Document ymxx0LV55B4L97Y29QB1zD4Y2

CONFIDENTIAL JAN 10 1950 D.B.K. JAN 9 -1950 A Newark, New JJeerrssSp 111950 January 6, 1950 J, H, COOPER (3) GRINDING STUDIES HF PROCESS A-IIC-261 AJS-50# EFK-30# This represents an Informal progress report on the HF Process for the month of December, * Samples aupgrlor in..strength to BT-3Q4-D have been I repeatedly made using pulverised NaCl as the grinding medium in a two hour cycle. One attempt to separate the NaCl by dilution and decantation followed by re-use of the acetone-salt mixture in a subsequent grind was moderately successful, except for a rather excessive amount of acetone required for the dilution. A grind of chlorine-free CPC was continued for 7-1/4 hours and, some place between 4 and 7 hours, there was a substantial, but not quite complete, phase ohange to the beta form. This is the \| strongest product approximating the hue of BT-297-D that we have 1* seen {+15% strong). A 3 hour grind of an Orohem crude green gave a product which was yellow and Intense versus GT-674-D,Lot 430, but still about 20^ weak. One trial of a draft tube in place of the disc type agitator gave quite poor strength development. | The semi-works unit (+13 gal. capacity) was put in opera- ftion during the month with two 4 Hour grinds of CPC-LB. One of these Mhas been evaluated and gave a very smooth strength development curve, 'though a little slower than the lab. grinds. The strength of BT-304was reached in about 3 hours. There was some trouble with the bear ings and belt on this unit and repairs are being made before further runs are started. # It is believed that the most important immediate problem in this study is to develop a practical method of separating the grinding medium from the pigment suspension. Efforts are being directed toward this end. AJSiRMK r N41991