Location: Kashan, Isfahan
client: Moshfeq Industrial Development Co.
services: Site Supervision
DRI Plant (with Tunnel Kilns)
Here is a summary of the activities Vista Faraz Co. monitors and certifications it issues as field supervisor:
- Contractors’ site mobilization
- Contractors’ observance of all the HSE rules
- All tests carried out by the material laboratory located on the site as per the standards
- Issuing work permits for construction at different stages and approving the concreting prerequisite operations
- Manpower supply
- Quality and quantity of equipment and machinery
- Handling of materials and equipment
- Different stages of the installation of equipment and heavy steel frames
- Plumbing and ducting
- High voltage cabling
- Construction of medium and low pressure electrical substations and installation of switchgears
- Set-up of automation, control, and instrumentation systems
- Plumbing of hydraulic systems, welding, and leak tests
- Installation of hydraulic power units
- Installation of pneumatic equipment and systems
- Installation of fire-fighting systems
- Execution of refractory masses
- Installation of telecommunication and audio systems in the factory premises
- Commissioning process of all the installed equipment, systems and tools
- Start-up with the incoming flow of raw materials
- Quality assurance tests of equipment and systems
- Provisional acceptance of the contractors’ work
- Final acceptance of the contractors’ work
How to produce DRI using tunnel kilns
The operations department of the DRI plant consists of the following sections:
Incoming materials preparation area
Dehumidification of the concentrate
Crushing and granulation of pellets
Preparation of lime and coal
Loading, which consists of the following:
Lime and coal loading
Concentrate loading
Inspection
Lime and coal loading
Mold handling
Product preparation area
Ash discharge
Sponge iron discharge
Product crushing in a machine with three sections: feeder, jaw crusher, and hammer crusher.
Briquetting
There can be direct rotary or even multi-story kilns depending on the place of construction, with capacities of 5000 metric tons and more.
Refractory/fireproof containers for loading iron concentrate are made of silicon carbide or materials resistant to thermal shock.
Production process:
Raw materials that include powdered iron-ore concentrate (hematite or magnetite), oxide shell, soft pellet, coal and lime, are put into the dryer one by one to reach a humidity below 2%.
After that, the containers are placed on the car and taken into the kiln, so that the materials will be reduced by coal.
Reduction time: 40 to 50 hours
Maximum temperature of the kiln: 1220 degrees Celsius
Reduction temperature: 1140 to 1180 degrees Celsius
Kiln pressure: controlled
Material inlet temperature: ambient temperature
Material outlet temperature: about 70 degrees Celsius
DRI Kiln requirements:
After loading, the materials enter the kiln and are placed in the three zones of pre-heating, reduction and cooling, so that the reduction takes place.
Tunnel kilns:
By controlling the quality of raw materials, it is possible to increase the grade of sponge iron to over 95%. This type of DRI is fairly resistant to self-heating.
A briquetting machine can be added to the production line to change the product’s density. The gangue can be reduced by a magnetic separator. The product can be used in the induction furnace after briquetting.
Having a unit with a suitable capacity, the investment return time is less than three years. This method is cheaper than the Midrex method.