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1、International Standard ( 8541 0 a 4 4igib INTERNATIONAL ORGANIZATION FOR STANDARDIZATlON.MEYHAPOHAR DPl-AHM3AUK-l nD CTAHAAPTti3AUMWORGANlSATlON INTERNATIONALE DE NORMALISATIDN Manganese and chromium ores - Experimental methods for checking the bias of sampling and sample preparation Minerais de man
2、gake et de chrome - Mkthodes expkrimenteies de contHe de lerreur systkmatique dkhantilonnage et de prhparation des Bchantillons First edition - 1966-10-15 z UDC 663.32 + 663.461 : 620.113 Ref. No. IS0 6541-1666 (E) % ? Descriptors : minerals and ores, manganese ores, chromate minerals, quality audit
3、, statistical quality control, sampling, rules of calculation. s Price based on 6 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 21:22:12 MDTNo reproduction or networking
4、permitted without license from IHS -,-,- Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member b
5、ody interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO,. also take part in the work. Draft International Standards adopted by the technic
6、al committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 8541 was prepared by Tech
7、nical Committee ISO/TC 65, Manganese and chromium ores. Users should note that all International Standards undergo revision from time to time and that any reference tiade herein to any other International Standard implies its latest edition, unless othetwise stated. 0 International Organization for
8、Standardization, 1966 0 Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 21:22:12 MDTNo reproduction or networking permitted without license from IHS -,-,-
9、INTERNATIONAL STANDARD IS0 6641-1666 (E) Manganese and chromium ores - Experimental methods for checking the bias of sampling and sample preparation 1 Scope and field of application This International Standard specifies experimental methods for checking the bias of sampling and preparation of sample
10、s of manganese and chromium ores, whether natural or processed, when the sampling is carried out in accordance with the methods specified in the relevant International Standards. 2 References IS0 429611, Manganese ores - Sampling - Part I : Increment sampling. IS0 429612, Manganese ores - Sampling -
11、 Part 2: Preparation of samples. 3 General conditions 3.1 The sampling and preparation of samples shall be carried out in accordance with the methods specified in the relevant International Standards. 3.2 In the experimental method, the results obtained from the method to be checked (referred to as
12、method Bl shall be compared with the results of a specified reference method (referred to as method A) which is assumed to produce prac- tically unbiased results from technical and empirical view- points. The comparison shall be made by use of a statistical method of test for significance of differe
13、nce between two mean values of test results at the 5 % level of significance. 3.3 The quality characteristics to be selected for the purposes ofbxperiment shall be the major chemical elements. particle size distribution or moisture content of the ore, as the case may be. 3.4 The experiment shall be
14、conducted on at least 10 con- signments or 10 parts of the consignments. 3.5 When individual increments of a sample taken by method A and that by method B are correctly paired, the method of data analysis for paired data shall be applied. In order to apply the method of paired data analysis, it is i
15、ndis- pensable to design and to perform the field experiment so that the pairing of samples, one by method A and the other by method B, is assured technically. Such pairing is generally assured if the two samples taken by method A and method B are from identical material and undergo identical proces
16、sing and analysis almost simultaneously under similar conditions. 3.6 In cases where the pairing of individual increments of a sample taken by method A and that by method B is considered to be not sufficient, the method of data analysis for unpaired data shall be applied. The method of unpaired data
17、 analysis used in this International Standard is based on the condition that the numbers of measurements of method A and method B are the same. Care shall be taken to obtain the same number of increments of a sample for both methods. 4 Experimental methods 4.1 Experiments.for bias of sampling 4.1.1
18、Methods to be checked Examples of checking the bias of methods of sampling are given in 4.1.1.1 to 4.1.1.5. 4.1.1.1 Sampling from conveyors Method A: Stopped-belt sampling shall be the reference method in which each increment is taken from a stopped-belt conveyor at a specified place over the full w
19、idth and thickness of the ore stream with the required length. Method B : Each increment is taken from a point selected at random each time within the ore stream. 4.1.1.2 Sampling from wagons Method A : Stopped-belt sampling (see 4.1 :l .I I shall be the reference method. It is required to provide a
20、 belt conveyor system for the experiment. Method B: A sample consisting of the required mass and number of increments is taken at random from the surface of the ore exposed during the loading or discharging of wagons or trucks. 1 Copyright International Organization for Standardization Provided by I
21、HS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 21:22:12 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 8541-1986 (E) 4.1 .I .3 Sampling from stockpiles 4.2 Experiment for bias of sample preparation Method A: The meth
22、od of sampling on conveyors as specified in the relevant International Standards shall be the reference method. Where practicable, method A given in 4. I. 1.1 is recommended. Method B: The method of sampling from stockpiles as specified in the relevant International Standards is the method to be che
23、cked. 4.1.1.4 Sampling from containers Method A: Each increment shall be the ore contained in a container in its entirety, which has been selected at random in the sampling. Method B : Each increment is taken at random from the ore in a container which has been selected at random in the sampling. 4.
24、2.1 Methods to be checked Examples of checking the bias of methods of sample prep- aration are as follows : Method A : The residue of sample in its entirety obtained after having been taken from the divided sample by a dividing ap- paratus shall be the reference sample. Method B: The divided sample
25、obtained by the dividing ap- paratus is a controlled sample. The dividing apparatus to be used for method A and method B shall be the same. Other examples may be given in terms of stages of division, different dividing apparatus, etc. For instance, if method A is the reference method, method B may b
26、e the one which uses a different dividing apparatus or involves fewer stages of division. 4.1.1.5 Mechanical sampling 4.2.2 Preparation of experimental samples Method A: The increments taken by method A given in 4.1.1.1 shall be the reference sample. Method B: Each increment is taken by the installe
27、d mechanical primary sampler. 4.1.2 Experimental sampling Two gross samples shall be taken from the same consignment under study, or the same part of the consignment, one of the two shall be taken by method A and the other by method B. The gross sample taken by method A is designated gross sample A
28、and that taken by method B gross sample B. 4.1.3 Preparation of experimental samples These two gross samples shall be processed separately for the preparation of the respective final sample by the same method, and shall be tested for the selected quality characteristics by the same method. 4.1.4 Pai
29、ring the increments The gross samples A and B shall be taken from theportion of the ore as being regarded to be practically the same, on an in- dividual increment basis. The selected quality characteristics shall be determined and the measurements recorded on a data sheet such as that given in table
30、 3. 4.1.5 Unpaired increments In the event that the pairing of increments is not achieved, the measurements shall be recorded on a data sheet such as that given in table 4. A pair of final samples shall be prepared from the same sample under study, one by method A, designated sample A, and the other
31、 by method B, designated sample B. 4.2.3 Determination and recording The quality characteristics shall be determined and the measurements recorded on a data sheet such as that given in table 4. 5 Data analysis The test for significance of difference between two experimen- tal results, in other words
32、 deviation of the results of method B from the results of the reference method A, shall be carried out by the t-test. For unpaired data, the F-test for equality of variances shall be carried out prior to the t-test. 5.1 Paired data 5.1.1 Calculate the difference between paired measurements di = XBi
33、- XAi i = 1,2, . . k where XAir Xai are respectively the ith measurements of sample A obtained by the reference method A and the ith measurement of sample B obtained by the method B to be checked; di is the ith difference of deviation of xsi from XAi; k is the number of pairs of measurements of samp
34、le A or of sample B. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 21:22:12 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 6641-1966 (El 5.1.2
35、Calculate the mean of differences to one decimal place 5.2.1.1 For the sake of simplicity, transform the crude further than that used in the measurements themselves measurements to integers d=$di where d is the mean value of k differences. . . . (2) XAi = (XA - cl)h i = 1,2, . . n . . . (6) XBi = (X
36、Bi - cJ)h i = 1,2, . . . . n where 5.1.3 Calculate the unbiased estimates of variance of the dif- ferences x . . (3) where V, is the unbiased estimate of variance of differences; is the number of degrees of freedom, 4 = k - 1. 5.1.4 Calculate the observed value of t, denoted by to, by rounding off t
37、o the third decimal place to= Clf CP are respective subtracting constants, arbitrarily selected separately, for the transformation; h is a multiplying constant arbitrarily selected for the transformation; n is the number of measurements of sample A or of sample B. 5.2.1.2 Calculate the mean values o
38、f measurements of samples A and B, denoted .?A and ya respectively, and express them by inverting the transformation xA ?A = cl + - h - XB . . . (7) YB = c2 + - h where and XB = $xBi i = 1,2, . . ., n 5.2.1.3 Calculate the sums of squares, denoted SA and ss respectively SA= xX in this method nA = ng
39、 = n. 5,2.1.5 Calculate the ratio of V, of method B to VA of the reference method A by equation (10) and round off to the second decimal place. In this method it is assumed that the variance of the reference method A would be smaller than that of method B (VA V, change the denomi- nator for numerato
40、r so that the ratio is greater than unity, and use equation (lOa). F, = VB/V,j F, 1 * . . (10) F. = VA/I/B F, 1 . t * (lOa) 5.2.1.6 Obtain the F-statistic at the 5 % level of significance for #a and A degrees of freedom (48 = A = f$j, denoted by F(#, ; 0,051. (See table 2.) 5.2.1.7 Compare the obser
41、ved F, value obtained by exper- iment with the F(, ; 0,05) point obtained from table 2. When F, F(, ; 0,05), then the test is failed . . . (12) 5,2.1.8 When the F-test is passed, conduct the t-test as specified in 5.2.2. When the F-test is failed, reject the experimental results, improve the techniq
42、ue and, if necessary, carry out a further experiment. 5.2.2 t-test for significance of difference 5.2,2.1 Calculate the obsen/ed value of the t-statistic, denoted to, by rounding off to the third decimal place * (13) hence to = FB - FA s, -+ sB If- Gn where A = nA - 1 ( WW ) 4 9 10 11 12 13 14 15 16
43、 17 18 19 20 F 3,18 2,98 a= 289 2,88 2,48 2,40 233 2,27 2,22 2,17 2,12 1) Source: MERAINGTON, M. and THOMPSON, CM., Tables of percentage points of the inverted beta distribution, Biometrika 33 1943. 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Lic
44、ensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 21:22:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO6541-1666(E) Table 3 - Data sheet for t-test of paired data (example) Designation of experiment: Type of ore : (for example manginese ore) Date
45、s of experiment : Consignment No. Name of ore 1. 2. xBi Quality characteristic (for example % Mn) XAi di = XBi - XAi .df k. t-test Vd = iC df - (C di)/k= f.= t(2qa 0,051 Statement of the result of t-test: *. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 21:22:12 MDTNo reproduction or networking permitted without license from IHS -,-,-
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