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By James R. Arnold, John G. Mansanti

BACKGROUND Gold Fields Mining Corporation started their Chimney Creek operation in late 1987. The dump leaching operations commenced in October and the mill startup took place during the last half of November. The milling process at Chimney Creek is almost a conventional CIP plant with the major exception being the installation of a second thickener as a washing stage prior to CIP12 ' A simplified flow sheet is shown in FIGURE 1. Most of the gold in the mill is liberated by grinding in cyanide. After grinding in a conventional SAGball sill circuit, the cyclone overflow reports to the thickeners. The thickener overflow from the first thickener is pumped through 5 stages of carbon columns for gold adsorption. Slurry from the thickener underflow is leached, washed, re-thickened and pumped to CIP. After approximately 6 hours of retention time in CIP, the slurry is pumped to tailings for final deposition. The carbon from CIP is transferred to the third stage of carbon adsorption and then advanced as normal through the columns and strip circuit. Loaded carbon is stripped at approximately 1500C (3000 F) and 55 kPa (80 psi). After 4-5 hours of stripping, the grade of four tons of carbon is reduced from 5,140-6,860 g/t (150¬200 oz/ton) to typically 17 g/t (0.5 oz/ton). Zinc precipitation is used to recover the gold from the pregnant solution. After a water wash, the stripped carbon is transferred to acid wash or to the kiln feed tank for reactivation. All strip lots are acid washed in 3.0% HC1 and all stripped carbon passes through the kiln for thermal reactivation. Then the carbon is quenched, sized and stored in tanks or bins for transferral to CIP or to the carbon columns. Loaded carbon from the dump leach circuit is treated in a circuit consisting of five carbon columns which are parallel to the mill circuit. No distinction is made between the mill or dump leach carbon once the gold has been stripped from them. CARBON FINES HANDLING Once the carbon has been transferred from the carbon columns, every effort is made to minimize carbon attrition and to recover the carbon fines that have been generated in the process. Wemco Hidrostall pumps are used for transferring all carbon in

Jan 1, 1990

By João Paulo Melo Silva

No beneficiamento de itabiritos pobres (%Fe˜44,0) um dos principais desafios para as usinas de tratamento é a produção de concentrado dentro das especificações de qualidade e com menor custo. Nas usinas de beneficiamento a moagem é a operação unitária com o maior custo. Além disso, a moagem secundária é a operação unitária na qual a granulometria do concentrado é adequada às especificações para a etapa de flotação cleaner e para o transporte em mineroduto. Dessa forma, o aumento da eficiência energética no circuito de remoagem permite reduzir os custos e aumentar a eficiência do circuito de flotação cleaner. Amostragens de rotina e testes de bancada realizados com amostras coletadas no concentrador I indicaram oportunidade de aumentar a eficiência energética (kWh/t) da remoagem e reduzir a granulometria na alimentação da flotação. Com esse objetivo, foram realizadas alterações no circuito de remoagem do pré-concentrado da flotação mecânica do concentrador I da Samarco. Essas alterações consistiram em moer todo o pré-concentrado em circuito fechado reverso e não mais em dois estágios, sendo um em circuito aberto e outro em circuito fechado. Essas alterações realizadas no circuito permitiram aumentar a eficiência energética do circuito de remoagem, reduzir o consumo energético em 9,3% e adequar as granulometria e grau de liberação para a etapa subsequente de flotação.

Aug 16, 2017

By D. F. Hewett

ALTHOUGH most persons will agree that an individual or a nation can profit from the experience of other individuals or nations, there is always room for debate over the degree of similarity of their past and present conditions and of their future problems. Noting the increasing interest that Americans are showing in our mineral problems, I have felt that we could profit from reviews of the experiences in mineral exploitation acquired by the industrial nations of Europe. Whether we can learn much from Europe's experience in exploiting such minerals as petroleum may be debatable, but certainly, with a record of metal production extending back nearly 3000 years, Europe should hold much of value for America. A trip to Europe in 1926 permitted me to visit 28 mining districts, of which about half are now or have been in times past outstanding sources of several metals. The districts range from England to Greece and from Spain to Poland. To summarize briefly my impressions of these mining districts, as well as such reactions to the thought and life of Europe as so short a visit permits, I shall only venture the opinion that Americans can review with great profit the ideas and actions of Europeans, with regard not only to the production of metals but to many expressions of life. I believe that America has made and is making new contributions to the art of living, as well as to the arts of mining and metallurgy, but in so far as Europe is and has been a laboratory of economic, social and political experiments, the results she has attained deserve the thoughtful attention of America. I have come to believe that many of the problems that harass Europe lie in our path not far ahead. I have therefore hoped that a review of metal production in Europe in the light of its geologic, economic and political background may -serve to clear our vision with regard to our own metal production.

Jan 1, 1929

By Ronald T. Mayerle

In 1986, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied a 20,500-acre part of the 104,085-acre Rincon Wilderness Study Area (OR-002-082) in order to evaluate its identified mineral resources. The wilderness study area is located in Harney County, OR, about 12 miles west from Fields. No mineral resources were identified within the study area. A literature search found no records of mining or minerals exploration, nor did a ground search find any evidence of mining-related activity. Of seven alluvial samples taken from the major drainages of the study area, all were barren except one. This sample, taken from a dry streambed along the southern boundary, contained $0.07 gold per cubic yard; however, this small amount of gold is of no economic significance, and the source is probably outside the study area. The Pueblo-Steens mining district extends to within 4 miles east of the study area. No evidence of geological environments similar to those that were responsible for the formation of resources or occurrences of metals and nonmetals within the district is known within the study area.

Jan 1, 1987

By W. D. Robertson

A considerable quantity of experimental data is available on the effect of time, temperature, work-hardening and composition on the mechanical properties and corrosion resistance of aluminum alloys. There is, however, little unity of purpose or generality in most of the studies and, because the number of variables is large, the results often are not applicable to the problems that arise in practice. Furthermore, the customary expression of the effect of different variables as separate curves or as three-dimensional diagrams with time, temperature and the dependent variables as coordinates, renders the task of selecting the optimum time and temperature of precipitation treatment, with respect to their simultaneous but unequal etfect on the various properties, exceedingly difficult. The introduction of precipitation treatments to raise the yield strength of 24s-type alloys has created a need for a method of correlating and summarizing the effect of time and temperature on the mechanical properties and susceptibility to inter-crystalline corrosion. Correlation is particularly desirable because the choice of time and temperature is of necessity a compromise to achieve the best possible combination of properties, and the optimum conditions cannot he accurately specified unless the data are in a form in which the alternatives can be readily compared. Therefore, the work described here was undertaken to find a common relationship that would be capable of expressing the effect of precipitation time and temperature on the various properties and by means of which the relative effects could be correlated and their interpretation facilitated. Review of Previous Work In connection with an investigation of the interrelation of age-hardening and creep performance of nickel-silicon-copper alloys, Jenkins and Bucknalll demonstrated that the time required to attain maximum hardness and tensile strength could be expressed by a relationship of the form: t = K • io"^ (i) where t is the time in hours and T the temperature of aging, expressed in degrees absolute, and m and K are constants. They also pointed out that this expression is analogous to that which describes the change of the diffusion coefficient D with temperature; namely, D = Ae-~/m (2) Later, Cohen used this relationship in studies of the mechanism of age-hardening of a silver.rich copper alloyZ and of duralumin.3

Jan 1, 1946

By W. D. Robertson

A considerable quantity of experimental data is available on the effect of time, temperature, work-hardening and composition on the mechanical properties and corrosion resistance of aluminum alloys. There is, however, little unity of purpose or generality in most of the studies and, because the number of variables is large, the results often are not applicable to the problems that arise in practice. Furthermore, the customary expression of the effect of different variables as separate curves or as three-dimensional diagrams with time, temperature and the dependent variables as coordinates, renders the task of selecting the optimum time and temperature of precipitation treatment, with respect to their simultaneous but unequal etfect on the various properties, exceedingly difficult. The introduction of precipitation treatments to raise the yield strength of 24s-type alloys has created a need for a method of correlating and summarizing the effect of time and temperature on the mechanical properties and susceptibility to inter-crystalline corrosion. Correlation is particularly desirable because the choice of time and temperature is of necessity a compromise to achieve the best possible combination of properties, and the optimum conditions cannot he accurately specified unless the data are in a form in which the alternatives can be readily compared. Therefore, the work described here was undertaken to find a common relationship that would be capable of expressing the effect of precipitation time and temperature on the various properties and by means of which the relative effects could be correlated and their interpretation facilitated. Review of Previous Work In connection with an investigation of the interrelation of age-hardening and creep performance of nickel-silicon-copper alloys, Jenkins and Bucknalll demonstrated that the time required to attain maximum hardness and tensile strength could be expressed by a relationship of the form: t = K • io"^ (i) where t is the time in hours and T the temperature of aging, expressed in degrees absolute, and m and K are constants. They also pointed out that this expression is analogous to that which describes the change of the diffusion coefficient D with temperature; namely, D = Ae-~/m (2) Later, Cohen used this relationship in studies of the mechanism of age-hardening of a silver.rich copper alloyZ and of duralumin.3

Jan 1, 1946

By Lucien P. Weber

Over the last few years, increased customer demands as well as strong competition from substitute materials have accelerated the development of advanced technologies to improve both the performance and the cost-effectiveness of steel H-piles. On the material side, the development of an in-line heat treatment, combined with the most advanced steelmaking and rolling techniques, allowed to create a new generation of high-strength low-alloy steel grades, called HISTAR, achieving yield points up to 500 MPa (~72 ksi) and yet maintaining excellent weldability properties thanks to a low carbon equivalent. The topic of this paper is to illustrate the performance of H-bearing piles in HISTAR steel grades. In 1989, a major test program was started at different locations in Hong Kong, which is renowned for its difficult soil and severe driving conditions. After the successful completion of these tests, the HISTAR bearing piles were accepted by the local building authorities. Thanks to their cost-effectiveness, the HISTAR bearing piles have subsequently been used with great success in areas with appropriate soil conditions, especially in Asia and more recently in Europe.

Jan 1, 1997

By A. F. Banks

"Potash processing has much in common in terms of unit operations and plant operating strategy with other mineral processing plants. As it is a rather large topic the processes will be broad brushed to give you some background and then I will go into a little detail on the things we do in the Cominco plant that may be of interest to the group as a whole. In particular the centrallized computer control system and associated instrumentation and the operator training programs will be covered as well as the mill fire, something that could happen in any plant. THE ORE AND PRODUCTSThere are differences in potash ores as you would expect. It is my intention to deal with the ores processed in the Saskatoon area. These are mined from the beds in the Patience Lake Member and have a mineralogical description as follows:Sylvite (Potassium Chloride) 40%Halite (Sodium Chloride) 55%Insolubles (Slimes) 5%A number of products are made from this ore. It is characteristic of a potash plant that you put as much effort into grading and converting the sylvite to meet market requirements as you do in recovering it."

Jan 1, 1976

By Robert Stefanko

The growing demand for energy during the post World War I and World War II periods has prompted underground coal production to increase rapidly. This has been met primarily by mine mechanization, resulting in the development and application of new mining machine types. Correspondingly, the total connected horsepower of each machine as well as the number employed has enlarged rapidly since 1950. (2,3,9,14,16,17) Electrical consumption for each mine has also grown. In the early years of mining electrical applications, only d-c power was utilized underground. Yet, d-c machine limitations were soon realized, and many a-c systems were substituted to permit economic and efficient utilization of a-c distribution and motors. Due to the attractive torque characteristics, ease of distribution and speed control, several traction applications have continued to be powered by d-c motors. The result has been the now prevalent use of mixed a-c/d-c mine power. However, augmented electrical power employment seems to have added to underground coal mining electrical accidents.

Jan 1, 1974

By Spencee L. Willett

A sand and gravel deposit exists in the Wildrose Canyon Wilderness Study Area (WSA), Out it is limited to local use because of the distance from major markets and resulting high transportation costs. The WSA has no identified metallic minerals, oil, gas or other energy related deposits. INTRODUCTION The WSA encompasses 17,366 acres (7,028 ha) in the Panamint Range, Inyo County, California. Access to the area is by State Route 190, approximately 45 miles (72.4 km) east of Lone Pine, California and 16 miles (26 km) southwest of Stovepipe Wells, California (fig. 1).

Jan 1, 1983

By G. S. Brooks

WITH the gradual depletion of the natural-gas pools of the Kansas district, together with the uncertainty of further cheap fuel developments, some. of the western zinc companies turned to the coal fields, attracted by their permanency and the 'success of the Matthiessen & Hegeler Co. and the Illinois Zinc Co. Being then confronted with the problem of using a relatively high-priced fuel, although the ultimate' supply was very great, the fuel economies of the kilns and furnaces became of far more importance, and the more modern equipments, as a result, embodied distinct gads in this phase of the business. In addition, there have been some pronounced advances in the actual making of gas from these coals. Increased efficiency in gas making has contributed its share to lowering costs and those plants located in the higher priced fuel districts have probably been obliged to study these economies somewhat more closely. Naturally, many beneficial changes have resulted in both practice and apparatus in these sections. On, certain western coals, for instance, the actual saving in fuel consumption has been 50 per cent. By this is meant that, where about 1.75 tons were burned to smelt 1 ton of oxidized ore, 0.7 to 0.9 ton is now required. While comparisons by W. R. Ingalls1 of fuel economies in smelting in this country and Germany before the war may, in general, be correct, they do not appear to-do justice to the more progressive. American practice. It is doubtful whether German plants were substantially bettering these fuel ratios. Data furnished by Bender and Frams do not afford records averaging less than 0.9 ton coal per ton ore on materials from 40 per cent. to 50 per cent. zinc.

Jan 9, 1919

By M. Ramulu, A. Raina, A. Chakraborty, Jethwa Choudhury, Dudhankar

Application of digital image analysis technique for assessment of blast fragmentation is gaining grounds in India, very recently. Central Mining Research Institute, India made its maiden attempt to optimize blast design based on fragmentation assessment of one of the biggest opencast mines of Singareni Collieries Company Limited, India. Indigenously developed photoanalysis software called ‘FRAGALYST’ was used for measurement of blast fragmentation A series of trial blasts were carried out in overburden benches with ongoing blast parameters and pictures of muck pile were taken by video camera for image analysis. Cycle time study of loaders and dumpers was done to determine machinery performance for each and every blast. Optimization of pre-blast parameters like specific charge, specific drilling and post-blast results like shovel cycle time and dumper cycle time, was done to determine optimum range of fragmentation. Interpreting the mean fragment size (K50) obtained by image analysis the blast design parameters were modified.

Jan 1, 2001

By Keiichi Fujita, Katsumoto Ueda, Hiroshi Nakauchi, Naohiko Okumura

INTRODUCTION This paper presents (1) modified slipform system which was employed for simultaneous concrete placement for permanent lining and Instruction of a partition wall in the execution of a ventilation shaft 620m deep, and (2) current shaft sinking techniques which have been applicable and efficient for the subsurface conditions in Japan. MODIFIED SLIPFORM SYSTEM FOR PERMANENT LINING OF VERTICAL SHAFT General Information This paragraph deals with rapid construction by using modified slipform system for the permanent concrete lining and a partition wall of ventilation shaft, which has inside diameter of 620m and depth of 620m, of Enasan Highway Tunnel. The general feature of the shaft is illustrated in Fig. 1 and standard section of the shaft is illustrated in Fig. 2. The geological condition surrounding the shaft is mainly of ryolite and surface is of talus, but as a whole, they are rather weak and weathered rocks with faults, fissures and clay seams. 220mm borehole for the geological investigation was used as a drainage hole, predicting the amount of water inflow into the shaft to be 10t/min. The shaft was executed mainly by means of the conventional short step sinking method of 1.2m lift, employing temporary headframe and hoists. For each lift, 40 to 50cm thick temporary concrete lining was used. About 28,600m3 of rocks were excavated and

Jan 1, 1979

By M. P. Hay

"For a model to be successful it must address the concerns and needs of a target audience. Further, the model must demonstrate the same patterns of behaviour as the real system, and need only be complex enough to meet this objective. If the model is too complex it can become unusable to those who need it most.With this in mind, SUPASIM has been developed for the practical metallurgist requiring only laboratory flotation rate data as input. Some 35+ successful plant simulations have been completed since 1985. The approach of SUPASIM is to characterise an ore, organise information in an understandable way and add structure to the complex flotation situation and hence support the metallurgist to interpret the relationship between variables and optimise the flotation process.The paper describes the basis on which the model was developed and sets out to provide an insight into interpreting laboratory flotation kinetics and their physical meaning in a production plant and the influence floatable gangue has on float performance and plant design. A case study illustrates how the ratio of slow floating mineral to gangue can influence circuit design and improve recovery on a plant scale.INTRODUCTIONThere is an enormous amount of useful data in the results of a laboratory scale rate test. Each variable of fraction and rate, for mineral, metal and gangue has a physical meaning in the plant. The link between float kinetics and the plant in respect of recovery, grade, pulp density, pulp flowrate, residence time, number of stages of cleaning and circuit configuration has been established by the author in the process of developing SUPASIM."

Jan 1, 2005

By Hemang Desai

A damaged outlet pipe beneath Lenihan Dam has restricted reservoir discharges, severely constraining the owner?s groundwater recharge program. The solution, a new outlet pipeline through the dam?s right abutment, includes an approximately12.2-m-deep (40-ft-deep) shaft and 618.7-m-long, 4.3-m-diameter (2,030-ft long, 14-ft-diameter) tunnel mined in Franciscan melange composed of hard blocks of rock and soft clayey matrix. Alternating road header with drill and blast operations and using steel ribs and shotcrete have proven a flexible combination for handling the variable ground conditions. Excavating the shaft and connecting it to the tunnel require lowering the reservoir for five months, during which time careful construction sequencing and use of a tunnel plug eliminate the risk of an uncontrolled discharge.

By S. S. Peng

In dealing with the mining engineering problems, the traditional approaches of laboratory experimental simulations and/or analytical solutions are not very effective. Mainly because the field problems are too complex to be solved with a few simplified assumptions. Conversely it is also true that the experimental and analytical/ numerical models currently available are far from being able to model the actual cases. Under such conditions, the most effective mean of research into mining engineering problems is to combine the mine (field) investigations with laboratory and / or analytical modelings. It is with this concept in mind this research was initiated in 1973. 'The field investigations which began in the fall of 1978 consisted of mainly visiting the mines where surface subsidence monitorings had been or were being monitored and/or surface structural changes had occurred. From such visits, subsidence data were collected. A quick analysis of those data provided preliminary understandings of the characteristics of the surface subsidence parameters in the regions (1-5). Using those date, models of various types are being developed for subsidence prediction / control. So far, a total of 44 longwall subsidence profiles in 22 longwall panels and 10 room-and-pillar profiles in 5 room and-pillar sections have been collected. This paper summarizes the combined results published previously (1-5) and present the preliminary results of the predictive models developed.

Jan 1, 1982

By Stanislatv Pawlowski

New, large sulphur deposits were discovered in Poland in 1953, the result of investigations by the National Geological Institute. All deposits occur in a widespread Miocene evaporite unit in the Carpathian foredeep. The gypsum underlying impermeable Sarmatian clays was altered to limestone and native sulphur where penetrated by hydrocarbons and bacteria. All deposits occur in Miocene structural uplifts. The early determination of the genesis of the sulphur deposits and their occurrence in elevated blocks led to an exploration program that successfully located new deposits.

Jan 1, 1978

By A. F. Baker

Tests were conducted in commercial foundries to determine the suitability of calcined anthracite as a cupola fuel. The calcined anthracite performed satisfactorily at two of the three foundries where iron-melting tests were conducted. Performance at the third installation was unsatisfactory because metal temperatures deviated widely and, in general, were lower than is desirable for the type of castings being made.

Jan 1, 1963

By Fletcher G

This paper will outline the design process, and the constmction and rehabilitation techniques proposed for the external waste dumps associated with the mining of the Wolfang Basin coal measures.The basin is located to the north of Clermont and immediately west of the Bowen Basin in Central Queensland, Australia. Development of the Clermont Coal Mine is planned for the mid-1990s after adequate sales commitments are obtained to allow the project to proceed.

Jan 1, 1992

By J. E. House, C. J. Lewis

In the solvent extraction process, also referred to as liquid-liquid extraction, the clarified uranium-pregnant sulfuric acid leach solution is contacted with an organic extractant dispersed in kerosene; the uranium enters the organic phase and associates itself with the organic extractants. Simultaneously an-ions or cations, as the case may be, leave the organic extractant phase and enter the aqueous phase. The two phases are then allowed to separate by virtue of their immiscibility. Based on the data available, a generalized procedure for the recovery of molybdenum from the sodium carbonate scrub liquor of acid leach uranium mills using secondary and tertiary amine extractants is presented, as is another generalized procedure for the recovery of molybdenum from the bleed stream of alkaline leach uranium mill circuits. Such economic appraisal as can be made at this stage of the development is also indicated. Molybdenum occurs in most uranium ores. Whether the uranium is solubilized by the acid leach route or by the alkaline leach process, some of the molybdenum present in the ore is solubilized along with the uranium. Molybdenum in uranium mill pregant solutions may cause processing difficulties, among which may be mentioned the poisoning of resins, the precipitation of organo-molybdenum complexes, or the build-up of molybdenum in recycle streams. While the uranium milling industry has been successful in applying measures to overcome the problems arising from the presence of molybdenum in the circuits, such measures nevertheless add to the cost of producing uranium yellow cake concentrate. Table I shows the analysis of typical uranium pregnant leach solutions. Uranium recovery by solvent extraction is presently practiced only in conjunction with acid leach circuits, and it may be noted that of about 16,000 tons of uranium ore daily processed by sulfuric acid leach, more than half of this tonnage follows the solvent extraction route. Uranium mills leaching ore with sodium carbonate-sodium bicarbonate solution (the so-called alkaline leach circuit) do not use solvent extraction. In this case the uranium pregnant solution is sufficiently pure to permit the direct precipitation of uranium concentrate with subsequent recycle of the alkaline leach solution. While solvent extraction procedures may be developed which are economically attractive for the alkaline leach uranium process, this has so far not been the case. The earlier uranium mill solvent extraction circuits used organo-phosphate extraction reagents, among which di-2-ethylhexyl phosphoric acid was popular. It should be borne in mind that uranium in its sulfuric acid leach solution exists in an equilibrium involving uranium in both anion and cation forms: uo + 2S0 = [uo2(so4)2] For this reason uranium may be extracted by either cation extractors or anion extractors and this is likewise true of molybdenum. However, the organo-phosphate extractants also load ferric iron which is usually present in the uranium acid leach solution. For this reason, it is necessary to reduce this solution substantially to the ferrous state ahead of solvent extraction using organo-phosphate reagents. The amines, being anion extractors, selectively reject iron and thus render the iron reduction step unnecessary. In the solvent extraction process, also referred to as liquid-liquid extraction, the clarified uranium-

Jan 1, 1961