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By Uldis Jansons

This report evaluates the economic Mining feasibility of four selected mineral deposit types that can be anticipated to be found in (d)(2) lands in the western Brooks Range, Alaska. The major assumption made for this study is the availability of a rail system for transporting equipment and concentrates for the base metal mines. Commodity prices used are those in existence in July 1976. Mine models were established based on known deposits and then evaluated. A lead-zinc-silver-barite deposit for which grades were available but ore reserves were assumed would require approximately 25% higher ore grades or higher metal prices to yield a 15% discounted cash-flow rate of return an the investment if mined at a rate of 10,000 tons per day open pit methods. Large copper-zinc mineral deposits could be mined economically at rates either of 5,000 tons per day underground or 10,000 tons per day by open pit methods. A high-grade copper deposit require a copper price of over one dollar ryes pound to yield an economic profit to be mined at 2,000 tons per day by underground methods. A small high-grade gold underground mine would require a gold price of about $295 per ounce to yield a 20% discounted cash-flow rate of return on investment if all new mine equipment were used and if existing labor rates were paid: Enterprising mining groups operating as partnerships might be able to operate this mine profitably at a gold price of about $152 per ounce, perhaps slightly less.

Jan 1, 2012

By Frank Clemes Smith

The study of the so-called refractory gold-ores of the Potsdam sandstone, ores which are probably of wider occurrence and of much greater economic importance in the Black Hills than is generally supposed, has led the writer to formulate in the present paper some of the results obtained in the course of a special examination of these particular ores, conducted at the State School of Mines at Rapid City, So. Dak. Various circumstances have interrupted the work, and it will easily be seen that relatively little has yet been accomplished; but it is hoped that this little may be of sufficient interest to justify a later supplement. Tellurium, discovered by Muller von Reichenstein in 1781, is generally classed as a very rare metal; it is further mentioned by one of our late writers as " of comparatively little importance," and as obtained from its ores by a " complicated process.'' Concerning its rarity, we have some trustworthy evidence below. Its commercial importance, particularly in connection with electrical appliances, has been passed upon by Mr. Edison ; * and it is certain that, in some metallurgical processes for the treatment of gold- and silver-ores, it may be saved as a byproduct at a relatively reasonable expense. The importance of tellurium as a mineralizing agent is emphasized by the remarks of one of our leading metallurgists,jwho, in his own practice and by a wide series of experiments, has found its occurrence to be much more general than has been supposed. Recently the same writer has discussed the occurrence of tellurides and oxidized tellurium compounds in the gold-ores of Cripple Creek, Colo., and in those of the Black

Jan 1, 1897

By Albert H. Fay

The first data compiled by the Bureau of Mines relating to coal- mine accidents in the United States were published in Bulletin 69," in which the total fatalities by years and States were tabulated from 1896 to 1912. Since the publication of Bulletin 69, further research has been conducted, with the result that the bureau is now able to publish for the first time all of the fatal accidents described in the State inspectors' reports by States, causes, and calendar years, from the beginning of inspection service to date. For the anthracite mines of Pennsylvania, there is a continuous record since 1870; the records of the Pennsylvania bituminous mines are continuous from 1877, and, with the exception of one year, the Ohio records are complete from 1874 to date. In fact, the records of all of the States, with few exceptions, are complete; and incomplete data for any year may generally be attributed to the fact that no report was published during that year. The magnitude of the coal-mining industry in the United States is such that too much stress can not be placed on the need of safeguard- ing the three-quarters of a million men employed. Although the figures given herein show an appalling record for past years, they are not published for the purpose of proclaiming the high fatality rate of the past. They are a record of experience covering a period of 45 years, showing causes and results of many accidents in the coal mines of the United States. They represent a diagnosis of the hazard of the mining industry, pointing out the principal physical causes of accidents, and make available a body of uniform facts that will serve as a basis of preventive measures for use in future operations. It is with these great purposes in view that the Bureau of Mines presents the classified data in this report. Classification and study of mine accidents on the basis of number of persons killed is common and very old, but fails to throw enough light upon the problem involved. Many serious accidents in mines have no fatal results, hence in a tabulation of fatalities they are overlooked and the real hazard of the industry is not made clear. An accident does not necessarily include an injury that may result therefrom. Such accidents as the breaking of a hoisting cable, an explosion of powder, gas, or dust, a runaway car or motor are all serious. Although no loss of life results, they should be recorded, investigated, and studied to prevent their repetition. No accurate data for the United States are available showing how far the personal element as related to the miner and his co-worker, the mine foreman, or to the superintendent and others in authority, contributes to accidents. Many accidents are due to inexperience on the part of the miner, his failure to heed orders, a misunderstanding of instructions and last, but not least, carelessness of himself or his fellow worker. A foreman or superintendent may fail to give proper warning regarding the conditions of certain parts of the mine; he may not have inspected certain rooms or entries on the day of a mine accident; the mine may not be properly equipped, or the operator may neglect to comply with the inspector's recommendations. There is, therefore, a personal element on the part of both the operator and the miner that must be considered. Legislation and the enactment of compensation laws will make the operator realize the seriousness of the mine-accident situation, when fatalities and injuries are to be paid for in legal tender of the realm. The miner must be educated and made to realize the dangers he encounters; he must learn that self-preservation and the safety of his fellow workmen should receive his first attention; he should cooperate with his employer, his asso- ciates, and the State mine inspector to the end that the mine hazard may be reduced to a minimum. "Cooperation for safety" should be the watchwords of the operator, miner, State inspectors, and all others in any way interested in the mining industry.

Jan 1, 1916

By Steve P. Signer

Researchers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health installed 39 instrumented, fully grouted bolts at six test sites in a trona mine retreat panel to study mine roof stability for the improvement of workplace safety. Variables at each test site included bolt spacing, bolt length, roof span, and location in the panel layout. At most test sites, two rows of instrumented bolts were installed, one in or near the intersection created during development and the other in or near the intersection created during second-pass mining. The most significant factor affecting bolt load was roof span. The highest loads were on the bolts installed in the intersections of the 6 m-wide entry. Mining-induced stress resulting from panel layout was the next most significant factor affecting bolt loading. Minor varia¬tions in bolt loading could be attributed to changes in bolt spacing and bolt length. Gas pressure release in the immediate roof contributed to some bolts showing compressional loading during gas bleed-off.

Jan 1, 2001

By Yunnen Chen

This work concerns the removal of zinc(II) and COD by means of sawdust obtained as a by-product from locally used wood. The zinc(II) and COD removal study has been carried out batchwise where the influence of physico-chemical key parameters such as tree species, pH value of solution, temperature and contacting time and dosage of adsorbent have been considered. The maximum percent removal was attained at pH 9 all for Zn(II) and COD after about 60 min. The adsorbent can be effectively desorption using 0.1 M HCl. The experimental results showed that ion exchange maybe the major adsorption mechanisms for binding the divalent metal ions to the sawdust. Sawdust was a potential adsorbent for the removal of Zn(II) from the effluent of electroplating industry.

Jan 1, 2009

By Robert Leach

THIS paper gives a brief summary of the process of manufacture of sterling silver, and some of its more important physical properties, as observed in commercial production of rolled sheet and wire. Although papers have been published by Turner and Smith,1 Rose,2 Sperry3 and Jordan,4 there are few technical data available, and unfortunately the time allowed for the preparation of this paper has not been sufficient to make it as comprehensive as the title might indicate. ANALYSIS OF STERLING SILVER Fine or pure silver is too soft for coinage and the manufacture of articles in which strength and resistance to wear are desired. From the earliest times of which we have record, copper has been the metal generally used to harden silver. Analyses of coins and silver articles from ancient tombs show varying amounts of copper, and old Roman silver objects in the British Museum have approximately the same analysis as our sterling. The first authentic record of the establishment of a standard alloy is during the reign of Henry II in England. During the twelfth and thirteenth centuries, the people in the Eastern Provinces of Germany had a reputation for the standard and purity of their silver coinage, and it is said that Henry II employed some of these Easterlings, as they were called, to improve and standardize the English coinage, which had become debased. The peculiar standard adopted is probably accounted for by the system of weights used. A troy pound contains

Jan 1, 1928

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during .the period Jan. 10 to Feb. 10, 1915: N. H. Emmons, 2d, Dover, Mass. R. 0. Hocking, Redruth, England. Paul W. Gaebelein, Cornucopia, Ore. G. H. Carnahan, New York, N. Y. H. D. Kinney, Easton, Pa. W. A. Wilson, Salt Lake City, Utah. W. D. McDougall, New York, N. Y. H. V. Winchell, Minneapolis, Minn. Kirby Thomas, New York, N. Y. Mrs. H. V. Winchell, Minneapolis, Minn. V. T. Lawshe, Newark, N. J. Keijiro Nishio, Tokyo, Japan. Henry S. Stebbins, who has been connected with the firm of Oglebay, Norton & Co., Cleveland, since 1892, has resigned to accept a position with M. A. Hanna & Co. of the same city. E. L. Newhouse has been chosen First Vice-President of the American Smelting & Refining Co. in place of the late Barton Sewell.

Jan 3, 1915

By E. Don Dilling, W. F. Holbrook, Lloyd R. Michels, James W. Pennington, Dwight L. Harris, Wm. F. Hergert, Cyrus L. Blogett, H. A. Doerner, Ernest A. Reige

"IntroductionA process for production of magnesium by carbothermal reduction was developed at Padentheirm, Austria, by the Austro Americanische Magnesit Corporation& an independent investigation of this and other processes was started in 1937 by the Bureau of Mines at Pullman, Wash., with the cooperation of Washington State College. 10/ A preliminary study of the Radentheirm pro¬cess, as revealed by the meager information then available, demonstrated the following two major disadvantages,The use of hydrogen for shock cooling requires an enormous volume of gas - about 1,000 cubic feet for condensing each pound of metal as a pyrophoric dust which must be completely separated from this gas. Then if the gas is to be recycled for repeated use, the CO produced by the reduction reaction must be separated from the hydrogen. These separations are costly from the standpoint of equipment and operation. 11/The condensate is an impure, pyrophoric metal powder that must be purified and converted to coherent form. This is accomplished by distillation or sublimation of the metal. Distillation on a large scale involves difficulties inherent in the high boiling point (1,107° C.) and the chemical activity of the metal. To avoid these difficulties, the metal is sublimed at 600° C. and of very low pressure. This is quite easily carried out as a batch operation but is a costly procedure. A continuous sublimation process has not been accompli shed."

May 1, 1945

Preventive maintenance practices are listed in the manufacturers' instruction books. In general, equipment that requires frequent and extensive preventive maintenance is generally the most costly. The manpower spent on these frequent trips to remote areas is such that it is usually better to invest in a more costly system which requires little preventive maintenance. The best preventive maintenance for the system is a good installation. 7.2 Preventive Maintenance and Inspections With any system, periodic inspection is required because of the corrosive atmosphere and adverse conditions that exist in underground mines. These inspections can spot potential trouble in the system. Repair or replacement at that time averts the possibility of losing effectiveness of all or part of the system. 7.2.1 Cables Approximately once per month all cables in the communications system should be inspected for kinking, chafing, cracking, wear, stretching, or other signs of physical abuse. Particular attention should be paid to cable glands at the entry or exit points to the various units in the system, where the cable goes around sharp corners, in the vicinity of holding cleats which may be clamping the cable too tightly causing potential damage, and across the areas where the cable is exposed to physical damage from outside sources, such as equipment or falling objects. If a cable is damaged, it should be replaced as soon as possible. It is mandatory that the ground leads and connections to carrier current phones be thoroughly inspected and maintained in good condition, since considerable hazard may exist to the operator or equipment if a ground connection is broken. 7.2.2 Pager Phones The most readily available test set to determine if a pager telephone is operating correctly is the pager phone itself. The following physical check of the system can be performed at any phone station. 7.2.2a Listen Circuit Remove the handset from its cradle and listen to determine if the circuit is functional, as indicated by the presence of noise or conversation on the line. If no noise or voice signals are present at the handset receiver, take the following corrective action: 1. Operate the handset press-to-talk switch several times. Any corrosion on the contacts of this switch may cause a receiver to be temporarily inoperative. Repeated operation may clear the condition. 2. Open the cabinet and see if the battery cables are properly connected and are making firm contact. Check the handset cable and its connections in the cabinet of the pager phone, and see if there is any evidence of a break in the cable, corroded contacts, or poor connections. 3. Remove the handset receiver earpiece by unscrewing it counterclockwise (to the left), and remove the receiver from the socket. Examine the handset cavity; in some units, a patch of cotton batting or floss is used as a barrier to reduce acoustic feedback in the handset. If the cotton patch has absorbed moisture, remove it and replace with a crumpled ball of soft rubber, stuffed just far enough into the handset so it will not touch the receiver or switch terminals. 7.2.2b Page Circuit and Talk Circuit Push the page switch, squeeze the handset press-to-talk switch, and call any other phone. Release the page switch

Jan 1, 1984

By William A. Beck

"In 1912 bauxite was discovered in the Andersonville district, which lies in the 28th and 29th land districts of Georgia and comprises parts of Sumter, Macon, and Schley Counties. Mining was begun in May 1914 by the Republic Mining & Manufacturing Co. Considerable ore has been produced in this region since that time by individual interests and by the American Cyanamid & Chemical Corp., which acquired the property formerly owned by the Republic Co.The area was examined in the fall of 1941 by representatives of the Bureau of Mines and the Geological Survey, after which a prospecting program was begun by the Bureau. Drilling was started on December 26, 1941, and continued until November 18, 1943. A total of 1,192 holes was drilled in the district, and 3,679 samples were taken and analyzed.Mineral exploration agreements were signed by 146 property owners covering 42,128 acres. Holes were drilled on 121 of these properties, which have a total area of 38,778 acres.Drilling under this project disclosed several new deposits, of which four have been completely delimited. Previous prospecting in this area by mining companies did not find bauxite, as it lies under heavy overburden. Work by the Bureau indicates 14,412,000 long tons of ore containing 30 percent or more alumina. The total tonnage is divided as follows:Georgia State Highway Routes 26 and 4-9 traverse the district. The Central of Georgia Railroad passes through the center of the entire district (see fig. 1).The project was initiated by J. R. Thoenen, supervising engineer, Non-metals Mining Section, Mining Division, Bureau of Mines. It was under his general supervision until July 1942, after which it was under the general supervision of E. J. Lintner and Rowe McCrae, district engineers for Georgia, South Carolina, and Flordia, respectively.John C. Feeley, Jr., was project engineer from December 1941 to April 1942. Other engineers who assisted in the work on the project are R. E. Babcock, T. M. Romslo, Don M. Coulter, and Walter T. Lewiecki.Acknowledgment is due the metallurgical staffs at College Park, Md., and Tuscaloosa, Ala., for analyses of samples and beneficiation tests.Acknowledgment is also expressed to Alfred D. Zapp, M. W. Harris, Elmer Kneedler,and Parke D. Snavely, of the United States Geological Survey, for their aid, data, and maps.Bauxite was discovered in the Andersonville district in 1912 on lot 187 of the 28th land district, in Sumter County. This lot is situated about 1.5 miles west of the Flint River, on the south slope of the valley of Sweetwater Creek. Mining was started in May 1914 by the Republic Mining & Manufacturing Co. This and adjacent properties were acquired in 1930 by the American Cyanamid & Chemical Corp., which has been operating there since."

Dec 1, 1949

By Changshou Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,175 t (3,500 st) of ore per day with an average gold grade of 12.6 g/t (0.4 opst). The mine has a large horizontal extent of 762 by 152 m (2,500 by 500 ft) and a vertical extent of 6 to 61 m (20 to 200 ft). Based on the characteristics of the ore bodies, the deposits are divided into several mining zones. The geotechnical properties of mining zones are also different from one zone to another. A successful geotechnical collection system is very important for mining design and operation in the Leeville underground mine. Three methods are used to collect the geotechnical data in the Leeville underground mine: • Core logging. Most geotechnical data are collected by this method, which is based on exploratory drills and estimates parameters for rock quality designation (RQD), fracture frequency (FF), compressive strength and rock mass rate (RMR). • Site investigation. This method collects more detailed geotechnical data and geostructural data from work done in the underground drifts and stopes. Parameters of RQD, FF, compressive strength, RMR, rock tunneling quality index (Q) and geostructural data are estimated. • Data collected from drill holes made for the critical infrastructure facilities. This method provides the best detailed geotechnical information for areas in which the critical infrastructure located. A complete geotechnical database has been constructed using this geotechnical data collection system. The database can be used for the design of ground support, stopes and stope blasts, among other critical applications.

Jan 1, 2010

F. G. SMITH, Waterbury, Conn.-I would like to ask whether small amounts of iron give the maximum resistance at a low temperature, and if the large amounts of iron raise the temperature at which the maximum resistance occurs? That is, with a small amount of iron, will a maximum be at, say, 10°? F. E. BASH.-With the small amount of iron, the maximum is at a lower temperature, and with the increase of iron, the maximum increases; it seems to come to a maximum and then decrease; that is, increasing the iron up to a certain value increases the temperature at which there is a maximum of resistance, and any increase of iron beyond that value will start decreasing this temperature. With 2 per cent. of iron, the maximum is lower than for 1.5 per cent. which was the value that we found to be satisfactory. F. L. DRIVER,* Jr., Harrison, N. J.-I would like to ask what chance there is of the instrument companies getting together and deciding on standards for both manganin and constantan? We make both of these alloys in this country and we find that each one of the instrument com-panies who buy these materials require different standards of specific electrical resistance and thermal e.m.f. For instance, some of our cus-tomers require an electrical resistance in manganin or therlo of 240 ohms per circular mil foot and others require it with a specific electrical resist-ance of 270 ohms per circular mil foot. They buy these alloys in relatively small quantities so that it means much extra melting and supervision when making up small quantities for each consumer. If something could be. clone to eliminate this, it would be a benefit to the instrument com-panies, who could secure their material more cheaply, and to the manu-facturers, who would not have to spend so much time and effort in special manufacturing.

Jan 12, 1919

IT is intended in this paper to present in broad outline to the members of the Institute a short account of the conditions and operations that constitute what is, variously known as Subterranean Warfare, Military Mining, or Tunnelling. Realizing ,the magnitude of the operations, and the varied and minute details met with in them on,the Western Front, it is the writer's intention to confine these notes to operations carried out by the First Australian Tunnelling Company. In so doing there is no wish to detract from the very fine records of the Second and Third companies it is to be hoped that members of the Institute (or others) who were with these companies will write accounts of their doings-the former in the water-logged areas to the south of Armentieres, and later in the sand-dunes at Lombardzee, and the latter in the chalk area of the Lens coal...

Jan 1, 1920

By Stanley Lefond

Industrial Minerals, often called the Cinderella Minerals or the Building Blocks of industry continued their growth patterns through 1973, although profits were slightly lower due to the cost-price squeeze. Most of the individual reports which follow indicate growth rates of 3-15%. Surprisingly such commodities as sulfur held firm in spite of the over supply in the Canadian gas fields; cement was in short supply while the asbestos industry reported a worldwide shortage of group 4 and 5 fibers. Talc and perlite production set new records. In synopsis, 1973 was a productive year for industrial minerals. However 1974 onward appears to be one of contradiction. The unsettled conditions of world economics, the energy shortage, compounded by the Arabs oil embargo have created great problems for all industries. The high energy consuming segments of the Industrial Minerals field will be under intense pressures. On the other hand limestone, lime and perhaps trona, nahcolite might be consumed in ever increasing tonnages in SO2 removal systems connected with smelters and coal-fired power stations. The effects of the proposed changes in the staking, claiming and exploitation of federal lands by the BLM may also have serious repercussions not only to the industrial minerals field but to the entire mining industry. 1974-1975 will certainly be ear-marked as a year of frustrations and difficult decisions.

Jan 2, 1974

By Per Anders Eidem, Merete Tangstad, Jens Davidsen

"During excavations of submerged arc furnaces producing silicomanganese, silicon carbide (SiC) has been found. Contributing to the size of the inactive area of the furnace, the active area of the furnace where reactions occur will decrease, thus reducing the potential for pre-reduction in the furnace.This work studied the formation of SiC from the liquid-solid reaction between slag, metal, and metallurgical coke. Slags and metals with different levels of silica (S1O2) and silicon (Si) have been studied. The slag and metal has been heated together with coke, and the samples investigated by microprobe. The results show that SiC was formed on the coke particle through reactions with both slag and metal. For the metal, the carbon most likely diffused through the SiC to react with Si in the alloy. SiC formation with slag is likely to go through the reduction of Si02 to Si.IntroductionToday, Silicomanganese (SiMn) is produced in submerged arc furnaces (SAF) by reduction of S1O2 and manganese oxides, mainly with metallurgical cokes. Typically, the tapped metal has a silicon content of 17 - 20 wt.%. To achieve higher levels of Si, the metal can be refined by adding off-grade silicon metal, yielding low carbon SiMn. [1]. What is believed to be SiC that has been found during dig-outs of SiMn furnaces producing high silicon alloy. It is possible that excess amounts of SiC in the furnace cause operational problems, since SiC will occupy furnace volume. As SiC accumulates, the active volume of the furnace will decrease, increasing the flow of material and gas in the active areas of the furnace. Formation of SiC is inevitable, so it is desired to keep the formation as low as possible. To be able to control the formation of SiC, one has to understand the basic mechanisms."

Jan 1, 2012

By Wei Han, Zhenwei Liu, Jianhong Yang, Qingwei Qin, Tiejun Chen, Zili Huang

The preparation of industrial ammonium molybdate from molybdenum concentrate was conducted according to the process of roasting—leaching—purification—precipitation—crystallization. The optimum technological conditions were determined: the roasting temperature was 680 degrees C, the roasting time was 2.5 h; in the leaching process the alkali excess coefficient was 1.2, the reaction temperature was 80 degrees C, the liquid-solid ratio was 3:1, the leaching time was 3 h; the amount of (NH4)2S added into the solution was 1.1 times of the theoretical amount, the temperature was 80-85 degrees C, and the terminal pH was 8.5-9 in the purification process; the density of the solution was 1.4-1.6 g/mL, the pH was 1.5-2 in the precipitation process; temperature of dissolution was controlled at 80-90 degrees C. The recovery of the preparation of ammonium molybdate can reach 85.18%.

Mar 1, 2017

By E. Simode

El presente texto describe los métodos de medida y ventilación aplicados a las labores de subterráneos. En este sentido, los elementos fundamentales de tales estudios son las resistencias de los circuitos, que se determinarán a partir de medidas de pérdidas de cargas y de caudales. La calidad de dichas medidas es condición para el éxito del método, dado que en ellas residen las causas de numerosos errores. Entre los aparatos de medida tenemos: la medida de los caudales, velocidad, secciones y las presiones. Los métodos de medida son: medida de los caudales, medidas de las pérdidas de carga, expresión de la resistencia de un elemento, esquematización de los circuitos,.

Sep 1, 1962

By Clarence G. Merritt

Stainless iron, as mild stainless steel is usually called, an alloy ranging from 11.50 to 15.00 per cent chromium with carbon under 0.12 per cent, has been considered to be not appreciably affected in respect to corrosion resistance by heat treatment. This metal, while one of the most widely used of the "straight" chromium stainless alloys, has failed in many applications because of insufficient information regarding heat treatment. These failures have been attributed to many possible causes from an inherent lack of resistance to corrosion and misapplication to mlysterious electrolytic effects or comparatively minute non metallic inclusions. Many uses for a steel with such excellent physical properties as are latent in this alloy have been lost on account of corrosion failures which could have been avoided by applying proper heat treatment. The alloy has not received the recognition or attention it should because of the fact that the details of its metallurgical behavior were not thoroughly understood. Response to heat treatment of the steel is well known as regards tensile properties,1-2 but its application has been for improvement in tensile characteristics or on account of machining considerations rather than for corrosion prevention. The potential user of this steel has not been clearly advised in papers, either technical or commercial, that have been written about it in the last 10 years or more, of particular features that are of prime importance in developing the excellent properties of this metal. The data to be presented in this paper are concerned mainly with the effect of heat treatment on the corrosion resistance, but a study has also been made of the concurrent microstructural changes and an explanation developed for the phenomena revealed, as well as a correlation to the other physical properties—hardness, tensile characteristics and impact strength. Stainless steel, largely used for cutlery purposes, an alloy of approximately 13.00 per cent Cr with 0.30 per cent C;, must be hardened and the surface prepared by polishing or pickling for best resistance to staining and corrosion. Monypenny reports that a loss of hardness is

Jan 1, 1932

By P. Hand

Most coal plants must run under conditions of varying feed conditions or are asked to produce qualities different from that used in the design. This can cause overloaded conditions as the ?bottlenecks? within the plant, depending on plant operation or as the feed changes. During plant design, geological information can be used to determine washability envelopes and blends that may be expected. Historical data can also be used to develop a size distribution envelope as well as to assign reasonable models for each of the unit processes. In operation, a plant can be sampled to determine changes and to refine process models. The information obtained can then be used in an accurate simulation to define how the plant can deal with the changing environment. This paper uses Limn: The Flowsheet Processor to simulate the coal plant in detail and will produce an accurate model, in terms of equipment sizing as well as water, medium, and solids balance, for each change in feed condition. It will show examples of running the simulation through complete density and size ranges and will determine the equipment required to address each part of the performance envelope.

Jan 1, 2010

By T Leach, F Kaiqiang

The Jianchaling gold deposit is located about 1200 km south west of Beijing in central China. The deposit was discovered in 1988 by the Northwestern Geological Exploration Bureau (711 Exploration Team). Sino Gold Limited, an Australian based company, developed the mine in 1998 and is currently operating a 1000 t per day underground mine, producing about 80 000 ounces of gold per year. The pre-mine resource for Jianchaling was 1.6 million tonnes at 9.85 g/t gold. The deposit occurs within the east-west trending Mesozoic Qinling-Dabie orogenic belt formed during the Yanshanian Orogeny. In the Jianchaling region, gold mineralisation is primarily hosted by regional west-northwest to east-southeast striking faults, the most important of which, the reverse sinistral F145 fault, hosts the larger gold deposits including Jianchaling. At the mine scale, the most important zone of mineralisation is localised within a shallowly north dipping dilation on the F145 fault. Proterozoic dolomite forms the hangingwall and serpentinite and talc schist the footwall to the fault. Within the footwall, serpentinite is the most important host rock to mineralisation. Initial alteration involves replacement of serpentine to dolomite ¦ pyrite, talc to ankerite ¦ pyrite, and magnetite and chromite to pyrite, the latter locally through a transitional hematite phase. Proximal to feeder structures, the carbonate minerals have undergone partial dissolution and replacement to quartz. Gold is related to arsenean pyrite and marcasite rimming and replacement of early-formed pyrite, and associated with iron release during the processes of dolomitisation, silicification and carbonate dissolution.

Jan 1, 2004