DWIGHT LLOYED SINTERING MACHINE

Dwight Lloyed

Principle:

The Dwight lloyed sintering machine is essentially for band of pallets moving over rails, stretched across and over two huge pulleys, one of which is driven by a motor through a reduction gear system. The raw material are loaded at the end of the machine and top layer is ignited as it under a fixed ignition hood.

● As the pallets moves, the ignited portion comes over a series of stationary wind boxes connected to an exhaust blower. Sintering of the charge is completed by the time of pallets travels over nearly the whole useful length of the machine.

● The sintered cake drops out at the other end when the pallets turn upside down. The cake is broken, screened and oversize is cooled. The usually under size is 9mm, is returned to the machine for resintering where as the oversized after rescreening goes to the blast furnace as charged.

● From the discharge end the pallets returned to feed end in inverted overhung fashion on rails. The exhaust gases from the wind boxes are let off in to the atmosphere through a chimney after dust extraction.
Dwight-Lloyed sintering machine
Dwight-Lloyed sintering machine

● The important parts of the machine and it's asscesories that make complete sinter plant are:
1. Storage bins, mister, feeder.
2. Charge leveller
3. Band of pallets and rail for its movement.
4. Ignition hood.
5. Drive mechanism.
6. Sinter breaker, screen, cooler etc.
7. Spillage collected.
8. Windboxes, dust extractor, exhaust fan.
Chiminy etc.

Recent Treands in sintering practice : 

Now coke and cool are being used in blast furnaces. The sinter is aimed to be better reducible. Sintering with low heat input can lead to these objectives :

1. Better reducibility.
2. Less slag volume.
3. Good high temperature properties like softening and melting characteristics.
4. Optimum strength and RDI.

●  These have resulted in changes in sintering practices as follows :

1. Use of magnesium silicate mineral as flux in sinter-mix.
2. Use of quick-lime as flux in sinter-mix to improve upon the bonding.

3. Increase in depth of sinter bed from usual 350-400mm to 600-650mm. This has resulted in much higher productivity and decreased coke rate by about 5-10kg/t  sinter. This has been actually been achieved at Tata Steel.

4. Deeper bed logically leads to adoption of double layer sintering, I.e. different coke percentages in the two layers higher in the top and lower in the bottom. This saves coke breeze rate by about 4kg/t sinter and reduced blast rate by about 0.5Nm3/t sinter.

5. Oxygen enrichment of the igniting fuel gas and extending the ignition area by about 10% more by extending and better shatter strength.

6. Nearly 50% of the heat required in sintering is discharged in the open atmosphere as waste heat. Sintering process consumes nearly 10% of the total energy required in an integrated steel plant. Heat recovery systems have been developed by the Kokura Steel works of symptoms metal industries, Japan.

7. For low production of sinter China has development an alternative to standard sintering  machine. It's capital cost is half that of the standard machine.

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