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1、INTERNATIONAL STANDARD IS0 13543 First edition 1996-07-01 Copper, lead and zinc sulfide concentrates - Determination of mass of contained metal in a lot Concent mw is the wet mass of the lot, in tonnes; M is the moisture content of the lot, in percent of the wet mass (m/m). 4.5 Mass of contained met
2、al 4.5.1 Major elements For the major elements copper, lead and zinc, the mass of contained metal in the lot is given by the equation: ma aL mM=- 100 . . . (2) where mM mD aL is the mass of contained metal in the lot, in tonnes; is the dry mass of lot, in tonnes; is the metal content of the lot on a
3、 dry basis, in percent (m/m). Alternatively, equation (2) can be rewritten as follows: mw FaL m”= 100 . . . where F is the moisture factor given by: F=,-E . . . 100 (3) 4.5.2 Precious metals For the precious metals silver and gold, the mass of contained metal in the lot is given by the equation: mw
4、Fa, m”= 1000 . . (5) mM is the mass of contained metal in the lot, in kilograms; mW is the wet mass of lot, in tonnes; F is the moisture factor; aL is the precious metal content of the lot on a dry basis, in grams per tonne (m/m). 5 Determination of variance of mass of contained metal The variance o
5、f the mass of contained metal in the lot can be determined from equation (3) by taking the partial derivatives with respect to the wet mass, the moisture factor and the metal content of the lot as follows: where 4 4 4 4 is the estimated variance of the mass of con- tained metal in the lot; is the es
6、timated variance of the wet mass of the lot; is the estimated total variance of the mois- ture factor = (Q/I OO)* with SH being the total precision (1 standard deviation) of moisture determination; is the estimated total variance of the metal content of the lot. Note that the estimated total varianc
7、es of the mois- ture factor and the metal content include the contri- butions from primary sampling, sample processing and analysis. Determining the partial derivatives and substituting them into equation (6) gives: s,ps,.zs+fg2s: (71 Equation (7) can be simplified as follows: Equation (8) is applic
8、able to both the major elements and the precious metals. 2 -,-,- 0 IS0 IS0 13543:1996(E) The vanance of the wet mass of the lot shall be de- termined in accordance with the procedures specified in IS0 12745 for estimating the precision of mass measurement techniques. The variances of the mois- ture
9、factor and the metal content of the lot shall be determined according to the procedures specified in IS0 12744. The analyses shall be carried out accord- ing to the methods prescribed in relevant International Standards. 6 Examples of calculation of contained metal and its variance 6.1 Static scale
10、Assume a 500 tonne lot containing 30 % copper (m/m), 10 g of gold/t (m/m) and 8 % moisture (m/m) is weighed using a static hopper scale with a capacity of 25 tonne, i.e. 20 hopper loads. The precision (I stan- dard deviation) of the hopper scale is 0,2 % relative. The lot is divided into 10 sub-lots
11、, and a single mois- ture determination is carried out on each subsample. A single lot sample is constituted for chemical analy- sis. The total precisions of the copper, gold and mois- ture determinations (1 standard deviation) are 0,05 % copper, 0,5 g of gold/t and 0,l % moisture absolute (m/m) res
12、pectively. 6.1.1 Mass of contained copper mw = 500t F =l- aL = 30 % copper 4 = (0,05)2 = 0,002 5 Equations (3) and (8) give: 500 x 0,92 x 30 mM = 100 = 138 t copper 0,000 000 1 0,002 5 0,922 +302 = 138* (0,000 000 2 + 0,000 000 12 + + 0,000 002 78) = 0,003 8 + 0,002 3 + 0,052 9 = 0,059 Calculation o
13、f the standard deviation SM gives: SM = 0,24 t Copper Hence, at the 95 % confidence level (i.e. two standard deviations), the mass of contained copper metal is: mM = 138 + O,5 t copper (i.e. + 0,4 % relative) The 95 % confidence range is 137,5 t of copper to 138,5 t of copper. In this case the preci
14、sion of the measured copper con- tent of the lot is the major contributor to the uncer- tainty in the mass of contained metal. This can be re- duced by carrying out additional analyses on the lot sample, or, in future, by analysing each sub-lot sep- arately. 6.1.2 Mass of contained gold mw =500t aL
15、= 10 g of gold/t 4 = (0,5)* = 0,25 Equations (5) and (8) give: 500x0,92x10 mM = 103 = 4.6 kg gold = 4,6* (0,000 000 2 + 0,000 000 12 + + 0,002 5) =0,0000042 +0,000002 5+ 0,052 9 = 0,053 Calculation of the standard deviation $, gives: SM = 0,23 kg gold Hence, at the 95 % confidence level, the mass of
16、 con- tained gold is: mM = 4,6 + 0,5 kg gold (i.e. f 11 % relative) The 95 % confidence range is 4.1 kg of gold to 5,l kg of gold. -,-,- IS0 13543:1996(E) 0 IS0 The precision of the measured gold content of the lot is the major contributor to the uncertainty in the mass of contained metal. Again thi
17、s can be reduced by car- rying out additional analyses on the lot sample, or, in future, by analysing each sub-lot separately. 6.2 Draft survey Assume a lot containing 30 % copper and 8 % mois- ture (m/m) has a wet mass of 25 000 t. If the wet mass is determined by draft survey with a relative preci
18、sion (I standard deviation) of 0,5 % and the cop- per and moisture content of the lot have been deter- mined with total precisions (I standard deviation) of 0,05 % copper and 0,l % moisture absolute (m/m) respectively, then: mw =25000t QL = 30 % copper 4 = (0,05)2 = 0,002 5 Hence, equations (3) and
19、(8) give: 25 000 x 0.92 x 30 mM = 100 = 6 900 t copper 4 = 6900* 15625 + 0.000001 : 0.0025 25 0002 0.922 302 = 6 9002 (0,000 025 + 0,000 001 2 + + 0,000 002 8) =I 190+57+133=1380 Calculation of the standard deviation sr, gives: sM = 37 t copper Hence, at the 95 % confidence level. the mass of con- t
20、ained copper metal is: mM = 6 900 + 74 t copper (i.e. -t 1 ,I % relative) The 95 % confidence range is 6 826 t of copper 6 974 t of copper. Clearly, the poor precision of mass determination the major contributor to the uncertainty in the mass contained metal. This is typical when the wet mass the lo
21、t is determined by draft survey. to is of of -,-,- IS0 13543:1996(E) 111 21 I31 Annex A (informative) Bibliography IS0 10258: 1994, Copper sulfide concentrates - Determination of copper content - Titrimetric methods. 141 IS0 10378: 1994, Copper sulfide concentrates - Determination of gold and silver
22、 contents - Fire assay gravimetric and atomic absorption spec- trometric method. 151 IS0 10469:1994, Copper sulfide concentrates - Determination of copper content - Electro- gravimetric method. 61 IS0 11441 :I 935, Lead sulfide concentrates - Determination of lead content - Back titration of EDTA af
23、ter precipitation of lead sulfate. IS0 12739:-21, Zinc sulfide concentrates - Determination of zinc content - Ion-exchange method. IS0 13291 :-*I, Zinc sulfide concentrates - Determination of zinc content - Solvent extrac- tion EDTA titrimetric method. 2) To be published 5 -,-,- IS0 13543:1996(E) IS0 ICS 73.060 Descriptors: metalliferous minerals, copper ores, lead ores, zinc ores, concentrates, copper Inorganic compounds, lead InorganIc compounds, zinc Inorganic compounds, sulphides, tests, determination, commercial mass, mass measurement, metals. Price based on 5 pages
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