beneficiation of low-grade turkish manganese ore

Paper No. 177

BENEFICIATION OF LOW-GRADE TURKISH MANGANESE ORE O Güven1,*, F Burat2, O Kangal3 and N Acarkan4 ABSTRACT In recent years, there is an increasing demand on manganese consumption which stems from the important role of manganese in carbon steel production. And the growing need for manganese ores makes the beneficiation of low-grade manganese ores more economical. In this study, the characterization and beneficiation studies were carried out to propose a flow sheet for typical lowgrade Turkish manganese ores. For this aim, different gravity separation methods were applied. According to the mineralogical analysis, the major mineral phases are pyrolusite (MnO 2) and psilomelane (MnO2) while the major gangue mineral is radiolarite. Gravity separation tests were accomplished by using jigs, shaking table, MGS (Multi Gravity Separator) and in order to obtain products with high Mn ratio, high intensity magnetic separation was also performed. As a result, different combinations of flow sheets were utilized and a concentrate assaying 56.5% Mn with 85 % recovery was obtained. Keywords: Manganese, Jigs, MGS

1. INTRODUCTION There is an increasing demand for manganese ore, considerably due to the increase in the manufacture of steel over the years and the increasing scarcity of natural resources (Xin et al, 2009, Xin et al, 2011). A shortage of high-grade manganese ores in international markets still exist for carbon steels and this situation has led to price gains for both manganese ores and alloys (Doshi, 2007). And in order to provide this demand for ferro alloys, there will be a huge requirement for manganese ore for steel production. Considering the rapid growing demand for manganese, the beneficiation of low grade manganese ores become more economical (Acharya et al, 2003). In total production of world, approximately 95 % of manganese is used in steel making processes to form ferro-manganese-alloys because without the addition of manganese, steel cannot be produced in desired quality (Acharya et al, 2003). In steel production, the role of manganese ore is to provide unique deoxidizing and desulfidizing agent. The processing of manganese ores is dependent upon the Mn content of the ore where high grade manganese ores are processed into suitable metallic alloy formed by pyrometallurgical processes, the hydrometallurgical processing of low grade manganese ores is performed after conventional pyrometallurgical reductive roasting for the manufacturing of chemical manganese dioxide (CMD) or electrolytic manganesedioxide (EMD) (Zhang, 2007). For instance, EMD production in 2010 is 422.500 Mt/year with an increasing growth rate compared to previous years depending on the usage of EMD on batteries. Considering these situations, manganese ore is typically classified into three grades based on the manganese content of the ore. High grade ores contain 44–48% and above while medium and low grade ores contain 35–44% and 25–35% and lower Mn respectively (Acharya et al, 2004). For beneficiation of manganese ore, gravity separation techniques can be used to remove nonferrous gangue minerals but additionally high intensity magnetic separation is required to obtain products with high Mn ratio in the concentrate (Huaming and Guanzhou, 1998; Singh et al, 2011). In this study, the characterization and beneficiation studies have been carried out for increasing the Mn content in concentrate while proposing a flowsheet for utilizing low-grade manganese ores. 1. Istanbul Technical University, 34469 Maslak/Istanbul, Email: [email protected] 2 . Istanbul Technical University, 34469 Maslak/Istanbul, Email: [email protected] 3 . Istanbul Technical University, 34469 Maslak/Istanbul, Email: [email protected] 4 . Istanbul Technical University, 34469 Maslak/Istanbul, Email: [email protected] XXVI INTERNATIONAL MINERAL PROCESSING CONGRESS (IMPC) 2012 PROCEEDINGS / NEW DELHI, INDIA / 24 - 28 SEPTEMBER 2012

GÜVEN ET AL

2. MATERIALS Representative samples were collected from Kilis region, Turkey. The chemical analysis of the samples is given in Table 1. The mineralogical and petrographic analysis reveals that major mineral phases are pyrolusite (MnO 2) and psilomelane (MnO2) while the major gangue mineral is radiolarite. The mineralogical analysis also suggested, that the coarser size of pyrolusite minerals is approximately 0.5-0.6 mm. In the transition region of ore and gangue mineral, the size of the pyrolusite crystals are getting finer, even in microns. In addition, the radius of the main gangue mineral “radiolarite” is found as 75-80 microns, while it is grown as pins in pyrolusite crystal structure. In order to determine the distribution of Mn content, fractional analysis were performed and the results were shown in Table 2. In Jigging tests, laboratory type Hartz Jig was used and shaking table tests were carried out with Wilfley Shaking Table here. Table . Chemical Analysis of received sample Compound

%

Mn

14.10

Al2O3

2.03

SiO2

70.59

Fe2O3

1.37

P

0.094

Other

11.82

Mn/Fe

10.29

Table . Fractional analysis of received sample Size, mm

Weight, %

-9+6

Mn, % Content

Distribution

30.3

14.17

31.1

-6+4

21.5

14.65

22.8

-4+2

25.4

13.77

25.3

-2+1

10.1

12.91

9.4

-1+0.5

6.3

11.75

5.3

-0.5

6.4

13.29

6.1

Total

100.0

13.83

100.0

3. METHODS Increasing Manganese content in concentrate is the most challenging aspect of beneficiation studies. Therefore various gravity methods including jigging, shaking tables and magnetic separation were applied for beneficiation of manganese ore. A combination of jig and shaking tables was tested to beneficiate the manganese ore. The coarser fraction (-9+6, -6+4 and -4+2 mm) was upgraded by Hartz jig and fines of -2+1, -1+0.5 and -0.5 mm were beneficiated by shaking table. On the other hand, finer fraction (-0.053 mm) were then treated with MGS (Multi Gravity Separator) for recovering the Mn content. As mentioned in introduction section, the major manganese mineral is pyrolusite. Depending on the paramagnetic feature of pyrolusite and other oxide type manganese minerals, magnetic separation tests were tested for searching the possibility of obtaining a saleable concentrate. For this aim, magnetic separation tests were carried out with the same fractions as studied by jig and shaking table, -9+6 mm, -6+4 mm, -4+2 mm, -2+1 mm and -1+0,5 mm by lab scale high intensity induced roll magnetic separator. XXVI INTERNATIONAL MINERAL PROCESSING CONGRESS (IMPC) 2012 PROCEEDINGS / NEW DELHI, INDIA / 24 - 28 SEPTEMBER 2012

BENEFICIATION OF LOW-GRADE TURKISH MANGANESE ORE

4. RESULTS AND DISCUSSION According to the results of jigging tests shown in Table 3, Mn content of the products was increased in proportion to the decrease on size. From that point of view, it can be understood that the liberation size of this ore sample is under -2 mm. However, depending on the specifications of jig instrument and characteristics of ore, jigging would not be efficient for beneficiation and therefore shaking table were performed for ore under 2 mm. Table . The results of jigging tests Size Range,mm

-9+6

-6+4

-4+2

Products

Weight, %

Concentrate

Mn, % Content

Recovery

34.0

37.84

85.7

Middlings-1

28.9

4.34

8.3

Middlings-2

16.1

2.41

2.6

Tailings

21.0

2.42

3.4

Total

100.0

15.03

100.0

Concentrate

29.0

43.01

86.9

Middlings-1

14.5

4.59

4.6

Middlings-2

30.5

2.25

4.8

Tailings

26.0

2.02

3.7

Total

100.0

14.35

100.0

Concentrate

23.3

50.57

79.4

Middlings-1

18.5

9.67

12.1

Middlings-2

24.6

2.54

4.2

Tailings

33.6

1.90

4.3

Total

100.0

14.84

100.0

Shaking table tests were carried out with -2+1; -1+0.5; -0.5+0.053 mm size fractions. Additionally, before all tests, sample under 0.053 mm was removed in order to prevent the effect of slime and enhance the recovery under these series of tests. The results of shaking table tests also show the similar tendency with the results of jigging, that the Mn content of the concentrate is increasing with respect to the decrease on feed size (refer Table 4).

XXVI INTERNATIONAL MINERAL PROCESSING CONGRESS (IMPC) 2012 PROCEEDINGS / NEW DELHI, INDIA / 24 - 28 SEPTEMBER 2012

GÜVEN ET AL

Table . The results of shaking table tests Size Range,mm

Products

Weight, %

Concentrate

Mn, % Content

Recovery

5.9

50.10

21.1

Middlings-1

10.5

11.32

8.5

Middlings-2

19.7

7.91

11.1

Tailings

6.4

2.62

1.2

Concentrate-1

2.6

54.66

10.1

Concentrate-2

0.9

53.98

3.5

Middlings

10.3

7.36

5.4

Tailings

7.3

2.52

1.3

Concentrate-1

2.3

59.15

9.7

Concentrate-2

2.0

58.96

8.4

Concentrate-3

1.3

53.09

4.9

Middlings

6.4

10.62

4.8

Tailings

18.4

2.55

3.3

Slime

6.0

15.65

6.7

Total

100.0

14.04

100.0

-2+1

-1+0.5

-0.5+Slime

As can be seen from Table 5, a concentrate assaying 44.72 % Mn content with 88.8 % recovery was obtained by combination of jig and shaking table tests. Table 5. The combined results of Jigging and shaking Table tests Method

Jig + Shaking Table

Products

Weight, %

Concentrate

Mn, % Content

Recovery

24.9

44.72

76.8

Middlings

29.8

7.81

16.0

Tailings

45.3

2.29

7.2

Total

100.0

14.50

100.0

The beneficiation of ore under fraction below 0.053 mm was utilized with MGS. The results of these tests were shown in Table 6. Table 6. The results of MGS tests Products

Weight, %

Concentrate

Mn, % Content

Recovery

27.4

7.15

44.0

Middlings

48.3

4.03

43.7

Tailings

24.3

2.25

12.3

Total

100.0

4.45

100.0


BENEFICIATION OF LOW-GRADE TURKISH MANGANESE ORE

Magnetic separation tests was applied to both coarse and fine size fractions as -9+4 ; -6+4; -4+2; -2+1; -1+0.5 mm and the results of these tests was shown in Table 7. Table 7. The results of magnetic separation tests Size Range, mm

Products

Weight, %

Magnetic Product

Mn,% Content

Recovery

3.8

50.39

13.7

Middlings

3.0

22.89

4.8

Non-Magnetic Product

11.9

2.15

1.8

Magnetic Product

1.1

55.87

4.5

Middlings

3.5

42.71

10.4


14.1

3.01

3.0

Magnetic Product

2.6

51.89

9.6

Middlings

2.7

31.51

5.9


13.5

2.85

2.7

Magnetic Product

4.5

47.15

15.0

Middlings

2.5

12.71

2.2


11.7

2.11

1.7

Magnetic Product

4.7

41.64

13.8

Middlings

5.2

10.69

3.9


8.8

1.54

1.0

-0.5

6.4

13.29

6.0

Total

100.0

14.16

100.0

-9+6

-6+4

-4+2

-2+1

-1+0.5

In jigging and shaking table tests, it was found that the Mn content of the concentrare was increasing upon the decrease on feed size, however in magnetic separation tests, it was found that higher Mn content could also be obtained in coarser sizes where a decrease in Mn content was obtained in proportion to the decrease on feed size. This can be attributed to the difference on beneficiation principles where in gravity separation methods, the major point is the liberation size and the difference on density, in magnetic separation, liberation size is completed with the difference on magnetic features of the ore. From that point of view it can be understood that the beneficiation method is also effective on the products characteristics involving content and recovery.

5. CONCLUSIONS 1. The mineralogical analysis indicated, that pyrolusite involves the valuable mineral of the ore and psilomelane is associated with pyrolusite. The gangue mineral of the ore is formed with radiolarite fossils. 2. The results of beneficiation studies carried out under 9 mm showed, that the liberation size of the ore is under 1 mm. 3. The results of jigging tests performed under 9 mm size, indicates that a concentrate assaying 42.15 % Mn content could be obtained with 85 % recovery. 4. For beneficiation of manganase ore, a series of tests were also utilized with shaking table tests and the results performed under 2 mm, a concentrate assaying 53.76 % Mn content with 70 % recovery could be obtained.


GÜVEN ET AL

5. The results of gravity separation tests (combined), the enrichment ratio became 3.57 and the recovery of Mn is 86.5 % in process scale while 89.2 % in experimental scale. 6. As a result of magnetic separation, tests perfomed with the size fraction of -9+2 mm, a concentrate assaying 49.51 % Mn content with 68.5 % recovery ratio. 7. For beneficiation of manganese ore, magnetic separation was applied to the sample at the size range -9+2 mm however for increasing the content and the recovery ratio of products, sample under 2 mm was also enriched with shaking table and the Mn recovery ratio became 80.4 %. 8. Considering all results, it was understood that, a manganese ore assaying at least 10 % Mn content can be economically beneficiated but as to make gain from beneficiation, manganese ore assaying at least 20 % Mn content is needed.

REFERENCES Acharya, C, Kar, R N, Sukla, L B, 2003. Studies on reaction mechanism of bioleaching of manganese ore, Miner. Eng. 16, 1027–1030. Evaluation strategies for sedimentary phosphates with siliceous and carbonates gangues. Minerals Engineering Vol. 13 No.7 pp. 789-793. Acharya, C, Sukla, L B, Vibhuti, N, 2004. Fungal leaching of manganese ore. Trans. Indian Inst. Met. 57, 501– 508.Upgrading of calcareous phosphate ores by flotation: effect of ore characteristics. International Journal of Mineral Processing, pp. 81-89. Doshi, J, 2007. Bioleaching of lateritic nickel ore using chemolithotrophic micro organisms (Acidithiobacillus ferrooxidans), http://ethesis.nitrkl.ac.in/1541/1/Jayesh.pdf. Huaming, Y, Guanzhou, Q, 1998. Fabrication and application of ferromanganese composite briquette. J. Cent. South University. Technology 5 (1), pp. 7–10. Singh, V, Tamal, K G, Ramamurthy Y, Tathavadkar, V, 2011. Beneficiation and agglomeration process to utilize low-grade ferruginous manganese ore fines. International Journal of Mineral Processing, 99 pp. 84–86. Xin, B P, Zhang, D, Zhang, X, Feng, W, Li, L, 2009. Bioleaching mechanism of Co and Li from spent lithium-ion battery by the mixed culture of acidophilic sulfur oxidizing and iron-oxidizing bacteria, Bioresour. Technol. 100, pp. 6163–6169. Xin, B, Chen, B, Duan, N, Zhou, C, 2011. Extraction of manganese from electrolyticmanganese residue by bioleaching, Bioresour. Technol. 102, pp. 1683–1687. Zhang, J S, 2007. Current challenge and chance in China’s Mn-industry”, China Manganese Indust. 1, pp. 6–9.
