ASTM D521-02 pdf free.Standard Test Methods for Chemical Analysis of Zinc Dust (Metallic Zinc Powder).
Dissolve22 g of potassium ferrocyanide (KFe(CN)·3H ,O) in waterand dilute to 1 L.To standardize, transfer 0.2 g of metallic zincor freshly ignited zinc oxide (ZnO) to a 400-mL beaker.Dissolve in 10 mL of hydrochloric acid (HCl), sp gr 1.19 and20 mL of water. Drop in a small piece of litmus paper，addammonium hydroxide (NH OH) until slightly alkaline, thenadd HCl until just acid, and then 3 mL more of HC1. Dilute toabout 250 mL with hot water and heat nearly to boiling. Run inthe K 4Fe(CN),solution slowly from a buret，while stirringconstantly, until a drop tested on a white porcelain plate with adrop of the uranyl indicator solution shows a brown tinge afterstanding 1 min. Do not allow the temperature of the solution tofall below 70°C during the titration. Run a blank using thesame amounts of reagents and water as in the standardization.The standardization must be made under the same conditionsof temperature,volume,and acidity as obtained when thesample is titrated.
Transfer 20 g of the specimen, weighed to the nearest0.1 g, to a 600-mL beaker. Cover the sample with 50 mL ofsaturated bromine water and then cautiously add HNO;(sp gr1.42) until solution is complete.
Add 1 g of anhydrous sodium carbonate (Na ,CO3 ) andboil down until salts just begin to separate, then add 75 mL ofHCl (sp gr 1.19) and again boil down until salts begin toseparate.Repeat this operation and, finally, dilute to 100 mL,heat until solution is complete, and filter into a 400-mL beakerthrough close-texture paper.
Wash the paper with hot water，make the filtratealkaline with NH4OH, and then just acid with HC1.Heat toboiling and hold at boiling temperature at least 5 to 10 min todrive out Co , then slowly add with stirring 5 mL of BaC1,solution. Allow to stand at least 5 h (preferably overnight).24.4 Filter on a weighed Gooch crucible， wash free fromchlorides with hot water，dry,and ignite carefully at 900°c.Cool and weigh. The difference between the original and finalweight is BaSo 4.
Make a blank determination，following thesame procedure and using the same amounts of all reagents.ASTM D521 pdf download.