Copper concentrate processing method

Abstract

Provided is a copper concentrate processing method by which arsenic can be removed from copper concentrate conveniently and safely.　The present invention provides a copper concentrate processing method for removing arsenic in a copper concentrate, comprising: Step 1 of roasting the copper concentrate in the presence of a non-oxidizing gas in a temperature range of at least 707°C and lower than 1130°C to obtain As2S3 in a gas phase; and Step 2 of liquefying As2S3 in the gas phase in Step 1 in a temperature range of at least 445°C and lower than 707°C to obtain As2S3 in a liquid phase. The copper concentrate processing method according to the present invention makes it possible to remove arsenic from copper concentrate conveniently and safely.

Description

Copper concentrate processing method

[0001] The present invention relates to a method for treating copper concentrate.

[0002] Japan's annual copper concentrate consumption is said to be 4.5 million tons, but the grade of copper concentrate is declining, and the amount of slag generated during the smelting process is increasing, putting a strain on the production capacity of smelting furnaces. In recent years, the arsenic content of copper concentrate has been reduced to 0.12%, resulting in the amount of arsenic brought into Japan reaching approximately 5,000 tons per year. Traditionally, arsenic was detoxified and then mixed with granulated slag for distribution, but in recent years, there is a risk that the arsenic concentration may exceed the upper limit, calling for drastic measures (see, for example, Non-Patent Document 1).

[0003] As an example of a method for removing arsenic from copper ore, the so-called chloride leaching method is known, in which copper ore is roasted in an inert gas atmosphere at a temperature range of 550°C to 700°C, arsenic sulfide is liquefied and removed, and then an oxidizing agent containing divalent Cu and trivalent Fe is added to the roasted ore. Arsenic contained in copper ore is mainly Cu. ３ AsS ４ The copper ore is contained in this form, and its dense molecular structure makes it difficult for the leachate to diffuse through. However, in the chloride leaching method, the copper ore is roasted to remove the arsenic, which converts it into a porous material, making it easier for the chloride leachate to penetrate.

[0004] Junichi Takahashi, Materia, Vol. 58, No. 10 (2019), pp. 548-552

[0005] However, in the chloride leaching method, arsenic sulfide is removed in a crystalline state, so if it is stored for a long period of time, it will be oxidized by oxygen in the atmosphere and become highly toxic As. ２ O ３ In addition, it is difficult to effectively utilize the removed crystalline arsenic sulfide. ２ O ３ As such, ２ O ３ Arsenic is highly water-soluble and easily becomes toxic. Therefore, when arsenic is oxidized, it becomes difficult to store it, which can be a problem.

[0006] From this perspective, there is a strong demand for the development of technology to render harmless or effectively utilize the arsenic contained in copper concentrate, and such technological development is expected to open the way for its use in new industrial products.

[0007] The present invention has been made in view of the above, and an object of the present invention is to provide a method for treating copper concentrate that enables arsenic to be removed from copper concentrate simply and safely.

[0008] As a result of extensive research to achieve the above object, the present inventors have discovered that As recovered by roasting copper concentrate ２ S ３ The present inventors have found that the above object can be achieved by vitrifying the above-mentioned compound, and have thus completed the present invention.

[0009] That is, the present invention includes, for example, the subject matter described in the following items. Item 1 is a method for treating copper concentrate to remove arsenic from the copper concentrate, comprising roasting the copper concentrate in the presence of a non-oxidizing gas at a temperature range of 707°C or higher and lower than 1130°C to remove gaseous As. ２ S ３ Step 1 to obtain As in the gas phase in the step 1 ２ S ３ is liquefied in a temperature range of 445°C or higher and lower than 707°C to obtain liquid As ２ S ３ Item 2: A method for treating copper concentrate, comprising: a step 2 for obtaining As in the liquid phase obtained in the step 2. ２ S ３ is rapidly cooled to form a glass. ２ S ３ Item 3. The method for treating copper concentrate according to Item 1, further comprising step 3 of obtaining a non-oxidizing gas. ２ Item 4: The method for treating copper concentrate according to Item 1 or 2, wherein the non-oxidizing gas is SO 2 generated in the roasting step of the step 1. ２ Item 5: The method for treating copper concentrate according to any one of Items 1 to 3, wherein the liquid phase As ２ S ３Item 6. The copper concentrate treatment method according to any one of Items 1 to 4, further comprising a step 4 of recovering the non-oxidizing gas after obtaining the SO 3 and maintaining the non-oxidizing gas at a temperature of 115.2°C or higher and lower than 360°C to recover liquid-phase S. Item 7. The copper concentrate treatment method according to Item 5, further comprising cooling the liquid-phase S obtained in step 4 to a temperature lower than 115.2°C to solidify it, thereby recovering solid-phase S. Item 8. The copper concentrate treatment method according to Item 5, further comprising: ２ Item 8: The copper concentrate treatment method according to Item 3 or 4, wherein the copper concentrate is recovered and used in a step for producing sulfuric acid. ２ S ３ Item 2. The method for treating copper concentrate according to Item 2, wherein the non-oxidizing gas is recovered after the S is recovered and reused in the roasting in step 1. Item 9. The method for treating copper concentrate according to Item 5, wherein the non-oxidizing gas after the S is recovered is recovered and reused in the roasting in step 1. Item 10. The method for treating copper concentrate according to Item 6, wherein the non-oxidizing gas after the S is recovered is recovered and reused in the roasting in step 1.

[0010] The copper concentrate treatment method of the present invention makes it possible to remove arsenic from copper concentrate in a simple and safe manner.

[0011] 1 is a schematic explanatory diagram showing one embodiment of a rotary kiln that can be used in the copper concentrate processing method of the present invention. 2 is a schematic explanatory diagram showing an apparatus used in the copper concentrate processing method of Example 1.

[0012]

[0023] In the present specification, the terms "contain" and "comprise" include the concepts of "contain," "comprise," "consist essentially of," and "consist only of."

[0013] The present invention provides a method for treating copper concentrate to remove arsenic from the copper concentrate, and includes at least the following steps 1 and 2: Step 1: Roasting copper concentrate in the presence of a non-oxidizing gas at a temperature range of 707°C or higher and lower than 1130°C to remove gaseous As. ２ S ３ Step 2: obtaining the gas phase As in step 1; ２ S ３ is liquefied in a temperature range of 445°C or higher and lower than 707°C to obtain liquid As ２ S ３The process of obtaining the above.

[0014] The copper concentrate treatment method of the present invention makes it possible to easily and safely remove arsenic from copper concentrate. In particular, according to the copper concentrate treatment method of the present invention, arsenic in the copper concentrate is converted into vitrified As ２ S ３ This allows the arsenic in copper concentrate to be easily neutralized and removed.

[0015] (Step 1) Step 1 is a step for roasting copper concentrate. The type of copper concentrate used in step 1 is not particularly limited, and for example, a wide range of known copper concentrates can be used. The apparent specific gravity of the copper concentrate depends on the water content, but is, for example, 1.0 to 1.9 t / m ３ The copper concentrate used in step 1 is preferably in the form of a powder, and the particle size thereof may be, for example, about 5 to 100 μm.

[0016] The copper concentrate used in step 1 may be dried in advance as needed. Here, the components contained in the copper concentrate include CuS, FeS, As, ２ S ３ , Sb ２ S ３ , B ２ S ３ , Bi ２ S ３ Among these components, CuS decomposes at temperatures above 220°C to form Cu. ２ Since S and S are generated, the drying temperature is desirably in the range of less than 220°C. Preferably, the drying process is carried out at 100°C or higher, which is the temperature at which water evaporates. In any case, it is preferable that the drying process of copper concentrate removes moisture from the copper concentrate while controlling the temperature below the decomposition temperature of CuS. The drying temperature is more preferably 120°C or higher, even more preferably 150°C or higher, particularly preferably 160°C or higher, and more preferably 200°C or lower.

[0017] The roasting of copper concentrate in step 1 is carried out in a non-oxidizing gas. In the present invention, the non-oxidizing gas is a gas containing As, which is the target recovered product. ２ S ３By using such a non-oxidizing gas, As ２ S ３ Since the sulfur generated by the decomposition of CuS is evaporated and mixed into the non-oxidizing gas, the copper concentrate can be treated as powder, which has the advantage that a separate process for treating the sulfur in the copper concentrate is not required.

[0018] The non-oxidizing gases used in step 1 include rare gases such as argon and nitrogen, as well as hydrocarbons, CO, hydrogen, SO ２ The non-oxidizing gas used in step 1 may be a rare gas and / or SO . ２ In this case, as will be described later, SO ２ This is because the above-mentioned can also be used as a heat source in step 1.

[0019] As described above, the roasting temperature in step 1 is 707°C or higher and lower than 1130°C. ２ S ３ The melting point of As is 310°C and the boiling point is 707°C. Therefore, by setting the roasting temperature at 707°C or higher, the arsenic component in the copper concentrate can be converted to As ２ S ３ That is, when the roasting temperature in step 1 is less than 707°C, As ２ S ３ Since the gas cannot be vaporized, the desired recovery cannot be achieved.

[0020] When the roasting temperature in step 1 is 1130°C or higher, the Cu generated by the decomposition of CuS described above is ２ Since the melting point of S is exceeded, for example, liquid phase Cu ２ This is undesirable because it may generate sulfur, which may cause the copper concentrate fine powder to become agglomerated, causing problems in the equipment, etc.

[0021] Of the above-mentioned components contained in copper concentrate, the sublimation point of ZnS is 1180°C, ２ S ３ The boiling point of As is 707°C and the boiling point of S is 444.6°C. Therefore, if the roasting temperature is higher than 707°C and lower than 1180°C, As ２ S ３and S are evaporated and mixed into the non-oxidizing gas.

[0022] The roasting temperature in step 1 is preferably 720°C or higher, more preferably 730°C or higher, and even more preferably 740°C or higher, and is preferably 900°C or lower, more preferably 850°C or lower, further preferably 800°C or lower, and particularly preferably 770°C or lower.

[0023] In the roasting in step 1, the heat source is not particularly limited, and a wide range of known heat sources can be used. ２ It is preferable to utilize the sensible heat of SO ２ can easily provide heat of about 1200°C, and therefore has sufficient heat to heat copper concentrate to over 707°C. ２ When sensible heat is utilized, it becomes easier to control the roasting temperature.

[0024] SO ２ is the SO contained in the non-oxidizing gas mentioned above. ２ Among them, high temperature SO generated in the oxidation smelting furnace of copper concentrate can be used. ２ Of course, it is preferable to use SO ２ is not limited to that generated in copper concentrate smelting furnaces, and SO ２ It is also possible to prepare

[0025] There are no particular limitations on the apparatus used in the roasting in step 1. For example, a wide range of known roasting furnaces used in conventional roasting can be used in the present invention. Examples of methods for roasting in a roasting furnace include a method in which copper concentrate is heated at a predetermined temperature in a non-oxidizing gas.

[0026] Therefore, examples of roasting methods include using a fluidized bed bottle to charge copper concentrate from above while injecting a non-oxidizing gas from below, or passing the concentrate through heated metals. Examples of heating methods include indirect heating, in which copper concentrate is brought into contact with an object heated to a high temperature, and direct contact of a hot non-oxidizing gas with the copper concentrate. It is preferable that the non-oxidizing gas used in step 1 is recovered and recycled, or that the non-oxidizing gas itself is effectively utilized. From this perspective, using a rotary kiln as a roasting furnace is a preferred embodiment. The method of using a rotary kiln as a roasting furnace will be described later (see FIG. 1, etc.).

[0027] In the above step 1, the copper concentrate is roasted, and the roasting generates gaseous As ２ S ３ The resulting gas phase As ２ S ３ is subjected to the next step 2. ２ S ３ is contained in the non-oxidizing gas, and therefore, such non-oxidizing gas may be subjected to the next step 2.

[0028] The roasted copper concentrate is preferably stored, for example, under a nitrogen atmosphere. The roasted copper concentrate can be stored in an appropriate container, for example, in a recovery tank provided in a rotary kiln described below. The roasted copper concentrate may be smelted by an appropriate method.

[0029] (Step 2) Step 2 is a step of converting the gas phase As ２ S ３ is liquefied in a temperature range of 445°C or higher and lower than 707°C to obtain liquid As ２ S ３ This is a process for obtaining the above.

[0030] In step 2, the non-oxidizing gas used in the roasting in step 1 is recovered and supplied to a liquefaction furnace. ２ S ３ Contains:

[0031] When the non-oxidizing gas is supplied to the liquefaction furnace, the non-oxidizing gas is supplied to the liquefaction furnace while being maintained at a temperature of 707°C or higher and lower than 1130°C, which is the roasting temperature.

[0032] Therefore, in the above-mentioned step 1, the non-oxidizing gas is maintained at a temperature of 707° C. or higher, whereas in step 2, the non-oxidizing gas is cooled to a temperature range of 445° C. or higher and lower than 707° C. This cooling treatment reduces the As in the gas phase contained in the non-oxidizing gas. ２ S ３ is liquefied, and the liquid phase As ２ S ３ can be obtained.

[0033] The non-oxidizing gas supplied from step 1 contains As, which has a melting point of 310°C and a boiling point of 707°C. ２ S ３ As and S, which have a melting point of 115.2°C and a boiling point of 444.6°C, coexist in the non-oxidizing gas. Therefore, when the non-oxidizing gas is cooled to a temperature range of 445°C or higher and lower than 707°C, liquid phase As is released from the non-oxidizing gas. ２ S ３ is separated, while S remains as a vapor. ２ S ３ On the other hand, the vapor (non-oxidizing gas) containing residual S can be subjected to the next step 3 as needed. ２ S ３ Alternatively, it can be directly subjected to step 4 described below.

[0034] The temperature of the cooling treatment in step 2 is preferably 450°C or higher, more preferably 460°C or higher, even more preferably 470°C or higher, and particularly preferably 480°C or higher, and is preferably 650°C or lower, more preferably 600°C or lower, even more preferably 550°C or lower, and particularly preferably 510°C or lower.

[0035] The cooling treatment in step 2 can be carried out, for example, in a liquefaction furnace. The type of liquefaction furnace is not particularly limited, and a wide range of known liquefaction furnaces can be used.

[0036] (Step 3) The copper concentrate treatment method of the present invention preferably includes the following step 3 in addition to the above steps 1 and 2. Step 3: Removing the As from the liquid phase obtained in the step 2. ２ S ３ is rapidly cooled to form a glass. ２ S ３ The process of obtaining the above.

[0037] In step 3, the liquid phase As obtained in step 2 is ２ S ３ is rapidly cooled to form a glass. ２ S ３ For example, the liquid phase As obtained in step 2 can be obtained. ２ S ３ can be subjected to step 3, or the liquid phase As obtained in step 2 ２ S ３ can be subjected to step 3 together with fresh non-oxidizing gas.

[0038] Liquid phase As obtained in step 2 ２ S ３ is the liquid phase As ２ S ３ The mixture is subjected to step 3 while being maintained at 310°C or higher, which is the melting point of As, and then rapidly cooled. ２ S ３ is maintained at 350±30°C and subjected to step 3.

[0039] In step 3, liquid phase As ２ S ３ The method for cooling is not particularly limited, and for example, ２ S ３ One method is to pour the mixture into the gap between a pair of rotating water-cooled metal rolls and rapidly cool it. ２ S ３ It is preferable that a large number of protrusions (for example, protrusions with a height of about 1 mm) are provided on the surface of the rotating water-cooled metal roll. In this case, the vitrified As solidified between the metal rolls is ２ S ３ The gap between the pair of rotating water-cooled metal rolls can be maintained at, for example, about 3 mm.

[0040] The rapid cooling temperature in step 3 is not particularly limited, and is, for example, 300°C or less, preferably 200°C or less, more preferably 100°C or less, even more preferably 80°C or less, and particularly preferably 40°C or less.

[0041] The rapid cooling in step 3 can be carried out in the presence of a non-oxidizing gas. In this case, the non-oxidizing gas that was present in step 2 can be continued to be used as the non-oxidizing gas. Alternatively, the rapid cooling in step 3 can be carried out in the presence of a new non-oxidizing gas.

[0042] In addition, in step 3, vitrified As ２ S ３ After obtaining the non-oxidizing gas, the non-oxidizing gas can be recovered and reused in the roasting in step 1. In this case, S in the non-oxidizing gas can be recovered in step 4 described later and then reused in the roasting in step 1, or the non-oxidizing gas can be reused in the roasting in step 1 without going through step 4.

[0043] By going through the above steps 1, 2 and optionally included step 3, arsenic in the copper concentrate is vitrified into As ２ S ３ In addition, arsenic in copper concentrate can also be recovered as tetraarsenic tetrasulfide, tetraarsenic trisulfide, diarsenic pentasulfide, and tetraarsenic pentasulfide. Most of the arsenic in copper concentrate is recovered as vitrified As ２ S ３ can be recovered as

[0044] By the copper concentrate processing method of the present invention, 50 mass% or more of the arsenic in the raw copper concentrate can be removed, preferably 60 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more of the arsenic can be removed.

[0045] (Other Steps) The copper concentrate processing method of the present invention may include other steps in addition to the above-described steps 1, 2 and 3.

[0046] For example, the copper concentrate treatment method of the present invention may further include the following step 4: Step 4: Adding As in step 2 to the liquid phase ２ S ３and recovering the non-oxidizing gas after obtaining the above-mentioned product, and maintaining the non-oxidizing gas at a temperature in the range of 115.2°C or higher and lower than 360°C to recover liquid-phase S.

[0047] That is, step 4 is a step for recovering S from the non-oxidizing gas used in step 2 or step 3. ２ S ３ In the non-oxidizing gas after separation of SO, S vapor may be present. ２ When the non-oxidizing gas contains sulfur, the non-oxidizing gas is likely to contain sulfur vapor and may also contain a small amount of nitrogen.

[0048] Here, the boiling point of S is 444.6°C and the melting point is 115.2°C. Therefore, in step 2, the liquid phase As ２ S ３ The non-oxidizing gas obtained after the separation of sulfur is recovered and treated at a temperature in the range of 115.2°C or higher and lower than 360°C, whereby the liquid phase sulfur can be recovered.

[0049] The method for recovering S is not particularly limited. For example, S may be recovered by recovering the non-oxidizing gas used in step 2 in an appropriate container and maintaining it at a predetermined temperature.

[0050] Solid-phase S can also be recovered by cooling the liquid-phase S obtained in step 4 to a temperature range of less than 115.2°C to solidify it. For example, solid-phase S can be recovered by cooling the liquid-phase S recovered in step 4 in a water-cooled furnace at a temperature of less than 115.2°C. The cooling temperature is not particularly limited as long as it is less than 115.2°C, and can be appropriately determined depending on the application of the recovered S and ease of handling, and can be, for example, 100°C or lower.

[0051] The non-oxidizing gas after removing S is SO ２ Since the collected SO may contain SO , it can be collected by an appropriate suction means such as a suction fan. For example, the collected SO ２ can be supplied to a process for producing sulfuric acid. That is, in the copper concentrate treatment method of the present invention, ２ can also be recovered and used in a process to produce sulfuric acid. ２When collecting SO ２ The pressure must be negative to prevent air from being sucked in, and high to prevent SO ２ The pressure can be controlled to prevent the gas from spraying out.

[0052] (Apparatus) In the copper concentrate treatment method of the present invention, the apparatus used is not particularly limited as long as it includes at least the above steps 1, 2, and 3. For example, a wide variety of known apparatuses can be used in the present invention. A rotary kiln can be used as one embodiment of an apparatus that can be used in the copper concentrate treatment method of the present invention. A rotary kiln is an apparatus that is used in the drying treatment of copper concentrate, and can be preferably used in the copper concentrate treatment method of the present invention.

[0053] Fig. 1 is a schematic diagram showing one embodiment of a rotary kiln that can be used in the copper concentrate processing method of the present invention. As shown in Fig. 1, the rotary kiln L has a slope from one end (upper part of the apparatus) to the other end (lower part of the apparatus).

[0054] The upper part of the device is equipped with a raw material tank 1 for storing copper concentrate R as the raw material, and the lower part is equipped with a vitrified As ２ S ３ The apparatus is provided with a recovery tank 2 for recovering the copper concentrate T after the separation.

[0055] When a rotary kiln is used, dried copper concentrate is placed in a raw material tank 1 and discharged from the raw material tank 1 into the treatment space 3 of the rotary kiln L. The temperature of the treatment space 3 can be maintained at a desired roasting temperature by an appropriate method. In particular, SO 4 is used as a heat source for the rotary kiln L. ２ It is preferable to use the sensible heat of the non-oxidizing gas. ２ Hereinafter, the non-oxidizing gas will be referred to as SO ２ The case where the following is used will be described as an example.

[0056] The material of the inside of the treatment space 3 is not particularly limited, but it is preferable to select, for example, an abrasion-resistant material that can withstand abrasion caused by the copper concentrate. Sialon can be attached to areas where the copper concentrate collides and is subject to severe abrasion. Alternatively, a stainless steel plate or a heat-resistant steel plate can be used as the inside material, which will simplify the structure.

[0057] Here, the stainless steel sheet referred to in this specification can include various stainless steel sheets listed in JIS G0203 (2009), such as stainless steel, austenitic stainless steel, ferritic stainless steel, austenitic-ferritic stainless steel, precipitation hardened stainless steel, low-carbon stainless steel, stabilized stainless steel, free-cutting stainless steel, and painted stainless steel.

[0058] The heat-resistant steel plate referred to in this specification may include various heat-resistant steel plates listed in JIS G0203 (2009), such as heat-resistant steel, martensitic heat-resistant steel, ferritic heat-resistant steel, austenitic heat-resistant steel, and precipitation-hardened heat-resistant steel.

[0059] It is preferable that spiral protrusions are formed on the wall surface of the treatment space 3, which makes it easier for the copper concentrate to flow down as the rotary kiln rotates.

[0060] The outermost part of the rotary kiln L can be covered with a steel shell made of thick structural steel plates, and a heat insulating refractory material 4 can be placed between the steel shell and the internal wear-resistant tube. ２ This allows the amount of material used to be minimized, and also makes it possible to suppress heat dissipation.

[0061] The rotary kiln L is rotatably configured. As the rotary kiln L rotates, the copper concentrate moves downward along the inclination of the rotary kiln L.

[0062] A charging pipe 1a is connected to the raw material tank 1 above the rotary kiln L, and copper concentrate is introduced into the treatment space 3 through this charging pipe 1a. The charging pipe 1a can be made of, for example, a heat-resistant and abrasion-resistant material. It is preferable to fix the charging pipe 1a so that the central axis of the charging pipe 1a and the central axis of the rotary kiln L coincide with each other.

[0063] The outer wall of the charging pipe 1a and the outer wall of the rotary kiln L are sealed by a rotary joint. Copper concentrate is charged from the top of the charging pipe 1a. A sloped space is provided inside the fixed charging pipe 1a to allow the copper concentrate to slide naturally, and the copper concentrate slides down the sloped space and is charged into the treatment space 3 inside the rotary kiln L. This creates a region near the top of the charging pipe 1a where the copper concentrate does not pass. This region is filled with high-temperature (for example, about 1200°C) non-oxidizing gas (SO ２ An outlet of the blowing pipe 1b is opened to the inside of the rotary kiln L (treatment space 3) to blow in SO ２ The structure allows for the injection of

[0064] The blowing pipe 1b is bent so that the tip of the outlet side is positioned above the treatment space 3. This allows the inner wall of the rotary kiln L to be ２ can be sprayed, and SO ２ As a result, the copper concentrate that has flowed into the treatment space 3 is heated (roasted) at a predetermined temperature and flows along the inner wall below the rotary kiln L toward the recovery tank 2. ２ This prevents the copper concentrate from being directly hit by the particles, thereby reducing the amount of Cu in the copper concentrate. ２ This can prevent S from melting and forming lumps.

[0065] The outlet side of the rotary kiln L can have the same structure as the inlet side. For example, a discharge pipe 2a connecting to the recovery tank 2 can be provided at the bottom of the rotary kiln L. The discharge pipe 2a can be made of, for example, a heat-resistant and abrasion-resistant material, and is preferably fixed so that the central axis of the discharge pipe 2a coincides with that of the rotary kiln L. The outer wall of the discharge pipe 2a and the outer wall of the rotary kiln L are sealed by a rotary joint.

[0066] Since the discharge pipe 2a is fixed to the rotary kiln L, it is also preferable to bend the outlet side to an extent that the copper concentrate naturally slides down inside the discharge pipe 2a. The copper concentrate slides down the space inside the discharge pipe 2a and is stored in a recovery tank 2 for storing roasted copper concentrate. The inner diameter on the outlet side of the rotary kiln L can be narrowed so that the copper concentrate flows out smoothly from the discharge pipe 2a. In particular, by making the outlet of the discharge pipe 2a and the discharge port of the rotary kiln L at the same height, the copper concentrate can be discharged more smoothly.

[0067] The copper concentrate roasted in the treatment space 3 of the rotary kiln L is stored in the recovery tank 2 through the discharge pipe 2a, while the non-oxidizing gas (SO ２ ) can be collected through the gas exhaust pipe 2b. The gas exhaust pipe 2b can be made of, for example, a stainless steel plate or a heat-resistant steel plate.

[0068] As shown in Figure 1, the gas exhaust pipe 2b can be provided so as to branch off from the exhaust pipe 2a. In this case, the gas exhaust pipe 2b is provided at a position higher than the outlet of the exhaust pipe 2a so as not to come into contact with the copper concentrate being discharged. The non-oxidizing gas exhausted from the gas exhaust pipe 2b can be supplied to the liquefaction furnace, where it can be subjected to processing from step 2 onwards.

[0069] The size of the rotary kiln L is not particularly limited and can be designed to an appropriate size depending on the amount of raw material used, etc. It is preferable to design the inner diameter of the rotary kiln to be large enough to allow for ample space. For example, when using 1 ton of copper concentrate, the size of the rotary kiln L can be designed from the following perspectives.

[0070] Sulfur vapor generated by decomposition of CuS from 1 ton of copper concentrate is extracted as S ２ Then, the number of moles of sulfur vapor is 1.08 x 10 ３ moles, the volume of the sulfur vapor at 0°C is 0.0224 m ３ / mol×1.06×10 ３ mol ≒ 24 m ３ At 740°C, the volume is about 3.7 times larger, i.e., about 89 m ３ The volume is

[0071] In addition, As separated from 1 ton of copper concentrate ２ S ３ The mass of As is 1.2 kg. ２ S ３ The volume of the gas at 0°C is 1.2 kg ÷ 245.8 g / mol = 4.88 mol × 0.0224 m ３ / mol ≒0.11m ３ At 740°C, it becomes about 3.7 times larger, so it becomes about 0.41m ３ This becomes:

[0072] That is, when 1 ton of copper concentrate is used, the exhaust volume from rotary kiln L is about 90 m ３ and the heating SO ２ Therefore, the size of the rotary kiln L can be determined taking these gas volumes into consideration.

[0073] The recovered gas contains unreacted copper concentrate fine powder, gangue fine powder, ZnO ２ The roasting rotary kiln L contains fine particles such as iron oxide fine powder and iron oxide fine powder. These fine particles are relatively heavy, so they can be easily dropped and reused by reducing the gas flow rate inside the rotary kiln L. For this reason, it is preferable to increase the inner diameter of the roasting rotary kiln L and reduce the gas flow rate as much as possible.

[0074] Here, T1, T2, ..., T9 indicated by lead lines in Fig. 1 respectively mean the following: T1: rotary joint T2: outer cylinder (rotating) T3: inner cylinder (rotating) T4: heat insulating material T5: SO ２ Gas Emission (As ２ S ３T6: Copper concentrate (without As) T7: Copper concentrate discharge (750±30°C) T8: Spiral protrusions on the inner surface (copper concentrate moves downward and to the left as the inner cylinder rotates) T9: By adjusting the temperature and flow rate of SO2 gas (to control the temperature inside the inner cylinder)

[0075] (Roasted copper concentrate) When the copper concentrate is roasted in step 1, As is extracted from the copper concentrate. ２ S ３ As the gas evaporates, a porous copper concentrate is formed. The porous copper concentrate has improved reactivity. In addition, during the roasting of the copper concentrate, CuFeS ２ CuS decomposes to Cu ２ The sulfur content in the copper concentrate is stabilized by the evaporation of sulfur, which also contributes to the porosity of the concentrate. Furthermore, the roasting process evaporates and removes sulfur from various miscellaneous processing materials, stabilizing the sulfur content in the copper concentrate. This reduces the fluctuation range of the combustion reaction of the copper concentrate in the oxidation smelting furnace, particularly in the flash smelting furnace.

[0076] By evaporating and removing sulfur, oxygen consumption in flash smelting is reduced by approximately 20% compared to conventional methods. Furthermore, if the temperature of the copper concentrate charged is approximately 700°C, the reaction rate is faster than when it is charged at room temperature. Therefore, the oxidation reaction rate in the reaction shaft inside the concentrate burner is faster than in conventional methods, and the amount of unreacted copper concentrate is reduced. As a result, the peroxidized Fe ３ O ４ The amount of reaction between Fe and FeS increases, and Fe ３ O ４ At the same time, the amount of Fe in the slag is expected to decrease. ３ O ４ This reduces the amount of copper, which also contributes to reducing copper loss.

[0077] Also, FeO—SiO ２ The formation of slag becomes faster and the appearance of liquid slag becomes faster, so SO ２ It is expected that the unreacted copper concentrate powder in the solid phase that flows out of the furnace on the gas flow will be more easily captured by the liquid slag, reducing the amount of copper concentrate that flows out of the furnace. This will reduce the amount of deposits in the heat recovery boiler and the amount of fine powder collected by the electrostatic precipitator, thereby easing the work of removing this fine powder.

[0078] In specifying the inventions included in the present disclosure, the components (properties, structures, functions, etc.) described in each embodiment of the present disclosure may be combined in any manner. In other words, the present disclosure includes all subject matter consisting of all combinations of the components that can be combined as described in this specification.

[0079] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0080] Example 1: Arsenic removal treatment was carried out using copper concentrate. The main components (per ton) of the copper concentrate used and the properties of each component are as follows: Main components and contents Cu = 273 kg S = 315 kg Fe = 263 kg SiO ２ = 95 kg Al ２ O ３ =26kg MgO=6kg As ２ S ３ = 1.2 kg Total = 979.2 kg, other trace elements 20.8 kg (Mo 0.18%, Ni 0.007%, Cd 0.004%, Se 0.01%) Properties of substances contained in copper concentrate CuS = 273 kg ÷ 63.5 g / mol × 95.5 g / mol = 411 kg (CuS is converted into Cu at 220°C or higher) ２ It decomposes into S and S, so in copper smelting it becomes Cu ２ (Considering only S) Cu ２ S=273kg÷63.5g / mol÷2×159g / mol=342kg Cu ２ S (cuprous sulfide); melting point 1130°C, density 5.6 g / cm3, molecular weight = 159 Amount of S generated in the decomposition reaction of CuS = 411 kg - 342 kg = 69 kg ÷ 32 g / mol = 2156 mol Melting point of S; 115.2°C, boiling point 444.6°C, ignition point 360°C FeS = 263 kg ÷ 55.8 g / mol × 87.8 g / mol = 41 kg FeS; melting point 1194°C, density 4.89 g / cm ３ , molecular weight=87.8 As ２ S ３ Melting point 310°C, boiling point 707°C, yellow Sb ２ S ３ Melting point 550°C, boiling point 1587°C, gray Bi２ S ３ Melting point: 685°C (decomposes at 685°C), density: 7.7 g / cm ３ , Gray Bi; melting point 271 ° C, boiling point 1560 ° C PbS; melting point 1118 ° C, boiling point 1281 ° C, density 7.60 g / cm ３ , black ZnS; melting point 1718℃, sublimation point 1180℃, white or yellow

[0081] As shown in FIG. 2 , an apparatus including a stainless steel container 50 (inner diameter 80 mm, height 200 mm, thickness 2 mm) was used to process copper concentrate 100. A bottom plate was installed at the bottom of the SUS container 50, and an argon gas storage space was provided below the bottom plate. Numerous holes 51 with a diameter of 30 μm were formed throughout the bottom plate, and these holes 51 served as argon gas inlets. The argon gas flowed from the bottom plate through the gaps between the copper concentrate charged onto it and into an exhaust gas pipe (the "SUS pipe" described below) at the top. The top of the SUS container 50 was sealed with a stainless steel lid, to which an L-shaped bent SUS pipe 56 for argon gas exhaust was attached. Electric heating tape 52 was wrapped around the SUS pipe 56 to maintain the exhausted argon gas at 750°C ± 30°C. A U-shaped fused silica tube 54 was connected to the tip of the SUS tube 56 (the opposite side to the SUS lid), and the fused silica tube 54 was wrapped with an electric heating tape 52 for heating and controlled to 450°C ± 30°C. In this way, the argon gas was cooled from 750°C ± 30°C to 450°C ± 30°C, and the liquid phase As ２ S ３ The argon gas was allowed to escape from the heat-resistant glass tube 55, which was connected to the outlet side of the fused silica tube 54, and was then released into the atmosphere.

[0082] Using the above-mentioned apparatus, copper concentrate was treated according to the following procedure. First, 1 kg of wet copper concentrate was placed in an SUS container and set in the electric furnace 53. Argon gas was introduced into the SUS container, and the SUS container was controlled at 150°C ± 20°C for 3 hours for drying treatment. During the drying treatment, all of the above-mentioned tubes connected to the SUS container were controlled at 150°C ± 20°C. However, no cooling water was introduced into the final heat-resistant glass tube.

[0083] After the drying process, cooling water was added to the heat-resistant glass tube, and the temperature of the SUS container was maintained at 750°C ± 30°C while flowing argon gas for 5 hours (step 1). Meanwhile, the fused silica tube was maintained at 450°C ± 30°C, and the argon gas flowing out of the SUS container passed through the fused silica tube (step 2). The argon gas that had passed through the fused silica tube was passed through the heat-resistant glass tube maintained at 100°C. Finally, while flowing argon gas, the electric furnace and SUS tube were turned off and the container was cooled to room temperature.

[0084] The fused silica tube was cut and the deposit (liquid phase) was analyzed by X-ray diffraction. ２ S ３ On the other hand, the presence of As in the copper concentrate in the SUS container set in the electric furnace was confirmed. ２ S ３ X-ray diffraction was performed to confirm the presence of As ２ S ３ From the above, the presence of As in the copper concentrate was not confirmed. ２ S ３ It was confirmed that the separation of the solvent by evaporation and subsequent recovery could be carried out with high accuracy.

[0085] In this example, although step 3 was not performed, liquid As was placed in a fused silica tube maintained at 450°C ± 30°C. ２ S ３ The presence of As was confirmed, and by rapidly cooling it, vitrified As ２ S ３ It is presumed that this is generated.

Claims

1. A copper concentrate treatment method for removing arsenic from copper concentrate, comprising roasting the copper concentrate in the presence of a non-oxidizing gas at a temperature range of 707°C to 1130°C to remove gaseous As. ２ S ３ Step 1 to obtain As in the gas phase in the step 1 ２ S ３ is liquefied in a temperature range of 445°C or higher and lower than 707°C to obtain liquid As ２ S ３ 2. A method for treating copper concentrate, comprising the steps of:

2. The liquid phase As obtained in step 2 ２ S ３ is rapidly cooled to form a glass. ２ S ３ 2. The method of claim 1, further comprising step 3 of obtaining:

3. The non-oxidizing gas is SO ２ The method for treating copper concentrate according to claim 1 or 2, comprising:

4. The non-oxidizing gas is SO generated during roasting in step 1. ２ 3. A method for treating copper concentrate according to claim 1 or 2, wherein the method comprises:

5. As in the liquid phase ２ S ３ 3. The copper concentrate treatment method according to claim 1, further comprising a step 4 of recovering the non-oxidizing gas after obtaining the above-mentioned non-oxidizing gas, and maintaining the non-oxidizing gas at a temperature in the range of 115.2°C or higher and lower than 360°C to recover liquid-phase S.

6. The method for treating copper concentrate according to claim 5, wherein the liquid-phase sulfur obtained in step 4 is cooled to a temperature range of less than 115.2°C to solidify it, thereby recovering solid-phase sulfur.

7. The above SO ２ and using the recovered copper concentrate in a process for producing sulfuric acid.

8. As vitrified in step 3 ２ S ３ 3. The method for treating copper concentrate according to claim 2, wherein the non-oxidizing gas is recovered and reused in the roasting in step 1.

9. The method for treating copper concentrate according to claim 5, wherein the non-oxidizing gas after the recovery of S is recovered and reused in the roasting in step 1.

10. The method for treating copper concentrate according to claim 6, wherein the non-oxidizing gas after the recovery of the sulfur is recovered and reused in the roasting in step 1.

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