Title of Invention

'A PROCESS FOR THE UTILISATION OF THE FINE OILY MILLSCALE GENERATED IN THE FINISHING MILLS OF INTEGRATED STEEL PLANTS' AS HEAVY MEDIA IN COAL WASHERIES'

Abstract This invention relates to a process for the utilisation of fine oily millscale generated in the finishing mills of integrated steel plants as heavy media particularly in coal washeries comprising the following process steps: 1) screening the mill scale to a size less than 0,044mm, 2) grinding the oversize mill scale left in the screen below the size of 0.044mm, 3) mixing the mill scale thus screened in step (1) with the grinded mill scale of step (2) to get an end mix having 90-97% of the said mix being of a size less than 0.045mm, 1) the said end mix being men mixed with a dispersant such as sodium silicate of an amount of 0.7 to 0.8% by weight of the heavy media used, ensuing uniform suspension without any formation of lumps in the said media, 2) adding required amount of water for making the required specific gravity of 1,2 to 3 thus resulting the heavy media for use in coal washeries. The statement of claim (1) may also be revised accordingly as stated above.
Full Text This invention relates to a process for the utilisation of the fine oily millscale generated in the finishing mills of integrated steel plants as heavy media particularly in coal washeries. The fine oily mill scale is also known as mill sludge. Presently the fine oily millscale which is highly magnetic is now discarded as waste.
Magnetite as magnetic material is used as heavy medium in coal washeries.
In India, the reserves of magnetic material are meagre and therefore an alternate source of magnetite for use in coal washeries has assumed importance.
However the qualities, properties and the cost of secondary magnetite now vary considerably and therefore a uniform variety of secondary magnetite has become essential.
Moreover, since the coal industries in India are ever expanding, the demand for secondary magnetite has assumed huge proportions.
Therefore the main object of the present invention is to propose a process for the utilisation of fine oily millscale as heavy media in coal washeries as a substitute of secondary magnetite.
Another object of the present invention is to propose such a process which will produce substantially uniform quality of a material alternative to magnetite.
Further object of the present invention is to propose a process which is economical and can be practiced without difficulty. Cost effectiveness of the present invention is expressed as follows:-


• Cost of procuring mill scale-Nil (since it is a waste obtained from rolling/ finishing mills)
• Screening, grinding and mixing millscale, RE 5 00/t
• Sodium silicate procurement and mixing with ground millscaJe, Rs/t:500
• Total cost, Rs/t 1000
existing cost of magnetite used as heavy media in coal washeries is Rs/t.2000
According to the present invention there is provided a process for the utilisation of fine oily millscale generated in the finishing mills of integrated steel plants as heavy media, particularly in coal washeries comprising the following process steps:
1) screening the mill scale to a size less than 0.044mm,
2) grinding the oversize mill scale left in the screen below the size of 0.044mm,
3) mixing the mill scale thus screened in step (1) with the grinded mill scale of step (2) to get an end mix having 90-97% of the said mix being of a size less than 0.045mm,
4) the said end mix being men mixed with a dispersant such as sodium silicate of an amount of 0.7 to 0.8% by weight of the heavy media used, ensuing uniform suspension without any formation of lumps in the said media,
5) adding required amount of water for making the required specific gravity of 1.2 to 3 thus resulting the heavy media for use in coal washeries.
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The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to non-limiting exemplary embodiments of the invention represented in me accompanying drawings in which Figure 1 represents a flow sheet diagram of sequential steps of the process of the invention.
The nature and purpose of the invention will be best understood from the following tables in which
Table 1 shows a comparison of properties between millsludge and magnetite for use as heavy media in coal washeries.
Table 2 shows a table of results of DMC (Dense Medium Cyclone) tests with millsludge and magnetite as heavy media
TABLE 1: COMPARISON OF PROPERTIES BETWEEN MILLSLUDGE AND MAGNETITE FOR USE AS HEAVY MEDIA IN
COAL WASHERIES
PROPERTIES | MAGNETITE MILLSLUDGE
SEE ANALYSIS 80% Below 90% Below 0.045mm
0.04 5 mm
STABILITY AT
1.3 sp.gr 1.69 mitt/cm 1.72 min/cm
1.4 sp.gr 2.16 min/cm 2.47 min/cm
1.5 sp.gr 2.56 min/cm 10.64 min/cm SPECIFIC GRAVITY 4.6 4.3 RECOVERABILITY* 90% at 1000 gauss 90% at 5000 gauss
Tests were carried out in the laboratory Wet High Intensity Magnetic Separator

(WHIMS) - 4 -

TABLE 2: RESULTS OF DMC (DENSE MEDIA CYCLONE) TESTS
WITH MILLSLUDGE AND MAGNETITE AS HEAVY MEDIA
Specific gravity of suspension 13.5, Feed ash % :35



The fine oily millscale contains magnetic property and hence compares closely with magnetite which is generally mined and used as heavy media in coal washeries.
In the tables 1 and 2 the comparison of the properties between magnetite and the fine oily millscale is given.
It may be noticed from Table 1 and Table 2 mat better properties of mill sludge than that of magnetite can be maintained and better yield of clean coal is obtained by using the mill sludge as heavy medium in conventional coal washing industries and thus resulting an economical process.
The process is now discussed in details as below:
In the manufacture of blast furnace coke from coal, the coal is subjected to washing for lowering the ash content so that the high ash Indian coal can be usefully employed in coke manufacture. The ash content is to be lowered to a practical limit of 17-18% which is dictated by the quality of Indian coking coals. The general practice of coal washing is to crush the coal to below 50 mm or less, followed by separate treatment of coarse

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(+0.5mm) and fine (-0.5mm) coal fractions. While fine coal is processed by froth floatation, coarse coal cleaning is universally carried out by heavy medium separation. In commercial plants of heavy medium separation using dense medium cyclones, finely divided solids of magnetite are kept in suspension in water to create a dense medium.
Thus for the creating of the heavy medium in fee above mentioned coal washing procedure, magnetite is being employed. If fee magnetite requirements of the coal washeries can be shifted from fee mineral magnetite to other secondary sources of substantially similar qualities, not only a great saving of fee magnetite can be ensured for other more important and useful purposes, but also a secondary source can be beneficially developed.
Table-1 shows a table of comparison between fee millsludge and magnetite which indicates size is 90% below 0.045 mm compared to 80% below for magnetite, stability and recoverability is also better in case of millsludge.
Table-2 shows a table of comparison results of fee dense media cyclone which show coal yield % is better in case of millsludge used as heavy media.
The process steps as stated earlier comprises of screening and sizes bigger than 0.044 mm is ground to reduce sizes below 0.044 mm. Both fee ground and un-ground millscale is then mixed so feat at least 90% is less than 0.044 mm. A dispersant is added to ensure feat fee suspension is uniform without fee formation of lumps. A dispersant like sodium silicate is used. Generally dispersant used is 0.7 to 0.8% of the heavy media
Desired amount of water is added for making fee desire specific gravity of suspension. Table-1 shows fee specific gravity as 4.3.

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The material is then used as heavy media in coal washeries. The recoverability is 90% at 5000 gauss. Hie clean coal yield % is 16.2 to 35.95 depending on clean coal ash % of 5.74 to 13.58 as shown in Table-2.
The invention described hereinabove is in relation to non-limiting embodiments and as defined by the accompanying claims.
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WE CLAM
1. A process for the utilisation of fine oily millscale generated in Hie finishing mills
of integrated steel plants as heavy media particularly in coal washeries comprising
the following process steps:
1) screening the mill scale to a size less than 0.044mm,
2) grinding the oversize mill scale left in the screen below the size of 0.044mm,
3) mixing the mill scale thus screened in step (1) with the grinded mill scale of step (2) to get an end mix having 90-97% of the said mix being of a size less than 0.045mm,
4) the said end mix being then mixed with a dispersant such as sodium silicate of an amount of 0.7 to 0.8% by weight of the heavy media used, ensuing uniform suspension without any formation of lumps in the said media,
5) adding required amount of water for making the required specific gravity of 1.2 to 3 thus resulting the heavy media for use in coal washeries.

2. A process for the utilisation of fine oily millscale as claimed in claim 1 wherein the stability of the millsludge at 1.3 Sp.gr. is 1.72 min/cm and at 1.5 Sp.gr. is 10.64 min/cm.
3. A process for the utilisation of fine oily millscale as claimed in claim 1 wherein the recoverability is 90% at 5000 gauss.
4. A process for the utilisation of fine oily millscale as claimed in claim 1 wherein the clean coal yield percentage with millsludge as heavy media is 16.2 having clean coal ash percentage of 5.74 and 35,95 having clean coal ash percentage of 13.58.

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A process for the utilisation of the fine oily millscale generated in the finishing mills of integrated steel plants as herein described and illustrated in the accompanying drawings.
This invention relates to a process for the utilisation of fine oily millscale generated in the finishing mills of integrated steel plants as heavy media particularly in coal washeries comprising the following process steps:
1) screening the mill scale to a size less than 0,044mm,
2) grinding the oversize mill scale left in the screen below the size of 0.044mm,
3) mixing the mill scale thus screened in step (1) with the grinded mill scale of step (2) to get an end mix having 90-97% of the said mix being of a size less than 0.045mm,
1) the said end mix being men mixed with a dispersant such as sodium silicate of an amount of 0.7 to 0.8% by weight of the heavy media used, ensuing uniform suspension without any formation of lumps in the said media,
2) adding required amount of water for making the required specific gravity of 1,2 to 3 thus resulting the heavy media for use in coal washeries.
The statement of claim (1) may also be revised accordingly as stated above.



Documents:

00349-cal-2000-abstract.pdf

00349-cal-2000-claims.pdf

00349-cal-2000-correspondence.pdf

00349-cal-2000-description(complete).pdf

00349-cal-2000-drawings.pdf

00349-cal-2000-form-1.pdf

00349-cal-2000-form-18.pdf

00349-cal-2000-form-2.pdf

00349-cal-2000-form-26.pdf

00349-cal-2000-form-3.pdf

00349-cal-2000-letters patent.pdf

349-cal-2000-granted-abstract.pdf

349-cal-2000-granted-claims.pdf

349-cal-2000-granted-correspondence.pdf

349-cal-2000-granted-description (complete).pdf

349-cal-2000-granted-drawings.pdf

349-cal-2000-granted-examination report.pdf

349-cal-2000-granted-form 1.pdf

349-cal-2000-granted-form 2.pdf

349-cal-2000-granted-form 26.pdf

349-cal-2000-granted-form 3.pdf

349-cal-2000-granted-letter patent.pdf

349-cal-2000-granted-reply to examination report.pdf

349-cal-2000-granted-specification.pdf


Patent Number 203362
Indian Patent Application Number 349/CAL/2000
PG Journal Number 11/2007
Publication Date 16-Mar-2007
Grant Date 16-Mar-2007
Date of Filing 14-Jun-2000
Name of Patentee MRS. R. SRIPRIYA,MRS.SONI & MR. P.V.T. RAO
Applicant Address INDIAN NATIONALS OF JAMSHEDPUR - 831 001, THE TATA IRON AND STEEL COMPANY LIMITED, AN INDIAN COMPANY OF BOMBAY HOUSE, 24, HOMI MODY STREET, MUMBAI - 400 001
Inventors:
# Inventor's Name Inventor's Address
1 MRS. R. SRIPRIYA,MRS.SONI & MR. P.V.T. RAO INDIAN NATIONALS OF JAMSHEDPUR - 831 001, THE TATA IRON AND STEEL COMPANY LIMITED, AN INDIAN COMPANY OF BOMBAY HOUSE, 24, HOMI MODY STREET, MUMBAI - 400 001
PCT International Classification Number B21B 28/02
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA