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 :
STEEL SLAG BASED BRICK COMPOSITION FREE OF CEMENT FOR CIVIL CONSTRUCTION AND METHOD OF MANUFACTURING THEREOF.



2 APPLICANT (S)

Name : STEEL AUTHORITY OF INDIA LIMITED.

Nationality : Indian.

Address : Research & Development Centre for Iron & Steel,
Doranda, Ranchi, Jharkhand, India. PIN-834002.






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 adaptation of steel slag based brick composition for making bricks suitable for civil construction and a process to manufacture such bricks by combining steel slag with fly-ash and other additives. More particularly, the present invention is directed to a process to utilize steel slag generated during processing of hot metal with flux like calcined lime and dolo in BOF converter to produce liquid steel. The invention is directed to develop a process to use steel slag combined with fly ash generated from coal based power plant and other additives free of cement for manufacturing brick. The invention totally replaces the clay soil in the preparation of brick to conserve the nature. The present invention is directed to manufacture steel slag-fly ash based brick to achieve high cold compressive strength greater than 80 kg/cm2, water absorption less than 8% and deformation temperature greater than 1200oC, favouring advantageous use in construction of boundary wall and the like.

BACKGROUND OF THE INVENTION

The biggest part (about 70% - 80%) of solid waste arising in an integrated steel plant is metallurgical slag. Disposal or utilization of slag generated during iron making in Blast furnace or during steel making in converter have been a concern for long. Over the years external markets have been developed for blast furnace slags. But since the potential for internal recycling of steel slag is constrained by productivity and quality considerations, external markets are also required to be developed for the Steel Slag.

In view of steel slag having similar chemical composition and mineral phases of cement clinker, attempt has been made for developing “Steel Slag–Flyash” based Bricks, utilizing a combination of steel slag of steel plant and flyash from power plant, which would ensure enhanced strength and other desired end properties of the bricks for civil construction application. In view of utilizing steel slag as a measure for “Waste to Wealth” initiative, BOF Slag in combination with fly-ash, bricks with adequate properties suitable for civil construction have been manufactured by way of this invention.

In BOF steel making process, 140-150 kg steel slag generated with every ton of steel production. Due to limited internal use of steel slag, huge amount of steel slag is dumped in yard which create a serious pollution to whole environment. BOF Slag -Fly ash based bricks are one of the application which can be used for civil construction application.

OBJECTIVE OF THE INVENTION

The basic object of the present invention is to develop a Steel slag-Flyash based brick composition and a process of manufacturing bricks.

Another object of the present invention is to develop Steel slag-Flyash based bricks for “Waste to Wealth” initiation by utilizing waste steel slag and fly ash and preserving natural resource like soil clay.

A further object of the present invention is to develop a steel slag-fly ash based brick without cement ingredient in composition and bricks made thereof wherein the bricks have higher compressive and low water absorption and high deformation temperature of the bricks.

A still further object of the present invention is directed to developing a Steel slag-Flyash based brick composition and bricks made thereof wherein no heating required for getting strength.

A still further object of the present invention is directed to developing a Steel slag-Flyash based brick composition and bricks made thereof wherein high strength to weight ratio can be achieved.

A still further objective of the invention relates to a composition and method for preparation of a steel slag-flyash based brick that is suitable for utilization in civil construction by conserving the nature.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is directed to provide Steel slag based brick free of cement having composition comprising :

Fly-Ash : 35%to 40% by wt;
BOF Slag (-5 mm) : 30% to 35%by wt;
Fly-ash +BOF Slag : 70% max by wt;
Hydrated Lime : 9%-11%by wt;
Gypsum : 1.5-3% by wt;
Calcium Chloride : less than 1% by wt;
Sand : 20-25% min % by wt;

A further aspect of the present invention is directed to said Steel slag based brick wherein said Fly Ash and BOF Slag comprise of -5 mm Fly Ash and -5 mm BOF slag having cold Compressive strength in the range of 80kg/cm2to 130kg/cm2preferably : 80 kg/cm2 min; and Water absorption in the range of 4%to 8%preferably about 8.0% max

A still further aspect of the present invention is directed to said steel slag based brick having
- Deformation Temperature : in the range of 1175oC to 1250oC preferably greater than 1200oC;
- Hemisphere Temperature: in the range 1200oC to 1275oCpreferably greater than 1200oC
- Flow Temperature: in the range of 1200oC to 1285oCpreferably greater than 1200oC.

A further aspect of the present invention is directed to a process for the manufacture of steel slag based brick as described above comprising:

(i) selectively providing fly ash of size 0.5 mm to 5 mm alongwith BOF slag of size 1mm to 5 mm
(ii) subjecting the said fly ash and BOF slag to mixing for a period of 30to 45minutes ;
(iii) sprinkling binder preferably Calcium Chloride ; and
(iv) finally subjecting to curing such as to attain compressive strength in the range of 28 days to 35 days free of any heating.

A still further aspect of the present invention is directed to said process comprising the steps of:
- Mixing of raw material in mixer drum in the sequence of Steel slag-Fly Ash- hydrated lime-Sand-Gypsum
- Sprinkling of Calcium chloride solution as binder in mixer provide the bricks of desired green strength
- Making brick in mold with hydraulic pressure of 175-200 kg/cm2.
- Drying for 28 days comprising 3 days in shadow, and rest 25 days in open air/sun
- Curing for 28 days with water from 4th day to 28days in the interval of 1-2 days to obtain Brick ready for use.

The above and other aspects and advantages of the present invention are described hereunder in greater details with reference to following accompanying non limiting illustrative drawings and example.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig-1: Process flow chart for making Steel slag-Fly ash based bricks.
Fig-2: Manufacturing stages of Steel slag-Fly ash based bricks.
Fig-3: Cold compression test of Steel slag-Fly ash based Bricks.
Fig-4: Fusion temperature of Steel slag-Fly ash based brick
Fig-5: Exemplary illustration of Steel slag-Fly ash based bricks for construction of boundary wall.
Fig- 6:shows the phase diagram of steel slag as used in brick composition of present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS

The present invention relates to development of steel slag-fly ash based brick with more than 30% steel slag component in the brick.
The composition and mineralogical constituent of raw material are given below:

(a) Composition of a BOF slag is following:

CaO SiO2 MgO Al2O3 P2O5 TiO2 FeO S Na2O K2O
42-58 10-17 6-14 0.8-1.5 0.8-1.2 0.5-1.0 18-25 0.04-0.08 0.01-0.05 0.01-0.15

(b) The phase diagram of steel slag is as shown in fig-6.

(c) Mineralogical constituent of BOF Slag
Calcium Phosphate Ca3(PO4)2
Calcium sulfate CaSO4
Magnesia MgO
Monocalcium aluminate CaO-Al2O3
Tri-calcium aluminate (CaO)3-Al2O3
Ternary systems (CaO)3-MgO-2Al2O3
Calcium Silicate (CaO)2SiO2
Calcium ferrite (CaO)2Fe2O3
Calcium Sulfide CaS

(d) Composition of a Fly ash is following:
CaO SiO2 MgO Al2O3 TiO2 Fe2O3 Na2O
1-10 31-66 0.8-5.5 18-28 0.5-2.5 3-21 0.1-3.5

(e) Composition of other raw material:
Fully Hydrated Calcined Lime:
CaO: 87-88% SiO2: 2.0-2.5% MgO: ~ 1.5%
Gypsum: CaSO4 : 70-75%
Anhydrous Calcium Chloride: Purity > 90%
River Sand: mostly SiO2

The present invention relates to development of steel slag-fly ash-Lime based brick without using cement wherein:
(a) The sequence of addition and mixing of raw material in mixing drum is as follows:
- Steel slag-Fly Ash- hydrated lime-Sand-Gypsum;
- Sprinkling of Calcium chloride solution as binder in mixer provide the bricks of desired green strength.

(b) The process for brick making is carried out by pressing in mold with hydraulic pressure of 175-200 kg/cm2 having brick size of 230 mm x 110 mm x 75 mm;
(i) The process include step of drying of green brick for 28 days comprising 3 days in shadow, and rest 25 days in open air/sun;
(ii) The process include step of curing for 28 days with water from 4th day to 28days in the interval of 1-2 days;
(iii) The present invention relates to development of steel slag-fly ash-Lime based brick with compressive strength greater than 80 kg/cm2 and water absorption less than 8.0%.
(iv) The processing of the steel slag-fly ash-Lime based brick with three different compositions were experimented to achieve the desired strength. The composition of trial samples are given in following table 1 and the respective properties achieved of each brick samples obtained thereof are given in Table 2 below.

Table-1: Composition of bricks
Material Type-1 Type-2 Type-3
Fly-Ash 36.00% 36.00%
BOF Slag (-5 mm) 31.00% 31.00% 50.00%
Hydrated Lime 5.75% 9.75% 7.75%
Cement 4.00% --- 15.00%
Gypsum 2.00% 2.00%
Calcium Chloride 0.25% 0.25% 0.25%
Sand 21.00% 21.00% 27.00%

Table-2: Mechanical & physical properties of bricks
Parameters Type-1 Type-2 Type-3
7 days 14 days 28 days 7 days 14 days 28 days 7 days 14 days 28 days
Compressive strength, kg/cm2 32-44 52-60 88-98 36-40 69-80 96-128 100-128 100-110 96-145
%Water absorption 9.0 9.6 10.5 7.3 4.9 5.4 5.6 4.2 3.1
Weight/ brick(kg) - - 3.25 - - 3.25 - - 3.80
Compressive strength per kg - - 27-30 - - 29-40 - - 25-38

Table-3: Fusion Temperature of bricks
Type-1 Type-2 Type-3
Deformation Temperature, 1200oC 1226oC 1256oC
Sphere Temperature, oC 1290oC 1251oC 1266oC
Hemisphere Temperature, oC 1330oC 1262oC 1270oC
Flow Temperature, oC 1365oC 1285oC 1275oC

ADVANTAGES OF THE INVENTION

(a) Utilization of waste steel slag which is dumped in open atmosphere and creating hazard for environment
(b) High compressive strength per weight of brick.

INDUSTRIAL APPLICABILITY

More than 15000 nos. of brick with steel slag-Fly ash–lime based bricks are produced and successfully utilized for civil construction like wall/ boundary making.

, Claims:WE CLAIM:

1. Steel slag based brick free of cement having composition comprising:

Fly-Ash : 35% to 40 % by wt;
BOF Slag (-5 mm) : 30% to 35% by wt;
Fly-ash +BOF Slag : 70% max by wt;
Hydrated Lime : 9%-11% by wt;
Gypsum : 1.5-3% by wt;
Calcium Chloride : less than 1% by wt;
Sand : 20-25% min % by wt;

2. The Steel slag based brick as claimed in claim 1 wherein said Fly Ash and BOF Slag comprise of -5 mm Fly Ash and -5 mm BOF slag having cold Compressive strength in the range of 80 to 130 preferably: 80 kg/cm2 min; and Water absorption in the range of 4% to 8% preferably about 8.0% max

3. The Steel slag based brick as claimed in anyone of claims 1 or 2 wherein said bricks have
Compressive strength to weight ratio in the range of 29/cm2 to 40/cm2.

4. The steel slag based brick as claimed in anyone of claims 1 to 3 having
- Deformation Temperature : in the range of 1175oC to 1250oC preferably greater than 1200oC;
- Hemisphere Temperature: in the range 1200oC to 1275oC preferably greater than 1200oC
- Flow Temperature: in the range of 1200oC to 1285oC preferably greater than 1200oC.

5. A process for the manufacture of steel slag based brick as claimed in anyone of claims 1 to 4 comprising:

(i) selectively providing fly ash of size 0.5 mm to 5 mm along with BOF slag of size 1mm to 5 mm
(ii) subjecting the said fly ash and BOF slag to mixing for a period of 30 to 45 minutes ;
(iii) sprinkling binder preferably Calcium Chloride ; and
(iv) Finally subjecting to curing such as to attain compressive strength in the range of 28 days to 35 days free of any heating.

6. The process as claimed in claim 5 comprising the steps of:
- Mixing of raw material in mixer drum in the sequence of Steel slag-Fly Ash- hydrated lime-Sand-Gypsum
- Sprinkling of Calcium chloride solution as binder in mixer provide the bricks of desired green strength
- Making brick in mold with hydraulic pressure of 175-200 kg/cm2.
- Drying for 28 days comprising 3 days in shadow, and rest 25 days in open air/sun
- Curing for 28 days with water from 4th day to 28 days in the interval of 1-2 days to obtain Brick ready for use.

Dated this the 20th day of March, 2023
Anjan Sen
Of Anjan Sen & Associates
(Applicants’ Agent)
IN/PA-199