Title of Invention	"A PROCESS FOR PRODUCING DENSE HIGH ALUMINA CONTENT GRAINS FROM LOW-GRADE BAUXITE ORES AND FINE GRAIN BAYER'S ALUMINA"
Abstract	The invention provides a process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, comprising the following steps in sequence :- l) crushing the low grade Bauxite ores in primary and secondary crushers into particles of size (-60)B.S. mesh; ii) passing the crushed Bauxite ores through a magnetic separator to remove magnetic particles; iii) pulverising the particles and leaching the pulverised particles with (N/5) HC1 acid for 2 hours at 80°C to remove CaO as CaCl2 solution; iv) passing the particles again through a wet high intensity magnetic separator (WHIMS) to remove magnetic materials; bauxite v) mixing the/particles with calcined fine grain Bayer's alumina in 40:60 ratio by weight; vi) wet milling the mix in a ball mill; vii) passing the mix through a blunger and filter press and drying the same in a dryer; viii) dividing the mix into two parts, one part being sintered in a kiln at 1500°C, crushed in a crusher/grinder, passed through a magnetic separator and transferred to storage, and the other part being crushed in a crusher/grinder, mixed thoroughly in a mixer, pressed into cylinder forms of diameter 50 mm in a hydraulic press at a pressure of 500 Kg/cm , sintered in kiln, at 1500°C, crushed in a crusher/grinder, passed through a magnetic separator and transferred to storages. The dense high alumina content grains produced are of physical characteristics '• colour - dark grey, density - 3.33 gm/cc, porosity - 2.86% and water absorption - 0.85%; and of chemical composition (by weight %) : A1203 - 88.33, Ti02 - 1.11, Fe2O3, - 2.56, Si02 - 5.55, CaO - 1.17, MgO - 0.44, Na20 - 0.44, K2O - 0.11 and Others - 0.29.

Title of Invention

"A PROCESS FOR PRODUCING DENSE HIGH ALUMINA CONTENT GRAINS FROM LOW-GRADE BAUXITE ORES AND FINE GRAIN BAYER'S ALUMINA"

Abstract

The invention provides a process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, comprising the following steps in sequence :- l) crushing the low grade Bauxite ores in primary and secondary crushers into particles of size (-60)B.S. mesh; ii) passing the crushed Bauxite ores through a magnetic separator to remove magnetic particles; iii) pulverising the particles and leaching the pulverised particles with (N/5) HC1 acid for 2 hours at 80°C to remove CaO as CaCl2 solution; iv) passing the particles again through a wet high intensity magnetic separator (WHIMS) to remove magnetic materials; bauxite v) mixing the/particles with calcined fine grain Bayer's alumina in 40:60 ratio by weight; vi) wet milling the mix in a ball mill; vii) passing the mix through a blunger and filter press and drying the same in a dryer; viii) dividing the mix into two parts, one part being sintered in a kiln at 1500°C, crushed in a crusher/grinder, passed through a magnetic separator and transferred to storage, and the other part being crushed in a crusher/grinder, mixed thoroughly in a mixer, pressed into cylinder forms of diameter 50 mm in a hydraulic press at a pressure of 500 Kg/cm , sintered in kiln, at 1500°C, crushed in a crusher/grinder, passed through a magnetic separator and transferred to storages. The dense high alumina content grains produced are of physical characteristics '• colour - dark grey, density - 3.33 gm/cc, porosity - 2.86% and water absorption - 0.85%; and of chemical composition (by weight %) : A1203 - 88.33, Ti02 - 1.11, Fe2O3, - 2.56, Si02 - 5.55, CaO - 1.17, MgO - 0.44, Na20 - 0.44, K2O - 0.11 and Others - 0.29.

Full Text	The present invention relates to a process for producing dense high alumina content grains from low-grade baxite ores and fine grain Bayer's alumina. The invention relates more particularly to a process for producing alumina grains of density 3.0 gm/cc or more and alumina (Al2O3) content more than 60% by weight required for making different ' shaped and unshaped' refractories such as high alumina bricks, alumina-chrome bricks, alumina-carbon bricks which are capable of withstanding the aggressive thermo-dynamic environment of the modern steel manufacturing plants, the demand for which has been rising rapidly at present, using low grade Bauxite ores and fine-grain Bayer's alumina as the raw materials. The high alumina content refractories are produced at present from naturally occurring ores like Sillimanite, Kyanite, Diaspore and high grade Bauxite ores containing low proportion of fluxing materials like CaO, Fe2O3, and TiO2. But the supply of these ores has been dwindling rapidly at present with escalation of their cost. For example, although Bauxite ores are available abundantly in India, hardly 10% or so of the available Bauxite ores are of high grade and can be used for producing high alumina content refractories. The balance being of low grade i.e. containing a high percentage of the fluxing materials are mostly used for producing aluminium and cement. A method for producing fused alumina from low grade Bauxite ores of relatively high flux content is known. But the cost of production in this method is prohibitively high. A synthetic method of producing dense high-alumina grains is also available, but the method being highly capital- and also energy-intensive, is not found to be commercially viable. The objective of the present invention is to provide a relatively low cost and simple method of producing dense high-alumina content grains from low grade Bauxite ores which are available in abundance in India, and fine grain Bayer's alumina as the raw materials. Extensive investigations have been carried out in developing the Invented process for optimising the conditions suitable for removing the fluxing materials like CaO and Fe2O3, present in high proportion in low grade Bauxite ores. For this purpose, the low grade Bauxite ores have been crushed and ground into particles of different sizes and leached with HC1 acid of different strengths for different durations at different temperatures, and passed through magnetic field of different intensities. The Bauxite particles with minimised content of CaO and Fe2O3 fluxing materials produced under the optimised conditions are mixed with the required proportion of calcined fine grain Bayer's alumina, co-ground, sintered, crushed, ground and screened into different fractions, passed through magnetic field to remove free iron content and stored for producing high alumina content refractories required for use in steel plants. Thus the present Invention provides a process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, comprising the following steps in sequence :- i) crushing the low grade Bauxite ores in primary and secondary crushers; ii) passing the crushed Bauxite ores through magnetic separator to remove magnetic particles; iil) pulverising the particles and leaching the pulverised particles with HCI. acid to remove CaO as CaCl2 solution; iv) passing the particles again through wat high intensity magnetic separator (WHIMS) to remove magnetic materials; v) mixing the particles with calcined fine grain Bayer's alumina in the proportion thereof, such as herein described; vi) wet milling the mix in ball mill; Vii) passing the mixture through blunger and filter press and drying the same in dryer at temperature, such as herein described; viil) dividing the mixture into two parts, one part being sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage, and the other part being crushed in crusher/grinder, mixed thoroughly in mixer, pressed into cylinder forms in hydraulic press, sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage; characterised in that (a) the Bauxite ores are crushed into particles of size (-60) B.S. mesh; (b) crushed Bauxite particles are leached with N/5 HC1 acid for 2 hours at 80°C; (c) leached Bauxite particles and sintered fine grain Bayer's alumina are mixed in 40:60 ratio by weight; and (d) mixture of leached Bauxite particles and fine grain Bayer's alumina is co-ground, passed through filter press, dried and sintered in kiln at 1500°C. The invention is described fully and particularly in an unrestricted manner by way of an example only with reference to the accompanying drawings in which - Figure 1 is a flow chart showing the various steps followed in sequence; Figure 2 shows the effect of particle size of the crushed Bauxite ore on the removal of CaO by leaching the same with HGL of strengths N/10 and N/20 for four hours; Figure 3 shows the effect of the concentration of HC1 on removal of CaO and Fe2O3 from ore particles of size (-60) B. S. mesh, at temperature 80°C for four hours; Figure 4 shows the effect of duration of leaching with N/10 HCL on removal of CaO from the ore particles of sizes (-60) B. S. mesh and (-100) B.S. mesh at room temperature; Figure 5 shows the effect of the duration of leaching with N/5 HCL on removal of CaO and Fe2O3 from the ore particles of size (-60) B.S. mesh; and Figure 6 shows the effect of the duration and size of ore particles on the removal of CaO at room temperature; Referring to Fig. 1 the process according to the invention comprises the following steps in sequence : 1) collection of raw raw Bauxite ore of low grade i.e. containing a relatively high proportion of fluxing materials like CaO and Fe2O3,; 2) crushing in primary crusher; 3) crushing in secondary crusher; 4) passing through magnetic separator; 5) pulverising in pulveriser; 6) leaching in leaching tank with HC1 from HC1 source (5A) and removing CaCl2 solution formed to tank (5B); 7) passing the leached ore particles through Wet High Intensity magnetic separator (WHIMS); 8) mixing with calcined fine grain Bayerfs alumina from source (8A) and milling the mix in ball mill; 9) passing through blunger; 10) passing through filter press; 11) passing through dryer and dividing the mix into two parts (I) and (II) and treating them separately as: (I) (II) 12) sintering in kiln; 16) crushing in crusher/ grinder; 13) crushing in crusher/ grinder; 17) mixing thoroughly in mixer; 14) passing through magnetic 18) pressing in hydraulic press separator; into cylinders/briquettes; 15) screening the particles 19) sintering in kiln; through 5mm screen and transferring to storage; 20) crushing in crusher/grinder; 21) passing through magnetic separator. Referring to Figs. 2 to 6, the optimum conditions for removal of CaO and Fe20, from the low grade Bauxite ores are found to be as follows :- (a) particle size - (-60) B.S. mesh (b) strength of HC1 for leaching - N/5 (c) leaching temperature - around 80°C. (d) leaching time - around 2 hours. The optimum sintering temperature in kiln has been found to be 1500°C. The leached particles of low grade Bauxite ores are mixed with calcined fine grade Bayer's alumina in 40:60 ratio by weight. The mix of part (II) is pressed into cylinders of 2 diameter 50 mm in a hydraulic press at a pressure of 500 kg/cm . The physical characteristics and chemical composition of the dense high-alumina grains produced in the invented process, as presented in Table I, have been found to be suitable for producing superior quality high-alumina refractories for applications in steel plants with satisfactory service life at a reduced cost. TABIE - I Physical characteristics and chemical composition of dense nigh alumina content grains produced in the invented process. (Table 1 Removed) We Claim :- 1. A process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, comprising the following steps in sequence :- i) crushing the low grade Bauxite ores in primary and secondary crushers; ii) passing the crushed Bauxite ores through magnetic separator to remove magnetic particles; iii) pulverising the particles and leaching the pulverised particles with HC1 acid to remove CaO as CaCl2 solution; iv) passing the particles again through wet high intensity magnetic separator (WHIMS) to remove magnetic materials; v) mixing the particles with calcined fine grain Bayer's alumina in the proportion thereof, such as herein described; vi) wet milling the mix in ball mill; vii) passing the mixture through blunger and filter press and drying the same in dryer at temperature, such as herein described; viii) dividing the mixture into two parts, one part being sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage, and the other part being crushed in crusher/grinder, mixed thoroughly in mixer, pressed into cylinder forms in hydraulic press, sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage; characterised in that (a) tha Bauxite ores are crushed into particles of size (-60) B.S. mesh; (b) crushed Bauxite particles are leached with N/5 HC1 acid for 2 hours at 80° C; (c) leached Bauxite particles and sintered fine grain Bayer's alumina are mixed in 40:60 ratio by weight; and (d) mixture of leached Bauxite particles and fine grains Bayer's alumina is co-ground, passed through filter press, dried and sintered in kiln at 1500°C. 2. The process as claimed in Claim 1 or 2, wherein the mixture is pressed into cylinders of diameter 50 mm in a hydraulic press at pressure of 500 kg/cm2 . 3. A process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, substantially as herein described and illustrated in the accompanying drawings.

Full Text

The present invention relates to a process for producing dense high alumina content grains from low-grade baxite ores and fine grain Bayer's alumina.
The invention relates more particularly to a process for producing alumina grains of density 3.0 gm/cc or more and alumina (Al2O3) content more than 60% by weight required for making different ' shaped and unshaped' refractories such as high alumina bricks, alumina-chrome bricks, alumina-carbon bricks which are capable of withstanding the aggressive thermo-dynamic environment of the modern steel manufacturing plants, the demand for which has been rising rapidly at present, using low grade Bauxite ores and fine-grain Bayer's alumina as the raw materials.
The high alumina content refractories are produced at present from naturally occurring ores like Sillimanite, Kyanite, Diaspore and high grade Bauxite ores containing low proportion of fluxing materials like CaO, Fe2O3, and TiO2. But the supply of these ores has been dwindling rapidly at present with escalation of their cost. For example, although Bauxite ores are available abundantly in India, hardly 10% or so of the available Bauxite ores are of high grade and can be used for producing high alumina content refractories. The balance being of low grade i.e. containing a high percentage of the fluxing materials are mostly used for producing aluminium and cement.
A method for producing fused alumina from low grade Bauxite ores of relatively high flux content is known. But the cost of production in this method is prohibitively high. A

synthetic method of producing dense high-alumina grains is also available, but the method being highly capital- and also energy-intensive, is not found to be commercially viable.
The objective of the present invention is to provide a relatively low cost and simple method of producing dense high-alumina content grains from low grade Bauxite ores which are available in abundance in India, and fine grain Bayer's alumina as the raw materials.
Extensive investigations have been carried out in developing the Invented process for optimising the conditions suitable for removing the fluxing materials like CaO and Fe2O3, present in high proportion in low grade Bauxite ores. For this purpose, the low grade Bauxite ores have been crushed and ground into particles of different sizes and leached with HC1 acid of different strengths for different durations at different temperatures, and passed through magnetic field of different intensities. The Bauxite particles with minimised content of CaO and Fe2O3 fluxing materials produced under the optimised conditions are mixed with the required proportion of calcined fine grain Bayer's alumina, co-ground, sintered, crushed, ground and screened into different fractions, passed through magnetic field to remove free iron content and stored for producing high alumina content refractories required for use in steel plants.
Thus the present Invention provides a process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, comprising the following steps in sequence :-
i) crushing the low grade Bauxite ores in primary and
secondary crushers; ii) passing the crushed Bauxite ores through magnetic
separator to remove magnetic particles;
iil) pulverising the particles and leaching the pulverised particles with HCI. acid to remove CaO as CaCl2 solution; iv) passing the particles again through wat high intensity
magnetic separator (WHIMS) to remove magnetic materials; v) mixing the particles with calcined fine grain Bayer's alumina in the proportion thereof, such as herein described;
vi) wet milling the mix in ball mill;
Vii) passing the mixture through blunger and filter press and drying the same in dryer at temperature, such as herein described;
viil) dividing the mixture into two parts, one part being sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage, and the other part being crushed in crusher/grinder, mixed thoroughly in mixer, pressed into cylinder forms in hydraulic press, sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage;
characterised in that
(a) the Bauxite ores are crushed into particles of size (-60) B.S. mesh;
(b) crushed Bauxite particles are leached with N/5 HC1
acid for 2 hours at 80°C;
(c) leached Bauxite particles and sintered fine grain
Bayer's alumina are mixed in 40:60 ratio by weight; and
(d) mixture of leached Bauxite particles and fine grain
Bayer's alumina is co-ground, passed through filter
press, dried and sintered in kiln at 1500°C.
The invention is described fully and particularly in an unrestricted manner by way of an example only with reference to the accompanying drawings in which -
Figure 1 is a flow chart showing the various steps followed in sequence;
Figure 2 shows the effect of particle size of the crushed Bauxite ore on the removal of CaO by leaching the same with HGL of strengths N/10 and N/20 for four hours;
Figure 3 shows the effect of the concentration of HC1 on removal of CaO and Fe2O3 from ore particles of size (-60) B. S. mesh, at temperature 80°C for four hours;
Figure 4 shows the effect of duration of leaching with N/10 HCL on removal of CaO from the ore particles of sizes (-60) B. S. mesh and (-100) B.S. mesh at room temperature;
Figure 5 shows the effect of the duration of leaching with N/5 HCL on removal of CaO and Fe2O3 from the ore particles of size (-60) B.S. mesh; and
Figure 6 shows the effect of the duration and size of ore particles on the removal of CaO at room temperature;
Referring to Fig. 1 the process according to the invention comprises the following steps in sequence :
1) collection of raw raw Bauxite ore of low grade i.e.
containing a relatively high proportion of fluxing
materials like CaO and Fe2O3,;
2) crushing in primary crusher;
3) crushing in secondary crusher;
4) passing through magnetic separator;
5) pulverising in pulveriser;
6) leaching in leaching tank with HC1 from HC1 source
(5A) and removing CaCl2 solution formed to tank (5B);
7) passing the leached ore particles through Wet High
Intensity magnetic separator (WHIMS);
8) mixing with calcined fine grain Bayerfs alumina from
source (8A) and milling the mix in ball mill;
9) passing through blunger;

10) passing through filter press;
11) passing through dryer and dividing the mix into two
parts (I) and (II) and treating them separately as:
(I) (II)
12) sintering in kiln; 16) crushing in crusher/
grinder;
13) crushing in crusher/
grinder; 17) mixing thoroughly in mixer;
14) passing through magnetic 18) pressing in hydraulic press
separator; into cylinders/briquettes;
15) screening the particles 19) sintering in kiln;
through 5mm screen and
transferring to storage; 20) crushing in crusher/grinder;
21) passing through magnetic separator.
Referring to Figs. 2 to 6, the optimum conditions for removal of CaO and Fe20, from the low grade Bauxite ores are found to be as follows :-
(a) particle size - (-60) B.S. mesh
(b) strength of HC1 for leaching - N/5
(c) leaching temperature - around 80°C.
(d) leaching time - around 2 hours.
The optimum sintering temperature in kiln has been found to be 1500°C.
The leached particles of low grade Bauxite ores are mixed with calcined fine grade Bayer's alumina in 40:60 ratio by weight.
The mix of part (II) is pressed into cylinders of
2 diameter 50 mm in a hydraulic press at a pressure of 500 kg/cm .
The physical characteristics and chemical composition of the dense high-alumina grains produced in the invented process, as presented in Table I, have been found to be suitable for producing superior quality high-alumina refractories for applications in steel plants with satisfactory service life at a reduced cost.

TABIE - I
Physical characteristics and chemical composition of dense nigh alumina content grains produced in the invented process.
(Table 1 Removed)

We Claim :-
1. A process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, comprising the following steps in sequence :-
i) crushing the low grade Bauxite ores in primary and
secondary crushers; ii) passing the crushed Bauxite ores through magnetic
separator to remove magnetic particles;
iii) pulverising the particles and leaching the pulverised particles with HC1 acid to remove CaO as CaCl2 solution; iv) passing the particles again through wet high intensity
magnetic separator (WHIMS) to remove magnetic materials; v) mixing the particles with calcined fine grain Bayer's alumina in the proportion thereof, such as herein described;
vi) wet milling the mix in ball mill;
vii) passing the mixture through blunger and filter press and drying the same in dryer at temperature, such as herein described;
viii) dividing the mixture into two parts, one part being sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage,
and the other part being crushed in crusher/grinder, mixed thoroughly in mixer, pressed into cylinder forms in hydraulic press, sintered in kiln, crushed in crusher/grinder, passed through magnetic separator and transferred to storage;
characterised in that
(a) tha Bauxite ores are crushed into particles of
size (-60) B.S. mesh;
(b) crushed Bauxite particles are leached with N/5 HC1
acid for 2 hours at 80° C;
(c) leached Bauxite particles and sintered fine grain
Bayer's alumina are mixed in 40:60 ratio by weight; and
(d) mixture of leached Bauxite particles and fine grains
Bayer's alumina is co-ground, passed through filter
press, dried and sintered in kiln at 1500°C.
2. The process as claimed in Claim 1 or 2, wherein the
mixture is pressed into cylinders of diameter 50 mm in a
hydraulic press at pressure of 500 kg/cm2 .
3. A process for producing dense high alumina content
grains from low grade Bauxite ores and fine grain Bayer's
alumina, substantially as herein described and illustrated in
the accompanying drawings.

Documents:

47-del-1998-abstract.pdf

47-del-1998-claims.pdf

47-del-1998-correspondence-others.pdf

47-del-1998-correspondence-po.pdf

47-del-1998-description (complete).pdf

47-del-1998-drawings.pdf

47-del-1998-form-1.pdf

47-del-1998-form-19.pdf

47-del-1998-form-2.pdf

47-del-1998-form-4.pdf

47-del-1998-gpa.pdf

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Patent Number

210326

Indian Patent Application Number

47/DEL/1998

PG Journal Number

43/2007

Publication Date

26-Oct-2007

Grant Date

27-Sep-2007

Date of Filing

09-Jan-1998

Name of Patentee

STEEL AUTHORITY OF INDIA LTD., RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL

Applicant Address

ISPAT BHAWAN, LODI ROAD, NEW DELHI-110003.INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	JAGDISH PRASAD	RESEARCH & DEVELOPMENT CENTRE IRON & STEEL, SAIL, RANCHI-834 002, INDIA.
2	MANI SHANKER MUKHOPADHYAY	RESEARCH & DEVELOPMENT CENTRE IRON & STEEL, SAIL, RANCHI-834 002, INDIA.
3	KRISHNA CHRAN CHATTERJEE	RESEARCH & DEVELOPMENT CENTRE IRON & STEEL, SAIL, RANCHI-834 002, INDIA.

PCT International Classification Number

B24D 3/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA