ZADRA Elution Circuit Optimisation and Operational

ZADRA Elution Circuit Optimisation and Operational Experience at the CIL Plant of Gold Fields Ghana Limited M. Beyuo and G. B. Abaka-Wood Beyuo, M. and Abaka-Wood, G.B. (2016). ―ZADRA Elution Circuit Optimisation and Operational Experience at the CIL Plant of Gold Fields Ghana Limited‖, 4th UMaT Biennial International Mining and Mineral Conference, pp. MR 161-167.

Abstract The ZADRA system is another elution process where gold that is adsorbed on to activated carbon is desorbed from the carbon by a reversal of the adsorption kinetics. The ZADRA elution circuit at Gold Fields Ghana Limited was designed as a pressure system with an operational pressure set point of 350 kPa. It consists of circulating 3% sodium hydroxide water based solution up flow through a stationary bed of loaded activated carbon at a flow rate of 64m3/h at a temperature of 125 °C. The process was designed to take about 16 hours to complete 30 elutions per month. The ZADRA process is characterised by simplicity of system design and operation, with low desorption rates. Manual control is the standard devoid of the necessity for automated controls and expected low chemical consumption. However, fluctuations in flow and temperatures recorded during commissioning and operational stages, reduced stripping efficiencies with its concomitant effect as an extension of the required stripping cycle time. Consequent on the extension of the required stripping cycle time and high chemical consumption, the ZADRA elution process hardly completed one batch of elution per day. A review on the basis of the process design as to whether it is a pressure or atmospheric ZADRA was carried out necessitating in the reduction of the pressure set point to 120 kPa culminating in a complete turnaround in the system‘s performance. Other changes followed resulting in a reduction of the stripping cycle time to 13 hours completing two batches of elution per day.

Keywords: Elution, ZADRA elution, activated carbon, eluate, electrowinning, heat exchangers

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of high temperature and pressure, treatment of gold loaded AC with concentrated cyanide or caustic solution followed by elution with potable water, aurocyanide complex is desorbed from the gold loaded activated carbon. Temperature is a key variable in the elution process and temperatures of 100-120°C are necessary to achieve optimum elution performance (Anon, 2016). A successful desorption process requires proper selection of eluants, which strongly depends on the mechanism of desorption. Selected eluant should be: costeffective, eco-friendly and efficient.

Introduction

The CIL Plant of Gold Fields Ghana Limited (GGL) Tarkwa Mine, currently exploits the tabular auriferous conglomerates from seven active open pits Pepe, Awonaben, Teberebie, Akontansi Central, Akontansi Ridge, Underlap and Kottraverchy. The CIL plant capacity was increased from 12.3 Mtpa to 13.5 Mtpa in 2014. Further expansions being considered have the potential to increase the capacity to 15.5Mtpa (Mineral resources report, 2014). The leaching circuit of the plant is made up of 17 tanks in which sodium cyanide is used as the lixiviant whiles activated carbon is introduced to adsorb the leached gold. The plant employs both the Anglo American Research Laboratory (AARL) and ZADRA methods to strip loaded carbon (1000 -1500 g/t Au). The scope of this paper is aimed at reviewing the performance of the ZADRA elution circuit from its commissioning year to the end of 2015.

The most common commercial techniques for elution of gold cyanide from activated carbon are the ZADRA and AARL procedure. In the ZADRA elution process, hot solutions of 1% weight/volume (w/v) sodium hydroxide (NaOH) and 0.2% w/v sodium cyanide (NaCN) are recycled through a gold cyanide-loaded AC bed for up to 72 h at 95–100 oC and atmospheric pressure to desorb Au(CN)2. More recently a modified Zadra procedure operating at 140 oC in a pressurized system has reduced elution time to 10–12 h (Robles, 2001).

1.1 Review on Gold Elution

Soleimani & Kaghazchi (2008) sought to investigate for a rapid, safe, ambient temperature method for gold stripping from loaded activated carbon. Gold loaded AC was contacted with a strong base followed by elution with an aqueous solution containing an organic solvent to investigate an improved process for recovering gold from activated carbon other than ZADRA or AARL methods. Gold desorption from loaded activated carbon was carried

A variety of techniques are found in literature on the recovery of gold from various solution. (Aylmore and Muir, 2001; Grosse et al., 2003; Syed, 2012; Van Deventer and Van der Merwe, 1995; Wan et al., 1993; Yalcin and Arol, 2002). The adsorption of gold complexes onto activated carbon (AC) is the basis of modern techniques for gold recovery and it is proceded by the desorption of adsorbed gold from activated carbon with an efficient eluant. By means

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carbon at a flow rate of about 64m3/h at about 125°C. Pregnant eluate from the elution column is cooled to below boiling point and passed through the electro winning cells where gold is deposited on the cathodes. On leaving the electrowinning cell, the now gold depleted eluate is re-heated before it is circulated back into the elution column. Achieving the design electro winning single pass extraction in a ZADRA elution circuit is critical. Unlike the AARL elution system, poor single pass extraction in a ZADRA process has a direct impact on the overall elution efficiency. The process was designed to last for about 14 to 16 hours. An elution column temperature of 125 °C is maintained until the process is over. Elution and electrowinning as indicated occurs simultaneously, and solution circulation and transfer from one stage to the other is made possible by automated valves. Electrowinning cells are operated within 750-800 A and 3.8-4.0 V. The first ZADRA elution process started at the CIL plant on 21st January 2009 and has since been running to date.

out using acetonitrile, acetone, methanol, isopropanol and ethanol. Gold recovery for these solvents was in the order: acetone > acetonitrile > methanol > ethanol > isopropanol. It was concluded that organic solvents could be used to strip gold from activated carbon which compared well with both ZADRA and AARL methods (Soleimani and Kaghazchi, 2008). van Deventer and van der Merwe (1994) studied the functional relationship between the effect of pH, temperature, concentrations of cyanide and cations on the gold cyanide equilibrium during elution from activated carbon in columns and in batch reactors. They identified that the resistance to the mass transfer were less intense under robust elution conditions. It was identified that the elution of aurocyanide was inhibited by the action of cations through the formation of Mn+(Au(CN)2−) on activated carbon. Gold desorption conditions namely high temperatures and intense cyanide pretreatment, decreased the sensitivity of gold elution to flow rate and the radial distribution of the gold through the carbon particles. (van Deventer and van der Merwe, 1994).

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Boshoff (1994) suggested that the elution efficiency is independent of the amount of gold present on the activated carbon. It was proved that cyanide-free elutions of carbons containing < 1 200 g/t copper, are indeed possible and that under these conditions acid wash conditions typically acid concentration could be reduced without a detrimental effect on gold elution efficiency (Boshoff, 1994).

The scope of the performance review of the ZADRA elution circuit, covers from the commissioning year (2009) to the end of 2015. Selected operational parameters and experiences in the running of the circuit are presented in this section. Two sections of performance review are presented; elution start-up (February, 2009 to December 2012) and interventions (January, 2013 to December, 2015). The start-up period mainly discusses the performance of the circuit from its commissioning to the end of 2012. The intervention section, on the other discusses the circuit performance whiles various changes in operational parameters as a result of challenges encountered during the start-up period. For the periods under review, ZADRA elution circuit performance data have been analyzed and presented. Operational parameters considered include gold loaded activated carbon concentration, eluate flow, caustic concentration, elution duration, and stripping and electrowinning efficiencies.

ZADRA and AARL processes are known to be effective in stripping of gold from activated carbon, but both processes suffer from high-energy consumption, high capital costs for pressurized operations, long elution times and the use of concentrations of environmentally obnoxious sodium cyanide (Liebenberg and Deventer, 1997; Soleimani and Kaghazchi, 2008; van Deventer and van der Merwe, 1994).

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Overview of CIL Plant ZADRA design parameters

ZADRA Elution Circuit Performance Review

(GGL)

3.1

The ZADRA elution circuit at the CIL Plant constitute various stages including carbon recovery, acid washing, carbon transfer, column fill, eluant recirculation, elution and electrowinning, carbon cooling and discharge with no cyanide addition. The eluant is continuously circulated through the elution column and the electrowinning cell in series.

Elution Start-up Performance

In the commissioning year, 2009, a total of 270 elutions were performed, over 11 months, representing approximately 24.5 elutions/month as against the design of 30 elutions/month. The number of elutions increased steadily from the month of commissioning to the end of the year. The least number of elutions, 19 was performed in February and the highest, 32 was in December. On the other hand, the strip cycle duration was observed to decrease towards the end of the year. In December, where the highest number of elutions was

The process begins with recovery of loaded carbon into the acid wash vessel, where inorganic foulants are removed using hydrochloric acid. The process consists of circulating about 3% NaOH solution up flow through a stationary bed of loaded activated

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performed, an average of about 16 hours of strip cycle was recorded. The longer the strip cycle the less the number of elutions performed. The NaOH concentration for the year was generally good, recording an average of 3.01% with the least monthly average concentration of 2.78% obtained in February (see Table 2). A general improvement in the stripping and electrowinning efficiency as the year progressed was achieved. It is a common practice to experience fairly low stripping and electrowinning efficiency during start-up of circuits, as it takes some time to obtain optimum operating levels. Much stable efficiencies were observed towards the end of the year. Gold loaded AC stripped over the period (2009) averaged about 1372 ppm. Month average gold loaded AC grade of 1168 ppm was obtained in December, hence the increased number of elutions (32), and the shorter strip cycle period (16.63 hrs.) to compensate 2D Graph 1 for the relatively poor gold loading on the AC.

Table 1 Month Average AC Grade, Stripping and Electrowinning Efficiency Data (2009).

32 Elution duration/Number of elution

LC grade

EC grade

SE

EE

Feb-09

1331.32

164.45

76.96

64.54

Mar-09

1363.78

94.36

86.81

72.53

Apr-09

1366.82

98.70

86.44

72.87

May-09

1199.39

71.17

91.54

76.77

Jun-09

1181.10

46.83

90.03

78.44

Jul-09

1392.51

79.13

95.70

83.53

Aug-09

1502.75

70.04

89.56

83.25

Sep-09

1482.44

74.62

89.64

83.08

Oct-09

1480.19

98.94

92.55

88.07

Nov-09

1420.71

78.60

95.03

91.05

Dec-09

1168.36

79.80

93.26

84.97

Average

1353.58

86.97

89.78

79.92

*LC – gold on loaded AC, EC – gold on eluted AC, SE – stripping efficiency and EE – Electrowinning efficiency.

34

Elution duration Number of Elutions

30

MONTH

After commissioning, the ZADRA circuit faced some challenges, which included excessive metal build-up in eluate, rampant scaling in heat exchangers, blockage of bottom strainers in elution column, excessive pressure build-up, high electrowinning cell feed temperature and poor deposited gold texture and high burn-off.

28 26 24 22 20 18 16

Table

14

Month

12 Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Figure 1 Elution Duration and Number of Elutions Data in 2009 The circuit‘s performance has been summarized in Table 1. It is shown that both stripping and electrowinning efficiencies generally improved across the year (2009). The stripping efficiency showed a much linear trend than electrowinning efficiency, having an R2 value of 0.8631, as against 0.5554 for electrowinning efficiency. The data indicates that stripping efficiency increased steadily between February to July, plateaued between July and September, and increased in November, and thereafter decreased marginally.

Month Average Elution Parameters (2009).

Circuit

Feb-09

NaOH conc., ppm 2.78

Flowrate, m3/h 28.82

Duration, h 18.21

19

Mar-09

3.07

35.66

16.78

23

Apr-09

3.08

37.37

18.36

22

May-09

2.89

38.35

20.80

26

Jun-09

2.87

36.22

21.00

24

Dec

Month, (in 2009)

2

N

Jul-09

3.21

33.05

22.43

23

Aug-09

3.14

33.72

24.18

25

Sep-09

3.27

33.37

17.64

22

Oct-09

3.11

40.65

20.20

27

Nov-09

3.28

37.12

19.33

27

Dec-09

2.83

25.62

16.63

32

Average

3.05

34.54

19.60

25

*N – Number of elutions The excessive metal build-up in the eluate may be responsible for the poor electrowinning efficiencies encountered over the period under review. These metals, predominantly copper (Cu) and nickel (Ni) are competitively deposited on the cathodes of the electrowinning cells, affecting the electrowinning efficiency. The year average of electrowinning efficiency increased from 79.41% to 89.02%

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between 2009 and 2010, and reduced by approximately 9 % in 2011 (Fig. 3). The effect of metal deposition on the cathode of the electrowinning cell was pronounced in 2011. Electrowinning samples were analysed and the results showed significant amount of Cu and Ni were present in the samples (Table 3). The high concentration of these metal species were attributed to co-leaching due to high NaCN concentration used in the CIL circuit.

2.03% reported in June. The low concentrations were mainly as a results of reduction in purity of NaOH supplied. Low caustic (NaOH) concentrations may also haveCustic negative impact on the stripping efficiency. 4.5 2009 2010 2011 Design

Caustic concentration, %

4.0

Table 3 Metal Distribution in Electrowinning Samples at 250 ppm NaCN Set-point (2011). Metal concentration Sample Cu, ppm Ni, ppm PE Start 22.00 3.20 PE Mid 6.88 2.65 PE End 2.9 1.8 LE 3.22 0.5 BE 4.78 0.5 EW Feed 1.00 1.45 EW Tail 0.2 0.5 *PE – Pregnant Eluate, LE – Lean eluate, BE – Barren eluate and EW – Electrowinning

3.5

3.0

2.5

2.0

1.5 Jan Feb Mar Apr May Jun

Jul

Aug Sep Oct Nov Dec

Month

Figure 2 Caustic Concentration Data from 2009 to 2011.

Excessive scaling in heat exchangers was one major challenge the circuit encountered. The scale build up in the heat exchangers impacted on the elution temperature control system hence the extended elution duration. The temperature control system is automated, hence eluant had to be recirculated for a longer period to attain the desired temperature. This also explains why longer elution durations were observed for less number of elutions relative to the design. A year average of 19.89 h was taken to complete approximately 25 elutions/month in 2009.

3.2 Interventions It was realized that the circuit performance was dependent on the optimization of operating parameters. Certain parameters had to be compensated for others, whiles efforts were made to maintain some parameters within plant design levels, especially temperature. Along with parameter changes, improved cleaning and maintenance regimes were instituted to control/minimize some of the identified problems.

Excessive production of fine gold loaded AC at the bottom of the elution column was also a huge challenge the circuit faced. The high attrition rate of the loaded AC led to the problem of ‗blinding‘ especially the bottom strainers of the ZADRA elution column. These near mesh (fine) carbon end up restricting the flow of eluant through the circuit. Very poor eluant flow rates were observed from 2009 to 2010. The month average flow rates were generally < 40 m3/h in 2009 (35.54 m3/h), relative to 64 m3/h per design, whilst in 2010 the average flow rate was 37.54 m3/h.

In order to address the challenges posed by the fine carbon due to attrition, regular strainer clean-up was instituted followed, by changing the mesh size of bottom strainers from 600 µm to 700 µm and as well as changing the carbon recovery screen mesh size to 1000 µm from 700 µm. Investigations into identifying and selecting AC brand with lower attrition rate and high adsorptive capacity were conducted on seven different AC brands by AbakaWood et al. (2014). This was aimed at revising the AC brand being used. PICA AC was thus introduced as it showed optimum attrition rate and adsorption capacity compared to the other brands investigated (Abaka-Wood et al., 2014). PICA AC has been blended with CHEMQUEST AC since the latter part of 2012 to date. These implementations significantly aided in reducing the rate of ‗blinding‘ of the bottom strainers hence improved eluant flow rate. A gradual increase in flow rate can be seen from Fig. 3. The year average solution flow rate increased

Frequent boiling eluate was a norm in the electrowinning cells in the gold room giving rise to a very light and fluffy deposited gold texture and high burn-off after smelting. It is also shown that the average concentration of NaOH used in 2011 was generally lower than in the previous year (Figure 2). Half of the months in the year recorded concentrations < 3.0%, with the least average of

4

22

20

60

50

18

Elution flow rate Elutions/month Elution duration

16 40 14

30

12

generally above 60 (up to 64) m3/h in accordance with design. The year average flow rate in 2014 was approximately 61 m3/h. The least month average in 2014 was approximately 58 m3/h in August. It is important to note that the shorter elution duration, resulted in generally lower gold loading on activated carbon, as the residence time of carbon in the CIL circuit was shortened to keep elution cycle running. The trends in Fig. 4 indicate that the gold loadings on activated carbon decreased significantly after the period when the changes were implemented (that is 2012). The average year gold loading on the AC for stripping was 1558.68 g/t in 2012, which reduced to 1327.67 g/t in 2013, 1159.32 g/t in 2014 and 1145.64 g/t in 2015. Stripping efficiency was affected especially in 2015, where it reduced by about 2.5 %, relative to 90.1% in 2014. Furthermore, an effective eluate cooling system and a strict eluate temperature controls were put in place. Temperature at which eluate reports to electrowinning cells which was initially set at 100 °C, was changed to 110 °C to rid the eluate of all volatiles especially oxygen which is particularly obnoxious to gold deposition at the cathodes. This action not only improved gold deposition but also contributed to the reduction in the overall eluate circulation time. Electrowinning efficiency was fairly constant between 2012 and Graph it2 increased to about 2014 (about 81%), after2Dwhich 86% in 2015. 94

20

1600

10 2010

2011

2012

2013

2014

2015

Stripping/Electrowinning Efficiencies, %

2009

Year

Figure 3 Elution Flow Rate, Number of Elutions/month and Elution Duration Data from 2009 to 2015. Vertical line shows year of implementation of interventions. Furthermore, a bi-weekly eluate ‗bleed-off‘ and monthly complete eluate change-out regimes were instituted which improved stripping efficiency and consequently reduced gold grade on eluted carbon drastically. This also improved the rate of temperature rise to its set point in the elution column. A bi-weekly sulphamic acid treatment of heat exchangers was also instituted which also reduced the regular heat exchanger bundle changeout time of 3 to 8 months at the oil side and 4 to 12 months at the solution side of the heat exchanger. It was observed that the elution column pressure and the flow had an inverse relationship. This is maintained by a process control valve. With a high set point (intending to be a pressure ZADRA) of 350 kPa, the flow could not exceed 40 m3/hr. The excessive pressure also forced so many near-mesh size carbon particles into the elution column bottom strainers thereby restricting the flow of eluate through the column from the heat exchangers. The pressure set point was thus reduced to 120 kPa. This also contributed massively to optimizing the elution flow rate. In 2014, the month average flow rate was

Stripping Efficiency Electrowinning Efficiency LC Grade

92

1500 90 88

1400

86 1300

84 82

1200 80 78 2008

2009

2010

2011

2012

2013

2014

2015

1100 2016

Year

Figure 4 Electrowinning Efficiency, Stripping Efficiency and Gold Loaded Carbon Grade Data from 2009 to 2015. Vertical line shows year of implementation of interventions.

In effort to reduce the levels of metal impurities that affect electrowinning efficiency and gold deposition, the NaCN concentration set-point for leaching at the CIL circuit was reduced to 200 ppm, with gold recovery unaffected. However, the concentration of Cu and Ni in 5

Gold Loaded Carbon Grade, ppm

70

Elution duration, h

Number of elutions per month / Elution flow rate

significantly from 2012 to 2014 and decreased marginally in 2015. The year average flow rates recorded were 39.54, 53.52, 61.18 and 54.92 m3/h for 2012, 2013, 2014 and 2015, respectively. The increase in the flow rates also resulted in increase in the number of elution cycles conducted, as the increased flow rate reduced the elution duration. With the exception of 2013, between 2012 and 2015, the number of elutions conducted were more than 30 per month. An average of 40 elutions/month were conducted in 2014, whiles 43 elutions/month was achieved in 2015. The least year average within this period was 28 elution/month in 2013 (due industrial action for 2D2 Graph months), whilst 30 1 elution/month was conducted in 2012.

assurance on reagents used must also be ensured. Adherence to the cleaning regimes as instituted should be ensured to minimize the production of scales, especially in heat exchangers.

electrowinning samples analysed were lower compared to that presented in Table 3.

Table 4 Metal distribution in electrowinning samples at 200 ppm NaCN set-point Sample PE Start PE Mid PE End LE BE EW Feed EW Tail

References

Metal concentration Cu, ppm Ni, ppm 9.5 1.06 4.81 0.89 2.35 0.58 0.26 0.07 0.09 0.05 0.69 0.11 0.14 0.09

Abaka-Wood, G.B., Asamoah, R.K. and Abbey, C.E., (2014), "Comparison of Selected Activated Carbon Brands‘ Characteristic Properties for Gold Adsorption – A Case Study at Goldfields Ghana Limited (GGL), Tarkwa Mine", 3rd UMaT Biennial International Mining and Mineral Conference, Tarkwa, Ghana pp. 187-191. Anon, (2016), "Elution and Carbon Reactivation", Metalliferous Mining - Processing, 19 pp. Aylmore, M.G. and Muir, D.M. (2001), "Thiosulfate leaching of gold—a review", Minerals Engineering, 14(2): 135-174. Boshoff, P.T.E., (1994), "Cyanide-free AARL elutions are feasible", Minerals Engineering, 7(2): 251-264. Grosse, A.C., Dicinoski, G.W., Shaw, M.J. and Haddad, P.R., (2003), "Leaching and recovery of gold using ammoniacal thiosulfate leach liquors (a review)", Hydrometallurgy, 69(1): 121. Liebenberg, S. and Deventer, J.V., (1997), "Evaluating a dynamic model for the competitive elution of gold and base metals from activated carbon", Separation science and technology, 32(11): 1787-1804. Robles, A.T., (2001), "Process for eluting precious metals from activated carbon", Google Patents. Soleimani, M. and Kaghazchi, T. (2008), "Gold recovery from loaded activated carbon using different solvents", Journal of the Chinese Institute of Chemical Engineers, 39(1): 9-11. Syed, S., (2012), "Recovery of gold from secondary sources—a review", Hydrometallurgy, 115: 3051. Van Deventer, J. and Van der Merwe, P. (1995), "Kinetic model for the decomposition of cyanide during the elution of gold from activated carbon", Separation science and technology, 30(6): 883-898. van Deventer, J.S.J. and van der Merwe, P.F., (1994), "Factors affecting the elution of gold cyanide from activated carbon", Minerals Engineering, 7(1): 71-86. Wan, R.Y., Le Vier, M. and Miller, J.D. (1993), "Research and development activities for the recovery of gold from non-cyanide solutions", SME Conference, Salt Lake City, Utah, pp. 415-436. Yalcin, M. and Arol, A.I. (2002), "Gold cyanide adsorption characteristics of activated carbon of

4 Key findings and Conclusions The ZADRA elution circuit was characterized by fluctuations in eluate flow, production of fine AC from gold loaded AC, low desorption rate and excess column pressure. Stripping and electrowinning efficiencies were generally poor, hence their concomitant effect of prolonged stripping cycle. The system produced poor textured deposited gold and high-burn off, due to the presence of other metals and volatile matter. Optimization of NaCN concentration used in the CIL circuit was necessary in reducing the levels of Cu and Ni that pose threat to gold deposition on the cathodes of the electrowinning cells. Regular strainer clean-up, changing of the mesh size of bottom strainers from 600 µm to 700 µm and also changing the recovery screen size to 1000 µm from 700 µm, was necessary to control and/eliminate the problems posed by fine carbon. Scaling in heat exchangers was controlled with the introduction of the bi-weekly sulphamic acid treatment (de-scaling). The elution column pressure and flow rate have inverse relationship. With a high pressure set point, the elution flow rate could not exceed 40 m3/h, hence reduction in the pressure set point saw the flow increasing up to 64 m3/h in accordance with design. The temperature of eluate reporting to the electrowinning cell was set to 110 °C to eliminate significant amount of volatiles especially oxygen.

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Recommendations

An effective eluate cooling system and a strict eluate temperature controls must be adhered to, to ensure that the right levels of temperature and pressure are attained. Strict and regular quality control and

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non-coconut shell origin", Hydrometallurgy, 63(2): 201-206.

Authors

Martin Beyuo, CIL and Extraction Superintendent at Gold Fields Ghana Limited, Tarkwa. He obtained both MPhil (2013) and BSc (2005) degrees in Minerals Engineering from the University of Mines and Technology (UMaT), Tarkwa. He has worked as an Assay Technician at Precious Minerals Marketing Company Limited (PMMC), Ghana (1996-2005). His research interests are in CIL operations and gold desorption from activated carbon. George Blankson Abaka-Wood, PhD candidate at the Future Industries Institute of the University of South Australia, Australia. He holds a BSc degree in Minerals Engineering from the University of Mines and Technology, Tarkwa (2011). He was a research assistant at Process Innovation, Ghana (2011). George, worked as a Metallurgist at the CIL Plant of Gold Fields Ghana Limited, Tarkwa Mine (2012 – 2014). His research interests are in Rare earth elements minerals beneficiation, Comminution and CIL plant optimization issues.

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