MANINDRA MANNA (IN)
PRADIP KUMAR BANERJEE (IN)
| US5307938A | 1994-05-03 | |||
| US3292780A | 1966-12-20 | |||
| AU495911B2 | 1977-07-28 |
| We Claim: 1. A process for producing high purity Fe203 for value-added applications including blast furnace feed from a poor-grade iron ore slime, comprising the steps of: - separating through a non-selective dispersion of iron-containing ultra fines having different particle sizes ranging between 100 micron to 100 nm, into coarser and finer categories in a plurality of hydrocyclones of different sizes, wet-grinding the coarser category with a particle size of more than 15 microns under varied concentration to convert into finer category with a particle size of less than 15 microns; and allowing the produced fines in a single benefication step to undergo a selective flocculation by adapting a modified starch which generates a first concentrate containing around 68.5% Fe, 0.8% alumina, and 1% silica, and a first tailing containing around 29.8% Fe, 20.5% alumina, and 19.67% quartz; - allowing the first concentrate to undergo a further dispersion followed by a further selective flocculation to produce high grade concentrate and a second tailing, the high grade concentrate being suitable for value-added applications; and - allowing the first tailing to undergo a selective flocculation to produce a second concentrate and a second tailing, the second tailing being suitable as material for refractory and building construction, wherein the second concentrate suitable for pelletization. 2. The process as claimed in claim 1, wherein the ultra fines constitutes the mixture of Fe, Si, and AJ-Oxides, and wherein the aluminium and silica comprises 2.5 to 14 wt%. 3. The process as claimed in claim 1, wherein the dispersant comprises nonselective dispersant applied with different dosages. 4. The process as claimed in claim 1 or 3, wherein the dispersant comprises sodium silicate and sodium hexameta phosphate. 5. The process as claimed in claim 1 or 4, wherein the dosages of the dispersant is selected in the range of 20 to 15000 ppm, preferably in the range of 20 to 10000 ppm. 6. The process as claimed in claim 1, wherein the starch includes potato, wheat, maze, and wherein the starch solution comprises a plain including a caustic starch solution with varied concentration of caustic starch for example, in the concentration range of 0.1 to 10.0 wt%. 7. The process as claimed in claim 1, wherein the process is enabled to be implemented under varied pH-concentration for example, in the range of 2.5 to 11, preferably in the range of 8-10. 8. The process as claimed in claim 1, wherein the concentration of the ultrafines is in the range of 2 to 25 wt% with varied settling time for example, between 10 seconds to 20 hours. 9. The process as claimed in claim 1, wherein the ultrasonic treatment comprises a treatment time in the range of 1 to 100 minutes under variable ultrasonic power, and wherein the solvent comprises one of a double-distilled water, tap water, and industrial process water. 10. A process for producing high purity Fe203 for value-added applications including blast furnace feed from a poor-grade iron ore slime, as substantially described and illustrated herein with reference to the accompanying drawings. |
FIELD OF INVENTION
The present invention generally relates to a method of producing a concentrate containing very high purity iron oxide with very low alumina and silica from a poor grade iron ore fines. More particularly, the invention relates to a process for producing high purity Fe 2 0 3 for value added applications including blast furnace feed from a poor grade iron ore slime.
BACKGROUND OF INVENTION
Quality of the raw materials for the iron and steel industries p/ays an important role in the downstream processes. The fines generated in the iron ore mines and also in the iron ore washing plants do not satisfy the stringent specifications of raw materials to be used either for value added application or blast furnace.
Iron ore are beneficiated all over the world for which several techniques are being used namely spiral, floatex density separators, jigs, multi-gravity separator, low and high intensity magnetic separator, flotation, selective
dispersion and flocculation and many more with advanced technologies. Iron ore production entails generation of fines (10-25%) containing high alumina (6-8%), which is unsuitable for direct use in the blast furnace. Assuming an annual production of 150 tons of iron ore, the iron values to the tune of 15- 25 million tones is lost every year. The main drawback for use of iron ore ultra fines is that high level of clay are associated with it. As a consequence, this ultra fines being rejected and getting wasted including causing environmental hazards. The particle size of these ultra fines is not suitable to beneficiate it by known beneficiation processes such as (i) gravity or (ii) magnetic separation.
The known benefication processes separate minerals from the mixture of two oxides. But, iron ore ultra fines are mixtures of different oxides, which have no utility . It is mixed with goethite, silica, alumina, alumina silicate,refractory minerals.
An efficient benefication technology is thus needed which is enabled to effectively produce two valuable products from the waste which are respectively suitable for fine magnetic particles for value added application and making building material, refractory material, nano paint or nano coolant. Large quantities of ultra fines are generated during mining and washing of iron ores. If the alumina content of the slimes can be reduced to below 2%, in the beneficiated product, the following benefits can be derived immediately: (1) High mine out put.
(2) Optimum utilization of the natural resources
(3) Reduction at the environmental hazardgenerated due to storage and disposal of the unsuitable products.
(4) Higher productivity in the blast furnace and the sinter plant
(5) Inerface in production of value added products like application in medical science, paint formulation, removal of hazardous element from contaminated water and soil.
Due to ultrafineness of the particles, a process-selection from among the established techniques has become difficult. Accordingly, it requires a more dominating property than gravity or magnetic separation of such ultra fines. The selective flocculation process is known to be adapted to separate iron oxide as red mud from bauxite. It is expected that such a process could be considered to beneficiate such ultra fines. Also this process can be deployed to improve the brightness of selectively separated silica. Thus, a selective flocculation of these fines could be a viable option for efficient separation of alumina and silica from the iron bearing minerals.
OBJECTS OF INVENTION
It is therefore an object of the invention to propose a process for producing high purity Fe 2 0 3 for value added application and blast furnace feed from a poor grade iron ore slime , which eliminates the prior art disadvantages. Another object of the invention is to propose a process for producing high purity Fe 2 0 3 for value added application and blast furnace feed from a poor grade iron ore slime, which provides a first grade of product containing only very low amount of alumina and silica adaptable for high-valued product or blast furnace feed.
A further object of the invention is to propose a process for producing high purity Fe20 3 for value added application and blast furnace feed from a poor grade iron ore slime, which provides a second grade of product containing high alumina and silica suitable for making building or refractory material.
SUMMARY OF THE INVENTION
According to the invention, various grades of rejected ultra fines can be separated out into two categories, (i) a concentrate for value-added applications including blast furnace feed by the selective flocculation followed by pelletization process, the concentrate can be further separated into a good concentrate and a high grade concentrate, the later requiring a two- step selective flocculation process; and (ii) a tailing (with rich in alumina and silica) containing mostly as sillimanite and quartz by selective dispersion and selective flocculation process. Both the alumina and silica levels in the ultra fines are in the range of 2.5 to 14wt%. The alumina and silica levels in the concentrate can be dropped down to a level of 0.8 whereas both the alumina and silica level in the tailing can be up to 21 wt% with varying level of yield of concentrate. The concentrate is most suited as the feed material for iron making through the blast furnace route, whereas the tailing is most suited as the feed material to make building material. The tailing material may be potentially suited for other applications like feed material for formulation of nano paint and nano coolant. Added advantage is that this process is environmental and eco friendly with zero waste.
Accordingly, the invention provides a process for producing a high purity Fe 2 03 for value added application and blast furnace feed from a poor grade iron ore slime . The process provides a concentrate containing a very high purity iron with very low alumina and silica from the slime containing high alumina and silica generated in the iron ore mines and the iron ore washing plants. According to the process, all the oxide minerals are dispersed and subsequently flocculated selectively under specific conditions. Two products are produced in this process, namely a concentrate, and a tailing. The concentrate contains 68.5% Fe with only around 0.8% alumina and 1.0% silica from the slime containing around 54.5% Fe, 7.61 % alumina and 7.42% silica. This concentrate is suitable for value added applications like in medical science, paint formulation, removal of hazardous elements from contaminated water and soil, and also as the blast furnace feed. The tailing are generated in this process contains 29.8% Fe with 20.5% Al 2 0 3 and 19.68% Si0 2 present mainly as the sillimanite and quartz. This tailing can be utilized as building and refractory material. This process is environmental friendly with zero waste.
Thus the inventive process can effectively produce two valuable products from the ultra fines of iron ore. One product is suitable for fine magnetic particle application or for peptization whereas the other product is suitable for refractory making, nano paint or nano coolant.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1- schematically illustrates in the form of a flow-chart of the process steps according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, the difference in surface charge of the iron bearing minerals and the gangue minerals is utilized first to separate out a first part of the gangue minerals present in the ultra fines. In the second stage, the materials from the first stage is subjected to a selective flocculation by adapting modified starch. By this process, the concentrate gets converted and suitable for use as the raw material for blast furnace, and the tailing containing high alumina and silica suitable for use as the building materials.
As shown in figure- 1, a non-selective dispersion followed by a selective flocculation process is proposed to separate out different levels of iron containing ultra fines into (i) an iron rich concentrate, and (ii) a tailing having high level of clay and refractory materials. The ultra fines are processed according to the invention include the ground rejected material of various beneficiation processes and hydro cyclone over-flow. The processable iron containing ultra fines is the mixture of Fe, Si and Al oxides with different particle size. The alumina and silica level of each includes in the range of 2.5 to 14 wt%. The particle size of the ultra fines is in the range of 100 micron to lOOnm, and separated into coarser (more than 15 micron) and finer (less than 15 micron) categories, by adapting a hydro-cyclone of different sizes. The coarser particles are caused to undergo wet grinding under varied concentration to make it finer, finer particles being more suitable for the process because they offer better liberation and better floe formation. The dispersant used in the process includes different non-selective dispersant with different dosages for example, sodium silicate and sodium hexameta phosphate. The dosages of the dispersant are selected in the range of 20 to 150000 ppm, preferably in the range of 20 to 10000 ppm. The flocculant includes different starch solutions under varied dosage. The starch includes potato, wheat and maize. The starch solution comprises plain including caustic starch solution with varied concentration of caustic for example, in the concentration range of 0.1 to 10 wt%. The process can be implemented under varied pH conditions. The range of pH solution includes 2.5 to 11, preferably 8-10. The concentration of the ultra fines includes in the range of 2 to 25wt%, with varied settling time for example, between 10 seconds to 20 hours. The process includes different mixing processes to break agglomerated particles, the mixing process comprises magnetic stirring, mechanical stirring or mixing the ultra fines in solution using ultrasonic treatment. The ultrasonic treatment includes a treatment time in the range of 1 to 300 minutes under variable ultrasonic power. The solvent includes double distilled water, distilled water, tap water and industrial process water . The industrial process water includes different degree of contamination with different metallic and non- metallic ions and bacteria.
Next Patent: ACTIVE ANTIOXIDANTS FOR ALL AGE GROUP