A method of extracting chemical substances from used molding sand includes: preparing a mixture of used molding sand and liquid, wherein the used molding sand includes a sand material and at least one chemical substance; and cleaning the mixture via an ultrasonic cleaning process to separate and extract the at least one chemical substance from the sand material.

Both a hydraulic (wet) separation process and a dry separation process are used in combination to recover sand, bentonite clay and organics from foundry waste created during operation of a green sand foundry. These recovered ingredients are then recycled for reuse in making additional green sand molds.

A system for processing a sand product includes a process tank having a first compartment, a second compartment in fluid communication with the first compartment, and a third compartment that is isolated from the first compartment and the second compartment. The system also includes a first hydrocyclone configured to receive a sand mixture comprising the sand product and water from the first compartment, and separate the sand mixture into wet sand and a clay mixture. The second compartment is configured to receive the wet sand and clay mixture from the first hydrocyclone. The system also includes a second hydrocyclone configured to receive the wet sand and the clay mixture from the second compartment, and further separate the wet sand from the clay mixture to produce a clay product that can include a fully hydrated clay material. The third compartment is configured to receive the clay product from the second hydrocyclone.

To provide a reclamation method of foundry sand capable of suppressing deterioration in strength of core after remanufacturing. A reclamation method of foundry sand includes: a preparation step for preparing foundry sand to which a binder is adhered; a washing step for washing the foundry sand prepared in the preparation step; a polishing step for polishing the foundry sand washed in the washing step; and rinsing step for rinsing the foundry sand polished in the polishing step.