J. Cent. South Univ. (2021) 28: 1333-1341

DOI: https://doi.org/10.1007/s11771-021-4706-x

Effect of particle size on bioleaching of low-grade nickel ore in a column reactor

WANG Xin(王欣), YANG Hong-ying(杨洪英), ZHANG Qin(张勤),JIN Zhe-nan(金哲男), TONG Lin-lin(佟琳琳), SU Ying-bin(苏迎彬)

School of Metallurgy, Northeastern University, Shenyang 110819, China

Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2021

Abstract: Biological column leaching of Ni from low-grade Ni ore was studied, and the effects of ore particle size on leaching rate were investigated. The Ni ore with an average Ni content of 0.23% was crushed into four different particle size fractions: >10 mm, 5-10 mm, 2-5 mm and <2 mm. The main strain components at the genus level were acidithiobacillus (53.11%), leptospirillum (43.52%), and acidiphilium (3.37%). The leaching tests were carried out at pH 2.0 and ~23°C. The Ni leaching rates from ores with particle sizes >10 mm (bioleaching), 5–10 mm (acid leaching), 5–10 mm (bioleaching), and 2–5 mm (bioleaching) were 23.76%, 22.15%, 32.42% and 54.17%, respectively, after 180 d of bioleaching. The ore particle size changed after leaching, compared with the original ore size, the proportion of the same size of 2-5 mm ore decreased to 44.64%. Ore with particle size of 2–5 mm was most suitable for column bioleaching, and effective Ni extraction was achieved with appropriate control of ore granularity.

Key words: bacteria; particle size; column-leaching; nickel; bioleaching

Cite this article as: WANG Xin, YANG Hong-ying, ZHANG Qin, JIN Zhe-nan, TONG Lin-lin, SU Ying-bin. Effect of particle size on bioleaching of low-grade nickel ore in a column reactor [J]. Journal of Central South University, 2021, 28(5): 1333-1341. DOI: https://doi.org/10.1007/s11771-021-4706-x.

1 Introduction

Ni is an important strategic reserve resource widely used in metallurgy, chemical industry, and other fields. For example, with the global promotion of new energy electric vehicles, the demand for Ni has greatly increased as a raw material for preparing batteries [1]. In recent years, reserves of high-grade and easily selected Ni ores have been decreasing with continuous mining. Low-grade Ni ores have long been accumulated or abandoned, not only occupying land and polluting the environment but also wasting scarce resources [2].

The government of China has increased its oversite of solid waste management and efforts to protect the environment near mines, prompting companies to consider making full use of or otherwise handling such minerals. Whether because of economic considerations or a company’s production process, conventional methods are no longer suitable for processing low-grade Ni ore. Attention is therefore shifting to effective biological leaching technology, which has the advantages of low resource consumption, environmental friendliness, and low costs [3-6].

In recent decades, biometallurgy has been widely used in the metallurgical industry abroad and is still in the promotion stage in China [7, 8]. Research into biometallurgy and related areas has recently been expanding [9-11]. For example, bacteria have been used to recycle valuable metals from electronic waste, and the bacterial erosion of sulfide ores such as those of Ni, Cu, and Zn has been reported [12-15].

Studies have shown that microbial survival conditions are limited by the local environment. The main factors affecting biological heap leaching are mineral particle size, pH, and temperature [16-19]. The suitable pH range for acidophilic bacteria is known to be 1.5-3.0 [20]. However, the outdoor heap immersion temperature is not easy to control. Particle size has thus emerged as an important and controllable factor that determines the permeability of the ore heap in bioleaching [21-23]. After mineral corrosion, the residue settles, leading to reduced permeability of the ore heap and affecting the leaching rate. In industrial production, there are few studies on biological heap leaching, and the bacterial leaching data will be different from that of acid leaching, which is suitable for enterprise reference.

This paper aims to study the effect of microorganisms in column leaching and evaluate the feasibility of bioleaching, which is of great significance to industrial production. In the present study, localized bacteria were used to leach Ni sulfide ore in a column reactor and the effects of bacteria and particle size on the Ni leaching process were investigated. The change in particle size of the leach was studied to deduce the best conditions, and the results provide a basis for an enterprise heap leaching design.

2 Materials and methods

Low-grade Ni ores were obtained from Jilin Province, China. The samples for experiments were broken with a jaw crusher. Four particle size ranges (>10 mm, 5-10 mm, 2-5 mm and <2 mm) were selected for the biological column leaching. The elemental contents of different size fractions are shown in Table 1. The average Fe content was 7.5%, and the content of S was greater than 0.8%; both of these elements are essential nutrients for bacterial growth.

Since the composition of each grain was similar, 2-5 mm ore was used for X-ray powder diffraction. XRD analysis (Bruker-D8 Discover, Bruker, Mannheim, Germany) of the samples (Figure 1) shows that the main minerals were silicon oxide,chlorite, and pyrite. The samples were scanned over the range 5°≤2θ≤90°.

Table1 Chemical composition of ore sample (mass fraction, %)

Figure 1 XRD patterns of the raw material

The experimental bacteria were obtained from a mine crater where acid sewage was retained in Jilin Province, China. The bacteria was continuously domesticated in 9K medium that contained (NH₄)₂SO₄ (3.0 g/L), MgSO₄·7H₂O (0.5 g/L),KCl (0.1 g/L), Ca(NO₃)₂·4H₂O (0.01 g/L), K₂HPO₄ (0.5 g/L), and FeSO₄·7H₂O (44.78 g/L), and was maintained at pH 2.0 by the addition of concentrated sulfuric acid. The culture was incubated in flasks on a full temperature oscillator (HZQ-QX) at 150 r/min and 30°C.

To know the strains used in the experiment, the 16S rRNA sequence analysis technique was used to analyze the bacterial fluid, which was a mixed strain; as shown in Figure 2, the main components of the strains at the genus taxon level were acidithiobacillus, leptospirillum, and acidiphilium, which were present at contents of 53.11%, 43.52% and 3.37%, respectively.

A schematic diagram of mineral leaching column is shown in Figure 3. The dimensions of the column-type leaching unit were d15 cm×100 cm. A layer of canvas was placed at the bottom of each column to prevent solids from clogging the outlet. Four different ore samples were loaded into the columns (the 5-10 mm fraction was used in two columns), and an acid immersion comparison experiment using the particles was designed. The columns were loaded with >10 mm (bioleaching), 5-10 mm (acid leaching), 5-10 mm (bioleaching), 2-5 mm (bioleaching), and <2 mm (bioleaching) ore size fractions. These columns are hereafter referred to as columns 1-5, respectively. The column-leaching experiments were conducted at room temperature. Each column was loaded with 2 kg of ore sample, and the inoculation ratio was 1:10. The pH of the leaching solution was 2.0, and the solid/liquid ratio was 1:1.25. The leachate was circulated twice per day at a flow rate of 30 mL/min. Deionized water was added to compensate for evaporated water on a regular basis, and the pH of the solution was adjusted using a 1:1 concentrated sulfuric acid/water solution. Column 2 was used as a contrast experiment conducted under the same conditions as the bacterial leaching experiments except that concentrated sulfuric acid was used as a reagent and the column was not inoculated with the bacteria.

Figure 2 Fractions of strains at classification level of taxon

Figure 3 A schematic diagram of mineral leaching column

The pH was measured using a pH meter (PHS-3E). The redox potential of the solutions was measured using a Pt electrode in conjunction with a saturated Ag/AgCl reference electrode. The elemental contents of the leachate and the ore samples were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES; America Baird Co. PS-6). The leaching-rate efficiency W was calculated as:

                       (1)

where m₀ is the initial ore mass; G₀ is the initial ore grade; C is the ion concentration; V is the volume of the experimental liquid.

3 Results and discussion

3.1 Effect of particle size on variation of E_h and Fe²⁺ ion concentration

The variations in the leaching potential E_h and the Fe²⁺ ion concentration during bacterial leaching and acid leaching in columns with different particle sizes are shown in Figures 4 and 5, respectively. The redox potential of the solution is mainly determined by the concentration of Fe²⁺ ions and the concentration ratio between Fe³⁺ ions and Fe²⁺ ions. The bacteria were inoculated using a column immersion test, and the redox potential was maintained at 450-500 mV. As the leaching progressed, the redox potential continuously decreased. However, when the potential reached a minimum of 420 mV at 12 d, the corresponding Fe²⁺ ion concentration reached its maximum value of 8.2 g/L.

Figure 4 Redox potential for ore samples with different particle sizes

Figure 5 Fe²⁺ concentration of ore samples with different particle sizes

When the bacteria began to grow in logarithmic phase, the E_h increased sharply and reached a peak value of 750 mV in 19 d; by contrast, the concentration of Fe²⁺ ions decreased sharply, eventually reaching a concentration of 0 g/L, because during the growth of bacteria Fe²⁺ ions were oxidized to Fe³⁺ ions and the oxidizing substances in the solution continued to increase, causing the redox potential to increase accordingly. The redox potential of conventional acid leaching is typically between 390 and 450 mV.

The changes in the Fe²⁺ ion concentration show that, at the same particle size of 5-10 mm, the concentration of Fe²⁺ ions in the solution containing bacteria was lower than that in the acid leaching solution, indicating that some Fe²⁺ ions were oxidized and that the bacteria played a role in the early stage of the leaching process. The particle size exerted less effect on the E_h of the leaching solution than on the Fe²⁺ concentration.

3.2 Effect of particle size on Ni leaching and SEM characterization

The effects of different particle sizes on bacterial leaching and acid leaching were characterized on the basis of the extent of Ni leaching. The results are shown in Figure 6. The effect of bacterial leaching was substantially better than that of acid leaching under the same particle size and leaching conditions. On days 15 through 30, the leaching rate of Ni increased rapidly because the bacteria proliferated rapidly after a period of adaptation.

Figure 6 Effect of particle size on Ni leaching efficiency

Compared with the ore with a particle size >5 mm, the leaching speed of the ore with a particle size of 2-5 mm was faster. When the ore particle size is small, the leaching speed increases because the small-grained mineral has a large specific surface area and the useful mineral is more likely to be contacted by the bacteria. However, when the particle size is smaller than 2 mm, the leaching rate does not increase: after 45 d of leaching, the leaching rate was only 4.83% and the column 5 leaching experiment was terminated prematurely. This result is attributed to the particle size being too small and affecting the permeability of the leaching process, resulting in insufficient contact between the leaching liquid and the mineral.

When the leaching was continued, the leaching effect gradually decreased and the ore was covered by a layer of yellow material. As shown in Figures 7 and 8, XRD and SEM analyses of the slag show that jarosite was formed in the ore, which impeded the contact between the bacteria-containing liquid and the ore, and is one of the reasons for the observed decrease in the column bioleaching rate.

After 180 d of leaching, the corresponding Ni leaching rates for minerals in columns 1-4 were 23.76%, 22.15%, 32.42%, and 54.17%, respectively; Under the same leaching conditions, the bacterial leaching rate of 5–10 mm ore is 10.27% higher than the acid leaching rate. The leaching effect of 2-5 mm Ni ore was 30.41% higher than that of 10 mm Ni ore.

Figure 7 XRD pattern of Ni leaching residue

The SEM characterization is shown in Figure 8, the EDS images Figures 8(g) and (h) and XRD patterns (Figure 1) show that pyrite (point A) and chalcopyrite (point B) are present in the raw ore, which are associated with each other.

The SEM images of the bacterial leaching residue (Figures 8(c) and (d)) show that most of the pyrite disappeared, and the remaining part is mainly chalcopyrite. Because the electrostatic potential of pyrite is lower than that of chalcopyrite, pyrite is easily oxidized by bioleaching, while chalcopyrite is difficult to oxidize using bioleaching, which is the reason for the low leaching rate of copper.

In addition, as seen in Figure 8(i), certain amount of jarosite (point C in Figure 8(d)) is formed and covers the mineral in the SEM image of bacterial leach residue; jarosite is an important factor that restricts the bioleaching of minerals, which also causes the ore leaching rate not to reach a high level.

Therefore, there is a requirement to find a way to remove it, or prevent the formation of jarosite, which will help to improve the leaching rate of Ni ore in the actual production.

3.3 Kinetic analysis

Microbial leaching of metallic nickel in the ore is actually a mass–transfer process between the solid and liquid phases.

Currently, the leaching models that have been proposed include shrinking core, porous diffusion, and mixed models. The shrinking core model mainly considers the diffusion of reagents in the mineral particles and the chemical reaction with the particle surface. Most of the ore leaching process can be described by the shrinking core model. Figure 9 presents a schematic of this model.

Figure 8 SEM images of raw ore (a, b), bacterial leach residue (c, d), and acid leach residue (e, f) and EDS images (g-i) of points A-C

Figure 9 A schematic of shrinking core model

Assuming that the mineral particles are nearly spherical in the liquid–solid reaction and the leaching process is controlled by surface chemical reactions, the leaching kinetic equation of the shrinking core model is given by:

                            (2)

When the reaction process is diffusion controlled, the leaching kinetics equation of the shrinking core model becomes:

                      (3)

where x is the leaching rate of minerals, k₁ and k₂ are the rate constants of different control steps, and t is the leaching time (min).

The Ni leaching rate and time data of differently sized ores in bioleaching were substituted into Eqs. (2) and (3); the fitting curves are shown in Figures 10 and 11, respectively. The reaction rate constants and the correlation coefficients R² under different conditions are shown in Table 2.

As observed in Figures 10 and 11 and Table 2 (comparing the fitting curve data of the two models), the diffusion control model yielded a greater correlation coefficient than the chemical reaction control model under the same particle-size conditions. Therefore, the leaching process conformed to the diffusion control model.

Figure 10 Relationship between time and 1-(1-x)^1/3 in ores with different granularities

Figure 11 Relationship between time and 1-2x/3- (1-x)^2/3 in ores with different granularities

Table 2 Correlation coefficients R² of kinetic models for different grades

In this model, when the quartz grain sizes are Φ>10 mm, 5 mm<Φ<10 mm (acid), 5 mm<Φ<10 mm, and 2 mm<Φ<5 mm, the ordinate is linearly related to leaching time, with R² values of 0.9886, 0.99213, 0.99306 and 0.99491, respectively. The radius of the mineral particles is inversely proportional to the correlation coefficient because the size of the ore particles is small and their shape is nearly spherical; therefore, they better fit the hypothesis of the shrinking core model than large ore particles.

Leaching is a multiphase process between a solid and solution. Under the same conditions, the leaching rate was proportional to the contact surface area of the solid and liquid phases. For minerals of the same quality, smaller particle sizes present a larger specific surface area than larger particles; therefore, their reaction rate constant is enlarged and their leaching effect improves.

For particles of the same size, the reaction rate constant was one order of magnitude smaller in the diffusion control model than in the chemical reaction model. Therefore, the diffusion control of the solid product layer is the rate-controlling step of the Ni ore leaching, and dominantly affects the leaching process. In the experiment, the diffraction reaction of the mineral was impeded by jarosite that formed and covered the mineral surface. Therefore, reducing and eliminating the impact of sediment is a key research direction.

3.4 Change in particle size after leaching

When the column leaching was conducted for an extended period, the particle size of the ore changed because some chemical reactions and microbial actions occurred. The results are shown in Figure 12. Compared with the original mass of >10 mm particle leaching slag in column 1, after leaching accounted for 72.65%, the corresponding leaching rate was 23.76%. Because of the large particle size, bacteria and the leaching solution could not fully contact the ore, which is not conducive to Ni leaching.

Figure 12 Change in particle size after leaching in columns 1-4

Comparing the results for column 2 and column 3, both columns contain the same ore particles, revealing that the ratio of the ore size in column 2 (below 5 mm) was 28.21%, whereas that in column 3 was 36.39%. Under the same leaching conditions, the corrosion degree of the particles in column 3 was more significant, demonstrating that bacteria played an important role in the leaching process.

A comparison of columns 1, 3 and 4 shows that the fraction of the >10 mm leached slag in column 1 was 72.65%, that of the 5-10 mm leached slag in column 3 was 63.61%, and that of the 2-5 mm leached slag in column 4 was 44.64%. The effect of corrosion is most obvious in the case of column 4, demonstrating that a small particle size is conducive to the corrosion of minerals. Thus, the most effective leaching of valuable metals can be achieved by selecting an appropriate particle size for heap leaching.

4 Conclusions

The variation of particle size of the low-grade Ni ore during the leaching process using a bacteria column and the effect of Ni leaching with different particle sizes are studied. The following conclusions are drawn.

1) The results for acid leaching and bioleaching show that under the same particle size of 5–10 mm, the rate of bacterial leaching is 10.27% greater than that of acid leaching, demonstrating that bioleaching has obvious advantages over acid leaching.

2) According to the results of the column bioleaching experiments, the leaching rates of Ni with particle sizes >10 mm, 5-10 mm, and 2-5 mm are 23.76%, 32.42%, and 54.17%, respectively, after 180 d. The leaching effect of different particle sizes varies greatly, showing that particle size is an important leaching index.

3) The SEM analysis reveals the presence of large quantities of pyrite and chalcopyrite minerals in the raw ore, both of which exist in the acid leaching experiment, but the pyrite almost disappears completely in the bacterial leaching experiment, leaving only a certain amount of chalcopyrite; jarosite formation covers the surface of the mineral, indicating that pyrite is more easily oxidized than chalcopyrite in a bioleaching environment.

4) The bioleaching kinetics of low-grade nickel ore conforms to the shrinking core model, and the leaching process is controlled by internal diffusion of the solid product layer. To improve the biological leaching rate and industrial production efficiency of biologically leached ore, it is necessary to weaken or eliminate the solid passivation layer formed during the leaching process.

5) In the heap leaching operation, an ore with a slightly larger particle size can be used as the lower layer, preventing corrosion debris from accumulating at the bottom and causing a blockage. The particle size of <2 mm in column 2 could not be carried out because of blockage caused by the small particles. As long as ore with appropriate granularity is used, this outcome can be avoided. The results of this particle size experimental investigation should provide useful reference data for enterprises.

Contributors

The concept was provided by WANG Xin and YANG Hong-ying. WANG Xin, ZHANG Qin and SU Ying-bin provided the measured data and analyzed the measured data. WANG Xin and JIN Zhe-nan established the models. WANG Xin, Tong Lin-lin and SU Ying-bin analyzed the calculated results. The initial draft of the manuscript was written by WANG Xin. All authors replied to reviewers’ comments and revised the final version.

Conflict of interest

WANG Xin, YANG Hong-ying, ZHANG Qin, JIN Zhe-nan, TONG Lin-lin and SU Ying-bin declare that they have no conflict of interest.

References

[1] WANG Jiang-lin, XU Xue-liang, DING Qing-qing. Application and prospect of zinc nickel battery in energy storage technology [J]. Energy Storage Science and Technology, 2019, 8(3): 506-511. DOI: 10.12028/j.issn.2095-4239.2019.0053. (in Chinese)

[2] LIU Shu-peng, ZHANG Xiao-wei, WEI Fang. The hazards of solid waste in metal mines and resource reuse [J]. Modern Mining, 2017, 574(2): 122-125. DOI: CNKI:SUN:KYKB.0. 2017-02-033. (in Chinese)

[3] LIAO Rui, YU Shi-chao, WU Bai-qiang, ZHAO Chun-xiao, LIN Hao, HONG Mao-xin, WU Hai-yan. YANG Cong-ren, ZHANG Yan-sheng, XIE Jian-ping, QIN Wen-qing, WANG Jun, QIU Guan-zhou. Sulfide mineral bioleaching: Understanding of microbe-chemistry assisted hydrometallurgy technology and acid mine drainage environment protection [J]. Journal of Central South University, 2020, 27(5): 1367-1372. DOI: 10.1007/s11771-020-4372-4.

[4] YANG Cong-ren, QIN Wen-qing, LAI Shao-shi, WANG Jun, ZHANG Yan-sheng, JIAO Fen, REN Liu-yi, ZHUANG Tian, CHANG Zi-yong. Bioleaching of a low grade nickel-copper-cobalt sulfide ore [J]. Hydrometallurgy, 2011, 106(1, 2): 32-37. DOI: 10.1016/j.hydromet.2010.11.013.

[5] FUNARI V, MAKINE J, SALMINEN J, BRAGA R, DINELLI E, REVITZR H. Metal removal from municipal solid waste incineration fly ash: A comparison between chemical leaching and bioleaching [J]. Waste Management, 2017, 60: 397-406. DOI:10.1016/j.wasman.2016.07.025.

[6] PATHAK A, MORRISON L, HEALY M G. Catalytic potential of selected metal ions for bioleaching, and potential techno-economic and environmental issues: A critical review [J]. Bioresource Technology, 2017, 229: 211-221. DOI: 10.1016/j.biortech.2017.01.001.

[7] ANJUM F, SHAHID M, AKCIL A. Biohydrometallurgy techniques of low grade ores: A review on black shale [J]. Hydrometallurgy, 2012, 117-118: 1-12. DOI: 10.1016/ j.hydromet.2012.01.007.

[8] XIE Feng-chun, CAI Ting-ting, MA Yang, LI Chun-cheng. HUANG Zhi-yuan, YUAN Gao-qing. Recovery of Cu and Fe from printed circuit board waste sludge by ultrasound: Evaluation of industrial application [J]. Journal of Cleaner Production, 2009, 17(16): 1494-1498. DOI: 10.1016/j.jclepro. 2009.06.012.

[9] LI Shu-zhen, ZHONG Hui, HU Yue-hua, ZHAO Jian-cun, HE Zhi-guo, GU Guo-hua. Bioleaching of a low-grade nickel copper sulfide by mixture of four thermophiles [J]. Bioresource Technology, 2014, 153: 300-306. DOI: 10.1016/ j.biortech.2013.12.018.

[10] FENG Ya-li, WANG Hong-jun, LI Hao-ran, CHEN Xi-pei, DU Zhu-wei, KANG jin-xing. Effect of iron transformation on Acidithiobacillus ferrooxidans bio-leaching of clay vanadium residue [J]. Journal of Central South University, 2019, 26(4): 796-805. DOI:10.1007/s11771-019-4049-z.

[11] ZHEN Shi-jie, YAN Zhong-qiang, ZHANG Yan-sheng, WANG Jun, MAURICE C, QIN Wen-qing. Column bioleaching of a low grade nickel-bearing sulfide ore containing high magnesium as olivine, chlorite and antigorite [J]. Hydrometallurgy, 2009, 96(4): 337-341. DOI: 10.1016/ j.hydromet.2008.11.007.

[12] KARWOWSKA E, ANDRZEJEWSKA M D. Bioleaching of metals from printed circuit boards supported with surfactant-producing bacteria [J]. Journal of Hazardous Materials, 2014, 264: 203-210. DOI:10.1016/j.jhazmat.2013.11.018.

[13] WANG Jun, QIN Wen-qing, ZHANG Yan-sheng, YANG Cong-ren, ZhANG Jian-wen, NAI Shao-shi, SHANG He, QIU Guan-zhou. Bacterial leaching of chalcopyrite and bornite with native bioleaching microorganism [J]. Transactions of Nonferrous Metals Society of China, 2008, 18(6): 1468-1472. DOI: 10.1016/S1003-6326(09)60027-3.

[14] WANG Jun, ZHAO Hong-bo, QIN Wen-qing. Bioleaching of complex polymetallic sulfide ores by mixed culture [J]. Journal of Central South University, 2014, 21(7): 2633-2637. DOI:10.1007/s11771-014-2223-x.

[15] AI Chen-bing, LIANG Yu-ting, QIU Guan-zhou, ZENG Wei-min. Bioleaching of low-grade copper sulfide ore by extremely thermoacidophilic consortia at 70 °C in column reactors [J]. Journal of Central South University, 2020. 27(5):1404-1415. DOI: 10.1007/s11771-020-4376-0.

[16] MAHMOUD, A, CEZAC P, HOADLEY A F A, CONTAMINE F, DUGUES P. A review of sulfide minerals microbially assisted leaching in stirred tank reactors [J]. International Biodeterioration & Biodegradation, 2017, 119: 118-146. DOI:10.1016/j.ibiod.2016.09.015.

[17] WU Jian-hui. Process optimization on heap bioleaching of low-grade secondary copper sulfide [J]. Non-ferrous Metals (smelting), 2015(2): 1-4. (in Chinese)

[18] WANG Yu-guang, CHEN Xin-hua, ZHOU Hong-bo. Disentangling effects of temperature on microbial community and copper extraction in column bioleaching of low grade copper sulfide [J]. Bioresource Technology, 2018, 268: 480-487. DOI:10.1016/j.biortech.2018.08.031.

[19] WU Zeng-ling, ZOU Lai-chang, CHEN Jin-he, LAI Xiao-kang, ZHU Yong-guan. Column bioleaching characteristic of copper and iron from Zijinshan sulfide ores by acid mine drainage [J]. International Journal of Mineral Processing, 2016, 149: 18-24. DOI:10.1016/j.minpro.2016.01.015.

[20] BAKER A C, DOPSON M. Life in acid: pH homelostasis in acidophiles [J]. Trends in Microbiology, 2007, 15(4): 165-171. DOI:10.1016/j.tim.2007.02.005.

[21] GHORBANI Y, BECKER M, PETERSEN J, MAINZA A N, FRANZIDIS J P. Investigation of the effect of mineralogy as rate-limiting factors in large particle leaching [J]. Minerals Engineering, 2013, 52: 38-51. DOI: 10.1016/j.mineng. 2013.03.006.

[22] EGAN J, BAZIN C, HODOUIN D. Effect of particle size and grinding time on gold dissolution in cyanide solution [J]. Minerals, 2016, 6(3): 1-9. DOI:10.3390/min6030068.

[23] YANG Yu, DIAO Meng-xue, LIU Kai, QIU Guan-zhou. Column bioleaching of low-grade copper ore by Acidithiobacillus ferrooxidans in pure and mixed cultures with a heterotrophic acidophile Acidiphilium sp [J]. Hydrometallurgy, 2013, 131-132: 93-98. DOI: 10.1016/ j.hydromet.2012.09.003.

(Edited by FANG Jing-hua)

中文导读

柱式反应器中粒径对低品位镍矿生物浸出的影响

摘要：本文研究了生物柱浸出低品位镍矿中镍的浸出，并考察了不同粒度对浸出镍的影响。将镍矿石(平均镍含量为0.23%)破碎成>10 mm，5~10 mm，2~5 mm和<2 mm四种不同粒径的颗粒度。属水平上菌株的主要成分为硫杆菌属53.11%、钩端螺旋菌属43.52%和嗜酸菌属3.37%。浸出试验条件控制在pH 2.0和23 °C。经过180 d的生物浸出实验，>10 mm(生物浸出)，5~10 mm(酸浸出)，5~10 mm(生物浸出)，2~5 mm(生物浸出)的镍浸出率分别为23.76%， 22.15%，32.42%和54.17%。分析粒度为2~5 mm的矿石，浸出前后矿石粒度发生很大变化，其中2~5 mm粒度的矿石比例降到44.64%。实验结果表明，柱式生物浸出最适合2~5 mm粒径的矿石，适当控制矿石粒度可以实现镍的高效浸出，可以为企业提供参考数据。

关键词：细菌；颗粒大小；柱浸；镍；生物浸出

Foundation item: Project(U1608254) supported by the Special Fund for the National Natural Science Foundation of China; Projects(ZJKY2017(B)KFJJ01, ZJKY2017(B)KFJJ02) supported by the Zijin Mining Group Co., Ltd., China

Received date: 2019-06-30; Accepted date: 2020-04-30

Corresponding author: YANG Hong-ying, PhD, Professor; Tel: +86-24-83673932; E-mail: yanghy@smm.neu.edu.cn; ORCID: https://orcid.org/0000-0001-9753-2051