Reuse of spent foundry sand as hydraulic barrier layer in landfill

Abstract

Spent foundry sand is considered as non-hazardous waste because leachate of the heavy metals from spent foundry sand are lower thanthe government standards. Foundry sands are primarily mixtures of sand and bentonite. They have inherent potential to be used in the construction of hydraulic barrier layers because sand-bentonite mixtures can be compacted to achieve hydraulic conductivities of less than 1x10⁻⁷ cm/sec. Moreover, reuse of spent foundry sand can reduce the amount of wastes going to landfill and help the foundries' to save the costs of handling wastes. Based on this study, the results are 1) moldability correlates well with bentonite content and spent foundry sand can be molded for bentonite content greater than 16% 2) when the bentonite content is greater than 11%, the hydraulic conductivity is less than 1x10⁻⁷ cm/s. So, Spent foundry sand can be reused as hydraulic barrier layers based on permeability and moldability both as-received and as mixture with pure sand until it has bentonite content of greater than 16%.