Search Documents

By Gunnar Eriksson

Computer simulation has become an everyday practice in thennodynamic and materials research. Advanced thennochemical algorithms take into account heat transfer effects and salient reaction kinetics when applied for process models. In particular, the combination of mass transfer or overall reaction rates with multi-component Gibbs energy minimisation provides an effective tool for simulation of industrial thennochemical processes and processing of materials. In this work the combination of rate factors with the Gibbs energy technique was studied by using the novel program ChemSheet, which operates through Microsoft's Excel® spreadsheets. Such processes as, for example, CVD of pure silicon production, titania pigment manufacturing, vapour pressure of Mercury in amalgams (in Hg-Iamp manufacturing) and melting behaviour of low-temperature alloys have been modelled. Provided that the thennochemical data is available simulations can be performed with any thennodynamic system. The calculation can be performed as an affinity study without a particular reactor model or with a specific reactor scheme.

Jan 1, 2001

By M. J. Santofimia

Multiphase microstructures in steel have been intensively studied in the past years, but combining non-equilibrium phases still offers a great potential for further development of these steel grades. Thus, improved combinations of mechanical properties can be obtained with microstructures formed by bainite or martensite, in combination with retained austenite. In particular, microstructures on the basis of carbon-depleted martensite and retained austenite can be produced by the very promising production process named quenching and partitioning (Q&P). Originally, the Q&P process aimed to avoid the formation of bainite during the heat treatment. However, the process does provide the possibility for (carbide-free) bainite formation during the partitioning step, i.e. in the presence of martensite. This article evaluates this approach, considering thatthe formation of bainite from austenite is strongly influenced by the preceding formation of martensite. Although the accelerating effect of the presence of martensite during bainite formation has been observed, it is not yet fully understood, and experimental and theoretical studies are being performed in order to come to a more effective exploitation of these processes for the formation of multiphase microstructures.

Jan 1, 2013

By Jean-Pierre Côté, Alexandre Noiseux

"Hatch and ArcelorMittal Mines Canada have combined their expertise to develop a dynamic model of the latter’s Iron Ore Pellet Plant in Quebec, Canada. This model was used to predict the benefits of different expansion projects, as well as asses the best implementation sequence.Two modelling tools were used: a discrete-event simulation software used to develop the dynamic model of the Pellet Plant and an in-house process simulator. The latter was based on operational data and known behavior of the process, and was calibrated with historical data gathered under different operating conditions.The results of the process simulator were used as input values for the dynamic model, which included all of the operation steps of the pelletizing process, from concentrate beneficiation to baking of the pellets. The model has been validated by assessing its capacity to represent adequately the operation of the plant during a 20-month operating period. It was able to reproduce the plant capacity within a precision of 1.2%.Simulated “what-if” scenarios allowed quantifying the production increase associated with the addition of new equipment such as ball mills or balling discs, implemented individually or in combination. Results revealed a potential 10% increase in the annual plant production by adding additional equipment in the two most limiting sectors of the plant, grinding and agglomeration. The simulation results made it possible to quantify the synergistic effect of two projects on plant throughput; the model showed that the combination of two projects resulted in a greater production increase than the sum of the same projects evaluated individually.Now that it has proven reliable, the simulation tool can readily be used by ArcelorMittal Mines Canada process engineers to perform simulations for equipment optimization, and to evaluate the impact of various operating parameters such as equipment availability and tonnage, product mix or concentrate quality. This work showed that a reliable model can be developed based on known parameters in combination with the proper integration of the process knowledge."

Jan 1, 2010

By Nural Kuyucak

Several thousand years ago, metallurgists discovered that by combining two relatively soft metals, copper and tin, they could make a new material, bronze, that was stronger than either metal separately. Bronze and other alloys show how different materials can be integrated to create something new and better. Today?s mining industry can likewise find benefit in an integrated approach to managing the external impacts it has through its waste materials and its use of water. Just as using bronze gave ancient nations an economic and military advantage, mining companies can gain competitive advantage through finding better ways to manage water and waste. Trends pushing this include: ? Environmental ? Regulations on water-taking and the quality of discharged water are becoming more stringent. Net zero discharge requirements are often imposed by regulators. Mining companies also come under pressure to manage environmental impacts of mine waste, including minimizing the area occupied by waste and seepage amount resulting from infiltration of water from a smaller surface area. ? Social ? Particularly in arid parts of the world, there are multiple possible uses for each gallon of water. Local residents do not want to see a reduction in supplies of water for agricultural, domestic, manufacturing and other purposes. They get suspicious about any potential impact of water being mixed with their water reservoirs if it comes from a mining site, even if it would be treated. Such suspicions may cause conflicts among the stake-holders and delays in project approval processes.

Jan 1, 2009

By Sharon L. Eyer

"FTIR spectroscopy is employed to define mineable ore deposits based on exploration samples. The RAMBO (Robotic Assessment of Mineable Bauxite Ore) technology is operating successfully at an alumina refinery in K winana, Australia, for assessment of a number of critical ore attributes including available alumina, extractable organic carbon and total iron. Classical methods of analyses for these properties require laboratory-scale digestion of alumina ore (bauxite) or XRF analyses.Multivariate calibration is used in the RAMBO system to generate robust mathematical models that are able to estimate classical data from FTIR spectral data. Furthermore the models can highlight regions of ore that are relatively unusual. Unusual ore may be investigated for potential impacts on refinery processes well in advance of mining.The components of the technology are described and some results for an example application (bauxite) are presented. Challenges and difficulties are discussed. The potential to apply the technique to process control is introduced."

Jan 1, 1999

By K. E. Brown, T. D. Murphy

At Monterey Coal's No. 1 Mine in central Illinois, it became necessary to predict if the sulfur content of individual trainloads of coal would exceed a contract sulfur maximum. Using geostatistics and Monte Carlo-type simulations, a forecasting procedure was developed to meet this need. The developed procedure predicts the monthly, mean sulfur content of the coal shipped and the probability of individual shipments exceeding the contract limit. During the first five months of using this procedure, the forecasted, monthly mean sulfur value was within 0.03% of actual. This represents a significant improvement over the inverse-distance, gridding-based, forecasting used previously.

Jan 1, 1994

By Fred L. Stanley, Ricky Q. Honaker, Michael J. Mankosa

Spiral concentration has gained a great deal of popularity as a cheap, effective method for recovering fine coal (8x100 mesh). Typically, 6-turn, wide-profile spirals are used in either a single pass, open- circuit configuration or in combination with a middlings retreat circuit. Recent work conducted at Carpco, however, has indicated that a split feed scenario and/or hydraulic classification in advance of spiral concentration offers significant advantages in both capacity and metallurgical performance. In addition, it has also been shown that the apparent density separation which naturally occurs in a hydraulic classifier provides significant up-grading in terms of pyrite and ash rejection. The results from this study will be presented in comparison with those obtained from open-circuit spiral testing.

Jan 1, 1995

By Hatherly P, Luo X, Balusu R, Gale W

Ongoing, collaborative research between CSIRO's Exploration and Mining and Strata Control Technology has resulted in a better understanding of rock failure mechanisms around longwall extraction. Failure has occurred further ahead of the retreating face than predicted by conventional longwall geomechanics theory. In some cases significant failure has been detected several hundred metres ahead of the face position with demonstrated influences of minor geological discontinuities. Shear, rather than tensile failure has been the predominant failure mechanism in the environments monitored. Validating technologies of microseismic monitoring and new face monitoring techniques have assisted the development of predictive 2D computational modelling tools. The demonstrated 3D consequences of failure has assisted in the ongoing direction of the project to further investigate these effects.

Jan 1, 1998

By H Hy÷tyniemi

In this paper multivariate data analysis performed on a new multi-camera system implemented to zinc flotation circuit of PyhSsalmi mine is presented. Image-analysis-based system was developed to take advantage of the commonly known fact that the changes in the flotation process are reflected to the visual appearance of the froth surface. Most often the changes are seen first in the froth and later in other process measurements. The image variables are already utilised in closed loop control and considerable savings are achieved with the current setting, but the results coming from the separate cells are used individually. This is clearly not the optimal way to take advantage of the many measurements coming from different locations of the process. A better approach would be for example to use the measurements coming from the early stages of the process to predict the behaviour (or improve the quality of measurements) in the later stages. The methods described in this paper are aimed to improving the situation in this sense.

Jan 1, 2005

By Wright JK, Turner RE, Batterham RJ, Morrison AL

Simulation can play an important role in the design, optimization and control of complete industrial processes, the most appropriate method depending on the particular application. Most commonly, process models or simulators are means of representing the process which are either purely mathematical or physical. Mathematical models, however, almost invariably need to be based to some extent on experimental data or require experimental verification before they can be used with confidence. Ways in which experimental and mathematical modelling techniques can be combined to best effect are discussed, with reference to the simulation of iron ore induration and direct reduction processes. A novel method is presented for the simulation of direct reduction shaft furnaces. Small scale apparatus has been developed in which ore or pellet samples are subjected to the changing environment of the industrial process. The time dependent conditions (solid temperature and gas compositions) are provided by a mathematical representation of heat transfer and the conservation of mass and energy in the process Simulated.

Jan 1, 1986

By M. ]. [Mohkam

The paper describes the features of the problems encountered and the countermeasures taken for two different tunneling projects. Where, slurry shields were used to excavate, in soft heterogeneaous water-bearing grounds, tunnels passing at very low cover beneath existing foundations of H.T. electric pylons, underground structures and major utilities. In order to avoid any ground failure and/or damage to the existing structures, one option was ground treatement by grouting or freezing technics. However, it was judged that, based on previous experiences, excavation with slurry shield could be carried on securely using an appropriate slurry enriched with polymers and applying a well determined pressure at ground face. A three dimensionnal limiting equilibrium analysis model was used to determine proper confinement pressures. And, the appropriate slurry compositions were stabilished based on laboratory test results. The tunnels were excavated successfully, no ground failure was experienced, and the maximum settlement recorded (on pylons) didn't exceed 3 mm.

Jan 1, 1991

By K. W. Harris, K. A. Perry

Underground coal mines beneath Black Mountain in the Harlan County district of the Central Appalachian coalfields have an extensive history of bump events, which yields an elevated probability for significant injury or fatality to underground miners. According to Mark (2009), Harlan County has had the greatest concentration of deep-cover retreat mining in the United States. Combined with the extensive multiple seam mining history, room-and-pillar coal bumps have had a disproportionate impact on coal operations in this region. The Harlan seam, one of the principal, economically recoverable coalbeds exploited beneath Black Mountain, has a significant burst history that extends into modern times. A numerical investigation using the LaModel software of 17 bumps that occurred at the same mine in the Harlan seam was conducted and used to create a calibration methodology which serves as the quantitative basis for current and future numerical efforts in an adjacent mine exploiting the same reserve. In addition to this numerical study, a qualitative assessment of the geologic factors that are believed to contribute to the bump potential was completed. Combined with stability prediction using the numerical basis, these geologic factors will be used for recognition of high bump potential areas with the goal of reducing the potential for future bumps, helping to ensure the highest level of safety and productivity for underground personnel.

Jan 1, 2016

By J. Patrick Powers, Joel Miller, Arthur B. Corwin

A combination of a slurry trench with dewatering successfully controlled groundwater for a large sloped excavation immediately adjacent to the Arkansas River. The Murray Hydro Electric Project required excavation through sand and gravel to bedrock, 85 feet below high water in the River. The perimeter system of deep wells pumping up to 25,000 GPM (1,600 1/sec) lowered the water level to 15 feet (4.6 m) above bedrock. A short soil/bentonite slurry trench near the toe of the slope cut off the residual head. The method cut six weeks from the critical path. Design of the slopes and the dewatering system demanded high safety factors because of risk to existing Lock and Dam No. 7. A localized pocket of soft organic clay was supported by a rock filled bolster. A major flood event was successfully withstood. The method can be applied to large civil excavations and open pit mines.

Jan 1, 1989

By Karina Forster

Open stope design depends on the ore body geometry, loading conditions and rock mass properties to estimate stope dilution and ground support requirements. Rock mass conditions for design primarily rely upon estimates of well established rock classification systems. Many sources of data exist for obtaining estimates for these rock mass classification values which include core logging, geotechnical mapping, geological mapping as well as linking one classification system to another through the use of empirically derived equations. The extent of mapping coverage can also vary significantly based on the data collection technique. This paper proposes an approach where individual components of rock mass classification systems are collected by the different available data collection techniques. Data from different rock types are also considered separately based on their alteration characteristics and general observation products. Data from the Cameco Corporation Eagle Point Mine is presented and an approach is outlined for obtaining average representative classification values for stope hanging wall characterization. The effectiveness of this approach is demonstrated through the analysis of a data base of hanging wall dilution information.

Jun 1, 2012

By G. R. Baiden

This paper discusses the application of Load-Haul-Dump (LHD) machine teleoperation in combination with a guidance system for single operator control of multiple IJIDs. A system accomplishing these goals has been tested at Copper Cliff North Mine of Inco Limited. This development uses a high-speed, high-capacity production network to teleoperate an LHD during loading and dumping by using 3D video and radio remote control. Following loading, the operator dispatches the LHD using an automatic guidance system to traverse the drifts to the orepass. Remote dumping is done at the ore pass and then the machine returns to repeat the procedure. This has significant productivity gains and improvements in safety. Productivity is improved because operators are involved only in the loading and dumping part of the process. This frees the operators to utilize their time more effectively, loading or dumping a particular machine, while other machines with guidance systems continue to work travelling and/or automatically dumping ore in the ore passes. Safety is improved as the operator is located on a remote control station. Automatic dumping will be incorporated as a future development.

Jan 1, 1994

By S Khadhraoui, T Yusuf, C Kirmse, E Hecker, R Degel, A Akouch, N Borowski, M Reuter

For an optimal design and control of metallurgical processes, a deep understanding of the thermodynamics of the governing reactions is required. Modelling the thermochemical behaviour of those reactions is complex, as it involves multi-component and multi-phase systems. For this purpose, thermodynamic computing systems such as FactSage™ (Bale et al, 2016), which combine Gibbs energy minimisation routines with large databases of optimised thermodynamic data of solutions and compounds, have been used within the SMS group GmbH. Recently, the successful integration of those thermodynamic computing systems into the digital platforms of SMS has been achieved through ChemApp, which made running complex thermochemical calculations in Python-integrated development environments possible. ChemApp is a programmer’s package for thermochemistry and incorporates the Gibbs energy minimiser of FactSage™ as reported by Petersen and Hack (2007) as well as by Zietsman and Petersen (2018). The digital platforms link the fundamental and the industrial aspects together and can be applied as a process advisor, or for the evaluation of the environmental footprint and the economic implications of different process routes, as discussed by Reuter (2023). Two examples illustrating the progress of the developments in this regard will be introduced: 1. The Tilting Refining Furnace (TRF) for copper scrap recycling and refining to anode copper (the BlueControlApp). 2. Dephosphorisation control for the oxygen steelmaking process (Basic Oxygen Furnace (BOF)).

Jun 19, 2024

By Juliana Gonçalves Pohlmann, Guilherme Liziero Ruggio da Silva, Eduardo Osório, Claudia Caroline Teixeira Barbieri, Hector Alejandro Picarte Fragoso, Antônio Cezar Faria Vilela

Este trabalho teve como objetivo avaliar a combustibilidade de misturas carvão nacional, do estado do Rio Grande do Sul, para injeção em altos-fornos. O estudo foi realizado através de ensaios de combustão no simulador de PCI do Laboratório de Siderurgia da Universidade Federal do Rio Grande do Sul (LaSid/UFRGS). Os carvões empregados foram carvão nacional, carvões importados e misturas destes tendo o baixo volátil importado como base. Os resultados mostraram que a combustibilidade medida pelo burnout foi proporcional ao teor de matéria volátil. Foi verificado efeito sinérgico nas misturas, onde o carvão alto volátil (CC) exerceu uma maior interação com o carvão base baixo volátil (CA) do que o carvão brasileiro (CB). Uma adição de 10% de CC proporcionou uma eficiência de combustão na mistura CA:CC superior a uma adição de até 30% de CB na mistura CA:CB. A partir de 30% de CC e 50% de CB não houve variação significativa nas eficiências de combustão em relação aos carvões individuais CC e CB.

Oct 1, 2019

By Szpindler G

The results of pot-furnace tests with 35 bituminous coals from 20 seams in New South Wales and Queensland were used to establish the relationship between coal properties, as determined by standard laboratory tests, and the combustion process. The rate of combustion is influenced chiefly by the expansion of the fuel bed, but this cannot be accurately predicted from the crucible swelling number of the coal.The effects of various other factors, such as calorific value and ash yield, were investigated and statistical analysis of the results shows that the coals could be classified satisfactorily according to two experimentally derived parameters, namely heat-release rate at an air flow rate of 260 lb/sq.ft/hr and air flow rate giving stoichiometric combustion. The grouping obtained is shown to be related to ash yield and swelling number.INTRODUCTIQNThe rate of heat release from the fuel bed of a travelling grate stoker and the efficiency with which the heat is used depend upon the design and method of operation of the furnace as well as upon the properties of the fuel. It is difficult to draw general conclusions concerning the influence of fuel properties from tests on a single stoker installation. In the pot-furnace test, on the other hand, a part of the same combustion process as occurs on a travelling grate is carried out in isolation, uninfluenced by furnace design variables, and consequently the effects of coal properties and of the method of pretreatment can readily be demonstrated.While the combustion pot provides a rapid method of assessing the combustion characteristics of a fuel during the ignition and burn-out stages under standard conditions, and of predicting changes in performance with changes in fuel or in air flow rate, it is unable to simulate certain features of furnace design and operation. Data from combustion pot...

Jan 1, 1962

Although most N.S.W. coal mines contain large amounts of combustible materials such as coal and timber, the introduction of mechanisation has extended the range of combustible materials now found underground. The role of combustible material in a fire is not clearly understood and as a result the assessment of these materials for flammability by small and large scale tests is doubtful. Extensive research has been carried out on the toxic and irritating gases evolved during the combustion of plastics. However, most autopsies report death due to carbon monoxide inhalation because the combined toxicity of smoke and fire gases is unknown.

Jan 1, 1981

By Raymond S. Weimer

Of the several characteristics of a coal that influence its suitability for use in a given piece of burning equipment, the clinkering and slagging characteristics of the ash of the coal are highly important. They determine the maximum rate at which the coal may be burned on a stoker or in pulverized form without difficulty from damage to metal parts, from erosion of refractory walls, or from stoppage of gas passages by accumulation on the tubes. They also determine the minimum rate at which a slag-tap furnace may be operated without difficulty in removal of the ash in fluid form. Need for a Better Criterion In common with other producers and users of coal, the Northern Illinois Coal Corporation has long used the available methods for the measurement of the clinkering characteristics of coal ash, chemical composition and fusion temperature of the ash, as criteria for the selection of coal that would suit the particular requirements of its customers. These two available criteria have greatly helped in the problem of selection but it is unnecessary to dwell upon the fact that they are not completely adequate for the purpose. The composition of the ash and its clinkering tendency vary widely over the company's mining area. In a certain period, some years ago, an unusual amount of severe clinkering of the ash of coal shipped made extremely acute the need for a better criterion of the clinkering that might be expected. It was also desirable that the criterion result from a reasonably rapid method, so that the clinkering characteristics of the coal would be known before shipment. Complaints on the severe clinkering of the ash came from only a fraction of the output of the mine but the occurrence of the clinkering seemed quite unpredictable. Attempts to relate the chemical composition of the ash and the fusion temperatures to the clinkering were unsuccessful. Coal from the area of the mine in which the fusion temperature of the ash was the lowest gave the least trouble from clinker-ing. Chemical analysis of the ash from that section giving the most trouble showed high contents of iron and low contents of silica, but frequently these were not greatly different from those of coals that gave little trouble from clinker. Aside from the clinkering difficulty, the coal was quite satisfactory. The ash content was normal and high rates of burning could be obtained, but again and again such severe clinkering would occur that the furnace would be shut down because of the accumulation of clinker. Examination of the clinker from the customers' plants showed that the clinkers that adhered to the grates and fouled the fuel beds were hard, flat, dense, and usually dark in color. Coal that was satisfactory gave clinkers that were softer, bulky rather than flat, of low density, and usually lighter in color.

Jan 1, 1944