Low alkalinity depressant for pyrite in secondary copper sulfide ores and method

Abstract

The application discloses a low-alkalinity inhibitor for pyrite in secondary copper-sulfur ore and a method. The method comprises the following steps: adding trisodium trithiocyanate in the process of ore grinding; and adding a second inhibitor to adjust the pH value of the ore slurry to 9.5-10.5 in the process of flotation. The second inhibitor is calcium oxide and an organic copolymer, the organic copolymer is an acrylamide-acrylic acid-maleic anhydride copolymer, and the molecular weight of the organic copolymer is 5000-10000. The method can reduce the activation of copper ions on pyrite, realize low-alkalinity inhibition of pyrite, and avoid problems such as high pH value of mineral processing waste water, easy pipe blockage, and low recovery rate of precious metals.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, in particular to a low-alkalinity inhibitor for pyrite in secondary copper-containing copper-sulfur ore and a method. BACKGROUND

[0002] Pyrite has a chemical formula of FeS2 and is the most widely distributed sulfide mineral in the earth's crust, often associated with copper, nickel, lead, zinc and other minerals. Therefore, in the flotation process of non-ferrous metal sulfide ore, the inhibition or separation of pyrite is very common and important. The most common method for inhibiting pyrite is the lime method, which has the advantages of good inhibition effect and relatively low cost, but its strong alkalinity can cause problems such as high pH value of mineral processing wastewater, pipe blockage, and low recovery rate of valuable metals. The traditional method for inhibiting sulfur is the cyanide method, but its use is greatly limited due to the toxicity of cyanide.

[0003] In order to overcome the above problems, many inhibition methods have been developed by those skilled in the art to replace or optimize lime, mainly including: oxidation-reduction agent methods represented by sodium sulfite, sodium metabisulfite, sulfur dioxide, potassium permanganate, and hypochlorite; various organic inhibitor methods represented by sodium humate, dextrin, tannic acid, and triethanolamine; and combined inhibitor methods in which calcium oxide, inorganic substances, or organic substances are combined with each other. Among the above-mentioned methods for inhibiting pyrite, reduced inorganic salts such as sodium sulfite, sodium metabisulfite, and sodium thiosulfate have been widely used; for example, Chinese application CN107694760A discloses a combined reagent for inhibiting pyrite, which uses a combined reagent of sodium sulfite and calcium oxide in a ratio of 1:1 as an inhibitor for pyrite, can achieve the inhibition of pyrite, and can be applied to copper-sulfur preferential flotation and copper-sulfur concentrate separation. Chinese application CN103691569A discloses a beneficiation method for high-sulfur gold-containing copper ore, which uses sodium metabisulfite and calcium oxide as a slurry conditioning agent and a pyrite inhibitor to inhibit pyrite and improve the flotation recovery rate of copper and gold. Chinese application CN109261368A discloses an inhibitor for pyrrhotite and a method of use, which uses sodium metabisulfite, sodium humate, and calcium oxide as a pyrrhotite inhibitor to strengthen the inhibition of pyrrhotite through the synergistic effect between the reagents. In the prior art, reduced inorganic salts are mixed with lime, sodium humate, and the like to achieve a certain synergistic effect. Current research shows that reduced inorganic salts mainly inhibit pyrite by reducing the slurry potential and desorbing the xanthate on the mineral surface.

[0004] However, the inventors of this application discovered that when the ore contains secondary copper, the copper ions in the slurry activate pyrite, making pyrite inhibition significantly more difficult. In this case, a higher alkalinity is required for effective inhibition, which, in turn, can lead to the aforementioned problems. Therefore, it is necessary to develop a low-alkalinity sulfur inhibitor for this type of ore that can achieve a better pyrite inhibition effect while avoiding the aforementioned problems. Summary of the Invention

[0005] According to one embodiment of the present invention, an object is to provide a method and a low-alkalinity inhibitor for suppressing the low alkalinity of pyrite in a copper-sulfide ore containing secondary copper, thereby achieving low-alkalinity suppression of pyrite in a copper-sulfide ore containing secondary copper. The above object can be achieved by implementing the following technical solutions:

[0006] A method for suppressing the low alkalinity of pyrite in a secondary copper-containing copper-sulfide ore comprises: adding trisodium thiocyanate in an amount of 25 to 100 g / t during the grinding process; and adding a second inhibitor in a flotation stage to adjust the pH value of the ore pulp to 9.5 to 10.5; wherein the second inhibitor comprises calcium oxide and an organic copolymer, the organic copolymer being an acrylamide-acrylic acid-maleic anhydride copolymer, the second inhibitor being added in an amount of 50 to 200 g / t, and the molecular weight of the organic copolymer being 5,000 to 10,000.

[0007] Optionally, after grinding, a slurry is obtained in which the ore fineness is -0.074 mm, accounting for 65% to 75%.

[0008] Optionally, during the flotation stage, the process further includes: adding a copper collector and a foaming agent; wherein the copper collector is one or more of ethionamide, butyl ammonium black medicine, and thiocyanate; and the foaming agent is one of No. 2 oil or methyl isobutyl carbinol.

[0009] Optionally, the copper collector is used in an amount of 40 to 80 g / t.

[0010] Optionally, in the flotation stage, after obtaining the flotation concentrate and flotation tailings through roughing, the method further comprises: adding the second depressant to perform 2-3 times of beneficiation on the flotation concentrate; and / or, performing 2-3 times of scavenging on the flotation tailings.

[0011] Optionally, after flotation, a copper concentrate with a copper grade of not less than 25% and a copper recovery rate of not less than 89% is obtained, and the gold recovery rate in the copper concentrate is not less than 45%.

[0012] Optionally, in the secondary copper-containing copper-sulfide ore, the proportion of secondary copper in the total copper is higher than 20%.

[0013] A low-alkalinity inhibitor for pyrite in a copper-sulfide ore containing secondary copper, comprising trisodium thiocyanate and a second inhibitor; wherein the trisodium thiocyanate is added during the grinding process in an amount of 25 to 100 g / t; the second inhibitor comprises calcium oxide and an organic copolymer, and is added during the flotation stage; wherein the calcium oxide is added in an amount sufficient to adjust the pH value of the ore pulp to 9.5 to 10.5; and the organic copolymer is an acrylamide-acrylic acid-maleic anhydride copolymer, added in an amount of 50 to 200 g / t and having a molecular weight of 5,000 to 10,000.

[0014] Optionally, in the secondary copper-containing copper-sulfide ore, the proportion of secondary copper in the total copper is higher than 20%.

[0015] According to an embodiment of the present invention, by first adding trisodium thiocyanate in the grinding stage, the activation of pyrite by copper ions is reduced, thus simplifying the copper-sulfur separation difficulty of secondary copper-copper-sulfur ores. Calcium oxide and an organic copolymer are then added in the flotation stage. The synergistic effect of these three factors achieves low-alkalinity suppression of pyrite, thereby avoiding problems such as high pH in the beneficiation wastewater, easy pipe clogging, and low precious metal recovery. This method can be applied to the preferential flotation practice of secondary copper-copper-sulfur ores. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a schematic flow chart of a method for suppressing pyrite with low basicity in a copper-sulfur ore containing secondary copper according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] The low-alkalinity inhibition method for pyrite in secondary copper-containing copper-sulfide ore provided in the present application is to first add trisodium thiocyanate in the grinding section to reduce the activation of pyrite by copper ions, and then add calcium oxide and an organic copolymer as a second inhibitor in the flotation stage. The three act synergistically to achieve low-alkalinity inhibition of pyrite, avoiding problems such as high pH value of mineral processing wastewater, easy blockage of pipelines, and low recovery rate of precious metals.

[0019] Figure 1 The following schematically illustrates a method for suppressing the low basicity of pyrite in a copper-sulfur ore containing secondary copper in an embodiment of the present application. Figure 1As shown, the low basicity suppression method for pyrite in copper-sulfur ore containing secondary copper ore may include the following steps:

[0020] Step S10, grinding to prepare slurry. During the grinding process, trisodium thiocyanate is first added to the raw ore and the added amount is controlled; after grinding, a slurry with an ore fineness of -0.074 mm accounting for 65% to 75% is obtained.

[0021] During the grinding process, the addition of trisodium thiocyanate can effectively remove free copper ions in the pulp. It can chelate with copper metal ions to form organic sulfide products that are extremely insoluble in water and have good chemical stability, thereby reducing the activation of pyrite by copper ions and reducing the difficulty of copper and sulfur separation in secondary copper-containing copper-sulfur ores. Trisodium thiocyanate exists in many forms in the pulp, and the possible reactions with copper ions are as follows:

[0022] 2(C3N3S3) 3- +3Cu 2+ =Cu3(C3N3S3)2

[0023] (HC3N3S3) 2- +Cu 2+ =CuHC3N3S3

[0024] 2(H2C3N3S3) - +Cu 2+ =Cu(H2C3N3S3)2

[0025] Among them, the addition amount of trisodium thiocyanate is controlled at 25 to 100 g / t of ore, for example, 50 g / t, 75 g / t, 100 g / t, etc. Within this range, a copper concentrate with a high recovery rate can be obtained, the copper concentrate grade is improved, and a high precious metal recovery rate is achieved. The inventors also found that when the addition amount exceeds 100 g / t, it will have a negative impact on the copper concentrate recovery rate.

[0026] By adding trisodium thiocyanate to the raw ore for grinding and controlling the fineness and proportion of the ore in the slurry, the useful minerals and gangue minerals in the copper-sulfur ore can be better separated into monomers, which is more conducive to the subsequent flotation.

[0027] The raw ore is a copper-sulfide ore containing secondary copper. For example, when the proportion of secondary copper in the total copper is greater than 20%, the present invention can achieve low-alkalinity inhibition with a pH value of no more than 10.5 while ensuring the inhibition effect. Existing technologies require high alkalinity, generally around a pH of 12, to achieve a similar copper grade and recovery rate. Such strong alkalinity results in high pH values ​​in the mineral processing wastewater, easy pipe clogging, and low precious metal recovery rates.

[0028] Step S20, adding chemicals to the slurry and stirring. Add a sulfur inhibitor, i.e., a second inhibitor, to the slurry to which trisodium thiocyanate has been added, stirring for 3 to 5 minutes, and then add a copper collector and a foaming agent, stirring for 2 to 3 minutes.

[0029] The second inhibitor is calcium oxide and an organic copolymer; the pH value of the pulp is adjusted to 9.5-10.5 by adding calcium oxide; the organic copolymer is specifically an acrylamide-acrylic acid-maleic anhydride copolymer, and the addition amount is 50-200 g / t, for example 75 g / t, 100 g / t, 150 g / t, 200 g / t, etc., within this range, the grade of copper concentrate can be guaranteed while still having an inhibitory effect on pyrite, and the molecular weight of the organic copolymer is 5000-10000. In the present application, the organic copolymer can react with the iron ions on the surface of pyrite and the calcium ions adsorbed on the surface of pyrite, increase the hydrophilicity of the pyrite surface, strengthen the inhibition of calcium oxide on pyrite, and thus achieve the effect of low alkalinity inhibition. The organic copolymer is a multi-polymer synthesized in an aqueous phase using maleic anhydride, acrylic acid and acrylamide as raw materials. The synthesis method can be as follows: maleic anhydride and distilled water are added to a four-necked flask connected to a stirrer, a thermometer, and a condenser, and the temperature is raised to 65°C; acrylic acid, acrylamide, and ammonium persulfate are prepared into a solution and added dropwise to a dropping funnel at 65°C. After the addition is complete, the mixture is reacted at 85°C for 4 hours before being discharged. However, this is not limited to the above. The multi-component copolymer is rich in polar groups such as carboxyl, carbonyl, and amino groups, and has a very strong chelating ability for iron and calcium ions. Pyrite contains iron ions on its surface, and calcium ions are easily adsorbed on it. This makes the organic copolymer easily adsorbed to the pyrite surface. Since the polar groups contained in the copolymer are hydrophilic, they greatly increase the hydrophilicity of the pyrite surface, thereby exerting an inhibitory effect.

[0030] The copper collector is one or more of Z-200 (ethylthiocarbamate), butylammonium black medicine, and Ester 105 (sulfur nitrogen nitrile ester), with a dosage of 40-80 g / t of ore. The foaming agent is one of No. 2 oil or methyl isobutyl carbinol, with a dosage of about 20-40 g / t of ore.

[0031] Step S30, flotation. The slurry after adding chemicals and stirring enters the flotation machine for flotation. The flotation time is 3 to 6 minutes. After copper roughing flotation, flotation rough concentrate and flotation tailings are obtained.

[0032] In addition, to ensure the grade and recovery rate of copper ore, the flotation rough concentrate is subjected to 2-3 rounds of cleaning, and the flotation tailings after roughing are subjected to 2-3 rounds of scavenging. The second depressant is optionally added during cleaning, and a collector and frother are optionally added during scavenging.

[0033] For example, after a rough selection, Figure 1As shown, two more concentrations (Copper Concentration I and Copper Concentration II) and two scavengings (Copper Scavenging I and Copper Scavenging II) are performed to achieve a copper grade of no less than 25% and a copper recovery rate of no less than 89%. In addition, the middlings from Copper Concentration I and Copper Scavenging I are returned to the rougher, the middlings from Copper Concentration II are returned to Copper Concentration I, and the middlings from Copper Scavenging II are returned to Copper Scavenging I.

[0034] In the above embodiment, trisodium thiocyanate is first added to the grinding section and the addition amount is controlled, thereby reducing the activation of pyrite by copper ions. In the flotation stage, calcium oxide and an organic copolymer are added to the slurry to which trisodium thiocyanate has been added as a second inhibitor. The pH is adjusted by calcium oxide, and the three act synergistically. At the same time, by adopting a specific organic copolymer and controlling its addition amount, low alkalinity inhibition of pyrite (pH value not higher than 10.5) is achieved, thereby avoiding problems such as high pH value of mineral processing wastewater, easy blockage of pipelines, and low recovery rate of precious metals. Finally, a copper concentrate with high grade and high recovery rate is obtained, and the gold recovery rate in the copper concentrate is high.

[0035] The following is a further description of the implementation methods and technical effects of this application with reference to specific examples:

[0036] Example 1

[0037] A copper mine contains 1.46% copper, 6.34% sulfur, 0.2g / t Au, and the proportion of secondary copper in the total copper is 25%.

[0038] Grinding: During the grinding process, 100g / t of trisodium thiocyanate was added to obtain a 65% slurry with a fineness of -0.074mm. Flotation: During copper roughing, calcium oxide was added to the ground slurry to adjust the pH to 10. 150g / t of organic copolymer, 60g / t of Z-200, and 30g / t of No. 2 oil were added. During copper concentration I, the slurry pH was 10.5, and 50g / t of organic copolymer was added. During copper scavenging I, 20g / t of Z-200 was added, and during scavenging II, 10g / t of Z-200 was added. This flotation process of one roughing, two finishing, and two scavenging processes yielded a copper concentrate with a copper grade of 26.12% and a copper recovery of 89.26%. The gold recovery in the copper concentrate was 45.88%.

[0039] Example 2

[0040] The difference from Example 1 is that the addition amount of trisodium thiocyanate is 25 g / t ore, and a copper concentrate with a copper grade of 25.48% and a copper recovery rate of 89.27% ​​can be obtained, and the gold recovery rate in the copper concentrate is 46.12%. It can be seen that when the addition amount of trisodium thiocyanate is reduced to 25 g / t, the copper grade obtained is reduced; when the addition amount is controlled at 100 g / t ore, the grade of the copper concentrate obtained is higher and there is no significant negative impact on the copper recovery rate; when the addition amount of trisodium thiocyanate is controlled within the range of 25-100 g / t, the copper concentrate grade is ensured to be higher without negatively affecting the recovery rate, and the gold recovery rate is also higher.

[0041] Example 3

[0042] Unlike Example 1, the addition of the organic copolymer in the copper roughing stage was 50 g / t, resulting in a copper concentrate with a copper grade of 25.45%, a copper recovery of 89.32%, and a gold recovery of 46.27%. This indicates that reducing the amount of organic copolymer slightly lowers the copper concentrate grade, but the above-mentioned addition still has a certain inhibitory effect on pyrite production. Therefore, controlling the addition amount to 50-200 g / t ensures a higher copper concentrate grade and a better inhibitory effect on pyrite production.

[0043] Comparative Example 1

[0044] The difference from Example 1 is that trisodium thiocyanate was not added during the grinding process. A copper concentrate with a copper grade of 24.54% and a copper recovery of 89.93% was obtained, and the gold recovery in the copper concentrate was 46.43%. It can be seen that if trisodium thiocyanate is not added during the grinding stage, the copper grade will decrease. Due to the activation of free copper ions, the sulfur mineral inhibition effect becomes poor, resulting in a lower copper concentrate grade.

[0045] Comparative Example 2

[0046] The difference from Example 1 is that without the addition of the organic copolymer, a copper concentrate with a copper grade of 23.78% and a copper recovery of 90.22% was obtained, and the gold recovery in the copper concentrate was 46.64%. This indicates that without the addition of the organic copolymer during the flotation stage, effective pyrite suppression is difficult to achieve under low alkalinity conditions, resulting in increased pyrite flotation and a decrease in copper grade.

[0047] Comparative Example 3

[0048] The difference from example 1 is that: using traditional high alkaline process, the pH value of roughing slurry is controlled to be 10.5, the pH value of first cleaning slurry is controlled to be 11, the pH value of second cleaning slurry is controlled to be 12, no trimeric thiocyanic acid trisodium and organic copolymer are added, the copper concentrate with copper grade of 26.22% and copper recovery of 89.31% can be obtained, and the gold recovery in the copper concentrate is reduced to 42.21%. It can be seen that: if trimeric thiocyanic acid trisodium and organic copolymer are not added, using traditional high alkaline process to inhibit secondary copper-sulfur ore, the pH value of slurry needs to be adjusted to about 12 to obtain copper concentrate with close grade and recovery, which further leads to high pH value of mineral processing wastewater, and the pipeline is easy to be blocked, and high alkalinity has certain inhibition effect on noble metal, and the recovery of noble metal in the obtained copper concentrate is low.

[0049] The description of the application is given for the purpose of illustration and description, and is not intended to be exhaustive or to limit the application to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Embodiments were chosen and described in order to best explain the principles of the application and its practical application, and to enable others skilled in the art to understand the application for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A method for suppressing the low basicity of pyrite in a secondary copper-containing copper-sulfide ore, characterized in that: include: During the grinding process, trisodium thiocyanate is added in an amount of 25-100 g / t; During the flotation stage, a second inhibitor is added to adjust the pH value of the pulp to 9.5-10.5; wherein, the second inhibitor is calcium oxide and an organic copolymer, the organic copolymer is an acrylamide-acrylic acid-maleic anhydride copolymer, the addition amount is 50-200 g / t, and the molecular weight of the organic copolymer is 5000-10000; during the flotation stage, a copper collector and a foaming agent are also added, the copper collector is one or more of ethiocarbamate, butyl ammonium black medicine, and thiocyanate; the foaming agent is one of No. 2 oil or methyl isobutyl carbinol; the amount of the copper collector is 40-80 g / t.

2. The low basicity suppression method for pyrite in secondary copper-containing copper-sulfide ore according to claim 1, characterized in that: After grinding, the ore pulp is obtained, with the ore fineness of -0.074mm accounting for 65% to 75%.

3. The low basicity suppression method for pyrite in secondary copper-containing copper-sulfur ore according to claim 1, characterized in that: The flotation stage, after obtaining flotation concentrate and flotation tailings through roughing, also includes: adding the second depressant to perform 2-3 times of beneficiation on the flotation coarse concentrate; The flotation tailings are scavenged 2 to 3 times.

4. The low basicity suppression method for pyrite in secondary copper-containing copper-sulfur ore according to claim 3, characterized in that: After flotation, a copper concentrate with a copper grade of not less than 25% and a copper recovery rate of not less than 89% is obtained, and the gold recovery rate in the copper concentrate is not less than 45%.

5. The low basicity suppression method for pyrite in secondary copper-containing copper-sulfide ore according to claim 1, characterized in that: In the secondary copper-containing copper-sulfide ore, the proportion of secondary copper in the total copper is higher than 20%.

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