BS ISO 12744 pdf download Copper, lead, zinc and nickel concentrates — Experimental methods for checking the precision of sampling
This International Standard specifies methods for checking the precision of primary sampling, sample processing, chemical analysis, physical testing and determination of moisture content of copper, lead, zinc and nickel concentrates being carried out in accordance with the methods specified in ISO 1 2743, expressed in terms of standard deviations.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1 2743, Copper, lead, zinc and nickel concentrates — Sampling procedures for determination of metal and moisture content
3 General conditions
3.1 General The determination of precision of primary sampling is based on collecting pairs of interleaved samples from each lot. If sample processing and measurement are also carried out in duplicate, it is possible to determine the precision of sample processing and analysis.
3.2 Number of lots It is recommended that pairs of interleaved samples be collected from more than 20 lots of the same type of concentrate, in order to reach a reliable conclusion. The lot size shall be chosen to ensure that this requirement is met.
3.3 Number of increments and number of samples The minimum number of increments for checking precision should preferably be twice the number determined in accordance with ISO 1 2743. Hence, if the number of increments required for routine sampling is n and one lot sample is constituted, the minimum number of increments should be 2n, and two interleaved samples shall be constituted. Alternatively, if the precision is being checked as part of routine sampling, n increments may be taken and two interleaved samples constituted, each comprising n/2 increments. The sampling precision thus obtained must be divided by 2 to obtain the sampling precision for lot samples comprising n increments.
3.4 Sample processing and analysis Sample processing shall be carried out in accordance with ISO 1 2743. The analysis of samples shall be carried out according to the methods specified in the relevant International Standards.
3.5 Frequency of precision checks It is recommended that, even after a precision check has been conducted, further checks be carried out at regular intervals. Precision checks should also be carried out when there is a change in equipment. Because of the large amount of work involved in checking precision, it is recommended that checks be carried out as a part of routine sampling and analysis.