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EN
The paper presents the results of an investigation of the gases emission of moulding sands with an inorganic (geopolymer) binder with a relaxation additive, whose main task is to reduce the final (residual) strength and improves knocking-out properties of moulding sand. The moulding sand without a relaxation additive was the reference point. The research was carried out using in accordance with the procedure developed at the Faculty of Foundry Engineering of AGH - University of Science and Technology, on the patented stand for determining gas emissions. Quantification of BTEX compounds was performed involving gas chromatography method (GC).The study showed that the introduction of relaxation additive has no negative impact on gas emissions - both in terms of the total amount of gases generated, as well as emissions of BTEX compounds. Among the BTEX compounds, only benzene is emitted from the tested moulding sands. Its emission is associated with the introduction a small amount of an organic hardener from the group of esters.
EN
The problem of harmful casting resins has been present in foundries for many years. Manufacturers are introducing new products that contain in their composition environmentally and eco-friendly ingredients. Unfortunately, not all types of technology can be used, sometimes environmental benefits are disproportionate to the quality of castings and their price. In the foundry industry, the most popular binders are based on organic compounds (often carcinogenic) and other harmful substances. Due to strict legal regulations regarding environmental protection, as well as care for the foundry's workers' comfort - their occurrence should be reduce to a minimum. These compounds often behave also depending on the conditions of use (temperature, atmosphere). The application of various methods of thermal analysis and spectroscopic methods allows to verify the mechanism of resin decomposition process in relation to conditions in the form in both inert and oxidizing atmosphere. For analysis the resins from cold-box technology, were used TG–DTG–DSC, Py-GC/MS methods and specified the course of changes occurring in combination of different atmosphere.
EN
This paper focuses on the thermal behavior of the starch-based binder (Albertine F/1 by Hüttenes-Albertus) used in foundry technology of molding sand. The analysis of the course of decomposition of the starch material under controlled heating in the temperature range of 25- 1100°C was conducted. Thermal analysis methods (TG-DTG-DSC), pyrolysis gas chromatography coupled with mass spectrometry (Py- GC/MS) and diffuse reflectance spectroscopy (DRIFT) were used. The application of various methods of thermal analysis and spectroscopic methods allows to verify the binder decomposition process in relation to conditions in the form in both inert and oxidizing atmosphere. It was confirmed that the binder decomposition is a complex multistage process. The identification of CO2 formation at set temperature range indicated the progressive process of decomposition. A qualitative evaluation of pyrolysis products was carried out and the course of structural changes occurring in the presence of oxygen was determined based on thermo-analytical investigations the temperature of the beginning of binder degradation in set condition was determined. It was noticed that, significant intensification of Albertine F/1 sample decomposition with formation of more degradation products took place at temperatures above 550ºC. Aromatic hydrocarbons were identified at 1100ºC.
EN
Foundry waxes currently used in lost-wax casting technology are composed of paraffin, stearin, and – to a lesser extent – ceresin, polyethylene wax, and other natural and synthetic waxes. Most of these compounds are non-toxic; however, they may release aromatic hydrocarbons as a result of exposure to high temperatures. Based on a chromatographic analysis (pyrolysis gas chromatography-mass spectrometry, Py-GC/MS), the compounds that are separated from the popular wax mixtures used in foundries were evaluated (as well as the impact they may have on foundry workers). For this purpose, the three main stages of the process (wax, burnout, and pouring) were analyzed, and the appropriate test temperature was chosen (similar to the actual conditions during the process).
EN
It was found that the addition of carbon fibers (CFs) does not affect the crosslinking process in the microwave radiation (800 W, 2.45 GHz) of the BioCo2 binder, which is a water solution of poly(acrylic acid) and dextrin (PAA/D). It has influence on BioCo2 thermal properties. The CFs addition improves the thermostability of a binder and leads to the reduction of gas products quantity generated in the temperature range of 300-1100°C (TG-DTG, Py-GC/MS). Moreover, it causes the emission of harmful decomposition products such as benzene, toluene, xylene and styrene to be registered in a higher temperatures (above 700°C). BioCo2 binder without CFs addition is characterized by the emission of these substances in the lower temperature range. This indicates the positive effect of carbon fibers presence on the amount of released harmful products. The selected technological tests (permeability, friability, bending strength, tensile strength) have shown that the moulding sand with the 0.3 parts by weight carbon fibers addition displays the worst properties. The addition of 0.1 parts by weight of CFs is sufficient to obtain a beneficial effect on the analyzed moulding sands properties. The reduction of harmful substances at the higher temperatures can also be observed.
EN
In many foundries, the requirements placed on castings production have risen mainly over the few years. Further trends in recent years have been the ever increasing level of automation and introduction of new alloys, especially composites. On the other hand, the foundry environment has become increasingly difficult because is used many organic binders. Environmental regulations will be further tightened up. These processes are pursued at national, European and global level. Conformity with emission limits is becoming increasingly difficult. The problem is emission of aromatic hydrocarbons, phenol, odours and other harmful compounds to environment. The main purpose of many companies is reduction of this toxins. The new cold-box systems (based on phenolic resins) try to reduce the emission by introducing into the resin structure silicate modifiers. Research presented of this article evaluate the effectiveness of these methods. The results show comparison of two resins ("without" and "with" silicate modifier) for assessment of emission of harmful aromatic hydrocarbons and phenol.
EN
In the foundry industry, many harmful compounds can be found, which as a result of gradual but long-term exposure to employees bring negative results. One of such compounds is phenol (aromatic organic compound), which its vapours are corrosive to the eyes, the skin, and the respiratory tract. Exposition to this compound also may cause harmful effects on the central nervous system and heart, resulting in dysrhythmia, seizures, and coma. Phenol is a component of many foundry resins, especially used in shell moulds in the form of resin-coated sands. In order to identify it, the pyrolysis gas chromatography-mass spectrometry method (Py-GC/MS) was used. The tests were carried out in conditions close to real (shell mould process – temperature 300°C). During the measurement, attention was focused on the appropriate selection of chromatographic analysis conditions in order to best separate the compounds, as it is difficult to separate the phenol and its derivatives. The identification of compounds was based on own standards.
EN
The organo-inorganic commercial binder Albertine F/1 (Hüttenes-Albertus) constituting the starch-aluminosilicate mixture was directed to structural studies. The paper presents a detailed structural analysis of the binder before and after exposure to physical curing agents (microwaves, high temperature) based on the results of infrared spectroscopy studies (FTIR). An analysis of structural changes taking place in the binder system with the quartz matrix was also carried out. Based on the course of the obtained IR spectra, it was found that during the exposure on physical agents there are structural changes within the hydroxyl groups in the polymeric starch chains and silanol groups derived from aluminosilicate as well as in the quartz matrix (SiO2). The curing of the molding sand takes place due to the evaporation of the solvent water and the formation of intramolecular and intermolecular cross-linking hydrogen bonds. Type and amount of hydrogen bonds presence in cured molding sand have an impact on selected properties of molding sand. Results indicates that for molding sand with Albertine F/1 during conventional heating a more extensive network of hydrogen bonds is created.
EN
The article presents the results of surface morphology of dust from dry dedusting of moulding sand with bentonite and mixtures of bentonite with lustrous carbon carrier using scanning electron microscopy. The study identifies the approximate chemical composition of the dust, and compares it with the composition of starting mixtures. The mixtures of bentonite with lustrous carbon carrier from different manufacturers differ in chemical composition. The process of de- dusting should be carried out using properly selected operating parameters of the dedusting equipment. If the process of dedusting is carried out incorrectly, it can lead to the loss of valuable components.
PL
W artykule przedstawiono wyniki badań morfologii powierzchni pyłów z suchego odpylania mas formierskich z bentonitem oraz mieszanek bentonitu z nośnikiem węgla błyszczącego z wykorzystaniem mikroskopii skaningowej. Badania pozwoliły wskazać przybliżony skład chemiczny pyłu i porównać go ze składem mieszanek wyjściowych. Mieszanki bentonitu z nośnikiem węgla błyszczącego oferowane przez ich producentów różnią się pod względem składu chemicznego. Proces odpylania mas formierskich z bentonitem powinien przebiegać przy odpowiednio dobranych parametry pracy urządzeń odpylających. Niewłaściwie prowadzony proces odpylania może doprowadzić do utraty cennych składników.
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PL
Metoda odlewania kokilowego opiera się na odlewaniu do metalowych, trwałych form, co pozwala na uzyskanie dużej liczby odlewów o praktycznie identycznych kształtach. W porównaniu z technologią odlewania do form piaskowych ma ona wiele zalet. Tym samym jednak posiada zupełnie inne wymagania dotyczące zarówno warunków wypełniania formy, jak również krzepnięcia metalu. Dlatego istotny wydaje się być dobór odpowiednich pokryć ochronnych na formy, które spełnią zadania kontroli poszczególnych procesów, a także ułatwią usuwanie odlewu, czy przedłużą żywotność form metalowych. W ramach pracy wykonano badania lepkości dynamicznej oraz umownej powłok ochronnych (podkładowych, izolacyjnych i przewodzących ciepło) stosowanych na formy metalowe. Badania prowadzono w temperaturze 25°C. Dokonano również próby oceny ekologiczności stosowanych powłok w temperaturze ich nakładania na formy metalowe (200°C) oraz w temperaturze pracy form (400°C) na podstawie badań chromatograficznych.
EN
The die casting method is based on casting into permanent metal moulds, which makes it possible to obtain a large amount of casts with practically identical shapes. Compared to the technology of sand mould casting, this method has many advantages. However, it thus faces completely different requirements concerning the conditions of both filling the mould and metal solidification. That is why it seems important to select the appropriate protective coatings applied on the moulds, which provide control over the particular processes as well as facilitate the removal of the cast and prolong the durability of the metal moulds. The study included investigations of the dynamic and relative viscosity of protective coatings (ground, insulating and thermal conductive) used for metal moulds. The examinations were performed at 25°C. Also, an attempt was made at evaluating the environmental performance of the used coatings at the temperature of their application onto the metal moulds (200°C) as well as the temperature of the moulds’ operation (400°C) based on chromatographic tests.
EN
TG-DTG-DSC, FTIR, DRIFT, and Py-GC-MS studies have been conducted to determine the effect of the thermal decomposition conditions and structure of foundry binder BioCo3 in the form of a composition poly(sodium acrylate)/dextrin (PAANa/D) on the progress of degradation in terms of processes occurring in foundry sands in contact with liquid metal. TG-DTG-DSC curves of the composition allowed us to determine the temperature range in which they do not undergo degradation, by which they do not lose their binding properties. With temperature increasing, physical and chemical changes occur that are related to the evaporation of solvent water (20–110°C), followed by the release of constitution water, and finally intermolecular dehydration (110–230°C). In this temperature range, processes that are mainly reversible take place. Within a temperature range of 450–826°C, polymer chains are decomposed, including the decomposition of side chains. Within a temperature range of 399–663°C, polymer composition decomposition can be observed (FTIR, DRIFT), and gas products are generated from this destruction (Py-GC-MS).
EN
The paper presents the results of thermoanalytical studies by TG/DTG/DTA, FTIR and GC/MS for the oil sand used in art and precision foundry. On the basis of course of DTG and DTA curves the characteristic temperature points for thermal effects accompanying the thermal decomposition reactions were determined. This results were linked with structural changes occurred in sample. It has been shown that the highest weight loss of the sample at temperatures of about 320°C is associated with destruction of C-H bonds (FTIR). In addition, a large volume of gases and high amounts of compounds from the BTEX group are generated when liquid metal interacts with oil sand. The results show, that compared to other molding sands used in foundry, this material is characterized by the highest gaseous emissions and the highest harmfulness, because benzene emissions per kilogram of oil sand are more than 7 times higher than molding sand with furan and phenolic binders and green sand with bentonite and lustrous carbon carrier.
EN
Emission of gases under high temperature after pouring molten metal into moulds, which contain the organic binder or other additives (solvents or curing agent), may be an important factor influencing both on the quality of the produced castings, and on the state of environment. Therefore, a comprehensive studies of the emitted gases would allow to determine restrictions on the use of the moulding sands in foundry technologies, eg. the probability of occurrence of casting defects, and identify the gaseous pollutants emitted to the environment. The aim of the research presented in this paper was to determine the amount of gases that are released at high temperatures from moulding sands bonded by biopolymer binder and the quantitative assessment of the emitted pollutants with particular emphasis on chemical compounds: benzene, toluene, ethylbenzene and xylenes (BTEX). The water-soluble modified potato starch as a sodium carboxymethyl starch with low (CMS-NaL) or high (CMS-NaH) degree of substitution was a binder in the tested moulding sands. A tests of gases emission level were conducted according to the procedure developed at the Faculty of Foundry Engineering (AGH University of Science and Technology) involving gas chromatography method (GC). The obtained results of the determination of amount of BTEX compounds generated during the decomposition process of starch binders showed lower emission of aromatic hydrocarbons in comparison with binder based on resin Kaltharz U404 with the acidic curing agent commonly used in the foundries.
EN
The effects of silica additive (Poraver) on selected properties of BioCo3 binder in form of an aqueous poly(sodium acrylate) and dextrin (PAANa/D) binder were determined. Based on the results of the thermoanalytical studies (TG-DTG, FTIR, Py-GC/MS), it was found that the silica additive results in the increase of the thermostability of the BioCo3 binder and its contribution does not affect the increase in the level of emissions of organic destruction products. Compounds from group of aromatic hydrocarbons are only generated in the third set temperature range (420-838°C). The addition of silicate into the moulding sand with BioCo3 causes also the formation of a hydrogen bonds network with its share in the microwave radiation field and they are mainly responsible for maintaining the cross-linked structures in the mineral matrix system. As a consequence, the microwave curing process in the presence of Poraver leads to improved strength properties of the moulding sand […]. The addition of Poraver's silica to moulding sand did not alter the permeability of the moulding sand samples, and consequently reduced their friability. Microstructure investigations (SEM) of microwave-cured samples have confirmed that heterogeneous sand grains are bonded to one another through a binder film (bridges).
PL
Sypkie masy szybkoutwardzalne z żywicami syntetycznymi, nazywane zwyczajowo technologiami cold-box, zdominowały proces wytwarzania rdzeni odlewniczych. Charakterystyczną cechą tych technologii jest sposób przygotowywania masy, którą sporządza się bez dodatku utwardzacza. Środek utwardzający (w postaci zgazowanej) wprowadza się poprzez przegazowywanie go do zagęszczonego rdzenia. W grupie tych technologii największe znaczenie posiada fenolowy proces cold-box (Ashland-cold-box, Pur-cold-box). Ocena szkodliwości tych mas rdzeniowych dla otoczenia wymaga uwzględnienia ilości i toksyczności wydzielanych gazów. Głównym hamulcem ograniczającym technologię cold-box z udziałem aminy jest problem związany z jej neutralizacją i obawy dotyczące szkodliwości dla otoczenia. Do oceny ekologiczności spoiw odlewniczych nadają się badania pirolityczne w połączeniu z metodą chromatografii gazowej sprzężonej ze spektrometrią mas (Py-GC/MS). W artykule przedstawiono wyniki badań chromatograficznych wybranych produktów rozkładu termicznego (BTEX – głównie benzen, toluen oraz fenol) masy rdzeniowej wykonanej w klasycznej technologii cold-box. Badania przeprowadzono w atmosferze obojętnej, w temperaturze 500°C i 1200°C.
EN
Loose rapid hardening masses with synthetic resins, customarily called cold-box technologies, have dominated the process of casting core production. A distinguishing feature of these technologies is the manner of mass preparation without the use of a hardener. The hardening agent (in the gaseous form) is introduced by way of its gasification into the condensed core. In the group of these technologies, the most significant one is the phenol cold-box process (Ashland-cold-box, Pur-cold-box). The evaluation of the harmfulness of these core sands to the environment requires consideration of the amount and toxicity of the released gases. The main limitation of the cold-box technology with the participation of amine is connected with its neutralization and its harmfulness to the environment. For the evaluation of environmental performance of casting binders, it is suitable to apply pyrolytic testing in combination with the gas chromatography method (Py-GC/MS). The article presents the results of chromatographic tests of selected products of thermal decomposition (BTEX – mainly benzene, toluene and phenol) of core sand made in the classic cold-box technology. The investigations were performed in inert atmosphere, at the temperature of 500°C and 1200°C.
EN
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. These resins in their 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, under an influence of a temperature such compounds as: furfuryl alcohol, formaldehyde, phenol, BTEX group (benzene, toluene, ethylbenzene, xylene), and also polycyclic aromatic hydrocarbons (PAHs) 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 and PAHs group. Investigations were carried out in the specially designed set up for the thermal decomposition of organic substances in a temperature range: 500 – 1 300°C at the laboratory scale. The object for testing was alkyd resin applied as a binding material for moulding sands. The qualitative and quantitative analyses of compounds were performed by means of the gas chromatography coupled with the mass spectrometry (GC/MS).
EN
The article presents research results of physico-chemical and environmental issues for the dust generated during dedusting of the installation for the processing and preparation of moulding sand with bentonite. Particular attention was paid to the content of heavy metals and emission of gases from the BTEX group, which is one of the determinants of the moulding sands harmfulness for the environment. The analysis of heavy metals in the test samples indicate that there is an increase of the content of all metals in the dust compared to the initial mixture of bentonite. The most significant (almost double) increase observed for zinc is probably related to the adsorption of this element on the dust surface by contact with the liquid metal. The study showed, that dust contained more than 20% of the amount of montmorillonite and had a loss on ignition at a similar level. The addition of 1% of dust to the used moulding sand results in almost 30% increase in the total volume of gases generated in casting processes and nearly 30% increase of the benzene emission.
EN
The furan resin offers advantages such as high intensity, low viscosity, good humidity resistance and is suitable for cast different casting alloys: steel, cast iron and non-ferrous metal casting. For hardening furan resins are used different hardeners (acid catalysts). The acid catalysts have significant effects on the properties of the cured binder (e,g. binding strength and thermal stability) [1 - 3]. Investigations of the gases emission in the test foundry plant were performed according to the original method developed in the Faculty of Foundry Engineering, AGH UST. The analysis is carried out by the gas chromatography method with the application of the flame-ionising detector (FID) (TRACE GC Ultra THERMO SCIENTIFIC).
EN
No-bake process refers to the use of chemical binders to bond the moulding sand. Sand is moved to the mould fill station in preparation for filling of the mould. A mixer is used to blend the sand with the chemical binder and activator. As the sand exits the mixer, the binder begins the chemical process of hardening. This paper presents the results of decomposition of the moulding sands with modified urea-furfuryl resin (with the low content of furfuryl alcohol below 25 % and different activators: organic and inorganic) on a quartz matrix, under semi-industrial conditions. Investigations of the gases emission in the test foundry plant were executed according to the method extended in the Faculty of Foundry Engineering (AGH University of Science and Technology). Article presents the results of the emitted chosen aromatic hydrocarbons and loss on ignition compared with the different activators used to harden this resin. On the bases of the data, it is possible to determine the content of the emitted dangerous substances from the moulding sand according to the content of loss on ignition.
EN
The harmfulness assessment of moulding sands with a geopolymer binder and a new hardener, in an aspect of the emission of substances from the BTEX group, was performed. Within the expedience project the new series of hardeners for the inorganic GEOPOL binder was developed. Before the introduction of the new system of moulding sands it was necessary to estimate their influence on the environment. To this aim the gasses emission from moulding sands subjected to the influence of liquid cast iron was tested with regard to the content of the gases from the BTEX group (benzene, toluene, ethylbenzene and xylenes). For the comparison the analogous investigations of the up to now applied moulding sands with the geopolymer binder, were performed. It was found that both systems of moulding sands binding emit similar amounts of gases, as well as similar amounts of substances from the BTEX group. Moulding sands with the GEOPOL binder are much more environmentally friendly than moulding sands with organic binders. The content of the BTEX group substances in gases emitted from moulding sands with the GEOPOL binder was approximately 10-times lower than in case of the moulding sands with organic binders.
PL
W ramach projektu celowego opracowano nową serię utwardzaczy dla spoiwa nieorganicznego Geopol. Przed wprowadzeniem nowego systemu mas formierskich konieczne było określenie ich wpływu na środowisko. W tym celu przeprowadzono badania emisji gazów z mas poddanych oddziaływaniu ciekłego żeliwa pod kątem zawartości w tych gazach związków z grupy BTEX (benzen, toluen, etylobenzen i ksyleny). Dla porównania przeprowadzono analogiczne badania dotychczas stosowanego systemu wiązania masy ze spoiwem geopolimerowym. Stwierdzono, ze obydwa systemy wiązania mas formierskich emitują zbliżone ilości gazów, jak również związków z grupy BTEX. W porównaniu do mas ze spoiwami organicznymi można uznać, że masy ze spoiwem GEOPOL są wysoce przyjazne dla środowiska. Zawartość związków z grupy BTEX w gazach emitowanych z mas ze spoiwem GEOPOL była około 10-krotnie mniejsza niż w przypadku mas ze spoiwami organicznymi.
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