The analysis of after reclamation dusts generated during the reclamation treatment of test portions of two kinds of polydispersive material in the Regmas device, is presented in the hereby paper. For the comparative purpose the fresh moulding sand marked as quartz sand „Sibelco” –1K 0.40/0.32/0.20, J88, >14000C, WK = 1.20 (acc. PN-83/H-11077), as well as the spent moulding sand, which was previously subjected to the primary reclamation and to dedusting, were used. Conditions of the process treatment were forced by the frequency of supplying the vibratory drive motors being successively 40, 50 and 60Hz for 5, 10 and 15 min. and by causing a diversified material flow through the functional system of the device (charging hopper, abrasive chamber acting as a buffer space). Two states of the process treatment, when a material was flowing through the chamber, were applied. In the first one, an intergranular surface abrasion of grains occurred as a result of the granular material circulation in the chamber forced by the vibratory drive. In the second one, the forced material flow was performed in the presence of crushing elements (steel balls), additionally introduced into the abrasive chamber. Analyses of the device influence were performed by determinations of the amount of dusts separated in the pneumatic classifier and analysis of their grain sizes by means of Analysette 22NanoTec.
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.
The article presents the results of selected energy parameters calculations, carried out for the recorded values of instantaneous voltages and currents in the three-phase power supply of the model vibratory unit. The parameters were the values of active and apparent power taken from the drive consisting of two electric motors supplied by the inverter for selected frequency settings and directly from the power grid. In addition, calculations of tgφ power factor values were made to evaluate the compensation of reactive power consumption in the tested power systems. Measurements and calculations lead to the conclusion that if the frequency of the inverter output voltage rises, the active and apparent power consumed by the model vibratory drive unit increases. The active and apparent power for setting the output frequency of the inverter from 50 Hz was less than the active and apparent power taken by the model vibratory unit that was powered directly from the power grid. The power factor tgφ in the power supply system was approximately 6, except one case (f = 30 Hz).
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
u
.
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.
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