Home The Enhancing Effect of Microwave Irradiation and Ultrasonic Wave on the Recovery of Zinc Sulfide Ores
Article Open Access

The Enhancing Effect of Microwave Irradiation and Ultrasonic Wave on the Recovery of Zinc Sulfide Ores

  • Kun Yang , Libo Zhang , Chao Lv , Shiwei Li EMAIL logo , Jinhui Peng , Aiyuan Ma , Weiheng Chen and Feng Xie
Published/Copyright: September 14, 2016
Download Article (PDF)
Become an author with De Gruyter Brill
Submit Manuscript Author Information
High Temperature Materials and Processes
From the journal High Temperature Materials and Processes Volume 36 Issue 6

Abstract

A novel process for the treatment of zinc sulfide ores is discussed in this paper, which consists of two procedures: microwave roasting pretreatment and synergistic chelation. What’s more, the reaction mechanism also has been studied. By comparing XRD patterns before and after roasting, it can be concluded that microwave truly alleviates the reaction energy, and adding Na2O2 avoids the emission of SO2. % recovery of zinc can reaches 72.47 % on conditions of adding Na2O2 25 %, microwave activating temperature 500 °C, holding time 10 min, leaching temperature 40 °C, ultrasonic wave power 1,800 W, leaching time 4.5 h and solid to liquid ratio 10:1 in ammonium chloride solution whose total ammonium concentrate is 7.5 mol/L (c(NH3)T=7.5 mol/L). The molar ratio of NH4Cl and NH3·H2O is 1:1 (c(NH4Cl): c(NH3·H2O)=1:1). The effect of ultrasonic wave power in this process is to shorten reaction time.

Keywords: zinc sulfide ores; microwave roasting; synergistic chelation; % recovery of zinc
PACS: 81.40.Wx

Introduction

Conventional zinc recovery process mainly comprise of three steps: roasting, leaching and electrowinning [1]. Though it has showed tremendous value to the development of zinc industry, its defects on environment protection, energy saving, and limiting raw materials, put serious restrictions on its application [2]. And the present wildly used hydrometallurgy processes also exist some disadvantages, such as low efficiency, complex operation, and high demand for apparatus, etc. [3, 4, 5,6,7, ,8, 9]. Therefore developing cost-effective meanwhile environment-friendly processes remains a major challenge.

Microwave is an emerging green technology, which is widely used in communication, radar, cellular phones, television and satellite [10]. Microwave energy is one kind of nonionizing electromagnetic radiation with wavelengths between 1 mm and 1 m (frequencies 300 MHz and 300 GHz). Unlike traditional electrical resistance heating in the form of heat conduction, microwave energy can be dissipated in the volume of material and transferred to inner energy, thus it has advantages of non-contact heating, energy transfer, rapid heating, selective heating, volumetric heating, quick start and stop, heating starting from interior of the material body, higher level of safety and automation [11, 12]. It can be expected enormous potential from application of microwave energy in the recovery of zinc sulfide ores.

The main objective of this present investigation is to design a mild and effective operation procedure to realize effective recovery of zinc sulfide ores. Through adopting various analytical techniques, such as XRD, TG-DTA and chemical composition, effect of microwave roasting and ultrasonic wave power, related reactions and potential of this process are researched.

Experimental

Materials and equipment

The zinc sulfide ores is mined from Lanping, Yunnan. Its main chemical compositions and zinc phase distributions are given in Tables 1 and 2. From the two tables, it can be known that this zinc sulfide ores belongs to high-iron and refine sphalerite [13], zinc content being 43.58 %. Zinc mainly exists in the form of ZnS, with zinc sulfide taking amount 98.81 %, and in contrast zinc oxides and fraklinite just sum up to 1.19 %. The sphalerite content in this zinc sulfide ores is deduced to 64.17 %. Figure 1 reveals the XRD pattern of this zinc sulfide ores and its analysis is following a XRF detection.

Table 1:

Main chemical compositions of zinc sulfide ores (mass fraction, %).

SZnTPbFeCaOAl2O3SiO2MgO
30.9243.5811.078.081.920.63＜0.50.14

  1. Note: ZnT, total Zn content.

Table 2:

Zinc phase distributions of zinc sulfide ores.

Zinc phaseZinc sulfideZnSiO3ZnCO3Franklinite et al.ZnT
Mass fraction/%43.060.290.140.09443.58
Distribution/%98.810.670.320.22100
Figure 1: XRD pattern of zinc sulfide ores.
Figure 1:

XRD pattern of zinc sulfide ores.

Main crystalline phases in this zinc sulfide ores include ZnS, PbS, and FeS2 (Figure 1). No detection of other zinc phases may be due to low content.

The microwave high temperature reactor is produced by the Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming University of Science and Technology, which uses 2,450 MHz magnetron tube as microwave generator. Its main part is a rectangular cavity characterized by low losses, simple structure and versatility. There are four magnetron tubes (1.5 kW) in this system, and uses waveguide transmission technology to feed the microwave into the cavity. Through real time regulating microwave currents, it can be achieved that the power output fluctuating continuously between 0~800 W.

Analytical techniques

All samples are characterized by X-ray diffractometry (XRD) and chemical composition analysis. And the precursor is determined by thermogravimetry-differential thermal analysis (TG-DTA). The X-ray power diffraction patterns are recorded on a Rigaku D/max-3B powder X-ray diffractometer using Cu Kα radiation (λ=1.5418 Å) and a graphite monochromator in the diffracted beam. A scan rate of 4 °·min−1 is applied to record a pattern in the 2θ range of 2θ=20–80°. Thermogravimetry-differential thermal analysis (TG-DTA) is carried out in a STA 449F3 simultaneous thermal analyzer from Netzsch in air flow and heating rate is 10 °C·min−1.

Chemicals and solvents are all analytical grade and used without any further purification. The working solutions are prepared using analytical grade chemicals and double-distilled water.

Experiment procedure

The process of synthetic chelation leaching of zinc sulfide ores can be divided into two steps: microwave roasting pretreatment and chelation leaching assisted by ultrasonic wave. The first step-microwave roasting pretreatment is operated as: weight Na2O2 and zinc sulfide ores in a mass ratio of 1:4, after blending, place them in the high temperature microwave reactor, roast at 500 °C, and hold 10 min. The second step proceeds as: leach the precursor with ammonium chloride solution (c(NH3)T=7.5 mol/L, c(NH3): c(NH4+)=1:1) in a solid/liquid ratio of 10:1, control ultrasonic wave power at 1,800 W, keep leaching temperature at 313 K, and add NaClO- one alkaline strong oxidant at every other 0.5 h. After leaching, separate liquid and solid, meanwhile recover value metal from leaching solution. The process diagram is shown in Figure 2.

Figure 2: Leaching diagram of zinc sulfide ores.
Figure 2:

Leaching diagram of zinc sulfide ores.

Phase transformation of zinc sulfide ores

To understand the process of microwave roasting pretreatment, conducting a TG-DTA analysis of zinc sulfide ores at first seems needed. The TG-DTA curve is shown in Figure 3.

Figure 3: TG-DTA curves of zinc sulfide ores.
Figure 3:

TG-DTA curves of zinc sulfide ores.

Results from Figure 3 are interpreted on the basis of published data [14, 15, 16,17, 18]. In the TG curve of zinc sulfide ores, four steps of mass losses are observed. The initial mass loss is observed between 430 °C and 564 °C, which is accompanied by the exothermic peak at around 532.8 °C in the corresponding DTA curve and it is ascribed to oxidation of FeS2. The second mass loss of zinc sulfide ores at 680–803 °C is interpreted as ZnS oxidization and in the DTA curve this period belongs to exothermal. The third mass loss between 803 °C and 900 °C shows an endothermal trend in the DTA curve, which is attributed to decomposition of ZnSO4. The last one, higher than 900 °C, corresponds to decomposition of PbSO4. Relate reactions are listed as following [19, 20, 21, 22, 23, 24, 25, 26, 27]:

(1)FeS2=FeS+S400−600degC
(2)FeS+2O2=FeSO4up to 450degC
(3)2FeSO4=Fe2O3+SO2+SO3450−880degC
(4)S+O2=SO2400−600degC
(5)FeS2+11/2O2=Fe2O3+4SO2550,625−725degC
(6)2FeS+7/2O2=Fe2O3+2SO2600degC
(7)FeS+3/2O2=FeO+SO2around 625degC
(8)2FeS+3.5+0.5xO2=Fe2O3−xSO4x+2−xSO2600−1200degC
(9)Fe2O3−xSO4x=Fe2O3+xSO3600−1200degC
(10)ZnS+3/2O2=ZnO+SO2 (500–1440, 640–830,740–1020, 850 °C)
(11)PbS+3/2O2=PbO+SO2527−827,840degC
(12)PbS+2O2=PbSO4527−827degC
(13)2PbSO4=PbSO4⋅PbO+SO3up to 866degC

Result and discussion

Phase transformation of zinc sulfide ores

After microwave heating pretreatment, XRD pattern of the precursor is revealed in Figure 4.

Figure 4: XRD of zinc sulfide ores after microwave heating pretreatment.
Figure 4:

XRD of zinc sulfide ores after microwave heating pretreatment.

As can be observed in Figure 4, phase compositions of this precursor become complicate. The initial phase FeS2 disappear, and diffraction peak intensity of PbS and ZnS weaken. NaFeO2 is the oxidation production of FeS2, and ZnO, ZnSiO3, Na2Zn(SO4)2, Na2(ZnSiO4) are obtained through ZnS oxidizing. It can be deduced from the phase changes that oxidation of FeS2 happens at a relatively low temperature. Under microwave irradiation, ZnS has been oxidized which is lower than traditional heating, at 530–625 °C [28]. The advantage of microwave heating alleviate the reaction energy thus shows. Even in microwave field, PbS need a higher oxidation energy (> 500 °C).

Making a comprehensive understanding of the TG-DTA curve, with temperature rising the oxidation process can be postulated as:

(14)Na2O2=Na2O+O
(15)2FeS2+Na2O2+2O=2NaFeO2+4S
(16)S+O=SO2abs
(17)ZnS+O=ZnO+SO2abs
(18)ZnS+4O=ZnSO4
(19)ZnSO4+Na2O+SO2+O=Na2ZnSO42
(20)ZnO+SiO2=ZnSiO3
(21)ZnSiO3+Na2O=Na2ZnSiO4

In the process of microwave roasting pretreatment, Na2O2 is heated, decomposing to Na2O and free oxygen. Generated elemental sulfur will react with free oxygen to form SO2. In low temperature operation, the rate to go into SO2 is very slow, which results in its absorption on the surface of minerals. The ZnSO4 is high value oxidation of ZnS. Existence of ZnSO4 will cause consuming of SO2 to producing Na2Zn(SO4)2. During oxidizing, no SO2 gas is detected. Thus it can be concluded that adding strong oxidation-Na2O2 in microwave field, the emission of SO2 can be avoided, which is environmental favor.

Percentage recovery of zinc sulfide ores

Leach the above precursor with ammonium chloride under mechanical agitation, leaching rate is acquired as shown in Figure 5.

From the below diagram, it can be known that coordination leaching process of zinc sulfide ores belongs to a gradual procedure. With adding NaClO at a limit intervals, Zn2+ can escape from zinc ores little by little and coordinate with NH4+ generating zinc ammines [29, 30, 31], at 4.5 h zinc leaching rate can reaching 72.47 %.

Figure 5: Zinc leaching rate of zinc sulfide ores.
Figure 5:

Zinc leaching rate of zinc sulfide ores.

Ultrasonic wave effect

In this experiment, we also investigate the enhancing effect of ultrasonic wave technology on the recovery of zinc sulfide ores, and results are shown in Figure 6.

Figure 6: The enhancing effect of ultrasonic wave on recovery of zinc sulfide ores.
Figure 6:

The enhancing effect of ultrasonic wave on recovery of zinc sulfide ores.

As can be seen from the above figure, in the initial stage, the enhancing effect of ultrasonic wave is not obvious, and there seems no difference between the two samples in one hour, while after that, the effect of ultrasonic wave begins to show, embodying in the figure, the leaching time dropping to reach the same leaching rate. What can be predicted, in the final stage, ultrasonic wave leaching shows no difference with the traditional mechanical agitation leaching. The effect of ultrasonic wave is to shorten the reaction time.

Conclusion

In this paper, we develop a new process to recover the zinc sulfide ores, which consists of two steps: microwave roasting pretreatment and coordination leaching. By analyzing the TG-DTA curve and comparing the XRD pattern before and after microwave heating, it can be concluded that microwave energy can truly alleviate the reaction energy, Na2O2 can directly oxidize zinc sulfide ores to Na2Zn(SO4)2, avoiding the emission of SO2. The % recovery of zinc can reach 72.47 %, under conditions of adding Na2O2 25 %, microwave roasting temperature 500 °C, holding time 10 min, leaching temperature 40 °C, ultrasonic wave power 1,800 W, leaching time 4.5 h and solid liquid ratio 10:1 in ammonium solution, whose total ammonium concentrate being 7.5 mol/L (c(NH3)T=7.5 mol/L) and the concentrate ratio of NH4Cl and NH3·H2O is 1:1 (c(NH4Cl): c(NH3·H2O)=1:1). The effect of ultrasonic wave power in this process is shortening reaction time.

Funding statement: This work was supported by National Program on Key Basic Research Project of China (973 Program, 2014CB643404) and the Scholarship Award for Excellent Doctoral Student granted by Ministry of Education, China (1319880206).

References

[1] A.M. Pandey, K.N. Gupta, and V.A. Alteker, Hydrometallurgy, 9 (1982), 57–68.10.1016/0304-386X(82)90053-6Search in Google Scholar

[2] G. Uçar, Hydrometallurgy, 95 (2009) 39–43.10.1016/j.hydromet.2008.04.008Search in Google Scholar

[3] P. Baláž and I. Ebert, Hydrometallurgy, 27 (1991) 141–150.10.1016/0304-386X(91)90062-QSearch in Google Scholar

[4] Z.M. Jin, G.W. Warren, H. Henein, Int. J. Mineral Process., 37 (1993) 223–238.10.1016/0301-7516(93)90028-9Search in Google Scholar

[5] S.K. Sahu, K.K. Sahu, B.D. Pandey, Metall. Mater. Trans. B, 37(2006) 541–549.10.1007/s11663-006-0037-4Search in Google Scholar

[6] T. Pecina, T. Franco, P. Castillo, E. Orrantia, Miner. Eng., 21 (2008) 23–30.Pecina et al., 2008; Sahu et al., 2006; Weisener et al., 2004.10.1016/j.mineng.2007.07.006Search in Google Scholar

[7] M.N. Babu, K.K. Sahu, and B.D. Pandey, Hydrometallurgy, 64 (2002) 119–129.10.1016/S0304-386X(02)00030-0Search in Google Scholar

[8] K. Svens, B. Kerstiens and M. Runkel, Erzmetall, 56 (2003) 94–103.Search in Google Scholar

[9] M. Lahtinen, H. Takala, K. Svens, A. Jarvinen and P. Talonen, Atmospheric zinc concentrate leaching of Outokumpu, Lead-zinc 05, Kyoto, Japan. 2005.Search in Google Scholar

[10] E.T. Thostenson and T.W. Chou, Composites Part A, 30 (1999) 1055–1071.10.1016/S1359-835X(99)00020-2Search in Google Scholar

[11] K.E. Haque, Int. J. Miner. Process., 57 (1999) 1–24.10.1016/S0301-7516(99)00009-5Search in Google Scholar

[12] M. Al-Harahsheh and S.W. Kingman, Hydrometallurgy, 73 (2004) 189–203.10.1016/j.hydromet.2003.10.006Search in Google Scholar

[13] H.F. Steger and L.E. Desjardins, Can. Mineral., 18 (1980) 365–372.Search in Google Scholar

[14] O.C. Kopp and P.F. Kerr, Am. Mineral., 43 (1958) 1079–1097.Search in Google Scholar

[15] R.B. Kemp, M.E. Brown and P.K. Gallagher, Handbook of Thermal Analysis and Calorimetry, New York: Elsevier, 1998.Search in Google Scholar

[16] J.M. Lambert Jr., G. Simkovich, P.L. Walker Jr., Metall. Mater. Trans. B, 29 (1998) 385–396.10.1007/s11663-998-0115-xSearch in Google Scholar

[17] R. Dimitrov, B. Boyanov, J. Therm. Anal. Calorim., 61 (2000) 181–189.10.1023/A:1010181112713Search in Google Scholar

[18] B. Boyanov, A. Peltekov and V. Petkova, Thermochim. Acta, 586 (2014) 9–16.10.1016/j.tca.2014.04.005Search in Google Scholar

[19] F. Paulik, J. Paulik and M. Arnold, J. Therm. Anal. Calorim., 25 (1982) 313–325. EM Bollin, Chalcogenides p. 20210.1007/BF01912956Search in Google Scholar

[20] E.M. Bollin, Chalcogenides, in RC Mackemzie (Ed.), Differential Thermal Analysis, Academic Press, London 1970, pp. 193–234.Search in Google Scholar

[21] T. Kennedy, B.T. Sturman, J. Therm. Anal. Calorim., 8 (1975) 329–337.10.1007/BF01904010Search in Google Scholar

[22] K.G. Denbigh and G.S.G. Beveridge, Trans. Inst. Chem. Eng. (London), 40 (1962) 23–34.Search in Google Scholar

[23] J. Gerlach and W. Stichel, Erzbergbau Metallhuettenw, 17 (1964) 427–433.Search in Google Scholar

[24] K. Natesan and W.O. Philbrook, Trans. Met. Soc. Aime, 245 (1969) 2243–2250.Search in Google Scholar

[25] Kellogg H H, Basu S K. Trans. Am. Inst. Mining Metall. Eng., 1960, 218(1): 70–81.Search in Google Scholar

[26] H.H. Kellogg, Trans. Metall. Soc. AIME, 230 (1964) 1622–1634.Search in Google Scholar

[27] A.C. Banerjee, P. Vasudevan and S. Sood, Thermochim. Acta, 92 (1985) 583–586.10.1016/0040-6031(85)85945-1Search in Google Scholar

[28] R. Dimitrov and B. Boyanov, Thermochim. Acta, 64(1983) 27–37.10.1016/0040-6031(83)80125-7Search in Google Scholar

[29] K.B. Yatsimirskii, Instability constants of complex compounds, Springer Science & Business Media, 2012. P.96.Search in Google Scholar

[30] I.M. Nelen and S.I. Sobol, Sb. Tr. Gos. Nauchno-Issled. Inst. Tsvftn. Metall., 1959, 15: 577–584.Search in Google Scholar

[31] H. Majima and E. Peters, Trans. Metall. Soc. AIME, 236 (1966) 1409–1413.Search in Google Scholar

Received: 2015-10-17
Accepted: 2016-4-20
Published Online: 2016-9-14
Published in Print: 2017-7-26

© 2017 Walter de Gruyter GmbH, Berlin/Boston

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Articles in the same Issue

  1. Frontmatter
  2. Research Articles
  3. Estimation for Iron Redox Equilibria in Multicomponent Slags
  4. The Effect of Multi-inclined Holes on the Creep Properties of Nickel-Based Superalloy
  5. Estimation of Various Properties of CaO–“FeO”–SiO2 System at 1,673 K by Mass Triangle Model
  6. The Enhancing Effect of Microwave Irradiation and Ultrasonic Wave on the Recovery of Zinc Sulfide Ores
  7. The Self-assembled Deposition on the Surface of Mono-crystalline Silicon Induced by High-Current Pulsed Electron Beam
  8. Numerical Model of Dephosphorization Reaction Kinetics in Top Blown Converter Coupled with Flow Field
  9. Morphological Evolution of Low-Grade Silica Fume at Elevated Temperature
  10. Discussion of Carbon Emissions for Charging Hot Metal in EAF Steelmaking Process
  11. Predictive Models for Modulus of Rupture and Modulus of Elasticity of Particleboard Manufactured in Different Pressing Conditions
  12. Photoluminescence Properties of Eu3+-activated Silicate Phosphors
  13. Synthesis, Acidity and Catalytic of the Rare Earth Ce Loaded on the Composite Pore Zeolite Catalyst for Hydrogenation Cracking
https://doi.org/10.1515/htmp-2015-0230
Keywords for this article
zinc sulfide ores; microwave roasting; synergistic chelation; % recovery of zinc
Creative Commons
BY-NC-ND 3.0

Articles in the same Issue

  1. Frontmatter
  2. Research Articles
  3. Estimation for Iron Redox Equilibria in Multicomponent Slags
  4. The Effect of Multi-inclined Holes on the Creep Properties of Nickel-Based Superalloy
  5. Estimation of Various Properties of CaO–“FeO”–SiO2 System at 1,673 K by Mass Triangle Model
  6. The Enhancing Effect of Microwave Irradiation and Ultrasonic Wave on the Recovery of Zinc Sulfide Ores
  7. The Self-assembled Deposition on the Surface of Mono-crystalline Silicon Induced by High-Current Pulsed Electron Beam
  8. Numerical Model of Dephosphorization Reaction Kinetics in Top Blown Converter Coupled with Flow Field
  9. Morphological Evolution of Low-Grade Silica Fume at Elevated Temperature
  10. Discussion of Carbon Emissions for Charging Hot Metal in EAF Steelmaking Process
  11. Predictive Models for Modulus of Rupture and Modulus of Elasticity of Particleboard Manufactured in Different Pressing Conditions
  12. Photoluminescence Properties of Eu3+-activated Silicate Phosphors
  13. Synthesis, Acidity and Catalytic of the Rare Earth Ce Loaded on the Composite Pore Zeolite Catalyst for Hydrogenation Cracking
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 10.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/htmp-2015-0230/html
Scroll to top button