This article investigates possible use of waste gypsum (synthetic), recovered via flue-gas desulfurization from coal-fired electric power plants, in foundries. Energy sector, which in Eastern Europe is mostly composed from coal-fired electric power plants, is one of the largest producers of sulfur dioxide (SO2). In order to protect the environment and reduce the amount of pollution flue-gas desulfurization (FGD) is used to remove SO2 from exhaust flue gases of fossil-fuel power plants. As a result of this process gypsum waste is produced that can be used in practical applications. Strength and permeability tests have been made and also in-depth analysis of energy consumption of production process to investigate ways of preparing the synthetic gypsum for casting moulds application. This paper also assesses the chemical composition, strength and permeability of moulds made with synthetic gypsum, in comparison with moulds made with traditional GoldStar XL gypsum and with ceramic molds. Moreover examination of structure of synthetic gypsum, the investigations on derivatograph and calculations of energy consumption during production process of synthetic gypsum in wet flue-gas desulfurization were made. After analysis of gathered data it’s possible to conclude that synthetic gypsum can be used as a material for casting mould. There is no significant decrease in key properties, and on the other hand there is many additional benefits including low energy consumption, decreased cost, and decreased environmental impact.
Modern investigation methods and equipment for the quality estimation of the moulding sands matrices with organic binders, in their circulation process, are presented in the paper. These methods, utilising the special equipment combined with the authors investigation methods developed in the Faculty of Foundry Engineering, AGH the University of Science and Technology, allow for the better estimation of the matrix quality. Moulding sands systems with organic binders require an in-depth approach to factors deciding on the matrix technological suitability as well as on their environmental impact. Into modern methods allowing for the better assessment of the matrix quality belongs the grain size analysis of the reclaimed material performed by means of the laser diffraction and also the estimation of the moulding sand gas evolution rate and identification of the emitted gases and their BTEX group gases content, since they are specially hazardous from the point of view of the Occupational Safety and Health.
This paper presents a new perspective on the issue of reclamation of moulding and core sands. Taking as a premise that the reclamation process must remain on the surface of grains some not separated binding materials rests, it should be chosen the proper moulding sand’s composition that will be least harmful for the reclaim quality. There are two different moulding and core sands taken into examinations. The researches prove that a small correction of their compositions (hardener type) improves the quality of the received reclaims. Carried out in this article studies have shown that such an approach to the problem of reclamation of the moulding and core sands is needed and reasonable.
The demand for castings of high quality and sound work is nowadays very high. The production of sound castings without foundry errors is the big issue in modern foundries. Foundry simulation software can do a lot to help improve the disposition of castings, gating system and feeder system, and assure good filling and solidification conditions, and also produce sound casting without the need of the old method of "try and error". One can easily change a lot of parameters for filling and solidification, and create the best proposal for production. Connor inlets have two functions. One is that it serves as an ingate, through which molten metal passes and comes into the mould cavity. The second function is that it serves as a feeder and substitutes the metal contracted during solidification and cooling of the castings. It can also save quite a lot of metal in comparison to classic feeders.
Definition of a composite [1] describes an ideal composite material with perfect structure. In real composite materials, structure is usually imperfect – composites contain various types of defects [2, 3–5], especially as the casted composites are of concern. The reason for this is a specific structure of castings, related to course of the manufacturing process. In case of metal matrix composite castings, especially regarding these manufactured by saturation, there is no classification of these defects [2, 4]. Classification of defects in castings of classic materials (cast iron, cast steel, non-ferrous alloys) is insufficient and requires completion of specific defects of mentioned materials. This problem (noted during manufacturing metal matrix composite castings with saturated reinforcement in Institute of Basic Technical Sciences of Maritime University Szczecin) has become a reason of starting work aimed at creating such classification. As a result, this paper was prepared. It can contribute to improvement of quality of studied materials and, as a consequence, improve the environment protection level.
In this paper the results of studies of polymeric binders on the example of the new BioCo2 binder, including the problem of its renewability, are presented. The results of structural studies (FT-IR) for the BioCo2 binder before and after crosslinking, and bending strength tests Rg u fresh and renewed cured molding sands with BioCo2 binder are discussed. The cross-linking binder and curring of moulding sand was carried out by physical agents (microwave radiation, temperature). On the basis of obtained results was shown that it is possible to restore the initial properties of the adhesive of BioCo2 binder. The initial properties of moulding sand can be achieved, after the cross-linking binders and after curing in the moulding sands with bioCo2 binder , by supplementing the moulding sand composition by the appropriate amount of water.
Increasing demands on the utility properties of materials used for castings have led to the production of cast iron with a modified shape of graphite, where the required properties are achieved by a change in graphite shape, its size and layout, and a change in the basic structure of the metal. This paper is focused on the continuous method of producing spheroidal graphite FLOTRET. In the introductory section is summarized the theoretical foundations of the secondary treatment of cast irons, especially the FLOTRET flow method, describes the advantages and disadvantages of the method. The practical part is divided into laboratory and operational tests. Laboratory experiments were conducted on a laboratory-type modifier FLOTRET chamber, which was designed and hydraulically optimized. Experiments were focused on the effects of pressure altitude and amount of modifier on the residual values of magnesium, as conditions for a successful modification. The method was tested in two foundries under operating conditions and in one of them was observed a long-term modification process.
In earlier works were described trends in the production of tools for die casting (hot work). Almost the entire set of issues dealt with may seem insignificant when incompletely assembled acceptance of the material and the associated risks of processing a material with an inappropriate structure, leading to a very early defect of the die. Therefore, further work will focus particularly on identifying the causes of thermal cracks and preventing a suitable choice of acceptance criteria conditions and heat treatment.
The results of investigations of the granulation process of foundry dusts generated in the dry mechanical reclamation process of used sands, where furan resins were binders are presented in the paper. Investigations concerned producing of granules of the determined dimensions and strength parameters. Granules were formed from the dusts mixture consisting in 50 mass% of dusts obtained after the reclamation of the furane sands and in 50 mass % of dusts from sands with bentonite. Dusts from the bentonite sands with water were used as a binder allowing the granulation of after reclamation dusts from the furane sands. The following parameters of the ready final product were determined: moisture content (W), shatter test of granules (Wz) performed directly after the granulation process and after 1, 3, 5, 10 days and nights of seasoning, water-resistance of granules after 24 hours of being immersed in water, surface porosity ep and volumetric porosity ev. In addition the shatter test and water-resistance of granulate dried at a temperature of 105oC were determined. Investigations were performed at the bowl angle of inclination 45o, for three rotational speeds of the bowl being: 10, 15, 20 rpm. For the speed of 10 rpm the granulation tests of dusts mixture after the preliminary mixing in the roller mixer and with the addition of water-glass in the amount of 2% in relation to the amount of dust were carried out. The obtained results indicate that the granulator allows to obtain granules from dusts originated from the reclamations of moulding sands with the furane resin with an addition of dusts from the bentonite sands processing plants.
The aim of the present study was to develop a modifier for water glass. The method of thermal generation of metal oxide nanoparticles was adapted and used in the research. Nanoparticles of ZnO from the thermal decomposition of basic zinc carbonate were used. A method for the modifier introduction was developed, and the effect of modifier content and organic solvent type on the physico-chemical properties of binder (viscosity) and quartz wettability was determined. Binder viscosity was examined from the flow curves plotted with the help of a RHEOTEST 2 rotational rheometer equipped with proper software. Quartz wettability was determined examining timerelated changes in the value of the contact angle in a quartz-binder system, until full stabilisation of the angle value has been achieved. Binder modification was carried out on sodium water glass designated as R"145". The water glass modifiers were suspensions of ZnO nanoparticles in propanol and methanol at a fixed concentration of c = 0.3 M and with the size of nanoparticles comprised in a range of <61 - 981 nm>. Water glass modification with the suspensions of ZnO nanoparticles in methanol and propanol showed the effect of modifier on the water glass viscosity and quartz wettability. This effect depends on the type of alcohol used. The ZnO suspension in propanol (alcohol with a longer hydrocarbon chain) affects more strongly the viscosity of binder and quartz wettability than the methanol suspension.
Suitability of the given binding agent for the moulding sands preparation depends on the one hand on the estimation of technological properties of the sand and the mould made of it and the obtained casting quality and on the other hand on the assessment of this sand influence on the natural and working environment. Out of moulding sands used in the foundry industry, sands with organic binders deserve a special attention. These binders are based on synthetic resins, which ensure obtaining the proper technological properties and sound castings, however, they negatively influence the environment. If in the initial state these resins are not very dangerous for people and for the environment, thus under an influence of high temperatures they generate very harmful products, being the result of their thermal decomposition. Depending on the kind of the applied resin (phenol-formaldehyde, urea, furfuryl, urea–furfuryl, alkyd) under an influence of a temperature such compounds as: furfuryl alcohol, formaldehyde, phenol, BTEX group (benzene, toluene, ethylbenzene, xylene), and also polycyclic aromatic hydrocarbons (PAH) can be formed and released. The aim of the study was the development of the method, selection of analytical methods and the determination of optimal conditions of formation compounds from the BTEX group. An emission of these components constitutes one of the basic criteria of the harmfulness assessment of binders applied for moulding and core sands. Investigations were carried out in the specially designed set up for the thermal decomposition of organic substances in a temperature range: 5000 C – 13000 C at the laboratory scale. The object for testing was alkyd resin applied as a binding material for moulding sands. Within investigations the minimal amount of adsorbent necessary for the adsorption of compounds released during the decomposition of the resin sample of a mass app. 15 mg was selected. Also the minimal amount of solvent needed for the desorption of compounds adsorbed in the column with adsorbent was found. The temperature range, in which the maximal amounts of benzene, toluene, ethylobenzene and xylenes are released from the resin, was defined. The qualitative and quantitative analyses of compounds from the BTEX group were performed by means of the gas chromatography combined with the mass spectrometry (GC/MS).
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