kromit-imps-yayin.pdf

Proceedings of 14th International Mineral Processing Symposium – Kuşadası, Turkey, 2014

183

INVESTIGATION OF THE ENRICHMENT POSSIBILITIES OF

TEKCROM MINING COMPANY TAILINGS

Hüseyin Vapur1, a

, Soner Top1, Seda Demirci

1

Yusuf Develi2 and Ayhan Ali Sirkeci

3

1. Cukurova University Adana, Turkey

2. Teckrom Mining Company, Hatay, Turkey

3. İstanbul Technical University, İstanbul, Turkey

a. Corresponding author ([email protected])

ABSTRACT: In this research, hand sorting tailings of the chromite plant, Tekcrom

Mining Company, located in Hatay/Turkey were used. The samples were investigated by

gravity methods to determine enrichment possibilities. Shaking table and MGS (Multi

Gravity Separator) experiments were performed as processing methods. After grinding,

while the samples whose particle sizes are over +53 µm were tested at the shaking table,

the other sample -53 µm were tested at MGS. The samples worked at the shaking table

tests were divided into four dimensional fractions as -1000+500 µm, -500+212 µm,

-212+106 µm and -106+53 µm. The samples had -500+212 µm dimensions were able to

enrich 48.87% Cr2O3 grade with 68.97% total concentrate yield by shaking table tests as an

optimum value. In the MGS experiments, a concentrate with 44.78% Cr2O3 grade and

71.94% recovery yield was obtained by optimum conditions (200 rpm, 2° drum slope, 15

mm amplitude, 10% solid ratio with 2 L/min flow rate with wash water).

1. INTRODUCTION

Chromite ores, which is one of the most

important raw materials of metallurgy

and chemistry industries, are mostly

beneficiated by gravity separation

methods such as shaking table, MGS,

Humprey spiral and jigging due to

density difference between chromites and

gang minerals. Besides, magnetic

separation methods are applied to

chromite ores because of the high

magnetic susceptibility of the chromites.

A lot of chromite beneficiation researches

were performed by using gravity and

magnetic separation methods [Wills,

1985; Burt, 1987; Cicek and Cocen,

2002; Agacayak et al., 2007; Aslan and

Kaya; 2009]. Usage area of chromite ores

depend on Cr:Fe ratio. The ores which

have Cr:Fe>2.8 ratio are suitable for

metallurgical uses while the ores which

have Cr:Fe of 2.8-1.8 ratioare suitable for

refractory making. The other chromite

ores are processed by chemical industry

[Tripathy et al., 2012]. Generally,

Turkish Chromite ores have high Cr:Fe

ratio. 2013 proved to be a year of

expansion for the chrome industry.Global

ferrochrome output reached a new record

high in 2013, at 10.8 million tonnes.

Ferrochrome output volume expanded

sharply in China, which confirmed its

position of the world's greatest

ferrochrome producer by manufacturing

around 4 million tonnes of material in

2013 [ICDA, 2014]. Chromite ore

production by regions is seen in Figure 1.

Turkey is the sixth largest chromite ores

exporter in the world. These ores have

been mined from mostly serpentinized

ultramafic bodies, discontinuously

spreaded all over the country [Agacayak

et al., 2007]. Chromite deposites in

Turkey are alpine (podiform) type and

their formation is generally observed in

the east-west direction. As a result of

intense tectonic activities, various ore

types such as massive, banded, leopard

skinchromites were formed. The

184

accompanying secondary minerals found

in Turkish chromite deposits are dunite,

harzburgite, olivine, serpentine and talc

[Onal et al., 1986].

Ophiolites of the Southeastern Turkey

occur along the border folds belt forming

the northern boundary of the Arabian

plate. They extend along an ophiolitic

zone between the Troodos (Cyprus) and

the Semail ophiolite (Oman) which, at

least at the first glance, poses

implications about the existence of a

southerly ocean, with respect to the major

North Anatolian ophiolite belt, in the

Eastern Mediterranean.In the western end

of this zone, the second ophiolite after the

Troodos is the Kızıldağ ophiolite. It is the

most complete and the best preserved

ophiolite among the Turkish ophiolites.

The Kızıldağ ophiolite nappe has been

emplaced upon the thick autochthonous

Cambrian to Cretaceous shelf section that

characterizes the Arabian Peninsula

[Tekeli and Erendil, 1986]. Working area,

which is located in Hatay/Turkey, is in

formation of the Kızıldağ ophiolite.

In Turkey, chromite ores concentration

plants are mostly limited by shaking table

applications. Because of the fluctuations

related to China’s purchasing power in

chromite prices, chromite companies tend

to sell lump chromite ores. Hand sorting

method has an important place in the

lump chromite ores production.

Figure 1.Chrome ore production by region [ICDA, 2014]

2. MATERIAL and METHOD

2.1. Materials

In Tekcrom Mining Company Plant, the

chromite ores are extracted by open pit

and underground mining methods. Then,

lump chromite ores over 42% Cr2O3

grade are picked by hand sorting method.

Hand sorting tailings are stocked up to

storage area. The sample, approximate

300 kg, was taken from the area stocked

over 400000 tons of tailings in this

company. Also, there are other

companies produces chromite

concentrates (lump chromite) by similar

route. The samples was brought to the

laboratory and reduced by quartering.

Reduced samples were used in separation

tests and characterization definition

stages.In order to find out

characterization of the tailings, Rigaku

Minflex II X-ray diffractometer (XRD)

was used. According to the XRD results,

the samples consist of antigorite

(serpentine), olivine, chromite,

magnesiochromite and diopside minerals

(Figure 2). Chemical composition of the

tailings were determined by MiniPal-4


185

Figure 2: XRD Pattern of the chromite tailings

Panalytical XRF device and confirmed by

wet chemical analysises and Perkin

Elmer PinAAcle 900 H Atomic

absorption spectrophotometer device.

Chemical composition of the tailings is

seen in (Table 1).

Table 1: Chemical composition of the

tailings

Compound %

MgO 29.09

Al2O3 01.47

Cr2O3 14.55

SiO2 34.16

Fe2O3 17.43

Firstly, tailings were crushed to minimize

particle size under 5mm. Then, dry

grinding tests were applied to the crushed

tailings by laboratory type rod mill. In the

grinding tests, 12 kg of steel rod and 1.0

kg of the crushed tailings was used as

grinding media. The effect of the

different grinding times on grain size of

the tailings is seen in Figure 3. In view

of the size of the grinded materials, 10

minutes grinding time was detected as

convenient comminition time (d80= -650

m.

Figure 3: Effect of grinding time on size

reduction.

2.2. Methods

The samples investigated by processing

methods at the shaking table tests were

divided into four dimensional fractions as

-1000+500 µm, -500+212 µm, -212+106

µm and -106+53 µm. MGS tests were

carried out by using -53 µm fraction. The

laboratory type C900 MGS with a

nominal capacity of 150 kg/h, used for

the test, consists of a slightly tapered

open end drum measuring 0,6 m long

with a diameter of 0,5 m, which rotates in

a clockwise direction (viewed from the

open end) and is shaken sinusoidal in an

A A: Antigorite Cr: Chromite

S: Serpentine O: Olivine

Mg-Cr: Magnesiochromite

D: Diopside

186

20

25

30

35

40

45

160 180 200 220 240 260

Yield

Grade

%

Stroke Number (rpm)

axial direction. Firstly, preliminary

shaking table tests were applied for

ascertaining the variable parameter values

which are table slope, particle size and

stroke number (invariable parameters for

each test are water flow rate: 10 l/min,

feeding weight: 1,0 kg). Besides, 4o table

slope and 202 rpm stroke number were

constant parameters in stroke number and

table slope determining tests,

respectively. Fraction of -106 µm was put

aside for processing tests due to its slime

size. The effects of parameters on the

enrichment were determined by keeping

invariable parameters constant. Then,

design tests for determination of optimum

flow sheets were applied.

3. RESULTS

It can be seen that Cr2O3 yield and grade

of concentrates increased when particle

sizes were decreased in preliminary

shaking table tests with different stroke

numbers (rpm) or frequency. The tests

results applied to -1000+500 µm fraction

indicated that deliberation degree of the

particles was not enough for the

separation of chromite from gangue

minerals. Therefore, there are fluctuations

in Figure 4. Both concentrate grade and

yield values were low in this fraction.

Figure 4: The effect of stroke number

(rpm) on yield (%) at -1000+500 µm

(Figure 5) shows that good quality

chromites (Cr2O3>50%) were obtained,

albeit without high recovery yield at

-500+212 µm fraction. Especially, when

stroke number was 202 rpm, the best

yield percent was obtained (68%).

-212+106 µm fraction, high recovery

yields were achieved although chromite

grade cannot exceed 50% (Figure 6).

Besides, when stroke number was 202

rpm the highest yield percent was

obtained (~ 80%).

Figure 5: The effect of stroke number

(rpm) on yield (%) at 500-212 µm

Figure 6: The effect of frequency on the

beneficiation at -212+106 µm


187

The best result for frequency tests was

obtained at 500-212 µm fraction and 202

rpm frequency with 53.82% Cr2O3 grade

and 68.14% recovery yield. In all of the

tests, if the middling apportioned,

recovery yield would increase.

In table slope determining tests, 3o was

seen fit for coarse particles

(-1000+500 µm) while 4o was preferred

for finer particle sizes as shown in Figure

7, 8 and 9. But grade values of

concentrates were not suitable for as a

saleable product in -1000+500 µm

fraction. It shows that liberation degree is

insufficient (Figure 7). Figure 8 shows

chromite recovery yield and grade of the

concentrate at -500+212 µm fraction. In

this fraction, chromite grade being the

best value at the 4o slope (Cr2O3>50%)

were obtained. In -212+106 µm fraction

slope determining tests, high recovery

yields were achieved with approximate

50% chromite grade (Figure 9).

Processing studies consists of 5 stage

containing shaking table and MGS

methods. As it can be seen in Figure 10,

the recovery process of tailings for

-1000+500 μm were performed in

following flow sheet.

Figure 7: The effect of slope on the

beneficiation at 1000-500 µm fraction





In this size fraction, the rough

concentrate was processed by shaking

table with different slope again.

Scavenger 1 was recovered by processing

tailings and Cleaning 1 recovered from

rough concentrate. Finally, it was

observed that recovery grade was 46,73%

with 28,79% yield. It was shown in

188

(Figure 11) that the grades% of tailings

for -500 +212 μm was reached at

marketable values. But, yields% values

for concentrates were very low except

Concentrate 1 (55.06%). Besides, it was

thought that chromite contents in the final

middling product can be recovered by

slime table with grinding in this fraction.

The recovery process of -212+106 μm

size range is seen in the flow sheet

(Figure 12). It was obvious that the

chromite yields% of this fraction were

better in comparison with -500-212 μm

fraction but not for grades%. The best

chromite grade% was taken from rough

concentrate with %46.39. Desliming was

applied to the -106 μm fraction and -53

μm materials was set aside in order to fed

into MGS while -106+53 μm fraction

was processed by shaking table

(Figure 13).

Figure 10. Shaking table test results for -1000+500 μm

Figure 11. Shaking table processing test results for -500 +212 μm

Tailing Scavenger 1

Tailing

Feeding

Yield%

Weight% Grade%

100

100 6,94

3,41

20,05 1,18

32,63

8,95 25,3

29,17

37,78 5,36

5,97

28,95 1,43

Tailing

Final Tailing

Concentrate

Middling Scavenger 2

Cleaning 1

Slope 4o

Slope 6o

Slope 4o

Slope 2o

28,79

4,28 46,73

27,30

Feeding

Middling

Tailing

2

Tailing

Concentrate 1 Tailing

Concentrate 2

Concentrate 3

Slope 4o

Slope2o

100

100 18,48

1,74

1,18

55,06

20,38 49,94

7,86

3,10 46,88

6,03

2,60 42,89 2,10

22,83 1,70

27,21

23,80 21,13

Slope 4o

Slope 6o

Middling


189

Figure 12. Shaking table processing test results for -212+106μm

Figure 13. Shaking table processing test results for -106+53 μm

The concentrates over 48% Cr2O3 grade

were achieved through this route. It was

seen that chromite contents escaping to

the tailings were more than other size

ranges in this fine fraction. MGS tests

were applied to -53 μm fraction at

different rotational speeds as 270, 230

and 200 rpm consecutively. A

concentrate with 71.94% Cr2O3 grade and

44.78% yield was recovered by following

route (Figure 14).

4. CONCLUSIONS

Present study demonstrates that Teckrom

Mining Company tailings can be

beneficiated by shaking table and MGS.

Different 5 flow sheets processing

different sized material were created with

merchantable concentrate products. There

is no processing plant in this region.

Therefore, ~ 2000000 tons/year

processable tailing has been being

10,55

5,00 42,02

Tailing 1

2,66

40,80 1,30

Feeding

Tailing 2

Concentrate 1

Concentrate 2

Concentrate 3

Middling

Slope 2o

Middling

23,56

10,88 43,16

Shaking Table

Slope 4o

100

100 19,92

43,55

18,70 46,39

Slope 2o

0,70

7,28 1,93

18,97

17,35 21,78

Desliming

(53μm)

Slope 2o

Slope 2o

Middling

Slope 2o

100

45 13,19

-53μm to

MGS

Tailing 1

11,54

6,06 34,54

Feeding

100

100 15,91

100

55 18,14

+53μm to

Shaking Table

Tailing 2

8,05

21,05 6,94

Concentrate 1

23,54

8,55 49,96

Concentrate 2

23,87

8,93 48,47

Middling 2 33,00

26,94 22,22

190

Figure 14. MGS processing test results for -53μm produced from several chromite plants,

locally. It is obvious that if this tailings is

economically recovered with suitable

processing method, it will be contributed

to national economy.

Acknowledgements: This study was

supported in part by Cukurova University

(Project Code: MMF2011YL13).

REFERENCES Agacayak, T., Zedef, V. and Aydogan, Ş., 2007.

Beneficiation of Low-grade Chromite Ores

of Abandoned Mine at Topraktepe,

Beyşehir, SW Turkey,

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323-327.

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Chromite Tailings, Research Project, ITU;

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Dogan Z.M., NATO ASI Series E: Applied

sciences-No. 122, 106-137.

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Mozley Gravity Separator (MGS) to Fine

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Concentrating Plants, Minerals Engineering,

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ICDA, 2014. International Chromium

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05.06.2014;

http://www.icdacr.com/index.php?option=co

m_content&view=article&id=578&Itemid=6

98&lang=en).

Tekeli, O. and Erendil, M., 1986.Geology and the

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Bulletin of the Mineral Research &

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21-37.

Tripathy, S. K., Singh, V. And Ramamurthy, Y.,

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Chromite Ore for Ferro Chrome Production,

International Journal of Mining Engineering

and Mineral Processing, I(3), pp. 101-106.

Wills, B. A., 1985. Mineral Processing

Technology, 3rd edition, Pergamon Press,.

Feeding

MGS 270 rpm

MGS 230 rpm

MGS 200 rpm

Middling 12,14

11,91 13,44

100

100 13,19

Tailing 1

9,04

38,44 3,10

Tailing 2

1,99

12,36 2,12

Tailing 3

4,91

16,10 4,02

Concentrate

71,94

21,19 44,78

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