Search Documents

By Nikkam Suresh

Dense medium cyclones have been in use for washing coarse and small coals for more than 50 years. There have been modifications in its design and today these units have become indispensable for washing of Indian coals possessing difficult washing characteristics. About 53 percent of the Indian coals (coking and non-coking) are being washed in jigs, about 38 per cent are washed in dense medium cyclones while the remaining 9 per cent is treated in other units like Barrel Washers, Heavy Media Baths and Drum Separators etc. The present paper deals with the attempts made for design of industrial Dense Medium Cyclones for enhanced coal recovery. Two industrial units of 500 mm diameter and 650 mm diameter were designed with their washing capacities being 200 m3/hr and 350 m3/hr, respectively. The results of the pilot tests conducted on 500 mm cyclone treating very high Near Gravity Material coals crushed to -3.0+0.5 mm gave an ash reduction of up to 19.5 percent with the new design i.e., from a feed ash of 34.5 percent to 15.06 percent in clean coal with an appreciable yield of 45 percent in one stage.

Sep 1, 2012

By R. Lestari

Newmont Batu Hijau operates with an accelerated mining rate to optimize life of mine (LOM) project economics. This results in a portion of ore mined being stockpiled for reclaim and processing throughout, and at the end of mine life. LOM economics can be further enhanced by preserving stockpiled ore value by mitigating oxidation effects. A detailed stockpile ore oxidation study was conducted to: ?? Develop a practical understanding of how oxidation affects ore value; ?? Determine how oxidation rate can be controlled, and; ?? Determine how oxidation effects can be mitigated to preserve ore value. The result of the study is a stockpile management strategy that significantly reduces oxidation related losses and, implementation of that strategy within practical constraints. Implementation includes installation of Controlled Potential Sulfidisation (CPS) flotation to facilitate oxidised sulfide copper recovery and, recovery of dissolved copper from stockpile drainage solution into saleable product. This paper describes the study results including managing and predicting stockpile oxidation with time, monitoring performance of implemented CPS flotation and recovery of dissolved copper from stockpile drainage. These are essential elements of successful long term mine operation in Batu Hijau.

Jan 1, 2014

By Chris Plackowski, Bruckard. Warren J., Anh V. Nguyen

"Enargite is a significant penalty mineral in the copper industry and its separation from many copper sulfides by flotation is difficult. The separation may be crudely achieved using selective oxidation techniques or through the use of pulp potential control. This paper summarizes our latest contributions to a better understanding of enargite surface electrochemistry and hydrophobicity. Oxidation, roughness, hydrophobicity and species formation on the surface of natural enargite were examined by a novel experimental approach that combines electrochemical techniques, atomic force microscopy, X-ray photoelectron spectroscopy and droplet evaporation tensiometry. It allows for synchronized electrochemical control and examination of the oxidative surface morphology, speciation and hydrophobicity of enargite at pH 4 and pH 10. At low pH, surface layer formations consisting of metal deficient sulfide and elemental sulfur were identified associated with a limited increase in roughness and heterogeneous distribution of surface species produced by initial rapid dissolution of Cu, followed by diffusion limited surface layer deposition. At high pH, a similar diffusive mechanism associated with oxidation products consisting of copper sulfate and hydroxide and a significant increase in surface roughness were established. Receding contact angle measurements showed no significant difference in the contact angle on a surface oxidized at pH 10 and the freshly polished surface. Contact angle increased from 46° on the polished surface to 59° after oxidation at pH 4. Competing effects of hydrophilic copper oxides and hydroxides, and hydrophobic species of elemental sulfur on the mineral surfaces under oxidizing conditions at pH 4, and the change in surface roughness at pH 10, contribute to the changes in enargite hydrophobicity under electrochemically-controlled oxidation conditions. Most likely, both surface species and surface roughness produced by oxidation are critical to the changes in the wettability of enargite and other sulfide minerals."

Jan 1, 2014

By Heikki Häkkänen, Tommi Kauppinen, Navid Khajehzadeh

"There are a variety of methods suitable to analyse elemental and mineralogical contents of rock drill core samples. Current demands are on fast exploration and objective analysis of ore samples. This paper proposes a combination of Laser-Induced Fluorescence (LIF) and image processing, entitled LIF-imaging, as a potential method for automated mineral analysis of the drill core samples. It is shown that LIF-imaging can produce a mineral map of the fluorescent minerals existing on the surface of the drill core samples. The test cases are drill core samples from a Ni-Cu mine situated in Kevitsa, Finland. The main prerequisite of LIF-imaging technique is a reference data, linking colours to the minerals. This study describes the calibration of LIF-imaging technique using precise but slow Raman spectroscopy. Using regularized logistic regression, a model is obtained that classifies the minerals based on their emitted fluorescent colours in the digital images. The abundance of each mineral group is estimated by pixel counting. The results are compared with X-Ray Diffraction laboratory assays performed on the same samples. The results show that the interpretation of the fluorescent minerals through LIF images corresponds to the XRD results. Furthermore, the utilization of the logistic regression to interpret the existing fluorescent minerals greatly improves the technique."

Jan 1, 2014

By M. Rehor

The importance of brown coal as a raw material is currently given by growing energy needs of Czech Republic. More than 70% of mined brown coal comes from North Bohemian Basin these days. Mining of brown coal is run in four mining locations. They are geologically different and the parameters of mining coal are quite different too. This requires a little bit different methodology of both extraction and reclamation. Methods of reclamation works in the region are given mainly by the characteristics of overburden rocks appearing in the upper horizon of recuperated localities. The difficulties of the North Bohemian mine dumps reclamation works are caused by extremely unfavourable properties of rocks poured down to the majority of mine dumps. These are mainly rocks of the overlaying strata and the rocks strata of brown coal bed. Main materials poured down to the mine dumps are sands, clayey sands and kaolin ? illitic clays. Admixtures in filled rocks consist of organic (coal) mass, siderite and pyrite. These rocks are mechanically instable with respect to the wind and water erosion and during weathering they are getting unfavourable, acid (phytotoxic) nature, due to the influence of SO3 and Al ions. External and internal dumps of open pit mines are significant part of the North ? Bohemian landscape sustained by excavation. Their as fast as possible preparation and gradual integration into ecosystem of the area is interest of both citizens of region and mining companies. The paper briefly summarizes the methodology of restoration of the largest dumps of the North Bohemian Brown Coal Basin and the results of analyses and evaluation of samples taken on restored localities Rado-vesice dump, Strimice dump, Ru?odol dum pand internal dump of Bilina mine. An example of modern non-tradicional restoration methods is the restoration of internal dump of Bilina mine (application of power plant stabilizer). According to observations and results of sample analyses the methods of restoration were selected to limit the erosion influence, adjust the chemical and physical composition of surface of Radovesice and Strimice dumps. The application of marlites and bentonite prevent the unfavourable weathering processes on dump surface. Compensation of Quaternary sediments was artifically formed here. The need of marlite ploughing in, application of organical substrates and vegetation preparation was proved on Radovesice dump. The conception of landscape reclamation of the largest dumps after finishing of mining, methodology of technical reclamation and well considered using of fertilizable soils are main results presented in this article.

Jan 1, 2014

By E. Szelag

The adsorption and stabilization of mineral dispersed systems by using Pluronic copolymers with different molecular weights and EO content has been studied. The role of sequential adsorption of EO-PO copolymers and cationic surfactant (CTAB) on the carbonate particle properties and in determining the stability of their suspension was studied with particular attention to the conformation of the polymer at the solid-liquid interface. The purpose of this work was to investigate the flocculation phenomena, influence of polymer molecular size on stability of suspensions of magnesite and dolomite and the effect of addition mode of polymer and surfactant. The suspension stability measurements and the determination of sedimentation speed were carried out using an optical analyser (Turbiscan). In most of investigated cases, the biggest floccs and the fastest sedimentation were found for low concentrations of copolymers.

Jan 1, 2014

By Moris Fresko, Julia Sun, Charles C. Golembewski, Vytas Svalbonas

"A history of mill strain gaging at Metso is presented. The output of these strain-gaging programs is compared with calculated stress ranges from different finite element solutions. These comparisons expose the amount of approximation that exists in the analytical solutions, starting from geometry, and material properties, and ending with different forms of internal load models. The influence of strain gaging results on mill design and analysis practices is also discussed. While these instrumentation programs are valuable in identifying areas of high stress in mills, and locations of stress concentration factors, they are by no means extensive or comprehensive enough to verify general internal load models. The vast majority of the programs were aimed at getting additional data about potential failure points, rather than describing overall mill stress behavior. This is especially true since the more recent gaging programs have not included the difficult task of gaging the mill rotating structure interior. This paper tries to avoid the novice path of leaping to general conclusions on the basis of insufficient data."

Jan 1, 2014

By B. Hosseini

Considering the subtractive trend of the sulfide and high-grade zinc ores in worldwide and also in Iran, Nowadays special attentions have been drawn to the extraction of zinc from its other resources such as low-grade oxide ores and secondary resources. Oxide ore of the eastern part of Mehdi-abad lead and zinc mine is silicate and has an average grade of 7% (with cut off grade of 4%). Main mineral of the Mehdi-abad ore is Hemimorphite and this mineral is associated with Goethite, Hematite, Ferrous Dolomite, and Manganese oxide mineral so that oxides of Iron, manganese and silica include almost 50% of the total ore. In this paper, the results obtained from the leaching kinetic study of the low-grade zinc oxide ore using Sulfuric acid are presented. The effects of particle size, reaction temperature, acid concentration, and solid percent on the dissolution rate have been investigated. The results obtained from the Taghochi approach showed that the zinc recovery is about 78% under the following optimized conditions: particle size: 106µm, leaching time: one hour, temperature: 45°C, acid concentration: 15% and solid percent: 15%. Kinetics study was revealed that zinc minerals leaching controlled by diffusion rate through the product layer during leaching time with the activation energy of 5 KJ/mol and compliance with the 1- (2/3. x) ? (1- x) 2/3 = k. t model. Keywords: leaching kinetics, kinetics models, sulfuric acid leaching, taguchi methods, low grade zinc ore, mehdi-abad mine

Sep 1, 2012

By Graeme J. Jameson

"When mineral particles are floated in a mechanical flotation cell, it is found that the rate constant, after reaching a maximum value, starts to decline as particle size increases. It had been thought that the reduction in rate constant had been due to the increased prevalence of composite particles in natural ores, for larger particles. However, Jameson (2012) showed that the rate constant for composites is certainly a function of the surface liberation, but the reduction in flotation rate is independent of particle size. Thus all particles are equally affected by reduced surface liberation, independently of their size. He further argued that the classical peak observed in the rate constant with increasing particle size, is a function of machine hydrodynamics. Thus in mechanical cells, the peak may be due to the high energy dissipation rate and its effects on the detachment of particles from bubbles (Goel and Jameson, 2012). Consequently, in a different flotation environment, it may be possible to float large composite particles that cannot be floated in mechanical cells. This paper describes the flotation of large composite particles in a fluidized bed flotation cell. The particles to be floated are fed to a column in which there is a continuous upflow of liquid. A conventional froth layer of controlled depth is formed at the top of the vessel. A fluidized bed of particles is established which provides a gentle environment for the contacting of large particles with bubbles. An example is given where a porphyry copper ore was prepared at a top size of 710 µm, and floated with conventional collector (PAX) and frother (MIBC). The concentrate was separated into size fractions and examined by photography. Composites were observed at all size fractions, but above 400 µm, all particles were composites. The implications for future flotation circuits will be described."

Jan 1, 2014

By I. D. Ustinov, V. A. Arsentyev, A. O. Mezenin, A. M. Gerasimov

"The solid mineral raw materials of the sediment deposits containing the argillaceous variations such as the coal and the potash ores are the most multi-tonnage solid minerals mined and processed in the territory of the Russian Federation. Both types of the deposits have relatively simple geology aspects with large and medium-sized solids and as a rule, the most often, with the regular bedding which are characterized by the fitchery thickness and the internal structure. Such deposits are very difficult for mining and processing. The thermal modification of this of ores allows changing the physico-chemical properties of its components in such a way that their further processing - grinding, separation, transportation and storage can be carried out without the use of process water or significantly reduces its consumption. The purpose of the present study is to increase the efficiency of the mineral processing containing the layered aluminum silicate by reducing their negative impact on the basic dressing processes, the separation of suspended matters and the storage of waste. INTRODUCTION Many deposits of minerals are associated with the presence of layered silicates such as the argil, mudstones, argillaceous slate - highly hydrophilic mineral varieties which have the ability to swell in the water. This ability to self-disperse creates the great difficulties both for the extraction and the processing of such ores. Since the dressing of most minerals is associated with the use of wet processes, where in contact with water the swelling layered silicates are dispersed to a particle size of less than 50 µm, but due to their high hydrophylic property they form bonds that promote the formation of so-called structured suspensions having increased viscosity. In this case the structured suspensions make it difficult to perform the separation operations as the classification, the gravity and magnetic separation, the flotation and thickening and filtration operations."

Jan 1, 2018

By S. K. Kawatra, T. C. Eisele

"Coal-fired electrical power generation plants produce 56% of all the electricity in the U.S., burning approximately 860 million tons of coal annually. This results in the production of 58 million tons of fly-ash; 19 million tons of bottom ash and boiler slag, and 23 million tons of desulfurization sludge.s annually. These are a considerable disposal problem, and it would therefore be very valuable to be able to sell these residues and by-products as useful materials, rather than paying to dispose of them in landfills. However, utilization rates are currently very low, below 32% even for the most thoroughly commercialized combustion byproduct (fly-ash). This poor utilization rate is a result of the high impurity content of combustion byproducts, which makes them unsuitable for existing markets.Mineral processing techniques are useful for upgrading and utilizing combustion by-products. Fly-ash can be processed to remove unburned carbon, or utilized as a binder component in ore pelletization and agglomeration processes; bottom ash can be processed to produce certain aggregate grades; CO2 emissions can be sequestered using modified leaching techniques; and many scrubber sludge’s require processing before they can be used for producing gypsum products.The experiments described in this paper were carried out to study the application of mineral processing techniques to upgrading combustion by-products, particularly flue-gas scrubber sludge. A process was developed for upgrading unoxidized Flue-Gas Desulfurization (FGD) sludge’s by removing the primary impurity (unreacted limestone). A combination of hydrocycloning followed by froth flotation reduced the limestone concentration to as little as 1.7%, while recovering 66% of the sludge weight as a clean product. The recovered limestone was sufficiently concentrated that it could be recycled to the scrubber for more complete utilization."

Jan 1, 2003

By Massimiliano Zanin, William Skinner, Owusu Clement, Jonas Addai-Mensah, Daniel Fornasiero

This paper highlights the importance of pulp aeration in the selective separation of chalcopyrite from chalcopyrite/pyrite mixtures of varying pyrite content (20-80 wt.%). Laboratory batch flotation studies and oxygen demand tests were performed to predict the optimum amount of air required for the selective separation of chalcopyrite from pyrite. The pulp oxygen demand was shown to increase with increasing pyrite content but decrease with time as more air is introduced into the system. Complementary batch flotation tests showed significant improvement in chalcopyrite flotation under moderate pre-aeration of the pulp. However, a continuous decrease of chalcopyrite flotation was observed under highly aerated conditions. The amount of air required to achieve maximum chalcopyrite flotation recovery correlated positively with the mass fraction of pyrite in the pulps. The greater the wt.% of pyrite in the chalcopyrite/pyrite pulp, the longer the aeration time required. The optimum aeration time was established as the time before which the oxygen consumption rate constant reaches a bottom plateau. Surface analysis (XPS) indicated that the continuous decrease in pyrite recovery observed with increasing aeration time was due to the formation of more iron oxy/hydroxide on its surfaces, the same species accounting for the decrease in Cp recovery after prolonged aeration.

Jan 1, 2014

By P. S. Dash

With implementation of stringent environmental regulations, ultra clean coal technology development programs have gained significant importance worldwide. As far as Indian scenario is concerned, most of the coals present in India are of drift origin and low grade, containing high mineral matter varying from 15% to greater than 50%. The inorganic or ash constituents of Indian coals are finely disseminated through the organic or carbonaceous constituents so, that commonly used physical beneficiation techniques are of only limited value in affecting separation. Chemical processes involve addition of chemicals, which react with the mineral matter and allow its easy removal. The present study envisages the effect of aqueous alkali leaching followed by acid washing on the removal of mineral matter from two different captive coals of Tata Steel at elevated temperature and pressure. The experiments are conducted at desired conditions using a bench scale pressure reactor set up having proper data acquisition and control system. The research study revealed, that it is possible to reduce the ash content up to 70% by this method. The alkali content of the product clean coal does not increase whereas the silica and alumina content reduces by nearly 58% and 62% respectively. Significant reduction in the phosphorus content is observed after the acid treatment. The crucible swelling number of the feed coal improves after the treatment. The mechanism of demineralisation was evaluated by analyzing the coal samples before and after the alkali and acid treatment using scanning electron microscope (SEM). Because of the acidic nature of the silicates and aluminates, they dissolve into the NaOH solution and form sodalite. Sodalite is partially soluble in the alkali solution. The hydrates formed during alkali treatment are partially removed due to acid wash. This study in overall provides an insight into possible alternative methods of beneficiation for removal of ash from high ash Indian coals.

Sep 1, 2012

Much has been published in recent years on the challenges facing the engineer of the 21st century and the consequent challenges facing the education providers and industry. The world is changing rapidly on the social, economic, political, technical and environmental fronts and our metallurgists/mineral processing engineers of the future will arguably need to have a different set of skills than those which were traditionally regarded as adequate during the latter half of the 20th century. This paper attempts to explore some of these issues and their ramifications.

Jan 1, 2014

Producing robust agglomerates with desirable structural properties is the key to success of the heap leaching of complex, low-grade nickel laterite ores. Mechanically strong but porous agglomerates with narrow size distribution (e.g., 5 ? 40 mm) are required to build permeable and perennially stable heaps of 4 ? 10 m height. The characterization of granules? microstructure is essential for greater understanding and correlation with the concomitant mechanical properties and robustness. In this study, we used non-destructive, computed X-Ray tomography analyses and scanning electron microscopy (SEM) in tandem with conventional compressive strength,and integrity/stability tests to draw links between nickel (Ni) laterite agglomerate strength/stability, internal microstructure (e.g.,porosity, inter-particle bridges) and binder type. It is shown that binder composition (e.g., tap water vs. 30% w/w H2SO4) and post-agglomeration drying both significantly impact on granules? physicochemical and microstructural properties. Acidic binder, in contrast with tap water, leads to significant incongruent leaching of different species from particles during ore-binder mixing and agglomeration. Upon wet agglomerate curing, solidified/recrystallized leached species form strong intra-granular solid bridges which, lead to greater compressive strength of dry agglomerates. Structural stability/integrity of cured agglomerates in acidic solution, however, decreases dramatically due to greater porosity and acid solubility of intra-granular solid bridges. These findings are useful in shedding more light on agglomerate structure characteristics and their optimization for enhanced column and heap leaching with concentrated sulphuric acid.

Sep 1, 2012

By S. P. Nagaeva, A. V. Kuptcova, O. Yu. Poperechnikova

"The present paper contains study results of gold morphology and grain size distribution in flotation concentrates produced from original ore samples from deposits of different genesis. Pre-concentration methods were used with selective dissolution of rock minerals and mineral heavy medium separation to obtain statistically valid data on gold grain size and morphology in concentration products. Special attention is given to study of flash flotation concentrates that is mainly used for coarse gold, underextracted in gravity circuit. Analysis of geometrical optics has allowed to establish that during flash flotation gold grains more than 150 µm can be extracted from 10 to 35%, and in some cases single gold grains above 300 µm. INTRODUCTION Distinctive features of gold that have a significant impact, and in some cases, decisive influence on its recovery into saleable products are mineral shape, grain size and morphology of metal particles, paragenetic associations of gold. Peculiar feature of coarse gold is its easy extraction during grinding from associated mineral components like quartz, sulphide and other and almost complete recovery into gravity concentrates (Lodeischikov V.V., 1997). Morphology of native gold is so diverse that different gold grains are better extracted using different methods of concentration. Compacted and rounded particles are easily processed using gravity concentration but low cyanidable and hard to process using flotation. On the contrary, lamellar, flake, dendrite and capillary aggregates of high specific surface are easily cyanidable and under definite conditions it has strong floatability (Lodeischikov V.V., 1997). Flotation of gold-containing sulphide minerals and free gold takes place simultaneously during flotation concentration. In case of low-sulphide ores, native gold takes the basic load, having the high density (15.6 to 18.3 g/cm3, for pure gold – 19.3 g/cm3) it has limited size and morphology for successful flotation. It is known that flake gold and fine-grained gold up to 0.1 mm are easily extracted (Lodeischikov V.V., 1997). Authors of the present paper performed a study of gold granulometry and morphology in flotation concentrates produced from gold-containing ores from two deposits of different types: gold-copper oxidized hematite ores and low-sulphide gold-quartz ores. Ores are different by both host rock composition, mineralogical and petrographic features, gold grade in mineral assemblage and morphology and size of precious metal. Common for both ore types is low-sulphide content and presence of free gold."

Jan 1, 2018

By Klaus M. Hahn, Kurt Aasly, Jutta Lennartz, Hermann Wotruba, Ben Snook, Przemyslaw B. Kowalczuk, Rolf Arne Kleiv

"Seafloor massive sulphide (SMS) deposits have been identified as important marine metal resources for the future. However, literature on mineral processing of SMS is currently limited, and to date, no research has been published on processing of SMS from either active or inactive hydrothermal vent fields on the Arctic Mid-Ocean Ridge. In this paper, individual SMS rock samples from the Loki’s Castle area were tested. Chalcopyrite, isocubanite and sphalerite represented the main copper and zinc bearing minerals in the SMS samples, whereas the gangue consisted of barite and silica. Based on the X-ray transmission response (XRT), i.e. differences in the atomic number of elements in tested samples, and using portable XRF (PXRF) values of elemental composition, individual particles were classified as a either product (low barium / high to low silicon / high copper and zinc) or waste (high barium / high silicon / low copper and zinc). The classification was based on the elemental composition of the samples with the cut-off grade equal to 0.5% for copper. It was shown that the XRT discrimination analysis correlated well with elemental (PXRF) data classification. The results clearly indicate that X-ray transmission sensor-based sorting can be used a useful technique for preconcentration of SMS rock samples. INTRODUCTION Due to different compositions of investigated samples, sensor-based sorting is a useful technique for preconcentration of different materials. The aim of using sensor-based sorting is to upgrade an ore by reducing the quantity of overall waste material reporting to the next processing stage. This can be achieved by eliminating (reducing) the waste fraction. By applying sensor-based sorting, the energy consumption for particle comminution as well as the required process water and reagents can be decreased. The total volume of the waste rejection leads to a proportional reduction in the total energy costs (Lessard et al., 2014, 2016)."

Jan 1, 2018

By V. Tsyplakov

This article reviews factors of preg-robbing effect, occurring in the course of pressure oxidation of ore and concentrates, containing chloride compounds and so-called 'organic carbon'. The article also summarizes the main results of the studies and testwork conducted to overcome this effect. The following efficient preg-robbing mitigation methods have been noted: higher temperature of pressure oxidation process, preliminary removal of natural carbonaceous material from concentrate, chloride removal prior to concentrate pressure oxidation, and addition of water-soluble organic blanking agents, which suppress the adsorption activity of the native ore adsorbents. Keywords: preg-robbing, double-refractory gold concentrates, pyrite, arsenopyrite, blanking agents, pressure oxidation, autoclave leaching

Sep 1, 2012

By David Morrow

Fly ash is a by-product from coal-fired power stations that is captured from the exhaust gas stream by electrostatic precipitators (ESPs) or bag houses. It is mainly derived from the inorganic components in coal but also contains residual carbon from unburnt fuel (measured as LOI). In the past, nearly all fly ash was sent to landfills or tailings ponds by power generators but this trend is quickly changing due to landfill costs, sustainability requirements and the inherent value in correctly processed fly ash. The main property that makes fly ash suitable for recycling is its use as a pozzolan. Pozzolans exhibit cementitious properties that make them suitable for partial cement replacement, and that can have beneficial properties for concrete mix designs. Fly ash can be used to replace up to a third of the of the Ordinary Portland Cement (OPC) requirement. Suitable fly ash nearly always requires the removal of the less reactive coarser fraction from the finer fraction. Due to the pozzolanic nature of fly ash, it must be processed dry and separation is normally required at 45 micron. In response to the increasing demand from a range of dry classification applications, Metso purchased an established air classification technology suitable for both mining and construction applications. The classifiers intelligent design efficiently utilizes the air flow which keeps power requirements low whilst including a scrubbing/recirculating function within the classifier that allows extremely efficient separations even at very fine sizes. This technology is of global interest to Fly Ash processors, but should be of particular interest in India which is both the second largest cement producer in the world as well as producing 80% of its power from thermal sources. This paper is intended to give a brief overview of fly ash and requirements for use as a pozzolan, air classification of fly ash and a case study from an established and experienced fly ash producer. Keywords: air classifier, fly ash, pozzolan, fineness, cement, cholla, salt river materials group

Sep 1, 2012

By S. Fiore, M. C. Zanetti, C. Clerici

The processes and fluxes of a cast iron foundry plant located in the North of Italy were analyzed in order to determine the amount and kind of wastes produced from the different activities. The main fractions are the molding sands, furnace muds and powders coming from the dust abatement plant, the exhaust lime, the furnace refractory, the metallic shotting and the sludges and powders coming from the dust abatement plant of molding lines for a total production equal to 800 t/d. All wastes were sampled and particle-size and chemically characterized to evaluate the best recycling or reuse solutions. Wastes were sieved and divided in three categories according to the particle-size dimensions: below 0.1 mm, between 0.1 and 0.6 mm and above 0.6 mm. The fraction above 0.6 mm dimension underwent magnetic separation to recover and quantify the potentially available iron fraction. The fraction between 0.1 mm and 0.6 mm was chemically characterized in order to understand if it could be fed to the sand regeneration plant. The below 0.1 mm fraction was characterized to evaluate the following recycling and reuse solutions: additive for molding sands and/or raw material for the concrete industry.

Jan 1, 2003