Claims:1. A process for preparing compound of Formula-I:

Compound of Formula-I
wherein ‘R’ is alkyl chain;
or salts thereof,
said process comprising reacting alkyl amine with acrylamide in presence of iron and solvent.

2. The process as claimed in claim 1, wherein the alkyl chain is selected from a group comprising C6, C8 and C12 alkyl chains.

3. The process as claimed in claim 1, wherein the alkyl amine is selected from a group comprising C6, C8 and C12 alkyl amine.

4. The process as claimed in claim 1, wherein the solvent is selected from a group comprising Dichloromethane, Acetonitrile, Tetrahydrofuran, ionic liquids, ethyl acetate, DMF and combinations thereof.

5. The process as claimed in claim 1, wherein the ionic liquid is

3-Butyl-1-methyl-1H-imidazol-3-ium bromide (BMIM-Br), or

3-Butyl-1-methyl-1H-imidazol-3-ium acetate (BMIM-OAc),
or a combination thereof.

6. The process as claimed in claim 1, wherein the iron is in the form of iron powder and is present at a concentration ranging from about 1mol % to 5 mol %, and wherein the process is carried at a temperature ranging from about 25 °C to 70 °C and for a time period ranging from about 2 to 48 hours.

7. The process as claimed in claim 1, wherein the process further comprises isolation and/or purification of the Formula-I product; wherein said isolation and/or purification is carried out by acts selected from a group comprising separation of iron powder using a magnet, adding and/or washing with solvent, precipitation, evaporation, quenching, filtration, extraction and combination of acts thereof.

8. The process as claimed in claim 1, wherein the salt of compound of Formula I is selected from a group comprising acetate salt, hydrochloride salt, sulfonate salt and combinations thereof.

9. The process as claimed in claim 1, wherein the salt of compound of Formula I is prepared by reacting the compound of Formula-I with a salt forming reagent.

10. The process as claimed in claim 9, wherein the salt forming reagent is selected from a group comprising acetic acid, hydrochloric acid, sulfonate salt and combinations thereof.

11. The process as claimed in claim 1, wherein the Formula-I compound is 3,3'-(Dodecylazanediyl)dipropanamide, 3,3'-(Octylazanediyl)dipropanamide or 3,3'-(Hexylazanediyl)dipropanamide.

12. The process as claimed in claim 1, wherein the process comprises preparing 3,3'-(Dodecylazanediyl)dipropanamide by reacting dodecylamine with acrylamide in presence of iron and solvent.

3,3'-(Dodecylazanediyl)dipropanamide

13. The process as claimed in claim 12, wherein the iron powder is present at a concentration of about 5 mol%, and wherein the process is carried at a temperature ranging of about 60°C and for a time period of about 4 hours.

14. The process as claimed in claim 1 or claim 12, wherein salt form of the 3,3'-(Dodecylazanediyl)dipropanamide is prepared by reacting 3,3'-(Dodecylazanediyl)dipropanamide with a salt forming reagent as defined in claim 10.

15. A method for removal of alumina, silica or a combination thereof from low-grade iron ore, said method comprising employing the compound of Formula-I as floatation reagent.

16. A method for obtaining iron ore concentrate from a low-grade iron ore, comprising steps of:
a) contacting a feed comprising the low-grade iron ore with water to obtain a mixture 1;
b) maintaining pH of the mixture 1 at about 9.5 to 10.5, followed by adding a depressant to obtain a mixture 2;
c) contacting compound of Formula-I or a salt thereof with mixture 2, followed by addition of a frother reagent to obtain a mixture 3; and
d) collecting tailings and drying to obtain the iron ore concentrate.

17. The method as claimed in claim 16, wherein the Formula-I or salt thereof removes alumina, silica or a combination thereof from the low-grade iron ore.

18. The method as claimed in claim 16, wherein the pH of the mixture 1 at about 9.5 to 10.5 is maintained by adding alkali metal hydroxide selected from a group comprising sodium hydroxide, potassium hydroxide, sodium carbonate and combinations thereof; and the depressant is selected from a group comprising causticized starch solution, Corn starch, guar gum, dextrin, natural polysaccharides and combinations thereof.
, Description:TECHNICAL FIELD
The present disclosure is in the field of chemical sciences and metallurgy. The present disclosure describes a process for preparing flotation reagents. In particular, the present disclosure relates to a process for preparing compound of Formula-I or salts thereof using an iron mediated Aza Michael addition reaction in presence of solvent(s). The present disclosure further describes the applications of compound of Formula-I as flotation reagents for effective removal of gangue, such as alumina and silica from low-grade iron ores.

BACKGROUND OF THE DISCLOSURE
Iron ores containing high Al2O3/SiO2 gangue are detrimental to blast furnace and sinter plant operations. Therefore, they have to be beneficiated before being fed to the blast furnace for optimum production of steel. Kaolinite is a common gangue mineral frequently found in iron ore deposits. In iron ore flotation, both direct and reverse flotation techniques have been employed. Chemical reagents are the most important part of the flotation process. Based on their function, the reagents are divided into collectors, frothers, regulators and depressants. In flotation practice, the collector consists of a functional group that is polar and a nonpolar hydrocarbon chain or a polymeric compound. The selectivity of the collector and mineral interaction is determined by the characteristic of the functional group and the nature of the hydrocarbon chain. The capacity of a mineral to adsorb selectively a particular reagent molecule depends on a wide range of chemical, thermodynamic and steric factors. Iron ore bearing minerals like hematite can be floated by a variety of collectors, such as amines, oleates, sulfonates and sulfates.

Beneficiation of iron ore slimes containing significant amount of Fe along with SiO2 and Al2O3 can be concentrated either by reverse cationic flotation of aluminosilicates (Kaolin) or direct anionic flotation of Fe. The cationic reverse flotation of aluminosilicates seems to be an attractive route for the concentration of low-grade ores. However, this is not practiced widely as it is a very difficult task to float alumina. This is because alumina selective reagents are not available as flotation collectors. The collectors available for reverse flotation are mostly silica selective and applicable for ores outside India which have basically silica/quartz as the main impurity. Therefore, it is an important task to design and synthesize cationic collectors for reverse flotation, which can improve the selectivity and floatability of gangue minerals with respect to iron ore.

Primary, secondary and tertiary amines with a carbon chain of varying length have found use in froth flotation of silica and other ores. In case of iron ore flotation, amines have been used for reverse flotation process. But these are effective only when the gangue mineral is basically siliceous in nature. Further, the currently available methods/reagents are not effective in providing good/efficient results with respect to iron ore-gangue separation, and usually result in iron ore concentrates with very low yields. Hence, it will be of great importance and lucrative to the industry if flotation reagents are developed for beneficiation of iron ores.

SUMMARY OF THE DISCLOSURE
The present disclosure describes a process for preparing a compound of Formula-I

Compound of Formula-I
wherein ‘R’ is alkyl chain;
or salts thereof,
said process comprising reacting alkyl amine with acrylamide in presence of iron and solvent.

The present disclosure further provides a method for removal of alumina, silica or a combination thereof, from low-grade iron ore, said method comprising employing the Formula-I compound of the present invention as floatation reagent.

The present disclosure also provides a method for obtaining iron ore concentrate from low-grade iron ore, comprising acts of:
a) contacting a feed comprising the low-grade iron ore with water to obtain a mixture 1;
b) maintaining the pH of the mixture 1 at about 9.5 to 10.5, followed by adding a depressant to obtain a mixture 2;
c) contacting compound of Formula-I or a salt thereof with mixture 2, followed by addition of a frother reagent to obtain a mixture 3; and
d) collecting tailings and drying to obtain the iron ore concentrate.

The present disclosure furthermore describes applications of the compound of Formula-I in iron ore beneficiation, more particularly in iron ore-gangue separation. The Formula-I compounds can be used for flotation of gangue selected from a group comprising alumina and silica to produce low alumina concentrates and high iron-ore yields.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figure(s). The figure(s) together with detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present disclosure where:

FIGURE 1 illustrates the NMR spectrum of 3,3'-(Dodecylazanediyl)dipropanamide.

DETAILED DESCRIPTION OF THE DISCLOSURE
The present disclosure is in relation to the beneficiation of iron ores. An object of the present invention is to synthesize compounds/reagents and corresponding methods for efficient iron ore-gangue separation.

The present disclosure describes flotation reagents for removal of minerals including but is not limited to alumina and silica from ore, such as low-grade iron ore slime.

The present disclosure describes a process for preparing a compound of Formula-I

Compound of Formula-I
wherein ‘R’ is alkyl chain;
or salts thereof,
said process comprising reacting alkyl amine with acrylamide in presence of iron and solvent.

In an embodiment of the process, the alkyl chain is selected from a group comprising C6, C8 and C12 alkyl chains.
In another embodiment of the process, the alkyl amine is selected from a group comprising C6, C8 and C12 alkyl amine.
In yet another embodiment of the process, C6 alkyl amine is hexylamine.

In still another embodiment of the process, C8 alkyl amine is octylamine.

In still another embodiment of the process, C12 alkyl amine is dodecylamine.

In an embodiment of the process, the salt form of compound of Formula I is selected from a group comprising acetate salt, hydrochloride salt, sulphate salt and combinations thereof.

In another embodiment of the process, the salt form of compound of Formula I is prepared by reacting compound of Formula-I with a salt forming reagent.

In another embodiment of the process, the salt forming reagent is selected from a group comprising acetic acid, hydrochloride salt, sulphate salt and combinations thereof.

In an embodiment, the compound of Formula-I is 3,3'-(Dodecylazanediyl)dipropanamide.

3,3'-(Dodecylazanediyl)dipropanamide
In another embodiment of the present disclosure, Formula-I compound is 3,3'-(Dodecylazanediyl)dipropanamide, 3,3'-(Octylazanediyl)dipropanamide or 3,3'-(Hexylazanediyl)dipropanamide.

In an embodiment of the present process, 3,3'-(Dodecylazanediyl)dipropanamide is prepared by reacting dodecylamine with acrylamide in presence of iron and solvent.

In an embodiment of the process, the solvent is selected from a group comprising dichloromethane, acetonitrile, tetrahydrofuran, ionic liquids, ethyl acetate, toluene, DMF and combinations thereof.

In another embodiment of the process, the preferred solvent is ionic liquid.

In another embodiment of the process, the ionic liquid is

3-Butyl-1-methyl-1H-imidazol-3-ium bromide (BMIM-Br), or

3-Butyl-1-methyl-1H-imidazol-3-ium acetate (BMIM-OAc),

or a combination thereof.
In another embodiment of the present process, the iron is in the form of iron powder which is present at a concentration ranging from about 1 mol% to 5 mol %, and wherein the process is carried at a temperature ranging from about 25 °C to 70 °C and for a time period ranging from about 4 to 24 hours.

In yet another embodiment of the present process, the iron powder is present at a concentration of about 5 mol%, and wherein the process is carried at a temperature ranging of about 60°C and for a time period of about 4 hours.

In still another embodiment of the present process, the process further comprises isolation and/or purification of the Formula-I product; wherein said isolation and/or purification is carried out by acts selected from a group comprising separation of iron powder using a magnet, adding and/or washing with solvent, precipitation, evaporation, quenching, filtration, extraction and combination of acts thereof.

In a preferred embodiment of the present disclosure, the process of preparation of compound of Formula-I including alkyl azanediyldipropanamide comprises treating alkyl amine with acrylamide in presence of iron and solvent to obtain a reaction mixture. The reaction mixture is heated followed by stirring under heating conditions in inert atmosphere. The progress of the reaction is monitored by thin-layer chromatography (TLC). After the completion of the reaction, iron is separated. Solvent is added to the above obtained mixture and is subjected to stirring to obtain a precipitate, which is filtered out and washed with solvent to remove unreacted acrylamide. The obtained precipitate is subjected to drying to obtain alkyl azanediyldipropanamide. Iron used in the instant process is in the form of iron powder and it can be reused for next reaction. In an embodiment, iron powder is recycled and reused for about five cycles.

Scheme 1: Retrosynthesis of alkyl azanediyldipropanamide.

Scheme 2: General synthetic scheme for preparing alkyl azanediyldipropanamide.
In an exemplary embodiment of the present disclosure, the synthesis of compound of Formula-I comprises treating alkyl amine (about 1 equivalent) with acrylamide (about 2.2 equivalents) in presence of iron powder (about 5 mol%) and ionic liquid (about 2 volumes) to obtain a reaction mixture. The reaction mixture is heated up to about 60 oC followed by stirring at the same temperature for about 4 hours under nitrogen atmosphere. The progress of the reaction is monitored by TLC. After the completion of the reaction, iron powder is separated by magnet. About 2 volumes of acetone is added to the above obtained mixture and subjected to stirring for about 30 minutes to obtain white solid precipitate, which is filtered out and washed with about 0.5 volumes of acetone. The obtained solid precipitate is subjected to drying for about 15 minutes under vacuum oven at about 40 oC. Acetone washings are evaporated to get back ionic liquid and is used for next reaction as a solvent.

In an embodiment, the synthesis of Formula-I compounds when performed with different solvents (BMIM-Br, BMIM-OAc, CH2Cl2, Tetrahydrofuran and Acetonitrile) without catalyst (iron) at reflux temperature result in very poor conversion with low yields.

In another embodiment, yield of the compound of Formula-I obtained by the process of the present disclosure ranges from about 60% to 70%.

In an exemplary embodiment, yield of the compound of Formula-I obtained by the process of the present disclosure is about 60% to 70%.

In an embodiment of the present disclosure, salt form of 3,3'-(Dodecylazanediyl)dipropanamide is prepared by reacting 3,3'-(Dodecylazanediyl)dipropanamide with a salt forming reagent.

In an exemplary embodiment, the salt of 3,3'-(Dodecylazanediyl)dipropanamide is 3,3'-(Dodecylazanediyl)dipropanamide acetate.

In another exemplary embodiment of the present disclosure, acetate salt of 3,3'-(Dodecylazanediyl)dipropanamide is prepared by reacting 3,3'-(Dodecylazanediyl)dipropanamide with acetic acid.
The present disclosure further provides a method for removal of alumina, silica or a combination thereof from low-grade iron ore, said method comprising employing the compound of Formula-I as flotation reagent.

The present disclosure also relates to a method for obtaining iron ore concentrate from low-grade iron ore, comprising acts of:
a) contacting a feed comprising the low-grade iron ore with water to obtain a mixture 1;
b) maintaining the pH of the mixture 1 at about 9.5 to 10.5, followed by adding a depressant to obtain a mixture 2;
c) contacting compound of Formula-I or a salt of the compound of Formula-I with mixture 2, followed by addition of a frother reagent to obtain a mixture 3; and
d) collecting tailings and drying to obtain iron ore concentrate.

In an embodiment of the above described method, low-grade iron ore in the feed comprises about 58 to 61% of Fe(t), about 2.5 to 4 % of Al2O3 and about 2 to 4 % of SiO2.

In another embodiment of the above described method, the obtained iron ore concentrate comprises about 62 to 64% of Fe, about 2 to 3 % of Al2O3, and about 1.2 to 2.2 % of SiO2.

In yet another embodiment of the above described method, the Formula-I in the method removes alumina, silica or a combination thereof from the low-grade iron ore.

In still another embodiment of the above described method, the pH of the mixture 1 at about 9.5 to 10.5 is maintained by adding alkali metal hydroxide selected from a group comprising sodium hydroxide, potassium hydroxide, sodium carbonate and combinations thereof.

In still another embodiment of the above described method, the depressant is selected from a group comprising causticized starch solution, Corn starch, guar gum, dextrin, natural polysaccharides and combinations thereof.

In an embodiment of the present disclosure, the synthesised compounds of Formula-I are flotation reagents and are employed for removal of gangue including but not limited to alumina and silica from ore, such as low-grade iron ore. In an exemplary embodiment, the compound of Formula-I is employed for removal of gangue including but not limited to alumina and silica from low-grade iron ore.

In another embodiment of the present disclosure, the compound of Formula-I has high selectivity and specificity for gangue including but not limited to alumina and silica.

In yet another embodiment, the compound of Formula-I possesses hydrophobic-hydrophilic balance for effective flotation of gangue, such as alumina and silica.

In still another embodiment, the compound of Formula-I possesses high hydrogen bonding capabilities for effective interaction with gangue, such as alumina and silica.

The present disclosure further describes use of the synthesized compound of Formula-I for flotation of gangue.

In an embodiment, the compound of Formula-I is used for flotation of gangue including but not limiting to alumina and silica.

In another embodiment, the compound of Formula-I causes selective removal of gangue, such as alumina and silica.

In yet another embodiment, the compound of Formula-I causes selective removal of gangue, such as alumina.

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon the description provided. The embodiments provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments. The examples provided herein are intended merely to facilitate an understanding of ways in which the embodiments provided may be practiced and to further enable those of skill in the art to practice the embodiments provided. Accordingly, the following examples should not be construed as limiting the scope of the embodiments.

EXAMPLES

Example 1: Process of preparing compound of Formula-I
Compound of Formula I, namely alkyl azanediyldipropanamide was synthesised using the following procedure:

Alkyl amine (1 equivalent) was treated with acrylamide (2.2 equivalents) in presence of iron powder (1mol% to 5 mol%) and solvent 2 volumes to obtain the reaction mixture. The reaction mixture was heated up to 60 oC followed by stirring at the same temperature for 4 hours under nitrogen atmosphere. The progress of the reaction was monitored by TLC. After the completion of the reaction, Iron powder was separated by the magnet. 2 volumes of acetone were added to the above obtained mixture and subjected to stirring for 30 minutes to obtain white solid precipitate, which was filtered out and washed with 0.5 volumes of acetone. The obtained solid precipitate was subjected to drying for 15 minutes under vacuum oven at 40 oC. Compound obtained as a white solid with 60% to 70%.

Example 2: Process of preparing the salt of compound of Formula-I
Formula-1 (1 eq.) was dissolved in methanol, cooled to 5 oC to 10 oC. Acetic acid (1.2 eq.) was added drop wise pH of the reaction mixture 3 to 4. White solid precipitated out stirred the mass at 25 oC to 30 oC for 2 hours. Filtered the solid washed with 1 volume of chilled methanol suck dried for 30 min and dried the solid under vacuum oven at 50 oC for 4 hours.

Example 3: Process of preparing the compound of Formula-I [3,3'-(Dodecylazanediyl)dipropanamide]
Dodecylamine (1 equivalent) was treated with acrylamide (2.2 equivalents) in presence of iron powder (5mol%) and solvent 2 volumes to obtain the reaction mixture. The reaction mixture was heated up to 60 oC followed by stirring at the same temperature for 4 hours under nitrogen atmosphere. The progress of the reaction was monitored by TLC. After the completion of the reaction, Iron powder was separated by the magnet. 2 volumes of acetone was added to the above obtained mixture and subjected to stirring for 30 minutes to obtain white solid precipitate, which was filtered out and washed with 0.5 volumes of acetone. The obtained solid precipitate was subjected to drying for 15 minutes under vacuum oven at 40 oC. The product was characterized and the NMR spectra is provided under Figure 1.

Table 1 below illustrates the catalytic role played by iron powder in increasing the rate of the reaction and yield of the product.

Table 1: Effect of catalyst [Fe] on product formation/yields

S. No Solvent Catalyst (Fe) Time (h) Temperature (oC) Yield (%)
1. Dichloromethane Without Fe 24 50 20 - 30
2. Acetonitrile Without Fe 24 60 20 - 30
3. Tetrahydrofuran Without Fe 24 70 20 - 30
4. BMIM-Br Without Fe 24 70 20 - 30
5. BMIM-OAc Without Fe 24 70 20 - 30
6. Dichloromethane Fe (1 mol%) 16 - 20 50 50 - 60
7. Dichloromethane Fe (2.5 mol%) 12 - 15 50 60 - 70
8. Dichloromethane Fe (5 mol%) 4 - 6 50 60 - 70
9. Acetonitrile Fe (1 mol%) 16 - 24 50 50 - 60
10. Acetonitrile Fe (2.5 mol%) 12 - 15 50 60 - 70
11. Acetonitrile Fe (5 mol%) 4 - 6 60 60 - 70
12. Tetrahydrofuran Fe (1 mol%) 16 - 18 50 60 - 70
13. Tetrahydrofuran Fe (2.5 mol%) 12 - 15 50 60 - 70
14. Tetrahydrofuran Fe (5 mol%) 4 - 6 70 60 - 70
15. BMIM-Br Fe (1 mol%) 16 - 20 50 60 - 70
16. BMIM-Br Fe (2.5 mol%) 12 - 18 50 60 - 70
17. BMIM-Br Fe (5 mol%) 4 - 6 70 60 - 70
18. BMIM-OAc Fe (1 mol%) 16 - 20 50 60 - 70
19. BMIM-OAc Fe (2.5 mol%) 12 - 15 50 60 - 70
20. BMIM-OAc Fe (5 mol%) 4 - 6 70 60 - 70

It is evident from the above results that the absence and presence of iron powder has significant influence in altering the rate of the reaction and in improving the yield of the product. In other words, it is demonstrated that iron powder plays a critical role in carrying out the synthesis of compound of Formula-I, such as 3,3'-(Dodecylazanediyl)dipropanamide. Further, the results also demonstrated that 1mol% of Fe requires 20 hours to complete the above said reaction with 60 to 70% yield, whereas 2.5 mol% of Fe requires the reaction time of around 15 hours to complete the same reaction to give 60 -70% yield.

Example 4: Process of preparing salt of 3,3'-(Dodecylazanediyl)dipropanamide
Formula-1 (1 eq.) was dissolved in methanol, cooled to 5 oC to 10 oC. Acetic acid (1.2 eq.) was added drop wise pH of the reaction mixture 3 to 4. White solid precipitated out stirred the mass at 25 oC to 30 oC for 2 hours. Filtered the solid washed with 1 volume of chilled methanol suck dried for 30 min and dried the solid under vacuum oven at 50 oC for 4 hours in a quantitative yield.

Example 5: Flotation test illustrating the separation of alumina and silica, and concentration of iron ore

Flotation experiments
Chemical and Materials for the flotation test -
Materials required:
1. Weight of iron ore sample: 500g
2. Size of the iron ore sample: -200# (mesh)
3. Collector used: Synthesized reagents (compound of Formula I)
4. Depressant used: causticized starch solution (200 ppm)
5. pH regulator: NaOH, HCl
6. pH maintained: 8.5-9.5
7. pH meter
8. trays, weighing balance, beakers, droppers, conical flasks, glass rod
9. Acetic acid
Preparation of causticized starch solution:
a) 100mL of water was taken in a beaker.
b) It was heated in a magnetic stirrer up to a temperature of 80 degree centigrade.
c) Then, 0.5g of NaOH flakes was added.
d) Thereafter, 1g of potato starch was added slowly with continuous stirring for 2 to 5 minutes.
e) Then the solution was cooled as soon as possible.
Procedure -
About 1000 ml of water was poured into the flotation cell and the about 500g of the iron ore sample was added to the floatation cell. The pH was maintained between 9.5 to 10.5 by adding NaOH. After about 5 minutes, about 500-1000 ppm causticized starch solution was added, followed by adding the compound of Formula-I [i.e. 3,3'-(Dodecylazanediyl)dipropanamide] to the samples and conditioning the sample for about 3 minutes to 5 minutes. Formula-I was converted into acetate salt as shown in scheme 3 below. Frother was added to the sample and after about 2 minutes, the air valve of the flotation cell was opened. The material was raked off after 30 seconds and froth was collected for about 5 minutes. Tailings were collected separately as froth 1 and froth 2. The products were dried, weighed and sent for chemical analysis.

Wherein ‘R' is Dodecyl, octyl or hexyl moieties.
Scheme 3: Synthesis of acetate salt of alkyl azanediyldipropanamide

Result and Inference -
Flotation tests were performed on 500 g of iron ore sample (size: -200#, mesh) using the dipropanamide derivatives (Formula I compounds) as collectors. The feed alumina range was 2%-4% and silica range was 2.0%-4%. In all the flotation experiments, two fragments were collected, basically that is froth and tailings. In a reverse flotation system, the froth is the impurity and the tailing which remains behind in the flotation machine is the product and is called the concentrate. The employment of diamides and derivatives (synthesised Formula I compounds mentioned above) afforded the final product, which contained alumina and silica in the range of 1.8%-2.8% and 1.2%-2.0% respectively with a yield of around 60% to 70%. The commercially available flotation reagents or collectors are silica specific. They are more suitable for other types of ores mainly from USA, Brazil, China etc. which contain silica/quartz as the major impure phase with iron ore. With the available collectors we are able to reduce silica to the desired level that is in the range of 2.0-2.5 but alumina levels in the concentrate was in the range of 3.0-3.5. It is observed that when the iron in the feed sample is 58, then the
iron in the concentrate is 62; and accordingly when the iron content in the feed is 61, then the
iron in the concentrate is 64. The same is observed in case of alumina and silica as well.

Fe(t)% Al2O3 (%) SiO2 (%) Yield (%)
Feed 58-61 2.5-4 2-4 100
Concentrate obtained by employing Formula I compound [acetate salt of 3,3'-(Dodecylazanediyl)dipropanamide] 62-64 1.8-2.8 1.2-2 70-80

In summary, the compound of Formula-I showed good selectivity for minerals like silica and alumina in reverse floatation process giving high yields of iron ore concentrates as shown in the results above. The alumina levels in the final concentrate was brought down to a level of less than 1.8 -2.8% and the silica levels were also lowered to a great extent of less than 1.2 - 2%.