A process for separating and recovering minerals, such as molybdenum or graphite, from ores with which they occur by addition of an amino mercaptothiadiazole to an ore flotation process.

BACKGROUND OF INVENTION 
The present invention relates generally to flotation processes for 
recovering desired minerals from ores containing those minerals. In 
another aspect, this invention relates to a process wherein sulfide 
minerals are separated from other sulfide minerals with which they occur 
by addition of an amino mercaptothiadiazole to an ore flotation process. 
Flotation processes are known in the art and are used for concentrating and 
recovering minerals from ores. In froth flotation processes, the ore is 
crushed and wet ground to obtain a pulp. Additives such as mineral 
flotation or collecting agents, frothers, depressants, and stabilizers are 
added to the pulp to assist separating valuable materials from undesirable 
or gangue portions of the ore in subsequent flotation steps. The pulp is 
then aerated to produce a froth at the surface. The minerals which adhere 
to the bubbles or froth are skimmed or otherwise removed and the mineral 
bearing froth is collected and further processed to obtain the desired 
minerals. Typical mineral flotation collectors include xanthates, amines, 
alkyl sulfates, arene sulfonates, dithiocarbamates, dithiophosphates, and 
thiols. Frequently, other chemicals are added to the separated 
mineral-bearing froth to assist in subsequent separations particularly 
when significant proportions of two or more minerals are present in the 
separated mineral-bearing froth. Such chemicals are known as depressants. 
These materials are used to selectively separate one type of mineral from 
another type of mineral. 
While the art of ore flotation has reached a significant degree of 
sophistication, it is a continuing goal in the ore recovery industry to 
increase the productivity of ore flotation processes and above all to 
provide specific processes which are selective to one ore or to one 
mineral over other ores or other minerals, respectively, which are present 
in the treated material. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to provide an improved process 
for recovering desired minerals from ores containing such minerals. 
It is also the object of this invention to provide a process for recovery 
of molybdenum from ores in which it occurs. 
It is another object of this invention to provide a process for recovery of 
graphite from other minerals with which it occurs. 
It is still another object of this invention to provide a process for 
recovery of molybdenum from the metallurgical concentrates in which it 
occurs. 
In accordance with this invention, it has now been found that amino 
mercaptothiadiazoles are very effective in the recovery of desired 
minerals from ores containing those minerals in ore flotation processes. 
In one more specific embodiment of this invention, a process is provided 
for the recovery of molybdenum from the ore in which it occurs by the 
addition of an amino mercaptothiadiazole in an ore flotation process. 
In a second embodiment of this invention, a process is provided for the 
recovery of graphite from other minerals with which it occurs by the 
addition of an amino mercaptothiadiazole in an ore flotation process. 
In a third embodiment of this invention, a process is provided for the 
recovery of molybdenum from a metallurgical concentrate obtained in a 
first flotation step by the addition of an amino mercaptothiadiazole in 
subsequent flotation steps in a flotation process. 
DETAILED DESCRIPTION OF THE INVENTION 
In accordance with the present invention, there is provided a process for 
recovering at least one desired mineral from a mineral ore containing the 
at least one desired mineral. The ore flotation process of this invention 
distinguishes over the known ore flotation processes primarily in the 
employment of a new treating agent to be defined. The flotation process 
comprises carrying out a mineral flotation with a treating agent present, 
wherein the treating agent is an amino mercaptothiadiazole having the 
formula: 
##STR1## 
wherein M is selected from the group consisting of hydrogen and alkali 
metal atoms. 
Generally, the flotation process will utilize a composition comprising the 
amino mercaptothiadiazole, water, and the mineral material. The treating 
agent of the present invention can be used to depress copper sulfides in 
the presence of molybdenum. The recovery of other mineral sulfides, such 
as those based on Pb, Fe, Zn, Ni, Sb, etc., are considered within the 
scope of this invention. In ores, the metals are usually in a solid 
sulfided state and form a slurry, which can be finely divided, as in a 
pulp. For example, the invention can be employed to process an ore slurry 
containing high copper values. The invention can also be employed to 
process a concentrate, such as a concentrate which contains high 
molybdenum values. Exemplary ores include the following: 
______________________________________ 
Molybdenum-Bearing Ores 
Molybdenum MoS.sub.2 
Wulfenite PbMoO.sub.4 
Powellite Ca(MO,W)O.sub.4 
Ferrimolybdite Fe.sub.2 Mo.sub.3 O.sub.12.8H.sub.2 O 
Copper-Bearing Ores 
Covallite CuS 
Chalcocite Cu.sub.2 S 
Chalcopyrite CuFeS.sub.2 
Bornite Cu.sub.5 FeS.sub.4 
Cubanite Cu.sub.2 SFe.sub.4 S.sub.5 
Valerite Cu.sub.2 Fe.sub.4 S.sub.7 or Cu.sub.3 Fe.sub.4 
S.sub.7 
Enargite Cu.sub.3 (As,Sb)S.sub.4 
Tetrahedrite Cu.sub.3 SbS.sub.2 
Tennanite Cu.sub.12 As.sub.4 S 
Stannite Cu.sub.2 S.FeS.SnS.sub.2 
Bournonite PbCuSbS.sub.3 
Leading-Bearing Ore 
Galena PbS 
Antimony-Bearing Ore 
Stibnite Sb.sub.2 S.sub.3 
Kermesite Sb.sub.2 S.sub.2 O 
Zinc-Bearing Ore 
Sphalerite ZnS 
Silver-Bearing Ore 
Argentite Ag.sub.2 S 
Stephanite Ag.sub.5 SbS.sub.4 
Polybasite 9Ag.sub.2 S.Sb.sub.2 S.sub.3 
Iron-Bearing Ore 
Pyrite FeS.sub.2 
Pyrrohotite Fe.sub.5 S.sub.6 to Fe.sub.16 S.sub.17 
Arsenopyrite FeAsS 
Marmatite (ZnFe)S 
Nickel-Bearing Ore 
Millerite NiS 
Pentlandite (FeNi)S 
Ullmannite NiSbS 
______________________________________ 
Generally, the solids to be processed will be present as a slurry in water 
which contains the treating agent, with the treating agent being present 
in an amount of about 0.01 to about 20 pounds per ton of the solids. The 
slurry usually contains between about 10 and 75 percent solids preferably 
in the range of 15-60 weight percent solids, depending on the processing 
stage. Preferably, the amino mercaptothiadiazole is present in the 
composition in an amount in the range of about 0.01 to about 3 pounds per 
ton of solids. Even more preferably, the amino mercaptothiadiazole is 
present in an amount in the range of about 0.04 to about 2 pounds per ton 
of the solids. The preferred amino mercaptothiadiazole is 
2-amino-5-mercapto-1,3,4-thiadiazole. The flotation process usually 
involves the steps of: 
(a) mixing crushed or ground mineral material with water and the treating 
agent defined above to establish a pulp, 
(b) aerating the pulp to produce a froth and a pulp, 
(c) separating the froth from the pulp and producing a concentrate product 
and a tail product, and 
(d) recovering minerals from the so separated concentrate and/or tail 
product. 
Recovery after additional flotation and frothing steps is optional. In the 
method of the present invention, the treating agent may be added to the 
concentrate obtained from a first flotation step and the concentrate then 
subjected to a subsequent flotation step. The desired minerals may then be 
recovered from the resulting concentrate and/or tail. 
Mineral flotation or collecting agents, frothers, and stabilizers can also 
be used in the various steps. 
The inventive depressant can be used together with other depressants or 
depression steps if desired. For example, the depressant composition 
defined above can be used with additional depressants, such as sodium 
cyanide, sodium ferrocyanide, lime and zinc sulfate, in the treatment of 
an ore. 
Any froth flotation apparatus can be used in this invention. The most 
commonly used commercial flotation machines are the Agitair (Galigher 
Co.), Denver D-12 (Denver Equipment Co.), and the Fagergren (Western 
Machinery Co.). 
The instant invention was demonstrated in tests conducted at ambient room 
temperature and atmospheric pressure. However, any temperature or pressure 
generally employed by those skilled in the art is within the scope of this 
invention.

EXAMPLE 
This example shows the effectiveness of 2-amino-5-mercapto- 
1,3,4-thiadiazole as a copper sulfide and iron sulfide depressant using 
three different methods of addition of the depressant composition. In a 
rod mill, 1000 g of a molybdenum bearing ore (Morenci, Oreg.), 800 ml 
water, 1.67g lime and 0.05 lbs of 2-amino-5-mercapto-1,3,4-thiadiazole per 
ton of ore were ground for 5 minutes to obtain a pulp. The pulp was 
conditioned for 1 minute at 1950 rpm after addition of 0.13 lb/ton Frother 
F2X (30% isopherone, 70% Kodak 750) and floated 5 minutes at a pH of 10.5 
in a Denver D12, 2.5 liter cell. The depressant was added to the grind in 
run number 1 as a dry powder (.025g), in run number 2 as a 0.5% solution 
(with 3 drops 50% NaOH solution to 25 ml water.), and in run number 3 as a 
0.5% solution but with no lime added to the grind. The percent average 
recovery of molybdendum, copper, and iron are shown in the following 
table. 
TABLE 
______________________________________ 
Effect of 2-amino-5-mercapto-1,3,4,thiadiazole, as a Cu and 
Fe Depressant in Mo Ore Flotation 
Conc. % Recovery Calculated Heads** 
Run lb/ton* Cu Fe Mo Cu Fe Mo 
______________________________________ 
1 .05 15.08 5.41 44.08 
0.435 3.050 0.0089 
2 .05 21.22 9.23 48.18 
0.433 2.848 0.0091 
3 .05 28.73 8.81 39.25 
0.420 2.871 0.0084 
______________________________________ 
*Pounds of chemical per ton of ore 
**Amount of Cu, Fe, and Mo in ore 
As can be seen from this table a much larger percent of Mo was recovered 
compared to either Cu or Fe. 2-amino-5-mercapto-1,3,4-thiadiazole is 
therefore an effective depressant for copper as well as iron in the 
presence of molybdenum. 
While this invention has been described in detail for the purpose of 
illustration, it is not to be construed as limited thereby but is intended 
to cover all changes and modifications within the spirit and scope thereof 
.