JP2016191118A - Method for recovering rhenium from molybdenum concentrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering rhenium from molybdenum concentrate in which the volatilization ratio of rhenium oxide can be improved in a way having a higher productivity and safety as compared to the conventional method.SOLUTION: Provided is a method for recovering rhenium from molybdenum concentrate including: a pretreatment step for leaching copper and calcium contained in molybdenum concentrate using a chloride ion-containing acidic aqueous solution; an oxidation roasting step for oxidation roasting the molybdenum concentrate processed product obtained in the pretreatment step; and a step for recovering rhenium oxide volatilized in the oxidation roasting step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for recovering rhenium from molybdenum concentrate.

Rhenium is contained in molybdenum ores such as molybdenite (MoS ₂ ) produced in association with copper ore, and when recovering molybdenum from molybdenum ore, rhenium is also volatilized and recovered. It is made from. In particular, the oxide of rhenium (especially Re ₂ O ₇ ) contained in molybdenum ore is volatile, so the molybdenum concentrate obtained by sorting copper and molybdenum by the flotation process is oxidized and roasted, A method of recovering rhenium oxide (Re ₂ O ₇ ) volatilized by oxidative roasting is known (see, for example, Non-Patent Document 1).

  Molybdenum ore is often produced together with copper sulfide, so after separating copper and molybdenum by the flotation method, usually several percent of copper sulfide is mixed in the recovered molybdenum concentrate. Yes. Since copper deteriorates the properties of steel products, it is generally performed in advance to remove copper from molybdenum concentrate by the iron chloride method.

  For example, US Pat. No. 3,674,424 (Patent Document 1) uses an aqueous solution containing an alkali metal or alkaline earth metal chloride as a leachate and removes copper from molybdenum concentrate to increase the purity. Is described.

  Japanese Patent Laid-Open No. 58-189343 (Patent Document 2) describes a method of leaching copper contained as an impurity present in a molybdenum ore mineral using ferric chloride.

US Pat. No. 3,744,424 JP 58-189343 A

Nao Ito, Kei Takashi, Recent Research Recovery of rhenium, Journal of the Japan Institute of Metals, Volume 4, p. 751-760

  However, in the case of using the iron chloride method as described in Patent Documents 1 and 2, in order to perform high temperature treatment using chlorine gas or high pressure gas containing chloride of alkali metal or alkaline earth metal There is a risk in processing, and there are still problems in cost and safety. Furthermore, Patent Documents 1 and 2 only describe a specific method for removing copper from molybdenum concentrate, and no knowledge about the recovery of rhenium oxide obtained by volatilization by subsequent roasting treatment has been made. Absent.

  On the other hand, Non-Patent Document 1 describes an outline of a method for recovering rhenium after oxidative roasting, but does not describe or suggest a specific measure for improving the volatilization rate of rhenium. .

  In view of the above problems, the present invention provides a method for recovering rhenium from molybdenum concentrate that can improve the volatility of rhenium oxide by a safer and more productive method than conventional methods.

  As a result of intensive studies, the present inventor performed a pretreatment for removing copper and calcium in molybdenum concentrate using an acidic chloride bath, that is, an acidic aqueous solution containing chloride ions, and the molybdenum concentrate subjected to the pretreatment. It has been found that by subjecting the ore to oxidative roasting, it is possible to improve the volatility of rhenium oxide using a safer and more productive method.

  The present invention completed on the basis of the above knowledge is, in one aspect, a pretreatment step of leaching copper and calcium contained in molybdenum concentrate using an acidic aqueous solution containing chloride ions, and molybdenum obtained in the pretreatment step. There is provided a method for recovering rhenium from molybdenum concentrate, which includes an oxidation roasting step for oxidizing and roasting the concentrate concentrate and a step of recovering rhenium oxide volatilized in the oxidation roasting step.

  In one embodiment of the method for recovering rhenium from molybdenum concentrate according to the present invention, the acidic aqueous solution containing chloride ions is an acidic aqueous solution containing at least one of copper ions or iron ions, and the pretreatment step is acidic. It includes leaching copper and calcium in molybdenum concentrate while supplying an oxidizing agent to an aqueous solution, and then obtaining a leaching residue and a liquid after leaching by solid-liquid separation.

  In another embodiment of the method for recovering rhenium from the molybdenum concentrate according to the present invention, the pretreatment step comprises chloride ions of 100 to 200 g / L, copper ions of 1 to 30 g / L, and iron ions of 1 to 1. A step of leaching copper and calcium in the molybdenum concentrate by contacting the molybdenum concentrate while supplying an oxygen-containing gas to an acidic aqueous solution containing 10 g / L at 50 to 100 ° C., and then a liquid after leaching by solid-liquid separation Including obtaining a leaching residue.

  In yet another embodiment of the method for recovering rhenium from molybdenum concentrate according to the present invention, the pretreatment step comprises 100 to 200 g / L of chloride ions, 1 to 30 g / L of copper ions, and 1 of iron ions. A step of leaching copper and calcium by contacting an acidic aqueous solution containing ˜20 g / L at 50 to 100 ° C. with molybdenum concentrate, and then obtaining a post-leaching solution and a leaching residue by solid-liquid separation; The oxidation-reduction potential (vs Ag / AgCl) of the acidic aqueous solution at the end point of leaching of 400 to 480 mV.

  In yet another embodiment of the method for recovering rhenium from molybdenum concentrate according to the present invention, the molybdenum concentrate contains 0.5 to 10% by mass of copper, 0.15 to 5.0% by mass of calcium, and iron. 0.3 to 10% by mass and 20 to 60% by mass of molybdenum.

  According to the present invention, rhenium from a molybdenum concentrate that can improve the volatility of rhenium oxide obtained by oxidation roasting treatment of molybdenum concentrate in a more productive and safer method than in the past. A recovery method is obtained.

It is a graph which shows the influence of the Re volatility with respect to the presence or absence of the pretreatment of molybdenum concentrate. It is a graph showing the relationship between the raw material Cu quality of a to-be-roasted processed material, and Re volatilization rate. It is a graph showing the relationship between the raw material Fe quality of a to-be-roasted processed material, and Re volatility. It is a graph showing the relationship between the raw material Ca quality of a to-be-roasted processed material, and Re volatility.

  Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

  The method for recovering rhenium from molybdenum concentrate according to the embodiment of the present invention includes (1) a pretreatment step of leaching copper and calcium contained in molybdenum concentrate, and (2) molybdenum obtained in the pretreatment step. An oxidation roasting step of oxidizing and roasting the concentrate processed product, and (3) a step of recovering rhenium oxide volatilized in the oxidation roasting step.

  In the present embodiment, the molybdenum concentrate to be treated is not particularly limited as long as it is a molybdenum concentrate containing rhenium. For example, at least one selected from molybdenite, molybdenum lead, pawerite, and iron-water lead ore is used. Molybdenum concentrates obtained by flotation of ores containing, especially ores containing molybdenite, are preferably used.

  The copper in the molybdenum concentrate may be present in the form of sulfides, for example in the form of chalcocite and / or chalcopyrite. Although the component composition in the molybdenum concentrate varies depending on the flotation conditions and the like, in one embodiment, the molybdenum concentrate contains 0.5 to 10% by mass of Cu, and in one typical embodiment, 1 to 10 Cu. In a more typical embodiment, 2 to 5% by mass of Cu is contained. The molybdenum concentrate in one embodiment contains 20% by mass or more of Mo, typically contains 20-60% by mass of Mo, more typically contains 30-60% by mass of Mo, and is more typical. In one Embodiment, Mo is contained 40-50 mass%.

  Furthermore, molybdenum concentrate contains 0.15-5.0 mass% of Ca in one Embodiment, More typically, it contains 0.3-2.0 mass% of Ca. Furthermore, the molybdenum concentrate contains 0.3 to 10% by mass of Fe in one embodiment. The Re content in the molybdenum concentrate is not particularly limited, but typically contains 200 to 700 ppm by mass.

(1) Pretreatment step In the pretreatment step according to this embodiment, first, copper and calcium contained in molybdenum concentrate are leached using an acidic aqueous solution containing chloride ions (hereinafter also referred to as “leaching solution”). And a step of solid-liquid separation of the leaching reaction liquid obtained in the leaching step.

  There is no restriction | limiting in particular as a supply source of the chloride ion to acidic aqueous solution, For example, hydrogen chloride, hydrochloric acid, a metal chloride, etc. are mentioned. In consideration of economy and safety, it is preferable to supply in the form of metal chloride. Examples of the metal chloride include copper chloride (cuprous chloride, cupric chloride), alkali metal (lithium, sodium, potassium, rubidium, cesium, francium) chloride, alkaline earth metal (beryllium, magnesium, calcium, (Strontium, barium, radium) chlorides are mentioned, and sodium chloride is preferred from the viewpoint of economy and availability. Moreover, since it can utilize also as a supply source of copper ion, it is also preferable to utilize copper chloride.

The acidic aqueous solution preferably further contains at least one of copper ions and iron ions in addition to chloride ions. Copper ions and iron ions are usually supplied in the form of a salt, and can be supplied, for example, in the form of a halide salt. From the viewpoint that it can also be used as a supply source of chloride ions, copper ions are preferably supplied as copper chloride and iron ions are preferably supplied as iron chloride. As copper chloride and iron chloride, it is preferable to use cupric chloride (CuCl ₂ ) and ferric chloride (FeCl ₃ ) from the viewpoint of oxidizing power, respectively, but cuprous chloride (CuCl) and ferrous chloride are preferable. Even if (FeCl ₂ ) is used, supplying an oxygen-containing gas to the leachate oxidizes to cupric chloride (CuCl ₂ ) and ferric chloride (FeCl ₃ ), respectively, so there is no significant difference.

  In order to efficiently volatilize and recover rhenium oxide in the subsequent roasting process from molybdenum concentrate, the leachate used in the leaching process should be acidic. In particular, since it can be used as a supply source of chloride ions, it is preferably made acidic with hydrochloric acid. The pH of the leaching solution is preferably about 0 to 3 and more preferably about 0.2 to 2.5 as measured by the glass electrode for ensuring the solubility of the leached copper and calcium. . In the present embodiment, a mixed solution of hydrochloric acid, cupric chloride, ferric chloride, and sodium chloride can be used as the leachate used in the pretreatment step.

  As a specific example of the acidic aqueous solution, it is preferable to use an acidic aqueous solution at 50 to 100 ° C. containing 100 to 200 g / L of chloride ions, 1 to 30 g / L of copper ions, and 1 to 10 g / L of iron ions. That is, by using an acidic chloride bath as a leaching solution in the leaching step, not only copper in molybdenum concentrate but also calcium can be more efficiently removed. As a result, the volatilization rate of rhenium oxide obtained by oxidation roasting treatment of molybdenum concentrate can be improved. Furthermore, the copper leaching reaction is also promoted by allowing copper ions to be present in the leaching solution.

  The concentration of chloride ions in the leachate is preferably 100 g / L or more, more preferably 120 g / L or more, and 140 g / L or more from the viewpoint of realizing a copper and calcium dissolution reaction with high efficiency. Even more preferably. However, in consideration of economy, it is not necessary to make the concentration too high, and the concentration of chloride ions in the leachate is generally 200 g / L or less, preferably 180 g / L or less.

  The concentration of copper ions in the leaching solution is preferably 1 g / L or more, and more preferably 5 g / L or more, from the viewpoint of promoting the copper and calcium leaching reaction. However, in consideration of economy, it is not necessary to make the concentration too high, and the concentration of copper ions in the leachate is generally 30 g / L or less, preferably 20 g / L or less.

  Iron ion is a suitable component for promoting copper and calcium leaching, and is preferably 1 g / L or more from the viewpoint of realizing a copper dissolution reaction with high efficiency, but if it exceeds 20 g / L, the leaching rate of Mo Iron concentration in the leachate should be 20 g / L or less, preferably 10 g / L or less, more preferably 8 g / L or less, and 6 g / L or less is more preferable.

  From the viewpoint of preventing leaching of Mo, the total of copper ions and iron ions in the leaching solution is preferably 25 g / L or less, and more preferably 20 g / L or less.

  In addition, the density | concentration of said chloride ion, copper ion, and iron ion points out the density | concentration in the leaching solution before making acidic aqueous solution contact molybdenum concentrate.

  The contact method between the leachate and the molybdenum concentrate is not particularly limited, and there are methods such as spraying and dipping. From the viewpoint of reaction efficiency, a method of dipping and stirring the molybdenum concentrate in the leachate is preferable.

  In the leaching process, it is possible to increase the leaching rate of copper and calcium by supplying an oxygen-containing gas to the leaching solution. By increasing the flow rate of the oxygen-containing gas, the leaching rate of copper and calcium tends to increase. Thereby, since the leaching of copper and calcium proceeds before leaching of molybdenum, it is possible to suppress the loss of molybdenum. Although there is no restriction | limiting in particular as oxygen-containing gas, For example, the mixed gas of air, oxygen, oxygen, and inert gas (nitrogen, a noble gas, etc.) is mentioned. Air is preferable from the viewpoint of economy.

  The oxygen-containing gas is preferably supplied at a flow rate of 0.02 slpm or more, more preferably 0.04 slpm or more, and 0.08 slpm or more from the viewpoint of effectively exhibiting the above-described effects. It is even more preferable to supply at a flow rate of However, if it is supplied excessively, it consumes a lot of energy such as electric power to compensate for the heat of evaporation taken away by evaporation of the liquid into the bubbles, and a layer of bubbles with concentrate particles coated on the surface ( Is generated at a flow rate of 0.5 slpm or less per liter of the leachate, more preferably at a flow rate of 0.25 slpm or less per liter of the leachate, It is even more preferable to supply at a flow rate of 0.15 slpm or less per liter of leachate.

  Alternatively, the leaching step can be performed such that the redox potential (vs Ag / AgCl) of the leachate at the leaching end point is in the range of 400 to 480 mV. Cu and Ca can be more efficiently reduced while suppressing Mo elution. Effective from the viewpoint of leaching. When the redox potential exceeds 480 mV, the elution of Mo cannot be ignored. On the other hand, when the redox potential is less than 400 mV, the leaching rate of copper and calcium becomes extremely slow, which is not industrial. The redox potential of the leachate at the end of leaching is preferably 460 mV or less, more preferably 450 mV or less, even more preferably 440 mV or less, still more preferably 430 mV, and most preferably 420 mV or less.

  The redox potential of the leaching solution at the leaching end point is preferably 410 mV or more. The oxidation-reduction potential of the leachate gradually decreases with the lapse of the leaching time unless a special operation such as blowing in oxygen-containing gas is performed. In order to control within such a range, it is important to set the liquid composition and the pulp concentration so that the oxidation-reduction potential is sufficiently high at the initial stage of leaching.

  It is desirable that the oxidation-reduction potential be maintained in the above range not only during the leaching end point but also during leaching. This is to obtain a stable leaching effect. Specifically, it is preferable to maintain the redox potential in the above-described range from 2 hours after the start of leaching until the end of leaching. It is more preferable to maintain it.

  The leaching start time is the time when contact between the leachate and the molybdenum concentrate starts, and the leaching end point means the time when the leachate is solid-liquid separated from the molybdenum concentrate.

  The temperature of the leachate used in the pretreatment step is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and even more preferably 70 ° C. or higher, from the viewpoint of leaching efficiency and material of the apparatus. If it is too high, the leachate will evaporate and the heating cost will increase. Therefore, it is preferably 100 ° C. or lower, more preferably 90 ° C. or lower, and more preferably 85 ° C. or lower. It is possible to carry out the pretreatment step under pressure for the purpose of increasing the leaching efficiency, but it is sufficient under atmospheric pressure. That is, a pressure vessel for performing a high pressure leaching step is not required, and a simpler apparatus can be used. In order to promote leaching of copper and calcium, it is preferable to pulverize and grind the molybdenum concentrate to be treated in advance.

  In the pretreatment step, it is preferable to increase the amount of molybdenum concentrate with respect to the leaching solution used from the viewpoint of reducing the leaching cost. Therefore, in one embodiment of the present invention, the leaching step can be performed at a pulp concentration of 50 g / L or more, and in another embodiment of the present invention, the leaching step is performed at a pulp concentration of 150 g / L or more. In yet another embodiment of the present invention, the leaching step can be performed at a pulp concentration of 300 g / L or more. On the other hand, from the viewpoint of increasing the leaching rate, it is preferable that the amount of molybdenum concentrate with respect to the leaching solution to be used is small. Therefore, in one embodiment of the present invention, the leaching step is performed at a pulp concentration of 800 g / L or less. In another embodiment of the present invention, the leaching step can be performed at a pulp concentration of 600 g / L or less, and in yet another embodiment of the present invention, a pulp concentration of 500 g / L or less. A leaching process can be performed. Here, the pulp concentration is the ratio of molybdenum concentrate (dry weight (g)) to the volume (L) of the leachate used.

  The leaching process of copper and calcium can be carried out in one stage, but the leaching process can also be carried out in a plurality of stages in order to sufficiently brew copper in the molybdenum concentrate. Specifically, the leaching process using multiple stages is carried out by performing solid-liquid separation with a filter press or thickener after completing the leaching operation in the first stage and performing the next stage copper leaching operation on the leaching residue. can do.

  According to the present invention, copper and calcium can be leached while suppressing leaching of molybdenum. For example, in one embodiment of the present invention, a copper leaching rate of 70% or more can be achieved while suppressing the molybdenum concentration in the liquid after leaching to 0.001 g / L or less. In another embodiment of the present invention, it is possible to achieve a copper leaching rate of 90% or more while suppressing the molybdenum concentration in the liquid after leaching to 0.005 g / L or less. In one embodiment, a copper leaching rate of 95% or more can be achieved while suppressing the molybdenum concentration in the liquid after leaching to 0.005 g / L or less.

  In addition, the leaching step is carried out until the copper grade in the leaching residue is 2.0 mass% or less, preferably 1.5 mass% or less, and typically about 0.3 to 1.2 mass%. Is preferred. Thereby, the volatilization rate of Re in the oxidation roasting step described later can be increased to 85% or more.

  Alternatively, the leaching step is preferably carried out until the calcium quality in the leaching residue is 1500 ppm or less, preferably 500 ppm or less. The lower limit of calcium quality is not particularly limited, but is preferably 200 ppm or more from the viewpoint of leaching treatment time and productivity. Thereby, the volatility of Re in the oxidation roasting step described later can be increased to 80% or more, more typically 85% or more.

  Alternatively, in the leaching step, the iron grade in the leaching residue is 10% by mass or less, preferably 5% by mass or less, more preferably 3.6% by mass or less, typically 2.0 to 3.8% by mass, or more. It is preferable to carry out until 2.5 to 3.5% by mass.

  The time required for the leaching depends on the copper grade in the molybdenum concentrate as a raw material, but the time required for the copper grade in the leaching residue to be 0.5 mass% is, for example, about 4 to 10 hours, Typically about 5-6 hours.

(2) Oxidation roasting step Next, the leaching residue (molybdenum concentrate processed product) obtained by solid-liquid separation in the pretreatment step is oxidized and roasted. In the oxidative roasting treatment, the treatment temperature of the treated product is preferably 500 to 600 ° C, more typically around 550 ° C. For the oxidation roasting treatment, an oxygen-containing gas such as air is supplied to the roasting furnace. The oxygen-containing gas is supplied so as to be typically 2.0 to 8.0 (L / g-MoS ₂ ), more typically 2.5 to 6.0 (L / g-MoS ₂ ). It is preferable to do. The roasting time is not particularly limited, but can be, for example, about 1.5 to 6 hours.

(3) Rhenium oxide recovery step The rhenium oxide volatilized in the roasting step is dissolved as dust or in washing water in exhaust gas cleaning, and recovered as a solution (hereinafter, the solution is also referred to as “waste acid”).

(Rhenium recovery)
Recovery of rhenium from dust or spent acid can be recovered by well-known techniques. For example, it is possible to recover Re as ammonium perrhenate (APR) by separating Re from a solution obtained by dissolving dust with water or acid, or by separating waste acid from a strongly basic resin and then eluting with an ammoniacal solution.

<Others>
(Iron oxidation)
The leachate obtained in the leaching step contains iron in which a part of iron in the molybdenum concentrate is dissolved in addition to iron originally contained in the leachate. Many of these iron ions are thought to be Fe (II). This can be oxidized to Fe (III) and used again for leaching. Further, by adjusting the pH, a part of Fe (III) is precipitated, and the iron concentration in the leachate can be controlled. As oxidation conditions, aeration at 20 to 70 ° C. and pH 1.5 to 3.0 is most preferable in terms of cost and reaction rate. The higher the temperature and pH, the faster the reaction rate.

(Copper recovery)
Copper can be recovered from the post-leaching solution obtained in the leaching step. Although there is no restriction | limiting in particular as a copper collection | recovery method, For example, solvent extraction, ion exchange, substitution precipitation with a base metal, electrowinning, etc. can be utilized. The copper in the solution after leaching contains both monovalent and divalent states, but in order to perform solvent extraction and ion exchange smoothly, all of them should be oxidized beforehand to be divalent copper ions. Is preferred. The method of oxidation is not particularly limited, but a method of leaching air or oxygen into the liquid after leaching is simple.

  In one embodiment of the method for treating molybdenum concentrate according to the present invention, the method further includes the step of recovering copper in the solution after leaching as electrolytic copper on the cathode by electrolytic extraction through solvent extraction and back extraction. The process itself is generally called a SX-EW (Solvent Extraction and Electro-Winning) method and is well known to those skilled in the art.

In addition, before the solvent extraction, a step of oxidizing copper in the liquid by blowing an oxygen-containing gas such as air into the liquid after leaching can also be performed. This provides the advantage that copper can be back extracted (striped) after solvent extraction and directly electrowinned. In the case of not passing through the oxidation step, monovalent copper is present in a high concentration in the strong chloride bath, so that it is deposited as dendrite copper during electrowinning. Dendritic copper precipitates in the electrolytic cell as a metal powder. It is overwhelmingly more advantageous in terms of operability such as transportation when recovered as plate-like copper on the cathode. Furthermore, solid-liquid separation can also be performed after the oxidation step. Solid-liquid separation is advantageous in increasing the copper purity in the liquid after leaching because it moves to an oxidation residue when iron is contained in the leaching liquid.

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

(Example 1: Influence of volatilization rate improvement by presence or absence of pre-processing)
We prepared a pulverized molybdenum concentrate selected by floatation from ores containing molybdenite. Molybdenum concentrate was analyzed by ICP emission spectroscopy (ICP-OES) after acid dissolution, and was found to have Mo: 45 mass%, Cu: 3.6 mass%, Fe: 4.5 mass%, S: 37 mass%. , Re: 350 ppm, Ca: 3700 ppm. It has an ionic composition of total chloride ions of 180 g / L, Cu ions of 18 g / L, Fe ions of 2 g / L, and hydrochloric acid of 7 g / L, so that the pH is 0.75. After preparing a leachate (acidic aqueous solution) in which dicopper and sodium chloride were mixed, 4L of this leachate was heated to 75 ° C. with a hot stirrer, and then 1520 g of the molybdenum concentrate was added and air blowing into the leachate (0.37 slpm) A leaching test was carried out while continuing stirring, and solid-liquid separation was performed to obtain a liquid after leaching and a leaching residue. The metal in the leachate and the residue was analyzed by ICP emission spectroscopic analysis. The ion concentration was calculated on the assumption that the components of the leachate were completely ionized.

  When the leaching residue obtained by solid-liquid separation was analyzed by ICP emission spectrometry, Mo: 51% by mass, Cu: 0.45-0.47% by mass, Fe: 2.9-3.0% by mass, S: 40% by mass, Re: 380 ppm, Si: 15000 ppm, Ca: less than 100 ppm to 1000 ppm. The composition of the leaching residue is shown in Table 1 (in Table 1, Conventional Examples 1 to 3 show the composition of molybdenum concentrate (raw ore) not subjected to leaching treatment).

  The leaching residue shown in Table 1 was subjected to oxidation roasting treatment while changing the roasting time and gas velocity under the conditions shown in Table 2. The relationship of the volatilization rate (Re volatilization rate [%]) of rhenium oxide obtained by the oxidation roasting process with respect to each roasting time is shown in FIG. For comparison, molybdenum concentrates not subjected to the above pretreatment (leaching / solid-liquid separation) were similarly subjected to oxidation roasting treatment while changing the roasting time and gas velocity, and the Re volatility was compared. . Table 2 shows the evaluation results of the Re volatilization rate and the residue rate of the roasting residue obtained by the oxidation roasting treatment.

The evaluation of the Re volatility was calculated according to the following formulas (1) and (2) assuming that Si does not volatilize during roasting.
Re volatilization rate (%) = 100 × (1- (residue Re quality (ppm) × residue rate (%) / raw material Re quality (ppm) × 100)) (1)
Residual rate (%) = 100 × (raw material Si quality (ppm) / residual Si quality (ppm)) (2)

  As shown in FIG. 1, prior to the roasting treatment, by performing a pretreatment for removing copper and calcium from the molybdenum concentrate according to the present invention (Examples 1 to 3 of the present invention), no conventional pretreatment is performed. It can be seen that the rhenium volatility is improved by about 10% compared to Examples 1 to 3.

(Example 2: Effect of Re volatilization rate on Cu, Ca, Fe quality reduced by pretreatment)
Leaching the same molybdenum concentrate as in Example 1 using the same leachate as in Example 1 as acidic leachate 1 and using hydrochloric acid as the leachate to remove Ca in the molybdenum concentrate as acidic leachate 2 After the treatment and solid-liquid separation, a leaching residue having the composition shown in Table 3 was obtained. The leaching residue was subjected to oxidation roasting treatment under the conditions shown in Table 4 to recover rhenium oxide, and the Re volatilization rate was calculated. For comparison, molybdenum concentrates not subjected to the above pretreatment (leaching / solid-liquid separation) were also subjected to oxidation roasting treatment to recover rhenium oxide, and the Re volatilization rate and the residue rate of the roasting residue were calculated. .

As shown in FIG. 2, the Re volatilization rate was lower than 80% when the molybdenum concentrate without pretreatment was oxidized and roasted, whereas the Re volatilization was performed when the Ca was removed by the acidic leachate 2. The rate exceeded 80%. Furthermore, when the copper removal and the Ca removal treatment were performed with the acidic leachate 1, the Re volatilization rate could be improved up to 89.6%. Moreover, it turns out that Re volatilization rate can be improved from FIGS. 2-4 by adjusting Cu, Fe, and Ca quality of the oxidation roasting object processed material. This is because the treated product of molybdenum concentrate after pre-treatment has reduced Ca and Cu quality compared to the molybdenum concentrate before pre-treatment, so that it reacts with Ca and Cu in the treated product in the oxidation roasting treatment. This is considered to be because it was not volatilized in the form of Ca (ReO ₄ ) ₂ , Cu (ReO ₄ ) ₂ or the like.

  Moreover, the residue S quality in the residue obtained after roasting can also be reduced by carrying out oxidation roasting of the molybdenum concentrate which performed the pre-processing which concerns on this embodiment. Thereby, since the sulfur density | concentration in a baking process residue can be reduced, it turns out that the purity of the collect | recovered molybdenum trioxide can be improved more.

Claims (5)

A pretreatment step of leaching copper and calcium contained in molybdenum concentrate using an acidic aqueous solution containing chloride ions;
An oxidation roasting step of oxidizing and roasting the molybdenum concentrate processed product obtained in the pretreatment step;
A method for recovering rhenium from molybdenum concentrate, the method including recovering volatilized rhenium oxide in the oxidation roasting step. The acidic aqueous solution containing chloride ions is an acidic aqueous solution containing at least one of copper ions or iron ions,
2. The pretreatment step includes leaching copper and calcium in the molybdenum concentrate while supplying an oxidizing agent to the acidic aqueous solution, and then obtaining a leaching residue and a liquid after leaching by solid-liquid separation. For recovering rhenium from molybdenum concentrates.   The pretreatment step supplies oxygen-containing gas to the acidic aqueous solution at 50 to 100 ° C. containing 100 to 200 g / L of chloride ions, 1 to 30 g / L of copper ions, and 1 to 10 g / L of iron ions. The molybdenum concentrate according to claim 1, further comprising: contacting the molybdenum concentrate while leaching copper and calcium in the molybdenum concentrate, and then obtaining a post-leaching solution and a leaching residue by solid-liquid separation. Method for recovering rhenium.   In the pretreatment step, the acidic aqueous solution containing 50 to 100 ° C. containing 100 to 200 g / L of chloride ions, 1 to 30 g / L of copper ions, and 1 to 20 g / L of iron ions is brought into contact with molybdenum concentrate. A step of leaching copper and calcium, and then obtaining a post-leaching solution and a leaching residue by solid-liquid separation, and the oxidation-reduction potential (vs Ag / AgCl) of the acidic aqueous solution at the leaching end point of copper and calcium is 400 to The method for recovering rhenium from molybdenum concentrate according to claim 1, comprising adjusting the pressure to 480 mV.   The molybdenum concentrate contains 0.5 to 10% by mass of copper, 0.15 to 5% by mass of calcium, 0.3 to 10% by mass of iron, and 20 to 60% by mass of molybdenum. The method for recovering rhenium from the molybdenum concentrate according to any one of the above.

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