Manufacturing Process Of Cement

The main constituents Limestone, Alluvium and shale are obtained from captive mines at Al Tawayeen, Dibba and Bushera area. Bauxite, Kaolin, Laterite, Iron ore, Gypsum and other materials are imported.

CRUSHER:

We have two crushers of 1800 TPH (Unit-I 550 TPH and Unit-II 1250 TPH) for crushing Limestone , Alluvium and Shale.

The crushed product size of 0-25 mm, called premix is then shifted through belt conveyor to the stacker in the premix storage shed.

The pre-crushed Limestone is transported to the works by road and the chevron stacking/CBS method is used to reclaim and obtain high efficiency raw material blending. Limestone is transported to the designated hopper for grinding. After storage, the additive raw materials such as kaolin and iron ore are transported to the designated hopper for raw mix proportioning through weigh feeders for grinding at the Ball Mills/Roller Mill to achieve the desired raw mix.

Coal and Gypsum are received by trucks and are stored at the covered storage yard. Thereafter, they are transported through designated hoppers to the air-swept ball mill for blending and grinding.

RAW MATERIALS (LINE-1):

The Pre-mix is drawn from stock pile to storage bin beside the raw mill. The Pre-mix materials and additives-Kaolin and Iron Ore  are proportionately fed to the raw mill for drying, grinding and blending. Hot gases are drawn from pre-heater for circulation through the mill.

The mills have a grinding capacity (total 340 TPH Residue at 90 MIC is 18 percentage.) of ball mill-1, 180 TPH ball mill-2, 160 TPH. The product is elevated to dynamic separator where oversize material is returned for regrinding and the fine product which is the feed material for the kiln is conveyed to the two homogenization silos each of 5000 tons capacity.

RAW MATERIALS (LINE-2):

Feed materials for grinding in the mill to meet the raw mix formulation are stored in four hoppers and dosed by separate weigh feeders.

The Vertical Roller Mill (QUADRAPOL) has a grinding capacity of 540 TPH, grinds the raw material into fine powder by applying hydraulic pressure through rollers inside the mill.

Ground material then passes through a classifier.  A total of 90 percent of the resulting raw meal is collected at the cyclone and rest at the main bag house. It is then transported to the blending cum storage silo.

The hot gas required during grinding is drawn from the pre-heater waste gas.

PREHEATER(LINE-1& II):

The raw meal is drawn from the homogenization silos, a SCHANK feed system is used to dose the feed to the five stage pre-heater.

The pre-heater is a form of heat exchanger where hot gas from the kiln is drawn up, and the fed raw material is partially calcined in process.

In line – I , a new 6 stage cyclone pre-heater was erected in the year 1994-95, in place of existing sket shaft pre-heater, with inline calciner for better heat recuperation to reduce the specific heat consumption by more than 20%.

Pulverized coal is used as a fuel for firing in the kiln as well as the PYROCLONE pre-calciner. It is finally converted in to ash and absorbed by the clinker during process. The mill is a two chamber, horizontal, cylindrical shell made of cast iron and the inside surface of which is bolted with liners made of manganese steel to prevent wear and tear of the mill body.

Inside the mill are different sized chromium steel balls, which act like a series of hammers to grind the coal into a fine powder. The pulverized coal is collected by the bag filters, stored in the bin and then transported to pre-calciner as well as to the kiln by pneumatic conveyor system for firing.

CAPACITY:

COAL MILL (LINE-1)            : 24 TPH

COAL MILL (LINE-2)            : 40 TPH

KILN/COOLER (LINE-1&2):

Clinker production capacity of the plant is 12,100 TPD, Unit-I(4,600 TPD) and Unit-II(7,500 TPD).

The pyro-system has been established with the most modern and advanced technology and equipment from POLYSIUS.  The kiln feed is fed through the bucket elevator, while a diverting gate separators feeds into the kiln-string and the pyro-string.

The kiln feed encounters the flow of hot gas generated from the firing in the kiln and pre-calciner. There is an exchange of heat between the raw meal and the hot air.

We have three closed ball circuit Cement Mills with a grinding capacity of 315 TPH in total.

Cement mill-1 of 100TPH at 2900-3000 cm²/gram Blaine

Cement mill-2 of 105 TPH at 3200-3300 cm²/gram Blaine

Cement mill-3 of 110 TPH at 2900-3000 cm²/gram Blaine.

The ground cement is stored in five silos for final dispatch.

A dynamic separator was installed in place of the old separator in cement mill-1 to improve the grinding capacity as well as the cement strength at lower fineness to meet the requirement of international standard for strength.

Road tankers are used for dispatching bulk cement and flat trailers for 50 Kg bagged cement. Bagged cement is packed in two six-spout automatic roto-packers of  100 tons per hour each.

We also have one of the most advanced BEUMER palletizing unit of 100 tons per hour capacity, making the units of  2.5 tons (50 bags) facilitating for easy loading and unloading using the fork lifts.

We also have facility of jumbo bag packing upto 2.5 tons of cement.

A boom conveyor is also installed at the packing plant for stuffing the cement bags in containers for export sales.