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.

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 results of the efficiency of the primary reclamation process as well as the influence of the used sand temperature and other process parameters on it are presented in this paper. A separate stand realized on a reduced scale was built, which is an analogous process of the primary reclamation treatment of spent foundry sands. The used sands were introduced to the crushing process in an agglomerated form in the way typically used in industrial devices. The primary reclamation process was realized on a set of four horizontal sieves with decreasing mesh clearances while maintaining their geometrical dimensions applied in the Regmas industrial device. The model system consists of a vibratory drive mounted on the table, allowing us to control the supply frequency of the vibratory motors within a range of 40-60 Hz as well as the computer system for measuring the vibration parameters and drive power. The used sand on the quartz matrix with the KALTHARZ U404 resin and 100T3 hardener was used in our investigations. The used sand was prepared under the following conditions: cubic-shaped elements made of the applied furan sand was compacted by vibrations then hardened and subjected to heating under controlled conditions (as a “simulation” of the overheating process taking place in the mold after pouring). Time functions of the crushing and sieving process in dependence of the overheating degree of the reference sand samples (100°, 200°, and 300°C) were investigated at various table vibration frequencies and feed loads of the sieve set. The relative index of the crushing ability was determined.

The investigation results of the reclamation of spent moulding sands with furfuryl resin are presented in this paper. The reclamation

process was performed in the secondary reclamation chamber of the REGMAS 1.5 vibratory reclaimer. 70 kg portions of moulding sands,

previously subjected to the primary reclamation and dedusting, were used. The secondary reclamation was performed in two stages: the

first consisted of determining the reclaimer intensity at various reclamation times (5 min, 10 min and 15 min) and various electrovibrator

frequencies (40 Hz, 50 Hz and 60 Hz), the second consisted of determining the influence of additional crushing elements on the intensity

of processes.

In the knock-out process, as well as in the preliminary phase of moulding sand reclamation, the issue of energy demand for the process of crushing used sand agglutinations, preferably to single grains, is particularly important. At present, numerical values of moulding sand impact resistance, which would allow energy-related aspects of this process to be forecast, are not known, as such research has not been carried out. It seems that impact resistance tested on very small cross-section samples, which allows us to very precisely reveal some unique features of a moulding sand with organic and inorganic binders, is an important parameter, which so far has not been taken into account for evaluation of mechanical properties of moulding sands. Preliminary attempts to determine impact resistance of moulding sands have been carried out as part of own research of the author. The conducted investigations aimed at determining the relationships between the obtained values of tensile strength and impact resistance of moulding sands. In addition, the effect of holding samples at temperatures of 100oC, 200oC, 300oC on the value of impact resistance was determined, both for sands made with fresh and with reclaimed sand grains.

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.

Mechanical reclamation process of spent moulding sands generate large amounts dusts containing mainly rubbed spent binding agents and quartz dust. The amounts of post-reclamation dusts, depending of the reclamation system efficiency and reclaim dedusting system, can reach 5 -10% in relation to the total reclaimed moulding sand. This dust due to the high content of the organic substances is a threat to the environment and therefore requires the storage on landfills specially adapted for this type of waste. On the other hand, the presence of organic substances causes that these dusts have relatively high energy values that could be used. However, at present there is no coherent, environmentally friendly concept for the management of this type of dust. The paper presents the results of tests of thermal utilization the dusts (as a source of energy) were carried out at AGH University of Science and Technology. Thermal utilization of dusts was carried out in the co-burning with carbon carriers process or in individual burning (Patent PL 227878 B1 and patent application PL - 411 902).

Experiments of filling the model moulds cavity of various inner shapes inserted in rectangular cavity of the casting die (dimensions: 280

mm (height) x 190 mm (width) x 10 mm (depth) by applying model liquids of various density and viscosity are presented in the paper.

Influence of die venting as well as inlet system area and inlet velocity on the volumetric rate of filling of the model liquid – achieved by

means of filming the process in the system of a cold-chamber casting die was tested. Experiments compared with the results of simulation

performed by means of the calculation module Novacast (Novaflow&Solid) for the selected various casting conditions – are also

presented in the paper.

The paper, especially dealt with problems of reclamation of used furan sand, carried out in new, vibratory sand reclamation unit REGMAS

developed by researches from AGH-University of Science and Technology, Faculty of Foundry Engineering in Cracow (Poland).

Functional characteristics of reclamation unit as well as the results of reclamation of used sand with furfuryl resin are discussed in the

paper. The quality of reclaim was tested by means of the LOI and pH value, dust content in the reclaim and at least by the the quality of

the castings produced in moulds prepared with the use of reclaimed matrix.

The effects of filling the core box cavity and sand compaction in processes of core production by blowing methods (blowing, shooting)

depend on several main factors. The most important are: geometrical parameters of cavity and complexity of its shape, number,

distribution and shape of blowing holes feeding sands as well as the venting of a technological cavity. Values of individual parameters are

selected according to various criteria, but mostly they should be adjusted to properties of the applied core sand.

Various methods developed by several researchers, including the authors own attempts, allow to assess core sands properties on the basis

of special technological tests projecting the process into a laboratory scale. The developed criteria defining a degree or a filling ability

factor provide a better possibility of assessing the core sand behavior during flowing and core box filling, which indicate the value and

structure of the obtained compacting decisive – after hardening – for strength and permeability. The mentioned above aspects are analyzed

– on the basis of authors’ own examinations - in the hereby paper.

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

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