US2669545A - Methods of preparing flotation reagents - Google Patents

Description

Patented Feb. 16, 1954 METHODS OF PREPARING FLOTATION REAGENTS Frederick R. Archibald, Toronto, Ontario, Canada, assignor to United States Steel Corporation, a corporation of New Jersey N Drawing. Application July 5, 1951, Serial No. 235,359

Claims.

This invention relates to improved methods of preparing flotation reagents which consist essentially of collectors of the fatty acid type and colloidal silica and are substantially free of alkali metal ions.

My co-pending application Serial No. 172,197, filed July 5, 1950, describes and claims the foregoing type of reagents and also flotation methods involving their use. Briefly these reagents consist of about 0.06 to 0.6 part by weight of colloidal silica to one part by weight of a collector of the fatty acid type on an anhydrous basis; they have a mol ratio of silica to alkali metals of at least 25 to 1; preferably they are premixed. These reagents are particularly useful for floating iron oxide minerals from siliceous gangue, where colloidal silica is a highly effective agent for wetting and depressing gangue particles and allowing the collector to float the iron oxide mineral particles.

My aforesaid application defines collectors of the fatty acid type as including higher fatty acids, such as oleic acid, palmitic acid, linoleic acid, lauric acid, myristic acid, stearic acid and tariric acid; esters of the higher fatty acids, such as their glyceryl and glycol esters; resin acids, such as abietic acid, naphthenic acids; and various mixtures of the foregoing, but in each instance being substantially free of ions of alkali metals such as would be found in the sodium salts of the various acids. In the present application this same definition applies, but I also define "fatty acid material as including all the foregoing substances, as well as their alkali metal soaps. As sources of fatty acid materials, I prefer crude mixtures of fatty acids and resin acids, such as tall oil, which is sold under the trade names Opoil and Facoil, crude soap skimmings from the pulp and paper industry, or cottonseed foots, all of which have the advantages of ready availability and low cost.

An object of the present invention is to provide preparation methods which produce improved pre-mixed reagents in which collectors of the fatty acid type and colloidal silica of low alkali metal content are more highly dispersed, and which reagents have enhanced wetting action on siliceous mineral particles.

A further object is to provide simplified and improved methods of preparing such reagents in which preferably the components are pro-mixed and treated with an ion exchange medium to remove alkali metal ions, although without sacrificing all the benefits of the invention, these components can be treated separately with the ion exchange medium and either subsequently mixed or added separately to an ore pulp.

According to the preferred way of practicing the present invention, a fatty acid material first is mixed with sodium silicate. Said fatty acid material can be any of those previously mentioned. An example is Opoil in which the fatty acids are chiefly oleic, linoleic and palmitic and the resin acid chiefly abietic. The fatty acid content is about 46 to 48.5% and the resin acid content about 42.2 to 45% (calculated as abietic). The sodium silicate can be any of the commercially available preparations. Such preparations commonly have a mol ratio of SiOz to NazO of about 3.2 to 1, a specific gravity of about 40 to 43 Baum, and. contain roughly 30% S102. An example is Philadelphia Quartz Company N brand. The proportions used are equivalent to about 0.06 to 0.6 part by Weight of SiOz to 1 part by weight of collector of the fatty acid type as produced in .the subsequent ion exchange reaction. Many of the fatty acid materials, such as the soaps, are readily dispersed in sodium silicate solution without additional dispersing agents, but where needed, as With the acids themselves, alkali or ammonium hydroxide can be added either in this first mixing step, or previously to the fatty acid, to act as a dispersing agent.

Next the mixture is diluted with water and roughly emulsified to form a solution having a maximum S102 content of about 1.5%. In the example of Opoil and N brand sodium silicate, if the solution is diluted to 1% Opoil, the maximum concentration of N brand sodium silicate (30% SiOz) is about 5%, or if the solution is diluted to 1% N brand sodium silicate, the maximum concentration of Opoil is about 5%, to produce satisfactory reactions with the ion exchanger. The actual proportions used give the ratio of 0.06 to 0.6 part by weight of SiOz to 1 part by weight of collector of the fatty acid type in the finished reagent, these maximum concentrations being merely those that react satisfactorily with the ion exchanger.

Next the solution thus prepared is treated with an acid type ion exchange medium. This medium can be of any of the Well known substances which are capable of exchanging hydrogen ions for sodium ions present in the sodium silicate, in the fatty acid material, and in the dispersing agent if used. Examples of such substances are natural and synthetic zeolite and certain synthetic resins which have hydrogen atoms in ion exchange positions, such as the phenolic resin sold by the trade name Amberlite lR-lOOH. Either the solution can be passed through a bed of ion exchanger or else granules of the exchanger can be agitated with the solution. During such treatment the ion exchanger acquires alkali metal ions from the solution, but can be regenerated by treatment with an acid, as known in the art.

ti'oduce additional colloidal silica to the resulting product. This practice is particularly useful where the desired ratio of colloidal silica to collector is higher than desired for treatment with The effluent from the ion exchange is a highly 5 the ion exchanger. dispersed solution of colloidal silica and collector Specific examples of ways in which reagents of the fatty acid type and has a very low content can be prepared according to the present invenof alkali metal ions, that is, a mol ratio of silica tion and used in flotation processes are as folto alkali metals of at least 25 to 1. The pH of the lows: original solution varies from to 12 and that of 10 the effluent from 2.5 to 3.5. The solution can be EXAMPLE I stabilized by addition of a small amount of so- 10 ram ofcrude tall oil (Opoil) was mixed dium silicate as long as the alkali metal ion con- Wi h 10 gr ms of sodium silicate solution (Philatent is maintained within the limits hereinbefore delp Quartz p y. N brand). The mixstated. This solution can be used as a flotation 15 t was diluted with a little water, warmed on reagent in the manner described and claimed in a hot plate, and shaken until roughly emulsified. my aforesaid application; that is, it can be mixed T miXture W d uted to 1 liter with Water with a. finely divided pulp of iron oxide ore and and stirred With an electric stirrer until unisiliceous gangue, which then can be treated in formly mixed. Next it Was Passed through a any standard or desired flotation cell. The 001- acid p n h n lumn and the r sultin loidal silica effectively wets and depresses the Product Was a milky l d mu siongangue, while the collector of the fatty acid type A samp of classifier lmderfiOW from a Closed floats the iron xide minerals circuit grinding and classification operation on Pro-mixing the components before treating taconite ore was selected for treatment. A rethem with the ion exchanger produces a more agent p p as j t de c bed was added to highly dispersed and active reagent than when the Sample in an amount equivalent to Pound the components are mixed after s ch t t t tall oil and 0.81 pound sodium silicate solution or added separately to an ore pulp. While I do (approximately p d Co lo al Sil ca On an not wish to limit myself to any particular theory, enhydrells basis) D Ions ten o olids in the I believe this improvement is due at least in part Sample In accordance With the third p s il ty to the formation of the colloidal silica in the described hereinbefore, addit o al colloidal silica presence of fatty acid ions. According to this was introduced an nt qu v l nt t 1 theory, the wetting action of colloidal silica on p nd um s i t ti n appr x at ly siliceous gangue is due partially to its afiinity to 0.25 pound colloidal silica on an anhydrous basis) calcium ions which usually are associated with D i; ten of SelidS- After pp p mixing this gangue. Fatty acid ions are known to have the sample was tr d y fleatiel'l and O a strong affinity for calcium ions. Colloidal silica the samp Weight a recovered as a flotation molecules which are formed in the presence of Concentrate a say n 3.5% Fe and 6.0% acid infatty acid molecules tend to conform in physcial soluble residue. This concentrate was recoverd structure to the latter and consequently acquire 40 at a much coarser particle size and a higher some of the affinity of fatty acid ions for calcium grade than was being obtained in the regular ions, becoming in effect tailor-made molecules. opertion after grinding much finer and using Some of the benefits of the present invention magnetic separators for treatment of classifier can be achieved by treating a fiatty acid material overflow. Screen analyses and grades of concenalone with an ionic exchanger and then either trates obtained by flotation of the classifier unmixing it with previously prepared colloidal silica derfiow and magnetic separation of the clasifier or adding the two separately to an ore pulp. In overflow were as follows:

Magnetic Flotation, Mesh Sue tiiigiii (figfixg Separator Concentrate 66323; Cumulative Fe Insol Fe/Insol Fe Insol Fe/lnsol i l iatir'f'. -99 1 4 7- 9-! this instance the fatty acid material can be any of EXAMPLE II those previously mentioned, and it is treated in concentrations up to 20% with any of the same ionic exchangers. This alternative way of practicing the invention retains the benefits of substantially eliminating alkali metal ions and of producing a highly dispersed collector of the fatty acid type, but of course it loses the advantages gained by forming the colloidal silica in the presence of fatty acid.

A third possibility is to pre-mix the fatty acid material and sodium silicate and treat them together with the ion exchanger, as in the preferred practice already described,- and then to in- The fatty acid material was soap skimmings, a by-product of the pulp and paper industry containing alkali metal compounds of fatty and resin acids, as well as other degradation products of pulp wood and inorganic salts incidental to the manufacturing process. 10 grams of soap skimmings were mixed with one liter of colloidal silica solution containing the silica equivalent of 10 grams of N brand sodium silicate. The mixture was stirred with a motor stirrer until thoroughly dispersed and then passed through an acid type ion exchange medium set up as a column in a glass tube. The effluent was used as a flotation reagent in the manner next described.

A sample of iron ore classifier underflow containing approximately 1300 grams of solids and representing the circulating load in a grinding and classification circuit was placed in a laboratory flotation cell and conditioned with 100 ml. of the efliuent thus prepared for 6 minutes. The pulp was diluted to the normal operating level and froth removed. The rougher concentrate was returned to the cell and twice re-cleaned, producing a cleaner concentrate assaying 65.25% Fe and 5.64% acid insoluble residue, equal in weight to 30.8% of the original sample. The reagents used were equivalent to 1.74 pounds each of soap skimmings and sodium silicate solution (0.52 pound of colloidal silica on an anhydrous basis) per long ton of solids.

For comparison, to show the advantage of premixing the fatty acid material and sodium silicate and treating them together with the ion exchanger, a similar ore sample was treated by flotation with these agents prepared by separate treatment with an ion exchanger. Other conditions were identical. This treatment yielded 28% of the weight of the sample as a concentrate assaying 64.05% Fe and 6.2% acid insoluble residue.

From another sample of classifier underflow taken under different operating conditions and using the pre-mixed reagent of the present example, 42.8% of the sample weight was recovered as a concentrate assaying 65.85% Fe and 5.66% acid insoluble.

EXAMPLE III For comparative tests two reagents were prepared similarly except that the first lacked treatment with an ion exchanger. This first reagent was prepared by mixing 1 gram of ammonium hydroxide with grams crude tall oil, warming and then diluting to one liter. 10 grams N brand sodium silicate was diluted with water to a volume of 1 liter. Equal volumes of ammoniatall oil and diluted sodium silicate were mixed and produced a cloudy and somewhat viscous solution. The second reagent was prepared by passing some of this same solution through an acid type ion exchange medium. I

For comparison of the effectiveness of the two reagents, a sample classifier underflow as described in Example I was divided into two por tions containing approximately 800 grams of solids each. In each flotation test the pulp was added to a laboratory flotation cell and conditioned with 150 ml. of reagent solution. Flotation and one re-cleaning were carried out on each utilizing the two reagents prepared as described, following usual procedures and without further reagent additions. The results were as follows:

Percent Analysis Concentrate Weight as Concentrate Fe Inso] Fe/Insol Firs Reagent 46. 5 61.35 7. 94 7.73 Second Reagent 46. 6 64.05 6. 30 10.17

6 EXAMPLE IV 10 grams of soap skimmings were diluted with stantially all dissolved or dispersed. The mixture was run through an acid type ion exchanger set up in a vertical glass tube 2 inches in diameter. The column of ion exchange resin (Amberlite 1R-100H) was 15 inches high. The

effluent from the exchanger was used as a flotation collector in conjunction with colloidal silica having a mol ratio of silica to alkali metal ions of at least 25 to 1.

A sample of classifier underflow pulp was taken from a closed circuit as in the preceding examples and split to give representative portions of about 1360 grams of solids each. One such portion was placed in a laboratory flotation cell and conditioned with 50 m1. colloidal silica solution for three minutes. The colloidal silica solution contained silica equivalent to approximately 3 grams $102 per liter. '75 ml. of the fatty acid collector next was added and conditioning carried on for five minutes more. The pulp level was raised to normal operating level by addition of water. Froth was removed for 5 minutes. The rougher concentrate thus obtained was returned to the cell using the original flotation liquor for dilution, and again froth was removed in the usual Way. One more re-cleaning was performed in the same manner. The total reagents used were equivalent to 1.30 pounds soap skimmings and 0.86 pound sodium silicate (0.26 pound silica on an anhydrous basis) per long ton of ore. The sodium silicate had been converted to colloidal silica solution by passing diluted water glass through an acid type ion exchanger. The flotation resulted in a recovery of 33.4% of the weight of the sample in a concentrate assaying 64.65% Fe and 6.54 acid insoluble residue.

EXAMPLE V A similar sample of classifier underflow was treated by flotation with the same reagents in larger quantities, namely, the equivalent of 2 pounds of soap skimmings and 1 pound sodium silicate (0.30 pound silica on an anhydrous basis) per long ton of ore. By one re-cleaning of the rougher concentrate, 59.1% of the total sample weight was recovered in a product assaying 63.8% Fe and 7.24% acid insoluble.

From the foregoing description it is seen that the present invention affords a simple method of preparing a highly effective reagent for floating iron ore minerals from siliceous gangue. As best shown by the comparative tests of Example II, reagents in which the fatty acid type material and sodium silicate are mixed together before treatment with the ionic exchanger produce better results than reagents in which the two are separately prepared, although the latter still are effective reagents.

While I have described only certain preferred ways of practicing the invention, it is apparent that modifications may arise. Therefore, I do not wish to be limited by the specific disclosure, but only by the scope of the appended claim.

I claim:

1. A method of preparing pre-mixed flotation reagents, which consist essentially of collectors of th fatty acid type and colloidal silica in proportions of about 0.06 to 6.6 parts by weight of colloidal silica to one part by weight of collector on an anhydrous basis and have a mol ratio of silica to alkali metals of at least 5 to 1, comprising treating sodium silicate and an alkali 7 metal soap of an acid ofuthe group consisting of higher fatty acids, resin tion, with an acid type ion exchange medium which removes alkalimetal ions therefrom.

2. A method as defined in claim 1 in which the dilute water solutions of soap and sodium silicate are mixed together before treatment with the ion exchange medium.

3. A method. as defined. in claim .1 in which the dilute. water solutionsof soap and sodium silicate ar treated separately with the ion eX- change medium and subsequently mixed.

4. A method of preparing pre-mixe'd flotation reagents, which consist essentially of collectors of the fatty acidtype and colloidal silica inproportions of about 0.06 1100.6. parts-by Weight of colloidal silicav to one ,part by weight of collector. on an anhydrous basis and have a mol ratio of silica to alkali metals of at least 25. to 1, comprising mixing .water solutions of .sodium silicate and an alkalimetal. soap of an acid of.

acids, naphthenic acids. and mixturesthereof, both,in dilute,watersoluthe group consisting of higher fatty acids, resin acids, naphthenic acids. and mixtures thereof, di-

luting the mixture with water to a maximum thenicacids and mixtures thereofpand thus removing alkali metal ions therefrom.

FREDERICK "R. ARCHIBALD.

References Cited' in the file of thispatent UNITED. STATES PATENTS Number Name Date 1,326,855 Edserv Dem 30, 1919v 1,492,904 1 Sulman'et-al; May 6; 1924 3,164,063 -..-Handy l June 27, 1939 OTHER REFERENCES NachodIon Exchange-pub. 1949 by AcademicPress of N. Y-.-p. 365 copyinDiv. .63.

an acidof, the group consisting of higher fatty acids, resin acids, naph-

Claims (1)

1. A METHOD OF PREPARING PRE-MIXED FLOTATION REAGENTS, WHICH CONSIST ESSENTIALLY OF COLLECTORS OF THE FATTY ACID TYPE AND COLLOIDAL SILICA IN PROPORTIONS OF ABOUT 0.06 TO 0.6 PARTS BY WEIGHT OF COLLOIDAL SILICA TO ONE PART BY WEIGHT OF COLLECTOR ON AN ANHYDROUS BASIS AND HAVE A MOL RATIO OF SILICA TO ALKALI METALS OF AT LEAST 25 TO 1, COMPRISING TREATING SODIUM SILICATE AND AN ALKALI METAL SOAP OF AN ACID OF THE GROUP CONSISTING OF HIGHER FATTY ACIDS, RESIN ACIDS, NAPHTHENIC ACIDS AND MIXTURES THEREOF, BOTH IN DILUTE WATER SOLUTION, WITH AN ACID TYPE ION EXCHANGE MEDIUM WHICH REMOVES ALKALI METAL IONS THEREFROM.