Arsenic Removal from Mine Tailings for Recycling via Flotation

Materials Transactions, Vol. 54, No. 12 (2013) pp. 2291 to 2296 © 2013 The Japan Institute of Metals and Materials

EXPRESS REGULAR ARTICLE

Arsenic Removal from Mine Tailings for Recycling via Flotation Junhyun Choi1, Kyuhyeong Park1, Jeongsik Hong1, Jayhyun Park2 and Hyunjung Kim1,+ 1 Department of Mineral Resources and Energy Engineering, Chonbuk National University, 664-14 Duckjin-dong 1Ga, Duckjin-gu, Jeonju, Jeonbuk 556-756, Republic of Korea 2 R&D Team, Institute of Mine Reclamation Coporation, Coal Center, 30 Chungjun-dong, Jongno-gu, Seoul 110-727, Republic of Korea

In this study, we propose a flotation process to remove the arsenic from Samkwang mine tailings in South Korea, which contained a high arsenic content, in order to render them suitable for recycling. In order to maximize the arsenic removal from the mine tailings, three variables (type of collectors and activators, and solution pH) were systematically investigated. Characterization experiments (X-ray diffraction and electrokinetic property analyses) were carried out to complement the flotation results, and the results showed that the mine tailings were mainly composed of arsenopyrite (FeAsS), arsenic trioxide (As2O3, As4O6), arsenic pentoxide (As2O5) and quartz (SiO2). The flotation results obtained using different collectors (i.e., potassium amyl xanthate (PAX), sodium oleate, sodium dodecyl sulfate) revealed that arsenic removal efficiency was greatest in the presence of PAX, which was explained by the difference in the electrokinetic properties and the interaction type of collectors with arsenic-bearing minerals. Meanwhile, the addition of activators (Na2S, CuSO4, Na2S+CuSO4) and the pulp pH significantly affected the arsenic removal efficiency. The arsenic removal was maximized in the presence of mixed activators (Na2S+CuSO4) at low pH. The effect of activator type and pulp pH on the arsenic removal efficiency was attributed to the coupled role of the sulphidization of arsenic oxides (e.g., AS2O3, AS4O6 and AS2O5), the activation of sulphidized minerals, and the formation of dixanthogen. Lastly, based on the results obtained from the parameter optimization tests (i.e., type of collector and activator, and pulp pH), a series of flotation processes consisting of rougher flotation and two subsequent scavenging flotations was designed. The results demonstrated the capability of the process to successfully remove arsenic from Samkwang mine tailings for recycling. [doi:10.2320/matertrans.M2013285] (Received July 25, 2013; Accepted October 7, 2013; Published November 15, 2013) Keywords: mine tailings, arsenic removal, flotation, recycling

1.

Introduction

Arsenic is one of the most dangerous inorganic pollutants, causing health and environmental emergencies in several areas of the world. Exposure to arsenic causes serious human health problems including irritation of the stomach and intestines and, especially, an increased risk of developing lung, liver, kidney and skin cancer.1­6) In addition, arsenic from mine tailings has caused the serious contamination of soil, surface water and groundwater.7­10) Arsenopyrite (FeAsS) is one of the most common arsenicbearing minerals and is found in a range of ore deposits, including magmatic, hydrothermal and porphyry-style systems. Due to its common association with gold, FeAsS is often mined.11,12) In South Korea, in order to obtain gold, a lot of cyanide was conventionally used as a depressant during the flotation process at gold-containing mines because cyanide acts as an inhibitor for the electrochemical reactions on the surface of the FeAsS. In the presence of cyanide, the adsorption of xanthate onto FeAsS was significantly inhibited.13­15) This historical use of a lot of cyanide has been reported to have resulted in many South Korean mine tailings with high arsenic contents.16­18) The mine tailings of the approximately 1000 dormant and/or abandoned mines in South Korea are a threat to the natural environment and national health. The Korean government has initiated restorations of the dormant and/or abandoned mines. One of the major methods used in South Korea to prevent soil pollution/contamination includes the establishment of concrete-retaining walls for preventing loss of mine tailings and mine-waste prior to soil +

Corresponding author, E-mail: [email protected]

covering.19) This method of establishing preventive structures is effective for restricting the physical movement of tailing particles; however, the method still suffers a risk of environmental pollution of the surrounding areas of the mines by the infiltration of rainfall through the mine tailings (e.g., acid mine drainage), indicating that alternative methods are required to reduce the risk. Much research has been devoted to developing a flotation method capable of separating arsenic-bearing minerals.20­25) For instance, some studies20,22) reported the flotation technique by using thionalide as a collector for the selective enrichment of arsenic. In addition, Bruckard and the colleagues21) investigated the flotation behavior of arsenic as a function of pulp pH. More recently, there was an attempt to develop an environmentally friendly flotation process for the selective separation of arsenic.25) Nevertheless, no attempt to investigate arsenic removal from mine tailings through flotation has been made in South Korea. Therefore, considering the regional diversity of mine tailings in terms of physicochemical and mineralogical characteristics, relevant studies are required. According to Korea Soil Standard Criteria, the warning level for arsenic concentration is 50 mg/kg for zone 2 areas, which include forest land, salt farm and waterfields.26,27) In this study, therefore, flotation was conducted to recycle Samkwang mine tailings in South Korea containing a high arsenic content (target arsenic concentration at the tailings after flotation ¯50 mg/kg). The content of other heavy metals (i.e., cadmium, chromium, copper, lead, zinc) was almost equal to or less than the warning level for zone 2 areas (Table 1).26,27) Furthermore, with the Korea government’s goal of minimizing the loss of mine tailings, the effects of collectors, activators, mixed activators, and solution pH were also examined.

2292

J. Choi, K. Park, J. Hong, J. Park and H. Kim

Table 1

Heavy metal composition of the Samkwang mine tailings. Chemical composition (mg/kg)

As

Cd

Cr

Cu

Pb

Zn

8137.8

19.58

68.15

21.68

29.35

606.83

2.

Materials and Methods

2.1 Samples Samkwang mine tailings containing high arsenic and pure FeAsS which was obtained from Industry & Trade Co. (China) were selected for the present study. For the characterization and flotation experiments, the tailings were sieved between ¹65 mesh and +200 mesh (212­75 µm, Tyler Standard), collected, and used in flotation tests. To investigate the chemical composition and mineralogy of the raw tailings, inductively coupled plasma (ICP) analysis (Optima 5300PV, PerkinElmer Inc., USA) and X-ray diffraction (XRD) analysis (D/Max-2200/PC, Rigaku, Japan) were conducted, respectively. 2.2 Reagents The xanthate used in this study was potassium amyl xanthate (PAX, C5H11OCS2K) having a purity of 90% or higher and made by Hong Yuan Industry & Trade Co. in China. Sodium oleate (SO, C18H33O2Na) and sodium dodecyl sulfate (SDS, CH3(CH2)11OSO3Na) were employed as other collectors and obtained from Sigma-Aldrich. Sodium sulfide (Na2S) and copper sulfate (CuSO4) manufactured by SigmaAldrich were used as activators. Aerofloat-65 (AF-65, CH3(C3H6O)4OH) supplied by American Cyanamid, USA was used as a frother and analytical grade of HCl and NaOH (Fisher Scientific) were used as pH modifiers. 2.3

Electrokinetic properties of the Samkwang mine tailings The electrophoretic mobility of the Samkwang mine tailings and pure FeAsS was measured at different pH conditions using a zeta-potential analyzer (ELS-Z, Otsuka, Hirakata, Japan). To measure the mobility, the samples were ground using a mortar. Then, 1 g of each sample was added to DI water (Milli-Q Plus, Millipore Ltd., UK) and the electrophoretic mobility of the samples was measured at different pH conditions. The measured mobility values were converted to zeta potentials based on Smoluchowski equation.28,29) The solution pH was adjusted with 1N HCl and NaOH by a pH meter (Accumet AP61, Fisher Scientific), and the measurements were conducted in triplicate. 2.4 Flotation tests For flotation experiments, a 1 L flotation cell (Denver Sub-A, USA) was used. In every test, 200 g Samkwang mine tailings, 800 mL deionized (DI) water, impeller speed of 1000 rpm and flotation time of 10 min were applied. In addition, the AF-65 (250 mL/ton) was conditioned for 3 min for all experiments before the air was introduced in the suspension. In the first set of experiments, to select the desired type of collectors, SO, SDS or PAX was added to the

pulp in the same concentration (100 g/ton) and then was conditioned for 5 min, followed by 3 min frother conditioning and 10 min flotation. For the second set of experiments, Na2S or CuSO4 (50­200 g/ton) was added to examine the effect of activators and determine their optimum concentration to maximize arsenic removal efficiency, followed by 5 min collector conditioning, 3 min frother conditioning and 10 min flotation. For the third set of experiments, the desired concentration of mixed Na2S and CuSO4 was added to the pulp at two different pH conditions (pH 4 and 9) to further examine the coupled effect of mixed activators and improve arsenic removal efficiency, followed by 5 min collector conditioning, 3 min frother conditioning, and 10 min flotation. Lastly, in order to obtain recyclable products with a target arsenic concentration after flotation of less than 50 mg/kg, two subsequent scavenging processes were carried out at the optimum conditions (i.e., desired collector’s type and activators’ concentration, and solution pH) as determined from the previous sets of experiments. The floated and unfloated products were collected, filtered with a 0.45 µm filter (ADVANTEC, Toyo RoshiKaisha, Japan) using a small vacuum pump, and dried at 80°C in an oven. The arsenic removal efficiency was calculated by ((Cc)/(Ff )) © 100. Where, C and F denote the weight of the concentrate (i.e., floated product) and the feed, respectively. And, c and f denote the arsenic concentration (i.e., assay) of the concentrate and the feed, respectively. 3.

Results and Discussion

3.1

Physicochemical properties of the Samkwang mine tailings and pure arsenopyrite The XRD patterns and ICP analysis results for the Samkwang mine tailings are presented in Fig. 1 and Table 1, respectively. The arsenic, cadmium, chromium, copper, lead and zinc contents in the tailings measured through ICP were about 8138, 20, 68, 22, 29 and 607 mg/kg, respectively, which indicated that arsenic is the main contaminant (Table 1). The XRD analysis revealed the main minerals to be FeAsS, arsenic trioxide (As2O3, As4O6), arsenic pentoxide (As2O5) and quartz (SiO2) (Fig. 1). Since arsenic was present in the forms of FeAsS, AS2O3, AS2O5 and AS4O6 (Fig. 1), the tailings were considered suitable for using flotation for

Fig. 1

XRD patterns of the Samkwang mine tailings.

Arsenic Removal from Mine Tailings for Recycling via Flotation

Fig. 2 Zeta potentials of pure FeAsS and the Samkwang mine tailings at different solution pHs.

Fig. 3 Arsenic concentration of the tails and arsenic removal efficiency after flotation. The experiments were carried out at pH 9 with PAX, SO and SDS concentrations of 100 g/ton and AF-65 concentration of 250 mL/ton.

arsenic removal. Figure 2 shows the zeta potentials of the tailings and pure FeAsS according to pH. The isoelectric point (IEP) of pure FeAsS ranged from 4 to 5, which is consistent with the results from a previous study.31) The IEP of the tailings was determined to be less than 2, which was attributed to the large fraction of SiO2 present in the tailings, as indicated in the XRD results (Fig. 1).30) 3.2 Arsenic flotation 3.2.1 Effect of collectors In order to investigate the effect of collectors on the flotation of the Samkwang mine tailings and further select the optimum reagent for the subsequent processes, flotation experiments in accordance with PAX, SO and SDS were first carried out at an adjusted pulp pH of 9 and the results are presented in Fig. 3. The arsenic concentration of the tails was about 8125 and 15030 mg/kg and the arsenic removal efficiency was about 3.77 and 2.95% when SO and SDS were used as the collector, respectively. The interaction of anionic surfactants such as SO and SDS with FeAsS was expected to be unfavorable, due to the electrostatic repulsive force between anionic surfactants and FeAsS, at pH 9 because the IEP of FeAsS ranged between 4 and 5 (Fig. 2).30) Therefore, FeAsS did not float well using SO and SDS at pH 9. Meanwhile, when PAX was used as a collector, the arsenic concentration of the tails was about

2293

Fig. 4 Arsenic concentration of the tails and arsenic removal efficiency after flotation. The experiments were carried out at pH 9 with Na2S concentration of 50­200 g/ton, PAX concentration of 100 g/ton, and AF-65 concentration of 250 mL/ton.

Fig. 5 Arsenic concentration of the tails and arsenic removal efficiency after flotation. The experiments were carried out at pH 9 with CuSO4 concentration of 50­200 g/ton, PAX concentration of 100 g/ton, and AF65 concentration of 250 mL/ton.

6678 mg/kg and the arsenic removal efficiency was about 29.06%, indicating that xanthate was a more powerful collector for FeAsS flotation. Chemisorption has been suggested as the adsorption mechanism of xanthate ions (X¹) onto the surface of sulfide minerals, whereas the two other collectors (SDS and SO) were physically adsorbed onto the mineral surfaces.32,33) More specifically, the oxidation of xanthate ions (X¹) to dixanthogen (X2) occurs onto the surface of the FeAsS which acts as a catalyst for the oxidation/reduction reaction.33,34) This process renders the surface of FeAsS hydrophobic. In fact, previous studies reported that FeAsS floated well using xanthate as a collector.35­38) Hence, PAX was utilized as the collector in the following experiments. 3.2.2 Effect of activators Figures 4 and 5 show that arsenic concentration of the tails and the arsenic removal efficiency after the flotation in accordance with the addition of Na2S and CuSO4 as activators, respectively. Overall, the addition of Na2S and CuSO4 before PAX addition (100 g/ton) strongly affected the arsenic concentration of the tails and the arsenic removal efficiency, which were about 4679, 4793, 4080 and 4681 mg/kg and 52.39, 51.42, 58.73 and 68.67% in the presence of 50, 100, 150 and 200 g/ton Na2S, respectively

2294

J. Choi, K. Park, J. Hong, J. Park and H. Kim

(Fig. 4). The arsenic removal tended to increase with increasing Na2S addition. Additionally, the arsenic concentration of the tails was approximately 1996 mg/kg lower and the arsenic removal efficiency was about 39.31% greater in the presence of Na2S compared to in the case of its absence. The Na2S-induced enhancement in arsenic removal was attributed to the sulphidization of the arsenic oxides such as AS2O3, AS4O6 and AS2O5 by Na2S, which led to more selective interaction between the surface of the sulphidized arsenic oxides and xanthate.35) Specifically, soluble sulfide ions (S2¹) could form a sulfide layer onto the surface of the arsenic oxides, which favors xanthate adsorption onto the sulphidized arsenic oxides.39­41) The addition of CuSO4 before PAX addition also strongly affected the arsenic flotation (Fig. 5). In the presence of 50, 100, 150, 200 g/ton CuSO4, the arsenic concentration of the tails and the arsenic removal efficiency were about 3210, 3869, 3833 and 3110 mg/kg and 69.4, 62.47, 71.21 and 77.06%, respectively. The trend for the arsenic concentration of the tails and the arsenic removal efficiency in the presence of CuSO4 was similar with that for Na2S, showing the maximum arsenic removal at the highest CuSO4 dosage of 200 g/ton. Specifically, the arsenic concentration of the tails was about 3568 mg/kg lower and the arsenic removal efficiency 47.7% greater in the presence of CuSO4, as compared to the case without CuSO4. Previous studies reported that cupric ions (Cu2+) could activate sulfide minerals and enhance their flotation with xanthate.42,43) Wang et al.44) reported that Cu2+ could form copper complexes onto the surface of FeAsS due to their strong electron accepting ability through which the adsorption of xanthate ions (X¹) onto the surface of FeAsS was enhanced. Although arsenic removal maximized in the presence of 200 g/ton Na2S or CuSO4, the arsenic concentration in tails did not meet the warning criteria (50 mg/kg) for recycling. Since the main purpose of this study was to render the Samkwang mine tailings suitable for recycling, we conducted additional flotation tests with 200 g/ton of both Na2S and CuSO4 at different pH conditions (pH 4 versus pH 9) to improve the removal efficiency. 3.2.3 Effect of mixed activators Figure 6 shows the arsenic concentration of the tails and the arsenic removal efficiency after the flotation in the presence of mixed activators (200 g/ton Na2S + 200 g/ton CuSO4) at two different pH conditions (pH 4 and 9). Overall, the arsenic concentration of the tails and the arsenic removal efficiency were lower and greater, respectively, in the presence of mixed activators (200 g/ton Na2S + 200 g/ton CuSO4) than in the case of their individual use (i.e., 200 g/ton Na2S or 200 g/ton CuSO4) at pH 9. At pH 9, the arsenic concentration of the tails and the arsenic removal efficiency in the presence of both Na2S and CuSO4 were about 2933 mg/kg and 80.11%, respectively, which were around 1748 mg/kg lower and about 11.44% greater than in the case of Na2S alone. Additionally, the arsenic concentration of the tails and the arsenic removal efficiency were approximately 176 mg/kg lower and around 3.05% greater, respectively, in the presence of both Na2S and CuSO4 than in the case of 200 g/ton CuSO4 alone at pH 9. The results clearly exhibited the strong coupled effect of Na2S and CuSO4 (i.e., the sulphidization of arsenic oxides such as

Fig. 6 Arsenic concentration of the tails and arsenic removal efficiency after flotation. The experiments were carried out with mixed activators (Na2S and CuSO4 concentration = 200 g/ton) at pH 4 and 9. PAX and AF-65 concentrations were 100 g/ton and 250 mL/ton, respectively.

AS2O3, AS4O6 and AS2O5 and the activation of sulphidized minerals) and the reinforcement effect of this coupling action on arsenic flotation with PAX. In order to further examine the effect of solution pH on arsenic removal via flotation, additional experiments were carried out at a low pH condition (pH 4), and the results are also presented in Fig. 6. The arsenic concentration of the tails and the arsenic removal efficiency were about 1753 mg/kg and 86.54% at pH 4, respectively. Compared with the results at pH 9, the arsenic concentration of the tails was approximately 1179 mg/kg lower and the arsenic removal efficiency was around 6.43% higher. The decreased removal efficiency at higher pH was attributed to the relatively higher oxidation of FeAsS at higher pH, resulting in the greater formation of an oxidation product on the surface of FeAsS.45,46) Accordingly, the chemisorption of xanthate onto FeAsS was reduced, which decreased the hydrophobicity of the FeAsS surface.45,46) In fact, several studies reported similar trends in which FeAsS floated better at low pH conditions (ca. pH 3­4).31,45,46) However, the arsenic removal efficiencies obtained from the flotation tests using mixed activators did not meet the warning criteria of arsenic (50 mg/kg) for recycling the tailings, regardless of pH. Hence, to meet the warning criteria, we conducted additional experiments with scavenging tests to maximize the arsenic removal efficiency. 3.2.4 Effect of scavenging Figure 7 shows the arsenic concentration of the tails and the arsenic removal efficiency obtained during and after two subsequent scavenging tests. Here, it should be noted that similar optimization tests with the rougher flotation were carried out to determine the optimal chemical dosages added for the scavenging tests, and the results suggested that the arsenic removal efficiency was maximized at the same chemical dosages as observed from the rougher flotation (data not shown). Hence, the scavenging tests were carried out using the tails obtained after the rougher flotation with mixed activators (200 g/ton Na2S + 200 g/ton CuSO4) at pH 4. The experiments were conducted with 100 g/ton PAX and 250 mL/ton AF-65. The results showed that the arsenic concentrations of middlings 1, middlings 2, concentrates, and tails were about 135830, 95778, 3711 and 44 mg/kg, respectively. The cumulative arsenic removal efficiencies of

Arsenic Removal from Mine Tailings for Recycling via Flotation

2295

Tailings

Rougher flotation

Na2S : 200 g/ton, CuSO4 : 200 g/ton PAX : 100 g/ton AF-65 : 250 mL/ton

tails

1st scavenging

Na2S : 200 g/ton, CuSO4 : 200 g/ton PAX : 100 g/ton AF-65 : 250 mL/ton

tails

2nd scavenging Fig. 7 Arsenic concentration of the tails and cumulative arsenic removal efficiency for two subsequent scavenging tests. All experiments were carried out with mixed activators (Na2S and CuSO4 concentration = 200 g/ton). PAX and AF-65 concentrations were 100 g/ton and 250 mL/ton, respectively, for all cases.

middlings 1, middlings 2, and concentrates were about 79.28, 98.56 and 99.73%, respectively. Hence, the arsenic concentration in the tails was reduced to below the warning criteria (50 mg/kg) after the two subsequent scavenging processes, which would render the tailings recyclable. The contents of cadmium, chromium, copper, lead and zinc in the final products were 1.65, 12.62, 10.03, 11.63 and 76.5 mg/kg, respectively, which were also below the warning level for recycling. Additionally, the yield of final products (i.e., the weight ratio of recyclable products and starting materials) was about 84.58%. 4.

Conclusions

The Korean government has currently initiated the restoration of all dormant and/or abandoned mines. Hence, flotation experiments were conducted to recycle the Samkwang mine tailings by reducing the arsenic content below the warning criteria (50 mg/kg). The following conclusions were obtained from the study results. (1) The arsenic removal was greater in the presence of PAX than in that of SO or SDS due to the difference in the electrokinetic properties and the interaction type of collectors with arsenic-bearing minerals. (2) The type of activator and pulp pH significantly affected the arsenic removal efficiency. The arsenic removal was maximized in the presence of mixed activators (Na2S + CuSO4) at low pH due to the coupled role of the sulphidization of arsenic oxides (e.g., AS2O3, AS4O6 and AS2O5), the activation of sulphidized minerals, and the formation of dixanthogen. (3) A successful flotation process consisting of rougher flotation and two subsequent scavenging flotations (Fig. 8) was designed for recycling the Samkwang mine tailings by reducing the arsenic content to 44 mg/kg, which is below the warning criteria of 50 mg/kg. Additionally, about 85% of the mine tailings (w/w) were recyclable via the proposed process. Acknowledgements This research was supported by the Mine Reclamation Corporation Research Fund (MIRECO) and the selection of

Na2S : 200 g/ton, CuSO4 : 200 g/ton PAX : 100 g/ton AF-65 : 250 mL/ton

tails

Recyclable products Fig. 8 Flowsheet of the flotation process optimized for arsenic removal from the Samkwang mine tailings.

research-oriented professor of Chonbuk National University in 2013. REFERENCES 1) J. C. Ng, J. P. Wang and A. Shraim: Chemosphere 52 (2003) 1353­ 1359. 2) K. Ahmad: Lancet 358 (2001) 133. 3) P. Lattanzi, S. D. Pelo, E. Musu, D. Atzei, B. Elsener, M. Fantauzzi and A. Rossi: Earth-Sci. Rev. 86 (2008) 62­88. 4) G. Long, Y. Peng and D. Bradshaw: Miner. Eng. 36­38 (2012) 179­ 186. 5) P. L. Smedley and D. G. Kinniburgh: Appl. Geochem. 17 (2002) 517­ 568. 6) A. H. Smith, C. Hopenhaynrich, M. N. Bates, H. M. Goeden, I. Hertzpicciotto, H. M. Duggan, R. Wood, M. J. Kosnett and M. T. Smith: Environ. Health Persp. 97 (1992) 259­267. 7) M. C. Jung, I. Thornton and H.-T. Chon: Sci. Total Environ. 295 (2002) 81­89. 8) I. Ko, J. S. Ahn, Y. S. Park and K. W. Kim: Korea Chem. Spec. Bioavailab. 15 (2003) 67­74. 9) N. C. Woo and M. J. Choi: Environ. Geol. 40 (2001) 305­311. 10) K.-R. Kim, B.-T. Lee and K.-W. Kim: J. Geochem. Explor. 113 (2012) 124­129. 11) C. L. Corkhill and D. J. Vaughan: Appl. Geochem. 24 (2009) 2342­ 2361. 12) H. W. Nesbitt, L. J. Muir and A. R. Pratt: Geochim. Cosmochim. Acta 59 (1995) 1773­1786. 13) K. Osseoasare, T. Xue and V. S. T. Ciminelli: JOM J. Miner. Met. Mater. Soc. 35 (1983) 51. 14) C. A. Prestidge, J. Ralston and R. S. Smart: Int. J. Miner. Process. 38 (1993) 205­233. 15) C. A. Prestidge, J. Ralston and R. S. Smart: Colloids Surf. A 81 (1993) 103­119. 16) J. S. Ahn, Y. S. Park, J.-Y. Kim and K.-W. Kim: Environ. Geochem. Health 27 (2005) 147­157. 17) J.-Y. Kim, K.-W. Kim, J.-U. Lee, J.-S. Lee and J. Cook: Environ. Geochem. Health 24 (2002) 213­225. 18) M.-J. Kim, K.-H. Ahn and Y. J. Jung: Chemosphere 49 (2002) 307­ 312. 19) M.-S. Ko, H.-S. Park and J.-U. Lee: J. Korean Soc. Geosystem Eng. 46 (2009) 239­251. 20) S. Nakashima: Fresen. J. Anal. Chem. 341 (1991) 570­571. 21) W. J. Bruckard, I. Kyriakidis and J. T. Woodcock: Int. J. Miner. Process. 84 (2007) 25­32. 22) Z. Karagölge, M. Alkan and B. Dönmez: J. Chem. Eng. Jpn. 35 (2002) 217­225. 23) X. Ma and W. J. Bruckard: Int. J. Miner. Process. 93 (2009) 89­94.

2296

J. Choi, K. Park, J. Hong, J. Park and H. Kim

24) J. Rubio, M. L. Souza and R. W. Smith: Miner. Eng. 15 (2002) 139­ 155. 25) A. V. Kanarskii, E. V. Adamov and L. N. Krylova: Russ. J. Non-Ferr. Met. 53 (2012) 120­124. 26) M.-S. Ko, H.-S. Park, K.-W. Kim and J.-U. Lee: Environ. Geochem. Health 35 (2013) 1­7. 27) K.-W. Kim, M.-S. Ko, A.-Y. Kim, J. W. Kim, J.-Y. Kim, B.-T. Lee, J.-S. Lee and J.-U. Lee: Geochem. J. 46 (2012) 17­19. 28) M. Von Smoluchowski: Z. Phys. Chem. (Muenchen, Ger.) 92 (1917) 129­168. 29) M. Elimelech, J. Gregory, X. Jia and R. Williams: Particle Deposition & Aggregation-Measurement, Modeling and Simulation, (ButterworthHeinemann, Oxford, 1995). 30) J. Choi, W. Kim, W. Chae, S. B. Kim and H. Kim: Mater. Trans. 53 (2012) 2191­2194. 31) A. L. Valdivieso, A. A. S. Lopez, C. O. Escamilla and M. C. Fuerstenau: Int. J. Miner. Process. 81 (2006) 27­34. 32) F. Goktepe and J. Turkish: Eng. Env. Sci. 26 (2002) 309­318. 33) S. A. Allison, L. A. Goold, M. J. Nicol and A. Granville: Metall. Trans. 3 (1972) 2613­2618. 34) A. L. Valdivieso, C. O. Escamilla, S. Song, I. L. Baez and I. G. Martinez: Int. J. Miner. Process. 69 (2003) 175­184.

35) F. Garip and H. Ozdag: Int. J. Miner. Process. 55 (1998) 129­137. 36) N. D. Janetski, S. I. Woodburn and R. Woods: Int. J. Miner. Process. 4 (1977) 227­239. 37) J. O. Leppinen, C. I. Basilio and R. H. Yoon: Int. J. Miner. Process. 26 (1989) 259­274. 38) W. Tolley, D. Kotlyar and R. V. Wagoner: Miner. Eng. 9 (1996) 603­ 637. 39) S. Castro, H. Soto, J. Goldfarb and J. Laskowski: Int. J. Miner. Process. 1 (1974) 151­161. 40) S. Castro, J. Goldfarb and J. Laskowski: Int. J. Miner. Process. 1 (1974) 141­149. 41) D. W. Clark, A. J. H. Newell, G. F. Chilman and P. G. Capps: Miner. Eng. 13 (2000) 1197­1206. 42) T. N. Khmeleva, D. A. Beattie, T. V. Georgiev and W. M. Skinner: Miner. Eng. 16 (2003) 601­608. 43) N. P. Finkelstein: Int. J. Miner. Process. 52 (1997) 81­120. 44) X. H. Wang, K. S. E. Forssberg and N. J. Bolin: Scand. J. Metall. 18 (1989) 288­294. 45) C. Plackowski, A. V. Nguyen and W. J. Bruckard: Miner. Eng. 30 (2012) 1­11. 46) B. Tapley and D. Yan: Miner. Eng. 16 (2003) 1217­1220.