US2475581A - Froth flotation of iron ore with sulfonated fatty acid - Google Patents

Description

PatentedjJuly 12, 1949 FROTH FLOTATION OF IRON ORE WITH SULFONATED FATTY ACID Robert B. Booth, Springdale, and Earl C. Her-kenhol'l', Stamford,

ration oi Maine Conn., Cyanamid Company,

assignor's to American New York, N. Y., a corpo- No Drawing. ApplicationFebruary 8, 1944,

Serial No. 521,574

r 7 Claims. 1 This invention relates to a process of beneficiating iron ores. More particularly, the invention relates tothose processes of iron ore beneficiation by froth flotation in which sulfonated organic carboxylic acids are used as promoting agents.

The beneflciation of iron ore by froth flotation has presented a number of peculiarly diflicult practical problems. Naturally-occurring high grade ores have kept the unit value at a low figure. Economic considerations have, therefore, required a beneficiated concentrate to contain a high content of iron and that the recovery be fairly high. While it is a comparatively simple matter to concentrate certain iron ores by froth flotation with a number of different promoters of, the anionic-type, such asoleic acid and the like, the results obtained have not been within an economically competitive range.

Rapidly diminishing. sources of available high grade ore, particularly in the United States, have recently created increasing interest in beneficiating low grade iron ores by froth flotation. It is therefore a principal object of the present invention to develop such a process which will permit the production of concentrates in a sufficiently high grade and recovery to be advantageously compared with naturally-occurring ores At the same time it is also desirable that the process be one which is simple in operation, low in cost and makes use of readily available reagents.

In general, according to the present invention, these objects are accomplished by conditioning low grade iron ores with a sulfonated fatty acid and an acid having a dissociation constant greater than 10-". For best results an accessory oiling agent, preferably an unsulfonated oil, is usually helpful. The conditioned ore is then subjected to froth flotation in a conventional procedure.

The subject matter of the present invention constitutes a continuation-in-part of our copending application for U. S. Letters Patent Serial No. 498,254 patented September 18, 1945 No. 2,385,054, filedAugust 11, 1943, which discloses theuse of sulfonated talloel for the same purpose.

Throughout the specification and claims the term sulfonated fatty acids is used in its ordinary sense to designate the products obtained by treating a fatty acid with a sulfonating agent,

usually strong sulfuric acid. Consequently, it is quite possible that the fatty acids may be either sulfonated or sulfated or both. There is no intention that the term sulfonated fatty acids" shall be restricted to include only those compounds in which the sulfur is present in the form of sulfonic acid groups.

As pointed out in connection with suli'onated talloel in our above-mentioned copending application, useful results ordinarily depend upon an acid treatment of the ore, except possibly in those cases in which the fatty acid reagent is highly sulfonated. Such cases are not an exception since such promoters are usually suificiently acid in themselves to producethe' necessary number of available H+ ions or contain suflicient residual acid from the sulfonating operation to furnish the necessary acidity. Apparently the acid treatment produces a change in the nature of the mineral surfaces. The exact nature of this change is not wholly understood and it is not meant that this invention be limited to any particular theory of operation. It does appear to be necessary that the fatty acid be sulfonated and that suificient acid be used during the ore treatment to produce a pH less than seven.

It is an advantage of the present invention that the particular acid from which the H+ ions are derived does not appear to be critical except that results of practical utility, in general, are not obtained when using weaker acids than those having a dissociation constant of 10-". It is, of course, necessary that the acid anion should not have a depressive action on the iron minerals as is the case with tannic acid and the like. Sulfuric acid gives as good results as any and because of its availability and relatively low cost is probably preferable in practical operation. It is, however, not superior to other strong acids in the quality of the results obtained andthe choice is based on the dictates of economics and not because .of the similarity of the sulfate anion to the sulfonate or sulfate groups on the promoter.

It is also an advantage of the present invention that it is not limited to any particular ore. The froth flotation process of the present invention produces excellent results with the more common iron minerals such as hematite and magnetite.

However, other iron minerals such as martite, limonite, siderite, goethite and the like which are commonly present in iron ores also may be suc- 3 cessfully floated by the procedure of the present invention. Taconite ores are amenable'to treatlow in iron for blast furnace feed and which cannot belbeneflciated readily by washing and sim-' ilar operations, but will also produce commercially acceptable concentrates from tailings rejected in ordinary beneflciating processes in common While commercially acceptable results may be obtained in many cases in the operation of the process of the present invention without the use c ntainin p n ipally not, containing about 13% Fe, was divided into a number of samples, and these were conditioned at about 67% solids with theflotation reagents, diluted to' about 21-22% solids and subjected to froth flotation in a Fagergren flotation machine. The rougher concentrate was subjected to a .cleaner flotationwithout the use of additional flotation reagents. As a promoter, oleic acid and sulfonated oleic acid were used in different tests. Various amounts of oiling agent and sulfuric acid were used. The results are shown in Table I.

Table I Concentrate Promoter Lbs./Ton Used Percent Rgh. Tslling Fatty Acid Sulfuric Percent Acid, Promoter 1 3 5 3 5 Assay Distrib. Iron pH Parts Assay 'lype Parts 100 None 1. 8i None None 39. 6B 87 6. 9 100 None 1.81 1. 59 None No Promotion 100 None 1. 8i 1. 69 2. 50 No Prom otion 100 NOD 1. 81 N one 2. 50 37- 00 55. 48 0. 35 6. 9

100 '25 1.04 r 1.50 6.00 51.28 sass 0.98 as 100 '25 0. 97 None None 15. 75 72. 58- 10. 74 6. 9 100 1.94 None 5. 00 45.28 60. 25 4. 64 5.9 100 25 1. 94 1. 59 None 44. 2o 74. 68 3. 2. 8

100 20 1. 92 1. 59 4. 00 56. 41 95. H 0. 51 2.6 100 20 1. 92 None 4. 00 54. 84 83. 90 2. 32 5. 7 100 Z) 1. 92 1. 59 N01!!! 52. 75 75. 95 2. 59 1 2. 5

100 10 1. 73 1. 59 4. 00 59. 83 87. 24 1. 22 2. 7 100 10 1. 73 None 4. (X) 52. 50 88. 59 1. 47 6. 7

100 5 3. 54 1. 59 None 00. a0 55. 13 3. 79 2. 7 100 5 5. 90 1. 59 1; 00 69. 58 79. 01 1. 83 2. 5

100 34. s 1. 7s 1. so 4. 00 59. 46 93.18 0. 85 2.0

1 Prepared by the usual commercial procedure. Had been neutralized to methyl orange with NaOH after sulfonation. All other sulionates were acidic (not neutralized) when added to conditioner.

of an accessory oiling agent, in most cases a definite improvement in both recovery and grade is obtained when one is used. Preferably, therefore. an oiling agent such as an unsulfonated oil is used. These oils may be either unsaponiflable mineral oils or hydrocarbons or saponifiablei organic oils of the fatty-acid glyceride type; In

some cases the sulfonated reagent itself may have sufficiently oily characteristics or may contain a sufficient amount of oil as a diluent therewith so that the use of additional oiling agents may be unnecessary. Such cases, however, are ordinarily the exception rather than the rule, and require higher amounts of promoter. Since in most cases the promoter is more expensive than an oil, such use ordinarily'is not to be preferred. The process of the present invention behaves normally with respect to slimes in the ore. Like many common anionic flotations a small amount of slime can be tolerated but increasing amounts generally produce corresponding decreases in the grade of the concentrate and increases in. the amount of reagents required. It is therefore desirable to deslime the feed fairly thoroughly although the extreme degree of desliming essential with many cationic flotations is unnecessary.

The invention will be described in greater detail in connection with the following examples which are meant to be illustrative only and not by way of limitation. All parts are byweight unless otherwise noted.

Exsuru: 1

A low-grade, Minnesota iron ore washer reject,

From the above results, it can be seen that an unsulfonated fatty acid such as oleic does not produce satisfactory results, even when making use of fuel oil in an acid circuit. Similarly, the second four tests, in which any residual sulfonating acid was neutralized before use, show that the presence of H+ ions in the circuit is essential ExAuPLz 2 In order to show the similar results which are obtained on varying the sulfonated organic acid, the following procedure was carried out. A number of samples of the same ore treated in Example 1 were given the same preliminary preparation and subjected to froth flotation using as reagents various sulfonated organic acids, alone, with H2804, with fuel oil, and with both H2804 and fuel oil. In the last four tests, additional samples of a low grade Mesabi iron ore containing about 17% iron and containing principally hematite and quartz were subjected to the same procedure. sulfuric acid used in sulfonating the fatty-acid are shown in the following table along with the hematite. limo'nite me quartz and assaying. about 15% Fe was deslimed' by hydraulic classification. The deslimed prod- The proportions of fatty acid and the ore used was a reject from an iron beneficial.- ing plant, contained principally hematite and metallurgical results. The sulfonatingacid used was 95.5% H2804.

Table 2 Promoter Lbs./Ton Used rfi igh Rgh. 'Iailing Fatty Acid 3 uliuric Percent Acid, Promoter Sulfuric Fuel Assay Distrib. Iron pH Pam Acid on Am Typo Parts y Dehgdrated 111011101010 A0111- 100 20 3. 77 1. 59 1. 51 58. 36 84. Q1 2. 20 2. 6 20 3. 77 1. 59 NOHB 57. 03 79. 04 2. 69 .2. 6 DO--- 20 3. 77 None 1. 57. 65 80. 10 2. 81 4. 1 3. 77 N0119 None 34. 19 91. 68 1. 47 6. 2 20 3. 77 1 N028 N 0110 42. 49 68. 5. 34 8. 5 20 3. 72 1. 59 3. 00 59. 85 88. 71 1. 16 Z. 6 20 3. 72 1. 59 NOllB 46. 11 82. 27 2. 2O 2. 6 20 3. 72 None NODB 29. 31 90. 41 1. 71 4. 8 20 5.16 1. 3. 00 56. 98 92. 53 0. 67 2. 5 20 5. 16 NOIIQ 3. O0 55. O9 87. 87 1. 62 4.. 7 15 5. 77 1. 59 1. 00 59. 73 90. 41 0. 92 2. 6 15 5. 77 1. 59 None 55. 51 84. 01 1. 71 2. 6 15 5. 77 None 1.00 57.16 91.17 1.34 4.0 15 5. 77 None None 48. 49 90. 11 '1. 34 3.8 SS-dll 1. 06 1. 59 4. 50 58. 02 85. 82 1. 83 2. B SB-dll 1. U6 1. 59 None 23. 45 19. 02 12. 21 2. 6 SS-dll 1. 06 None 4. 5O 42. 93 26. 55 10. 26 7. 0 SS-du 1. 06 NOIIB None 19. 60 14. 84 12. 58 7. G

40 ,1. 62 1. 62 3. 23 55. 23 90. 67 1. 19 Z. 7 40 1. 62 1. 62 None 48. 36 61. 28 5. U7 2. 6 40 1. 62 None 3. 35. 83 92. 62 1. 43 5. 8 40 l. 62 None None 30. 93 87. 38 2. 15 6. 4 53 2. 24 2. 24 2. 47 58. 10 93. 84 0. 94 2. 7 53 2. 24 2. 24 None 47. 05 89. 31 2. 02 2. 7 53 2. 24 None 2. 47 30. 73 95. 55 0. 94 53 2. 24 None None 23. 59 96. 05 1. 82 6. 6

0.8 lb./ton NaOH added to conditioner.

The results show that the process is not particuquartz, and assayed only about 14.5% Fe. The larly critical as to the nature of the fatty acid results, which further show the wide variety of which is sulfonated to form the promoter or as tcthe degree of sulfonation but that an acid circuit is necessary to obtain satisfactory results.

fatty acids which may .be sulfonated and used according to the process of the present invention, are shown in Table 3.

Table 3 Promoter Fatty Acid Lbs/Ton Used a Per Rgh. Tailing Ohlctogg 81111311110 7 Parts 8c Per Cent Type Parts Parts igg 2255 3 5 Assay Drstnb. AIron pH ssay Fish Liver Oil Fatty Acids 100 60 None 1. 76 4.68 9. 47.93 61.89 4.19 2. 8 Boys. Fatty Acids 100 None 1. 76 2. 34 4. 70 57.92 92. 50 1.62 2. 7 N aphthenic Acids 100 None 67 5.88 v2. 34 2. 34 59. 81- 44. 51 11.11 2. 4 Palm Kernel Oil Fatty Acuis. 100 None 50 6. 88 2. 34 2. 34 59. 40 57.70 9. 05 2. 5 100 None 50 11. 76 2. 34 4. 70 58. 73 48. 96 11. 34 2. 4 100 None 100 5. 88 2. 34 4. 70 54. 27 41. 76 11.21 '2. 5 100 N one 50 5.88 2. 34 4.70 59.00 69. 58 5. 94 r 2. 6 100 50 None 1. 76 2. 34 4. 70 59. 81 84. 40 3.65 100 58 1 None 1. 76 2. 34 4. 70 59. 67 84. 82 3. 51 2. 4 Dehydrated Castor O 100 50 None 1.76 2. 34 4. 70 57. 51 93. 41 1.49 Nee-Fat 3R, 59.0% Linoleic, 39 v (Armour & Co.) 100 50 None 1. 76 2. 34 4. 70 49. 82 78. 74 2.16 2. 7

Roleic"-Mixed Vegetable i (W. 0. Hardesty & Co.) 100 None 2.08 3.12 4.16 56.18 73. 99 4. 13 2.6 Animal Fatty Acids (W. O. Hardesty 6: Co.) 100 None 67 2.08 3. 12 4.16 57.35 84. 24 2.22 2. 4 Synthetic Fatty Acids (Standard Oil Develo ment Co. v 100 None 67 5.20 3.12 4.16 58.30 70.14 4.56 2.3 Crude Synthetic Fatty Acids (Standard 11 Development Co. 100 None 67 5.20 3.12 4.16 57.24 80. 72 2. 76 2.3 Palm Kernel Oil Fatty Acids. 100 None 100 10. 40 2. 08 4. 16 57. 24 82. 51 2. 76 2. 2 N aphthenic Acids 100 None 67 10- 40 2.08 4.16 56. 60 85. 16 2. 12 2.4 Flashing Grease-50% Fatty Acids Glue by- Product-F. W. Tunnel & Co 100 None 67 2.0 3.0 4.0 59. 35 76. 84 2. 76 2.6

EXAMPLE 3 EXAMPLE 4 A number of additional types of fatty acid, sulfonated with 95.5% sulfuric acid or with chlorosulfonic acid, were used in carrying out the same procedural steps of Example 1. In the first eleven tests a Minnesota ore washer reject conthe last seven tests of Example 3, was subjected taining mainly hematite and quartz and assaying to the same procedural steps as in Example 1 about 25% Fe was used. In the last seven tests 75 but a number of diiferent metallic and organic difference whether the sulfonated fatty acid reagent is fed per se or as a metallic or organic salt thereof, a number of samples of the ore used in In order to show that it makes little practical salts of various sulfonated fatty acids were used as the'promoter. These salts were prepared by adding an inorganic salt of a metal or an organic base to an aqueous solution of the sulfonated fatty acid and collecting the resultant precipitate by filtration, or decantation. The results of these tests, as shown in Table 4, clearly demonstrate that wholly acceptable results are obtained by feeding the sulfonated fatty acid as a salt thereof.

10 structures, produce good reagents after sulfona- Table 4 1 I Concentrate R her Promoter Used Lbs/Ton Percent F6 T I Parts, Parts Lb s A888? Added As- Fat Sulfuric Fm Assa Distrib. rcent B Mm Per Ton Acid on Y P Calcium Salt of Sulionated Oleic Acid-precipitated with 080]] 100 1. 81 8. 24 5. 00 57. 69 74. 76 3. 50 2. B Ferric Sulfo-oleate-precipitated with Fe0l;.'. 100 25 2. 76 2. 70 6. 18 44. 84. 41 1. 89 2. 7 Aluminum Sulfo-oleate--precipitated with AlCl: 100 25 2. 16 3. 24 5. 47 55. 00 88. 82 1. 69 2. 6

Sulionated Soya Fatty Acids-neutralimd with monoethanolamine 100 60 2. 16 2. 70 6. 23 52. 71 89. 04 l. 69 2. 1 Sulionated Fish Liver Oil Fatty Acids-neutralized with Guanidlne Carbonate 100 50 1.80 2. 70 3.80 45. 02 85. 53 1.35 Ammonium Sulfo-Ricinoleate Beacon 00., Boston,

Mesa... 1. 71 2. 63 2. 55 53. 06 86. 71 1. 88 2. 8

EXAMPLE 5 Table 5 Sulfonated promoter, lbs/ton 7.00 Sulfuric acid, lbs/ton 2.33 Fuel oil, lbs/ton 7.00 Concentrate, assay, percent Fe 60.53 Concentrate, distrib., percent Fe 77.45 Rgh. tailing, assay, percent Fe 4.58 Rgh. tailing, pH 2.3

From the preceding examples, it is apparent that a wide variety of fatty acids may be, sulfonated to form promoting reagents suitable for use in the present process. These acids in general should contain 11 or more carbon atoms in order to obtain the best results, since, otherwise, the fatty acid group on the reagent is not sumciently non-polar to obtain best results in the acid circuit. These fatty acids may be straight chain aliphatics such as undecylenic, oleic, lauric,

tion. There is no necessity for using single purified acids, as evidenced by the successful results obtained with such mixtures as fish oil fatty acids, fish liver oil fatty acids, coconut oil fatty acids; soybean fatty acids, cottonseed oil acids, palm oil fatty acids, and the like, as well as the commercial fatty acid mixtures. High grade mixtures such as "Nee-Fat 3R containing oleic and linoleic acids give good results also. However, it is not necessary that the mixtures be pure as is shown by the successful results obtained with the commercially-obtainable Roleic acid, which is a mixture of different vegetable oil fatty acids, and with mixtures of animal fatty acids, crude synthetic fatty acids, and fleshing grease such as is obtained in the leather trade and which contains about 50% of mixed fatty acids.

- Exaurnz 6 In order to show the effect of the use of various oiling agents and acids of different dissociation constants, the procedure of Example 1 was repeated .on a. number of samples of ore using 'various oiling agents and various acids to produce the necessary H+ ion concentration. In the first eight tests the ore used is the same as that used in the first part of Example 3. In the remaining testsa low grade Mesabiiron ore, the same as used in Example 4, was employed. It contained chiefly hematite and quartz and assayed about 14.5% Fe; The results are shown in Table 6.

Table 6 Promoter Acid Used Addition Agent $3 Rough Fatty Acid Sulfuric Lbs./Ton i l i Acid, Promoter Type Lbs./Ton Type Lbs/Ton Assay Distrib. Type Parts Parts Used Fiihfloil Fatty 100 50 1.76 Nitric 4.70 'Talloel 4. 70 57. 38 79. 54 2. 7 in. 100 to 1.76 Sulfurous--- an Coconut on 4.10 59.13 as. so 4. a Do 100 50 1. 76 Hydrochloric 2. 84 Chlorinated Kero- 4. 70 51. 03 80. 45 2. g

sene. Do 100 50 1. 76 Sulfamlc---- I. 34 Fuel Oil N0. 2 4. 70 55. 22 94. 20 3. 2 Boys Fatty Acids- 100 1. 76 Formic. 2. 34 M ila tglilyl I Ester of 4. 54. 00 86. 74 3. 4

Do 100 60 l. 76 Citric 2.34 Crude Oil 4. 70 48. 20 90. 05 3. 8 Do 100 50 1. 76 Sulfuric 2.34 Bunker 0 Fuel 011., 4. 70 49. 83. 00 2. 3 Fiiheidgil Fatty 50 1. 76 Acetic 2.34 Cottonseed Oil 4. 70 51.03 80. 57 4. 0

They need not be satu- I Table 6-Continued Promoter Acid Used Addition Agent fififif' r ml iough 1" Add scrum, LbsJTon a n Acid, Promoter Type Liza/Ton Type Lbs'J'lon Assay Distrib.

Type Parts Used 100 60 1. 67 Hydrofluorlc 2. 40 Fuel Oil No. 2- 4. 17 58. 32 80. 98 3. 2 100 60 1. 57 Phosphoric 2.09 Fish Oil 1 8.34 57.65 82. 12 2.9 100 60 1. 57 Citric 2. 09 Fuel 011 No. 2 4. 17 55.89 66. 71 3.8 100 60 1.57 2.09 do 4.17 53.87 72.86 3.4 100 60 1. 57 5.10 do 4. 17 15.50 90. 60 6.9 100 60 1. 67 Saturated- .d 4.17 16. 72 85. 70 6. 100 25 l. 79 2. 68 Naghthenlc Acid--- 6. 90 62. 71 72. 2. 7 100 l. 79 2.68 Et lone Glycol 6.68 56.35. 68.50

. ono-oleate.

.100 25- 1. 79 3. 22 Sagonifled T81l061 4. 58 50. 16 66. 27 2. 7 100 25 1. 79 2. 68 neptaldehyde.. 6.60 47. 58 67. 100 25 2. 09 2. 68 Lauryl Mercaptan. 8. 14 68. 10 69. 97 100 25 2.09 2. 68 22 B. Fuel Oil--- 6. 62.03 93. 14 2.7

cessory reagents.

From the results it will be seen that carbonic acid which has a dissociation constant of approximately 10- is about the weakest acid that can be used, boric acid not giving any appreciable beneficiation.

It will be further noted that a wide variety of accessory reagents having oily characteristics were used in conjunction with the sulfonated fatty acids. Excellent results were obtained with hydrocarbon oils such as kerosene, fuel oil, crude oil, and halogenated hydrocarbons such as chlorinated kerosene. Various saponiflable. oils of the glyceride type including coconut oil,fish oils, cottonseed oil and the like are wholly satisfactory. Similarly fatty acids, or derivatives thereof which yield acidsdn the circuit, such as talloel, oleic acid, and the soaps thereof may be used. Various organics showing oily characteristics may be used. Naturally, the hydrocarbons, saponifiable oils or fatty acids because of their availability and relatively low cost are preferable as the ac- EXAMPLE 7 In order to show the utility of acid salts rather than acids perse, the procedure of Example 2 1.57 lbs/ton of sulfonated soyabean fatty acids, sulfonated with 60 parts per of 95.5% H2804; was used and fuel oil No. 2 in the amount of 4.17 lbs. per ton was used as an oiling agent. Illustrative results are shown in Table '7.

should be a constituent of an acid having a dissociation constant greater than 10"". The acid salt should be usedin sufllcient quantity o Provide the necessary pH.

The effect of desliming was demonstrated by repeating the procedure of Example 1 on low 1 grade Mesabi iron ore. tailing but varying the 40 degree of deslirning. The ore used contained about 14.57% iron, chiefly as hematite, in a, gangue of principally quartz. In the first test, the ore was essentially deslimed, in the next test only partly deslimed, and in the last, test no deslimlng was employed. As a promoter sulfonated oleic acid was used, which had been sulfonated with 25 parts per 100 of 95.5% sulfuricacid, followed by neutralization to methylorange by caustic soda. The results, which show the effective reagent savings which can be obtained by deslim- I 1 ing, are shown inTable 8.

Table 8 Assay Consumption, Lbs./Ton Percent Percent Product wt. Distrib. V

x f'fif mso. Promoter Fuel 011 Essentially Deslimed:

Cale. Head 100.00 11.44 100.00

Obviously, the salts used must be strongly ExmmQ acidic and. as noted above, must not have a deleterious action on the flotation of iron minerals. In order to provide suflicient acidity, the anion In order to demonstrate the effect of scrubbing, the procedure used in the first test of Example 8 was repeated except that after desliming the ore peated on a number of ore samples using as pro- H2804, 1.12 lbs/ton of neutralized sulfonated 5 oleic acid and 2.64 lbs/ton of 22 B. fuel oil.

meters 9. number of diflerent sulfonated products in combination with a sulfonated fatty acid. Illustrative results are shown in Table 11. The ore was the same as that used in the last four tests of Example 2.

Table 11 7 Concentrate Ro her Promoters Lbs'lTon Percent Fe '1 g L135. Per

on Assay Composition 1 2 5 6 8 Assay Distrlb. Pei- Cent pH 1 Part oil-soluble troleum sullonate (Petronate-L. Sonnebom 6: Sons) 1 Part suli'onateifgleie acid (treated with 25% by weight concentrated sul- 1. 80 2. 33 4.10 so, 35 9g 1 74 2' 9 furic acid and neutralized after sulionatlon) 1 Part water-soluble petroleum sulfonate (SP-702-Stanco Distrlb Inc.)- 1 63 2 33 4 61 5g 87 95 58 o 8 2 9 1 Part suli'onated oleic acid (as above) 1 Part sulfonated talloel (treated with 50% by weight concentrated sulfuric I acid) 63 2.33 3. 59 60. 93 91, 31 1 55 2. 7 1 Part sulionated oleic acid (as above) d The concentrate was cleaned twice. without ad i E Pm 12 tional reagents. The results obtained are shown in Table 9.

Table 9 Assay Percent gergelit Product Weight Percent Percent s r v Fe Insol. of Iron Cale. Head 100.00 14. 56 100. 00 Prim. Slime.. 6. 27 20. 49 8. 83 Sec. Slime. 2. 71 19.28 3. 59 Clean. Cone. 21. 85 62. 84 79. 55 2nd Cl. Tail- 4. 79 4.04 1.3.5 1st 01. Tail 8. 82 1. 21 0. 74 Rgh. Tail 55.56 1.62 6.18

' ample 8. The reagents used were 2.73 lbs./ton of H2804, 2.12 lbs/ton of neutralized sulfonated oleic acid and 5.76 lbs/ton of 22 B. fuel oil. The rougher concentrate was cleaned once in the first test and twice in the second test. The results show the definite advantage of conditioning at high solids.

Table 00 ee trate Per Pulp Density, Per Cent lei i t Fe Solids Assay Assay Dlstrib. Per oent pH Conditioning Flotation Emma 11 In order to show that the sulfonated fatty acids may be used in conjunction with other sulfonated materials, the procedure of Example 1 was re- A Minnesota iron ore, a washer overflow containing mainly hematite and quartz, portions of which were locked, and assaying about 15% Fe, was deslimed, conditioned at about 65% solids with 1.57 lbs. of sulfonated soya fatty acids (100 parts fatty acid: 60 parts 95.5% H2804), 4.0 lbs/ton fuel oil No. 2, and 2.09 lbs/ton sulfuric acid, and floated in a Fagergren flotation machine. The resulting rougher concentrate contained about 34% of the flotation feed by weight and assayed 33.8% Fe and about 49% insoluble. The flotation tailing, about 66% by weight, as sayed 2.43% Fe.

m This concentrate was conditioned with 2.0

lbs/ton of lime and 2.0 lbs/ton of quebracho and then was deslimed using 2.0 lbs/ton of sodium silicate. The deslimed product was conditioned with 0.08 lb./ton of a higher alcohol frother, B23, and with 0.05 lb./ ton of a cationic-type reagent, lauryl amine hydrochloride. and then floated. for 1 minute to remove the silica. This treatment was followed by two stage-additions of 0.05 lb./ ton of lauryl amine hydrochloride, conditioning and flotation for the-further removal of silica. This treatment produced an iron product (i. e. flotation tailing) assaying 57.51% Fe, and representing a recovery of 50.55% of the iron. Further cleaning of the silica concentrate, using additional 0.027 lb./ton B 23 and 0.02 lb./ton lauryl amine hydrochloride, gave a middling product containing 15.41% of the iron and assaying 34.70% Fe.

EXAMPLE 13 In order to show the applicability of the present process to different types of iron ore, in addition to those used in the preceding examples, a number of various ores were ground to flotation size, ifnecessary, and then were subjected to a procedure similar to that of Example '1. The rougher concentrates were cleaned once in all except the last test where two cleanings were employed. The results are shown in the following table. It will be noted that acceptable results were readily obtained from a. number of types of products or ores which contained a wide variety of iron minerals.

Table 12 Promoter Used Lbs/Ton Feed Concentrate, Per

my Cent Fe Rougher Fatty Acid Parts sul Type oi Ore For 091'"; Telling,

Sulfuric Per furic fi Fe pH Type Parts Am Assay Distrib.

Oleic Acid 100 2. 44 2. 73 6.10 A washer tailing containing 30. 43 58. 91 95. 88 2. 75

. mainly hematite, limonite V and quartz. Ammonium Sulioricinoleate 2. 50 2. 76 4. 07 A table concentrate contain- 64. 44 68. 34 95.92 3. 3

(Beacon 00., Boston, lng ch1eflymagnet1te,-marass). tite and quartz. Soya Fatty Acids 100 50 1. 75 2.06 3. 62 An ore containing martite, I 22. 07 61.33 96. 42 2. 7

magnetite and hematite Fish Liver Oil Fatty Acids. 100 50 2. l8 2. 73 2. 84 A tacomte containing prin- 21. 47 54. 73 95. 62 2. 65 cipaly hematite and quar z. Soya Fatty Acids 100 50 2.00 2. 50 5. 06 An ore containing goethite, 15.85 51.30 92. 61 2. 6

siderite and hematite.

In the claims, the term oxidized iron ores is used in its commonly accepted meaning to include not only iron oxide ores such as those containing magnetite, hematite, etc., but also hydroxides, carbonates, etc.

We claim:

1. A method of beneflciating oxidized iron ores by froth flotation which comprises subjecting the ore to froth flotation in the presence of an effective amount of a, collector consisting essentially of a sulfonated aliphatic fatty acid selected from the group consisting of the aliphatic fatty-acids having at least eleven carbon atoms and mixtures of such acids, only. and an amount of an acid substance the anion of which is a constituentof an acid having a dissociation constant greater than 10- effective to produce in the flotation tailing a pH of from 2 to 6, whereby a concentrate relatively rich in iron mineral and a tailing relatively poor in iron is obtained.

2. A method according to claim 1 in which thesulfonated fatty acid reagent is associated with at least one oiling agent selected from the group consisting of unsulfonated saponiflable oils, unsulfonated hydrocarbon oils and unsulfonated fatty acids.

3. A method according to claim 1 in which the collecting reagent is a. sulfonated oleic acid.

4. A method according to claim 1 inwhich the collecting reagent is a sulfonated fish oil fatty tures of such acids, only, and an amount of an acid substance, the anion of which is a constituent of an acid having a dissociation constant greater than 10" effective to produce in the flotation tailing a pH of from 2 to 6, diluting the conditioned ore to flotation density and subjecting it to froth flotation, whereby a concentrate relatively rich in iron mineral and a tailing relatively poor in iron is obtained.

'7. A method of beneflciating oxidized iron ores by froth flotation which comprises subjecting the ore to froth flotation in the presence of an effective amount of a reagent consisting essentially of a sulfonated acid selected from the group consistingof the aliphatic fatty-acids having at least eleven carbon atoms and mixtures of such acids, only, and an amount of sulfuric acid effective to produce in the flotation tailing a pH of from 2 to 6, whereby a concentrate relatively rich in iron mineral and a tailing relatively poor in iron are produced.

ROBERT B. BOOTH. EARL C. HERKENHOFF.

REFERENCES CITED The following referenices are of record in the file of this patent:

Y UNITED STATES PATENTS acid Number Name I Date 2,120,217 Harris June 7, 1938 5. A method according to claim 1 in which the 2,126,292 Tartaron 9 1933 collecting reagent is a sulfonated soya bean oil 2,235,394 Coke June 9, 1942 fatty acid- 1 2,331,722 Patel: Oct. 12, 1943 6. A method of beneficiating oxidized iron ores 2 385 054 Booth Sept 13, 1 by froth flotation which comprises conditioning the ore at high solids with a reagent consisting essentially of a sulfonated acid selected from the group consisting of the aliphatic fatty-acids having at least eleven carbon atoms and mix- OTHER REFERENCES Flotative Properties of Hematite in Milling Methods, 1939, pages 104, 105, 106, 108, 110, 111 and 116.

Certificate of Correction Patent No. 2,475,581 July 12, 1949 ROBERT B. BOOTH ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Columns 7 ends, Table 4, eighth column thereof, for 85.53 read 8.9.58; 001- umns ,9 and 10, Table 8, eighth column, for 5.82 read 5.28;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 7th day of February, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commission r of Patents.