GB/T 8151.3-2012Methods for chemical analysis of zinc concentrates - Part 3: Determination of iron content - Na2EDTA titrimetric method (English PDF)

3.1

ammonium chloride.

3.2

hydrochloride (rho1.19g/mL).

Nitrate 3.3 (rho1.42g/mL).

3.4

Ammonia (rho0.90g/mL).

3.5

hydrochloride (11).

3.6

hydrochloride (111).

3.7

Aqueous ammonia (11).

3.8 lotion

25g ammonium chloride (3.1) in 500mL water dissolved, add 20mL ammonia (3.4), and mix.

3.9

sulfosalicylic acid solution (100g/L).

3.10

disodium edetate (Na2EDTA) standard titration solution.

3.10.1 preparation

Weigh 20gNa2EDTA (C10H14N2O8Na2 · 2H2O) in a beaker, add about 400mL dissolved in hot water, cold

To room temperature. Moved into 1000mL volumetric flask, dilute to the mark, mix, 3d place after calibration.

3.10.2

Calibration.

3.10.2.1 pretreatment of metal wire

metal wire (wFe>=99.9%) cut into small pieces (each less than 80mg), placed in dilute nitric acid (13) soaked 1min ~ 2min, out on ethanol (anhydrous) soaked 1min ~ 2min, removed after repeated dry immediately with filter paper

Weigh.

3.10.2.2 Calibration

said pretreated metal wire learn about 0.06g (accurate to 0.0001g) were placed in 300mL beaker, add

20mL of nitric acid (11), after dissolved by heating evaporated to near dryness 10mL hydrochloric acid (3.2), washed with water table dish and cup wall, then steamed in a cold place

To nearly dry, with about 10 drops of hydrochloric acid (3.2) to dissolve salt, add water to about 120mL, appears with ammonia (3.7) and to iron hydroxide, plus

10mL hydrochloric acid (3.6), heated to near boiling, remove, add about 1mL sulfosalicylic acid solution (3.9), the standard titration solution Na2EDTA (3.10) titration until the solution changed from red to yellow as the end point.

Along with the calibration blank test.

According to equation (1) to calculate the concentration Na2EDTA standard titration solution.

c = m155.85 × (V2-V1) (1) […]