CA1265265A - Frother composition and a froth flotation process for the recovery of mineral - Google Patents

Abstract

ABSTRACT
A frother composition and a process for recovering mineral values from ore by subjecting the ore, in the form of an aqueous pulp, to a flotation process. The frother composition comprises the reaction product of 1) a polyhydroxy C1-20 alkane or polyhydroxy C3-20 cycloalkane, and 2) propylene oxide or a mixture of propylene oxide and ethylene oxide, with the proviso that at least 50 mole percent of a mixture is propylene oxide, wherein the reaction product has a molecular weight of between 150 and 1400. The frother composition and process of the invention is particularly effective in the floatation of fine mineral values wherein 75 percent or more of the ore comprise particles of a size of 75 micrometers or less.

33,232-F

Description

t`~i FROTHERS USEFUL IN TH:E RECOVERY OF FINE
PARTICLES OF ~ETAL VALUES IN FROTH FLOTATION

The i~vention resides in a frother com-position and a froth flotation process for the recovery of mineral values from ore. The process o this i~vention is not only effective in beneficiating ores in general but is also effective in the benefi-ciation of ores having a particle size of 75 micro-meter6 or le~s. Fine particle size ores are generally xe~erxed to in khe art as slimes.

The frothe.r composi~ion and pxocess of the invention are capable of selectively recoverlng the fine particles o~ mineral ~alues from ores con-taining me-tallic or non-metallic mineral values without carrying over undersirable portions of the ore, i.e. gangue, in the fxoth.

In the recovery of fine mineral values from ore, about 75 percent of the ore has a particle size of 75 micrometers or less. Preferably, 80 percent of ~' 33, 232 F

,`i ~

the ore has a particle size of 75 micrometers or less, and most preferably, 90 percent of the ore comprises particles having a siæe of 75 micrometers or less.

The ine par~icle size ores useful in this invention can be prepared by classifying the ore, i.e.
by separating the fine particles rom the medium and large;par~icles. This can be done by the use of a sieve of the appropria~e size or the use of a hydro-cyclone or other metho~s known in the art. Altexna-tively, the ore can be comminu~ed until the ore com-prises the desired perce~tage of fine particles. Com-minution refers to the size reduction of orPs. This can be achieved by one of several means known in the ar~, for example, grinding the ore in a rod mill.
Alternatively, flotation can be performed in a two--circuit syst~m wherein the large and medium size mineral value par~icles are recovered in a firs t step froth flotation process and the tailings which contain mineral values o a ~ine particle size can then be recovered by second s~ep froth 10tation process using the frother composi tion and process o this inv~ntion.

The term "ore" refers herein to the ore as it is taken out of the ground and includes the mineral values in admixture with the gangue. Gangue refers herein to those materials which are of no value and which need to be separated from ~he mineral values.
The frother composition and process of the invention can be used to recover metal oxides, metal sulfides and other metal values.

Froth flotation is a commonly employed process for concentrating mineral values from ores. In a flo-tation process, the ore is crushed and wet ground to 33,232-F -2-obtain a pulp. A frothing agent, usually employed with a collecting agent, is added to an aqueous ore pulp to assist in separating valuable minerals from the unde-sired or gangue portions of the ore in subse~uent flo-tation steps. The pulp is then aerated ~o produce afroth a~ the surface thereof and the collector assists ~he frothing agent in separating the mineral values from the ore by causing ~he mineral values to adhere to ~he bubbles fonmed during this aeration step.
The adherence of the mineral values is selectively accomplished so that the portion of the ore not containing mineral values, i.e. the gangue, does not adhere to the bubbles. The mineral-bearing froth is collected and furthex processed to obtain the desired mineral values.
That portion of the ore which is not carried over with the froth, usually identified as "flotation tailings", is usually not further processed for extraction of mineral values therefrom. The frother composition and process of the invention i5 generally applicable -to ores containing metallic or non-m~tallic mineral values.

In froth flotation, it is yenerally desir-able to recover as much of the mineral values as pos-sible from the ore while efecting the recovery in a selective manner, that is, without carrying over unde-sirable portions of the ore, i.e. ~he gangue, in thefroth. While a large numbex of compounds have foam or froth producing prope~ties, the frothers most widely used in commercial froth flotation operakions are mono-hydroxylated compounds such as C5 8 alcohols, pine oils, cresols and Cl 4 alkyl ethers of polypropylene glycols as well as dihydroxylates such as polypropylene glycols.
The frothers most widely used in froth flotation opera-tions are compounds containing a non-polar, water-33,232-F -3-g_ -repellent group and a single, polar, wa~er-seeking group such as hydroxyl (OH). Typical of ~his class of fxothers are mixed amyl alcohols, methylisobutyl carbinol, he~yl and heptyl alcohols, cresols, ter-pineol, and the like. Other efective frothers usedcommercially are the Cl 4 alkyl ethers of polypropylene glycol, especially the methyl ether and the polypropylene glycols o~ 1~0-2100 molecular weight and particularly those in thé 200-500 range. In addition, cer~ain alkoxyalkanes, e.g., triethoxybutane, are used as fro~hers in the flotation of certain ore~.

Although mineral value recovery improvements from a preferred frother in the treatment of an ore can be as low as only about 1 percent over other frothers, this small improvement is o great importanc~ ec~nomic~
ally since commercial operations often handle as much as 50,000 tons o ore daily. With the high throughput rates noxmally encountered in commercial flotation pxocesses, relatively small improvements in the rate of mineral value recovexy result in the recovery of additional tons of mineral values daily. Obviously then, any frother which promotes improved minexal value recovery, even though it is by a small per-centage, is very desirable and can be highly advan-tageous in commercial flotation operations.

It is well-known in the practice of froth flotation, that the recovery o fine (slime) particles of mineral values with a reasonable selectivity in favor of the mineral values over the gangue is quite difficult.
Normally the problem is not one of achieving high recovery of the valuable component i.e. the mineral value, but rather one of accepting a much lower than desired recovery 33,232-F _~

,~ r ~
J~ J~'~3 of the mineral values so as to achieve a product of an acceptable quality or grade (selectivity). In practice, it is normally found that as the recovery of the fines of the mineral values increases, the quality of ~he product ~selectivity) dramatically decr ases. Thus, an economic optimization occurs between increasing the amount of recovered product versus the drop in product value with the decreasing product yrade.

Accordingly, the present invention provides an improved frother co~positio~ and a process for a substantially higher recovery of fine particles of mineral values by froth flotation. Frothers of the invention are capable of the selective recovery of the ine particles of mineral values, having a par-ticle ~ize of 75 micrometers or less.

The invention particularly resides in a flo-tation froth~r composition for recovering mineral values from an aqueous ore pulp, wherein 75 percent or more o the raw ore comprises particles of a size of 75 micrometers or less, said frother comprising the reaction product of 1) a polyhydroxy alkane having from l to 20 carbon atoms or a polyhydroxy cycloalkane having from 3 to 20 carbon atoms and 2) propylene oxide or a mixture of propylene oxide and ethylene oxide, with the proviso that at least 50 mole percent of ~he mixture is propylene oxide, and wherein the reaction product has a molecular weight of from 150 to 1400.

Another aspect of this invention resides in a process for recovering mineral values from ore, wherein 75 percent or more of the ore comprises par-ticles of a size of 75 micrometers or less, wherein 33,232-F -5-the ore, in the form of an aqueous pulp, is subjected to a flotation process in the presence of a flotation collector and a flotation frother, charac-terized in that the frother comprises the reaction product of 1) a polyhydroxy al~ane having from 1 to 20 carbon atoms or a polyhydroxy cycloalkane having from 3 to 20 carbon atoms and 2) propylene oxide, or a mixture of propylene oxide and ethylene oxide, with the pro-viso ~hat at least 50 mole percent of the mixture is propylene oxide, wherein the reaction product has a molecular weight of from 150 to 1400.

The frother composition and process of this invention results in a surprisingly high recovery of mineral values wi~h a high selectivity toward the mineral values i~ preference to the gangue. Critical to this recovery are rothers which are not only useful for floating mineral values o~ large o~ medi~ size par--ticles but are also particularly ef~ective in the flo-tatiun of the ine particle sizes i.e. a particles size of 7S micrometers or less, resul~ing in an enhanced selectivity in favor of the fine mineral values over ~he gangue.

In a preferred embodiment, the reaction product of the invention corresponds to -the formula R~o tcH-cHo~nH)Tl, wherein R is a C1_20 alkane or a C3_20 cy radical; Rl is hydrogen or methyl; m is an integer of from 3 to 10; and n is a number of from 1 to 8;

33,232-F -6---7~

with the proviso that each ether unit can contain only one methyl group, and with the further proviso that at least 50 percent of ~he ether units must have one methyl group.

Any polyhydroxy Cl 20 alkane or polyhydroxy C3 20 cycloalkane which will react with propylene oxide, or a mixture of ethylene oxide and propylene oxide, can be used in this inventio~. Polyhydroxy C3 12 alkanes polyhydroxy C3_12 cycloalkanes are preferred. Poly-hydroxy C3 6 alkanes and polyhydroxy C5 ~ cycloalkanes are more preferred with trihydroxy propa~es being most preferred.

The polyhydroxy alkanes and polyhydroxy cycloalkanes useful in thi5 invention include those which correspond to the formula R~O~)m wherein R and m a:re as herei~before deined. Desirable polyhydroxy alka~es inc~ude ~he trihydroxy ethanes, trihydroxy propanes, trihydroxy butanes, trihydroxy pentanes, trihydroxy hexanes, trihydroxy heptanes, txihydroxy octanes, diglyc~rol, sorbitol, pentaerythritol, a monosaccharide, a disaccharide, sucrose or mixtures thexeo. More preferred polyhydroxy alkanes include the trihydroxy propanes, trihydroxy butanes, tri hydxoxy pentanes, and trihydroxy hexanes. A most preferred polyhydroxy alkane is trihydxoxy 1,2,3-propane.
Poly refers herein to 3 or more. The alkane polyols include C~ 20 alkanes containing from 3 to 10 hydroxyl moieties, inclusive, more preferably from 3 to 8 hydroxyl moieties, inclusive, even more preferably from 3 to 6 hydroxyls, inclusive, and most preferably 3 hydroxyls.

33,232-F .7_ The polyhydroxy Cl_20 alkanes or polyhydroxy C3 20 cycloalkanes are reacted with either propylene oxide ox a mixture of ethylene and propylene oxide wherein such mixture contains at least 50 mole percent of propylene S oxide. The alkylene oxides generally correspond to the formula ; RlC~- CHR

wherein Rl is as hereinhefore defined, wi~h the proviso that only one Rl can be methyl. Preferably, the polyhy-droxy Cl_20 alkane or polyhydroxy C3 20 cycloalkane is reacted with propylene oxide. In the hereinbefore pre-sen~ed formulas, R is preferably a C3 12 alkane radical or C3 12 cycloalkane radical, more preferably C3 6 alkane radical or C5 8 cycloalkane radical, and most preferably a C3 alkane radical. Preerably, m is an integer of from 3 to 8; more preerably an integer of from 3 to 6 and most ~referably 3. ~referably, n is from 1 to 4, and most preferably from 1 to 3.

The frothers of this invention can be pre-pared by contacting a polyhydroxy C1 20 alkane or polyhydroxy C3_20 cycloalkane with the appropriate molar amount of propylene oxide, or a mixture of ethylene oxide and propylene oxide, in the presence of an alkali catalyst such as an alkali metal hydroxide, an amine, or boron trifluoLide. Generally, from 0.5 to 1 percent of the total weight of the reactants of the catalyst can be used. In general, temperatures of up to 150C and pres~ures of up to 689 kPa can be used for the reaction. In the embodiment wherein a mixture of propylene and ethylene oxi.d~ is used, 33,232-F -8--the propylene and ethylene oxide may be added simul taneously or in a seguential manner.

The polyhydroxy Cl_20 alkane or polyhydroxy C3 ~0 cycloalkane is reacted with a sufficient amount of propylene oxide or a mix~ure of e~hylene oxide and pro-pylene o~ide 50 as to prepare a reaction product of the desired molecular weight, i~ particular, a molecular weight of from 150 to 1400, more preerably from 200 to 800, and most preferably from 250 to 500.

Sulfide ores for which the compounds of ~he invention are useful include copper sulfide-, zinc sulfide-, molybdenum sulfide-, cobalt sulfide , nickel sulfide-, lead sulfide-, arsenic sulfide-, silver sulfide-, chromium sulfide-, gold sulfide-, platinum sulfide- and uranium sulfide-containing ores. Examples of sulide ores from which metal sulfides may be concentrated by froth 1O-tation usin~ the process o this i~ven~ion include copper-bearing ores such a~, for example, covellite (CuS~, chalcocite (Cu2S), chalcopyrite (CuFeS2), val-leriite (Cu2Fe~S7 or C~3Fe4S7), bornite (Cu5FeS4), cubanite (Cu2SFe~S5), enargite (Cu3(As1Sb)S4), tetra-3SbS2), ~ermantite (CUl2As,~,sl3), brocharltite ~CU4(0H)6S04), antlexite (Cu3S04(0H)4), famatinite (CU3(SbAS)S4), and bournonite (PbCUSbS3); lead-bearing ores such as, for example, galena (PbS); antimony-bearing ores such as, for example stibnite (Sb2S3); zinc-bearing ores such as, or example, sphalerite (ZnS); silver--bearing ores such as, for example, stephanite (Ag5SbS4), and argentite (Ag2S); chromium-bearing ores such as, for example, daubreelite (FeSCrS3); and pla~inum-and palladium-bearing ores such as, for example, cooperite (Pt(AsS)2).

33,232-F _g_ d~`~5i Oxide ores for which this process is useful include copper oxide-, aluminum oxide-, iron oxide-, iron titanium oxide-, magnesium aluminum oxide-, iron chromium o~ide-, ti-tanium oxide-, manganese o~ide-, tin oxide-, 5 and uranium oxide-containing ores. Examples o oxide ores from which metal oxides may be concentrated by froth flotation usin~ the process of this in~ention include copper-bearing ores r such as cuprite ~Cu20), tenorite (CuO), malachite ~Cu2(0H)2C03), azurlte ~Cu3(0H)2(C03)2), ~0 atacamite (CU2C1(0~)3), chrysocolla (CuSiO3); aluminum-bearing ores, such as corundum;- zinc-con~aining ores, such as zincite (ZnO), and smithsonite ~ZnC03); iron-containing ores, such as hematite and magnetite; chromium-containing ores, such as chromite (FeOCr203); iron- and titanium-containing or~s, such as ilmenite; magnesium-and aluminum-containing ores, such as spinel; ironchromium-containing ores, such as chromite; titanium-containing ores, such as rutile; mangane~e-containing ores, such as pyrolusite; tin-containing ores, such as cass.i-~erite; and uranium-containing ores, such as urani~
nite; and uranium-bearing ores such as, or example, p.itchblende (U205(U308)) and gummite (U03nH20). Other metal values for which this process is useul include gold-bearing ores, such as sylvanite (AuAgTe2) and calaverite (AuTe); platinum- and palladium-bearing ores, such as sperrylite (PtAs2); and silver-bearing ores, such as hessite (AgTe2).
.
In a preerred embodiment o,f this invention, oxide- or sulfide-containing values are recovered. In a more preferred embodiment of thi~ invention copper sul-fide, nickel sulfide, lead sulfide, zinc sulfide or molybdenum sulfide values are recovered. In an even more preferred embodiment, copper sulfide values are recovered.

33,232-F -10-,,~i ~11--The amount of the frother used or fro~h flotation depends upon the type, the grade and the size of the ore particles and the particular frother used. Generally, that amount which separates the desired mineral values from the ore is suitable. It has been discoverPd that less than 0.05 kg/metric ton can be used. Preferably, an amoun~ of from 0.0025 to 0.0~ kg/metric ton is used. Most pre-ferably, an amount of from 0.005 to 0.05 kg/metric ton is used. The fro~h flotation process of this invention, usually xequires ~he use of collectors.
Any collector well-known in the art, which results in the recovery of ~he desired mineral value is suit-able. Further, in the process of this invention it is contemplated that the frothers of this invention can be used in mixtures with other frothers known in the art.

Ex~mples of collectors useful in this inven-tion include alkyl mono~hiocarbonates, alkyl dithiocar-bonates, alkyl trithiocarbonates, dialkyl dithiocar-bamates, alkyl thionocarbamates, dialkyl thioureas, monoalkyl dithiophosphates, dialkyl and diaryl dithiophosphates, dialkyl monothiophosphates, thiophos-phonyl chlorides, dialkyl and diaryl dithiophosphona~es, al~yl mercaptans, xan~hogen formates, xanthate esters, mercapto benzothiazoles, fat~y acids and salts of fatty acids, alkyl sulfuric acids and salts thereof, alkyl and alkaryl sulfonic acids and salts ~herecf, alkyl phos-phoric acids and salts thereof, alkyl and aryl phosphoric acids and salts thereof, sulfosuccinates, sulfosuccina-mates, primary amines, secondary amines, tertiary amines, 33,232-F -11-.

r ~12~

quaternary ammonium salts, alkyl pyridinium salts, quani-dine, and alkyl propylene diamines. Furthermore, blends of such kno~n collectors can be used in this invention also.

The frothers described hereinbefore can be used in admixture with o~her well known frothers.
Example~ of such frothers include C5 8 alcohols, pine oils, cresols, C1~4 alkyl ethers of pol~propylene glycols, dihydroxylates of polypropyle~e ylycols, glycols, fatty acids, soaps, alkylaryl sulfonates, and ~he like.
Furthe.rmore, blends of such frothers may also be used.
~11 frothers which are suitable for beneiciation of ores by froth flotation can be used in ~his invenkion.

The frothers of this i~vention result in selectivity improvements o 5 percent or more over ~hose selectivities achieved using e.g. methylisobutyl carbinol (MI~C) at the same recovery levels, pre-ferably a 10 percent selectivity increase, and most preerab1y a 20 percent selectivity inc~ease.

The following examples are included for illustration and are not intended to limit the scope o the invention or claims. Unless otherwise indi-cated, all parts and percentages are by weight.

In the following examples, the performance of the rother compositions described hereinbefore is shown by giving the ra~e constant of flo~ation and the amount of recovery at infi~ite time. These numbers are calculated by using the ormula 33,232-F -12 : .

D~;D~

r = R~ [1 Kt ]

wherein: r is the amount of mineral value recovered at time t; K is the ra~e constant for t~e rate of recovery, and R~ is ~he c~lculated ~mount of the mineral value which would be recovered at i~finite time. The amoun~ recovered at various times is detenmined experimen~ally and ~he series of values are substituted into the equatlon to obtain R~ and K.
The above fonmula is explained in "Selection of Chemical Reagents for Flotation"by R. Klimpel, Chapter 45, pp. 907-934, Mineral Processing Plan Design, 2nd Ed., 1980, AIME (Denver).

Example_1 In this example three fro~hers are tested for 1Otation o copper sulfide values. A 500-g quan-ti-ty of Pinto Valley copper ore, iOe. chalcopyrite copper sulfide ore, is plac~d in a rod mill with 2S7 g of deionized water. The copper ore comprises ~0.2 perce.nt with a par~icle si2e of about 75 micro-meters or less. A ~uantity of lime is also added ~o e rod mill, based on the desired pH for the subse-~uent flotation. The rod mill is then rotated at 60 .rpm for a total of 360 revolutions. The ground slurry is transferred to a 1500 ml cell o an Agitair~
Flotation machine. The float cell is agitated at 1150 rpm and the pH is adjusted to 10.0 by the addition of fur~her lime, if necessary.

A collector, potassium amyl xanthate, is added to the float cell (0.035 kg/metric ton), follow~d 33,232-F ~13 ,

2~
-14~

by a conditioning time of one minute, at which time the frother is added (O.036 kg/metxic ~on). After the addi-tional one minute conditioning time, -the air to the float cell is turned on at a ra-~e of ~O5 liters per minute and ~he automatic froth removal paddle is started. The roth samples were taken of at 8 minutes. The fxoth samples are dried overnight in an oven, along with the flotation tailin~s. ~he drieA samples are weighed, divided into suitablé samples for analysis, pulverized to insure suit able ~ineness, and dissolved in acid for analysis. The samples are analyzed using a DC Plasma Spectrograph. The resul~s are compiled in Table I.

33,232-F -14 .~

C`~
CO N U~ ~ ~ N Ll~ N
~ o o a ~D
la ~ ~ r~ N t~
O O O C~ O C~ O O

U~

O O u~ O ~
r-~ O a~ I o ~1 ~1 ~ ~1 ~ ., ~ .
U~

~ ~ C~ D O O a~
P a) ~ ~ L

q3 ~ ~1 0 ~ o co a O O O ~ O O O
O O O O O O O O ~ a P~ O
P
U tJl ~ . 1~
o o z a~ co o ~ ~ o ~ ~ ~ ~O ~ ` p P~ O
h l~ . . . . . . . ~ ~ ~1 ~ ~
8 ~, ~ o ~ o ~o ~ a~ u~ ~u s~ ~ .,, h 1-~~1 o ~ r` t` t~ 0 rl ~ ~ O O u~
a~ 1 0 1~: ~
P~ P0 aD ~ a) u~ u~
P, O. . . . . . ~ ~ O ~ El ~
c~ au~o o o o o o oo ~ ~ ~ ~ u ~: 1:~ ~ O
.~1 .,1 _I
O N
O O O ~ ~
N N ~l 0 r/ rl X

o o ~1 o o O P~ U
,1: o ~ Ln o N U ~I ~ 1~ d1 la Ul ~ ~1 ~) o , ~, , ~, ~, ~+ a~ ~ o ~ ~ ~ ~ ~ O ~ O O U~
~ a ~: a ~

33, 232-F 15-Table I demonstrates that the frothers of this inve~tion demonstrate good recovery of the copper values with high selectivity toward the copper values.
The selectivities of the frothers of this invention are better than the selectivities of the commerc:ial frothers tested side by side with them. In fine mineral particle flota~ion there i5 relatively little valuable metal recove~y diffexence when employing the different fxothers. The biggest difference in effectiveness between frothers is the amount of gangue ~hat is recovered in the roth (i.e., s~lectivity).

In Table I and the following Table II, MIBC refer~ to me~hyl isobutyl carbinol. DF-200 refers herein to DOWTROI~X~200 (Trademark of The Dow Chemical Company) which is a me~hyl ether of propylene glycol with an average molecular weight of about 200.
DF-250 refers herein to DOWFROT~ 250 (Trademark of The Dow Chemical Company) which is a methyl ether of polypropylene glycol with an average molecular weight of about 250. DF-1012 refer~ to DOWFROTH~ 1012 (Trademark o The Dow Ch~mical Company) which is a methyl e~her o polypropylene glycol with an average molecular weight of about 400. Voranol0 2025 refers herein to the reaction product of glycerol and pro~
pylene oxide with an average molecular weight of 250.
Voranol~ CP 450 refers herein to the reaction product of glycerol and propylene oxide with an average molecular weight of 700. Voranol~ 2070 refers herein to the reac-tion product of glycerol a~d propylene oxide with an 30 average molecular weight of 700. Sorbi~ol~/propylene oxide adduct refers herein ~o ~he reaction product of Sorbitol~ and propylene oxide with an average molecular weight of 762 (or equivalent weigh~ of 127). Sucrose/-33,232-F -16-.:

~f~
-17~

propylene oxide adduct refers herein to the reaction product of sucxose with propylene oxid~ with an average moleculax weight o.- 984 (or equivalent weight of 123).

An El Tenien~e copper ore, wherein 91.1 per-cent comprises particle sizes of 75 micrometers or less, is floated by a fxo~h flo~a~ion machine using the proce-dure of Example 1. The pH of the aqueous pulp in the cell is 8.5. The collector is methyl isopropyl ~hiono-carb~mate (Z-200~, a Trademark of The Dow Chemical Com-pany) and used in an amount o 0.052 kg/ton. The frothers are used in concentrations o 0.025 kg/ton.
The results are compiled in Table II.

33,232 F- -17~

--18 ~

O ~0 0 aD c~
n~-~ ~ ~ I~ n ~ d' O
~1 :' N

U
U~

~ o ~ u~ ~n o o .,.~
O O t~ rl N
U ; ;

U~

~ ~ u~ o ~
o~
; d~

~0 r~ 0 a~
v~ b~ O c~ O ~1 0 0 0 0 t~ o o o o o C~ h O (~
u u ~ ~ ~ O~ ~ ~ O O
i~ O h O ~ Il) ~1 N N a~
n ~ P ,~ p P P ~ p h h ~r1 ~ 4l t~
h h ~t OD 1~ i-l u) 00 dt ~ ~ O o ~ ~ ~--1 0 ~ ~ ) ~ O ~: G ~rl ;~ a P a~ 0 ~ a~ ~ ~ ~
c~ U O O O O ~ O O ~ ~ ~ ~ .
~ ~ ~t O
rl r~
o ~
h ~ t ~t ~rl O~rl O ~\
~3~X ~aOe 5~
v~ ~/~, ~ O Q~
o ~ o ~ ~ U V~t O U
e~ O O L~l ~rl O O a~ :1 0 ~

O ~ I I I L! ~t~ U ~t~ ~ + ~1 ~
v~t-t ~t ~t ~ O ~ ~ ¢ O u~ u~ Z

33, 2~2-F -18-, -l9~

Table II demonstrates that the use of the frothers of this invention result in higher recoveries of copper than the commercial frothers ~hey are com-pared to. Fur~her, the frothexs of this invention result in surprisingly better selectivities for the copper values over the gangue than the commercial frothers allow.

33,232-F -19 Example 3 In this example three frothers are tested for flotation of coper sulfide values. A 500-g ~uantity of copper ore, chalcopyrite copper sul~ide ore, previously packaged in plaçe in a rod mill with 257 g of deionized water. A quantity of lime is also added to the rod mill, based on the desired pH for ~h~ subsequen~ flotation. The rod mill is then rotated at 60 rpm for a total of 360 revolutions to produce a feed in which 50.1 percent of the particles have a size less than 75 micrometers. The ground slurry i~ transferred to a 1500 ml cell of an Agi-tair Flotation machine. The float cell is agitated at 1150 rpm and the pH is adjusted to the desired pH (10.0) by the addition of urther lime, if necessary.

The collecto~, potassium amyl xanthate, is add~d to the float cell (0.004 kg/metric ton), followed by a conditioning time o one minute, at which tim~ the frothe~ is added (0.058 kg/metric ton).
After an additional one minute conditioning time, the air to the 1Oat cell is turned on at a rate of 4.5 liters per minute and the automatic froth removal paddle is started. Froth was taken for 8.0 minutes. The froth samples are dried overnight in an oven, along with the flotation tailings.
The dried samples are weighed, divided into suitable samplesOfor analysis, pulverized to insure suitable fineness, and dissolved in acid for analysis. The samples are analyzed using a DC Plasma Spectrograph. The weights of recovered froth and tailings samples and the analyses are used in a computer program to calculate metal and ganguge recovery, and the R and K parameters.
The results are compiled in Table III.

33,232-F ~20-~ I ~
.~ ~ I

Ei ~ D
¦N
~ o ~ d' r~ a lo ~ o~
~ r~l ~ d~ N r ~ E I o o o o o E ~ ~ O ~ O

~

~, N ~ ~ ~ ô E~ 5 33,232-F ~21 Table III demonstrates that the use of CP-450 frothers o~ this invention resulted in a substantially higher recovery of copper particles having a size of less than ~bout 200 microns. The recovery of gangue in the coarse particle size of greater than 200 microns as well a~ in the xecovery of gangue in the fine particle size below ~00 microns was substantially less. Ac~ordingly, ~he selectivity recovered for both coarse and fine particles was substantially greater.
The percentage selectivi~y for fine particles is improved by at least 19 percent.

33,232~F -22

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process of recovering fine minerals from ore, comprising:
classifying or comminuting the ore such that 75 percent or greater of the ore particles are 75 micrometers or less;
subjecting an aqueous pulp of the ore to a froth flotation such that mineral particles greater than 75 micrometers are recovered in the froth and the mineral particles of 75 micrometers or less remain in the aqueous pulp after the flotation; and subjecting said remaining aqueous pulp, to a froth flotation in the presence of a flotation collector and a flotation frother, wherein said frother comprises the reaction product of a 1) polyhydroxy alkane having 1 to 20 carbon atoms or a polyhydroxy cycloalkane having 3 to 20 carbon atoms and 2) propylene oxide, or a mixture of propylene oxide and ethylene oxide, with the proviso that at least 50 mole percent of the mixture is 33, 232-F -23-propylene oxide, wherein the reaction product has a molecular weight of 150 to 1400.

2. The process of Claim 1, wherein the polyhydroxy alkane or polyhydroxy cycloalkane corresponds to the formula R(OH)m' wherein R is an alkane having 3 to 12 carbon atoms or a cycloalkane having 3 to 20 carbon atoms, and m is an integer of from 3 to 10.

3. The process of Claim 1 of 2, wherein the frother is the reaction product of trihydroxy 1,2,3-propane and propylene oxide.

4. The process of Claim 1, wherein the reaction product has a molecular weight of 200 to 800.

5. The process of Claim 1, wherein the ore is a metal sulfide ore, metal oxide ore, gold-bearing ore, platinum-bearing ore, palladium-bearing ore, or silver-bearing ore.

33,232-F -24-

6. The process of Claim 1, wherein the frother is added to the aqueous plup in an amount of less than 0.055 kg/mt of ore.