FIELD OF THE INVENTION

The present invention relates to a binder for sinter mix suitable for making pellets such as in iron ore sintering and, more particularly, to Ilmenite (FeTiO3) process industry waste based binder suitable for iron ore sinter raw mix in iron ore pellet plants and a process for sinter production involving said waste based binder. Importantly, the present invention is directed to a simple, cost effective and environment friendly process for sinter production ensuring achieving improved permeability of bed and higher productivity utilising Ilmenite process industry waste.

BACKGROUND OF THE INVENTION

The existing system in sinter making utilizes constituents like Mill scale (generated in-house and procured from other industries), sludge (waste from steel melt shop) and flue dust (waste from blast furnace) as some of the iron bearing wastes generated in steel industries. Many of these wastes (as well as beneficiated iron ore fines) are of very small size (<100 nanometers), designated as super fines/ultra fines. Due to the excessive fineness of these and very poor permeability, results in decreased productivity, when used as such, in sinter making. Hence, to improve bed permeability, these super fines are pelletised/nodulised to a size range measuring between 2-6mm, before being used in sinter making.

The industrial wastes containing iron/iron oxide is conventionally used in sinter making due to the following advantages:

1. to utilize iron value available in industrial wastes;

2. as a waste recycling measure to promote cleaner environment;

3. as a partial substitute for iron ore;

4. to conserve natural resources;

5. to minimize cost;

6. to conserve space which would otherwise be occupied by these wastes.

Due to the advantages of utilizing iron bearing wastes contents as cited above and heavy demand for iron ore, a rigorous search was conducted as a precursor to the present invention for alternative sources of iron bearing industrial wastes (available elsewhere) that could potentially be utilized in sinter making.

It is well known in iron and steel industries, that formation of balls (of sinter raw mix)/pellets is considered a crucial step in sinter making, as it improves bed permeability. Better the balling, the higher is the permeability. Higher the permeability, higher will be the bed height and productivity. Calcium oxide (present in lime) due to its excellent binding properties tends to facilitate ball formation. Conventionally used binders are burnt lime fines (0-3 mm size), bentonite, starch etc. Applicants co-pending Patent Application No: 4732/CHE/2012 dated 12.11.2012 disclosed use of higher sized burnt lime with a size range of 0-10 mm (granular burnt lime) in order to increase sinter productivity by ensuring improved permeability.

There has been thus a need in the relevant art to introduce alternative iron bearing wastes in sinter raw mix which will help forming pellets/balls for sinter making by providing additional attributes of a good binder.

OBJECTS OF THE INVENTION

The basic object of the present invention is thus directed to a binder adapted for peptization of sinter raw mix.

According to another aspect of the present invention there is provided a sinter charge comprising a binder adapted for facilitating peptization of sinter raw mix.

Yet another object of the present invention is thus directed to Ilmenite (FeTi03) process industry waste based binder with improved iron value replacing burnt lime in raw sinter mix, and a process for sinter production using said binder ensuring increased sinter bed permeability and productivity.

A further object of the present invention is directed to Ilmenite (FeTiO3) process industry waste as binder and a process for sinter production using said binder in sinter raw mix for utilisation of wastes with iron value generated from industries other than iron and steel industries.

A further object of the present invention is directed to a process for sinter production using Ilmenite (FeTiO3) process industry waste as binder in sinter raw mix for conservation of iron ore as natural resource.

A further object of the present invention is directed to a process for sinter production using Ilmenite (FeTiO3) process industry waste as binder which would produce sinter with improved quality and higher strength thereby reducing the sinter fines generation.

A further object of the present invention is directed to a process for sinter production using Ilmenite (FeTiO3) process industry waste as binder to enable use of a new and alternate material in sinter making thereby ensuring productive utilization of wastes.

A further object of the present invention is directed to a process for sinter production using Ilmenite (FeTiO3) process industry waste ensuring increase in permeability of sinter bed and enhanced sinter production with reduced power consumption and reduced sinter fine generation.

SUMMARY OF THE INVENTION

Thus according to the basic aspect of the present invention the same is directed to a binder adapted for peptization of sinter raw mix comprising:

comprising of industrial waste including a combination of iron oxide as iron value in the presence of iron hydroxide.

A further aspect of the present invention is directed to said binder comprises Ilmenite process industry waste comprising said combination of iron oxide as iron value in the presence of said iron hydroxide.

Yet another aspect of the present invention is directed to said binder comprising Ilmenite process industry waste which comprises iron oxide as iron value in amounts of 24.15% to 35.88% preferably about 30%.

Based on the above findings, a process for the production of iron ore pellets has been proposed by way of the present invention for the first time using Ilmenite process industry waste replacing burnt lime in raw sinter mix which on one hand provide enhanced iron value and on the other hand act as binder to form pellets of higher size and strength favouring increased bed permeability and sinter productivity with reduced sinter fines generation. As a result of which, a new waste material obtained from Ilmenite process industry, was found to be suitable for the intended purpose.

Titanium normally occurs as oxides in combination with iron. The two most common titanium ores are: Ilmenite (FeTiO3), occurs either as sand or rock deposits and Rutile (TiO2), occurs as rock deposit, which is relatively rare. Ilmenite is the most abundant and cheapest mineral available for the metal titanium. As Ilmenite is associated with large concentration of iron oxide, Ilmenite process industries (such as those involved in mining, mineral separation and value addition activities) generate huge quantities of wastes, which contain various forms of iron oxides viz. iron hydroxides, hydrated iron oxides and iron oxide, depending upon moisture content and temperature.

Moreover, the Ilmenite process industry waste was found to be sticky and flatten under load (resembling clay), which could be attributed to the presence of iron hydroxide.

Based on these properties, it was envisaged to exhibit good binding properties. In order to ascertain its binding properties, permeability studies were conducted using this waste in sinter raw mixes.

According to a further aspect of the present invention directed to said binder having Particle size in the range of 0.075-0.5 mm.

A still further aspect of the present invention is directed to a sinter charge comprising a binder adapted for facilitating peptization of sinter raw mix comprising:

industrial waste including a combination of iron oxide as iron value in the presence of iron hydroxide.

A still further aspect of the present invention is directed to a sinter charge wherein said binder comprises Ilmenite process industry waste comprising said combination of iron oxide as iron value in the presence of said iron hydroxide.

A still further aspect of the present invention is directed to a sinter charge wherein said
binder comprises Ilmenite process industry waste comprising iron oxide as iron value in amounts of 25.15% to 35.88% preferably about 30%.

Importantly, said sinter charge is adapted for sinter bed permeability in the range of 150 to 250 preferably 195.

According to a further aspect of the present invention, there is provided a process for sinter production involving binder as described above comprising:

providing a sinter charge comprising of said binder adapted for pelletization of sinter raw mix comprising industrial waste including a combination of iron oxide as iron value in the presence of iron hydroxide;

subjecting the above sinter charge to step of sintering to obtain micropellets /nodules in the size ranging from 2-6 mm.

A further aspect of the present invention is directed to said process for sinter production wherein said industrial waste comprises Ilmenite process industry waste comprises iron oxide as iron value in amounts of 24.15% to 35.88% preferably about 30%.

A still further aspect of the present invention is directed to a process for sinter production comprising the steps of

(i) providing a raw mix for pelletisation comprising

Components Sinter charge (wt %)

Iron ore fines 45 to 60 preferably about 47.8

Ilmenite process industry waste 1 to 7 preferably about 5.0

Coke breeze 5 to 6 preferably about 5.5

Sinter return fines 15 to 30 preferably about 25.3

Limestone 2 to 7 preferably about 4.2

Dolomite 5 to 8 preferably about 6.8

Solid waste 3 to 14 preferably about 7.9

(ii) subjecting the raw mix to pelletisation in ball mill with improved binding resulting in
the formation of well defined balls leading to increased voids between balls and enhanced permeability;

(iii) subjecting the pellets to sintering operation to form sinters for higher strength with reduced sinter fines generation.

Advantageously, said process for sinter production is adapted to increase the productivity up to a level of 1.27t/m2/nr and ensure sinter bed permeability in the range of 150 to 250 preferably 195.

The objects and advantages of the present invention are described in greater details with reference to accompanying illustrative example.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is thus directed to binder suitable for sinter mix adapted for pelletization and esepcially in advancements relating to providing such suitable binders involving industrial waste with special binder characteristics .As disclosed hereinbefore one such indutrsial waste suitable for the purpose of the present advancement is Ilmenite (FeTi03) process industry waste with iron value as a binder and accordingly the advancement further relates to process for sinter production using said binder in sinter raw mix which is surprisingly compatible with burnt lime with improved sinter bed permeability, sinter productivity and reduced sinter fine generation.

It has already been observed that binder obtained of such industrial waste which can be sourced from Ilmenite industrial waste is advantageous since Ilemenite waste is one of the most abundant and cheapest mineral available for the metal titanium. As Ilmenite is associated with large concentration of iron oxide, Ilmenite process industries (such as those involved in mining, mineral separation and value addition activities) generate huge quantities of wastes, which contain various forms of iron oxides viz. iron hydroxides, hydrated iron oxides and iron oxide, depending upon moisture content and temperature.

Furthermore, it has been found by way of the present advancement that the Ilmenite waste based binder was found to be selectively sticky and flatten under load (resembling clay) in the presence of iron hydroxide and accordingly exhibited good binding properties.

The suitability of Ilmenite process industry waste based sinter production /peptization as provider of iron value in sinter raw mix and also as a binder favouring pellet formation and improved permeability, experiments were conducted as illustrated through the following example:

EXAMPLE:

(1) According to an embodiment of the present invention, iron oxide based waste obtained from Ilmenite process industry was selectively provided in sinter mix for sinter production having the composition as presented in following Table 1.

Table 1:

It can be seen from Table 1 that, the selected waste contained high iron and high moisture contents. At high moisture levels, iron exists as iron hydroxide in Ilmenite process industry waste, as evidenced by its bluish green tinge, which on subsequent exposure to air and temperature, turns to brownish hue due to the formation of iron oxide. Moreover, the waste is found to be sticky and flatten under load (resembling clay), which is attributed to the presence of iron hydroxide, indicative of good binding properties. In order to ascertain its binding properties, permeability studies were conducted using two sinter raw mix samples: (i) one containing burnt lime and (ii) the other containing 5% of Ilmenite process industry waste having composition as in Table 1, in place of burnt lime. Permeability tests were conducted with the above two sample mixes to illustrate that Ilmenite process industry waste based binder exhibited better binding characteristics, as well as improved permeability of sinter charge (containing Ilmenite process industry waste) even without burnt lime and is found to be advantageously comparable to or better than the sinter charge with burnt lime (as better binding results in the formation of well defined balls leading to increased voids between balls and improved permeability). Comparison of permeability of sinter charge with granular lime and sinter charge with Ilmenite process industry waste is presented in following Table 2.

Table 2 :

It is seen from Table-2 above that the permeability of sinter raw mix containing Ilmenite process industry waste based binder is marginally better than the sinter raw mix containing burnt lime. It indicates that, burnt lime can be replaced by Ilmenite process industry waste, forming a part of sinter raw mix.

Based on above findings, as the iron oxide waste material obtained from Ilmenite process industry, involved considerable iron value, it is successfully used in sinter making. Also as the Ilmenite process industry waste based binder possesses good binding properties, it is fauvoured as a binder in place of burnt lime in sinter mix.

Addition of Ilmenite process industry waste based binder as a part of sinter raw mix (about 5-7% in raw mix) by replacing burnt lime was further trialed in sinter mills for regular production. It was observed that, the role of Ilmenite process industry waste based binder advantageously served two fold purposes by way of (a) imparting its iron value and (b) acting as binder replacing burnt lime. During the trials, it was also observed that, there was surprisingly a drastic reduction in the generation of sinter return fines. This indicates that, the sinter produced by using Ilmenite process industry waste possesses higher strength and hence improved quality than the one produced in its absentia.

Various parameters such as permeability, sinter quality, productivity etc. were monitored during these trials. It was observed that, apart from an increase in permeability, there was a marginal improvement in productivity. A comparison of various operating parameters recorded during these trials is presented in the following Table 3.

Table 3:

The above comparative data clearly show that there is substantial reduction in sinter return fines generation by introducing Ilmenite process industry waste as binder replacing burnt lime in sinter raw mix and considerable increase in sinter production rate per day.

The various benefits derived by way of the process of sinter production according to the present invention are summarized as follows:

1. An increase in sinter productivity from 1.25 t/m2/nr to 1.27 t/m2/hr.

2. A reduction in power consumption from 46 KWH/t of sinter to 45 KWH/t of sinter.

3. Replacement of burnt lime by Ilmenite process industry waste as binder.

4. A substantial reduction in the generation of sinter return fines.

It is thus possible by way of the present invention to providing for the first time a binder for sinter raw mix from industrial process waste such as Ilmenite process industry waste base binder of the present invention and a process for sinter production using the same replacing conventional burnt lime based binder whereby on one hand sinter quality and strength is improved and on the other hand provide iron value through the iron oxide based waste as binder ensuring enhanced sinter production rate and reduced sinter fines generation. The process according to the present invention is thus capable to offer a host of benefits such as utilisation of wastes generated from other industries, conservation of natural resource (iron ore), use of a new and alternate material in sinter making, reduction in environmental impacts of extraction and processing of raw materials as a result of co-processing etc.

We Claim:

1. A binder adapted for pelletization of sinter raw mix comprising:

industrial waste based binder including a combination of iron oxide as iron value in the presence of iron hydroxide.

2. A binder as claimed in claim 1 comprising Ilmenite process industry waste comprising said combination of iron oxide as iron value in the presence of said iron hydroxide.

3. A binder as claimed in claim 2 wherein said Ilmenite process industry waste comprising iron oxide as iron value in amounts of 24.15% to 35.88% preferably about 30%.

4. A binder as claimed in claim anyone of claims 1 to 3 having Particle size in the range of 0.075-0.5 mm.

5. A sinter charge comprising a binder adapted for facilitating pelletization of sinter raw mix comprising:

industrial waste including a combination of iron oxide as iron value in the presence of iron hydroxide.

6. A sinter charge as claimed in claim 5 wherein said binder comprises Ilmenite process industry waste comprising said combination of iron oxide as iron value in the presence of said iron hydroxide.

7. A sinter charge as claimed in anyone of claims 5 or 6 wherein said binder comprises Ilmenite process industry waste comprises iron oxide as iron value in amounts of 24.15% to 35.88% preferably about 30%.

8. A sinter charge as claimed in anyone of claims 5 to 7 adapted for sinter bed permeability in the range of 150 to 250 preferably 195.

9. A process for sinter production involving binder as claimed in anyone of claims 1 to 4 comprising:

providing a sinter charge comprising of said binder adapted for peptization of sinter raw mix comprising industrial waste including a combination of iron oxide as iron value in the presence of iron hydroxide;

subjecting the above sinter charge to step of sintering to obtain micropellets /nodules in the size ranging from 2-6 mm.

10. A process for sinter production as claimed in claim 9 wherein said industrial waste comprises Ilmenite process industry waste comprising iron oxide as iron value in amounts of 24.15% to 35.88% preferably about 30%.

11. A process for sinter production as claimed in anyone of claims 8 to 10 comprising the steps of

(i) providing a raw mix for pelletisation comprising

Component Sinter charge (wt %)

Iron ore fines 45 to 60 preferably about 47.8

Ilmenite process industry waste 1 to 7 preferably about 5.0

Coke breeze 5 to 6 preferably about 5.5

Sinter return fines 15 to 30 preferably about 25.3

Limestone 2 to 7 preferably about 4.2

Dolomite 5 to 8 preferably about 6.8

Solid waste 3 to 14 preferably about 7.9

(ii) subjecting the raw mix to pelletisation in ball mill with improved binding resulting in the formation of well defined balls leading to increased voids between balls and
enhanced permeability;

(iii) subjecting the pellets to sintering operation to form sinters for higher strength with
reduced sinter fines generation.

12. A process as claimed in anyone of claims 8 to 11 adapted to increase the productivity up to a level of 1.27t/m2/nr and ensure sinter bed permeability in the range of 150 to 250 preferably 195.