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By James E. Hoffmann

Oxidative pressure leaching is gradually supplanting other techniques for the decopperizing of slimes. The reasons for this include: much more rapid reactions, more compact equipment, a reduced environmental burden, and perhaps most important, a much lower final copper concentration in the decopperized slimes. This paper will discuss the reactions occurring during decopperization, the acidity and temperatures encountered and the techniques employed for discharging non condensable gasses. A spreadsheet is provided which allows adjusting the operating conditions depending upon raw (undecopperized) slimes composition, solids concentration and lixiviant composition. A typical process equipment flowsheet is provided along with a process narrative.

Jan 1, 2000

By J B. Maughan

Gas and oil seeps have been known in Quebec for more than one hundred years. These occur in three main areas which contain sedimentary rocks with a total thickness estimated to vary from 6,000 to 20,000 feet. The strata in these areas are similar in many respects to those in producing areas of southwestern Ontario and the Appalachian basin, and the prospects for finding and developing commercial reserves of oil and gas in Quebec would therefore also appear to be favourable. Little of the exploratory drilling to date has been con-ducted in a systematic manner, and most of the drilling has utilized improper or inadequate equipment. Many wells have also failed to adequately test and fully evaluate the principal zones of interest. Relatively high drilling costs have hindered systematic exploration; however, with improved portable equipment, it is expected that future wells can be drilled with greater efficiency and at less cost. Most of the mineral rights in Quebec are held by the Provincial Government, and acreage can still be leased in large blocks on favourable terms.

Jan 1, 1964

By L. K. Weaver

Bureau of Mines investigated the progressive impact that petroleum (crude oil and condensate) operations in the Gulf of Mexico have had on onshore operations and the expected effect of increasing activities in this area on future petroleum supplies from domestic sources. The data analyzed include capital expenditures, number of wells drilled, success ratio for exploratory wells, daily production per completion, annual producing rates, and oil reserves. The report compares offshore and onshore data and ascertains trends in petroleum industry operations. Observed data and trends indicate that in the near future Gulf of Mexico development and production will continue to increase relative to total U.S. petroleum activity. By 1975 annual oil and condensate production from the Gulf of Mexico is expected to be in the range of 750 million bbl to 1,150 million bbl, and account for approximately 20 to 30 pct of the estimated total domestic production.

Jan 1, 1969

By Bjarne Ekberg

"The most economical way of dewatering mineral concentrates is to reduce the moisture content in the material mechanically using thickeners and filtration avoiding thermal drying whenever possible. In addition to this, the dewatering process should produce low moisture cake, high quality liquid, consume little energy. As a part of the dewatering process The CERAMEC® capillary filter has been proven to meet these requirements in over 150 installations. The filtration is done by using ceramic filter plates with small pore size. The capillary action in the filter medium secures gas free filtration at good vacuum, and due to the small pore size, filtrate is crystal clean and particle free. The energy consumption is minimal. This paper will discuss results from filters installed at Pyhäsalmi Mine Oy in Finland where the technology was has been used since the late eighties. Results from more recent installations like Los Pelambres in Chile and LKAB in Sweden will also be discussed.INTRODUCTIONThe idea of using capillary action to make dewatering more efficient was invented two decades ago. Ten years later whole filter plants utilizing the new method were delivered to mine concentrators for dewatering of mineral concentrates. Further development of ceramic membrane plates made it possible to meet the requirements in iron ore dewatering. In addition to low cake moisture, high capacity and low energy consumption, there are a lot of environmental advantages in using capillary filtration. One of them is clear filtrate.CAPILLARY FILTRATIONA micro-porous filter material behaves like a large number of narrow capillaries forming a network. When a pressure difference ?P is applied over the wetted, hydrophilic pore with the radius r, the force striving to push the water out of the pore will be ?Ppr2. The force striving to hold the water in the pore will be the vector force 2pr? cosa of the surface tension ? and the cosine contact angle a. Equalling those forces and solving the equation for ?P we get"

Jan 1, 2003

By Maral Papazian Bedian

"Case 2. 100th Street Bus Depot: Elimination of Deep Caissons in Favor of Spread FootingsThe PROJECTThe 100th Street Bus Depot is a new five-story bus terminal for the New York City Metropolitan Transit Authority occupying one city block in Manhattan between 99th and 100th Streets, and between Lexington and Park Avenues. It replaces a former two-story garage, built in the 1890’s and initially used as a trolley-car barn. The new structure is a steelframed building with concrete floors and includes a partial basement near its middle. The easternmost column line with design loads of 10 MN (1,125 tons) is within 1.5 m of the underlying multi-tube Lexington Avenue subway system. To support the new columns along the subway line, the project bid plans had called for 1 m diameter and 17 m deep drilled shafts. The upper 14 m of each unit would have required 50 mm separation from the surrounding rock to prevent stress from being imposed on the roof and walls of the adjacent tunnel. The column loads were thus transferred to below the base of the tunnel and supported by 3 m long sockets in bedrock. The bid documents contained extensive test boring information, which revealed that the project site was underlain by massive Manhattan Mica Schist bedrock within just 3 m below street level. In fact, the Lexington Avenue two-level and multi-tube subway had been tunneled through this rock circa 1910, leaving an about 6 m thick solid roof over the upper-level subway. The NX rock core recovery values were near 100 %, with average RQD of 75 %.The CHANGEThe Bus Depot project was let as a design/build contract with a very aggressive fast-track schedule. Both the pre-bid preliminary design and the subsequent final design by the Contractor’s own hired design engineers relied heavily on very restrictive codes, including unnecessarily conservative approaches to seismic design. Any suggestion for value engineering change was undesirable and was strongly resisted. Yet, objecting against the blind reliance on codes in foundation design, the author questioned the real need for the deep drilled shafts to support the columns along the subway. The unsupported statement that no stresses from the new structure can be imposed on the roof and walls of the adjacent tunnel was not sufficient reason for the drilled-shaft design. Unconvinced that deep shafts were necessary, the author rushed to MTA’s warehouse where many rows of rock core boxes were neatly stacked. Careful inspection and some simple testing of the rock cores with the blows of a geologic hammer gave support to the reservations about the design. Later, as expected, the schist bedrock at this site was found to be hard to very hard with unconfined compressive strength values estimated to range from at least 70 MPa to over 100 MPa (10,000 psi to 15,000 psi). The tensile strength of the rock was assessed to be minimum 5 MPa (750 psi)."

Jan 1, 2003

By R. M. Howe, J. Spotts McDowell

Preparation and Use.—Magnesite is an important refractory in open-hearth, heating, and electric furnaces for steel-making and in many of those employed in the metallurgy of copper and lead. It is sold in the form of brick, finely ground "furnace magnesite" for bricklaying, and dead-burned grains for making and repairing furnace bottoms. The latter are a mixture of granules varying in size from pieces of about 5/8 in. (1.6 cm.) diameter to very fine but sandy particles. Dead-burned magnesite results from calcining the crude or lightly burned mineral at a temperaturc that will not merely drive off practically all the CO2, but will also cause sintering of the particles. During this process the pieces shrink considerably and become hard, dense, and inert to atmospheric moisture and CO2; under-burned material, on the other hand, will hydrate on exposure to the air. A small percentage of ferric oxide seems to be necessary for the production of a satisfactory sinter; from 4.5 to 8 per cent. in the dead-burned grains is considered the most desirable amount. Dolomite has been little used for brickmaking in the United States, but it is prepared for use in the granular condition calcined or "double-burned" and is the principal ingredient of several materials offered for sale under various trade names for refractory purposes. Dolomitic refractories are almost wholly confined to the open-hearth and electric furnaces, where they are used for fettling and as substitutes for magnesite. Much more magnesite and dolomite are used for basic open-hearth steel-making than for all other refractory purposes. The hearth of the furnace is usually built up of magnesite brick and dead-burned grain magnesite so laid that the brick base is protected by a working bottom of the granular material. The latter is sintered into place in layers 1/2 to 1 in: (1.25 to 2.5 cm.) thick to a total depth of 12 to 18 in. (30 to 45 cm.) at the center of the furnace. After each heat, burned dolomite is thrown against the banks as high as it will stick, and all holes in the bottom are Glled. At most plants such holes, at the end of each week, are also carefully filled with dead-burned grain magnesite. For temporary

Jan 1, 1920

By J. Spotts McDowell

Preparation and Use.-Magnesite is an important refractory in open-hearth, heating, and electric furnaces for steel-making and in many of those employed in the metallurgy of copper and lead. It is sold in the form of brick, finely ground "furnace magnesite" for brick-laying, and dead-burned grains for making and repairing furnace bottoms. The latter are a mixture of granules varying in size from pieces of about 5/8 in. (1.6 cm.) diameter to very fine but sandy particles. Dead-burned magnesite results from calcining 'the crude or lightly burned mineral at a temperature that will not merely drive off practically all the CO2, but will also cause sintering of the particles. During this process the pieces shrink considerably and become hard, dense, and inert to atmospheric moisture and C02; under-burned material, on the other hand, will hydrate on exposure to the air. A small percentage of ferric oxide seems to be necessary for the production of a satisfactory sinter; from 4.5 to 8 per cent. in the dead-burned grains is considered the most desirable amount. Dolomite has been little used for brick-making in the United States, but it is prepared for use in the granular condition calcined or "double-burned" and is the principal ingredient of several materials offered for sale under various trade names for refractory purposes. Dolomitic refractories are almost wholly confined to the open-hearth and electric furnaces, where they are used for fettling and as substitutes for magnesite. Much more magnesite and dolomite are used for basic open-hearth steel-making than for all other refractory purposes. The hearth of the furnace is usually built up of magnesite brick and dead-burned grain magnesite so laid that the brick base is protected by a working bottom of the granular material. The latter is sintered into place in layers 1 to 2 in. (2.5 to 5 cm.) thick to a total depth of 12 to 18 in. (30 to 45 cm.) at the center of the furnace. After each heat, burned dolomite is thrown against the banks as high as it will stick, and all holes in the bottom are filled. At most plants such holes, at the end of each week, are also

Jan 2, 1919

By Nikhil Dhawan, Ashwini Kumar, Yogendra Pratap, Himanshu Tanvar

India does not possess any soluble potash reserves and depends completely on imports. In this study, an attempt has been made to recover potash (K) values from the mica sample employing thermal and mechanical routes followed by leaching. Direct leaching of mica in different lixiviants is found to be ineffective with very low K-dissolution (1–5%). Heat treatment with different fluxes, such as NaCl, NaOH, and CaCl2, is carried out and almost 85% K-values are recovered. Mechanical activation of mica and with different calcium additives is carried out to recover potash values. K is recovered in leach solution in the form of soluble salts, such as K2CO3, K2SO4, and KOH, and leach residue consists mainly of calcium-alumino-silicates. Using mechanical activation with flux, it is possible to recover >95% K-values from mica sample. Mechanical activation with calcium-based flux is found sustainable in the recovery of K-values from mica.

By Robert W. Freedman

In the Bureau of Mines study, a filter with a 20-by 20-inch-square cross section was inserted into the exhaust ducting of a 4-stroke-cycle, 90-hp diesel engine, and the efficiency of removal of total particulate was measured gravimetrically as a function of time. Removal efficiencies were close to 90 pct during the main portion of several extended runs employing several combinations of filter beds. Variations in engine load had little effect on collection efficiency. Particle size as measured by a Bureau-developed online instrument centered on 0.07 m based on number count. Removal efficiency increased rather sharply for both larger and smaller particles.

Jan 1, 1979

By M. K. Elmouttie, G. V. Poropat

Mapping of exposed rock walls provides data on geological features such as joints, bedding planes, faults etc critical to the economics and the safety of mine operations. Traditional, manual methods of mapping can be time consuming, error prone and limited in their coverage. New methods have been developed to map exposed faces remotely and safely however the benefits of these methods are only fully realised when exposed structures can be quickly and easily mapped using automated methods. This paper describes the application of an automated method of analysis of 3D images that provides users with the capacity to map exposed structures automatically. The method is based on the use of vector classification methods used in some neural network systems and provides rapid and reliable identification of exposed planes. CSIRO Exploration and Mining is applying these methods to 3D images for a range of applications from pit mapping to machine automation.

Jan 1, 2006

By H. M. Fisher, R. E. Snow, S. C. Sun

RAPID colorimetric estimation of the amount of transparent minerals has been applied success- fully to instream mill products at the cryolite flotation plant of the Pennsylvania Salt Mfg. Co., Natrona, Pa. Apparatus used was a Bausch & Lomb monochromatic colorimeter. The optical assembly of the colorimeter, shown in Fig. 1, passes light from a 6-v, 32-cp, prefocus incandescent lamp through two condensing lenses, a heat-absorbing filter, an aperture-control diaphragm, an interference filter, and a sample container. The light finally strikes a barrier-layer photocell and the output current of the photocell is measured by a galvanometer. The engraved index line of the collective lens, located between the lamp and the galvanometer, is imaged upon the transmission scale of the colorimeter by the galvanometer mirror. Reflected light from the galvanometer mirror, the position of which is determined by the output current of the photocell, enables reading of percent transmission throughout the mineral sample being tested. The colorimeter, Fig. 1, was standardized as follows: 1-The colorimeter was connected to a Sola constant voltage transformer, A, of 6-v output operated from a 110-v ac supply. 2-Turning the toggle switch, C, illuminated the transmission scale, B, and the control knob, D, was adjusted with a blank in the optical system until the hairline on the scale read zero. 3-A No. 430 interference filter, E, was inserted into the filter channel, F. &--A test tube, G, containing 7 cc of distilled water was pressed into the sample space, H, and the fine adjustment knob,

Jan 9, 1954

By H. M. Fisher, R. E. Snow, S. C. Sun

RAPID colorimetric estimation of the amount of transparent minerals has been applied successfully to instream mill products at the cryolite flotation plant of the Pennsylvania Salt Mfg. Co., Na-trona, Pa. Apparatus used was a Bausch & Lomb monochromatic colorimeter. The optical assembly of the colorimeter, shown in Fig. 1, passes light from a 6-v, 32-cp, prefocus incandescent lamp through two condensing lenses, a heat-absorbing filter, an aperture-control diaphragm, an interference filter, and a sample container. The light finally strikes a barrier-layer photocell and the output current of the photocell is measured by a galvanometer. The engraved index line of the collective lens, located between the lamp and the galvanometer, is imaged upon the transmission scale of the colorimeter by the galvanometer mirror. Reflected light from the galvanometer mirror, the position of which is determined by the output current of the photocell, enables reading of percent transmission throughout the mineral sample being tested. The colorimeter, Fig. 1, was standardized as follows: 1—The colorimeter was' connected to a Sola constant voltage transformer, A, of 6-v output operated from a 110-v ac supply. 2—Turning the toggle switch, C, illuminated the transmission scale, B, and the control knob, D, was adjusted with a blank in the optical system until the hairline on the scale read zero. 3—A No. 430 interference filter, E, was inserted into the filter channel, F. 4—A test tube, G, containing 7 cc of distilled water was pressed into the sample space, H, and the fine adjustment knob,

Jan 1, 1955

By Zou Lisheng

The culture of safety is very important to coal mining production. About 90% of mine accidents are caused by human error. This paper analyzes the status of China?s coal mining accidents, and accident cause. This paper explains the concept of safety culture, the value of safety culture, as well as the relationships between safety culture and safety behavior, and between safety culture and science and technology. The paper proposes the model of safety culture and the ways to enhance safety culture of coal enterprises. Safety culture and safety production is closely related and are significant to the improvement of mine safety situation in China.

Aug 1, 2013

By Virgil J. Stachura

The Bureau of Mines has investigated techniques and instrumentation that measure accurately the airblast overpressures from surface mine blasting. The results include equivalencies between broadband research instrumentation and commercially available impulse precision sound levels meters measuring: root-mean-square, peak, fast, slow, impulse, A and C weighting, C-weighted sound exposure level (CSEL), and "linear" (flat) response. These values were obtained from field measurements and broadband FM tape recordings of production blasts at area and contour coal mines, limestones quarries, and iron mines. Frequency response was determined for 14 commercial systems.

Jan 1, 1981

By Stephen J. Hales

State-of-the-art Resistance Spot Welding (RSW) equipment has the potential to permit adaptive feedback through recent advances in computerized process control. The initial step toward achieving this goal involves assessment of the effect of specific variables and the interaction between these process inputs on spot weld characteristics. This investigation addresses this issue through the application of Taguchi methodology to understand and refine a RSW schedule developed for joining of two dissimilar aluminum-lithium (AI-Li) alloys of different nominal thickness. The experiment was designed to establish a hierarchy of inputs with respect to each 'other, and to determine the significance of these inputs with respect to experimental noise. Valuable insight was gained regarding the interaction between process variables and the effect of certain equipment-related changes. In spite of a decrease in equipment performance, an improvement in the maximum strength attainable for defect-free spot welds resulted from the application of the statistical experiment.

Jan 1, 1992

By A. S. H. Kabir

Due to the high specific strength and excellent corrosion resistance, Ti-6A1-4V has been widely applied in aerospace industries. In this study, the welding performance of 3.2-mm and 5.1-mm thick Ti¬6A1-4V sheets was studied using a 4 kW continuous wave Nd: YAG laser. It is found that the use of filler wire, matching the parent metal composition, can bridge the joint gap and produce full penetrated welds up to a width of 0.6 mm without cracking. The laser welds were characterized in terms of the bead geometry, defects, microstructures, and hardness. With increasing joint gap, the percent porosity area increased, reaching just over 1% of the fusion zone area at a gap width of 0.6 mm for the 3.2 mm and 5.1 mm thick sheets. The maximum underfill depth in the Ti-6A1-4V laser welds was about 5% or 7% of the sheet thickness for the 3.2-mm and 5.2-mm thick materials, respectively, meeting the AWS D17-1 specification. The microindentation hardness was maximum in the fusion zone and sharply decreased through the heat affected zone until reaching the base metal value.

Jan 1, 2011

By H. Rosenberg

Haldor Topsoe A/S has developed its WSA technology to meet the demand in the market for a simple and reliable process that converts sulphurous emissions from off-gasses into high-grade sulphuric acid. With more than 50 references in 25 countries, the WSA technology has proven its ability to generate acid at 98% concentration, efficiently and economically. The wet gas sulphuric acid (WSA) technology treats the furnace off-gas directly from upstream gas cleaning plants. No further drying is required, since the humidity present in the off-gas is used to hydrate the SO3generated in the converter and produce sulphuric acid. The heat generated during the oxidation, hydration and condensation processes is principally reused in the process to preheat the off-gas to the required temperature level, and also to generate high pressure superheated steam for process use. This advantage of steam production, coupled with lower water and power consumption requirements, is particularly important in the African production environment. Having fewer process components than conventional acid plants, the WSA technology is a simple and compact operation, which makes it easier to retrofit into an existing smelter plant. Further, the WSA technology simultaneously offers the possibility to treat multiple gas streams arising within the production facility due to superior flexibility in terms of SO2concentration and turndown ratio.

Jan 1, 2006

By D. R. Nagaraj

Based on our finding that commercial copper chelating solvent extractants such as LIX65N® and LIX63® are excellent collectors for copper minerals, a detailed study was made using several water-soluble chelating agents belonging to the class of aromatic hydroxyoximes and having a gradual structural variation. A basic study of the system salicylaldoxime-tenorite was also carried out. Microflotation tests as a function of concentration of oxime, pH, addition of copper etc., using oxidic copper minerals such as chrysocolla and tenorite, and batch laboratory flotation tests using synthetic mixtures of quartz and oxidic copper minerals were carried out. The studies were aimed at an understanding of the collector function of the hydroxyoximes and of the general flotation behavior in these systems, in addition to studying the structural aspects of oximes vis-a-vis flotation. The results have demonstrated that all of the hydroxyoximes studied here have comparable collector property, and in all cases the oxime was found to be partitioned between the mineral surface and the copper in the bulk aqueous phase in the form of a bulk copper chelate. The occurrence of the latter could be accounted for by the formation in the bulk phase of a chelate between oxime and copper released from the mineral and/or by the detachment of the surface chelate. The role of surface and bulk chelates in flotation is discussed based on the results of partitioning of chelating agent into bulk and surface chelates in the system salicylaldoximetenorite. The effect of substitution of CH2 groups or benzene ring in the chelating agent molecule on its collector property is also discussed, in addition to the finding that only the anti-isomer has the ability to collect.

Jan 1, 1979

By H. Son

The three-dimensional (3D) reconstruction of as-built industrial plant models plays an important role in revamping planning, maintenance planning, and preparation for dismantling during the lifecycle of industrial plants. Recently, the 3D reconstruction of existing industrial plants was conducted using laserscan data to make surveying processes more efficient. However, the current 3D reconstruction process from laser-scan data is still limited due to the need for significant human assistance. Although a great deal of effort has been made to efficiently reconstruct 3D as-built industrial plant models, the presence of objects?such as equipment, pipelines, and valves of different sizes and shapes?in existing industrial plants significantly increases the complexity of laser-scan data and makes automating the reconstruction process more challenging in practice. The purpose of this study is to propose a knowledge-based approach for the 3D reconstruction of as-built industrial plant models from unstructured laser-scan data. First, pipelines were extracted from laser-scan data based on surface curvature information and knowledge about pipelines' sizes from existing piping and instrumentation diagrams (P&ID). Once entire pipelines were extracted, they were modeled based on skeleton features. Then, the remaining objects were clustered and grouped separately via the region grouping process. Afterward, clustered objects were retrieved and modeled based on global feature-based matching from the 3D database. Finally, the resulting model was checked to ensure that it was well-reconstructed according to the information regarding the relationships among objects abstracted from the existing P&ID. The preliminary results on actual industrial plants show that integrating knowledge into the reconstruction steps played an important role in the proposed approach and that this approach obtained accurate as-built industrial plant models from unstructured laser-scan data. The proposed approach could be successfully utilized to assist in many applications during the lifecycle of industrial plants.

Aug 1, 2013

By M Monaghan, B S. Gregory

The Geita Gold Mine is located 80 km southwest of the town of Mwanza in the north-west of Tanzania and is 100 per cent owned by AngloGold Ashanti Limited. Open pit mining commenced at Geita in 2000. In 2011, the operation produced 494 000 oz at a cash cost of US$536/oz. This is a significant improvement from 2008, when 264 000 oz were produced at a cash cost of US$742/oz.A period of relatively poor operating performance at Geita was recorded over the period from 2006 to 2009. A period known at Geita as æthe turnaroundÆ commenced in 2009, and has been remarkable to say the least. Over the last couple of years the mine has embarked on a journey, which saw various interventions and initiatives. Among the key initiatives were Project ONE (which focuses on business process framework, systems for people and safety transformation), asset integrity, fatigue management and contract mining of satellite pits.Since the commencement of the turnaround at Geita, gold production has matched market guidance. The mine has returned to positive cash flow on the basis of strong performance on cash management, improved production and increased gold price.This paper explains some of the details of the mine operationsÆ improvements, how they were implemented, their relative contributions to improved mining performance and the path ahead to best practice. Observations will be made about some improvement rules that can be applied generally in open pit mining.CITATION:Gregory, B S and Monaghan, M, 2012. The path to best practice at Geita Gold Mine, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 41-48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012