Novel Cationic Collectors for Improving a Process for Froth Flotation of Silicates

Abstract

A process or use of at least one hydroxyl ether diamine for improving a process for froth flotation of silicates. Compared to the benchmark ether monoamines, ether diamines or mixtures thereof, the selectivity performance of the hydroxyl ether diamines is significantly better, delivering higher recoveries for the mineral of interest.

Claims

1.-7. (canceled)

8. A process for improving collector performance of a collector composition for froth flotation of silicates, comprising the step of adding at least one hydroxyl ether diamine to a froth pulp of a mineral ore, wherein the at least one hydroxyl ether diamine is according to Formula (1) ##STR00002## wherein R.sup.1 is a linear or branched alkyl or alkenyl group having C.sub.6-C.sub.24 carbon atoms and R.sup.2, R.sup.3, R.sup.4 can be different or the same independently from each other, are H or a linear or branched alkyl or alkenyl group having C.sub.1-C.sub.5 carbon atoms and n is an integer 2-5 or is a salt of the at least one compound of Formula (1) formed by neutralization with formic, acetic, propionic or hydrochloric acid wherein the pH is greater than about 8.0, preferably the pH is greater than about 10.0.

9. The process according to claim 8, wherein is the at least one hydroxyl ether diamine is selected from the group consisting of 1-(2-aminoethylamino)-3-(octyloxy-/decyloxy)propan-2-ol, 1-(2-aminoethylamino)-3-(decyloxy)propan-2-ol, 1-(2-aminoethylamino)-3-(dodecyloxy-/tetradecyloxy)propan-2-ol , 1-(2-aminoethylamino)-3-(isononyloxy)propan-2-ol, 1-(2-aminoethylamino)-3-(octyloxy-) propan-2-ol and mixtures thereof.

10. The process according to claim 8, wherein the at least one hydroxyl ether diamine is 1-(2-aminoethylamino)-3-(isononyloxy)propan-2-ol.

11. The process according to claim 8, further comprising the addition of 1-(2-aminoethylamino)-3-(isononyloxy)propan-2-ol neutralized with formic, acetic, propionic or hydrochloric acid.

12. The process according to claim 8, wherein the mineral ore is an iron ore.

13. The process according to claim 8, wherein the mineral ore is a phosphate ore.

14. The process according to claim 8, wherein the terms “improvement of collector performance” and “improving the collector performance” mean (i) an increase of recovery rate when the hydroxyl ether diamine is present, compared to the case when it is absent; (ii) a higher selectivity in removal of silicates, which means that the collector composition comprising the hydroxyl ether diamine enables a higher proportion of the iron and phosphate to be retained and a higher proportion of the silicates to be removed, compared to the case when it is absent.

Description

EXAMPLE 1

Direct Flotation of Silicates from Iron Ore

[0073]

TABLE-US-00001 TABLE 1 Materials evaluated for direct flotation of silicates from iron ore A (comparative) 3-(isodecyloxy)propylamine B (comparative) 1,3-Propanediamine, N-[3- (tridecyloxy)propyl]-, branched C 1-(2-aminoethylamino)-3- (octyloxy-/decyloxy)propan-2-ol D 1-(2-aminoethylamino)-3- (decyloxy)propan-2-ol E 1-(2-aminoethylamino)-3- (dodecyloxy-/tetradecyloxy)propan-2-ol F 1-(2-aminoethylamino)-3- (isononyloxy)propan-2-ol G 1-(2-aminoethylamino)-3- (octyloxy-)propan-2-ol

[0074] The collectors A to G were tested in the direct flotation of silicates in an iron ore sample from flotation feed. The iron ore sample used for this study was characterized in terms of chemical analysis and particle size analysis with the results given in Table 3 (hereinafter also referred to as crude iron ore).

[0075] The content of silicate in the ores was determined by a gravimetric method. The ore was decomposed by an acid attack (HCl) leading to the dissolution of metal oxides and metal hydroxides, and leaving insoluble silicates as the residue. The iron content of the ores was determined by a titration method wherein the sample was decomposed by an acid attack (HCl), trivalent iron was reduced to bivalent iron by addition of stannous chloride (SnCl.sub.2) and mercury chloride (HgCl) and the iron content was determined by titration with potassium dichromate (K.sub.2Cr.sub.2O.sub.7).

[0076] The particle size was determined by wet sieving according to ASTM E276-13 wherein sieves of different openings were used. The results of this analysis are given in the table 2 below. P80 represents the diameter of openings through which eighty percent of the particles pass; D50 represents the diameter of the particle that 50 wt.-% of a sample's mass is smaller than and 50 wt.-% of a sample's mass is larger than; %-38 μm represents the percentage of particles smaller than 38 μm.

TABLE-US-00002 TABLE 2 Characterization of the crude iron ores used for flotation tests Iron Item Ore Sample iron content 32.4% silicate content 51.4% P80 124 μm D50  63 μm %−38 μm 31.7%

[0077] The flotation tests were done in laboratory scale using a Denver Flotation Cell D12 apparatus at a temperature of about 25° C. according to the following procedure: A sample with 1 kilogram of the respective crude iron ore was charged to the flotation cell of 1.5 l volume and water was added in order to prepare a pulp of 50 wt.-% of solids content. The stirrer was set to a speed of 1200 rpm and the pulp was homogenized for 1 minute. Then, a depressant (corn starch alkalized with NaOH in a weight ratio of starch to NaOH of 6:1) was added in a dosage rate of 600 mg/kg in respect to the dried ore. The pulp was conditioned under stirring for 5 minutes. The pH of the pulp was controlled and, if necessary, adjusted to 10.0 by further addition of NaOH. A collector composition according to Table 1 was added in the required dosage of dry ore. For ease of handling the collector compositions were applied as aqueous solutions of 1 wt.-% by weight active. The collector was conditioned in the ore pulp for 1 minute. Then air flow was started and froth flotation was done for 3 minutes. The floated mass (tailings) and the depressed mass (concentrated iron ore) were collected in separate bowls and dried in a lab oven. Both samples (depressed and floated) were then analyzed in respect to weight, SiO.sub.2 content and iron content according to the methods described above.

[0078] The results are given in terms of the following parameters: [0079] Fe content—Concentrate (wt.-%): content of Fe present in the concentrate (non floated mass). [0080] SiO.sub.2 content—Concentrate (wt.-%): content of silicate present in the concentrate (non floated mass). [0081] Fe content—Tailings (wt.-%): content of Fe present in the tailings (floated mass). [0082] SiO.sub.2 content—Tailings (wt.-%): content of SiO.sub.2 present in the tailings (floated mass). [0083] Fe. Recovery (wt.-%): weight ratio of iron mass recovered in the concentrate (non floated mass) in relation to the total mass of iron in the crude iron ore.

[0084] Targets considered for this flotation trials are Fe content higher than 65 wt. - % in the concentrate and silicate lower than 3 wt. - % in the concentrate. A higher wt. -% of the Fe Recovery is better.

TABLE-US-00003 TABLE 3 Results of flotation experiments with iron ore sample SiO.sub.2 Fe SiO.sub.2 Fe content— content— content— content— Fe Dosage Concentrate Concentrate Tailings Tailings Rec Example Collector [g/to] [wt.-%] [wt.-%] [wt.-%] [wt.-%] [wt.-%] 1 A (comparative) 150 67.8% 2.90% 13.6% 77.3% 72.7% 2 B (comparative) 150 66.5% 4.82% 12.8% 78.8% 76.5% 3 50% A + 50% B 150 67.6% 2.78% 13.1% 77.9% 74.1% (comparative) 4 C 150 67.9% 2.01% 10.5% 81.5    79.8% 5 D 150 67.4% 2.60% 11.3% 80.9    78.4% 6 E 150 67.2% 2.36% 11.9% 79.5% 78.0% 7 F 150 67.5% 2.32% 10.2% 81.9% 80.4% 8 G 150 67.6% 2.30% 10.4% 81.6% 80.1%

[0085] The experimental results show that the hydroxyl ether diamines (C to G) were able to collect silicates selectively from iron minerals, since SiO.sub.2 content was reduced below 3% in the concentrate and the Fe recovery was higher than the benchmark collectors (Collector A and B). Results also demonstrated that the hydroxyl ether diamines achieved better results even than the benchmark collectors used in combination (test number 3), achieving less SiO.sub.2 in the concentrate and higher iron recovery.

EXAMPLE 2

Direct Flotation of Silicates from Phosphate Ore

[0086]

TABLE-US-00004 TABLE 4 Materials evaluated for direct flotation of silicates from phosphate ore A (comparative) 3-(isodecyloxy)propylamine B (comparative) 1,3-Propanediamine, N-[3- (tridecyloxy)propyl]-, branched F 1-(2-aminoethylamino)-3- (isononyloxy)propan-2-ol

[0087] Collectors A, B and F were tested in the direct flotation of silicates in a phosphate ore sample from flotation feed. The phosphate ore sample used for this study was characterized in terms of chemical analysis and particle size analysis with the results given in Table 5.

[0088] The content of SiO.sub.2 and P.sub.2O.sub.5 in the ores was determined by X-ray fluorescence. The particle size was determined by wet sieving according to ASTM E276-13 wherein sieves of different openings were used. The results of this analysis are given in the table 7 below. P80 represents the diameter of openings through which eighty percent of the particles pass; D50 represents the diameter of the particle that 50 wt.-% of a sample's mass is smaller than and 50 wt.-% of a sample's mass is larger than; %-38 μm represents the percentage of particles smaller than 38 μm.

TABLE-US-00005 TABLE 5 Characterization of the crude iron ores used for flotation tests Phosphate Item Ore Sample P.sub.2O.sub.5 content 23.7% SiO.sub.2 content 14.2% P80 195 μm D50 106 μm %−38 μm  1.4%

[0089] The flotation tests were done in laboratory scale using a Denver Flotation Cell D12 apparatus at a temperature of about 25° C. according to the following procedure: A sample with 0.5 kilogram of the respective crude iron ore was charged to the flotation cell of 4.0 l volume and water was added in order to prepare a pulp of 15 wt.-% of solids content. The stirrer was set to a speed of 1300 rpm and the pulp was homogenized for 1 minute. The pH of the pulp was monitored, and flotation occurs under pulp natural pH (7.5). A collector composition according to Table 4 was added in the required dosage of dry ore. For ease of handling the collector compositions were applied as aqueous solutions of 1 wt.-% by weight active. The collector was conditioned in the ore pulp for 1 minute. Then air flow was started and froth flotation was done for 2.5 minutes during the rougher stage. The floated mass (tailings) was collected to a bowl. Remaining pulp was kept under stirring in the flotation cell to run the cleaner stage. Collector composition was added in the required dosage of dry ore. Then air flow was started and froth flotation was done for additional 2.5 minutes during the cleaner stage. Depressed mass (phosphate concentrate) was collected in separate bowls and dried in a lab oven. All samples (floated rougher, floated cleaner and depressed cleaner) were then analyzed in respect to weight, SiO.sub.2 content and P.sub.2O.sub.5 content according to the methods described above.

[0090] The results are given in terms of the following parameters: [0091] P.sub.2O.sub.5 content in concentrate (wt.-%): content of P.sub.2O.sub.5 present in the concentrated phosphate ore (depressed mass). [0092] SiO.sub.2 content in concentrate (wt.-%): content of SiO.sub.2 present in the concentrated phosphate ore (depressed mass). [0093] SiO.sub.2 content in tailings (wt.-%): content of SiO.sub.2 present in the tailings (floated mass). [0094] P.sub.2O.sub.5 Recovery (wt.-%): weight ratio of P.sub.2O.sub.5 mass recovered in the concentrate (depressed mass) in relation to the total mass of P.sub.2O.sub.5 in the feed.

[0095] Targets considered for these flotation trials are P.sub.2O.sub.5 content higher than 29 wt.-% % in the concentrate and SiO.sub.2 lower than 5 wt. - % in the concentrate. A higher wt. - % of the P.sub.2O.sub.5 Recovery is better.

TABLE-US-00006 TABLE 6 Results of flotation experiments with phosphate ore sample SiO.sub.2 P.sub.2O.sub.5 SiO.sub.2 Content Content in Content in in P.sub.2O.sub.5 Dosage concentrate concentrate tailings Recovery Example Collector [g/to] [wt.-%] [wt.-%] [wt.-%] [wt.-%] 1 A 150 30.3% 3.52% 30.7% 74.2% 2 B 150 30.1% 3.78% 33.7% 77.9% 3 F 150 30.7% 3.47% 43.6% 89.0%

[0096] The experimental results show that the hydroxyl ether diamine (F) was able to collect silicates selectively from phosphate minerals, since SiO.sub.2 content was reduced below 5 wt. - % in the concentrate. Surprisingly it was demonstrated that the hydroxyl ether diamine achieved even higher P.sub.2O.sub.5 recovery than the benchmark collectors (collector A and B).

[0097] For both Fe Recovery and P.sub.2O.sub.5 Recovery, direct flotation of silicates in an iron ore and direct flotation of silicates in a phosphate ore, collectors based on hydroxyl ether diamine have demonstrated higher selectivity in the process, ensuring quality targets and recovering higher amount of the valuable minerals, by higher iron and phosphate recoveries. It follows that the flotation process is more sustainable, since less waste is generated and greater use of mineral resources is guaranteed, compared to benchmark technology.