OA17668A - Method for recovering a copper sulfide from an ore containing an iron sulfide. - Google Patents
Method for recovering a copper sulfide from an ore containing an iron sulfide. Download PDFInfo
- Publication number
- OA17668A OA17668A OA1201600011 OA17668A OA 17668 A OA17668 A OA 17668A OA 1201600011 OA1201600011 OA 1201600011 OA 17668 A OA17668 A OA 17668A
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- Prior art keywords
- hydrogen peroxide
- added
- concentration
- pulp
- minerai
- Prior art date
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- BWFPGXWASODCHM-UHFFFAOYSA-N Copper monosulfide Chemical compound [Cu]=S BWFPGXWASODCHM-UHFFFAOYSA-N 0.000 title claims abstract description 30
- GNVXPFBEZCSHQZ-UHFFFAOYSA-N iron(2+);sulfide Chemical compound [S-2].[Fe+2] GNVXPFBEZCSHQZ-UHFFFAOYSA-N 0.000 title claims abstract description 8
- MHAJPDPJQMAIIY-UHFFFAOYSA-N hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 247
- 239000012141 concentrate Substances 0.000 claims abstract description 42
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 42
- 239000001301 oxygen Substances 0.000 claims abstract description 42
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims abstract description 42
- 238000005188 flotation Methods 0.000 claims abstract description 41
- 238000009291 froth flotation Methods 0.000 claims abstract description 21
- 230000001143 conditioned Effects 0.000 claims abstract description 16
- 238000000227 grinding Methods 0.000 claims description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 18
- 238000002474 experimental method Methods 0.000 claims description 15
- 150000001875 compounds Chemical class 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 claims description 9
- 230000003750 conditioning Effects 0.000 claims description 8
- 239000007789 gas Substances 0.000 claims description 5
- 229910000831 Steel Inorganic materials 0.000 claims description 3
- 239000010959 steel Substances 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 2
- -1 alkyl xanthate Chemical compound 0.000 claims description 2
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 238000001238 wet grinding Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 abstract description 13
- 229910052500 inorganic mineral Inorganic materials 0.000 abstract 2
- 239000011707 mineral Substances 0.000 abstract 2
- 239000010949 copper Substances 0.000 description 60
- 229910052802 copper Inorganic materials 0.000 description 52
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 48
- 238000011084 recovery Methods 0.000 description 40
- 239000010931 gold Substances 0.000 description 31
- 230000001955 cumulated Effects 0.000 description 17
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 16
- 229910052737 gold Inorganic materials 0.000 description 16
- MBMLMWLHJBBADN-UHFFFAOYSA-N iron-sulfur Chemical class [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 11
- 150000004763 sulfides Chemical class 0.000 description 9
- 239000003085 diluting agent Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 238000004166 bioassay Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- 229910052717 sulfur Inorganic materials 0.000 description 4
- 206010053317 Hydrophobia Diseases 0.000 description 3
- 230000000994 depressed Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000005457 optimization Methods 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- RZFBEFUNINJXRQ-UHFFFAOYSA-M Sodium ethyl xanthate Chemical compound [Na+].CCOC([S-])=S RZFBEFUNINJXRQ-UHFFFAOYSA-M 0.000 description 2
- 239000007900 aqueous suspension Substances 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium monoxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 230000003247 decreasing Effects 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 230000001590 oxidative Effects 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L Calcium hydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- RPNUMPOLZDHAAY-UHFFFAOYSA-N DETA Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 1
- VILCJCGEZXAXTO-UHFFFAOYSA-N Triethylenetetramine Chemical compound NCCNCCNCCN VILCJCGEZXAXTO-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 229910000460 iron oxide Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 230000003287 optical Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229920000768 polyamine Polymers 0.000 description 1
- YIBBMDDEXKBIAM-UHFFFAOYSA-M potassium;pentoxymethanedithioate Chemical compound [K+].CCCCCOC([S-])=S YIBBMDDEXKBIAM-UHFFFAOYSA-M 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching Effects 0.000 description 1
- 239000002516 radical scavenger Substances 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000001187 sodium carbonate Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Abstract
In a method for recovering a copper sulfide concentrate by froth flotation from an ore containing an iron sulfide, hydrogen peroxide is added to the conditioned mineral pulp before or during flotation, a concentration of dissolved oxygen is determined in the mineral pulp after addition of hydrogen peroxide and the amount of hydrogen peroxide added is adjusted to maintain a concentration of dissolved oxygen of from 1 to 5 times a predetermined target concentration, in order to adjust the amount of hydrogen peroxide to changes in ore composition.
Description
Field of the Invention
The présent invention is directed to a method of recovering a copper sulfide concentrate from an ore containing an iron sulfide which provides an improvement in concentrate grade and recovery of copper sulfides, has a low consumption of processing chemicals and can be easily adapted to changing ore compositions.
Background of the Invention
The most common method for recovering a copper sulfide concentrate from an ore is by froth flotation. The ore is wet ground to form a minerai pulp, which is usually conditioned with a collector compound that adsorbs to the surface of copper sulfide minerais and makes the surface of copper sulfide minerais more hydrophobie. A gas is then passed through the minerai pulp to form gas bubbles, hydrophobie particles of the minerai pulp attach predominantly to the gas/liquid phase boundary of the bubbles and are carried with the gas bubbles to the froth that forms on top of the minerai pulp. The froth is removed from the liquid surface to recover a copper sulfide concentrate.
Most copper sulfide ores contain iron sulfides in addition to copper sulfides and one aims at achieving sélective flotation of copper sulfides, with iron sulfides remaining in the flotation tailings.
US 5,110,455 discloses a method for separating copper sulfide from rimmed iron sulfide which uses conditioning of the minerai pulp with an oxidant that is preferably hydrogen peroxide. The document teaches to add an oxidant in an amount that raises the redox potential of the minerai pulp by 20 to 500 mV.
A Uribe-Salas et al., Int. J. Miner. Process. 59 (2000) 69-83 describe an improvement in the selectivity for the flotation of chalcopyrite from an ore of pyrite matrix by raising the redox potential of the minerai pulp by 0.1 V through an addition of hydrogen peroxide before flotation. The amount of hydrogen peroxide added is adjusted to provide a constant redox potential.
Summary of the Invention
The inventors of the présent invention hâve found that a substantial improvement in concentrate grade and recovery of copper sulfides can be achieved by addition of small amounts of hydrogen peroxide to the conditioned minerai pulp before or during flotation. Addition of such small amounts of hydrogen peroxide does not lead to an increase in the redox potential of the pulp, as taught in the prior art, but to a decreased redox potential. The inventors hâve also observed that the optimum amount of hydrogen peroxide for such a process does not correspond to a particular value of the redox potential in the minerai pulp and that the curve of the redox potential plotted against the amount of hydrogen peroxide may display several maxima and minima for hydrogen peroxide amounts below and up to the optimum amount. Therefore, the redox potential of the minerai pulp cannot be used to adjust the amount of hydrogen peroxide to the optimum value when changes in the ore composition occur. The inventors of the présent invention hâve further found that the optimum amount of hydrogen peroxide to be used can be determined based on the concentration of dissolved oxygen in the minerai pulp after addition of hydrogen peroxide and that an optimum recovery of copper sulfides can be maintained by adjusting the amount of hydrogen peroxide to maintain a predetermined concentration of dissolved oxygen. This allows adapting the method to changes in the ore composition without carrying out ore assays or extra optimization experiments.
The présent invention is therefore directed to a method for recovering a copper sulfide from an ore containing an iron sulfide, comprising the steps of
a) wet grinding the ore with grinding media to form a minerai pulp,
b) conditioning the minerai pulp with a collector compound to form a conditioned minerai pulp, and
c) froth flotation of the conditioned minerai pulp to form a froth and a flotation tailing, separating the froth from the flotation tailing to recover a copper sulfide concentrate, wherein hydrogen peroxide is added to the conditioned minerai pulp between steps b) and c) or during step c), a concentration of dissolved oxygen is determined in the minerai pulp after addition of hydrogen peroxide and the amount of hydrogen peroxide added is adjusted to maintain a concentration of dissolved oxygen of from 1 to 5 times a predetermined target concentration.
Brief Description of the Drawings
Figure 1 shows redox potential Eh plotted against the amount of added hydrogen peroxide for the experiments of example 1.
Figure 2 shows DO plotted against the logarithm of the amount of hydrogen peroxide added in the experiments of example 1.
Figure 3 shows curves for cumulated copper concentrate grade (y-axis) plotted against cumulated copper recovery (x-axis) for examples 2 and 3.
Figure 4 shows redox potential Eh plotted against the amount of added hydrogen peroxide for the experiments of example 4.
Figure 5 shows DO plotted against the logarithm of the amount of hydrogen peroxide added in the experiments of example 4.
Figure 6 shows curves for cumulated copper concentrate grade (y-axis) plotted against cumulated copper recovery (x-axis) for examples 5 to 7.
Figure 7 shows redox potential Eh plotted against the amount of added hydrogen peroxide for the experiments of example 8.
Figure 8 shows DO plotted against the logarithm of the amount of hydrogen peroxide added in the experiments of example 8.
Figure 9 shows curves for cumulated copper concentrate grade (y-axis) plotted against cumulated copper recovery (x-axis) for examples 9 and 10.
Figure 10 shows redox potential Eh plotted against the amount of added hydrogen peroxide for the experiments of example 11.
Figure 11 shows DO plotted against the logarithm of the amount of hydrogen peroxide added in the experiments of example 11.
Figure 12 shows curves for cumulated copper concentrate grade (y-axis) plotted against cumulated copper recovery (x-axis) for examples 12 and 13.
Detailed Description of the Invention
The method of the invention recovers a copper sulfide concentrate from an ore containing an iron sulfide using three method steps.
In the first step of the method of the invention, the ore is ground with grinding media to form a minerai pulp, i.e. an aqueous suspension of ground ore. Suitable grinding media for grinding ores are known from the prior art. In a preferred embodiment, the grinding media comprise a grinding surface made of steel or cast iron having an iron content of at least 90 % by weight. Grinding can be carried out in any mill known from the art that uses grinding media. Suitable mills are bail mills using balls as grinding media or rod mills using rods as grinding media, with bail mills being preferred. The mill preferably has a lining of an abrasion résistant material.
The ore is wet milled to form a minerai pulp, i.e. an aqueous suspension of ground ore. The ore may be fed to the mill together with water. Alternatively, ore and water are fed separately. Milling is carried out typically to a médian particle size of 50-200 pm. Preferably, the ore is ground to what is called the libération size, i.e. the maximum médian particle size where essentially ail copper sulfide is exposed to the particle surface and essentially no copper sulfide remains encapsulated inside a particle.
In the second step of the method of the invention, the ore is conditioned with a collector compound to form a conditioned minerai pulp. Collector compounds are compounds which after addition to the minerai pulp adsorb to the surface of copper sulfides and render the surface hydrophobie. Collector compounds suitable for froth flotation of copper sulfides are known from the prior art. Preferably, an alkali métal alkyl xanthate is used as collector, such as potassium amyl xanthate or sodium ethyl xanthate. Conditioning is typically carried out by adding the conditioner to the minerai pulp and mixing for a finie period sufficient to achieve adsorption of the conditioner to the minerai surface, typically for less than 15 minutes. Preferably for 0.5 to 15 minutes. Alternatively, the collector is added in the first step of grinding and conditioning is carried out by retaining the minerai pulp for a corresponding time.
Further reagents, such as frothers, pH regulators, depressants and mixtures thereof may be added in the grinding step, the conditioning step or in both steps. Frothers are compounds that stabilize the froth formed in a froth flotation. Suitable frothers are commercially available, e.g. from Huntsman under the trade name Polyfroth®. Depressants are compounds that render the surface of unwanted minerais more hydrophilic. Polyamines known from the prior art, such as diethylenetriamine or triethylenetetraamine, may be used as depressants for iron sulfides. pH regulators, such as calcium oxide, calcium hydroxide or sodium carbonate, may be added to adjust the pH of the minerai pulp to a desired value, preferably to a value in the range from 7 to 11.
In the third step of the method of the invention, the conditioned minerai pulp is subjected to froth flotation to form froth and a flotation tailing, with hydrogen peroxide being added to the conditioned minerai pulp during froth flotation or between the second step of conditioning the minerai pulp and the step of froth flotation. The froth is separated from the flotation tailing to recover a copper sulfide concentrate. Froth flotation may be carried out using equipment and procedures known to a person skilled in the art for the froth flotation of copper ores.
Froth flotation may be carried out as a single stage flotation or as a multiple stage flotation, using e.g.
rougher, scavenger and cleaner stages. In a multiple stage froth flotation, hydrogen peroxide is preferably added before the first flotation stage or during the first flotation stage.
When hydrogen peroxide is added between the step of 10 conditioning the minerai pulp and the step of froth flotation, the time period between addition of hydrogen peroxide and froth flotation is preferably less than min, more preferably less than 3 min and most preferably less than 1 min. Limiting the time period between addition 15 of hydrogen peroxide and froth flotation improves both concentrate grade and recovery of copper suifides.
In a preferred embodiment of the method of the invention, froth flotation is carried out continuously and hydrogen peroxide is added continuously during froth flotation.
Hydrogen peroxide is preferably added as an aqueous solution comprising 0.5 to 5 % by weight hydrogen peroxide.
Adding such a dilute hydrogen peroxide solution provides better concentrate grade and recovery than obtained with the same amount of a more concentrated hydrogen peroxide 25 solution. Therefore, it is preferred to dilute a commercial hydrogen peroxide solution comprising 30 to 70 % by weight hydrogen peroxide to a dilute solution comprising 0.5 to 5 % by weight hydrogen peroxide before adding it in the method of the invention.
The amount of hydrogen peroxide added to the conditioned pulp can be varied over a wide range depending on the ore composition. The method of the invention requires only small amounts of hydrogen peroxide. In general, less than
100 g hydrogen peroxide per ton of ore are needed and preferably less than 50 g/t are used. The method can be carried out with as little as 2 g/t hydrogen peroxide per ton of ore and preferably at least 5 g/t are used.
Usually there will be an optimum amount of hydrogen peroxide per ton of ore that dépends on the ore composition. Increasing the amount of added hydrogen peroxide up to the optimum amount will lead to an increase in concentrate grade and recovery of copper sulfides, whereas increasing the amount of added hydrogen peroxide beyond the optimum amount will not lead to any further improvement, but in general will even lead to a reduced concentrate grade and recovery of copper sulfides. The optimum amount of hydrogen peroxide corresponds to a particular concentration of dissolved oxygen in the minerai pulp after addition of hydrogen peroxide, which concentration dépends on the type of ore. Small variations in the ore composition of a particular ore type, which occur within an ore deposit, will require to adjust the amount of hydrogen peroxide added but will in general not affect the particular value for the concentration of dissolved oxygen that corresponds to an optimum amount of hydrogen peroxide. Therefore, in the method of the présent invention a concentration of dissolved oxygen is determined in the minerai pulp after addition of hydrogen peroxide and the amount of hydrogen peroxide added is adjusted to maintain a concentration of dissolved oxygen of from 1 to 5 times a predetermined target concentration. Preferably, the amount of hydrogen peroxide added is adjusted to maintain a concentration of dissolved oxygen of from 1 to 2 times a predetermined target concentration. Such adjusting can be done either regularly or when a change in ore composition has occurred.
The can concentration of dissolved oxygen m the minerai pulp be determined with equipment known from the prior art.
Preferred sensors for determining the concentration of dissolved oxygen are amperometric sensors or optical sensors that measure oxygen concentration by electrochemical réduction of oxygen or by oxygen caused fluorescence quenching of a dye. The sensor preferably has an oxygen permeable membrane on the oxygen sensing device, which membrane has low permeability for hydrogen peroxide.
The predetermined target concentration of dissolved oxygen to be used in the method of the invention can be determined 10 by carrying out a sériés of flotation experiments varying the amount of hydrogen peroxide added, measuring the concentration of dissolved oxygen in the minerai pulp after addition of hydrogen peroxide, analyzing the copper sulfide concentrate recovered, selecting the critical concentration 15 of dissolved oxygen for which an optimum in concentrate grade and recovery of copper sulfides is achieved and selecting the target concentration as 1.1 to 2 times the critical concentration.
In a preferred embodiment of the method of the invention, the target concentration of dissolved oxygen is determined in a sériés of preliminary experiments in which the amount of added hydrogen peroxide is varied, the concentration of dissolved oxygen is determined in the minerai pulp after addition of hydrogen peroxide, the concentration of dissolved oxygen is plotted over the amount of added hydrogen peroxide to give a curve having an inflection point, a critical concentration of dissolved oxygen is determined as the concentration of dissolved oxygen at the inflection point, and the target concentration is selected as 1.1 to 2 times the critical concentration. Preferably, the concentration of dissolved oxygen is plotted against the logarithm of the amount of added hydrogen peroxide to give a curve having an essentially constant slope on both sides of the inflection point. This embodiment allows selecting a target concentration of dissolved oxygen c/Z without carrying out ore assays or extra optimization experiments.
When grinding media are used which comprise a grinding surface made of steel or cast iron having an iron content of at least 90 % by weight, the curve of the concentration of dissolved oxygen plotted against the logarithm of the amount of added hydrogen peroxide is usually fiat or has a small slope for hydrogen peroxide amounts below the inflection point and has a larger positive slope for hydrogen peroxide amounts above the inflection point. For such grinding media, the target concentration of dissolved oxygen is preferably selected at a value larger than any of the concentrations of dissolved oxygen measured for hydrogen peroxide amounts below the inflection point, in order to ensure stable operation of the method and to avoid dosing too small amounts of hydrogen peroxide.
The method of the invention provides a substantial increase in the concentrate grade and recovery of copper sulfides in a flotation process for recovering a copper sulfide from an 20 ore containing an iron sulfide by adding small amounts of hydrogen peroxide to the conditioned minerai pulp before or during flotation and provides a simple way for adjusting the required amount of hydrogen peroxide to changes in ore composition that does not require ore assays or extra optimization experiments.
The following examples illustrate the invention, but are not intended to limit the scope of the invention.
Examples
In ail flotation experiments, ores were ground to a particle size P80 of 200 pm with a laboratory Magotteaux Mill® using 16*1 inch forged carbon steel rods as grinding media. The resulting minerai pulp was transferred to a laboratory flotation cell and mixed for two minutes to homogenize. Sodium ethyl xanthate was added as collector at 21 g per ton of ore, followed by 5 g per ton of POLYFROTH® H27 frother from Huntsman. The resulting minerai pulp was conditioned for 1 min before flotation was started by introducing air. Four timed concentrâtes were collected during flotation over intervals given in the examples. Each concentrate was collected by hand scraping the froth from the surface of the pulp once every 10 seconds. Concentrâtes were weighed and assayed and cumulated grades and recoveries were calculated from these data. Grades were plotted against recovery and the values for grades at a spécifie copper recovery and recoveries at a spécifie copper grade given in the tables below were read from these curves.
Examples 1 to 3
Flotation was carried out with a sedimentary copper/gold ore having a head assay of 1.74 % Cu, 9.95 % Fe, 3.27 ppm Au, 168 ppm Bi, and 3.21 % S.
In example 1, varying amounts of hydrogen peroxide were added immediately before starting flotation and the redox potential (Eh) and the content of dissolved oxygen (DO) were determined immediately after flotation was started. The results are summarized in table 1. Figure 1 shows the values of Eh plotted against the amount of added hydrogen peroxide. Figure 2 shows a curve of DO plotted against the logarithm of the amount of added hydrogen peroxide. The curve of figure 2 shows an inflection point for a hydrogen peroxide amount of about 66 g/t, with DO slightly decreasing upon addition of smaller amounts and DO rapidly increasing upon addition of larger amounts. The Eh values of figure 1 appear to hâve at least two minima and one maximum for Eh for small amounts of hydrogen peroxide κ/' added. The same Eh as observed for an optimum amount of hydrogen peroxide can also be observed for much smaller amounts of hydrogen peroxide, making Eh unsuitable for adjusting the amount of hydrogen peroxide after changes in 5 ore composition.
Table 1
Variation of added hydrogen peroxide amount
| H2O2 added [g/t] | Example 1 | |
| DO [ppm] | Eh[mV] | |
| 0 | 1.13 | 241 |
| 7.5 | 1.13 | 230 |
| 15 | 1.05 | 220 |
| 30 | 0.95 | 226 |
| 60 | 0.90 | 222 |
| 90 | 1.56 | 227 |
| 120 | 2.20 | 239 |
In examples 2 and 3, flotation was carried out with concentrâtes collected over intervals of 0.5, 2, 5, and 10 minutes. No hydrogen peroxide was added in example 2. In example 3, a 1 % by weight aqueous hydrogen peroxide solution was added in an amount of 75 g/t ore immediately 15 before starting flotation.
Figure 3 shows the curves for cumulated copper concentrate grade plotted against cumulated copper recovery for y/ examples 2 and 3. Tables 2 and 3 compare these results at % copper recovery and at 18 % concentrate copper grade.
Table 2
Copper and gold concentrate grades and gold and diluent recoveries at 85 % copper recovery
| Example | H2O2 added | Grade | Recovery | ||||
| Cu [%] | Au [ppm] | Au [%] | Bi [%] | IS [%] | NSG [%] | ||
| 2* | 0 g/t | 18.2 | 25.0 | 62.5 | 69.2 | 18.8 | 3.6 |
| 3 | 75 g/t | 19.2 | 26.0 | 55.0 | 65.0 | 13.6 | 3.4 |
* Not according to the invention,
IS = iron sulfides, NSG = non sulfide gangue
Table 3
Copper and gold recovery and concentrate gold and diluents grade at 18 % concentrate copper grade
| Example | H2O2 added | Recovery | Grade | ||||
| Cu [%] | Au [%] | Au [ppm] | Bi [ppm] | IS [%] | NSG [%] | ||
| 2* | 0 g/t | 85.7 | 58.8 | 24.7 | 1420 | 6.2 | 41.5 |
| 3 | 75 g/t | 89.3 | 63.3 | 24.7 | 1310 | 4.7 | 42.8 |
* Not according to the invention,
IS = iron sulfides, NSG = non sulfide gangue )V/X
Examples 4 to 7
Flotation was carried out with a volcanogenic sulfide deposit ore having a head assay of 2.63 % Cu, 19.2 % Fe, and 15.9 % S.
In example 4, varying amounts of hydrogen peroxide were added immediately before starting flotation and the redox potential (Eh) and the content of dissolved oxygen (DO) were determined immediately after flotation was started. The results are summarized in table 4.
Table 4
Variation of added hydrogen peroxide amount
| H2O2 added [g/t] | Example 4 | |
| DO [ppm] | Eh[mV] | |
| 0 | 0.74 | 250 |
| 30 | 0.77 | 243 |
| 60 | 0.75 | 237 |
| 120 | 0.74 | 239 |
| 180 | 0.72 | 235 |
| 240 | 1.05 | 236 |
| 300 | 1.49 | 240 |
| 360 | 1.67 | 245 |
Figure 4 shows the values of Eh plotted against the amount 15 of added hydrogen peroxide. Figure 5 shows a curve of DO plotted against the logarithm of the amount of added hydrogen peroxide. The curve of figure 5 shows an inflection point for a hydrogen peroxide amount of about 190 g/t, with no significant change of DO upon addition of smaller amounts and DO rapidly increasing upon addition of larger amounts. The Eh values of figure 4 appear to hâve at least two minima and one maximum for Eh for small amounts of hydrogen peroxide added.
In examples 5 to 7, flotation was carried out with concentrâtes collected over intervals of 0.5, 2, 4, and 7 minutes. No hydrogen peroxide was added in example 5. In examples 6 and 7, a 1 % by weight aqueous hydrogen peroxide solution was added in amounts of 15 g/t ore and 240 g/t ore immediately before starting flotation.
Figure 6 shows the curves for cumulated copper concentrate grade plotted against cumulated copper recovery for examples 5 to 7. Tables 5 and 6 compare these results at 90 % copper recovery and at 18 % concentrate copper grade.
Table 5
Copper and iron concentrate grades and diluent recoveries at 90 % copper recovery
| Example | H2O2 added | Grade | Recovery | |||
| Cu [%] | Fe [%] | Fe [%] | IS [%] | NSG [%] | ||
| 5* | 0 g/t | 15.5 | 26.8 | 18.2 | 10.0 | 4.5 |
| 6 | 15 g/t | 20.5 | 28.8 | 17.7 | 7.7 | 4.1 |
| 7 | 240 g/t | 21.1 | 27.6 | 16.4 | 8.0 | 3.9 |
* Not according to the invention,
IS = iron sulfides, NSG = non sulfide gangue
Table 6
Copper and iron recovery and concentrate diluents grade at % concentrate copper grade
| Example | Η2Ο2 added | Recovery | Grade | |||
| Cu [%] | Fe [%] | Fe [%] | IS [%] | NSG [%] | ||
| 5* | 0 g/t | 91.0 | 18.8 | 26.8 | 19.0 | 28.4 |
| 6 | 15 g/t | 93.5 | 20.2 | 28.1 | 18.0 | 26.4 |
| 7 | 240 g/t | 94.6 | 19.5 | 26.9 | 20.0 | 27.5 |
* Not according to the invention,
IS = iron sulfides, NSG = non sulfide gangue
Examples 8 to 10
Flotation was carried out with a porphyry copper/gold ore having a head assay of 0.43 % Cu, 5.4 % Fe, 0.18 ppm Au and 5.0 % S.
In example 8, varying amounts of hydrogen peroxide were added immediately before starting flotation and the redox potential (Eh) and the content of dissolved oxygen (DO) were determined immediately after flotation was started. The results are summarized in table 7. Figure 7 shows the values of Eh plotted against the amount of added hydrogen peroxide. Figure 8 shows a curve of DO plotted against the logarithm of the amount of added hydrogen peroxide. The curve of figure 8 shows an inflection point for a hydrogen peroxide amount of about 95 g/t, with no significant change of DO upon addition of smaller amounts and DO rapidly increasing upon addition of larger amounts. The Eh values u/'' of figure 7 appear to hâve at least two minima and one maximum for Eh for small amounts of hydrogen peroxide added. The same Eh as observed for an optimum amount of hydrogen peroxide can also be observed for much smaller amounts of hydrogen peroxide, making Eh unsuitable for adjusting the amount of hydrogen peroxide after changes in ore composition.
Table 7
Variation of added hydrogen peroxide amount
| H2O2 added [g/t] | Example 8 | |
| DO [ppm] | Eh[mV] | |
| 0 | 0.40 | 224 |
| 7.5 | 0.40 | 203 |
| 15 | 0.30 | 186 |
| 30 | 0.30 | 199 |
| 60 | 0.30 | 190 |
| 120 | 0.45 | 201 |
| 180 | 0.75 | 210 |
| 240 | 1.00 | 225 |
In examples 9 and 10, flotation was carried out with concentrâtes collected over intervals of 0.5, 2, 4, and 9 minutes. No hydrogen peroxide was added in example 9. In 15 example 10, a 1 % by weight aqueous hydrogen peroxide y//' solution was added in an amount of 120 g/t ore immediately before starting flotation.
Figure 9 shows the curves for cumulated copper concentrate grade plotted against cumulated copper recovery for examples 9 and 10. Tables 8 and 9 compare these results at % copper recovery and at 9 % concentrate copper grade.
Table 8
Copper and gold concentrate grades and gold and diluent recoveries at 70 % copper recovery
| Example | H2O2 added | Grade | Recovery | |||
| Cu [%] | Au [ppm] | Au [%] | IS [%] | NSG [%] | ||
| 9 * | 0 g/t | 6.2 | 1.3 | 35.0 | 14.5 | 3.1 |
| 10 | 120 g/t | 7.2 | 1.7 | 46.0 | 11.2 | 2.6 |
* Not according to the invention,
IS = iron sulfides, NSG = non sulfide gangue vlA”
Table 9
Copper and gold recovery and concentrate gold and diluents grade at 9 % concentrate copper grade
| Example | H2O2 added | Recovery | Grade | |||
| Cu [%] | Au [%] | Au [ppm] | IS [%] | NSG [%] | ||
| 9* | 0 g/t | 60.0 | 27.5 | 1.7 | 33.0 | 41.0 |
| 10 | 120 g/t | 67.0 | 42.5 | 2.0 | 27.0 | 47.0 |
* Not according to the invention,
IS = iron sulfides, NSG = non sulfide gangue
Table 9 shows an additional improvement in the recovery of copper and gold.
Examples 11 to 13
Flotation was carried out with an iron oxide hosted copper/gold ore having a head assay of 0.83 % Cu, 21.7 % Fe, 0.39 ppm Au, 568 ppm As, and 4.0 % S.
In example 11, varying amounts of hydrogen peroxide were added immediately before starting flotation and the redox potential (Eh) and the content of dissolved oxygen (DO) were determined immediately after flotation was started. The results are summarized in table 10. Figure 10 shows the values of Eh plotted against the amount of added hydrogen peroxide. Figure 11 shows a curve of DO plotted against the logarithm of the amount of added hydrogen peroxide. The curve of figure 11 shows an inflection point for a hydrogen peroxide amount of about 64 g/t, with no significant change of DO upon addition of smaller amounts and DO rapidly increasing upon addition of larger amounts. The Eh values of figure 10 appear to hâve a minimum for Eh for small amounts of hydrogen peroxide added. The same Eh as observed for an optimum amount of hydrogen peroxide can also be observed for a much smaller amount of hydrogen peroxide, making Eh unsuitable for adjusting the amount of hydrogen peroxide after changes in ore composition.
Table 10
Variation of added hydrogen peroxide amount
| H2O2 added [g/t] | Example 11 | |
| DO [ppm] | Eh[mV] | |
| 0 | 0.55 | 233 |
| 7.5 | 0.60 | 216 |
| 15 | 0.68 | 203 |
| 30 | 0.63 | 200 |
| 60 | 0.65 | 206 |
| 90 | 1.15 | 214 |
| 120 | 1.57 | 224 |
In examples 12 and 13, flotation was carried out with concentrâtes collected over intervals of 0.5, 2, 4, and 8 minutes. No hydrogen peroxide was added in example 12. In 15 example 13 a 1 % by weight aqueous hydrogen peroxide solution was added in an amount of 50 g/t ore immediately before starting flotation.
Figure 12 shows the curves for cumulated copper concentrate grade plotted against cumulated copper recovery for examples 12 and 13. Tables 11 and 12 compare these results at 80 % copper recovery and at 13 % concentrate copper grade.
Table 11
Copper and gold concentrate grades and gold and diluent recoveries at 80 % copper recovery
| Example | H2O2 added | Grade | Recovery | ||||
| Cu [%] | Au [ppm] | Au [%] | As [%] | IS [%] | NSG [%] | ||
| 12* | 0 g/t | 10.5 | 3.7 | 60.0 | 33.9 | 46.3 | 1.8 |
| 13 | 50 g/t | 12.0 | 3.9 | 59.0 | 27.5 | 38.0 | 1.4 |
* Not according to the invention,
IS = iron sulfides, NSG = non sulfide gangue
Table 12
Copper and gold recovery and concentrate gold and diluents grade at 13 % concentrate copper grade
| Example | H2O2 added | Recovery | Grade | ||||
| Cu [%] | Au m | Au [ppm] | As [ppm] | IS [%] | NSG [%] | ||
| 12* | 0 g/t | 57.5 | 36.0 | 3.8 | 2740 | 42.8 | 19.1 |
| 13 | 50 g/t | 75.0 | 53.0 | 4.0 | 2780 | 41.8 | 20.1 |
* Not according to the invention,
IS iron sulfides,
NSG = non sulfide gangue .13 JAN 2816
EKpN^E LYSAGHT Sari
b. p. ..........................
TéL- Fax.: 22 31 67 53
Claims (7)
1) A method for recovering a copper sulfide from an ore containing an iron sulfide, comprising the steps of
a) wet grinding the ore with grinding media to form a minerai pulp,
b) conditioning the minerai pulp with a collector compound to form a conditioned minerai pulp, and
c) froth flotation of the conditioned minerai pulp to form a froth and a flotation tailing, separating the froth from the flotation tailing to recover a copper sulfide concentrate, wherein hydrogen peroxide is added to the conditioned minerai pulp between steps b) and c) or during step c), a concentration of dissolved oxygen is determined in the minerai pulp after addition of hydrogen peroxide and the amount of hydrogen peroxide added is adjusted to maintain a concentration of dissolved oxygen of from 1 to 5 times a predetermined target concentration.
2) The method of claim 1, wherein the target concentration of dissolved oxygen is determined in a sériés of preliminary experiments in which the amount of added hydrogen peroxide is varied, the concentration of dissolved oxygen is determined in the minerai pulp after addition of hydrogen peroxide, the concentration of dissolved oxygen is plotted over the amount of added hydrogen peroxide to give a curve having an inflection point, a critical concentration of dissolved oxygen is determined as the concentration of dissolved oxygen at the inflection point, and the target concentration is selected as 1.1 to 2 times the critical concentration.
3) The method of claim 1 or 2, wherein the hydrogen peroxide is added less than 15 minutes before a gas is introduced for froth flotation.
4) The method of claim 1 or 2, wherein froth flotation is carried out continuously and hydrogen peroxide is added continuously during froth flotation.
5) The method of any one of daims 1 to 4, wherein hydrogen peroxide is added as an aqueous solution comprising 0.5 to 5 % by weight hydrogen peroxide.
10
6) The method of any one of daims 1 to 5, wherein an alkali métal alkyl xanthate is used as collector.
7) The method of any one of daims 1 to 5, wherein the grinding media comprise a grinding surface made of steel having an iron content of at least 90 % by weight.d
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US61/856439 | 2013-07-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| OA17668A true OA17668A (en) | 2017-06-28 |
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