JP7153599B2 - Ore processing method - Google Patents

Description

This specification discloses a technology related to a method of processing ore.

Copper ore such as copper sulfide ore and other ores can be subjected to beneficiation treatment such as flotation and specific gravity separation as required to obtain concentrate, and then subjected to a prescribed wet treatment to separate the metals to be recovered. be. For example, the wet treatment for the purpose of recovering copper from ore is described in Patent Documents 1 to 4 and the like.

This wet treatment includes a leaching step of leaching the copper contained in the ore using a halogen bath with an acidic solution containing copper ions and iron ions as cations and halide ions as anions, and and an oxidation step in which the copper ions and the like are oxidized, for example by air blowing. After that, a copper recovery step may be performed to recover copper from the post-oxidation solution by solvent extraction, ion exchange, substitution, electrolytic winning, or the like.

JP 2009-235519 A U.S. Patent Application Publication No. 2009/0241736 JP 2009-256764 A 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 typically leached into an acidic solution during the leaching process.
However, when the acid solution is circulated and used in a series of processes such as the leaching process, the oxidation process, and the copper recovery process, for example, when the calcium concentration in the acid solution becomes saturated, the calcium in the ore is no longer leached. , the calcium is contained in the leaching residue.

Moreover, when the calcium ion concentration and sulfate ions in the acidic solution are saturated, the calcium ions in the acidic solution may precipitate 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 utilized without being disposed of afterwards.

This specification discloses an ore treatment method capable of effectively removing calcium in the ore.

Disclosed herein is a method of treating an ore containing copper and calcium, wherein copper and calcium in the ore are treated in an acidic solution containing copper ions, iron ions and halide ions. and a leaching step of obtaining a post-leaching solution containing the copper ions, calcium ions and sulfate ions; and an oxidation step of oxidizing the copper ions in the post-leaching solution. The liquid temperature of the post-leaching solution is set to 0° C. to 60° C., and calcium ions in the post-leaching solution are precipitated as calcium sulfate.

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

1 is a flow diagram showing a method for processing ore according to one embodiment; FIG. 4 is a graph showing the calcium ion concentration in the post-leaching solution, the calcium ion concentration in the post-oxidation solution, and the amount of oxidation residue in each cycle of Examples.

An embodiment of the above-described ore processing method will be described in detail below.
A method for treating ore according to one embodiment is intended for ore containing calcium, leaching calcium in the ore into an acidic solution containing copper ions, iron ions and halide ions, It includes a leaching step of obtaining a post-leaching solution containing ions and sulfate ions, and an oxidation step of oxidizing copper ions in the post-leaching solution.

When an ore containing copper as well as calcium is targeted, the copper may be leached out together with the calcium in the ore in the leaching process. In this case, the ore treatment method may further include a copper recovery step of recovering copper from the post-oxidation solution obtained in the oxidation step. The post-copper recovery solution obtained in the copper recovery step can be used as an acidic solution in the leaching step and circulated, as illustrated in FIG.

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

The ore can typically contain certain sulfur-containing sulfide minerals or intermediates obtained after smelting the sulfide minerals (smelting intermediates). The smelting process means, for example, in the case of an ore containing a predetermined metal, a process 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.
The ore can also be made into a concentrate that has undergone a conventional beneficiation treatment such as flotation or gravity separation, if desired. Alternatively, the ore can be made to have a smaller grain size by performing pulverization or the like.

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

As the ore, it is effective to target molybdenum ore, more specifically molybdenum ore containing calcium and copper. Various kinds of molybdenum ores can be applied, but for example, ores containing one or more selected from molybdenum, molybdenum, powellite and ferruginite, especially molybdenum ores, are suspended. Mention may be made of molybdenum concentrate after beneficiation. Note that copper in molybdenum ores may exist 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, bornite, copper indigo, chalcopyrite, pyrite, arsenopyrite, arsenopyrite, galena, sphalerite, arsenopyrite, stibnite, and pyrrhotite. I have something to do.

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

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

When an ore containing sulfur such as a sulfide mineral is targeted, in the leaching step, oxidation of the sulfur contained in the ore generates sulfate ions, and the solution after leaching also contains sulfate ions.
In the process of recovering copper from ores, such as that shown in FIG. 1, the leaching step is generally performed primarily to leach copper from the ore, although calcium in the ore is also leached along with it. In this case, the post-leaching solution contains copper ions and calcium ions. In addition, when molybdenum is contained in the ore, the said molybdenum is contained in the leaching residue (decopperized ore) without being leached out.

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 a copper dissolution reaction with high efficiency. L is even more preferable. The concentration of bromide ions can be determined such that the total concentration of halide ions is within 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 ions are a suitable component for promoting copper leaching, and from the viewpoint of realizing a copper dissolution reaction with high efficiency, it is preferably 1 g / L or more, but if it exceeds 50 g / L, the copper leaching rate decreases. Remarkably increased and lost. In order to prevent this, the iron ion concentration in the acid 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, more preferably 6 g/L or less.

In addition, each density|concentration of said bromide ion, chloride ion, copper ion, and iron ion means the density|concentration in the acidic solution before contacting an ore with an acidic solution.

Chloride ion sources include, for example, hydrogen chloride, hydrochloric acid, metal chloride, and chlorine gas. Among them, it is preferable to supply metal chloride in the form of metal chloride in consideration of economy and safety. . Examples of metal chlorides include copper chloride (cuprous chloride, cupric chloride), iron chloride (ferrous chloride, ferric chloride), and alkali metals (lithium, sodium, potassium, rubidium, cesium, francium). Chlorides and chlorides of alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, radium) can be mentioned, and sodium chloride is preferred from the viewpoint of economy and availability. Moreover, since it can be used as a source of copper ions and iron ions, it is also possible to use copper chloride and iron chloride.

Sources of bromide ions include, for example, hydrogen bromide, hydrobromic acid, metal bromide and bromine gas. preferably supplied. Examples of metal bromides include copper bromide (cuprous bromide, cupric bromide), iron bromide (ferrous bromide, ferric bromide), alkali metals (lithium, sodium, potassium, rubidium, cesium, francium) and alkaline earth metal (beryllium, magnesium, calcium, strontium, barium, radium) bromides, and sodium bromide is preferred from the viewpoint of economy and availability. It is also preferable to use copper bromide and iron bromide because they can also be used as sources of copper ions and iron ions.

Copper ions and iron ions are usually supplied in the form of their salts, and can be supplied, for example, in the form of halide salts. Copper ions are preferably supplied as copper bromide and/or copper chloride, and iron ions are preferably supplied as iron bromide and/or iron chloride, from the viewpoint that they can also be used as a supply source of chloride ions and/or bromide ions. Copper chloride and iron chloride include cupric chloride (CuCl ₂ ), cuprous chloride (CuCl), ferric chloride (FeCl ₃ ), ferrous chloride (FeCl ₂ ), and the like. Copper bromide and iron bromide include cupric bromide (CuBr ₂ ), cuprous bromide (CuBr), ferric bromide (FeBr ₃ ), ferrous bromide (FeBr ₂ ), and the like. be.

The method of contacting the ore with the acid solution is not particularly limited, and includes methods such as spraying and immersion. From the viewpoint of reaction efficiency, the method of immersing the ore in the acid solution and stirring is preferred.

The oxidation-reduction potential (vs Ag/AgCl) of the acidic solution at the start of the leaching step is preferably 500 mV or higher, more preferably 600 mV or higher, from the viewpoint of promoting leaching. 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. It is more preferable to keep it between 5 and 1.9.

The oxidation-reduction potential can be controlled by performing the leaching step while supplying the oxidizing agent. If the oxidizing agent is not added, the oxidation-reduction potential will drop in the middle, and there is concern that the leaching reaction will not proceed. Oxidants include, for example, oxygen, air, chlorine, bromine, hydrogen peroxide, and the like. Oxidants with extremely high redox potentials are not required, air is sufficient.

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

After sufficient leaching, the leaching solution has an oxidation-reduction potential of approximately 450 to 600 mV, typically 500 to 580 mV.

(Oxidation process)
It is believed that many of the copper ions and iron ions in the post-leaching solution obtained in the leaching step are Cu(I) and Fe(II) as a result of being used as an oxidizing agent during leaching. These copper ions and iron ions are oxidized to Cu (II), Fe (III ) is desirable.

In this embodiment, it is particularly important to set the liquid temperature of the post-leaching liquid during oxidation to 0.degree. C. to 60.degree. As a result, calcium ions in the post-leaching solution form and precipitate calcium sulfate together with sulfate ions. Here, since the solubility of calcium sulfate depends on temperature, the solubility of calcium sulfate is lowered by making the liquid temperature relatively low as described above, and calcium sulfate precipitates. By performing solid-liquid separation after oxidation, a post-oxidation liquid with reduced calcium is obtained. The oxidation residue contains calcium in the form of calcium sulfate or the like.

By lowering the liquid temperature during oxidation, the calcium concentration in the post-oxidation liquid decreases. When the post-copper recovery solution obtained by performing the below-described copper recovery step on the post-oxidation solution is repeatedly used as an acidic solution in the leaching step, the acid solution has a low calcium concentration, so the calcium in the ore is leached. can be made The calcium can then be transferred to the oxidation residue in the same way in the oxidation step. Therefore, according to this, calcium in the ore can be effectively removed out of the system.
In this embodiment, since the calcium in the ore can be removed in the oxidation step, it is possible to omit acid washing and other pretreatments for calcium removal before the leaching step, which may lead to a reduction in man-hours. In addition, although it cannot be denied that such acid washing may cause loss of copper or the like in the ore, such a loss is not likely to occur if the acid washing is omitted.

On the other hand, if the calcium is not reduced in the oxidation process, repeated use of the acidic solution in the series of leaching, oxidation, and copper recovery processes will increase the calcium concentration in the acidic solution, eventually reaching a saturated state. . Calcium is contained in the leach residue because the calcium in the ore does not leach into the saturated acidic solution. Calcium in the leaching residue is undesirable because it can interfere with dry or wet processes for recovering molybdenum and the like from the leaching residue (decopperized ore), for example.

If the liquid temperature of the post-leaching liquid during oxidation is too high, the solubility of calcium sulfate may not be lowered sufficiently, and the reduction of calcium in the oxidation step may become insufficient. However, if the temperature of the post-leaching solution during oxidation is too low, there is concern that the oxidation rate of copper will decrease. From this point of view, the liquid temperature of the post-leaching liquid during oxidation is preferably 0°C to 30°C, more 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, 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 liquid temperature lowering operation described above is performed, the oxidation in the oxidation step is preferably performed for 10 to 20 hours. As a result, calcium ions in the post-leaching solution can be precipitated as calcium sulfate to effectively reduce calcium while sufficiently oxidizing copper. If the oxidation time is too short, there is a concern that oxidation of copper will be insufficient in combination with the lowering of the liquid temperature as described above. If the oxidation time is too long, it may be necessary to increase the scale of the facility, such as increasing the number of tanks used for oxidation, in order to extend the oxidation time.

Assuming that the leaching process, the oxidation process, and the copper recovery process are regarded as one cycle as shown in FIG. By oxidation to III) and adjusting the pH, some of the Fe(III) is precipitated to form and precipitate iron compounds. The production of iron compounds occurs, for example, by the reaction FeCl ₃ +2H ₂ O→FeOOH+3HCl. This reduces the iron concentration in the post-leaching solution. Here, copper ions are also oxidized from Cu(I) to Cu(II).

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

Oxidation of iron ions in the oxidation process can be achieved by adding hydrogen peroxide solution to the leached solution, or blowing oxygen-containing gas such as oxygen or a mixed gas of oxygen and inert gas (nitrogen, rare gas, etc.). Blowing of an oxygen-containing gas is particularly preferred. Among them, blowing air is preferable in terms of cost.
When the oxygen-containing gas is blown, it is preferably supplied at a flow rate of 0.01 L/min to 1.5 L/min per 1 L of the leached liquid. The supply rate of 0.01 L/min is such that the dissolved oxygen in water at 60° C. does not decrease, and if the flow rate of the oxygen-containing gas is too low, oxidation takes time. On the other hand, if the supply flow rate of the oxygen-containing gas is too high, a large amount of energy such as electric power is consumed in order to compensate for the evaporation heat 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 solution after the oxidation step. The method for recovering copper here is not particularly limited, but for example, solvent extraction, ion exchange, displacement deposition with a base metal, electrowinning, and the like can be used.

Copper ions in the post-oxidation solution are in a mixture of monovalent and divalent states. In order to perform solvent extraction and ion exchange smoothly, it is preferable to previously oxidize the post-oxidation solution so that all the copper ions become divalent copper ions. The oxidation method is not particularly limited, but a simple method is to blow air or oxygen or other oxygen-containing gas into the post-oxidation solution.

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

In addition, by oxidizing the copper ions in the post-oxidation solution before solvent extraction as described above, there is the advantage that copper can be stripped directly after solvent extraction and directly electrowinning. can get. Without such oxidation, univalent copper is present in high concentrations in strong chloride baths and is deposited as dendritic copper during electrowinning. Dendrite copper precipitates in the electrolytic bath as metal powder. There are many advantages from the viewpoint of operability, such as transportation, to recover the copper sheet in the cathode.

Next, the ore treatment method as described above was carried out on a trial basis, and the effect was confirmed, which will be described below. However, the description herein is for illustrative purposes only and is not intended to be limiting.

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

Here, the liquid temperature during oxidation was 20° C. (normal temperature) only in the fourth cycle, and 60° C. in other cycles. FIG. 2 graphically shows the calcium ion concentration in the post-leaching solution, the calcium ion concentration in the post-oxidation solution, and the oxidation residue amount in each cycle.

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 in the post-oxidation liquid decreased significantly and the oxidation residue amount increased significantly. This is probably because in the 4th cycle, calcium in the liquid precipitated due to a drop in the liquid temperature during oxidation and was included in the oxidation residue. The increase in calcium concentration in the leaching solution in the 5th cycle is considered to be due to effective leaching of calcium in the ore in the leaching process in the 5th cycle.

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

Claims (9)

A method of processing ore containing copper and calcium comprising:
a 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 solution containing the copper ions, calcium ions and sulfate ions; and an oxidation step of oxidizing the copper ions in the liquid,
A method of treating an ore, wherein in the oxidation step, the temperature of the post-leaching solution during oxidation is set to 0° C. to 60° C., and calcium ions in the post-leaching solution are precipitated as calcium sulfate. The method for treating ore according to claim 1, wherein the liquid temperature of the liquid after leaching during oxidation is 0°C to 30°C. The method for treating ore according to claim 1 or 2, wherein in the oxidation step, oxidation is performed for 10 to 20 hours. The method for treating ore according to any one of claims 1 to 3, wherein the post-oxidation liquid obtained in the oxidation step has a calcium ion concentration of 0.8 g/L or less. the ore further contains copper, and the leaching step leaches the copper together with the calcium in the ore;
The ore processing method 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. 6. The ore processing method according to claim 5, wherein the post-copper recovery solution obtained in the copper recovery step is used as the acidic solution in the leaching step and circulated. The method for treating 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 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. A method of treating ore according to any one of claims 1 to 8, wherein said ore comprises molybdenum concentrate.

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