US2607479A - Agglomerate tabling of tungsten bearing ores - Google Patents

Description

ug- 19, 1952 w. A. BATES AGGLOMERATE TABLING OF TUNGSTEN BEARING ORES 2 :SHEETS-SHEET l Filed Feb. 4, 1948 /A/Vf/VTOR William A. Bates Aug. 19, 1952 w. A. BATES n AGGLOMERATE TABLING OF TUNGSTEN BEARING ORES 2 svHEETs-SHEET 2 Filed Feb. 4, 1948 FEED IN WATER IN 24 DRIVING RIFFLES SECr/o/'I/ A-A L A PLA/v v/EW PIG2A SHAKING TABLE F I G. 2

D. O E E E 1N F w I 4:5 f/w K E R/\` //D T/mw A b Na WILAW/ er ma? o0 Hvmww/ s www vw E F. 52K MMM 7m D mm Cm M 4 /A .n R E m M m ,w T A A E W H H E S W. WA F FIG. B

WASH WATER FINE GANGUE STRATIFICATION BETWEEN RIFF'LES DISTRIBUTION OF SCHEELITE INAGGLOMERATE TABLING ON SHAKING TABLE F I G. 6

/NI/ENTOR William A, Baies FIG.

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ITTOR/VE'I/s Patented Aug. 19, 1952 Umso STATES PATENT' omai-z;

G'GLMT TABLING' oF TNGSTN BEARING ORES William A. Bates,l Berkeley, Calif., assignonto California, Research Corporation, SanrFran'- cisco, Calif., a corporation of Delaware This invention pertains" to a' process for beneciating tungsten-bearing minerals,v and more particularly to a froth `flotation process for beneciating scheelite. v

It is Well known that tungstenebearingniinerals, such as schee1ite, a re commonly found associated with otherminerals of metalliferousand non-metalliferous nature. Thus; a typiealscheelite-bearing orer may comprise' chalcopyrite and molybdenite, aswellas 'amiXedgangue of calcite, iluorite andthe like, 'and a considerableproportion of siliceous v co napolinds',A for example; quartz, garnet vand epidote. No diiiiculty is encountered inseparatingA simultaneously chalopyrite and molybdenite by froth flotation' from` s'ucl1 an ore. The Combined.ehalcbpifriimolybdnite consentrate is then readily retreatedf to yyield separate copper` and molybdenum concentrates by any method suitable for thei'lotatien ofw sulfiidev minerals. Then tailings W'hchjar'e vObtained .from `the notationy of combined; chalcopyrite-molybdenite concentrate contain scheelite;calcite,4 uorite and siliceous materials,

However, the recovery of s clfreelite fromthese tailings iS 110i Se satisaciery, and. .straightforward the above lentiened Separation, of cobperand I nolybde n1f.r'r1 l minerals from 'the [chaloopyritemolybdenite concentrate. As a: lmatter of' fact., theapplication' of' conventional froth notation With"` anioni: collectors such as soaps 4of 'fatty acida; for4 example; of tallol acids, f or the Tc-@Very Uf scheen-te lCSJl- '.nj. ein', unduly 10W erad' f'V theftuilesteefbearilie"concentrate (only g/bbylwghlfofwoh The. @Satisfaetory grade of the concentrate is causedloy4 very similar floatabilities of s clree11?3 1calcite andfluorite, all of which havea-eominon calcium ion and a similarchemicalconstitution; Calcite and 3 Claims. (01.269449) nuorite tenero noatwithschente, as' de some of thesiliceous constituents'jof the ore' pulp'g'and thus render-fthe produotionjpf high grade Itungsten-bearing` concentrates difficult andjeostly.

1 lt Sthe primary Object of the'present invention t0 rrovdea'process for the relcvry oftungstenbearing mineralsybylselective frotnotationnom concomitantmetalliferous and nonemetalliferous contamin ntsin improvedA yield' and substantially high concentration.

' It is a further object of Vthis' invfention togp'rovide aprocess for therecovery of tungstenbearing n iineralsA by selectiveifroth flotation thereofjfrom ore'svghich," in addition'td saltsof tungsten acids, comprise salts 0f other acids: with tion whichY enhances the vselectivity'of the ta'- tion process.

2 Y y An additional important object of the invention is rto provide avnevv process' for beneiicia'ting andv recovering tungsten-bearing minerals; which involves carrying out the flotation of said minerals -under controlledconditions of pl-lin order to insure selective flotation thereof from other components of theore pulp.

Still another particular object of the invention is4 to provide ajnevv and efficient process for the recoveryof high-grade tungsten-bearing minerals fro m metalliferous and nonmetalliferous contaminants thereof by selective froth notation and by lsubsequent tabling of thev floated tungsten agglomerate. f

A more4 specie object "of the present invention i'siarwovde apresfsffrthe rovery Qf. highlgrade scheelite from; an' ore pulp containing metalliferous and non-metalliferous contaminantsf'such as calcite, luorite and silicates, byaselective froth ltatio'n'based en -the application of a particular eifeetive collector composition comprisinga naphthe'nic acid, or its soap; and a` neutral oil, 'WhileV` controlling the pli-fof the ore"pulp. v

Other objects of the invention will become obvious to those skilled in the art'fromV the deto aloout-IQOL` However, thev optimum pH range for the otation'of oalcite and iiuorite also lies in theneghberhooldjof this figure, and' as a result sleelit does' no t separate lfrorrr the other constituents' of the pulpf On the otherjhand, it is observed that inl the pel-frange of about 117.5; and even at af pl-l of about ll,2,'all three minerale:` selieelitqk ealoite and' uorite, rare simultaneously depressed inthe presence of a sapcolle'cto, and tatin ofneither can be ihlvhed. Y :n Y 4 K It hasnovbeen diseovered that scheelite can be efffe'tively'f separated` from cale'ite, v fiuorite and most' ofthe sileeouS' g2ie` in froth flotation by adjusting plofthe pulp toa value higlier than abuitA 10.5, andl preferably betweenv about 10.8 and about 11.5'and even"higher, and apply ing a collector combination comprising anaph-l therc acid; conveniently addedin'j the form of aS'fQ'B-illpl, aS 'a S C 1 i 1 1i S 0D91lC, a neutral hydrocarbon oil to' effect' the selective flotatior')if of 'scheelite'.

Thisjregulation of priioupiee with the as dition of-Iieutral 'hydrocarbon v oil to tliefnaplithenic acidcollector resultsY in considerable im- Weight of W03A as eompared With scheelite conn centrates heretofore obtained in the industry.

bearing minerals are not pure but contain from about 20% to about 50% by weight of unsaponiable hydrocarbons or neutral oil based on' the combined Weight of oil-free acid and oil.

Neutral hydrocarbon oils may be added to these oil-containing naphthenic acids, as well as to pure acids, to secure the improved flotation elects of the present invention, provided the total content of neutral hydrocarbon oil in the collector combination does not exceed 50% by Weight of the combined weight of oil-free acid and oil. These oils are preferably petroleum distillates, such as light fuel oils, boiling between about 350 P. and about '700 F. and having a flash point in the range from about 100 F. to about 250 F. and a viscosity less than about 55 S. S. U. at 100 F.

In applying naphthenic acids or their soaps for preparing the collector of the present invention to secure the best flotation results, effective proportions of neutral oil for enhancing the selective flotation of ore may be varied from about 20% to about 50%by Weight of the oil, based on the total weight of the oil-free acid and oil in the combination. V

The true mechanism responsible for the depression o calcite, iluorite and siliceous gangue and for the selective flotation of scheelite is not fully understood, but it is believed that in the presence of the effective naphthenic acid soap collector, a mono-ionic coating of collector adheres to the surface of mineral particles, and, in

turn, adsorbs a second coating or layer of collector ions oriented reversely to the original layer, that is, with polar groups outwardly. This causes the mineral particles to become hydrophilic and unoatable. However, in the particular pH range of the present invention from 10.8 to 11.5 and higher, the formation of this second layer of soap collector molecules on the surface of scheelite particlesis less complete than upon calcite and fluorite particles, and permits the replacement of the second layer of soap collector particles by a layer of the molecules of neutral oil which are strongly adsorbed by the rst soap collector layer of particles and cause the selective flotation of scheelite.

It is noted that some siliceous material is oated along with the scheelite concentrate which floats in strongly agglomerated patches or clusters on the otherwise nearly clear froth. These clusters are air-bound and are held at the airwater interface. Since their apparent specific gravity is lower than that of the floated siliceous gangue, this latter undesirable contamination Vmay be eliminated, and the-scheelite concentrate upgraded by treating the froth carrying away the scheelite clusters by the method of agglomerate tabling.

In contradistinction to the conventional practice of tabling which is usually applied to recover materials too coarse to be levitated by froth flotation, the present invention resorts to tabling for the recovery of line agglomerated scheelite which has been previously subjected to froth flotation, in a manner heretofore unknown in the art, as will be described later on in this specification.

VWhen the selective froth flotation of the ore in accordance with the process of the present invention is followed by this tabling treatment of thev agglomerated scheelite, the W03 content of the final concentrate is increased to a value as high as Ll0--50% by Weight of W03 as compared with the values of 10% to 12% of W03 obtained by comparable froth flotation methods, e. g., using tallol acids as collectors.

The operation of the process of this invention will be better understood by reference to the drawing, wherein: Figure 1 represents a flow diagraml of the step-by-step processing of a typical tungsten-bearing ore in accordance with the invention; Figures 2 and 2A show diagrammatically a, conventional shaking table; Figures 3 and 4 represent the stratification of the constituents of the pulp between theriflles and the distribution of materials as they comejolf the shaking table respectively in a conventional. tabling treatment; Figures 5 Yand 6 illustrate the stratification of the pulp between the rifles and the distribution of materials leaving the table as in the present process. l j Y In the flow diagram'of lFigure 1 the tungstenbearing ore is fed to the process from mine l and undergoes a series of conventional crushing operations in a coarsecrusher 2 and fine crusher 3, before being dumped into storage bin 4. The crushed ore is taken out from the storage bin and subjected to grinding (milling) Ordinarily, such an ore may contain copper in the form of chalcopyrite, molybdenum in the form of molybdenite and tungsten in the form of scheelite. The other constitutents of the ore, theQgangue, may comprise calcite, fluorite anda variety of siliceous minerals, chiey quartz, epidote and garnet.

Afterwet grinding. to a relatively coarse grind, for example, in a ball-mill 5,fan aqueous pulp is formed which contains about 25% .by weight of solids in the form of ore particles-'not larger than 35 mesh in size. This pulp proceedsto a conditioning tank 6 where it is conditioned with a mixture consisting of an appropriate conventional collecting reagent, suchas an alkyl thiophosphate, for example, di-isobutyl dithiophosphatafor potassium amyl xanthate, inan amount of, say, 0.01 pound per tone of ore to vfloat the chalcopyrite and, simultaneously, anadequate amount of pine oil or cresylic acid (e.f g. ,0.1 poundper ton of ore), or other suitablefrothing agent for sulfide flotation, to act as a collector and frother for the molybdenite. In the diagram these conditioning agents are introduced into vconditioner 6 from a mixingtank lUvialine Il.

Upon flotation in lsulfide flotation cells I2 theA combined sulfide concentrate lor froth is sent through line I3 for additional processing, not shown inthe diagram, to'. obtain separate chalcopyrite vand molybdenite' concentrates. 1 This processing of sulfide-bearing .frothl mayf consist,

for instance, in steamingto decompose the chalcopyritel collector and subsequentlylfloating molybdenite away from chalc'opyritelwith the aid of additional frother, such as pin'e'loilor cresylic acid, supplemented, if desired, byanv addition of a small amount of neutral hydrocarbon oil of @the white-oil type.

In order to recover'scheelite by theprocess of selective froth flotation of. thepresent invention, the tailings from the V'flotation of combined chalcopyrite-molybdenite concentrate are` sent to another conditioning tank I4 to be treated with chemical reagents prior to beginning the flotation step. The conditioning .treatment of the pulp formed by these tailings maybe effected by forming a collector mixture in a mixing tankV l5 and introducing this mixture through line'l'into conditioning tank I4. The collector mixture in tank l5 comprises a naphthenic acid in the form of a soap^,'supplemented by a neutral hydrocarbon oil, the total amount of the oil in the mixture varying from' about 20% to about 50% by Weight based on the combined Weight of the soap and oil. As mentioned hereinbefore, naphthenic acids effective as collectors in the flotation of scheelite have acid numbers ranging from about 160 to about 190 maximum (on oil-free basis) andtheir unsapcniable hydrocarbon content may range from about to about 50% by Weight, provided the total content of neutral oil in the collector combination is less than about 50% by weight basedon the combined weight ofthe oilfree acid and oil. Satisfactory selective flotation of scheelite is usually obtained by adjusting the pH of the pulp to al value of about 10.8 and upward prior to the vintroduction of naphthenic acid. Sodium carbonate and sodium hydroxide are ordinarily added as pH regulators. In addition, the scheelite collector mixture may comprise a slime regulator and depressant from siliceous materials, e. g., sodium silicate (specific gravity 40-41" Be), and a reagent, such asquebracho or a similar tannin-bearing material, to promote the depression of calcite, fluorite and siliceous sangue. fv In a typical case, the` fcallowing collector mixture may be used to condition the pulpprior to the flotation of scheelite:

The conditioning treatment is effected by agitating the pulp with the reagents in tank I4 for at least 2 minutes in order to produce an intimate mixture, whereupon the pulp is fed into the rougher notation lcells Il. l I

The froth from these cells is directed into the cleaner flotation cells 20, While the rougher tailings, upon introduction of additional collector and, if desiredgiof neutral oil from tank I8 are sent' to the middling flotation cells 2l. Likewise, the tailings 'from the cleaner cells maybe recycled vas shown by line 22,'if desired, to the rougherflotation cells l1. From the' middling cells- 2| the froth is recycled as shown by line 23 to be retreated in the rougher flotation cells l1, while the tailings are withdrawn to' the reject pond.

The froth produced in the cleaner cells and carrying agglomerated clusters of vscheelite may be contaminated with some siliceous gangue which failed to become depressed, in spite of the critical adjustment of pH- to between 10.8 and 11.15 and the' application of the novel collector combination of the' present invention. In order to. free the scheelite-bearing froth from` thesev siliceous contaminants', it is subjected to agiglomerate tabling. Y Y y ,Y

' This latter operation is effected by utilizing any type of conventional shakingl table, as shown diagrammatica-lly in Figures 2 and 2A. A typical table 24 may be l5 feet'l'o'ng and 5 feet wide at the narrow or concentrate end. Itsdeck is depth of Mi at the head and to a feather edge along the diagonal'line'of termination and spaced ll/ apart. The table has a reciprocating motion parallel to itsv long axis, variablek from 230 to 280 strokes of about 3A" 'per minute. In the conventional tabling practi-ce`,f1the line heavy mineral 'particles are deposited at the bottom between individualY riles', While coarse light mineral is 'deposited at the top and is sheared off during the tabling operation bythe downilow of water, partly because of the thickening of the underlying bed ofy heavy mineral values between the' riles and partly because of the diminishing height `of the` riilies. The stratification obtained Abetween the rilllesV and the" distribution of the various materials' as they leave the table in a conventional tabling operation are shown in Figures Sand 4. A

In the tabling step of the present invention, as shown in the flow diagram in Figure 1, the heavier tungsten' values in the cleaner concentrate, agglon'ieratledl into airebound ocks which are coarser and` lighterthan the gangue, are'fed to shaking table 20;. These oc'ks stratify at the top between the riile's, are entrained by the flow oi Wash water, and come oi the tailing side' of the table, as detailed inJ Figures 5' and 6. The resulting scheelite concentrate is subjected to drying in drier 25'and iina'lly withdrawn to storage bin 2E?, v,while the' silic'e'os tailings, if desired, may be returned to the rougher flotation cells, as shown byline 27.

yThe novel application of agglomerate tabling to the recovery of scheelite in accordance with the invention 'increases the W63 content of the cleaner flotation concentrate by as much as 10% by weight, while the total recovery of scheelite from the original ore-feedA by thepresent process is of the ordero'f' 90% byfwei'ght. Concentrates containing 40% to 50% and even more by Weight of WO2 are readily produced by resorting to the particular collector combinations of the invention,l maintainingthe critical p-l range of the pulp and further concentrating and recovering tungsten values'b'y agglomeratie tabling` A number of snall scale' tests furnish the data which illustrate and emphasize the utility and advantagesr of the invention.

The ore'used in these 'tests' contained scheelite, calcite, nuorite, chalcopyrite and varioiis"v siliceous minerals. Ore samples were crushedthrough No. 10 mesh in laboratory jaw Crushers and rolls, anul grounds;A a 12" bau murat 5c R. P. M. Each' ball rnill cli'a'igeof 4500"g".`of orer was ground for'ab'out 10 minuteswith 300Go'. of Water.

A typical screen analysisof'suchaV ground ore isgiven below in Table I:

TABLE I Direct Cumulative The mill `freed" analysis of this ore indicates the followingcontent mineral values:

Moszosy@ ,f cil-0.3 'No3-0.35

Flotation of chalcopyrite-molybdenite concentrate was Veffected in a' 4600 g. Fagergren laboratory cell having a rotor speed of 1800 R. P. M.,

dilution of the pulp being about 25% solids for both chalcopyrte-molybdenite and scheelite flotation. Chalcopyrite molybdenite concentrate was oated away with the aid of a collector combination comprising an alkyl thiophosphate co1- lector for chalco'pyrite, such as di-isobutyl dithiophosphate (0.01 to, 0.05 pound per ton), and pine 'oil acting asY a collector and frother Vfor molybdenite (0.1 to 0.15 pound per ton).

In the subsequent tests of molybdenite otation,` the effects of addition f various hydrocarbon oils'on the grade of molybdenite concentrate were compared. Two neutral hydrocarbon oils were used: A-a heavy aromatic oil having an A.,P. I. gravity of 13.9, and boiling between about 400 F. and about 700 F.; and oil "--obtained by polymerization of butenes and having a viscosity of about 222 S. S. U. at 210 F. The maximum of improvement in collection eciency was noted in the case of a collector combination: di-isobutyl dithiophosphate (0.007 pound per ton) pine oil (0.12 pound per ton) and neutral oil B (1 pound per t0n).

The results of these tests of molybdenite recovery are tabulated in Table II. The analyses of the concentrates and middlings were made by means of a polarograph, while those of the tailings by means of a spectograph.

TABLE II Eect of oils upon flotation of molybdemte After the removal vof the chalcopyrite-molybdenite concentrate the scheelite-bearing tailings were reconditioned for about two minutes with a mixture of the following reagents:

Y Lbs. per ton Sodium carbonate, a pH regulator 5.0 Sodium silicate (40 B.) a slime regulator 5.0 Quebracho, a depressant for silicates and quartz 0.5

Thereupon .75 pound per t0n of oil-free naphthenic acid in the form 0f sodium soapv was added to a similar batch of scheelite-bearing tailings, and the sample subjected to flotation in the rougher flotation cells.

The acid used in these tests has been originally o of w03).

8 obtained by extraction of a lubricating oil fraction and"contained about 43% by weight of Vunsaponiablematerial; it was dissolved in dilute sodium'hydroxide soluton and repeatedly ex.-

tracted with petroleum ether until substantially all Vsaponiable Yoils have been removed from it, whereupon it -was acidied to yield an oil-free naphthenic acid'v having an acid number of approximately 177 and a specific gravity of 0.97.

10 Upon withdrawing a rougher scheelite froth, an

additional 0.75 pound per ton of oil-free naphthenic .acid in the form of sodium soap was added to the rougher tailings and a middling froth removedA from the corresponding flotation cells. The remaining material Vconstituted thev final rougher tailings. The rougher froth product was refloated in fresh water upon the addition of 0.25 poundper ton of naphthenic acid (as sodium naphthenate), and 1 pound per ton of sodium 0 carbonateV toA yield a final cleaner concentrate In this first test the pI-Ivof the pulp was equal throughout to 10.0. Two other tests, Nos. 2 and 3, were carried out at a higher pH of 11.2, which was achieved by the introduction of about 4 pounds per ton of sodium hydroxide prior to the recovery of rougher flotation froth and of additional 2 pounds per ton of sodium hydroxide prior to the recovery of final cleaner froth. In the last test, No. -3, the oil-free naphthenic acid (as sodium naphthenate) was applied together with about 0.75 pound per ton of neutral hydrocarbon oil, namely, a light petroleum fuel oil which boiled in the range from about 360 F. to about 684 F. and had a gravity value of 31.9 A. P. I., a ash point 0f 174 F., and a viscosity of 37.1 S. S. U. at

100 F. The cleaner froth product from all three tests was subjected to a form of agglomerate separation (tabling) by using a vanning plaque for the purpose, except in test No. 1 where the amount o of cleaner froth was too small to permit separa- .tion.

The'results of flotation tests Nos. 1, 2 and 3 are ypresented in Table III and indicate that a pH equal to 10.0, the application of oil-free naphthenic acid as a notation agent results in a low recovery of W03 equal to 50.8% by weight of the totalxWOs in the ore, even though the cleaner concentrate grade is rather high (58.7% by weight Increasing the pH to 11.2 depresses the scheelite and reduces both the concentrate grade and the total recovery, notwithstanding the application of agglomerate tabling. However, upon addition of neutral hydrocarbon oil in test No. 3, the concentrate grade was markedly improved and a very satisfactory recovery value of 61.9% was attained.

. TABLE III Test No. 1, i Test No. 2, Test No: 3' pH=10.0 Qil-free pH=ll.2 Oil-free llerHllz Ou'fre Naphthemc Amd Naphthenic Acid agg Ifellfafl Percent Percent Percent Percent Percent Percent P r t P Percent Total Total e .Cen ement Weight W0; WOa Welght W03 Wol Weight WO; 'Jazl Agglfomerate Concenm n 0. e1 21. 5 32. 2 0.53 47 0 61 9 Aggmmerate railing 0.51 18. 2 22. s geaner gonhclentrate g. 52.1 Y 5(8).225 0 20 37'4 18' 4 eanr a1' g 1 2.12 1.4 1.4 5.78 Midd1mg 5.8 .58 14.1 11.2 0. 35 9.6 11.4 339 l2 Rougher Ta11ing. 82. 9 05 16. 9 81. 4 0.14 28.0 79. 0 0. 03 5 9 Sulde Concentrate l0. 3 4. 2 3, 1

Heads-- 0.24 41 41 anotner group of." tests 4J .5. and 6, were enacted byI following the ame procedure as de- 10 With the nanlithenic acidrneiitral hydrocarbon oil collective combinations. in which theproporseriedfor tests 1; :2 and 3. However. in tion of neutral hydrocarbon oil. Whether Oriel-- these. tests the nanhtnenic acid wasa connneroial nallv in the. acid or Subsequently added thereto, grade naphthenic acid added in the form of so- 5 does not exceed 50% by Weishtbased on the comdiiirnsoap, having an acid number on oil-free bined Weight of the oil and acid, compared with basis canal to, ll'and containing 30% by weight the results obtainedwi-th naphthenic acid with-V ofunsapcninable matter. The other reagents and Ollt neutral Oil, 0I' With a naphthenc acid-.neutral test conditions were identical with those applied Oil COmbnatQn containing neutral oil in excess in tests. 1, z and 3 except forth@ fact that 1.0V 10 of 50% by Weight, or with a combination of a pound per ton of naphthenic acid was used to fatty aCd 01 its S0510 With neutral Oilloat the rougher and middling concentrates, in- The antlySiS O f tungsten fnntent as represtead of 0.75 pound per ton. The results presented in tile ttbuifted dat@ Was effected as foi' sen-ted in Tapie 1v show that with the higher pH IOWS: Ore. Salnlelns were treated with an acid, equal to 11.2, the application of commercial grade l5 Dlefefibly hydrochloric, in Order to decomposel naphthenic acid containingabout 30% by weight seheellte and to precipitate most tungsten as of unsaponiable material as a flotation agent tungstlc acid The remainder WaS lteled and improves the recovery o'fscheelite as shown by wattted and finality eXtraCted With DOtaSSium 115- the values determined for agglomerate conceniK-Xldef the iCSllltng Potassium tungstate S0111- trate. However, the addition' of neutral oil to 20 non bemg thereafter @Cidied and treated With this acid in the amountof .'15 pound per? ton in a emes-S of alpi-1a benzonoxime' The* greci-mi' test NQ 6 showed very definitely that such an gtdsungsten complex was ltered and ignited lflidllile,csglnbgtlettaopomon egg-nin It hasbeen observed that in certain instances, f l am gv e e l f-g 25 the eiiiciencyof selective notation according to 59% by Weight Qf. they total Weight 0f acid and the process of this invention may be adversely af- 011, an adverse eecton the IeCOVelY Of fected by the hardness of water used. Coarse and soheelite. heavy flocks or tungsten minerai wiii then be TABLE IV Y e Test No.6,

,- pantitiftntnag pealtesdiitaim pngai-gjelgggalag Naphthenic Acid Naphthemo Acid Neutl Oi? Percent Percen eliel'-lercent ,lva Pceit Totali; Pant PIiiit Agglomerate Concentrate. Agglomerate Telling Cleaner Concentrate.

Sultlde Concentrate Heads In addition, tests were carried out with oleic acid (test, No. 7) and semi-.refined tallol acid (test N028), applied in the form of their sodium soaps, at a pH' of 11.2 and'vvith the addition of the same amount of the neutral hydrocarbon oil as u secl in preceding tests Nos. 4, 5 and 6. 'The test data presented in Table V show vunambiguously that the improvement in the selectivity of sclieelite notation in the pHrange from 10.8 t0

,present invention will require softening whenever its hardness approaches about 88 p. n. mof calcium ion.

11.5 are peculiar of the naplithenic acidfneutral 55 The new process is not limited by the exampes hydrocarbon oil collector combination of the nor by the QW diagram dSfSQlibed herenabve, presentv invention and that fatty acids are unand includes Within its scope all the modicatons Suitable for the use in combination with such and variations.. thereof, except as limited by the neutral oils. appended claims. Thus, for exalgrple2 the quanti- TABLE V Test No. 7 Test No. 8 PH.=11.2 oleic Acid pnaiiz Tauoioii Neutral Oil Neutral O11 Percent Percent Percent Percent Percent Percent 1 weight Wo '$521. Weight wo wg?.

Agglomerate Concentrate.-- 0.05 16.6 1.4

Agglomerate Taling 0.05 28.4 2.5

Cleaner Concentrate.. 0. 05 35. 4 3. 1

Cleaner Tailng. 0. 3 16. 6 9.0 0. 92 34. 3 53. 5

Middling e. 1 c. 3 69. i o. to 1o. 6 1o. s

Rougher railing... eo. 9 0.11 18.0 9o. 1 o. 2o 32. e

Sulde Concentrate.. 2.6 2. 3

Heads 0 56 0.59

The data from the above tests clearly point out the superiority of the notation results Obtained ties of the various reagents may be varied to suit the requirements of each particular case;

1l likewise, the rougher concentrate may be cleaned and recleaned as many times as desired. Furthermore, other eflicient collectors and frothers than pine oil and alkyl thiophosphates may be used for the recovery of copper and molybdenum values described hereinbefore.

In 'summarizing the various significant improvements over the prior art secured by this invention, the following important features thereof are emphasized:

(l) Production of high grade tungsten concentrates largely superior to those previously obtained in the art is'now made possible;

(2) The grade of tungsten concentrate may be further improved by the application of agglomerate tabling to remove persisting siliceous contamina'nts';

^ (3) High amounts o f tungsten minerals vmay be recovered from tungsten-bearing ores by selective flotation in the alkaline pI-I range of 10.8 to 11.5 with'the'aid of heavy naphthenic acids as flotation collectors improved by the addition fof neutral hydrocarbon oil.

It is finally stressed that this invention is not limited to the flotation of scheelite away from calcite and iuorite;v but that this process may also be successfully used to recover tungsten minerals from any type of tungsten-bearing ore, wherein other constituents have the same or an equivalent cation, such as calcium or magnesium and, therefore, cannot be floated away from each other by conventional flotation procedures. For "instance, it is possible to separate scheelite from ores containing, e. g.,pscheelite and magnesite, or

from ores containing scheelite, apatite and anhydrite.

As mentioned above, many modifications may be made in the process of the invention without departing from the spirit thereof, its scope being limited solely by the definitions in the appended claims.

I claim:

1. In a process of recovering scheelite from an ore pulpcontaining scheelite, calcite, fluorite and siliceous gangue and having a pH of between about '10.8 and'about. 11.5, the combination of steps of conditioning said pulp with sodium silicate as a slime regulator and a tannin-containing depressant for said calcite, uorite, and siliceous gangue; effecting selective flotation of scheelite away :fromh said calcite, iluorite, and siliceous gangue contained in said pulp in the presence of a collector combination comprising a soap of a naphthenic acid having an acid number on oilfree basisbetween about 160 and about 190 maximum, and, further comprising from about 20% toless than about 50% by weight of afneutral petroleum hydrocarbon oil boiling between about 350 F. and about 700 F. and having a viscosity of less than about 55 S. S. U. at 100 F., based on the total weight of oil-free acid and oil.

2. In a process of recovering scheelite from an ore pulp containing scheelite, calcite, uorite and siliceous gangue and having a pH of between about 10.8 and about 11.5, the combination of steps of conditioning said pulp with sodium silicate as a slime regulator and quebracho as a degangue; effecting selective vnotation of scheelite away from said calcite, iluorte, and siliceous gangue contained in said pulp in the presence of a collector combination comprising a soap of a naphthenic acid having an acid number on oilfree basis between about 160 and about 190 maX- imum, and further comprising from about 20% to less than about 50% by weight of a neutral petroleum hydrocarbon oil boiling between about 350 F. and about 700 F. and having a viscosity of less than 55 S. S. U. at 100 F., based on the total weight of oil-free acid and oil.

3. In a process of recovering scheelite from an ore pulp containing scheelite, calcite, fluorite and siliceous gangue and having a pI-I of between about 10.8 and about 11.5, the combination of steps of conditioning said pulp with sodium silicate as a slime regulator and quebracho as a depressant for said calcite, uorite and siliceous gangue; effecting said selective flotation of scheelite away from said calcite, fluorite and siliceous gangue contained in said pulp in the presence of a collector combination comprising a soap of a naphthenic acid having an acid number between about 160 and about'190 maximum on oil-free basis, and further comprising from about 20% to less than about 50% by weight of a neutral petroleum hydrocarbon oil boiling between about .350 F. and about 700 F. and having a viscosity of less than 55 S. S. U. at 100 F., based on the total weight of oil-free acid and oil; recovering the resultant supernatant oat of light air-bound clusters of scheelite particles; and floating away said supernatant clusters of scheelite particles from the underlying heavier siliceous gangue of said iloat by agglomerate tabling.

WILLIAM A. BATES.

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

UNITED STATES PATENTS Number Name Date 1,319,129 Wells Oct. 2l, 1919 1,953,431 Patek Apr. 3, 1934 2,069,365 Handy Feb. 2, 1937 2,094,646 Frantz Oct. 5, 1937 2,105,827 Tartaron Jan. 18, 1938 2,120,485 Clemmer et al. June 14, 1938 2,216,992 Vogel-Jargensen Oct, 8, 1940 2,303,962 Tartaron et al Dec. 1, 1942 2,373,305` Gieseke Apr. 10, 1945 2,395,639 Monson Feb. 26, 1946 2,442,455 Booth June 1, 1948 2,464,313 Weinig Mar. 15, 1949 OTHER REFERENCES Gaudin, Principles of Mineral Dressing (c), 1939, by McGraw-Hill Book Company, pages 387-388.

The Mineral-Industry during 1939, vol. 48 (c),

` 1940, page 673.

pressant for said calcite, uorite, and siliceous Y Engineering and Mining Journal, April 1943, p. 66.

Taggart, Handbook of Mineral Dressing (c),

1945, section 12, page 13.

Claims (1)

1. IN A PROCESS OF RECOVERING SCHEELITE FROM AN ORE PULP CONTAINING SCHEELITE, CALCITE, FLUORITE AND SILICEOUS GANGUE AND HAVING A PH OF BETWEEN ABOUT 10.8 AND ABOUT 11.5, THE COMBINATION OF STEPS OF CONDITIONING SAID PULP WITH SODIUM SILICATE AS A SLIME REGULATOR AND A TANNIN-CONTAINING DEPRESSANT FOR SAID CALCITE, FLUORITE, AND SILICEOUS GANGUE; EFFECTING SELECTIVE FLOTATION OF SCHEELITE AWAY FROM SAID CALCITE, FLUORITE, AND SILICEOUS GANGUE CONTAINED IN SAID PULP IN THE PRESENCE OF A COLLECTOR COMBINATION COMPRISING A SOAP OF A NAPHTHENIC ACID HAVING AN ACID NUMBER ON OILFREE BASIS BETWEEN ABOUT 160 AND ABOUT 190 MAXIMUM, AND FURTHER COMPRISING FROM ABOUT 20% TO LESS THAN ABOUT 50% BY WEIGHT OF A NEUTRAL PETROLEUM HYDROCARBON OIL BOILING BETWEEN ABOUT 350* F. AND ABOUT 700* F. AND HAVING A VISCOSITY OF LESS THAN ABOUT 55 S.S.U. AT 100* F., BASED ON THE TOTAL WEIGHT OF OIL-FREE ACID AND OIL.

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