Cryogenic metal chip reclamation

Claim 1

A method of making a metal powder suitable for use as a sinterable powder, the method comprising: a. selecting and conveying a charge of metal pieces along a continuous stream, said pieces having a transverse dimension no greater than 1/2 inch, b. injecting and directing a liquified cryogenic cooling medium, said medium being normally gaseous at ambient temperature conditions, against at least one section of said stream in sufficient amount to reduce the temperature of all the scrap pieces passing through said section to a temperature below the ductile-brittle transition temperature of the metal pieces, c. immediately conveying the super cooled metal pieces into a circulatory path and repetitively bringing a series of impacting elements against said super cooled pieces causing said pieces to fragment into particles and d. during said impaction of step (c) injecting a liquid cryogenic cooling medium into said path to insure said pieces and fragmented particles remain below said ductile-brittle transition temperature during any number of circulations in said path.

Claim 2

A method of making a metal powder suitable for use as a sinterable powder, the method comprising: a. selecting and conveying a charge of metal pieces along a continuous stream, said pieces having a transverse dimension no greater than 1/2 inch, b. injecting and directing a liquified cryogenic cooling medium, said medium being normally gaseous at ambient temperature conditions, against at least one section of said stream in sufficient amount to reduce the temperature of all the scrap pieces passing through said section to a temperature below the ductile-brittle transition temperature of the metal pieces, c. immediately conveying the super cooled metal pieces into a circulatory path and repetitively bringing a series of impacting elements against said super cooled pieces causing said pieces to fragment into particles and d. during said impaction of step (c) injecting a liquid cryogenic cooling medium into said path to insure said pieces and fragmented particles remain below said ductile-brittle transition temperature during any number of circulations in said path.

Claim 8

A method of making a metal powder suitable for use as a sinterable powder, the method comprising: a. selecting scrap metal pieces having a surface/volume ratio of at least 60:1 and a predetermined chemical range, b. conveying said pieces, in a cleaned or uncleaned condition, along a first stream while shrouding at least one station through which said first stream passes with a liquid cryogenic medium, c. conveying said cryogenically cooled pieces along a first circulatory path in a slurry formed with additional liquid cryogenic medium, d. repeatedly impacting said pieces in said slurry with a sufficient force and frequency to fragment and comminute said pieces into a supply of particles having a first predetermined size, e. separating said supply of particles from said slurry and thence conveying said supply of particles along a second stream while shrouding at least one station through which said second stream passes with a liquid cryogenic medium, f. conveying said second stream particles along the second circulatory path in the form of a slurry provided by additional introduction of liquid cryogenic medium, and g. repeatedly impacting said pieces in said second circulatory slurry with sufficient force and frequency to fragment and comminute said pieces into a powder supply having a second predetermined size no greater than 10% of said first predetermined size, said second predetermined size being achieved by at least 90% of the pieces exiting from said second circulatory slurry.

Claim 9

A method of making a metal powder suitable for use as a sinterable powder, the method comprising: a. selecting scrap metal pieces having a surface/volume ratio of at least 60:1 and a predetermined chemical range, b. conveying said pieces, in a cleaned or uncleaned condition, along a first stream while shrouding at least one station through which said first stream passes with a liquid cryogenic medium, c. conveying said cryogenically cooled pieces along a first circulatory path in a slurry formed with additional liquid cryogenic medium, d. repeatedly impacting said pieces in said slurry with a sufficient force and frequency to fragment and comminute said pieces into a supply of particles having a first predetermined size, e. separating said supply of particles from said slurry and thence conveying said supply of particles along a second stream while shrouding at least one station through which said second stream passes with a liquid cryogenic medium, f. conveying said second stream particles along the second circulatory path in the form of a slurry provided by additional introduction of liquid cryogenic medium, and g. repeatedly impacting said pieces in said second circulatory slurry with sufficient force and frequency to fragment and comminute said pieces into a powder supply having a second predetermined size no greater than 10% of said first predetermined size, said second predetermined size being achieved by at least 90% of the pieces exiting from said second circulatory slurry.

Claim 17

A method of making a metal powder suitable for use as a sinterable powder, the method comprising: a. selecting scrap metal pieces having a surface/volume ratio of at least 60:1 and a predetermined chemical range, b. conveying said pieces, in a cleaned or uncleaned condition, along a first stream while shrouding at least one station through which said first stream passes with a liquid cryogenic medium, c. conveying said cryogenically cooled pieces along a first circulatory path in a slurry formed with additional liquid cryogenic medium, d. repeatedly impacting said pieces in said slurry with a sufficient force and frequency to fragment and comminute said pieces into a supply of particles having a first predetermined size, e. separating said supply of particles from said slurry and thence conveying said supply of particles along a second stream while shrouding at least one station through which said second stream passes with a liquid cryogenic medium, f. conveying said second stream particles along the second circulatory path in the form of a slurry provided by additional introduction of a liquid cryogenic medium, g. repeatedly impacting said pieces in said second circulatory slurry with sufficient force and frequency to fragment and comminute said pieces into a powder supply having a second predetermined size no greater than 10% of said first predetermined size, said second predetermined size being achieved by at least 90% of the pieces exiting from said second circulatory slurry, h. annealing said second predetermined powder, and i. blending two or more of said annealled second predetermined powders, each having differing predetermined chemistry ranges in order to obtain a desired master powder chemistry.

Claim 18

A method of making a metal powder suitable for use as a sinterable powder, the method comprising: a. selecting scrap metal pieces having a surface/volume ratio of at least 60:1 and a predetermined chemical range, b. conveying said pieces, in a cleaned or uncleaned condition, along a first stream while shrouding at least one station through which said first stream passes with a liquid cryogenic medium, c. conveying said cryogenically cooled pieces along a first circulatory path in a slurry formed with additional liquid cryogenic medium, d. repeatedly impacting said pieces in said slurry with a sufficient force and frequency to fragment and comminute said pieces into a supply of particles having a first predetermined size, e. separating said supply of particles from said slurry and thence conveying said supply of particles along a second stream while shrouding at least one station through which said second stream passes with a liquid cryogenic medium, f. conveying said second stream particles along the second circulatory path in the form of a slurry provided by additional introduction of a liquid cryogenic medium, g. repeatedly impacting said pieces in said second circulatory slurry with sufficient force and frequency to fragment and comminute said pieces into a powder supply having a second predetermined size no greater than 10% of said first predetermined size, said second predetermined size being achieved by at least 90% of the pieces exiting from said second circulatory slurry, h. annealing said second predetermined powder, and i. blending two or more of said annealled second predetermined powders, each having differing predetermined chemistry ranges in order to obtain a desired master powder chemistry.

Claim 19

A method of producing powder metal, comprising: a. selecting a charge of metal scrap pieces each carrying machining oil resulting from cutting operations and conveying said scrap pieces along a stream, b. injecting a liquified cooling medium against a section of said stream so as to contact the pieces at a substantial number of points whereby substantially all of the scrap pieces will be reduced in temperature below their ductile-brittle transition temperature, c. immediately conveying the super cooled scrap pieces into a circulatory path within a chamber and wherein a series of impacting elements are repetitively brought against said scrap metal pieces and frozen oil to produce a composite homogeneous mixture of metal powder particles and fragmented frozen oil particles, during said impacting step a liquid cryogenic cooling medium is injected against said scrap pieces at a point of said circulatory path remote from said impacting elements to insure that the metal scrap and frozen oil retain their super cooled condition throughout repetitive impacting, and d. permitting said composite mixture to be elevated to ambient temperature conditions whereby each comminuted frozen oil particle forms a liquid coating along each of the several adjacent metal particles.

Claim 20

A method of producing powder metal, comprising: a. selecting a charge of metal scrap pieces each carrying machining oil resulting from cutting operations and conveying said scrap pieces along a stream, b. injecting a liquified cooling medium against a section of said stream so as to contact the pieces at a substantial number of points whereby substantially all of the scrap pieces will be reduced in temperature below their ductile-brittle transition temperature, c. immediately conveying the super cooled scrap pieces into a circulatory path within a chamber and wherein a series of impacting elements are repetitively brought against said scrap metal pieces and frozen oil to produce a composite homogeneous mixture of metal powder particles and fragmented frozen oil particles, during said impacting step a liquid cryogenic cooling medium is injected against said scrap pieces at a point of said circulatory path remote from said impacting elements to insure that the metal scrap and frozen oil retain their super cooled condition throughout repetitive impacting, and d. permitting said composite mixture to be elevated to ambient temperature conditions whereby each comminuted frozen oil particle forms a liquid coating along each of the several adjacent metal particles.