FIELD OF THE INVENTION:
The present invention relates to a method of coating of sinter product with fine particles adaptable to burden for metallurgical application.
BACKGROUND OF THE INVENTION:
In India, iron ores from run of mines are available in various sizes. Among them lump ore having a size (-40 + 10 mm) are used directly in the blast furnace. The ores having an under size (-10 + 0.15 mm) is used in sinter making process. A good quality iron ore sinter consumable in the blast furnace is prepared from a raw sinter mix comprising a) iron bearing materials, b) basic fluxes including a source of CaO and a source of MgO and c) carbon bearing material commonly coke breeze, used as a heat-generating combustible. The raw sinter mix is subjected to a sintering treatment at a high temperature inorder to cause the iron-bearing materials fluxes and carbon bearing material to agglomerate and sintered by incipient fusion followed by an air cooling treatment in order to produce a

hard lumpy product having a porous cellular structure and thereafter, a mechanical treatment to break the lumpy substance into a specific size range.
The iron ores having a size -0.15 mm is utilized in pellet making. A major percentage of ultrafine iron ore still remain unutilized. The utilization of these ultrafine iron ores in metallurgical application is still under research stage. The ultrafine iron ore needs to be agglomerated as otherwise they cause blockade in the inside burden passages and the result of which a hindrance of burden movement inside the blast furnace shall cause 'hangs'. Secondly, the agglomeration needs energy, thus increasing the cost and fuel consumption. The inventors emphasize on effective utilization of such non-usable and wasted ultrafine iron ore and this invention explores the possibility of charging such ultrafine iron ore as a carrier with existing sinter product. Such new method of ultrafine iron ore utilization has numerous and unexpected advantages over the use of common iron ore sinter without affecting environment.

OBJECTS OF THE INVENTION:
It is therefore, an object of the present invention to propose a method of coating on sinter product with iron ore fines which eliminates the disadvantages of existing state of arts.
Another object of the present invention is to propose a method of coating on sinter product with iron ore fines which prevents air pollution in the environment.
A further object of the present invention is to propose a method of coating on sinter product with iron ore fines which saves national resources.
A still further object of the present invention is to propose a method of coating on sinter product with iron ore fines which saves health hazards of the employees.
A yet further object of the present invention is to propose a method of coating on sinter product with iron ore fines which increases the productivity of the metallurgical reduction and smelting application.

A still further object of the present invention is to propose a method of coating on sinter product with iron ore fines which increases RDI of the sinter product.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES:
Fig. 1 shows a flow chart of the new method of coating of sinter product as per invention.
Fig. 2 shows a sectional view of coated sinter product.
Fig. 3 shows a photo view of mixing drum.
DETAILED DESCRIPTION OF THE INVENTION:
The invention relates to a new method of coating of sinter product with ultrafine iron ores such that the ultrafine iron ore acts as a carrier of sinter product. The coating was done with the help of some adhesive material like binder which are commonly used as Dextrin, phosphate binder, lignin based binders, Hydrated Lime, Caustic Soda, Molasses, etc. A number of trials were conducted for coating on the sinter product out of which two sets of experiments (Set A and Set B) have been elaborately described below:

Experiment set A (Table 1)
1. Dry sinter, were measured and soaked in binder and coal fines slurry. The above was kept in three different tanks and were kept in vacuum for 7-8 hours. In all the cases an increase in 0.5-2% of the weight was observed.
2. Wet sinter was rolled and tumbled in dry coal fines and after tumbling of 4-7 mins binders were sprayed, an increase in 2-4% of the weight was observed.
3. Wet sinter was rolled and tumbled in dry coal fines and after tumbling of 4-7 mins binders were sprayed. The samples were then subjected to heat treatment in muffle furnace at 500°C for about 3-5 hrs, an increase in 2-4% of the weight was observed.
4. Wet sinter was rolled and tumbled in dry iron ore fines and after tumbling of 4-7 mins binders were sprayed, an increase in 1-3% of the weight was observed.
5. Wet sinter was rolled and tumbled in dry iron ore fines and after tumbling of 4-7 mins binders were sprayed. The samples were then subjected to heat treatment in muffle furnace at 500° for about 3-4 hrs, an increase in 1-3% of the weight was observed.

Experiment set B
Experiment-1
In this experiment coating is done by dipping the sinter sample in iron ore slime slurry. The percentage of binders was varied from 2-12%. The maximum increase in weight was observed in the range of 2-7% binders used. It was also observed that the percentage of binder did not affect the net increase. Table 2.

Experiment-2
Sinter having a size of 10 mm to 15 mm was dipped in water tank and was rolled in a drum containing ultrafines. Binders dissolved in water (equal ratio), were then sprayed through a nozzle. The binder used was 8-15% of the weight of the sinter. The sinters were thoroughly mixed with ultrafine iron ore containing in a mixing drum which is rotating at 60 RPM. The coated sinter was then taken out from the mixing drum and allowed to dry for 3-4 hrs in sun. Maximum increase in weight was in the range of 10-30%. Table 2.
Note: In all the experiments sinters used were approx 25 kg in weight. The mixing drum used is as given in Fig 2.
Drop test and RDI of the sinter
The above samples were dropped 5 times from 5 ft height and net weight reduced 3-7 points. Sinter samples, coated and uncoated were sent for RDI. The RDI of the uncoated samples varied from 28-31. The RDI of the coated sample varied in the range of 32-35.

WE CLAIM:
1. A method of coating on sinter product with ultrafine particles
adaptable to burden of blast furnace and metallurgical
application, comprising of following steps:
- wetting the sinter products either by dipping a plurality of sinter
products in water tank or by spraying water on sinter products;
- rolling the wet sinter products in a drum containing ultrafines;
- spraying a binder dissolve with water on the sinter products by means of a nozzle;
- mixing thoroughly the sinter product in a mixing drum containing ultrafines for a period of 10 minutes, preferably for 4-7 minutes;
- drying of wet coated sinter to remove the water.
2. The method of coating on sinter product as claimed in claim 1
wherein the ultrafine particles used are ore fines comprising
iron ore, chromite ore, manganese ore or their combination.

3. The method of coating on sinter product as claimed in claim 1 wherein the ultrafine particles used are ore fines comprising iron ore, chromite ore, manganese ore or their combination.
4. The method of coating on sinter product as claimed in claim 1 wherein the binders comprising either Dextrin, starch and their derivatives phosphate based binder, lignin based binder, Hydrate Lime, Caustic Soda, Molasses or their combination.
5. The method of coating on sinter product as claimed in claim 1 wherein the binder was used 8-15% of sinter weight.
6. The method of coating on sinter product as claimed in claim 1 wherein wet coated sinter is dried for 3-4 hours in sunrays.
7. The method of coating on sinter product as claimed in claim 1 wherein weight of sinter products was increased by 10-32%.
8. The method as claimed in claim 1 wherein the size of each sinter product is ranging from 6 to 40 mm.

9. The method as claimed in claim 1 wherein the RDI of coated sinter is 32-35 after a drop test from 5 ft height.

The present invention is provided with a method of coating on sinter product with ultrafine particles adaptable to burden of blast furnace and metallurgical application, comprising of wetting the sinter products either by dipping a plurality of sinter products in water tank or by spraying water on sinter products; rolling the wet sinter products in a drum containing ultrafines; spraying a binder dissolve with water on the sinter products by means of a nozzle; mixing thoroughly the sinter product in a mixing drum containing ultrafines for a period of 10 minutes, preferably for 4-7 minutes; drying of wet coated sinter to remove the water.