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By Matthew Russell, Bobby Randhawa, Leopoldo Mariscal Samaniego, Jose A. Puente, D. Brosig, Paykan Safe

The La Caridad copper smelter, located in Nacozari, Mexico, have started a multi-year plan to reduce sulfur dioxide and particulate matter emissions into the environment. In 2014 the smelter completed a voluntary plant-wide SO2 process emissions inventory as part of the smelter’s proactive environmental stewardship policy. In turn, this triggered the development of several environmental projects to alleviate these emissions. A strategy consisting of improved capture efficiency of the sources with greatest impact has been followed to maximize cost-effectiveness. The reduction of secondary emissions from the Teniente Converter, as well as of primary and secondary emissions from the Peirce-Smith Converters have been key areas of priority. Additionally, a new system to capture and recover particulate matter from the Anode Refining Furnaces off-gas is also in the process of being implemented. This paper presents an overview of the work developed behind this effort and the smelter’s vision towards a greener future. INTRODUCTION The La Caridad copper smelter is owned and operated by Metalurgica de Cobre S.A. de C.V. (a subsidiary of Grupo Mexico). Currently, the smelter has a production capacity of 300,000 tonnes of anodic copper per year. The smelter is coupled with a 300,000 t/y electrolytic refinery. Other by-products (such as precious metals and sulfuric acid) are also generated as part of an integrated process. The original smelter started operating in 1986 with one Furukawa concentrate dryer, one Outokumpu Flash Smelting Furnace (FSF), two slag cleaning electric furnaces (SCFs), three Peirce-Smith Converters (PSCs), two Anode Refining Furnaces (ARFs) and one casting wheel. In 1997, a plant expansion project was concluded with the installation of one steam dryer, one Modified Teniente Converter (MTC), one additional ARF, one additional casting wheel, and the electrolytic refinery [1]. Over the years, the smelter management has implemented numerous environmental projects to alleviate SO2 and particulate matter (PM) emissions. The smelter process gas handling system captures the process gases from the FSF, MTC, and the three PSCs. The process gases are cleaned and conditioned and sent to the two acid plants. The first acid plant (with a capacity of 226,000 Nm3/h, wet basis) was commissioned in 1988 to process the FSF and PSC off-gases. A second acid plant (with a capacity of 195,000 Nm3/h, wet basis) was commissioned as part of the smelter expansion project [1]. The PSCs also have a secondary gas handling system with a dedicated baghouse and stack. The Furukawa dryer off-gas reports to a dedicated electrostatic precipitator (ESP) for dedusting before venting via a local stack. Process gas from the two SCFs, along with hygiene ventilation from various sources inside the smelter (including matte and slag tapping hoods from the FSF) report to a baghouse-based gas handling system and vent to atmosphere via a local stack. The original ARFs do not have an off-gas handling system, however, each ARF has a post- combustion chamber which naturally vents the process gases to the atmosphere via a dedicated stack.

Jan 1, 2019

By J. F. T. Agapito, L. J. Gilbride, K. Hollberg

Room-and-pillar mining at the Big Island Mine uses narrow, yield (i.e., load transferring) pillars to achieve high resource recovery and productivity. Two flat-lying 3- to 3fi-meter (10- to 11fi-ft) seams are mined. The interburden between the seams is about 10 meters (33 ft) and the cover depth is 250 to 330 meters (820 to 1,080 ft).Most of the mining has been single-seam, but two-seam mining will begin in the near future. Yield pillars minimize stress transfer between the seams. However, it is important that good long-term stability be maintained to prevent subsidence over a large portion of the mine beneath the Green River channel. Three stress issues impacting stability are discussed in this paper: (1) higher-than-gravity vertical pre-mining stresses, (2) time-dependent stress transfer or arching, and (3) stresses induced by strata gas. Although the stress environment and behavior is not fully understood, steps have been taken in mine design and operations to minimize impacts to stability. Stress determinations have been very important to verify analytical predictions used in mine design and in long-term stability assessment.

Jan 1, 2004

By Phillip J. Mackey, Susumu Okabe

Copper mining and smelting has been carried out in Japan for over 13 centuries and in fact stretching back into antiquity. In 1889, the first electrolytic copper refinery in Japan based on Elkington’s principles was started by Furukawa Mining at Honjyo in downtown Tokyo based on the multiple or parallel system. Within two decades, a number of other copper refineries had begun operation. Interestingly, but perhaps not surprising given Japan’s long history of copper production, this first refinery in Japan commenced just ten years after the first refinery in the USA (1879), and not long after the first plants in Europe. By 1935, as a result of growth in copper demand, there were six domestic copper electro-refineries in Japan with an installed capacity of 97,800 tonnes/a, while actual production was 71,200 tonnes/a. Since about 1932, the majority of these plants were based on the more common parallel or multiple system. In 1946, just after World War II, domestic production capacity had dropped considerably to 29,000 tonnes/a, however with reconstruction, capacity and production expanded rapidly, with production reaching 81,000 tonnes/a in 1955, 187,000 tonnes/a in 1960 and 307,000 tonnes/a in 1965. The introduction of the first refinery and the early ones that followed and subsequent developments are discussed in this paper. The major technical achievements during the high growth period from 1945 to 1963 included: the use of fire- refined anodes; the introduction of newly-developed rectifiers; the introduction of lead-lined or vinyl-lined concrete cells; improvements in the electrolyte heating system; application of improved anti-corrosion materials and the introduction of heat-insulating surface coverings. In 2018, Japan’s refined copper production totaled 1,595,000 tonnes of copper, with Japan ranking third in the world after China and Chile. INTRODUCTION In 2018, Japan’s refined copper production totalled 1,595,000 tonnes of copper and Japan ranked third in the world for refined copper after China and Chile (Wood Mackenzie, 2019). There are now eight copper refineries in Japan which provide Japan’s production of refined copper. These plants are listed in Table 1 (Wood Mackenzie, 2019), also showing the production trend since 2013; in general, production over this period has been relatively steady. The Toyo plant is now the 7th largest copper refinery in the world after several large plants as rated by capacity in China, Russia and India (ICSG, 2019).

Jan 1, 2019

By Ervin P. Fuchs

Volume II of this report presents the vibration data, octave band data, one-third octave band data and narrow band (amplitude versus frequency) data for ten mining machines. These ten mining machines include a Goodman 968-2 Loading Machine, a Lee Norse 245 Continuous Miner, a Jeffrey 120L Continuous Miner, a National Mine Service 3080 Continuous Miner, Acme D-1 Roof Bolter, a Lee Norse 265 Continuous Miner, two Jeffrey Locomotives, a Joy CD-71A Coal Drill and a Jeffrey 100L Auger Miner. Volume J of this report presents the effects of underground environment and loading conditions on noise levels of coal mining equipment

Jan 1, 1979

By D. C. McIntire

The Homer City Station, jointly owned by New York State Electric and Gas Corporation and Pennsylvania Electric Company is a three unit coal fired station. The first two units were put into commercial operation in 1969; the third unit became commercial in 1977. Units 1 and 2 are subject to the Pennsylvania State Implementation Plan (SIP) emission limit of 3.7 pounds of S02 per million BTU. Unit 3, having started construction later, is subject to the Clean Air Act, New Source Performance Standards emission levels of 1.2 pounds of 50-2 per million BTU.

Jan 1, 1988

By William K. Tolley

The U.S. Bureau of Mines (USBM) is investigating hydrometallurgical processing techniques to recycle metals from semiconductors and other advanced materials. Cadmium and tellurium were recovered from mixed CdTe/CdS scrap produced in the manufacture of thin-film photovoltaic devices. Selective cadmium dissolution was achieved using oxygen-pressure leaching in dilute sulfuric acid. Leaching the scrap for 90 min at 110° C in 2.2NH2S04 under 400 psig 02 yielded 97% Cd extraction; however, cadmium content of the residue ranged between 4% and 7%. Soluble iron was added to the lixiviant to catalyze oxidation of the CdS component. Tellurium and sulfur remained in the leach residue primarily in the elemental form. The iron and tellurium were removed from the cadmium-rich leach liquor by adjusting the pH to 5.3. The cadmium was recovered as cadmium sulfate crystals by evaporating the solution. Alternative leaching and purification schemes are discussed.

Jan 1, 2010

By A. B. Hooker, E. J. Coggeshall

"INTRODUCTION Ignitions of gas at the coal face when a blast is fired electrically are often a tributed to the explosive; but sometimes the ignition cannot be explained satisfactorily in this way-in fact, ignitions have occurred when the detonator has failed explode.The possibility of such electrically by sparks from the blast between poorly insulated leading wires and detonator leg have been recognized. Several countries have provided safe types of single-shot blasting units; some have permitted the use of larger multiple-shot blasting units provided each unit is equipped with a time-limiting switch that prevents unnecessarily long application of voltage on the leading wires after the shot has occurred, the assumption being that the firing line will this be dead before damage to the wires and subsequent sparking can take place. An extensive research was made by a French commission relative to the characteristics of electric detonators and methods of firing. Along other tailings they investigated the probability of ignitions by sparks across the leading wired at the face, also the time and duration of the various events in blasting, such as ignition of the detonators, movement of the coal face, and application of firing current. They suggested, as a means of eliminating or reducing tilt possibility of gas ignitions from the blasting unit, that the timing switch of the blasting unit be designed to disconnect the blasting"

Oct 1, 1934

By S Bouzalakos, W Timms, H Malli

Combining ultramafic mine tailings and acidic mine drainage via mineral carbonation to sequester carbon dioxide, presents an opportunity to minimise waste on mine sites. Low pH mine water with trace element concentrations can be effectively treated by high magnesium mine tailings, a useful source of finely ground reactive matrix. By using milled tailings for mineral carbonation, there are negligible energy requirements for communition of ore rocks to reduce particle size. This study aimed to assess the technical applicability of reacting ultramafic tailings and acidic mine water through mineral carbonation technology in the mining industry. Dissolution has been identified as the rate limiting stage in mineral carbonation; hence the study focused on identifying optimal dissolution conditions. Ultramafic tailings (particle size <100 µm) derived from serpentinite ore, were reacted with a typical mine water that was synthesised in the laboratory. Through variances in the solid to liquid ratios and temperature of dissolution, a maximum five per cent magnesium dissolution efficiency was reached at 50 g/L and 100°C. The acidic mine water was neutralised (from pH <2 to pH ~6) and iron, copper and zinc ion concentrations reduced significantly during the formation of solid precipitates. Carbonation was undertaken by injecting carbon dioxide into the magnesium-rich solution to form stable carbonates. The experimental work demonstrated proof of concept; however, dissolution efficiency and carbon dioxide sequestration was low, indicating that further research would be required before larger scale implementation.CITATION:Malli, H, Bouzalakos, S and Timms, W, 2015. Ultramafic mine tailings to treat acidic mine water and lock away carbon through mineral carbonation, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 133–136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By J. E. Cannaday, R. J. Austin, R. K. Saxer

PREVIOUS investigators have determined activation energies and have postulated various controlling mechanisms for creep.'-' Recently Barrett et 01.I5 have suggested, as the result of their work with cadmium, that the apparent activation energies for creep (AHc) above 0.5 T, could be correlated by means of activation energies for self-diffusion (AHSD) and modulus of elasticity functions: AHC = AHSD - (5RT/E) dE/dT. The wide disparity of apparent activation energies previously obtained with nickel compared to those reported for other fcc metals and the desire to test the postulate of Barrett el al. prompted this study. The as-received 17.5-mil nickel wire used during this work assayed 99.87 pct pure, Table I. X-ray analysis indicated that the wire was in a stress-re- lieved state and metallographic examination revealed an equiaxed grain size of approximately 0.01 mm. Specimens degreased in acetone and cut to 1-1/2 in. lengths were tested in a cam-mechanized constant-stress creep machine. A vacuum of at least lo-5 mm Hg was maintained during all tests. Stresses were applied when thermal equilibrium was established. When a measurable (at least 0.5 pct) secondary creep was observed, the temperature was pulsed to a higher temperature. Pulsing time varied from 30 sec at 480°C to 2 min at 1300'C and above. Slopes of creep curves were determined after the initial acceleration in the strain rate had subsided and steady-state creep was achieved. To confirm the results obtained, additional tests were performed incorporating a temperature pulsing method suggested by sherby. In this method the load was removed during temperature pulsing and reapplied after thermal expansion had occurred. No appreciable differences in results were obtained. Tests were performed over a wide range of temperature (470" to 1310°C) and stresses (250 to 17,000 psi). The expression was used to calculate activation energies. In this expression T1 and T2 are the initial and final temperatures, and el and i2 are the creep rates at T, and T2. The variation of the apparent activation energies with the mean test temperature calculated by means of Eq. [I] are shown in Fig. 1. The mean test temperature (Tmean) was calculated from the relationship

Jan 1, 1967

By Paul Foote

SEEBECK discovered, in 1821, that if, in a closed circuit of two metals the two junctions are at different temperatures, an electric current will flow in the circuit. In the case of an iron and a copper wire, for example, current will flow from copper to iron at the hot junction, or from iron to copper at the cold junction. Two factors combine to cause the current. An electromotive force exists between the two metals, the magnitude of which, depends upon the temperature and upon the metals; this is called the Peltier e.m.f. If a single wire of homogeneous material is heated at one end, an electromotive force is developed between the ends of the wire, the magnitude of which depends upon the metal and upon the difference in temperature; this is known as the Thomson e.m.f: The total e.m.f. acting in the circuit is the sum of the Peltier e.m.f. at the two junctions and the Thomson e.m.f. in each wire, consideration being given, of course, to the algebraic signs of the four e.m.f.'s. The total electromotive force thus depends upon the difference in temperature of the two

Jan 9, 1919

By Russell P

Polyurethane resin (PUR) is extensively used in almost all coal producing countries. On the local scene, PUR components suitable for underground application were selected and subsequently, trials were carried out at several coal mines. This paper describes the work at Pikes Gully Colliery (B.P.3Coal), where water flow rates of up to 4.5 m (1000 gallons) per minute, were reduced to 1-1.5 m /minute at the tirst stage of application. Subsequent trials were carried out at West Cliff Colliery (Kembla Coal and Coke). A variety of PUR chemical mixtures were tested in coal ribs and in the roof of intersections and roadways. The trial results are presented with all particular details. Using the PUR injection method, the roof, at the most difficult intersection, was stabilised and 'de-bonded' roof bolts were re-sealed. At Pikes Gully and West Cliff Collieries, 2 tonnes and 3 tonnes of PUR chemicals were injected, respectively. The technique, primarily based on German experience (Bergwerksverband), was used by Delta Control Systems Pty. Ltd. ACIRL was closely associated with the trials, which were monitored by installation of the measuring Stations.

Jan 1, 1986

By Martin G. Taube, Dwayne A. Lewis

Drainage improvements at O’Hare International Airport, Chicago, IL included the installation of a drainage and storm water system to control the over?ow from nearby Willow Higgins Creek. This involved construction of a weir structure at the creek and the channeling of water from the weir to a newly constructed reservoir via three, 3.7-m(12-ft) diameter, underground storm sewer lines. The sewer lines passed beneath an existing, 2.3-m (90-inch) diameter high-pressure water main, which was to remain in service throughout sewer line installation. The soil composition around the water main ranged from medium stiff clays to silty sands and sandy silts. Triple-fluid jet grouting was used to stabilize the variable soil profile beneath the water main in preparation for tunneling and installation of the sewer lines. The varying soil strata presented a challenge to the project team to establish a constant set of jet grouting parameters throughout the stabilized zone while keeping within the specified unconfined compressive strength range for the stabilized zone of 690 to 1,380 kPa (100 to 200 psi)at 28 days.

Jan 1, 2003

By Roberto Lira Chipana

El presente texto señala el proceso de optimización en perforación y voladura de la mina Iscaycruz ubicada en la parte oriental de la región Lima. Este procedimiento comprende la perforación horizontal (tipo de mallas para roca suave, semidura y dura, mallas antiguas y mallas optimizadas actuales), perforación vertical y el sistema Casing, tipo de mallas para roca suave, semidura, dura. Asimismo, el diseño y la aplicación de las mallas de perforación y voladura tipo VCR permite tener un menor metraje en taladros de producción, un menor consumo de explosivos y un buen control de la fragmentación del material.

Sep 12, 2005

By Kim C. Harden

INTRODUCTION The purpose of the following discussion is to present the state of the art of solution mining. Since the economics of a mining method ultimately determines its applicability and viability this presentation shall revolve around the costs of in- situ solution mining. First the assumed physical characteristics of the hypothetical ore body are described, followed by the appropriate operating assumptions. Then after a brief discussion on the type of surface plant to be used, the assumed project time tables and costs for Texas and Wyoming are presented. Finally, the economics of in-situ uranium leaching are analyzed through the use of discounted cash flow rate of return analysis. ORE BODY CHARACTERISTICS The assumption of the ore body characteristics is probably the most variable portion of this discussion. The characteristics that have been used are based mainly on state of the art technology, however, consideration of the most common depths of ore, ore thicknesses, and permeabilities also influenced these assumptions. In addition, it is assumed that these assumptions are equally applicable to Texas and Wyoming. The average grade of the ore is assumed to be .09% U308 with no apparent disequilibrium. The average thickness of ore is 2.29 m (7.5 ft) which results in an average grade-thickness (GT) of .675. The assumed depth to the top of the ore is 121.92 m (400 ft), the ore density is placed at 1.78 gm/cc (18 cu ft/ton), the porosity is estimated to be 28% and the permeability 1 darcy. These assumed ore body characteristics are shown in Table I. In addition, it is specified that the costs to be later discussed are based on a minimum GT cut-off of 0.15. It is more common to use GT cut-offs of 0.30 to 0.50 but GT cut-offs as low as 0.15 in conjunction with a minimum grade of 0.05% U308 have been used in the past with success and is considered state of the art. The ultimate percentage of uranium recovered from the ore is left to the discretion of the reader since the costs and economics are based on pounds recovered by the surface plant. OPERATING AS.SUMPTIONS An annual production rate of 200,000 lbs U308!yr was chosen for this example. In order to maintain this production rate, based on the ore body characterized above, a flow of 4731 liter/min (1250 GPM) with a recovery solution grade averaging .039 gm U308/liter is assumed. A regular 5 spot well field pattern is used with a well spacing of 21.5 m (70.7 ft) between like wells and 15.24 m (50 ft) between unlike wells. This well spacing gives each well an area of influence equal to 232.25 sq m (2500 sq ftl. An excess wells factor of 1.17 is used to estimate additional monitor wells and well field boundary wells. Each production well is expected to yield an average flow rate of 37.85 liter/min (10 GPM). In addition it is assumed that the ore body has a good shape in that it is not tenuous and narrow but has at least an average width of 200 ft. The process chemistry required for this ore body is assumed to be based on the sodium carbonate System- Oxygen is the chosen oxidant. Sodium chloride elution followed by precipitation with hydrogen peroxide makes up the remaining portion of the process. A fluidized up-flow ion exchange system is specified. The operating assumptions are listed in Table II. Restoration of the ore body shall be assumed to be accomplished through the use of ground water flush. Other methods may be considered as having to fall within the costs estimated for a ground water flush in order to be economic. In Texas it is assumed that a high capacity disposal well (200 GPM +I is required and in Wyoming evaporation ponds covering approximately 35 acres are to be used. No specific cost has been given to restoration. Instead only the additional capital investment for restoration equipment is given. Then, one year of restoration operating expense is estimated and included as the operating expense for one year beyond the last pound of U308 produced. It is also assumed that restoration will be pursued in the mined out areas of the ore body contiguous with ongoing production.

Jan 1, 1980

By J Krahn

In designing climate exposed soil structures such as caps and covers over mine waste it is necessary to include the wetting and drying influences of the local climate in order to accurately predict the net water, vapour and oxygen fluxes across the ground surface and through the base of the covers. The most advanced evaporative flux modelling tools currently available to practitioners have been limited to rigorous one-dimensional models (ie SoilCover) or semi-empirical two-dimensional models (ie Hydrus-2D). It is common practice to use the rigorous one-dimensional evaporative flux model results to develop a surface boundary function that can then be applied within a saturated/unsaturated two-dimensional model. However, this is not an ideal situation and results in a further approximation of the real system being modelled. This paper will highlight the use of a new modelling tool, VADOSE/W, which brings existing, rigorously formulated evaporative flux theory into the familiar setting of a two-dimensional model. The model is enhanced for simultaneous two-dimensional oxygen gas transport analysis, which has direct application in the mine waste industry. A key focus of the paper will be addressing the limitations of one-dimensional analysis for cover systems on sloping and hummocky terrain.

Jan 1, 2003

By K. Kavouridis

The competitiveness of power production from lignite depends on the ability of coal industry to meet CO2 emissions limits, as specified by the Kyoto protocol. According to the National Allocation plan issued by EC, power plants should reduce CO2 emissions to a certain level, other-wise they will be obliged to cover the difference buying CO2 certificates through the Emission Trading Scheme. These charges will increase the operating cost of current units, as well as the investment cost for new units. To predict the increase in the marginal cost of electric power produced from the current plants of Western Macedonia, an emissions factor (CO2 t/MWh) for various units has been computed. Based on the algorithm used, this factor depends on the calorific value of the lignite, the efficiency of the power plant and the oxidation factor of the unit. For lignite plants with efficiency ~37%, CO2 emissions factor ranged from 1.19 t/MWh to 1.32 t/MWh. The increase in the marginal cost of kWh, as compared to the values of CO2 certificates, is higher in units fed with low quality lignite and worsens if the efficiency of the unit is low too. Also the presence of calcareous minerals in lignite increases the CO2 emissions and consequently the cost of power generation.

Jan 1, 2006

By L. V. Wade

Abstract-US Bureau of Mines efforts under longwall research programs to develop the capability to predict support requirements for longwall/shortwall support systems are discussed. Ground control studies are being conducted in conjunction with several longwall/shortwall demonstration projects. Geologic, support performance, and strata behavior are being documented on these projects. A hypothesis is presented for the prediction of support requirements.

Jan 11, 1978

By Douglas E. Wolfe, Jogender Singh, Robert Miller, Dong-Ming Zhu, Jeff Eldridge

This paper discusses microstructural changes produced by two novel approaches using electron beam physical vapor deposition (EB-PVD) in which periodic strain fields/microporosity was incorporated within the large columnar grains of Zr02- 8wt.%Y2O3 (8YSZ). The traditional columnar microstructure of partially stabilized zirconia has been slightly modified to produce a lower thermal conductive thermal barrier coating (TBC) by periodically interrupting the condensing vapor resulting in microstructural modifications with diffuse or sharp interfaces and morphological changes on the sub-micron scale without changing the composition of the TBC. These microstructural modifications resulted in a 20-30% reduction in the thermal conductivity, 28-56% increase in hemispherical reflectance, improved oxidation cyclic life (over 100%), and better strain tolerance as compared to standard ZrO2-8wt.%Y2O3 deposited on platinum-nickel-aluminide and CoNiCrA1Y bond-coated MAR-M-247 test samples. The TBC with tailored microstructures were examined by various techniques including scanning electron microscopy (SEM), x-ray diffraction (XRD), steady-state laser heat flux technique, and hemispherical reflectance.

Jan 1, 2004

By R. K. Mehta

An accurate, efficient and stable computation of the mill matrix function (eAt) is needed where mill matrix (A) is a real general matrix. Two important modeling cases in comminution where such need arises are: Heterogeneous comminution behavior of multi-component ores and ultra-fine grinding involving simultaneous attrition and fragmentation breakages. This paper presents the application of a novel splitting method in conjunction With similarity transformation technique in the form of "product formula" which is found to work in all cases and uses a most aggravating, yet interesting property of the matrix exponential in a restricted sense. Results are presented showing that this method can yield solution as accurate as those obtained With an analytical technique. The utility of this computational approach is demonstrated by parameter estimation analysis using a distributed component model in the liberation area through computer simulations.

Jan 1, 1992

By H. A. Doerner

From thermodynamic calculations3 Maier predicted that zinc oxide Land methane would react at specified temperatures substantially according to equation (1). (1) ZnO + CH; = Zn (gas) + CO + 2H2 Other reactions that may take place are: (2) CH4 = C + 2H2. (3) ZnO + CO = Zn (gas) + CO2 (4) ZnO + H 2 = Zn (gas) + H2O . Maier predicted that 870°C. would be the critical temperature above which reaction (1) would take precedence over reaction (2) and that reaction (1), at equilibrium, would be substantially complete at or above 927°C.

Jan 1, 1931