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1、BRITISH STANDARD BS ISO 3086:2006 Iron ores Experimental methods for checking the bias of sampling ICS 73.060.10 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 3086:2006 This British Standard was published under the authority of th
2、e Standards Policy and Strategy Committee on 31 May 2006 BSI 2006 ISBN 0 580 48386 X National foreword This British Standard reproduces verbatim ISO 3086:2006 and implements it as the UK national standard. It supersedes BS ISO 3086:1998 which is withdrawn. The UK participation in its preparation was
3、 entrusted to Technical Committee ISE/58, Iron ores, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may
4、be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users ar
5、e responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and
6、 keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 23 and a back cover. The BSI copyright notice displayed in
7、 this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 3086:2006(E) INTERNATIONAL STANDARD ISO 3086 Fourth ed
8、ition 2006-04-15 Iron ores Experimental methods for checking the bias of sampling BS ISO 3086:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolle
9、d Copy, (c) BSI iii Contents Page Foreword iv 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 Principle. 2 5 General conditions . 2 6 Sampling and sample preparation methods 2 6.1 Sampling 2 6.2 Sample preparation 2 7 Analysis of experimental data. 3 7.1 Computation of the differe
10、nces. 3 7.2 Determination of the mean and the standard deviation of the differences 3 7.3 Test for outliers Grubbs test 3 7.4 Selection of data for use in statistical test for bias. 5 7.4.1 Consideration of outliers whose causes are assignable 5 7.4.2 Consideration of outliers whose causes are not a
11、ssignable. 5 7.4.3 Consideration of amount of data remaining 5 7.5 Statistical test for bias 5 7.5.1 Determination of the confidence interval for d 5 7.5.2 Interpretation of confidence interval 6 8 Test report . 7 Annex A (normative) Flowsheets of the statistical analysis 8 Annex B (informative) Num
12、erical examples of experiments 11 BS ISO 3086:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies
13、). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and no
14、n-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Par
15、t 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting
16、 a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 3086 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron, S
17、ubcommittee SC 1, Sampling. This fourth edition cancels and replaces the third edition (ISO 3086:1998), which has been technically revised. BS ISO 3086:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Iron ores Experimental methods for
18、 checking the bias of sampling 1 Scope This International Standard specifies experimental methods for checking the bias of sampling of iron ores, when sampling is carried out in accordance with the methods specified in ISO 3082, having as reference a stopped-belt sampling method. It is recommended t
19、hat an inspection of the mechanical sampling system be carried out before conducting bias testing. Sampling systems not completely in accordance with ISO 3082 are not always expected to be biased. Therefore, bias checking may be done when there is some disagreement about the importance of some depar
20、ture from the conditions of ISO 3082. If one party argues that the bias is likely to be substantial under some particular set of conditions then bias testing should mostly be done when those conditions apply. NOTE The method for analysis of experimental data described here may also be applied: a) fo
21、r checking the bias of sample preparation of iron ores, having as reference the methods for sampling preparation according to ISO 3082; b) for checking the bias of size distribution of iron ores by sieving, having as reference the hand sieving methods according to ISO 4701; c) for checking a possibl
22、y significant difference in the results obtained from the samples of one lot collected at different places, for example, a loading point and unloading point. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only t
23、he edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3082:2000, Iron ores Sampling and sample preparation procedures ISO 3085:2002, Iron ores Experimental methods for checking the precision of sampling, sample prepara
24、tion and measurement ISO 11323:2002, Iron ore and direct reduced iron Vocabulary 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 11323 apply. BS ISO 3086:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolle
25、d Copy, (c) BSI 2 4 Principle The results obtained from the method to be checked (referred to as method B) are compared with the results of a reference method (referred to as method A) which is considered to produce practically unbiased results, from technical and empirical viewpoints. In the event
26、of there being no significant difference, in a statistical sense, between the results obtained by method B and method A, method B may be adopted as a routine method. This difference is assessed by comparing a 90 % confidence interval for the true average bias with the relevant bias, (see 5.2). 5 Gen
27、eral conditions 5.1 The number of paired sets of measurement shall not be less than ten. The number of further tests required depends on the results of the outlier test and of the statistical analysis of the confidence interval for the true average bias, based on at least ten paired sets. NOTE A pai
28、red set of measurement is a paired measurement data of samples, which are sampled by methods A and B, and prepared and measured in the same way, for identical material. 5.2 The relevant bias, , which is considered large enough to justify the likely expense of reducing the average bias, shall be deci
29、ded beforehand. As a guide, is likely to be less than SPM, the standard deviation for sampling, sample preparation and measurement, determined according to ISO 3085. NOTE If the experiment is aimed at checking sample preparation only, the value of is likely to be less than PM, determined according t
30、o ISO 3085. 5.3 Quality characteristics, such as total iron content, moisture content, size distribution and physical properties, may be used. 6 Sampling and sample preparation methods 6.1 Sampling The reference method, method A, for checking the bias of sampling is a stopped-belt sampling method in
31、 accordance with ISO 3082. Method A: take each increment from the full width and thickness of the ore stream on the stopped conveyor at a specified place, for a length of belt more than three times the nominal top size or 30 mm, whichever is the greater. The method to be checked, method B, carried o
32、ut according to ISO 3082 as far as possible, shall be compared with method A for the same material. Method B: sampling methods, such as sampling from moving conveyors with a mechanical sampler and sampling during the transfer to or from ships and wagons, are examples of method B. Samples from Method
33、s A and B shall be taken as close together as possible. This is particularly important for ore streams which are known to be variable. 6.2 Sample preparation 6.2.1 Increments obtained from one lot, in accordance with methods A and B, are made up into two gross samples, A and B. BS ISO 3086:2006 Lice
34、nsed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 6.2.2 The gross samples, A and B, are subjected, in the same manner, to sample preparation as specified in ISO 3082, and tested as specified in the relevant International Standards separately, an
35、d a pair of measurements obtained. 6.2.3 The above procedure is performed on ten or more lots (see 5.1). When increments for methods A and B can be taken from closely adjacent portions of the ore, it is recommended that sample preparation and testing be carried out on individual increments or on com
36、binations of a small number of adjacent increments. This allows comparisons of ten or more pairs of measurements to be made more quickly than if measurements were only made on entire lots. The above comparison of measurements should be made on pairs of increments taken from several lots, preferably
37、of the same type of ore. However, it is not permitted to combine a number of paired results, originating from both increments and gross samples. It should be either a number of pairs from increments or from gross samples. NOTE Given the cost and inconvenience of stopped-belt sampling, it is generall
38、y economic to conduct sample preparation and measurement in duplicate and with great care so that the number of stopped-belt samples might be reduced. 7 Analysis of experimental data NOTE The procedures described in 7.1 to 7.5 are also shown in the form of a flowsheet in Annex A (normative). 7.1 Com
39、putation of the differences 7.1.1 Denote measurements obtained in accordance with methods A and B, by xAi and xBi, respectively. When sampling preparation and measurement have been conducted in duplicate, these measurements will be averaged. 7.1.2 Calculate the difference, di, between xAi and xBi us
40、ing the equation: BA 1, 2, . iii dxxik= (1) where k is the number of paired sets of measurements. 7.2 Determination of the mean and the standard deviation of the differences 7.2.1 Calculate the mean of the differences,d with one decimal place more than that used in the measurements themselves: 1 i d
41、d k = (2) 7.2.2 Calculate the sum of squares, SSd, and the standard deviation of the differences, Sd, with one decimal place more than that used in the measurements themselves: () 2 2 1 SSd ii dd k = (3) SS (1) d d S k = (4) 7.3 Test for outliers Grubbs test 7.3.1 Sort di into ascending order. BS IS
42、O 3086:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 7.3.2 Calculate the Grubbs test statistics Gk and G1, using the following equations: k k d dd G S = (5) 1 1 d dd G S = (6) where dk is the largest value of di; d1 is the smallest
43、value of di; 7.3.3 Choose the larger of Gk and G1. 7.3.4 Compare the larger of Gk and G1 with the critical value for Grubbs test at the 5 % significance level according to Table 1. Table 1 Critical values for Grubbs outlier test k Critical value (5 %) k Critical value (5 %) k Critical value (5 %) 6
44、1,887 12 2,412 18 2,651 7 2,020 13 2,462 19 2,681 8 2,126 14 2,507 20 2,709 9 2,215 15 2,549 21 2,733 10 2,290 16 2,585 22 2,758 11 2,355 17 2,620 23 2,781 NOTE Critical values for Grubbs test for a wider range of numbers of observations, and for additional significance levels, are given in Grubbs,
45、F. E. and Beck, G. (1972) Extension of sample sizes and percentage points for significance tests of outlying observations, Technometrics 14, pp. 847-854. 7.3.4.1 If the larger of Gk and G1 is less than or equal to the critical value, conclude that there is no outlier. Proceed with 7.5. 7.3.4.2 If th
46、e larger of Gk and G1 is larger than the critical value: 7.3.4.2.1 If the larger is Gk, conclude that the largest value of the difference, dk, is an outlier. 7.3.4.2.2 If the larger is G1, conclude that the smallest value of the difference, d1, is an outlier. 7.3.5 Exclude the outlier di, repeat the
47、 procedure described in 7.2 to 7.3.3. 7.3.6 Compare the larger of Gk and G1 with the critical value for Grubbs test at 5 % significance level according to Table 1. 7.3.6.1 If the larger of Gk and G1 is less than or equal to the critical value, conclude that there is no outlier and proceed with 7.4.
48、BS ISO 3086:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:42:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 7.3.6.2 If the larger of Gk and G1 is larger than the critical value: 7.3.6.2.1 If the larger is Gk, conclude that the largest value of the difference, dk, is an outlier. 7.3
49、.6.2.2 If the larger is G1, conclude that the smallest value of the difference, d1, is an outlier. 7.3.7 If at least 60 % of the initial set of data remain, proceed with 7.3.5. 7.3.8 If not, stop the outlier test, reinstate all outliers and proceed with 7.5. 7.4 Selection of data for use in statistical test for bias 7.4.1 Consideration of outliers whose causes are assignable Once outliers have been detected by Grubbs test, consideration should be given to assignable caus
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