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By B. M. Das, V. J. Hucka, J. H. Tu

Subsidence can cause serious damage to surface installations such as railroads, highways, pipelines, buildings and other facilities over a period of many years. Although total elimination of the effects of subsidence is difficult, the damage can be minimized through a systematic analysis. An example of such a study for reducing the effects of subsidence on pipelines is presented in this paper. Subsidence-induced stresses on a pipeline over some coal mining properties in Utah have been analyzed using a computer with graphics capabilities. The results are useful in predicting the extent of damages due to mining subsidence. In view of the gradual replacement of room-and-pillar mining by longwall with caving, this sort of analysis will become more and more important. In the next phase of this study the predicted results will be compared with the permissible stress levels on pipelines over actual subsided areas in an actual case.

Jan 1, 1989

By Victor Maksaev, Marcos Zentilli

"Abstract - The Domeyko Cordillera, the westernmost uplifted crustal block of the composite High Andes of northern Chile (20°S to 28°S) hosts a narrow N-S trending belt of Late Eocene-Oligocene giant porphyry copper deposits, which include Collahuasi, Chuquicamata, El Abra, La Escondida, and El Salvador. These deposits are spatially and genetically associated with the closing igneous activity along this range, prior to a 30 km eastward jump of the magmatic front in response to tectonic plate interaction. The porphyry copper deposits are also spatially associated with a major intraarc strike-slip shear system, the Domeyko Fault System. Although the tectonic uplift of the 3000 m to 5000 m high range has generally been assumed to be mostly Miocene in age, field relationships suggest that the Domeyko Fault System and tectonic uplift were active as early as the Eocene, coinciding with porphyry copper emplacement between 41 Ma and 30 Ma. Apatite fission track (FT) thermochronology provides both age data and a time-temperature history for rocks since they cooled below a temperature of ca. 125°C (equivalent to a depth of 4 km to 5 km under normal geothermal gradients) on their way to the surface during exhumation, or after a heating event. Apatite FT data from the Paleozoic crystalline basement of the Domeyko Cordillera indicate that at least 4 km to 5 km of rocks were eroded during exhumation of this tectonic block between ca. 50 Ma to 30 Ma (Middle Eocene to Early Oligocene), a time that immediately precedes and overlaps with the emplacement of giant porphyry copper deposits. The FT data constrain the age and duration of a period of crustal thickening and extensive erosion known as the Incaic compression, an event recognized in the Andes of Chile and Peru. Assuming that cooling was due to denudation alone, modelling of the FT data allow estimation of denudation rates between 200 and 100 m/My during this period. In contrast, exposures of pre-porphyry Paleocene intrusives on the western edge of the Domeyko Cordillera reveal apatite FT ages that are concordant with biotite 40Ar-39Ar dates, indicating shallow emplacement, fast cooling and negligible exhumation. The apatite FT ages of the Chuquicamata and El Abra porphyry copper deposits are only marginally younger than their 40Ar-39Ar dates, implying fast cooling/exhumation of shallow mineralizing systems (ca. 2 km to 3 km). Their FT time-temperature history is compatible with extremely low rates of exhumation (ca. 50 m/My) since about 30 Ma (Early Oligocene). This limited extent of erosion, due to exceptional aridity, has greatly contributed to the preservation of rich supergene enriched blankets above some of the porphyry copper deposits.A model is proposed, which is consistent with field relationships, geochemical, and geochronological data. High relative velocities and intermediate-angle oblique convergence between the Nazca and South American plates in the Eocene-Early Oligocene led to intra-arc transpression partitioned into reverse faults of opposing vergence and a right-lateral shear system (the Domeyko Shear System) localized along the magmatic front. Crustal shortening and thickening led to uplift within the Domeyko Fault System and to erosion of at least 4 km to 5 km. Crustal thickening deepened the zone of magma generation, and magmas accumulated in the lower crust, allowing small volumes to rise rapidly to shallow levels along transtensional domains of the regional shear system. A similar model of crustal thickening and shortening before and during porphyry copper emplacement in zones of transtension may also apply to the Miocene-Pliocene giant porphyry copper province of central Chile."

Jan 1, 1999

By Lawrence Devon Smith

"The concept of risk is well established in the mining industry. It is acknowledged when estimates of reserves are expressed as proven or probable, when mining and metallurgical recoveries are applied to the ore, and when contingencies are added to costs. However, it is difficult to provide a quantitative assessment of risk. The significant sources of risk in a mineral project and how these are addressed in project evaluations are discussed.The discount rate is examined as a fundamental means of reflecting risk in discounted cash flow evaluations. Current industry practice is discussed, and a methodology for the analysis of risk levels is proposed that assesses the constituent components of the discount rate: real interest, mineral project risks, and country risk.IntroductionThis paper examines the components of the discounted cash flow discount rate and proposes a method of estimating project-specific discount rates. The motivation for this work comes from experience of project evaluations in which owners and purchasers had agreed on virtually every aspect of the evaluation except how much the project was worth. Agreement was reached on reserves, grade, recovery, capital costs, operating costs, taxes, and, by combining these components, even on the final cash flow values. The only difference in opinion concerned the discount rate to be used in the calculation of the net present value. Depending on the life of the project, such differences of opinion can cause a variation of more than 50% in the value placed on a project! This is illustrated in Figure I."

Jan 1, 1995

By J. C. Taylor, J. A. Davis

"Existing environmental, health and safety regulations have forced pyrometallurgical facilities worldwide to drastically change some of their traditional methods of operation. In extreme cases, a number of facilities have been closed due to their inability to conform to these existing regulations. Tougher future legislation and government policy will lead to more stringent regulations and enforcement policies. The efficient control of smelter secondary emissions will, therefore, become critical to successful smelter operation.Much attention has been paid to the smelter primary process off-gas systems, including the development of new process designs to reduce the number of uncontrolled transfer operations. However, even the most modem smelter design requires control of its secondary contaminant sources, which mayor may not be directly related to the process operation.This paper discusses some of the potential secondary emissions encountered in many of the present process technologies. A few of the emission sources presented are only periodic in nature, such as those caused by maintenance procedures, but which have the capability of forcing smelter shut-down because of their direct impact on worker health and safety. The paper deals with a variety of topics relating to the efficient control, maintenance and monitoring of secondary emissions in copper, nickel, aluminum, magnesium and lead smelters, as well as in iron foundries and steel making facilities. Examples of the typical problems encountered in each of the above process operations are presented, including fume control at furnace tapping and slagging locations, metal transfer stations, tapping launders, and ladle transfer operations. The parameters for the most efficient design of fume capture systems, problems encountered with the handling and clean-up of certain collected emissions, and examples of successful solutions in particular operations are discussed."

Jan 1, 1994

By K. Hashiba, Y. Z. Liang, K. Fukui, M. Koizumi

"Efficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Development and modification of the rock drills based on test data are timeconsuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved. The objective of our research project is to construct a new realistic numerical model of continuous percussive drilling, which is based on the previous Okubo-Nishimatsu’s model. In this study, the parts of the previous model involved in stress wave propagation and attenuation were modified. The two models were prepared for HD712 hydraulic rock drill mounted on crawler drills and HD210 hydraulic rock drill mounted on drilling jumbos. Stress wave propagation was computed with the discretized one-dimensional wave equation. The calculated results were compared to the stress waves measured on a rod during percussive drilling. In both models for HD712 and HD210, the measured stress waves can be reproduced with the one-dimensional model of the same acoustic impedance as the actual piston, shank rod and rod combined with the CI+spring model as a rod joint. The calculated results indicate that the spring constant in the model of a rod joint needs to be set appropriately depending on drilling conditions. INTRODUCTIONEfficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Components related to the percussive drilling are a drill body, a piston, a shank rod, rods, rod joints, a bit and rock. The piston in the drill body is reciprocated by hydraulic pressure and collides with the shank rod a few thousand times per minute. Stress waves generated by the collision propagate and attenuate in the rods and rod joints, and then reach the bit. The bit penetrates and crushes rock. During percussive drilling, the components mutually affect each other and self-induced oscillation occurs. The number of blows and the rate of penetration are determined by the practical drilling conditions such as hydraulic pressure, thrust force, number of rods and mechanical properties of rock. Development and modification of the rock drills based on test data are time-consuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved."

Jan 1, 2015

By J. G. Mieczaniec

"A key element for a successful mining operation is the grinding circuit. It must be reliable, maintainable and must perform to or above design capacities for 95% of the time. Once chosen and installed major modifications are either prohibitive or very expensive. The selection of mills and drive system is probably the single most important decision made within the concentrator complex.Economic studies revealed that the optimum expansion for Lornex was a 68070 increase in plant throughput. This indicated that the new mill would have to be larger than the existing 32-foot mills.The Lornex ore has a wide range of hardness which has a great influence on mill throughput (Table 1). To smooth out the fluctuations, a blending program ha s always been in effect at the mine, coupled with ball charge control for the primary mills. As can be appreciated, an optimum balance is difficult to achieve. A sudden change to so ft ore with a high ball charge puts the mill into jeopardy with a constant speed drive.The blending philosophy would continue after the expansion, but with the addition o f a second primary crusher, it was envisaged to have the new mill process harder ore to maintain production targets. In theory, the new mill would have a proportionally larger ball charge than the existing mills.This scheme makes the new mill vulnerable for processing so ft ore for a fixed speed mill. Thus, variable speed seemed an attractive option.In early 1979 prominent mill manufacturers were invited to submit proposals for the new mill. Fixed and variable speed mills were to be considered with mill size ranging from 32-foot to 36-foot diameter. The proposals were to include the drive, ball charge, % critical speed, couplings, gears, etc. - the complete package. The recommendations were variable with most manufacturers submitting several alternatives. Recommended mill speed varied from 68% to 78% critical. The concept of variable speed was becoming more attractive, Lornex ultimately decided on a twin DC motor drive system for a 34-foot diameter mill.After start-up it was discovered that best throughput occurred at 78% mill critical speed or top speed of the drive motors. The motor speed range was adjusted upward from 186 to 200 rpm. Today the mills operate at 79% critical or a motor speed o f 193.5 rpm.Clearly the selection of the variable speed mill allowed the flexibility to optimize throughput."

Jan 1, 1985

By L. Hutton, S. W. Colley

"The release of soluble salts of base metals from acid mine pits and in the waste water from metal refiners is an avoidable source local pollution and contamination. Tightening of the regulations controlling natural resource extraction and industrial wastewater discharge is mandating the removal and recovery of metals from waste streams, and the remediation of contaminated sites. There is an economic incentive in recovering the valuable copper and nickel, as the value of the recovered metal can offset remediation costs and for high flow waste streams can be a source of income. Extraction of metals from waste streams by conventional Ion Exchange and chelation resins is widely practised, but has limitations on applicability in complex and dilute feeds due to the structure and properties of polymeric resin beads. Composite Advanced Ion Exchange (AIX) materials have been developed for the recovery and purification of base metals from base metal mining and metal processing industries. A silica-composite based resin has been developed for the selective extraction of copper from high iron containing feeds. This resin can be eluted with sulfuric acid yielding a copper stream suitable for return to solvent extraction or to electrowinning. We describe the development and application of the resin and process to two acid mine drain feeds of varying copper and iron concentrations, and show that the copper concentration can be considerably upgraded even at small scale with a final metal content of >95% copper.INTRODUCTIONWaste water with high sulphate concentrations, low pH and containing complex and variable mixtures of metals is an inevitable product in the mining, extraction and metal refining industries. One problematical water source is Acid Mine Drainage (AMD) which in addition to the metals of interest also contains a wide range of contaminating elements. Purge streams from metal refining are less complex in composition but contain significant quantities of the value metals. The typical treatment of such waste streams is treatment with lime to increase the pH of the water, precipitating the dissolved metals and sulphate as a sludge of mixed metal oxides/hydroxides and sulphates. The process is effective in producing a water stream that can be safely discharged but if there are significant concentrations of value metals such as copper, nickel, zinc then there can be a considerable loss of metal value."

Jan 1, 2016

By Simon B. Blancher, Malo Rousseau, Renato Contessotto, Thomas Wallmach

The Manganese division of the ERAMET group extracts manganese ore in Gabon and produces manganese alloys for the steel industry. ERAMET has an economic interest to maximize the ore throughput without reducing the lifetime of its manganese mines. This can be achieved by means of research and development leading to innovative ore beneficiation processes. For this purpose, the ERAMET research center has designed and constructed a new pilot plant for ore beneficiation by physical separation processes. This pilot facility was erected within an infrastructural and synergetic framework, including competencies in hydrometallurgy, pyrometallurgy, numerical modelling, analyses and mineral characterization that provide ideal research conditions. After laboratory scale tests, a pilot operation of beneficiation of low grade Mn ore (around 35% Mn) was carried out by jigging of the 1-10 mm fraction. This gravity separation process exploits density differences between the various Mn-bearing minerals such as pyrolusite and lithiophorite as well as gangue minerals such as silicates and iron-hydroxides. Enrichment leads to the production of a marketable product associated with a high mass recovery (53% for the jigging step). However, 20% of pyrolusite and 30% of lithiophorite are lost in the waste. Mineral characterization has shown microtextural complexities, but grinding the ore to approach the liberation mesh was not an option due to commercially defined constraints given by the ferro-alloy industry. Recovery of the Mn-bearing minerals or adjustments of the feed grain size (6.3-10 mm) are two potential areas of process improvements identified by means of Qemscan® mineral characterization. This paper details the process tested on a pilot scale (0.5 t/h), which has led to a significant increase in the beneficiation of a low grade Mn ore.

Jan 1, 2016

By P. M. Tyroler, W. J. Thoburn, M. R. Alberty

"An initial test of this unique application demonstrated that hot gunned refractory would adhere satisfactorily. Subsequently, it was found that the proportion of material sticking during application increased with increased vessel temperature and when a mix containing pitch was used. About 75 per cent of the latter type adhered when it was applied at 1600°C.TBRC availability increased from an historical average of 62.5 per cent to 64.7 per cent during four campaigns when hot gunning was routinely practiced. Refractory cost was about 20 per cent less than that anticipated without gunning. Average parameters per campaign with gunning ranged as follows: 90 to 108 heats, 10 to 37 applications and 1.4 to 2. 7 hours per application. Prior to gunning, the average number of heats per campaign was 73.IntroductionThe Top Blown Rotary Converter process at Inco's Copper Cliff Nickel Refinery converts copper-nickel-sulphur concentrates to a material suitable for carbonyl refining (1),(2).Operating conditions are particularly hard on refractory. Batch cycles finish at temperatures up to 1650°C, with occasional excursions over 1700°C. New heats are then usually initiated immediately and the refractory is subjected to intense thermal shock from the cold feed. Temperature cycles are also introduced three to four times during a heat when the process is interrupted for scrap charging, temperature measurement or sampling.Abrasion wear results from rotation of the converters at speeds up to 15 RPM and from agitation of the bath with supersonic-velocity oxygen. Mechanical damage also occurs when chunks of scrap or solid matte are processed. Chemical corrosion is also present, as we know from our own laboratory work(2) and reports of operations elsewhere. As a consequence, refractory material and installation form a very large proportion of the converter plant costs. Equally important is the loss of converter availability during rebricking; this significantly reduces plant capacity."

Jan 1, 1981

By M. Silver, R. H. McCorkell

The effects of covering materials on radon emanations from uranium mine mill tailings were investigated. Granular materials with air in the spaces allow radon to pass freely. Moist covers of compost or soil decrease radon emanation from tailings. Water-saturated covers were more effective, and freezing the tailings with these covers further decreased radon escape. Water itself is a poor radon barrier probably due to circulation. Plants had no effect on radon emanation through soil. Although radon diffusion through water-saturated powders appears to be very slow and inefficient, about 25% of the radon escaping from the grains in water-saturated tailings diffuse to the surface and emanate when no cover is present. The radon escaping from tailings through covers of water-saturated compost or soil is no more than could be accounted for by radon produced in the covers themselves.

Jan 1, 1987

By Randolph A. Pax, Brian Cornish

The operation of grinding mills in an ore processing circuit is supported by monitoring the input and output variables. These can include the feed ore size distributions, ore feed and water addition rates. The outputs can include the discharge undersize density, oversize tonnage rate and the P80 of the discharge. The grinding mill performance is judged by the power draw, recycle rates and discharge grind size. Conditions inside the mill are inferred from loads cells or bearing pressures and past histories. An overall noise value is sometimes used to evaluate the load as well as the occurrence of excessive impacting of steel balls onto the liners/lifters of the mill. This paper presents results of the internal behaviour of a mill using non-contact stationary microphones located close to the mill outer shell (Pax, 2012). The noise generated by a mill can be attributed to a number of events that occur inside these mills and suitably analysed can provide real-time determinations of in-mill behaviour and can provide powerful insights into the operation of the primary comminution tumbling mills. The acoustically determined signals including a specific 'steel' signal, water hold-up, integrated area together with a classification of impact events. Specific results from case studies will show information of the trajectories inside a mill, steel to rock ratio as well as rheology effects. By incorporating a self-consistent understanding methodology for the in-mill processes from an array of microphones, the information can be used to diagnose the dynamic conditions inside a mill.

Jan 1, 2016

By R. H. McCorkell

Measurements of radon in air and aqueous solutions can be affected by leakage from vessels in which samples and standards are kept and by absorption and later release of radon by the materials of these vessels. The author had received various oral communications concerning the se processes : e.g ., that natural rubber and greases absorb large amounts of radon, whereas silicone rubber and grease do not; and that radon is readily lost from polyethylene bottles and that inverting glass bottles containing aqueous samples reduced radon loss from them . However, the results of actual tests and quantitative data showing these effects were not available. For this reason, it was necessary to make numerous measurements of the leakage and absorption of radon in the course of designing apparatus and methods for measuring radium and radon concentrations. It was thought that the data obtained might be of use to others, and consequently they are compiled in the present note .

Jan 1, 1980

By Michael L. Free, Zongliang Zhang, Joshua M. Werner

In the copper electrowinning process, short-circuiting between the anodes and the cathodes is a critical problem that changes the current allocation among local electrodes and reduces the current efficiency significantly. Possible reasons for the short-circuiting include the improper alignment of the electrode, bent electrode, and nodules on the cathode surface. In typical tankhouses, there is often a time between shorting and harvesting as well as between shorting and clearing. Therefore, it is inevitable to have short-circuiting affect the operation performance in practical electrowinning operations. However, one key piece of missing data is the actual measurements of the current efficiency as short-circuiting is approached and allowed to continue. Consequently, short-circuiting tests that allow tracking of electrowinning parameters before and after short-circuiting were performed in a laboratory scale Cu electrowinning cell. In the tests, the electrode spacing change, the mass of electrodeposited Cu, the deposition morphology, and the current allocation as well as the current efficiency before and after short-circuiting were studied. Results show that the short- circuiting affects the current allocation and the current efficiency significantly. Moreover, it changes the Cu deposition on the short-circuited cathode and therefore causes problems for Cu electrowinning. INTRODUCTION Electrowinning (EW) is commonly used for copper production around the world, with a rated production from 120,000 to 200,000 tons per year per operation (Wiechmann, Aqueveque, Henríquez, Muñoz, & Morales, 2014). In Cu electrowinning, Cu ions in the electrolyte are reduced on the cathode surface as metallic copper with a DC current, while on the anode, a counter anodic reaction occurs with oxygen gas generation (Werner, Zeng, Free, Zhang, & Cho, 2018; Zhang, Werner, & Free, 2018; Zhang, Werner, & Free, 2018). In copper electrowinning, an average current density of 200 to 400 A/m2 is applied to the electrowinning cell (Wiechmann et al., 2014). As the Cu deposits on the cathode, the distance between anode and cathode reduces and most of the time, short-circuiting forms between some anodes and cathodes in a large tankhouse containing thousands of electrodes, reducing the current efficiency and increasing the energy consumption significantly. The current efficiency in well-run copper EW operations is typically above 90 %. Most of the unused current is wasted through short circuits, stray currents, and by-byproduct formation (Davenport, King, Schlesinger, & Biswas, 2002; Wiechmann, Vidal, Pagliero, & Gonzalez, 2002; Wiechmann, Morales, & Aqueveque, 2010). Usually, in the tankhouse, the short-circuiting increases the current in the involved cathode by up to 1500 A (Wiechmann et al., 2010). Multiple reasons can cause the short-circuiting in the cell, and the most common reasons include the uneven current distribution among cathodes, tilted electrodes, bent electrodes, and nodules formed due to the large deposition roughness. Recognition of this challenge in the Cu electrowinning process has led researchers to perform many investigations on approaches to avoid and reduce the short-circuiting in the cell. A series of research investigations have been conducted to develop and improve a new type of intercell bar for Cu electrowinning (Wiechmann et al., 2002; Wiechmann, Morales, Aqueveque, & Burgos, 2007; Wiechmann, Morales, & Aqueveque, 2009; Wiechmann et al., 2010; Wiechmann et al., 2014). The associated test results show that this new design limits the occurrence and magnitude of short circuits and allows operation at higher current densities. Sandoval, Clayton, Dominguez, Unger, and Robinson (2010) stated several keys to control short circuits, such as maintaining the straightness of the cathode, removing “edge hair” from the cathode starter, and maintaining electrode alignment in the cell. Prengaman and Siegmund (1999) from RSR technologies developed a new Pb-Ca-Sn anode to prevent the anode deformation, thereby reducing the short-circuiting in the Cu electrowinning cell. Although the negative effects of short-circuiting on the Cu electrowinning have been recognized, and various investigations have been conducted to address this issue, the actual measurements of the electrowinning behavior and performance as short-circuiting is approached and allowed to continue are seldom reported. However, in typical tankhouses, there is a time between when shorting occurs and harvesting/clearing are performed. One key factor in determining the harvest time is the frequency of shorting. Consequently, we have performed short-circuiting tests that allow us to track electrowinning parameters before and after short-circuiting.

Jan 1, 2019

By R. B. Stein

"Countercurrent decantation circuits(CCD) are often employed in hydrometallurgy to effect solids-liquid separation in combination with a barren solution wash to reduce losses of valuable solution component(s) from the tails. Bechtel Corporation uses its BEMSIM flowsheet-modelling PC computer program to simulate a CCD circuit where the ""dirty"" wash solution contains significant amounts of soluble components. An algorithm successfully models this condition and is simplified to a single expression when the wash solution is a ""clean"" solution containing no solubles. The CCD calculation module is compared to operating data from uranium and nickel-cobalt CCD circuits.IntroductionHydrometallurgical process schemes have often relied on countercurrent washing methods to reduce soluble losses of valuable product in the tails. Commonly used equipment to effect this operation is a CCD circuit of N thickeners in series, where a slurry is fed to thickener I and a wash solution to thickener N; clear pregnant solution overflows thickener I and washed tails exit as underflow from thickener N. CCD circuits of this type are typically employed when the solids tend to slime heavily and where a filter is not economic.A typical CCD circuit usually employs from two to five thickeners and can employ either a ""clean"" washing solution of, say, pure water or else the hydrometallurgical circuit may generate a ""dirty"" barren solution containing an appreciable amount of soluble component which may be advantageously returned to the process as CCD wash solution. Various authors have treated the case for clean washing solutions (Svarkovsky 1977, Merritt 1970). For the case of dirty wash solutions, an algorithm has been developed to enable efficient modelling by the BEMSIM computer program, because the need for an accurate method to calculate soluble losses is required when performing an economic trade-off analysis of the value of product lost in the tails as a function of the number of thickeners."

Jan 1, 1990

By Philip Thwaites

"Automatic flotation control in varying degrees of sophistication is practiced at a number of concentrators throughout the world. Practically, the variable conditions in the flotation circuit and the difficulty in maintaining accurate instrumentation information all add to the complexity of automatic control.Further development at the Kidd Creek concentrator has resulted in a 3075 mtpd copper flotation circuit capable of running twenty-four hours a day under the direct control of an optimizing supervisory computer.Three main streams, continuously monitored by an XRF analyzer, supply circuit information to the optimizing computer. Circuit efficiency calculations (from smelter contract terms) and target setpoints allow the computer to determine the economic optimum direction to move the circuit based on the grade/recovery relationship. Circuit manipulation is accomplished by precise pumping of collector and frother reagents together with accurate control of flotation bank pulp levels. The former uses computer controlled diaphragm pumps and the latter is achieved by control loops utilizing a float type level transmitter, variable position dart plugs and a process computer working to setpoints determined by the optimizing computer.The development of a fully automated flotation circuit is by no means complete, but increased knowledge and major hardware improvements have allowed its progression to a higher level of sophistication.IntroductionThe Kidd Creek concentrator is located twenty-six kilometers east of Timmins, Ontario, within a metallurgical complex including a 109,000 mtpy zinc plant and a 59,000 mtpy copper smelter and refinery. The concentrator treats two ore types, a copper-zinc ore and a copper-silver-Iead-zinc ore, at a combined rate of 4,500,000 mtpy. Flotation of the crushed and ground ore yields copper and zinc concentrates from the copper-zinc ore and copper, lead and zinc concentrates from the copper-silver-lead-zinc ore."

Jan 1, 1983

By D. G. Osborne

"The paper describes current 'tools' available to the coal preparation engineer for carrying out the evaluation of data, process design, selection of equipment and layout and design of coal preparation plants.Laboratory and pilot-scale equipment is widely available and test data can be used to provide valuable design information regarding capacities and sizing for specific applications. Pilot plants, unless they fit closely to the basic design envisaged for the eventual commercial plant, C(In often provide only limited useful information.Computing aids such as equipment simulation, plant modelling, etc. are becoming widely applied for establishing design criteria and investigating flowsheet options . Other computer tools such as computer-aided design systems are taking over some of the time-consuming tasks of detailed layout and design and estimation of quantities, etc. and providing the means for detailed examination of more than a single option.Besides computer modelling there is also physical modelling of plant buildings, plant sites and entire proposed mining areas; the former can be especially useful in finalizing design and threading' pipework and electrical reticulation systems through the plant without the resultant risk of impairment of flow, obstruction or wastefulness. Not the least of the benefits of plant models is the assistance provided for training new operating and maintenance staff."

Jan 1, 1985

By J. C. Ingles

"A new technique is in the process of revolutionizing inorganic chemical analysis. Galled atomic absorption spectrophotometry, it combines the use of a special light source, a flame, and the equipment of conventional spectrophotometry, to provide a quick, reasonably accurate method for the determination of a large number of elements.This paper outlines the principles on which it is based, describes the commercial instrumentation"" available for exploiting it, and. summarizes current applications in process metallurgy."

Jan 1, 1966

By Tibor Horvath

Dust abatement is possible on bulk materials, whether conveyed or stockpiled. Minimum (ppm) quantities of chemical additives can efficiently and rapidly control dust of conveyed substrates with no effect on floatation chemistry. Top coating of large surface areas can control surface dust and wind erosion. Environmental and toxicity impact must be considered in any treatment, especially on areas with percolation runoff, leachates, or limited containment. The most effective dust control is preventing release of substrate fines rather than trapping and removing air borne dust. Techniques to prevent release of fines from conveyed substrates will be discussed. Dust control dynamics are a very complex combination of solid phase physical and chemical interactions between the substrate and the fines. ?Smart Technology? products permit dust abatement of stockpiled substrates and tailing fields with no environmental impact. Using ?Smart Technology?, the dust abatement products remain active and can re-seal damaged areas. Efficient, low environmental and toxicity impact, dust control will be demonstrated through case studies where these principals have been applied.

Oct 1, 2010

By Noel G. Thomas

"This paper will identify where the industry is heading with iron· ore in the next ten years. From a customer's point of view, an indication of the changing, yet expanding, market will be made. This will progress further into the most likely changes in chemical and physical requirements of the ore products. No definite target can be set for 1990, but the logic from the direction of the changes will be established.IntroductionThe tonnage and quality of iron ore produced in the eighties will be heavily influenced by energy and investment considerations. That's not a great pronouncement, but this paper will explain how these two factors are :(I) influencing a disproportionate growth of electric furnace capacity and a greater use of scrap for iron units, in place of Iron ore;(2) influencing chemistry specifications; and(3) causing extensive examination of ore agglomerate form. Inflating investment costs are emphasizing the need for more productive blast furnaces, and the iron ore burden is under heavy examination as to how it affects productivity and coke rate."

Jan 1, 1981

By C. G. Anderson

As the global demand for copper and gold steadily increases and the need for environmentally sound processing also grows, successful hydrometallurgical treatment of enargite (Cu3AsS4) concentrates has come to the forefront. This type of concentrate contains considerable arsenic so that successful arsenic fixation, for example as scorodite, is of the essence. This paper outlines the successful application of low temperature and low pressure nitrogen species catalyzed (NSC) hydrometallurgical pressure oxidation of enargite concentrates. The successful stabilization of the arsenic as an iron arsenate compound is discussed. Also, the use of experimental design software is highlighted as a process application and optimization tool.

Jan 1, 2006