WO2012053614A1 - Copper concentrate treatment method - Google Patents

Abstract

A copper concentrate treatment method characterized by comprising: a roasting step of roasting an enargite (Cu₃AsS₄) or a copper concentrate mainly composed of an enargite at 550-700°C in an inert gas atmosphere; and a leaching step of subjecting a calcined pyrite mainly composed of copper pyrite, which is produced in the roasting step, to a leaching treatment employing a chlorine leaching technique in which an oxidizing agent containing Cu (bivalent) and Fe (trivalent) is added, thereby leaching copper.

Description

Copper concentrate processing method

The present invention relates to a method for treating copper concentrate. More specifically, it provides a method for recovering copper by wet treatment of roasted arsenite or high arsenic grade copper concentrate mainly composed of arsenite ore in an inert atmosphere. is there.

Copper ores produced at copper mines are mainly sulfide ores. If sulfide ores are roughly classified, they are relatively high copper grades mainly composed of minerals such as chalcocite (Cu ₂ S) and copper indigo (CuS). There are relatively low copper grade primary sulfide ores mainly composed of secondary copper sulfide ores and chalcopyrite (CuFeS ₂ ). Sulfide ore is crushed, ground, and processed to improve copper grade, to make copper concentrate, which is mainly used for dry copper smelting including flash smelting.

On the other hand, copper oxide ore is also produced in the relatively surface layer of the copper mine, which is generally used in the mine ancillary equipment by smelting sulfuric acid followed by solvent extraction-electrolytic extraction (SX-EW). Processed at a relatively low cost. However, since the amount of copper oxide ore is extremely small among copper ores, in recent years, the facility for processing the oxide ore is effectively used to reduce the capital investment, and it is relatively easy to leach with the oxide ore. Hydrometallurgical smelting for secondary sulfide ore mixed or secondary sulfide ore is also performed.

Furthermore, recently, there is a movement to try applying hydrometallurgy to primary sulfide ores. This is because of the high copper value, newly developed small-scale mines with insufficient infrastructure such as copper concentrate transportation roads, and the production of copper concentrates for dry smelting due to a decline in the quality of copper ore produced. There is a growing need in mines where cost increases and copper and precious metals recovery rates are suffering.

In recent years, copper ores collected at copper mines operating around the world are mainly primary sulfide ores, and iron, sulfur, and other impurities have increased, and the copper quality has been on the decline. This leads to an increase in copper concentrate production costs for dry copper smelting. Of the impurities in copper ore, arsenic is considered the most problematic. Although arsenic depends on the form of its existence, it is extremely harmful and has few applications in the industrial field, so most of it needs to be discarded or stored in a stable form. For this reason, the mine smelter has given a certain limit (usually about <0.3 mass%) to the arsenic in the copper concentrate to be purchased. It is common to pay penalties to the smelter according to the excess amount.

Therefore, from the mine's perspective, in order to reduce costs and extend the life of the mine, low-grade copper concentrate (primary sulfide ore) treatment methods and efficient treatment methods for sulfide ores containing a large amount of arsenic are important concerns. is there. On the other hand, the purchase smelter is likely to need to deal with arsenic-rich copper concentrate in the future due to depletion of high-quality ore and tight supply and demand of copper concentrate.

As a means for solving these problems, there is a wet treatment of primary sulfide ore as described above. For example, a copper concentrate obtained by beneficiating primary sulfide ore mainly composed of hardly leachable chalcopyrite (CuFeS ₂ ) and concentrating the copper content to an appropriate grade,
1) A method of leaching sulfuric acid in the coexistence of Fe (trivalent) while blowing oxygen or air as an oxidizing agent at a temperature of 80 to 100 ° C. while secondary grinding to 10 μm or less 2) Pressurization There is a method of leaching sulfuric acid at a temperature of 130 to 230 ° C., which has been put into practical use in recent years. In addition, a process has been proposed in which chalcopyrite is roasted in an inert atmosphere, mineralized into copper indigo (CuS) and pyroxenite (Cu ₂ S), and leached, but due to cost problems, There are few examples.

On the other hand, copper ores containing a large amount of arsenic are generally low-arsenic grade copper concentrates at the beneficiation stage at a high cost, but are treated as high arsenic grade copper concentrates or at the beneficiation stage. There are also attempts to process high-arsenic concentrates that have been removed. For example,
1) Oxidation roasting and making leaching easy (leaching copper oxide, copper sulphate) 2) Method of leaching 2) Drying roasting in an inert atmosphere and removing arsenic as arsenic sulfide There are methods for processing. In the method 1), since arsenic is volatilized with highly toxic arsenous acid, there are many problems in its treatment, and there are few examples. The method 2) is a pretreatment for dry smelting and has no effect such as a reduction in the cost of transporting copper concentrate to a distant location.

Arsenic contained in copper ore is mainly contained in the form of copper arsenite (Cu ₃ AsS ₄ ), is a hardly leachable mineral that has a dense molecular structure and is difficult for the leachate to diffuse. Although a process has been proposed, there are problems such as cost, and there are very few examples.

In US Pat. No. 5,993,635 (Patent Document 1), a copper concentrate after flotation treatment is used with a solution of Fe (trivalent) = 30 g / liter, H ₂ SO ₄ = 50 g / liter, and a pulp concentration of 10 %, A method of leaching copper at a temperature of 90 ° C. is shown. The leaching time is 10 hours for oxygen gas blowing and 14 hours for air blowing. This method is characterized in that a hardly leachable mineral is pulverized to a particle size of 5 μm or less before leaching.

In the examples in this patent document, two examples of leaching of copper concentrate containing arsenite are described. In the first example, Cu concentrate is composed of Cu = 19.5 mass%, As = 4.0 mass%, Fe = 23 mass% (arsenite ore 20.9 mass%, chalcocite 11.9 mass%, pyrite 50 mass%. ) Is finely pulverized to 80% passing particle diameter = 3.5 μm and processed by the above leaching method. In the second example, Cu concentrate of Cu = 8.1 mass%, As = 0.2 mass%, Fe = 13 mass% (1.3 mass% of pyrite, 9.4 mass% of chalcopyrite, 29.6 mass% of pyrite, and the rest As a result of pulverizing to 80% passing particle size = 5 μm and treating by the above leaching method, a copper leaching rate of 95% is obtained.

In both cases, the copper leaching rate is 90% or more, but as can be seen from these comparisons, the copper leaching rate decreases as the abundance ratio of arsenite is increased. Moreover, in order to supplement it, the copper concentrate particle | grain is further grind | pulverized rather than 5 micrometers. That is, in this method, the cost for pulverizing to fine particles is required, and in addition, the leaching rate is reduced in copper concentrate mainly composed of arsenite.

US Pat. No. 5,993,635

The present invention solves the above-mentioned problems, and an object of the present invention is to provide a method for efficiently and economically recovering copper from arsenite or copper concentrate mainly composed of arsenite.

The copper concentrate treatment method according to the present invention comprises a roasting step of roasting copper concentrate mainly composed of arsenous copper ore (Cu ₃ AsS ₄ ) or arsenous copper ore at 550 ° C. to 700 ° C. in an inert gas atmosphere. And a leaching step of leaching copper using the chloride leaching method in which an oxidizing agent containing Cu (divalent) and Fe (trivalent) is added to the chalcopyrite-based sinter obtained in the roasting step; , Including. According to the copper concentrate processing method according to the present invention, copper can be efficiently and economically recovered from arsenite or copper concentrate mainly composed of arsenite.

In the roasting step, a sulfur source may be added. In the leaching step, oxidation treatment may be performed using oxygen gas or air. In the leaching step, the temperature of the leaching solution may be adjusted to 70 ° C. to 90 ° C. In the leaching step, the concentration of Cl in the leachate may be adjusted to a concentration of 80 g / liter to 180 g / liter. In the leaching step, Fe (trivalent) may be adjusted from 1 g / liter to 3 g / liter, and Cu (divalent) may be adjusted from 10 g / liter to 25 g / liter.

According to the present invention, copper can be efficiently and economically recovered from arsenite or copper concentrate mainly composed of arsenite.

The processing flow which is 1 aspect of this invention is shown. The copper concentrate XRD analysis result before roasting which is one mode in the present invention is shown. The copper concentrate XRD analysis result after 550 degreeC roasting which is one aspect | mode in this invention is shown. The copper concentrate XRD analysis result after 600 degreeC roasting which is one aspect | mode in this invention is shown. The copper leaching rate in the chloride leaching method of the copper concentrate after roasting which is one aspect of the present invention is shown. The copper leaching rate in the chloride leaching method of the copper concentrate before roasting which is a comparative example in the present invention is shown.

Hereafter, this research will be explained in more detail by examples.

In the present invention, copper concentrate mainly composed of arsenous pyrite (Cu ₃ AsS ₄ ) or arsenous copper ore is roasted in an inert atmosphere, and volatiles mainly composed of arsenic sulfide and sintered mainly composed of chalcopyrite. An object is to provide a method for efficiently and economically recovering calcination ore by wet processing.

The target processed product of the present invention is copper concentrate. In particular, it is a copper concentrate containing a large amount of arsenic, mainly composed of arsenite. The grade of copper concentrate mainly composed of arsenite contains 15 to 35 mass% copper and 5 to 15 mass% arsenic depending on the amount of pyrite (FeS ₂ ) and gangue components. In the present invention, the copper concentrate is pre-dried at a temperature at which the mineral species and quality do not change. Usually, when drying with high-temperature air, the temperature of the copper concentrate at the outlet of the dryer is about 90 ° C., and the moisture content of the copper concentrate is 0.5% or less.

The dried copper concentrate is heated at 550 to 700 ° C. for 10 to 60 minutes in an inert atmosphere (roasting step). Nitrogen gas is mainly used as the inert gas. These temperatures and atmospheres are the conditions necessary for converting copper concentrate mainly composed of arsenite ore to arsenic sulfide and chalcopyrite, etc., and the reaction time is the time required to leave no unreacted arsenite. It is. As for the balance of arsenic and sulfur, if the original concentrate contains a lot of pyrite, etc., S in the formula (1) is as shown in the reaction formula of (2). Since it is compensated by the generated S, it becomes unnecessary.
4Cu ₃ AsS ₄ + 12FeS ₂ + 2S → 12CuFeS ₂ + As ₄ S ₆ (1)
FeS ₂ → FeS + S (2)
However, if the copper concentrate is deficient in sulfur relative to arsenic, it is necessary to supplement the deficiency by adding a sulfur source. Thereby, preferable arsenic removal is possible in advance. The preferred arsenic grade of the concentrate after roasting is 1.0 mass% or less, more preferably 0.5 mass% or less.

The roasting process is performed using a rotary kiln or the like. As a result of the above reaction treatment, it is divided into calcined mainly composed of chalcopyrite and arsenic sulfide and elemental sulfur recovered by volatilization.

In the form of copper arsenite, efficient leaching is impossible even if it is subjected to the chloride leaching method, high-temperature pressurized sulfuric acid leaching method, etc., but after the above treatment, the recovered calcined ore is copper mainly composed of chalcopyrite. It can be used as it is for a wet process including these methods capable of leaching the concentrate.

As a result of inventing the copper concentrate mainly composed of arsenite before roasting by the chloride leaching method using the oxidizing power of Fe (trivalent) and Cu (divalent), the inventor found that the copper leaching rate was 51%. However, as a result of leaching the copper concentrate after roasting under the same conditions, the copper leaching rate dramatically increased to 90%. The concentrations of Fe (trivalent) and Cu (divalent) at this time are adjusted, for example, from 1 g / liter to 3 g / liter for Fe (trivalent) and 10 g / liter for Cu (divalent). Adjust to 1 to 25 g / liter. For this purpose, for example, CuCl ₂ · 2H ₂ O is added at 67 to 135 g / liter and FeCl ₃ at 7 to 20 g / liter, but the addition amount is the copper content of the treated copper concentrate, iron It changes according to the amount (pyrite amount). Also, an oxygen-containing gas is blown for iron oxidation. For example, oxygen gas, air, oxygen gas enriched air. For example, in the case of air, 1 to 4 liters / minute is blown. For example, the roasted ore after the roasting is adjusted to be 50 g / liter to 200 g / liter, and the oxidative leaching treatment is performed. Further, the chloride leaching solution is used for the leaching after adjusting the Cl concentration from 80 g / liter to 180 g / liter. Chlorine is added with, for example, NaCl to adjust the Cl concentration. Further, the leaching temperature is preferably 70 ° C to 90 ° C. This is because leaching is preferably performed.

In the roasting process described above, the volatilized arsenic sulfide and the simple substance S are separated from the exhaust gas, and are disposed or stored in a more stable form as necessary. For example, condensers, electrostatic precipitators, washing towers, etc. are used for volatiles recovery.In addition to arsenic sulfide, arsenous acid, and elemental sulfur, in order to separate and recover entrained sinter, in addition to a combination of these devices, If necessary, adiabatic cooling is performed by introducing diluted air or increasing the humidity. Further, since a part of sulfur becomes sulfurous acid gas due to a small amount of oxygen contained in the nitrogen gas or air slightly entering the apparatus, a desulfurization facility is provided if necessary.

Example 1
FIG. 1 shows a processing flow of copper concentrate mainly composed of arsenite. Copper concentrate mainly composed of copper arsenite (Cu grade = 24 mass%, Fe grade = 23 mass%, As grade = 9 mass%, S grade = 39 mass%) after drying at 90 ° C. for 10 hours, at 550 ° C. for 60 minutes, inert atmosphere The calcined mainly composed of chalcopyrite was obtained. Table 1 shows the grades of copper concentrate Cu, Fe, As, and S before and after the treatment, and the weight ratio after the conversion when the value before the conversion is 100. The copper concentrate had a particle size of 40 to 100 μm because fine pulverization was not performed. FIG. 2 is an XRD analysis result of the (original) copper concentrate before roasting. FIG. 3 is an XRD analysis result of the copper concentrate after roasting at 550 ° C.

According to Table 1 and FIG. 2, the concentrate before roasting is almost composed of arsenite and pyrite, and the molar ratio is arsenite: pyrite = 1: 3.5.

According to Table 1 and Fig. 3, most of the concentrate after roasting is converted to chalcopyrite, partly tetrahedral arsenite (Cu ₁₂ As ₄ S ₁₃ ) generated during the decomposition process of arsenite, unreacted pyrite and became. This reaction basically follows the reaction formula (1).
4Cu ₃ AsS ₄ + 12FeS ₂ + 2S → 12CuFeS ₂ + As ₄ S ₆ (1)
If the pyrite contains a lot of pyrite, the S in the formula (1) is compensated by the generated S due to the decomposition of the pyrite in the test temperature zone as in the reaction formula (2). It becomes unnecessary.
FeS ₂ → FeS + S (2)
In Example 1, since sulfur addition was not performed before baking, sulfur content is insufficient. In this case, the reaction is as shown in the following equation (3).
4Cu ₃ AsS ₄ → 6Cu ₂ S + As ₄ S ₆ (3)
Since a higher temperature is required for the reaction of (3) to proceed, in Example 1, it can be determined that even with a reaction time of 60 minutes, it cannot be completely converted to chalcopyrite. .

The calcined ore obtained after roasting was treated at 80 ° C. using the chloride leaching method. The leaching test used in this leaching test was a chloride leaching solution based on Cl = 180 g / liter, and Cu (divalent) = 18 g / liter and Fe (trivalent) = 2 g / liter as an oxidizing agent for copper. It is added. Prepare 2.5 liters of this in a 3 liter beaker, add the roasted ore to this so that the pulp concentration is 90 g / liter, and stir while blowing air at 2.5 liters / minute, The copper leaching rate was confirmed. The leaching operation was carried out in four stages. The first stage and the second stage are leaching time of 3 hours each, the third stage and the fourth stage are leaching time of 5 hours each, the first stage is leaching of the sinter itself, and the second and subsequent stages are in the previous stage leaching, respectively. The residue obtained by filtration was treated with a new leachate having the above composition.

FIG. 5 shows the leaching rate of copper when the sinter after 550 ° C. roasting is leached by the above-described chloride leaching method. Finally, a copper leach rate of 72% was obtained. Further, as in Patent Document 1, arsenic can be removed in advance without finely pulverizing copper concentrate, and copper can also be leached.

(Example 2)
Table 2 shows analytical values of the calcined ore obtained by treating the copper ore based mainly on the arsenous copper ore used in Example 1 under the same roasting conditions and changing the temperature only to 600 ° C. FIG. 4 is an XRD analysis result of the copper concentrate after roasting at 600 ° C.

According to Table 2 and FIG. 4, further arsenic removal from the arsenite and ore conversion and ore conversion proceed, and it is understood that most of the copper-iron sulfide is chalcopyrite or Cubanite (CuFe ₂ S ₃ ). . Some copper seems to be chalcocite. Moreover, since the peak of pyrite cannot be confirmed, it is judged that the reaction is almost completed.

FIG. 5 shows the leaching rate of copper when the calcination after 600 ° C. roasting is leached by the above-mentioned chlorination advance method together with the leaching result of the 550 ° C. roasting treatment calcination. Finally, the copper leaching rate was 91%, and a high leaching rate was obtained as compared with the result of 550 ° C. sinter. Also, 96% of arsenic could be removed to the exhaust gas system, and the copper leaching process was performed efficiently. Furthermore, as in Patent Document 1, arsenic could be removed in advance without finely pulverizing the copper concentrate, and copper could be leached.

(Comparative example)
For comparison with the copper leaching rate in Example 1 and Example 2, the leaching rate of copper in the case of leaching the original concentrate mainly composed of arsenite ore without roasting treatment as it is is shown in FIG. Show. The leaching rate is slow and the final leaching rate is only 52%. In other words, it was confirmed that by roasting treatment, arsenous oresite which is hardly leachable can be treated without problems in practice under various conditions such as leaching time and temperature.

Claims (6)

A roasting step of roasting copper concentrate mainly composed of arsenous pyrite (Cu ₃ AsS ₄ ) or arsenous pyrite at 550 ° C. to 700 ° C. in an inert gas atmosphere;
A leaching step of leaching copper using a chloride leaching method in which an oxidizing agent containing Cu (divalent) and Fe (trivalent) is added to the chalcopyrite-based sinter obtained in the roasting step; A method for treating copper concentrate, comprising: The method for treating copper concentrate according to claim 1, wherein a sulfur source is added in the roasting step. The method for treating copper concentrate according to claim 1 or 2, wherein in the leaching step, oxidation treatment is performed using oxygen gas or air. The copper concentrate treatment method according to any one of claims 1 to 3, wherein in the leaching step, the temperature of the leaching solution is adjusted to 70 ° C to 90 ° C. The method for treating copper concentrate according to any one of claims 1 to 4, wherein in the leaching step, the Cl concentration of the leachate is adjusted to a concentration of 80 g / liter to 180 g / liter. 6. In the leaching step, Fe (trivalent) is adjusted from 1 g / liter to 3 g / liter, and Cu (divalent) is adjusted from 10 g / liter to 25 g / liter. The processing method of the copper concentrate of description.

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