Description:FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

1 TITLE OF THE INVENTION :
A SYSTEM FOR PREHEATING OF IRON BEARING FINE MATERIALS USING WASTE HOT GASES FOR FEEDING IN FLUIDIZED BED REACTOR.


2 APPLICANT (S)

Name : JSW STEEL LIMITED.

Nationality : An Indian Company incorporated under the Companies Act, 1956.

Address : JSW CENTRE,
BANDRA KURLA COMPLEX,
BANDRA(EAST),
MUMBAI-400051,
MAHARASHTRA,INDIA.



3 PREAMBLE TO THE DESCRIPTION

COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:
The present invention relates to the field of mineral processing especially roasting of iron ore fines / slime/iron ore tailings. More particularly, the present invention is directed to provide a preheating device for heating iron ore fines or slime/iron ore tailing to be charged as feed in a fluidized bed chamber for roasting or any other similar process.

BACKGROUND OF THE INVENTION:
Beneficiation of low grade iron ore to meet growing demand for iron and steel is an important research topic because of the gradual depletion of high grade iron ore. Many of the low grade iron ore (less than 45% Fe) does not qualify to be treated in physical separation process and hence alternative technologies are being looked into for upgrading their iron content. Also higher recovery from processing of low grade iron ore during upgradation is essential to make it economically viable and for sustainable development of steel industry.

Reduction roasting is one among the unconventional technique to upgrade low grade iron ore with high iron recovery. Historically reduction roasting of iron ore has been carried out any of shaft furnace, rotary kiln, fluidized bed or microwave roasting. Among all fluidized bed has the advantage of high heat and mass transfer rates, which leads to lower fuel consumption and better process economics.

The evolution of fluidized bed started with coal in the bed with technologies like swirl suspension magnetic roasting and circulating fluidized bed reduction roasting. Having coal in the bed resulted in disadvantages of difficulty in coal utilization, synchronization issue in process because of inconsistent coal combustion reaction, H2S problem and so on. So the next generation of fluidized bed reduction roasting technology concentrated on using gas as a reducing agent to overcome the afore mentioned problems. The gas based reduction roasting technologies were engineered in a way to utilize the sensible heat of gas and latent heat of unreduced gas.

Prior art:
1. China patent application CN104726690A - 2015/06/24 - discussed about three stage suspension roasting-magnetic separation method taking place in single chamber in sequential manner(i.e) heating, reduction and cooling respectively.
2.China patent application CN106048210A- 2016/10/26- invention consisted of two circulating fluidized bed reactor , one for oxidizing and preheating and another for magnetization roasting of heated materials.
3.China patent application CN114438310A- 2022/05/06-Process for producing iron ore concentrate through red mud suspension magnetization roasting-grinding separation.
4.China patent application CN108823400B- 2020-04-07-Integrated process and device for dry grinding and suspension roasting of refractory iron ore.
The above mentioned works used vertically placed preheaters to preheat the materials getting into fluidized bed and to remove LOI from that. Additionally, series of cyclone units are added to remove the materials from gas stream and to preheat the incoming cold material or to recover sensible heat from gas.
This adds engineering complexity into the process and to simplify this present invention provides a preheating system setup which recovers the combustion gas heat to higher extent in single apparatus/setup.

OBJECTIVE OF THE INVENTION:
The basic objective of the present invention is to develop a system for preheating iron bearing fine materials with higher thermal efficiency having flexibility of heating wider particle size range in a single apparatus/setup.

A further object of the present invention is directed to said preheating system for heating iron ore fines or slime/iron ore tailing to be charged as feed in a fluidized bed chamber for roasting or any other similar process.

A still further object of the present invention is to develop a system for preheating iron bearing fine materials with higher thermal efficiency for wider particle size range there by facilitating higher recovery from processing of low grade iron ore by way of reduction roasting in fluidized bed reactor.

SUMMARY OF INVENTION:
The basic aspect of the present invention is directed to a system for preheating solid materials including roasting of iron ore fines, slimes, iron ore tailings utilizing hot gases comprising:

solid material heater unit comprising a coaxially disposed inner tubular member surrounded by an outer tubular member defining therebetween an annular space for supply of the hot gas for heating;

said inner tube operatively connected to a solid material feeder at one end and internally supporting a screw conveyor means operatively connected to a drive motor to move the solid material for heating from a feed end to a heated solid material discharge end;

said hot gas feed inlet into said annular space being provided at the other end of said solid material feed inlet such that counter current flow between the hot gases from one end and the solid feed material from another end provide for energy efficient heat transfer and heating of the solid material.

A further aspect of the present invention is directed to said system wherein said hot gases inlet for transport of hot gases to said annular space is provided with a burner tube;

Said inner tube inside which the solid material is heated is transported through said screw conveyor, said screw conveyor rotated by means of a drive motor, coupled by means of a geared flange, such that the solid moves from left to right while the hot gases fed into said burner tube moves from right to left to attain a counter current flow therebtween.

A still further aspect of the present invention is directed to said system comprising a compensator including a moving mechanism adapted to move left and right to compensate shaft expansion and contraction due to thermal expansion.

Another aspect of the present invention is directed to said system which is operatively connected to a fluidized bed for supply of pre-heated iron ore fines, slimes, iron ore tailings comprising said discharge end including a hot discharge tube for preheated material discharge into said fluidized bed for further processing.
Yet another aspect of the present invention is directed to said system wherein said feeding bin is adapted to feed the iron bearing materials at a rate of 50-80 Kg/hr with particle size less than -3mm through said inner tube of the preheater.

A still further aspect of the present invention is directed to said system wherein one end of the screw conveyor shaft is attached to said compensator located near discharge end.

A still further aspect of the present invention is directed to said system wherein the preheater heats the solid materials in the temperature range of 800-850 Deg C by hot combustion gases from burner involving a cooperating thermocouple.

Above and other aspects of this invention are illustrated hereunder in details by way of example and are not limited to the accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Fig. 1: illustrates the assembly view of Fluidized bed reactor according to a preferred embodiment of the present invention.
Fig. 2: illustrates the preheating unit according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS:
The accompanying figure together with the detailed description below forms part of the specification and serves to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.
The present invention is now discussed in more detail referring to the drawings that accompany the present application. In the accompanying drawings, like and/or corresponding elements are referred to by like reference numbers. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. Before describing in detail embodiments that are in accordance with the invention, it should be observed that the embodiments reside primarily for a Preheater 2.
Accompanying Figure 1 illustrates the assembly view of fluidized bed reactor system 1where preheater 2 utility has been shown. The entire system is used to preheat the iron ore in preheater 2 and the preheated ore is transferred to fluidized chamber 3, where iron ore reduction roasting happens with reduction gases like CO/H2 and the reduced hot ore is transferred to cooling chamber 4.
Accompanying Figure 2 illustrates the preheater 2, which heats the material to the required temperature (max 850 deg c) for reduction roasting in fluidized bed. It comprises of a drive motor 2.1, mounted on drive side 2.4, which is connected to a screw conveyor 2.2 through a coupling 2.12. This screw conveyor moves inside inner tube 2.7, where the material fed from feeding bin 2.6 is transferred to U-type fluidized bed through the rotation of screw conveyor 2.2. The preheater 2 also comprises of an outer tube 2.8, which carries the hot combusted gases from the burner 2.9 through the burner tube 2.10 and the annular space between inner tube 2.7 and outer tube 2.8.Non drive side 2.3 comprises of a compensator 2.13 on which one end of the screw conveyor 2.2 shaft is attached.

Example 1:
The preheating of the sample is done by feeding 50-80 Kg/hr of solid materials in the feeding bin 2.6, at ambient temperature. The hot gas from the gas burner 2.9 works in such a way that when Max temperature(800-850 Deg C) is reached in thermocouple 2.15, the burner 2.9 stops combustion and cut off gases. Again when the temperature goes lesser than lower limit X, the burner 2.9 starts combustion and allow hot gases to pass through the annular space. The screw conveyor 2.2 is rotated at rpm of 5 to 8, which moves material inside the inner tube 2.7 and the hot material discharged to the next system through the 2.11 hot discharge tube.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not limiting. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention shall not depart from the spirit and scope of the technical solutions of the present invention, which shall all be covered by the present invention within the scope of the claims.
, Claims:We Claim:
1. A system for preheating solid materials including roasting of iron ore fines, slimes, iron ore tailings utilizing hot gases comprising:

said solid material heater unit comprising a coaxially disposed inner tubular member surrounded by an outer tubular member defining therebetween an annular space for supply of the hot gas for heating;

said inner tube operatively connected to a solid material feeder at one end and internally supporting a screw conveyor means operatively connected to a drive motor to move the solid material for heating from a feed end to a heated solid material discharge end;

said hot gas feed inlet into said annular space being provided at the other end of said solid material feed inlet such that counter current flow between the hot gases from one end and the solid feed material from another end provide for energy efficient heat transfer and heating of the solid material.

2.The system as claimed in claim 1 wherein said hot gases inlet for transport of hot gases to said annular space is provided with a burner tube;

said inner tube inside which the solid material is heated is transported through said screw conveyor, said screw conveyor rotated by means of a drive motor, coupled by means of a geared flange, such that the solid moves from left to right while the hot gases fed into said burner tube moves from right to left to attain a counter current flow therebtween.

3. The system as claimed in anyone of claims 1 or 2 comprising a compensator including a moving mechanism adapted to move left and right to compensate shaft expansion and contraction due to thermal expansion.

4. The system as claimed in anyone of claims 1 to 3 which is operatively connected to a fluidized bed for supply of pre-heated iron ore fines, slimes, iron ore tailings comprising said discharge end including a hot discharge tube for preheated material discharge into said fluidized bed for further processing.

5. The system as claimed in anyone of claims 1 to 4 wherein said feeding bin is adapted to feed the iron bearing materials at a rate of 50-80 Kg/hr with particle size less than -3mm through said inner tube of the preheater.

6. The system as claimed in anyone of claims 1 to 5 wherein one end of the screw conveyor shaft is attached to said compensator located near discharge end.

7. The system as claimed in anyone of claims 1 to 6 wherein the preheater heats the solid materials in the temperature range of 800-850 Deg C by hot combustion gases from burner involving a cooperating thermocouple.

Dated this the 16th day of February, 2023
Anjan Sen
Of Anjan Sen & Associates
(Applicant’s Agent)
IN/PA-199