiou-Chuan Sun

Notwithstanding the fact that unsaturated fatty acids are used in preference to saturated acids for most flotation purposes, information regarding their collecting properties is sketchy. Keck, Eggleston, and Lowry1 reported in 1939 that the collecting power of fatty acids on hematite decreased in the order of oleic, lauric, myristic, palmitic, and caprylic acid. Keck and Jasberg2 described in the same year that "unsaturated oleic acid with 18 carbon atoms was a better collector than saturated stearic acid" for floating magnetite. Gaudin and Cole3 stated in 1953 that the double bonds of oleic and linoleic acid were not oxidized during the flotation of fluorite, whereas the double bonds of linolenic acid were measurably altered even after one single flotation step. In August, 1953, Hukki and Vartiainen4 concluded that the collecting power of palmitic, oleic, linoleic, and linolenic acids on ilmenite, magnetite, pyrite, and rutile increased with an increasing number of double bonds in the acid molecules. This was subsequently proved to be generally true for the flotation of mapganese5, phosphate6, and magnetite7. The above cited literature indicates that, prior to the present paper, only about ten minerals were tested with pure unsaturated fatty acids as collectors.

Jan 1, 1959

By A. Duerksen

"Surface coal mining in West Virginia has supplied energy to the eastern coast of the United States for over a century. Over the years, the coal mining industry has been forced to adapt as societal demands regarding health, safety, and environmental impacts have changed. More recent pressure has called for another iteration of change: long-term post-mining sustainability. The research discussed in this paper investigates one potential solution - or component of a solution - to improve the sustainability of surface coal mining in West Virginia: post-mining wind power. The paper begins with an introduction to the Appalachian region of the U.S. and the role that mining has played in its history, followed by a discussion of the need for sustainable mining and how post-mining wind power may help fulfill it. Data processing methodology of field data from monitoring locations is then explained. The results are then used to estimate the electrical output of a wind turbine. This data is then utilized in a case study discussion of one of the monitored sites. The paper concludes with an analysis of the broader implications of the research and a discussion of future work."

Jan 1, 2011

By J. du Plooy

Mintek has implemented a training scheme that provides students with the experiential training requirement for the National Diplomas in Chemical Engineering and Extraction Metallurgy. This note describes the main features of the scheme and the course content, and our view of future developments in this area.

Jan 1, 1998

By Lamont G

The significance of blasthole stemming in determining blasting efficiency has been extensively studied for small diameter holes using gelignite explosives. Recent developments in blasting technology with the use of large diameter holes and low cost blasting agents have not included studies of the effectiveness of different types of stemming materials. A review of previous measurement techniques and the relevance of these earlier results to present stemming practice is presented in this paper. A survey of operating mines in Australia provided information for this analysis. The value of stemming in reducing blast noise and improving blasting efficiency is generally accepted but the use of bulk-loaded explosives in underground operations has resulted in the practice of eliminating the use of stemming material.In surface operations drill cuttings are used for stemming on the basis of availability rather than efficiency in providing resistance to movement. The development of laboratory testing techniques, based on noise level and borehole pressure measurements, to evaluate the relative efficiency of different types of stemming materials is described. The results of an extensive series of tests with ANFO explosive showed similar trends tothose obtained from earlier published results with gelignite type explosives. Conclusive quantitative results on the relative effectiveness of different stemming materials will require minor modifications to the existingequipment. Observations and the results of pressure measurements indicated the presence of shock wave effects which caused the ejection of the top section of the stemming column when using coarsely fragmented material.

Jan 1, 1979

Some important mineral fields are referred to in discussing the formation of placer deposits in Australia.Testing methods include boring by hand, with percussion rigs, with auger and pit digging drills, and by vibro drilling.Sampling errors are minimized by the use of correct techniques and equipment for boring, sampling and sample dressing. A hypothetical set of data is used to demonstrate the final process of evaluation, and somerelevant taxation provisions are discussed.

Jan 1, 1966

By R. L. Loofbourow

The Sunro Copper Mine is near the south coast of Vancouver Island about 35 miles west of Victoria. Failure of the roof of a large open stope let a good sized mountain stream into the mine. Broken are, boulders and sand were washed into the underground mill and out through a 7 800-foot adit. The adit became plugged; water burst out an a ridge above the adit, washing out the portal and o trestle by which it was reached, Rock and ore are strong but several systems of steep, pronounced but generally tight fractures are found on and parallel to the walls of the orebody. The stope was started from a slusher drift 390 feet below the bed of the River and brought up to an elevation 155 feet below the River by blasting vertical and horizontal rings of longholes in the nearly vertical orebody. Mining was stopped there and five months were given to grouting and bolting the pillar under the bed of the River, During this time and for several months thereafter sloughing increased the width, length and height of the stope. At the last known observation the stope was 77 to 96 feet wide, 185 feet long and the highest point of the domed back was only 55 feet below the River. The flooding took no lives. In other respects, however, it might be difficult to find in mining lore o more savage example of the application of "Murphy&apos;s Laws".

Jan 1, 1968

By David Kramer, Cecil G. Rhodes

Critical transport currents were measured as a function of perpendicular external magnetic field in Ti-22 at. pct Nb wire samples. These samples were heat-treated to yield w Phase precipitates at denslties ranging from 10 to 10 17cm-3. The Precipitates are ellipsoids of revolution with major axes of 50 to 1300A. Flux-Pinning by w precipitates is responsible for the high critical transport currents that were ob- ThE ability of a type II superconductor to sustain a zero-resistance transport current (Jc) in an external magnetic field (H) is due to the presence of micro-structural features which can impede the motion of magnetic flux penetrating the superconductor under the influence of a Lorentz force. Such features are referred to as pinning sites. The pinning strength is tained. A sample cooled from 800°C and annealed 1 hr at 450°C carried a critical tramport current of 10 amp per sq cm at 30 kG. Variations in the current-carrying ability of this alloy are due to changes in its pinning strength which is a function of precipitate density and composition and of the composition of the matrix. the reaction of the bulk superconductor to the Lorentz force and depends on the efficiency of the individual pinning sites and on their volume density. The super -current density increases with pinning strength, other things being equal. The above concepts are discussed in detail in a comprehensive review by Livingston and Schadler.&apos; In Ti-Nb alloys, as in other binary titanium alloys, the metastable hexagonal w phase usually forms below the p/a + p phase boundary near the titanium side of the phase diagram. Stiegler et a1.&apos; have summarized much of what is known about w phase in titanium and zirconium binary alloys. The present work deals with

Jan 1, 1968

Minimize drilling time in roof bolting. Approach The Bureau of Mines conducted a survey of 34 roof bolting machines used in underground coal mines. Results of the survey indicated that drilling time, bit cost, and respirable dust concentrations and be reduced by using the appropriate bits for drilling, To evaluate bits currently used and to find optimum cutting parameters needed to minimize drilling time, the Bureau tested two bits commonly used in most underground mines on both wet and dry systems. These are the dusthog* and shank type. The dusthog has dust ports in the bit body to remove cuttings. With shank bits, holes in the drill steel do this. Cost of each type is roughly equal. Bolters with dry vacuum systems were tested in the laboratory first. The lab tests were verified by underground tests in several mines. Bolters with low-pressure wet drilling systems were also tested under-ground. Tests concentrated on the effect of rpm, water and airflow rates, heating, wear, bit design and bit type. Lab Results -Dry Drilling Holes were drilled during the laboratory tests using a production model bolter drilling 45-inch-deep holes into mixtures of lime stone and sandstone aggregate. All tests started with new shank and dusthog type bits at 225 and 450 rpm. Thrust was about 6,000 lbs in all tests. Each bit was tested at two airflows, 15 and 25 cfm, airflows which are typical on operating roof bolter bits. Eleven styles of bits were evaluated. On the average, dusthog bits drilled 25% faster than shank types and were always cooler after drilling. The effect of RPM was tested with 5 different bit types. When bit rpm was increased from 300 to 400, drilling rates doubled. With used, well-worn bits drilling time and final bit temperature were more than doubled.

Jan 1, 1986

By V. K. Grotzky, F. J. Fraikor

A number of investigators have noted the importance of various precipitation reactions on the properties of commercial-purity beryllium.1-5 Carrabine, for example, has demonstrated the interaction of iron and aluminum on the mechanical properties of hot-pressed polycrystalline beryllium.6 He considered the determining factor on elevated-temperature properties to be a reversible AlFeBe, precipitation reaction which could be directly related to the Fe/Al impurity ratio of the beryllium. Any aluminum in excess of the stoichio-metric amount required to form A1FeBe4 was presumed to remain primarily in the grain boundaries. We have observed, by transmission electron microscopy, such a grain boundary effect after various heat treatments of beryllium sheet. The starting material in this investigation was bare-rolled beryllium ingot sheet (0.001 to 0.005 in. thick), in contrast to the hot-pressed powder utilized by Carra-bine. It should be noted from the ingot sheet analysis shown in Table I that the Fe/Al weight ratio was near unity which would provide some free aluminum although the total aluminum and iron content was still small. Fig. l(a) shows some aluminum or aluminum-rich precipitates in the grain boundaries of a beryllium foil which had been quenched from 1200°C into brine at -TPC. Similar grain boundary precipitates were found, particularly at grain boundary intersections, in other samples quenched from 1100° and 1000°C. The length of annealing time at these elevated temperatures did not appear to substantially alter the amount of grain boundary precipitates, thus attesting to their relative insolubility. No matrix precipitates were observed other than the normal BeO and Be2C inclusions. A microprobe analysis of the larger precipitates at

Jan 1, 1968

By F. S. Sinnatt

THIS paper is the outcome of an extended investigation carried out in association with Dr. L. Slater. The inquiry had been continued in various directions and a number of results are quoted from an investigation recently completed by S. H. Jenkins. In projecting the work some five years ago, the author had in view a general attack on the problem of the spontaneous combustion of coal from an angle that had received little attention. The basic idea was to obtain a "slow motion study" of the active combustion of coal. This included an examination of the conditions prevailing in a mass of coal at the moment when active combustion ceases. It was thought that, if the factors governing the extinction of combustion in coal could be definitely established, it might offer an explanation of the manner in which the spontaneous combustion of coal originates. The inquiry arose from a detailed study of the properties of fusain that the author began in 1918. Fusain seemed to possess characteristics quite distinct from the coal with which it was associated, for if it were collected into a heap and one portion were heated by a small flame the combustion would traverse the whole mass. This combustion was not accompanied by smoke and passed slowly through the heap of material. Later, it was found that coals, including anthracites, would behave in a similar manner provided they were in the form of powder and that the particles were smaller than a certain size. The limiting size of particles is a definite characteristic of the coals investigated. In view of the fact that fusain exists with coal in a state that enables it to undergo this particular form of combustion, it must be assumed, sometimes, to playa definite part in the spontaneous combustion of coal in the goaf (waste).

Jan 3, 1925

In sizing of wet coal by the horizontal vibrating screen, screen openings to be used is much restricted, because coal is sticky and its bulk density is little. The electrically heated screen and other various types of screen had been tried to screen raw coal and coal as raw materials at a few mm. However, they failed to realize satisfactory results. On the other hand, fine sizing of coal is requested by many fields. For example, raw coal is desired to be screened at the fine rate, before being fed to the coal preparation control system in order to transport undersizes as unprepared coal particles and to reduce load in coal preparation waste water treatment system.1) Coals fed to the fluidized bed boiler also should be sized at a few mm. Regardless of many requests on fine sizing of coal, it seems that there are many cases to omit the basic screening process, because the screening is very difficult on a industrial scale. Size control as pretreatment of coal as raw materials is presented as one of the basic screening processes. In 1979, Kinki Industrial Co., Ltd. and Nippon Steel Corporation jointly succeeded in developing the vertical centrifugal screen. Closed -circuit crushing system by the use of this screen has operated actually at N.S.C, Hirbhata .Works, and realized the anticipated result. Consequently, this system has established the position as the most basic technology in the coal preparation. 2), 3), 4) This system has been also introduced to Nakayama Steel Works, Ltd. in 1982. This system termed the CPC (Coal Preparation Control) Process has been operated smoothly in both N.S.C. and Nakayama. Reported herein is the practical application of the vertical centrifugal screen termed V3-Separator. (V3 means vertical, versatile and vibration.)

Jan 1, 1984