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Abstract

This summer practice was done in ET Copper Inc., Kre. The main object of the

practice was understanding and witnessing the mineral processing operations by the

first eye. Kre has got one of the best processing plants in Turkey and it is operated

by an important company. There was also another choice in ET Copper Inc., which

covers the underground mining operations, but after doing the first summer practice

about surface mining, my second choice became mineral processing in order to see

also the development and enrichment of the extracted materials in the mines before

sending them to the market. The practice is basically about five different stages of the

processing operations. These are primary crushing, secondary crushing, grinding,

flotation and dewatering. In every part, besides operations, also the used machinesor materials etc. were studied. There is also a personal study part of this report which

is about a series of flotation experiments. They were real processing experiments

and the management used some of the results and informations that we found. In

conclusion, the 20 days spent in the management were full of learning, practice,

examining and surprising.

Acknowledgement

The company has changed its vision a bit during the past couple of years. They are

working with a young and dynamic team nowadays. We have met with four engineer

(one of them was the plant manager) and they were under 33-34 years old. The

relationship with the engineers or workers is very important for the trainees. It can be

said that this relationships can effect all the summer practice and can be the reason

of learning something from it or not. The Black Sea Region people were very kind

and hospitable, they deserve special thanks. The trainees were sharing the dorms

with that people (generally workers of the management) and the relations both during

schedule hours and after work were extremely joyful. As a trainee, we didnt come up

with any problems about this subject. As mentioned, there was a young team of

engineers in the processing operations. They did their best for teaching us something

new or showing the operations by the first eye. Their help was not only about the

management or about mineral processing, but also about the job, mining engineering

and its problem sor benefits etc. ET Copper Inc. is an important management and

the trainees of it were the lucky ones. All the clothes, equipment etc. were ready for


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the trainees, they were new and helpful for the whole summer practice. Also, the

content of the personal study in this report is about some flotation experiments and

Ar-Ge engineers helped us while experiencing them.

Introduction

The word mining refers to extracting the valuable minerals, rocks etc. from the

earths crust in many persons mind. But mining doesnt end after extracting the

minerals from the earth, the operations after getting the minerals outside are as

important as the first part. This summer practice report is about the second part

mining, namely mineral processing. Mineral processing is the enrichment of the

minerals by crushing them, grinding them or floating them, shortly liberating them. It

is about the gaining of the valuable and useful pieces in the extracted material.

Mineral processing is kind of bridge between the mines and the marketing. It is the

area of which the financial considerations are directly affecting the decisions. The aim

of this practice and report is witnessing these operations and learning some of the

details or key points fort he job. If an engineer candidate wants to work in the mineral

processing field after graduation, he/she has to make one of his/her practices in a

processing plant. This report is examining the operations step by step, from starting

with the primary crushing and ending at the dewatering unit. The management has a

lot of building for the operations of course, there was not a single building in which all

the works can be done easily and at one time. Therefore, besides the operations, this

report also examines the machines which are directly or indirectly affects the

operations. For example, crushers are the major objects for the crushing and

downsizing works in the first stage, but it is also very important to observe and report

the conveyors which are some kind of vehicles and they carry the material between

each unit. This is just one example. The machines and their properties are also

placed in this report. At the beginning of the report, the structure of the ore is studied

in detail. Of course we have to know what we are dealing with before starting to

processing it. After observing the whole processing plant and works, in the final part

of the report, a personal study takes place. This study is the result of a series of

flotation experiments. The flotation part is counted as the most important and difficult

part of the processing operations. The personal study asks the question of: Which

one will be more effective? The experiments are covering the addition of lime to thematerial before flotation. There are three experiments and in each of them, lime was


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added to the material in different times. The aim is observing the results according to

the behaviour of flotation. The report is ending with a conclusion part, and then the

references of some informations. Some photographs taken by myself is taking place

in Appendix.

Company Information

Kre concentrating facility was founded in 1973 in order to benefit from the copper

orebodies in Black Sea Region. 1.000.000 tonnes of copper aggregate (touvenant

copper), 90.000 tonnes of copper concentrate, 400.000 tonnes of pyrite concentrate

are produced in this facility in a single year. There are 3 surface and 1 underground

mining operations which are now active. Nearly 250 employees are placed in the

facility. Workings such as modernization, increasing the capacity and finding new

orebodies are continuing.

Kre Mining Areas passed to MTA in 1939 and then coppered pyrite (chalcopyrite,

CuFeS2) orebody was discovered in the area by the geological and geophysical

drilling methods by Etibank in 1963. In 1968, the area this time passed to Black Sea

Copper Managements. Firstly, the produced copper ore was being delivered as only

raw material but later, after the foundation of Etibank Coppered Pyrite Managements

in 1987, it started to be delivered as copper and pyrite concentrations seperately.

Following, area was passed to Etibank Coppered Pyrite Managements in 1991.

Between 1991-1998, the management kept working under that name, but in 1998 it

turned out to Eti Copper Inc. Finally, it was bought by Cengiz Holding in 2004 inside

the privatization project.


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http://www.etibakir.com.tr/default.asp

Physical Properties

Bulk Density =2,2 gr/cm3

Particle Size

+ 200 mesh =% 4,00

-200 + 270 mesh =% 5,00-270 + 400 mesh =% 16,00

- 400 mesh =% 75,00

Delivery Conditions

Kre Copper Concentrate can be transported as bulk load. The material is

transported to nebolu Port according to the contracts made.

Pyrite Concentrate
http://www.etibakir.com.tr/default.asphttp://www.etibakir.com.tr/default.asphttp://www.etibakir.com.tr/default.asp


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Physical Properties

Bulk Density =2,4 gr/cm3

Particle Size

-75 mikron : 78-82 %

-53 mikron : 68-72 %

-38 mikron : 50-55 %

Delivery Conditions

Kre Pyrite Concentrate can be transported as bulk load. The material is transported

to nebolu Port according to the contracts made.

Structure of the Ore

The main ore minerals are pyrite and chalcopyrite in Kre. Many other rock types can

also be seen but they are generally not in large amounts. Some examples are

hematite, sphalerite, limonite, marcasite, galenite, bornite, basalt, fahlerz, bravoyite,

rutile, chromit, magnetite and digenite. Naturally, the grades of these minerals are

changing from drilling to drilling because the structure is changing from location to

location. But it is for sure that the actual aim of the facility is producing pyrite and

chalcopyrite. Copper (Cu) and Pyrite (FeS2) are obtained from Chalcopyrite (CuFeS2)

at the end of many liberating and concentrating processes. The extracted and

concentrated pyrite and copper are stocked separately and then sent to nebolu Port

by trucks for transporting to Samsun by the seaway.


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Quartz, chlorite, carbonate minerals are the main gangue minerals extracted

from the mine.

Once upon a time, there was a very efficient surface mine in the area called

Bakibaba and the extracted material had a grade of 16-18 %. But the ore here ran

out in 2009 so the management cant benefit from Bakibaba now. Drilling operations

are continueing in order to find a new vein. Also, Aky surface mine ran out two

years ago and today reclamation works are taking place. Nowadays, from the

surface, three types of ore are fed to the primary crushers; 2-4 % graded wooded

ore, 0.8-1 % graded impregnated ore (oxidization can be seen because the high

rates of Fe), 4-8 % graded massive ore.

Today, the actual source of the management is an underground mine called

Mara. The ore coming from here has a grade of 2-2.2 %. Cyprus type orebody

formation can be seen in underground mine. There are stil 10 million tonnes of

reserve takes place in Mara mine, this means the mine life will be nearly 10 years

from today. Daily 1500-2000 tonnes of production is done in the management.

However, the facility capacity is about 4000 tonnes.

There is an important situation in primary crushing unit. It is impossible to

liberate the wooden ore into wood and ore separately. Because they lie under the

ground for many years and in a sense their formation has changed, they sticked

together and act as a whole. Therefore, it becomes a different structure. They dont

sink into water for example, also other techniques dont work. But the management

realized that this new formation is harmful for the facility. Especially in the flotation

process, the resin of that woods causes over-frothing. So, the engineers found a

solution that, if they mix the wooden ore with the ore coming from underground mine

(Mara) and do not put it directly into processes, the problem vanishes. Finally, the

ore fed directly to the primary crushers has a grade of 1.5-1.6 %.

The facility can be divided into five parts in order to analyze and understand the

process. This dividing is also helpful for the directors of the management. Each of theparts can be said self-governing but also they are all bonded. These parts are;


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1 Primary Crushing Unit

2 Secondary Crushing Unit

3 Grinding Unit

4 Flotation

5 Dewatering

Lets examine all of this parts of the facility separately:

1 Primary Crushing Unit

This unit consists of the very first stages of processing operations. The newlyextracted ore directly comes to primary crushing. Here, it is exposed to the first

downsizing. But this downsizing rate is not enough for further operations such as

flotation, so after primary crushing there is a similar unit called secondary crushing

and it continues to decrease the particle size.

Machines and Their Properties

There are three trucks in primary crushing unit and they are responsible for the

feeding of the crusher. Actually, in general they dont feed the crusher directly, they

empty their material at a kind of stockpile near the crusher and the loaders use this

stockpile for the feeding. But sometimes also the trucks are used for this job directly.

These are two Volvo (34 DA 8942 34 TU 4650) an done Mercedes (37 NA 499)

model trucks. A hydraulic shovel makes the loading to these trucks. It has six

cylinder. The shovel capacity is 2.5 m3 and it can load or carry 5-6 tonnes of material

at one time. The loading time of the Mercedes truck is 2.75 minutes (it is loaded by 8

dipper), total cycle time is 22 minutes. Volvo (34 DA 8942) truck has a loading time of

about 3.5 minutes and a total cycle time of 21.5 minutes. The other Volvo truck (34

TU 4650) has a loading time of 3.25 minutes and a total cycle time of 17.5 minutes.

Four loaders are used for the feeding of primary crusher (966 G (two item), 938 G,

980 G CAT). Their shovel capacity is about 3.5-4 m3. The machines have a weight of

nearly 23 tonnes and they need experienced drivers for handling. During the feeding

into primary crusher, in order to balance the grade of the material, the loaders take 3


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shovels from impregnated (low-graded) ore, 1 shovel from wooded ore and 1 shovel

from massive (high-graded) ore. This balancing detail is an important one.

Crusher and Conveyor Properties

Previously there was a crusher which is used for ramble production (upper jaw width :

90 cm) and another primary jaw crusher (C 160 model) which is placed after K1

conveyor -it comes from underground- but today they are not in use and a jaw

crusher called new crusher is responsible for the operations. This one is a bit far

from K1 conveyor and there are many other conveyors which helps to collect their

output material into one stockpile. The new crusher is (MEM model) has an upper

jaw width of 130 cm, bottom jaw width of 15-16 cm. It has a motor power of 130 kW

and its capacity is 300 t/h. In jaw crushers, the materials are downsized by both the

impact of the dynamic jaws and the compression between each other.

The important parts of the crusher are steady cloth, dynamic cloth, the big pulley

called flywheel - it provides the movement - , and helix (spiral) strings. These helix

springs absorb the vibration of the crusher and they help to balance the crusher

during optimum feeding.

Generally in jaw crushers, the cloths are the parts that most prone to damaging. Main

reasons of this situation are the impact force of the material, friction, and feeding of

the moist material. This problem can be handled by changing the cloths regularly or

adding a metal plate behind the cloths. Besides, sometimes tough and big particles

can be stucked between the two jaws and it causes the loss of time and of course

money. In this case, the crusher is stopped and with the help of the lifters, the big

rocks are removed.

The dust problem occuring in the primary crusher is solved by four dust fans (filters)

placed in four different places around the crusher. These dust fans have 224 cloths

and works with 37 kW motor power.

Reduction gear is used for the purpose of arranging the speed of the conveyors.

There is a small part between the reduction gear and conveyor drum and it gives the

hydraulic pushing to the reduction gear. There is also another part which provides the

steadiness between the conveyor and conveyor drum during the movement. The


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switch button is needed for emergency cases, in such situations we can stop the

conveyor system by pushing it.

There is a sample taker after the K8 conveyor which comes from underground. This

is also called feed hopper. In the management, in every 20 minutes samples aretaken from the 35 cm crusher (jaw) and every morning at 7 a.m it is taken to the

laboratory for analyzing (K8 conveyor carries the particles which are smaller than 10

cm, this materials come from the 90 cm crusher which is placed at underground).

Under the buffer stock, there are five reciprocating feeders (one armed) called F1,

F2, F3, F4 and F5. Today, only F2, F3 and F4 feeders are working. The material is

feeded to K6 conveyor from these feeders, then K6 drops its load to K7 conveyor and

K7 carries the material to the secondary crushing unit, this point is the end of

primary crushing operations. In the management, like some other conveyors, this K6

and K7 conveyors are also have magnetic separators in order to separate harmful or

unnecessary iron particles (F2 works in a schedule of 10 minutes (underground) and

F3, F4 works in a schedule of 5 minutes (impregnated)).

2 Secondary Crushing Unit

The extracted material is supposed to downsizing process firstly in the primary

crushing unit, and then it comes to secondary crushing, in which it will also exposed

to further sizing operations. The next step for the material will be grinding (mills).

Therefore, the materials size is tried to be suitable for the flotation unit.

We can say that this unit starts with the feeding of K6 conveyor by the reciprocating

feeders F2, F3, and F4 which are under the buffer stock. Then the material comes to

the 370-metered-long K7 conveyor (which has a slope of 15%) and goes to

secondary crushing plant. It passes through the 500 tonnes capacitied (250 m3

volumed) SB1 silo and with the help of F6 banded feeder, the material falls to the F1

doubledeck screen. The upper deck has the aperture size of 60x60 mm2 and the

lower deck has the aperture size of 15x30 mm2, the screen has made of a flexible but

hard material; polyurethane. It has the length of 5 meters and width of 1.6 meters. It

consists of 4 equal pieces which are bonded end to end, each has a 1.25 meters

length. The particles can not passed under the screen are sent to the seconder

crusher (G4214 Lokomo). The particles passed from the apertures of the screen are


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directly sent to the next unit, grinding, by K11 conveyor. The particles crushed in the

seconder crusher (cone type) are sent to the other silo SB2 (800 tonnes capacitied,

400 m3 volume by the conveyors (in order) K8, K9 and K10 conveyors for the

purpose of screening or, if necessary, crushing again. They are fed from SB2 silo to

F2 screen by F7 feeder and to F3 screen by F8 feeder. These screens have the

aperture size of 52x12 mm2. This time, the particles bigger than the aperture size

(oversize material) are sent to tertiary crusher (HP 300 Metso). There are two of them

but today, just the second one is working because the material amount comes to

secondary crusher is not enough to fill both of them, the capacity can not be met. The

small particles passing through the screens F2 and F3 are sent to grinding unit by

K11 conveyor. The particles crushed by the tertiary crusher are dropped into SB2 silo

by K8, K9 and K10 conveyors and the same processes continue in a closed circuit till

the required particle size is obtained. In conclusion, the particles downsized by this

system reach to three cylindirical silos (each has a volume of 2500 m3 and a capacity

of 5000 tonnes) by K11 and then K12 conveyors. From here, with the help of the

feeders F9, F10, F11, F12, F13 and F14, again they are dropped to K13 and K14

conveyors, and finally K15 conveyor and sent to grinding unit by this conveyor. So,

the secondary crushing unit ends up here.


K6 conveyor has a length of 75 meters, a width of 1200 mm, velocity of 1 m/s and it

works with 30 kW motor power. K7 conveyor has a length of 370 meters, a width of

1000 mm, velocity of 1.5 m/s and it works with 160 kW motor power. The entering

particle size of the ore to the SB1 silo is between 0-12 cm. F6 feeder (banded) has a

width of 1200 mm and it works with 7.5 kW motor power. The upper deck (60x60

mm2)of the doubledeck screen was put in order to protect the lower deck (15x30

mm2). K8 conveyor has a length of 85 meters, a width of 1000 mm and it works with

55 kW motor power. K9 conveyor has a length of 20 meters, a width of 1000 mm and

it works with 7.5 kW motor power. K10 conveyor has a length of 85 meters and it

works with 75 kW motor power. K11 conveyor has a length of 115 meters and it

works with 75 kW motor power. K12 conveyor has a length of 25 meters and it works

with 7.5 kW motor power. Secondary crusher works with 132 kW and tertiary crusher

works with 200 kW motor powers. F7 and F8 feeders also work with 7.5 kW motorpower. Screen motor works with 22 kW. Dust fan cleans the air of the secondary


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crushing unit with its 21 pipes placed different points around the unit and this fan

works with 132 kW motor power. This dust fan is 11 years old and sometimes one of

its air valves get broken (blow-out etc.) and this valve can be changed with another in

15-20 minutes, so the problem can easily be solved.

Secondary crusher has a capacity of about 400 t/h. Its cloth has a useful life of 6000

hours. The cloth is made of cast iron. The actual capacity is 400 t/h but during the

fine or mixed feeding, it can decrease to 200 t/h because of the limited extraction. It

works with open circuit system and it is repulsive from both upper and lower sides.

The upper opening (mouth) is about 10 cm but after 9-10 months, it gets wider and

reaches 11-11.5 cm. The working ampere ranges from 150 A to 200 A.

Tertiary crusher is standard (head) cone crusher and it is available for possible

blockages. It is repulsive from just the lower side, it works with closed circuit system.

The crusher cloth is again made of cast iron and it has a useful life of about 1000

hours. Grease temperature changes between 36C and 40C. The hose temperature

changes between 27C and 38C. Its reduction ratio is 5:1. The secondary crushers

reduction ratio is between 10:1 and 3:1. Before starting to work, tertiary crusher waits

120 seconds for greasing, 60 seconds for feeding and 10 seconds for increasing the

ampere to high degrees from low degrees. The cutting action is arranged by the

stroke, therefore the particles supposed to downsizing and finally folieceous products

are obtained. Because of this reason, the screen apertures are rectangular-shaped.

Tertiary crushers motors engine rpm is 1500 revolution per minute. The wood and

rock pieces which hinder the circuit are cleaned daily.

In secondary crusher, if the feeding is hindered by a hard object (like iron), the

crusher may be stucked. The problem is solved by stopping the crusher, lowering the

conical head and taking that object out. For raising the head again, some grease is

pumped. In tertiary crusher, at the moment of stucking, the nitrogen tanks

automatically gives pressure to the stucked area and lower the conical head by this

way.

A heavy, protective plate made by lead is placed at the lower part of the crushers.

This is a very important part and it can be called as the heart of the crusher.

Because, after the abrasion or broken of this plate, you have to pay serious money inorder to compensate.


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3 Grinding Unit

The grinding unit is the last unit for particle downsizing after the primary and second

crushing. The required sized product of this unit is sent to flotation after classification.

The main elements of grinding unit are mills (rod and ball type) and hydrocyclones.

The grinding takes place in both rod and ball mills, it is wet grinding type. The

material taken from the secondary crushings stocked silos (-20 mm) is mixed with

lime and enters the grinding unit with 140-180 tph capacity. The reason for the

addition of lime is to increase the pH range for the flotation process because the main

purpose is to depress pyrite. The material firstly enters to rod mill. Rod mill operates

in open circuit and the material grinded here directly goes to cyclones (Before going

to cyclones, it visites Tank 1 and then it is sent to cyclones by sludge pump). After

classified in here, overflow is sent to flotation and underflow is sent to ball mills.

Overflow is 90 % ( - 74 ), 70 % ( - 38 ). Underflow is ( - 2 mm). Underflow is

grinded again at ball mills (BM1, BM2), and then pumped to cyclones by the sludge

pumps. The maximum particle size entering to cyclones becomes 2 mm. Ball mills

operate with closed circuit, so, while the overflow samely sent to flotation, underflow

continues to downsizing operation until the required particle size is obtained. The

floating particles in the copper flotation comes to BM3 ball mill for re-grinding. The

entering to BM3 is 80-90 % ( - 23 ) (overflow). The particles grinded in here are sent

to another small cyclone by Tank 2 in order to classification. Again overflow is sent to

flotation and underflow comes to BM3 by closed circuit principle. Grinding unit ends

up here.

By the formula ( Nc = (42.3) / (D-d) ) (D : 3,4 m) (d: it can be neglected because the

diameter is too small)

42,3/3,4 = 23 .

Revolution per minute is 14. So;

14/23 = 0.608 0.608 x 100 = 60.8 % 60-65 % critical speed

(rod mill).

Similarly, the diameter of the ball mill : 4 m. Nc= 42.3/ D = 21.2

Revolution per minute is 16. So;


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16/21.2 = 0.75 0.75 x 100 = 75 % 75 % critical speed (ball mill).

140 tonnes ; BM1 BM2 : 7.14 kW/ton

RM : 3.21 kW/ton

BM3 : 2.5 kW/ton

170 tonnes ; BM1 - BM2 : 7.05 kW/ton

RM : 2.94 kW/ton

BM3 : 2.17 kW/ton

The ball used for each tonnes is 1500 gr/ton. The rod used for each tonnes is 450gr/ton. In the rod mill, there are 640 (80 mm sized) body cloth, and 384 (160 mm

sized) lifting cloth. In the ball mills, the body cloth is 160 cm sized and the lifting cloth

is 80 cm sized. The entrance protectors have a usage life of nearly 8500 hours. The

body cloths have a usage life of nearly 1700 hours. The ball mill has a flow rate of

210 t/h.

If the pressure of the hydrocyclone increases, the cutting size decreases. If the length

of the body cone increases, the cutting size decreases. If the apex increases, the

cutting size also increases. If the vortex corrodes (increasing width), the cutting size

increases.


The rod mill has the diameter of 3400 mm, and the length of 5000 mm. The rods

inside are sized 70 x 4625 mm. The capacity of the machine can change between

140-180 t/h. The particle size enters to the mill is 20 mm. The cloth is cast iron (withmanganese). The solid rate of the machine is 70 %. The rod mill is Reoma Repola

type and it works with 850 kW motor power (1000 rpm).

BM1 and BM2 ball mills have the same properties. They have the diameter of 4000

mm and the length of 6000 mm. The balls are sized 30 mm and the solid rate of the

mill is 60 %. The material feeding to the mill has a particle size of averagely 2mm.

They are also Reoma Repola type mills and their cloth is also cast iron (with

manganese). While BM1 works with 170 kW (1000 rpm) motor power, BM2 works


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with 1700 kW (1000 rpm). BM3 ball mill (re-grinding) has a smaller size compared to

the others. It has a diameter of 2700 mm and a length of 4500 mm. The balls are

sized 30 mm diameter. The solid rate can change between 60-65 % and the feeding

material has a particle size of -38 . Averagely 65 tonnes of material is fed to BM3

which is a model of Reoma Repola. Electric motor works with 450 kW (1000 rpm).

BM1 battery has 4 cyclones ( 2 (500), 1 (350) and 1 (250) ). There were previously 6

ones. BM2 battery has got 6 cyclones ( 5 (350) and 1 (250) ). BM3 battery has 8

cyclones ( 4 (150) and 4 (250) ). The 500 cyclones have upper aperture diameter of

210 mm and lower aperture diameter of 105 mm. 350 cyclones have upper aperture

diameter of 130 mm and lower aperture diameter of 65 mm. 250 cyclones have upper

aperture diameter of 100 mm and lower aperture diameter of 45 mm. The conicalparts of the cyclones are made of polyethylene and the cylindirical parts are made of

rubber.

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