| 摘要 |
Furnace carbon black including lamp-black is heated to a black-heat temperature not lower than 650 DEG F. but below the ignition temperature, say 1100 DEG F. and air or air and steam is passed in contact therewith until 5-75 per cent by weight of the carbon has been burned away, and the product is heated in a non-oxidizing atmosphere to 1800-2000 DEG F. for say 5-30 minutes and cooled out of contact with free oxygen. The product has a pH 8-10, an ABC colour number 95-175, an oil absorption value 11-30 gallons per 100 lbs., an iodine absorption value of 250-350X10-5 equivalents per gram, and a blue tone. The first heating step is carried out as described in Specification 673,400. The second heating may be carried out in a closed refractory, e.g. silica, tube at sub-atmospheric pressure, and the product may be cooled in an inert gas or in vacuum. Specification 667,329 also is referred to. |
