JP2020164967A - Processing method of ore - Google Patents

Abstract

To provide a processing method of ore which is capable of effectively removing calcium in ore.SOLUTION: A method for processing ore containing copper and calcium includes: a leaching process of leaching copper and calcium in the ore into acid solution containing copper ion, iron ion and halide ion to obtain post-leaching liquid containing the copper ion, calcium ion and sulfuric acid ion; and an oxidation process of oxidizing copper ion in the post-leaching liquid. In the oxidation process, the temperature of post-leaching liquid during oxidation is set to 0°C to 60°C, and calcium ion in the post-leaching liquid is precipitated as calcium sulfate.SELECTED DRAWING: Figure 1

Description

This specification discloses a technique relating to a method of processing an ore.

Copper ore such as copper sulfide ore and other ores may be subjected to a predetermined wet treatment in order to separate the metal to be recovered after performing a beneficiation treatment such as flotation or specific gravity sorting as necessary to obtain a concentrate. is there. For example, as the wet treatment performed for the purpose of recovering copper from ore, there are those described in Patent Documents 1 to 4 and the like.

This wet treatment involves an leaching step in which copper contained in the ore is leached using a halogen bath in an acidic solution containing copper ions and iron ions as cations and halide ions as anions, and in the liquid after leaching. It includes an oxidation step of oxidizing copper ions and the like of the above by, for example, blowing air. After that, a copper recovery step of recovering copper from the post-oxidation liquid may be performed by solvent extraction, ion exchange, substitution, electrowinning, or the like.

JP-A-2009-235519 U.S. Patent Application Publication No. 2009/0241736 Japanese Unexamined Patent Publication No. 2009-2567664 U.S. Patent Application Publication No. 2009/0241732

The ore subjected to the wet treatment described above may contain calcium as gangue or the like. Calcium in the ore is usually leached into an acidic solution during the leaching process.
However, when the acidic solution is circulated and used in a series of steps such as leaching step, oxidation step and copper recovery step, when the calcium concentration in the acidic solution becomes saturated, calcium in the ore is not leached. , The leachate residue will contain the calcium.

In addition, when the calcium ion concentration and the sulfate ion in the acidic solution are saturated, the calcium ion in the acidic solution may be precipitated as calcium sulfate in the leaching step, and the leaching residue may contain calcium sulfate.

If the leaching residue contains calcium in this way, inconvenience may occur when the leaching residue is subsequently utilized without being discarded.

This specification discloses a method for treating an ore that can effectively remove calcium in the ore.

The method for treating an ore disclosed in this specification is a method for treating an ore containing copper and calcium, in which copper and calcium in the ore are contained in an acidic solution containing copper ion, iron ion and halide ion. Including an leaching step of leaching the copper ion, a post-leaching liquid containing the copper ion, a calcium ion and a sulfate ion, and an oxidation step of oxidizing the copper ion in the post-leaching liquid, the leaching step during oxidation. The temperature of the after-liquid is set to 0 ° C. to 60 ° C., and the calcium ions in the after-liquid are precipitated as calcium sulfate.

According to the above-mentioned ore treatment method, calcium in the ore can be effectively removed.

It is a flow chart which shows the processing method of the ore which concerns on one Embodiment. It is a graph which shows the calcium ion concentration in the post-leaching liquid, the calcium ion concentration in the post-oxidation liquid, and the amount of oxidation residue in each cycle of an Example.

Hereinafter, embodiments of the above-mentioned ore treatment method will be described in detail.
The method for treating an ore according to one embodiment is intended for an ore containing calcium, and leaches calcium in the ore into an acidic solution containing copper ions, iron ions and halide ions to obtain calcium. It includes a leaching step of obtaining a post-leaching liquid containing ions and sulfate ions, and an oxidation step of oxidizing copper ions in the post-leaching liquid.

When targeting an ore containing not only calcium but also copper, the copper may be leached together with calcium in the ore in the leaching step. In this case, the method for treating the ore can further include a copper recovery step of recovering copper from the post-oxidation liquid obtained in the oxidation step. As illustrated in FIG. 1, the post-copper recovery liquid obtained in the copper recovery step can be used as an acidic solution in the leaching step and circulated.

(ore)
The ore to be treated is not particularly limited as long as it contains at least calcium and is used for the above-mentioned leaching step and the subsequent oxidation step.

The ore can typically contain a predetermined sulfur-containing sulfide mineral or an intermediate (smelting intermediate) obtained after smelting the sulfide mineral. The smelting treatment means, for example, in the case of an ore containing a predetermined metal, a treatment of leaching the metal with a predetermined leaching solution, and the leaching residue obtained after such treatment is used as a smelting intermediate. Can be done.
Further, the ore can be a concentrate that has undergone a conventional beneficiation treatment such as flotation or specific gravity sorting, if necessary. It is also possible to reduce the grain size of the ore by performing pulverization ore or the like.

The ore shall be an ore containing calcium and copper. According to the embodiment shown in FIG. 1, the copper contained in such an ore can be recovered.

As the ore, it is effective to target a molybdenum ore, more specifically, a molybdenum ore containing calcium and copper. Various molybdenum ores can be applied. For example, ores containing one or more selected from molybdenite, molybdenum lead ore, pawellite and iron water lead ore, and above all, ores containing molybdenite are floated. Molybdenum concentrate after beneficiation can be mentioned. Copper in molybdenum ore may be present in the form of sulfides, such as chalcocite and / or chalcopyrite.

The ore may contain copper ore. The copper ore contains at least one selected from chalcocite, chalcocite, copper indigo, chalcopyrite, pyrite, enargite, arsenopyrite, galena, zincite, arsenopyrite, chalcocite, and iron porcelain. I have something to do.

The ore contains calcium, for example in an amount of 0.1% to 2%, typically 0.4% to 1.0%, and copper, for example, 1% to 30%. It may typically be contained in an amount of 3% by mass to 10% by mass. The molybdenum content in ores such as molybdenum ore or molybdenum concentrate is, for example, 40% by mass to 55% by mass, typically 46% by mass to 50% by mass.

(Leaching process)
In the leaching step, the above-mentioned ore is brought into contact with an acidic solution containing copper ion, iron ion and halide ion under the supply of an oxidizing agent to leach calcium in the ore. Then, by solid-liquid separation using a filter press, a thickener, or the like, a post-leaching liquid containing calcium ions can be obtained.

When a sulfur-containing ore such as a sulfide mineral is targeted, sulfate ions are generated by the oxidation of sulfur contained in the ore in the leaching step, and the leached liquid also contains sulfate ions.
In the process of recovering copper from an ore as shown in FIG. 1, this leaching step is generally performed mainly for leaching copper from the ore, but at the same time, calcium in the ore is also leached. In this case, the post-leaching liquid contains copper ions and calcium ions. When molybdenum is contained in the ore, the molybdenum is contained in the leaching residue (decopper ore) without leaching.

The concentration of chloride ions in the acidic solution used in the leaching step is preferably 100 g / L or more to 200 g / L, particularly 120 g / L to 180 g / L, from the viewpoint of realizing the copper dissolution reaction with high efficiency. It is even more preferable to set it to L. The concentration of bromide ions can be determined so that the total concentration of halide ions is in the range of 120 g / L to 200 g / L.

The concentration of copper ions in the acidic solution used in the leaching step is preferably 1 g / L to 30 g / L, more preferably 5 g / L to 20 g / L, from the viewpoint of promoting the leaching reaction. .. Iron ion is a component suitable for promoting copper leaching, and is preferably 1 g / L or more from the viewpoint of realizing a copper dissolution reaction with high efficiency. However, when it exceeds 50 g / L, the copper leaching rate increases. It increases significantly and is lost. In order to prevent this, the iron ion concentration in the acidic solution can be 50 g / L or less, preferably 10 g / L or less. The iron ion concentration is particularly preferably 8 g / L or less, and more preferably 6 g / L or less.

The above-mentioned concentrations of bromide ion, chloride ion, copper ion and iron ion mean the concentration in the acidic solution before the acidic solution is brought into contact with the ore.

Examples of the source of chloride ions include hydrogen chloride, hydrochloric acid, metal chloride and chlorine gas, and among them, it is preferable to supply chloride ions in the form of metal chloride in consideration of economy and safety. .. Examples of metals chloride include copper chloride (ferrous chloride, ferric chloride), iron chloride (ferrous chloride, ferric chloride), and alkali metals (lithium, sodium, potassium, rubidium, cesium, franchium). Chlorides and chlorides of alkaline earth metals (berylium, magnesium, calcium, strontium, barium, radium) can be mentioned, and sodium chloride is preferable from the viewpoint of economy and availability. Further, since it can be used as a source of copper ions and iron ions, copper chloride and iron chloride can also be used.

Examples of the source of the bromide ion include hydrogen bromide, hydrobromic acid, metal bromide, and bromine gas. Among them, in the form of metal bromide in consideration of economy and safety. It is preferable to supply. Examples of metals bromide include copper bromide (copper bromide, cupric bromide), iron bromide (ferrous bromide, ferric bromide), alkali metals (lithium, sodium, potassium, etc.). Bromides of rubidium, cesium, franchium) and bromides of alkaline earth metals (berylium, magnesium, calcium, strontium, barium, radium) can be mentioned, and sodium bromide is preferable from the viewpoint of economy and availability. Further, since it can be used as a source of copper ions and iron ions, it is also preferable to use copper bromide and iron bromide.

Copper ions and iron ions are usually supplied in the form of these salts, and can be supplied, for example, in the form of halogenated salts. From the viewpoint that it can also be used as a source of chloride ion and / or bromide ion, it is preferable that copper ion is supplied as copper bromide and / or copper chloride, and iron ion is supplied as iron bromide and / or iron chloride. Examples of copper chloride and iron chloride include cupric chloride (CuCl ₂ ), cuprous chloride (CuCl), ferric chloride (FeCl ₃ ), ferrous chloride (FeCl ₂ ) and the like. Examples of copper bromide and iron bromide include cupric bromide (CuBr ₂ ), cuprous bromide (CuBr), ferric bromide (FeBr ₃ ), ferrous bromide (FeBr ₂ ), and the like. is there.

The method of contacting the acidic solution with the ore is not particularly limited, and there are methods such as sprinkling and dipping, but from the viewpoint of reaction efficiency, a method of immersing the ore in the acidic solution and stirring it is preferable.

The redox potential (vs Ag / AgCl) of the acidic solution at the start of the leaching step is preferably 500 mV or more, and more preferably 600 mV or more, from the viewpoint of promoting leaching. Further, from the viewpoint of increasing the leaching rate of copper, it is preferable to maintain the pH of the acidic solution at 2.0 or less, but since the higher pH of iron is promoted, the pH of the acidic solution is 0. It is more preferable to maintain it at 5 to 1.9.

The redox potential can be controlled by carrying out the leaching step while supplying the oxidizing agent. If no oxidant is added, the redox potential will drop on the way, and there is concern that the leaching reaction will not proceed. Examples of the oxidizing agent include oxygen, air, chlorine, bromine, hydrogen peroxide and the like. No oxidant with an extremely high redox potential is required, air is sufficient.

The pulp concentration of the acidic solution to which the ore is added is preferably 200 g / L or less, and more preferably 15 g / L to 50 g / L. Pulp concentration means the ratio of the dry weight (g) of the ore to the volume (L) of the acidic solution.

The redox potential of the leaching solution after sufficient leaching is about 450 to 600 mV, typically about 500 to 580 mV.

(Oxidation process)
It is considered that most of the copper ions and iron ions in the post-leaching liquid obtained in the leaching step are Cu (I) and Fe (II) as a result of being used as an oxidizing agent at the time of leaching. These copper ions and iron ions are oxidized in order to effectively recover copper in the copper recovery step described later and to repeatedly use the liquid after leaching in the leaching step again, and Cu (II) and Fe (III). ) Is desirable.

In this embodiment, it is particularly important that the temperature of the post-leaching liquid during oxidation is 0 ° C to 60 ° C. As a result, calcium ions in the liquid after leaching generate calcium sulfate together with sulfate ions and precipitate. Here, since the solubility of calcium sulfate is temperature-dependent, by lowering the liquid temperature as described above, the solubility of calcium sulfate is lowered and calcium sulfate is precipitated. Then, by performing solid-liquid separation after oxidation, a post-oxidation liquid in which calcium is reduced can be obtained. Calcium is contained in the oxidation residue in the form of calcium sulfate or the like.

By lowering the liquid temperature during oxidation, the calcium concentration in the post-oxidation liquid is lowered. When the copper recovery liquid obtained by performing the copper recovery step described later on this post-oxidation liquid is repeatedly used as an acidic solution in the leaching step, the acidic solution has a low calcium concentration, so calcium in the ore is leached. Can be made to. After that, the calcium can be transferred to an oxidation residue in the oxidation step in the same manner. Therefore, according to this, calcium in the ore can be effectively removed from the system.
In this embodiment, since calcium in the ore can be removed by the oxidation step, acid cleaning and other pretreatments for removing calcium before the leaching step can be omitted, which may lead to reduction of man-hours. In addition, it cannot be denied that such loss of copper and the like in the ore may occur in such acid cleaning, but if acid cleaning is omitted, there is no risk of such loss.

On the other hand, if calcium is not reduced in the oxidation step, repeated use of the acidic solution in a series of steps of leaching step, oxidation step and copper recovery step increases the calcium concentration in the acidic solution and finally becomes saturated. .. Calcium is contained in the leaching residue because calcium in the ore does not leach into the saturated acidic solution. Calcium in the leaching residue is not desirable because it can inhibit a dry or wet treatment for recovering molybdenum or the like from the leaching residue (decopper ore), for example.

If the temperature of the liquid after leaching during oxidation is too high, the solubility of calcium sulfate may not be sufficiently lowered, and the reduction of calcium in the oxidation step may be insufficient. However, if the temperature of the liquid after leaching during oxidation is too low, there is a concern that the oxidation rate of copper will decrease. From this point of view, the temperature of the leaching solution during oxidation is more preferably 0 ° C. to 30 ° C., and further preferably 0 ° C. to 20 ° C.

By lowering the liquid temperature, the calcium ion concentration in the post-oxidation liquid obtained in the oxidation step is preferably 0.8 g / L or less, and even more preferably 0.6 g / L or less. However, in many cases, the calcium ion concentration in the post-oxidation liquid is 0.9 g / L or more, typically 1.0 g / L or more.

When the above-mentioned operation of lowering the liquid temperature is performed, the oxidation in the oxidation step is preferably performed for 10 to 20 hours. This makes it possible to sufficiently oxidize copper while effectively reducing calcium by precipitating calcium ions in the liquid after leaching as calcium sulfate. If the oxidation time is too short, there is a concern that the oxidation of copper will be insufficient in combination with lowering the liquid temperature as described above. If the oxidation time is too long, it may be necessary to increase the scale of equipment such as increasing the number of tanks used for oxidation in order to extend the oxidation time.

As shown in FIG. 1, when the leaching step, the oxidizing step and the copper recovery step are set as one cycle and the acidic solution is circulated and repeated, Fe (II) is generally converted to Fe (II) in the oxidation step in many cycles. By oxidizing to III) and adjusting the pH, a part of Fe (III) is precipitated to produce an iron compound, which is precipitated. The formation of the iron compound occurs, for example, by the reaction of FeCl ₃ + 2H ₂ O → FeOOH + 3HCl. As a result, the iron concentration of the leached liquid decreases. Here, copper ions are also oxidized from Cu (I) to Cu (II).

In such an oxidation step, in order to effectively oxidize iron ions and prevent precipitation of copper ions, iron ions are generally oxidized in a post-leaching solution having a pH of 0.2 to 2.0, and then obtained. It is preferable that the pH of the oxidized liquid to be obtained is in the range of 1.5 to 2.0. If the pH of the post-oxidation liquid is less than 1.3, iron ion precipitation may not occur. On the other hand, if the pH of the post-oxidation liquid exceeds 3.0, copper may move too much to the solvent side during solvent extraction in the copper recovery step of the next step, and the copper and acid balance of the entire step may be disturbed.

Oxidation of iron ions in the oxidation step includes addition of hydrogen peroxide solution to the liquid after leaching, or blowing of oxygen-containing gas such as oxygen, a mixed gas of oxygen and an inert gas (nitrogen, rare gas, etc.), etc. However, it is particularly preferable to blow in an oxygen-containing gas. Above all, blowing air is preferable in terms of cost.
When the oxygen-containing gas is blown, it is preferable to supply it at a flow rate of 0.01 L / min to 1.5 L / min per 1 L of the leaching liquid. 0.01 L / min is a supply amount such that the dissolved oxygen at 60 ° C. of water does not decrease, and when the supply flow rate of the oxygen-containing gas is too small as described above, it takes time to oxidize. On the other hand, when the supply flow rate of the oxygen-containing gas is too large, a large amount of energy such as electric power is consumed in order to compensate for the heat of vaporization taken away by the evaporation of the liquid into the bubbles.

(Copper recovery process)
In the copper recovery step, copper can be recovered from the post-oxidation liquid after the above oxidation step. The method for recovering copper here is not particularly limited, and for example, solvent extraction, ion exchange, substitution precipitation with a base metal, electrowinning, and the like can be used.

Copper ions in the post-oxidation liquid are in a mixture of monovalent and divalent states. In order to facilitate solvent extraction and ion exchange, it is preferable to pre-oxidize the post-oxidation liquid so that all the copper ions are divalent. The method of oxidation is not particularly limited, but a method of blowing air, oxygen or other oxygen-containing gas into the post-oxidation liquid is convenient.

The copper recovery step further includes a process of subjecting copper in the oxidized liquid to solvent extraction and back extraction, and then recovering it as electrolytic copper on the cathode by electrowinning. This process is generally called the SX-EW (Solvent Extraction and Electro-Winning) method, and is well known to those skilled in the art.

Further, by oxidizing the copper ions in the post-oxidation liquid as described above before solvent extraction, there is an advantage that copper can be back-extracted (striped) after solvent extraction and directly electrowinned. can get. When the oxidation is not performed, monovalent copper is present in a high concentration in the strong chloride bath, so that it precipitates as dendrite copper during electrowinning. Dendrite copper precipitates in the electrolytic cell as a metal powder. Collecting as plate copper at the cathode has many advantages from the viewpoint of operability such as transportation.

Next, the above-mentioned ore treatment method was carried out on a trial basis and its effect was confirmed, which will be described below. However, the description here is for the purpose of mere illustration, and is not intended to be limited thereto.

A series of steps of the leaching step, the oxidizing step, and the copper recovery step shown in FIG. 1 were set as one cycle, and the liquid after copper recovery was repeatedly circulated as an acidic solution. As the ore, molybdenum concentrate containing 4.5% Cu, 2.0% Fe, and 0.43% Ca was targeted. In each cycle, as the conditions of the leaching step, the pulp concentration was set to the amount of concentrate such that the difference in copper ion concentration before and after leaching was 6 g / L, the leaching temperature was set to 75 ° C., the leaching time was set to 6 hours, and air was blown. The amount was 0.1 L / min / L with respect to the volume of the acidic solution. As the conditions of the oxidation step, the oxidation time was 12 hours, and the amount of air blown was 0.2 L / min / L with respect to the volume of the liquid after leaching. In the copper recovery step, 20% -LIX984N (diluent IsoperM) was used as an extractant, and the copper solvent was extracted with an O / A ratio (volume ratio of the organic phase to the aqueous phase) = 1.

Here, the liquid temperature during oxidation was set to 20 ° C. (normal temperature) only in the fourth cycle, and 60 ° C. in the other cycles. The calcium ion concentration in the post-leaching liquid, the calcium ion concentration in the post-oxidation liquid, and the amount of oxidation residue in each cycle are shown graphically in FIG.

From FIG. 2, it can be seen that in the fourth cycle in which the liquid temperature during oxidation was lowered to 20 ° C., the calcium ion concentration of the post-oxidation liquid was significantly reduced and the amount of oxidation residue was significantly increased. It is considered that this is because in the 4th cycle, calcium in the liquid was precipitated due to the decrease in the liquid temperature during oxidation and was contained in the oxidation residue. It is understood that the increase in the calcium concentration in the liquid after leaching in the 5th cycle is due to the effective leaching of calcium in the ore in the leaching step of the 5th cycle.

From the above, it was found that calcium in the ore can be effectively removed by the above-mentioned method.

Claims (9)

A method of treating ores containing copper and calcium.
An leaching step of leaching copper and calcium in the ore into an acidic solution containing copper ions, iron ions and halide ions to obtain a post-leaching liquid containing the copper ions, calcium ions and sulfate ions, and after leaching. Including an oxidation step that oxidizes copper ions in the liquid,
A method for treating an ore, wherein in the oxidation step, the liquid temperature of the leaching liquid during oxidation is set to 0 ° C. to 60 ° C., and calcium ions in the leaching liquid are precipitated as calcium sulfate. The method for treating an ore according to claim 1, wherein the temperature of the liquid after leaching during oxidation is 0 ° C to 30 ° C. The method for treating an ore according to claim 1 or 2, wherein the oxidation step is carried out over 10 to 20 hours. The method for treating an ore according to any one of claims 1 to 3, wherein the calcium ion concentration in the post-oxidation liquid obtained in the oxidation step is 0.8 g / L or less. The ore further contains copper, and in the leaching step, the copper is leached together with calcium in the ore.
The method for treating an ore according to any one of claims 1 to 4, further comprising a copper recovery step of recovering copper from the post-oxidation liquid obtained in the oxidation step. The ore treatment method according to claim 5, wherein the copper recovery liquid obtained in the copper recovery step is used as the acidic solution in the leaching step and circulated. The method for treating an ore according to claim 5 or 6, wherein the content of copper in the ore is 1% by mass to 30% by mass. The method for treating an ore according to any one of claims 1 to 7, wherein the content of calcium in the ore is 0.1% by mass to 2% by mass. The method for treating an ore according to any one of claims 1 to 8, wherein the ore contains molybdenum concentrate.

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