Using the available analytical methods, including the determination of chemical composition using wavelength-dispersive X-ray
fluorescent spectroscopy technique and phase composition determined using X-ray diffraction, microstructural observations in a highresolution
scanning microscope equipped with an X-ray microanalysis system as well as determination of characteristic softening and
sintering temperatures using high-temperature microscope, the properties of particular chromite sands were defined. For the study has been
typed reference sand with chemical properties, physical and thermal, treated as standard, and the sands of the regeneration process and the
grinding process. Using these kinds of sand in foundries resulted in the occurrence of the phenomenon of the molding mass sintering.
Impurities were identified and causes of sintering of a moulding sand based on chromite sand were characterized. Next, research methods
enabling a quick evaluation of chromite sand suitability for use in the preparation of moulding sands were selected.
The aim of the hereby paper is to present the developed model of determining the volume and surface porosity based on the main fraction
of polifractional materials, its experimental verification and utilisation for the interpretation of effects accompanying the formation of a
moulding sand apparent density, porosity and permeability in the blowing processes of the core and moulds technology.
The drainage consolidation method has been efficiently used to deal with soft ground improvement. Nowadays, it has been suggested to use a new sand soil which is a composite of sand and recycled glass waste. The permeability performance of glass-sand soil was explored to judge the feasibility of glass-sand soil backfilled in the drainage consolidation of sand-drained ground. For comparison purposes, different mix proportions of recycled glass waste, fineness modulus, and glass particle size were analyzed to certify the impact on the permeability coefficient and the degree of consolidation. The numerical results show that adding a proper amount of recycled glass waste could promote the permeability performance of glass-sand soil, and the glasssand soil drain could be consolidated more quickly than a sand drain. Experiments showed that glass-sand soil with the a 20% mix of recycled glass waste reveals the optimum performance of permeability.
The goal of this article is to application of non-silica sands based on alumininosilicates as an alternative of traditionally used chromite sand for alloyed steel and iron castings. Basic parameters as bulk density, pH value of water suspension, refractoriness, grain shape of the testing sands were evaluated. Also mechanical properties of furan no-bake moulding mixtures with testing sand were determined. Finally, the influence of non-silica sand on casting quality was evaluated via semi-scale under normal casting production for sand characterization Optimization of production process and production costs were described.
The paper presents the test results of molding compounds, sand casting molds and their analysis. The subject of testing was compound containing furan resins prepared according to the following recipe: matrix – regenerate 90% + fresh sand – 10%, furan resin – 1.10% by weight, hardener – 0.40% by weight. The impact of adhesive type and its quantity (Quan = 0.90, 1.1 and 1.5%) on the strength indexes of molding compound subject to densification was analyzed. The publication presents the test results: tensile strength Rm, compressive strength Rc and flexural strength Rg, as well as compound permeability as function of its density. The analysis also covers the impact of density level on mold strength and the distribution of density level along the mold height.
Based on the test results, it was found that the best method to obtain high strength molds made from compounds with chemical adhesives was to densify it by vibrating the system: match plate – molding flask – compound filling the mold. The effectiveness of this densification method depends on the amplitude and frequency of vibrations.
The investigation results of the mechanical reclamation of spent moulding sands from the Cordis technology are presented in the paper.
The quality assessment of the obtained reclaim and the influence of the reclaim fraction in a matrix on the core sand strength is given. The
reclaim quality assessment was performed on the basis of the determination of losses on ignition, Na2O content on reclaim grains and pH
values. The reclaim constituted 100%, 75% and 50% of the core sand matrix, for which the bending strength was determined. The matrix
reclamation treatment was performed in the experimental rotor reclaimer RD-6. Spent sands were applied in as-delivered condition and
after the heating to a temperature of 140 o
C. Shaped samples for strength tests were made by shooting and hardening of sands in the warmbox
technology.
This study summarises the research efforts undertaken in iron foundry plants in which the process are mostly automated and mechanised.
The research program was limited in scope, focusing on causes of surface defects in castings products that are attributable to the
bentonite-containing sand and the mould system. One of the potential roots of surface defects is heterogeneity of sand grains, containing
lumped ball-shaped grains and irregular pellets with a layered-structure. The moisture contents of those lumped grains is different than
the moisture level required in the process, besides these grains may contain various elements and metallic compounds which, when cast
into moulds, may react with molten metals in an uncontrolled manner. As a result, surface defects are produced, such as surface blowholes,
burst penetration, sand holes, slag inclusions, pinhole porosity. This study investigated the efficiency of key sand preparation and
moulding machines and installations integrated into the casting process line. The efficiency of machines and installations is defined in
terms of quality parameters of sand mix and moulds, which are associated with the emergence of surface defects on castings.
Until now, the mould sand in general use in the foundry industry are based on bentonite, which resulted from the fact that a good recognition properties and phenomena associated with this material. Come to know and normalized content of montmorillonite and carbonates and their important role in the construction of bentonite, and mass properties of the participation of compressive strength or scatter. Halloysite is widely used in industry and beyond them. However, little is known about its use in the foundry in Poland and abroad. This article presents preliminary research conducted at the Foundry Department of Silesian University of Technology on this material. Will raise the question of the representation of this two materials, which contains information connected with history and formation of materials, their structure and chemical composition. In the research, the results of compressive strength tests in wet masses of quartz matrix, where as a binder is used halloysite and bentonite in different proportions.
The aim of this study was to assess sand accumulation in the gastrointestinal tract and fecal sand excretion in Silesian foals using three diagnostic methods and taking into account the sex and age of the animals. Another aim of the study was to compare the three diagnostic methods. The study was carried out on 21 clinically healthy Silesian foals (10 females and 11 males) from 9-28 weeks old grazed on permanent pasture. The sand intake was assessed using a sedimentation test, abdominal ultrasonography and a quantitative evaluation of sand per 100 g of stool. In the sedimentation test, the sand was palpable in the stool of 57.1% of the horses, and clearly visible in 42.9% of the animals. The ultrasound examination revealed the presence of sand in the gastrointestinal tract in 66.7% of the horses. It was limited to a single location in 60% of the horses, while it was present in several regions in 40% of the horses. The mean amount of sand was 0.14 ± 0.33 g per 100 g of stool. It did not exceed 0.1g in 71.4% foals, while it ranged from 0.1-0.5 g in 23.8% foals. In 4.8% of the animals, it amounted to 1.6 g per 100 g of stool. There was no correlation between age and gender and the results. There was a positive correlation between the ultrasound examination and the sedimentation test.
Sand may be accumulated in the gastrointestinal tract of foals without any clinical signs. The amount of sand excreted in the stool is not an indicator of the amount of sand accumulated in the gastrointestinal tract. An abdominal ultrasound examination should be combined with a sedimentation test for more specific results.
The aim of the study was to determine the applicability of a new product added to water glass-containing foundry sands hardened with
ethylene glycol diacetate. The new additive designated by the symbol "B" is a composition of aqueous solutions of modified polyalcohols,
improving the sand knocking out properties. The scope of studies included testing various mechanical and technological properties
of foundry sand mixtures, such as permeability, friability, life cycle of cores and knocking out properties.
In the technological studies, two types of water glass with different values of the silica modulus and density, designated as R145 and R150,
were used. Moulding sands were prepared with the additive "B". For comparison, reference sands with water glass but without the additive
"B" were also made. In Part I of the article, the results of studies of the effect of additive "B" on the properties of foundry sands with water
glass hardened by CO2 blowing were discussed.
In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is
presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within
100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared
with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation
of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand
grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The
observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in
internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at
elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular
particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of
chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand
and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.
The paper presents the idea of the integrated recycling system of used moulding sands with organic resins. A combination of the method of
forecasting averaged ignition loss values of moulding sands after casting and defining the range of necessary matrix reclamation
treatments in order to obtain its full recycling constitutes the basics of this process.
The results of own investigations, allowing to combine ignition loss values of spent moulding sands after casting knocking out with
amounts of dusts generated during the mechanical reclamation treatment of such sands, were utilized in the system.
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.
The results of investigations of the influence of the matrix grain sizes on properties of cores made by the blowing method are presented in
the hereby paper. Five kinds of matrices, differing in grain size compositions, determined by the laser diffraction method in the Analysette
22NanoTec device, were applied in investigations. Individual kinds of matrices were used for making core sands in the Cordis technology.
From these sands the shaped elements, for determining the apparent density of compacted sands and their bending strength, were made by
the blowing method. The shaped elements (cores) were made at shooting pressures being 3, 4 and 5 atn. The bending strength of samples
were determined directly after their preparation and after the storing time of 1 hour.
In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is
presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within
100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared
with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation
of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand
grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The
observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in
internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at
elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular
particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of
chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand
and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.
Core sands for blowing processes, belong to these sands in which small amount of the applied binding material has the ability of covering
the sand matrix surface in a way which - at relatively small coating thickness - allows to achieve the high strength. Although the deciding
factor constitute, in this aspect, strength properties of a binder, its viscosity and ability to moisten the matrix surface, the essential meaning
for the strength properties of the prepared moulding sand and the mould has the packing method of differing in sizes sand grains with the
coating of the binding material deposited on their surfaces.
The knowledge of the influence of the compaction degree of grains forming the core on the total contact surface area can be the essential
information concerning the core strength.
Forecasting the strength properties of core sands, at known properties of the applied chemically hardened binder and the quartz matrix,
requires certain modifications of the existing theoretical models. They should be made more realistic with regard to assumptions
concerning grain sizes composition of quartz sands and the packing structure deciding on the active surface area of the contacts between
grains of various sizes and - in consequence - on the final strength of cores.
The cumulative results of investigations of the possibility of using the reclaimed materials after the mechanical, thermal or
mechanical-thermal reclamation for making cores by means of the blowing method in the alkaline CO2 technology, are
presented in the paper. Three kinds of spent sands: with furfuryl resin, bentonite and alkaline phenolic resin, obtained from
the foundry, were subjected to three kinds of reclamation: mechanical, thermal and combined mechanical-thermal, applying
for this aim adequate experimental devices. The obtained reclaims were assessed with regard to the degree of the matrix
liberation from the determined binding material. Reclaims of moulding sands with binders of the form of resin were assessed
with regard to ignition loss values and pH reaction, while reclaims of moulding sands with bentonite with regard to the
residual clay content and pH value. In all cases the results of the performed sieve analyses were estimated and the average
characteristic diameter dl was determined. The reclaimed matrix was applied as a full substitute of the fresh high-silica sand in typical
procedures of preparing core sands used for making shaped samples for bending strength investigations, Rg
u
.
The vegetation of the Chernihiv city sands (natural and technogenic origin) has rather high syntaxonomic diversity (17 associations and 5 initial communities) and the ruderal phytocoenoses prevail. Natural phytocenoses are represented to a small extent (Cyperetum flavescentis Koch 1926, Dichostylidi–Helochloetum alopecuroidis (Timar 1950) Pietsch 1973, Artemisia scoparia–Dianthus borbasii community, Kochietum arenariae Fijalk 1978). Synanthropic psammophytes species communities that are more resistant to anthropogenic influence, are formed under urban conditions. The ecological range of vegetation of sandy alluvia varies from xerophytic phytocoenoses in mineral-poor sand (Kochietum arenariae) to the communities, which indicate waterlogged areas with increased mineralization of water and saline bottom sediments (Typhetum laxmannii Nedulcu 1968). Itispossibletoobserve the adventization and apophization of sand vegetation, one of the indicators of which is the rupture of coenotic connections between the species of the community. These phenomena indicate that the process of synanthropization of the vegetation cover of the city keeps intensifying, and first of all, occurs in places of newly formed technogenic ecotopes.
The most common chemical’s spills in typical transportation accidents are those with petroleum products such as diesel fuel, the consequence of which is an extensive pollution of the soil. In order to plan properly fuel recovery from the soil, it is important to gain information about the soil depth which may be affected by pollutant and to predict the pollutant concentration in different soil layers. This study deals with the impact of basic atmospheric conditions, i.e. air temperature and humidity on the diesel fuel migration through the soil. The diesel fuel was spilled into columns (L = 30 cm; D = 4.6 cm) filled with sandy and clay soil samples, and its concentrations at various depths were measured after 11 days under various air temperature (20 and 40°C) and relative humidity (30–100%) conditions. The effects observed were explained by understanding physical processes, such as fuel evaporation, diffusion and adsorption on soil grains. The increase in temperature results in higher fuel evaporation loss and its faster vertical migration. The relative humidity effect is less pronounced but more complex, and it depends much on the soil type.
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.