Search Documents

By Austin Gudmundsen

"The smoke nuisance, like many other undesirable and longstanding features in our present civilization, is still with us. On reviewing the situation we are astonished to find no authentic record of a major smoke-abatement campaign that has succeeded in eliminating a smoke nuisance, in spite of the fact that the problem has been with us since the use of bituminous coal began. We might well ask ourselves where the trouble lies; is the problem impossible of solution? We can not blame the average citizen for harboring this thought as a conviction. He has been urged for so long but sees so little evidence of progress. He has repeatedly been assured by the scientist and the engineer in most convincing terms that smoke. is unnecessary, that it can be avoided; small wonder is it that he is beginning to distrust so-called authority on the subject.On the other hand, the scientist and engineer are entirely within their rights. We all know that even high-volatile coal can be and is now being burned with no visible smoke. We know that even small domestic heating furnaces, with favorable conditions and with proper care, can be fired by hand without producing much smoke. And we know that when such equipment is fitted with suitable stoking devices, little or no smoke results. What, then, is the answer?Perhaps we may learn something from a critical examination of a typical smoke-abatement problem. Probably one of the most enlightening campaigns that has been waged in the United States is that of Salt Lake City, Utah; therefore, the purpose of this paper is to discuss the important aspects of this particular case."

Apr 1, 1930

By C. J. Bise

Continuous mining accounts for about 69% of the nation's underground coal production. This level is not expected to change much in the near future. This is because continuous mining represents the primary means of under- ground coal production. It is also the primary means of driving development entries for underground coal mines, including longwall mines. The continuous miner worksite contains many characteristics that can lead to personnel accidents. It continues to be an area of concern for mine managers, safety engineers, and training coordinators. In an effort to assist mine management in attempts to reduce the number of accidents and injuries sustained in this area, this paper presents a loss-control-based, non-intrusive strategy for conducting safety evaluations at continuous miner worksites.

Jan 1, 1991

"U.S. Bureau of Mines Publications and Articles, 1994 with Subject and Author Index Compiled by Office of Public Information U.S. Bureau of Mines (USBM) Department of the InteriorINTRODUCTIONThe U.S. Bureau of Mines (USBM) was established in 1910 to conduct inquiries and scientific and technological investigations on mining and the preparation, treatment, and use of mineral substances; to promote health and safety in the mineral industries; to conserve material resources; to promote economic development; to increase efficiency in the mining, metallurgical, quarrying, and other mineral industries; and to inquire into the economic conditions affecting those industries. The organic act of the Bureau, as amended by Congress and approved February 25, 1913, made it the province and duty of the Bureau of Mines to ""disseminate information concerning these subjects in such manner as will best carry out the purpose of this Act.""In accordance with this directive, USBM reports the findings of its research and investigations in its own series of publications and also in articles that appear in scientific, technical, and trade journals; in proceedings of conventions and seminars; in reference books; and in other non-USBM publications. This edition describes reports and articles published during calendar year 1994. It supplements the 50-year list of Bureau publications issued from July 1, 1910, to January 1, 1960; 1 the 50-year list of articles by Bureau authors published outside the Bureau from July 1, 1910, to January 1, 1960; 2 andthe 5-year lists of publications and articlesfrom January 1, 1960, to December 31, 1964,3from January 1, 1965, to December 31, 1969,4from January 1,1970, to December 31,1974,5from January 1,1975, to December 31,1979,6from January 1,1980, to December 31,1984/and from January 1, 1985, to December 31,1989.8"

May 1, 1995

By G. Barr

"The Polymetallic Twin Metals Project deposits in Northern Minnesota are being developed by Twin Metals Minnesota. Amongst the flowsheet alternatives being examined at a prefeasibility study level is one involving flotation of a bulk concentrate followed by high temperature autoclaving of the concentrate using the PlatsolTM Process to solubilize all the valuable metals in the concentrate (Cu, Ni, Pt, Pd and Au). Autoclave operating conditions have been established in which recoveries of all the pay metals are in the 92 to 99% range, and the autoclave residence time has been reduced to an hour. The stability of the precious metals in solution after autoclaving has been assessed, as well as the impact of internally recycling process liquors to the feed to the autoclave.INTRODUCTIONPlatinum group metals (PGMs; platinum, palladium, rhodium, ruthenium, iridium and osmium) are traditionally recovered from their ores by production of a high-grade concentrate by flotation and/or gravity concentration followed by smelting of the concentrate. Concentrates are smelted to remove nonsulphide minerals and converted to remove iron and sulphur. The resulting high PGM grade matte is processed hydrometallurgically to leach the base metals, leaving a residue with a very high grade (20-40%) PGM concentrate for final refining to individual PGMs. Due to the complexity of this process and its high capital cost, this process can only be applied economically to high grade PGM ores. Lower grade PGM concentrates might be accepted as copper and nickel concentrates but may not yield attractive payment terms for the PGMs. The mineralized Duluth Gabbro region of Minnesota hosts several low grade base and PGM deposits and Twin Metals Minnesota is working to develop the Twin Metals Project deposits. Earlier studies at both pre-feasibility and feasibility level, by other mining companies, have failed to yield an economically viable project based on the traditional process. It is possible to produce a saleable copper concentrate from these ores, but economic recovery of nickel and PGMs into saleable concentrates proved elusive.In the late 1990’s and early 2000’s the Platsol™ process was developed at SGS in Lakefield, Ontario (at the time Lakefield Research Limited) for the NorthMet deposit (also within the Duluth Gabbro) owned by PolyMet Mining. The process developed was a high temperature chloride-assisted pressure oxidation process capable of dissolving simultaneously the base metals (Cu, Ni, Co, Zn), gold and the PGMs."

Jan 1, 2012

By W. E. Davies

"This paper is the sequel to that on Developments in Sintering Efficiency delivered by Davies and Mitchell at the International Ore Dressing Congress, Stockholm, 1957. Attention is drawn to the fundamental concept of sintering as a heat transfer process, in which the ignition heat is continually transferred onward through the bed as a heat wave. By its passage, this heat initiates endothermic 'changes, such as carbonate decomposition, whose energy requirements are supplied by the combustion of the fuel contained in the bed.Ideally, the heat wave should be generated by the ignition hood followed by the pre-heating of the incoming air. The fuel content of the bed should be no more than the theoretical quantity needed to balance the endothermic changes. In practice, the heat wave is seriously short of energy and this is offset by excess fuel in the bed. As a result, sinter quality suffers, more return .fines are produced, and fuel is wasted, a loss of efficiency which could be avoided if the fundamentals of correct ignition were more widely appreciated.Sintering speed, otherwise heat wave velocity, is a function of the rate at which the incoming air acquires .heat from the cooling sinter and imparts it to the unburned feed below the combustion zone. It is thus a function of rate of air flow and so depends on bed permeability>. Ways of• improving and maintaining permeability at the maximum consistent with thorough sintering are discussed, particular reference being made to taconite concentrates. The possibilities of recrystallizing refractory ores into forms more amenable to physical concentration techniques by sintering are visualised, very little expenditure on heat energy being required when the process is operated near the ideal conditions."

Jan 1, 1960

By Franklin J. A, Tam C. Palangio, N H. Maerz

WipFrag systems I, II and III have become the world standard in photoanalysis systems to measure particle sizes. Mines, quarries and excavating contractors can now easily measure blast results and track the progress of optimization efforts. This technology was developed and evolved ~to allow automatic measurements of the size distribution of particles on moving conveyors, in truck boxesand on crusher feeds. Production machinery can now be controlled by photoanalysis results and multiple cameras allow various locations to be monitored by a single system. Blast designs can, be monitored on a shot by shot basis. Changes in delay times, explosives, patterns and hole sizes can be quickly evaluated. Along with this measurement capability has come a heightened awareness of the importance of “optimum size” and uniformity of particles for lowest cost production and material handling efficiency. In the past, savings in the “drill / blast” cycle of the operation were sometimes overshadowed by downstream production costs related to fragmentation. Now total production costs can be compared with fragmentation sizes, which will immediately show the trend towards optimum size for economical production. No cost reduction program can be complete without this critical information.

Jan 1, 1998

By R J. Tremblay, R. R. Hoffman

This paper deals with materials of construction and problems encountered and overcome in leaching and filtration of oxidized sulphuric acid slurry in the Port Radium mill after eight years of operation. The slurry is characterized by a high calcium sulphate content as well as a high chloride level under oxidized conditions, both of which affected initial design and subsequent changes. Leach agitation tanks are of wood with a mild steel superstructure and stainless steel agitator and moving parts below solution level. Electro-polished 316 stainless steel cooling coils are used for temperature control of the slurry. The string filters are of the Oliver type with wood decking. Extensive use is made of wood, Linatex lined mild steel and stainless steel for the slurry handling. A typical analysis of the slurry solution follows:(pH-1.30) ClOa Fe+++ Free Acid UaOs c1-so.--0.10 gms/litre 10.2 gms/litre 6. 7 gms/litre 3.5 gms/litre 2.0 gms/litre 155 gms/litre

Jan 1, 1961

Sec. 1. The membership of the Institute shall comprise six classes, namely: 1. Members; 2. Honorary Members; 3. Senior Members; 4. Associates; 5. Junior Members; 6. Rocky Mountain Members. All shall be equally entitled to the privileges of membership, excepting that no member of any class whom residence shall be outside of the United States of America, except those residing in Mexico and Canada, shall be entitled to vote. SEC. 2. Members: A person to be eligible for election or transfer into the claw of Member must be at least 27 years of age and must have had at least six years' employment in the practice of engineering, mining, geology, metallurgy, or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. This shall not apply to Rocky Mountain members.

Jan 1, 1944

By Boyd Guthrie

The current use of Mid - Continent crude oil for the manufacture of war products , such as aviation gasoline and lubricating cil , has caused an acute shortage of available supply from established sources . Therefore , refiners who heretofore have had no reason to use West Texas crude oils now are considering them as charging stock and need more information concerning their characteristics . The Bureau of Mines has published several reports3/ giving analyses of the most important of these crude oils . However, to make the applicable data in these publications readily available to refiners , the present compilation of analyses of West Texas crude oils has been prepared . Data showing the effect of catalytic desulfurization of naphthas from West Texas crude oils have been presented in a restricted Bureau of Mines Report of Investigations . These analyses were made under the general supervision of R. A. Cattell , chief, Petroleum and Natural Gas Division, Bureau of Mines , Washington, D. C. , and N. A. C. Smith, supervising engineer , Fetroleum Experiment Station, Bureau of Mines , Bartlesville, Okla . , and under the direct supervision of Harold M. Smith, senior petroleum chemist, Bartlesville , Okla .

Jan 1, 1944

COUNCIL OF ECONOMICS OF AIME Formerly Mineral Economics Division Established as a Division December 15, 1948 Established as a Council February 26, 1957 Douglas Donald, Chairman Sheldon Wimpfen, Vice-Chairman (Mining) A J Phillips, Vice-Chairman (Metals) E Connaughton, Vice-Chairman (Petroleum) J S Vanick, Contact AIME Director A H Lindley, Jr Secretary-Treasurer Lehman Brothers 1 William Street New York 4, N Y COUNCIL OF EDUCATION Formerly Mineral Industry Education Division Established as a Division January 15, 1932 Established as a Council February 26, 1957 L E Shaffer, Chairman J D Forrester, Vice-Chairman O Cutler Shepard, Past Chairman , Contact AIME Director

Jan 1, 1959

By E. M. Norris

THE Western phosphate deposits extend over a large area in the Rocky Mountain region, comprising portions of south central Montana, southeastern Idaho, northeastern Utah, and southwestern Wyoming. A limited acreage of these deposits passed into private ownership prior to Dec. 9, 1908, at which time 7000 sq. mi. of land in these phosphate fields was withdrawn from public entry by direction of the Secretary of the Interior. Under the Act of Feb. 25, 1920 (41 Stat. 437) title to all phosphate lands in the public domain was reserved to the United States with provisions for leasing portions to citizens, corporations, states, etc. The above act, in effect, created by law a Western phosphate reserve of approximately 2,269,055 acres.

Jan 1, 1944

By P. P. Reichert, L. S. Gournay, N. T. Burdine

An investigation of equivalent pore entry radii in typical samples of petroleum reservoir rock and the pore volume associated with each value of pore entry radius has been made. Theoretical discussions together with experimental procedures for obtaining pore entry radii and the distribution of pore volume with pore entry radii are presented. Experimental results on a number of core samples, along with typical distribution curves, are shown. Data on the per cent of the pore volume filled by mercury at a pressure of 1500 psi are included. The results of re-runs of samples, made possible by regenerative apparatus, show the repeatability of the data and indicate the amount of physical change in the samples by mercury penetration. Theoretical equations for calculating permeability from pore size distribution data were derived and the results of such calculations are compared with measured gas permeability data. The effect of the shape, surface area, and weight of the sample on the pore size distribution of reservoir rocks was investigated experimentally. Mercury capillary pressure curves are compared with those obtained by the porous diaphragm method using pas to displace water. Standard core analysis techniques, in general, lead to quantities which are statistical averages of the varying properties of the samples under examination. Although such statistical information has real value in predicting the gross performance of porous bodies. it fails to provide fundamental information concerning the properties of the porous medium itself or any processes which may be occurring in it. For example, a gas permeability measurement on a core sample is an indirect way of determining an average pore radius for that particular sample. Since there are many combinations of pore radii that will give the same radius. and, hence, the same permeability, no information is obtained on the pore size distribution. Furthermore, similar values in permeability do not imply similarity in other properties of a porous medium. For instance, it is possible to have two core samples with identical permeability which would have different residual oil contents at the end of an air-oil drive, or even different amounts of interstitial water. It has been recognized for some time by the petroleum industry that a determination of pore size distribution for porous reservoir rocks offered promise of increased understanding of fundamental flow processes in the porous matrix. and therefore of petroleum res- ervoir performance in general. There have recently been published several methods for determination of pore size distribution in porous materials. A report is given here of the modifications in equipment and technique required to adapt one of these methods to measurements on petroleum reservoir core samples. Although only a few correlations or applications of the method are available for presentation at this time, the technique is brought to the attention of the industry so that the opinions and experience of others with this or similar techniques may be exchanged. It seems possible that the method will have wide application in the future. METHOD There are three general methods which may be employed to measure the pore size distribution in naturally occurring rock formations. One method1 is based on experimentally determined adsorption isotherms for calculating the surface area of the porous medium. Knowing the surface area and the pore volume, a rough estimate of the pore radius can be made. Since this method depends on the thickness and uniformity of the adsorbed layer, the validity of the results would be highly questionable. A second method utilizes capillary pressure data obtained by static dis-

Jan 1, 1950

By R Kahnt, S Jahn, D Baacke, M Eckart

Relocation into the Lichtenberg open pit mine of about 110 million m3 of sulfide-bearing and ARD-generating waste rock piled up on the surface is the most important and cost-intensive single surface restoration project conducted by WISMUT GmbH at the former Ronneburg uranium mining site. The waste rock comprises for the most part Palaeozoic shales, limestones and diabases with pyrite contents of up to seven per cent. Waste pile relocation began in 1992 and is scheduled to be completed by 2007. The approach used for relocation has been extensively described elsewhere (Jakubick et al, 1997; Hockley et al, 1997; Chapman et al, 1998; Paul, 2003). Following completion of the backfill that will be up to 60 m above the initial ground level, a dry cover will be placed on top of the backfilled mine wastes. The area to be covered amounts to about 220 ha. Design planning for the final cover placement of which is to begin in 2004 had to be based on a comprehensive cost-benefit analysis over and above compliance with legal requirements. The crucial question to be answered in this respect was to determine û in addition to the expenditure required to ensure reuse, radiation protection and soil protection û the extent to which additional time, effort and money were justified in order to minimise contaminant release from the unsaturated portion of the backfilled pit contributing to total releases into the ground water and possibly achieve savings in long-term operating costs for the on-site water treatment plant. Optimisation was based on contaminant balance modelling for the entire site reproducing dominant physical and geochemical processes. Among the specifics underlying the cover design is that contaminant release from the backfilled open pit must not be considered independently of that from the adjacent flooded underground mine and that a major part of the backfilled open pit will also be submerged. Following weighing of cover-related short- and long-term costs it was found that higher construction costs for the various cover options will not be offset by cost savings in the long-term water treatment. As a consequence of pit flooding, even a costly multiple cover including an impermeable layer will only insignificantly impact on concentrations and loads at ground water spill over points. As a result of comprehensive studies and investigations, a combined cover of cohesive soil material from on-site excavation overlain by a 0.4 m thick storage layer to restore natural soil functions for revegetation was derived and submitted for approval. Together with hydraulic measures, this approach is to meet any requirement in terms of radiology, water protection, stability, erosion protection, and reuse.

Jan 1, 2003

By Charles H. Behre

UNDER the caption "fault," geologists intend to include all mass movements of solid rocks over adjacent rock masses. When these are studied long after their origin, however, circumstances make it possible to recognize as "fault" only formations showing clear evidence of actual movement of one side with respect to the other. Necessarily the chief evidence consists of the offset of a vein, bed, or other key structure. Planes of movement parallel to the bedding, or nearly so, are recognized with difficulty or are overlooked and hence many important faults are wholly unrecorded. Indeed, among standard American references on structural geology, one alone emphasizes the importance of bedding-plane movements and that one only briefly1. For some time the writer, cognizant of this difficulty, has paid special attention to such movements, both as observed in the field and as recorded in the literature. It is believed that enough data are now at hand to justify a short discussion. Its purposes are fivefold. It is desired first to briefly classify and describe at least the more common kinds of bedding-plane faults, and second, to examine the causes and manner of their formation, at least in instances where the subject has not yet been well covered by other investigators. Third, certain by-products of bedding- lane movements are of such conspicuous importance to the economic geologist and mining engineer as to merit mention. Fourth, concrete illustrations should be placed before the reader in order to lend reality and to furnish a basis of comparison with his experience; such illustrations will necessarily be scattered through the text of this paper. They are only in part from the writer's own field observations. The fifth and prime objective of this paper is to direct attention to the great importance of movements on the bedding planes, in the hope that the recognition of such movements and their significance may simplify mining problems.

Jan 1, 1937

By R. J. P. Lyon, A. E. Prelat, H. Lawrence

Introduction In 1977, the US Bureau of Mines awarded a grant to the state of South Carolina to explore the possibility of using Landsat multispectral scanner (MSS) data as an aid in monitoring surface mining activities in selected counties of the state. Work had been done in Aiken County prior to the grant by USBM and state personnel at the EROS Data Center using both the GE Image 100 and ESL IDIMS systems. The initial work on the 1:100 consisted of locating and measuring the areas of various kaolin mines. The results were excellent on location, identification, and accurate area measurements of several mines as compared with aerial photos of each mine. The effort also included locating and measuring the size of all mines (including sand and gravel) within two US Geological Survey (USGS) 7 % - min quadrangle maps. Line printer overlays using the IDIMS equipment and software resulted in the location of all known mines within an estimated error less than zt 91.4 m. Mine acreage was calculated by counting each symbol (which represented one pixel) and multiplying by 1.1 (the number of acres per pixel). [Fig. 1] shows a portion of one quadrangle overlay. [Table 1] gives a comparison of acreage measured for several mines from the 1-100 and IDIMS system vs. aerial photo measurements. The success of the preliminary work resulted in the South Carolina Land Resources Conservation Commission submitting a proposal to USBM for funding to expand the scope of work to other mineral mining operations within the state and determine if Landsat Imagery could be used to accurately locate and measure mining and reclamation activity on a continuing basis. Three separate tasks were proposed for selected kaolin mines in Aiken County: Task 1, to measure changes in active mine developments over the period 1974-77; Task 2, to measure reclamation activity, and, if time permitted, seasonal changes in mine signatures over the same period of time; and Task 3, to classify one complete mining operation (i.e., differentiate between active, spoil, overburden, water, reclaimed portions and surrounding terrain. The major effort was centered around J.M. Hubeis Richardson mine. Mining operations were progressing in a northerly direction and included three areas of reclamation: one prior to 1974; one started during early 1974; and one reclaimed during 1976. A discussion of all work done under the grant is available in the March 1979 Final Report listed under References. Computer compatible tapes (CCTs) containing MSS data from Landsat Path 18, Row 37, were purchased from the National Aeronautics and Space Administration (NASA) covering the period February 1974 through January 1977. The MSS data were processed on the General Electric Image 100 using parallelepiped classification at the EROS Data Center's Data Analysis Laboratory, Sioux Falls, SD, and at the Stanford Remote Sensing Laboratory, Stanford University, Palo Alto, CA, utilizing both an unsupervised classification (ISOMIX) and a supervised classification (sequential discriminant analysis). Studies at Stanford University Remote Sensing Lab (SRSL). In Feburary 1977, initial work was begun at Stanford using the STANSORT computer program running on a DEC PDP-10 (Honey, Prelat, and Lyon, 1974). This software is fully interactive and designed to study Landsat CCT data at high resolution (small areas) on a pixel-by-pixel basis (Lyon, 1977). Unsupervised Classification. The initial step was to locate the Richardson mine on the positive print of the full Landsat scene from CCT 1644-15252, dated 6/17/74. This was relatively easy due to a large abandoned kaolin mine and a long narrow pond clearly visible in the scene. Two unsupervised classifications of the Richardson mine were run using ISOMIX clustering (Honey, Prelat and Lyon, 1974). (ISOMIX essentially follows the interactive clustering procedures of ISOCLS Kan, Holley, and Parker. 1973). Although the classifications were successfully accomplished, it was apparent from the TV display that the results did not clearly define the mine areas. A supervised classification would have to be made in order to clearly separate each portion of the mine. Supervised Classification. This classification was done using the Stepwise Discriminant Program (BMDO7M) which is part of the BIOMED package (Dixon, 1970) and involved the following steps: Training group populations were selected and the digital

Jan 1, 1982

By F. D. DeVaney

[In the course of the investigation by the U. S. Bureau of Mines and the Missouri School of Mines and Metallurgy at the Mississippi Valley experiment Station at Rolla, Mo., on the beneficiation of the low-grade manganese ores of the country, some samples from the Cuyuna District, Minn., have been examined. The work was done under the direction of W. H. Coghill, supervising engineer of the Mississippi Valley Experiment Station. Josoph and Kinney5 in venting about the relative importance of Minnesota deposits of low-grade ore compared to the total reserves say:]

Jan 1, 1930

By M. H. Pelkki, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Research has shown that excessive soil compaction is detrimental to the establishment of trees in reclaimed soils. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed soils. It is believed that reclamation practices that minimize soil compaction will produce better results when forestland is the intended postmining use. The University of Kentucky has developed reforestation test cells on reclaimed soils at a surface mine in eastern Kentucky to test this hypothesis. Each test cell has been planted with various species of trees. Since 1997, data have been collected at these test cells for soil average dry bulk density, average penetration resistance, average depth to refusal and average survival rate of trees. These data have been correlated to determine the relationship between soil compaction and tree-survival rate. It is believed that these two soil-compaction parameters may ultimately be used to predict tree-survival rates on reclaimed surface mined lands.

Jan 1, 2003

By H. W. Young

Development of high-tension outdoor substations during the past few years has been due primarily to economic reasons. The demand for power in small communities could not be met with the conventional and Fig. 1.—33,000-VOLT step-up outdoor air-break switch and substation installation outside of a powerhouse generating at 2300 volts stepping up to 33,000. Twenty-one coal mines are supplied from lines leading from this installation. comparatively expensive indoor types unless the rate for service was materially increased. To prove that the problems lncident to development have been solved successfully, it is only necessary to point to the wide adoption of outdoor substations by utility companies. Passing at once to the question as to whether outdoor substations are applicable to

Jan 1, 1920

By S. Caron, M. Bourassa, J. Châteauneuf, L. Tardif

"Since many years, the Yvan-Vézina gold plant custom mills and processes different ore types that show different behaviors. Because of this, cyanidation control is more complex than for a typical milling operation. In 1992, a Cyancor™ on-line « free cyanide » analyzer has been installed for monitoring and optimizing cyanidation. This implementation significantly reduced cyanide consumption for the overall cyanidation process. In order to further reduce cyanide costs, an automatic control strategy has been implemented to decrease fluctuations of« free cyanide » from their set points.This paper outlines the major steps of the project: process control audit, control strategy development, implementation and running-in period. Control strategy features include data filtering modules, adaptive PID algorithm and set points management modules are also presented. Finally, the strategy efficiency is illustrated with load-disturbance responses.IntroductionLocated in northwestern Quebec, the Yvan-Vézina plant has an average capacity of 1300 t/d using carbon-in-pulp technology. In 1991, the Yvan-Vézina gold plant was processing three types of ores (Beauchemin, Mouska and Silidor mines) and a pyrite concentrate (Beliveau mine). A cyanide reduction program was then undertaken to reduce « free cyanide» fluctuations <6>. To reach this objective, the optimum cyanide concentration was determined for each ore, a continuous monitoring method with the Cyancor™ on-line analyzer was developed and a tighter control of cyanide addition was applied. These modifications to the leaching practice significantly reduced cyanide consumption.After a while, it was observed that regulation of « free cyanide » concentrations could still be improved by the use of an automatic control strategy. Yvan-Vézina and CRM began collaborating in 1995 to develop and implement such a strategy. Results show that main disturbances of the circuit (e.g. ore mineralogy and pulp feed rate) can be significantly overcome in order to reduce their effects on the leaching operation."

Jan 1, 1998

The Lennard Shelf is an Upper Devonian carbonate reef complex striking northwest for 350 km along the northeast margin of the Canning Basin. Numerous small Mississippi Valley type (MVT) Pb-Zn prospects occur within this belt, including the Wagon Pass prospect, located 105 km east of Derby in the Napier Range. At Wagon Pass, the base of the Upper Devonian sequence is a cobbly, dolomitic sandstone, the Van Emmerick Conglomerate. This is conformably overlain by the Frasnian to Famennian Pillara cycle Lower Napier Formation fore-reef deposits. These are characterized by red algal wackestones and terrigenous stylo- bedded packstones, with common dolomitization. The conformably overlying Famennian Nullara cycle contains a classic reefal assemblage, consisting of flat lying Nullara Limestone back-reef, fore-stepping massive Windjana Reef, and steep basinward dipping Upper Napier Formation marginal slope. The Nullara cycle is not dolomitized. The Wagon Pass mineralization is hosted by Lower Napier Formation dolomite. Mineral- ization consists of complex intergrowths and semi-massive assemblages of sphalerite and galena, with subordinate pyrite, marcasite, chalcopyrite, bornite, digenite, covellite and bravoite. Ore textures include granular and colloform. Gangue minerals are dolomite and very fine grained green chloritic clay. Although mineralization commonly occurs as reticulate fracture fillings, its overall distribution is stratabound. Ore paragenesis involved early "diagenetic" dolomitization, followed by breccia formation with chloritic and granular dolomite matrices. Main stage galena-sphalerite mineralization then occurred, accompanied by pervasive chloritization of silty units. Ore genesis was probably related to basin-derived "oil field" brines, with open space textures in the mineralization quite comparable to textures seen in Canning Basin dolomitic hydrocarbon reservoirs. Fluid inclusions in the host dolomite have typical MVT homogenization temperatures of 70-1150 C, and contain minor organic phases. The Van Emmerick Conglomerate, with its high porosity, dolomitization and weak Pb-Zn anomalism, was probably the aquifer for the mineralizing brines. Access of ore solutions to the Wagon

Jan 1, 1986