Note: Descriptions are shown in the official language in which they were submitted.
lL~9gi~77
-- 1 --
RECOVERY OF PLATINUM-GROUP METALS
AND OTHER ~ETAL VALUABLES
This invention relates to the benefication of metal-
liferous ores, particular ores containing metals of the plat-
inum-group, i.e. platinum, rhodium, palladium, osmium, irid
ium and ruthenium. Such ores are, for example, found in the
Merensky and other related reefs where the metals occur in
either the free or combined form, in copper, nickel, iron and
chrome ores, and in minerals such as pentlandite, pyrohtite,
chalcopyrite, troilite and chromite.
It is known to employ the soluble salts of mercaptans,
dithiocarbonates, and dithiophosphates as promotors and/or
collectors in the froth flotation of the aforementioned ores.
It is also known to utilize these substances in combination
with one another to improve the recovery of platinum-group
metals in such processes.
These known3 so called thio-promotors and/or collec-
tors, are characterized by the fact that they contain either
one or two sulphur atoms on one of their terminal carbon at-
oms.
Applicant has now found other thio-compounds which are
even more selective froth flotation promotors and/or collec-
tors for the platinum-group metals, individually and/or in
groups thereof than what the case is with any of the afore-
said known thio-compounds.
According to the invention a froth flotation promotor
and/or collector for the recovery of metals from the platinum-
group is provided which includes a trithiocarbonate (other
than a dialkyl or ethoxy ester derivative thereof) and/or an
alkyl derivative thereof having 2 to 16 carbon atoms and/or
the ammonium or alkali metal salts of any of these compounds.
Applicant has found these trithiocarbonates or phos-
phates, when used as independent promotors and/or collectors
in the flotation of the aforementioned ores, to give much bet-
ter recovery of the platinum-grouP metals than what is pos~
sible with the known dithiocarbonates~ dithiophosphates, or
~r
7~
-- 2
mercaptans used either individually or in combination with
one another.
Not only is the yield of the platinum-group metals
higher and the grade better when using the compounds of the
invention, but it is also possible to float lower mass con-
centrates while achieving tailings with lower metal concen-
trations.
Compounds which the Applicant has found particularly
useful in this regard are:
sodium ethyl trithiocarbonate,
sodium n-propyl trithiocarbonate,
sodium isopropyl trithiocarbonate,
sodium n-butyl trithiocarbonate,
sodium isobutyl trithiocarbonate,
sodium sec-butyl trithiocarbonate~
sodium tert-butyl trithiocarbonate,
sodium n-pentyl trithiocarbonate,
sodium isopentyl trithiocarbonate, and
sodium benzyl trithiocarbonate.
Of these compounds the one which the Applicant found
most useful was the sodium salt of isopropyl trithiocarbo~
nate.
Applicant has also found a combination of the compounds
of this invention and the mercaptans to give good results as
a froth flotation collector and~or promotor in the recovery
of metals of the platinum-group.
The invention also includes within its scope a method
for the recovery of platinum-group metals by means of a froth
flotation process in which one or more of the promotors and/
or collectors of the invention are utilized.
This invention further relates to the recovery of metal
valuables, and to substances suitable for use in such recovery.
More particularly this invention relates to the froth flotation
of metalliferous ores, such as those containing metals of the
platinum-group as well as other sulphide ores, particularly
copper bearing sulphide ores.
Ores containing metals of the platinum-group are, for
_ 3 _
example, found in Southern Arica in the Merensky and other
related reefs, in which the metals occur in either the free
or combined form; in copper, nickel, iron, and chrome ores;
and in minerals such as pentlandite, pyrohtite, chalcopyrite,
troilite and chromite. The metals of the platinum-yroup,
which will in the rest of this specification be referred to
as the PGM, include platinum, rhodium, palladium, osmium,
iridium and ruthenium.
One copper bearing ore of the aforesaid type is, for
example, that found in the Bushveld Igneous Complex at Phala-
borwa in the Northern Transvaal in the Republic of South Af-
rica. This ore, which will hereafter be referred to as the
PMC-ore, usually comprises a mixture of the minerals chalco-
pyrite (60%); bornite (28%); cubanite (6~); and valleriite
(6%). Such an ore body usually contains between 0.2 and 10.0%
copper, although the lower copper level can in some instances
even be less.
It is known to recover metal valuables of the afore-
said kinds by means of a froth flotation process, and amongst
the froth flotation agents which have been used. In this re-
gard, are certain of the so called dithiocarbonates (hereaf-
ter referred to as DTC), such as, for example, potassium amyl
xanthate (hereafter referred to as PAX); certain of the so
called dithiophosphates (hereafter referred to as DTP), such
as, for example, di-isobutyl dithiophosphate (hereafter re-
ferred to as di-iC4DTP); mercaptobenzothiazole (hereafter re-
ferred to as MBT); and certain of the mercaptans.
Applicant itself has also found that certain trithio-
carbonates (hereafter referred to as TTC) can be used as froth
flotation collectors for metal valuables of the aforesaid
kinds.
As a result of the constant depletion of the previously
existing very rich ore bodies, the grade of ore which has to
be worked gets lower all the time, and there is accordingly a
continued search for better collectors. It is an object of
this invention to provide such a collector.
Accordin~ to a further feature of the invention a froth
2~ 7~
flotation collector for the recovery of a metal valuable co~n-
prises a combination of at least two diEferent compounds of
which one is a mono al`kyl TTC in which the alkyl groups can
be linear or branched and can have 2 to 16 carbon atoms, andJ
or the ammonium and/or alkali metal salts of any of those com-
pounds and the other compound is at least one compound of the
group of compounds including a TTC; DTC; DTP; mercaptan (ex-
cept where the metal valuable is a PGM); the alkyl derivatives
of any of the aforesaid compounds in which the alkyl group can
be linear or branched and can have 2 to 16 carbon atoms; MBT
(except where the metal valuable is copper or iron); an am-
monium and/or alkali metal salt of any of the aforesaid com-
pounds, the compounds of the combination being added to the
reaction medium either as a blend or separately.
Applicant has found that when such a combination is em-
ployed as a collector in the recovery of metal valuables of
the aforesaid kinds, an unexpected synergistic effect results
and the overall collecting properties, including the rate of
collection, are better than the combined properties of the
individual compounds of the combination.
Further according to the invention at least one of the
compounds of the combination is iC3TTC (i.e~ isopropyl TTC~.
Further according to one embodiment of the invention a
froth flotation collector combination for the recovery of a
PGM includes an iC3TTC and iC4TTC; or an iC3TTC and/or iC4TTC
and at least one of the compounds iC4DTP and MBT.
Further according to another embodiment of the inven-
tion a froth flotation collector combination for the recovery
of copper includes at least two compounds of the group of com-
pounds including iC3TTC, nC4TTC, iC4DTP and PAX.
Still further according to this embodiment of the in-
vention the collector comprises iC4DTP and at least one of the
compounds iC3TTC, nC4TTC and PAX.
Still further according to this embodiment of the in-
vention the collector comprises iC4DTP, nC4TTC and PAX, pre-
ferably in equimolecular quantities.
The invention also includes within its scope a method
~ ~ 3Z423CA
Eor the recovery oE metAl vAluAbles particularly plat:Lnum, or copper
from a copper containLng sulpIlide ore, employing a collec-tor accord:Ing
to the invention.
~ OF T~IE DRAWINGS
F:lgure 1 shows PGM recove,ry of the stanclard :Ln iC3TTC a-t 45 g/t.
F:Lgure 2 shows PGM recovery of -the standard in iC3TTC at 30 g/t.
Figure 3 shows PGM recovery of the standard and i.C4TTC at 30 g/t.
Figure 4 shows the regression line for collector A at 45 g/t.
Figure 5 shows ths regression line for collector A at 30 g/-t.
Figure 6 shows the regression line for collec-tor B at 30 g/t.
Figure 7 shows the regression line for collector ~ at 45 g/t.
Figure 8 shows the regression line for collector E at 10 g/t.
Figure 9 shows the regression line for collector E at 20 g/t.
Figure 10 shows the regression line for collector E at 30 g/t.
Figure 11 shows the regression line for collector E a-t 40 g/t.
Figure 12 shows the regression line for collector E at 45 g/t.
Figure 13 shows the time-recovery data for copper USillg iC3TTC.
Figure 14 shows -the time-recovery data for Gangue for iC3TTC.
Figure 15 shows the time-recovery data for copper using iC4DTP.
Figure 16 shows the time-recovery data for Gangue using iC4DTP.
Figure 17 shows the -time-recovery data for copper using nC4TTC.
Figure 18 shows the time-recovery data for Gangue using nC4TTC.
Figure 19 shows the time-recovery data for copper using PAX.
Figure 20 shows the time-recovery data for Gangue using PAX.
Figure 21 shows the time-recovery data for copper using iC3TTC ancl
iC4DTP.
Figure 22 shows the time-recovery data for Gangue using :LC3TTC and
iC4DTP.
Figure 23 shows -the time-recovery data for copper using iC3TTC and
PAX.
Figure 24 shows the time-recovery data for Gangue using iC3TTC and
P~X .
Figure 25 shows the time-recovery data for copper using :LC3TTC and
nC4TTC.
Figure 26 shows -the time-recovery data for Gangue USiDg iC3TTC and
nC4TTC.
Figure 27 shows the time-recovery data for copper using nC4TTC and
iC4DTP.
~' .
~9~ 32423CA
-- 6 --
Figllre 28 shows -the -time-recovery data for Gangue uæing nC4TTC
and iC4DTP.
Figure 29 shows the time-recovery data for Ganglle l1s~ng nC4'r'rC nn(l
P~X .
Figure 30 shows the time-recovery data Eor copper usLng nC4TTC ancl
P~X .
Figure 31 shows the time-recovery da-ta for copper using iC3TTC and
iC4DTP and PAX.
Figure 32 shows -the time-recovery data for Gangue using iC3'rTC and
iC4DTP and PAX.
Figure 33 shows the time-recovery da-ta for copper using iC3TTC and
nC4TTC and PAX.
Figure 34 shows the -time-recovery data for Gangue using iC3TTC and
nC4TTC and PAX.
Figure 35 shows the time-recovery data for copper using iC3TTC and
nC4TTC and iC4DTP.
Figure 36 shows the time-recovery data for Gangue using iC3TTC and
nC4TTC and iC4DTP.
Figure 37 shows the time-recovery data for copper using nC4TTC and
iC4DTP and PAX.
Figure 38 shows -the time-recovery da-ta for Gangue using nC4TTC ancl
iC4DTP and PAX.
Figure 39 shows the comparison of time-recovery data for iC3TTC and
nC4TTC.
Figure 40 shows the comparison of time-recovery data for iC3TTC and
iC4DTP.
Figure 41 shows the comparison of time-recovery data for iC3TTC and
PAX.
Figure 42 shows the comparison of time-recovery da-ta for nC4TTC and
iC4DTP.
Figure 43 shows the comparison of time-recovery data for nC4TTC and
PAX.
Figure 44 shows the comparison of time-recovery dnta for iC3TTC and
nC4TTC and iC4DTP.
Figure 45 shows the comparison of time-recovery da-ta for iC3TTC and
PAX and iC4DTP.
Figure 46 shows -the comparison of time-recoVery data for nC4TTC and
iC4DTP and PAX.
~2~9~7
32423CA
-- 7 --
Figure 47 shows the comparison of -time-recovery dat~ for iC3TTC and
nC4TTC and P~X.
Figure 48 shows the R and K value for compos:lt:Lons ranging frt)m
tO0% iG4TTC and 0% lC4DTP to 100% lC4DTP and 0% lC4TTC.
The inventlon will now be described further by way of the following
non-limitillg examples:
EX~MPLE 1
In a typical laboratory scale froth flotation process 1640
grams of Merensky Reef ore were mllled at a mlll feed speclflc gravlty
of 2.0 for 34 mlnu-tes to obtain a milled feed -to flotation containing
55% minus 200 mesh.
The milled ore was added to a 4.5 lltre batch flotatlon cell
and adjus-ted to a pump speclflc gravlty of 1.25. The rotor speed of the
flotation machlne was adjusted to 1800 r.p.m. and 5 ml of a copper
sulphate solution (100 g/t) and 10 ml of dextrin (starch) solutlon (80
g/t) were added and condltloned wlth the pulp for one minute.
In the reference float 5 ml of sodium lsobutyl xanthate
solution (40-50 g/t~ and 5 ml of aeropromotor 3477 solutlon (80-100 g/t)
were used as the collector standard.
25 Grams per ton solid feed Dowfroth 200 were added and the
pulp condl-tioned for half a minute. The alr to the flotation machlne
was then turned on as follows:
Concentrate l: for three minutes after the froth bed developed;
Concentrate 2: for nine minu-tes.
The above procedure was repeated replaclng the sodlum lsobutyl
xanthate and fleropromotor 3477 (di-isobutyl dithiophosphate) collector
sys-tem with different types of trlthlocarbonates according to the
lnventlon at different dosages. The results are reflected in Table I on
page 8.
~2~
H ~ O O ~ ~-1 O r~
~ o c~) ~ ~t c~l n ~
~ ~ O r~ ~ O ~ ~ ~
r~ O ~1 C`~ C`~ C~ C~i ~
Z C~ o cr~ u~ C~l ~ O u~ O
0~ O ~ ~ ~0 ~ ~ ~
h
~ ~ O ~ 00 ~ ~ ~ ~ P~
p:; ~ o ~1 co ul ~ o ~ R
:~ ~ C~ ,~ ~ ~ ~ ~) ~i ~Y) O
~! z; o ~)
~1 C~ J~ o u~ ~ ~O ~ L~ c~ R
¢ ¢ ~ CO CO ~o oo ~ ~
IY ~ o ~Q oo U~ ~_1`J ~ O
~ Z O r-l ~ ~ C~l tO ~
~: 1_1 ~ O ,_1 r~ C~ C~l~1 r~
E~ r~ o oo ~1 C~l ~ o c~ r~
~ ~ ~i ~ c~ ~ c~c~l ~ g
k~ P~ * ii' OCl~ ~ u~ r~ ?
O O O r~ O ~ O h
~1~ O Pl~
¢ U~ O O O O O O ~
o r~ ~-1 u~ ~ u~~ u~ W
a~ c~ ,~ ~ ~ a)
R O R o R O R ~1 ,R ~ ~~ R ~ u w
::1 .q ::) .CI ~~ ~ e ~ ~ ,q ~ ~ h
o O h O ~ O 1~1 0 Il) O h O C) O h O h O
rn ~ ~ ~ rn J rn ~ rn ern ~ U~ eu~ ~ rn ~ *
:3.2~77~7 32423CA
From Table I it wlll be noted -that by employLng the compouncls
according to the inven-tion, both the yield, grade, nnd tailings grade of
the Pt-metal recovery improved compared to those obta:Lrled wLth the
stflndard .
EXAMPLE 2
In a typical pilot plant scale Ero-th fLo-tation process, 4
kilograms of Nerensky Reef ore wi-tb the desired particle size
dis-tribu-tion were pulped in an eight liter D12 Denver flotation machine
at 1500 r.p.m. and at na-tural pH. Copper sulphate was added at 100 g/t
and the system allowed to condition for five minutes. Thereafter a
collector according to the invention was added in the form oE a one
percent solution and dextrin. A -talc depressant was added a-t 80 g/t and
a further five minutes were allowed for conditioning. The frother, a
cresylic acid, was added one minute before aeration. Aera-tion at a rate
of 1.5 cell volumes per minute was initiated and the first concentrate
was continuously collected during ths first four-and-a-half minutes.
Thereafter two further concentrates were collected, respectively for
five-and-a-half minutes, and ten minutes. The floats were done in
triplicate and the platinum-group metals (PGM) were analy~ed for in the
concentrates tails and feed of the flotation cell. Copper and nickel
analyses served as controls for the PGM's analyses.
A con-trol set of experiments was also carried out using a
standard collector suit which consisted of Aero 3477 promotor and sodium
isopropyl xan-thate (hereafter SiPX).
In the first of our experiments the standard collector suit
used contained Aero 3477 promotor and SiPX in a ratio of 70 to 30
percent, which is the optimum ratio, at a combined dosage of 140 g/-t.
The resul-ts of this experiment are reflected in Figure 1 of the drawings
attached here-to by the line labeled "standard". ~ second set of
experiments were performed identlcally to the first set, except that the
collector in this instance was sodium isopropyl tri-thiocarbonate at a
dosage of ~5 g/t. From -the results, which are reflec-ted in the
aforesaid Figure 1 by the line labeled "TTC", it w:Lll be noted that an
improvement in the order of a-t least two percent in the recovery of
PGM's was obtaLned.
32423C~
In a third set of identical experiments a pur:Lf:Led vers:Lon o:E
sodium isopropyl tri-thiocarbona-te was substltutecl for the standard Acro
3477/SiPX combinatlon at A dosage of 30 g/t. T~e result~: are :refLected
in Figure 2 of the draw:Lngs attached hereto. Again fl s:Lgniflcant
:Lmprovemen-t in the order of at least two percent l:n the recovery of
PGM's was reallzed. It was also found ln thls and i.n the prcvious
instance that the grade of the concentratcs fllso :Lmproved, partly at
least because less talc was recovered.
In a fourth set of ideDtical exper:iments, -the collector
utllized comprised sodium isobu-tyl trlthiocarbonate at a dosage of 30
g/t and the results obtained are reflected in Figure 3 of the drawings
a-ttached hereto.
The results of further identical experiments which were
carried out w;.th the aforesaid collectors at different concentrations
(and/or p~lrities) and with other collectors falling within the scope of
the invention, are reflec-ted in Figures 4 to 12 of the drawings a-ttached
hereto. In these figures the three legends used for the collectors
denote the following:
A = sodium isopropyl trithiocarbonate,
B = sodium ben~yl trithiocarbonate, and
E = sodium n-butyl trithiocarbonate.
Applicant has also found that, apart from the sodium salts,
the potassium and ammonium salts of the aforesaid compounds also give
good results as promotors and/or collectors, Eor the pla-tinum-group
metals.
It ~li].l be appreciated that there are many variations i.n
detail possible with promotors and/or collectors according -to the
invention and their use in -the recovery of PGM which do not fall outside
the scope of the appended claims.
EXAMPLE 3
Recovery of a PGM
Approximately 1.5 kg of Merensky Reef ore were milled at a
mill feed specific gravity of 2.0 for thir-ty-four minu-tes to
obtain a milled feed to flotation containing 55% minus 200 mesh.
32423C~
11 æ;~
The mi]led ora WflS added to a 4.5 li.tre batch Elotat:Lon c~ll
and adjusted to a pump specific gravity oE 1.25. The rotor speecl of the
flotation machine was adJusted to 1800 r.p.m. and 5 ml of a copper
sulphate solution (100 g/t) and 10 ml of dextr:Ln (starch) solut:Lon (80
g/-t) were added and cond:Ltloned wl-th -the pu1p for one mi.nllte.
In the reference floa-t 5 ml of sodium isobutyl xanthate
solution (40 g/t) and 6 ml of sodium dithiophosphate solu-tion (30 g/t)
were used as the collector s-tandard.
25 Grams per -ton solid feed Dowfroth 200 were added and the
pulp conditioned for thirty minutes. The air to the ilotation machine
was then turned on as follows:
Concentrate 1: for three minutes after the froth bed developed;
Concentrate 2: for nine minutes.
The above procedure was repeated replacing the aforesaid
standard collector system with differen-t TTC collector combinations
according to -the invention at different dosages. The results are
reflected in Table II on page 12.
~,~
~29~1~7
-- 12 --
OC'l ~ ~1 ~D O ~`1
Z O~C) I~ C`l ~ 00 ~
C~ r~ r; r~i C~i ~ r1 ~1
H
X ~ o ~ `D O U~ I~ I~
~ ~ O ~ ~ I~ ~ O~ `D
E-l r1r; r~ O O O O
i--~
00 00 000 00 000 000 00
C`~ C~l C`l ~ ~ ~ ~ ~ ~ ~ C`l C`l C~ ~ o~
E~ O
~ ~:4 ~1 d ~ P~ ~4
K ~ o o 3 ~ 1:~1
C~ ~ ~ .,U ~ ~ C~L~ C~
~ ~q O E~ E~ E~ ~ ~ E~ ~ O ~1 ~ O ~ O
;~ ~1 ~ ~ ~ ~ ~) O Pl h C.) O rl C~ 1 ~ '
rl ~ ~rl ~rl rl ~rl e ~,1 e ~e E3 ~ ~1 e ~
e e 6 6 e e e e e e e 6 6 6 e 6 e
,,q.,P ,,~ ~ ~ ,,~ ,,~ ,,~
~o ~o ~o ~o ~o ~o ~o ~o ~o ~ ~o ~o ~o ~o ~o ~o ~o
u~u~ ~ u~cacn u~u~ u~ c~ ~
r ~ ~ ~ U~
~29~7~7 32423CA
- 13 -
In Table II the dosages referred to flre calculatsd on the
bas:is of the solicl and/or 100% active ingred:Lent whlle, ~or reasons of
confidentiality~ the PGM values are sxprsssed relfltive to the results
obtained with the aforesaid standard.
From Table II lt wlll be clear that due to a very sign:lticnnt
amount oE synergism betwoen the constituents of the various mixtures
dsscribed above, -the collec-tor combinations according to the invention
have much better flota-tion propsr-ties in respect of -the recovery oE PGM
than any of the hitherto known collectors.
EXAMPLE 4
Recoverv of copper
The following thirteen collectors or collec-tor combinations
were in turn used to recover copper from a PMC-ore:
1. iC3TTC,
2. Na diiso-CI,DTP,
3. nC4TTC,
4. PAX,
5. iC3TTC -~ Na diiso-C4DTP,
6. iC3TTC -~ PAX,
7. iC3TTC -~ nC4TTC,
8. nC4TTC + Na diiso-DTP,
9. nC4TTC + PAX,
10. iC3TTC + Na diiso-DTP + PAX,
11. iC 3 TTC + nCI,TTC + PAX,
12. iC3TTC + nC4TTC + Na diiso-DTP,
13. nC4TTC + Na diiso-DTP + PA~.
The PMC-ore was ground -to an average size of 40 - 75 microns.
1 Kg of ths ore was weighed into a flotation cell, and the cell filled
with water to a predetermined level. While -the pulp was being agitated,
the collector or collector-mixture was added and a five minute
conditioning -time allowed. The amount oE collector used, was 125 ~mole
per kilogram of ore. In -the case of collector-mixtures, 1:1 or 1:1:1
molar ratio of the 125 ~mol/kg dosags was admlnistered. These molar
ratios were determined taking the molecular weight and the activity of
the specific collector in-to account.
;
32423CA
77~
~ fter :Eour m:Lnutes of -the mentioned condit:Lorl:Lng t:Lme, 25 ~:l
oE the frother was added. ~fter ftve mlnutes o:E cond:Ltion:Lng time, the
flir supply to the flotation cell was openecl, care belng take:n to keep
the fluid level constAn-t. Thi.s was necessary because the vollJme of the
whole fluid sys-tem (pulp ~ froth) decraases as concentrates are being
co:llected. Concentra-tes were collec-ted a-t the following cumulative time
intervflls: 1~ 2, 4, 6 and 9 minutes.
The concentrates and the tailings -that werc left in -the oatch
flota-tion cell were filtered with the aid of Buchner funnels. The
filter-cakes were the:n dried in an oven, the weight of each filter-cake
measured, and the copper contents of each sample determined.
The results of the aforesaid thirteen experimen-ts were used to
de-termine the R and K values of the so called Klimpel model which can
mathematically be expressed as
r = R r 1 - - (1 - exp (Kt))
L Kt
where K = the first order rate constant of the to-tal mass (valua le +
gangue) collected;
R = the ultimate equilibrium recovery after a long -time of flotation;
r = the accumulative recovery at time t.
In a modified model, K was taken as the average slope of the
release curve over the first half a minute of the flotation, and R as
the value of r after thirty minutes of flotation.
The modified results of -the aforesald thirteen experiments
insofar as the copper values in the concen-trate and gangue respectively
are concerned, are reflected in the graphs constituting Figures 13 to 38
attached hereto.
The graphs constituting Figures 3~ to 47 at-tached hereto
clearly illus-trate the synergistic effect obtained with various
combinations of collectors according to the invention when employed in
the recovery of copper.
Further combinations of collectors according -to the in-
ven-tion which were also investigated under the same conditions as above
in the recovery of copper, and which all gave good results, were:
14. nC4TTC + iC4DTP + iC4TTC,
..
~i~
- 15 - 32423CA
15. iC4TTC + iC4DTP,
16. iC4TTC ~ nC4TTC + iC3TTC ~ MBT,
17. iC3TTC ~ nC4TTC + M~T,
18. iC3TTC ~ iC4TTC + nC4TTC.
The conclusion whlch Applicant has reached from the results
from the aforesaid eighteen experiments is that, except for the
comb:ination iC4DTP ~ iC3TTC, iC4DTP, and iC4TTC or nC4TTC, are always
present in the combinations having the best collectlng properties. A
further conclusion is that a combination of the various TTC's on their
own gives poor results.
Applicant has furthermore found that through an appropria-te
selection of the concentration of the individual components of a
particular mixture of collectors according to the invention, the rate of
collection and amount of valuables recovered may be predetermined.
This phenomenum is illustrated in the graph of Figure 48
attached hereto in which the results obtained with a collector-mixture
comprising iC4TTC and iC4DTP in the recovery of copper are reflected.
It will be appreciated that because of the unexpected
synergism shown by the collector combinations according to the
invention, a collector for the recovery of a metal valuable,
particularly PGN and/or copper from a copper sulphide ore, is provided
which gives better results insofar as its collecting properties and rate
of collection are concerned than any of the hitherto known collectors.
It will be appreciated further that there are no doubt many
variations in detail possible with a collector combination according to
the invention, and to a froth flotation process involving such a
combination, without departing from the scope of the appended claims.
