ASTM_C_866_-_11_2016.pdf

Designation:C86611(Reapproved 2016)Standard Test Method forFiltration Rate of Ceramic Whiteware Clays1This standard is issued under the fixed designation C866;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers the determination of the rate atwhich a layer of clay-water paste is formed from a clay-waterslip under pressure filtration.The filtration rate is directlyrelated to such whiteware operations as filter pressing,slipcasting,and drying of ware in which water permeabilitythrough a clay-water paste is the controlling mechanism.1.2 A straight-line relationship exists between the time offilter pressing and the square of the thickness of the paste layer.The filtration rate is directly related to the filter press pressureand the void fraction of the paste layer,and is inversely relatedto the square of the clay surface area,the ratio of solids toliquid in the slip,and the viscosity of water at the testingtemperature.1.3 The values stated in acceptable metric units are to beregarded as the standard.The values given in parentheses arefor information only.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C324 Test Method for Free Moisture in Ceramic WhitewareClays3.Apparatus3.1 Balance,0.001-g sensitivity.3.2 Blender.3.3 Filter Press,capable of operation at 345 kPa(50 psi).3.4 Stop Watch.3.5 Vernier Calipers,capable of measuring thickness to thenearest 0.1 mm.4.Procedure4.1 Weigh 100 g of clay,dried in accordance with TestMethod C324,to the nearest 0.1 g and mix with 300 mL ofwater measured to the nearest 1.0 mL for 10 min in a blender.4.2 Store the slip in a closed container for at least 24 h toallow the clay and water to reach equilibrium conditions.4.3 Remix the clay-water slurry for 5 min in the blender.4.4 Pour the clay-water slurry into the filter press and apply345 kPa(50 psi)air pressure for 30 min.4.5 Relieve the pressure from the filter press and then pourthe clay-water slurry from the top of the filter cake that hasformed.A sharp movement of the wrist is required to removeall of the remaining slip from the filter press.4.6 Record the temperature of the filtrate.4.7 Reapply air pressure to the filter press for 10 min toforce some of the water from the cake that has formed.NOTE1Some clays have a fast filtration rate and the air may passthrough the cake in less than 10 min.In this case,the air pressure shouldbe relieved as soon as the sound of air emitting from the press is detected.4.8 Remove the filter cake from the press and measure thethickness to the nearest 0.1 mm with the vernier calipers.4.9 Place the cake in a drying oven at 100 to 110C for aperiod of 24 h.Weigh the dried filter cake to the nearest 0.01g.5.Calculations5.1 Calculate the filtration rate as follows:FR5 L2/T(1)where:FR=filtration rate,cm2/s,L=thickness of the wet filter cake,cm,andT=filtration time,s.NOTE2The filtration time is based upon the 30-min period duringwhich the clay-water slip is being filter pressed and does not include theadditional 10-min period for removal of water from the cake after it hasbeen formed.1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Products and is the direct responsibility of SubcommitteeC21.04 on Raw Materials.Current edition approved July 1,2016.Published July 2016.Originally approvedin 1977.Last previous edition approved in 2011 as C866 11.DOI:10.1520/C0866-11R16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2 The void fraction in the filter cake varies considerablydepending upon ions in the water that modify the packingstructure of the clay particles in the filter cake.Water that isnormally used for mixing with the clays should be used for thetest so that interactions between ions in the water with the clayare considered.However,in some cases distilled water may beused for mixing with the clay so that only those ions introducedwith the clay are considered in the test.The void fraction iscalculated as follows based upon the density of the clay being2.60 Mg/m3:VF5 1 2W2.603A 3L(2)where:VF=void fraction in the filter cake,W=dry weight of the filter cak