Search Documents

By David A. Milligan, William Cobb

2.1 INTRODUCTION This chapter provides the reader with a sense of how a heap leach project may make an orderly, and hopefully non-traumatic, transition from discovery or acquisition to project construction. In making this transition a project can pass through several project development phases (i.e. ore definition and delineation, conceptual engineering, detailed engineering, and ultimately on to project construction and operation). "Go" or "no go" decisions may occur at any point in each of these phases. The transition from ore definition to detailed engineering should be accomplished via a well thought out program of interdisciplinary studies and an integrated, interdisciplinary project team. This chapter also describes, in general terms, a "roadmap" approach to the project evaluation process that must occur as project planning and development progress. It is the experience of the authors, as well as a myriad of companies who have been through the heap leach project development process, that a systematic approach will save many headaches, and many dollars. In fact, it is safe to say that a project with no formalized system of "objectives setting" and "milestone charting" may well flounder along the way, even if an economic ore body exists. Many papers and technical articles have been written about various aspects of mineral resource appraisal, economic evaluation, and mine development. Most of these invoke the same general philosophy of a systematic approach to project evaluation and development, although methods cited for attaining goals are quite variable. This is undoubtedly appropriate, given the fact that there is great variation in approach to project development (e.g., climatic considerations, ore body size and physical ore characteristics, permitting constraints, etc.). For the purposes of this chapter, two primary sources of information have been used to highlight the "road map" approach previously alluded to. These sources are cited throughout the text as Mackenzie (1980) and Snow and Michel s (1986). A brief summary of each of these sources is provided below: Brian GJ. Mackenzie of Queens University (Mackenzie, 1980) has developed a wealth of information concerning project development topics. Much of this information is synthesized in his notes for a short course entitled : "Mineral Exploration Planning and Economic

Jan 1, 1988

By Gerd A. Schroth

For many years, the automatic preparation of samples prior to elemental analyses has become quite common in several indus­tries, including aluminum, cement, non-ferrous and steel. Modem automatic preparation of powdery, granular or metallic samples which initially emerged as leading edge technology, has become state of the art and a proven technology.

Jan 1, 1996

By J. B. Hiskey

The principle oxide minerals of molybdenum are wulfenite (PbMoO4), ferrimolybdite (Fe2(MOO 4)3.nH2O), powellite (CaMoO4), and ilsemannite (Mo304). Wulfenite is found in Arizona, New Mexico, Nevada, Utah, California, and Montana. It is also found in the states of Sonora and Chihuahua, Mexico. Prior to 1915 wulfenite ores were the primary source of molybdenum. The solubility of wulfenite in hot sodium sulfide was first noted by Bonardi(1) during attempts to sulfidize wulfenite material prior to flotation. He identified lead sulfide and soluble sodium molybdate as reaction products. Bacon (2) sulfidized wulfenite in preparation for flotation and by X-ray analysis found the reaction product to be lead sulfide. Holmes(3) made an extensive investigation of the extraction of molybdenum from wulfenite concentrates by leaching. Nearly 100% molybdenum extraction was possible from -100 mesh samples leached for 15 min with 10% sodium sulfide solution at room temperature. Molybdenum extraction from -100 mesh samples after leaching 30 min at a temperature of 45°C using 2, 4, and 6% sodium sulfide was about 32, 79, and 98% respectively. The extraction showed little sensitivity to time, temperature, or particle size using 10" sodium sulfide solution.

Jan 1, 1976

By Samantha Smith

Nautilus is completing the world's first environmental impact assessment (EIA) of seafloor mineral extraction and Nautilus has gained extensive experience conducting environmental studies in subsea environments. Nautilus is currently working on the Solwara 1 Project in the Bismarck Sea, Papua New Guinea, where high grade seafloor massive sulfide deposits lie at ~1600 m water depth. Conducting an EIA in the deep sea presents some interesting and exciting challenges. Seafloor studies commenced in December 2005 using a remotely operated vehicle (ROV) fitted out with highly specialized scientific equipment to conduct water quality, sediment, biological and oceanographic studies. During 2007 and 2008, Nautilus launched two two 30-day ROV programs dedicated to environmental baseline studies and during this campaign, over 550 biological, sediment and water samples were collected and over 20,000 seafloor observations were logged. On board specialists included an international team of experts in the field of deep sea marine science. Collaboration between industry and scientific research institutions allows data to be collected for the EIA but also provides an extraordinary opportunity for researchers to access sites that might otherwise remain unobtainable to science. This presentation will review the studies conducted as part of this exciting project. Keywords: Seafloor Massive Sulfides, Environmental Impact Assessment

Jan 1, 2008

By Hiromu Kusakawa, Tetsuo Kanematsu

INTRODUCTION In urbanized area with heavy street traffic and with environmental requirements to lessen construction noise and vibration, the cut-and-cover is not always a feasible method to build a small diameter tunnel for sewage, water or other utilities. That is where the use of the shield machine to bore such a small diameter tunnel should be considered as a more acceptable alternative. Although the shield machine of this type should be small enough to meet specific requirements for a given tunnel, it should be big enough to provide some working space inside of the tunnel. Recently, we have successfully developed the fully mechanized small diameter tunneling method which enables us to bore a tunnel as small as 600mm in finished diameter. This paper discusses the concept of this newly developed method, including a case history where sewage tunnels of 800mm finished diameter were constructed by using this method. OUTLINE OF METHOD Developed from the original slurry shield pipe-jacking tunneling method, this method is highly automated so that all operations inside of the tunnel can be remotely controlled. Various data including the advance rate, position and inclination of the shield are transmitted to the central control room outside of the tunnel and monitored by the CCTV and the instrument panel at all times to

Jan 1, 1981

By J. A. Siekmeier

The thickness of the laminated beam modeled in this study is based on bridging potential and TDR measurements. The laminated beam stiffness is based on the effective stiffness of an equivalent transformed section. The maximum deflection of this near-surface laminated beam is compared with the maximum measured surface subsidence. The spreadsheet provides a rational technique to graphically display the character of the overburden and potentially allows prediction of a subsidence factor based on boring logs and the proposed mine plan. The U.S. Department of the Interior, Bureau of Mines (Bureau), utilizes a commercially available computer spreadsheet program in combination with a modified version of Bieniawski's Rock Mass Rating (RMR) system to characterize the geology overlying high extraction coal mines. The spreadsheet program calculates a RMR for each bed based on the lithology, thickness, and engineering properties, which are determined from boring logs and laboratory tests. Once the RMR is calculated the spreadsheet has two major functions. First, the spreadsheet calculates values used to graphically represent the character of each individual bed in the overburden. It calculates an in situ deformation modulus using an empirical rela¬tionship between the modulus and the RMR and then uses this effective modulus along with additional parameters that are based on mine geometry to calculate the bending stiffness and bridging potential for each bed. Second, the spreadsheet creates a transformed section that allows groups of beds to be modeled as an elastic beam. It then calculates a bridging potential for the entire rock mass. The bridging potential of the rock mass is a single value that takes into account both the geology of the overburden and the geometry of the mine. It seems reasonable that there would be a strong correlation between the bridging potential, the overburden response to high extraction mining, and the subsidence ratio. The results presented in this paper focus on the relationship between the bridging potential of individual beds and the deformation measured using Time Domain Reflectometry (TOR). Subsurface displacements measured over seven high extraction coal mines in southern Illinois were correlated with the bed stiffness and bridging potential profiles. Based on these correlations it was evident that the process of caving and subsidence over these high extraction mines involved momentary bridging by individual beds or groups of beds and the ultimate development of a laminated beam near the surface.

Jan 1, 1986

By William E. Lamont

As a part of the Department of the Interior's rutile and titaniferous materials development program conducted under the Defense Production Act, the Bureau of Mines investigated the potential for producing national stockpile grade rutile from plant products of phosphate beneficiation plants operating in the central Florida pebble phosphate district. The potential for producing ilmenite, zircon, and monazite concentrates from the plant products was also investigated. Results of these studies indicated that 3,000 to 6,000 tons of rutile, 28,000 to 55,000 tons of ilmenite, 9,000 to 19,000 tons of zircon, and 400 to 800 tons of monazite passed through the plant circuits annually. All of these minerals are presently being sent to waste ponds. Beneficiation of a bulk heavy mineral concentrate separated from the amine flotation tailing (froth product) of numerous plants in the district showed that it was possible to produce a rutile concentrate containing over 94 percent Ti02. Additional studies showed that over 70 percent of the Ti02 in the rutile concentrate could be isolated in a product containing 98.0 percent Ti02. The studies also showed that it was possible to produce ilmenite concentrates containing 63 percent Ti02, zircon concen¬trates containing 65 percent Zr02, monazite concentrates containing over 85 percent monazite [(Ce,La,Y,Th) (P04)], and xenotime concentrates containing over 35 percent xenotime (YPO4).

Jan 1, 1969

By A. G. Oppegaard

Most iron ores treated by the R-N direct reduction process yield metallic iron products considerably lower in titanium, manganese, and chromium oxides and alkaline metal sulfates/sulfides than were contained in the original ores. These metallic iron products are suitable as feed stock for the open hearth and electric steel-making furnaces. The elements which are rejected in part are acceptable in the product since the product is designed to by-pass the blast furnace. R-N reduction conditions (PCO+H2-1 atmosphere, 1830° to 2150° F.) are adjusted for each ore. The iron ore which is reduced to 90 to 95 percent metallic iron is then subjected to the conventional beneficiation techniques. Under these conditions, 55 to 80 percent of titanium oxides, 75 to 95 percent of manganese oxides, 60 to 90 percent of chromium oxides and up to 97 percent of alkaline metal sulfates contained in the ore are rejected with the gangue to the non- magnetic tailings. The metallic iron products illustrated in this work contained 89 to 96 percent total iron, one to five percent TiO2, 0.2 to one percent MnO, 0.3 to 1.6 percent Cr2O3 and/or up to one percent alkaline metal sulfide. Usually only one of these components was present. Recoveries ranged from 80 to 96 percent of the iron in ore.

Jan 1, 1958

By Peter V. Avotins

During last year's AIME meeting in New Orleans, Deepak Malhotra and I were discussing some of the topics that would be presented in this Symposium. It seemed appropriate that along with papers on specific reagent and flocculant types, we should address research management aspects of new product development. This development is a long, arduous task that requires a significant technical and fiscal commitment by the chemical company and potential users. A flow chart depicting the research process is shown in Figure 1. The sequence of events are plotted on an undefined time line. Our experience has shown that it takes 3-5 years to complete a typical reagent development project. A new project starts with an idea of how to do something better. The ideas range from relatively simple product modifications to opportunities created by technological change. An example of this is the use of flocculants in tailings operations to close the water recycle loop. The change was brought about by the need to conserve water and comply with environmental statutes. The result was the development and wide-spread use of synthetic polymers to help in solid-liquid separation. More recently the ups and downs of oil prices have led to development of coal water slurries as an alternative to fuel oil. The slurries contain high levels of chemicals (up to 3%) to insure proper stability and burn characteristics. There are technical changes under way right now that may lead to ideas for other new products. One exciting source of new technology is the ability to manipulate genetic material of microbes to select for specific capabilities. This has evolved by leaps and bounds over the past 5 years. Biologically assisted leaching and removal of wastewater impurities are two possible end uses. I'm sure that there are many others. The ideas can originate anywhere and are often half-baked at first, but to lead to new products they must be refined to provide project definition and eventually a research plan. A chemical ,development project cannot be started without approval to commit the company's resources. The internal selling job is often very difficult. The company must see clear financial benefits in order to launch efforts that may not pay off for many years. It is critical to project the total market, profitability, eventual market share, and timing of introduction of the new product. There is much uncertainty in this and the research manager is often skating on thin ice to retain his credibility. Once we obtain support from upper management, the research team is assembled to start the project. The teams generally consist of organic chemists, research metallurgists, and technicians. They have access to analytical scientists and technicians for surface and analytical chemistry. The projects are often augmented by help from university staff and consultants. This is particularly true where there is a need to develop fundamental understanding of the technology in addition to synthesis of chemicals. The project now proceeds along two lines. First, there is an emphasis on understanding the prior art. Extensive literature and patent searches are undertaken to provide research leads and to keep from "reinventing the wheel" and infringing on someone else's patent. The scientists and technologists are qualified to conduct computer-assisted library searches. This process usually uncovers 80-90% of the relevant information. The remainder is very much harder to get and requires the help of professional library search staff with scientific backgrounds. Along with literature searching, the team begins synthesis of new compounds. These are screened by use of techniques such as microflotation or filtration in a Buchner funnel. The scientists are looking for the direction of response as they modify structural features . Inevitably, a large number of candidates reach the next stage, a laboratory bench test. At this point it is possible to set up a research plan and use project management techniques to monitor progress. The bench tests are conducted in larger equipment, usually requiring 100-1000 grams of test substrate. Typical laboratory flotation tests are run in Denver or Wemco cells.

Jan 1, 1986

By Morteza Gharouni Nik

Flexible Dilatometer Test (FDT) is one of the in-situ test methods for determining the deformational characteristics of rock masses. In this study, several dilatometer tests have been conducted in different geotechnical phases of site investigations by means of two types of FDTs. The purpose of this paper is comparison of the performance of these two types of dilatometers and analysis of the differences in the results of the tests.

Jan 1, 2008

By C. Haycocks

The Appalachian coal fields contain many mineable contiguously placed coal seams. Selection of the mining sequence for these seams, historically and currently, is based primarily on considerations of seam ownership, availability and economics. Mining any seam can seriously affect subsequent operations in coal seams both above and below the one being mined. The effect is often detrimental to recovery costs and safety of mining in the subsequent seams. The purpose of this paper is to examine the conditions that can develop in an underlying seam due to stress concentrations that can occur below pillars or abutment zones in an overlying seam, and suggest guidelines for avoiding them. This situation most commonly occurs when the overlying seam is mined first, although simultaneous and subsequent mining of the upper seam can also produce such effects. Other interaction phenomena resulting from subsidence or arching will not be considered here. The methodology used in this research utilized both computer and body loaded photoelastic models to study the interaction mechanisms. Field studies are used in both interpretation and analysis of the results. Numerous examples of load transfer from upper workings exist in all parts of the world and many of these have been incorporated into this work. Such interaction problems are quite common and likely to be an ever increasing occurrence as mining activities in old seams are completed and new seams opened up.

Jan 1, 1982

By A. Iordanidis

Ieropigi Fe-Ni deposit is located in northern Greece, in Kastoria?s prefecture near Albania?s borders. A laterite profile exposed by opencast mining and placed near the basement of the mine was chosen for sampling. Ten samples, representing ?pure? Fe-Ni ore, ophiolite-bedrock, ?red? ophiolite and ?enriched? ophiolite were collected, based on macroscopic observation. The samples were analysed by X-Ray powder Diffraction (XRD) for the determination of the mineral phases. Iron and Nickel concentrations of the same samples were also determined by X-Ray Fluorescence (XRF) methodology. The Fe-Ni ore samples consists predomi-nantly of hematite, goethite, chrysotile (serpentine), saponite and quartz. ?Red? ophiolite samples consists mainly of chrysotile, hematite, quartz, calcite and small amounts of paragonite and goethite. Bedrock and ?enriched ophiolite samples are comprised of chrysotile, hematite, calcite, quartz, nontronite, paragonite and sepiolite. The Fe content ranges between 13% and 49% in Fe-Ni ore samples and between 7% and 10% in ophiolite samples. The Ni content ranges between 1% and 3% in Fe-Ni ore samples and between 0.3% and 4.5% in ophiolite samples (the higher content is observed in the so-called ?enriched? ophiolite). A correlation between Fe-Ni concentrations and mineral assemblages is being attempted in order to evaluate the nickel-rich mineral phases. It is shown that the nickeliferous minerals are serpentine, hematite, goethite and saponite.

Jan 1, 2006

By H. Dr. Boldt, J. Dr. Henneke

PREFACE In German coal mines the application of tunnel boring machines has become a very effective and economic technique for major development works. After initial trials around 1970 the breakthrough was reached by driving 13 km of road ways on Rheinland and Friedrich Heinrich collieries, using a DEMAG tunnel boring machine of 6 m diameter. INTRODUCTION The coal mines of Rheinland and Friedrich Heinrich are to be found in the West of the Ruhr Area, the largest coal mining area in the Federal Republic of Germany (Table 1). They form part of the Ruhrkohle company. Rheinland coal mines produces 41000 to 43000 t of run-of-mine coal every day, of which 20500 t are usable coal. Friedrich Heinrich has a daily production of 17000 t of run-of-mine coal, 9000 t of which are usable. The coal is worked at depths of 600 to 1100 m in seams 0.6 to 3.0 m thick. The method of mining is longwall, and the machines used are ploughs and shearer loaders. From 1973 to 1980 a programme was put into operation in these two mines to develop and open up the coal field on the 885 m level. A total tunnel length of 20 km was to be driven. After thorough investigations it was decided to employ a full-face tunnel boring machine for

Jan 1, 1981

By Louis M. Schlesinger, Joel F. Hutwelker

A pilot plant was constructed to attrition scrub and deslime North Carolina phosphate ore. A 15.2 cm (6 in.) diameter pilot-scale Linatex Hydrosizer was used for desliming. Four tests were run at a throughput of 2.9 t/hr/m2 (0.30 ton/hr/f t2) and a teeter bed density of 1.12-1.13 g/cm3. The teeter water flow rate was varied to create an upflow velocity ranging from 0.25-0.47 cm/s. (This latter value is equal to the terminal settling velocity of a 200 mesh (74 micron) particle having a density of 2.7 g/cm3.) The recovery of +200 mesh oversize to the sizer underflow was 95%-96%, regardless of the teeter flow rate. The recovery of -200 mesh undersize to the sizer overflow increased from about 90% at 0.25 cm/sec to 100% at 0.47 cm/sec. A metallurgical balance that was conducted for one of the tests showed that less than 2% of the phosphatic value was lost to the overflow. A fifth test was run using an upflow velocity of 0.47 cm/sec; however, the teeter bed density was maintained at 1.05 cm/sec. This change had the effect of reducing the cut point (d50), while maintaining complete slime removal.

Jan 1, 1993

By Yeonuk Choi, Gus Van Weert

cyanide control in effluents is becoming a critical environmental issue for the gold extraction industry. Silver impregnated carbon removes free cyanide effectively to the ppb level from solution in high throughput columns. By re-calcining the cyanide saturated carbon, the impregnated silver is restored to activity and the cyanide destroyed outside the effluent stream. Many gold mills already have an activation kiln on site, which could make retrofit relatively easy.

Jan 1, 1993

By Antonio Jorge de Sousa

In order to compare several mining variants, on the point of view of the variability of the ore quality parameters, a conditional simulation technique is applied to a complex pyrite deposit (FEITAIS orebody, Portugal). Exploitation methods such as cut and fill and sublevel stoping are studied by the a.m. methodology. For each mining variant, it is assessed the influence of several mining operators on the variability of grades.

Jan 1, 1982

By Russell Dittrich

The Kinross DeLamar Mine has been operated for more than 17 years producing precious metals doré from ores, principally silver bearing with associated gold coproducts. In late 1995, the Stone Cabin ore body was commissioned and the site began a phased shift from silver dominance to gold dominance. The Knelson concentrator was selected to remove gold from a portion of the cyclone under- flow stream in the grinding circuit.

Jan 1, 1998

By Jean-Luc Cornet

Advances in conveyor technology over the past decade have enabled the design and erection of very long overland belt conveyors. Such conveyors usually require head and tail drives to lower the belt tension and belt strength required. This paper provides an overview of the problems encountered in controlling the head and tail drives on such conveyors and some of the solutions developed by CDI for several such projects.

Jan 1, 2002

By S. A. Moffatt, S. K. Kawatra, T. C. Eisele

This paper describes the decomposition of bulk samples to fine particles using alkali metal vapors. Basalt, pyrite, alumina, pyrex and quartz glass samples were exposed to sodium vapors at elevated temperatures for different time periods up to 30 hours. Examination of the particles showed that fragmentation occurred preferentially along grain boundaries. Emphasis of this paper is on the theory of the degradation mechanism and the size distribution of the particles produced.

Jan 1, 1992

By Bernie W. Martin

The East Side Access (ESA) project is the largest commuter railroad project ever undertaken in the United States. The purpose of the ESA project is to bring commuters from Long Island into Grand Central Terminal. The program is estimated to cost $4.3billion. The purpose of this paper is to describe the key design elements for the Queens segment, ?re life safety, ventilation and changes to the proposed contract delivery method.

Jan 1, 2003