ISO 15247 pdf download.Zinc sulfide concentrates — Determination of silver content — Acid dissolution and flame atomic absorption spectrometric method
1 Scope
This International Standard specifies an acid dissolution and flame atomic absorption spectrometric method for the determination of silver content of zinc sulfide concentrates. The method is applicable to the determination of silver in zinc sulfide concentrates containing up to 60 % (m/m) zinc in the form of zinc blende and related materials. The method is applicable to silver contents from 1 0 g/t to 500 g/t.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 385-1 :1 984, Laboratory glassware — Burettes — Part 1 : General requirements. ISO 648:1977, Laboratory glassware — One mark pipettes. ISO 1042:1998, Laboratory glassware — One-mark volumetric flasks. ISO 3696:1987, Water for analytical laboratory use — Specification and test methods . ISO 4787:1984, Laboratory glassware — Volumetric glassware — Methods for use and testing of capacity. ISO 9599:1991, Copper, lead and zinc sulfide concentrates — Determination of hygroscopic moisture in the analysis sample — Gravimetric method.
3 Principle
Decomposition of the concentrate in hydrochloric and nitric acids. Dissolution of the digestion residue in hydrochloric acid and measurement by flame atomic absorption at 328,1 nm.
4 Reagents
During the analysis, use only reagents of recognized analytical grade and water that complies with grade 2 of ISO 3696. 4.1 Silver metal, minimum 99,99 % purity. 4.2 Nitric acid, ( ρ 20 1 ,42 g/ml), chloride content < 0,5 µg/ml. 4.3 Nitric acid, (500 ml/l). To 250 ml of water carefully add, with stirring, 250 ml of nitric acid (4.2). 4.4 Hydrochloric acid, ( ρ 20 1 ,1 6 g/ml to 1 ,1 9 g/ml). 4.5 Hydrochloric acid, (200 ml/l). To 800 ml of water carefully add, with stirring, 200 ml of hydrochloric acid (4.4). 4.6 Ammonia solution, ( ρ 20 0,89 g/ml). 4.7 Ammonia solution, (250 ml/l). To 750 ml of water add, with stirring, 250 ml of ammonia solution (4.6). 4.8 Silver standard solutions 4.8.1 Silver standard solution, (1 000 µg/ml) Weigh 0,500 0 g of silver metal (4.1 ) into a 250 ml conical beaker, add 50 ml of nitric acid (4.3), cover and heat gently until the metal dissolves. Remove the cover and evaporate gently to near dryness. Add 250 ml of hydrochloric acid (4.4) and warm until the solution clears. Cool, and transfer to a 500 ml volumetric flask. Dilute to volume with water and mix thoroughly. This solution should be freshly prepared, unless it is being used on a regular basis. 4.8.2 Silver standard solution, (1 00 µg/ml) Pipette 1 0 ml of silver standard solution (4.8.1 ) into a 1 00 ml volumetric flask containing 45 ml of hydrochloric acid (4.4). Dilute to volume with water and mix thoroughly. NOTE 1 Standard solutions should be prepared at the same ambient temperature as that at which the determinations will be conducted. NOTE 2 Silver standard solutions should be stored in brown glass bottles. 4.9 Calibration solutions To six 1 00 ml volumetric flasks, each containing 20 ml of hydrochloric acid (4.4), add from a burette (5.2) 0 ml, 1 ml, 2 ml, 3 ml, 4 ml and 5 ml of silver standard solution (4.8.2). Dilute to volume with water and mix thoroughly. These standards contain 0 µg, 1 µg, 2 µg, 3 µg, 4 µg and 5 µg of silver per ml and shall be freshly prepared.
5 Apparatus
Ordinary laboratory apparatus and 5.1 Volumetric glassware, of class A complying with ISO 385-1 , ISO 648 and ISO 1 042 and used in accordance with ISO 4787. 5.2 Burette, grade A 1 0 ml capacity, capable of being read to 0,02 ml. 5.3 Atomic absorption spectrometer (AAS), equipped with a glass bead in the spray chamber rather than a flow spoiler. 5.4 Balance, precision analytical, capable of being read to 0,1 milligram.