AS ISO 19976.1:2020 – Copper, lead and zinc sulfide concentrates —Determination of cadmium Part 1: Flame atomic absorption spectrometric method.
8 Procedure
8.1 Number of determinations
Carry out the determinations at least in duplicate, as tar as possible under repeatability conditions, on each test sample.
NOTE Repeatability conditions exist where mutually Independent test results are obtained with the same method on identical test material in the same laboratory by the same operator using the same equipment, within short Intervals oltime.
8.2 Blank test
Carry out a blank test in parallel with the analysis using the same quantities of all reagents but omitting the test portion. The purpose of the blank test in this method is to check the quality of reagents. If a sigmilcant blank value Is obtained as a result of the blank test, check all reagents and rectify the problem.
8.3 Determination
8.3.1 DIssolution of test portion
Transfer the test portion into a 200 ml polytetrafluoroethylene beaker (6.2) and moisten with 5 ml of water.
Add 10 ml of hydrochloric acid (5.1) and heat for S mm at 60 °C to 70 °C. Add 10 ml of nitric acid (5.4) and heat gently. Add 3 ml of hydrofluoric acid (5.), then heat gradually until the solution is about 5 ml at 60 °C to 70 °C. Add perchloric acid (5.6) repeatedly until the residue is not present. Heat until the strong white fumes have exhausted completely, then allow to cool.
Add 40 ml of hydrochloric acid (5.2) [for lead concentrate samples, add 50 ml of hydrochloric acid (5.3)]. Wash down the cover and sides of the beaker and then heat until the onset of boiling, then allow to cool.
8.3.2 Preparation of test solutions
Transfer the solution (8.3.1) to a 200 ml one-mark volumetric flask, dilute to the mark with water and mix thoroughly Ifor lead concentrate samples, filter the solution through an Insoluble filter paper (6.5)1. Wash the precipitate with hydrochloric acid (5.3) and collect the filtrate in a 200 ml one-mark volumetric flask, Dilute to the mark with hydrochloric acid (5.3) and mix thoroughly. Then transfer an appropriate aliquot of this solution (see Table 1) to the corresponding one.mark volumetric flask. Add an appropriate amount of hydrochloric acid 5.2) as indicated in Table L fill up nearly to the mark with water, mix and cool to room temperature, then fill up exactly to the mark with water and mix again.
The dilutions shown in Table 1 will provide concentrations of cadmium falling within the range of the calibration solutions.
This annex specifies a method for the preparation and determination of the mass of a predried test portion in the analysis of copper. lead and zinc sulfide concentrates.
The method is applicable to copper, lead and zinc sulfide concentrates not susceptible to oxidation and with hygroscopic moisture contents ranging from 0,05 % to 2 %.
A.2 Principle
The test portion to be used for analysis Is dried in air in an oven maintained at 105 °C ± S °C. The dried test portion is then weighed and used for the analysis. No correction for hygroscopic moisture is required.
A.3 Chemicals
A.3.1 Desiccant, such as self-indicating silica gel or anhydrous magnesium perchlorate.
WARNING — Care must be taken when disposing of exhausted magnesium perchlorate. It must be washed down the sink with a stream of running water.
A.4 Apparatus
Ordinary laboratory equipment, and the following.
A.4.1 Analytical balance, sensitive to 0,1 mg.
A.4.2 Weighing vessels, of glass or silica or corrosion-resistant metal, with externally fitting airtight covers. For small test portions (of mass less than 3 g). thc mass of t,he vessel shall be as small as possible. i.e. less than 20g.
A.4.3 Laboratory oven, capable of maintaining a temperature of 105 °C ± 5 C.
A.5 Procedure
A.5.1 Preparation of the weighing vessel
Dry the weighing vessel and its cover (A42) by heating in the laboratory oven (AA3) at 105 C i 5 C for I h. Transfer the vessel and its cover to a desiccator containing a suitable fresh desiccant (A.3.1) and allow to cool to ambient temperature.