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The invention relates to an improved and beneficial process of testing of enrichment of ores and minerals especially.
INTRODUCTION
A fluidized bed is a device where a solid is made to behave like a fluid when air is made to flow through a bed of granular solids. With the gradual increase in velocity, the bed gradually transforms from a packed bed to bubbling bed, then to turbulent bed and finally to fast-fluidized bed. Further increase in gas velocity results in pneumatic conveying. As the velocity rises, entrainment and elutriation rate increases. Therefore, there is a provision for recirculating the solids into the riser. Circulating fluidized bed, is comprising riser, cyclone, down comer, slow bed and transfer line with a valve to control independently solid circulation rate.
SEGREGATION AND MIXING IN CIRCULATING FLUIDIZED BED
The unique feature and advantage of CFB reactors have resulted them being used in a number of chemical and metallurgical processes. It is apparent that the main CFB applications have in common, are operated with solids that are not identical.
When dissimilar solids that is solids exhibiting a wide size distribution and different densities, are in a CFB, segregation of solids always occurs. Usually, the solid particles that are easier to fluidize tend to be elutriated by the fluidization gas and the others sink and remain at lower levels. Gas turbulence as well as interactions between individual particles and particularly the interaction of the upward flowing gas-solids suspension with downward moving strands or clusters lead to mixing of the particles. As a result, a dynamic equilibrium is obtained between mixing and segregation tendencies.

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Segregation phenomena are important in separation of impurities from pure substances and enrichment of ores and minerals such as iron ores and coal especially with fine sizes of the substances.
In this work, the mixing and segregation pattern in circulating fluidized bed consisting of fine particles and coarse particles having different density, size distributions and terminal settling velocity were investigated using a riser of CFB having dimension 0.1016 m ID inside diameter and 5.62 m height. Attention has been focused on understanding the interaction and mechanism between the particles and the conditions in which complete mixing or segregation is possible in CFB. The scope is limited to exploratory work for beneficiating fine iron ore. Beneficiation means enrichment in quality. The main impurities in Indian iron ore are alumina and silica. Beneficiation process reduces the % of these impurities. Therefore, the Fe, % in the ore increases. This enrichment process of ore is known as beneficiation.
The objective of the present invention was to study the feasibility of beneficiation in CFB (Circulated Fluidized Bed) column. Feed particles are mixture of impurities and pure ore. Also product (Concentrate) of this process is mixture of impurities and pure ore. However, the % of impurities present in feed sample was more than that in concentrate.
Basically, the objective was to develop a beneficiation (enrichment of the ore quality) process. In general most of the beneficiation processes are wet process. However, dry beneficiation has many advantages over wet processes and has high demands in mineral processing industry. Therefore, a dry beneficiation process was conceptualized.

4 DRY BENEFICIATION THROUGH CFB
3.1 EXPERIMENTAL SET UP
The experimental set up is schematically shown in Figure.1, The set up consists of a blower (A), airlines provided with orifice meters (D), a fast bed column (G), a cyclone separator (J), with a bag filter (K), a down comer along with a butterfly valve (I), a slow bed column (H), and a solids control valve (L) fitted in solids transfer line. For visual observation, the set up is made up of Perspex. For the pressure drop measurements, 22 pressure taps are installed along the CFB loop that is connected to manometers. Along the whole riser seven sampling probes are installed at different locations. They are located at h = 0.67m, 1.20m, 1.57m, 3.53m, 4.77m and 5.09m above the distributor plate. The equipment characteristics are presented in Table 1.
A: BLOWER
B: GLOBE VALVE
C: FLOW CONTROL VALVES
D: ORIFICE METERS E F: DISTRIBUTOR G: FAST BED COLUMN H: SLOW BED COLUMN I: BUTTERFLY VALVE J: CYCLONE SEPARATOR K: BAG FILTER

5 Table 1: Equipment characteristics

Riser Column
Slow Bed Column
Solid Transfer Line
Cyclone
Re-circulating column
Diameter, m =0.1016
Diameter, m =0.2032
Diameter, m =0.258
Diameter, m =0.258
Diameter, m =0.1016
Height, m = 5.62
Height, m
- 1.00
Height, im = 0.42
Height, m = 0.99
Height, m =2.225
3.2 Experimental Procedure
The experiments have been carried out in three different steps, namely sample preparation, sample collection and sample analysis sample analysis is meant chemical analysis of sample. Samples collected through the seven probes are enriched iron ore sample. The extent of enrichment depends on the height of sample collection point. Collected samples were sent for analysis of Fe, AI2O3, and SiO2 content of the samples. Solid particles are fed into the fast bed column or riser through a feed hopper. Feed hopper is not shown in Figure. 1. Feed hopper is a conical arrangement to feed the material in the fast bed column (near the distributor plate). Some Cap type of arrangement is kept there. While feeding the material one need to open the cap, insert the cylindrical bottom portion of the feed hopper to the column, put the required quantity of material, take out the feed offer and close the cap. Solid particles meant the feed material, which are required to beneficiate or enrich in quality. It is impurities + pure ore. Initially, static beds of solids are maintained in both fast and slow bed columns.

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Then, by controlling the valve in the airlines, air is sent into the riser or fast bed column (G) to fluidize the solid particles. The flow rate of an air in the slow bed is kept tow enough so as to maintain the bed just above the minimum fluidization condition, The solid particles or feed materials entrained from the riser get separated from the carrying gas into the cyclone. Fine and light particles get enrichment from the riser top (G in Figure. 1). To recover and recirculate those, one cyclone separator is fitted at the top of column H (Figure. 1). Cyclone is basically a classifying device. In this particular case, the purpose of cyclone is gas-solid separation. Solid particles get separated in cyclone from carrying gas and fall back into the slow bed through the down comer and recycled to the riser through the solid transfer line. Entrained solid fines along with high speed air entered to the cyclone through the tangential inlet of the cyclone. Cyclone has two products: overflow (lighter and fine product) and underflow (heavier and coarser product). In this case, overflow consist of mainly air with some % of very fine and light particles, where as underflow consists of mainly solid particles. The purpose of the cyclone is only to separate the solid from the air.
Cyclone overflow is again filtered in bag filter. Purpose of bag filter is 2nd stage fine solid-gas separation. Dag filter catches the very fine particles reported In cyclone overflow and air goes to atmosphere passing through the bag filter.
Bag filter is a dust collector device to filter solid-gas/air mixture. In this case, air passes through the filter cloth, and fine solid particles remains in the cloth as residue, and finally fall back to the slow bed column. The mixing process is then monitored by continuous sampling at various locations above the distributor plate at one radial position of r/R=0 that is on the axis of the riser with the tip of the probe pointed downward to sample only

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the upward flowing solids. The sample is collected in the sample collector with the help of the suction pump. Sampling probes were used to collect samples from different height of the riser. There are seven sampling probes at different height of the riser. Distances of those probes from distributor are respectively 0.67 m, 1.57 m, 3.53 m, 4.3 m, 4.77 m, and 5.09 m. A rotameter is used in the system so that the sampling can be done non-isokinetically. After the air steady state is attained, the samples at different axial locations of the riser are collected. The static pressures at different sections of the CFB also noted from the manometer readings.
The airflow rate to both the riser and slow bed, are measured from the manometer readings. By controlling the valves in the airlines, the gas velocity in the riser can be changed. Solids circulation rate can be controlled with the help of the valve in the transfer line, which can be opened partially or fully. Solids circulation rate is measured with the help of butterfly valve. This can be achieved momentarily by closing the valve and noting the solids accumulated on the valve plate against time.
Sample is prepared for feeding solid particle into the fast bed column or riser by crushing original ore sample, in the present case original iron ore sample to 1 mm and the screening at 1 mm. Screen underflow i.e. - 1 mm fraction is mixed thoroughly to homogenize it and then taken by coning-quartering method for conducting experiments.
RESULTS AND DISCUSSIONS:
Raw data for iron ore beneficiation are shown in Table 2. Since the set up was entirely made up of Perspex tube the nature of fluidization can be clearly seen visually. It is observed that while a dense zone prevails at the bottom of the riser with low voltage but

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content in a single riser was achieved. Further enrichment seems to be possible by increasing the gas velocity or multistage operation of the process.
Industrial CFB system is expected to be much larger diameter and higher riser length. While larger diameter wilt increase the throughout, the increased riser length is expected to have further improvement in iron ore beneficiation. Moreover, multiple risers in series will improve the beneficiation efficiency.
Table 2: Analysis of iron ore samples withdrawn at different locations of the riser

Ug=4.02m/s Gs=40.5 kg/m2s Gs=3LSkg/m2s Gs=25.5 kg/m2s
Probe distance from Distributor, m
Case-1
Case -2
Case -3

Fe,%
Fe,%
Fe,%
0.67
61.90
63.19
63.84
1.2
58.79
57.38
S9.26
1.57
51.19
49.07
57.17
SJ9
48.90
46.97
54.81
Ug=4.02m/s Gs=52.5 kg/m2s Gs=28.5 kg/m2s Gs=25.5kg/m2s
Probe distance front Distributor, m
Case-1
Case -2
Case -3

Fe,%
0.67
64.87
63.02
63.04
1.2
64.07
59.29
55.21
1.57
53,09
53.5
55.53

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3.53
52.46
53.00
51.77
4.3

57. 43

56.91
4.77
56.45
57.19
53.37
5.09
53.8
54.27
55.43
HOW TATA STEEL WILL BE BENEFITED?
Dry beneficiation through CFB is a new concept all together. Results shows segregation of solid content up to significant extent. This concept and information generated through this study can be used for present and future reference. If this work is not protected by the law of patent then the outside agencies may use this for their advantage and efforts made to generate this information will be lost.

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We Claim
1, An improved and beneficial Process of testing of enrichment of ores and minerals
especially with fine size of substances using Circulating fluidized bed (CFD), having
a blower (A), a fast bed column (riser) (G), a cyclone separator (J), a down comer
along with a butterfly valve (I), a slow bed column (H) and a solid control valve
(L) fitted in solid transfer fine, consisting of the first step of preparation of the
sample of the ores to be tested, the second step is the collection of the sample in
the sample collector with the help of the suction pump and finally the samples are
analyzed,
2. A process as claimed in claim 1 wherein the sample is prepared by crushing
original ore/iron ore to 1 mm size and is fed into the fast bed column and air is
blown by the blower (A) in both the columns where the flow rate of air In the slow
bed column is kept low enough so as to maintain the bed just above the minimum
fluidization condition.
3, A process as claimed in claim 2, wherein, initially static beds of solid particles are
maintained in both the columns and thereafter controlled air is sent to both the
column by controlling the valves of the air lines, so that air rate sent into the fast bed column is sufficient to fluidize the solid particles.
4. A process as claimed in claim 3, wherein the solid particles entrained from the fast
bed column (riser) get separated from the carrying air into the cyclone and fall
back into the slow bed through the down comer and recycled to the riser through the solid transfer fine.

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5. A process as claimed in claim 4, wherein the samples are collected in the sample
collector with the help of suction pump at different locations of the riser, when the
air steady state is attained.
6. A process as claimed in claim 5, wherein the pressures and the air flow rate to
both the riser and slow bed are measured form the manometer reading.
7. A process as claimed in claim 4 wherein the gas velocity in the riser can be
changed by controlling the valves in the air lines and solid particles circulation
orate can be controlled and measured with the help of the butterfly valve in the
transfer line which can be opened partially or fully.
8. The device used to carry out the process as claimed in the claims 1 to 7.
9. An improved and beneficial process of testing of enrichment of ores and minerals
especially with fine sizes of substances as substantially described in the body of
the specification and illustrated in the accompanying drawings.