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Huang Kaiguo
Professor, Department of Mineral Engineering, Central South University of Technology
Hui nickel matte in copper ore (Cu 2 S), sulfur flotation separation hexagonal nickel (Ni 3 S 2) is a process 1940s was developed. The process still uses traditional xanthate collectors . Due to the versatility of such collectors for the flotation of sulfide minerals, the lack of selectivity results in a higher mutual content of copper concentrates and nickel concentrates. In order to improve the selectivity of flotation separation and reduce its mutual content, this paper studies the capture performance of urethane esters on Cu 2 S and Ni 3 S 2 minerals from the search for selective collectors. The conditions for the effective separation of copper and nickel in the collector have achieved significant results.
1. Samples and research methods
Jinchuan Nonferrous Metals Company samples taken from the second smelter. The high-alloy nickel contains 46.82% of nickel, 24.62% of copper, 19.82% of sulfur and 4.37% of iron . The main minerals are hexagonal sulfur-nickel ore, chalcopyrite and alloy. The single mineral of the copper ore and the hexagonal sulphur nickel ore is a copper concentrate and a nickel concentrate which are separated by high-ice nickel flotation, and the surface material is cleaned by mechanical scrubbing, acetone extraction and hydrochloric acid, respectively, and the sample is prepared in a desiccator for storage in a desiccator. use. Both single minerals have a purity of over 92%.
The single mineral flotation test was carried out in a 40 ml hanging trough flotation machine, each time using 2 g of sample, ultrasonic pretreatment for 5 min, adding, adjusting, and flotation for 5 min in the order of adjusting agent, collector, and foaming agent. The XPS image was taken on an XSAM-800 multifunction surface analyzer.
High-ice nickel flotation separation test is to crush large pieces of high-ice nickel to -3mm, mix and shrink into 200g per package, grind to 91%-74μm, screen out its +74μm part for alloy products, - 74μm part in 0.5L single groove The flotation separation test was carried out in a flotation machine. The flotation separation process, the open circuit is a rough selection, one sweep, and three selections; in the closed circuit test, the sweep concentrate is returned to the grinding, and the selected mines are returned in sequence.
Second, the test results and discussion
(1) Single mineral flotation test
Figure 1 shows the effect of pulp pH on the flotation of Cu 2 S and Ni 3 S 2 when butyl xanthate is used as a collector. As can be seen from the figure, the yellow drug collector has a strong collection property for Cu 2 S at pH <11.5, and has a strong collection property for Ni 3 S 2 , which reflects the traditional collection performance of xanthate, but The selectivity is poor, and it also indicates that the butyl xanthate is used as a collector, and the separation of Cu 2 S and Ni 3 S 2 must be achieved at a high pH.
Figure 2 shows the effect of pH on the floatability of minerals when thiourethane is used as a collector. Figure 2 shows that the difference in floatability between Cu 2 S and Ni 3 S 2 is more obvious with thiourethane as the collector. The floatability of the two minerals is quite different in the wide range of pH from 10.5 to 12.5. As can be seen from the comparison with Figure 1, the urethane has a slightly lower ability to capture than the butyl xanthate, but the selectivity is significantly higher than that of the butyl xanthate.
(2) High-ice nickel flotation separation test
On the basis of the single mineral test, butyl xanthate and thiourethane were used as collectors respectively, and the Jinchuan high-ice nickel flotation separation test was carried out. The open circuit test results are shown in Table 1. The combination of ethyl xanthate and thiourethane used closed-circuit test. The results are shown in Table 2. Table 1 shows that copper content in copper concentrates and nickel concentrates in copper concentrates with thiourethane as the collector are significantly lower than those in the case of butyl xanthate. The closed-circuit test results in Table 2 also show that the two concentrates separated by high-ice nickel flotation using thiourethane and ethyl xanthate are also low in mutual content.
Table 1 High-ice nickel flotation separation open circuit test results (%)
Collector Species | Copper concentrate grade | Nickel concentrate grade | Two concentrates The sum of each other | ||
Cu | Ni | Cu | Ni | ||
Butyl xanthate | 64.76 | 5.23 | 2.44 | 67.22 | 7.67 |
Thiazolyl ester | 67.87 | 2.15 | 2.24 | 68.27 | 4.39 |
Table 2 Closed-circuit test results of high-ice nickel flotation separation (%)
product | Yield | grade | Recovery rate | Two concentrates The sum of each other | ||
Ni | Cu | Ni | Cu | |||
Alloy | 13.50 | 65.59 | 14.72 | 18.91 | 8.07 | 6.47 |
Nickel concentrate | 55.83 | 66.24 | 3.26 | 78.99 | 7.39 | |
Copper concentrate | 30.67 | 3.21 | 67.86 | 2.10 | 84.54 | |
High ice nickel | 100. 0 | 46. ​​82 | 24. 62 | 100. 0 | 100.0 | |
Discussion on the capture performance of thiourethane
S S
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The structure of the thiourethane collector is R-O-C-NHR', and its polar group is -O-C-NH-(1). The pole of yellow medicine
S
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The base is -O-C-S-(2). The difference between the two types of collectors in the structural formula is that (2) the electronegativity of the medium-S-group (X 5 2.5) is smaller than the electronegativity (X N 3.0) of the N-group of (1). The negative induction effect of thiourethane is higher than that of xanthate. The difference between the non-polar groups is that (1) there is an R' group in the nitrogen, so the positive inducing effect of the thiourethane is stronger than that of the xanthate. In combination, the bonding ability of the thiourethane-bonded sulfur atom and the nitrogen atom is stronger than that of the xanthate and has a good selectivity.
The strong selective capture of copper minerals by thiourethane can be explained by the calculation results of group electronegativity, collector polar base section width dg and flotation agent performance molecular orbital method. Taking the calculation of the section width dg as an example, the reasons why the thiourethane selectivity is higher than that of the xanthate are as follows:
Flotation agent and mineral action is a surface process, using the atom's radius, covalent radius and bond angle data, according to
S
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The molecular structure of the agent estimates the cross-sectional width dg of the polar group of the flotation reagent. Calculated, d RR ' = 8.7 in thiourethane R-O-C-NHR' And the yellow drug dg=6.8 . According to the rule that the larger the section width, the better the selectivity of the agent, the selectivity of the urethane collector is better than that of the xanthate.
The simple verification test and the XPS energy spectrum further illustrate that the adsorption between the thiourethane and the chalcopyrite is chemisorption, and the adsorption between the Ni 3 S 2 and the Ni 3 S 2 is a reversible physical adsorption. The use of sulphur ammonia and Cu 2 S, Ni 3 S 2 respectively, the foam product obtained by flotation is washed several times with distilled water, and then subjected to a single mineral flotation test, without adding a collector, Cu 2 S still There is a good floating rate, and the floating rate of Ni 3 S 2 has been significantly reduced. It indicates that the adsorption of thiourethane on the surface of Ni 3 S 2 is very unstable. It can be completely removed from the surface by mechanical stirring and is reversible physical adsorption. The thiourethane is firmly adhered on the surface of Cu 2 S, although it is still clean after washing. A good floating rate indicates that the adsorption is irreversible chemical adsorption.
The XPS energy spectrum further reveals the above phenomenon. In Fig. 3, a and b are the characteristic peak spectrums of copper of Cu 2 S and the characteristic peak spectrum of copper after Cu2S and thiourethane and after several cleanings. Comparing the two spectra, it can be found that the electron binding energy of Cu 2P3/2 before Cu2S and thiamin is 932.2 eV. After the action of thiourethane, the electron binding energy of Cu 2P3/2 is shifted to the positive direction to 932.8 eV. The difference between the two is 0.6eV, indicating that chemical adsorption (or chemical reaction) occurs between Cu 2 S and thiourethane, and the effect of Cu 2 S and sulphur ammonia AN can also be seen from the corresponding total spectrum (not attached). The difference between before and after is that the nitrogen element peak appears on the total spectrum after the action of Cu 2 S and thiourethane. Similarly, FIG. 3 c, d are the characteristic peaks of nickel Ni 3 S 2 and the spectrum of Ni 3 S 2 and thiourethane effect after cleaning and after several characteristic peaks of nickel spectrum. Comparing the two spectra, it can be found that the electron binding energy of Ni 2p3/2 before Ni 3 S 2 and thiourethane is 855 eV. After the action of thiourethane, the electron binding energy of Ni 2p3/2 is still 855 eV, and there is no change between the two. It shows that there is no chemisorption between Ni 3 S 2 and thiourethane, and the same conclusion is drawn from the total spectrum.
The adsorption chemistry of thiourethane on Cu 2 S indicates that it has a high activation energy (94 kJ/g molecule), while the activation energy on Ni 3 S 2 is still 21.7 kJ/g. The pro-solid atoms in the thiourethane are sulfur atoms and nitrogen atoms. Since the affinity between the two is strong, the copper ions are chelated with such agents. XPS analysis showed that thiourethane adsorbed on the surface of Cu 2 S and chemical reaction occurred to form S and N tetracyclic chelates. The structural formula of the compound is:
Since sulphur ammonia is chemisorbed on the surface of Cu 2 S, and the adsorption on the surface of Ni 3 S 2 is physical adsorption, thiourethane can selectively float and separate Cu 2 S and Ni 3 S 2 in high ice nickel, single mineral. Both the test and the actual high ice nickel flotation separation test results are a good confirmation of this.
Fourth, the conclusion
(1) Compared with xanthate, thiourethane has better selective collection performance, urethane ester has strong ability to capture chelates, and the ability to capture hexagonal sulphur nickel ore is weak. In high-ice nickel flotation separation, whether it is thiourethane alone or in combination with xanthate, it is beneficial to high-ice nickel flotation separation and reduce the mutual content of copper concentrate and nickel concentrate.
(2) It is further proved by the structure, performance analysis and XPS measurement of thiourethane that the surface of thiourethane and chalcopyrite is strong and belongs to chemical adsorption; it has weak effect on the surface of hexagonal sulphur nickel ore and is reversible physics. Adsorption.
references
1. Wang Dianzuo. The principle and application of flotation agent, Beijing: Metallurgical Industry Press.1982
2. BAЩÑрδаков et al. Improve the flotation efficiency with sulfur carbamate, foreign mining and metallurgy, 1985, No.5
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