GB/T 15249.4-2009Methods for chemical analysis of crude gold - Part 4: Determination of lead content - EDTA titrimetric method (English PDF)

3.1

hydrochloride (rho1.19g/mL).

3.2

HCl (2 + 98).

Nitrate 3.3 (rho1.42g/mL).

3.4

nitric acid (1 + 1).

3.5

sulfate (1 + 1).

3.6

sulfate (24 + 1).

3.7

sulfate (2 + 98).

3.8

sulfite (rho1.03g/mL).

3.9

ethanol.

3.10

acetic acid - sodium acetate buffer solution (pH5.5 ~ 6.0). The 375g of anhydrous sodium acetate dissolved in water, 50mL glacial acetic acid was added, washed with water

Diluted to 2.5L.

3.11 xylenol orange indicator solution (5g/L)

add 1 to 2 drops of ammonia (1 + 1) in 50mL solution. Use within 1 week.

3.12 Lead standard solution

Weigh 2.0000g metallic lead (w1 (Pb) >=99.99%) in 250mL beaker, add 40mL of nitric acid (3.4), covered with a watch glass placed on a hot plate, heated and dissolved low temperature, until complete dissolution of the oxides of nitrogen purge boiling, removed, cooled to room temperature. Moved into 1000mL volumetric flask, dilute with water to volume, and mix. This solution 1mL lead 2mg.

3.13

disodium edetate (Na2EDTA) standard titration solution [Ba (Na2EDTA) ~0.01mol/L].

3.13.1 preparation

Weigh 18g disodium edetate (Na2EDTA) placed in 400mL beaker, add water 200mL heat gently to dissolve,

Cooled to room temperature, diluted to 5L, and mix.

3.13.2 Calibration

Pipette three 20.00mL lead standard solution (3.12), were placed in 250mL beaker, add 10mL sulfuric acid (3.5),

Low-temperature heating to take trioxide smoke, remove the cooled, washed with water Beibi, then low heat until smoke disappears, remove the cooling. Analysis by the following steps

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

Ba Ba = 0

· Vp 1 × 1000 (Vp Vp 2- 0) × 207.2 (1) […]