Document YGRLJNG5rb6VOwwwnozm8RBxV

E. i. DU PONT DE NEMOURS & COMPANY 256 VANDERPOOI. STREET NEWARK, NEW JERSEY Serial No. KN-67-12 Copy No. ^ NEWARK PLANT PIGMENT COLOR RESEARCH REPORT PRELIMINARY EVALUATION OP THE FUNDA FILTER Period Covered November 1966 to February 1967 FILE: DATE: 114 6/7/67 NJ 9346 N33703 KN-67-12 Copy No. i .1. Numerical Pile 2 Research Office File (ll4) 3. Library File (ll4) 4. M. Hunt/ E. Gonick, Pigments-Wilm. i: W, S. Struve/A. .A .Brizzolara H.R.Linton/F .F.Ehrich/B.H.Perkins/Library * l: P.J.Monahan (Vital Records) R.H.Wetzel/J,W.Minnich, Newport 9. N. G.Fisher, Central Res. Dept., Wilm. .10 G.P.Lewis - Newark .11 W.J.McClure/R.A.Hageman, Newark .12 E..Andrews/J .F.Little, Newark 13* J.E.Flood/ F.W.Rennie-Louviers, Wilm. 14. 15 * Eu xtra it it ii NEWARK PLANT PIGMENT COLOR RESEARCH REPORT SUBJECT: PRELIMINARY EVALUATION OF THE FUNDA FILTER PERIOD COVERED: November 1966 to February 1967 SUBMITTED BY: Date Submitted: 6/1/67 APPROVED BY: Date Released: 6/7/67 ABSTRACT Evaluation of a small Funda filter has shown filtration rates 15 to 20 times those obtained in a plate and frame filter press A test using a 20 ft2 filter is recommended. i DUP050027441 TABLE OF CONTENTS PAGE INTRODUCTION .1 SUMMARY AND CONCLUSION PATENT STATUS.... ....{..ft** DESCRIPTION OF FILTER.____.........------- .* 1 .* .1 ........ 2 e x p e r ime n t a l d e t a il s ............................. TEST RESULTS QU2NACRIDONE PIGMENTS.............. PHTHALOCYANINE BLUE PIGMENTS. ....... ....... . .... 3 4 4 5 MOLYBDATE ORANGE PIGMENTS.... d is c u s s io n o f r e s u l t s .................................. 5 ,# > 5 FILTRATION AND WASHING....... DRYING.............................................,. 5 6 SCALEUP AND COST DATA: COMPARISON WITH PRESENT FILTERS. 7 QUINACRIDONE........................................ .. CPC BLUE. MOLYBDATE ORANGE. 7 8 8 DUP050027442 INTRODUCTION Filtration of pigment from synthesis and extraction slurries at the Newark plant is usually carried out with plate and frame filter presses. The only exceptions are the inorganic lead and zinc based colors which are isolated by continuous centrifuge. Batch pressing is followed by tray drying, and the combined operation requires a considerable amount of manual labor. As a possible labor savings device, the methods and standards depart ment suggested that research evaluate a new automatic discharg ing filter. Preliminary evaluation at the vendor* s facility resulted in inconclusive data, A small scale pilot plant filter was rented from the vendor and evaluated in the Newark Semi-Works, SUMMARY AND CONCLUSIONS The Furida filter has been tested on quinacridone, CPC blue and imolybdate orange vat control slurries, The filtration and washing rates were up to 20 times that presently obtained in our plate and frame filter presses. The drying cycles for the cake to obtain discharge from the filter was not conclusively established during the test. Drying cycles In the test were longer than necessary due to limiting dimensions of the pilot plant unit tested, which had a filtration area of ,5 feet2. The data indicates a significant improvement in through put (lb/hr/ft2), and a potential cost savings. It is recommended that further testing on a 20 ft2 filter equipped with a Rootes Blower be carried out to establish the operating cycles for several pigments. PATENT STATUS No patentable items will result from this work. -1 DUP050027443 DESCRIPTION OF FILTER The filter tested is called a Funda filter and it is manufactured 'by Chemap A, 0. of Switzerland. Sales in the United States are carried out hy the De Laval Separator Company, and an affiliate of Chemap} Chemapec Inc. located in Hoboken, N. J. The work reported on in this memorandum was carried out using Chemapae equipment. The Funda filter is a horizontal multi-leaf pressure filter. It is similar to a Nutsche filter with the exception that several leaves can be accommodated within the filter vessel. Automatic discharge of the cake is another feature of the filter. These innovations lead to a compact unit with a rela tively high filter area per unit volume. Figure 1 is a schematic of the filter. The vessel is cylindrical with a conical bottom. Several disc shaped filter leaves are mounted on a hollow central shaft and any type of filter cloth can be used with these leaves. The shaft is con nected to a motor mounted on top of the vessel. Figure 2 shows the detail of the filter nest. The slurry passes over the top of the cloth, and filtration takes place when the appropriate pressure differential is applied. The filtrate passes through the cloth and down the filter disc toward the central shaft. Openings on the shaft at specified locations permit the filtrate to pass down the hollow center of the shaft. The cake is col lected on the top surface of the cloth and a cake thickness essentially equal to the distance between two adjacent filter discs can be obtained. Auxiliary equipment includes a slurry and wash water pump, and a source of pressurized (10-15 psig) heated air. In operation, the slurry is pumped to the vessel as shown in Figure 2. It is desirable to operate the filter with a recycle stream, as shown by the slurry overflow line at the top of the vessel. This overflow returns to the synthesis or extraction vat. A valve in this line may be used to control the filtration pressure by varying the overflow rate. The filtrate runs down the shaft and out the bottom of the vessel as shown. The fil tration is carried out for a predetermined time until the desired cake thickness is reached. This thickness is typically one inch. Following this a heel filtration is carried out to filter the slurring remaining in the filter vessel. Washing is now carried out using the same pump as for the feed slurry. Overflow washing as before is preferred for the operation. At a given conductivity, the washing is termin ated, and the remaining wash water can be heel filtered or drained. -2- DUP050027444 Slurry Overflow Slurpy,or Wash .-Water Pig, 1 FUNDA FILTER DUP050027445 Description of Filter (Cont1 d) A unique feature of the Funda filter is automatic cake discharge obtained by rotating the center shaft and filter leaves. In order for the pigment to leave the filter doth and discharge through the bottom of the filter, the pigment generally must be partly dewatered. This is accomplished by the use of hot pres surized air to displace the water from the cake and to dry it. The air pressure would be 10-15 psig with an inlet temperature of up to 300 F - 350F. Drying is carried out only up to the point where the pigment can discharge easily. This will be in the range of 35$ - 50$ solids depending on the material. The drying time which is determined experimentally, can be as long as the filter ing or washing times, but again depends on the pigment filtered. Following the drying, the motor on the filter vessel is activated, and the entire filter nest rotates, discharging pig ment by centrifugal force. After pigment discharge, the vessel is ready for another filtration cycle. Changeover between codes is normally made by replacing the filter nest assembly and scrubbing the equipment. This changeover should be accomplished in 4 - 6 hours. The entire process can be automatically controlled requiring a minimum of manual labor. EXPERIMENTAL DETAILS The pilot plant filter rented from Chemapec had a .5 ft2 filter area, a total volume of about 13 liters and was constructed of stainless steel. The unit is identical to production models with two exceptions. The heel filtration lines were not present and air Jets to help discharge cake was not available. Each filter disc was .1 ft2 in area and 5 discs were placed in the unit at a spacing of 1-1/4". Feutron cloths were sewn together to completely surround the disc and a single cloth was used for the majority of the runs. The pigment slurry was fed from a 30 gallon steel tank by a gear pump capable of delivering a 75 psig head. Washing was accomplished using city water directly off the line at 40 psig, which was throttled to vary the pressure in the filter. Plant compressed air was used for heating and drying of the filter cake. Steam tracing around the air line provided inlet air temperatures up to 170P maximum. Preliminary runs to establish rates and pigment loading on the filter disc were made using a pressure Nutsche filter with a single filter disc of 0.1 ft2 in area. The volume of the pres sure filter was 95 ml. Nitrogen gas from cylinders was used to pressurize the vessel. -3- DUP050027446 TEST RESULTS Q.UINACRIDONE PIGMENTS The samples tested in the quinacridone group were RT-796-D, RT-839-D and RT-849-D. The first two materials are the extraction vat slurries obtained by charging mill powder into a sulfuric acid solution. The main soluble salt is the aluminum sulfate* The weight percent pigment is 4 -- 6$ in these slurries. The RT-849-D has a 10% calcium staybelite extension of the pig ment, The soluble salts contain mainly sodium chloride, with the solution being alkaline. Pigment content is about 6% by weight. Initial testing with the pressure nutsche using RT-839-D gave a total filtration time of one hour for a quart of slurry. The filtration rate was 2,5 gal/hr/fta with a final pressure of 60 psig. Washing was carried out at pressures of 40-50-psig. The filtration rate was 2.5 gal/hr/ft2 for the first quart of wash water and this rate increased to 4,3 gal/hr/ft2 for the second wash. The cake thickness was 5/16 to 3/8 inch for a quart of feed slurry. Based on a desired cake thickness of one inch in the ,5 ft2 pilot plant filter, about four gallons of the quinacridone slurry (.3 - .4 lb/gal) had to be filtered. Testing in the pilot plant unit was carried out a3 follows: Fifteen gallons of the slurry were added to the feed tank and agitated. The slurry was then pumped into the filter unit. Approximately four gallons were required to fill the unit. After the unit was filled as indicated by the overflow at the top of the filter, the overflow valve was closed to obtain pressure within the filter. At this point filtration commenced. The pressure within the filter was regulated by the overflow valve. Most runs were carried out with an overflow. That is, the feed rate exceeded the filtration rate. In some cases the pump did not deliver the rated flow and the runs were carried out with a closed overflow valve. Maximum pres sure developed was 30 - 35 psig because of leakage in the pump packing. When the required amount of filtrate was collected, the pump was shut off and the contents of the filter drained to the feed tank. This was done carefully to avoid disturbing the cake. Washing was carried out by applying hot water at city line pressure directly to the filter and controlling by the Inlet and the overflow valve. Conductivity readings were taken to Indicate degree of washing. When the desired conductivity was reached, the wash water was turned off and the filter drained as before. Hot air (170F) at essentially zero pressure was used to blow the water out of the cake. -4- DUP050027447 Quinaerldone Pigments (Cant'd) This required about 3 - 5 minutes* Following this, 12 SCFM of air at 170 F was passed through the cake for varying times. The jacket of the filter was chased with steam to maintain temperature. After the drying was complete the air was shut off and the filter nest rotated for up to one minute. The cake was collected at the bottom of the filter and a solids analysis was carried out. Several runs were made to familiarize the personnel with the unit. The data sheets indicate the pertinent information obtained from typical runs on quinacridone slurries. Phtalocyanine Blue Pigments The same procedure was followed for BT-417-D slurry. Pressure Nutsche tests showed that one liter of slurry filtered with a cake thickness of 1/4" on the ,1 ft2 unit. The average rate was 2 to 2.5 gal/hr/fta at a 60 psig maximum pressure. Two typical runs are given for the pilot plant .5 ft2 Funda. Molybdate Orange Pigments This pigment filtered very rapidly using, fee pressure Nutsche. Average filtration rates of 14 gal/hr/fts were obtained for a total of 1.4 gallons of slurry. The cake thickness was one inch at a maximum of 60 pound pressure. Four runs were made as shown on the data sheets. DISCUSSION OF RESULTS Filtration and Washing Operation of the unit generally was satisfactory regard ing filtration and drying. In some of the runs, the final vat control slurry to be filtered had a 50$ higher s ollds content than expected. This was caused by sampling at the bottom of the vat after settling had taken place. The higher solids level meant that for the calculated quantity of slurry to be filtered, too much pigment was collected. For these runs the plates were filled and filtering occurred at the outer periphery with cake extending to the wall. This resulted in lower average filtration rates, as in run 1. Solids were then taken before each run and the unit performed satisfactorily. The data indicated average filtration rates of 8 -- 10 gal/hr/ft2 for the dispersion milled vat control .QA slurries. This is the average for the one inch of cake to form. Rates of up to 16 gal/hr/ft2 were observed at cake thicknesses up to one half inch. The washing rates were not reproducible for all the r-5- DUP050027448 RUN: 1 Filtration Pigment Slurry: Solids Content: Gal. Filtered: Time: Avg, Filtration Rate: Maximum Pressure: Washing Gallons Wash Water: Time: Average Wash Rate: Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate: Drying Drying Dime: Air Temp: Air Flowrate: # Solids of Cake: Cotton Cloth RT-796-D 3.5 2 hr.20 min. 3 gal/hr/ft2 14 psig 10 1 hour 15 minutes l6 gal/hr/ft2 14 psig 2000 2 hours 170F 12 SCFM 52# -5a- DUP050027449 RUN: 2 Filtration Pigment Slurry: Solids Content: Cel, Filtered: Time: Avg. Filtration Rate: Maximum Pressure: Washing Gallons Wash Water: Time: Avg. Filtration Rate: Maximum Pressure; Initial Ohms Wash Water: Final Ohms of Filtrate: Cotton Cloth RT-839-P Approx. 5* 4 1 hour 8 gal/hr/ft2 6o psig 20 1 hour 30 minutes 27 gal/hr/ft2 25 3500 3000 Drying Time: Air Temp: Air Flowrate; * Solids of Cake: 1 hour 30 minutes 170F 125 CFM 43* -5b- DUP050027450 RUN: 3 Filtration Pigment Slurry: Solids Content: Gal, Filtered: Time: Avg. Filtration Rate: Maximum Pressure: Washing Gallons Wash Water; Time: Avg, Filtration Rate; Maximum Pressure: initial Ohms Wash Water: Final Ohms of Filtrate; Feutron Cloth RT-796-D 4# 5.1 1 hour 25 minutes 7.7 gal/hr/ft2 25 P3ig 50 50 minutes 84 gal/hr/ft2 27 psig 2900 2900 Urging Drying Time: Air Temp: Air Flowrate: # Solids of Cake: 1 hour 160 F 12 SCFM 35*1* -5c- DUP050027451 BUN; 4 Filtration Pigment Slurry: Solicit Content: Gal. Filtered: Time; Avg. Filtration Bate Maximum Pressure: Washing Gallons Wash Water: Time: Avg. Filtration Bate: Maximum Pressure: Initial Ohms Wash Water; F.inal Ohms of Filtrate: Feutron Cloth BT-849-D 6$ 5 1 hour 10 gal/hr/ft2 16 pslg 25 1 hour 20 minutes 38 gal/hr/ft2 34 psig 4000 ohms 3600 Drying Drying Time: Air Temp; Air Flowrate: # Solids of Cake* 40 170 F 12 SCFM * 23.8# *Did not spin off. ~5d- DUP050027452 RtJN: 5 Filtration Pigment Slurry: Solids Content: Gal. Filtered: Time: Avg. Filtration Rate: Maximum Pressure: Feutron Cloth RT-849-D 4# 2-1/2 24 minutes 13.4 gal/hr/ft2 16 psig Washing Gallons Wash Water: Time: Avg. Filtration Rate: Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate: 25 1 hour 25 gal/hr/ft2 30 psig 3300 ohms 3100 ohms Drying Drying Time: Air Temp: Air Flowrate: % Solids of Cake: 40 minutes l6oF 12 SCFM * 26.4# *Did not all spin off. -5e- DUP050027453 Him: 6 Filtration Pigment Slurry: Solids Content: Gal, Filtered: Time: Avg, Filtration rate: Maximum Pressure: Feutron Cloth RT-796-D k$> 3 30 minutes 12 gal/hr/ft2 32 pslg Washing Gallons Wash Water: Time; Avg, Filtration Hate: Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate; 15 gallons 1 hour 15 minutes 24 gal/ hr/ft2 20 psig 5000 5000 Drying Time; Air Temp: Air Flowrate: i> Solids of Cake: 1 hour 30 minutes 170 *F 12 SCFM 34.5# ~5f- DUP050027454 BUN: 7 Filtration Pigment Slurry: Solids Content: Gal, Filtered: Time: Avg. Filtration Bate: Maximum Pressure: Washing Gallons Wash Water; Time: Avg. Filtration Rate: Maximum Pressure; Initial Ohms Wash Water: Final Ohms of Filtrate; Feutron Cloth RT-796-D 4j 4 gallons 35 raintites 13.8 galAn/ft2 28 psig 16 1 hour 32 gal/hr/ft^ 24 psig 4200 4000 Drying. Drying Time; Air Temp; Air Flowrate; % Solids of Cake: 1 hour 30 minutes 170 F 12 SCFM 34.1$ -5:8- DUP050027455 RUN: 8 Filtration Pigment Slurry: Solids Content: Gal. Filtered: Time; Avg. Filtration Rate: Maximum Pressure: Washing Gallons Wash Water: Time: Avg. Filtration Rate; Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate: Feutron Cloth BT-417-D 4 3 hours 2.7 gal/hr/ft2 22 pslg 50 7 hours 40 minutes 13 gal/hr/ft2 28 psig 3800 3000 Drying Time: Air Temp: Air Flowrate: <$> Solids of Cake: 2.5 hr 170F 12 SCFM 40.3^ -5h- DUP050027456 RUN: 9 Filtration Pigment Slurry: Solids Content: Gal, Filtered: Time: Avg. Filtration Rate; Maximum pressure: Feutron Cloth BT-417-D 4$ 5 1 hour 45 minutes 5,8 gal/hr/ft2 20 psig washing Gallons Wash Water: Time: Avg. Filtration Rate: Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate: 60 3.5 hours 34 gal/hr/ft2 35 psig 3400 Drying Drying Time: Air Temp: Air Flowrate: $ Solids of Cake: *Did not spin off. 2 hours 170F 12 SCFM *26.4$ -5i DUP050027457 RUN: 10 Filtration Pigment Slurry: Solids Content: Gal, Filtered: Time: Avg. Filtration Rate: Maximum Pressure: Washing Gallons Wash Water: Time: Avg, Filtration Rate: Maximum Pressure; Initial Ohms Wash Water: Final Ohms of Filtrate: Cotton Duck Cloth YE-698-D W 10 30 minutes 40 gal/hr 20 psig 16 25 minutes 75 gal/hr/ft^ 20 psig 4000 3200 Drying Time: Air Temp: Air Flowrate: $> Solids of Cake: 6 170F 12 SCFM 99$ -53- DUP050027458 RUN: 11 Filtration Cotton Duck Cloth Pigment Slurry: Solids Content: Gal. Filtered: Time: Avg. Filtration Rate: Maximum Pressure: YE-698-D 5# 7 20 minutes 44 gal/hr/ft2 20 psig Washing Gallons Wash Water: Time;: Avg. Filtration Rate; Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate: 50 1 hour 100 gal/hr/ft2 25 psig 2700 2500 Drying Drying Time: Air Temp: Air Flowrate: $ Solids of Cake: 3-1/2 hours 170 F 12 SCFM 84$ -5k- DUP050027459 RUN: 12 Filtration Pigment Slurry: SolicLs Content: Gal. Filtered; Time: Avg, Filtration Rate: Maximum Pressure: Washing Gallons Wash Water: Time: Avg, Filtration Rate: Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate: Drying Drying Time: Air TempP Air Flowrate: # Solids of Cake: Cotton Duck Cloth YE-698-D 5# 7 20 minuteS 42 gal/hr/ft2 20 psig 30 45 minutes 80 gal/hr/ft2 20 psig 3000 3000 1 hour 30 minutes 170 F 12 SCFM 68# -5L- DUP050027460 RUN? 13 Filtration Pigment Slurry: Solicls Content: Gal. Filtered: Time: Avg. Filtration Rate; Maximum Pressure; Washing GA Gallons Wash Water; Time; Avg, Filtration Rate: Maximum Pressure: Initial Ohms Wash Water: Final Ohms of Filtrate: Cotton Duck Cloth YE-698-D 5$ 7 20 minutes 44 gal/hr/ft2 20 psig ) DID ) ) NOT ) ^ WASH ) Drying Time; Air Temp: Air Flowrate: % Solids of Cake: Some Sticking to Wall. 1 hour ljO F 12 SCPM * 6o -5m- DUPO 50027461 Filtration and Washing (Cont'd) runs, tut generally were between 20 and 30 gal/hr/ft2. About 3-4 gallons of wash water per gallon of filtrate were required, to reach the acceptable ohms level. In most cases the washed cake was reslurried in water to check on the uniformity of washes. No changes in conductivity were observed, indicating a uniform wash vrith no channeling or leakage. _ The CPC blue BT-417-D filtered at rates frqm 3 to 5 gal/ hr/ft- and washed at rates exceeding 20 gal/hr/ft. Approximate ly 8 - 10 gallons of wash water were required per gallon of slurry filtered. The inorganic molybdate orange YE-698-D filtered exceed ingly well at rates up to 45 gai/Tir/ft2, and washed at rates up to 80 gal/hr/ft2. This is of course due to the density of the pigment, The data indicates that the loading of the blue and red pigments is 3 - 4 lb dry pigment per ft2 of filtering area at a one inch cake thickness. For the molybdate orange pigments the loading is about 6 lb. dry pigment per ft2 at a one inch cake thickness. Baring. The drying portion of the test did not yield valid data for several reasons. The low air temperature (170F) attainable resulted in long drying cycles. In addition there was only about a half inch clearance between the plate and the wall in the pilot plant unit. The bottom of the vessel, where the pigment dis charges also had a small clearance due to the piping necessary to take the filtrate out. This meant that when the cake was spun off the plate, chunks of pigment were caught between the plate and the wall, and in the bottom of the filter. Since the pig ment did not discharge properly, we had to dry longer than neces sary in order to get discharge of the pigment, Therefore drying cycles can only be estimated. It was determined that the quinacridone pigments will discharge at about 35# solids, the CPC blue discharged only after the 40# solids level was reached, and the molybdate orange did not discharge below 60# solids. -6- DUP050027462 SCALEUP AND COST DATA COMPARISON WITH PRESENT FILTERS Using the data obtained with maximum pump pressures of 30-35 psig we can extrapolate to somewhat higher rates if the pump could reach 70-90 psig, as is common in our present fil tering operation. We can also extrapolate the drying data for assumed air temperatures of 275P - 290 F to arrive at overall cycle times, Quinaoridone Pigments Extrapolation of the data as indicated above results in a filtration rate of 10 gal/hr/ft2, a wash rate of 25 gal/hr/ft2 and a drying time of one hour at a rate of 8 SCFM/ft2 of air at 275E. Our present filter press operation on RT-79& takes 12 hours to fill the press, 32 hours to wash and two hours to drop the press for a total of 46 hours. The press has an area of 1550 ft2 and a batch has about 8000 gallons. The filtration rate is 8000/l550 x 12 .43 gal/ hr/ft2, while the Punda rate is 20-25 times this rate. At a one Inch cake loading a sq. ft. of filter area requires 10 gallons of filtrate giving a pigment loading of 3-3.5 Ib/ft . This is achieved in one hour. About 35 gallons are required to wash this amount of pigment and this requires 1.4 hours, while the drying time to discharge is one hour. The throughput of the Punda is therefore 3 - 3.5 lb/ft2/3.4 hr * .88 - 1.04 lb/hr/ft2. The com parable number for the plate and frame is 2600/1550 x 46 = .036 lb/hr/ft2. An improved press, the ALP Shriver, has been installed at Newport for QA crude. Its service is not the same as our filter presses, but its capacity is only,.057 lb/hr/ft2. The number and size of the filters required for a given hourly throughput of pigment can be calculated as follows: Assume a desired 500 lb/hr throughput. Using an average loading of 3.25 lb/hr/ft2 the filter area required is 154 ft2. The nearest production unit is a 15 m2 or 162 ft2. Our cycle time is 3.4 hours and therefore four filters would be selected to produce a rate of 500 lb/hr. The cost for each filter would be about $20,000. With automatic controls, Rootes blower, etc., the unit should cost $40,000. Installation might double this price leading to $80,000 per filter. This compares to an un installed capital costs of $69,000 for the aforementioned ALP Shriver press. On a square foot basis the Punda costs $240/ft2 uninstalled, the ALP Shriver cost $70/ft2 and a plate and frame of iron construction of 1500 ft2 cost about $20/ft . The Punda throughput per ft^ is 15-20 times the ALP and 25-30 times a plate and frame press. -7- DUP050027463 CPC Blue Pigments As above, the extrapolated filtration rate for a BT-417 type slurry Is about 7 gal/hr/ft2. The wash rate is 25/ gal/lir/ft2 and a drying time is 1.5 hours. The pigment loading is also 3-3.5 lb/'ft2 requiring 10 gallons filtered in 1.4 hours. About 100 gallons of wash water were required, to reach the pro per conductivity level. This requires four hours and 1-1/2 hours are necessary to dry. The cycle is 6.9 hours and the throughput Is 3.25/6.9 .47 lb/hr/ft2, The rate through our plate and frame presses is ,038 lb/hr/ft2. Calculating the filter size requirements as before, assume a desired production rate of 306 lb/hr. The pigment load ing is 3.25 lb/ft2 as before, which results from the filtration of 10 gallons of slurry. At the conservative rate of 7 gal/hr/ft2 for filtration, the above loading requires 1.42 hours and fil tration throughput is 3.25/1.42 2,3 lb/hr/ft2. The filter area required is therefore 300 lb/hr/2.. 3 lb/hr/ft2. This is a 12 m2 production size unit. The cycle is 6.9 hours as before, requir ing seven filters for this job. Each filter equipped with blower and controls would cost about $32,000. The number of filters is quite large due to the neces sity to wash with 10 volumes of water per volume of slurry fil tered; as compared to 3 volumes for quinacrldones. The plant data Indicates that the washing times are the same for QA and CPC and this paradox should be explored by further testing. Molybdate Orange Pigments While the throughput for the molybdate orange slurries were very rapid, it is necessary to dry to 60$ solids before adequate discharge is obtained. This means that the largest por tion of the cycle is spent in drying and the unit does not appear attractive. This is particularly true when centrifuges do an adequate job in a continuous production facility for inorganic pigments. -8- DUP050027464