ASTM_E_1028_-_98.pdf

Designation:E 1028 98Standard Test Method forTotal Iron in Iron Ores and Related Materials by DichromateTitrimetry1This standard is issued under the fixed designation E 1028;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of total ironin iron ores,concentrates,and agglomerates in the concentra-tion range from 35 to 95%iron.1.2 This standard does not purport to address all of thesafety problems,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:E 50 Practices for Apparatus,Reagents,and Safety Precau-tions for Chemical Analysis of Metals2E 877 Practice for Sampling and Sample Preparation of IronOres and Related Materials33.Summary of Test Method3.1 Acid DecompositionThe sample is dissolved in hy-drochloric acid.The insoluble residue is removed by filtration,ignited,treated for the recovery of iron,and added to the mainsolution.3.2 Decomposition by FusionThe sample is fused with amixture of sodium carbonate and sodium peroxide or sinteredwith sodium peroxide at 400C,and fused over a burner.Themelt is leached with water and acidified with hydrochloric acid.For samples containing more than 0.1%vanadium or 0.1%molybdenum,or both,the melt is leached with water andfiltered.The insoluble iron hydroxide is then dissolved inhydrochloric acid.3.3 Reduction of the IronMost of the iron is reduced in ahot 6M hydrochloric acid medium with stannous chloride,followed by the addition of a slight excess of titanium(III)solution.The excess Ti(III)is oxidized in the hot solution withperchloric acid.The solution is rapidly cooled and the reducediron is titrated with a standard dichromate solution usingsodium diphenylamine sulfonate as indicator.4.Significance and Use4.1 The determination of the total iron content is theprimary means for establishing the commercial value of ironores used in international trade and by industry.4.2 This test method is intended to be a referee method forthe determination of iron in iron ores.It is assummed that theuser of this procedure will be trained analysts,capable ofperforming common laboratory procedures skillfully andsafely.It is expected that work will be performed in a properlyequipped laboratory.5.Interferences5.1 This test method is written for iron ores containing lessthan 0.1%of copper.Other elements normally found in ironores do not interfere with this test method.6.Apparatus6.1 Zirconium,vitreous carbon,or sintered alumina cru-cibles,25 to 30-mL capacity.6.2 Weighing Spatula,of a nonmagnetic material or demag-netized stainless steel.7.Reagents7.1 Purity and Concentration of ReagentsThe purity andconcentration of all reagents used shall conform to PracticesE 50.7.2 Ammonium Hydroxide(sp gr 0.90)Concentrated am-monium hydroxide(NH4OH).7.3 Hydrochloric Acid(sp gr 1.19)Concentrated hydro-chloric acid(HCl).7.4 Hydrochloric Acid(1+1)Mix 1 volume of concen-trated hydrochloric acid(HCl)with 1 volume of water.7.5 Hydrochloric Acid(1+2)Mix 1 volume of concen-trated hydrochloric acid(HCl)with 2 volumes of water.7.6 Hydrochloric Acid(1+10)Mix 1 volume of concen-trated hydrochloric acid(HCl)with 10 volumes of water.7.7 Hydrochloric Acid(1+50)Mix 1 volume of concen-trated hydrochloric acid(HCl)with 50 volumes of water.7.8 Hydrofluoric Acid(sp gr 1.15)Concentrated hydrof-luoric acid(48 to 50%HF).1This test method is under the jurisdiction of ASTM Committee E-1 onAnalytical Chemistry for Metals,Ores,and Related Materials and is the directresponsibility of Subcommittee E01.02 on Ores,Concentrates,and Related Metal-lurgical Materials.Current edition approved May 10,1998.Published July 1998.Originallypublished as E 1028 84.Last previous edition E 1028 93.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 03.05.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.7.9 Ice WaterCool water to about 3 to 5C by adding icecubes,prepared from distilled water or water of equivalentpurity.7.10 Iron(II)Ammonium Sulfate Solution(approximately0.1 N)Dissolve 40 g of iron(II)ammonium sulfate,(FeSO4(NH4)2SO46H2O)in dilute sulfuric acid(7.22).Transfer to a1-L volumetric flask,dilute to volume with the same acid,andmix.Standardize against the standard potassium dichromatesolution(7.13)using diphenylamine sulfonate as indicator(9.6).7.11 Perchloric Acid(1+1)Mix 1 volume of perchloricacid(70%)(HClO4)with 1 volume of water.7.12 Phosphoric Acid(sp gr 1.57)Concentrated phospho-ric acid(H3PO4).7.13 Potassium Dichromate,Standard Solution(0.1 N)Pulverize about 6 g of potassium dichroma