TALC-MOLYBDENITE SEPARATION

SEPARATION DU TALC ET DE LA MOLYBDENITE

English Abstract

A B S T R A C T

A method of enriching the molybdenite
fraction of ores and concentrates having hydrophobic
silicates containing magnesium and/or aluminum, such
as talc. An aqueous slurry of the ore or concentrate
is conditioned with a water soluble metallic salt of
a weak base and strong acid and a water soluble salt
of a weak acid and subject to agitation. The condi-
tioned pulp is then subject to a conventional froth
flotation wherein the molybdenite fraction is floated
off as a molybdenite enriched concentrate and the talc
fraction and other acid-insoluble contaminates are
depressed into the tailings.

Claims

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

1. A method of preparing molybdenite bearing concentrates containing
an acid insoluble fraction consisting principally of hydrophobic silicates
containing magnesium which is conventionally floated or depressed with the
molybdenite fraction during flotation, said method including the steps of
conditioning an aqueous pulp of the molybdenite bearing ore or concentrate
with a water-soluble metallic salt of a weak base and strong acid and a water-
soluble salt of a weak acid; agitating said conditioned aqueous pulp, and
subjecting said agitated conditioned pulp to froth flotation.

2. The method according to claim 1 including the additional steps of
particulating the molybdenite bearing concentrate and adjusting the density of
the aqueous pulp from about 1 to about 45% solids.

3. The method according to claim 1 wherein the aqueous pulp is first
conditioned with the water-soluble metallic salt of the weak base and strong
acid.

4. The method according to claim 1 wherein the aqueous pulp is condi-
tioned with from about 1 to about 30 pounds per ton of pulp solids of the
water-soluble metallic salt of the weak base and strong acid.

5. The method according to claim 1 wherein the water-soluble metallic
salt of a weak base and strong acid is selected from the water-soluble alumi-
num, manganese, zinc, chromium, iron and cadmium salts of hydrofluoric acid,
hydrochloric acid, nitric acid, and sulfuric acid.

6. The method according to claim 1 wherein the water-soluble salt of a
weak acid is selected from the water-soluble alkali metal, alkaline earth metal
and ammonium salts of silicic acids, carbonic acid, acids of phosphorous and
acids of boron.

7. The method according to claim 1 wherein the water-soluble metallic
salt and a weak base and a strong acid is selected from the group consisting

12


of zinc sulfate, aluminum sulfate and chromium sulfate.

8. The method according to claim 1 wherein the water-soluble salt of
the weak acid is selected from the group consisting of sodium silicate, sodium
monohydrogen orthophosphate and sodium bicarbonate.

9. The method according to claim 1 wherein the water-soluble metallic
salt of the weak base and strong acid is zinc sulfate and the water-soluble
salt of the weak acid is sodium silicate.

10. A method of separating ore or concentrate having molybdenite and a
substantial amount of hydrophobic silicate containing magnesium by froth
flotation to obtain a molybdenite enriched concentrate and hydrophobic sili-
cate enriched tailings, which method includes the steps of:
(1) forming a dual agent conditioned aqueous pulp of said ore or
concentrate,
said dual agent consisting essentially of
(I) (a) water soluble metallic salt of a weak base and a strong acid,
and
(b) water soluble salt of a weak acid, except when said weak acid
is hydroferrocyanic acid, or
(II) (a) water soluble zinc salt of a strong acid, and
(b) water soluble salt of hydroferrocyanic acid;
(2) agitating said conditioned aqueous pulp; and
(3) subjecting said agitated conditioned aqueous pulp to froth flotation
separation whereby a molybdenite enriched concentrate is flotated and hydro-
phobic silicate is selectively depressed into the tailings from said froth
flotation separation.

11. The method according to claim 10 where said hydrophobic silicate is
talc.

12. The method according to claim 10 where said dual agent consists
essentially of:

13


(I) (a) water soluble metallic salt of a weak base of which the cation
is selected from the class consisting of aluminum, cadmium, chromium, cobalt,
copper, calcium, magnesium, iron, manganese, nickel and zinc, and a strong acid
selected from the class consisting of hydrochloric acid, hydrofluoric acid,
nitric acid, and sulfuric acid affording the anions chloride, fluoride, nitrate
and sulfate, and
(b) water soluble alkali metal, water soluble alkaline earth metal,
or water soluble ammonium salt of weak acid selected from the class consisting
of boron acids, carbonic acid, acids of phosphorus, and silicic acid; or
(II) (a) water soluble zinc chloride, zinc fluoride, zinc nitrate, or
zinc sulfate, and
(b) water soluble alkali metal, water soluble alkaline earth metal,
or water soluble ammonium salt of hydroferrocyanic acid.

13. The method according to claim 12 where said conditioning is carried
out by adding said metallic salt of (I)(a) and (II)(a) to said aqueous pulp
to condition said pulp prior to the addition of said salt of (I)(b) and
(II)(b), as the case may be.

14. The method according to claim 12 where said aqueous pulp is treated
with between about 1 and 30 pounds per ton of pulp solids of said metallic
salt of (I)(a) and between about 1 and 45 pounds per ton of pulp solids of
said salt of (I)(b) and (II)(b) as the case may be.

15. The method according to claim 10 where said dual agent consists
essentially of
(a) water soluble metallic salt of a weak base of which the cation
is selected from the class consisting of aluminum, cadmium, chromium, cobalt
copper, calcium, magnesium, iron, magnanese, nickel and zinc, and a strong
acid selected from the class consisting of hydrochloric acid, nitric acid and
sulfuric acid affording the anions chloride, nitrate and sulfate, and
(b) sodium silicate or potassium silicate.

16. The method according to claim 10 where said dual agent consists

14


essentially of
(a) water soluble metallic salt of a weak base
of which the cation is selected from the class consisting
of aluminum, chromium, copper, manganese, and zinc, and
a strong acid selected from the class consisting of
hydrochloric acid, nitric acid and sulfuric acid affording
the anions chloride, nitrate and sulfate, and
(b) sodium bicarbonate, potassium bicarbonate,
or ammonium, bicarbonate.

17. The method according to claim 10 where said
dual agent consists essentially of
(a) water soluble metallic salt of a weak
base of which the cation is selected from the class
consisting of aluminum, chromium, manganese, and zinc,
and a strong acid selected from the class consisting
of hydrochloric acid, nitric acid and sulfuric acid
affording the anions chloride, nitrate and sulfate,
and
(b) water soluble sodium monohydrogen
orthophosphate, or ammonium monohydrogen orthophosphate.

18. The method according to claim 10 where said
dual agent consists essentially of
(a) water soluble metallic salt of a weak base of
which the cation is selected from the class consisting of
aluminum, cobalt, copper, manganese, and zinc, and a
strong acid selected from the class consisting of




hydrochloric acid, nitric acid and sulfuric acid affording
the anions chloride, nitrate and sulfate, and
(b) water soluble sodium borate, potassium
borate or ammonium borate.

19. The method according to claim 10 where said dual
agent consists essentially of
(a) water soluble metallic salt of a weak
base of which the cation is selected from the class
consisting of aluminum, copper, and zinc, and a strong
acid selected from the class consisting of hydrochloric
acid, nitric acid and sulfuric acid affording the anions
chloride, nitrate and sulfate, and
(b) water soluble sodium orthophosphate, potassium
orthophosphate, or ammonium orthophosphate.

20. The method according to claim 10 where said
dual agent consists essentially of
(a) water soluble zinc chloride, zinc nitrate
or zinc sulfate, and
(b) sodium carbonate, potassium carbonate,
ammonium carbonate, sodium ferrocyanide, potassium ferro-
cyanide or ammonium ferrocyanide.

21. The method according to claim 10 where said dual agent consists

16


essentially of
(a) water soluble zinc chloride, zinc nitrate, or zinc sulfate,
and
(b) sodium silicate or potassium silicate.

22. A method of separating molybdenite concentrate containing molyb-
denite as the major metal value, talc and other acid insoluble minerals,
which method consists essentially of:
(1) forming an aqueous pulp of said concentrate;
(2) conditioning said aqueous pulp with zinc sulfate;
(3) adding to said conditioned pulp potassium ferrocyanide;
(4) agitating said conditioned aqueous pulp; and
(5) subjecting said agitated conditioned pulp to froth flotation
separation whereby a molybdenite enriched concentrate is floated and talc is
selectively depressed into the tailings from said froth flotation separation.

23. The method according to claim 22 wherein said zinc sulfate is added
in an amount of about 6 pounds per ton of solids and said ferrocyanide is
added in an amount of about 8 pounds per ton of solids.

24. A method of separating ore or concentrate having molybdenite and a
substantial amount of hydrophobic silicate containing magnesium by froth
flotation to obtain a molybdenite enriched concentrate and hydrophobic
silicate enriched tailings, which method consists essentially of:
(1) forming a dual agent treated aqueous pulp of said ore or concentrate,
said dual agent consisting essentially of
(I) (a) water soluble metallic salt of a weak base and a strong acid,
and
(b) water soluble salt of a weak acid selected from the group
consisting of boron acids, carbonic acids, acids of phosphorous and silicic
acids; or
(II) (a) water soluble zinc salts of a strong acid, and
(b) water soluble salt of hydroferrocyanic acid, and

17


(2) subjecting said dual agent treated aqueous pulp to froth flotation
separation whereby a molybdenite enriched concentrate is floated and hydro-
phobic silicate is selectively depressed into the tailings from said froth
flotation separation.

25. A method of separating ore or concentrate having molybdenite and a
substantial amount of a hydrophobic silicate talc containing magnesium by froth
flotation to obtain a molybdenite enriched concentrate and hydrophobic silicate
talc enriched tailings, which method consists essentially of:
(1) forming a dual agent treated aqueous pulp of said ore or
concentrate,
where the treating agent consists essentially of aluminum sulfate
and sodium silicate, and
(2) subjecting said dual treated aqueous pulp to froth flotation
separation whereby a molybdenite enriched concentrate is floated and hydro-
phobic silicate talc is selectively depressed into the tailings from said
froth flotation separation.

18

Description

~q~394~L7
~ his invention is directed to a process for separting the hydro-
phobic silicates containing magnesium fraction from molybdenite bearing ores
and concentrates. In particular this invention is directed to a flotation
process for mol~bdenite ores and concentrates where the talc fraction is
depressed and the molybdenite fraction is selectively floated awa~ there-
from~
The present process consists of conditioning pulps of molybdenite
bearing concentrates having hydrophobic silicates containing magnesium by
agitation in the presence of a water soluble metallic salt of a weak base and
a strong acid and a water soluble salt of a weak acid.
The subject process is useful in that there is sufficient depres-
sion of hydrophobic silicates containing magnesium so that either a market-
able grade of molybdenite concentrate is produced directly or the molybdenite
concentrate is enriched so that sub~equent processing is facilitated.
The present process is practiced by preparing aqueous slurry or
pulp of ground molybdenite concentrate or a molybdenite bearing ore. Gener-


! . ' .
ally the concentrated ore is ground to minus 10 mesh, preferably minus 48mesh (85% minus 325 mesh). The pulp denisty varies between about 1 and about
45% solids; however~ our tests of the process indica~e that a more satisfact-

ory separation is obtained as pulp density decreases.
The pulp is then conditioned with a water-soluble metallic salt of
a weak base and a strong acid and a water-soluble salt of a weak acid.
Between about 1 and about 30 pounds of the metallic salt of the weak base
and strong acid are used per each ton of solids. Between about 1 and about
45 pounds of the salt of the weak acid are used per ton of solids. Optimum
salt concentrations are dependent upon pulp conditions and salt combinations.
Best results are usually obtained if the metallic salt of a weak
base and a strong acid is added first to the pulp, agitated and then followed
by the salt of a weak acid; however, satisfactory results can be obtained
when the salt of a weak acid is added first, followed by the metallic salt of

weak base and a strong acid, both salts are added simultaneously, or both
salts are premixed and then added to the pulp.



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The preferred metallic salts of a weak base and strong acids are the
water-soluble sulfate, nitrate, fluoride and chloride salts of aluminum~
manganese~ zinc, chromium, iron and cadmium. It appears that the cation of
these particular salts is active in the present process.
Typical salts of weak acids that can be employed in the present
process include the water-soluble alkali metal (especially sodium and potas-
sium), ammonium, and alkaline earth metal (especially calcium and magnesium),
salts of silicic acids; carbonic acid; acids of phosphorus, including
phosphoric acid, hypophosphorous acid, phosphorous acid, hypophosphoric acid
and the like; the acids o-f boronj including ortho-boric acid, meta boric
acid, tetraboric acid and the like, and nitrous acid and the like.
The pulp and salts are agitated for a period of from about 1 minute
; to about 60 minutes, preferably about 30 minutes. Then the pulp is subject
to a conventional froth flotation for about 1 to about 30 minutes. The molyb-
denite f~action~ is floated off as an enriched molybdenite concentrate. The
molybdenite recovery is very high, from about 80 to about 96% and the concen~
trate is enriched by a factor of about 2 to about 3 times. The hydrophobic
silicates fraction and the other acid insoluble contaminants are depressed
into the tailings (from about 50 to about 85% of the acid insoluble contamin-
ants, principally talc and other hydropholic silicates, are depressed into
the ~ailings).
The following examples are intended to further illustrate the
present invention and not intended as limitations thereof. Naturally the
process conditions such as process times, temperature, pH and reagent
concentration can be varied through routine experimentation to optimize the
end results for a particular ore, mesh size~ pulp density, and partic~lar
reagents employed.
Example 1 (no treating agent)
A composite sample of low grade molybdenite concentrate produced
at the Pima Mine containing approximately 18% molybdenite, 4% chalcopyrite,
5% pyrite and 69% acid insoluble minerals was made into a dilute pulp of five
percent solids in water at ambient temperature in a laboratory flotation cell.




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The pulp was immediately subjected to froth flotation and the froth removed
for five minutes, during which a concentrate was separated. This example is
given to exemplify the response of the composite sample without the treatment
of subject process. The results of the example are presented in the following
table.

eight Percent ~istribution %
Product Percent Mo Insol. MoInsol.
Head 100.00 10.98 68.8 100.0 100.0
Concentrate93.75 11.35 68.9 96.9 93.9
Tailing 6.25 5.47 66.7 3.1 6.1
10Example 2
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. The pulp was then agitated with
a quantity of zinc sulfate corresponding to four pounds per ton of solids for
thirty minutes. A quantity of sodium silicate corresponding to 7.5 pounds per
ton of solids was then added. The pulp was then subjected to flotation as
described in Example 1. The results are presented in the following table.

~eight Percent istribution %
Product Percent Mo Insol. MoInsol.
._ _ __ _
HeadlOOnOO10.98 ~7.7 100.0 100.0
Concentrate44.69 22.53 49.7 89.0 32.8
20Tailing~r55.31 2.24 82.2 lloO 67.2
Example 3
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. A quantity of sodium silicate
corresponding to 7.5 pounds per ton of solids was added to the pulp. A
quantity of zinc sulfate corresponding to 16 pounds per ton of solids was
then added to the pulp. The pulp was agitated for thirty minutes and then
subjected to flotation as described in Example 1. The results are presented
in the following table.




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1~339gl~7
Weight Percent istribution %
Product Percent Mo Insol. Mo Insol.
Head 100.00 10.99 67.5 100 D O 100 ~ O
Concentrate54.08 19.03 55.1 93.6 44.1
Tailing 45.92 1.53 82.2 6.4 55D9
Example 4
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. A quanti,ty of 10% sodium
silicate solution was placed in a beaker. To this was added a quantity of
10% zinc sulfate solutionO The contents in the beaker were then washed into
the pulp. The quantity of sodium silicate corresponded to 7.5 pounds per
ton of solids, the quantity of zinc sulfate corresponded to 16 pounds per ton
of solids. The pulp was agitated for thirty minutes and then subjected to
flotation as described in Example 1. The results are presented in the follow-
ing table~

Weight Percent Distr tion %
Product Percent Mo Insol. Mo Insol.
Head 100.00 11.10 68.2 100.0 100.0
Con,centrate56.61 18.12 58.0 92.4 48~1
Tailing 43.39 1.95 81.6 7~6 51.9
Example 5
A sample of the composite described in Example 1 was subjected to
the pulping procedure~ described in Example 1. The pulp was then agitated
with a quantity of zinc sulfate corresponding to 16 pounds per ton of solids
for thirty minutes. An addition of disodium hydrogen phosphate corresponding
to 7.5 pounds per ton of solids was then added. The pulp was then subjected
to flotation as described in Example 1. The results are presented in the
following table.

Weight Percent Dist butio_ %
Product Percent Mo Insol. Mo Insol.
- Head 100.00 10.97 68.1 100.0 100.0

Concentrate35056 28.58 40~1 92.6 20.9
Tailing 64.4~ 1.26 83.6 7.4 79.1

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Example 6
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1~ The pulp was then agitated
with a quantity of zinc sulfate corresponding to 16 pounds per ton of solids
for thirty minutes. An addition of sodium acid carbonate corresponding to
7,5 pounds per ton of solids was then added. The pulp was then subjected to
flotation as described in Example 1. The results are presented in the follow-
ing table~

Weight Percent Distribution %
Product Percent Mo Insol. Mo Insol.
Head 100.00 11.66 67.6 100.0 100.0
Concentrate33.94 32.56 35.2 9~.8 17.7
Tailing 66.06 0.92 84.2 5.2 82.3
xample 7
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. A quantity of 10% sodium
silicate solution was placed in a beaker. To this was added a quantity of
10% aluminum sulfate solution~ The contents in the beaker were then washed
into the pulp. The quantity of sodium silicate corresponded to 7.5 pounds
per ton of solids, the quantity of aluminum sulfate corresponded to six
pounds per ton of solids. The pulp was then agitated for thirty minutes and
then subjected to flotation as described in Example 1. The results are
presented in the following tableO

Weight Percent Distribution %
Product Percent Mo Insol. M Insol.
Head 100.00 10.52 68~3 100.0 100.0
Concentrate52.50 17.59 58.0 87.8 44.6
Tailing 47.50 2.71 79.7 12.2 55.4
Example 8
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. The pulp was then agitated

with a quantity of aluminum sulfate corresponding to two pounds per ton of
solids for five minutes. A quantity of disodium hydrogen phosphate corres-




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ponding to 7~5 pounds per ton of solids was then added. The pulp was then
subjected to flotation as described in Example 1. The results are presented
in the following table.

Weight Percent Distribution %
Product Percent Mo Insol. Mo Insol.
Head 100.00 10.91 68.8 100.0 100.0
Concentrate 42.45 21.29 51.6 82.8 31.8
Tailing 57.55 3.26 81.5 17.2 68.2
Example 9
A sample of~,the composite described in Example 1 was subjected to
the pulping procedure described in Example 1~ The pulp was then agitated
with a quantity of alun~num sulfate corresponding to one pound per ton of
solids for two minutes. A quantity of sodium acid carbonate corresponding
to 7O5 pounds per ton of solids was then addedO The pulp was then subjected
to flotation as described in Example 1. The resul~s are presented in the
following table.

Weight PerGent Distribution %
Pro uct Percent Mo Insol. _ Insol.
Head 100.00 10.99 68.6 100.0 100.0
Concentrate52.51 18.82 55.6 89.9 42.6
Tailing 47.49 2.34 82.9 10.1 57.4
Example 10
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. The pulp was then agitated
with a quantity of chromic sulfate corresponding to four pounds per ton of
solids for fi~e minutes. A quantity of sodium silicate corresponding to 705
pounds per ton of solids was then added to the pulp. The pulp was then
subjected to flotation as described in Example 1. The results are presented
in the following table~

Weight Percent Distribution %
Product Percent M Insol. M

Head 100.00 11.17 69~1 100.0 100~0
Concentrate34.09 29.66 41.7 90.~ 20.6
Tailing 65.91 1.62 83.3 9.6 79.4


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Example 11
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. The pulp was then agitated
with a quantity of chromic sulfate corresponding to four pounds per ton of
solids for five minutes. A quantity of disodium hydrogen phosphate corres-
pondi~ng to 7.5 pounds per ton of solids was then added to ithe pulp. The
pulp was then subjected to flotation as described in Example 1. The results
are presented in the following table.

Weight Percent Distribution %
Product Percent Mo Insol. Mo Insol.
Head 100.00 11.34 69.4 100.0 100~0
Concentrate56.21 18.36 30~4 91.0 48~9
Tailing 43.79 2.32 81.0 9.0 51.1
Example 12
A sample of the composite described in Example 1 was subjected to
the pulping procedure described in Example 1. The pulp was then agitated
with a quantity of chromic sulfate corresponding to four pounds per ton of
solids for five miuutes. A quantity of sodium acid carbonate corresponding
to 7.5 pounds per ton of solids was then added to the pulp. The pulp was
then subjected to flotation as described in ~xample 1. The results are pre-

sented in the following table.

~ Percent Distribution %
Product Percent Mo Insol. Mo Insol.
Head 100.00 11.39 69.2 100.0 100.0
ConcentrateSl.38 20.28 56.4 91.5 41.9
Tailing ~8.62 1.99 82.8 8.5 58.1
Exa_~_e 13
The procedure of Example 2 is repeated employing a pulp density ofabout 5% solids, MnC12 (16 pounds per ton of solids) in place of ZnS04 and
sodium silicate (7.5 pounds per ton of solids) with substantially the same
results.

Example 14
The procedure of Example 9 is repeated with a pulp density of about



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1~39~7
1% solids and the water-soluble calcium salts of boron (3 pounds per ton of
solids) with similar resultsO
~ , .
The procedure of Example 6 is repeated with a pulp density of about
45% solids, CdF2 (30 pounds per ton of solids) and ammonium bicarbonate (45
pounds per ton of solids).
Example 16
Method of Determining Acid Insoluble Percentage in Molybdenite
Containing Ore or Concentrate.
Procedure:
1. Weight 0.5 gram of molybdenum concentrate sample and transfer to a
400 ml. beaker. Add 25 ml. of concentrated nitric acid, place on
hot plate and warm slightly. Add approximately 1/3 teaspoon potas-
sium chlorate, place watch glasses on beakers and take to near
dryness.
2. Add 10 ml~ of concentrated hydrochloric acid and again place on the
hot plate and take to near dryness.
3. Add 10 ml. of concentrated hydrochloric acid again and approximately
50 ml~ of distilled water. Place on the hot plate, bring to a boil
and boil for 5 - 10 minutes~
4. Remove from hot plate and filter through 15 cm. Whatman No. 40
(ashless) filter paper. Wash several times with hot distilled water.
5. Place residue in a clay annealing cup and ash in a muffle furnace.
6. Cool and weigh .
Calculation:
Wto _nsol in grams x 100 = % Acid Insol
Wt.sample in grams




Trade Mark

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SUPPLEME~TARY mscLosu
-
As previously stated, the pulp density varies between about 1% and
about 45% solids; however our tests of the process indicate that a more satis-
factory separation is obtained as pulp density decreases, with a preferred
range of about 5% to 15% solids.
The preferred metallic salts of a weak base and strong acid are the
water-soluble sulfates, nitrate, fluoride and chloride salts of the cations:
aluminumg manganese, calcium, magnesium, zinc, copper, cobalt, rlickel7
chromium, iron and cadmium; these strong acids afford the anions chloride~
fluoride, nitrate and sulfate.
The weak acid hydroferrocyanic acid is useful only in the form of-
\ its water-soluble metallic salt when the metal ion is zinc.
The molybdenite concentrate can be enriched, with respect to molyb-
denite as compared to the head, by a factor of about 2 to about 5 times.
E~ample 17
Another sample of low grade molybdenite concentrate that contained a
substantial portion of hydrophobic talc was made into a dilute pulp of
approximately 5% solids in water at ambient temperature in a laboratory flota-
tion cell. This pulp had a pH of 8.3~ The sample so prepared was then
agitated with a quantity of zinc sulfate corresponding to six pounds per ton
of solids for about 30 minutes. The pH of this admixture was measured and
found to be 6.8. Thereafter, one pound per ton of solids of NaOH was mixed
with the pulp so treated resulting in a pH of 7.1. Thereafter, eight pounds
per ton of potassium ferrocyanide was mixed with the aforementioned pulp con-
taining zinc sulfate and NaOH. The resulting admixture had a pH of 8.2. The
said admixture was immediately subjected to froth flotation and the froth
removed for five minutes during which a concentrate was separated with results
as follows:
Percent Weight Percent Mo In Percent Mo Recovered
in Concentrate Head Tail Concentrate in Concentrate
19.9 4.13 0.23 19.88 95.5
The benefits from the above processing will be appreciated by

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comparing said results with the following wherein the said pulp made up to 5%
solids was floated without the addition of our new treating reagents, i~e~,
such as zinc sulfate and potassium ferrocyanide.

Percent Weight Percent Mo In Percent ~o Recovered
in Concentrate Head Tail Concentrate in Concentrate
98.1 4.66 1.34 ~.73 99.4
As a result of repeating the above experiment substituting various
metals for zinc, it was observed that no effective separation of talc from
a molybdenite bearing concentrate was obtained.
Preferred ~ual-Agent Combinations
A. (a). Water so]uble metallic salt of a weak base of which the
cation is selected from the class consisting of aluminum, cadmium, chromium,
cobalt, copper, iron, calcium, magnesium, manganese~ nickel and zinc, and a
strong acid selected from the class consisting of hydrochloric acid, nitric
acid and sulfuric acid affording the anions chloride, nitrate and sulfate,
and
(b). Sodium silicate or potassium silicate.
B. ~; (a). Water soluble metallic salt of a weak base of which the
cation is selected from the class consisting of aluminum, chromium, copper,
manganese, and æinc, and a strong acid selected from the class consisting of
hydrochloric acid, nitric acid and sulfuric acid affording the anions chloride,
nitrate and sulfate~ and
(b)o Sodium bicarbonate, potassium bicarbonate, or ammonium bicar-
bonate.
C. (a). Water soluble metallic salt of a weak base of which the
cation is selected from the class consisting of aluminum, chro~ium, manganese,
and zinc, and a strong acid selected from the class consisting of hydrochloric
acid, nitric acid and sulfuric acid affording the anions chloride, nitrate,
and sulfate, and
(b). Water soluble sodium monohydrogen orthophosphate, potassium

monohydrogen orthophosphate, or ammonium monohydrogen orthophosphate.

D. (a). Water soluble metallic salt of a weak base of which the



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cation is selected from the class consisting of aluminum, cobalt, copper,
manganese~ and zinc, and a strong acid selected from the class consisting o-f
hydrochloric acid, nitric acid and sulfuric acid affording the anions
chloride, nitrate and sulfate, and
(b). Water soluble sodium borate, potassium borate or ammonium
borate.
E. (a). Water soluble metallic salt of a weak base of which the
cation is selected from the class consisting of aluminum, copper, and zinc,
and a strong acid selected from the class consisting of hydrochloric acid,
nitric acid and sulfuric acid affording the anion chloride~ nitrate and
sulfate, and
(b)D Water soluble sodium orthophosphate, potassium orthophosphate
or ammonium Qrthophosphate.
F. (a). Water soluble zinc chloride~ 7inc nitrate~ or zinc sulfate~
and
(b)~ Sodium carbonate, potassium carbonate, ammonium carbonate~
sodium ferrocyanide, potassium ferrocyanide or ammonium ferrocyanide.
Go (a). Water soluble zinc chloride~ ~inc nitrate~ or zinc sulfate,
and
(b~. Sodium silicate or potassium silicateO




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