Document 7RZkrnxnzZvGmLg9vJMg6Bxae

E. I. DU PONT DE NEMOURS & COMPANY # * KREBS PIGMENTS DEPARTMENT 1 256 VANDERPOOL STREET 4 ' NEWARK, NEW JERSEY / Serial No. Copy No. 81-44-32 / Period Covered: NEWARK PLANT PIGMENT COLOR RESEARCH REPORT Final Report X-?44-v ^iaat and Seal-Wastes J>*Yelopr.an$ May, 1943 - Beptotafcar, 1943. FILE: DATE: 212 26--44 NJ8>: N39983 <=2/ 2L Serial Ho. 0*44*32 Copy So* 1 Copy tot ll - Humerleal File </ 2 * Research Office (212) 3 - Library File (212) 4 * #10 Buildlsg Fllo 5-#6 * *4Y ^* Imp#erial Chemft ical Indusft tries, Ltti d* $~ * 9 - Hr* C. H. Ruppreeht, Wilmington (ICI File) BEWARE FLAM PIGMENT COLOR RESEARCH REPORT Final Report Title* 1*544*0, Plant and Semi-Works Development Period Covered* May, 1943 * September, 1943* SUBMITTED Bit J. R. Borst APPROVED lit DATS SUBMITTED* 5/5/44 DATE ISSUED* 5/26/44 N39983.01 DUP050150282 -2- lamxamm The sine yellow 7-544-9 was created in response to a demand for a low cost product in which the presence of an appreciable quantity of sulfate is not objectionable; the compo sition of the new yellow is similar to 7-232-9* This product like 1-539-0 is made from sine oxide mod the process differs mainly from the 1-539-9 formula in the acid used for neutralisation of the freshly struck slurry (sulfuric instead of hydrochloric) . this report covers seal-works and plant development of the 7-544-9 process* A limited amount of laboratory work which was performed concurrently with this study is reported in KB-43-160,- The 7-544-9 type of sine yellow is very similar in prepara tion to its prototype 7-539-9. Both of these protects are made by striking a slurry of sine oxide and potassium chloride with sodium bichromate liquor. The strike is immediately followed by acidification but 7-544-9 uses sulfuric acid whereas 7-539-9 is neutralised by hydrochloric acid* The effect of the sulfuric acid on the composition is shown by the table below, where the approxi mate compositions of 7-539-9 and 7-544-9 are shown with the theoretical sine yellow composition based on the formula K20.42n0.4Cr03`3H20. Theoretical It is probable that the sulfate is a definite part of the sine yellow crystal lattice* replacing an equivalent amount of chromate with which it is isoaorphous* The sulfate in 7-544-9 is extremely important since its presence is responsible for the higher yield per pound of chromate used mad lower cost than would otherwise be attainable. SUMMARY ABB COBCLUSIOttS At about the same time as the work on 7-544-9 was being started a Bird centrifuge was installed in the plant for the dewatering of sine yellows* Considerable effort was expended to determine factors which influenced the centrifuging capacity (pounds of pigment per hour)* The settling rate of the sine yellow was assumed to be a measure of the centrifuging rate. Consequently, DUP050150283 -3' references made here to the settling characteristics should be construed to indicate.the ability of the color to centrifuge. the first batch of Y-544-D was made is the semi-works on a formula later designated as -1921, This was based on a combination of laboratory recommendations and previous experi ence with Y-539-D. This batch settled poorly and the yield was lower than anticipated. It contained approximately 1.3 per coat S0^ Plant production ms started on this formula mad nearly sixty batches were struck on it under development super vision. & great proportion of this work was In collaboration with the Industrial Engineering Division in order to make material which would centrifuge at a high rate. Of the several variables studied* only the elimination of the eaustie soda Improved the rate of settling. Caustic was added as a dispersing agent for the sine oxide (as in Y-539-D) and was varied from 0 to 1/2 per cent (besed on the estimated yield). The settling remits wire not sharply defined but it was evident that the batches made without caustic settled most rapidly. The rate of strike* volume of water for dispersing the sine oxide and time of stirring after acidification failed to improve the settling rate. As a result of the work on settling, a new formula* -1926* was set up for centrifuging* This formula omitted the caustic for dispersing the sine oxide. Seven plant batches were made on this formula under development supervision* The average capacity of these In the centrifuge was 1330 pounds per hour on the first pass mad 950 pounds per hour on the second pass (after reslurrying). While these rates of through-put were not as great as desired* they were* nevertheless, e consider able improvement over earlier batches. Subsequent to the work on settling, the laboratory recommended the use of a greater amount of sulfuric add for increased yield. Semi-works end plant trials were nut with higher acid to verify this lead and these batches actually showed a alight improvement in yield. This material contained about 2.5 per cent SO3 whereas batches made on previous formulas analysed 1.5 per cent 6O3 or less. She change in add combined with some simplifications in making procedure resulted in the formulation of the present standard, -1934* The Y-544-D process was turned over to the plant after -1934 w&a set up and has performed satisfactorily since. Two batches made on the present standard were vet washed to 0.11 and 0.19 per cent Cl. Previous attempts to vat wash Y-544-D were unsuccessful because of its failure to settle. DUP050150284 mmmkMum The procedure employed for predicting the ability of the zinc yellow to centrifuge from ita settling rate may be of interest because of its potential usefulness on other colors* It should be emphasised that no empirical relationship has been found which would permit forecasting of rates through the centrifuge h&owing the settling characteristics, the relationship is merely qualitative but has been useful in a general manner* The samples of sine yellow slurry from the strike eat were always made to the same concentration in a graduate* Them the graduate was inverted several times (while covered by the hand to prevent spilling) in order to uniformity suspend the slurry. Readings of the volume of clear backwater were taken at five minute intervals until constant remits were obtained. Then a graph was plotted correlating time of settling versus decantable volume. The greater the slope of this curve the greater the settling rate and the higher should be the centrifuging rate. See USS-43-.61. DUP050150285