FI72900C - Flotation procedures for the recovery of minerals from their ores. - Google Patents

Description

72900

The present invention relates to a flotation process in which a gaseous stream is mixed from a flotation liquid and an ore containing iron or copper sulphide and lead or zinc sulphide to obtain a mineral-containing foam, and wherein said iron or copper is taken from the ore.

Ore deposits usually contain more than one valuable mineral. In order for valuable minerals to be sold as separate products, they must be separated. Similarly, valuable minerals must be distinguished from less valuable minerals and the bedrock. Such less valuable minerals and bedrock are often referred to as side-stone. For example, copper sulfide and iron sulfide ores often coexist with other metals, such as zinc and lead sulfides, and these minerals are usually found in their natural state associated with side rock materials.

Flotation methods are one means used to enrich and recover the desired valuable minerals. Such methods can be used to separate one valuable mineral from another and to separate valuable minerals from a side rock. Flotation methods are based on the affinity of a given mineral: particles for bubbles under certain conditions. Bubbles attract and float one or more minerals, while other minerals and side rock materials sink.

In conventional flotation, the ore is ground into fine particles. The finely divided particles are mixed with a flotation liquid such as water, brine, etc. to form an ore slurry. The foam is formed by mixing the slurry while passing a gas stream such as air through the slurry.

Various reagents can be added to the slurry to aid in foaming, flotation of certain minerals, prevention of foaming of certain minerals, etc. These 2,729,000 reagents are often commonly referred to as flotation process aids or flotation agents. These reagents include foaming agents, bulking agents, pH adjusting agents, flocculants, dispersants and printing agents.

Foams are reagents that can be used in ore flotation to help form bubbles and a stable foam in which the minerals to be recovered accumulate. Typical foams include wood distillation turpentine, methyl isobutylmethanol and poly (propylene glycol) methyl ethers.

Collecting agents can be added to the flotation process to help enrich the mineral into the foam. In general, the aggregating agents generate an affinity between the bubble and the respective mineral particle. The bubble can then lift the mineral particle onto the surface of the flotation fluid. It is preferred to use different builders for different minerals; for example, sulfides of lead, zinc, copper, and nickel can be assembled and floated with sulfhydryl-type short chain hydrocarbons (C2-C5). On the other hand, oxide minerals are typically assembled and foamed with long chain (Cp2-C18 fatty acids, sulfonates and amines).

Activators can be added to flotation processes to provide improved adhesive adhesion to the mineral to be flotated. Activators usually act on or adhere to the mineral to be foamed. The activator can also act on or adhere to the aggregate and thus act as a flotation mediator. For example, copper sulfate is known to activate zinc and thus aid in zinc foaming under certain conditions.

A pH adjusting agent can be added to the ore slurry to control the ionization of the collector from its molecular form to its ionic form. This can affect the tensile or repulsive forces between the aggregate and the mineral, the adsorption of the aggregate to the 3,72900 mineral and / or flotation. Various pH adjusting agents, such as acidic or basic compounds, are known in the art.

A dispersant can be added to the flotation system to ensure that co-flocculation of the desired mineral and side rock does not occur. Lignin sulfonates, sodium silicate, tannin and others are typical dispersants.

The flocculant can be added to the flotation step only to cause agglomeration of the desired particles. The flakes can then be removed by flotation. Known flocculants include starches and gums.

A printing agent can be added to the flotation system to prevent or reduce the foaming of certain minerals. A particular printing agent can selectively prevent or reduce the assimilation of a particular mineral or group of minerals or side rock materials into the foam.

For example, in the recovery of copper sulfide, lime can be added as a printing agent. Lime can depress pyrite, which is often present in significant amounts in copper sulfide ores.

Similarly, certain printing materials are known to selectively weigh copper sulfide in the recovery of other minerals under certain flotation conditions. Sodium thiophosphate, U.S. Patent 2,811,255; thioglycolic acid, U.S. Patent 2,449,984; and thioglycerol, U.S. Patent 3,785,488, are known copper sulfide depressants.

It is also known in the art to use, for example, sodium cyanide for the selective pressing of copper and iron sulfides while allowing lead sulfide to float.

72900 Thus, although many revelations and many improvements have been made in the ore flotation industry, which is exploited in mineral recovery, there is considerable room for further improvements. For example, there is a need for pressurizers that selectively precipitate lead and zinc sulfides while allowing copper-containing minerals to float.

In accordance with the present invention, it has been found that the use of beta-mercaptoethanol as an oxygen scavenger in the flotation process improves the efficiency of recovery of the desired minerals from the mineral-containing ore. The invention is thus characterized in that a thickener, beta-mercaptoethanol, is added to the slurry in an amount which contributes to the printing of lead or zinc sulphide. In the following detailed description, beta-mercaptoethanol or 2-mercaptoethanol is alternatively referred to as BME.

According to a first embodiment of the present invention, there is provided a method of recovering at least one desired mineral from a mineral ore containing at least this one desired mineral. In this method, the mineral ore is contacted with BME. The mineral ore thus contacted is subjected to a flotation process in which at least a portion of this at least one desired mineral is separated from the remainder of the mineral ore. Thereafter, at least a portion of the at least one desired mineral thus separated is recovered. In one aspect of the process of this invention, BME is fed to the ore during ore milling. In another aspect of the process of the invention, the oxygen scavenger is fed to a wetting or flotation step. In yet another aspect of the invention, sodium hydrosulfide (NaSH) is used as a disintegrant in flotation. In yet another aspect of the invention, thionocarbonate is used as a bulking agent in flotation.

A flotation operation to recover the desired minerals, which is improved in accordance with this invention, is part of a process in which mineral-containing ores from mines are used as a feedstock to produce the desired mineral or metal in ultimately purified form. This total process involves mainly grinding the ore into a small particle size, possibly one or more washing steps, a flotation operation and subsequent downstream cleaning steps. The flotation operation itself may be a multi-stage process in which the particles are subjected to initial flotation and the foam thus enriched is subjected to one or more subsequent flotation operations. The BME may be added to the milling step or to one or more of the plurality of flotation steps. Likewise, the disintegrant may be added to one or more of the many flotation steps as well as the collector.

The blowing agent or bulking agent used in the flotation steps may be any of the substances or additives well known in the art. Examples of blowing agents useful in the process of this invention include xanthates, amines, alkyl sulfates, arenesulfonates, dithiocarbamates, dithiophosphates, and thiols. Hydrocarbon oils such as kerosene, light oils and petroleum lubricants, as well as combinations of these oils with the bulking agents listed above, are useful in the process of this invention. Particularly effective for the recovery of molybdenum from molybdenum-containing ores are aromatic hydrocarbon oils such as Extract Oil, Fuel Oil and Wood Distillate Turpentine. Such oils are preferably used in combination with bulking agents such as mercaptans, especially normal dodecyl mercaptan and dihydrocarbyl trithiocarbamates.

The amount of blowing agent or bulking agent used depends on other process parameters. The amount is usually in the areas used. For further details regarding the parameters of the ore flotation process, in particular the molybdenum flotation process, reference is made to U.S. Patent 3,785,488, the disclosure of which is incorporated herein by reference.

Examples of disintegrants or printers that can be advantageously used as additives in carrying out the process of this invention include, for example, sodium hydrosulfide (NaSH), 6,729,000 sodium sulfide (Na 2 S), sodium cyanide and sodium silicate, and hydrocolloids such as starch, guar gum, glue, protein and tannins. mixtures of any two or more of these.

It has also been found that a small amount of BME added to the copper-containing ore (chalcosite) flour prior to flotation of the ore slurry thus formed in the presence of isopropyl ethylthionocarbamate as a collector resulted in a roughly 10% improvement in copper recovery in the flotation process.

It has further been found that beta-mercaptoethanol- (2-mercapto-1-hydroxyethane) (BME) is effective as a propellant in the foaming process. It has been found that BME is able to selectively prevent or reduce the foaming of lead and / or zinc sulphide while allowing other minerals such as copper and / or iron sulphide to float.

BME, HOCH CH SH is a water-soluble liquid with a solidified -2 ° C below -46 ° C. BME has no acute toxicity of other excipients such as sodium cyanide.

BME is preferred as a selective media for lead or zinc sulfides that can be recovered or activated with reagents used in flotation to recover copper or iron. With the appropriate use of BME, foams with a substantially reduced concentration of sulfide selected from the group consisting of lead and zinc sulfides can be obtained. The lower concentration of undesirable lead or zinc sulfides preferably results in flotation concentrates of the desired mineral, such as the sulfide selected from the group consisting of iron or copper sulfides.

7,72900 BME has been found to be a highly selective printer. BME primarily weighs down certain metals in the presence of others. This invention relates to the recovery of copper or iron sulfide using BME to selectively depress zinc or lead sulfide. Ores containing copper, iron, lead, and zinc sulfides can thus be enriched using BME to depress lead and zinc sulfides. The phrase "enrich" as used herein refers to increasing the concentration of a desired metal such as copper or iron in a foam by lowering or reducing in part the concentration of an undesirable metal such as lead or zinc in the foam.

According to another embodiment of the present invention, BME is used as a printing agent to provide an improved flotation process. Ore containing lead or zinc sulfides along with other minerals such as copper or iron can be ground to a suitable size for flotation. Preferably, the ore is ground to a particle size of between about 25 and 500 microns. The ore may be dry ground, i.e. the ore may be ground without a flotation or grinding liquid such as water or brine. A flotation liquid such as water can then be added to the dry ground ore to form a slurry. Preferably, the ore wet is ground with a suitable amount of flotation liquid and a residual amount of flotation liquid is added or removed to achieve the desired sludge concentration.

The slurry thus formed can be fed to a conventional flotation cell or a series of such cells. Flotation reagents can be added to the slurry to achieve foaming of the desired minerals. One or more flotation reagents selected from the group consisting of a bulking agent, a blowing agent, an activator, a dispersant, a flocculant, a pH adjusting agent, and a printing agent may be added to the flotation process. For example, bulking agents such as xanthates, dithiocarbamates, dithiophosphates or their salts or other derivatives and the like can be added to the slurry.

„72900 Ο

A gas stream, such as air, can be added to the slurry in the flotation cell to form bubbles and the resulting foam. The slurry and gas stream can be mixed or combined by stirring, stirring, etc. The foam thus obtained should contain a recoverable mineral or mineral concentrate. A set of flotation cells can be used to obtain a higher concentration of the desired mineral in the final foam. The desired mineral can be recovered from the foam by conventional techniques such as filtration, extraction, drying, etc.

It is preferred to add BME as a pressurizer to the flotation process to selectively press zinc and / or lead sulfide ores. BME can be added or combined with the ore before or during the milling step to achieve significant depression of zinc or lead. BME can be added during the wet milling step, typically referred to as post-milling, in which ground ore, flotation fluid and pressurizer are mixed during milling.

It is preferable to add BME as a printing agent to the flotation device or cell, where the printing agent is mixed with the slurry and / or other reagents in the cell during the flotation process. Preferably, when the flotation process includes more than one flotation, such as first flotation and at least one flotation in addition to the first flotation, it is preferred to add BME to the flotation cell after the first flotation to maximize lead and zinc depression. BME is most preferably added before the second flotation to depress the additional amount of zinc and to obtain higher iron or copper recoveries. BME may be added in the same process step where the bulking agent, activator, etc. is added, or BME may be added in a different process step.

It is most preferred to use a first flotation and at least one flotation in addition to the first flotation and a first batch of BME is added to the grinding step prior to the first flotation to primarily depress 9,72900 zinc and a second or subsequent flotation to primarily depress lead. The first and second portions can each be used in each of about 4.5 to 908 g BME per ton of mineral ore and in the preferred ranges shown below.

Depending on the analysis of the ore from which the copper and / or iron is to be recovered, BME may be added to only one cell of the cell series or may be added to more than one cell of the series to obtain optimal settling of lead or zinc sulphide ores when desired in a given foam. The concentrate obtained from the first or germ cell stages in a series of cells can be further processed in additional flotation cells. This further treatment or purification can increase the final content of the desired copper or iron minerals in the final foam. Cleaner concentrates can produce higher grades of discrete mineral products.

It has been found that the amount of BME used in the flotation process can affect its effectiveness as a selective printer. BME can be added to the ore flotation process in an amount that promotes sulfide depression selected from the group consisting of lead and zinc sulfides and promotes buoyancy of the sulfide selected from the group consisting of iron and copper sulfides.

BME can be used as a pressurizer in an amount of about 4.5-908 g per ton of mineral ore. Preferably, BME is used in an amount between about 22.7-454 g of toner per ton of mineral ores. Most preferably, BME is used in an amount of from about 22.7 to 113.5 g BME per ton of ore, which amount best promotes the depletion of lead or zinc sulfide and which amount may allow iron or copper sulfide to float.

BME can be used alone or in combination with other precipitants such as lime, sodium cyanide, hydrophilic polyamines, hydrophilic polycarboxylic acids, sodium thiophosphate, sodium silicate, starch, guar gum, glue, proteins, tannins and other known precipitants. The combination of BME and other pressurizers can be used in a flotation cell or process to settle lead and / or zinc sulfides and other undesirable minerals.

BME can be used as a printing agent in flotation in conjunction with one or more flotation reagents. BME can be used with builders, activators, flocculants, dispersants, pH adjusters, other printing agents, and the like.

BME can be used as a pressurizer in flotation without a bulking agent, etc., whenever the mineral to be recovered is substantially self-floating or inherently buoyant. For example, minerals such as molybdenum, graphite, talc, boric acid, and certain non-oxidized sulfide minerals are inherently substantially buoyant. BME can be used in such a case to depress the foaming of lead or zinc sulfide while allowing a mineral that is inherently buoyant, such as molybdenite, to float.

Although not intended to limit the invention described and claimed herein, it is believed that the depressing mechanism of BME is adsorbed on the crystal lattice of sulfides. It is also believed that the hydroxyethyl mercaptide ion, HO-Cl 2 -Cl 2 -S, behaves similarly to the mercaptor radical -SH in its ability to be absorbed on certain metal surfaces and gives them a hydrophilic nature under certain flotation conditions. Various parameters affect the effectiveness of BME as precipitants for lead and / or zinc sulfides. For example, the presence of other minerals, the level of BME present in the flotation process, the concentration in the crude ore assay, the aggregate or other flotation reagent selected, and other flotation process parameters can affect the effectiveness of BME as a depressant.

11 72900

Ores that can be treated in accordance with the process of this invention can be generally characterized as ores containing sulfide curing. The minerals are sulfided, which means that sulfur is significantly bound directly to metals, while metal-oxygen bonds are absent or present only in negligible amounts. The oxygen scavenging activity of BME has been found to be particularly significant for sulfide fossils of copper, iron, lead, zinc and molybdenum.

Although the total amount of oxygen scavenger, e.g., BME, is not currently believed to be critical, it is preferred to use BME as the scavenger in an amount of approximately 4.5 to 908 g per ton of mineral ore.

The following examples are intended to illustrate the invention in more detail without unduly limiting its scope.

Example I

This example is the first check flotation test. BME was not used in this example. This example shows significant amounts of lead and zinc floating in the presence of copper and iron and without BME as a settling agent.

In this example (and in all subsequent examples) a two flotation experiment was used. That is, certain reagents were added during grinding or just before the first flotation and other specific reagents were added before the second flotation.

1250 ml of water were added to 2500 grams of ore containing 3.18% by weight of lead, 0.39% by weight of zinc, 0.24% by weight of copper and 1.58% by weight of iron. The ore was ground in the presence of water for 9.2 minutes to form a slurry. The ground ore in the slurry was described as 23% + 100 Tyler mesh grinding.

.12,72900 The slurry thus formed was added to a 10 liter Denver flotation cell. Similarly, various reagents were added to the flotation cell. The term "g / t" as used herein refers to the amount of reagent added, expressed in grams of reagent equivalent per tonne of crude ore. The following materials were added to a flotation cell containing water and ore to form a flotation mixture.

(1) 6.4 ml (ca. 29 g / t) of a 1.25% by weight aqueous solution of sodium isopropyl xanthate (Z-11) as a lead and zinc collector, (2) 6.25 ml (227 g / t) t) a 10% aqueous solution of zinc sulphate as a zinc settling agent, (3) 2.5 drops (8.2 g / t) isopropylethylthionocarbamate (Z-200) and (4) 10.5 drops (45.4 g / t) n- hexanol as a blowing agent.

The flotation mixture was stirred at 1200 rpm for a few minutes. Air was then passed through the stirred flotation mixture and the lead was floated. The foam was collected for analysis.

The flotation process was interrupted to prepare for the second flotation. Then 6.6 ml (30 g / t) of a 1.25% by weight aqueous solution of copper sulfate was added to the cell. Copper sulfate was added to activate and foam the zinc. Similarly, an additional 21 drops (90.8 α / t) of n-hexanol foam were added to the cell. After the mixture was conditioned for 5 minutes with stirring, a second flotation was continued by adding air to the cell for 5 minutes to foam and collect the zinc. The combined floats were then analyzed for individual metals or corresponding sulfides. The results obtained are summarized in Table I below.

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Example II

This example is another check flotation test. BME was not used in this example. In this example, various mercaptans were tested to determine whether they would be able to effectively press or foam lead or zinc in the presence of other minerals such as iron or copper. The experimental procedure of Example I was repeated except that various reagent substitutions were made.

In the first experiment, the n-hexanol foamer used in the second flotation was replaced with 9 drops (39 g / t) of a mixture containing 80% by weight of tert-dodecyl mercaptan and 20% by weight of polypropylene glycol as a foaming agent. The results of this first experiment are presented in time A 1, Δ 2, and A3 in Table II below.

In the second experiment, all the reagents used in Example I were again used, in addition to 9 drops (39 g / t) of a mixture containing 80% by weight of n-dodecyl mercaptan and 20% by weight of polypropylene glycol. This second experiment is shown in Table II below at times B 4, B 5, and B 6.

The results are summarized in Table II. The results show that mercaptans are not useful under these flotation conditions as lead and zinc settling agents. The percentage of lead and zinc recovery increased rather than decreased when mercaptan was used.

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Example III

In this example, BME was used as a printing agent for lead and zinc. The experimental procedure of Example I was repeated in two separate experiments using BME.

In the first experiment using BME, 19 drops (68.1 g / t) of 98% w / w pure BME were added during grinding with water and before the first floating instead of zinc sulphate depressant. Zinc sulphate was not used in the first flotation. The first test runs at times AI, A 2 and A 3 are shown in Table III below.

In the second experiment using BME, the zinc sulfate solution was used in the first flotation. 19 drops (68.1 g / t) of 98% by weight pure BME were added to the flotation mixture after the first flotation before the second flotation.

The second test runs are shown in Table III below as times B 4, B 5 and B 6.

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Summary - Table IV

The results presented here are summarized in Table IV. The results show that BME presses the flotation of lead and zinc down while allowing copper and iron to float.

The results also show that it is advantageous and better to add BME long before flotation to achieve significant lead depression. For example, the addition of BME to the milling step can significantly reduce lead foaming. However, it is better to add BME after grinding to maximize lead and zinc depression. It is most advantageous to increase the BME before the second flotation for further depression of zinc and to obtain higher copper and iron recoveries and lower lead and zinc recoveries.

Table IV Summary of results

Tarkistus__Keksintö_

Example: _I_ IIA IIB IIIA IIIB

A. Additives g / t ore 1. Grinding (a) beta-mercaptoethanol - - - 68,1 2. First flotation (a) Z-11, Na-isopropyl xanthate 29,0 29,0 29,0 29,0 29, 0 b) Z-200 isopropylethylthionocarbamate 8.2 8.2 8.2 8.2 0.2 c) ZnSO 4 227.0 227.0 227.0-227.0 d) n-hexanol 65.4 45, 4 45.4 45.4 45.4 3. Second flotation a) CuSO 4 30 30 30 30 30 b) n-hexanol 90.3 90.8 90.8 90.8 90.8 c) tert-C - 39.0 - d) n-C12SH / foamer - - 29.0 - e) beta-mercaptoethanol - - - - 63.1 B. Recovery%

Pb 72.9 80.6 84.6 58.0 77.3

Zn 87.3 91.8 93.4 53.3 33.2

Cu 53.1 61.9 67.5 48.3 52.4

Fe 13.3 15.3 17.9 12.2 13.2 19 72900

Example IV

This example is presented for the purpose of illustrating the apparent effectiveness of BME as a depressant in ore flotation. Molybdenum-copper ore (2035 g) and water (850 ml) were added to a ball mill (70% dry matter) together with various flotation agents such as 25.4 g / t wood distillation turpentine, 10.9 g / t sulfonated coconut oil (Synthes, Colgate Palmolive), -33.5 g / t fuel oil and 45.4 g / t BME. After stirring for 10.5 minutes, the mixture was transferred to a 5-liter Denver D-12 flotation cell, diluted to a dry matter content of 42%, and the pH was adjusted to 7.5 with sulfuric acid. The slurry was conditioned for 2 minutes and foamed for 1 minute at 1400 rpm. The procedure was repeated with 136.2 cj / t BME and without BME for comparison. The results of these runs are listed in Table I, from which it can be seen that BME is not an effective depressant for iron, a mineral to be depressed.

Table V

BME effect as a printing agent 25.4 g / t wood distillation turpentine 10.9 g / t sulphonated coconut oil 83.5 g / t fuel oil 2035 g ore

Driving Printer- Recovery% in concentrate No. substance___ Mo Cu Fe 1 Not at all 86.4 65.1 6.18 2 Not at all 83.6 65.1 6.39

Mean = 85.0 65.1 6.28 3 BME, 45.4 cr / t 86.0 63.2 7.13 4 BME, 45.4 g / t 85.8 67.3 7.13

Mean = 85.9 65.3 7.13 5 BME, 136.2 g / t 84.1 49.2 6.90 6 BME, 136, 2 84.1 60.7 6.39 7 BME, 136.2 »83.2 49.7 5.98

Average = 83.8 53.2 6.42 a) beta-mercaptoethanol 20 72 9 0 0

Example V

This example illustrates a series of runs of the invention that illustrate how the use of BME reduces the amount of a known printing agent, such as sodium hydrosulfide (NaSH), required in the foaming process. Molybdenite germ cell concentrate slurry obtained from Phelps Dodge Morenci, Arizona, was used in this example. 2000 ml of concentrate slurry and about 8 L of water (15% dry matter) were placed in a 10 liter Denver flotation cell. Kerosene, NaSH and BME were added in the amounts shown in Table I. The mixture was conditioned at pH 10.5 for 5 minutes at 1200 rpm. The mixture was then foamed for 4 minutes. The concentrate was transferred to a 2.5 liter Denver cell with 1500 ml of water and the indicated reagents and conditioned for 2 minutes at 900 rpm and foamed for 4 minutes. The final concentrate from each of the three flotations was analyzed. The results obtained in this example are listed in Table VI, which shows that the use of BME can greatly reduce the required amount of NaSH while still maintaining the percentage recovery of molybdenum, copper and iron. This reduction in the amount of NaSH required is readily apparent when comparing the results of run 3 with the results of run 5 and comparing the results of run 2 with the results of runs 4 and 6.

2i 72900

Table VI

Effect of BME on the suppression of Fe and Cu with NaSH in Mo ore flotation_ 2000 ml Mo germ cell concentrate 104 g / t kerosene (3 flotations)

Driving Total reagent, kg / t% recovery in concentrate n '° NaSH BME Mo Cu Fe 1 H, 8 - 62.0 0.12 0.08 52.6 0.06 0.05

Mean = 57.3 0.09 0.065 2 5.9 - 57.7 0.05 0.05 63.5 0.073 0.075

Mean = 60.6 0.06 0.06 3 3.0 43.5 0.96 0.40 34.8 0.34 0.18

Mean = 39.2 0.65 0.29 4 5.9 0.4 5a 64.3 0.07 0.06 5 3.0 0.45a 57.2 0.15 0.10 6 5.9 0, 27a 56.0 0.05 0.047 a) was added only to the first float.

Example VI

This example illustrates the run of the invention, which again illustrates on a commercial factory scale how effective BME is in reducing the amount of NaSH required for depression. Approximately 36.3 kg of NaSH / t molybdenum-copper ore concentrate was fed to the germ cells at a commercial molybdenum plant in Anaconda, Butte, Montana as a depressant. NaSH was monitored by milli-volt shift at the end of the germ cells. Normally, a reading of -550 millivolts is typical of good depression of iron and copper sulfides in these germ cells. If the millivolt reading becomes more positive (eg -510 mV)

More NaSH is added to the germ cells. If the millivolt reading becomes more negative (e.g. -590 mV), the opposite is done. A major problem with the use of NaSH in the flotation of this ore 22,72900 is the ability of NaSH to oxidize rapidly to products with little depressant capacity for copper and iron sulfides.

Approximately 1.3 hours after the first addition of NaSH, 90.3 g / t BME was added to the germ cells, followed by conventional 35.3 kg / t NaSH. About 15-20 minutes after the addition of BME, the NaSH monitor recorded -630 mV, indicating that more NaSH was present than required. One hour later, 277 g / t BME was added, followed by half the usual amount of 18.15 ka / t NaSH. The NaSH monitor recorded -560 mV, an almost normal reading, indicating that there was sufficient NaSH in the germ cells to achieve the desired results. The process was continued for another 4 hours, during which time the monitor continuously recorded a reading of -560 mV. The results listed in Table III show that the addition of a small amount of BME (90.9-277 g / t) results in a 50% reduction in the required amount of NaSH without loss of molybdenum quality or recovery percentage.

Table VII

Effect of BME on NaSH depression in the Mo-Cu ore flotation cell experiment_

Time kg / t Germ cell enrichment - Germ cell concentrate 3 mV

NaSH BME stern> _ Cu% Mo% _ _ _ Cu% Mo% _ _ _ 8:00 3S, 3 - 28.6 0.068 17.0 25.3 -550 9:20 36.3 0.09 29.4 0.066 18.1 24.4 -630 10:20 18.15 0.27 29.3 0.048 15.7 27.4 -560 12:50 18.15 0.27 29.0 0.035 19.6 21.5 - 560 15:00 13.15 0.27 29.0 0.060 12.4 32.0 -560 16:00 13.15 o, 27 29.5 0.157 10.4 38.8 -560 a) Calculated as pure metal from the dry weight of the remainder being for the most part S.

Example VII

This example illustrates a run of the invention that illustrates the ability of BME to act as an oxygen scavenger. The chalcosite ore (CU2S) from Phelps Dodge Mines was floated in the same way as in Example I in Example 7 7 7 2 9 0 0, with the exception that different flotation reagents were used. Chalcosite was chosen as a copper mineral due to its ability to oxidize easily. In one run, 2.1 l / t isopropylethylthionocarbamate (Minerec 1661) was added as a collecting agent to a ball mill. In the second run 36, Sg / t BME was added to the ball mill just before the collector. These results are shown in Table VIII and show that the use of BME increases the percentage of copper recovery when used with a normal bulking agent. Thus, BME acts as an oxygen scavenger, protecting the chalcosite mineral from oxidation so that it can be recovered more efficiently. BME presumably acts as an oxygen scavenger because it was already found in Example I that BME does not act as a bulking agent or depressant.

Table VIII

Effect of BME as oxygen scavenger in powder (Calccosite ore)

Run Reagent g / ta ^ Cu recovery% n _ _ _ 1 Thionocarbamate ^ 20.1 67.80 2 a Thionocarbamate 28.1 75.9 BME 36.8 b Thionocarbamate 23.1 74.3 BME 36 .8 _

Average = 75.10 a) Added to a ball mill.

b) Isopropylethylthionocarbamate (Minerec 1661).

Claims (9)

A flotation process in which a sludge consisting of a flotation liquid and an ore comprising an iron or copper sulphide and a lead or zinc sulphide is mixed with a gas stream to produce a mineral-containing foam and in which said copper or iron sulphide is recovered from the foam. , characterized in that the sludge is supplied to the depressant beta-mercaptoethanol in such quantities that it contributes in turn to the reduction of the lead or zinc sulphide. Process according to Claim 1, characterized in that a first flotation and at least one further flotation are used and that the beta-mercaptoethanol is added after the first flotation. 3. A process according to claim 1, characterized in that the ore is ground and the ground ore is mixed with the flotation liquid to produce said sludge and that beta-mercaptoethanol is added to the ore before it is ground or during the process of grinding.