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Patented July 9, 1946 2,493,481 .METHOD OF CONGENTRA'E‘ENG Julius Bruce Clemmer and Carl Rampaceh: ‘in caloosa, Ala., assignors to the United States at America, as represented by the Secretary of the Interior ‘ No Drawing. Application February 9, 19%, Serial No. 576,996 7 Claims. (Granted under the act oft March 3, 1883, as amended April 30, 1928; 370 Q. G. 75'?) ' 2 l with the lignin sulphonates. The metaphos The invention described herein may be manu phates and pclyphosphates may be used as sup factured and used by or for the Government of plementary reagents in conjunction with various the United States for governmental purposes crude or puri?ed liin sulphonates, if desired, without the payment to us of any royalty there but are not obligatory in the practice of this in» on in accordance with the provisions of the act vention. of April so, 1928 (Ch. 460, 45 Stat. L. 467). The lignin sulphonates which we prefer to uti This invention relates to an improved process lize as iron oxide depressants in this invention for concentrating iron ores whereby froth ?ota are present in and may be derived from the tion of the siliceous gangue constituents yields an iron enriched product; more particularly it re Ill?) by-product of the sul?te process of paper making commonly known as “sul?te liquor.” These lates to a froth ?otation process employing anionic collecting agents to effect ?otation of . liquors separated asv waste from the cellulose ' pulp contain soluble salts of the lignin sulphonic activated siliceous gangue constituents from acids and other non-ligneous organic substances, caustic alkaline iron ore pulps while retarding ?otation of the iron oxides with lignin sul 15 such as hydrolyzed carbohydrates, resulting from phonates. ' ' An object of this invention is to provide a froth ?otation process for concentrating iron oxides in pulps containing them in the presence of siliceous gangue. A further object is to pro vide a ?otation process for separating silica from . iron. oxides employing anion-active collecting agents A still further object is to provide a ?ota decomposition of the wood by the acid solutions used in the pulping process. In the sul?te proc ess, the lignin in the wood is dissolved by digest the wood chips with an acid calcium, mag nesium, or sodium sul?te solution at an elevated temperature whereby the lignin forms soluble cal cium, magnesium, or sodium lignin sulphonates depending on the base‘ employed. The sul?te liquors containing the lignin sulphonates and non= tion process for concentrating iron ores or prod ucts from the milling of iron ores containing both 25 ligneous materials may be used as the iron oxide depressants in the practice of our invention or calcareous and siliceous gangue materials. Still ' the crude sul?te liquors may be puri?ed by known other objects include the development of a ?o methods to reject the non-ligneous substances tation process which will have greater selectivity and recover a substantially puri?ed lignin sul» in separating siliceous materials from oxide iron ore pulps and thereby effect greater operating 30 phonate which may be employed to retard ‘the economies. Other objects, purposes, and advan tages of the invention will hereinafter more fully appear or will be understood from the detailed description of its practice. iron oxides in our method of silica ?otation. The crude or whole sul?te'liquor recovered from the sul?te pulping process and ‘containing the lignin sulphonates and non-ligneous organic In a co-pending application, assigned to the 35 substances, such as hemi-cellulose. and various sugars, may be evaporated to yield a concentrated same assignee as the present application, Serial No. 473,162, ?led January 22, 1943, by Julius - liquid or dehydrated residue for marketing. The liquid forms as marketed contain about 50 per Bruce Clemmer and Ballard H. Clemmons, is de cent water, whereas the powdered forms are sub scribed a process for bene?ciating iron ores by froth ?otation wherein anionic collecting agents 40 stantially dehydrated. The liquid and powdered are employed to ?oat activated siliceous gangue constituents from caustic alkaline iron .ore pulps forms have been used interchangeably in our I method of ?otationand, based on their respec- ' tive content of lignin sulphonate, are equally ef fective for retardation of iron oxides. Compara 45 tive tests using the calcium, magnesium, and so phosphates. ' dium base sul?te liquors, or the respective dehy As a result of further extended research and with a pH of at least 10, while, retarding ?otation of the iron oxides with metaphosphates or poly dration residues thereof, gave substantially equiv experimentation, we have discovered an improved alent results. The non-lignéous materials-pres method of concentrating iron ores by froth ?ota ent in the liquid or dehydrated residues appear tion of activated siliceous gangue constituents employing anionic collecting agents, such as the 60 to be inactive diluents and exert little or no del eterious e?ect in the froth ?otation of activated higher fatty acids, resin acids, mixtures of fatty siliceous gangue from iron oxides. The evap and resin acids, and soaps thereof, to ?oat the activated siliceous materials from caustic alkaline iron ore pulps with a pH of at least as high as orated crude sulflte liquors or dehydration resi dues were slightly less effective pound per pound 10,‘ while retarding ?otation of the iron oxides 55 than the corresponding puri?ed lignin sulpho 2,408,481 nates relatively free of non-ligneous material, but were particularly attractive as iron oxide de pressants in our method of flotation due to their lower cost. The crude or evaporated sul?te liquors may be processed by numerous methods to reject the non ligneous material and recover substantially puri 4 anionic. ?otation and establishing the desired caustic alkalinity for ?otation by formation of caustic soda within the pulp. The optimum pH for anionic ?otation of the activated silica and retardation of the iron oxides varies slightly for dl?'erent ores but generally falls within the range of 10 to 12, and the proper pH for any particular case is best determined by experimentation. Poor ?otation of the silica and incomplete retardation mineral acids, lime water, basic lead acetate, or 10 of the iron oxides invariably results if the pI-l of » organic bases may be employed to recover the the pulp is much less than 10; a pulp pH greater ?ed lignin sulphonates. Fractional precipitation methods using sodium chloride, calcium chloride, lignin sulphonate and reject the non-ligneous materials. The precipitated lignin sulphonate than 12 is not particularly objectionable, but the froth is inclined to be voluminous and ?otation of may be further puri?ed by dissolution and re the silica is sluggish. We therefore prefer to keep precipitation, by dialysis, or other methods. The 15 the pH in the range 10 to 12 in our ?otation puri?ed sulphonates are ordinarily marketed as method. a the powdered forms but solutions containing from It is essential in the practice of this invention 15 to 50 percent of the lignin sulphonate are also that the siliceous gangue constituents in the iron available. Various of the commercially'available ore be activated and made ?oatable by the anionic puri?ed lignin sulphonates containing the cal 20 collecting agents. The siliceous gangue materials cium, magnesium, sodium, barium, aluminum, in certain iron ores, such as the calcareous red ' zinc, and copper salts have been tested and found ores of the Birmingham district, Alabama, are satisfactory as iron oxide retardants in the prac naturally activated to soap ?otation presumedly tice of our invention. The calcium, magnesium, due to the presence of lime and/or magnesia salts and sodium sulphonates are less expensive than 25 in the ores. siliceous iron ores, as exemplied by the heavy metal salts and were preferred. The the weathered red ores of the Birmingham dis liquid or powdered forms of either the crude or puri?ed sul?te liquor materials may be used in our method of ?otation, and the ultimate choice of the particular lignin sulphonate employed will 30 A variety of liquid and powdered forms of both largely depend upon economic factors. ‘ crude and puri?ed sul?te liquor products are com trict and most siliceous ores of the Lake Superior district, seldom contain naturally activated sili ceous materials, and the successful operation of our process requires that the silica in such ores be activated for anionic ?otation. Extended re- . search on a variety of siliceous iron ores demon strated that our method of ?otation lends itself mercially available and have been found satisfac readily to the use of silica activating agents. tory for retarding iron oxides in our ?otation 35 Many alkaline earth and heavy metal salts'ex method. Examples of the sul?te liquor materials hibit the property of activating quartz andvar which we have used successfully include those ious silicate minerals to soap ?otation if a proper sold under the trade names "Bindarene Liquid,” quantity is employed at an optimum pH. We “Bindarene Flour,” “Goulac,” “T. D. A.,” “Mara have found that conditioning of the caustic alka thon Extracts M, T, NS, TanC, SL, DT-31, DT-32, 40 line iron ore pulp with amoderate quantity of an DPT-33, DT-34, and DT-35,” and the “Daxads ll, activator selected from the group consisting of 21 and 23.” Other sul?te liquor products which soluble calcium, magnesium, barium, strontium, we have found acceptable include the crude and and lead salts su?lces to activate the siliceous puri?ed magnesium lignin sulphonates, the acid, constituents to anionic ?otation by the higher neutral, and basic calcium lignin sulphonates, 45 fatty acids, resin acids, or their derived soaps and sodium, copper, zinc, aluminum, and barium without adversely affecting retardation of the lignin sulphonates. For convenience, we shall iron oxides by the crude or puri?ed lignin sul hereinafter use the‘ term “lignin sulphonate” to phonates. The commercial lignin sulphonates' include the crude and puri?ed metal salts of are generally marketed as calcium or magnesium lignin sulphonic acids, the crude and puri?ed 50 salts of the lignin sulfom'c acids and as such may paper mill sul?te liquors, and dehydrated residues contain su?icient lime or magnesia to activate thereof. ' part of the silica in iron ores to ?otation. ,In While we have achieved satisfactory ?otation ' general, however, the metal salts in the lignin sul of activated silica from iron ore pulps containing are insui?cient for complete activation substantial quantities of slime by the practice 55 phonates of the silica and supplementary metal Salt acti of our invention, we prefer that the pulps be de- ' vating agents may be needed for an improved sep slimed. Desliming of the iron ore pulp should ‘ I be practiced whenever permissible as subsequent ?otation of the activated silica is more rapid and aration. ' , ~ In the practice of this invention, We prefer to employ hydrated lime for activation of the silica. complete, and less reagents are required. 60 Grinding or blunging the iron ore with sufficient A caustic alkaline pulp with a pH at least as hydrated lime to establish a pulp pH of about 11 high as 10, and preferably in the range of 10 to 12, is preferable in our method of ?otation to facilitate e?ective retardation of the iron oxides will generally su?lce on most ores for complete ac tivation of the siliceous gangue. The quantity of hydrated lime required’to activate the silica in by lignin sulphonates. We prefer to employ caus 65 iron ores varies from 1 to 4 pounds per ton of ore, tic alkalies, such. as sodium or potassium hy but some ores containing acidic salts may require droxide, or their equivalents, to establish the de 8 pounds or more of hydrated lime per ton. Our sired pH for ?otation. Moderate quantities of experiments on a variety of calcareous and silice other alkaline reagents, such as sodium sul?de, ous iron ores have revealed that only part of the sodium carbonate, and sodium silicate, may be 70 hydrated lime added to the ?otation pulp is con ’ used in conjunction with the caustic alkalies if sumed in activating‘the siliceous constituents to desired. A combination of hydrated lime and ~ anionic ?otation; part of the added lime may re soda- ash has been successfully employed in the act with salts in the pulp and is precipitated as ?otation ‘of many iron ores and served the dual carbonate, another part is adsorbed by the iron purpose of activating the siliceous materials to 76 oxides,v still another part remains in solution to dresser , 5 _ and ?nally any excess hydrated lime added to the tannin materials such as quebracho extract, can extract, and Borneo cutch. These auxiliary ad» pulp remains undissolved. The lime consuming capacity differs for different iron ores, and the proper quantity for activation of the silicais best in that they enable more e?ective retardation of the iron oxides with minimal quantities of the satisfy the solubility requirements of the water, determined by experimentation. Excessive quan= titles of dissolved lime in the conditioned pulp dition agents are advantageous on some iron ores lignin' suiphonates during anionic ?otation of the activated siliceous materials. The proportions of the various reagents em ployed in the practice of this invention are sub Ject to considerable variation, and the ‘optimum achieved by the practice of this invention gem quantities are best determined by experimenta ?otation of silica from iron ore pulps containing ' dissolved lime equivalent to 1% parts per million I v tion for any particular case. Purity of the sen‘ arated products is a. reliable guide for reagent of hydrated lime-For about lit pound of hydrated adjustment. An excess of collecting agent pro lime per ton of solids in our tests, we prefer that the ?otation pulp be substantially free 0;? dis- 15 motes ?otation of a portion of the'iron oxides with the siliceous gangue, whereas a de?ciency solved lime. The dissolved lime may be removm of collector results in incomplete ?otation of the either by washing the conditioned pulp with fresh siliceous gangue. Conversely, an crew of lignin water, ‘or by addition of su?lcient soda, ash to pre sulphonate results in retardation of a portion of, cipitate the lime as insoluble calcium carbonate. should be removed before ?otation as they in» crease collector requirements; Although we have Brief conditioning of the iron ore with sumcient 20 the siliceous materials, whereas a de?ciency per mits ?otation of some of the iron oxides with the hydrated lime to give a pulp with a. pH of about silica. Control of the collector and lignin sul 11 generally su?lces for complete activation of the silica. Subsequent addition of soda ash to the pulp; the requirements for most ores being 1 to 2 pounds per ton of solids, precipitates the lime in solution and gives a pulp of the desired caustic alkalinity for ?otation. Should an excess of hydrated lime be inadvertently added to the pulp to activate the ‘silica, as evidencedby a pH of about 12.8, the excess is best removed by settling .30 and washing the pulp one or more times with phonate is not critical, however, and reasonable variation in the quantities employed is permis= sible without adversely a?ecting the separation. ‘To avoid possible confusion in describing the results of our ?otation test, we shall hereinafter designate the iron enriched pulps from the rough ing and cleaning steps as “iron concentrates, rougher” and “iron concentrates, cleaner,” re spectively. The ?oated silica products from the . ' roughing and cleaning steps will be designated fresh water to reduce the pH to ll, whereupon as “rougher froth” and “silica rejects,” respec soda ash may be added to precipitate the remain= tively. In describing the results of our test we ing lime in solution before proceeding with flo consider and report the iron enriched pulps tation. If desired, however, the washing may be 35 shall from the cleaning steps (middlings) as ?nished carried further to give a. ?nal pulpfor ?otation concentrates. It will be readily apparent to those practically free of dissolved lime and having a skilled in the art that the middlings may be re-_ pH of 9 to 10. Subsequent addition of a caustic , treated by conventional methods in continuous , alkali to the lime conditioned and washed pulp to establish the desired pH for ?otation together 40 ?otation operations to yield an even higher grade concentrate without departing from the spirit of with a lignin sulphonate and a fatty acid or soap the invention. ' collector enables ?otation of the calcium-ac The invention will be further illustrated, but is tivated silica and retardation of the iron oxides. not intended to be limited by the following ex ‘It will be apparent to those skilled in the art» ' amples of ' practice: that soft water free of lime or magnesia salts is not obligatory in the practice of this invention. Emamnle Z Some lime or magnesia salts ‘in the ?otation pulp A sample of calcareous red iron ore was ob are permissible, and, in fact, are advantageous tained from an operating mine in the Birming» in that they insure complete activation of the 50? ham district, Alabama. The ore was typical of siliceous constituents to ?otation. . ~ The anion-active collecting agents which we , havefound suitable for ?otation of the activated siliceous gangue materials from iron oxides in clude the higher fatty acids such as oleic' acid or the district and ‘contained hematite associated with a gangue composed predominately of quartz and calcite together with minor quantities of accessory calcareous and siliceous materials in cluding shale and ferruginous clay. A head an . red oil, the puri?ed or crude sodium oleates, fish 55 alysis gave 86.2 percent Fe, 10.6- percent 09.0, oil fatty acids, ?sh oil soam, and various crude and puri?ed talloels and sulfate soaps derived from sulfate paper mill black liquors. The tall oels, which are mixtures of fatty and resin acids, are relatively inexpensive and are the preferred collectors in the practice of our invention. We have discovered that various addition agents may be advantageously employed to sup- j plement the crude or puri?ed lignin sulphonates and 24.6 percent hydrochloric acid insoluble (hereinafter referred to as “insol."). The sample was a. typical calcareousv iron ore containing siliceous gangue naturally activated to soap ?o tation. Pulps of the ground ore were alkaline (pH-8.6), and qualitative tests on the water showed presence of lime salts. _ V In carrying out the ?otation process according to this invention, the iron ore or product to be treated is ?rst ground to proper size for ?ota tion, if not already of such size, by conventional addition agents which we have‘ employed and methods. The ?neness of grind may vary from found useful include the metaphosphates; the 35 mesh to 200 mesh or ?ner depending on the polyphosphates; sodium silicate; sodium ?uoride; starches of different botanical origin such as po 70 degree of interlocking of the iron oxides and in the practice of our invention to enable an improved separation to be obtained. . The various gangue constituents in the particular ore; sub stantially complete liberation of the-iron oxides and siliceous gangue is essential for a satisfac yield starch solutions or gels of the ruptured tory separation by ?otation, and the ?neness of ' granules; hydrolyzed starch products, such'as British gum or dextrins; and various vegetable 75 grind for a particular ore should be selected ac tato, vwheat; corn, rice, arrow-root, or tapioca solubilized byheat and/or chemical treatment to ' 2,403,481 ' 8 . cordingly. A limiting size of 100 mesh was chosen for this ore. A 250-gram portion of the ore rolls-crushed to 20 mesh was wet ground to pass 100 mesh using 25 pounds of one-half inch steel rods as the 5 grinding 'media with 250 ml. of tap water in a lab oratory rod mill.‘ The ground charge was diluted to a volume of 2.5 liters with additional tap water to give a pulp containing about 10 percent solids. The pulp which was ?occulated was then m dispersed using caustic soda and soda ash equiva» lent to 2.0 and 1.0 pounds per ton of ore, respec tively. , The dispersed charge was fractionated percent of the weight of the feed and contained 46.0 percent of the insoluble and only 3.3 percent or the iron. The untreated slime and cleaner middlings were su?iciently low. in insoluble to be considered as iron concentrates. The composite iron concentrates from the test represent a recov cry of 96.7 percent of the iron in the feed and assayed 45.9 percent iron, 6.1 percent lime, and 16.9 percent insoluble. The results of the recorded test were about average of those obtained on deslimed charges of the calcareous red iron ore ground in alpebble mill, iron ball mill, or iron rod mill to pass v65, by sedimentation and decantation to remove the 100, or 200 mesh, respectively. Good ?otation bulk of the slime ?ner than 20 microns. The 15 of the activated quartz and granular silicates was granular portion, substantially free of slime and achieved in the tests by using from i. to 2 pounds coarser than 20 microns, was repulped with ad per ton of an anionic collecting agent, such as ditional tap water and transferred to a small oleic acid, sodium oleate, ?sh oil fatty acid, ?sh mechanical ?otation cell of standard design. oil soap, or a crude or puri?ed talloel or sulfate Su?lcient tap water was added to give a pulp for 20 soap from sulfate paper mill black liquors, to= ?otation containing ‘about 20 percent solids. gether with sufficient caustic alkali to give a pulp Flotation of the naturally activated silica was pH of about 11 and from 1 to 4 pounds per ton effected from a caustic alkaline pulp using talloel of a crude or puri?ed lignon sulphonate to retard as the collector, and Goulac, a commercial dehy the iron oxides. Sodium hydroxide, potassium drated sul?te liquid product marketed by Amer 25 hydroxide, caustic soda (commercial lye), and combinations of hydrated lime and soda ash to depressant. The reagent charge expressed in form caustic soda in the pulp proved equally suit conventional pounds per ton of ore was as fol ican Gum Products Company, as the iron oxide lows: able for establishing the desired caustic alka= linity for ?otation. 30 Example II A 250-gram charge of‘ the calcareous iron ore ' Conditioner P Cleaner ‘ Rougher \ No. 1 No. 2 was ground to pass 100 mesh as in Example I. r The ground charge, including slime, was trans No. 1 No. 2 0. 4 0.5 0.1 2.5 0L 4 0.5 0.1 2.5 0. 4 0.5 0.1 2.5 10.5 10.5 10.5 Caustic soda. o u] No. 3 35 ferred to a small mechanical ?otation cell of - standard design and sui?cient tap water was added to give a pulp for ?otation containing about 22 percent solids. Flotation of the silica from the slime-bearing pulp was e?'ected by the The substantiallydeslimed pulp was ?rst con 40 following reagents expressed in conventional ditioned with the caustic soda (commercial lye) terms of pounds per ton of ?otation feed: and Goulac to establish the alkalinity desired for ?otation and to retard the iron oxides. Talloel Condi was chosen for the collector in the test. The pulp “on” Cleaner was conditioned with the talloel as indicated. 45 Air was then allowed to enter the cell and re sulted in immediate formation of a compact, heavily mineralized froth of the siliceous mate rials. The froth was collected for 2.5 minutes, whereupon ?otation was complete. The rougher froth was cleaned by re-?cating in the same cell using tap water with additional caustic soda Reagent Rougher No. No. 1 No. No. No. No. No. 2 ' 1 2 3 4 5 Caustic soda (1011180.....‘. 60 Talloel .... ._ _. Time, min ..... .Q Pulp pH _______ _. to maintain alkalinity, Goulac to retard the re- ~ maining iron oxides, and talloel to insure ?ota~ ‘The slime-bearing pulp was conditioned with tion of the siliceous gangue, in each cleaning 65' caustic soda (commercial lye) and Goulac. Tall Q6]. was then added and the pulp again brie?y Y step. ‘The ?nal silica rejects, the combined iron conditioned as indicated. The rougher froth was concentrates from the cleaning steps, the rougher cleaned by re-?oating in the same cell using tap iron concentrates, and the untreated slime were water for dilution together with additional caus dried, weighed, and assayed. ' ‘ tic soda and Goulac.- The rougher and compos The results of the test follow: 60w ited cleaner iron concentrates and ?nal silica re d t Pro uc Weight, Assay'per cent‘ Jects were dried, weighed, and analyzed. Distribution mm‘ . The results of the test are as follows: A perwut Fe CaO Insoi. Fe CaO Insol. 65 mean Iron concentrates: Rougher ..... .. Cleaner ______ _. Slime 29.1 21.7 (un- 53.0 37.7 1.3 9.7 13.0 19.8 41.6 21.7 4.4 23.7 Amy 16.2 17.3 rm, ‘p8 Fe 0110 Insol. Distribution, P" “1" Fe CaO Insoi. \ treated) .... _. 28.6 44.0 8.3 17.8 33.4 26.8 20.5 Oomposite_---_ 79.4 45.9 6.1 16.9 96.7 54.9 54.0 70 Siiicarejeots _____ ._ 2L6 6.0 10.4 55.0 3.3 45.1 46.0 100.0 37.7 24.9 100.0 100.0 100.0 Composite feed ....... “h. Weight£ percen Q Rougher .... _. Cleaner _____ -_ Composite. ' . 8.9 Ironconcentrates: Elilicareiects .... .. The ?otation silica rejects accounted for 20.6 75 . 33.151.8 30.04a0 3.3 0.7 \ 16.1 41.5 20.1 44.0 10.1 22.8 21.4 29.8‘ '70.047.7 5.1 18.1 02.4 32.0 51.2 30.0 0.1 24.3 40.5 01.1 48.8 100.0aa1 10.0 24.91000 100.0 100.0 7.0 Com osite iee ..... -- accuser _ .. Flotation oi the silica from the slime-bearing - pulp rejected 48.8 percent of the silica (insolJ with a loss oi. only 7.6 percentoi the iron. It is from the iron oxides. , - vention include the metaphosphates, the poly. phosphates, sodlum silicate, sodium fluoride, and various vegetable tannin materials such as que~ bracho extract, oak extract, and Borneo cutch. The grade of the 'composited iron concentrates 10 recovered from ?otation tests On typical calcare Example III In the previously described examples of prac tice, a lignin sulphonate (Goulac) was employed to retard the iron oxides during anionic ?otation oi the naturally activated silica from either de 1.5 slimed or total charges or the ground calcareous red ore. ‘We shall now consider the results of ?o tation tests wherein auxiliary addition agents are employed to supplement the liin'sulphonates in the practice of our invention. _ so ous red ores using several of these auxiliary agents to supplement commercial lignin sulpha notes are given below. The red ores were ground to pass 100 mesh and ?oated by the procedure des scribed in Example 11. in the test to supplement the lignin sulphonate ' Product Inso]. 0.212 46-9 9-1 11-8 0H3} 48-6 8-6 no at 0.113 49-0 6-8 11-6 a: 3:2} 43-2 12-3 42-5 gtiitt?t‘ixlhusnntnuL 5:2 49-7 so as 91.8 a1 832mm::::::::::::::: . Rougher .... .Cleaner ..... ._ 45. 4 52. 8 28. 2 37. 0 Com ' ltd" 73.6 46.8 7.6 26.4 6. 7 20. 7 100.0 36. 2 11.0 Silica r9160 : percent ' 4. 2 l3. 0 Fe 0130 111501. 13. 0 60. 3 18. 3 28. 8 17. 3 33. 2 15. 0 95. 1 50. 5 44. 8 51.7 49.5 55.2 24.7 100.0 100 0 100.0 4.9 23. 9 20. 9 Composite d ..... ._ Fe m i8 41-8 5-1 or as t3 11 13-9 as t8 4“ W 12-7 95-0 M Example IV The ?otation tests heretofore reported were made on a typical calcareous iron ore containing siliceous gangue constituents naturally activated Fe 080 Insol. _ Iron concentrates: Distribution Recov Big-nil?! GaO spectively, in each step to retard the remaining iron oxides and yield the ?nal silica reject. ‘ ‘ Fe pounds per ton of feed, respectively. The rough Assay’per eem Assay, percent 53:13)‘: and aid retardation of the iron oxides. The quan 30 titles of caustic soda, causticized potato starch, S0°iiii‘.‘ttta;iu::::::::::::: ' lignin sulphonate (Goulac), and talloel employed in the roughing step were 2.8, 2.0, 3.0, and 0.8 5221;551:1311}: """" " er froth was cleaned 4 times using 0.5 and 0.1 $5 pound per vton of caustic soda and Goulac, re , . Depressant employed The results of a typical ?otation test on a 250 Efttlfisssasnasna: gram charge of the calcareous red iron ore ground to pass 100 mesh in a laboratory r mill go‘tt?'enséantssnui ‘ and the total charge ?oated by the procedure described in Example 11 are given below. Potato 25 gé’ii?taaseanztstnai starch solubilized with caustic soda to rupture the granules at room temperature and form a Eititifttitt‘éiannsnu: starch solution was used as. an auxiliary reagent Weight per con ' the lignin sulphonates in the practice of this in is applicable to both total and deslimed iron ore pulps. While we prefer to employ deslimed pulm in the practice of our invention, desllming is not . which have been employed in conjunction with therefore apparent that our method of ?otation obligatory for a satisfactory separation of silica it In addition to the starches and hydrolyzed starch products, other useful auxiliary agents A combination of the lignin sulphonate and causticized potato starch facilitated retardation ' ofboth the slime and granular iron oxides dur to soap ?otation. We shall now consider the ap plication of our method of ?otation to siliceous iron ores which contain unactivated siliceous ma terials; the silica in such ores is usually non ?oatable by anionic collectors, but can be ren dered ?oatable in the practice of our invention by the use of hydrated lime or metal-salt activat ing agents. , ‘A sample of rejects was obtained from an iron ore washer in the Mesabi range, Minnesota. ,.The sample as received was substantially‘ ?ner than 48 mesh, and was a" composite of classi?er alldq ing anionic ?otation of the activated silica. 55 dewatering device over?ows impractical to treat‘ Other cereal and tuber starches, such as corn, by methods of ?otation heretofore available. The sample contained hematite as the predominate iron oxide together with specular hematite and magnetite. The gangue was mainly quartz with tions or gels of the ruptured starch granules were . employed in other tests on the ore to supplement 60 some iron silicate minerals and clayey‘ material. A head analysis gave 40.9 percent Fe and 33.8 the lignin sulphonates. An optimum quantity of' ’ percent insoluble. the starches and lignin sulphonate gave results A 250-gram portion of the washer rejects was substantially identical to those recorded. The wet ground to pass 100mesh and deslimed at/20 utility of the starches and hydrolyzed starch prod microns by sedimentation and decantation using ucts for retarding iron oxides during anionic ?o the procedure described in Example I. The gran tation of activated silica from caustic alkaline ular portion was transferred to a laboratory me iron ore pulps is described in a co-pending appli chanical ?otation cell of standard design and cation, Serial No. 567,763, ?led December 11, 1944, diluted with tap water to give a. pulp containing by Julius Bruce Clemmer and Milton Friel Wil about 20 percent solids for ?otation. The pulp liams, Jr. Although the starches and hydrolyzed, was ?rst conditioned with hydrated lime to estab starch products are not obligatory in the prac lish a pulp pH of about 11 and activate the quartz tice of this invention, they are advantageous ad and silicate minerals to soap ?otation. The dition agents and enable an improved retardation lime-conditioned pulp was subsequently condi of the iron oxides with reduced quantities of the 75 tioned with soda ash to precipitate the hydrated lignin sulphonates. wheat, rice, arrow-root, and tapioca, solubilized by heat and/or chemical treatment to yield solu 2,403,481 '11 lime remaining in solution as insoluble calcium purpose of activating the silica to anionic ?ota tion while retarding ?otation of the iron oxides. A 250-gram charge of the rejects was ground and deslimed using the procedure described in Exam ple I. The granular portion was ?oated in a mechanical ?otation cell of standard design using the following reagents, expressed in conventional pounds per ton of ?otation feed: carbonate and simultaneously form caustic soda in the pulp. The resulting pulp, substantially free of dissolved lime, was then conditioned with Marathon M, a commercial magnesium lignin sulphonate marketed by the Marathon Chemical Company, and talloel, and then subjected to ?ota tion. The rougher froth was double-cleaned by re-flotating in the same cell using tap water for dilution together with additional caustic soda, 10' l Marathon M, and talloel in each step to retard Reagent the remaining iron oxides and yield a ?nal silica reject of low iron content. The quantities of reagents, expressed in conventional terms of Caustic soda ________ _. pounds per ton of ?otation feed, employed in the 15 Basie~calcium lignin test were as follows: sulphonate . . .._.__ Talloel ...... __ Conditioner Reagent- Rougher No. 1 No. 2 No. 3 No. ‘ 4 No. 1 No 2 20 Hydrated lime... Soda ash Caustic soda_-___ Marathon M _ _ 4. _ . _ _ -_ 0. 8 _- 1.1 0.3 0. 1 Time, min.. ___ 2. 5 2. 5 2. 5 2. 5 4.0 4.0 3.0 _ __ 11.2 11. 1 11.0 11.0 10.8 10.8 10.8 __ _ _ _ _ _ _ _ _ 1.1 0. 3 _ _ _ pp . _ . . _ _ 0. Talloel _ . . _ _ . 1 Cleaner Rougher No. 1 No. 2 No 1 No. 2 4. 4 ................ __ 0. s l 6. 0 ________________ -. 0. 4 0. 4 0. 1 0. 1 ___ ______ __ Time, min._.___ Pulp pH ............ _. Cle aner Conditioner . 2.5 11. 05 0.6 ________ ._ 2.5 ll. 0 2.5 ' l0. 9 2.5 10. 75 o. a 2.5 10. 8 The composited iron v concentrates recovered from the roughing and cleaning steps in the test assayed 58.4 percent Fe and 8.8 percent insol., and represented a recovery of 93.6 percent of the iron in the ?otation iced. The silica rejects as 25 sayed 9.3 percent Fe and 84.8 percent insoluble and contained 80.6 percent of the silica in the feed. The calcium salts contained in the com mercial basic calcium lignin sulphonate employed The grade and ‘distribution of iron and in in the test was "sufficient to activate the silica to soluble in'the test products were as follows: 30 anionic ?otation and the lignin portion retard the iron oxides. In the practice of our invention, Product we prefer, however, to employ supplementary Assay, per cent Distributiton, per Gen Weight per mm’; 'metal salt activating agents to insure more com plete activation and ?otation of the siliceous Fe Insol. Fe Iron concentrates: 35 gangue constituents. Insol. , Example VI 1' 7 Rougber ________ -- 49. 7 57. 2 7. 8 67. 7 11. 9 Cleaner _________ -_ » l7. 7 51. 7 l8. 1 21. 7 9. 8 67. 4 32. 6 55. 8 13. 6 10.5 78. 3 89.4 10. 6 21. 7 78. 3 A 250-gram portion of the Mesabi washer re jects was ground to pass 100 mesh and deslimed 40 at 20 microns by the procedure. described in Ex Composite ?ota ample‘ I. The granular portion was froth ?oated tion feed ____ .100. 0 42.0 32. 6 100.0 100. 0 in a mechanical cell to reject the silica and recover an iron enriched product using hydrated lime to Activation and ?otation of the silica from the activate the silica, Marathon NS, a commercial ground and deslimed sample rejected 78.3 per 45 sodium lignin sulphonate marketed by the Mara cent of the insoluble and enabled recovery of 89.4 thon Chemical Company, to retard the iron ox percent‘of the iron in concentrates which as ides, and talloel-as the collector for the activated sayed 55.8 percent Fe and 10.5 percent insoluble. silica. The reagent charge, expressed in pounds Similar results were obtained on the washer _ per ton of ?otation feed, employed in the test Composite ____ _. Silica rejects _________ __ rejects using other commercial lignin sulpho 50 was as follows: nates to retard the iron oxides during anionic ?otation’ of the calcium activated silica from caustic alkaline pulps. The grade and yield of iron concentrates from comparative tests with Conditioner Reagent . several lignin sulphonates using the previously 55 described ?otation procedure are as follows: Hydrated lime Caustic soda Marathon N S- Iron concentrates ‘ Assay, per cent Weight, Rougher No. 1 122.03%’ Fe No. 2 No. 3 5. 5 . 1. 5 . 3. 0 Talloel. _ _ Time, Lignin sulphonate , -- ‘ 0. 8 _- ........ -_- ________ _ _ 2. 5 2. 5 a5 a0 Pulp pH ..................... __ .10. 6 11. 0 11. 0 10. 85 60 A roughing treatment sufdced for an adequate separation of the activated silica from the re tarded iron oxides. The rougher iron concen Acid calcium lignin sulpho trates assayed 57.6 percent Fe and 8.1 percent at 54. 9 565 Neutral calcium lignin sul insol., and represented a. recovery of 85.7 percent phonate __________________ -_ 55. 6 Basic calcium lignin sul of the iron in the feed. The silica rejects rougher phonate __________________ __ 53. 0 froth assayed 16.0 percent Fe and 85.2 percent Sodium lignin sulphonate___ 54. 4 insol., and contained 62.2 percent of the insoluble in, the ?otation feed. Example V 70 In the recorded test, it will be noted that good ?otation of the silica was achieved from the iron A portion of the washer rejects containing un oxides in the presence of hydrated lime. Supple activated silica was next ?oated using a solution mentary experiments indicated that the ?otation of a commercial basic-calcium lignin sulphonate contained about 0.8 pound of dissolved hy that contained 12.0 percent of 08.0 for the dual 75 pulp drated lime .per ton of solids in the test. While per cent n e ...................... __ Fe Insol. - i3 we prefer that the ?otation pulp-be substantially free of dissolved hydrated lime in the practice of our invention, it is not obligatory that the ?o tation pulps be completely free 01' hydrated lime or calcium salts. Some calcium salts in the 110 tatlon pulp a_'e permissible, and, in fact, are ad vantage'ous in that they insure more complete _ notation of the silica. in carrying on our inven id many variations and modi?cations may be made . therein without. departing from the spirit of the invention. ‘What is claimed: \ ' ' l. A process for beneficiating calcareous iron ' ores containing siliceous gangue materials which comprises addition to an aqueous pulp of the conuted ore a quantity of caustic alkali to establish a pulp pH at least as alkaline as pHlG tion we prefer that the ?otation pulp contain not more than 100 parts per 'million of dissolved hy= "lid and a lignin sulphonate,‘ together with an anion active collecting agent selected from the class drated lime or calcium salts. . consisting of higher fatty acids, resin acids, and Example VI! mixtures of fatty and resin acids, and soaps A 250=gram portion of the washer rejects was ground and desllmed as previously described. The granular portion was conditioned with the equiv slant of 1? pounds per ton of hydrated lime. The lime-conditioned pulp which had a pH of 12.3 was then washed three times with tap water to thereof, and then subjecting said pulp to agitaw tion and aeration whereby siliceous gangue is heated and bene?ciated iron ore is depressed and recovered. 2. A process for heneilciating calcareous iron ores containing siliceous gangue materials which comprises addition to an aqueous pulp of the remove the hydrated lime remaining in solution. Y 20 comminuted ore a quantity of caustic alkali to a The resulting pulp which had a pH of 9.8 was sub establish a pulp pH at least as alkaline as pH 10 sequently transferred to a laboratory mechanical an iron oxide depressant selected from the‘ class ?otation cell and diluted with tap water to give consisting of crude and puri?ed metal salts of a pulp for ?otation containing about 20 percent lignin sulphonic acid, crude and puri?ed paper 25 solids. The pulp was conditioned with caustic mill sul?te liquors. and dehydrated residues soda, Goulac, and talloel, and then subjected to thereof, together with an anion active collecting ?otation to ?oat the lime-activated silica from agent selected from the class consisting of higher the retarded iron oxides. ,The rougher froth was fatty acids. resin acids, ures of fatty acids triple-cleaned by re-?oating in the same cell us and resin acids, and soaps thereof, and then ing tap water for dilution together with caustic 30 subjecting said pulp to agitation and aeration soda, Goulac, and talloel. The quantities of re whereby siliceous gangue is ?oated and bene? agents, expressed in terms of pounds per ton of’ ciated iron ore is depressed and recovered. ?otation feed, employed or the test were as fol v '3. A process for bene?ciating iron ores con lows: ’ 35 taining siliceous gangue materials which com prises addition to an aqueous pulp of the com Conditioner Reagent Cleaner Bougher No. 1 No. 2 Genetic is..- 2.8 Gnnlnn 4. 3 Tnlloel . _ _ Time, ___________ __ No. 1 No. 2 No. 3 1.1 1. 1 1.1 0. 6- 0. 6 0. 6 0. 1 4.0 0. 1 3.5 0. 1 2.5 l0. 8 10. 75 10. 85 ________ __ 2.5 0. 9 2.5 Pulp pH ............. _- ll. 1 11. 1 . 5.5 10. 7 minuted ore a quantity of caustic alkali to es itablish a. pulp at least as alkaline‘ as pH 19 adding thereto a basic-calcium lignin sulphonate 40 together with an anion active collecting agent selected from the class consisting of higher fatty acids, resin acids, mixtures of fatty and resin acids, and soaps thereof. and then subjecting said pulp to agitation and aeration whereby siliceous The grade and distribution of iron and insoluble 45 gangue is ?oated and fbene?ciated iron ore is depressed and recovered. > 1i. A process for bene?ciating iron ores con taining siliceous gangue materials which com prises conditioning an aqueous pulp of the com Product Weight, May’ New ' percent ' 50 minuted ore in the presence of su?icient hydrated per cent lime to yield a pulp with a pH of at least 19 and ' Fe Insol. Fe Insol. . containingnot more than 100 parts per million of dissolved hydrated lime, adding thereto a Iron concentrates: Rougher ........ __ 38. 8 55. 6 9. 9 51. 5 ll. li sulphonate and subjecting said pulp to Cleaner ......... . _ 33. 4 54. 0 l4. 6 ‘l3. 0 15. 55 agitation and aeration in the presence of an Composite .... .72. 2 54. 8 l2. 3 94. 5 27. in the test products were as follows: - Silica rejects ........ .- 27. 8 - 8. 2 Distribution 85. 4 5. 5 72. anion active collecting agent selected from the class consisting of higher fatty acids, resin acids, Composite iiote mixtures of fatty and resin acids, and soaps thereof, whereby siliceous gangue is ?oated and :bene?ciated iron ore is depressed and recovered. Activation and ?otation of the silica from the 60 5. A process for bene?ciating iron ores con ground and deslimed sample rejected 72.8 per‘ taining siliceous gangue materials which com cent of the silica and enabled recovery of 94.5 prises conditioning an aqueous pulp of the percent of the iron in concentrates which assayed comminuted ore, in the presence of su?lcient . tion iced .... -- 100. 0 41. 8 3?. B 100. 0 00.0 54.8 percent Fe and 12.3 percent insoluble. ’ hydrated lime to ‘yield a pulp with a pH of at Y The results of the previously described ?ota 65 lease 11, thereafter washing the conditioned pulp tion tests are typical of those we obtained on a with fresh water to yield a pulp containing not variety of ‘calcareous and siliceous iron ores us more than .100 parts per million of hydrated lime ing various crude and puri?ed lignin sulphonates remaining in solution, adding thereto su?lcient I as the iron oxide depressants while ?oating acti caustic alkali to establish a pulp at least as alka vated siliceous. gangue constituents from caustic 70 line as pHlO, and a lignin sulphonate, thereafter alkaline iron ore pulps Owith oleic acid, sodium oleate, talloel, sulfate soap, or similar anionic col lecting agents. While we have disclosed the pre subjecting said pulp to agitation and aeration in the presence of an anion active collecting agent selected from the class consisting of higher fatty ferred embodiments of our invention, it will be readily apparent to those skilled in the art that 75 acids, resin acids, mixtures‘ of fatty and resin 2,403,481. v I . 16 acids, and soaps thereof, whereb'y siliceous 7. A process for bene?ciating iron ores con gangue is ?oated and bene?ciated iron ore is depressed and recovered. , taining siliceous gangue materials which com prises addition to an aqueous pulp of the com minuted ore a quantity of caustic alkali to es tablish a pulp at least as alkaline as pH 10, and a soluble compound of an inorganic anion com . 6. A process of bene?ciating iron ores con taining siliceous gangue materials which com?’ prises conditioning an aqueous pulp of the com minuted ore in the presence of su?icient hy bined with a. polyvalent metal selected from the drated lime to yield a pulp with a pH of at least class consisting of calcium, magnesium, stron 11, adding thereto soda ash to precipitate the dissolved hydrated'lime and yield a pulp con 10 tium, barium, and lead, together with a lignin sulphonate and thereafter subject said pulp to taining not more than 100 parts per million of agitation and aeration in the presence of an hydrated lime remaining in solution, and adding ‘thereto a lignin sulphonate and thereafter sub jecting said pulp toiagitation and aeration in the ' anion active collecting agent selected from the class consisting of higher fatty acids, resin acids, _ presence of‘ an anion active collecting agent 15 mixtures of fatty and resin acids, and soaps thereof, whereby siliceous gangue is ?oated and selected‘ from the class consisting of higher fatty acids, resin acids, mixtures of fatty and resin acids, resin acids, mixtures of fatty and resin ac ids. and soaps thereof, whereby siliceous gamma is ?oated and bene?ciated iron ore is depressed 2o and recovered. 1 bene?clated iron ore is depressed and recovered. JULIUS BRUCE CLEMMER. CARL RAMIPACEK.