US2387856A - Recovery of ilmenite by a two-stage flotation process - Google Patents

Description

Oct. 30, 1945.

R. A. PICKENS 2,387,856

RECOVERY OF ILMENITE BY TWO STAGE FLOTATION PROCESSES FPGTHFA? -Filed May 26, 1942 2 Sheets-Sheet 1 CFI/.57459 ORE' R. A. PlKr-:Ns 2,387,856

Oct. 30, 1945.

RECOVERY OF ILMENITE BY TWO lSTAGE FLOTATION PROCESSES 2 Sheets-Sheetl 2 Filed May 26. 1942 Cil/JHK@ OAE PPOOl/C o ffl'fZ/'Mf/VT I Arran/wry.

Patented ct. 30, 1945 RECOVERY oF ILMENITE BY A TWosTAGE FLOTATION PROCESS Roy Alderson Pickens, Stamford, Conn., assgnor to American Cyanamid Company, New York, N. Y., a corporation of Maine Application May 26, 1942, Serial No. 444,500.

3 Claims.

This invention relates to froth flotation of ores particularly to the beneiiciation of ilmenite ores by a two stage flotation process. l

In commercial practice the use of titanium has become more and more important and accord,- ingly the demand for a high grade ore from which it may be recovered has steadily increased. To carry out a satisfactory recovery it' is necessary to have an ore or a concentrate containing `at least`50% of a titanium bearing mineral such as ilmenite, rutile and the like. While there are many deposits of titanium ores States, the grade in most .cases is not sufficiently high to make the recovery of titanium economi cally feasible. As a consequence, in the past a large proportion of the titanium used was obtained from imported ores.

In order to make use of the domestic ores, it has been proposed notation to produce grade for further processing.r been madeto float the ilmenite impurities by the use of anionic a concentrate of satisfactory Attempts have away from the reagents such as oleic acid, sodium oleate, tailoel, talloel soap,

iish oil, fatty acids. anionic-type wetting agents and the like. It was found, however, that successful concentrationv to the desired grade required an initial ore of fairly high grade'and extremely careful control of both the amount of reagent used and the flotation conditions. If any of these factors were allowed to'vary from rather exacting requirements an unsatisfactory separation was obtained. As a result, the anionic notation was neither particularly useful nor desirableon a commercial scale furthe beneciation of many naturally-occurring ores.

Attempts have also been made to oatthe impurities such as talc, chl-orite and other silicate-` bearing materials which usually comprise the -undesirable portions 'of low grade 'native ores away from the ilmenite by the use of a cationic reagent. When using a cationic-type of reagent alone it was foundthat with fairly high grade ore as the initial starting material a satisfactory concentration could be obtained, although often at the expense of good recovery. However, the concentrate so produced was in a wholly unsatisfactory physical condition since it could be neither readily ltered nor dried without resorting to equipment and a degree of care in their use which would render the process commercially undesirable.

Most of the lower grade ilmenite ores which require beneficiation in order to produce a marketable product, fall within one of three classes.

to beneficiate them by froth:

in the United The rst of these comprises those ores of a sumciently high initial grade so that a marketable grade can loe-obtained in a single step dotation either by floating the silicate-bearing materials away from the'ilmenite ores or alternatively iloatl ing the ilmenite away from the gangue with an anionic reagent. The present invention is not concernedwith cresci' this high an initial grade.

The second of these classes comprises those part of the linished product ores which permit a to be produced as tailings from a rougher silicate flotation and the remainder must be obtained by a retreatment of the rougher silicate concentrate. Ores of this type will be referred to in the succeeding portions of the present specication as easily-beneciated ores.

The third of these classes comprises those ores which in order to produce a marketable grade require further treatment of both the rougher silicate tail and the rougher silicate concentrate. Ores of this type will be referred to throughout the specification as dilicultly beneiiciated ores.

According to the present invention it is possible to produce concentrates which are of satisfactorily high grade with a good recovery and also have the concentrate in suchI physical condition that it can be readily ltered and dried. This is accomplished in general by the use'of a two-stage flotation process in which a portion of the silicates and silica are removed by iiotation with a cationic type of reagent after which lthe ilmenite is concentrated by flotation with an anionic type of reagent.

The invention is most readily set forth in connection with the accompanying drawings in which: l

Figure 1 is a iiow sheet showing the procedure used with an ore which ls relatively free from dicultly-separable, undesirable portions; and

Figure'2 is a ow sheet of the -procedure used with an ore containing a fairly large amount of impurities which can be removed only with great diiiculty.

In connection with both Figures 1 and 2, it may*i be noted that the present process is considered Also in both figures it win be noted that the f first otation stage is a silicate rougher `lieta-- tion using a cationic reagent. Since the, cationic reagents are extremely sensitive to the presence of slimes, even small amounts of the latter seriously impairing the efficiency of the reagent, it is necessary to remove as'large a proportion of the slimes as practicable before this first flotation step. If desired, a preliminary desliming may be carried out on thel ore after it has been crushed and before ne grinding although it is unnecessary to do so in all cases.

In preparing the ore for desliming, a procedurewhich produces good results is to wet grind the previously crushed ore with a sufficient amount of an alkaline material such as caustic soda or soda ash to maintain the liquid in the grinding apparatus at a basic pH. The grinding may be carried out in any desired form of apparatus. Good results may be obtained using almostany commercial form of rod or ball mill. In some instances I have found that it is desirable to grind the material until about 1% is retained on a 65 mesh screen and 48-50% will pass a 200, mesh screen, although the process need not be limited to this degree of grinding. Excessive grinding should be avoided since it tends to increase the amount of titanium mineral removed with the slimes and thereby lost.

The ground ore is then subjected to a desliming procedure. Again the type of apparatus used is immaterial and the operation may be carried out for example either by hydraulic classification or by means of a series of wet screens. Hy-

draulic classification is probably the quickest and easiest means and therefore, is perhaps preferable. The desliming, as was set forth above, should be carried out to the greatest extent that is feasible under the existing conditions since the l morer complete Ythe deslirning the more efiicient will be the action of the cationic reagent used in the rst flotation step.

After desliming, as will be noted in both Figures 1 and 2, the sands are passed to a flotation machine or a battery of notation machines which may be of any desired type such as the well known Fagergren flotation machine. In some cases it has been found advisable in connection with the silicate' rougher flotation to condition the pulp for a few seconds before adding the reagents, in this case a frother and a promoter of the cationic type. g

An advantage ofthe present invention is that neither stage is, limited to any particular re-v agents. any desired frothers and any desired cationic or `anionic type promoters being satisfac-y tory in the first and second stages respectively. For example, well-known frothers such as pine oil, cresylic acids and a mixture of higher alcohols known to the trade as i3-23," comprising principally C1 and Ce, have been found to' produce excellent results. In the first stage,.any desired cationic type of flotation reagent such 'for example as the quaternary ammonium reagents, th higher aliphatic amines or their salts` and the reaction products of polyamines with higher aliphatic carboxylic acids may be used. All produce ysatisfactory 4results when used according to the process of the present invention.

With different ores, different cationic reagents may show slightly-superior results. However, it is an advantage of the present invention that this factor need not be considered. If only the cationic float were to be used, great care would necessarily be employed in selecting the optimum amounts of the best agent. But since this is not true of the present process in which the cationic `whole ilmenite notation notation is in effect a preliminary treatment, this degree of care is not necessary. Any available reagent may be used so that the cheapest is the most preferable. At the Sametime, the minimum amount of reagent may be used. Since these reagents are fairly expensive, this feature of the invention is of considerable importance.

Referring to Figure 1, delineating the procedure suitable for easily concentrated ores, the silicate concentrate from the silicate rougher fiotation is subjected to a cleaning flotation and if so desired to one or more recleaner silicate ilotation operations. Since the cleaned silicate concentrates 'are usually relatively free from ilmenite, they may usually be 'discarded without appreciable loss. However, it is possible to recover at least a portion of any ilmenite retained in the recleaned silicate concentrate by regrinding and reclassifying it, discarding the overflow and returning the underflow to the silicate rough'- er flotation stage.

The tailings from the silicate rougher flotation with easily beneilciated ores of this type are usually of suiliciently high grade to constitute a finished product. With some few'ores the tailings from the silicate cleaner flotation may also be added directly tothe silicate rougher tail without causing the latter to fall below the desired grade. However, as previously pointed out, the present invention is not concerned with ores of that high an initial grade since thereby the is by-passed and the process of the present invention is not required in the beneilciation of such ores.

With ores of the type with which the present invention is concerned, however, the tailings from the several silicate cleaner notations are combined-and subjected to an ilmenite rougher flotation with a flotation reagent of the anionic type. Again the particular reagent used is not critical. Good `results may be obtained using such wellknown reagents for example, as oleic acid, coconut oil fatty acid, talloel, saponied fatty acids and saponied talloel, although the invention is not meant to be limited to these particular reagents since others ofa similar nature may be used. The tailings from the ilmenite rougher flotation itself may be discarded or if the ilmenite content is high enough to warrant further treatment, this material may be retreated by any of the concentrate is passed to one or more cleaning stages the nnal concentrate from which is the finished product andthe tailings from which may be discarded or may/ be combined and retreated by methods similar to that previously described for the treatment .of the rougher tailings. By this two-stage flotation procedure ores which otherwise could not be beneciated may be successfully used and ores' `of greatly varying grades may be fed to this process and still produce a product of satisfactory grade with a good recovery.

A further advantage with the two-stage notation procedure lies inthe fact that although in the case of easily treated 'ores only the initial silicate flotation step maybe necessary in order tion may not be in particularly good physical` state for subsequent dewatering and drying.I In such cases it may be advisable to reiloat this .portion along with the 'tailings from the silicate cleaner and recleaner stages in order to take advantage of the improvement in physical state made by the anionic otation.

This procedure will be illustrated by the following example which is meant to be merely illustrative and in no way limit the present invention. All parts are by weight.

EXAMPLE 1 1200 parts of a North Carolina ilrnenite ore were crushed to pass a mesh screen, diluted to about 67% solids, ground in a small rod mill for 13 minutes with 1.25 lbs/ton of caustic soda and then deslimed by decantation. The deslimed sands were diluted to 33% solids, conditioned for about l0 seconds with 0.1251b./ton of pine oil and 0.125 lb./ton of llioroly amine hydrochloride, a commercial product comprising principally lauryl amine hydrochloride and well-known to the trade as D. P.-243, and oated for 2 minutes in a Fagergren iiotation machine. The concentrate was given a cleaning and a recleaning oat of 2"minutes each with 0.02 lb./ton of Lorol aminehydrochloride. The rougher silicate tail was a iinished product and was not further treated. The cleaner and recleaner silicate tails were combined, diluted to .30 seconds with 0.12 lb./ton of oleic acid and floated for 4 minutes with l0.07 lb./ton of additional oleic acid. The ilrnenite rougher concentrate was given a cleaning and recleaning float of 2 minutes each, without reagents, and an addi tional recleaner float with 0.03 1b./ton of oleic acid. The results are shown in Table I;

Table I .d Assay f erccntA rt percent dist. T102 IiOz Feed 100. 00 42. 20 100. 00 slime (waste) 24. 43 22. 43 12. 9s- Sand (flotation feed). 75. 57 48. 59 87. 02 silicate rougher conc 52. 39 45.87 56. 94 silicate rougher tail 23. 18 54. 76 30.08 silicate recleaner conc. (waste) 7. 38 19. 75 3. 46 Combined silicate cleaner tails (ilrnenite rougher feed) 45. 0l 50. 15 53. 48 Ilmenite rougher conc. 39.81 52. 80 49. 80 Ilmemte rougher tail.. 5. 20 29. 87 3. 68 Ilmenite recleaner conc 33. 53. 97 42.65 Ilmenite recleaner tail (middlings) 6.46 46. 74 7. 15

Product combinations Silicate rougher taiH-ilmen ite recleaner conc 56. 53 54. 29 72. 73 Silicate rougher tail-i-ilmenite recleaner oonc.+iln1enite middlings- 62. 99 53. 52 79. 88

Figure 2 is a ow sheet which represents the procedure with an ore which contains a large proportion oi diftlcultly removable impurities such as weathered chlorite and certain forms of iron bearing minerals. The ore is prepared in the same way, by grinding and desliming and the same flotation reagents'are used as in the procedure outlined in Figure 1. With these diflicultly beneciated ores, the principal changes in procedure lie in the manner in which various concentrates are combined to make up the product and in the mannerf in which various tailings may be reworked. The silicate rougher concenL solids, conditioned for about 3 the rougher silicate oat instead of being a nished product are combined with the tailings from the recleaner stages and subjected to a rougher ilrnenite flotation with an anionic type of reagent. The tailings from the rougher ilrnenite oat are usually fairly high in titanium content and consequently may advantageously be retreated, although if the .titanium content is low they may be discarded. `The ilrnenite rougher concentrate lmay be of suiliciently high grade to be iinished product, although ores in which this is possible are seldom encountered. It is usually advantageous to subject the ilrnenite rougher concentrate to one or more cleaning stages, the concentrate from the nal stage of which forms the product. The combined tailings from the cleaner stages should ordinarily be recycled to the rougher ilrnenite oat to recover` part of their titanium content. However, if the tailings comprise a large amount of fine titanium ore ties, it may be well to regrind these tailings prior to further treatment.

This modification of the procedure will be illustrated by the following examples which are also .I meant to be merely illustrative and not by way of limitation. All parts are by weight.

EXAMPLE 2 l l -chlorethyloleate, a cationic type reagent. The

trate is passed to a cleaner silicate flotation and the concentrate therefrom subjected to one or silicate rougher concentrate was given a cleaning and recleaning iioat of 3 minutes each and the recleaned silicate concentrate discarded. The silicate rougher tail was combinedwith the tailings -from the cleaner and recleaner floats, diluted to about 30% solids, conditioned for 45 sec-` onds and oated for 2'1/2 minutes with 0.12 lb./ton oleic acid. The ilmenite once. The metallurgical results vare shown in Table II.

Table "II Assay Per cent Per gent per cent dist. W i0. Tio,

F ced 100. 00 43. 47 100. 00 Slime (waste) 20, 36 2l. 42 20. 04 Sand (flotation fee 79. 64 49.11 89. 96 Silicate reclean. conc 2.67 28. 25 1. 73 Silicate rough. teil4-combined silicate clean. tails (ilrnenite rougher v feed) 76. 97' 49. 83 88. 23 l'lmenite rough. tail.. 13. 39 39. 07 l2. 03 Ilmenlte clean. taiL.- 7. 23 46. 24 7. 69

Product I lmenite clean. conc 56. 35 52. S5 68. 51

EXAMPLE 3 ing 0.06` lb./ton of B-23 and 0.08 lb.`/ton of anA aliphatic amine hydrochloride, principally octadecyl amine and known tothe trade as Armour amine hydrochloride, in the cationic float and 0.7 lb./ton of oleic acid inthe anionic float. The

cleaner and recleaner silicate tails, however, were physically bound to impuri-v soda, ground in a rod mill for.

concentrate was cleaned not combined' with therougher silicate tail from the anionic oat but were discarded since they contained negligible quantities of titanium. The results are shown in Table 1212i.v

Table III 5 Assay Per een rekent per cent d T100 T10;

eed. 100. 00 43. 39 100.00 Slime (white) 2). 12 21. 64 10. 03 79. 88 4B. S7 8. W Silicate rough. conc 6. 13 14. 44 1. 71 Bilicate rough. tail (ilmenite rough.

leed) 74. 76 51.21 88. 26 Ilmenite rough. tail. 211.30 44. 42 m. 78 Ilmenite c1ean.'tail.. 5. 92 48. 29 0. 69

Product L Ilmenite clean. conc 48. 53 64. 44

Exmtn 4 20 The procedure of Example 3 was repeated using 0.06 lb./ton of pine oil and 0.10 lb./ton of Lorol amine hydrochloride in the cationic float and 1.0 lb./ton ofsaponifled talloel in the anionic float. The results are shown in Table IV.

Table IV Assay Per cent Per cent per cent st. Wt- Tio. 110, 3

Feed 100. 00 41. 70 100.00 Slime (waste) 20. 38 20. 42 9. 96 Sand (flotation feed) 79. 6g 47. 26 v 90.04 Silicete clean. conc. 14. l 29. 61 9. 99 S1l1catc comb tai 35 tion feed) 65. 52 51. 06 80. 05 Ilmenite rough. tail .v 5.81 34. 17 f 4. 75 Ilmenite clean. tail 3. 8l 50. 57- 4.61

Product A Ilmenite clean. conc 55.90 52.85 70.69 4() l EXAMPLE 5 Table V 50 Assay Percent Pevent percent dist. T10; T102 Feed 100.00 42. 100.00 55 d) 75. 35 49. 12 87. 41 Ilmenitc rough. tail 27. 57 46.93 30. 56 Ilmenitc clean. tail 5. 67 45. 6. 10 60 Product Ilmenite clean. conc. 42.11 51. 05 50. 75

EXAHPL: 6 -The procedure of Example 3 was repeated usine 0.35 lb./ton of trimethylcetyl ammonium bromide in the cationic float and 0.3 1b./ton of oleic acid in the anionic float. 'I'he results are shown in Table VI.

Table VI Asse Percent Rgent percent dist.

- T10, 'riosl 100.00 43.13 100.00 .ms @.42 L35 70. 02 4am 0.00 I 3.02 30.15 A 2.15 70.00 40. 00 sa 20 13.10 41.00 12. 51 Ilmenite clean. t0n s. sa 40. 0c 9. s4

Produc: 110100110 010010.00110 54.00 5210 eene I claim: 1. Aprocess of beneflciating low grade ilmenite ores to produce a beneciated ore adapted to ready filtration and drying and assaying at least 50% T10: which comprises subjecting the ore to a lrougher silicate flotation in the presence of an amount of a cationic-type collector effective to concentrate a major portion of the silicates but insufilcient to effect a maximum separation, whereby a concentrate rich in silicates and a tail rich in ilmenite are obtained, subjecting the rougher silicate concentrate to at least one silica cleaner notation and subjecting at least a part of the silicatevcleaner tailing to a rougher ilmenite flotation in the presence of .an anionic collector selected from the group consisting of the higher fatty acids, talloel and soaps thereof.

2. A method according to claim l in which the silicate rougher` flotation tailing and the silica cleaner tailing are, combined as feed to the ilmenite rougher flotation.

3. A process of beneiiciating low grade ilmenitc ores to produce a beneciated ore adapted to ready illtration and drying and assaying at least 50% TiOz which comprises grinding the lmenite ore in the presence of an alkaline material to a size suitable for froth flotation feed, desliming the ground 'ore in the presence of water, subject ing the deslimed ore to a rougher silicate flotation in the presence of an amount of a. cationictype collector effective to concentrate a major portion of the silicates but insuiiicient to eect a maximum separation, whereby a concentrate rich in silicates and a tail rich in ilmenite are obtained, subjecting the rougher silicate concentrate to at least one silica cleaner flotation and

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