Method of determining the amount of residue in carbon black

Abstract

Test methods are provided for determining the amount of contaminants in a carbon black sample. The test procedures include screening a known amount of carbon black to separate larger particles in the sample from smaller particles. The sample and/or separated larger particles are treated with a separating force to disperse larger agglomerates of carbon black into smaller aggregates of carbon black and to separate contaminants from carbon black aggregates. The treated sample or separated larger particles can then be screened to again separate larger particles from smaller particles. The separating force may be a water wash stream which contacts the sample or separated larger particles at a pressure of from about 15 psi to about 35 psi. The separating force may instead or additionally be generated by a dispersing agent which can be combined with the sample or separated larger particles in an amount or concentration sufficient to disperse larger agglomerates of carbon black into smaller carbon black aggregates. The measured weight of the separated contaminants and the measured weight of the carbon black sample can be used to determine the weight percent of certain contaminants in the carbon black sample.