It is a Iron Ore Palletizing Plant at

sohar –Sultanate of Oman

Capacity: 2*4.5MTPA13636 T/Day568.16 T/Hr

Technology:Grate Kiln {formerly

known as Allis-Chalmers Kiln}

Brief: Pellets are transforms of Mineral resources of superior quality feed as raw

materials to D.R.I & Blast Furnace process

For Steel making……

Raw Material: Iron ore,

Limestone, Anthracite & Bentonite.

Fuel: Natural Gas

Vale’s Industrial EmpireVale Oman

Palletizing Plant

Iron Ore Fines Utilization….. Via …..Pelletisation

Analyze Process capability

Stimulate Process Performance

Prepare Process Plan

We are here

Vale Oman Palletizing Complex:-

Process Control Dept.

Thickener

Vale Oman Process Flow Chart

Fuel

Drying Grinding

FeedIron OreAdditivesChips/Chunks

Bentonite

Mixing

PH2

PH1

TPH

DD1

DD2

Rotary Kiln Traveling Grate

Roller Feeder

Balling

AnnularCooler

CONTENTS:-

Define : Process Control Glossary of Terms & Methods of preparation: (Sampling)Raw Material Handling: ( Sampling of Iron ore , Lime stone, Anthracite)Grinding Area: ( Sampling of feed to mill & mill discharge feed)Mixing & Blending Area: ( Sampling of Mixed material & Bentonite )Thickener Area: (Sampling of slurry )Balling Area: (Sampling of Green Ball )Traveling Grate Area:( Sampling of Feed to T.G , Discharge material of T.G Measurement of Temperature, Differential Pressures and Process Gas flow)Rotary Kiln & Annular cooler Area: ( Measurement of Kiln Feed end, Middle, Discharge Temperatures, Gas Flow , Stack sampling & Sampling of finished product)Product Coating Area : ( Sampling of coating material )Health & Safety Information: Vales Motto

Define : Process Control : The Fundamental philosophy associated with the economic production of Pellets must be based on defect PREVENTION rather then defect DETECTION. This approach requires a system of PROCESS CONTROL, which can only be effectively implemented through STATISTICAL TECHNIQUES. Decisions to modify or adjust processes must be based on statistical evidence, such as control chart data. Reliance on INSPECTION for quality control is both ineffective and inefficient.

Process :

The combination of machine and equipment, people, resources, methods and mill environment that produce a given result.

Control :

To guide with in boundaries or to make something behave the way you want it to. Hold on specifics as well.

Glossary of Terms & Methods of preparation: (Sampling)

TERMINOLOGY USED IN SAMPLING AND SAMPLE PREPARATION

Lot: The quantity of Raw material/ Finished Products indicated to be of the same category and offered for inspection at one time. A lot may consist of the whole or a part of the quantity ordered for.

Sub-lot: The quantity of ore/pellets in each of the parts into which a lot is divided for the purpose of sampling.Increment: The quantity of ore/pellets obtained by a sampling device at one time from a lot or sub-lot. Unit Sample: The quantity of ore/pellets collected at one time from the conveyor (Unit sample is larger than the increment). Gross sample: The total quantity of ore/pellets consisting of all increments or unit samples taken from a sub-lot.Size sample: The sample taken for the determination of the size distribution of the lot or sub-lot.Moisture sample: The sample taken for the determination of moisture content of the lot or sub-lot.Laboratory sample: The quantity of ore/pellets obtained by reducing a gross sample following a specified procedure for determining chemical composition of a lot or sub-lot.Composite sample (For the lot): The quantity obtained by mixing together proportional quantities of ore/pellets representing the mass of each sub-lot which a lot has been divided.Sampler: Person responsible for performing the sampling operations.

Sampling method: That part of the sampling procedure dealing with the method prescribed for withdrawing samples.

Random sample: Sample in which the different fractions of the material have an equal probability of being represented.

Representative sample: Sample obtained according to a sampling procedure designed to ensure that the different parts of a batch or the different properties of a non-uniform material are proportionately represented.

Sampling plan: Description of the location, number of units and/or quantity of material that should be collected, and associated acceptance criteria.

Sampling procedure: The complete sampling operations to be performed on a defined material for a specific purpose. A detailed written description of the sampling procedure is provided in the sampling protocol.

Sampling record: Written record of the sampling operations carried out on a particular material for a defined purpose. The sampling record should contain the batch number, date and place of sampling, reference to the sampling protocol used, a description of the containers and of the materialssampled, notes on possible abnormalities, together with any other relevant observations, and the name and signature of the inspector.

Need for Sampling:

Introduction : According to ISO/IEC 10725, “sampling” is defined as “a procedure whereby a part of a substance, material or product is taken to provide for testing or calibration a representative sample of the whole. Sampling may also be required by the appropriate specification for which the substance, material or product is to be tested.” In other words, the goal of sampling is to select and obtain a test portion of the material in some manner, such that the sub-sample is representative of the larger amount of material.

Sampling is often a major source of error and if a truly representative sample of the batch isnot obtained, then the subsequent analysis will give a wrong figure. It is the aim thereforeto develop correct sampling protocols, considered to be an essential requirement forobtaining valid results within Prospect.

100% Inspection of Process Output is anunsatisfactory method to determine productquality. It is costly ,has no relationship to future quality, and is impossible in many cases.

Sampling reduces the cost to measureProduct quality and can be used to predict Future product quality when used in Conjunction with control charts.

Samples must be taken so that their results are representative of actual

process quality .In other words, they must be taken So that the results are unbiased.

SAMPLING:The methods of collecting increments or unit samples from a lot may be classified into following types or a combination of belowmentioned.

Sampling from conveyors.

Shipment sampling.

Stockpile sampling.

Sampling during production.

Automatic samplers.

Sectional sampling.

Trench sampling.

Iron

Ore Pellets

• Sampling from conveyors: When ore/pellets is moved on conveyors, one of the most reliable methods of manual sampling is stopped belt method. Whenever it is practicable to stop the conveyor belt periodically, a large quantity of iron ores known as unit sample may be drawn by stopping the belt. The sample shall be collected from the full width and thickness of the ore/pellet stream over a suitable length of the conveyor. In case it is not possible to stop the conveyor the sample shall be taken from a specified place on a conveyor or at a specified transfer point of conveyor.

• Shipment sampling: In order to get gross sample, the ore/pellets shall be sampled as far as possible when in motion. That is from the conveyor during loading or immediate discharge during unloading at regular interval.

• Stockpile sampling: The ore/pellets from stockpiles shall be carried out as far as possible, when they are in motion, that is, during the formation of the stock piles or during the shifting of the stockpiles to the other places. Sampling from the stationary stockpile shall not be conducted, as this would introduce significant bias in sampling.

• Sampling during production: The ore/pellets shall be collected as per stopped belt method from the conveyor or at the convenient discharge point of the conveyor.

Trench sampling: Along a randomly chosen line on the ore surface of the sub-lot, a trench shall be dug, right down to the ground level leaving about 0.3 meter walking space at the ground level. From the trenches so dug, the required number of increment shall be collected with the help of suitable sampling scoop, at various points randomly spread over the two exposed sides of the trenches. In case of large stockpiles, in addition to the trench, the sides of the piles may also be opened to expose the ore down to the bottom, at places where the trench does not expose the ore inside.

Automatic samplers: In Grinding Section & Product pellet area, the automatic samplers have been provided. By simple button pressing at the required interval the sample will be collected.

Sectional Sampling: 4 unit samples in the case of fines and calibrated ores and at least 8 unit samples in the case of sized ore and lumps are to be collected from each sub-lot. For this purpose, the requisite number of points shall be chosen at random on the entire surface of the stockpiles. At each of the selected points, a circle of suitable diameter (minimum three times the largest particle size) shall be marked. The material over the area of this circle and along entire height of the stockpile from top to bottom shall be collected in stages. This can be done by taking initially ores up to a depth of 50 cm and covering the hole so formed by a plate for removing the ores lying on the sides of the hole. Then after removing the plate further depth can be reached in the same manner and the ores can be collected from the freshly formed hole.

SAMPLE PREPARATION• Before analyzing any raw material for Physical/Chemical/Metallurgical properties it is very important to mention here about the sampling and

sample preparation. The sample should be collected which is a well representative of the total raw material ready for dispatch and well prepared before analysis. In order to collect representative sample for correct analysis, sampling and sample preparation is a very important tool for preparing a sample for analysis.

• The primary object of sampling of any material is to draw an inference about the quality of the lot on the basis of information derived from the sample. If the consignment is of uniform nature the inference so drawn is almost precise, which gives an accurate estimate of the quality, but when the material is heterogeneous in nature as is often the case with any raw material, the method by which a sample obtained becomes critical in inferring about the quality of the consignment.

• The efficiency of sampling largely depends on the degree of homogeneity of the material and size of the sample. In case of heterogeneous material, the size of the sample should be more for accurate estimate of the quality.

• Preparation of a final sample for physical, chemical and metallurgical properties is an important aspect, because the sample prepared in accordance with the below mentioned procedure will fetch accurate analysis otherwise erratic results.

•

• There are different methods of sample preparation.

• Riffle divider

• Coning and quartering.

• Reduction by Riffle divider: The final sample shall be well mixed and poured into the riffle. This process shall be repeated using different sizes of riffles according to the size of the ore.

• RIFFLE SAMPLE DIVIDER : IS : 1607, IS : 2720.

• Efficient sampling out of bulk materials/deposits is the most important for getting the true idea about the bulk material. The volume of material to be tested is usually quite huge and it requires reduction in volume in a methodical manner. The Riffler Sampler (sample divider) helps to reduce the bulk while maintaining the character of the material and thus it is a helpful, light and handy device for sampling work. The standard units are made of GI sheet and mounted on rigid steel frame and supplied with three pans and one scoop.

• Standard Chute sizes are 25mm, 18mm and 12 mm. However, the Chute sizes can be made according to the user's specifications etc.

• Coning and Quartering method: The ore shall be well mixed and then scooped into a cone shaped pile. Care shall be taken to drop each scoopful exactly over the same spot as otherwise the central axis of the cone will be slackened and an uneven distribution of lumps and fines will result.

• After the cone is formed, it shall be flattened by pressing the top of the cone with the smooth surface of the scoop. Then it is cut into quarters by two lines which intersect at right angles at the center of the cone.

• The bulk of the sample is reduced by rejecting any two diagonally opposite quarters

Coning Quartering

Process Control - Raw Material Sampling Tools :

Process control: Instruments for Monitoring Temperatures , Differential Pressures , Gas Flows & Level Sensors

THERMO

COUPLES

FLOW

METERS

PRESSURE

GAUGES

BED

LEVEL

SENSORS

Raw Material Handling systems: ( Sampling of Iron ore , Lime stone, Anthracite)

• In general, for any industry a right amount of input is necessary to produce an effective output as yield. In our pellet plant we are getting the iron ore fines as the input from Brazil through shipment, we need an handling system for transporting of the raw material from Port area to our plant, and hence we are making use of equipments like Stackers, Reclaimers & Conveyors for serving the purpose.

• Raw material unloading from ship

VESSAL CAPACITY: 4 .0 LAKHS TONS

UN LOADER CAPACITY : 10,000 T/H

Unloaded Iron ore stocked near Jetty area(Iron Ore Stockpile)

Stacker &

ReclaimerCapacity:10,000T/Hr

Iron orePiles near JettyOf

Capacity:946.000T

Iron oreStockpile capacity:766.000T

Limestone & Anthracite Stockpiles

LimestoneStockpile

Capacity:6.000T

AnthraciteStockpile

Capacity:15.000T

Process Control Sampling Plan:

• Vale Oman has Raw material’s Storage capacity of 1712.000T( Iron ore),where sampling is challenging task to meet the

Homogeneity of the sample. Process Control Dept. aims to execute such a difficult task where there is a higher

degree of confidence in the source then sample.

• Two types of sampling errors are possible:

a) Segregation errors

This occurs when particles are exposed to gravitational, rotational, vibratory or

aeration operations (or other types of mechanical motion), usually resulting in fine

particles migrating to the bottom and larger particles being concentrated at the top.

This type of error is thus dependent upon the previous history of the powder and

usually occurs with free or easily flowing powders, having a significant range of

particle size. This type of error can be minimized by suitable mixing and building up

the sample from a large number of increments.

b) Statistical errors

This is type of error is caused by observing a sample instead of the whole lot. Although this type of error cannot be prevented, it is

likely that the size of statistical errors can generally be controlled by taking a large enough random sample from the entire lot.

Process Sampling at Stockpiles

Random sampling of entire

area

We need to trench the entire the pile ,

so as to have uniformity &

homogenization in sampling

10 Mtrs

Top Layer

Middle Layer

Bottom Layer

Dividing the Entire Mass in to

Layers a Composite sample has to be drawn.

Stocked Raw materials are transported through conveyors in to Plant Storage Bins:-

Continuous visual Monitoring

has to be followed

so, as to identify contaminations

Random Sampling of raw materials on conveyors:-Sampled Raw materials are tested for moisture (M%) ; Size Distribution with the support of Quality control Depts. If there are any abnormalities, we can control at initial stages…………Later raw materials are stored in to Day Bins to meet the rated capacity of plant/day. Samples to be taken from Weigh feeders: AL: 2105.01-06

Hot Gas Generator

Ball MillCapacity:424TPH

Grinding Area: ( Sampling of Feed to Mill & Mill discharge feed)

The term H.G.G refers to Hot Gas Generator used to remove moisture from the mixed raw material (Iron ore, Lime stone, Anthracite) before it enters grinding mill , Grinding refers to the size reduction of a material by tumbling it in a revolving cylinder. There are two types of grinding processes (1) Vertical and (2) Horizontal. But we are using Horizontal grinding process. This occurs when the ore and a grinding media are tumbled together. The grinding media used are Hi-Chrome Steel balls. These balls are of different diameters distributed through out the Ball Mill.

The media method of size reduction depends primarily on impact or compression fracture of the ore caused by the impact action of heavier steel balls. Such impacts caused by the impacts or point-to-point contacts occur between the ore and the balls or between the balls and the mill shell liners. It is important that the balls are large enough so that as many points of contacts as possible occur and sufficient impacting action is provided which will result in the proper breaking of the ore particle.

Grinding Media

Mill Liners

Mill Diaphragm

• The grinding mill liners are provided with lifters. As the mill cylinder is rotated the lifters lift the balls to give them a proper cascade pattern and the energy to do breaking. The cascade pattern is determined by the rotating speed of the mill cylinder and the mill diameter. The energy consumed in grinding is therefore proportional to the weight of media, the diameter and rotational speed of the mill.

• The size of the ball media is determined by the size of the incoming feed particles. Larger sized ore requires a larger ball size for good impact efficiency. As the ore is gradually reduced size, the media itself wears out and the balls are reduced in size. These smaller balls are also necessary, as these balls are still adequate in size to cause fracture because many more points of contact occur and many more balls are present per unit volume. It is imperative to add bigger size balls for two reasons.

• To keep up the number of bigger size balls to break the large ore particles.

• To maintain the required number of balls in the mill to provide the power required for grinding. The media should be added as and when required as the balls are continuously being worn away.

• Another mechanism of size reduction that occurs in the mill together with impact grinding is abrasive grinding or attrition grinding or grinding by rubbing as the ore particles and media slide and rub against each other as the ball mill rotates.

DimensionsD=6.6M L=12M

• The patterns, which generally exist, are: -

• Cascade Pattern – Here the lifters lifts the balls giving them the proper cascading energy for breaking up the ore initially.

• Impact Pattern - Once the balls lifted up and after attaining a definite height it falls down on the ore creating fractures. More the intensity of the balls finer be the size reduction.

• Attrition Pattern – This takes place along with the impact grinding, here due to rubbing / sliding of the ore particles and the media against each other, size reduction takes place on the mill rotation.

• The discharge of the ball mill passed through the SEPOL a Dynamic separator to

separate the fine particles from coarse particles, it acts as a classifier. The

separated coarse particles are recirculated to mill for regrinding.

Make -Polysius

•• CRITICAL SPEED OF BALL MILLS:CRITICAL SPEED OF BALL MILLS:--•• ØØCRITICAL SPEED: IT IS THE LOWEST RPM WHICH WILL CAUSE AN INFINICRITICAL SPEED: IT IS THE LOWEST RPM WHICH WILL CAUSE AN INFINITELY SMALL TELY SMALL

PARTICLE ON THE SHELL LINER TO CENTRIFUGE.PARTICLE ON THE SHELL LINER TO CENTRIFUGE.

•• ØØBALL MILLS ARE NORMALLY OPERATED AT 70 BALL MILLS ARE NORMALLY OPERATED AT 70 –– 75% CRITICAL SPEED.75% CRITICAL SPEED.

•• ØØCRITICAL SPEED: [RPM] = 76.63 / CRITICAL SPEED: [RPM] = 76.63 / √√ DDWhere D is the Internal Diameter of mill in feet, measuWhere D is the Internal Diameter of mill in feet, measured inside shell linersred inside shell liners

• Types of circuits used in the Mills: -• Single Mill• Primary as Single Mill• Primary as Twin Circuit• Single as Twin circuit• Types of Grinding Media: • Steel Balls• Rods• Pebbles• Types of Grinding Mills : • Rod Mills• Ball Mills• Pebble Mills

Sampling of Feed to Ball Mill for

Moisture% & Size Distribution

Live load test to be carried on

AL2111.01/2112.01/2113.01

Sampling of Mill discharge for

Moisture%, Blain .No, Size fractions

Fig:-001

Process Sampling At Ball Mill Area

Automatic Sampler: Apart from manual sampling as showed in fig:-001, Automatic sampling units are also facilitated in Vale Pellet Plant for sampling purpose in Grinding Area.

A sample is extracted when a hollow tube with a longitudinal slot rotates into position against the material flow. The sample falls directly through the tube and into a sample bottle.

This is specially designed to extract dry, non-sticky, bulk solid powders on a continuous or intermittent

basis from air assisted conveyors

Air Slide Sampler

Dimensions: W x H x D/mm = 340 x 660 x 240

Sample collecting container volume = 51

Paddles

Intensive Mixer

Make:Lodige capacity: 650

T/HrLength:5 MtrDia:1.85Mtr

Mixing & Blending Area: ( Sampling of Mixed material & Bentonite )

• Mixer is provided for mixing of iron ore concentrate & bentonite on continuous basis.

• Ploughshare shovels rotate in special arrangement along the horizontal shaft inside a horizontal, cylindrical mixing drum. The size, number, positioning, geometric shape and peripheral speed of the mixing elements are coordinated for three-dimensional movement of the components inside the mixing drum. The resultant turbulence, with constant, total product mobility caused by the mixing elements, prevents the formation of dead or static zones and results in gentle, precision mixing within the shortest possible time.

• Mixing elements lift product during radial movement from the wall of the drum thereby preventing particles from becoming squashed between the wall and the shovel. The hurling and whirling process is, therefore, highly suitable for mixing processes in which the components have widely differing bulk densities, particle sizes, rheological features and – relevant to pharmaceutical production – highly different mass fractions.

Feed Rate of WF’s-

AL3112.01,02Bentonite

Sampling for Moisture% Grind% &

Swelling Index

Sampling at Mixer Discharge for Moisture% , LOI &

Chemical analysis.

Process Sampling Mixing & Blending Area:

Thickener Area: (Sampling of slurry )Diameter:30 m²area Thickener

Arms

• Thickening is a process of reducing the liquid content and thereby increasing the solid density within the slurry. The mechanism is all based on the settling rate. The settling is even controlled by the rotation of the rake arms. The rotation of the rake arms makes the denser particles to be dragged to the central portion and the light particles move to the periphery. Almost clear water is taken as the overflow. Thickener is essentially a conical tank like structure. It has a central shaft at the axis of the conical tank. The rake arms are attached to a sprocket that rotates about the central shaft. There are four arms, two long and two short, all 90° apart. The longer arms are responsible for the settling action. The shorter arms mainly deal with the central portion. But the central area is a denser portion subjecting more torque on the arms. The shorter arms handle such denser matter reducing the torque on longer arms.

Process sampling at Thickener area

Random Snap-cuts of slurry samples has to collected

diff.intervals to have uniformity in sample

Slurry Sampling at Thickener

under flow for Density & % of

solids checking as per ISO:2591

CBBS extracts a representative sample from the falling flow of material off a belt conveyor. It’s carriage-mounted cutter traverses through the material flow, collecting the product sample as it goes, before discharging it into a hopper positioned outside the material flow

CBBS – Cross Belt Bucket Sampler

Mounting may be in chutes, hoppers, at belt-end or head chutes. When activated, a slotted sample tube entersthe product stream with the slot facing down. While full y extended, the sample tube rotates 270 degrees, taking a representative sample through the product stream. The sample tube then retracts out of the product stream, into the sampler housing and deposits the sample into the discharge. The sample tube can be driven pneumatically or hydraulically.

In our process Cross Belt Samplers are provided at conveyor TR.3113.01 & TR.3123.01-Mixing &

Blending Area to Balling Feed. Sample will be collected at - CT.3113.01. Capacity : 2.5kgs & feed rate

of conveyor: 900Tph.Samples are collected in a box later carried to Quality Lab manually.

Automatic Sampling System –ISO-3082(2000)

Agglomeration:As the Mixed Material is fed to the

Balling disc, it gets lifted upwards due to the rotation of the disc. The material gets lifted up as long as the friction between the ore particles and the disc bed is more than the gravitational force. Once the gravitation force on the ore particles is more than the frictional force, the particles roll down. As the particles roll down, they agglomerate. The agglomeration of the particles continues as long as the rolling movement is sustained, resulting in formation of the balls.

Technical details of Balling Discs :

The palletizing discs consist of a flat circular base with a wall perpendicular to the plane of the base along the circumferences.Scrapers are provided on the base and side wall for deflecting the material. The disc is inclined at angle greater than the angle of response of the feed material and is rotated in this plane with a variable speed drive. The scrapers are fixed 1 position and donot rotate with the disc.

• Inside Diameter: 7500 mm

• Rotation Speed: 5 - 10 rpm

• Feeding Capacity: 150 – 180 TPH

Palletizing Disc Area: (Sampling of Green Ball )

Mechanism of Ball Formation:

liquid bridges

rolling up

powder seed

spraying

binder droplet

drying/solidifying

solid bridges

Green pellet

Granule

„

snowball“-structure

Spheronizing of Wet Granules

Powder layering

Factors effecting Balling:-

Inclination of Balling Disc

Disc Speed

Feed Rate

Moisture content

Sidewall height

Surface Area of the Particle

Principle of Agglomeration

SpheronizingGreen pellet

Process Sampling at Palletizing Discs Area

Green Ball Drop test

G.C.S – Green compression strength

Green Ball Sampling for Moisture % , Size fraction , Drop. No , G.C.S

Checking of Ballformation

in discs BL-3131.01-07

Traveling Grate Area:( Sampling of Feed to T.G , Discharge material of T.G, Measurement of Temperature, Differential Pressures and Process Gas flow)

Brief: The traveling grate is used primarily to dry and preheat green balls for feeding into the rotary kiln, where they are indurated. The traveling grate provides the means for efficient heat transfer with high, medium and low temperature gases. These gases transfer heat by convection so intimate gas solids contact is required for effective heat transfer.

Dried green balls do not have the physical properties necessary to survive direct feeding to the rotary kiln and must be semi-indurated. For acceptable semi-induration, it is necessary for green balls to be substantially heated and fluxstone carbonates (if used) to be substantially calcined. Good gas-solids contact is required to cause bonding to occur and to remove CO2 so that calcination of the fluxstone can proceed at reasonable rates. This semi-induration or preheating is accomplished by flowing the gases exiting the annular cooler and rotary kiln through the bed of dried balls in the tempered preheat and preheat zones respectively of the traveling grate.

Process Sampling at Traveling Grate

Checking the Bed Height,Sampling of feed to T.G forMoisture% & Size fraction

Checking Gapping of Roller Classifiers CS3131.01-07 &

Roller Feeder AL3131.01

External view ofTraveling Grate

Internal view ofTraveling Grate

Bed Level checking

Process Measurement of Temperatures , Differential Pressures & Gas Flows

Process Control Monitoringof Profile Deviation……

298.90M² AreaL =68.80 Mtr W = 4.716 Mtr

AIR HEATER

Analyzing of Process Parameters

Temperatures&

Differential Pressures &

Gas Flows, at Indurations Duct,

Wind Boxes, Heating zones ,Stack samplingetc……….

Rotary Kiln & Annular cooler Area: ( Measurement of Kiln Feed end, Middle, Discharge Temperatures, Gas Flow & Sampling of finished product )

Rotary Kiln

The rotary kiln is a downwards-sloping cylinder from the traveling grate to the annular cooler. The speed of rotation controls the rate of solids flow through the rotary kiln and imparts a mixing action to the pellet burden. The mixing action is important because it creates a homogeneous pellet product. All of the pellets are exposed to the burner flame for an equal amount of time.

This residence time is sufficient to uniformly indurate all pellets, thereby minimizing the ball-to-ball quality differences inherent in pellets discharging from the static bed processing typical of a SG.

At the discharge end of the rotary kiln is a single burner, which utilizes the hot recuperated (secondary) air from the annular cooler for combustion. The burner can be designed to fire a single fuel or a combination of fuels. Oil, Natural gas (LBG/Coke oven gas/ BF gas/ Corex gas) or coal can be used singly or in varying mixtures. Because of the single burner, controlling the induration process is a simple temperature loop. Grate-Kiln plant processing Hematite ore may have few additional burners in pre heating zone. This is very different from a SG system that may require up to 50 burners.

Dia: 6.9 MtrLength:45Mtr

Kiln Burner flame & Red Hot Pellets Discharge from

Kiln

Process control Monitoring Kiln

Temperatures & Pressures &

Burner Flame & Stack sampling

Sectional view of Annular cooler

Annular Cooler

The annular cooler is functionally the same as the traveling grate except for its annular configuration. Hot pellets discharging from the rotary kiln are distributed in the annular cooler as a level bed. Ambient air is forced upwards through the conveying elements (pallets) and the bed. Thus machine parts are not exposed to high temperatures.

The pellets are leveled in the annular cooler to a bed depth of 700 mm and conveyed over up to 4 cooling zones. In each cooling zone, sufficient cooling air is provided to produce the mass of air at a temperature required by the rotary kiln and traveling grate and . The various cooling zones are designed in such a way that they will recover the maximum heat from the hot pellets and various ducts carry this hot air to rotary kiln/ traveling grate zones and Ball Mill .

Cooled pellets discharge through the cooler’s discharge hopper at a controlled rate to a product load-out system.

81 M² Area

Inspection & Sampling of ProductPellet at TR3154.1-02 &TR3154.03-04

The HEAD sampling equipment samples pellet from the end of a belt conveyor. This product collects accurate representative samples when mounted on the end of a belt conveyor carrying the product. Sampler installations are designed per application.

When activated an electric motor drives the slotted sample cutter through the product flow to collect a sample of the material. The sample is discharged via gravity to a sample collection point. Sample collection is initiated in response to either an operator’s manual command or a signal automatically generated by controller logic, usually time-based but which could alsobe volume or quantity based.

In our process Head Samplers are provided at conveyor TR.1010.12 & TR.1010.13- Product Pellet Carrying Conveyor at

Transfer tower CT-1010.10&CT-1010.11.Capacity : 6.5kgs & feed rate of conveyor : 750Tph.Samples are collected in a

Sampling box later carried to Quality Lab manually.

Automatic Sampling System –ISO-3082(2000)

Product Coating Area : (Sampling of coating material )

Depending on customers requirements the finished product is coated to avoid

Sticking of pellets in the further reduction process. To avoid such conditions

Pellets are coated with external additives like Limestone or Dolomite with

Bentonite acts as binder, together called as oxide coating of pellets.

Pellets are coated with a additives ratio 5:1 of Limestone to Bentonite.

Role of Process control is to monitor the Process variables like:

Checking additives blend ration

Flow rate ~ Tonnage

Checking Pulp Density & % of Solids ( approx: 1.15gm/cc & 22 % solids)

Maintaining the Product Pellet Moisture to 1.5 % max.

Pellet Stockpile of Capacity: 3,80000 T

Stockpile sampling of pellets

Process control

C.C.R MonitoringQuality Control

Health and Safety InformationThe following list of safety precautions should be considered as a guideline:Personal safety:Use all PPEs applicable while working in the area (Safety helmets, Safety boots, hearing protection, Goggles, masks, gloves etc).Use protective clothing appropriate to the work being performed.

Work area safety: Maintain and practice good house keeping, which can prevent lots of imminent accidents Allow only authorized personnel inside.Operate the equipment controls with clean hands.Make daily check of starting alarms and warning devices and ensure the equipment is working properly.Examination of interior atmosphere for toxic etching, asphyxias or flammable components.Stairs, passageways, aisles, hallways, walkways, working areas and all emergency exit routes provided with electrical lights.

Equipment safety:Follow caution signs and warningsFollow manufacture recommended work practicesCheck all equipments before starting and give it a change incase it asks for.Skilled supervision is required.Use all the rotating machinery provided with appropriate protection devices such as coupling guard as well as emergency stop buttons. Equipment must be locked out prior to removal of equipment guards.

Electrical safety:Never assume a electrical line to be dead unless it is tested and declared so.Lockout and tag electrical /mechanical controls before performing any inspection, maintenance, lubrication.Any work on electrical installations to be carried out in accordance with safety instructions.Installation, maintenance and repair of electrical equipment to be done when permitted by authorized persons.Sparks from electrical equipment (cable, wire, motor, hose etc) if observed to be reported to shift supervisor and maintenancedepartment to be notified immediately.

Health & Safety Information: Vales Motto

• Conveyor safety: • Ensure the conveyor horns function properly.• Ensure conveyor zero speed switch function properly.• Stop the conveyor when there is a need to pass anything over it or under it.• Personnel must never ride on the conveyor belts.• All walkways along the conveyed must be free of material, tools, oil or grease.• Ensure all pull chords function properly.• Loose clothes should not be worn near conveyors.• Do not lean over the conveyor while taking samples• If the conveyor maintenance is to be taken, make certain the equipment is

locked out according to the electrical lock out system and a work permit has to be obtained prior to work commencing.

• To ensure safety, have the equipment controlled by the local field control panel.

• Safety training:• All should be aware of plant design philosophy and potential hazards.• All grades of personnel must be involved in elaborating emergency

procedures.• Reporting all unsafe conditions to their supervisors.• Identification of dangerous material and areas.• Identification of hazardous substances.• Identification of prohibitive and restricted areas.• First training and emergency preparedness.• Issuing of Safety work permits.

Gas safety:Carbon monoxide is highly toxic when inhaled, it acts by combining with hemoglobin ofred blood cells to form carboxyhaemoglobin. This results in oxy-hemoglobindissociation and oxygen transport in blood.An individual can work safely for 8 hrs in a 500-ppm exposure of CO gas.At high concentration of 0.4% i.e. 4000 ppm CO can prove fatal in less than an hour.Respiratory Protective equipments (RPPE) should be used in personal emergencies forevacuation purposes and during clean up of the area.

For exposure protection against CO hazard use,Oxy-Breathing apparatus.Compressed air breathing apparatus.Trolley mounted SCBA set.Air supplied blower facemask.Incase of a gas exposure,

Remove the person immediately from the contaminated area to fresh air location andkeep him comfortably warm. Tight fitting clothes, shoes and the belt of victim should beloosened. Inform OHC, Safety, Transport, and Utility for necessary action at their end.Incase of gas leaks, All sources of ignition should be kept away.SCBA to be used whilesampling and attending leaks. Incase of fire, Dry chemical Powder and CO2extinguisher are suitable to fight small fire of CO.In case of large fire brigadeshould be called to attend the fire call.

Presentation By:A.Srik@nthKaundiny@Process Control Dept.V@le Om@n Pellet Plant –Sohar-Sultanate of Om@n