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By María Cristina Ruiz

In the processing of copper concentrates by the conventional smelting-converting technology, complying with the increasingly severity of environmental legislation in some countries has become difficult, mainly due to severe fugitive emissions of gases produced during the batch PS (Peirce-Smith) converting step. In this work, the results of an investigation on the pressure leaching with sulfuric acid and oxygen of white metal (produced in a Teniente Converter reactor) are discussed. The study was carried out at laboratory scale and the main variables studied were temperature, concentration of sulfuric acid and partial pressure of oxygen. The experimental results indicated that most of the sulfur in the white metal was oxidized to sulfate in the whole range of temperature studied (105ºC to 150 ºC). The concentration of sulfuric acid over 0.05 M, and oxygen partial pressure over 6 atm had little effect on the dissolution of copper from the white metal. On the other hand, temperature had the most significant effect on copper dissolution; below 130 ºC copper dissolution was incomplete after 5 hours of leaching while at 150 ºC the dissolution was complete in 90 minutes and 10 atm of partial pressure of oxygen

Jan 1, 2006

By W. Birch

The traditional concept of scaled-distance modelling for predicting blast induced ground vibration holds many drawbacks, not least of which is the major effect data scatter imparts on confidence determination. An investigation by the Department of Mining and Mineral Engineering, The University of Leeds, England has resulted in the development of simple but effective method of improving prediction capacity through the reduction of effective error by incorporating individual location response into a scaled-distance model. The work is the product of an l&month blast-monitoring campaign at a limestone quarry situated in North Yorkshire, England. The data, when presented in the form of a scaled-distance model, indicates a typical scenario where a good overall correlation becomes marred by the extent of data scatter. Examination of the individual monitoring locations however indicates that the response of the individual location is an important factor in the explanation of the large residuals. The novel approach thathas been developed incorporates a series of locational site factors which when incorporated into a scaled distance model reduces the effective error and therefore improves prediction capacity. The approach is based on using a standard computer package “spread sheet” on the understanding that these are commonly available on all quarry or home computers. This approach has been validated by comparison with a more rigorous statistics method.

Jan 1, 2001

By G. Willard Quick

FAILURES in railroad rails have been of vital concern to engineers; railroad executives, rail manufacturers and the general public for years. Failures from transverse fissures originating from internal nuclei have received particular attention in the past 20 years. Dr. J. E. Howard first reported this type of failure in 1911, as being responsible for a wreck-on the Lehigh Valley R. R. in which several lives were lost. Since then many transverse fissures have been found. In 1919, Waring and Hofammann1 etched longitudinal sections of rails in hot acid and found cracks extending both longitudinally and transversely in certain used rails as well as in some new rails.. Since then it has been thought by many that these "shatter" cracks are the nuclei from which transverse fissures subsequently develop in service. Methods for reducing the rate of cooling rails on the hot. bed have been devised to decrease the temperature gradient and consequently the stress gradient in the rails. A study of the tensile properties of rails at elevated temperatures was made by Freeman and Quick,2 who investigated the properties at temperatures through which rails pass on the cooling bed after leaving the hot saw. In their investigation a special study was made of the ductility of the steels in the temperature range 400° to 700° C. In this temperature range it was found that certain rail and other steels showed a marked decrease in elongation and reduction of area. The phenomenon was called "secondary brittleness" and the temperature range the "secondary brittle range." A tentative explanation was presented that internal failure such as "shatter cracks" and "hair cracks" in rails are the result of thermal stresses developed in the steel structure while cooling through the secondary brittle range. The investigation showed that the magnitude of the phenomenon varies for different heats, but that it did not differ for specimens from different ingots or for different rails in a particular ingot. It was also shown that annealing rail steel at a temperature either above or below the critical

Jan 1, 1932

By Arsenio Enriquez, Adrian Deneys, Ryan Walton, Jenny Esker

NOx emissions at the Rio-Tinto Kennecott Copper (RTKC) smelter, near Salt Lake City, Utah, are regulated to a compliance emission limit at the Main Stack of 15.9 kg/hr on an annual rolling average. The paper discusses RTKC efforts and improvements, particularly related to the anode furnace operations, since the Smelter modernization in 1995 to comply with the air quality approval limit. This includes replacement of gaseous ammonia to Steam-Gas Refining (SGR) system during the copper reduction stage, upgrade anode furnace oxygen-fuel burner from Praxair’s Stabilized Jet (S-J) to Jet Lance (J-L) technology, development and implementation of operational best practices and continuing to investigate and evaluate NOx control technology and strategy in the industry. In early 2016, changes to Praxair J-L Burner technology on both anode furnaces, utilizing wider lance spacing, was adopted and further improved NOx emission levels well below the compliance limit. INTRODUCTION Since the establishment of the Clear Air Act in 1970, the Environmental Protection Agency (EPA) has been regulating emissions of nitrogen oxides (NOx) to reduce impact on public health and the environment (USEPA, CAA, USEPA, NAAQS). As a requirement of the Clean Air Act, the EPA evaluates the standards for NOx and criteria pollutants on a periodic basis and as a result, standards have been revised and ultimately reduced over time (USEPA, CAA, USEPA, NAAQS, UDAQ, SIP). To remain competitive with changing regulations and in conjunction with Rio Tinto environmental standards for continuous improvement, the RTKC smelter has been motivated to research and implement NOx control strategies. NOx health and environment impacts NOx refers to a group of seven compounds including the most common, nitrogen dioxide (NO2). (USEPA, NO2). The EPA enforces both short-term (1-hr average) and long-term (annual average) standards for NO2 to protect against associated respiratory system impacts. Short-term exposure of elevated NO2 concentrations can aggravate respiratory diseases and lead to symptoms such as coughing, wheezing or difficulty breathing while longer exposures may contribute to the development of asthma and potentially increase susceptibility to respiratory infections. (USEPA, NO2) Additionally, NOx is necessary in the formation of ozone and particulate matter less than 2.5 microns (PM2.5). Ozone concentrations can negatively impact lung function and in some cases, contribute to chronic obstructive pulmonary disease. (USEPA, Ozone) The particles associated with PM2.5 can reduce lung capacity and aggravate heart conditions. (USEPA, PM2.5) For all NOx related pollutants, children and the elderly are generally at greater risk for the health effects. (USEPA, NO2, USEPA, Ozone, USEPA, PM2.5)

Jan 1, 2019

By Rao S. B, Baafi E. Y

A venturi based multi-scrubber air cleaning system has been developed for dust control along a longwall face in coal mines. The system consists of a number of scrubbers. strategically placed along the wall face which deliver cleaned air at high exhaust velocity into the middle section of the longwall cross-section thus dividing it into two zones. The aim is to maintain the walkway on the powered support side as a zone of relatively clean air. Laboratory studies have shown that the scrubber's average efficiency is 90 per cent. Field trials in three longwall faces have shown that. under normal operating conditions. 40 to 50 per cent average protection efficiency can be achieved within 3 m to 4 m downstream of the scrubber. A three-dimensional finite element computational fluid dynamic model. FIDAP. was used to simulate the airflow patterns the dust concentration and the scrubber dust control technique at a typical longwall face. Results of simulations tally very well with the field results.

Jan 1, 1995

By J. Paul

Mining engineers in charge of open pit mine planning very often face decision making situations dealing with the selection of the most economical method for the removal of overburden. Ripping versus conventional drilling and blasting are the options considered. The choice of a particular overburden removal method depends upon the physic-mechanical properties of the overburden material as well as the various cost factors involved in the process. The analysis of techno-economical factors involved in different methods of overburden removal needs detailed study and investigation by a technical expert. But the expert system "Fragmentation System Design" has been created in a way such that it will help and expedite the decision making process relating to overburden removal in surface mines. Furthermore, this expert system can be used for detailed design aspects of overburden removal in open pit mines.

Jan 1, 1988

By D. R. Hatton

To obtain sufficient material on which to perform copper-molybdenum separation testwork a variability set of drill hole reject samples amounting to several tons was put together to include the different ore types proportions expected in the copper circuit. The samples were treated in a copper circuit pilot plant and enough mass of bulk concentrate was recovered to conduct copper moly separation tests in the laboratory. Tests consisted of stage flotation reactor (SFR) rougher pilot plant tests, conventional laboratory rougher, cleaner and 4 stage open circuit cleaner tests. The mineralogical liberation analysis of the feed and concentrate was used to model the effect of liberation on the grade-recovery relationship of the different samples. Mineral kinetic parameters for the various samples were determined by calibration to the test data. The copper concentrate results as simulated from previous studies on the same deposit were used to simulate the variability in head grade and throughput expected for the feed to the copper molybdenum separation circuit for each of the first 10 years of production. This variation in feed was then simulated through the separation circuit to obtain optimised molybdenum grade recovery curves to forecast the circuit production for each of the first 10 years. INTRODUCTION Incorporating Geometallurgy into the design for a copper molybdenum separation is especially challenging due to the low mass of final concentrate typically produced during testwork. This is due to the low molybdenum head grades and high overall molybdenum upgrading expected. With molybdenum head grades of around 300 ppm, 1 tonne of copper circuit feed is expected to produce around 300 g of molybdenum concentrate in the plant. In the laboratory however, this may end up only resulting in a few grams. Obtaining sufficient mass for laboratory testing therefore requires starting with a large initial sample and careful testwork planning to maximise the utilisation of this mass. A testwork program was designed to investigate the effect of ore variability on the copper molybdenum separation circuit (here after referred to as the molybdenum circuit). Composite samples were selected to represent the various ore types, copper content, moly content, pyrite content and clay contents expected in the copper circuit feed. These samples were run through a bulk copper pilot plant to create the feed for the molybdenum testwork. The molybdenum testwork consisted of rougher kinetic flotation tests, rougher cleaner kinetic tests, rougher cleaner kinetic tests with regrind, stage flotation reactor (SFR) pilot plant tests, open circuit cleaner tests. These tests were used to calibrate the ore kinetics in the IGS-FLEET model for simulation of the molybdenum circuit performance.

Jan 1, 2019

By F. Garcia-Carcedo

This research aimed to develop a clean technology for the production of ZnO from residues generated by the steel making industry. Scientific and technologic parameters were both investigated in order to define an industrial methodology allowing the integral recycling of EAF dusts. A reengineering of the Waelz process was perform,~d, aiming to produce a clean fraction of ZnO, fluorine free, as well as a slag enriched in metallic iron, which can be recycled in electric arc furnaces. The technical conditions used to produce the ultra pure fraction of ZnO are described. The magnetic separation of the EAF dust allowing the production of a phase high in iron and recyclable to the electric arc furnace is also discussed. Thermodynamic of the volatilization of all the elements contained in the EAF dust was performed in order to better control the thermal process in the rotary kiln. Tests were run using different reducing agents, weakly or highly reactive, aiming to determine their specific efficiency.

Jan 1, 2000

By Bianca Foggiatto, Marko Hilden, Malcolm Powell

"Since the introduction of the concept of flexible circuits (Powell and Bye, 2009), it has been further developed and refined to the definition of ‚FlexiCircuits leverage ore variability to maximise resource utilisation?. The focus of flexible circuits is to investigate processing options that provide extra capacity through sophistication rather than scale. This requires a combination of smart ore characterisation, economic modelling and innovative processing plant design. Flexible circuit design can reduce energy requirements through gangue rejection or progressive ore upgrade; and increased robustness and controllability by leveraging off ore variation. Each rock type, as characterised through Geometallurgical ore modelling, may be processed more efficiently by individually optimising processing paths. The objective of FlexiCircuits is to transform the processing capability of comminution and concentrator plants - targeting step change in performance through integrating a range of interrelated improvement opportunities. Considerable effort has been applied to developing the modelling and simulations tools required to develop and demonstrate the potential of this concept. This paper presents a practical application as a test case. A realistic application of flexible circuits is provided through a conceptual circuit design of an iron ore processing plant. It is simulated as a multi-component feed with a range of new models in the researcher’s Model Developers’ Kit (MDK) to trial the ability of different circuit designs to respond to variable ore and quantifying the potential of these circuits to transform processing capability of variable ore feed. The outcomes of the simulations are presented and discussed, providing a practical demonstration of the level of modelling and simulation required and the potential of flexible circuit design."

Jan 1, 2014

By J. L. Blaylock

Normally, the hydraulic system and structures are considered to be unrelated items. In reality, the two cannot be separated because one affects and depends on the other to function properly. This paper explores the potential failure areas of hydraulic cylinders, and suggests possible methods to prevent failures from occurring. The use of high-strength low-alloy steel in frames is reviewed and the benefits discussed. Fabrication techniques and handling of material are noted in the hope that this knowledge will aid in the repair of frames in the field.

Jan 1, 1979

By D. Limpitlaw

As coal mining often results in the generation of acid mine drainage (AMD), careful planning and management of the water on such mines is required. A colliery in Mpumalanga recently sponsored independent research into the pollution-ameliorating potential of a natural wetland that has been receiving AMD for at least two decades. Samples of the sediment collected in the wetland were subjected to nine stages of sequential extraction in a determination of the distribution of the metal species present. The samples were then analysed for aluminium, iron, and manganese. The concentrations of sulphate-reducing bacteria (SRB) were also determined. The SRB concentration was found to increase with distance downstream (away from the source of pollution). An analysis of the sediment speciation data indicated that metal immobilization may be optimal in areas where the organic adsorption of metals is at its greatest. The analysis also provided evidence of the biogeochemical improvement of the water quality as the AMD passed through the wetland environment. The metal species present did not correlate strongly with the SRB populations; nor did the soluble species correlate with the species formed over long periods of time.

Jan 1, 1996

In 1972, with the West Lyell Open Pit winding down, mining operations transferred underground. All development tunnelling until the end of the decade was carried out by a fleet of ten pneumatic Jumbos.A decision was made in 1980 to purchase an electric-hydraulic Jumbo and a second was purchased in 1982. Their introduction changed the face of development at Mount Lyell. Significant new demands were placed on main-tenance sections, particularly on electrical reticulation.Subsequently, two further electric-hydraulic Jumbos were purchased from Agnew Mining in 1984, and successfully overhauled and commissioned. As well, two electric-nydraulic production drilling rigs have been purchased. Only one of the original pneumatic Jumbos remains in service.

Jan 1, 1985

The title of this paper implies, and the text explicity states, that Sen and Spottiswood (1984) have found a new mineral species related to geocronite and jorganite. I believe that there is inadequate justification for this claim.The X-ray powder diffraction pattern reported by the authors exhibits a close similarity to that of geocronite, as stated by the authors, which suggests a close structural relationship at the very least. It is therefore reasonable to recalculate the results of the microprobe analysis reported by them to atomic proportions on the basis of the geocronite formula. This calculation, whether based on the formula used by Sen and Spottiswood (1984), or on one derived from a crystal-structure analysis (Birnie and Burnham, 1976), namely Pb18 (Sb, AS)11S46, with a total of 86 atoms, gives the results shown in Table 1.

Jan 1, 1985

The paper describes the procedure of data inquiry on the structure of mineral production in Austria and selected results. Goal of the endeavor was to gain more tangible insights into the mining industry as a basis for regulation balancing economical, ecological and social aspects.

Jan 1, 2006

By J. Craig Green

Companies mining for coal, oil shale, and minerals in the western US must often complete extensive geotechnical studies to satisfy federal and state regulations. The modern mining process is further complicated by the legal problems and liabilities associated with mineral rights and land leasing. Yet the study of water rights-unique to the West is often incomplete or ignored until the latter stages of mine planning. Water rights in the West are not adequately understood by many mining companies and their geotechnical consultants. Some firms, headquartered outside the western US, have not had to contend with the water supply problems of a semi-arid region. Water problems encountered by eastern mining companies, for example, are primarily water quality, drainage, and flood control. Even when water quantity is a problem in these areas, ownership and/or use of it is governed by entirely different legal and administrative concepts than in the West. Both legal and engineering issues have to be considered when studying western water rights. Legal issues, such as existence and title, must be addressed to insure that a particular water right is properly established and maintained. The exercise of a water right, however, often requires engineering analyses that focus on preventing injury to the properly established water rights of others.

Jan 8, 1981

By R. Allan Wallis

In the past mining engineers have tended to rely heavily on the advice of fan manufacturers in relation to fan equipment issues. A more adequate approach was advocated in a paper [ Wallis, 1965 ] submitted to the Eighth Commonwealth Mining and Metallurgical Congress held at Surfers Paradise, Australia during 1965. At that time Mount Isa Mine were in the process of installing 3 large 6096mm (20ft) diameter vertical axial flow surface fans of an advanced type [ Mathews et al, 1967 ]. The preliminary feasibility studies prior to preparing the detailed job specification for this project were extremely thorough with the result that it was possible to include detailed information and instructions in the document, ensuring the procurement of equipment that was satisfactory in all respects. Full advantage was taken of expert services provided by external organizations during the large coordinated multi-disciplinary exercise. My continuing activity and development in relation to the technology of axial flow fans is now at a stage where all known design and performance data are accessible through CAD programs [ Wallis and Kipp, 1987 ]. The extensive calculations that were necessary in 1983 can now be carried out in a mere fraction of the time, and with complete confidence. Model testing in order to validate the fan and duct design proposals is, in my view, no longer essential. The first of the computer programs enables a mine ventilation engineer to study a large number of alternative axial fan arrangements for comparison with the centrifugal alternative. By entering the volume flow rate, fan pressure and air density, he can then with ease, and rapidly, investigate the effect of various blading arrangements, downstream evasee area ratios, and hub ratios, on fan diameter and speed, with their related attainable fan efficiencies. This procedure had its origin back in the 60s when I was advising mining companies on new fan equipment. At that time such an investigation was quite lengthy and lacked the precision and completeness that is now available within the present programs. To obtain the major benefit from these outputs, it is most important not to be disconcerted by the three very important nondimensional parameters, namely, the tip flow coefficient (LAMt), the fan pressure coefficient (Kt or Kit), and the swirl coefficient (Es and/or Ep) as these are important when assessing the various design proposals. When seeking an understanding of the role and importance of each of these variables, ample help is provided in the user manual; the design recommendations are summarized in the help screens which are readily accessible within the design programs.

Jan 1, 1989

DD3-tunnels (PD BH's) ? Rotary coreholes 111no. (124) ? Percussion holes Ono. (37) ? Sampling (rock and soil) ? Soil and rock permeability ? testing ? BH Televiewer Surveys [ ]

Jan 1, 2007

By J. L. Weeks, K. F. Smith

IN order to determine the magnitude of thermal conductivity changes resulting from alloying vanadium with titanium and a few other elements, several sam~les were PrePared and measured. The thermal conductivity -values reported herein in Table I were determined with an apparatus previously described.' As in recently reported2 determinations on uranium and uranium alloys, whose thermal conductivities are in the same range as vanadium," the accuracy of the values was checked by using synthetic sapphire." The error in the measurement is estimated to be '-3 pct or 0.003 cal sec-1 cm-l "C-1, whichever is larger. The vanadium used in preparing the samples was the calcium-reduced type and was supplied by the Electro Metallurgical Co. as 99.6+ pct pure. All alloying elements used in the preparations were 99+ pct pure. A nonconsumable tungsten electrode arc furnace was used for melting the alloys and, without opening the furnace, each ingot was re-melted a number of times to insure homogeneity. The samples as prepared by the Armour Research Foundation were machined from as forged material without annealing. Acknowledgment The note is based on work performed under the auspices of the AEC. References 'J. L. Weeks and R. L. Seifert: Apparatus for the Measurement of the Thermal Conductivity of Solids. Review of Scientific Instruments (1953) 24, pp. 1054-1057. 2 J. L. Weeks: Thermal Conductivity of Uranium and Several Uranium Alloys. Trans. AIME (1955) 203, p. 192; Journal of Metals (January 1955). 3C. A. Hampel: Rare Metals Handbook. (1954) p. 593. New York. Reinhold Publishing Corp. Thermal conductivity of vanadium is given as 0.074 cal sec-1 cm- '°C-1 at 100°C. 4 J. L. Weeks and R. L. Seifert: Note Regarding the Thermal Conductivity of Synthetic Sapphire. Journal Amer. Ceramic Soc. (1952) 35, p. 15. At 70°C, K = 0.071 cal sec-l cm-l °C-1.

Jan 1, 1956

By S. W. Asihene, K. Osseo-Asare

The leaching and solution treatment operations used in the ammoniacal treatment of laterites depend on the ability to establish and maintain close stability relations between soluble metal ammine complexes and solid phases such as oxides, hydroxides, basic carbonates, sulfides and ammonium double salts. This paper presents a quantitative treatment of heterogeneous equilibria in ammonia/laterite hydrometallurgical systems, by means of several.types of hydrometallurgical phasedia- grams (e.g., Eh-pH, log [NH3 + NH4+] - pH, log [C02] - pH, log SO42-] - pH, log [Metal] - pH). Dissolution/precipitation phenomena associated with nickel and cobalt recovery and with magnesium scaling are discussed in the context of the phase diagrams.

Jan 1, 1979

By Trevor L. L. Orr

"AbstractThe background to the harmonization of geotechnical standards that has taken place in recent years in Europe has been the move to more economic and political integration following World War II that has led to the formation of the European Union. Prior to 2010 the standards used in the European countries for geotechnical design, investigation and testing and for the carrying out geotechnical work, such as the installation of piles, were the different national standards, which were not harmonized. The harmonization of geotechnical standards in Europe started in 1981 with work on a model Eurocode 7 for geotechnical design that led eventually to publication by CEN, the European Committee for Standardization, of the European Standard version of Eurocode 7 in 2004. In parallel with the work on Eurocode 7, a large number of associated harmonized standards have been, and are being, prepared by CEN and by the International Standards Organization (ISO) for geotechnical investigation and testing and for the execution of geotechnical works. Standards published by CEN must be adopted by the CEN member countries and all conflicting standards withdrawn. Hence all the CEN countries have adopted the same the harmonized text of Eurocode 7, but with National Annexes that allow national choice with regard to Design Approach and partial factor values. The adoption of Eurocode 7 and its associated geotechnical standards has removed the barriers to geotechnical activity in Europe due to the presence of different national standards. It has also enhanced the ability of EU firms to compete in the global market.Background to harmonization of geotechnical standards in EuropeThe initial moves towards the harmonization of geotechnical standards in Europe can be related to the economic and political developments that took place in the period immediately following World War II to revive the economies of Western Europe. Europe at that time was divided by a political and, in many places, a physical barrier, known as the Iron Curtain, into two very different and separate zones: communist in the east and non-communist in the west. In 1952 the European Coal and Steel Community (ECSC) was formed, linking 6 countries: Belgium, West Germany, France, Italy, Luxembourg and the Netherlands, and establishing a common market in coal and steel. The ECSC was the first international organization to be established on the basis of supranational principles whereby negotiated power is delegated to an authority by the governments of the member states. In 1957 the ECSC became the European Economic Community (EEC), also known as the Common Market in the English-speaking world, with the aim to bring about economic integration. With the addition of Denmark, Ireland and the UK in 1973 and Greece in 1981, followed by Portugal and Spain in 1986, this led to the formation of the European Union (EU) in 1993. East and West Germany were reunified in 1990, following the fall of the Iron Curtain in 1989. In 1995, Austria, Finland and Sweden joined the EU, and since then the numbers of countries in the EU has increased to 28, many of which are countries that were formerly behind the Iron Curtain."

Jan 1, 2014