FROTHING AGENT FOR FLOTATION OF ORES

Abstract

Described herein are methods for flotation of an ore. The methods include providing an aqueous suspension having an ore in the form of particles, water, and a first frothing agent including a poly(tetrahydrofuran), in a flotation cell to obtain a provided aqueous suspension. The method further includes introducing air into the provided aqueous suspension to obtain a froth. Further described herein are specific aqueous suspensions having ore particles and poly(tetrahydrofuran) and uses of poly(tetrahydrofuran) as a frothing agent for an aqueous suspension having an ore in the form of particles.

Claims

1. A method for flotation of an ore, comprising: (A) providing an aqueous suspension comprising (i) an ore, which is in the form of particles, (ii) water, and (iii) a first frothing agent, in a flotation cell to obtain a provided aqueous suspension; and (B) introducing air into the provided aqueous suspension to obtain a froth, wherein the first frothing agent is a poly(tetrahydrofuran) having a number-average molecular weight M.sub.n in the range of 200 to 1200.

2. The method according to claim 1, wherein the poly(tetrahydrofuran) has a number-average molecular weight M.sub.n in the range of 200 to 1000.

3. The method according to claim 1, wherein the amount of component (iii) in the aqueous suspension is in the range of 0.00001 to 0.1 parts by weight based on 100 parts by weight of component (i).

4. The method according to claim 3, wherein the amount of component (iii) in the aqueous suspension is in the range of 0.0001 to 0.05 parts by weight based on 100 parts by weight of component (i).

5. The method according to claim 1, wherein the amount of component (ii) in the aqueous suspension is in the range of 70 to 1100 parts by weight based on 100 parts by weight of component (i).

6. A The method according to claim 1, wherein at least 80 percent by weight of the ore particles pass a 500 .Math.m sieve.

7. A The method according to claim 1, wherein the ore comprises a first mineral, which is a sulfide mineral, a phosphate mineral, a silicate mineral, a carbonate mineral, a fluoride mineral, a chloride mineral, an oxide mineral, a copper mineral, a molybdenum mineral, a zinc mineral, a lead mineral, a nickel mineral, an iron mineral, a manganese mineral, a titanium mineral, a cobalt mineral, a tungsten mineral, a vanadium mineral, a tin mineral, an aluminium mineral, a lithium mineral, a scandium mineral, a yttrium mineral, a lanthanum mineral, a cerium mineral, a praseodymium mineral, a neodymium mineral, a samarium mineral, an europium mineral, a gadolinium mineral, a terbium mineral, a dysprosium mineral, a holmium mineral, an erbium mineral, a thulium mineral, a ytterbium mineral, a lutetium mineral, a ruthenium mineral, a rhodium mineral, a palladium mineral, a silver mineral, an osmium mineral, an iridium mineral, a platinum mineral, a gold mineral or a combined mineral, which has a chemical composition assigning the combined mineral to two or more of the aforementioned minerals at the same time.

8. The method according to claim 1, wherein at (B) the provided aqueous suspension is stirred during introducing of air.

9. The method according to claim 1, wherein at (B) the provided aqueous suspension is kept at atmospheric pressure during introducing of the air.

10. The method according to claim 1, wherein at (B) the provided aqueous suspension has a temperature in the range of 0° C. to 50° C. during introducing of the air.

11. The method according to claim 1, wherein (A) the provided aqueous suspension contains less than 10 parts by weight of an isocyanate based on 100 parts by weight of component (iii).

12. The method according to claim 1, wherein (A) the provided aqueous suspension contains less than 10 parts by weight of cellulose fibers based on 100 parts by weight of component (i).

13. The method according to claims 7, wherein the ore comprises the first mineral and a second mineral, which is different to the first mineral.

14. A The method according to claim 1, further comprising: (C) separating the froth from the flotation cell to obtain a froth concentrate and a cell concentrate.

15. The method according to claim 14, wherein at (C) the weight ratio between the first mineral and the second mineral is higher in the obtained froth concentrate than the weight ratio between the first mineral and the second mineral in the obtained cell concentrate.

16. The method according to claim 1, wherein at (A) the aqueous suspension further comprises (iv) a first flotation auxiliary, which is different to poly(tetrahydrofuran) and is a collector, a second frothing agent, a depressing agent, an extender oil or a pH-regulating substance, or (v) a second flotation auxiliary, which is different to poly(tetrahydrofuran) and is a collector.

17. The method according to claim 16, wherein (iv) the first flotation auxiliary is a collector or the second frothing agent, optionally, wherein the second frothing agent is a cyclic terpene alcohol, methylisobutyl carbinol, a non-cyclic C.sub.6-C.sub.12 alcohol, a high-boiling fraction from the oxo-synthesis of 2-ethylhexanol, an alcoholic aliphatic ester, triethoxybutane, an ethoxylated and/or propoxylated non-cyclic C.sub.1-C.sub.6 alcohol, polyethylene glycol or polypropylene glycol.

18. The method according to claim 16, wherein (iv) the first flotation auxiliary, an ionic collector, which is an anionic surface-active substance, an amphoteric surface-active substance or a cationic surface-active substance, a non-ionic surface-active compound, which is a non-ionic collector or a second frothing agent, a depressing agent, an extender oil or a pH-regulating substance.

19. (canceled)

20. A The method according to claim 19, wherein the second frothing agent is a cyclic terpene alcohol, methylisobutyl carbinol, a non-cyclic C.sub.6-C.sub.12 alcohol, a high-boiling fraction from the oxo-synthesis of 2-ethylhexanol, an alcoholic aliphatic ester, triethoxybutane, an ethoxylated and/or propoxylated non-cyclic C.sub.1-C.sub.6 alcohol, polyethylene glycol or polypropylene glycol.

21-23. (canceled)

24. An aqueous suspension comprising: (i) an ore, which is in the form of particles, (ii) water, and (iii) a first frothing agent, wherein the frothing agent is a poly(tetrahydrofuran), the amount of component (iii) in the aqueous suspension is in the range of 0.00001 to 0.1 parts by weight based on 100 parts by weight of component (i), and wherein the amount of component (ii) in the aqueous suspension is in the range of 100 to 1000 parts by weight based on 100 parts by weight of component (i).

25. A method of using a first frothing agent as a component (iii) of an aqueous suspension, comprising: combining the first frothing agent with an ore, which is in the form of particles, and (ii) water to form the aqueous suspension; and generating froth in a flotation cell by introducing air into the aqueous suspension within the flotation cell, wherein the first frothing agent is a poly(tetrahydrofuran).

Description

[0116] FIGS. 1 and 2 are attached and described below.

[0117] FIG. 1 shows a picture of the two-phase test of example E-1 with an aerated aqueous solution of Poly THF 250.

[0118] FIG. 2 shows a picture of the two-phase test of example E-1 with an aerated aqueous solution of Poly THF 650.

[0119] The following examples illustrate further the invention without limiting it. Percentage values are percentage by weight if not stated differently.

A) Methods For Characterization

[0120] A number-average weight of a poly(tetrahydrofuran) is determined by a wet-chemically determined hydroxyl number.

B) Agents

B.1) Collector/Collecting Agent

[0121] Xanthate is sodium isobutyl xanthate (SIBX) [CAS 25306-75-6] with molecular formula C5H9NaOS2 and molecular mass 172.2.

[0122] SIBX is commercially available for example from Redox.

B) Frothing Agents

[0123] MIBC is methyl isobutyl carbinol resp. 4-methyl-2-pentanol [CAS-No. 108-11-2] with a molecular weight of 88.1 g/mol as depicted below

##STR00021##

[0124] It is commercially available for example from Sigma-Aldrich Ltd.

[0125] Butyl Triglycol is Triethylene glycol monobutyl ether [CAS-No. 143-22-6] with Molecular Formula C10H22O4 and Molecular Mass of 206.28.

[0126] It is commercially available for example from Sigma-Aldrich Ltd.

[0127] High-boiling fraction from 2-ethyl-1-hexanol manufacturing process (HBF-2EH) [CAS 68609-68-7], which is a combination of hydrocarbons in the range of C4 through C16 produced by the distillation of products from a 2-ethyl-1-hexanol manufacturing process and boiling in the range of 199° C. to 308° C. (390° F. to 586° F.).

[0128] Polypropylene Glycol (230MW) [CAS-No. 25322-69-4] is a polymer of the monomer propylene glycol with a molecular weight of 230 g/mol and can be depicted as H(C3H6O)nOH and is commercially available for example from Sigma-Aldrich.

[0129] Poly THF 250 is a poly(tetrahydrofuran) resp. H(OCH2CH2CH2CH2)xOH [CAS-No. 25190-06-1] as depicted below

##STR00022##

with a number-average molecular weight Mn of 250. It is commercially available for example from Sigma-Aldrich Ltd. The grade commercially available from Sigma-Aldrich Ltd contains 2,6-di-tert-butyl-4-methyl-phenol as stabilizer in an amount below 0.05 wt.%.

[0130] Poly THF 650 is a poly(tetrahydrofuran) resp. H(OCH2CH2CH2CH2)yOH [CAS-No. 25190-06-1] as depicted below

##STR00023##

with a number-average molecular weight Mn of 650. It is commercially available for example from Sigma-Aldrich Ltd. The grade commercially available from Sigma-Aldrich Ltd contains 2,6-di-tert-butyl-4-methyl-phenol as stabilizer in an amount between 0.05 wt.% and below 0.07 wt.%.

C) Aeration Of An Aqueous Suspension Of Solids

Example C-1: Aeration of an Aqueous Phosphate Ore Pulp

[0131] For testing a system with three phases, an amount of ore calculated as 1000 g of dry ore are set in a 2.2 L flotation cell of a Denver D12 flotation machine and water is added to obtain an aqueous pulp with 34% solids content by weight. The ore is a ground phosphate ore, where fine particles are removed (deslimed oxide) and the 1000 g are without slimes. 80 wt.% of the particles of the phosphate ore pass a 250 .Math.m sieve. The flotation machine is turned on and its impeller rotation speed is set to 1000 revolutions per minute, which ensures an adequate suspension of solids. A frothing agent is added as defined in table C-1 to the agitated pulp and conditioned for 1 minute.

[0132] A collector is not added to the pulp (aqueous suspension) to avoid a contribution of the collector to a foam generation. Air is introduced as a regulated flow at varying flow rates as defined in table C-1. The froth is allowed to reach a steady state over 30 seconds and then the froth height is measured. The temperature of the stirred suspension is room temperature (around 20° C.), i.e. there is no heating or cooling. The surrounding pressure is atmospheric pressure. Results of the measured froth heights are listed in table C-1.

TABLE-US-00001 example No. frothing agent dose (g/t].sup.c) froth height [mm] at air flow rates [L / h].sup.d) 200 300 400 500 C-1-1.sup.a) MIBC 10 2 3 5 - C-1-2.sup.b) Poly THF 250 10 4 6 8 9 C-1-3.sup.a) MIBC 30 2 5 7 - C-1-4.sup.b) Poly THF 250 30 9 11 13 14 Footnotes: a) comparative b) inventive c) gram per ton of dry ore d) liter of air per hour

[0133] Table C-1 shows that [0134] by comparison of examples C-1-2 with C-1-1 and C-1-4 with C-1-3, Poly THF 250 generates a froth height, which is at the same applied amount higher than the one of MIBC; [0135] by comparison of examples C-1-2 with C-1-3, Poly THF 250 generates a froth height, which is not reached by MIBC even at a tripled amount.

Example C-2: Aeration of a Copper Molybdenum Sulfide Ore Pulp

[0136] For testing a system with three phases (water-air-solids), an amount of ore calculated as 1000 g of dry ore are set in a 2.2 L flotation cell of a Denver D12 flotation machine and water is added to obtain an aqueous pulp with 34% solids content by weight. The ore is a ground copper molybdenum sulfide ore. 80 wt.% of the particles of the copper molybdenum sulfide ore pass a 150 .Math.m sieve. The flotation machine is turned on and its impeller rotation speed is set to 1000 revolutions per minute, which ensures an adequate suspension of solids. A frothing agent is added as defined in table C-2 to the agitated pulp and conditioned for 1 minute. A collector is not added to the pulp (aqueous suspension) to avoid a contribution of the collector to a foam generation. Air is introduced as a regulated flow at varying flow rates as defined in table C-2. The froth is allowed to reach a steady state over 30 seconds and then the froth height is measured. The temperature of the stirred suspension is room temperature (around 20° C.), i.e. there is no heating or cooling. The surrounding pressure is atmospheric pressure. Results of the measured froth heights are listed in table C-1.

TABLE-US-00002 example No. frothing agent dose [g / t].sup.c) froth height [mm] at alr flow rates [L / h].sup.d) 200 300 400 500 600 C-2-1.sup.a) MIBC 10 5 8 11 14 15 C-2-2.sup.b) Poly THF 250 10 7 10 13 15 17 C-2-3.sup.a) MIBC 30 5 8 12 15 16 C-2-4.sup.b) Poly THF 250 30 10 13 17 22 27 Footnotes: a) comparative b) inventive c) gram per ton of dry ore d) liter of air per hour

[0137] Table C-2 shows that [0138] by comparison of examples C-2-2 with C-2-1 and C-2-4 with C-2-3, Poly THF 250 generates a froth height, which is at the same applied amount higher than the one of MIBC; [0139] by comparison of examples C-2-2 with C-2-3, Poly THF 250 generates a froth height, which is mostly not reached by MIBC even at a tripled amount.

D) Flotation of an Aqueous Suspension of Solids

Example D-1: Flotation of a Copper Molybdenum Sulfide Ore

[0140] A ground copper molybdenum sulfide ore is subjected to flotation employing a collector (SIBX) and a sole frothing agent as indicated in table D-1. All other variables including the collector are remained constant. The obtained flotation results are depicted in table D-1.

TABLE-US-00003 example No. D-1-1.sup.a) D-1-2.sup.b) frothing agent PPG 230.sup.c) Poly THF 250 froth concentrate (= from removed froth) Mass to froth (corresponds to mass recovery) [%] 9.68 9.64 copper grade [%].sup.e) (from removed froth 5.43 5.44 copper recovery [%].sup.f) (amount to froth) 91.6 92.8 molybdenum grade [%] (from removed froth) 0.1830 0.1960 molybdenum recovery [%] (amount to froth) 85.5 86.5 cell concentrate (= tailings remaining in cell) copper grade [%].sup.e) 0.045 0.039 molybdenum grade [%].sup.e) 0.0040 0.0030 Footnotes: a) comparative b) inventive c) standard frothing agent used d) the proportion of feed that reports to the removed froth e) comparative metals analysis f) comparative indicates text missing or illegible when filed

[0141] Table D-1 shows that [0142] by comparison of examples D-1-2 with D-1-1 shows that a change towards Poly THF 250 leads to an improved recovery of copper and molybdenum and a reduced loss of the desired copper and molybdenum into tailings.

Example D-2: Flotation of a Copper Gold Sulfide Ore

[0143] A ground copper gold sulfide ore is subjected to a flotation employing a collector (SIBX) and a sole frothing agent as indicated in table D-2. All other variables including the collector are remained constant. The obtained flotation results are depicted in table D-2.

TABLE-US-00004 example No. D-2-1.sup.a) D-2-2.sup.b) frothing agent MIBC.sup.c) Poly THF 250 froth concentrate (= from removed froth) Mass to froth (corresponds to mass recovery) (%).sup.d) 7.11 7.57 copper grade [%].sup.e) (from removed froth) 10.4 9.86 copper recovery [%] (amount to froth) 74.0 74.9 gold grade [ppm by weight) (from removed froth) 6.0 6.0 gold recovery [%] (amount to froth) 64.8 66.3 cellconcentrate (= tailings remaining in cell) copper grade [%] 0.28 0.27 gold grade [ppm by weight) 0.25 0.25 Footnotes: a) comparative b) inventive c) standard frothing agent used d) the proportion of feed that reports to the removed froth e) comparative metals analysis f) comparative indicates text missing or illegible when filed

[0144] Table D-2 shows that [0145] by comparison of examples D-2-2 with D-2-1 a change towards Poly THF 250 leads to an improved recovery of copper and gold and a reduced loss of the desired copper into tailings.

D-3 Flotation of a Copper Sulfide Ore

[0146] A ground copper sulfide ore is subjected to flotation employing a collector (SIBX) and a sole frothing agent as indicated in table D-3. All other variables including the collector are remained constant. The obtained flotation results are depicted in table D-3.

TABLE-US-00005 Example No D-3-1.sup.a) D-3-2.sup.a) D-3-3.sup.a) D-3-4.sup.(a D-3-59.sup.(a Frothing agent Poly THF 250 Butyl Triglycol.sup.c) MIBC.sup.c) HBF-2EH.sup.c) Polypropylene Glycol (230MW).sup.c) Mass to froth (corresponds to mass recovery) [%].sup.c) 20.2 20.4 20.8 23.7 15.6 froth concentrate (= from removed froth) copper grade [%] .sup.e) (from removed froth) 10.5 9.72 8.98 8.20 11.0 copper recovery [%].sup.f) (amount to froth) 79.9 78.5 78.4 76.1 73.3 Footnotes: a) comparative b) inventive c) standard frothing agent used d) the proportion of feed that reports to the removed froth e) comparative metals analysis f) comparative

[0147] Table D-3 shows that:

[0148] PolyTHF 250 results in the highest amount of copper reporting to the froth (recovery) compared to other standard frothing agent used.

D-4 Flotation of a Copper Ore With a Binary Mixture of Frothing Agents

[0149] A ground copper sulfide ore is subjected to flotation employing a collector (SIBX) and either a mixture of two frothing agents, one of it being PolyTHF 250, or the single frothing agent without PolyTHF 250. All other variables including the collector are remained constant. The obtained flotation results are depicted in table D-4-1.

TABLE-US-00006 Example No Frothing agent 1 Frothing agent 2 Mass to froth % copper grade [%].sup.e) (= from removed froth) Copper recovery (Amount to froth) [%].sup.f) D-4-1.sup.a) MIBC.sup.c) (100 wt%) PolyTHF 250 (0 wt%) 20.8 8.98 78.4 D-4-2.sup.b) MIBC (70 wt%) PolyTHF 250 (30 wt%) 21.7 9.19 79.7 D-4-3.sup.a) Butyl Trigiycol.sup.c) (100%) PolyTHF 250 (0%) 20.4 9.72 78.5 D-4-4.sup.b) Butyl Trigtycol (70%) PolyTHF 250 (30%) 19.2 10.5 78.6 D-4-5.sup.a) HBF-2EH (100%).sup.c) PolyTHF 250 (0%) 23.7 8.20 76.1 D-4-6.sup.b) HBF-2EH (70%) PolyTHF 250 (30%) 21.2 9.73 77.7 D-4-7.sup.a) Polypropylene Glycol (230MW).sup.c) 100% PolyTHF 250 (0%) 15.6 11.0 73.3 D-4-8.sup.b) Polypropylene Glycol(230MW) (70%) PolyTHF 250 (30%) 15.4 11.9 74.0 Footnotes: a) comparative b) inventive c) standard frothing agent used e) comparative metals analysis f) comparative

[0150] Table D-4 shows that:

[0151] By already partially substituting standard frothing agent with PolyTHF 250 (here up to 30%) an increase in the amount of copper that is reporting to the recovered froth can be demonstrated, and Partial substitution results as well in an increase in the grade of copper recovered in the froth.

CONCLUSIONS

[0152] When evaluating the performance from flotation experiments under this section D), the ratio of metal recovery compared to the mass recovered is a parameter indicating superior performance. The grade of the product (concentrate) relates very often directly to the mass recovered. However, a higher mass recovery for the same metal recovery may still result in a lower grade product. Thus, the value of the metal recovery is to be prioritized to the value of the mass recovery.

[0153] Summarizing the evaluation of the flotation examples herein above it can be observed and concluded that [0154] -When comparing such tests, the recovery of the respective metal is the value of most significance (as stated above), and [0155] -those tests turn out to be best performing, where the amount of the metal, e.g. the copper, is the highest, although the mass to froth may be at the lower end. This results in an elevated metal, respectively copper, grade

E) Aeration of an Aqueous Solution

[0156] For a two-phase system (water-air), an aqueous solution of Poly THF 250 and an aqueous solution of Poly THF 650, both with the same concentration, are prepared. The aqueous solution of Poly THF 250 is placed in a laboratory flotation machine with an impeller, stirred and air is introduced at a constant flow rate. The temperature of the aqueous solution is room temperature (around 20° C.), i.e. there is no heating or cooling. The surrounding pressure is atmospheric pressure. The shaft of the impeller has a black marking ring to allow a relative comparison of froth heights. After the froth height has stabilized, a picture is taken (= FIG. 1). The test is repeated under identical conditions with the aqueous solution of Poly THF 650 and a picture is taken (= FIG. 2).

[0157] For the aqueous solution with Poly THF 250, the obtained froth and its height is depicted at FIG. 1. For the aqueous solution with Poly THF 650, the obtained froth and its height is depicted at FIG. 2.

[0158] A comparison of FIG. 1 and FIG. 2 shows that both Poly THF 250 and Poly THF 650 generate small and persistent bubbles and act as a frothing agent. Bubble stability is increased respectively bubble coalescence is reduced for Poly THF 250 versus Poly THF 650, which is demonstrated by the height of the generated foam in view of a more stable foam rising higher due to increased bubble stability respectively reduced coalescence. The height of the froth at FIG. 1 with Poly THF 250 reaches the upper end of the black marking at the shaft of the impeller, whereas the height of the froth at FIG. 2 with Poly THF 650 stays below the upper end of the black marking at the shaft of the impeller. A higher bubble stability provides a greater probability of supporting a coarse particle.