Oman Cement Company

Oman Cement Company (SAOG) was formed in 1978. Rusayl Cement plant was completed in 1983 with an annual integrated cement production capacity of 624,000 tons, of cement. In 1999 clinkering capacity expanded to a total of 1.2 million tons per year. The second production line came on stream in mid 1998. Presently the company is working on expanding the capacity of plant form 1.26 MTS per year to 1.70 MTS per year by upgrading production line No. 1 and No. 2.

The company facilities are:

1- Computerized Manufacturing

Oman cement manufacturing process is fully computerized.

This avoids major hazards in manufacturing and needs less manpower.

2- Central Laboratory

The Quality Control is supported by central laboratory consisting of robotics, X-ray spectrometers, laser particle size analyzers and computerized physical properties testing equipment.

3- Quality Management System and Environmental Management System

oman cement Quality Management System is in accordance with the Quality Assurance Procedures of ISO 9001 : 2000 certification.

4- Pollution Control.

The Oman cement company produces many types of cement which are:

1- Ordinary Portland Cement:

It is type I Portland cement. Its uses are reinforced concrete buildings, bridges and railway structures. The typical compound compositions of this type are:

55% (C3S), 19% (C2S), 10% (C3A), 7% (C4AF), 2.8% MgO, 2.9% (SO3), 1.0% Ignition loss, and 1.0% free CaO.

2- Sulphate Resistant Cement:

It is type V, is used where sulfate resistance is important. Its typical compound composition is:

38% (C3S), 43% (C2S), 4% (C3A), 9% (C4AF), 1.9% MgO, 1.8% (SO3), 0.9% Ignition loss, and 0.8% free CaO.

3- Moderate sulphate resistant:

It is type II cement. This type of cement can be used in structures of considerable mass, such as large piers, heavy abutments, and heavy retaining walls. Its use will reduce temperature rise especially when the concrete is subject to hot weather. Its typical compounds composition is:

51% (C3S), 24% (C2S), 6% (C3A), 11% (C4AF), 2.9% MgO, 2.5% (SO3), 0.8% Ignition loss, and 1.0% free CaO.

4- Oil Well Cement

Oil well cement, used for oil wells grouting, usually made from Portland cement clinker or from blended hydraulic cements. It is used for cementing work in the drilling of oil wells where they are subject to high temperatures and pressures. Its typical compound composition is:

MgO: 6.0% SO3: 3.0% Loss On Ignition: 3.0% C3S: 48%-65% C3A: 3.0% Insoluble Residue: 0.75% C4AF+2C3A: 24%

Production methods:

There are four stages to produce cement that Oman cement using which are:

1- Preparation of the raw material at quarries

2- Heating and cooling to produce clinker

3- Preparation of the cement

4- Cement packing

Process description:

1- Preparation material at quarries

The raw material contains of limestone (80% of raw material), silica, aluminate and iron ore. The quarries located around the Oman cement plant. At quarries the raw materials are extracted with heavy equipments. Then the limestones are crushed with mobile crushers connected with long conveyer belt to transport them to storage passing the auto lab to analysis the samples with x-ray each two hours. After that the raw material are moved to reservoirs. Then they are moved with conveyor belt to the raw mill to grind the raw materials. Finally the grinding raw materials are moved to mixture reservoirs to get proper mixture before fed them to kiln.

2- Heating and cooling to produce clinker

The raw materials are moved to channel, where heat exchange is occurred between these material and the raising hot gases from kiln, then the materials are separated from the gases. After that the material moved to calciner where the limestone is converted to calcium oxide, and then the calcined materials arefed to the kiln where the temperature about 1400 c and then leave from kiln to get clinker. Then the clinker leaves from kiln to air to reduce its temperature to 100 c to be ready to be moved to cement mill.

Kiln process

3- Preparation of cement

The clinker that came out of the cooler will be transported by the bucket chain conveyor to the silo. The bag filter on the top of the silo is sized for the feeding by the bucket chain conveyor and thermal air expansion in the storage. The clinker extracted from the silo is transported by belt conveyors to the cement proportioning. The gypsum is added to the clinker. Then the proportioned materials are conveyed via belt conveyor to cement grinding. Materials ground by ball mill are transported separator by bucket elevator. The coarse particles separated return to ball mill for regrinding while the fine product is collected by the bag filter behind the separator and then conveyed to cement silo with an air slide and bucket elevator. Cement silos is used to store the cement.

Cement mill

4-Cement packing

The cement from extraction systems under the cement silo is delivered to the buffer bin by air slide and the bucket elevator and vibrating screen, before being fed into each packer. The bagged cement can be loaded directly or stored in storehouse temporarily.

Machinery and Equipments:

No. Name function

1 Limestone Crusher used in stone quarry to crush limestone

2 Clay crusher used in stone quarry to crush clay

3 Limestone Stacker Used to move limestone to preblending stockpile

4 Limestone reclaimer Used to take preblended mixture from preblending stockpile

5 Coal and iron ore Crusher Used to crush additive materials

6 Coal and iron ore Stacker Used to move iron ore to conveyor belt then to proportioning station

7 Coal & iron ore reclaimer Used for reclaiming all additive materials and coal

8 Raw mill used for raw materials grinding and drying

9 Raw mill fan Used to adjust the mill inlet temperature.

10 Preheater fan used to dry the raw materials

11 Preheater and precalciner Preheater used for preheating and partial decarbonation, and precalciner for calcination

12 Rotary kiln used to raise raw materials to a high temperature

13 Grate cooler Used for quenching

14 Cement mill Used to grind cement

15 Bag filter Used to collect dust

16 Coal mill Used for coal drying

17 Bulk loader for truck Used to load the bulk

18 Cement packer Used to pack cement product

Quality control system:

The quality control department in the Oman cement company function is to monitor product quality in every stage of production starting with extracting the limestone from the quarry till the stage of cement mills, by taking samples and analysis them.

1- The computer and x-ray analysis:

The automation lab consists of robot, x-ray spectrometers, laser particle size analyzer and computerized physical properties.

The samples will be taken by an automatic sampler from a point between the raw mill and homogenizing silo and then transported manually to the central auto lab, where it will be semi-automatically prepared and sent to an X-Ray analyzer. The results analyzed will be sent to a proportioning computer. The computer will calculate the ratio of raw materials and send out the set value to constant feeder according to the chemical compositions and raw meal module required.

2- Physical analysis:

To test the fineness, soundness, setting time, strength, specific gravity, heat of hydration and loss on ignition of the cement to achieve the American specifications requirement.

Maintenance procedure:

The department functions are:

-Checking all machinery and equipments are work properly.

-Scheduling and planning for preventive maintenance, predictive maintenance.

– Coordinating with all departments for daily problem.

– Planning, coordinating of preventive and breakdown activities for achieving high plant availability to meet production target.

The procedure that the Oman cement follows in case of breakdown, preventive and shutdown maintenance are:

1. Breakdown maintenance

In case of any breakdown maintenance in the production department, they give information regarding the breakdown to the maintenance department, and maintenance workers are sent to the production plant to fix machine failures.

2. Preventive maintenance

here, a team of maintenance workers is sent directly to the production plants to check out whether there is any failure in the machinery or not.

3. Shutdown maintenance

When the plant is shut down the employees in the production department sent a letter to the maintenance department and successive steps are taken by maintenance department to solve the failures. The plant shutdown occurs every 6 month in March and September.

The process of operating and monitoring production lines and machines instantly, so they can watch the failure and damage of the machines and equipments to repair them or replace them.

Technical management

The technical management responsibility is to supervise all the mechanical, electrical things and maintain the various equipments and everything that related to maintenance procedure, and this management divided in many sections:

a- The machine section

The responsibility of this section is prepare emergency and planning schedule and do it to all the equipments and report it to diagnose the unusual failure and fix it. Inspect the machinery, check with drawings and specifications and rectification. It contacts with store section to provide the required replacement parts and also contacts with other sections to maintain the equipments at the workshop.

At the workshop they fix the equipments in emergency conditions, check the equipments if they work properly and routinely, takes care the equipments and help to clean them.

b) The machine operation section

The responsibility of this section fabricate the replacement parts, make an order outside the company to get new parts, lathe the machine parts the required the workshops.

c) The immediate machine maintenance section

The responsibility of this section is to check and fix the production lines.

d) The electrical section

The electricity department is responsible to repair and ensure the continuation of the work of all electrical and electronic equipment and precision instruments on the production line and also supervises contact with other sections to that the electricity working properly.