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By Jewel A. G. Gomes

Electrocoagulation (EC) has been performed with Al-Fe electrode system with changing polarity for the removal of arsenic from water. The removal process has been studied using ICP-AES and Anodic Stripping Voltammetry with a wide range of arsenic concentration (1-1000 ppm) at various pH (4-10) and residence times (1-60 min). Electrochemically generated by-products have been analyzed using XRD, FTIR, XPS, SEM/EDS and Mössbauer Spectroscopy. Results revealed expected crystalline iron oxides (magnetite (Fe3O4), lepidocrocite (FeO(OH)), iron oxide (FeO)) and aluminum oxides (bayerite (Al(OH)3), diaspore (AlO(OH)), mansfieldite (AlAsO4?2(H2O)), as well as some interaction between the phases. The amorphous or ultra-fine particular phase was also found in the floc. The substitution of Fe3+ ions by Al3+ ions in the solid surface has been observed, indicating an alternative removal mechanism of arsenic in these metal hydroxides and oxyhydroxides by providing larger surface area for arsenic adsorption via retarding the crystalline formation of iron oxides.

Jan 1, 2006

By Thomas G. Goonan

Copper production through smelting generates large volumes of material flows. As copper contained in ore becomes copper contained in concentrate to be fed into the smelting process, it leaves behind an altered landscape, sometimes mine waste, and always mill tailings. Copper concentrate, fluxing materials, fuels, oxygen, recyclables, scrap and water are in-puts to the process. Dust (recycled),gases — containing carbon dioxide(CO2) (dissipated) and sulfur dioxide (SO2) (mostly collected, transformed and sold) and slag (discarded or sold) — are among the significant process outputs. This article reports estimates of the flows of these input/output materials for a particular set of smelters studied in some countries. They include Chile (Altonorte, Caletones, Chagres, Chuquicamata, LasVentanas and Potrerillos), Japan(Naoshima, Onahama, Saganoseki,Tamano and Toyo), the United States(Garfield — Fig. 1 — Miami and Hayden) and Europe (Glogow I, Glogow II, Huelva, Norddeutscheand Ronnskar).

Jan 1, 2005

By Marius B. Wechsler

There are considered deep piles which are fixed in blocks of rotating machinery foundations. A mathematical background is developed for determining the behavior of this kind of piles for motions caused by horizontal and vertical oscillations, as well as by roc-king and twisting. It is assumed that the piles come across a top soil layer of depth c, not capable of lateral support, and penetrate over a length b, in a bottom firm soil layer, or in a bottom soft soil layer in which vibrations can produce voids around the piles. With respect to b and c, as well as to the elastic properties of piles and soils, the analysis leads to the maximum bending moments and shear forces subjecting the piles, to the maximum lateral bearing on the bottom soil layer, as well as to the deflection of the pile and the displacement of the foundation block. The results of the performed analysis can be applied to seismic loads too, and they are illustrated by a numerical example.

Jan 1, 1987

By S. R. Krogh, T. O. Olsen

Analytical expressions for the breakage rate as functions of mill charge, mill speed, particle size, ball diameter, and ball load are derived, using idealized models for probability of breakage (Gaudin and Meloy), energy distribution (Mempel), and arithmetic mean of effective ball energy (Langemanns). Computational results using the theoretical equations are compared to experiments. The equations enable simulation of ball mill grinding at different grinding conditions.

Jan 1, 1973

By T. Fabritius, L. Hekkala, J. Härkki

The Outokumpu steel belt sintering technology is used for manufacturing chromite pellets that are charged into smelting furnace for ferrochromium production. Hot air is blown through the moving bed of raw pellets. Direct temperature and flow measurements are difficult to do in the bed of a real scale belt sintering process. Therefore, a tested and reliable mathematical model would be a valuable help for optimising operational parameters of the process and designing new constructional improvements. The aim of this work is to present a mathematical model that calculates the gas flow and temperature distribution in the bed of pellets and the atmosphere. Computational fluid dynamics program FLUENT is used to calculate the gas flow, composition and temperature of the gas in the sintering bed during processing. Energy equation for the bed, containing the effects of evaporation of water and oxidation of carbon and iron oxide, will be added to the model to obtain the temperature of the pellets. The porous media model used for pressure drop calculations in the bed is shortly discussed. A comparison between CFD-calculations and experiments with a pilot scale batch-sintering reactor are also presented. The final model can be used as an engineering tool when developing the process and the equipment further. Different designs can be easily tested with the model and the effects of the changes to the flow pattern and temperature distribution can be studied.

Jan 1, 2004

By P. J. Baguley

The model has been developed on the basis of the observation that the partitioning behaviour of a particle is related to its calculated terminal velocity. It utilises a theoretical calculation of the terminal velocity of each particle class. This is then correlated with the observed partition data for a plant separator using empirically-derived functions of operating conditions which take into account effects such as bath turbulence, holes in drum lifters and feed arrangements. The model successfully decouples the effects of medium density and viscosity and is appropriate for any bath-type separator. The correlation between calculated terminal velocity and actual partitioning behaviour was established and modelled using data obtained from two Wemco drums treating Fe and Mn ores. The model can be used to predict the prevailing size-by-size partition curves and the separation (product grades/recoveries) given the washability of the feed and operating conditions. Simulations are used to show that, for the treatment of Fe ore, there is a maximum medium density beyond which product grades fall and that this maximum decreases as the proportion of magnetite in the medium increases. This is attributed to the dominant effect of viscosity at higher medium solids concentrations

Jun 18, 1905

By M. Moys

The use of temperature measurements for unusual applications in the analysis and control of column flotation and milling is discussed. This is followed by a review of some of the authors current research in the application of the discrete element method to the modelling of particulate processes, specifically milling, fluidized beds and chute flow.

Jan 1, 2005

By R. Venkataramani

Crushed stone operations have become more difficult due to rising costs of labor and equipment, with the consequent reduction in profit margins. Competition from other operators and the encroachment of vertically integrated companies place severe restrictions on available markets. The seasonal demand for stone precludes any definite production level, and changes in productivity have to be accommodated. These influence profitability, and therefore production plans must be continuously adjusted to keep pace with rapidly changing conditions. The basic problem of stone companies seeking to maximize profits is one of balancing stone production costs, costs of inventory holding and stock-piling, marketing costs and any other charges accruing over time against the selling price of stone. Because of high peak demands, slack period production must be stored and then distributed to supplement peak period production. For a multi-plant operation, there is a need to evaluate at the same time the interaction between the plants and the various marketing sectors. In a multi-plant operation with different production capacities and production costs, stone producers are interested in the answers to the following questions: 1. How much stone should be produced at each plant in each time period? 2. What should be the optimum stone shipment from each plant to each market? 3. What are the effects on net returns and shipping plans, if production capacities are altered at the plants? These questions have many different answers that, will satisfy demands. From the point of production scheduling, the minimum production cost may be the objective. From the inventory standpoint, the best solution will be to synchronize production with sales. However, when the transportation of stone is also considered, the desired end is to achieve that delivered cost which maximizes the company f s net return. Besides, only an extremely naive analysis ,wouId attempt to

Jan 1, 1971

By J. A. Herbst

Until the past decade, the energy-size reduction relationship was the dominant form of mathematical model used in the description of tumbling mill grinding processes (1,2). Typically, in these models some single measure of product fineness (e.g. the 80% passing size, the size modules, the specific surface area) is chosen as the dependent variable and the energy input per unit mass of material being ground acts as the independent variable. In some instances these models have been useful for the correlation of experimental data, but, invariably, they have been found to be inadequate for meaningful process simulation. During the last decade considerable advances have been made in the development of phenomenological grinding models derived from population balance considerations (3-7). In these models a set of dependent variables is employed, corresponding to the set of mass fractions which constitute the product size distribution, and energy input is abandoned in favor of "time in the mill" as the independent variable. The phenomenological models have been shown to provide accurate simulations of the entire size distribution of ground products produced in batch (8-10), locked cycle(11)and steady and unsteady state, open and closed circuit continuous grinding(12,13).

Jan 1, 1973

By S. Sarac

In this study, graphical and mathematical methods used to determine operating points in single or multiple fan ventilation systems are summarized. The problem is mathematically formulized for parallel connected fans in which analytical solutions are not possible. For n number of parallel connected fans, a non-linear equation system that consists of n number of non-linear equation sis derived. The Newton-Raphson method, which is a numerical analysis method, is adapted to solve this non-linear equation system and the solution steps are given as an algorithm. A computer program based on this algorithm is written and its applicability is proved.

Jan 1, 2000

By M. Vallée

"RÉSUMÉDurant les 10 dernières années, les améliorations dans le contrôle des limites des sautages et les arpentages après l’exploitation ont fourni des informations préalables et post facto sur les limites minières réalisées par rapport à la planification, plus particulièrement pour les grands chantiers exploités par les méthodes chambres vides et sous-niveaux. Cependant, peu de recherches ont été faites pour améliorer la délimitation du minerai, l’estimation des ressources et des réserves, les études de faisabilité et la récupération minière dans d’autres types de gisements. Il faudra d’abord expliciter les impacts des lacunes, en quantité et en qualité, de l’information géologique et de l’échantillonnage sur le rendement de l’extraction. Il faudra également remplacer la notion de « dilution générale » par celles de « dilution » et de « perte de minerai ». Les impacts des lacunes observées sur l’exploitation des gisements d’or filoniens sont démontrés par une simulation basée sur des résultats d’études antérieures à la mine Thompson d’Inco, des impacts financiers de densités d’information moindre et par des analyses des valeurs actualisées nettes (VAN) de deux cas types.Deux gisements similaires, de 3 m et 6 m de largeur et exploités par chambres vides sont étudiés, en prenant pour cas de base la délimitation sur maille de 7,5 m (25 pi.) et en étudiant les impacts des limites moins précises supportées par une maille de 15 m (50 pi.), en assumant que ces imprécisions moyennes de +/- 0,62 m se transforment soit en surestimation (dilution), soit en sous-estimation (pertes de minerai).Les impacts d’information moins précise ont été beaucoup plus forts sur le gisement plus étroit : autant la dilution que les pertes de métal ont diminué les VAN du gisement de 3 m de 39,27 % et 45,41 % respectivement, tandis que les VAN du gisement de 6 m ont été diminuées que de 12,84 % et 11,55 %.Ces impacts des valeurs actualisées nettes diminuées justifient et exigent des efforts plus systématiques pour s’assurer que les travaux de mise en valeur et les études de faisabilité soient réalisés de façon requise pour optimiser l’exploitation et offrir aux investisseurs des rendements compétitifs par rapport à ceux des autres secteurs industriels. ABSTRACTDuring the past 10 years, research work to improve the survey of stope limits after mining supplied useful information, particularly for large open and sub-level stopes, regarding waste dilution caused by differences between final production limits and planned stope limits.However, the efficiency of this information to improve the overall efficiency of the mining process is limited, given that the impacts of inaccurate ore limits leading to dilution (sensu stricto) and ore losses have not been considered adequately. Geological/sampling information should be optimized in terms of quantity and/or quality for the deposit characteristics and the constraints of the mining method used. As industry practice regarding the definition and recording of dilution is flexible and as ore losses frequently are poorly documented, the use of these terms is reviewed.Simulations were carried out on two typical narrow gold deposits, based on an earlier study at Inco’s Thompson mine regarding the impacts of wide to narrow delineation grids using recorded variations of vein geometry. Vertical to sub-vertical deposits of 3 m and 6 m widths mined by long-hole open stopes were considered. Deposits delineated by 7.5 m (25 ft) grids were taken as a base case and the impacts of less accurate limits in conjunction with long hole mining based only on a 15 m (50 ft) delineation grid. The impacts of overestimation (dilution) and underestimation (metal losses) were considered separately, using the average error of +/-0.62 m recorded in the Inco study.The impact of less accurate information was much stronger on the narrower deposit: both dilution and ore losses diminished the net present value of the 3 m wide deposit"

Jan 1, 2005

By Gareth Barnes

Traditional approach to improvement is driven by good ideas from good people, but whilst the business case may sound good, when the project is complete, we often have not delivered on expectations.  Why not? The best way to successfully predict the outcomes of an improvement effort in a complex process is through using statistical modelling, which considers the impact of uncertainty within interacting processes.  Applying Theory of Constraints in a model helps leaders to quickly determine: Where the constraining process(es) is/are Where improvements will add the most value How much improvement should be targeted - before the next constraint takes over The confidence level of achieving a given target, which gives us a clear pathway to improvement. This paper presents an analysis of statistical modelling applications at Vale’s Manitoba Operations to achieve the 2025 targets. Using statistical modelling of the Business Structure, the team identified a series of process improvements through a Theory of Constraints Analysis. Value Stream Maps (VSMs) were used to define the required data, apply statistical modelling, and conduct training sessions enabling the Manitoba team to identify the constraining influences. Scenario testing in the Statistical models helped identify the Hierarchy of Constraints and specify the pathway to improvement. How to Improve a Business Video link https://vimeo.com/344418155

May 4, 2025

In the minerals industry allocating capital for setting up a new project or for upgrading an existing facility usually requires that a compromise be found between the initial cost of equipment, its operating performance and on-going operating costs. To maximise the return on the investment usually requires that various possible combinations and layouts of equipment be assessed. This task is both difficult and time consuming. Computer simulation can be used as a means of determining the expected operating performance of a range of alternate equipment configurations. Simulation is a particularly important technique for analysis as it is one of the few approaches that allows the analyst to take into account the variability inherent in a mining process. While computer simulation is a well established technique its use, until recent years, has been limited to large organisations with access to substantial computing facilities. However, with the current availability of low cost computing platforms combined with easily understood animated displays, simulation is now becoming more widely used across the industry.

Jan 1, 1990

By Pat McLaughlin

Blast design in the construction industry has often been based on past practice or powder factors. This is to some extent understandable, since construction projects do not have the longevity of mining or quarrying operations and therefore have less opportunity to pursue potential improvements. The main concern of the operator is whether or not the technique will work, and at what cost to the downstream processes. Time, not long term savings, is of the essence.

Jan 1, 1994

By J. Evans

Including: Tailings thickeners, CCD?s, paste thickeners, HI-rate thickeners, lamella thickeners, high compression thickeners, clarifiers etc. Flocculant dosing control for mining thickeners and clarifiers is influenced by a number of process factors. 1. Flow rate into the thickener or clarifier a) As the flow rate increases into the thickener or clarifier ?retention time? decreases which causes a greater affect hydraulically on the settling solids. So as the flow rate increases it will generally mean an increase in flocculant dosing rate. b) As the flow rate decreases into the thickener or clarifier the retention time increases which reduces the hydraulic affect on settling, improving settling rates. This will generally mean that as the flow rate decreases, we will decrease the flocculant dose rate.

Jan 1, 2011

By M. Dworzanowski

The physical beneficiation of iron ore that has a wide particle-size distribution is problematic, regardless of the process applied, whether dense medium separation, gravity concentration, magnetic separation, or flotation. The problem of particle size is further compounded when there is a significant -10 µm fraction. Generally the approach to a wide particle-size distribution is to split into narrower size ranges and treat each separately. More often than not the -10 µm fraction is not treated but discarded. This approach results in a more complicated and expensive flow sheet and the loss of any potential value in the -10 µm fraction. Wet high-intensity magnetic separation (WHIMS) bench-scale test work was conducted on a haematite-rich material with a particle size of -200 µm. What made this material different was that it contained a 60% -10 µm fraction, hence discarding the -10 µm material was not an option. The objective of the test work was to determine how to maximize the recovery of the haematite across the full particle size range. Given the unusual particle size distribution, it was concluded that WHIMS would be the only practical beneficiation route. The -200 +10 µm and -10 µm fractions were treated separately and together under varying WHIMS conditions. For a given concentrate grade, the mass yield obtained was greater when the total particle-size distribution was treated. The inferred optimum conditions, using the same material, were tested on a pilot-scale WHIMS and similar results were obtained.

Jan 1, 2014

By Barara Rose

Presentation Outline ?Introduction of BMS ?Resource Integration Process ?Methodologies ?Tools ?Case Studies ?Zone 01 : 725 SOZ ?Zone 16/17 : 1000 NRP ?Conclusions

Oct 1, 2010

By T. Gupta, T. Ghosh

Rare earth elements (REEs) and their compounds are essential in a multitude of mundane and sophisticated applications such as renewable energy technologies, catalysts, medicine, and defense applications. The global supply deficit could be attributed to the destabilization of REE market that has, as a result, incentivized indigenous production of REEs. Cost-effective and environmentally benign opportunities are being explored for the production of REEs from non-conventional mineral sources including coal and coal by-products to stabilize the supply chain. Coal from Healy coal mine and Wishbone Hill deposits in Alaska have been quantified for REEs and were found to possess elevated total REE concentrations as compared to world average levels (60– 70 ppm). The objective of the study was to concentrate the REEs in the froth phase by froth-flotation of the fine size fraction (< 75 μm). A Box-Behnken design of experiment was employed to ascertain the main and interaction effects of operational parameters on response variable by analyzing 3D response surfaces. Experiments were carried out to maximize REE recovery and concentration by modeling and optimization of three operating variables (frother dosage, pulp density (% solids), and collector dosage). Based on the results, the optimum flotation conditions for maximum recovery at an elevated concentration of REEs in the froth fraction was obtained at 4.2% solids and 32.7 ppm of frother dosage for Healy sample and 10% solids and 37.9 ppm of frother dosage for Wishbone Hill coal sample. The quadratic relationship between the input and response variable was found to be independent of collector dosage suggesting good surface hydrophobicity and floatability of the two coal samples.

By J. Humphries

With today?s turbulent markets and unprecedented global opportunities, the need to optimize net present value and internal rates of return from capital investments has never been greater. To help address the need, this paper presents an overview of the key processes and strategies for achieving maximum return from capital projects. Best practices discussed address stage gate management for project evaluation, selection, and oversight, project execution efficiency, value improving practices, operational readiness, and operational excellence. The paper also includes a model of key metrics and benchmarking with tips for application. [ ]

Jan 1, 2011

By Kevin Beirne

Most people involved in the mining industry are familiar with student-industry co-op work-study programs. Many colleges and universities have used them for years. Northern College’s Haileybury School of Mines student co-op program adds a new dimension of productivity to the college and the mining industry. The college is located in Hailey-bury, Ontario, Canada. An example of the program’s success is the school’s relationship with Sabin Metal’s SMC (Canada) Ltd.’s McAlpine Mill in Cobalt, Ontario. Students gain practical knowledge and experience while industry gains an eager-to-learn worker. And many of the college’s advanced research services are made available to industry to supplement their own capabilities. The McAlpine Mill was established to provide custom milling of slags and ores. It also recovers metal values from other products of the primary and secondary precious metal industries.

Jan 1, 1999