Foundry sand reclamation

Claim 1

A method of conditioning a spent foundry sand mixture, said mixture containing 0.1-12% clay, said clay forming a shell on the grains of said mixture, the method comprising: (a) while under ambient pressure and temperature conditions and without the addition of water, subjecting said mixture to a high-stress, low-kinetic energy squeezing action effective to slowly rub the mixture grains against each other and to fragment at least part of the shells on substantially each sand grain in said mixture, (b) while in the presence of a negative pressure or suction, propelling said squeezed mixture grains against a target and/or against each other in a high-kinetic energy stream, the sand mixture in said stream having flow rate of 1000-10,000 pounds per hour through a discharge opening having a diameter of 0.6-2 inches, whereby the remaining fragments of said shells on said mixture grains are dislodged and many particles finer than 200 mesh are separated by said suction, and (c) subject said mixture of burst shells and sand grains to classification for separation.

Claim 2

A method of conditioning a spent foundry sand mixture, said mixture containing 0.1-12% clay, said clay forming a shell on the grains of said mixture, the method comprising: (a) while under ambient pressure and temperature conditions and without the addition of water, subjecting said mixture to a high-stress, low-kinetic energy squeezing action effective to slowly rub the mixture grains against each other and to fragment at least part of the shells on substantially each sand grain in said mixture, (b) while in the presence of a negative pressure or suction, propelling said squeezed mixture grains against a target and/or against each other in a high-kinetic energy stream, the sand mixture in said stream having flow rate of 1000-10,000 pounds per hour through a discharge opening having a diameter of 0.6-2 inches, whereby the remaining fragments of said shells on said mixture grains are dislodged and many particles finer than 200 mesh are separated by said suction, and (c) subject said mixture of burst shells and sand grains to classification for separation.

Claim 8

A method of conditioning a used foundry sand mixture, said mixture containing at lease one or more elements selected from the group consisting of 0.1-12% clay, 0.5-10% combustible organic material, and lime, said selected elements forming a shell on the grains of said mixture, the method comprising: performing in sequence a mulling of said sand mixture for a period of time of about 6-30 minutes and then pneumatically scrubbing said mixture employing a flow rate of 1000-10,000 pounds/hr. through a discharge opening having a diameter of 0.6-2 inches, repeating said mulling and scrubbing sequence until the said mixture has a Ph factor of 6-9, substantially zero percent clay content, substantially zero percent organic combustible content, and 0.1% or less particle fines, and exhibits a density of at least 100 grams/biscuit when compacted.

Claim 9

A method of conditioning a used foundry sand mixture, said mixture containing at lease one or more elements selected from the group consisting of 0.1-12% clay, 0.5-10% combustible organic material, and lime, said selected elements forming a shell on the grains of said mixture, the method comprising: performing in sequence a mulling of said sand mixture for a period of time of about 6-30 minutes and then pneumatically scrubbing said mixture employing a flow rate of 1000-10,000 pounds/hr. through a discharge opening having a diameter of 0.6-2 inches, repeating said mulling and scrubbing sequence until the said mixture has a Ph factor of 6-9, substantially zero percent clay content, substantially zero percent organic combustible content, and 0.1% or less particle fines, and exhibits a density of at least 100 grams/biscuit when compacted.