Coalesced Copper-Its History, Production and Characteristics

IN the early fall of 1025, the writer was conducting, in the Ledoux and Co. labora-tory, New York, experiments directed to-ward ascertaining the effect on its impurity content when cathode copper was subjected to a current of various gases at an elevated temperature below the melting point. The apparatus consisted of a vertical I-in. dia. silica tube about 12 in. long, heated on the outside. The cathodes were broken to pass 3/8-in. mesh, and a current of various differ-ent gases was passed up through a 4-in. long column of these loose cathode particles in the vertical tube furnace. Temperature was maintained to 1500° to 1600°F. and the gas treatments lasted from 3 to 6 hr. The writer observed that whenever reducing gas (H2 or CO) was used, these cathode par-ticles stuck together at points of contact with each other. The cohesion was so marked and tenacious that an examination was made of the fractured surfaces, when cathode particles were broken from the cluster. Crystal growth was always found to have taken place across the surfaces where separate particles were in contact, but only after all oxides, sulphates, etc., had been completely removed. The idea of a possible new process was then conceived and was disclosed to A. M. Smoot (V. P. Ledoux and Co.) with intent to obtain his views. The first conception as given Smoot was "to gas-clean broken cathodes, put them in an extrusion press, solidify and extrude them at around 1500°F." Smoot's reaction, after a few moments considera-tion, was, "It looks perfectly all right to me." The writer and his assistants, W. H. Osborn and H. H. Stout, Jr., after confer-ring as to ways and means, decided to go ahead with preliminary laboratory experi-ments, which, it was thought, would move the new process from the possible to the probable. This program followed a course indicated by three basic considerations: I. Since brittle cathodes were often unin-tentionally produced, it seemed probable that the laws controlling this type of deposi-tion could be ascertained. 2. We had already proved the gas-clean-ing feature. 3. There remained to prove: whether a sound, homogeneous metal billet could be produced with crystal growth established over the entire surface of each individual particle in the billet; and, if so, what would be the physical properties? Osborn arranged with Columbia Uni-versity for conducting experiments in its research laboratory to prove or disprove the third item; Columbia assigned C. A. Phillipi, Jr. to assist in the project. A press with a cylinder 2 in. high and of I-in. dia. was used. It was surrounded and heated by a resistance coil of Nichrome wire. Broken tough cathodes were used.