An Analysis of the Possibilities of reclaiming Resol-bonded Sands hardened with Methylformate

Abstract

There is a close connection with developments in engineering and in the use of new technology with the effect on the environment. In the case of sands bonded with resols hardened with methylformate, one of the latest techniques to be employed by the foundry industry, it is therefore natural that the maximum attention has been paid to reclamation of used sand, the efficient use of reclaimed materials, and keeping waste to a minimum. This paper is based on a theoretical analysis of the resol/methylformate binder system in relation to reclamation and the effect of the hardening mechanism. The results, presented in detail, include temperature effects on loss-on-ignition values, and residual alkalinity. It is inferred that there should be a maximum temperature level of 600°C imposed on any attempt to carry out thermal reclamation. Thermal reclamation at 550°C, and the repeated reuse of reclaimed sand, without any input of new material was checked in performance tests. An initial mixture was prepared using 100% zircon sand, bonded with 1.2% of resin. In the fourth cycle of reuse, the sand was suddenly found to be unusable. Overcoming this problem has led to the development of new methods which make it possible to obtain reclaimed sand with superior properties. A survey of the resultant tests and an analysis of possible modifications to the properties of reclaimed sand will be presented in a subsequent paper.