GB/T 14353.18-2014Methods for chemical analysis of copper ores, lead ores and zinc ores - Part 18: Determination of copper content, lead content, zinc content, cobalt content and nickel content (English PDF)

1 Scope

Warning: persons using this part shall have practical experience of regular laboratory work. This part does not point out all the possible safety problems. It is the responsibility of the user to take suitable safety and health measures and to make sure that the conditions laid down by the relevant national regulations are met.

This part of GB/T 14353 lays down the method for the simultaneous determination of copper, lead, zinc, cobalt and nickel in copper ores, lead ores and zinc ores by inductively coupled plasma optical emission spectrometry.

This part applies to the simultaneous determination by inductively coupled plasma optical emission spectrometry of copper, lead, zinc, cobalt and nickel in copper ores, lead ores and zinc ores.

Determination range: 0.002 % to 8.5 % of copper, 0.01 % to 5 % of lead, 0.005 % to 3 % of zinc, 0.001 5 % to 0.5 % of cobalt, 0.003 % to 0.5 % of nickel.

Detection limits of the method: copper 0.000 66 %, lead 0.003 2 %, zinc 0.001 7 %, cobalt 0.000 47 %, nickel 0.001 0 %.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition, including all amendments, applies.

GB/T 6682 Water for analytical laboratory use - Specification and test methods

GB/T 14505 Methods for chemical analysis of rocks and ores - General rules and regulations

3 Principle

After the test portion has been decomposed with hydrochloric acid, nitric acid, hydrofluoric acid and perchloric acid, the test solution, in a 20 % nitric acid medium containing 3 % hydrochloric acid, is introduced into a high-temperature plasma torch, where the elements to be determined are excited into ions and atoms and emit the characteristic spectral lines of the elements contained. The emission spectral intensity of the ions and atoms of each element is measured at the prescribed wavelength; the emission spectral intensity is proportional to the concentration of the element measured, and the content of the element measured is calculated by the computer built into the instrument using the calibration curve method.

4 Reagents

Unless otherwise stated, analytically pure reagents and water for analytical laboratory use complying with GB/T 6682 are used throughout the analysis.

4.1 Nitric acid (density 1.42 g/mL).

4.2 Hydrofluoric acid (density 1.13 g/mL). Warning: hydrofluoric acid is toxic and strongly corrosive; corrosion-resistant gloves shall be worn during the operation and contact with the skin avoided.

4.3 Hydrochloric acid (density 1.19 g/mL).

4.4 Perchloric acid (density 1.68 g/mL). Warning: explosive, handle with care.

4.5 Mixed acid (nitric acid plus hydrochloric acid = 4+1).

4.6 Nitric acid (1+9).

4.7.1 Copper standard solutions. a) Copper stock standard solution, mass concentration of copper 1.00 mg/mL: 0.500 0 g of copper metal of purity greater than 99.99 % is weighed into a 250 mL beaker, covered with a watch glass, 10 mL of nitric acid (1+1) is added down the wall of the beaker and the solution warmed gently; after dissolution is complete 10 mL of sulfuric acid (1+1) is added, the solution is evaporated until white fumes of sulfur trioxide appear, taken off and cooled, the copper salt dissolved in water, the watch glass washed with water, and the solution transferred after cooling into a 500 mL volumetric flask, diluted to the mark with water and mixed. b) Copper standard solution, mass concentration of copper 100.0 µg/mL: 25.00 mL of the copper stock standard solution [4.7.1a)] is taken into a 250 mL volumetric flask, diluted to the mark with hydrochloric acid (5+95) and mixed. c) Copper standard solution, mass concentration of copper 20.0 µg/mL: 50.00 mL of the copper standard solution [4.7.1b)] is taken into a 250 mL volumetric flask, diluted to the mark with hydrochloric acid (5+95) and mixed.

4.7.2 Lead standard solutions. a) Lead stock standard solution, mass concentration of lead 1.00 mg/mL: 1.000 0 g of lead metal of purity greater than 99.99 % is weighed into a 250 mL beaker, covered with a watch glass, 10 mL of nitric acid (1+1) is added down the wall of the beaker and dissolved with heating; the watch glass is washed with a little water and the solution transferred into a 1 000 mL volumetric flask, diluted to the mark with water and mixed. b) Lead standard solution, mass concentration of lead 20.0 µg/mL: 20.00 mL of the lead stock standard solution [4.7.2a)] is taken into a 1 000 mL volumetric flask, diluted to the mark with water and mixed.

4.7.3 Zinc standard solutions. a) Zinc stock standard solution, mass concentration of zinc 1.00 mg/mL: 1.000 0 g of zinc metal of purity greater than 99.99 % is weighed into a 250 mL beaker, covered with a watch glass, 10 mL of hydrochloric acid (1+1) is added down the wall of the beaker and the mixture left to dissolve by itself, more acid being added if there is not enough; after dissolution is complete the watch glass is washed with water and the solution transferred into a 1 000 mL volumetric flask, diluted to the mark with water and mixed. b) Zinc standard solution, mass concentration of zinc 20.0 µg/mL: 20.00 mL of the zinc stock standard solution [4.7.3a)] is taken into a 1 000 mL volumetric flask, diluted to the mark with water and mixed.

4.7.4 Cobalt standard solutions. a) Cobalt stock standard solution, mass concentration of cobalt 100 µg/mL: 0.100 0 g of cobalt metal of purity greater than 99.99 % is weighed into a 100 mL beaker, covered with a watch glass, 20 mL of nitric acid (1+1) is added down the wall of the beaker, dissolved with heating and evaporated to dryness at low temperature; the watch glass is rinsed with a little water, 5 mL of hydrochloric acid (4.3) is added and the solution evaporated to dryness at low temperature, and the operation is repeated once. 10 mL of hydrochloric acid (4.3) is added to dissolve the cobalt salt, the solution is cooled, transferred with water into a 1 000 mL volumetric flask, diluted to the mark and mixed, and kept for use. b) Cobalt standard solution, mass concentration of cobalt 10.0 µg/mL: 50.00 mL of the cobalt stock standard solution [4.7.4a)] is transferred into a 500 mL volumetric flask, diluted to the mark with hydrochloric acid (1+99) and mixed.

4.7.5 Nickel standard solutions. a) Nickel stock standard solution, mass concentration of nickel 100 µg/mL: 0.100 0 g of nickel metal of purity greater than 99.99 % is weighed into a 100 mL beaker, covered with a watch glass, 20 mL of nitric acid (1+1) is added down the wall of the beaker, dissolved with heating and evaporated to dryness at low temperature; the watch glass is rinsed with a little water, 5 mL of hydrochloric acid (4.3) is added and the solution evaporated to dryness at low temperature, and the operation is repeated once. A further 10 mL of hydrochloric acid (4.3) is added to dissolve the nickel salt, the solution is cooled, transferred with water into a 1 000 mL volumetric flask, diluted to the mark and mixed. b) Nickel standard solution, mass concentration of nickel 10.0 µg/mL: 50.00 mL of the nickel stock standard solution [4.7.5a)] is transferred into a 500 mL volumetric flask, diluted to the mark with hydrochloric acid solution (1+99) and mixed.

5 Apparatus

5.1 Inductively coupled plasma optical emission spectrometer.

5.2 Analytical balance: class three, sensitivity 0.1 mg.

6 Test sample

6.1 The particle size of the test sample prepared according to the relevant provisions of GB/T 14505 shall be less than 97 µm.

6.2 The test sample is dried in an oven at 60 °C to 80 °C for 2 h to 4 h and cooled to room temperature in a desiccator before use.

7 Analytical procedure

7.1 According to the content of the element to be determined in the test sample, the test portion is weighed as given in Table 1 to the nearest 0.1 mg.

Table 1, test portion mass, has seven columns: the element, and then two sets of three columns giving the content in units of ten to the power minus two, the mass of test portion in grams and the make-up volume in millilitres. For Co the first set is 0.001 5 to 0.1 with 0.25 g made up to 25.00 mL and the second set is 0.1 to 0.5 with 0.1 g made up to 100.0 mL; for Cu, 0.002 to 0.1 with 0.25 g to 25.00 mL and 0.1 to 8 with 0.1 g to 100.0 mL; for Ni, 0.003 to 0.1 with 0.25 g to 25.00 mL and 0.1 to 0.5 with 0.1 g to 100.0 mL; for Pb, 0.01 to 0.1 with 0.25 g to 25.00 mL and 0.1 to 5 with 0.1 g to 100.0 mL; for Zn, 0.005 to 0.1 with 0.25 g to 25.00 mL and 0.1 to 3 with 0.1 g to 100.0 mL.

The note below Table 1 states that, for one and the same sample, when the mass fractions of copper, lead, zinc, cobalt and nickel differ by more than four orders of magnitude, 0.25 g and 0.1 g of the sample may be weighed separately, decomposed and made up into two test solutions of 25.00 mL and 100 mL and determined at the same time; the result obtained with the suitable test portion mass is chosen according to the content range of the element measured.

7.2 Blank test: a duplicate blank test is carried out along with the test portion; the reagents used shall be taken from the same reagent bottle and added in the same amounts.

7.3 Verification test: a certified reference material of the same ore type and of similar content is analysed along with the test portion.

7.4.1 The test portion (7.1) is placed in a 100 mL polytetrafluoroethylene beaker and wetted with a suitable amount of water; 10 mL of hydrochloric acid (4.3) is added and the mixture heated almost to dryness; 10 mL of nitric acid (4.1), 10 mL of hydrofluoric acid (4.2) and 2 mL of perchloric acid (4.4) are added, and the beaker is heated on a hot plate until the test portion is completely dissolved and then evaporated almost to dryness.

7.4.2 After slight cooling, 4 mL of mixed acid (4.5) is added and the salts dissolved with gentle heating until the solution is clear; the solution is cooled and transferred into a 25 mL colorimetric tube or a 100 mL volumetric flask, and for the test solution transferred into the 100 mL volumetric flask a further 10 mL of mixed acid (4.5) is added. The solution is diluted to the mark with nitric acid (4.6), mixed, left to stand overnight and is then ready for measurement on the instrument.

7.5 The single-element standard solutions [4.7.1c), 4.7.2b), 4.7.3b), 4.7.4b), 4.7.5b)] are taken separately and diluted to prepare the mixed standards required: BLANK, STD1, STD2, STD3, STD4 and STD5. The mixed calibration solution series is given in Table 2.

Table 2, mixed calibration solution series, has six columns: the standard series and the mass concentration in mg/L of copper, lead, zinc, cobalt and nickel. BLANK is 0 for all five elements. STD1 is 0.2 for all five. STD2 is 2.0 for all five. STD3 is 10.0 for copper, 20.0 for lead and 10.0 for zinc, cobalt and nickel. STD4 is 50.0 for copper, 200.0 for lead and 50.0 for zinc, cobalt and nickel. STD5 is 200.0 for copper, 1 000.0 for lead, 300.0 for zinc and 100.0 for cobalt and for nickel.

7.6 With reference to the working conditions of the instrument (see Annex A), after the instrument has been ignited and has become stable, the calibration working solutions and the test solutions are introduced one after the other into the high-temperature plasma flame and each element is determined; the blank test solution and the verification test solution are determined at the same time. The data are calculated and saved by the dedicated software of the computer.

7.7 The calibration solution series is chosen according to the content range; standardisation with high and low two-point calibration solutions is used; the determination is carried out at the same time following the procedure of 7.6, the data are stored in the computer and the calibration working curve is drawn automatically by the dedicated software of the computer.

8 Calculation of results

The contents of copper, lead, zinc, cobalt and nickel are expressed as the mass fraction w(Cu, Pb, Zn, Co, Ni), the value being given in %, and are calculated by formula (1). In the formula, the Greek letter rho with subscript 1 is the content of the element in the test solution read from the calibration curve, in micrograms per millilitre (µg/mL); the Greek letter rho with subscript 0 is the content of the element in the blank solution (7.2) read from the calibration curve, in micrograms per millilitre (µg/mL); V is the total volume of the test solution, in millilitres (mL); m is the mass of the test portion, in grams (g).

The standard also prints, in the form of digit patterns, the way in which the calculated result is to be expressed for each content level; the exact number of digits shown in those patterns could not be read with certainty from the scan and has not been reproduced here.

9 Precision

Under repeatability conditions, the absolute difference between the measured values of two independent test results obtained within the level range given in Table 3 shall not exceed the repeatability limit r, and the cases in which the repeatability limit r is exceeded shall not be more than 5 %. The repeatability limit r is calculated from the equations listed in Table 3.

Under reproducibility conditions, the absolute difference between the measured values of two independent test results obtained within the level range given in Table 3 shall not exceed the reproducibility limit R, and the cases in which the reproducibility limit R is exceeded shall not be more than 5 %. The reproducibility limit R is calculated from the equations listed in Table 3.

The statistical data obtained from the inter-laboratory test results are given for reference in Annex B. Table 3 itself falls beyond the pages available and its level ranges and equations have not been read.

Position within the GB/T 14353 series

GB/T 14353 Methods for chemical analysis of copper ores, lead ores and zinc ores is divided into eighteen parts: Part 1, determination of copper; Part 2, determination of lead; Part 3, determination of zinc; Part 4, determination of cadmium; Part 5, determination of nickel; Part 6, determination of cobalt; Part 7, determination of arsenic; Part 8, determination of bismuth; Part 9, determination of molybdenum; Part 10, determination of tungsten; Part 11, determination of silver; Part 12, determination of sulfur; Part 13, determination of gallium, indium, thallium, tungsten and molybdenum; Part 14, determination of germanium; Part 15, determination of selenium; Part 16, determination of tellurium; Part 17, determination of thallium; Part 18, determination of copper, lead, zinc, cobalt and nickel.

This part is the eighteenth part of GB/T 14353. It was drafted according to the rules given in GB/T 1.1-2009, was proposed by the Ministry of Land and Resources of the People's Republic of China and is under the jurisdiction of the National Technical Committee on Land and Resources of Standardization Administration of China (SAC/TC 93). The drafting organization is the Shaanxi Institute of Geology and Mineral Resources Experiment and Research.