The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Power requirements in pigment comminution
Author:	Gildersleeve, Joseph Timothy
View Online:	njit-etd1956-011 (v, 47 pages ~ 2.2 MB pdf)
Department:	Department of Chemical Engineering
Degree:	Master of Science
Program:	Chemical Engineering
Document Type:	Thesis
Advisory Committee:	Keeffe, George C. (Committee chair) Mantell, C. L. (Committee member) Kreps, Saul I. (Committee member)
Date:	1956-06
Keywords:	Milling machinery
Availability:	Unrestricted
Abstract:	The results of this work prove that the relation between total work and surface area developed in the wet grinding of pigments is an exponential function. The following equations were experimentally determined for the pigments studied: For Zinc Oxide; P = .090 (Δs)1.05 For Titanium Dioxide: P = .086 (Δs)1.072 For Calcium Carbonate: P = .107 (Δs)0.98 This work shows that in the grinding of sub-sieve size pigments the Rittinger and Bond theories which state that surface area developed is directly proportional to total work, are not valid and cannot be applied. It is also shown in another plot that when a surface area developed versus total work plot is made with all the pigments starting from the same surface area, the ratio of their y-intercepts, where Δs = log 1 = 0, are related to the ratio of the mineralogical hardness of the pigments. In fact the straight lines of the pigments fall in the order of their hardness. Since Δs = 0 refers to the unground pigment, the only plot it can have any significance in is a plot where the grinds have the same starting point. A study was also made of each of the grinding variables and their effect on the development of surface area. Thus by the use of a simple method of measuring surface area and a measurement of power expended, these equations can be used to predict power requirements to obtain a specific grind.