JP6151665B2 - Separation method of copper and molybdenum - Google Patents

Description

  The present invention relates to a technique for separating and recovering copper and molybdenum from a mineral containing copper and molybdenum using flotation.

  Copper ore produced from porphyry type copper deposits, one of typical copper deposits, may be accompanied by molybdenum minerals such as chalcocite and copper minerals such as chalcopyrite. Molybdenum is a valuable metal as a component of lubricating oils and corrosion-resistant alloys. is there. Therefore, in the processing of the produced copper ore, it is necessary to separate and recover copper and molybdenum.

  When molybdenum is effectively used as a resource, it is desirable to recover molybdenum with high quality, and it is preferable that copper and molybdenum can be separated efficiently. Various methods have been proposed for the separation of copper and molybdenum. In the above-mentioned copper deposits, however, it is common to use flotation because copper ore exists mainly in the form of sulfide minerals.

  As a method of flotation of copper ore, for example, in Patent Document 1, molybdenum flotation is further performed on copper concentrate obtained by copper roughing and copper selection, and the content of molybdenite in the flotation is about 1 mass. The method of refining molybdenum minerals by flotation beneficiation and recovering molybdenum minerals as floats after ozone oxidation of the floats at the time of reaching% is shown.

JP-A-5-195106

  Although a good actual yield can be obtained by the method of Patent Document 1 described above, in order to generate ozone for use in ozone oxidation, a large-scale device is required and equipment costs are required, and a large amount of power is consumed. In some mines with insufficient power infrastructure, there were cases where it was not profitable.

  Therefore, as a method of separating copper and molybdenum by flotation without performing ozone oxidation, a method of adding a sulfiding agent such as NaHS during flotation to suppress chalcopyrite containing copper and separating it from molybdenum. It is possible to adopt. This method makes use of the fact that copper sulfide minerals such as molybdenite and chalcopyrite are relatively easy to float in flotation, and by adding NaHS or the like, the copper mineral is suppressed and flotation separated. Is.

  However, although chalcopyrite has a floating property of about 80%, it has a problem that it is easily affected by the separability and setting of flotation conditions, and stable operation is difficult. In addition, copper sulfide minerals are partially oxidized by sulfur due to weathering, natural oxidation, and the like, and if this is mined and slurried to be processed by flotation, the slurry may become weakly acidic. Under such acidic conditions, NaHS may generate toxic hydrogen sulfide, so it is not preferable from the viewpoint of safety to use a large amount of NaHS. The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a method for safely separating and recovering copper and molybdenum from a sulfide mineral containing copper and molybdenum at a low cost. .

In order to achieve the above object, the method for separating copper and molybdenum provided by the present invention comprises performing a pretreatment of energizing between a counter electrode side with a sulfide mineral containing copper and molybdenum as a working electrode side, The sulfide mineral is subjected to flotation , and the energization is performed by applying a predetermined voltage between a working electrode and a counter electrode immersed in the slurry containing the sulfide mineral, and the working electrode is It installs in the position which contacts the sulfide mineral in the said slurry, The said counter electrode is installed in the position which does not contact the sulfide mineral in the said slurry .

  According to the present invention, chalcopyrite can be selectively oxidized or reduced without using a sulfiding agent or ozone as a pretreatment for flotation, so that copper or molybdenum can be selectively separated in the subsequent flotation. Therefore, copper and molybdenum can be separated and recovered from a mineral containing copper and molybdenum safely and efficiently at low cost.

  In the present invention, before subjecting a mineral containing chalcopyrite and molybdenite to flotation, the mineral is introduced into an electrolytic bath as a pretreatment and energized, whereby the surface of the mineral is oxidized or reduced. It is modified to be hydrophobic. A method of causing oxidation or reduction using a reagent or the like is also conceivable for surface modification of such minerals, but the present inventors use the mineral itself as a working electrode or immerse the working electrode in a slurry in which the mineral is dispersed. Then, it was found that the same effect can be obtained by energizing between the entire slurry as the working electrode side and a counter electrode installed at a position not contacting the mineral in the slurry. It has also been found that the reforming state can be controlled by the energization conditions and the pH conditions of the electrolytic bath, thereby obtaining a desired separation behavior during flotation.

  Since the liquid to be treated that is treated in the electrolytic bath needs to have appropriate electrical conductivity, it is necessary to include an appropriate supporting electrolyte. Any electrolyte other than the one that reacts with the electrolyte itself may be used, but a diluted potassium chloride aqueous solution having a concentration of about 0.001 M can be applied to the liquid used for preparing the slurry. The working electrode may be the above chalcopyrite or hydropyrite ore itself, but after the above mineral is pulverized to a particle size that can be used for flotation, it is mixed with the above potassium chloride solution to form a slurry. A working electrode made of an insoluble material such as platinum may be immersed in the slurry. In this case, it is preferable to energize the slurry while stirring, so that the mineral in the slurry can be brought into good contact with the working electrode.

  On the other hand, the counter electrode is preferably made of an insoluble material such as platinum or carbon. As described above, when a mineral is dispersed in an electrolytic bath as a slurry and a voltage is applied between, for example, a platinum plate on the counter electrode side as a working electrode side, the mineral contacts the surface of the platinum plate of the counter electrode. Since the effect of modification is hardly obtained even when a voltage is applied, the counter electrode is acted on by covering the surface of the counter electrode with a filter cloth having an opening that does not allow the passage of finely pulverized minerals, for example. It is preferable to separate from the pole side state.

  When energizing, it is preferable to apply a voltage between the counter electrode and the working electrode so that the working electrode is 1.2 to 1.4 V with the counter electrode as a reference of 0V. Specifically, a voltage in the range of 1.2 to 1.4 V is applied with the negative side of the power supply connected to the counter electrode and the positive side connected to the working electrode. In this case, not only in the neutral region where the pH of the electrolytic bath is about 5 to 8, but also in the weak acidic region of pH 3 to 5 or the weakly basic region of pH 8 to 10 Can be improved.

  Since the working electrode side is under strong oxidation conditions at a voltage within the above range, the surface of chalcopyrite is oxidized regardless of whether the pH of the electrolytic bath is neutral to weakly acidic or neutral to weakly basic. Then, copper or iron of chalcopyrite is dissolved in the electrolytic bath in the form of ions, and sulfur is considered to remain as elemental sulfur. As a result, since sulfur occupies most of the chalcopyrite surface, it exhibits hydrophobicity as a whole, and it is considered that the floatability of chalcopyrite increases in the subsequent flotation. If the applied voltage is less than 1.2 V, it is difficult to stably obtain the energization effect. On the other hand, if the voltage exceeds 1.4 V, the decomposition of water into oxygen becomes remarkable, and it is not desirable because it costs energy.

  Alternatively, a voltage may be applied between the counter electrode and the working electrode so that the working electrode is −0.8 to −1.0 V with the counter electrode as a reference of 0V. Specifically, a voltage in the range of −0.8 to −1.0 V is applied with the positive side of the power supply connected to the counter electrode and the negative side connected to the working electrode. In this case, the working electrode side is under reducing conditions, and chalcopyrite is reduced to produce chalcocite and copper indigo, which are considered to exhibit hydrophobicity and increase floatability. If the applied voltage is less than −0.8 V, it is difficult to stably obtain the effect of energization. On the other hand, when the above voltage exceeds -1.0 V, the decomposition of water into hydrogen becomes remarkable, and it is not desirable because it costs energy.

  In addition, when the oxidation conditions on the working electrode side are not so strong or in a reduced state, when the pH of the electrolytic bath is weakly basic, iron hydroxide, copper hydroxide, and the like are deposited on the surface to exhibit hydrophilicity, Suspension may be suppressed. In this case, it is preferable to energize the electrolytic bath under weakly acidic conditions in which no hydroxide is formed, specifically, at a pH of 3 to 5.

  After the above energization, it is preferable to wash the energized sulfide mineral using a cleaning solution such as water before being subjected to flotation. Thereby, the bad influence to the flotation by the solution of the electrolytic bath used at the time of electricity supply can be suppressed. The method of flotation is not particularly limited and can be performed by a general method.

Example 1A
A sample of sulfide mineral containing chalcopyrite and molybdenite was pulverized to a size of about 45 to 75 μm using a ball mill. When the pulverized sulfide mineral was sampled and observed with an optical microscope, chalcopyrite and molybdenite were present in a ratio of approximately 1: 1. Next, 150 ml of a solution adjusted to pH 4 by adding HCl to a 0.001 M potassium chloride solution was placed in a 200 ml beaker. 0.5 g of the pulverized sulfide mineral was put into this solution and stirred at 120 revolutions per minute using a stirrer and a rotor to maintain a suspended state.

  As the electrode on the working electrode side, a gutter formed using a mesh having a mesh opening of 0.5 mm made of a platinum wire having an outer diameter of 0.5 mm was used. On the other hand, a platinum plate measuring 5 mm in length and 20 mm in width was used for the electrode on the counter electrode side. The platinum plate was covered with a filter cloth having an opening of 30 μm in a bag shape, and a potassium chloride solution having the same concentration and pH as above was placed inside the bag. These working electrode and counter electrode were immersed in the beaker while being separated from each other. At that time, care was taken so that the pulverized sulfide mineral particles would not enter the bag on the opposite electrode side. And the electric wire was directly connected to the one end part of the collar of a working electrode, and the electric wire was connected to the upper end of the platinum plate of a counter electrode. Each of these connection locations was sealed with a resin so that the slurry made of the potassium chloride solution was not in contact.

  Both the electric wires described above were connected to a power source, and the energization was performed so that a positive voltage of 1.2 V was applied to the working electrode between the working electrode and the counter electrode with 0 V as the reference electrode, and the energization was continued for 800 seconds. This energization process was performed at room temperature. After a lapse of 800 seconds, the slurry in the beaker was extracted and subjected to solid-liquid separation using filter paper and Nutsche, and the resulting solid content was washed with pure water. Next, the water-washed solid was introduced into a column flotation device, and was subjected to flotation by bubbling air from the bottom to separate it into molybdenum concentrate and copper concentrate, and the ratio of the chalcopyrite floating was measured. .

  As a result, the floatability of chalcopyrite was about 90%, and extremely high floatability was obtained. Floatability is defined as the ratio of chalcopyrite recovered as flotation out of chalcopyrite introduced into the flotation equipment. On the other hand, the floating property of molybdenite was not particularly changed as compared with the untreated one. Molybdenite is less conductive than chalcopyrite, so it seems that there was little influence of electricity. When observed with a laser microscope, no change was observed on the surface of molybdenite, but the surface of chalcopyrite had turned purple, confirming that chalcopyrite was selectively oxidized.

(Example 1B)
The slurry obtained by preparing the same mineral sample as in Example 1A in the same manner was energized using the same apparatus, but the working electrode and the working electrode were set to 1.2 V with the working electrode as the 0 V reference. Instead, a positive voltage of 1.4V was applied. Thereafter, it was washed with water in the same manner as in Example 1A and subjected to flotation.

  As a result, the floatability of chalcopyrite was about 90%, and high floatability was obtained as in Example 1A. On the other hand, the floating property of molybdenite was not particularly changed as in Example 1A. Further, when observed with a laser microscope, no change was observed on the surface of molybdenite, but the surface of chalcopyrite was turned purple, and it was confirmed that chalcopyrite was selectively oxidized.

(Example 2A)
The slurry obtained by preparing the same mineral sample as in Example 1A in the same manner was energized using the same apparatus. However, the counter electrode was set to a positive voltage at the working electrode between the working electrode and the counter electrode as a 0 V reference. Instead, a negative voltage of -0.8V was applied. Thereafter, it was washed with water in the same manner as in Example 1A and subjected to flotation.

  As a result, the floatability of chalcopyrite was about 90%, and high floatability was obtained as in Example 1A. On the other hand, the floating property of molybdenite was not particularly changed as in Example 1A. In addition, when observed with a laser microscope, no change was observed on the surface of molybdenite, but the surface of chalcopyrite had turned a dull color, confirming that chalcopyrite was selectively reduced. It was.

(Example 2B)
The slurry obtained by preparing the same mineral sample as in Example 2A in the same manner was energized using the same apparatus, but the working electrode and the counter electrode were set to −0. Instead of 8V, a negative voltage of -1.0V was applied. Thereafter, it was washed with water in the same manner as in Example 2A and subjected to flotation.

  As a result, the floatability of chalcopyrite was about 90%, and high floatability was obtained as in Example 2A. On the other hand, the floatability of molybdenite was not particularly changed as in Example 2A. In addition, when observed with a laser microscope, no change was observed on the surface of molybdenite, but the surface of chalcopyrite had turned a dull color, confirming that chalcopyrite was selectively reduced. It was.

(Example 3)
The slurry obtained by preparing the same mineral sample as in Example 1A in the same way was subjected to energization treatment using the same apparatus, but the pH of the electrolytic bath was changed to 4 by adding NaOH to the potassium chloride solution. Adjusted to 9. Thereafter, it was washed with water in the same manner as in Example 1A and subjected to flotation.

  As a result, the floatability of chalcopyrite was about 90%, and high floatability was obtained as in Example 1A. On the other hand, the floating property of molybdenite was not particularly changed as in Example 1A. Further, when observed with a laser microscope, no change was observed on the surface of molybdenite, but the surface of chalcopyrite was turned purple, and it was confirmed that chalcopyrite was selectively oxidized.

(Comparative example)
A slurry obtained by preparing the same mineral sample as in Example 3 above was energized using the same apparatus, but the working electrode was 1.2 V with the counter electrode as the 0 V reference between the counter electrode and the working electrode. Instead, a positive voltage of 1.0 V was applied. Thereafter, it was washed with water in the same manner as in Example 3 and subjected to flotation.

  As a result, the floatability of chalcopyrite was about 50%, which was greatly reduced as compared with the above-described examples. On the other hand, the floating property of molybdenite was not particularly changed as in the examples. Further, when observed with a laser microscope, no change was observed on the surface of molybdenite, but the surface of chalcopyrite was turned purple, and it was confirmed that chalcopyrite was selectively oxidized. It was also found from the results of thermodynamic calculation and XPS analysis that iron hydroxide and copper hydroxide were deposited on the surface.

Claims (4)

A method of separating copper and molybdenum by performing a pretreatment of energizing a sulfide mineral containing copper and molybdenum as a working electrode side and a counter electrode side, and then subjecting the sulfide mineral to flotation. ,
The energization is performed by applying a predetermined voltage between a working electrode and a counter electrode immersed in the slurry containing the sulfide mineral, and the working electrode is installed at a position in contact with the sulfide mineral in the slurry, The said counter electrode is installed in the position which does not contact the sulfide mineral in the said slurry, The separation method of copper and molybdenum characterized by the above-mentioned . And performing the energization by the working electrode the counter electrode between the counter electrode and the working electrode as 0V reference applies a positive voltage to the 1.2～1.4V, in claim 1 The method for separating copper and molybdenum as described. After adjusting the pH of the slurry to 3 or more and 5 or less, a negative voltage at which the working electrode is −0.8 to −1.0 V is applied between the working electrode and the counter electrode with the counter electrode as a reference of 0 V. and performing the energization by a method of separating copper and molybdenum according to claim 1. The method for separating copper and molybdenum according to any one of claims 1 to 3, wherein the energized sulfide mineral is washed before being subjected to the flotation.